TY  - GEN
A1  - Federici, S.
A1  - Pohl, Martin
A1  - Ruppel, J.
A1  - Telezhinsky, Igor O.
A1  - Hofmann, Werner
A1  - Martinez, M.
A1  - Knapp, J.
T1  - Design concepts for the Cherenkov Telescope Array CTA
BT  - an advanced facility for ground-based high-energy gamma-ray astronomy
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1325 
KW  - ground based gamma ray astronomy
KW  - next generation Cherenkov telescopes
KW  - design concepts
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-430149
SN  - 1866-8372
VL  - 32
IS  - 1325
ER  - 
TY  - JOUR
A1  - Acciari, V. A.
A1  - Aliu, E.
A1  - Arlen, T.
A1  - Aune, T.
A1  - Beilicke, M.
A1  - Benbow, W.
A1  - Bradbury, S. M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cannon, A.
A1  - Cesarini, A.
A1  - Ciupik, L.
A1  - Collins-Hughes, E.
A1  - Cui, W.
A1  - Dickherber, R.
A1  - Duke, C.
A1  - Errando, M.
A1  - Finley, J. P.
A1  - Finnegan, G.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Galante, N.
A1  - Gall, D.
A1  - Gillanders, G. H.
A1  - Godambe, S.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Guenette, R.
A1  - Gyuk, G.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Hughes, J. P.
A1  - Hui, C. M.
A1  - Humensky, T. B.
A1  - Kaaret, P.
A1  - Karlsson, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krawczynski, H.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - LeBohec, S.
A1  - Madhavan, A. S.
A1  - Maier, G.
A1  - Majumdar, P.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Ong, R. A.
A1  - Orr, M.
A1  - Otte, A. N.
A1  - Pandel, D.
A1  - Park, N. H.
A1  - Perkins, J. S.
A1  - Pohl, Martin
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reyes, L. C.
A1  - Reynolds, P. T.
A1  - Roache, E.
A1  - Rose, H. J.
A1  - Saxon, D. B.
A1  - Schroedter, M.
A1  - Sembroski, G. H.
A1  - Senturk, G. Demet
A1  - Slane, P.
A1  - Smith, A. W.
A1  - Tesic, G.
A1  - Theiling, M.
A1  - Thibadeau, S.
A1  - Tsurusaki, K.
A1  - Varlotta, A.
A1  - Vassiliev, V. V.
A1  - Vincent, S.
A1  - Vivier, M.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weekes, T. C.
A1  - Weinstein, A.
A1  - Weisgarber, T.
A1  - Williams, D. A.
A1  - Wood, M.
A1  - Zitzer, B.
T1  - Discovery of OF TeV Gamma-Ray emission from tycho's supernova remnant
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - We report the discovery of TeV gamma-ray emission from the Type Ia supernova remnant (SNR) G120.1+1.4, known as Tycho's SNR. Observations performed in the period 2008-2010 with the VERITAS ground-based gamma-ray observatory reveal weak emission coming from the direction of the remnant, compatible with a point source located at 00(h)25(m)27(s).0, +64 degrees 10'50 '' (J2000). The TeV photon spectrum measured by VERITAS can be described with a power law dN/dE = C(E/3.42 TeV)(-Gamma) with Gamma = 1.95 +/- 0.51(stat) +/- 0.30(sys) and C = (1.55 +/- 0.43(stat) +/- 0.47(sys)) x 10(-14) cm(-2) s(-1) TeV-1. The integral flux above 1 TeV corresponds to similar to 0.9% of the steady Crab Nebula emission above the same energy, making it one of the weakest sources yet detected in TeV gamma rays. We present both leptonic and hadronic models that can describe the data. The lowest magnetic field allowed in these models is similar to 80 mu G, which may be interpreted as evidence for magnetic field amplification.
KW  - gamma rays: general
KW  - ISM: individual objects (G120.1+01.4, Tycho=VER J0025+641)
Y1  - 2011
U6  - https://doi.org/10.1088/2041-8205/730/2/L20
SN  - 2041-8205
VL  - 730
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Aliu, E.
A1  - Arlen, T.
A1  - Aune, T.
A1  - Beilicke, M.
A1  - Benbow, W.
A1  - Boettcher, Markus
A1  - Bouvier, A.
A1  - Bradbury, S. M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Cannon, A.
A1  - Cesarini, A.
A1  - Ciupik, L.
A1  - Collins-Hughes, E.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dickherber, R.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Finley, J. P.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Galante, N.
A1  - Gall, D.
A1  - Gillanders, G. H.
A1  - Godambe, S.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Gyuk, G.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Huan, H.
A1  - Hughes, G.
A1  - Hui, C. M.
A1  - Humensky, T. B.
A1  - Kaaret, P.
A1  - Karlsson, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krawczynski, H.
A1  - Krennrich, F.
A1  - Madhavan, A. S.
A1  - Maier, G.
A1  - Majumdar, P.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Ong, R. A.
A1  - Orr, M.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Perkins, J. S.
A1  - Pichel, A.
A1  - Pohl, Martin
A1  - Prokoph, H.
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reyes, L. C.
A1  - Reynolds, P. T.
A1  - Roache, E.
A1  - Rose, H. J.
A1  - Ruppel, J.
A1  - Saxon, D. B.
A1  - Schroedter, M.
A1  - Sembroski, G. H.
A1  - Skole, C.
A1  - Smith, A. W.
A1  - Staszak, D.
A1  - Tesic, G.
A1  - Theiling, M.
A1  - Thibadeau, S.
A1  - Tsurusaki, K.
A1  - Tyler, J.
A1  - Varlotta, A.
A1  - Vincent, S.
A1  - Vivier, M.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weinstein, A.
A1  - Weisgarber, T.
A1  - Williams, D. A.
T1  - Veritas observations of unusual extragalactic transient swift J164449.3+573451
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - We report on very high energy (>100 GeV) gamma-ray observations of Swift J164449.3+573451, an unusual transient object first detected by the Swift Observatory and later detected by multiple radio, optical, and X-ray observatories. A total exposure of 28 hr was obtained on Swift J164449.3+573451 with the Very Energetic Radiation Imaging Telescope Array System ( VERITAS) during 2011 March 28-April 15. We do not detect the source and place a differential upper limit on the emission at 500 GeV during these observations of 1.4 x 10(-12) erg cm(-2) s(-1) (99% confidence level). We also present time-resolved upper limits and use a flux limit averaged over the X-ray flaring period to constrain various emission scenarios that can accommodate both the radio-through-X-ray emission detected from the source and the lack of detection by VERITAS.
KW  - accretion, accretion disks
KW  - galaxies: active
KW  - gamma rays: galaxies
KW  - radiation mechanisms: non-thermal
Y1  - 2011
U6  - https://doi.org/10.1088/2041-8205/738/2/L30
SN  - 2041-8205
VL  - 738
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Aliu, E.
A1  - Arlen, T.
A1  - Aune, T.
A1  - Beilicke, M.
A1  - Benbow, W.
A1  - Bouvier, A.
A1  - Bradbury, S. M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cannon, A.
A1  - Cesarini, A.
A1  - Christiansen, J. L.
A1  - Ciupik, L.
A1  - Collins-Hughes, E.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dickherber, R.
A1  - Duke, C.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Finley, J. P.
A1  - Finnegan, G.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Galante, N.
A1  - Gall, D.
A1  - Gibbs, K.
A1  - Gillanders, G. H.
A1  - Godambe, S.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Guenette, R.
A1  - Gyuk, G.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Huan, H.
A1  - Hughes, G.
A1  - Hui, C. M.
A1  - Humensky, T. B.
A1  - Imran, A.
A1  - Kaaret, P.
A1  - Karlsson, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krawczynski, H.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Lyutikov, M.
A1  - Madhavan, A. S.
A1  - Maier, G.
A1  - Majumdar, P.
A1  - McArthur, S.
A1  - McCann, A.
A1  - McCutcheon, M.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nunez, P.
A1  - Ong, R. A.
A1  - Orr, M.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Perkins, J. S.
A1  - Pizlo, F.
A1  - Pohl, Martin
A1  - Prokoph, H.
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reyes, L. C.
A1  - Reynolds, P. T.
A1  - Roache, E.
A1  - Rose, H. J.
A1  - Ruppel, J.
A1  - Saxon, D. B.
A1  - Schroedter, M.
A1  - Sembroski, G. H.
A1  - Sentuerk, G. D.
A1  - Smith, A. W.
A1  - Staszak, D.
A1  - Tesic, G.
A1  - Theiling, M.
A1  - Thibadeau, S.
A1  - Tsurusaki, K.
A1  - Tyler, J.
A1  - Varlotta, A.
A1  - Vassiliev, V. V.
A1  - Vincent, S.
A1  - Vivier, M.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weekes, T. C.
A1  - Weinstein, A.
A1  - Weisgarber, T.
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - Detection of pulsed Gamma Rays Above 100 GeV from the Crab Pulsar
JF  - Science
N2  - We report the detection of pulsed gamma rays from the Crab pulsar at energies above 100 giga-electron volts (GeV) with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) array of atmospheric Cherenkov telescopes. The detection cannot be explained on the basis of current pulsar models. The photon spectrum of pulsed emission between 100 mega-electron volts and 400 GeV is described by a broken power law that is statistically preferred over a power law with an exponential cutoff. It is unlikely that the observation can be explained by invoking curvature radiation as the origin of the observed gamma rays above 100 GeV. Our findings require that these gamma rays be produced more than 10 stellar radii from the neutron star.
Y1  - 2011
U6  - https://doi.org/10.1126/science.1208192
SN  - 0036-8075
VL  - 334
IS  - 6052
SP  - 69
EP  - 72
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ackermann, Margit
A1  - Ajello, M.
A1  - Allafort, A. J.
A1  - Baldini, L.
A1  - Ballet, J.
A1  - Barbiellini, G.
A1  - Bastieri, D.
A1  - Belfiore, A.
A1  - Bellazzini, R.
A1  - Berenji, B.
A1  - Blandford, R. D.
A1  - Bloom, E. D.
A1  - Bonamente, E.
A1  - Borgland, A. W.
A1  - Bottacini, E.
A1  - Brigida, M.
A1  - Bruel, P.
A1  - Buehler, R.
A1  - Buson, S.
A1  - Caliandro, G. A.
A1  - Cameron, R. A.
A1  - Caraveo, P. A.
A1  - Casandjian, J. M.
A1  - Cecchi, C.
A1  - Chekhtman, A.
A1  - Cheung, C. C.
A1  - Chiang, J.
A1  - Ciprini, S.
A1  - Claus, R.
A1  - Cohen-Tanugi, J.
A1  - de Angelis, A.
A1  - de Palma, F.
A1  - Dermer, C. D.
A1  - do Couto e Silva, E.
A1  - Drell, P. S.
A1  - Dumora, D.
A1  - Favuzzi, C.
A1  - Fegan, S. J.
A1  - Focke, W. B.
A1  - Fortin, P.
A1  - Fukazawa, Y.
A1  - Fusco, P.
A1  - Gargano, F.
A1  - Germani, S.
A1  - Giglietto, N.
A1  - Giordano, F.
A1  - Giroletti, M.
A1  - Glanzman, T.
A1  - Godfrey, G.
A1  - Grenier, I. A.
A1  - Guillemot, L.
A1  - Guiriec, S.
A1  - Hadasch, D.
A1  - Hanabata, Y.
A1  - Harding, A. K.
A1  - Hayashida, M.
A1  - Hayashi, K.
A1  - Hays, E.
A1  - Johannesson, G.
A1  - Johnson, A. S.
A1  - Kamae, T.
A1  - Katagiri, H.
A1  - Kataoka, J.
A1  - Kerr, M.
A1  - Knoedlseder, J.
A1  - Kuss, M.
A1  - Lande, J.
A1  - Latronico, L.
A1  - Lee, S. -H.
A1  - Longo, F.
A1  - Loparco, F.
A1  - Lott, B.
A1  - Lovellette, M. N.
A1  - Lubrano, P.
A1  - Martin, P.
A1  - Mazziotta, Mario Nicola
A1  - McEnery, J. E.
A1  - Mehault, J.
A1  - Michelson, P. F.
A1  - Mitthumsiri, W.
A1  - Mizuno, T.
A1  - Monte, C.
A1  - Monzani, M. E.
A1  - Morselli, A.
A1  - Moskalenko, I. V.
A1  - Murgia, S.
A1  - Naumann-Godo, M.
A1  - Nolan, P. L.
A1  - Norris, J. P.
A1  - Nuss, E.
A1  - Ohsugi, T.
A1  - Okumura, A.
A1  - Orlando, E.
A1  - Ormes, J. F.
A1  - Ozaki, M.
A1  - Paneque, D.
A1  - Parent, D.
A1  - Pesce-Rollins, M.
A1  - Pierbattista, M.
A1  - Piron, F.
A1  - Pohl, Martin
A1  - Prokhorov, D.
A1  - Raino, S.
A1  - Rando, R.
A1  - Razzano, M.
A1  - Reposeur, T.
A1  - Ritz, S.
A1  - Parkinson, P. M. Saz
A1  - Sgro, C.
A1  - Siskind, E. J.
A1  - Smith, P. D.
A1  - Spinelli, P.
A1  - Strong, A. W.
A1  - Takahashi, H.
A1  - Tanaka, T.
A1  - Thayer, J. G.
A1  - Thayer, J. B.
A1  - Thompson, D. J.
A1  - Tibaldo, L.
A1  - Torres, D. F.
A1  - Tosti, G.
A1  - Tramacere, A.
A1  - Troja, E.
A1  - Uchiyama, Y.
A1  - Vandenbroucke, J.
A1  - Vasileiou, V.
A1  - Vianello, G.
A1  - Vitale, V.
A1  - Waite, A. P.
A1  - Wang, P.
A1  - Winer, B. L.
A1  - Wood, K. S.
A1  - Yang, Z.
A1  - Zimmer, S.
A1  - Bontemps, S.
T1  - A cocoon of freshly accelerated cosmic rays detected by fermi in the cygnus superbubble
JF  - Science
N2  - The origin of Galactic cosmic rays is a century-long puzzle. Indirect evidence points to their acceleration by supernova shockwaves, but we know little of their escape from the shock and their evolution through the turbulent medium surrounding massive stars. Gamma rays can probe their spreading through the ambient gas and radiation fields. The Fermi Large Area Telescope (LAT) has observed the star-forming region of Cygnus X. The 1- to 100-gigaelectronvolt images reveal a 50-parsec-wide cocoon of freshly accelerated cosmic rays that flood the cavities carved by the stellar winds and ionization fronts from young stellar clusters. It provides an example to study the youth of cosmic rays in a superbubble environment before they merge into the older Galactic population.
Y1  - 2011
U6  - https://doi.org/10.1126/science.1210311
SN  - 0036-8075
VL  - 334
IS  - 6059
SP  - 1103
EP  - 1107
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Donges, Jonathan
A1  - Donner, Reik Volker
A1  - Trauth, Martin H.
A1  - Marwan, Norbert
A1  - Schellnhuber, Hans Joachim
A1  - Kurths, Jürgen
T1  - Nonlinear detection of paleoclimate-variability transitions possibly related to human evolution
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - Potential paleoclimatic driving mechanisms acting on human evolution present an open problem of cross-disciplinary scientific interest. The analysis of paleoclimate archives encoding the environmental variability in East Africa during the past 5 Ma has triggered an ongoing debate about possible candidate processes and evolutionary mechanisms. In this work, we apply a nonlinear statistical technique, recurrence network analysis, to three distinct marine records of terrigenous dust flux. Our method enables us to identify three epochs with transitions between qualitatively different types of environmental variability in North and East Africa during the (i) Middle Pliocene (3.35-3.15 Ma B. P.), (ii) Early Pleistocene (2.25-1.6 Ma B. P.), and (iii) Middle Pleistocene (1.1-0.7 Ma B. P.). A deeper examination of these transition periods reveals potential climatic drivers, including (i) large-scale changes in ocean currents due to a spatial shift of the Indonesian throughflow in combination with an intensification of Northern Hemisphere glaciation, (ii) a global reorganization of the atmospheric Walker circulation induced in the tropical Pacific and Indian Ocean, and (iii) shifts in the dominating temporal variability pattern of glacial activity during the Middle Pleistocene, respectively. A reexamination of the available fossil record demonstrates statistically significant coincidences between the detected transition periods and major steps in hominin evolution. This result suggests that the observed shifts between more regular and more erratic environmental variability may have acted as a trigger for rapid change in the development of humankind in Africa.
KW  - African climate
KW  - Plio-Pleistocene
KW  - climate-driven evolution
KW  - dynamical transitions
KW  - nonlinear time series analysis
Y1  - 2011
U6  - https://doi.org/10.1073/pnas.1117052108
SN  - 0027-8424
VL  - 108
IS  - 51
SP  - 20422
EP  - 20427
PB  - National Acad. of Sciences
CY  - Washington
ER  - 
TY  - JOUR
A1  - Delahaye, T.
A1  - Fiasson, A.
A1  - Pohl, Martin
A1  - Salati, P.
T1  - The GeV-TeV Galactic gamma-ray diffuse emission I. Uncertainties in the predictions of the hadronic component
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Context. The Galactic gamma-ray diffuse emission is currently observed in the GeV-TeV energy range with unprecedented accuracy by the Fermi satellite. Understanding this component is crucial because it provides a background to many different signals, such as extragalactic sources or annihilating dark matter. It is timely to reinvestigate how it is calculated and to assess the various uncertainties that are likely to affect the accuracy of the predictions.
 Aims. The Galactic gamma-ray diffuse emission is mostly produced above a few GeV by the interactions of cosmic ray primaries impinging on the interstellar material. The theoretical error on that component is derived by exploring various potential sources of uncertainty. Particular attention is paid to cosmic ray propagation. Nuclear cross sections, the proton and helium fluxes at the Earth's position, the Galactic radial profile of supernova remnants, and the hydrogen distribution can also severely affect the signal.
 Methods. The propagation of cosmic ray species throughout the Galaxy is described in the framework of a semi-analytic two-zone diffusion/convection model. The gamma-ray flux is reliably and quickly determined. This allows conversion of the constraints set by the boron-to-carbon data into a theoretical uncertainty on the diffuse emission. New deconvolutions of the HI and CO sky maps are also used to get the hydrogen distribution within the Galaxy.
 Results. The thickness of the cosmic ray diffusive halo is found to have a significant effect on the Galactic gamma-ray diffuse emission, while the interplay between diffusion and convection has little influence on the signal. The uncertainties related to nuclear cross sections and to the primary cosmic ray fluxes at the Earth are significant. The radial distribution of supernova remnants along the Galactic plane turns out to be a key ingredient. As expected, the predictions are extremely sensitive to the spatial distribution of hydrogen within the Milky Way.
 Conclusions. Most of the sources of uncertainty are likely to be reduced in the near future. The stress should be put (i) on better determination of the thickness of the cosmic ray diffusive halo; and (ii) on refined observations of the radial profile of supernova remnants.
KW  - gamma rays: diffuse background
KW  - cosmic rays
KW  - methods: analytical
KW  - gamma rays: ISM
Y1  - 2011
U6  - https://doi.org/10.1051/0004-6361/201116647
SN  - 0004-6361
VL  - 531
IS  - 4
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Flad, Heinz-Jürgen
A1  - Harutyunyan, Gohar
A1  - Schneider, Reinhold
A1  - Schulze, Bert-Wolfgang
T1  - Explicit Green operators for quantum mechanical Hamiltonians
BT  - I. The hydrogen atom
JF  - Manuscripta mathematica
N2  - We study a new approach to determine the asymptotic behaviour of quantum many-particle systems near coalescence points of particles which interact via singular Coulomb potentials. This problem is of fundamental interest in electronic structure theory in order to establish accurate and efficient models for numerical simulations. Within our approach, coalescence points of particles are treated as embedded geometric singularities in the configuration space of electrons. Based on a general singular pseudo-differential calculus, we provide a recursive scheme for the calculation of the parametrix and corresponding Green operator of a nonrelativistic Hamiltonian. In our singular calculus, the Green operator encodes all the asymptotic information of the eigenfunctions. Explicit calculations and an asymptotic representation for the Green operator of the hydrogen atom and isoelectronic ions are presented.
Y1  - 2011
U6  - https://doi.org/10.1007/s00229-011-0429-x
SN  - 0025-2611
VL  - 135
IS  - 3-4
SP  - 497
EP  - 519
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Blakesley, James C.
A1  - Schubert, Marcel
A1  - Steyrleuthner, Robert
A1  - Chen, Zhihua
A1  - Facchetti, Antonio
A1  - Neher, Dieter
T1  - Time-of-flight measurements and vertical transport in a high electron-mobility polymer
JF  - Applied physics letters
N2  - We investigate charge transport in a high-electron mobility polymer, poly(N, N-bis 2-octyldodecyl-naphthalene-1,4,5,8-bis dicarboximide-2,6-diyl-alt-5,5-2,2-bithiophene) [P(NDI2OD-T2), Polyera ActivInk (TM) N2200]. Time-of-flight measurements reveal electron mobilities approaching those measured in field-effect transistors, the highest ever recorded in a conjugated polymer using this technique. The modest temperature dependence and weak dispersion of the transients indicate low energetic disorder in this material. Steady-state electron-only current measurements reveal a barrier to injection of about 300 meV. We propose that this barrier is located within the P(NDI2OD-T2) film and arises from molecular orientation effects.
Y1  - 2011
U6  - https://doi.org/10.1063/1.3657827
SN  - 0003-6951
VL  - 99
IS  - 18
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Turner, Sarah T.
A1  - Pingel, Patrick
A1  - Steyrleuthner, Robert
A1  - Crossland, Edward J. W.
A1  - Ludwigs, Sabine
A1  - Neher, Dieter
T1  - Quantitative analysis of bulk heterojunction films using linear absorption spectroscopy and solar cell performance
JF  - Advanced functional materials
N2  - A fundamental understanding of the relationship between the bulk morphology and device performance is required for the further development of bulk heterojunction organic solar cells. Here, non-optimized (chloroform cast) and nearly optimized (solvent-annealed o-dichlorobenzene cast) P3HT:PCBM blend films treated over a range of annealing temperatures are studied via optical and photovoltaic device measurements. Parameters related to the P3HT aggregate morphology in the blend are obtained through a recently established analytical model developed by F. C. Spano for the absorption of weakly interacting H-aggregates. Thermally induced changes are related to the glass transition range of the blend. In the chloroform prepared devices, the improvement in device efficiency upon annealing within the glass transition range can be attributed to the growth of P3HT aggregates, an overall increase in the percentage of chain crystallinity, and a concurrent increase in the hole mobilities. Films treated above the glass transition range show an increase in efficiency and fill factor not only associated with the change in chain crystallinity, but also with a decrease in the energetic disorder. On the other hand, the properties of the P3HT phase in the solvent-annealed o-dichlorobenzene cast blends are almost indistinguishable from those of the corresponding pristine P3HT layer and are only weakly affected by thermal annealing. Apparently, slow drying of the blend allows the P3HT chains to crystallize into large domains with low degrees of intra- and interchain disorder. This morphology appears to be most favorable for the efficient generation and extraction of charges.
