TY  - JOUR
A1  - Cassan, A.
A1  - Beaulieu, Jean-Philippe
A1  - Brillant, Stephane
A1  - Coutures, C.
A1  - Dominik, M.
A1  - Donatowicz, J.
A1  - Jorgensen, Uffe Grae
A1  - Kubas, Daniel
A1  - Albrow, Michael D.
A1  - Caldwell, John A. R.
A1  - Fouque, P.
A1  - Greenhill, John
A1  - Hill, K.
A1  - Horne, Keith
A1  - Kane, Stephen R.
A1  - Martin, Ralph
A1  - Menzies, J. W.
A1  - Pollard, K. R.
A1  - Sahu, K. C.
A1  - Vinter, C.
A1  - Wambsganss, Joachim
A1  - Watson, R.
A1  - Williams, A.
A1  - Fendt, Christian
A1  - Hauschildt, P.
A1  - Heinmueller, Janine
A1  - Marquette, Jean-Baptiste
A1  - Thurl, C.
T1  - Probing the atmosphere of the bulge G5III star OGLE-2002-BUL-069 by analysis of microlensed H alpha line
N2  - We discuss high-resolution, time-resolved spectra of the caustic exit of the binary microlensing event OGLE 2002-BLG-069 obtained with UVES on the VLT. The source star is a G5III giant in the Galactic Bulge. During such events, the source star is highly magnified, and a strong differential magnification around the caustic resolves its surface. Using an appropriate model stellar atmosphere generated by the PHOENIX v2.6 code we obtain a model light curve for the caustic exit and compare it with a dense set of photometric observations obtained by the PLANET microlensing follow up network. We further compare predicted variations in the Halpha equivalent width with those measured from our spectra. While the model and observations agree in the gross features, there are discrepancies suggesting shortcomings in the model, particularly for the Halpha line core, where we have detected amplified emission from the stellar chromosphere after the source star's trailing limb exited the caustic. This achievement became possible by the provision of the very efficient OGLE-III Early Warning System, a network of small telescopes capable of nearly-continuous round-the-clock photometric monitoring, on-line data reduction, daily near-real-time modelling in order to predict caustic crossing parameters, and a fast and efficient response of a 8 m class telescope to a "Target-of-Opportunity" observation request
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Jiang, G. F.
A1  - DePoy, D. L.
A1  - Gal-Yam, A.
A1  - Gaudi, B. S.
A1  - Gould, A.
A1  - Han, C.
A1  - Lipkin, Y.
A1  - Maoz, D.
A1  - Ofek, E. O.
A1  - Park, B. G.
A1  - Pogge, R. W.
A1  - Udalski, A.
A1  - Kubiak, Marcin
A1  - Szymanski, M. K.
A1  - Szewczyk, O.
A1  - Zerbrun, K.
A1  - Wyrzykowski, L.
A1  - Soszynski, I.
A1  - Pietrzynski, G.
A1  - Albrow, Michael D.
A1  - Beaulieu, Jean-Philippe
A1  - Caldwell, John A. R.
A1  - Cassan, A.
A1  - Coutures, C.
A1  - Dominik, M.
A1  - Donatowicz, J.
A1  - Fouque, P.
A1  - Greenhill, John
A1  - Hill, K.
A1  - Horne, Keith
A1  - Jorgensen, S. F.
A1  - Jorgensen, Uffe Grae
A1  - Kane, Stephen R.
A1  - Kubas, Daniel
A1  - Martin, Ralph
A1  - Menzies, J. W.
A1  - Pollard, R.
A1  - Sahu, K. C.
A1  - Wambsganss, Joachim
A1  - Watson, R.
A1  - Williams, A.
T1  - OGLE-2003-BLG-238 : Microlensing mass estimate of an isolated star
N2  - Microlensing is the only known direct method to measure the masses of stars that lack visible companions. In terms of microlensing observables, the mass is given by M (c(2)/4G)(r) over tilde (E)theta(E) and so requires the measurement of both the angular Einstein radius theta(E) and the projected Einstein radius (r) over tilde (E). Simultaneous measurement of these two parameters is extremely rare. Here we analyze OGLE-2003-BLG-238, a spectacularly bright (I-min 10.3), high-magnification (A(max) 170) microlensing event. Pronounced finite-source effects permit a measurement of theta(E) = 650 muas. Although the timescale of the event is only t(E) 38 days, one can still obtain weak constraints on the microlens parallax: 4.4 AU < <(r)over tilde>(E) < 18 AU at the 1 &sigma; level. Together these two parameter measurements yield a range for the lens mass of 0.36 M-&ODOT; < M < 1.48 M-&ODOT;. As was the case for MACHO- LMC-5, the only other single star (apart from the Sun) whose mass has been determined from its gravitational effects, this estimate is rather crude. It does, however, demonstrate the viability of the technique. We also discuss future prospects for single-lens mass measurements
Y1  - 2004
SN  - 0004-637X
ER  - 
TY  - JOUR
A1  - Treat, Claire C.
