TY  - JOUR
A1  - Sanders, Lloyd P.
A1  - Lomholt, Michael A.
A1  - Lizana, Ludvig
A1  - Fogelmark, Karl
A1  - Metzler, Ralf
A1  - Ambjoernsson, Tobias
T1  - Severe slowing-down and universality of the dynamics in disordered interacting many-body systems: ageing and ultraslow diffusion
JF  - New journal of physics : the open-access journal for physics
N2  - Low-dimensional, many-body systems are often characterized by ultraslow dynamics. We study a labelled particle in a generic system of identical particles with hard-core interactions in a strongly disordered environment. The disorder is manifested through intermittent motion with scale-free sticking times at the single particle level. While for a non-interacting particle we find anomalous diffusion of the power-law form < x(2)(t)> similar or equal to t(alpha) of the mean squared displacement with 0 < alpha < 1, we demonstrate here that the combination of the disordered environment with the many-body interactions leads to an ultraslow, logarithmic dynamics < x(2)(t)> similar or equal to log(1/2)t with a universal 1/2 exponent. Even when a characteristic sticking time exists but the fluctuations of sticking times diverge we observe the mean squared displacement < x(2)(t)> similar or equal to t(gamma) with 0 < gamma < 1/2, that is slower than the famed Harris law < x(2)(t)> similar or equal to t(1/2) without disorder. We rationalize the results in terms of a subordination to a counting process, in which each transition is dominated by the forward waiting time of an ageing continuous time process.
KW  - single-file diffusion
KW  - continuous time random walks
KW  - ageing
Y1  - 2014
U6  - https://doi.org/10.1088/1367-2630/16/11/113050
SN  - 1367-2630
VL  - 16
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Micciulla, Samantha
A1  - Dodoo, Samuel
A1  - Chevigny, Chloe
A1  - Laschewsky, André
A1  - von Klitzing, Regine
T1  - Short versus long chain polyelectrolyte multilayers: a direct comparison of self-assembly and structural properties
JF  - Physical chemistry, chemical physics : a journal of European Chemical Societies
N2  - Successful layer-by-layer (LbL) growth of short chain (similar to 30 repeat units per chain) poly(sodium styrene sulfonate) (PSS)-poly(diallyl dimethylammonium chloride) (PDADMAC) multilayers is presented for the first time and compared with the growth of equivalent long chain polyelectrolyte multilayers (PEMs). A detailed study performed by quartz crystal microbalance with dissipation (QCM-D) is carried out and three main processes are identified: (i) initial mass uptake, (ii) adsorption desorption during layer equilibration and (iii) desorption during rinsing. In contrast to the high stability and strong layer increment of high molecular weight (HMW) PEMs, layer degradation characterizes low molecular weight (LMW) multilayers. In particular, two different instability phenomena are observed: a constant decrease of sensed mass during equilibration after PDADMAC adsorption, and a strong mass toss by salt-free rinsing after PSS adsorption. Yet, an increase of salt concentration leads to much stronger layer growth. First, when the rinsing medium is changed from pure water to 0.1 M NaCl, the mass loss during rinsing is reduced, irrespective of molecular weight. Second, an increase in salt concentration in the LMW PE solutions causes a larger increment during the initial adsorption step, with no effect on the rinsing. Finally, the mechanical properties of the two systems are extracted from the measured frequency and dissipation shifts, as they offer a deeper insight into the multilayer structures depending on chain length and outermost layer. The paper enriches the field of PE assembly by presenting the use of very short PE chains to form multilayers and elucidates the role of preparation conditions to overcome the limitation of layer stability.