KW  - Organic electronics
KW  - morphology
KW  - solar cells
KW  - mobility
KW  - absorption spectroscopy
Y1  - 2011
U6  - https://doi.org/10.1002/adfm.201101583
SN  - 1616-301X
VL  - 21
IS  - 24
SP  - 4640
EP  - 4652
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Di Giacomo, Domenico
A1  - Bindi, Dino
A1  - Parolai, Stefano
A1  - Oth, Adrien
T1  - Residual analysis of teleseismic P-wave energy magnitude estimates: inter- and intrastation variability
JF  - Geophysical journal international
N2  - P>Computing the magnitude of an earthquake requires correcting for the propagation effects from the source to the receivers. This is often accomplished by performing numerical simulations using a suitable Earth model. In this work, the energy magnitude M(e) is considered and its determination is performed using theoretical spectral amplitude decay functions over teleseismic distances based on the global Earth model AK135Q. Since the high frequency part (above the corner frequency) of the source spectrum has to be considered in computing M(e), the influence of propagation and site effects may not be negligible and they could bias the single station M(e) estimations. Therefore, in this study we assess the inter- and intrastation distributions of errors by considering the M(e) residuals computed for a large data set of earthquakes recorded at teleseismic distances by seismic stations deployed worldwide. To separate the inter- and intrastation contribution of errors, we apply a maximum likelihood approach to the M(e) residuals. We show that the interstation errors (describing a sort of site effect for a station) are within +/- 0.2 magnitude units for most stations and their spatial distribution reflects the expected lateral variation affecting the velocity and attenuation of the Earth's structure in the uppermost layers, not accounted for by the 1-D AK135Q model. The variance of the intrastation error distribution (describing the record-to-record component of variability) is larger than the interstation one (0.240 against 0.159), and the spatial distribution of the errors is not random but shows specific patterns depending on the source-to-station paths. The set of coefficients empirically determined may be used in the future to account for the heterogeneities of the real Earth not considered in the theoretical calculations of the spectral amplitude decay functions used to correct the recorded data for propagation effects.
KW  - Time series analysis
KW  - Earthquake source observations
KW  - Body waves
KW  - Site effects
KW  - Wave propagation
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-246X.2011.05019.x
SN  - 0956-540X
VL  - 185
IS  - 3
SP  - 1444
EP  - 1454
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Rivera Villarreyes, C. A.
A1  - Baroni, Gabriele
A1  - Oswald, Sascha
T1  - Integral quantification of seasonal soil moisture changes in farmland by cosmic-ray neutrons
JF  - Hydrology and earth system sciences : HESS
N2  - Soil moisture at the plot or hill-slope scale is an important link between local vadose zone hydrology and catchment hydrology. However, so far only a few methods are on the way to close this gap between point measurements and remote sensing. One new measurement methodology that could determine integral soil moisture at this scale is the aboveground sensing of cosmic-ray neutrons, more precisely of ground albedo neutrons. The present study performed ground albedo neutron sensing (GANS) at an agricultural field in northern Germany. To test the method it was accompanied by other soil moisture measurements for a summer period with corn crops growing on the field and a later autumn-winter period without crops and a longer period of snow cover. Additionally, meteorological data and aboveground crop biomass were included in the evaluation. Hourly values of ground albedo neutron sensing showed a high statistical variability. Six-hourly values corresponded well with classical soil moisture measurements, after calibration based on one reference dry period and three wet periods of a few days each. Crop biomass seemed to influence the measurements only to minor degree, opposed to snow cover which has a more substantial impact on the measurements. The latter could be quantitatively related to a newly introduced field neutron ratio estimated from neutron counting rates of two energy ranges. Overall, our study outlines a procedure to apply the ground albedo neutron sensing method based on devices now commercially available, without the need for accompanying numerical simulations and suited for longer monitoring periods after initial calibration.
Y1  - 2011
U6  - https://doi.org/10.5194/hess-15-3843-2011
SN  - 1027-5606
VL  - 15
IS  - 12
SP  - 3843
EP  - 3859
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Balcke, Gerd U.
A1  - Hahn, M.
A1  - Oswald, Sascha
T1  - Nitrogen as an indicator of mass transfer during in-situ gas sparging
JF  - Journal of contaminant hydrology
N2  - Aiming at the stimulation of intrinsic microbial activity, pulses of pure oxygen or pressurized air were recurrently injected into groundwater polluted with chlorobenzene. To achieve well-controlled conditions and intensive sampling, a large, vertical underground tank was filled with the local unconfined sandy aquifer material. In the course of two individual gas injections, one using pure oxygen and one using pressurized air, the mass transfer of individual gas species between trapped gas phase and groundwater was studied. Field data on the dissolved gas composition in the groundwater were combined with a kinetic model on gas dissolution and transport in porous media. Phase mass transfer of individual gas components caused a temporary enrichment of nitrogen, and to a lower degree of methane, in trapped gas leading to the formation of excess dissolved nitrogen levels downgradient from the dissolving gas phase. By applying a novel gas sampling method for dissolved gases in groundwater it was shown that dissolved nitrogen can be used as a partitioning tracer to indicate complete gas dissolution in porous media.
KW  - Inter-phase mass transfer
KW  - Groundwater
KW  - Remediation
KW  - Gas sparging
KW  - Nitrogen
KW  - Methane
KW  - Kinetics
KW  - Bitterfeld
Y1  - 2011
U6  - https://doi.org/10.1016/j.jconhyd.2011.05.005
SN  - 0169-7722
VL  - 126
IS  - 1-2
SP  - 8
EP  - 18
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - BOOK
A1  - Schedler, Kuno
A1  - Proeller, Isabella
T1  - New Public Management
T3  - UTB ; 2132
N2  - New Public Management hat in den vergangenen Jahren die Ansätze und das Verständnis moderner Verwaltungsführung maßgebend beeinflusst.
Stossrichtungen und Grundanliegen dieses Modells wurden zum Teil in die Führungspraxis übernommen und stellen in vielerlei Hinsicht nach wie vor Entwicklungsziele und Leitlinien für die Steuerung und Führung der öffentlichen Verwaltung dar. NPM soll die öffentliche Verwaltung an geforderte Neuausrichtungen anpassen und effizienter gestalten. Ziele und Gestaltung der öffentlichen Verwaltung unter NPM und die dazu notwendigen Instrumente werden in diesem Lehrbuch umfassend und strukturiert erläutert. Besonderes Augenmerk wird dabei auf die Veränderungslinien und -ansätze für die Verwaltungsführung gelegt.
Y1  - 2011
SN  - 978-3-8252-3638-0
PB  - Haupt Verlag
CY  - Bern
ET  - 5., korrigierte Aufl.
ER  - 
TY  - JOUR
A1  - Hempel, Sabrina
A1  - Koseska, Aneta
A1  - Nikoloski, Zoran
A1  - Kurths, Jürgen
T1  - Unraveling gene regulatory networks from time-resolved gene expression data - a measures comparison study
JF  - BMC bioinformatics
N2  - Background: Inferring regulatory interactions between genes from transcriptomics time-resolved data, yielding reverse engineered gene regulatory networks, is of paramount importance to systems biology and bioinformatics studies. Accurate methods to address this problem can ultimately provide a deeper insight into the complexity, behavior, and functions of the underlying biological systems. However, the large number of interacting genes coupled with short and often noisy time-resolved read-outs of the system renders the reverse engineering a challenging task. Therefore, the development and assessment of methods which are computationally efficient, robust against noise, applicable to short time series data, and preferably capable of reconstructing the directionality of the regulatory interactions remains a pressing research problem with valuable applications.
 Results: Here we perform the largest systematic analysis of a set of similarity measures and scoring schemes within the scope of the relevance network approach which are commonly used for gene regulatory network reconstruction from time series data. In addition, we define and analyze several novel measures and schemes which are particularly suitable for short transcriptomics time series. We also compare the considered 21 measures and 6 scoring schemes according to their ability to correctly reconstruct such networks from short time series data by calculating summary statistics based on the corresponding specificity and sensitivity. Our results demonstrate that rank and symbol based measures have the highest performance in inferring regulatory interactions. In addition, the proposed scoring scheme by asymmetric weighting has shown to be valuable in reducing the number of false positive interactions. On the other hand, Granger causality as well as information-theoretic measures, frequently used in inference of regulatory networks, show low performance on the short time series analyzed in this study.
 Conclusions: Our study is intended to serve as a guide for choosing a particular combination of similarity measures and scoring schemes suitable for reconstruction of gene regulatory networks from short time series data. We show that further improvement of algorithms for reverse engineering can be obtained if one considers measures that are rooted in the study of symbolic dynamics or ranks, in contrast to the application of common similarity measures which do not consider the temporal character of the employed data. Moreover, we establish that the asymmetric weighting scoring scheme together with symbol based measures (for low noise level) and rank based measures (for high noise level) are the most suitable choices.
Y1  - 2011
U6  - https://doi.org/10.1186/1471-2105-12-292
SN  - 1471-2105
VL  - 12
IS  - 1
PB  - BioMed Central
CY  - London
ER  - 
TY  - JOUR
A1  - Ruprecht, Colin
A1  - Mutwil, Marek
A1  - Saxe, Friederike
A1  - Eder, Michaela
A1  - Nikoloski, Zoran
A1  - Persson, Staffan
T1  - Large-scale co-expression approach to dissect secondary cell wall formation across plant species
JF  - Frontiers in plant science
N2  - Plant cell walls are complex composites largely consisting of carbohydrate-based polymers, and are generally divided into primary and secondary walls based on content and characteristics. Cellulose microfibrils constitute a major component of both primary and secondary cell walls and are synthesized at the plasma membrane by cellulose synthase (CESA) complexes. Several studies in Arabidopsis have demonstrated the power of co-expression analyses to identify new genes associated with secondary wall cellulose biosynthesis. However, across-species comparative co-expression analyses remain largely unexplored. Here, we compared co-expressed gene vicinity networks of primary and secondary wall CESAsin Arabidopsis, barley, rice, poplar, soybean, Medicago, and wheat, and identified gene families that are consistently co-regulated with cellulose biosynthesis. In addition to the expected polysaccharide acting enzymes, we also found many gene families associated with cytoskeleton, signaling, transcriptional regulation, oxidation, and protein degradation. Based on these analyses, we selected and biochemically analyzed T-DNA insertion lines corresponding to approximately twenty genes from gene families that re-occur in the co-expressed gene vicinity networks of secondary wall CESAs across the seven species. We developed a statistical pipeline using principal component analysis and optimal clustering based on silhouette width to analyze sugar profiles. One of the mutants, corresponding to a pinoresinol reductase gene, displayed disturbed xylem morphology and held lower levels of lignin molecules. We propose that this type of large-scale co-expression approach, coupled with statistical analysis of the cell wall contents, will be useful to facilitate rapid knowledge transfer across plant species.
KW  - secondary cell wall
KW  - comparative co-expression analysis
KW  - Arabidopsis
KW  - cellulose
Y1  - 2011
U6  - https://doi.org/10.3389/fpls.2011.00023
SN  - 1664-462X
VL  - 2
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Basler, Georg
A1  - Ebenhoeh, Oliver
A1  - Selbig, Joachim
A1  - Nikoloski, Zoran
T1  - Mass-balanced randomization of metabolic networks
JF  - Bioinformatics
N2  - Motivation: Network-centered studies in systems biology attempt to integrate the topological properties of biological networks with experimental data in order to make predictions and posit hypotheses. For any topology-based prediction, it is necessary to first assess the significance of the analyzed property in a biologically meaningful context. Therefore, devising network null models, carefully tailored to the topological and biochemical constraints imposed on the network, remains an important computational problem.
 Results: We first review the shortcomings of the existing generic sampling scheme-switch randomization-and explain its unsuitability for application to metabolic networks. We then devise a novel polynomial-time algorithm for randomizing metabolic networks under the (bio)chemical constraint of mass balance. The tractability of our method follows from the concept of mass equivalence classes, defined on the representation of compounds in the vector space over chemical elements. We finally demonstrate the uniformity of the proposed method on seven genome-scale metabolic networks, and empirically validate the theoretical findings. The proposed method allows a biologically meaningful estimation of significance for metabolic network properties.
Y1  - 2011
U6  - https://doi.org/10.1093/bioinformatics/btr145
SN  - 1367-4803
VL  - 27
IS  - 10
SP  - 1397
EP  - 1403
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Grimbs, Sergio
A1  - Arnold, Anne
A1  - Koseska, Aneta
A1  - Kurths, Jürgen
A1  - Selbig, Joachim
A1  - Nikoloski, Zoran
T1  - Spatiotemporal dynamics of the Calvin cycle multistationarity and symmetry breaking instabilities
JF  - Biosystems : journal of biological and information processing sciences
N2  - The possibility of controlling the Calvin cycle has paramount implications for increasing the production of biomass. Multistationarity, as a dynamical feature of systems, is the first obvious candidate whose control could find biotechnological applications. Here we set out to resolve the debate on the multistationarity of the Calvin cycle. Unlike the existing simulation-based studies, our approach is based on a sound mathematical framework, chemical reaction network theory and algebraic geometry, which results in provable results for the investigated model of the Calvin cycle in which we embed a hierarchy of realistic kinetic laws. Our theoretical findings demonstrate that there is a possibility for multistationarity resulting from two sources, homogeneous and inhomogeneous instabilities, which partially settle the debate on multistability of the Calvin cycle. In addition, our tractable analytical treatment of the bifurcation parameters can be employed in the design of validation experiments.
KW  - Multistationarity
KW  - Calvin cycle
KW  - Algebraic geometry
KW  - Bifurcation parameters
KW  - Biomass
Y1  - 2011
U6  - https://doi.org/10.1016/j.biosystems.2010.10.015
SN  - 0303-2647
VL  - 103
IS  - 2
SP  - 212
EP  - 223
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Nikoloski, Zoran
A1  - Grimbs, Sergio
A1  - Klie, Sebastian
A1  - Selbig, Joachim
T1  - Complexity of automated gene annotation
JF  - Biosystems : journal of biological and information processing sciences
N2  - Integration of high-throughput data with functional annotation by graph-theoretic methods has been postulated as promising way to unravel the function of unannotated genes. Here, we first review the existing graph-theoretic approaches for automated gene function annotation and classify them into two categories with respect to their relation to two instances of transductive learning on networks - with dynamic costs and with constant costs - depending on whether or not ontological relationship between functional terms is employed. The determined categories allow to characterize the computational complexity of the existing approaches and establish the relation to classical graph-theoretic problems, such as bisection and multiway cut. In addition, our results point out that the ontological form of the structured functional knowledge does not lower the complexity of the transductive learning with dynamic costs - one of the key problems in modern systems biology. The NP-hardness of automated gene annotation renders the development of heuristic or approximation algorithms a priority for additional research.
KW  - Complexity
KW  - Gene function prediction
KW  - External structural measures
KW  - Transductive learning
Y1  - 2011
U6  - https://doi.org/10.1016/j.biosystems.2010.12.003
SN  - 0303-2647
VL  - 104
IS  - 1
SP  - 1
EP  - 8
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Basler, Georg
A1  - Nikoloski, Zoran
T1  - JMassBalance - mass-balanced randomization and analysis of metabolic networks
JF  - Bioinformatics
N2  - Analysis of biological networks requires assessing the statistical significance of network-based predictions by using a realistic null model. However, the existing network null model, switch randomization, is unsuitable for metabolic networks, as it does not include physical constraints and generates unrealistic reactions. We present JMassBalance, a tool for mass-balanced randomization and analysis of metabolic networks. The tool allows efficient generation of large sets of randomized networks under the physical constraint of mass balance. In addition, various structural properties of the original and randomized networks can be calculated, facilitating the identification of the salient properties of metabolic networks with a biologically meaningful null model.
Y1  - 2011
U6  - https://doi.org/10.1093/bioinformatics/btr448
SN  - 1367-4803
VL  - 27
IS  - 19
SP  - 2761
EP  - 2762
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Hempel, Stefan
A1  - Koseska, Aneta
A1  - Kurths, Jürgen
A1  - Nikoloski, Zoran
T1  - Inner composition alignment for inferring directed networks from short time series
JF  - Physical review letters
N2  - Identifying causal links (couplings) is a fundamental problem that facilitates the understanding of emerging structures in complex networks. We propose and analyze inner composition alignment-a novel, permutation-based asymmetric association measure to detect regulatory links from very short time series, currently applied to gene expression. The measure can be used to infer the direction of couplings, detect indirect (superfluous) links, and account for autoregulation. Applications to the gene regulatory network of E. coli are presented.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevLett.107.054101
SN  - 0031-9007
VL  - 107
IS  - 5
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - GEN
A1  - Nikoloski, Zoran
A1  - van Dongen, Joost T.
T1  - Modeling alternatives for interpreting the change in oxygen-consumption rates during hypoxic conditions
T2  - New phytologist : international journal of plant science
KW  - hypoxia
KW  - modeling
KW  - regulation
KW  - respiration
KW  - roots
Y1  - 2011
U6  - https://doi.org/10.1111/j.1469-8137.2011.03674.x
SN  - 0028-646X
VL  - 190
IS  - 2
SP  - 273
EP  - 276
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Lisec, Jan
A1  - Römisch-Margl, Lilla
A1  - Nikoloski, Zoran
A1  - Piepho, Hans-Peter
A1  - Giavalisco, Patrick
A1  - Selbig, Joachim
A1  - Gierl, Alfons
A1  - Willmitzer, Lothar
T1  - Corn hybrids display lower metabolite variability and complex metabolite inheritance patterns
JF  - The plant journal
N2  - We conducted a comparative analysis of the root metabolome of six parental maize inbred lines and their 14 corresponding hybrids showing fresh weight heterosis. We demonstrated that the metabolic profiles not only exhibit distinct features for each hybrid line compared with its parental lines, but also separate reciprocal hybrids. Reconstructed metabolic networks, based on robust correlations between metabolic profiles, display a higher network density in most hybrids as compared with the corresponding inbred lines. With respect to metabolite level inheritance, additive, dominant and overdominant patterns are observed with no specific overrepresentation. Despite the observed complexity of the inheritance pattern, for the majority of metabolites the variance observed in all 14 hybrids is lower compared with inbred lines. Deviations of metabolite levels from the average levels of the hybrids correlate negatively with biomass, which could be applied for developing predictors of hybrid performance based on characteristics of metabolite patterns.
KW  - heterosis
KW  - Zea mays
KW  - metabolomics
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-313X.2011.04689.x
SN  - 0960-7412
VL  - 68
IS  - 2
SP  - 326
EP  - 336
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Larhlimi, Abdelhalim
A1  - Blachon, Sylvain
A1  - Selbig, Joachim
A1  - Nikoloski, Zoran
T1  - Robustness of metabolic networks a review of existing definitions
JF  - Biosystems : journal of biological and information processing sciences
N2  - Describing the determinants of robustness of biological systems has become one of the central questions in systems biology. Despite the increasing research efforts, it has proven difficult to arrive at a unifying definition for this important concept. We argue that this is due to the multifaceted nature of the concept of robustness and the possibility to formally capture it at different levels of systemic formalisms (e.g, topology and dynamic behavior). Here we provide a comprehensive review of the existing definitions of robustness pertaining to metabolic networks. As kinetic approaches have been excellently reviewed elsewhere, we focus on definitions of robustness proposed within graph-theoretic and constraint-based formalisms.
KW  - Robustness
KW  - Metabolic networks
KW  - Graph theory
KW  - Constraint-based approaches
Y1  - 2011
U6  - https://doi.org/10.1016/j.biosystems.2011.06.002
SN  - 0303-2647
VL  - 106
IS  - 1
SP  - 1
EP  - 8
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Arnold, Anne
A1  - Nikoloski, Zoran
T1  - A quantitative comparison of Calvin-Benson cycle models
JF  - Trends in plant science
N2  - The Calvin-Benson cycle (CBC) provides the precursors for biomass synthesis necessary for plant growth. The dynamic behavior and yield of the CBC depend on the environmental conditions and regulation of the cellular state. Accurate quantitative models hold the promise of identifying the key determinants of the tightly regulated CBC function and their effects on the responses in future climates. We provide an integrative analysis of the largest compendium of existing models for photosynthetic processes. Based on the proposed ranking, our framework facilitates the discovery of best-performing models with regard to metabolomics data and of candidates for metabolic engineering.
Y1  - 2011
U6  - https://doi.org/10.1016/j.tplants.2011.09.004
SN  - 1360-1385
VL  - 16
IS  - 12
SP  - 676
EP  - 683
PB  - Elsevier
CY  - London
ER  - 
TY  - THES
A1  - Kittner, Madeleine
T1  - Folding and aggregation of amyloid peptides
T1  - Faltung und Aggregation von Amyloidpeptiden
N2  - Aggregation of the Amyloid β (Aβ) peptide to amyloid fibrils is associated with the outbreak of Alzheimer’s disease. Early aggregation intermediates in form of soluble oligomers are of special interest as they are believed to be the major toxic components in the process. These oligomers are of disordered and transient nature. Therefore, their detailed molecular structure is difficult to access experimentally and often remains unknown. In the present work extensive, fully atomistic replica exchange molecular dynamics simulations were performed to study the preaggregated, monomer states and early aggregation intermediates (dimers, trimers) of Aβ(25-35) and Aβ(10-35)-NH2 in aqueous solution. The folding and aggregation of Aβ(25-35) were studied at neutral pH and 293 K. Aβ(25-35) monomers mainly adopt β-hairpin conformations characterized by a β-turn formed by residues G29 and A30, and a β-sheet between residues N27–K28 and I31–I32 in equilibrium with coiled conformations. The β-hairpin conformations served as initial configurations to model spontaneous aggregation of Aβ(25-35). As expected, within the Aβ(25-35) dimer and trimer ensembles many different poorly populated conformations appear. Nevertheless, we were able to distinguish between disordered and fibril-like oligomers. Whereas disordered oligomers are rather compact with few intermolecular hydrogen bonds (HBs), fibril-like oligomers are characterized by the formation of large intermolecular β-sheets. In most of the fibril-like dimers and trimers individual peptides are fully extended forming in- or out-of-register antiparallel β-sheets. A small amount of fibril-like trimers contained V-shaped peptides forming parallel β-sheets. The dimensions of extended and V-shaped oligomers correspond well to the diameters of two distinct morphologies found for Aβ(25-35) fibrils. The transition from disordered to fibril-like Aβ(25-35) dimers is unfavorable but driven by energy. The lower energy of fibril-like dimers arises from favorable intermolecular HBs and other electrostatic interactions which compete with a loss in entropy. Approximately 25 % of the entropic cost correspond to configurational entropy. The rest relates to solvent entropy, presumably caused by hydrophobic and electrostatic effects. In contrast to the transition towards fibril-like dimers the first step of aggregation is driven by entropy. Here, we compared structural and thermodynamic properties of the individual monomer, dimer and trimer ensembles to gain qualitative information about the aggregation process. The β-hairpin conformation observed for monomers is successively dissolved in dimer and trimer ensembles while instead intermolecular β-sheets are formed. As expected upon aggregation the configurational entropy decreases. Additionally, the solvent accessible surface area (SASA), especially the hydrophobic SASA, decreases yielding a favorable solvation free energy which overcompensates the loss in configurational entropy. In summary, the hydrophobic effect, possibly combined with electrostatic effects, yields an increase in solvent entropy which is believed to be one major driving force towards aggregation. Spontaneous folding of the Aβ(10-35)-NH2 monomer was modeled using two force fields, GROMOS96 43a1 and OPLS/AA, and compared to primary NMR data collected at pH 5.6 and 283 K taken from the literature. Unexpectedly, the two force fields yielded significantly different main conformations. Comparison between experimental and calculated nuclear Overhauser effect (NOE) distances is not sufficient to distinguish between the different force fields. Additionally, the comparison with scalar coupling constants suggest that the chosen protonation in both simulations corresponds to a pH lower than in the experiment. Based on this analysis we were unable to determine which force field yields a better description of this system. Dimerization of Aβ(10-35)-NH2 was studied at neutral pH and 300 K. Dimer conformations arrange in many distinct, poorly populated and rather complex alignments or interlocking patterns which are rather stabilized by side chain interactions than by specific intermolecular hydrogen bonds. Similar to Aβ(25-35) dimers, transition towards β-sheet-rich, fibril-like Aβ(10-35) dimers is driven by energy competing with a loss in entropy. Here, transition is mediated by favorable peptide-solvent and solvent-solvent interactions mainly arising from electrostatic interactions.