A1  - Kleinen, Thomas
A1  - Broothaerts, Nils
A1  - Dalton, April S.
A1  - Dommain, Rene
A1  - Douglas, Thomas A.
A1  - Drexler, Judith Z.
A1  - Finkelstein, Sarah A.
A1  - Grosse, Guido
A1  - Hope, Geoffrey
A1  - Hutchings, Jack
A1  - Jones, Miriam C.
A1  - Kuhry, Peter
A1  - Lacourse, Terri
A1  - Lahteenoja, Outi
A1  - Loisel, Julie
A1  - Notebaert, Bastiaan
A1  - Payne, Richard J.
A1  - Peteet, Dorothy M.
A1  - Sannel, A. Britta K.
A1  - Stelling, Jonathan M.
A1  - Strauss, Jens
A1  - Swindles, Graeme T.
A1  - Talbot, Julie
A1  - Tarnocai, Charles
A1  - Verstraeten, Gert
A1  - Williams, Christopher J.
A1  - Xia, Zhengyu
A1  - Yu, Zicheng
A1  - Valiranta, Minna
A1  - Hattestrand, Martina
A1  - Alexanderson, Helena
A1  - Brovkin, Victor
T1  - Widespread global peatland establishment and persistence over the last 130,000 y
JF  - Proceedings of the National Academy of Sciences of the United States of America
N2  - Glacial-interglacial variations in CO2 and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks through the last glacial cycle (130 ka to present) using a newly compiled database of 1,063 detailed stratigraphic records of peat deposits buried by mineral sediments, as well as a global peatland model. Quantitative agreement between modeling and observations shows extensive peat accumulation before the LGM in northern latitudes (> 40 degrees N), particularly during warmer periods including the last interglacial (130 ka to 116 ka, MIS 5e) and the interstadial (57 ka to 29 ka, MIS 3). During cooling periods of glacial advance and permafrost formation, the burial of northern peatlands by glaciers and mineral sediments decreased active peatland extent, thickness, and modeled C stocks by 70 to 90% from warmer times. Tropical peatland extent and C stocks show little temporal variation throughout the study period. While the increased burial of northern peats was correlated with cooling periods, the burial of tropical peat was predominately driven by changes in sea level and regional hydrology. Peat burial by mineral sediments represents a mechanism for long-term terrestrial C storage in the Earth system. These results show that northern peatlands accumulate significant C stocks during warmer times, indicating their potential for C sequestration during the warming Anthropocene.
KW  - peatlands
KW  - carbon
KW  - methane
KW  - carbon burial
KW  - Quaternary
Y1  - 2019
U6  - https://doi.org/10.1073/pnas.1813305116
SN  - 0027-8424
VL  - 116
IS  - 11
SP  - 4822
EP  - 4827
PB  - National Acad. of Sciences
CY  - Washington
ER  - 
TY  - JOUR
A1  - Toy, Virginia Gail
A1  - Sutherland, Rupert
A1  - Townend, John
A1  - Allen, Michael J.
A1  - Becroft, Leeza
A1  - Boles, Austin
A1  - Boulton, Carolyn
A1  - Carpenter, Brett
A1  - Cooper, Alan
A1  - Cox, Simon C.
A1  - Daube, Christopher
A1  - Faulkner, D. R.
A1  - Halfpenny, Angela
A1  - Kato, Naoki
A1  - Keys, Stephen
A1  - Kirilova, Martina
A1  - Kometani, Yusuke
A1  - Little, Timothy
A1  - Mariani, Elisabetta
A1  - Melosh, Benjamin
A1  - Menzies, Catriona D.
A1  - Morales, Luiz
A1  - Morgan, Chance
A1  - Mori, Hiroshi
A1  - Niemeijer, Andre
A1  - Norris, Richard
A1  - Prior, David
A1  - Sauer, Katrina
A1  - Schleicher, Anja Maria
A1  - Shigematsu, Norio
A1  - Teagle, Damon A. H.
A1  - Tobin, Harold
A1  - Valdez, Robert
A1  - Williams, Jack
A1  - Yeo, Samantha
A1  - Baratin, Laura-May
A1  - Barth, Nicolas
A1  - Benson, Adrian
A1  - Boese, Carolin
A1  - Célérier, Bernard
A1  - Chamberlain, Calum J.