Y1  - 2014
U6  - https://doi.org/10.1039/c4cp03439b
SN  - 1463-9076
SN  - 1463-9084
VL  - 16
IS  - 40
SP  - 21988
EP  - 21998
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - INPR
A1  - Gerhard, Reimund
T1  - Sidney Lang - his collaboration with the University of Potsdam
T2  - Ferroelectrics
Y1  - 2014
U6  - https://doi.org/10.1080/00150193.2014.967090
SN  - 0015-0193
SN  - 1563-5112
VL  - 472
IS  - 1
SP  - 5
EP  - 5
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Gerhardt, Matthias
A1  - Walz, Michael
A1  - Beta, Carsten
T1  - Signaling in chemotactic amoebae remains spatially confined to stimulated membrane regions
JF  - Journal of cell science
N2  - Recent work has demonstrated that the receptor-mediated signaling system in chemotactic amoeboid cells shows typical properties of an excitable system. Here, we delivered spatially confined stimuli of the chemoattractant cAMP to the membrane of differentiated Dictyostelium discoideum cells to investigate whether localized receptor stimuli can induce the spreading of excitable waves in the G-protein-dependent signal transduction system. By imaging the spatiotemporal dynamics of fluorescent markers for phosphatidylinositol (3,4,5)-trisphosphate (PIP3), PTEN and filamentous actin, we observed that the activity of the signaling pathway remained spatially confined to the stimulated membrane region. Neighboring parts of the membrane were not excited and no receptor-initiated spatial spreading of excitation waves was observed. To generate localized cAMP stimuli, either particles that carried covalently bound cAMP molecules on their surface were brought into contact with the cell or a patch of the cell membrane was aspirated into a glass micropipette to shield this patch against freely diffusing cAMP molecules in the surrounding medium. Additionally, the binding site of the cAMP receptor was probed with different surface-immobilized cAMP molecules, confirming results from earlier ligand-binding studies.
KW  - Signal transduction
KW  - Excitable dynamics
KW  - Dictyostelium
KW  - cAMP
KW  - PIP3
KW  - PIP2
KW  - PI3K
KW  - PTEN
KW  - Micropipette aspiration
KW  - cAMP receptor
KW  - Patch clamp
Y1  - 2014
U6  - https://doi.org/10.1242/jcs.161133
SN  - 0021-9533
SN  - 1477-9137
VL  - 127
IS  - 23
SP  - 5115
EP  - 5125
PB  - Company of Biologists Limited
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Di Pietro, Riccardo
A1  - Venkateshvaran, Deepak
A1  - Klug, Andreas
A1  - List-Kratochvil, Emil J. W.
A1  - Facchetti, Antonio
A1  - Sirringhaus, Henning
A1  - Neher, Dieter
T1  - Simultaneous extraction of charge density dependent mobility and variable contact resistance from thin film transistors
JF  - Applied physics letters
N2  - A model for the extraction of the charge density dependent mobility and variable contact resistance in thin film transistors is proposed by performing a full derivation of the current-voltage characteristics both in the linear and saturation regime of operation. The calculated values are validated against the ones obtained from direct experimental methods. This approach allows unambiguous determination of gate voltage dependent contact and channel resistance from the analysis of a single device. It solves the inconsistencies in the commonly accepted mobility extraction methods and provides additional possibilities for the analysis of the injection and transport processes in semiconducting materials. (C) 2014 AIP Publishing LLC.
Y1  - 2014
U6  - https://doi.org/10.1063/1.4876057
SN  - 0003-6951
SN  - 1077-3118
VL  - 104
IS  - 19
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Holldack, Karsten
A1  - Ovsyannikov, Ruslan
A1  - Kuske, P.
A1  - Mueller, R.
A1  - Schaelicke, A.
A1  - Scheer, M.
A1  - Gorgoi, Mihaela
A1  - Kuehn, D.
A1  - Leitner, T.
A1  - Svensson, S.
A1  - Martensson, N.