N2  - Die Aggregation des Amyloid β (Aβ) Peptids zu Amyloidfibrillen wird mit dem Ausbruch der Alzheimer Krankheit in Verbindung gebracht. Die toxische Wirkung auf Zellen wird vor allem den zeitigen Intermediaten in Form von löslichen Oligomeren zugeschrieben. Aufgrund deren ungeordneter und flüchtiger Natur kann die molekulare Struktur solcher zeitigen Oligomere oft experimentell nicht aufgelöst werden. In der vorliegenden Arbeit wurden aufwendige atomistische Replica-Exchange-Molekulardynamik-Simulationen durchgeführt, um die molekulare Struktur von Monomeren und Oligomeren der Fragmente Aβ(25-35) und Aβ(10-35)-NH2 in Wasser zu untersuchen. Die Faltung und Aggregation von Aβ(25-35) wurde bei neutralem pH und 293 K untersucht. Monomere dieses Fragments bilden hauptsächlich β-Haarnadelkonformationen im Gleichgewicht mit Knäulstrukturen. Innerhalb der β-Haarnadelkonformationen bilden die Residuen G29 und A30 einen β-turn, während N27–K28 and I31–I32 ein β-Faltblatt bilden. Diese β-Haarnadelkonformationen bildeten den Ausgangspunkt zur Modellierung spontaner Aggregation. Wie zu erwarten, bilden sich eine Vielzahl verschiedener, gering besetzter Dimer- und Trimerkonformationen. Mit Hilfe einer gröberen Einteilung können diese in ungeordnete und fibrillähnliche Oligomere unterteilt werden. Ungeordnete Oligomere bilden kompakte Strukturen, die nur durch wenige intermolekulare Wasserstoffbrückenbindungen (HBB) stabilisiert sind. Typisch für fibrillähnliche Oligomere ist hingegen die Ausbildung großer intermolekularer β-Faltblätter. In vielen dieser Oligomere finden wir antiparallele, in- oder out-of-register β-Faltblätter gebildet durch vollständig ausgestreckte Peptide. Ein kleiner Teil der fibrillähnlichen Trimere bildet parallele, V-förmige β-Faltblätter. Die Ausdehnungen ausgestreckter und V-förmiger Oligomere entspricht in etwa den Durchmessern von zwei verschiedenen, experimentell gefundenen Fibrillmorphologien für Aβ(25-35). Die Umwandlung von ungeordneten zu fibrillähnlichen Aβ(25-35) Dimeren ist energetisch begünstigt, läuft aber nicht freiwillig ab. Fibrillähnliche Dimere haben eine geringere Energie aufgrund günstiger Peptidwechselwirkungen (HBB, Salzbrücken), welche durch den Verlust an Entropie kompensiert wird. Etwa 25 % entsprechen dem Verlust an Konfigurationsentropie. Der restliche Anteil wird einem Verlust an Lösungsmittelentropie aufgrund von hydrophoben und elektrostatischen Effekten zugesprochen. Im Gegensatz zur Umwandlung in fibrillähnliche Dimere, ist die Assoziation von Monomeren oder Oligomeren entropisch begünstigt. Beim Vergleich thermodynamischer Eigenschaften der Monomer-, Dimer- und Trimersysteme zeigt sich im Verlauf der Aggregation, wie erwartet, eine Abnahme der Konfigurationsentropie. Zusätzlich nimmt die dem Lösungsmittel zugängliche Oberfläche (SASA), insbesondere die hydrophobe SASA, ab. In Verbindung damit beobachten wir eine Abnahme der freien Solvatisierungsenergie, welche den Verlust an Konfigurationsentropie kompensiert. Mit anderen Worten, der hydrophobe Effekt in Kombination mit elektrostatischen Wechselwirkungen führt zu einem Ansteigen der Lösungsmittelentropie und begünstigt damit die Aggegation. Die spontane Faltung des Aβ(10-35)-NH2 Monomers wurde für zwei verschiedene Proteinkraftfelder, GROMOS96 43a1 und OPLS/AA, untersucht und mit primären NMR-Daten aus der Literatur, gemessen bei pH 5.6 und 283 K, verglichen. Beide Kraftfelder generieren unterschiedliche Hauptkonformationen. Der Vergleich zwischen experimentellen und berechneten Kern-Overhauser-Effekt (NOE) Abständen ist nicht ausreichend, um zwischen beiden Kraftfeldern zu unterscheiden. Der Vergleich mit Kopplungskonstanten aus Experiment und Simulation zeigt, dass beide Simulationen einem pH-Wert geringer als 5.6 ensprechen. Basierend auf den bisherigen Ergebnissen können wir nicht entscheiden, welches Kraftfeld eine bessere Beschreibung für dieses System liefert. Die Dimerisierung von Aβ(10-35)-NH2 wurde bei neutralem pH und 300 K untersucht. Wir finden eine Vielzahl verschiedener, gering besetzter Dimerstrukturen, welche eher durch Seitenkettenkontakte als durch spezifische HBB stabilisiert sind. Wie bei den Aβ(25-35) Dimeren, ist die Umwandlung zu β-Faltblattreichen, fibrillähnlichen Aβ(10-35) Dimeren energetisch begünstigt, konkurriert aber mit einem Entropieverlust. Die Umwandlung wird in diesem Fall durch elektrostatische Wechselwirkungen zwischen Peptid und Lösungsmittel und innerhalb des Lösungsmittels bestimmt.
KW  - Amyloid beta
KW  - Proteinaggregation
KW  - Alzheimer
KW  - Molekulardynamik-Simulation
KW  - Thermodynamische Stabilität
KW  - amyloid beta
KW  - protein aggregation
KW  - Alzheimer
KW  - molecular dynamics simulation
KW  - thermodynamic stability
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-53570
ER  - 
TY  - JOUR
A1  - Rivnay, Jonathan
A1  - Steyrleuthner, Robert
A1  - Jimison, Leslie H.
A1  - Casadei, Alberto
A1  - Chen, Zhihua
A1  - Toney, Michael F.
A1  - Facchetti, Antonio
A1  - Neher, Dieter
A1  - Salleo, Alberto
T1  - Drastic control of texture in a high performance n-Type polymeric semiconductor and implications for charge transport
JF  - Macromolecules : a publication of the American Chemical Society
N2  - Control of crystallographic texture from mostly face-on to edge-on is observed for the film morphology of the n-type semicrystalline polymer [N,N-9-bis(2-octyldodecyl)naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diy1]alt-5,59-(2,29-bithiophene)}, P(NDI2OD-T2), when annealing the film to the polymer melting point followed by slow cooling to ambient temperature. A variety of X-ray diffraction analyses, including pole figure construction and Fourier transform peak shape deconvolution, are employed to quantify the texture change, relative degree of crystallinity and lattice order. We find that annealing the polymer film to the melt leads to a shift from 77.5% face-on to 94.6% edge-on lamellar texture as well as to a 2-fold increase in crystallinity and a 40% decrease in intracrystallite cumulative disorder. The texture change results in a significant drop in the electron-only diode current density through the film thickness upon melt annealing while little change is observed in the in-plane transport of bottom gated thin film transistors. This suggests that the texture change is prevalent in the film interior and that either the (bottom) surface structure is different from the interior structure or the intracrystalline order and texture play a secondary role in transistor transport for this material.
Y1  - 2011
U6  - https://doi.org/10.1021/ma200864s
SN  - 0024-9297
VL  - 44
IS  - 13
SP  - 5246
EP  - 5255
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Tschöpe, Okka
A1  - Wallschläger, Hans-Dieter
A1  - Burkart, Michael
A1  - Tielbörger, Katja
T1  - Managing open habitats by wild ungulate browsing and grazing a case-study in North-Eastern Germany
JF  - Applied vegetation science : official organ of the International Association for Vegetation Science
N2  - Question: Can wild ungulates efficiently maintain and restore open habitats?
 Location: Brandenburg, NE Germany.
 Methods: The effect of wild ungulate grazing and browsing was studied in three successional stages: (1) Corynephorus canescens-dominated grassland; (2) ruderal tall forb vegetation dominated by Tanacetum vulgare; and (3) Pinus sylvestris-pioneer forest. The study was conducted over 3 yr. In each successional stage, six paired 4 m(2)-monitoring plots of permanently grazed versus ungrazed plots were arranged in three random blocks. Removal of grazing was introduced de novo for the study. In each plot, percentage cover of each plant and lichen species and total cover of woody plants was recorded.
 Results: Wild ungulates considerably affected successional pathways and species composition in open habitats but this influence became evident in alteration of abundances of only a few species. Grazing effects differed considerably between successional stages: species richness was higher in grazed versus ungrazed ruderal and pioneer forest plots, but not in the Corynephorus sites. Herbivory affected woody plant cover only in the Pioneer forest sites. Although the study period was too short to observe drastic changes in species richness and woody plant cover, notable changes in species composition were still detected in all successional stages.
 Conclusion: Wild ungulate browsing is a useful tool to inhibit encroachment of woody vegetation and to conserve a species-rich, open landscape.
KW  - Conservation
KW  - Red deer
KW  - Fallow deer
KW  - Succession
KW  - Species richness
KW  - Woody plant
Y1  - 2011
U6  - https://doi.org/10.1111/j.1654-109X.2010.01119.x
SN  - 1402-2001
VL  - 14
IS  - 2
SP  - 200
EP  - 209
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Donges, Jonathan
A1  - Donner, Reik Volker
A1  - Rehfeld, Kira
A1  - Marwan, Norbert
A1  - Trauth, Martin H.
A1  - Kurths, Jürgen
T1  - Identification of dynamical transitions in marine palaeoclimate records by recurrence network analysis
JF  - Nonlinear processes in geophysics
N2  - The analysis of palaeoclimate time series is usually affected by severe methodological problems, resulting primarily from non-equidistant sampling and uncertain age models. As an alternative to existing methods of time series analysis, in this paper we argue that the statistical properties of recurrence networks - a recently developed approach - are promising candidates for characterising the system's nonlinear dynamics and quantifying structural changes in its reconstructed phase space as time evolves. In a first order approximation, the results of recurrence network analysis are invariant to changes in the age model and are not directly affected by non-equidistant sampling of the data. Specifically, we investigate the behaviour of recurrence network measures for both paradigmatic model systems with non-stationary parameters and four marine records of long-term palaeoclimate variations. We show that the obtained results are qualitatively robust under changes of the relevant parameters of our method, including detrending, size of the running window used for analysis, and embedding delay. We demonstrate that recurrence network analysis is able to detect relevant regime shifts in synthetic data as well as in problematic geoscientific time series. This suggests its application as a general exploratory tool of time series analysis complementing existing methods.
Y1  - 2011
U6  - https://doi.org/10.5194/npg-18-545-2011
SN  - 1023-5809
VL  - 18
IS  - 5
SP  - 545
EP  - 562
PB  - Copernicus
CY  - Göttingen
ER  - 
TY  - JOUR
A1  - Ilnytskyi, Jaroslav M.
A1  - Neher, Dieter
A1  - Saphiannikova, Marina
T1  - Opposite photo-induced deformations in azobenzene-containing polymers with different molecular architecture molecular dynamics study
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - Photo-induced deformations in azobenzene-containing polymers (azo-polymers) are central to a number of applications, such as optical storage and fabrication of diffractive elements. The microscopic nature of the underlying opto-mechanical coupling is yet not clear. In this study, we address the experimental finding that the scenario of the effects depends on molecular architecture of the used azo-polymer. Typically, opposite deformations in respect to the direction of light polarization are observed for liquid crystalline and amorphous azo-polymers. In this study, we undertake molecular dynamics simulations of two different models that mimic these two types of azo-polymers. We employ hybrid force field modeling and consider only trans-isomers of azobenzene, represented as Gay-Berne sites. The effect of illumination on the orientation of the chromophores is considered on the level of orientational hole burning and emphasis is given to the resulting deformation of the polymer matrix. We reproduce deformations of opposite sign for the two models being considered here and discuss the relevant microscopic mechanisms in both cases.
KW  - amorphous state
KW  - light polarisation
KW  - liquid crystal polymers
KW  - molecular dynamics method
KW  - optical hole burning
KW  - photochemistry
Y1  - 2011
U6  - https://doi.org/10.1063/1.3614499
SN  - 0021-9606
VL  - 135
IS  - 4
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Kniepert, Juliane
A1  - Schubert, Marcel
A1  - Blakesley, James C.
A1  - Neher, Dieter
T1  - Photogeneration and recombination in P3HT/PCBM solar cells probed by time-delayed collection field experiments
JF  - The journal of physical chemistry letters
N2  - Time-delayed collection field (TDCF) experiments are performed on bulk heterojunction solar cells comprised of a blend of poly(3-hexylthiophene) and [6,6]-phenyl C-71 butyric acid methyl ester. TDCF is analogous to a pump-probe experiment using optical excitation and an electrical probe with a resolution of < 100 ns. The number of free charge carriers extracted after a short delay is found to be independent of the electric field during illumination. Also, experiments performed with a variable delay between the optical excitation and the electrical probe do not reveal any evidence for the generation of charge via field-assisted dissociation of bound long-lived polaron pairs. Photocurrent transients are well fitted by computational drift diffusion simulations with only direct generation of free charge carriers. With increasing delay times between pump and probe, two loss mechanisms are identified; first, charge-carriers are swept out of the device by the internal electric field, and second, bimolecular recombination of the remaining carriers takes place with a reduced recombination coefficient.
Y1  - 2011
U6  - https://doi.org/10.1021/jz200155b
SN  - 1948-7185
VL  - 2
IS  - 7
SP  - 700
EP  - 705
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kuehn, Sergei
A1  - Pingel, Patrick
A1  - Breusing, Markus
A1  - Fischer, Thomas
A1  - Stumpe, Joachim
A1  - Neher, Dieter
A1  - Elsaesser, Thomas
T1  - High-Resolution Near-Field Optical Investigation of Crystalline Domains in Oligomeric PQT-12 Thin Films
JF  - Advanced functional materials
N2  - The structure and morphology on different length scales dictate both the electrical and optical properties of organic semiconductor thin films. Using a combination of spectroscopic methods, including scanning near-field optical microscopy, we study the domain structure and packing quality of highly crystalline thin films of oligomeric PQT-12 with 100 nanometer spatial resolution. The pronounced optical anisotropy of these layers measured by polarized light microscopy facilitates the identification of regions with uniform molecular orientation. We find that a hierarchical order on three different length scales exists in these layers, made up of distinct well-ordered dichroic areas at the ten-micrometer-scale, which are sub-divided into domains with different molecular in-plane orientation. These serve as a template for the formation of smaller needle-like crystallites at the layer surface. A high degree of crystalline order is believed to be the cause of the rather high field-effect mobility of these layers of 10(-3) cm 2 V(-1) s(-1), whereas it is limited by the presence of domain boundaries at macroscopic distances.
Y1  - 2011
U6  - https://doi.org/10.1002/adfm.201001978
SN  - 1616-301X
VL  - 21
IS  - 5
SP  - 860
EP  - 868
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Blakesley, James C.
A1  - Neher, Dieter
T1  - Relationship between energetic disorder and open-circuit voltage in bulk heterojunction organic solar cells
JF  - Physical review : B, Condensed matter and materials physics
N2  - We simulate organic bulk heterojunction solar cells. The effects of energetic disorder are incorporated through a Gaussian or exponential model of density of states. Analytical models of open-circuit voltage (V(OC)) are derived from the splitting of quasi-Fermi potentials. Their predictions are backed up by more complex numerical device simulations including effects such as carrier-density-dependent charge-carrier mobilities. It is predicted that the V(OC) depends on: (1) the donor-acceptor energy gap; (2) charge-carrier recombination rates; (3) illumination intensity; (4) the contact work functions (if not in the pinning regime); and (5) the amount of energetic disorder. A large degree of energetic disorder, or a high density of traps, is found to cause significant reductions in V(OC). This can explain why V(OC) is often less than expected in real devices. Energetic disorder also explains the nonideal temperature and intensity dependence of V(OC) and the superbimolecular recombination rates observed in many real bulk heterojunction solar cells.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevB.84.075210
SN  - 1098-0121
VL  - 84
IS  - 7
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Lange, Ilja
A1  - Blakesley, James C.
A1  - Frisch, Johannes
A1  - Vollmer, Antje
A1  - Koch, Norbert
A1  - Neher, Dieter
T1  - Band bending in conjugated polymer layers
JF  - Physical review letters
N2  - We use the Kelvin probe method to study the energy-level alignment of four conjugated polymers deposited on various electrodes. Band bending is observed in all polymers when the substrate work function exceeds critical values. Through modeling, we show that the band bending is explained by charge transfer from the electrodes into a small density of states that extends several hundred meV into the band gap. The energetic spread of these states is correlated with charge-carrier mobilities, suggesting that the same states also govern charge transport in the bulk of these polymers.
Y1  - 2011
U6  - https://doi.org/10.1103/PhysRevLett.106.216402
SN  - 0031-9007
VL  - 106
IS  - 21
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Hundertmark, Michaela
A1  - Dimova, Rumiana
A1  - Lengefeld, Jan
A1  - Seckler, Robert
A1  - Hincha, Dirk K.
T1  - The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding
JF  - Biochimica et biophysica acta : Biomembranes
N2  - Intrinsically disordered proteins (IDPs) constitute a substantial part of cellular proteomes. late embryogenesis abundant (LEA) proteins are mostly predicted to be IDPs associated with dehydration tolerance in many plant, animal and bacterial species. Their functions, however, are largely unexplored and also their structure and interactions with potential target molecules have only recently been experimentally investigated in a small number of proteins. Here, we report on the structure and interactions with membranes of the Pfam LEA_1 protein LEA18 from the higher plant Arabidopsis thaliana. This functionally uncharacterized positively charged protein specifically aggregated and destabilized negatively charged liposomes. Isothermal titration calorimetry showed binding of the protein to both charged and uncharged membranes. LEA18 alone was largely unstructured in solution. While uncharged membranes had no influence on the secondary structure of LEA18, the protein partially folded into beta-sheet structure in the presence of negatively charged liposomes. These data suggest that LEA18 does not function as a membrane stabilizing protein, as suggested for other LEA proteins. Instead, a possible function of LEA18 could be the composition-dependent modulation of membrane stability, e.g., during signaling or vesicle-mediated transport.
KW  - Intrinsically disordered protein
KW  - Late embryogenesis abundant protein
KW  - Membrane stability
KW  - Protein-membrane interaction
KW  - Protein folding
Y1  - 2011
U6  - https://doi.org/10.1016/j.bbamem.2010.09.010
SN  - 0005-2736
VL  - 1808
IS  - 1
SP  - 446
EP  - 453
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Popova, Antoaneta V.
A1  - Hundertmark, Michaela
A1  - Seckler, Robert
A1  - Hincha, Dirk K.
T1  - Structural transitions in the intrinsically disordered plant dehydration stress protein LEA7 upon drying are modulated by the presence of membranes
JF  - Biochimica et biophysica acta : Biomembranes
N2  - Dehydration stress-related late embryogenesis abundant (LEA) proteins have been found in plants, invertebrates and bacteria. Most LEA proteins are unstructured in solution, but some fold into amphipathic a-helices during drying. The Pfam LEA_4 (Group 3) protein LEA7 from the higher plant Arabidopsis thaliana was predicted to be 87% alpha-helical, while CD spectroscopy showed it to be largely unstructured in solution and only 35% alpha-helical in the dry state. However, the dry protein contained 15% beta-sheets. FTIR spectroscopy revealed the (beta-sheets to be largely due to aggregation. beta-Sheet content was reduced and alpha-helix content increased when LEA7 was dried in the presence of liposomes with secondary structure apparently influenced by lipid composition. Secondary structure was also affected by the presence of membranes in the fully hydrated state. A temperature-induced increase in the flexibility of the dry protein was also only observed in the presence of membranes. Functional interactions of LEA7 with membranes in the dry state were indicated by its influence on the thermotropic phase transitions of the lipids and interactions with the lipid headgroup phosphates.
KW  - Desiccation
KW  - CD spectroscopy
KW  - FTIR spectroscopy
KW  - LEA protein
KW  - Protein-membrane interactions
KW  - Protein secondary structure
Y1  - 2011
U6  - https://doi.org/10.1016/j.bbamem.2011.03.009
SN  - 0005-2736
VL  - 1808
IS  - 7
SP  - 1879
EP  - 1887
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Eichler, David
A1  - Pohl, Martin
T1  - Can ultrahigh-energy cosmic rays come from Gamma-ray bursts? - cosmic rays below the ankle and galactic gamma-ray bursts
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters
N2  - The maximum cosmic-ray energy achievable by acceleration by a relativistic blast wave is derived. It is shown that forward shocks from long gamma-ray bursts (GRBs) in the interstellar medium accelerate protons to large enough energies, and have a sufficient energy budget, to produce the Galactic cosmic-ray component just below the ankle at 4 x 10(18) eV, as per an earlier suggestion. It is further argued that, were extragalactic long GRBs responsible for the component above the ankle as well, the occasional Galactic GRB within the solar circle would contribute more than the observational limits on the outward flux from the solar circle, unless an avoidance scenario, such as intermittency and/or beaming, allows the present-day local flux to be less than 10(-3) of the average. Difficulties with these avoidance scenarios are noted.
KW  - cosmic rays
KW  - galaxies: general
KW  - gamma-ray burst: general
Y1  - 2011
U6  - https://doi.org/10.1088/2041-8205/738/2/L21
SN  - 2041-8205
VL  - 738
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Mizuno, Yosuke
A1  - Pohl, Martin
A1  - Niemiec, Jacek
A1  - Zhang, Bing
A1  - Nishikawa, Ken-Ichi
A1  - Hardee, Philip E.
T1  - Magnetic-field amplification by turbulence in a relativistic shockpropagating through an inhomogeneous medium
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We perform two-dimensional relativistic magnetohydrodynamic simulations of a mildly relativistic shock propagating through an inhomogeneous medium. We show that the postshock region becomes turbulent owing to preshock density inhomogeneity, and the magnetic field is strongly amplified due to the stretching and folding of field lines in the turbulent velocity field. The amplified magnetic field evolves into a filamentary structure in two-dimensional simulations. The magnetic energy spectrum is flatter than the Kolmogorov spectrum and indicates that a so-called small-scale dynamo is occurring in the postshock region. We also find that the amount of magnetic-field amplification depends on the direction of the mean preshock magnetic field, and the timescale of magnetic-field growth depends on the shock strength.
KW  - gamma-ray burst: general
KW  - magnetohydrodynamics (MHD)
KW  - methods: numerical
KW  - relativistic processes
KW  - shock waves
KW  - turbulence
Y1  - 2011
U6  - https://doi.org/10.1088/0004-637X/726/2/62
SN  - 0004-637X
VL  - 726
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Pohl, Martin
A1  - Eichler, David
T1  - Origin of ultra-high-energy galactic cosmic rays the isotropy problem
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We study the propagation of ultra-high-energy cosmic rays (UHECRs) in the Galaxy, concentrating on the energy range below the ankle in the spectrum at 4 EeV. A Monte Carlo method, based on analytical solutions to the time-dependent diffusion problem, is used to account for intermittency by placing sources at random locations. Assuming a source population that scales with baryon mass density or star formation (e.g., long GRB), we derive constraints arising from intermittency and the observational limits on the composition and anisotropy. It is shown that the composition and anisotropy at 10(18) eV are difficult to reproduce and require that either (1) the particle mean free path is much smaller than a gyroradius, implying the escape time is very long, (2) the composition is heavier than suggested by recent Auger data, (3) the ultra-high-energy sub-ankle component is mostly extragalactic, or (4) we are living in a rare lull in the UHECR production, and the current UHECR intensity is far below the Galactic time average. We therefore recommend a strong observational focus on determining the UHECR composition around 10(18) eV.