A1  - Conze, Ronald
A1  - Coussens, Jamie
A1  - Craw, Lisa
A1  - Doan, Mai-Linh
A1  - Eccles, Jennifer
A1  - Grieve, Jason
A1  - Grochowski, Julia
A1  - Gulley, Anton
A1  - Howarth, Jamie
A1  - Jacobs, Katrina
A1  - Janku-Capova, Lucie
A1  - Jeppson, Tamara
A1  - Langridge, Robert
A1  - Mallyon, Deirdre
A1  - Marx, Ray
A1  - Massiot, Cécile
A1  - Mathewson, Loren
A1  - Moore, Josephine
A1  - Nishikawa, Osamu
A1  - Pooley, Brent
A1  - Pyne, Alex
A1  - Savage, Martha K.
A1  - Schmitt, Doug
A1  - Taylor-Offord, Sam
A1  - Upton, Phaedra
A1  - Weaver, Konrad C.
A1  - Wiersberg, Thomas
A1  - Zimmer, Martin
T1  - Bedrock geology of DFDP-2B, central Alpine Fault, New Zealand
JF  - New Zealand journal of geology and geophysics : an international journal of the geoscience of New Zealand, the Pacific Rim, and Antarctica ; NZJG
N2  - During the second phase of the Alpine Fault, Deep Fault Drilling Project (DFDP) in the Whataroa River, South Westland, New Zealand, bedrock was encountered in the DFDP-2B borehole from 238.5–893.2 m Measured Depth (MD). Continuous sampling and meso- to microscale characterisation of whole rock cuttings established that, in sequence, the borehole sampled amphibolite facies, Torlesse Composite Terrane-derived schists, protomylonites and mylonites, terminating 200–400 m above an Alpine Fault Principal Slip Zone (PSZ) with a maximum dip of 62°. The most diagnostic structural features of increasing PSZ proximity were the occurrence of shear bands and reduction in mean quartz grain sizes. A change in composition to greater mica:quartz + feldspar, most markedly below c. 700 m MD, is inferred to result from either heterogeneous sampling or a change in lithology related to alteration. Major oxide variations suggest the fault-proximal Alpine Fault alteration zone, as previously defined in DFDP-1 core, was not sampled.
KW  - Alpine Fault
KW  - New Zealand
KW  - scientific drilling
KW  - mylonite
KW  - cataclasite
Y1  - 2017
U6  - https://doi.org/10.1080/00288306.2017.1375533
SN  - 0028-8306
SN  - 1175-8791
VL  - 60
IS  - 4
SP  - 497
EP  - 518
PB  - Taylor & Francis
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - van Driel-Gesztelyi, L.
A1  - Baker, Daniel N.
A1  - Toeroek, T.
A1  - Pariat, E.
A1  - Green, L. M.
A1  - Williams, D. R.
A1  - Carlyle, J.
A1  - Valori, G.
A1  - Demoulin, Pascal
A1  - Kliem, Bernhard
A1  - Long, D. M.
A1  - Matthews, S. A.
A1  - Malherbe, J. -M.
T1  - Coronal magnetic reconnection driven by CME expansion-the 2011 June 7  event
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - Coronal mass ejections (CMEs) erupt and expand in a magnetically structured solar corona. Various indirect observational pieces of evidence have shown that the magnetic field of CMEs reconnects with surrounding magnetic fields, forming, e.g., dimming regions distant from the CME source regions. Analyzing Solar Dynamics Observatory (SDO) observations of the eruption from AR 11226 on 2011 June 7, we present the first direct evidence of coronal magnetic reconnection between the fields of two adjacent active regions during a CME. The observations are presented jointly with a data-constrained numerical simulation, demonstrating the formation/intensification of current sheets along a hyperbolic flux tube at the interface between the CME and the neighboring AR 11227. Reconnection resulted in the formation of new magnetic connections between the erupting magnetic structure from AR 11226 and the neighboring active region AR 11227 about 200 Mm from the eruption site. The onset of reconnection first becomes apparent in the SDO/AIA images when filament plasma, originally contained within the erupting flux rope, is redirected toward remote areas in AR 11227, tracing the change of large-scale magnetic connectivity. The location of the coronal reconnection region becomes bright and directly observable at SDO/AIA wavelengths, owing to the presence of down-flowing cool, dense (1010 cm(-3)) filament plasma in its vicinity. The high-density plasma around the reconnection region is heated to coronal temperatures, presumably by slow-mode shocks and Coulomb collisions. These results provide the first direct observational evidence that CMEs reconnect with surrounding magnetic structures, leading to a large-scale reconfiguration of the coronal magnetic field.
KW  - magnetic reconnection
KW  - magnetohydrodynamics (MHD)
KW  - Sun: corona
KW  - Sun: coronal mass ejections (CMEs)
KW  - Sun: magnetic fields
KW  - Sun: UV radiation
Y1  - 2014
U6  - https://doi.org/10.1088/0004-637X/788/1/85
SN  - 0004-637X
SN  - 1538-4357
VL  - 788
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - GEN
A1  - Driel-Gesztelyi, L. van
A1  - Baker, Daniel N.