A1  - Föhlisch, Alexander
T1  - Single bunch X-ray pulses on demand from a multi-bunch synchrotron radiation source
JF  - Nature Communications
N2  - Synchrotron radiation facilities routinely operate in a multi-bunch regime, but applications relying on time-of-flight schemes require single bunch operation. Here we show that pulse picking by resonant excitation in a storage ring creates in addition to the multi-bunch operation a distinct and separable single bunch soft X-ray source. It has variable polarization, a photon flux of up to 10(7)-10(9) ph s(-1)/0.1%BW at purity values of 10(4)-10(2) and a repetition rate of 1.25 MHz. The quasi-resonant excitation of incoherent betatron oscillations of electrons allows horizontal pulse separation at variable (also circular) polarization accessible for both, regular 30 ps pulses and ultrashort pulses of 2-3 ps duration. Combined with a new generation of angularly resolving electron spectrometers this creates unique opportunities for time-resolved photoemission studies as confirmed by time-of-flight spectra. Our pulse picking scheme is particularly suited for surface physics at diffraction-limited light sources promising ultimate spectral resolution.
Y1  - 2014
U6  - https://doi.org/10.1038/ncomms5010
SN  - 2041-1723
VL  - 5
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Shalom, Menny
A1  - Inal, Sahika
A1  - Neher, Dieter
A1  - Antonietti, Markus
T1  - SiO2/carbon nitride composite materials: The role of surfaces for enhanced photocatalysis
JF  - Catalysis today : a serial publication dealing with topical themes in catalysis and related subjects
N2  - The effect of SiO2 nanoparticles on carbon nitride (C3N4) photoactivity performance is described. The composite SiO2-C3N4 materials exhibit a higher activity in the photo degradation of RhB dye. A detailed analysis of the chemical and optical properties of the composite C3N4 materials shows that the photo activity increases with higher SiO2 concentration. We found out that the presence of SiO2 nanoparticles strongly affects the fluorescence intensity of the matrix and life time by the creation of new energy states for charge transfer within the C3N4. Furthermore, the use of SiO2 in the synthesis of C3N4 leads to new morphology with higher surface area which results in another, secondary improvement of C3N4 photoactivity. The effect of different surfaces within C3N4 on its chemical and electronic properties is discussed and a tentative mechanism is proposed. The utilization of SiO2 nanoparticles improves both photophysical and chemical properties of C3N4 and opens new possibilities for further enhancement of C3N4 catalytic properties by the formation of composites with many other materials.
KW  - Carbon nitride
KW  - SiO2 composite material
KW  - Photocatalysis
KW  - RhB degradation
Y1  - 2014
U6  - https://doi.org/10.1016/j.cattod.2013.12.013
SN  - 0920-5861
SN  - 1873-4308
VL  - 225
SP  - 185
EP  - 190
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kliem, Bernhard
A1  - Toeroek, Tibor
A1  - Titov, Viacheslav S.
A1  - Lionello, Roberto
A1  - Linker, Jon A.
A1  - Liu, Rui
A1  - Liu, Chang
A1  - Wang, Haimin
T1  - Slow rise and partial eruption of a double-decker filament. II. A double flux rope model
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - Force-free equilibria containing two vertically arranged magnetic flux ropes of like chirality and current direction are considered as a model for split filaments/prominences and filament-sigmoid systems. Such equilibria are constructed analytically through an extension of the methods developed in Titov & Demoulin and numerically through an evolutionary sequence including shear flows, flux emergence, and flux cancellation in the photospheric boundary. It is demonstrated that the analytical equilibria are stable if an external toroidal (shear) field component exceeding a threshold value is included. If this component decreases sufficiently, then both flux ropes turn unstable for conditions typical of solar active regions, with the lower rope typically becoming unstable first. Either both flux ropes erupt upward, or only the upper rope erupts while the lower rope reconnects with the ambient flux low in the corona and is destroyed. However, for shear field strengths staying somewhat above the threshold value, the configuration also admits evolutions which lead to partial eruptions with only the upper flux rope becoming unstable and the lower one remaining in place. This can be triggered by a transfer of flux and current from the lower to the upper rope, as suggested by the observations of a split filament in Paper I. It can also result from tether-cutting reconnection with the ambient flux at the X-type structure between the flux ropes, which similarly influences their stability properties in opposite ways. This is demonstrated for the numerically constructed equilibrium.