KW  - cosmic rays
KW  - gamma-ray burst: general
Y1  - 2011
U6  - https://doi.org/10.1088/0004-637X/742/2/114
SN  - 0004-637X
VL  - 742
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Abdo, A. A.
A1  - Ackermann, Margit
A1  - Ajello, M.
A1  - Allafort, A. J.
A1  - Baldini, L.
A1  - Ballet, J.
A1  - Barbiellini, G.
A1  - Baring, M. G.
A1  - Bastieri, D.
A1  - Bellazzini, R.
A1  - Berenji, B.
A1  - Blandford, R. D.
A1  - Bloom, E. D.
A1  - Bonamente, E.
A1  - Borgland, A. W.
A1  - Bouvier, A.
A1  - Brandt, T. J.
A1  - Bregeon, Johan
A1  - Brigida, M.
A1  - Bruel, P.
A1  - Buehler, R.
A1  - Buson, S.
A1  - Caliandro, G. A.
A1  - Cameron, R. A.
A1  - Caraveo, P. A.
A1  - Casandjian, J. M.
A1  - Cecchi, C.
A1  - Chaty, S.
A1  - Chekhtman, A.
A1  - Cheung, C. C.
A1  - Chiang, J.
A1  - Cillis, A. N.
A1  - Ciprini, S.
A1  - Claus, R.
A1  - Cohen-Tanugi, J.
A1  - Conrad, Jan
A1  - Corbel, S.
A1  - Cutini, S.
A1  - de Angelis, A.
A1  - de Palma, F.
A1  - Dermer, C. D.
A1  - Digel, S. W.
A1  - do Couto e Silva, E.
A1  - Drell, P. S.
A1  - Drlica-Wagner, A.
A1  - Dubois, R.
A1  - Dumora, D.
A1  - Favuzzi, C.
A1  - Ferrara, E. C.
A1  - Fortin, P.
A1  - Frailis, M.
A1  - Fukazawa, Y.
A1  - Fukui, Y.
A1  - Funk, S.
A1  - Fusco, P.
A1  - Gargano, F.
A1  - Gasparrini, D.
A1  - Gehrels, N.
A1  - Germani, S.
A1  - Giglietto, N.
A1  - Giordano, F.
A1  - Giroletti, M.
A1  - Glanzman, T.
A1  - Godfrey, G.
A1  - Grenier, I. A.
A1  - Grondin, M. -H.
A1  - Guiriec, S.
A1  - Hadasch, D.
A1  - Hanabata, Y.
A1  - Harding, A. K.
A1  - Hayashida, M.
A1  - Hayashi, K.
A1  - Hays, E.
A1  - Horan, D.
A1  - Jackson, M. S.
A1  - Johannesson, G.
A1  - Johnson, A. S.
A1  - Kamae, T.
A1  - Katagiri, H.
A1  - Kataoka, J.
A1  - Kerr, M.
A1  - Knoedlseder, J.
A1  - Kuss, M.
A1  - Lande, J.
A1  - Latronico, L.
A1  - Lee, S. -H.
A1  - Lemoine-Goumard, M.
A1  - Longo, F.
A1  - Loparco, F.
A1  - Lovellette, M. N.
A1  - Lubrano, P.
A1  - Madejski, G. M.
A1  - Makeev, A.
A1  - Mazziotta, Mario Nicola
A1  - McEnery, J. E.
A1  - Michelson, P. F.
A1  - Mignani, R. P.
A1  - Mitthumsiri, W.
A1  - Mizuno, T.
A1  - Moiseev, A. A.
A1  - Monte, C.
A1  - Monzani, M. E.
A1  - Morselli, A.
A1  - Moskalenko, I. V.
A1  - Murgia, S.
A1  - Naumann-Godo, M.
A1  - Nolan, P. L.
A1  - Norris, J. P.
A1  - Nuss, E.
A1  - Ohsugi, T.
A1  - Okumura, A.
A1  - Orlando, E.
A1  - Ormes, J. F.
A1  - Paneque, D.
A1  - Parent, D.
A1  - Pelassa, V.
A1  - Pesce-Rollins, M.
A1  - Pierbattista, M.
A1  - Piron, F.
A1  - Pohl, Martin
A1  - Porter, T. A.
A1  - Raino, S.
A1  - Rando, R.
A1  - Razzano, M.
A1  - Reimer, O.
A1  - Reposeur, T.
A1  - Ritz, S.
A1  - Romani, R. W.
A1  - Roth, M.
A1  - Sadrozinski, H. F. -W.
A1  - Parkinson, P. M. Saz
A1  - Sgro, C.
A1  - Smith, D. A.
A1  - Smith, P. D.
A1  - Spandre, G.
A1  - Spinelli, P.
A1  - Strickman, M. S.
A1  - Tajima, H.
A1  - Takahashi, H.
A1  - Takahashi, T.
A1  - Tanaka, T.
A1  - Thayer, J. G.
A1  - Thayer, J. B.
A1  - Thompson, D. J.
A1  - Tibaldo, L.
A1  - Tibolla, O.
A1  - Torres, D. F.
A1  - Tosti, G.
A1  - Tramacere, A.
A1  - Troja, E.
A1  - Uchiyama, Y.
A1  - Vandenbroucke, J.
A1  - Vasileiou, V.
A1  - Vianello, G.
A1  - Vilchez, N.
A1  - Vitale, V.
A1  - Waite, A. P.
A1  - Wang, P.
A1  - Winer, B. L.
A1  - Wood, K. S.
A1  - Yamamoto, H.
A1  - Yamazaki, R.
A1  - Yang, Z.
A1  - Ziegler, M.
T1  - Observations of the young supernova remnant RX J1713.7-3946 with the fermi large area telescope
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present observations of the young supernova remnant (SNR) RX J1713.7-3946 with the Fermi Large Area Telescope (LAT). We clearly detect a source positionally coincident with the SNR. The source is extended with a best-fit extension of 0 degrees.55 +/- 0 degrees.04 matching the size of the non-thermal X-ray and TeV gamma-ray emission from the remnant. The positional coincidence and the matching extended emission allow us to identify the LAT source with SNR RX J1713.7-3946. The spectrum of the source can be described by a very hard power law with a photon index of Gamma = 1.5 +/- 0.1 that coincides in normalization with the steeper H. E. S. S.-detected gamma-ray spectrum at higher energies. The broadband gamma-ray emission is consistent with a leptonic origin as the dominant mechanism for the gamma-ray emission.
KW  - acceleration of particles
KW  - gamma rays: general
KW  - gamma rays: ISM
KW  - ISM: individual objects (RX J1713.7-3946)
KW  - ISM: supernova remnants
KW  - radiation mechanisms: non-thermal
Y1  - 2011
U6  - https://doi.org/10.1088/0004-637X/734/1/28
SN  - 0004-637X
VL  - 734
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Acciari, V. A.
A1  - Aliu, E.
A1  - Arlen, T.
A1  - Aune, T.
A1  - Beilicke, M.
A1  - Benbow, W.
A1  - Bradbury, S. M.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Byrum, K.
A1  - Cannon, A.
A1  - Cesarini, A.
A1  - Ciupik, L.
A1  - Collins-Hughes, E.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dickherber, R.
A1  - Duke, C.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Finley, J. P.
A1  - Finnegan, G.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Galante, N.
A1  - Gall, D.
A1  - Gillanders, G. H.
A1  - Godambe, S.
A1  - Griffin, S.
A1  - Grube, J.
A1  - Guenette, R.
A1  - Gyuk, G.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Hui, C. M.
A1  - Humensky, T. B.
A1  - Kaaret, P.
A1  - Karlsson, N.
A1  - Kertzman, M.
A1  - Kieda, D.
A1  - Krawczynski, H.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - LeBohec, S.
A1  - Maier, G.
A1  - Majumdar, P.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Ong, R. A.
A1  - Orr, M.
A1  - Otte, A. N.
A1  - Park, N.
A1  - Perkins, J. S.
A1  - Pohl, Martin
A1  - Prokoph, H.
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reyes, L. C.
A1  - Reynolds, P. T.
A1  - Roache, E.
A1  - Rose, H. J.
A1  - Ruppel, J.
A1  - Saxon, D. B.
A1  - Schroedter, M.
A1  - Sembroski, G. H.
A1  - Senturk, G. D.
A1  - Smith, A. W.
A1  - Staszak, D.
A1  - Tesic, G.
A1  - Theiling, M.
A1  - Thibadeau, S.
A1  - Tsurusaki, K.
A1  - Varlotta, A.
A1  - Vassiliev, V. V.
A1  - Vincent, S.
A1  - Vivier, M.
A1  - Wakely, S. P.
A1  - Ward, J. E.
A1  - Weekes, T. C.
A1  - Weinstein, A.
A1  - Weisgarber, T.
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - VERITAS OBSERVATIONS OF THE TeV BINARY LS I+61 degrees 303 DURING 2008-2010
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present the results of observations of the TeV binary LS I + 61 degrees 303 with the VERITAS telescope array between 2008 and 2010, at energies above 300 GeV. In the past, both ground-based gamma-ray telescopes VERITAS and MAGIC have reported detections of TeV emission near the apastron phases of the binary orbit. The observations presented here show no strong evidence for TeV emission during these orbital phases; however, during observations taken in late 2010, significant emission was detected from the source close to the phase of superior conjunction (much closer to periastron passage) at a 5.6 standard deviation (5.6 sigma) post-trials significance. In total, between 2008 October and 2010 December a total exposure of 64.5 hr was accumulated with VERITAS on LS I + 61 degrees 303, resulting in an excess at the 3.3 sigma significance level for constant emission over the entire integrated data set. The flux upper limits derived for emission during the previously reliably active TeV phases (i.e., close to apastron) are less than 5% of the Crab Nebula flux in the same energy range. This result stands in apparent contrast to previous observations by both MAGIC and VERITAS which detected the source during these phases at 10% of the Crab Nebula flux. During the two year span of observations, a large amount of X-ray data were also accrued on LS I + 61 degrees 303 by the Swift X-ray Telescope and the Rossi X-ray Timing Explorer Proportional Counter Array. We find no evidence for a correlation between emission in the X-ray and TeV regimes during 20 directly overlapping observations. We also comment on data obtained contemporaneously by the Fermi Large Area Telescope.
KW  - binaries: general
KW  - gamma rays: general
KW  - X-rays: binaries
Y1  - 2011
U6  - https://doi.org/10.1088/0004-637X/738/1/3
SN  - 0004-637X
VL  - 738
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - THES
A1  - Wang, Long
T1  - X-tracking the usage interest on web sites
T1  - X-tracking des Nutzungsinteresses für Webseiten
N2  - The exponential expanding of the numbers of web sites and Internet users makes WWW the most important global information resource. From information publishing and electronic commerce to entertainment and social networking, the Web allows an inexpensive and efficient access to the services provided by individuals and institutions. The basic units for distributing these services are the web sites scattered throughout the world. However, the extreme fragility of web services and content, the high competence between similar services supplied by different sites, and the wide geographic distributions of the web users drive the urgent requirement from the web managers to track and understand the usage interest of their web customers. This thesis, "X-tracking the Usage Interest on Web Sites", aims to fulfill this requirement. "X" stands two meanings: one is that the usage interest differs from various web sites, and the other is that usage interest is depicted from multi aspects: internal and external, structural and conceptual, objective and subjective. "Tracking" shows that our concentration is on locating and measuring the differences and changes among usage patterns. This thesis presents the methodologies on discovering usage interest on three kinds of web sites: the public information portal site, e-learning site that provides kinds of streaming lectures and social site that supplies the public discussions on IT issues. On different sites, we concentrate on different issues related with mining usage interest. The educational information portal sites were the first implementation scenarios on discovering usage patterns and optimizing the organization of web services. In such cases, the usage patterns are modeled as frequent page sets, navigation paths, navigation structures or graphs. However, a necessary requirement is to rebuild the individual behaviors from usage history. We give a systematic study on how to rebuild individual behaviors. Besides, this thesis shows a new strategy on building content clusters based on pair browsing retrieved from usage logs. The difference between such clusters and the original web structure displays the distance between the destinations from usage side and the expectations from design side. Moreover, we study the problem on tracking the changes of usage patterns in their life cycles. The changes are described from internal side integrating conceptual and structure features, and from external side for the physical features; and described from local side measuring the difference between two time spans, and global side showing the change tendency along the life cycle. A platform, Web-Cares, is developed to discover the usage interest, to measure the difference between usage interest and site expectation and to track the changes of usage patterns. E-learning site provides the teaching materials such as slides, recorded lecture videos and exercise sheets. We focus on discovering the learning interest on streaming lectures, such as real medias, mp4 and flash clips. Compared to the information portal site, the usage on streaming lectures encapsulates the variables such as viewing time and actions during learning processes. The learning interest is discovered in the form of answering 6 questions, which covers finding the relations between pieces of lectures and the preference among different forms of lectures. We prefer on detecting the changes of learning interest on the same course from different semesters. The differences on the content and structure between two courses leverage the changes on the learning interest. We give an algorithm on measuring the difference on learning interest integrated with similarity comparison between courses. A search engine, TASK-Moniminer, is created to help the teacher query the learning interest on their streaming lectures on tele-TASK site. Social site acts as an online community attracting web users to discuss the common topics and share their interesting information. Compared to the public information portal site and e-learning web site, the rich interactions among users and web content bring the wider range of content quality, on the other hand, provide more possibilities to express and model usage interest. We propose a framework on finding and recommending high reputation articles in a social site. We observed that the reputation is classified into global and local categories; the quality of the articles having high reputation is related with the content features. Based on these observations, our framework is implemented firstly by finding the articles having global or local reputation, and secondly clustering articles based on their content relations, and then the articles are selected and recommended from each cluster based on their reputation ranks.
N2  - Wegen des exponentiellen Ansteigens der Anzahl an Internet-Nutzern und Websites ist das WWW (World Wide Web) die wichtigste globale Informationsressource geworden. Das Web bietet verschiedene Dienste (z. B. Informationsveröffentlichung, Electronic Commerce, Entertainment oder Social Networking) zum kostengünstigen und effizienten erlaubten Zugriff an, die von Einzelpersonen und Institutionen zur Verfügung gestellt werden. Um solche Dienste anzubieten, werden weltweite, vereinzelte Websites als Basiseinheiten definiert. Aber die extreme Fragilität der Web-Services und -inhalte, die hohe Kompetenz zwischen ähnlichen Diensten für verschiedene Sites bzw. die breite geographische Verteilung der Web-Nutzer treiben einen dringenden Bedarf für Web-Manager und das Verfolgen und Verstehen der Nutzungsinteresse ihrer Web-Kunden. Die Arbeit zielt darauf ab, dass die Anforderung "X-tracking the Usage Interest on Web Sites" erfüllt wird. "X" hat zwei Bedeutungen. Die erste Bedeutung ist, dass das Nutzungsinteresse von verschiedenen Websites sich unterscheidet. Außerdem stellt die zweite Bedeutung dar, dass das Nutzungsinteresse durch verschiedene Aspekte (interne und externe, strukturelle und konzeptionelle) beschrieben wird. Tracking zeigt, dass die Änderungen zwischen Nutzungsmustern festgelegt und gemessen werden. Die Arbeit eine Methodologie dar, um das Nutzungsinteresse gekoppelt an drei Arten von Websites (Public Informationsportal-Website, E-Learning-Website und Social-Website) zu finden. Wir konzentrieren uns auf unterschiedliche Themen im Bezug auf verschieden Sites, die mit Usage-Interest-Mining eng verbunden werden. Education Informationsportal-Website ist das erste Implementierungsscenario für Web-Usage-Mining. Durch das Scenario können Nutzungsmuster gefunden und die Organisation von Web-Services optimiert werden. In solchen Fällen wird das Nutzungsmuster als häufige Pagemenge, Navigation-Wege, -Strukturen oder -Graphen modelliert. Eine notwendige Voraussetzung ist jedoch, dass man individuelle Verhaltensmuster aus dem Verlauf der Nutzung (Usage History) wieder aufbauen muss. Deshalb geben wir in dieser Arbeit eine systematische Studie zum Nachempfinden der individuellen Verhaltensweisen. Außerdem zeigt die Arbeit eine neue Strategie, dass auf Page-Paaren basierten Content-Clustering aus Nutzungssite aufgebaut werden. Der Unterschied zwischen solchen Clustern und der originalen Webstruktur ist der Abstand zwischen Zielen der Nutzungssite und Erwartungen der Designsite. Darüber hinaus erforschen wir Probleme beim Tracking der Änderungen von Nutzungsmustern in ihrem Lebenszyklus. Die Änderungen werden durch mehrere Aspekte beschrieben. Für internen Aspekt werden konzeptionelle Strukturen und Funktionen integriert. Der externe Aspekt beschreibt physische Eigenschaften. Für lokalen Aspekt wird die Differenz zwischen zwei Zeitspannen gemessen. Der globale Aspekt zeigt Tendenzen der Änderung entlang des Lebenszyklus. Eine Plattform "Web-Cares" wird entwickelt, die die Nutzungsinteressen findet, Unterschiede zwischen Nutzungsinteresse und Website messen bzw. die Änderungen von Nutzungsmustern verfolgen kann. E-Learning-Websites bieten Lernmaterialien wie z.B. Folien, erfaßte Video-Vorlesungen und Übungsblätter an. Wir konzentrieren uns auf die Erfoschung des Lerninteresses auf Streaming-Vorlesungen z.B. Real-Media, mp4 und Flash-Clips. Im Vergleich zum Informationsportal Website kapselt die Nutzung auf Streaming-Vorlesungen die Variablen wie Schauzeit und Schautätigkeiten während der Lernprozesse. Das Lerninteresse wird erfasst, wenn wir Antworten zu sechs Fragen gehandelt haben. Diese Fragen umfassen verschiedene Themen, wie Erforschung der Relation zwischen Teilen von Lehrveranstaltungen oder die Präferenz zwischen den verschiedenen Formen der Lehrveranstaltungen. Wir bevorzugen die Aufdeckung der Veränderungen des Lerninteresses anhand der gleichen Kurse aus verschiedenen Semestern. Der Differenz auf den Inhalt und die Struktur zwischen zwei Kurse beeinflusst die Änderungen auf das Lerninteresse. Ein Algorithmus misst die Differenz des Lerninteresses im Bezug auf einen Ähnlichkeitsvergleich zwischen den Kursen. Die Suchmaschine „Task-Moniminer“ wird entwickelt, dass die Lehrkräfte das Lerninteresse für ihre Streaming-Vorlesungen über das Videoportal tele-TASK abrufen können. Social Websites dienen als eine Online-Community, in den teilnehmenden Web-Benutzern die gemeinsamen Themen diskutieren und ihre interessanten Informationen miteinander teilen. Im Vergleich zur Public Informationsportal-Website und E-Learning Website bietet diese Art von Website reichhaltige Interaktionen zwischen Benutzern und Inhalten an, die die breitere Auswahl der inhaltlichen Qualität bringen. Allerdings bietet eine Social-Website mehr Möglichkeiten zur Modellierung des Nutzungsinteresses an. Wir schlagen ein Rahmensystem vor, die hohe Reputation für Artikel in eine Social-Website empfiehlt. Unsere Beobachtungen sind, dass die Reputation in globalen und lokalen Kategorien klassifiziert wird. Außerdem wird die Qualität von Artikeln mit hoher Reputation mit den Content-Funktionen in Zusammenhang stehen. Durch die folgenden Schritte wird das Rahmensystem im Bezug auf die Überwachungen implementiert. Der erste Schritt ist, dass man die Artikel mit globalen oder lokalen Reputation findet. Danach werden Artikel im Bezug auf ihre Content-Relationen in jeder Kategorie gesammelt. Zum Schluß werden die ausgewählten Artikel aus jedem basierend auf ihren Reputation-Ranking Cluster empfohlen.
KW  - Tracking
KW  - Nutzungsinteresse
KW  - Webseite
KW  - Tracking
KW  - Usage Interest
KW  - Web Sites
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-51077
ER  - 
TY  - JOUR
A1  - Pollatos, Olga
A1  - Dietel, Anja
A1  - Herbert, Beate M.
A1  - Wankner, Sarah
A1  - Wachsmuth, Cornelia
A1  - Henningsen, Peter
A1  - Sack, Martin
T1  - Blunted autonomic reactivity and increased pain tolerance in somatoform patients
JF  - Pain : journal of the International Association for the Study of Pain
N2  - Somatoform disorders are characterized by the presence of multiple somatic symptoms. Patients often experience different pain syndromes, and recent research suggests that sympathovagal balance is disturbed in somatoform patients, which could be related to alteration in pain sensitivity. This study analyzed how proposed sympathovagal imbalance interacts with objective pain assessment and the imagination of pain in somatoform disorders. Twenty-one patients (4 men) with diagnosed multisomatoform disorder were included in the study and matched to healthy control subjects. Autonomic measures and heart rate variability were assessed during baseline; pain perception was assessed by means of a pressure algometer and pain imagination. We found evidence for a sympathovagal imbalance in somatoform disorders characterized by low parasympathetic activation and high sympathetic activation during all conditions. Additionally, somatoform patients had reduced pain tolerance. Vagal withdrawal during pain assessment was more pronounced for healthy control subjects and correlated positively with assessed pain tolerance. During imagination somatoform, patients reported higher pain unpleasantness and higher pain intensity as compared to control subjects. We conclude that our data demonstrate an imbalance in sympathovagal activation and a hyposensitivity to pain tolerance stimuli in somatoform disorders. Parasympathetic reactivity might form crucial information when judging pain-associated affective-motivational components. Our results might be attributable to a deficient detection of visceral signals and might be a pathogenetic mechanism for the development of emotional difficulties and increased everyday vulnerability in somatoform patients.
KW  - Autonomic
KW  - Heart rate variability
KW  - Pain threshold
KW  - Pain tolerance
KW  - Response
KW  - Somatoform disorder
KW  - Sympathovagal balance
Y1  - 2011
U6  - https://doi.org/10.1016/j.pain.2011.05.024
SN  - 0304-3959
VL  - 152
IS  - 9
SP  - 2157
EP  - 2164
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pollatos, Olga
A1  - Werner, Natalie S.
A1  - Duschek, Stefan
A1  - Schandry, Rainer
A1  - Matthias, Ellen
A1  - Traut-Mattausch, Eva
A1  - Herbert, Beate M.