A1  - Török, Tibor
A1  - Pariat, Etienne
A1  - Green, L. M.
A1  - Williams, D. R.
A1  - Carlyle, J.
A1  - Valori, G.
A1  - Démoulin, Pascal
A1  - Matthews, S. A.
A1  - Kliem, Bernhard
A1  - Malherbe, J.-M.
T1  - Magnetic reconnection driven by filament eruption in the 7 June 2011 event
T2  - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
N2  - During an unusually massive filament eruption on 7 June 2011, SDO/AIA imaged for the first time significant EUV emission around a magnetic reconnection region in the solar corona. The reconnection occurred between magnetic fields of the laterally expanding CME and a neighbouring active region. A pre-existing quasi-separatrix layer was activated in the process. This scenario is supported by data-constrained numerical simulations of the eruption. Observations show that dense cool filament plasma was re-directed and heated in situ, producing coronal-temperature emission around the reconnection region. These results provide the first direct observational evidence, supported by MHD simulations and magnetic modelling, that a large-scale re-configuration of the coronal magnetic field takes place during solar eruptions via the process of magnetic reconnection.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 608 
KW  - MHD
KW  - instabilities
KW  - Sun: activity
KW  - magnetic fields
KW  - coronal mass ejections (CMEs)
KW  - filaments
KW  - methods: numerical
KW  - data analysis
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-415671
IS  - 608
SP  - 502
EP  - 503
ER  - 
TY  - JOUR
A1  - Sackett, Penny D.
A1  - Albrow, Michael D.
A1  - Beaulieu, Jean-Philippe
A1  - Caldwell, John A. R.
A1  - Coutures, C.
A1  - Dominik, M.
A1  - Greenhill, John
A1  - Hill, K.
A1  - Horne, Keith
A1  - Jorgensen, Uffe Grae
A1  - Kane, Stephen R.
A1  - Kubas, Daniel
A1  - Martin, Ralph
A1  - Menzies, J. W.
A1  - Pollard, K. R.
A1  - Sahu, K. C.
A1  - Wambsganß, Joachim
A1  - Watson, R.
A1  - Williams, A.
T1  - PLANET II : a microlensing and transit search for extrasolar planets
N2  - Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can reveal the presence of exoplanets via the microlensing or eclipsing effects they induce. The international PLANET collaboration is performing such monitoring using a cadre of semi-dedicated telescopes around the world. Their results constrain the number of gas giants orbiting 1-7 AU from the most typical stars in the Galaxy. Upgrades in the program are opening regions of ''exoplanet discovery space'' - toward smaller masses and larger orbital radii - that are inaccessible to the Doppler velocity technique.
Y1  - 2003
UR  - http://arxiv.org/pdf/astro-ph/0211098
ER  - 
TY  - JOUR
A1  - Furniss, Amy
A1  - Worseck, Gabor
A1  - Fumagalli, Michele
A1  - Johnson, Caitlin A.
A1  - Williams, David A.
A1  - Pontrelli, P.
A1  - Prochaska, J. Xavier
T1  - Spectroscopic Redshift of the Gamma-Ray Blazar B2 1215+30 from Ly alpha Emission
JF  - The astronomical journal
N2  - We report on Cosmic Origin Spectrograph observations of the gamma-ray bright blazar B2 1215+30, collected in 2015 November. These observations allow for the confirmation of the source redshift from the detection of a Lyα emission feature at λ ~ 1374 Å. The emission feature places the source at a redshift of z = 0.1305 ± 0.003, confirming the source's ground-based spectral measurement. The gamma-ray emission of the source is discussed in the context of the source distance, required for the accurate reconstruction of the intrinsic gamma-ray emission taking the absorption by the extragalactic background light into account. The source distance is found to be low enough that the previously reported detection of an exceptional flaring event from B2 1215+30 in 2014 cannot be used to investigate opacity-specific spectral and variability characteristics introduced by possible ultra-high-energy cosmic-ray propagation.
KW  - galaxies:distances and redshifts
KW  - galaxies: individual (B2 1215+30)
KW  - gamma rays: galaxies
KW  - ultraviolet: galaxies
Y1  - 2019
U6  - https://doi.org/10.3847/1538-3881/aaf28b
SN  - 0004-6256
SN  - 1538-3881
VL  - 157
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Maddock, Simon T.
A1  - Childerstone, Aaron
A1  - Fry, Bryan Grieg
A1  - Williams, David J.