KW  - instabilities
KW  - magnetohydrodynamics (MHD)
KW  - Sun: coronal mass ejections (CMEs)
KW  - Sun: filaments, prominences
KW  - Sun: flares
Y1  - 2014
U6  - https://doi.org/10.1088/0004-637X/792/2/107
SN  - 0004-637X
SN  - 1538-4357
VL  - 792
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Maistrenko, Yuri
A1  - Penkovsky, Bogdan
A1  - Rosenblum, Michael
T1  - Solitary state at the edge of synchrony in ensembles with attractive and repulsive interactions
JF  - Physical review : E, Statistical, nonlinear and soft matter physics
N2  - We discuss the desynchronization transition in networks of globally coupled identical oscillators with attractive and repulsive interactions. We show that, if attractive and repulsive groups act in antiphase or close to that, a solitary state emerges with a single repulsive oscillator split up from the others fully synchronized. With further increase of the repulsing strength, the synchronized cluster becomes fuzzy and the dynamics is given by a variety of stationary states with zero common forcing. Intriguingly, solitary states represent the natural link between coherence and incoherence. The phenomenon is described analytically for phase oscillators with sine coupling and demonstrated numerically for more general amplitude models.
Y1  - 2014
U6  - https://doi.org/10.1103/PhysRevE.89.060901
SN  - 1539-3755
SN  - 1550-2376
VL  - 89
IS  - 6
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Palyulin, Vladimir V.
A1  - Chechkin, Aleksei V.
A1  - Metzler, Ralf
T1  - Space-fractional Fokker-Planck equation and optimization of random search processes in the presence of an external bias
JF  - Journal of statistical mechanics: theory and experiment
N2  - Based on the space-fractional Fokker-Planck equation with a delta-sink term, we study the efficiency of random search processes based on Levy flights with power-law distributed jump lengths in the presence of an external drift, for instance, an underwater current, an airflow, or simply the preference of the searcher based on prior experience. While Levy flights turn out to be efficient search processes when the target is upstream relative to the starting point, in the downstream scenario, regular Brownian motion turns out to be advantageous. This is caused by the occurrence of leapovers of Levy flights, due to which Levy flights typically overshoot a point or small interval. Studying the solution of the fractional Fokker-Planck equation, we establish criteria when the combination of the external stream and the initial distance between the starting point and the target favours Levy flights over the regular Brownian search. Contrary to the common belief that Levy flights with a Levy index alpha = 1 (i.e. Cauchy flights) are optimal for sparse targets, we find that the optimal value for alpha may range in the entire interval (1, 2) and explicitly include Brownian motion as the most efficient search strategy overall.
KW  - driven diffusive systems (theory)
KW  - fluctuations (theory)
KW  - stochastic processes (theory)
KW  - diffusion
Y1  - 2014
U6  - https://doi.org/10.1088/1742-5468/2014/11/P11031
SN  - 1742-5468
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Aliu, E.
A1  - Aune, T.
A1  - Behera, B.
A1  - Beilicke, M.
A1  - Benbow, W.
A1  - Berger, K.
A1  - Bird, R.
A1  - Bouvier, A.
A1  - Buckley, J. H.
A1  - Bugaev, V.
A1  - Cerruti, M.
A1  - Chen, Xuhui
A1  - Ciupik, L.
A1  - Connolly, M. P.
A1  - Cui, W.
A1  - Dumm, J.
A1  - Dwarkadas, Vikram V.
A1  - Errando, M.
A1  - Falcone, A.
A1  - Federici, Simone
A1  - Feng, Q.
A1  - Finley, J. P.
A1  - Fleischhack, H.
A1  - Fortin, P.
A1  - Fortson, L.
A1  - Furniss, A.
A1  - Galante, N.
A1  - Gillanders, G. H.
A1  - Gotthelf, E. V.
A1  - Griffin, S.
A1  - Griffiths, S. T.
A1  - Grube, J.
A1  - Gyuk, G.
A1  - Hanna, D.
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, C. A.
A1  - Kaaret, P.
A1  - Kargaltsev, O.