T1  - Differential effects of alexithymia subscales on autonomic reactivity and anxiety during social stress
JF  - Journal of psychosomatic research
N2  - Objectives: Alexithymia is characterized by a difficulty in identifying and describing one's emotions. Recent research has associated differential effects of the alexithymia facets to hypothalamic pituitary adrenal (HPA) axis markers during stress. This study aimed to analyze how the facets of alexithymia interact with autonomic reactivity as well as self- and observer-rated anxiety during a social stress task. Methods: With the use of a public-speaking paradigm, skin conductance levels (SCLs) and heart rate (HR) during the defined periods of baseline, preparation, stress, and recovery were assessed in 60 volunteers (42 females, mean age 22.8) categorized as having either high (HDA) or low (LDA) degrees of alexithymia. Results: We found smaller SCLs during preparation and speech in the HDA group. Regression analyses indicated that only the alexithymia facet "difficulty in describing feelings" (DDF) was associated with smaller electrodermal responses. In the HDA group, self- and observer-rated anxiety was higher in the HDA than in the LDA group, which was attributable to higher scores in the subscales "difficulty in identifying feelings" (DIF) and "externally oriented thinking" (EOT). Conclusions: Our data support and specify the decoupling hypothesis of alexithymia by showing that the facets of alexithymia are differentially related to autonomic reactivity as well as self- and observer-rated anxiety during social stress.
KW  - Alexithymia
KW  - Autonomic response
KW  - Social stress
KW  - Skin conductance
KW  - Anxiety
KW  - Social performance
KW  - Decoupling hypothesis
Y1  - 2011
U6  - https://doi.org/10.1016/j.jpsychores.2010.12.003
SN  - 0022-3999
VL  - 70
IS  - 6
SP  - 525
EP  - 533
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Pollatos, Olga
A1  - Herbert, Beate M.
A1  - Wankner, Sarah
A1  - Dietel, Anja
A1  - Wachsmuth, Cornelia
A1  - Henningsen, Peter
A1  - Sack, Martin
T1  - Autonomic imbalance is associated with reduced facial recognition in somatoform disorders
JF  - Journal of psychosomatic research
N2  - Objectives: Somatoform disorders are characterized by the presence of multiple somatic symptoms. While the accuracy of perceiving bodily signal (interoceptive awareness) is only sparely investigated in somatoform disorders, recent research has associated autonomic imbalance with cognitive and emotional difficulties in stress-related diseases. This study aimed to investigate how sympathovagal reactivity interacts with performance in recognizing emotions in faces (facial recognition task).
 Methods: Using a facial recognition and appraisal task, skin conductance levels (SCLs), heart rate (HR) and heart rate variability (HRV) were assessed in 26 somatoform patients and compared to healthy controls. Interoceptive awareness was assessed by a heartbeat detection task.
 Results: We found evidence for a sympathovagal imbalance in somatoform disorders characterized by low parasympathetic reactivity during emotional tasks and increased sympathetic activation during baseline. Somatoform patients exhibited a reduced recognition performance for neutral and sad emotional expressions only. Possible confounding variables such as alexithymia, anxiety or depression were taken into account. Interoceptive awareness was reduced in somatoform patients.
 Conclusions: Our data demonstrate an imbalance in sympathovagal activation in somatoform disorders associated with decreased parasympathetic activation. This might account for difficulties in processing of sad and neutral facial expressions in somatoform patients which might be a pathogenic mechanism for increased everyday vulnerability.
KW  - Somatoform disorder
KW  - Interoceptive awareness
KW  - Facial recognition
KW  - Autonomic response
KW  - Heart rate variability
Y1  - 2011
U6  - https://doi.org/10.1016/j.jpsychores.2011.03.012
SN  - 0022-3999
VL  - 71
IS  - 4
SP  - 232
EP  - 239
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Herbert, Beate M.
A1  - Herbert, Cornelia
A1  - Pollatos, Olga
T1  - On the relationship between interoceptive awareness and alexithymia - is interoceptive awareness related to emotional awareness?
JF  - Journal of personality
N2  - Interoceptive awareness (IA) is associated with emotional experience, the processing of emotional stimuli, and activation of brain structures that monitor the internal visceral and emotional state of the organism. Alexithymia is characterized by difficulties in identifying and describing one's emotions and externally oriented thinking (EOT) and reflects impairments in emotional awareness and the regulation of emotions. This study examined the relationship between alexithymia and IA in a healthy population of N = 155 persons. A well-validated heartbeat perception task to measure interoceptive awareness, the Toronto Alexithymia Scale (TAS-20) and a depression questionnaire (BDI-2) were administered to 88 women and 67 men. IA was inversely associated with all features of alexithymia in the whole sample. When considering sex differences, IA turned out to be a relevant negative predictor for the EOT subscale only in men. This large sample investigation in a nonclinical population indicates that IA represents a relevant negative predictor for alexithymia.
Y1  - 2011
U6  - https://doi.org/10.1111/j.1467-6494.2011.00717.x
SN  - 0022-3506
VL  - 79
IS  - 5
SP  - 1149
EP  - 1175
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Pollatos, Olga
A1  - Gramann, Klaus
T1  - Electrophysiological evidence of early processing deficits in alexithymia
JF  - Biological psychology
N2  - Alexithymia describes difficulties to identify and describe one's emotions. Previous research focused on difficulties associated with the later processing stages of appraisal in alexithymia. We tested whether early processing deficits are apparent in alexithymic persons and whether these abnormalities contribute to later processing difficulties. 20 participants were selected and identified as either having high (HDA) or low (LDA) degrees of alexithymia. IAPS pictures were presented while EEG was recorded. For HDA subjects processing of emotional pictures was accompanied by reduced P1 amplitudes most pronounced for pleasant and neutral pictures. In response to unpleasant pictures the P3 amplitudes were reduced. These amplitude modulations were predicted only by one alexithymia facet. P1 amplitudes systematically covaried with P3 amplitudes supporting the assumption that deficits in early emotional processing contribute to later processing deficits.
KW  - Evoked potentials
KW  - Emotions
KW  - Alexithymia
KW  - Perceived arousal
KW  - Unpleasant stimuli
KW  - IAPS
Y1  - 2011
U6  - https://doi.org/10.1016/j.biopsycho.2011.02.016
SN  - 0301-0511
VL  - 87
IS  - 1
SP  - 113
EP  - 121
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - THES
A1  - Wang, Yongbo
T1  - Late glacial to Holocene climate and vegetation changes on the Tibetan Plateau inferred from fossil pollen records in lacustrine sediments
T1  - Pollenanalytische Ableitung der spätglazialen und holozänen Klima- und Vegetationsveränderungen auf dem tibetischen Hochland anhand von Seesedimenten
N2  - The past climate in central Asia, and especially on the Tibetan Plateau (TP), is of great importance for an understanding of global climate processes and for predicting the future climate. As a major influence on the climate in this region, the Asian Summer Monsoon (ASM) and its evolutionary history are of vital importance for accurate predictions. However, neither the evolutionary pattern of the summer monsoon nor the driving mechanisms behind it are yet clearly understood. For this research, I first synthesized previously published Late Glacial to Holocene climatic records from monsoonal central Asia in order to extract the general climate signals and the associated summer monsoon intensities. New climate and vegetation sequences were then established using improved quantitative methods, focusing on fossil pollen records recovered from Tibetan lakes and also incorporating new modern datasets. The pollen-vegetation and vegetation-climate relationships on the TP were also evaluated in order to achieve a better understanding of fossil pollen records. The synthesis of previously published moisture-related palaeoclimate records in monsoonal central Asia revealed generally different temporal patterns for the two monsoonal subsystems, i.e. the Indian Summer Monsoon (ISM) and East Asian Summer Monsoon (EASM). The ISM appears to have experienced maximum wet conditions during the early Holocene, while many records from the area affected by the EASM indicate relatively dry conditions at that time, particularly in north-central China where the maximum moisture levels occurred during the middle Holocene. A detailed consideration of possible driving factors affecting the summer monsoon, including summer solar insolation and sea surface temperatures, revealed that the ISM was primarily driven by variations in northern hemisphere solar insolation, and that the EASM may have been constrained by the ISM resulting in asynchronous patterns of evolution for these two subsystems. This hypothesis is further supported by modern monsoon indices estimated using the NCEP/NCAR Reanalysis data from the last 50 years, which indicate a significant negative correlation between the two summer monsoon subsystems. By analogy with the early Holocene, intensification of the ISM during coming decades could lead to increased aridification elsewhere as a result of the asynchronous nature of the monsoon subsystems, as can already be observed in the meteorological data from the last 15 years. A quantitative climate reconstruction using fossil pollen records was achieved through analysis of sediment core recovered from Lake Donggi Cona (in the north-eastern part of the TP) which has been dated back to the Last Glacial Maximum (LGM). A new data-set of modern pollen collected from large lakes in arid to semi-arid regions of central Asia is also presented herein. The concept of "pollen source area" was introduced to modern climate calibration based on pollen from large lakes, and was applied to the fossil pollen sequence from Lake Donggi Cona. Extremely dry conditions were found to have dominated the LGM, and a subsequent gradually increasing trend in moisture during the Late Glacial period was terminated by an abrupt reversion to a dry phase that lasted for about 1000 years and coincided with the first Heinrich Event of the northern Atlantic region. Subsequent periods corresponding to the warm Bølling-Allerød period and the Younger Dryas cold event were followed by moist conditions during the early Holocene, with annual precipitation of up to about 400 mm. A slightly drier trend after 9 cal ka BP was then followed by a second wet phase during the middle Holocene that lasted until 4.5 cal ka BP. Relatively steady conditions with only slight fluctuations then dominated the late Holocene, resulting in the present climatic conditions. In order to investigate the relationship between vegetation and climate, temporal variations in the possible driving factors for vegetation change on the northern TP were examined using a high resolution late Holocene pollen record from Lake Kusai. Moving-window Redundancy Analyses (RDAs) were used to evaluate the correlations between pollen assemblages and individual sedimentary proxies. These analyses have revealed frequent fluctuations in the relative abundances of alpine steppe and alpine desert components, and in particular a decrease in the total vegetation cover at around 1500 cal a BP. The climate was found to have had an important influence on vegetation changes when conditions were relatively wet and stable. However, after the 1500 cal a BP threshold in vegetation cover was crossed the vegetation appears to have been affected more by extreme events such as dust storms or fluvial erosion than by the general climatic trends. In addition, pollen spectra over the last 600 years have been revealed by Procrustes analysis to be significantly different from those recovered from older samples, which is attributed to an increased human impact that resulted in unprecedented changes to the composition of the vegetation. Theoretical models that have been developed and widely applied to the European area (i.e. the Extended R-Value (ERV) model and the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model) have been applied to the high alpine TP ecosystems in order to investigate the pollen-vegetation relationships, as well as for quantitative reconstructions of vegetation abundance. The modern pollen–vegetation relationships for four common pollen species on the TP have been investigated using Poaceae as the reference taxa. The ERV Submodel 2 yielded relatively high PPEs for the steppe and desert taxa (Artemisia Chenopodiaceae), and low PPEs for the Cyperaceae that are characteristic of the alpine Kobresia meadows. The plant abundances on the central and north-eastern TP were quantified by applying these PPEs to four post-Late Glacial fossil pollen sequences. The reconstructed vegetation assemblages for the four pollen sequences always yielded smaller compositional species turnovers than suggested by the pollen spectra, indicating that the strength of the previously-reported vegetation changes may therefore have been overestimated. In summary, the key findings of this thesis are that (a) the two ASM subsystems show asynchronous patterns during both the Holocene and modern time periods, (b) fossil pollen records from large lakes reflect regional signals for which the pollen source areas need to be taken into account, (c) climate is not always the main driver for vegetation change, and (d) previously reported vegetation changes on the TP may have been overestimated because they ignored inter-species variations in pollen productivity.
N2  - Das Paläoklima in Zentralasien, besonders in der Hochebene von Tibet (HT), ist von großer Bedeutung um globale Klimaprozesse zu verstehen und mögliche Voraussagung für die zukunft zu treffen. Als wichtigstes Klimaphänomen nehmen der asiatische Sommermonsun (ASM) und seine Entwicklungsgeschichte eine Schlüsselposition ein. Dennoch sind derzeit weder das Entwicklungsschema noch der antreibende Vorgang ausreichend verstanden. Dies gilt insbesondere für das Holozän, für welches große Kimaschwankungen und regionale Diskrepanzen weithin belegt sind. Deshalb habe ich zuerst holozäne Klimadaten zusammengefasst. Bereits veröffentlichte Publikationen aus den Monsungebieten Zentralasiens dienten als Grundlage, um die wichtigsten Klimasignale und die zugehörigen Intensitäten des Sommermonsuns heraus zu arbeiten. Anhand von Pollensequenzen aus tibetischen Seen erzeugte ich neue Klima- und Vegetationssequenzen, welche auf verbesserten quantitativen Methoden und rezenten Datensätzen beruhen. Außerdem wurden die Verhältnisse Pollen-Vegetation und Vegetation-Klima bewertet, um Schlussfolgerungen fossiler Pollensequenzen zu verbessern. Die Zusammenfassung der zuvor veröffentlichten, niederschlagsbezogenen Paläoklimadaten im Monsungebiet Zentralasiens ergab generell unterschiedliche Muster für die zwei Teilsysteme des ASMs, den Indischen Sommermonsun (ISM) und den Ostasiatischen Sommermonsun (OASM). Der ISM weist maximale feuchte Bedingungen während des frühen Holozöns auf, während viele Datensätze aus dem Gebiet des OASMs einen relativ trockenen Zustand anzeigen, besonders im nördlichen Zentralchina, wo maximale Niederschläge während des mittleren Holozäns registriert wurden. Genaue Betrachtungen der Antriebsfaktoren des Sommermonsuns ergaben, dass der ISM hauptsächlich durch Veränderungen der Sonneneinstrahlung auf der Nordhemisphäre angetrieben wird, während der OASM potentiell durch den ISM beherrscht wird - dies führt zu asynchronen Entwicklungen. Diese Hypothese wird durch rezente Monsunindizes gestützt. Sie weisen eine signifikant negative Korrelation zwischen den beiden Sommermonsun-Teilsystemen auf. Für die quantitative Klimarekonstruktion von Pollensequenzen wurde ein Sedimentkern aus dem See Donggi Cona im Nordosten der HT analysiert, der bis zum letzten glazialen Maximum (LGM) zurückdatiert wurde. Aufgrund der Tatsache, dass Donggi Cona ein relativ großer See ist, wird hiermit ein neuer Pollen-Klima-Kalibrierungsdatensatz auf Grundlage großer Seen in ariden und semiariden Regionen Zentralasiens vorgelegt. Das Konzept des Pollenherkunftsgebietes wurde in diese rezente, pollenbasierte Klimakalibrierung eingebracht und auf die Pollensequenz von Donggi Cona angewendet. Die Auswertung ergab, dass extrem trockene Bedingungen während des LGM (ca. 100 mm/yr) vorherrschten. Ein ansteigender Trend von Niederschlägen während des späten Glazials wurde durch einen abrupten Rückgang zu einer etwa 1000-jährigen Trockenphase beendet, welche mit Heinrich-Ereignis 1 in der Nordatlantik-Region übereinstimmt. Danach entsprechen die Klimaperioden dem warmen Bølling/Allerød und dem Kälteereignis der Jüngeren Dryas. Anschließend herrschten feuchte Bedingungen im frühen Holozän (bis zu 400 mm/yr). Ein etwas trockenerer Trend nach dem Holozänen Klimaoptimum wurde dann von einer zweiten Feuchtphase abgelöst, welche bis 4,5 cal. ka vor heute andauerte. Relativ gleichmäßige Bedingungen dominierten das späte Holozän bis heute. Die Klimadynamik seit dem LGM wurde vor allem durch Entgletscherung und Intensitätsschwankungen des ASM bestimmt. Bei der Betrachtung des Vegetation-Klima-Verhältnisses habe ich die zeitlichen Variationen der bestimmenden Faktoren hinsichtlich der Vegetationsdynamik auf der nördlichen HT untersucht. Dabei wurden hochauflösende holozäne Pollendaten des Kusai-Sees verwendet. Eine Redundanzanalyse (RDA) wurde angewendet um die Korrelation zwischen Pollenvergesellschaftungen und individuellen sedimentären Klimaanzeigern als auch die damit verbundene Signifikanz zu bewerten. Es stellte sich heraus, dass das Klima einen wichtigen Einfluss auf den Veränderungen in der Vegetation besaß, wenn die Bedingungen relativ warm und feucht waren. Trotzdem scheint es, dass, dass die Vegetation bei zu geringer Bedeckung stärker durch Extremereignisse wie Staubstürme oder fluviale Erosion beeinflusst wurde. Pollenspektren der vergangen 600 Jahre erwiesen sich als signifikant unterschiedlich verglichen mit den älterer Proben, was auf verstärkten anthropogenen Einfluss hindeutet. Dieser resultierte in einem beispiellosen Wandel in der Zusammensetzung der Vegetation. In Hinsicht auf das Pollen-Vegetation-Verhältnis und der quantitativen Rekonstruktion der Vegetationshäufigkeit habe ich theoretische Modelle, welche für europäische Regionen entwickelt und weithin angewendet wurden, respektive die Modelle "Extended R-Value" (ERV) sowie "Regional Estimates of Vegetation Abundance from Large Sites" (REVEALS), auf die hochalpinen Ökosysteme der HT überführt. Dafür wurden rezente Pollen-Vegetations-Verhältnisse von vier weit verbreiteten Pollen-Arten der HT überprüft. Poaceae wurden als Referenztaxa verwendet. Bei der Anwendung dieser Verhältnisse auf vier Pollensequenzen, welche die Paläoumweltbedingungen seit dem letzten Glazial widerspiegeln, wurden die Häufigkeiten von Pflanzen auf der zentralen und nordöstlichen HT quantifiziert. Anteile von Artimisia und Chenopodiaceae waren dabei im Vergleich zu ihren ursprünglichen Pollenprozenten deutlich verringert. Cyperaceae hingegen wies eine relative Zunahme in dieser Vegetationsrekonstruktion auf. Die rekonstruierten Vegetationsvergesellschaftungen an den Standorten der vier Pollensequenzen ergaben stets geringere Umwälzungen in der Artenzusammensetzung, als durch die Pollenspektren zu vermuten gewesen wäre. Dies kann ein Hinweis darauf sein, dass die Intensität der bislang angenommenen Vegetationsveränderungen überschätzt worden ist. Zusammengefasst sind die Hauptresultate dieser Dissertation, dass (a) die zwei ASM Teilsysteme asynchrone Muster während des Holozäns und heute aufweisen, dass (b) fossile Pollensequenzen großer Seen regionale Klimasignale widerspiegeln sofern die Herkunftsgebiete der Pollen berücksichtigt werden, dass (c) Klima nicht immer der Haupteinflussfaktor für Vegetationswandel ist und dass (d) das Ausmaß von Vegetationsveränderungen in zuvor veröffentlichten Studien auf der Hochebene von Tibet überschätzt worden sein kann, weil Diskrepanzen der Pollenproduktivität zwischen den Arten nicht einbezogen wurden.
KW  - Asiatischer Sommermonsun
KW  - ASM
KW  - Holozän
KW  - Seesedimente
KW  - Pollen
KW  - Hochland von Tibet
KW  - Asian Summer Monsoon
KW  - Holocene
KW  - Lake sediments
KW  - Pollen
KW  - Tibetan Plateau
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-63155
ER  - 
TY  - THES
A1  - Wischnewski, Juliane
T1  - Reconstructing climate variability on the Tibetan Plateau : comparing aquatic and terrestrial signals
T1  - Klimarekonstruktionen auf dem Tibet Plateau : aquatische und terrestrische Signale im Vergleich
N2  - Spatial and temporal temperature and moisture patterns across the Tibetan Plateau are very complex. The onset and magnitude of the Holocene climate optimum in the Asian monsoon realm, in particular, is a subject of considerable debate as this time period is often used as an analogue for recent global warming. In the light of contradictory inferences regarding past climate and environmental change on the Tibetan Plateau, I have attempted to explain mismatches in the timing and magnitude of change. Therefore, I analysed the temporal variation of fossil pollen and diatom spectra and the geochemical record from palaeo-ecological records covering different time scales (late Quaternary and the last 200 years) from two core regions in the NE and SE Tibetan Plateau. For interpretation purposes I combined my data with other available palaeo-ecological data to set up corresponding aquatic and terrestrial proxy data sets of two lake pairs and two sets of sites. I focused on the direct comparison of proxies representing lacustrine response to climate signals (e.g., diatoms, ostracods, geochemical record) and proxies representing changes in the terrestrial environment (i.e., terrestrial pollen), in order to asses whether the lake and its catchments respond at similar times and magnitudes to environmental changes. Therefore, I introduced the established numerical technique procrustes rotation as a new approach in palaeoecology to quantitatively compare raw data of any two sedimentary records of interest in order to assess their degree of concordance. Focusing on the late Quaternary, sediment cores from two lakes (Kuhai Lake 35.3°N; 99.2°E; 4150 m asl; and Koucha Lake 34.0°N; 97.2°E; 4540 m asl) on the semi-arid northeastern Tibetan Plateau were analysed to identify post-glacial vegetation and environmental changes, and to investigate the responses of lake ecosystems to such changes. Based on the pollen record, five major vegetation and climate changes could be identified: (1) A shift from alpine desert to alpine steppe indicates a change from cold, dry conditions to warmer and more moist conditions at 14.8 cal. ka BP, (2) alpine steppe with tundra elements points to conditions of higher effective moisture and a stepwise warming climate at 13.6 cal. ka BP, (3) the appearance of high-alpine meadow vegetation indicates a further change towards increased moisture, but with colder temperatures, at 7.0 cal. ka BP, (4) the reoccurrence of alpine steppe with desert elements suggests a return to a significantly colder and drier phase at 6.3 cal. ka BP, and (5) the establishment of alpine steppe-meadow vegetation indicates a change back to relatively moist conditions at 2.2 cal. ka BP. To place the reconstructed climate inferences from the NE Tibetan Plateau into the context of Holocene moisture evolution across the Tibetan Plateau, I applied a five-scale moisture index and average link clustering to all available continuous pollen and non-pollen palaeoclimate records from the Tibetan Plateau, in an attempt to detect coherent regional and temporal patterns of moisture evolution on the Plateau. However, no common temporal or spatial pattern of moisture evolution during the Holocene could be detected, which can be assigned to the complex responses of different proxies to environmental changes in an already very heterogeneous mountain landscape, where minor differences in elevation can result in marked variations in microenvironments. Focusing on the past 200 years, I analysed the sedimentary records (LC6 Lake 29.5°N, 94.3°E, 4132 m asl; and Wuxu Lake 29.9°N, 101.1°E, 3705 m asl) from the southeastern Tibetan Plateau. I found that despite presumed significant temperature increases over that period, pollen and diatom records from the SE Tibetan Plateau reveal only very subtle changes throughout their profiles. The compositional species turnover investigated over the last 200 years appears relatively low in comparison to the species reorganisations during the Holocene. The results indicate that climatically induced ecological thresholds are not yet crossed, but that human activity has an increasing influence, particularly on the terrestrial ecosystem. Forest clearances and reforestation have not caused forest decline in our study area, but a conversion of natural forests to semi-natural secondary forests. The results from the numerical proxy comparison of the two sets of two pairs of Tibetan lakes indicate that the use of different proxies and the work with palaeo-ecological records from different lake types can cause deviant stories of inferred change. Irrespective of the timescale (Holocene or last 200 years) or region (SE or NE Tibetan Plateau) analysed, the agreement in terms of the direction, timing, and magnitude of change between the corresponding terrestrial data sets is generally better than the match between the corresponding lacustrine data sets, suggesting that lacustrine proxies may partly be influenced by in-lake or local catchment processes whereas the terrestrial proxy reflects a more regional climatic signal. The current disaccord on coherent temporal and spatial climate patterns on the Tibetan Plateau can partly be ascribed to the complexity of proxy response and lake systems on the Tibetan Plateau. Therefore, a multi-proxy, multi-site approach is important in order to gain a reliable climate interpretation for the complex mountain landscape of the Tibetan Plateau.