A1  - Barlow, Axel
A1  - Wuester, Wolfgang
T1  - Multi-locus phylogeny and species delimitation of Australo-Papuan blacksnakes (Pseudechis Wagler, 1830: Elapidae: Serpentes)
JF  - Molecular phylogenetics and evolution
N2  - Genetic analyses of Australasian organisms have resulted in the identification of extensive cryptic diversity across the continent. The venomous elapid snakes are among the best-studied organismal groups in this region, but many knowledge gaps persist: for instance, despite their iconic status, the species-level diversity among Australo-Papuan blacksnakes (Pseudechis) has remained poorly understood due to the existence of a group of cryptic species within the P. australis species complex, collectively termed "pygmy mulga snakes". Using two mitochondrial and three nuclear loci we assess species boundaries within the genus using Bayesian species delimitation methods and reconstruct their phylogenetic history using multispecies coalescent approaches. Our analyses support the recognition of 10 species, including all of the currently described pygmy mulga snakes and one undescribed species from the Northern Territory of Australia. Phylogenetic relationships within the genus are broadly consistent with previous work, with the recognition of three major groups, the viviparous red-bellied black snake P. porphyriacus forming the sister species to two clades consisting of ovoviviparous species.
KW  - Australia
KW  - New Guinea
KW  - Molecular phylogenetics
KW  - BPP
KW  - Snakes
KW  - Multispecies coalescent
Y1  - 2017
U6  - https://doi.org/10.1016/j.ympev.2016.09.005
SN  - 1055-7903
SN  - 1095-9513
VL  - 107
SP  - 48
EP  - 55
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Kefi, Sonia
A1  - Berlow, Eric L.
A1  - Wieters, Evie A.
A1  - Navarrete, Sergio A.
A1  - Petchey, Owen L.
A1  - Wood, Spencer A.
A1  - Boit, Alice
A1  - Joppa, Lucas N.
A1  - Lafferty, Kevin D.
A1  - Williams, Richard J.
A1  - Martinez, Neo D.
A1  - Menge, Bruce A.
A1  - Blanchette, Carol A.
A1  - Iles, Alison C.
A1  - Brose, Ulrich
T1  - More than a meal ... integrating non-feeding interactions into food webs
JF  - Ecology letters
N2  - Organisms eating each other are only one of many types of well documented and important interactions among species. Other such types include habitat modification, predator interference and facilitation. However, ecological network research has been typically limited to either pure food webs or to networks of only a few (<3) interaction types. The great diversity of non-trophic interactions observed in nature has been poorly addressed by ecologists and largely excluded from network theory. Herein, we propose a conceptual framework that organises this diversity into three main functional classes defined by how they modify specific parameters in a dynamic food web model. This approach provides a path forward for incorporating non-trophic interactions in traditional food web models and offers a new perspective on tackling ecological complexity that should stimulate both theoretical and empirical approaches to understanding the patterns and dynamics of diverse species interactions in nature.
KW  - Ecological network
KW  - ecosystem engineering
KW  - facilitation
KW  - food web
KW  - interaction modification
KW  - non-trophic interactions
KW  - trophic interactions
Y1  - 2012
U6  - https://doi.org/10.1111/j.1461-0248.2011.01732.x
SN  - 1461-023X
VL  - 15
IS  - 4
SP  - 291
EP  - 300
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Boit, Alice
A1  - Martinez, Neo D.
A1  - Williams, Richard J.
A1  - Gaedke, Ursula
T1  - Mechanistic theory and modelling of complex food-web dynamics in Lake Constance
JF  - Ecology letters
N2  - Mechanistic understanding of consumer-resource dynamics is critical to predicting the effects of global change on ecosystem structure, function and services. Such understanding is severely limited by mechanistic models inability to reproduce the dynamics of multiple populations interacting in the field. We surpass this limitation here by extending general consumer-resource network theory to the complex dynamics of a specific ecosystem comprised by the seasonal biomass and production patterns in a pelagic food web of a large, well-studied lake. We parameterised our allometric trophic network model of 24 guilds and 107 feeding relationships using the lakes food web structure, initial spring biomasses and body-masses. Adding activity respiration, the detrital loop, minimal abiotic forcing, prey resistance and several empirically observed rates substantially increased the model's fit to the observed seasonal dynamics and the size-abundance distribution. This process illuminates a promising approach towards improving food-web theory and dynamic models of specific habitats.
KW  - Allometric Trophic Network model
KW  - community ecology
KW  - food web
KW  - multi-trophic dynamics
KW  - seasonal plankton succession
Y1  - 2012
U6  - https://doi.org/10.1111/j.1461-0248.2012.01777.x
SN  - 1461-023X
VL  - 15
IS  - 6
SP  - 594
EP  - 602
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Richardson, Noel D.
A1  - Shenar, Tomer
A1  - Roy-Loubier, Olivier
A1  - Schaefer, Gail
A1  - Moffat, Anthony F. J.
A1  - St-Louis, Nicole
A1  - Gies, Douglas R.
A1  - Farrington, Chris
A1  - Hill, Grant M.
A1  - Williams, Peredur M.