A1  - Kertzman, M.
A1  - Khassen, Y.
A1  - Kieda, D.
A1  - Krennrich, F.
A1  - Lang, M. J.
A1  - Madhavan, A. S.
A1  - Maier, G.
A1  - McArthur, S.
A1  - McCann, A.
A1  - Millis, J.
A1  - Moriarty, P.
A1  - Mukherjee, R.
A1  - Nieto, D.
A1  - Ong, R. A.
A1  - Otte, A. N.
A1  - Pandel, D.
A1  - Park, N.
A1  - Pohl, Martin
A1  - Popkow, A.
A1  - Prokoph, H.
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Rajotte, J.
A1  - Reyes, L. C.
A1  - Reynolds, P. T.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Roberts, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, K.
A1  - Smith, A. W.
A1  - Staszak, D.
A1  - Telezhinsky, Igor O.
A1  - Tucci, J. V.
A1  - Tyler, J.
A1  - Vincent, S.
A1  - Wakely, S. P.
A1  - Weinstein, A.
A1  - Welsing, R.
A1  - Wilhelm, Alina
A1  - Williams, D. A.
A1  - Zitzer, B.
T1  - Spatially resolving the very high energy emission from MRGO J2019+37 wih  veritas
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - We present very high energy (VHE) imaging of MGRO J2019+37 obtained with the VERITAS observatory. The bright extended (similar to 2 degrees) unidentified Milagro source is located toward the rich star formation region Cygnus-X. MGRO J2019+37 is resolved into two VERITAS sources. The faint, point-like source VER J2016+371 overlaps CTB 87, a filled-center remnant (SNR) with no evidence of a supernova remnant shell at the present time. Its spectrum is well fit in the 0.65-10 TeV energy range by a power-law model with photon index 2.3 +/- 0.4. VER J2019+378 is a bright extended (similar to 1 degrees) source that likely accounts for the bulk of the Milagro emission and is notably coincident with PSR J2021+3651 and the star formation region Sh 2-104. Its spectrum in the range 1-30 TeV is well fit with a power-law model of photon index 1.75 +/- 0.3, among the hardest values measured in the VHE band, comparable to that observed near Vela-X. We explore the unusual spectrum and morphology in the radio and X-ray bands to constrain possible emission mechanisms for this source.
KW  - gamma rays : stars
KW  - pulsars : individual (PSR J2021+3651)
KW  - supernovae : individual (CTB 87)
Y1  - 2014
U6  - https://doi.org/10.1088/0004-637X/788/1/78
SN  - 0004-637X
SN  - 1538-4357
VL  - 788
IS  - 1
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - INPR
A1  - Hilczer, Börn
A1  - Gerhard, Reimund
A1  - Scott, James F.
T1  - Special Issue of Ferroelectrics in Honor of S. B. Lang
T2  - Ferroelectrics
Y1  - 2014
U6  - https://doi.org/10.1080/00150193.2014.964099
SN  - 0015-0193
SN  - 1563-5112
VL  - 472
IS  - 1
SP  - VII
EP  - VIII
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Toenjes, Ralf
A1  - Sokolov, Igor M.
A1  - Postnikov, Eugene B.
T1  - Spectral properties of the fractional Fokker-Planck operator for the Levy flight in a harmonic potential
JF  - The European physical journal
N2  - We present a detailed analysis of the eigenfunctions of the Fokker-Planck operator for the LevyOrnstein- Uhlenbeck process, their asymptotic behavior and recurrence relations, explicit expressions in coordinate space for the special cases of the Ornstein-Uhlenbeck process with Gaussian and with Cauchy white noise and for the transformation kernel, which maps the fractional Fokker-Planck operator of the Cauchy-Ornstein-Uhlenbeck process to the non-fractional Fokker-Planck operator of the usual Gaussian Ornstein-Uhlenbeck process. We also describe how non-spectral relaxation can be observed in bounded random variables of the Levy-Ornstein-Uhlenbeck process and their correlation functions.