N2  - Die räumlichen und zeitlichen Temperatur- und Feuchtigkeitsmuster auf dem Tibet-Plateau sind sehr komplex. Im Einzugsbereich der asiatischen Monsune sind insbesondere der Beginn und das Ausmaß des Klimaoptimums während des Holozäns von wissenschaftlichem Interesse, da diese Periode oft als Analogie für die derzeitige globale Klimaerwärmung herangezogen wird. In Hinblick auf sich teilweise widersprechende Paläoklima- und Umweltrekonstruktionen für das Tibet-Plateau, ist es mein Ziel, die bestehenden Unstimmigkeiten bezüglich des Zeitpunktes und des Ausmaßes des Umweltwandels zu erklären. Dafür wurden von mir zeitliche Variationen fossiler Pollen- und Diatomeenspektren und geochemische Untersuchungen an Seesedimenten unterschiedlicher Zeitskalen (Spätquartär und die letzten 200 Jahre) aus zwei Kernregionen auf dem NO und SO Tibet-Plateau analysiert. Zur Unterstützung der Interpretation wurden die hier erhobenen Daten mit bereits vorhandenen paläoökologischen Aufzeichnungen der Lokalitäten kombiniert, um Datensätze der entsprechenden aquatischen und terrestrischen Proxy-Daten (Stellvertreterdaten) zweier Seenpaare aus den beiden Regionen gegenüberstellen zu können. Hierbei konzentrierte ich mich auf den direkten Vergleich von Proxies, die die Seenentwicklung reflektieren (z.B. Diatomeen, Ostracoden, geochemische Eigenschaften), mit Proxies, die Veränderungen der terrestrischen Umgebung des Sees beschreiben (terrestrische Pollen). Durch diesen Vergleich lässt sich beurteilen, ob Veränderungen im See selbst mit Umweltveränderungen in dem jeweiligen Einzugsgebiet zeitlich übereinstimmen. Dafür habe ich die bereits etablierte numerische Methode Procrustes-Rotation als neuen Ansatz in der Paläoökologie eingeführt. Damit ist ein quantitativer Vergleich von Rohdaten zweier beliebiger sedimentärer Datensätze möglich, um den Grad der Übereinstimmung zu prüfen. Um die in dieser Arbeit rekonstruierten Umwelt- und Klimaereignisse des nordöstlichen Tibet-Plateaus in einen größeren Zusammenhang hinsichtlich holozäner Klimaentwicklung des gesamten Plateaus setzen zu können, und um schlüssige zeitliche und räumliche Klimatrends auf dem Plateau erkennen zu können, habe ich auf alle vorhandenen Paläoklimadatensätze einen Fünf-Skalen Feuchtigkeitsindex und eine Clusteranalyse angewandt. Es konnten jedoch keine einheitlichen zeitlichen und räumlichen Trends der holozänen Klimaentwicklung nachgewiesen werden, was meiner Analyse entsprechend, auf die komplexen Reaktionen verschiedener Proxies auf Umweltveränderungen in einer ohnehin sehr heterogen Berglandschaft, zurückgeführt werden kann. Die Ergebnisse des numerischen Proxy-Vergleichs beider Seenpaare zeigen, dass die Verwendung von verschiedenen Proxies und die Arbeit mit paläo-ökologischen Datensätzen unterschiedlicher See-Typen zu abweichenden Klimaableitungen führen können. Unabhängig vom untersuchten Zeitraum (Holozän oder die letzten 200 Jahren) oder der Region (SO oder NO Tibet-Plateau), ist die Übereinstimmung zweier Datensätze hinsichtlich der Richtung, des Zeitpunktes und des Ausmaßes der abgeleiteten Paläo-Umweltverhältnisse in der Regel zwischen den entsprechenden terrestrischen Datensätzen besser als zwischen den entsprechenden lakustrinen Datensätzen. Die derzeitige Uneinigkeit über stimmige zeitliche und räumliche Klimatrends auf dem Tibet-Plateau kann daher teilweise der Komplexität der verschieden Proxies und ihrer individuellen Empfindlichkeiten gegenüber Umweltveränderungen sowie der unterschiedlichen Reaktionsweise verschiedenartiger See-Systeme auf dem Plateau zugeschrieben werden. Meine Ergebnisse zeigen, dass ein „Multi-Proxy-Multi-Site-Ansatz“ für zuverlässige Paläoklimaableitungen für das Tibet-Plateau von zentraler Bedeutung ist.
KW  - Tibet Plateau
KW  - Holozän
KW  - Pollen
KW  - Diatomeen
KW  - Prokrustes Analyse
KW  - Tibetan Plateau
KW  - Holocene
KW  - Pollen
KW  - Diatoms
KW  - Procrustes rotation analysis
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-52453
ER  - 
TY  - JOUR
A1  - Kirpichenko, Svetlana V.
A1  - Kleinpeter, Erich
A1  - Ushakov, Igor A.
A1  - Shainyan, Bagrat A.
T1  - Conformational Analysis of 3-Methyl-3-Silathiane and 3-Fluoro-3-Methyl-3-Silathiane
JF  - Journal of physical organic chemistry
N2  - The conformational equilibria of 3-methyl-3-silathiane 5, 3-fluoro-3-methyl-3-silathiane 6 and 1-fluoro-1-methyl-1- silacyclohexane 7 have been studied using low temperature C-13 NMR spectroscopy and theoretical calculations. The conformer ratio at 103 K was measured to be about 5(ax):5(eq) - 15:85, 6(ax):6(eq)-50:50 and 7(ax):7(eq)-25:75. The equatorial preference of the methyl group in 5 (0.35 kcal mol(-1)) is much less than in 3-methylthiane 9 (1.40 kcal mol(-1)) but somewhat greater than in 1-methyl-1-silacyclohexane 1 (0.23 kcal mol(-1)). Compounds 5-7 have low barriers to ring inversion: 5.65 (ax -> eq) and 6.0 kcal mol(-1) (eq -> ax) (5), 4.6 kcal mol(-1) (6), 5.1 kcal mol(-1) (Me-ax -> Me-eq), and 5.4 kcal mol(-1) (Me-eq -> Me-ax) (7). Steric effects cannot explain the observed conformational preferences, like equal population of the two conformers of 6, or different conformer ratio for 5 and 7. Actually, by employing the NBO analysis, in particular, considering the second order perturbation energies, vicinal stereoelectronic interactions between the Si-X and adjacent C-H, C-S, and C-C bonds proved responsible.
KW  - conformational analysis
KW  - low-temperature NMR spectroscopy
KW  - NBO analysis
KW  - quantum chemical calculations
KW  - 3-silathianes
Y1  - 2011
U6  - https://doi.org/10.1002/poc.1758
SN  - 0894-3230
VL  - 24
IS  - 4
SP  - 320
EP  - 326
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Scharhag-Rosenberger, Friederike
A1  - Carlsohn, Anja
A1  - Cassel, Michael
A1  - Mayer, Frank
A1  - Scharhag, Jürgen
T1  - How to test maximal oxygen uptake a study on timing and testing procedure of a supramaximal verification test
JF  - Applied physiology, nutrition, and metabolism = Physiologie appliquée, nutrition et métabolisme
N2  - On utilise de plus en plus les tests de verification pour confirmer l'atteinte du consommation d'oxygene maximale (VO(2 max)). Toutefois, le moment et les methodes d'evaluation varient d'un groupe de travail a l'autre. Les objectifs de cette etude sont de constater si on peut administrer un test de verification apres un test d'effort progressif ou s'il est preferable de le faire une autre journee et si on peut determiner le VO(2 max) tout de meme lors de la premiere seance chez des sujets ne repondant pas au critere de verification. Quarante sujets (age, 24 +/- 4 ans; VO(2 max), 50 +/- 7 mL center dot min(-1)center dot kg(-1)) participent a un test d'effort progressif sur tapis roulant et, 10 min plus tard, a un test de verification (VerifDay1) a 110 % de la velocite maximale (v(max)). Le critere de verification est un VO(2) de pointe au VerifDay1 < 5,5 % a la valeur retenue au test d'effort progressif. Les sujets ne repondant pas au critere de verification passent un autre test de verification, mais a 115 % du VerifDay1', et ce, 10 min plus tard pour confirmer le VO(2) de pointe du VerifDay1 en tant que VO(2 max). Tous les autres sujets repassent le VerifDay1 a un jour different (VerifDay2). Six sujets sur quarante ne repondent pas au critere de verification. Chez quatre d'entre eux, on confirme l'atteinte du VO(2 max) au VerifDay1'. Le VO(2) de pointe au VerifDay1 est equivalent a celui du VerifDay2 (3722 +/- 991 mL center dot min(-1) comparativement a 3752 +/- 995 mL center dot min(-1), p = 0,56), mais le temps jusqu'a l'epuisement est significativement plus long au VerifDay2 (2:06 +/- 0:22 min:s comparativement a 2:42 +/- 0:38 min:s, p < 0,001, n = 34). Le VO(2) de pointe obtenu au test de verification ne semble pas conditionne par un test d'effort progressif maximal prealable. On peut donc realiser le test d'effort progressif et le test de verification lors de la meme seance d'evaluation. Chez presque tous les individus ne repondant pas au critere de verification, on peut determiner le VO(2 max) au moyen d'un autre test de verification plus intense.
Y1  - 2011
U6  - https://doi.org/10.1139/H10-099
SN  - 1715-5312
VL  - 36
IS  - 1
SP  - 153
EP  - 160
PB  - NRC Research Press
CY  - Ottawa
ER  - 
TY  - JOUR
A1  - Kuechly, Helga Ursula
A1  - Mueller, Julia Sophie
A1  - Reinfelder, Vanessa Luisa
A1  - Wiedemann, Stephan
A1  - Blaum, Niels
T1  - Rodent-mediated dispersal of Acacia seeds in Kalahari savannah rangelands - implications for bush encroachment
JF  - African journal of ecology
Y1  - 2011
U6  - https://doi.org/10.1111/j.1365-2028.2010.01230.x
SN  - 0141-6707
VL  - 49
IS  - 1
SP  - 119
EP  - 121
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Johnson, Kim L.
A1  - Lenhard, Michael
T1  - Genetic control of plant organ growth
JF  - New phytologist : international journal of plant science
N2  - The growth of plant organs is under genetic control. Work in model species has identified a considerable number of genes that regulate different aspects of organ growth. This has led to an increasingly detailed knowledge about how the basic cellular processes underlying organ growth are controlled, and which factors determine when proliferation gives way to expansion, with this transition emerging as a critical decision point during primordium growth. Progress has been made in elucidating the genetic basis of allometric growth and the role of tissue polarity in shaping organs. We are also beginning to understand how the mechanisms that determine organ identity influence local growth behaviour to generate organs with characteristic sizes and shapes. Lastly, growth needs to be coordinated at several levels, for example between different cell layers and different regions within one organ, and the genetic basis for such coordination is being elucidated. However, despite these impressive advances, a number of basic questions are still not fully answered, for example, whether and how a growing primordium keeps track of its size. Answering these questions will likely depend on including additional approaches that are gaining in power and popularity, such as combined live imaging and modelling.
KW  - growth coordination
KW  - organ growth
KW  - organ identity
KW  - organ shape
KW  - organ size
Y1  - 2011
U6  - https://doi.org/10.1111/j.1469-8137.2011.03737.x
SN  - 0028-646X
VL  - 191
IS  - 2
SP  - 319
EP  - 333
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Navirian, Hengameh A.
A1  - Herzog, Marc
A1  - Goldshteyn, J.
A1  - Leitenberger, Wolfram
A1  - Vrejoiu, Ionella
A1  - Khakhulin, D.
A1  - Wulff, M.
A1  - Shayduk, Roman
A1  - Gaal, P.
A1  - Bargheer, Matias
T1  - Shortening x-ray pulses for pump-probe experiments at synchrotrons
JF  - Journal of applied physics
N2  - We implemented an experimental scheme for ultrafast x-ray diffraction at storage rings based on a laser-driven Bragg-switch that shortens the x-ray pulses emitted from an undulator. The increased time-resolution is demonstrated by observing changes of intensity, position and width of the diffraction peaks of a La(0.7)Sr(0.3)MnO(3)/SrTiO(3) superlattice sample after optical excitation, i.e., by quantitatively measuring the propagation of an expansion wave through the sample. These experimental transients with timescales of 35 to 60 ps evidence a reduction of the x-ray pulse duration by a factor of two.
Y1  - 2011
U6  - https://doi.org/10.1063/1.3601057
SN  - 0021-8979
VL  - 109
IS  - 12
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Sicard, Adrien
A1  - Stacey, Nicola
A1  - Hermann, Katrin
A1  - Dessoly, Jimmy
A1  - Neuffer, Barbara
A1  - Bäurle, Isabel
A1  - Lenhard, Michael
T1  - Genetics, evolution, and adaptive significance of the selfing syndrome in the genus Capsella
JF  - The plant cell
N2  - The change from outbreeding to selfing is one of the most frequent evolutionary transitions in flowering plants. It is often accompanied by characteristic morphological and functional changes to the flowers (the selfing syndrome), including reduced flower size and opening. Little is known about the developmental and genetic basis of the selfing syndrome, as well as its adaptive significance. Here, we address these issues using the two closely related species Capsella grandiflora (the ancestral outbreeder) and red shepherd's purse (Capsella rubella, the derived selfer). In C. rubella, petal size has been decreased by shortening the period of proliferative growth. Using interspecific recombinant inbred lines, we show that differences in petal size and flower opening between the two species each have a complex genetic basis involving allelic differences at multiple loci. An intraspecific cross within C. rubella suggests that flower size and opening have been decreased in the C. rubella lineage before its extensive geographical spread. Lastly, by generating plants that likely resemble the earliest ancestors of the C. rubella lineage, we provide evidence that evolution of the selfing syndrome was at least partly driven by selection for efficient self-pollination. Thus, our studies pave the way for a molecular dissection of selfing-syndrome evolution.
Y1  - 2011
U6  - https://doi.org/10.1105/tpc.111.088237
SN  - 1040-4651
VL  - 23
IS  - 9
SP  - 3156
EP  - 3171
PB  - American Society of Plant Physiologists
CY  - Rockville
ER  - 
TY  - JOUR
A1  - Kuhn, Daniela
A1  - Ohrnberger, Matthias
A1  - Dahm, Torsten
T1  - Imaging a shallow salt diapir using ambient seismic vibrations beneath the densely built-up city area of Hamburg, Northern Germany
JF  - Journal of seismology
N2  - Salt diapirs are common features of sedimentary basins. If close to the surface, they can bear a significant hazard due to possible dissolution sinkholes, karst formation and collapse dolines or their influence on ground water chemistry. We investigate the potential of ambient vibration techniques to map the 3-D roof morphology of shallow salt diapirs. Horizontal-to-vertical (H/V) spectral peaks are derived at more than 900 positions above a shallow diapir beneath the city area of Hamburg, Germany, and are used to infer the depth of the first strong impedance contrast. In addition, 15 small-scale array measurements are conducted at different positions in order to compute frequency-dependent phase velocities of Rayleigh waves between 0.5 and 25 Hz. The dispersion curves are inverted together with the H/V peak frequency to obtain shear-wave velocity profiles. Additionally, we compare the morphology derived from H/V and array measurements to borehole lithology and a gravity-based 3-D model of the salt diapir. Both methods give consistent results in agreement with major features indicated by the independent data. An important result is that H/V and array measurements are better suited to identify weathered gypsum caprocks or gypsum floaters, while gravity-derived models better sample the interface between sediments and homogeneous salt. We further investigate qualitatively the influence of the 3-D subsurface topography of the salt diapir on the validity of local 1-D inversion results from ambient vibration dispersion curve inversion.
KW  - Ambient seismic vibrations
KW  - H/V method
KW  - Array measurements
KW  - Salt diapir
KW  - 3-D effects
Y1  - 2011
U6  - https://doi.org/10.1007/s10950-011-9234-y
SN  - 1383-4649
VL  - 15
IS  - 3
SP  - 507
EP  - 531
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Hass, Roland
A1  - Reich, Oliver
T1  - Photon density wave spectroscopy for dilution-free sizing of highly concentrated nanoparticles during starved-feed polymerization
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
KW  - analytical methods
KW  - fiber-optical spectroscopy
KW  - nanoparticles
KW  - photon density wave spectroscopy
KW  - polymerization
Y1  - 2011
U6  - https://doi.org/10.1002/cphc.201100323
SN  - 1439-4235
VL  - 12
IS  - 14
SP  - 2572
EP  - 2575
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Stojanovic, Milovan
A1  - Markovic, Rade
A1  - Kleinpeter, Erich
A1  - Baranac-Stojanovic, Marija
T1  - Endo-Mode cyclizations of vinylogous N-acyliminium ions as a route to the synthesis of condensed thiazolidines
JF  - Tetrahedron
N2  - endo-Mode cyclizations of vinylogous N-acyliminium ions incorporating heteroatom-based nucleophiles have been examined as a route to the synthesis of condensed thiazolidines. The scope of these reactions and stereochemical outcome are discussed and explained using quantum chemical calculations.
KW  - Vinylogous N-acyliminium ion
KW  - endo-Mode cyclization
KW  - Condensed thiazolidines
KW  - Quantum chemical calculations
Y1  - 2011
U6  - https://doi.org/10.1016/j.tet.2011.10.011
SN  - 0040-4020
VL  - 67
IS  - 49
SP  - 9541
EP  - 9554
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Pihlaja, Kalevi
A1  - Sinkkonen, Jari
A1  - Stájer, Gezá
A1  - Koch, Andreas
T1  - 1-Oxo-1,3-dithiolanesùsynthesis and stereochemistry
N2  - 1-Oxo-1,3-dithiolane (4) and its cis- andtrans-2-methyl (5,6), -4-methyl (7,8) and -5-methyl (9,10) derivatives were prepared by oxidizing the corresponding 1,3-dithiolanes (1-3) with NaIO4 in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with 1H and 13C NMR spectroscopy and molecular modelling. The sulfoxides 4-6 and 8-10 attain two S(1) type envelopes (sometimes slightly distorted) the S=Oax envelope greatly dominating. Cis-4-methyl-1-oxo-1,3-dithiolane is a special case exhibiting both two closely related S=Oax (30 and 27%) as well as S=Oeq (21 and 22%) forms [S(1) and C(4) envelopes, respectively]. The relative energies of these conformations, the values of 1H-1H coupling constants and 1H and 13C chemical shifts were estimated by computational methods and they support well the conclusions based on the experimental data.
Y1  - 2011
SN  - 0749-1581
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Marsat, Jean-Noël
A1  - Heydenreich, Matthias
A1  - von Berlepsch, Hans
A1  - Laschewsky, André
T1  - Self-Assembly into Multicompartment Micelles and Selective Solubilization by Hydrophilic-Lipophilic- Fluorophilic Block Copolymers
Y1  - 2011
SN  - 0024-9297
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Neuvonen, Kari
A1  - Neuvonen, Helmi
A1  - Koch, Andreas
T1  - NBO analysis of polar and steric effect using the axial-equatorial equilibrium of cyclohexyl acetates as a probe
Y1  - 2011
SN  - 2210-271X
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Shainyan, Bagrat A.
A1  - Suslova, Elena N.
T1  - Conformational analysis of N-phenyl- and N-trifyl-4,4-dimethyl-4-silathiane 1-sulfimides
Y1  - 2011
SN  - 0894-3230
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Shainyan, Bagrat A.
A1  - Suslova, Elena N.
T1  - Conformational analysis of 4,4-dimethyl-4-silathiane and its S-oxides
Y1  - 2011
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Kirpichenko, Svetlana V.
A1  - Ushakov, Igor A.
A1  - Shainyan, Bagrat A.
T1  - Conformational analysis of 3-methyl-3-silathiane and 3-fluoro-3-methyl-3-silathiane
N2  - The conformational equilibria of 3-methyl-3-silathiane 5, 3-fluoro-3-methyl-3-silathiane 6 and 1-fluoro-1- methyl-1-silacyclohexane 7 have been studied using low temperature 13C NMR spectroscopy and theoretical calculations. The conformer ratio at 103;K was measured to be about 5ax:5eq;=;15:85, 6ax:6eq;=;50:50 and 7ax:7eq;=;25:75. The equatorial preference of the methyl group in 5 (0.35;kcal;mol;1) is much less than in 3-methylthiane 9 (1.40;kcal;mol;1) but somewhat greater than in 1-methyl-1- silacyclohexane 1 (0.23;kcal;mol;1). Compounds 5-7 have low barriers to ring inversion: 5.65 (ax;;;eq) and 6.0 (eq;;;ax) kcal mol;1 (5), 4.6 (6), 5.1 (Meax;;;Meeq) and 5.4 (Meeq;;;Meax) kcal;mol;1 (7). Steric effects cannot explain the observed conformational preferences, like equal population of the two conformers of 6, or different conformer ratio for 5 and 7. Actually, by employing the NBO analysis, in particular, considering the second order perturbation energies, vicinal stereoelectronic interactions between the Si-X and adjacent C-H, C-S, and C-C bonds proved responsible.
Y1  - 2011
SN  - 0894-3230
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - The anisotropic effect of functional groups in 1H NMR spectra is the molecular response property of spatial NICS-the frozen conformational equilibria of 9-arylfluorenes
N2  - Rotation about the single bond adjoining the aryl and fluorene moieties in 9-arylfluorenes can be frozen out on the NMR timescale if methyl groups are located at either one or both of the ortho positions of the aryl substituent. In the ground-state of these rotamers, the planes of the aryl and fluorene moieties are perpendicular to each other and the methyl protons are either shielded or deshielded, respectively, due to the ringe current effect of the fluorene moiety. This anisotropic effect on the 1H chemical shifts of the methyl protons has been quantified on the basis of through- space NMR shieldings (TSNMRS) and subsequently _______ compared with the experimentally observed chemical shift differences _____. In this context, the experimental anisotropic effects of functional groups in the !H NMR have proven to quantitatively be the molecular response property of theoretical spatial nucleus independent chemical shieldings (NICS). Differences between _______ and _____ were, for the first time, also quantified as arising from steric compression.
Y1  - 2011
UR  - http://www.sciencedirect.com/science/article/pii/S0040402011008507 (13.9.13)
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Lammermann, Anica
A1  - Kühn, Heiner
T1  - Synthesis and NMR spectra of the syn and anti isomers of substituted cyclobutanes-evidence for steric and spatial hyperconjugative interactions
N2  - The syn and anti isomers of cis,cis-tricyclo[5.3.0.0(2.6)]dec-3-ene derivatives have been synthesized and their (1)H and (13)C NMR spectra unequivocally analyzed. Both their structures and their (1)H and (13)C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions.
Y1  - 2011
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Csütörtöki, Renáta
A1  - Szatmári, István
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Fulop, Ferenc
T1  - Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives
Y1  - 2011
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - Chelatoaromaticity-existing: yes or no? An answer given by spatial magnetic properties (through space NMR shieldings-TSNMRS)
Y1  - 2011
SN  - 1463-9076
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Lämmermann, Anica
A1  - Kühn, Heiner
T1  - The anisotropic effect of functional groups in H-1 NMR spectra is the molecular response property of spatial nucleus independent chemical shifts (NICS)-Conformational equilibria of exo/endo tetrahydrodicyclopentadiene derivatives
N2  - The inversion of the flexible five-membered ring in tetrahydrodicyclopentadiene (TH-DCPD) derivatives remains fast on the NMR timescale even at 103 K. Since the intramolecular exchange process could not be sufficiently slowed for spectroscopic evaluation, the conformational equilibrium is thus inaccessible by dynamic NMR. Fortunately, the spatial magnetic properties of the aryl and carbonyl groups attached to the DCPD skeleton can be employed in order to evaluate the conformational state of the system. In this context, the anisotropic effects of the functional groups in the H-1 NMR spectra prove to be the molecular response property of spatial nucleus independent chemical shifts (NICS).