A1  - Gordon, Kathryn
A1  - Pablo, Herbert
A1  - Ramiaramanantsoa, Tahina
T1  - The CHARA Array resolves the long-period Wolf-Rayet binaries WR 137 and WR 138
JF  - Monthly notices of the Royal Astronomical Society
N2  - We report on interferometric observations with the CHARAArray of two classical Wolf-Rayet (WR) stars in suspected binary systems, namely WR 137 and WR 138. In both cases, we resolve the component stars to be separated by a few milliarcseconds. The data were collected in the H band, and provide a measure of the fractional flux for both stars in each system. We find that the WR star is the dominant H-band light source in both systems (fWR, 137 = 0.59 +/- 0.04; fWR, 138 = 0.67 +/- 0.01), which is confirmed through both comparisons with estimated fundamental parameters for WR stars and O dwarfs, as well as through spectral modelling of each system. Our spectral modelling also provides fundamental parameters for the stars and winds in these systems. The results on WR 138 provide evidence that it is a binary system which may have gone through a previous mass-transfer episode to create the WR star. The separation and position of the stars in the WR 137 system together with previous results from the IOTA interferometer provides evidence that the binary is seen nearly edgeon. The possible edge-on orbit of WR 137 aligns well with the dust production site imaged by the Hubble Space Telescope during a previous periastron passage, showing that the dust production may be concentrated in the orbital plane.
KW  - binaries: visual
KW  - stars: individual: WR 137
KW  - stars: individual: WR 138
KW  - stars: mass-loss
KW  - stars: winds, outflows
KW  - stars: Wolf-Rayet
Y1  - 2016
U6  - https://doi.org/10.1093/mnras/stw1585
SN  - 0035-8711
SN  - 1365-2966
VL  - 461
SP  - 4115
EP  - 4124
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Hommes-Schattmann, Paul J.
A1  - Neffe, Axel T.
A1  - Ahmad, Bilal
A1  - Williams, Gareth R.
A1  - Vanneaux, Valerie
A1  - Menasche, Philippe
A1  - Kalfa, David
A1  - Lendlein, Andreas
T1  - RGD constructs with physical anchor groups as polymer co-electrospinnable cell adhesives
JF  - Polymers for advanced technologies
N2  - The tissue integration of synthetic polymers can be promoted by displaying RGD peptides at the biointerface with the objective of enhancing colonization of the material by endogenous cells. A firm but flexible attachment of the peptide to the polymer matrix, still allowing interaction with receptors, is therefore of interest. Here, the covalent coupling of flexible physical anchor groups, allowing for temporary immobilization on polymeric surfaces via hydrophobic or dipole-dipole interactions, to a RGD peptide was investigated. For this purpose, a stearate or an oligo(ethylene glycol) (OEG) was attached to GRGDS in 51-69% yield. The obtained RGD linker constructs were characterized by NMR, IR and MALDI-ToF mass spectrometry, revealing that the commercially available OEG and stearate linkers are in fact mixtures of similar compounds. The RGD linker constructs were co-electrospun with poly(p-dioxanone) (PPDO). After electrospinning, nitrogen could be detected on the surface of the PPDO fibers by X-ray photoelectron spectroscopy. The nitrogen content exceeded the calculated value for the homogeneous material mixture suggesting a pronounced presentation of the peptide on the fiber surface. Increasing amounts of RGD linker constructs in the electrospinning solution did not lead to a detection of an increased amount of peptide on the scaffold surface, suggesting inhomogeneous distribution of the peptide on the PPDO fiber surface. Human adipose-derived stem cells cultured on the patches showed similar viability as when cultured on PPDO containing pristine RGD. The fully characterized RGD linker constructs could serve as valuable tools for the further development of tissue-integrating polymeric scaffolds. Copyright (c) 2016 John Wiley & Sons, Ltd.
KW  - electrospinning
KW  - RGD peptides
KW  - cell adhesion
KW  - biofunctionalization
Y1  - 2017
U6  - https://doi.org/10.1002/pat.3963
SN  - 1042-7147
SN  - 1099-1581
VL  - 28
SP  - 1312
EP  - 1317
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Gvaramadze, V. V.
A1  - Kniazev, A. Y.
A1  - Miroshnichenko, A. S.
A1  - Berdnikov, Leonid N.
A1  - Langer, N.
A1  - Stringfellow, G. S.
A1  - Todt, Helge Tobias
A1  - Hamann, Wolf-Rainer
A1  - Grebel, E. K.
A1  - Buckley, D.
A1  - Crause, L.
A1  - Crawford, S.
A1  - Gulbis, A.
A1  - Hettlage, C.
A1  - Hooper, E.
A1  - Husser, T. -O.
A1  - Kotze, P.
A1  - Loaring, N.
A1  - Nordsieck, K. H.
A1  - O'Donoghue, D.
A1  - Pickering, T.
A1  - Potter, S.
A1  - Colmenero, E. Romero
A1  - Vaisanen, P.
A1  - Williams, T.
A1  - Wolf, M.
A1  - Reichart, D. E.
A1  - Ivarsen, K. M.
A1  - Haislip, J. B.
A1  - Nysewander, M. C.
A1  - LaCluyze, A. P.
T1  - Discovery of two new Galactic candidate luminous blue variables with Wide-field Infrared Survey Explorer
JF  - Monthly notices of the Royal Astronomical Society
N2  - We report the discovery of two new Galactic candidate luminous blue variable (LBV) stars via detection of circular shells (typical of confirmed and candidate LBVs) and follow-up spectroscopy of their central stars. The shells were detected at 22 mu m in the archival data of the Mid-Infrared All Sky Survey carried out with the Wide-field Infrared Survey Explorer (WISE). Follow-up optical spectroscopy of the central stars of the shells conducted with the renewed Southern African Large Telescope (SALT) showed that their spectra are very similar to those of the well-known LBVs P Cygni and AG Car, and the recently discovered candidate LBV MN112, which implies the LBV classification for these stars as well. The LBV classification of both stars is supported by detection of their significant photometric variability: one of them brightened in the R and I bands by 0.68 +/- 0.10 and 0.61 +/- 0.04 mag, respectively, during the last 1318 years, while the second one (known as Hen 3-1383) varies its B, V, R, I and Ks brightnesses by similar or equal to 0.50.9 mag on time-scales from 10 d to decades. We also found significant changes in the spectrum of Hen 3-1383 on a time-scale of similar or equal to 3 months, which provides additional support for the LBV classification of this star. Further spectrophotometric monitoring of both stars is required to firmly prove their LBV status. We discuss a connection between the location of massive stars in the field and their fast rotation, and suggest that the LBV activity of the newly discovered candidate LBVs might be directly related to their possible runaway status.
KW  - line: identification
KW  - circumstellar matter
KW  - stars: emission-line, Be
KW  - stars: evolution
KW  - stars: individual: Hen 3-1383
KW  - stars: massive
Y1  - 2012
U6  - https://doi.org/10.1111/j.1365-2966.2012.20556.x
SN  - 0035-8711
VL  - 421
IS  - 4
SP  - 3325
EP  - 3337
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Lützow, Karola
A1  - Hommes-Schattmann, Paul J.
A1  - Neffe, Axel T.
A1  - Ahmad, Bilal
A1  - Williams, Gareth R.
A1  - Lendlein, Andreas
T1  - Perfluorophenyl azide functionalization of electrospun poly(para-dioxanone)
JF  - Polymers for advanced technologies
N2  - Strategies to surface-functionalize scaffolds by covalent binding of biologically active compounds are of fundamental interest to control the interactions between scaffolds and biomolecules or cells. Poly(para-dioxanone) (PPDO) is a clinically established polymer that has shown potential as temporary implant, eg, for the reconstruction of the inferior vena cava, as a nonwoven fiber mesh. However, PPDO lacks suitable chemical groups for covalent functionalization. Furthermore, PPDO is highly sensitive to hydrolysis, reflected by short in vivo half-life times and degradation during storage. Establishing a method for covalent functionalization without degradation of this hydrolyzable polymer is therefore important to enable the surface tailoring for tissue engineering applications. It was hypothesized that treatment of PPDO with an N-hydroxysuccinimide ester group bearing perfluorophenyl azide (PFPA) under UV irradiation would allow efficient surface functionalization of the scaffold. X-ray photoelectron spectroscopy and attenuated total reflectance Fourier-transformed infrared spectroscopy investigation revealed the successful binding, while a gel permeation chromatography study showed that degradation did not occur under these conditions. Coupling of a rhodamine dye to the N-hydroxysuccinimide esters on the surface of a PFPA-functionalized scaffold via its amine linker showed a homogenous staining of the PPDO in laser confocal microscopy. The PFPA method is therefore applicable even to the surface functionalization of hydrolytically labile polymers, and it was demonstrated that PFPA chemistry may serve as a versatile tool for the (bio-)functionalization of PPDO scaffolds.
KW  - biological applications of polymers
KW  - fibers
KW  - functionalization of polymers
KW  - microstructure
Y1  - 2018
U6  - https://doi.org/10.1002/pat.4331
SN  - 1042-7147
SN  - 1099-1581
VL  - 30
IS  - 5
SP  - 1165
EP  - 1172
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Thiede, Rasmus Christoph
A1  - Arrowsmith, J. Ramón
A1  - Bookhagen, Bodo
A1  - McWilliams, Michael O.