Y1  - 2011
ER  - 
TY  - JOUR
A1  - Stojanovic, Milovan
A1  - Markovic, Rade
A1  - Kleinpeter, Erich
A1  - Baranac-Stojanovic, Marija
T1  - endo-Mode cyclizations of vinylogous N-acyliminium ions as a route to the synthesis of condensed thiazolidines
Y1  - 2011
SN  - 0040-4020
ER  - 
TY  - JOUR
A1  - Pontius, N.
A1  - Kachel, T.
A1  - Schüssler-Langeheine, C.
A1  - Schlotter, W. F.
A1  - Beye, Martin
A1  - Sorgenfrei, Nomi
A1  - Chang, C. F.
A1  - Föhlisch, Alexander
A1  - Wurth, W.
A1  - Metcalf, P.
A1  - Leonov, I.
A1  - Yaresko, A.
A1  - Stojanovic, N.
A1  - Berglund, Martin
A1  - Guerassimova, N.
A1  - Duesterer, S.
A1  - Redlin, H.
A1  - Duerr, H. A.
T1  - Time-resolved resonant soft x-ray diffraction with free-electron lasers  femtosecond dynamics across the Verwey transition in magnetite
JF  - Applied physics letters
N2  - Resonant soft x-ray diffraction (RSXD) with femtosecond (fs) time resolution is a powerful tool for disentangling the interplay between different degrees of freedom in strongly correlated electron materials. It allows addressing the coupling of particular degrees of freedom upon an external selective perturbation, e. g., by an optical or infrared laser pulse. Here, we report a time-resolved RSXD experiment from the prototypical correlated electron material magnetite using soft x-ray pulses from the free-electron laser FLASH in Hamburg. We observe ultrafast melting of the charge-orbital order leading to the formation of a transient phase, which has not been observed in equilibrium.
Y1  - 2011
U6  - https://doi.org/10.1063/1.3584855
SN  - 0003-6951
VL  - 98
IS  - 18
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Herzschuh, Ulrike
A1  - Ni, Jian
A1  - Birks, H. John B.
A1  - Böhner, Jürgen
T1  - Driving forces of mid-Holocene vegetation shifts on the upper Tibetan Plateau, with emphasis on changes in atmospheric CO2 concentrations
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - Numerous pollen records across the upper Tibetan Plateau indicate that in the early part of the mid-Holocene, Kobresia-rich high-alpine meadows invaded areas formerly dominated by alpine steppe vegetation rich in Artemisia. We examine climate, land-use, and CO2 concentration changes as potential drivers for this marked vegetation change. The climatic implications of these vegetational shifts are explored by applying a newly developed pollen-based moisture-balance transfer-function to fossil pollen spectra from Koucha Lake on the north-eastern Tibetan Plateau (34.0 degrees N; 97.2 degrees E; 4540 m a.s.l.) and Xuguo Lake on the central Tibetan Plateau (31.97 degrees N; 90.3 degrees E; 4595 m a.s.l.), both located in the meadow-steppe transition zone. Reconstructed moisture-balances were markedly reduced (by similar to 150-180 mm) during the early mid-Holocene compared to the late-Holocene. These findings contradict most other records from the Indian monsoonal realm and also most non-pollen records from the Tibetan Plateau that indicate a rather wet early- and mid-Holocene. The extent and timing of anthropogenic land-use involving grazing by large herbivores on the upper Tibetan Plateau and its possible impacts on high-alpine vegetation are still mostly unknown due to the lack of relevant archaeological evidence. Arguments against a mainly anthropogenic origin of Kobresia high-alpine meadows are the discovery of the widespread expansion of obviously 'natural' Kobresia meadows on the south-eastern Tibetan Plateau during the Lateglacial period indicating the natural origin of this vegetation type and the lack of any concurrence between modern human-driven vegetation shifts and the mid-Holocene compositional changes. Vegetation types are known to respond to atmospheric CO2 concentration changes, at least on glacial-interglacial scales. This assumption is confirmed by our sensitivity study where we model Tibetan vegetation at different CO2 concentrations of 375 (present-day), 260 (early Holocene), and 650 ppm (future scenario) using the BIOME4 global vegetation model. Previous experimental studies confirm that vegetation growing on dry and high sites is particularly sensitive to CO2 changes. Here we propose that the replacement of drought-resistant alpine steppes (that are well adapted to low CO2 concentrations) by mesic Kobresia meadows can, at least, be partly interpreted as a response to the increase of CO2 concentration since 7000 years ago due to fertilization and water-saving effects. Our hypothesis is corroborated by former CO2 fertilization experiments performed on various dry grasslands and by the strong recent expansion of high-alpine meadows documented by remote sensing studies in response to recent CO2 increases.
KW  - Tibetan Plateau
KW  - Pollen
KW  - Holocene
KW  - Transfer function
KW  - Kobresia meadow
KW  - Atmospheric CO2 concentration
Y1  - 2011
U6  - https://doi.org/10.1016/j.quascirev.2011.03.007
SN  - 0277-3791
VL  - 30
IS  - 15-16
SP  - 1907
EP  - 1917
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Bagnich, Sergey A.
A1  - Unger, Th.
A1  - Jaiser, Frank
A1  - Neher, Dieter
A1  - Thesen, M. W.
A1  - Krüger, H.
T1  - Efficient green electrophosphorescence based on ambipolar nonconjugated polymers evaluation of transport and emission properties
JF  - Journal of applied physics
N2  - New materials for polymer organic light-emitting diodes based on a polymer matrix doped with phosphorescent dyes are presented. The matrix system is based on a polystyrene backbone bearing either electron or hole transporting units at the 4-position of each repeat unit. Random copolymers and polymer blend systems of the homopolymers are prepared, both with 62 wt.% electron transporting and 38 wt.% hole transporting moieties. Adding a green electrophosphorescent dye to the polymer matrix leads to efficient electroluminescence with a maximum current efficiency of 35 cd/A and a maximum external quantum efficiency of up to 10%. The mobilities of electrons and holes in the dye-doped copolymer, as measured by transient electroluminescence, are around 5 x 10(-5) and 5 x 10(-6) cm(2)/Vs, respectively, while the blend of the two homopolymers exhibits slightly lower mobilities of both types of carriers. Despite the pronounced imbalance of charge transport, the device performance is almost entirely limited by the phosphorescence efficiency of the dye, implying balanced flow of holes and electrons into the active region. Also, devices made with either the copolymer or the blend yielded very similar device efficiencies, despite the noticeable difference in electron and hole mobility. It is proposed that electrons are efficiently blocked at the interlayer and that the so-formed space charge assists the balanced injection of holes.
Y1  - 2011
U6  - https://doi.org/10.1063/1.3618681
SN  - 0021-8979
SN  - 1089-7550
VL  - 110
IS  - 3
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Shayduk, Roman
A1  - Navirian, Hengameh
A1  - Leitenberger, Wolfram
A1  - Goldshteyn, Jevgenij
A1  - Vrejoiu, Ionela
A1  - Weinelt, Martin
A1  - Gaal, Peter
A1  - Herzog, Marc
A1  - von Korff Schmising, Clemens
A1  - Bargheer, Matias
T1  - Nanoscale heat transport studied by high-resolution time-resolved x-ray diffraction
JF  - New journal of physics : the open-access journal for physics
N2  - We report on synchrotron-based high-repetition rate ultrafast x-ray diffraction (UXRD) experiments monitoring the transport of heat from an epitaxial La(0.7)Sr(0.3)MnO(3)/SrTiO(3) superlattice (SL) into the substrate on timescales from 100 ps to 4 mu s. Transient thermal lattice expansion was determined with an accuracy of 10(-7), corresponding to a sensitivity to temperature changes down to 0.01 K. We follow the heat flow within the SL and into the substrate after the impulsive laser heating leads to a small temperature rise of Delta T = 6 K. The transient lattice temperature can be simulated very well using the bulk heat conductivities. This contradicts the interpretation of previous UXRD measurements, which predicted a long-lasting expansion of SrRuO(3) for more than 200 ps. The disagreement could be resolved by assuming that the heat conductivity changes in the first hundred picoseconds.
Y1  - 2011
U6  - https://doi.org/10.1088/1367-2630/13/9/093032
SN  - 1367-2630
VL  - 13
IS  - 11
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Hundertmark, Michaela
A1  - Dimova, Rumiana
A1  - Lengefeld, Jan
A1  - Seckler, Robert
A1  - Hincha, Dirk K.
T1  - The intrinsically disordered late embryogenesis abundant protein LEA18 from Arabidopsis thaliana modulates membrane stability through binding and folding.
N2  - Intrinsically disordered proteins (IDPs) constitute a substantial part of cellular proteomes. Late embryogenesis abundant (LEA) proteins are mostly predicted to be IDPs associated with dehydration tolerance in many plant, animal and bacterial species. Their functions, however, are largely unexplored and also their structure and interactions with potential target molecules have only recently been experimentally investigated in a small number of proteins. Here, we report on the structure and interactions with membranes of the Pfam LEA_1 protein LEA18 from the higher plant Arabidopsis thaliana. This functionally uncharacterized positively charged protein specifically aggregated and destabilized negatively charged liposomes. Isothermal titration calorimetry showed binding of the protein to both charged and uncharged membranes. LEA18 alone was largely unstructured in solution. While uncharged membranes had no influence on the secondary structure of LEA18, the protein partially folded into ;-sheet structure in the presence of negatively charged liposomes. These data suggest that LEA18 does not function as a membrane stabilizing protein, as suggested for other LEA proteins. Instead, a possible function of LEA18 could be the composition-dependent modulation of membrane stability, e.g., during signaling or vesicle-mediated transport. Research Highlights
Y1  - 2011
SN  - 0006-3002
ER  - 
TY  - JOUR
A1  - Jeltsch, Florian
A1  - Moloney, Kirk A.
A1  - Schwager, Monika
A1  - Körner, Katrin
A1  - Blaum, Niels
T1  - Consequences of correlations between habitat modifications and negative impact of climate change for regional species survival
JF  - Agriculture, ecosystems & environment : an international journal for scientific research on the relationship of agriculture and food production to the biosphere
N2  - While several empirical and theoretical studies have clearly shown the negative effects of climate or landscape changes on population and species survival only few of them addressed combined and correlated consequences of these key environmental drivers. This also includes positive landscape changes such as active habitat management and restoration to buffer the negative effects of deteriorating climatic conditions. In this study, we apply a conceptual spatial modelling approach based on functional types to explore the effects of both positive and negative correlations between changes in habitat and climate conditions on the survival of spatially structured populations. We test the effect of different climate and landscape change scenarios on four different functional types that represent a broad spectrum of species characterised by their landscape level carrying capacity, the local population turnover rates at the patch level (K-strategies vs. r-strategies) and dispersal characterstics. As expected, simulation results show that correlated landscape and climatic changes can accelerate (in case of habitat loss or degradation) or slow down (in case of habitat gain or improvement) regional species extinction. However, the strength of the combined changes depends on local turnover at the patch level, the overall landscape capacity of the species, and its specific dispersal characteristics. Under all scenarios of correlated changes in habitat and climate conditions we found the highest sensitivity for functional types representing species with a low landscape capacity but a high population growth rate and a strong density regulation causing a high turnover at the local patch level.
 The relative importance of habitat loss or habitat degradation, in combination with climate deterioration, differed among the functional types. However, an increase in regional capacity revealed a similar response pattern: For all types, habitat improvement led to higher survival times than habitat gain, i.e. the establishment of new habitat patches. This suggests that improving local habitat quality at a regional scale is a more promising conservation strategy under climate change than implementing new habitat patches. This conceptual modelling study provides a general framework to better understand and support the management of populations prone to complex environmental changes.
KW  - Functional types
KW  - Spatially explicit modelling
KW  - Dynamic landscapes
KW  - Species conservation
KW  - Habitat fragmentation
KW  - Habitat management
Y1  - 2011
U6  - https://doi.org/10.1016/j.agee.2010.12.019
SN  - 0167-8809
VL  - 145
IS  - 1
SP  - 49
EP  - 58
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Blaum, Niels
A1  - Mosner, Eva
A1  - Schwager, Monika
A1  - Jeltsch, Florian
T1  - How functional is functional?Ecological groupings in terrestrial animal ecology - towards an animal functional type approach
JF  - Biodiversity and conservation
N2  - Understanding mechanisms to predict changes in plant and animal communities is a key challenge in ecology. The need to transfer knowledge gained from single species to a more generalized approach has led to the development of categorization systems where species' similarities in life strategies and traits are classified into ecological groups (EGs) like functional groups/types or guilds. While approaches in plant ecology undergo a steady improvement and refinement of methodologies, progression in animal ecology is lagging behind. With this review, we aim to initiate a further development of functional classification systems in animal ecology, comparable to recent developments in plant ecology. We here (i) give an overview of terms and definitions of EGs in animal ecology, (ii) discuss existing classification systems, methods and application areas of EGs (focusing on terrestrial vertebrates), and (iii) provide a "roadmap towards an animal functional type approach" for improving the application of EGs and classifications in animal ecology. We found that an animal functional type approach requires: (i) the identification of core traits describing species' dependency on their habitat and life history traits, (ii) an optimization of trait selection by clustering traits into hierarchies, (iii) the assessment of "soft traits" as substitute for hardly measurable traits, e.g. body size for dispersal ability, and (iv) testing of delineated groups for validation including experiments.
KW  - Ecological classification
KW  - Functional type
KW  - Guild
KW  - Functional trait
KW  - Trait selection
KW  - Effect group
KW  - Response group
KW  - Environmental relationships
Y1  - 2011
U6  - https://doi.org/10.1007/s10531-011-9995-1
SN  - 0960-3115
VL  - 20
IS  - 11
SP  - 2333
EP  - 2345
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Wasiolka, Bernd
A1  - Blaum, Niels
T1  - Comparing biodiversity between protected savanna and adjacent non-protected farmland in the southern Kalahari
JF  - Journal of arid environments
N2  - In this study we investigated the effect of different land use options (wildlife versus livestock) on species richness of plants and reptiles in the protected Kgalagadi Transfrontier Park (KTP) versus adjacent non-protected farmland within the same savanna habitat type (Aoub dune veld) in the southern Kalahari, South Africa. Our results show that both plant and reptile species richness as well as plant cover and reptile abundance was significantly higher in the protected KTP than in the non-protected farmland. The higher proportion of shrub but lower proportions of perennial grass cover, herb cover, and herb species richness in the farmland can be explained by higher stocking rates and the differences in feeding behaviour between native wild ungulates (e.g. Antidorcas marsupialis, Oryx gazella) and livestock (mainly sheep). The reptile's prey availability and microhabitats (perennial grass tussocks and rodent burrows) for thermoregulation and protection against predators were significantly lower in the farmland. To conclude, our results clearly show that long term effects of different land use options (wildlife in protected KTP versus extensive livestock production in the non-protected farmland) even within the same habitat type have led to significant changes in vegetation composition, availability of microhabitat structures and in the reptile community.
KW  - Kgalagadi Transfrontier Park
KW  - Rangeland
KW  - Degradation
KW  - Species richness
KW  - Conservation
KW  - Reptile
Y1  - 2011
U6  - https://doi.org/10.1016/j.jaridenv.2011.04.011
SN  - 0140-1963
VL  - 75
IS  - 9
SP  - 836
EP  - 841
PB  - Elsevier
CY  - London
ER  - 
TY  - JOUR
A1  - Csuetoertoeki, Renata
A1  - Szatmari, Istvan
A1  - Koch, Andreas
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Fueloep, Ferenc
T1  - Synthesis and conformational analysis of new naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives
JF  - Tetrahedron
N2  - A new highly functionalized aminonaphthol derivative, 1-(amino(2-aminophenyl)methyl)-2-naphthol (4), was synthesized by the reaction of 2-naphthol, 2-nitrobenzaldehyde and tert-butyl carbamate or benzyl carbamate, followed by reduction and/or removal of the protecting group. The aminonaphthol derivative thus obtained was converted in ring-closure reactions with formaldehyde. benzaldehyde and/or phosgene to the corresponding naphth[1,2-e][1,3]oxazino[3,4-c]quinazoline derivatives. The conformational analysis of some derivatives by NMR spectroscopy and accompanying molecular modelling are also reported.
KW  - Naphthoxazinoquinazolines
KW  - NMR
KW  - Conformational analysis
KW  - DFT calculations
KW  - Hammett-Brown plots
Y1  - 2011
U6  - https://doi.org/10.1016/j.tet.2011.08.074
SN  - 0040-4020
VL  - 67
IS  - 44
SP  - 8564
EP  - 8571
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Kramer, Markus
A1  - Kleinpeter, Erich
T1  - A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings
JF  - Journal of magnetic resonance
N2  - The conformational analyses of six non-rigid N-acetyl glucosamine (NAG) derivatives employing residual dipolar couplings (RDCs) and NOEs together with molecular dynamics (MD) simulations are presented. Due to internal dynamics we had to consider different conformer ratios existing in solution. The good quality of the correlation between theoretically and experimentally obtained RDCs show the correctness of the calculated conformers even if the ratios derived from the MD simulations do not exactly meet the experimental data. If possible, the results were compared to former published data and commented.
KW  - NMR
KW  - Residual dipolar couplings
KW  - Molecular dynamics
KW  - N-acetyl glucosamine derivatives
KW  - Carbohydrates
Y1  - 2011
U6  - https://doi.org/10.1016/j.jmr.2011.06.029
SN  - 1090-7807
VL  - 212
IS  - 1
SP  - 174
EP  - 185
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - GEN
A1  - Kramer, Markus
A1  - Kleinpeter, Erich
T1  - A conformational study of N-acetyl glucosamine derivatives utilizing residual dipolar couplings (vol 212, pg 174, 2011)
T2  - Journal of magnetic resonance
Y1  - 2011
U6  - https://doi.org/10.1016/j.jmr.2011.09.017
SN  - 1090-7807
VL  - 213
IS  - 1
SP  - 210
EP  - 211
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Carlsohn, Anja
A1  - Cassel, Michael
A1  - Linne, Karsten
A1  - Mayer, Frank
T1  - How much is too much? - a case report of nutritional supplement use of a high-performance athlete
JF  - The British journal of nutrition : an international journal devoted to the science of human and animal nutrition
N2  - Although dietary nutrient intake is often adequate, nutritional supplement use is common among elite athletes. However, high-dose supplements or the use of multiple supplements may exceed the recommended daily allowance (RDA) of particular nutrients or even result in a daily intake above tolerable upper limits (UL). The present case report presents nutritional intake data and supplement use of a highly trained male swimmer competing at international level. Habitual energy and micronutrient intake were analysed by 3 d dietary reports. Supplement use and dosage were assessed, and total amount of nutrient supply was calculated. Micronutrient intake was evaluated based on RDA and UL as presented by the European Scientific Committee on Food, and maximum permitted levels in supplements (MPL) are given. The athlete's diet provided adequate micronutrient content well above RDA except for vitamin D. Simultaneous use of ten different supplements was reported, resulting in excess intake above tolerable UL for folate, vitamin E and Zn. Additionally, daily supplement dosage was considerably above MPL for nine micronutrients consumed as artificial products. Risks and possible side effects of exceeding UL by the athlete are discussed. Athletes with high energy intake may be at risk of exceeding UL of particular nutrients if multiple supplements are added. Therefore, dietary counselling of athletes should include assessment of habitual diet and nutritional supplement intake. Educating athletes to balance their diets instead of taking supplements might be prudent to prevent health risks that may occur with long-term excess nutrient intake.
KW  - Dietary supplements
KW  - Tolerable upper limits
KW  - Elite athletes
KW  - Vitamins
KW  - Minerals
Y1  - 2011
U6  - https://doi.org/10.1017/S0007114510005556
SN  - 0007-1145
VL  - 105
IS  - 12
SP  - 1724
EP  - 1728
PB  - Cambridge Univ. Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Marsat, Jean-Noel
A1  - Heydenreich, Matthias
A1  - Kleinpeter, Erich
A1  - Berlepsch, Hans V.
A1  - Boettcher, Christoph
A1  - Laschewsky, André
T1  - Self-Assembly into multicompartment micelles and selective solubilization by Hydrophilic-Lipophilic-Fluorophilic block copolymers
JF  - Macromolecules : a publication of the American Chemical Society
N2  - Amphiphilic linear ternary block copolymers (ABC) were synthesized in three consecutive steps by the reversible addition fragmentation chain transfer (RAFT) method. Using oligo(ethylene oxide) monomethyl ether acrylate, benzyl acrylate, and 1H,1H-perfluorobutyl acrylate monomers, the triblock copolymers consist of a hydrophilic (A), a lipophilic (B), and a fluorophilic (C) block. The block sequence of the triphilic copolymers was varied systematically to provide all possible variations: ABC, ACB, and BAC. All blocks have glass transition temperatures below 0 degrees C. Self-assembly into spherical micellar aggregates was observed in aqueous solution, where hydrophobic cores undergo local phase separation into various ultrastructures as shown by cryogenic transmission electron microscopy (cryo-TEM). Selective solubilization of substantial quantities of hydrocarbon and fluorocarbon low molar mass compounds by the lipophilic and fluorophilic block, respectively, is demonstrated.
Y1  - 2011
U6  - https://doi.org/10.1021/ma200032j
SN  - 0024-9297
VL  - 44
IS  - 7
SP  - 2092
EP  - 2105
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Pihlaja, Kalevi
A1  - Sinkkonen, Jari
A1  - Stajer, Geza
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - 1-Oxo-1,3-dithiolanes - synthesis and stereochemistry
JF  - Magnetic resonance in chemistry
N2  - 1-Oxo-1,3-dithiolane (4) and its cis- and trans-2-methyl (5,6), -4-methyl (7,8) and -5-methyl (9,10) derivatives were prepared by oxidizing the corresponding 1,3-dithiolanes (1-3) with NaIO(4) in water. The oxides were purified and their isomers separated using thin layer chromatography. The structural characterization was carried out with (1)H and (13)C NMR spectroscopy and molecular modelling. The sulfoxides 4-6 and 8-10 attain two S(1) type envelopes (sometimes slightly distorted) the S=O(ax) envelope greatly dominating. Cis-4-methyl-1-oxo-1,3-dithiolane is a special case exhibiting both two closely related S=O(ax) (30 and 27%) as well as S=O(eq) (21 and 22%) forms [S(1) and C(4) envelopes, respectively]. The relative energies of these conformations, the values of (1)H-(1)H coupling constants and (1)H and (13)C chemical shifts were estimated by computational methods and they support well the conclusions based on the experimental data.
KW  - NMR
KW  - (1)H NMR
KW  - (13)C NMR
KW  - sulfur heterocycles
KW  - conformational analysis
KW  - computational chemistry
Y1  - 2011
U6  - https://doi.org/10.1002/mrc.2764
SN  - 0749-1581
VL  - 49
IS  - 7
SP  - 443
EP  - 449
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Mayer, Frank
A1  - Scharhag-Rosenberger, Friederike
A1  - Carlsohn, Anja
A1  - Cassel, Michael
A1  - Müller, Steffen
A1  - Scharhag, Jürgen
T1  - The intensity and effects of strength training in the elderly
JF  - Deutsches Ärzteblatt international : a weekly online journal of clinical medicine and public health
N2  - Background: The elderly need strength training more and more as they grow older to stay mobile for their everyday activities. The goal of training is to reduce the loss of muscle mass and the resulting loss of motor function. The dose-response relationship of training intensity to training effect has not yet been fully elucidated.