A1  - Sobel, Edward
A1  - Strecker, Manfred
T1  - Dome formation and extension in the Tethyan Himalaya, Leo Pargil, northwest India
N2  - Metamorphic dome complexes occur within the internal structures of the northern Himalaya and southern Tibet. Their origin, deformation, and fault displacement patterns are poorly constrained. We report new field mapping, structural data, and cooling ages from the western flank of the Leo Pargil dome in the northwestern Himalaya in an attempt to characterize its post-middle Miocene structural development. The western flank of the dome is characterized by shallow, west-dipping pervasive foliation and WNW-ESE mineral lineation. Shear-sense indicators demonstrate that it is affected by east-west normal faulting that facilitated exhumation of high-grade metamorphic rocks in a contractional setting. Sustained top-to-northwest normal faulting during exhumation is observed in a progressive transition from ductile to brittle deformation. Garnet and kyanite indicate that the Leo Pargil dome was exhumed from the mid-crust. Ar- 40/Ar-39 mica and apatite fission track (AFT) ages constrain cooling and exhumation pathways front 350 to 60 degrees C and suggest that the dome cooled in three stages since the middle Miocene. Ar-40/Ar-39 white mica ages of 16-14 Ma suggest a first phase of rapid cooling and provide minimum estimates for the onset of dome exhumation. AFT ages between 10 and 8 Ma suggest that ductile fault displacement had ceased by then, and AFT track-length data from high-elevation samples indicate that the rate of cooling had decreased significantly. We interpret this to indicate decreased fault displacement along the Leo Pargil shear zone and possibly a transition to the Kaurik-Chango normal fault system between 10 and 6 Ma. AFT ages from lower elevations indicate accelerated cooling since the Pliocene that cannot be related to pure fault displacement, and therefore may reflect more pronounced regionally distributed and erosion-driven exhumation
Y1  - 2006
U6  - https://doi.org/10.1130/B25872.1
ER  - 
TY  - JOUR
A1  - Thiede, Rasmus Christoph
A1  - Arrowsmith, J. Ramón
A1  - Bookhagen, Bodo
A1  - McWilliams, Michael O.
A1  - Sobel, Edward
A1  - Strecker, Manfred
T1  - From tectonically to erosionally controlled development of the Himalayan orogen
N2  - Whether variations in the spatial distribution of erosion influence the location, style, and magnitude of deformation within the Himalayan orogen is a matter of debate. We report new Ar-40/Ar-39 white mica and apatite fission- track (AFT) ages that measure the vertical component of exhumation rates along an similar to 120-km-wide NE-SW transect spanning the greater Sutlej region of northwest India. The Ar-40/Ar-39 data indicate that first the High Himalayan Crystalline units cooled below their closing temperature during the early to middle Miocene. Subsequently, Lesser Himalayan Crystalline nappes cooled rapidly, indicating southward propagation of the orogen during late Miocene to Pliocene time. The AFT data, in contrast, imply synchronous exhumation of a NE-SW-oriented similar to 80 x 40 km region spanning both crystalline nappes during the Pliocene-Quaternary. The locus of pronounced exhumation defined by the AFT data correlates with a region of high precipitation, discharge, and sediment flux rates during the Holocene. This correlation suggests that although tectonic processes exerted the dominant control on the denudation pattern before and until the middle Miocene; erosion may have been the most important factor since the Pliocene
Y1  - 2005
SN  - 0091-7613
ER  - 
TY  - JOUR
A1  - Hoke, Gregory D.
A1  - Garzione, Carmala N.
A1  - Araneo, Diego C.
A1  - Latorre, Claudio
A1  - Strecker, Manfred
A1  - Williams, Kendra J.
T1  - The stable isotope altimeter : do quaternary pedogenic carbonates predict modern elevations?
N2  - Stable isotope altimetry is a useful tool for estimating paleoelevation in sedimentary records. Yet questions remain regarding how source moisture, climate, and local topography can influence these estimates. Here we present stable isotope altimetry results on late Quaternary pedogenic carbonates of known elevation on both flanks of the Andean orogen at 33 degrees S. We measured delta O-18 values of pedogenic carbonates and river water samples from small drainages at regular elevation increments within the Rio Aconcagua (Chile) and Rio Mendoza (Argentina) catchments. The delta O-18 values of river waters correlate well with elevation and show similar isotopic gradients between the Chilean (-3.7 parts per thousand/km) and Argentine (-4.8 parts per thousand/km) sides of the range. Uncertainties associated with scatter in the river water data and assumptions about the temperature of carbonate formation indicate that elevation estimates have 1 sigma errors of 350-450 m. We estimate the isotopic composition of soil water from pedogenic carbonates on both sides of the range by assuming mean annual temperatures based the modern temperature lapse rate from meteorological station data. Combined, our data show that stable isotope altimetry produces reasonable estimates of modern elevation, with the majority of our samples (60%) within the 1 sigma uncertainties and 77% within 2 sigma.
Y1  - 2009
UR  - http://geology.gsapubs.org/
U6  - https://doi.org/10.1130/G30308a.1
SN  - 0091-7613
ER  -