 Methods: PubMed was selectively searched for articles that appeared in the past 5 years about the effects and dose-response relationship of strength training in the elderly.
 Results: Strength training in the elderly (> 60 years) increases muscle strength by increasing muscle mass, and by improving the recruitment of motor units, and increasing their firing rate. Muscle mass can be increased through training at an intensity corresponding to 60% to 85% of the individual maximum voluntary strength. Improving the rate of force development requires training at a higher intensity (above 85%), in the elderly just as in younger persons. It is now recommended that healthy old people should train 3 or 4 times weekly for the best results; persons with poor performance at the outset can achieve improvement even with less frequent training. Side effects are rare.
 Conclusion: Progressive strength training in the elderly is efficient, even with higher intensities, to reduce sarcopenia, and to retain motor function.
Y1  - 2011
U6  - https://doi.org/10.3238/arztebl.2011.0359
SN  - 1866-0452
VL  - 108
IS  - 21
SP  - 359
EP  - U30
PB  - Dt. Ärzte-Verl.
CY  - Cologne
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - The anisotropic effect of functional groups in H-1 NMR spectra is the molecular response property of spatial NICS-the frozen conformational equilibria of 9-arylfluorenes
JF  - Tetrahedron
N2  - Rotation about the single bond adjoining the aryl and fluorene moieties in 9-arylfluorenes can be frozen out on the NMR timescale if methyl groups are located at either one or both of the ortho positions of the aryl substituent. In the ground-state of these rotamers, the planes of the aryl and fluorene moieties are perpendicular to each other and the methyl substituents are consequently positioned either above the fluorene moiety or in-plane with it; thus, the methyl protons are either shielded or deshielded, respectively, due to the ring current effect of the fluorene moiety. This anisotropic effect on the H-1 chemical shifts of the methyl protons has been quantified on the basis of through-space NMR shieldings (TSNMRS) and subsequently Delta delta(calcd) compared with the experimentally observed chemical shift differences, Delta delta(exp). In this context, the experimental anisotropic effects of functional groups in the H-1 NMR have proven to quantitatively be the molecular response property of theoretical spatial nucleus independent chemical shieldings (NICS). Differences between Delta delta(calcd) and Delta delta(exp) were, for the first time, also quantified as arising from steric compression.
KW  - Through-space NMR shieldings (TSNMRS)
KW  - Spatial NICS
KW  - Anisotropic effect
KW  - Iso-chemical-shielding surfaces (ICSS)
KW  - 9-Arylfluorenes
Y1  - 2011
U6  - https://doi.org/10.1016/j.tet.2011.06.005
SN  - 0040-4020
VL  - 67
IS  - 32
SP  - 5740
EP  - 5743
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Suslova, Elena N.
A1  - Kleinpeter, Erich
T1  - Conformational analysis of N-phenyl- and N-trifyl-4,4-dimethyl-4-silathiane 1-sulfimides
JF  - Journal of physical organic chemistry
N2  - N-Substituted 4,4-dimethyl-4-silathiane 1-sulfimides Me2Si(sic)S=NSO2R [R- Ph (1), CF3 (2)] were studied experimentally by variable temperature dynamic NMR spectroscopy. Low temperature 13 C NMR spectra of the two compounds revealed the frozen ring inversion process and approximately equal content of the axial and equatorial conformers. Calculations of the 4-silathiane derivatives 1, 2 and the model compound [R Me (3)] as well as their carbon analogs, the similarly N-substituted (sic)S=NSO2R thiane 1-sulfimides [R = Ph (4), CF3 (5), Me (6)] at the DFT/B3LYP/6-311G(d, p) level in the gas phase and in chloroform solution using the PCM model at the same level of theory showed a strong dependence of the relative stability of the conformer on the solvent. The electronegative trifluoromethyl group increases the relative stability of the axial conformer.
KW  - 4-silathianes
KW  - conformational analysis
KW  - dynamic NMR
KW  - quantum chemical calculations
KW  - sulfimides
Y1  - 2011
U6  - https://doi.org/10.1002/poc.1811
SN  - 0894-3230
VL  - 24
IS  - 8
SP  - 698
EP  - 704
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Carlsohn, Anja
A1  - Scharhag-Rosenberger, Friederike
A1  - Cassel, Michael
A1  - Weber, Josefine
A1  - Guzman, Annette de Guzman
A1  - Mayer, Frank
T1  - Physical activity levels to estimate the energy requirement of adolescent athletes
JF  - Pediatric exercise science
N2  - Adequate energy intake in adolescent athletes is considered important. Total energy expenditure (TEE) can be calculated from resting energy expenditure (REE) and physical activity level (PAL). However, validated PAL recommendations are available for adult athletes only. Purpose was to comprise physical activity data in adolescent athletes and to establish PAL recommendations for this population. In 64 competitive athletes (15.3 +/- 1.5yr, 20.5 +/- 2.0kg/m(2)) and 14 controls (15.1 +/- 1.1yr, 21 +/- 2.1kg/m(2)) TEE was calculated using 7-day activity protocols validated against doubly-labeled water. REE was estimated by Schofield-HW equation, and PAL was calculated as TEE:REE. Observed PAL in adolescent athletes (1.90 +/- 0.35) did not differ compared with controls (1.84 +/- 0.32, p = .582) and was lower than recommended for adult athletes by the WHO. In conclusion, applicability of PAL values recommended for adult athletes to estimate energy requirements in adolescent athletes must be questioned. Instead, a PAL range of 1.75-2.05 is suggested.
Y1  - 2011
SN  - 0899-8493
VL  - 23
IS  - 2
SP  - 261
EP  - 269
PB  - Human Kinetics Publ.
CY  - Champaign
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Laemmermann, Anica
A1  - Kühn, Heiner
T1  - Synthesis and NMR spectra of the syn and anti isomers of substituted cyclobutanes-evidence for steric and spatial hyperconjugative interactions
JF  - Tetrahedron
N2  - The syn and anti isomers of cis,cis-tricyclo[5.3.0.0(2.6)]dec-3-ene derivatives have been synthesized and their (1)H and (13)C NMR spectra unequivocally analyzed. Both their structures and their (1)H and (13)C NMR chemical shifts were calculated by DFT, the latter two calculations employing the GIAO perturbation method. Additionally, calculated NMR shielding values were partitioned into Lewis and non-Lewis contributions from the bonds and lone pairs involved in the molecules by accompanying NBO and NCS analyses. The differences between the syn and anti isomers were evaluated with respect to steric and spatial hyperconjugation interactions.
KW  - Conformational analysis
KW  - cis,cis-Tricyclo[5.3.0.0(2,6)]dec-3-enes
KW  - NMR
KW  - DFT calculation
KW  - NBO/NCS analysis
Y1  - 2011
U6  - https://doi.org/10.1016/j.tet.2011.02.012
SN  - 0040-4020
VL  - 67
IS  - 14
SP  - 2596
EP  - 2604
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Neuvonen, Kari
A1  - Neuvonen, Helmi
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - NBO analysis of polar and steric effect using the axial-equatorial equilibrium of cyclohexyl acetates as a probe
JF  - Computational and theoretical chemistry
N2  - The proportion of the axial conformer increases in the ax reversible arrow eq equilibrium of cyclohexyl acetates (RCOOC(6)H(11), R reversible arrow Me, Et, iPr, tBu, CH(2)Cl, CHCl(2), CO(3). CH(2)Br, CHBr(2), CBr(3)) with the increasing size of the acyloxy substitution. The nature of this unexpected steric substituent effect, which is opposite to general stereochemical concepts, was studied by means of ab kiln MO method, accompanied by NBO and isodesmic calculations. NBO parameters seem to be good descriptors for quantitative prediction of the experimental Delta G degrees value of the title conformational equilibrium. The origin and propagation of the substituent effect of the polar substitutions (CH(2)Cl, CHCl(2), CCl(3), CH(2)Br, CHBr(2), CBr(3)) differ, however, from those of the pure alkyl (Me, Et, iPr, tBu) substitutions. The Delta G degrees value of the polar derivatives depends on the qC8 charges, on the occupation of the sigma(center dot)(C1-07) orbital and on the hyperconjugative pi(center dot)(c=O) -> sigma(center dot)(C10-X) and sigma(center dot)(C10-X) -> pi(center dot)(c=O) interactions. The substituent sensitivity of these NBC parameters for the two conformers differ to the effect that the ax reversible arrow eq equilibrium is shifted to the left side with increasing electron withdrawing character of the acyloxy group. The Delta G degrees values of the alkyl derivatives are interpreted in terms of the calculated dipole moments. The destabilization in the non-polar medium (the experimental Delta G degrees values used were measured in CD(2)Cl(2)) due to the enhanced dipolar character is more prominent in the case of the equatorial alkyl conformers. As the consequence, the ax reversible arrow eq equilibrium is shifted to the left despite the increasing size of the R group when going from Me to tBu substitution.
KW  - Substituent effects
KW  - Ab initio MO computations
KW  - Conformational equilibria
KW  - Cyclohexyl esters
KW  - NBO analysis
Y1  - 2011
U6  - https://doi.org/10.1016/j.comptc.2010.12.033
SN  - 2210-271X
VL  - 964
IS  - 1-3
SP  - 234
EP  - 242
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Carlsohn, Anja
A1  - Scharhag-Rosenberger, Friederike
A1  - Cassel, Michael
A1  - Mayer, Frank
T1  - Resting metabolic rate in elite rowers and canoeists difference between indirect calorimetry and prediction
JF  - Annals of nutrition & metabolism : journal of nutrition, metabolic diseases and dietetics ; an official journal of International Union of Nutritional Sciences (IUNS)
N2  - Background: Athletes may differ in their resting metabolic rate (RMR) from the general population. However, to estimate the RMR in athletes, prediction equations that have not been validated in athletes are often used. The purpose of this study was therefore to verify the applicability of commonly used RMR predictions for use in athletes. Methods: The RMR was measured by indirect calorimetry in 17 highly trained rowers and canoeists of the German national teams (BMI 24 +/- 2 kg/m(2), fat-free mass 69 +/- 15 kg). In addition, the RMR was predicted using Cunningham (CUN) and Harris-Benedict (HB) equations. A two-way repeated measures ANOVA was calculated to test for differences between predicted and measured RMR (alpha = 0.05). The root mean square percentage error (RMSPE) was calculated and the Bland-Altman procedure was used to quantify the bias for each prediction. Results: Prediction equations significantly underestimated the RMR in males (p < 0.001). The RMSPE was calculated to be 18.4% (CUN) and 20.9% (HB) in the entire group. The bias was 133 kcal/24 h for CUN and 202 kcal/24 h for HB. Conclusions: Predictions significantly underestimate the RMR in male heavyweight endurance athletes but not in females. In athletes with a high fat-free mass, prediction equations might therefore not be applicable to estimate energy requirements. Instead, measurement of the resting energy expenditure or specific prediction equations might be needed for the individual heavyweight athlete.
KW  - Energy requirement
KW  - Calorimetry
KW  - Fat-free mass
KW  - Nutritional counseling
KW  - Athletes
Y1  - 2011
U6  - https://doi.org/10.1159/000330119
SN  - 0250-6807
VL  - 58
IS  - 3
SP  - 239
EP  - 244
PB  - Karger
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Koch, Andreas
T1  - Chelatoaromaticity-existing: yes or no? An answer given by spatial magnetic properties (through space NMR shieldings-TSNMRS)
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - The spatial magnetic properties (through space NMR shieldings-TSNMRS) of metal complexes (with ligands such as acetylacetone, 3-hydroxy-pyran(4) one) and "metallobenzenes" have been calculated by the GIAO perturbation method and visualized as Iso-Chemical-Shielding Surfaces (ICSS) of various sizes and directions. The TSNMRS values, thus obtained, can be successfully employed to quantify and visualize partial aromaticity of the metallocyclic ring by comparison with the spatial magnetic properties of the corresponding non-complexed ligands in comparable structural and electronic situations, and benzene, respectively. Because anisotropy/ring current effects in H-1 NMR spectra proved to be the molecular response property of TSNMRS, the results obtained concerning partial "chelatoaromaticity" are experimentally ensured.
Y1  - 2011
U6  - https://doi.org/10.1039/c1cp21942a
SN  - 1463-9076
SN  - 1463-9084
VL  - 13
IS  - 46
SP  - 20593
EP  - 20601
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Laemmermann, Anica
A1  - Kühn, Heiner
T1  - The anisotropic effect of functional groups in H-1 NMR spectra is the molecular response property of spatial nucleus independent chemical shifts (NICS)-Conformational equilibria of exo/endo tetrahydrodicyclopentadiene derivatives
JF  - Organic & biomolecular chemistry : an international journal of synthetic, physical and biomolecular organic chemistry
N2  - The inversion of the flexible five-membered ring in tetrahydrodicyclopentadiene (TH-DCPD) derivatives remains fast on the NMR timescale even at 103 K. Since the intramolecular exchange process could not be sufficiently slowed for spectroscopic evaluation, the conformational equilibrium is thus inaccessible by dynamic NMR. Fortunately, the spatial magnetic properties of the aryl and carbonyl groups attached to the DCPD skeleton can be employed in order to evaluate the conformational state of the system. In this context, the anisotropic effects of the functional groups in the H-1 NMR spectra prove to be the molecular response property of spatial nucleus independent chemical shifts (NICS).
Y1  - 2011
U6  - https://doi.org/10.1039/c0ob00356e
SN  - 1477-0520
VL  - 9
IS  - 4
SP  - 1098
EP  - 1111
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Baur, Heiner
A1  - Müller, Steffen
A1  - Hirschmüller, Anja
A1  - Cassel, Michael
A1  - Weber, Josefine
A1  - Mayer, Frank
T1  - Comparison in lower leg neuromuscular activity between runners with unilateral mid-portion Achilles tendinopathy and healthy individuals
JF  - Journal of electromyography and kinesiology
N2  - Neuromuscular control in functional situations and possible impairments due to Achilles tendinopathy are not well understood.
 Thirty controls (CO) and 30 runners with Achilles tendinopathy (AT) were tested on a treadmill at 3.33 m s(-1) (12 km h(-1)). Neuromuscular activity of the lower leg (tibialis anterior, peroneal, and gastrocnemius muscle) was measured by surface electromyography. Mean amplitude values (MAV) for the gait cycle phases preactivation, weight acceptance and push-off were calculated and normalised to the mean activity of the entire gait cycle.
 MAVs of the tibialis anterior did not differ between CO and AT in any gait cycle phase. The activation of the peroneal muscle was lower in AT in weight acceptance (p = 0.006), whereas no difference between CO and AT was found in preactivation (p = 0.71) and push-off (p = 0.83). Also, MAVs of the gastrocnemius muscle did not differ between AT and CO in preactivity (p = 0.71) but were reduced in AT during weight acceptance (p = 0.001) and push-off (p = 0.04).
 Achilles tendinopathy does not seem to alter pre-programmed neural control but might induce mechanical deficits of the lower extremity during weight bearing (joint stability). This should be addressed in the therapy process of AT.
KW  - Ankle joint
KW  - Electromyography
KW  - Overuse injury
KW  - Running gait
Y1  - 2011
U6  - https://doi.org/10.1016/j.jelekin.2010.11.010
SN  - 1050-6411
VL  - 21
IS  - 3
SP  - 499
EP  - 505
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - GEN
A1  - Kliegl, Reinhold
A1  - Wei, Ping
A1  - Dambacher, Michael
A1  - Yan, Ming
A1  - Zhou, Xiaolin
T1  - Experimental effects and individual differences in linear mixed models: Estimating the relationship between spatial, object, and attraction effects in visual attention
N2  - Linear mixed models (LMMs) provide a still underused methodological perspective on combining experimental and individual-differences research. Here we illustrate this approach with two-rectangle cueing in visual attention (Egly et al., 1994). We replicated previous experimental cue-validity effects relating to a spatial shift of attention within an object (spatial effect), to attention switch between objects (object effect), and to the attraction of attention toward the display centroid (attraction effect), also taking into account the design-inherent imbalance of valid and other trials. We simultaneously estimated variance/covariance components of subject-related random effects for these spatial, object, and attraction effects in addition to their mean reaction times (RTs). The spatial effect showed a strong positive correlation with mean RT and a strong negative correlation with the attraction effect. The analysis of individual differences suggests that slow subjects engage attention more strongly at the cued location than fast subjects. We compare this joint LMM analysis of experimental effects and associated subject-related variances and correlations with two frequently used alternative statistical procedures
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 236 
KW  - linear mixed model
KW  - individual differences
KW  - visual attention
KW  - spatial attention
KW  - object-based attention
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-56859
ER  - 
TY  - GEN
A1  - Risse, Sarah
A1  - Kliegl, Reinhold
T1  - Adult age differences in the perceptual span during reading
N2  - Following up on research suggesting an age-related reduction in the rightward extent of the perceptual span during reading (Rayner, Castelhano, & Yang, 2009), we compared old and young adults in an N+2-boundary paradigm in which a nonword preview of word N+2 or word N+2 itself is replaced by the target word once the eyes cross an invisible boundary located after word N. The intermediate word N+1 was always three letters long. Gaze durations on word N+2 were significantly shorter for identical than nonword N+2 preview both for young and for old adults with no significant difference in this preview benefit. Young adults, however, did modulate their gaze duration on word N more strongly than old adults in response to the difficulty of the parafoveal word N+1. Taken together, the results suggest a dissociation of preview benefit and parafoveal-on-foveal effect. Results are discussed in terms of age-related decline in resilience towards distributed processing while simultaneously preserving the ability to integrate parafoveal information into foveal processing. As such, the present results relate to proposals of regulatory compensation strategies older adults use to secure an overall reading speed very similar to that of young adults.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 241 
KW  - age differences
KW  - perceptual span
KW  - N+2-boundary paradigm
KW  - preview benefit
KW  - parafoveal-on-foveal effect
KW  - compensation strategies
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-56935
ER  - 
TY  - GEN
A1  - Kliegl, Reinhold
A1  - Bates, Douglas
T1  - International Collaboration in Psychology is on the Rise
N2  - There has been a substantial increase in the percentage for publications with co-authors located in departments from different countries in 12 major journals of psychology. The results are evidence for a remarkable internationalization of psychological research, starting in the mid 1970s and increasing in rate at the beginning of the 1990s. This growth occurs against a constant number of articles with authors from the same country; it is not due to a concomitant increase in the number of co-authors per article. Thus, international collaboration in psychology is obviously on the rise.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 244 
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-57045
ER  - 
TY  - JOUR
A1  - Weiss, Andrea Y.
A1  - Huisinga, Wilhelm
T1  - Error-controlled global sensitivity analysis of ordinary differential equations
JF  - Journal of computational physics
N2  - We propose a novel strategy for global sensitivity analysis of ordinary differential equations. It is based on an error-controlled solution of the partial differential equation (PDE) that describes the evolution of the probability density function associated with the input uncertainty/variability. The density yields a more accurate estimate of the output uncertainty/variability, where not only some observables (such as mean and variance) but also structural properties (e.g., skewness, heavy tails, bi-modality) can be resolved up to a selected accuracy. For the adaptive solution of the PDE Cauchy problem we use the Rothe method with multiplicative error correction, which was originally developed for the solution of parabolic PDEs. We show that, unlike in parabolic problems, conservation properties necessitate a coupling of temporal and spatial accuracy to avoid accumulation of spatial approximation errors over time. We provide convergence conditions for the numerical scheme and suggest an implementation using approximate approximations for spatial discretization to efficiently resolve the coupling of temporal and spatial accuracy. The performance of the method is studied by means of low-dimensional case studies. The favorable properties of the spatial discretization technique suggest that this may be the starting point for an error-controlled sensitivity analysis in higher dimensions.
KW  - ODE with random initial conditions
KW  - Global sensitivity analysis
KW  - Cauchy problem
KW  - Error control/adaptivity
KW  - Rothe method
KW  - Approximate approximations
Y1  - 2011
U6  - https://doi.org/10.1016/j.jcp.2011.05.011
SN  - 0021-9991
VL  - 230
IS  - 17
SP  - 6824
EP  - 6842
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Pilari, Sabine
A1  - Preusse, Cornelia
A1  - Huisinga, Wilhelm
T1  - Gestational influences on the pharmacokinetics of gestagenic drugs a combined in silico, in vitro and in vivo analysis
JF  - European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences, EUFEPS
N2  - During preclinical development of a gestagenic drug, a significant increase of the total plasma concentration was observed after multiple dosing in pregnant rabbits, but not in (non-pregnant) rats or monkeys. We used a PBPK modeling approach in combination with in vitro and in vivo data to address the question to what extent the pharmacologically active free drug concentration is affected by pregnancy induced processes. In human, a significant increase in sex hormone binding globulin (SHBG), and an induction of hepatic CYP3A4 as well as plasma esterases is observed during pregnancy. We find that the observed increase in total plasma trough levels in rabbits can be explained as a combined result of (i) drug accumulation due to multiple dosing, (ii) increase of the binding protein SHBG, and (iii) clearance induction. For human, we predict that free drug concentrations in plasma would not increase during pregnancy above the steady state trough level for non-pregnant women.
KW  - PBPK
KW  - Pregnancy
KW  - Gestagenic drug
KW  - Protein binding
KW  - SHBG
KW  - Clearance induction
Y1  - 2011
U6  - https://doi.org/10.1016/j.ejps.2010.12.003
SN  - 0928-0987
VL  - 42
IS  - 4
SP  - 318
EP  - 331
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - von Kleist, Max
A1  - Menz, Stephan
A1  - Stocker, Hartmut
A1  - Arasteh, Keikawus
A1  - Schuette, Christof
A1  - Huisinga, Wilhelm
T1  - HIV quasispecies dynamics during pro-active treatment switching impact on multi-drug resistance and resistance archiving in latent reservoirs
JF  - PLoS one
N2  - The human immunodeficiency virus (HIV) can be suppressed by highly active anti-retroviral therapy (HAART) in the majority of infected patients. Nevertheless, treatment interruptions inevitably result in viral rebounds from persistent, latently infected cells, necessitating lifelong treatment. Virological failure due to resistance development is a frequent event and the major threat to treatment success. Currently, it is recommended to change treatment after the confirmation of virological failure. However, at the moment virological failure is detected, drug resistant mutants already replicate in great numbers. They infect numerous cells, many of which will turn into latently infected cells. This pool of cells represents an archive of resistance, which has the potential of limiting future treatment options. The objective of this study was to design a treatment strategy for treatment-naive patients that decreases the likelihood of early treatment failure and preserves future treatment options. We propose to apply a single, pro-active treatment switch, following a period of treatment with an induction regimen. The main goal of the induction regimen is to decrease the abundance of randomly generated mutants that confer resistance to the maintenance regimen, thereby increasing subsequent treatment success. Treatment is switched before the overgrowth and archiving of mutant strains that carry resistance against the induction regimen and would limit its future re-use. In silico modelling shows that an optimal trade-off is achieved by switching treatment at & 80 days after the initiation of antiviral therapy. Evaluation of the proposed treatment strategy demonstrated significant improvements in terms of resistance archiving and virological response, as compared to conventional HAART. While continuous pro-active treatment alternation improved the clinical outcome in a randomized trial, our results indicate that a similar improvement might also be reached after a single pro-active treatment switch. The clinical validity of this finding, however, remains to be shown by a corresponding trial.
Y1  - 2011
U6  - https://doi.org/10.1371/journal.pone.0018204
SN  - 1932-6203
VL  - 6
IS  - 3
PB  - PLoS
CY  - San Fransisco
ER  -