Y1  - 2014
U6  - https://doi.org/10.1140/epjb/e2014-50558-5
SN  - 1434-6028
SN  - 1434-6036
VL  - 87
IS  - 12
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Palyulin, Vladimir V.
A1  - Metzler, Ralf
T1  - Speeding up the first-passage for subdiffusion by introducing a finite potential barrier
JF  - Journal of physics : A, Mathematical and theoretical
N2  - We show that for a subdiffusive continuous time random walk with scale-free waiting time distribution the first-passage dynamics on a finite interval can be optimized by introduction of a piecewise linear potential barrier. Analytical results for the survival probability and first-passage density based on the fractional Fokker-Planck equation are shown to agree well with Monte Carlo simulations results. As an application we discuss an improved design for efficient translocation of gradient copolymers compared to homopolymer translocation in a quasi-equilibrium approximation.
KW  - first passage
KW  - anomalous diffusion
KW  - potential landscape
KW  - polymer translocation
Y1  - 2014
U6  - https://doi.org/10.1088/1751-8113/47/3/032002
SN  - 1751-8113
SN  - 1751-8121
VL  - 47
IS  - 3
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Albrecht, Torsten
A1  - Levermann, Anders
T1  - Spontaneous ice-front retreat caused by disintegration of adjacent ice shelf in Antarctica
JF  - Earth & planetary science letters
N2  - Antarctic ice-discharge constitutes the largest uncertainty in future sea-level projections. Floating ice shelves, fringing most of Antarctica, exert retentive forces onto the ice flow. While abrupt ice-shelf retreat has been observed, it is generally considered a localized phenomenon. Here we show that the disintegration of an ice shelf may induce the spontaneous retreat of its neighbor. As an example, we reproduce the spontaneous but gradual retreat of the Larsen B ice front as observed after the disintegration of the adjacent Larsen A ice shelf. We show that the Larsen A collapse yields a change in spreading rate in Larsen B via their connecting ice channels and thereby causes a retreat of the ice front to its observed position of the year 2000, prior to its collapse. This mechanism might be particularly relevant for the role of East Antarctica and the Antarctic Peninsula in future sea level.
KW  - Antarctica
KW  - Larsen Ice Shelf
KW  - glaciology
KW  - numerical ice modeling
KW  - sea level
KW  - iceberg calving
Y1  - 2014
U6  - https://doi.org/10.1016/j.epsl.2014.02.034
SN  - 0012-821X
SN  - 1385-013X
VL  - 393
SP  - 26
EP  - 30
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Miedema, Piter S.
A1  - Wernet, Philippe
A1  - Föhlisch, Alexander
T1  - State-dependent fluorescence yields through the core-valence Coulomb exchange parameter
JF  - Physical review : A, Atomic, molecular, and optical physics
N2  - Total and partial fluorescence yield (PFY) L-edge x-ray absorption spectra differ from the transmission x-ray absorption spectra (XAS) through state-dependent fluorescence yield across the XAS. For 3d(1) to 3d(9) in octahedral symmetry we apply simulations of PFY and XAS and show how the atomic 2p3d Coulomb exchange parameter G(pd) governs the differences in the L-3/(L-2 + L-3) branching ratio between PFY and XAS. G(pd) orders the XAS final states following Hund's rules creating a strong state-dependent fluorescence decay strength variation across the XAS leading to the differences between PFY and XAS.
Y1  - 2014
U6  - https://doi.org/10.1103/PhysRevA.89.052507
SN  - 1050-2947
SN  - 1094-1622
VL  - 89
IS  - 5
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Winkler, Roland G.
A1  - Cherstvy, Andrey G.
ED  - Muller, M.
T1  - Strong and weak polyelectrolyte adsorption onto oppositely charged curved surfaces
JF  - Advances in polymer science
JF  - Advances in Polymer Science
N2  - Polyelectrolytes are macromolecules composed of charged monomers and exhibit unique properties due to the interplay of their flexibility and electrostatic interactions. In solution, they are attracted to oppositely charged surfaces and interfaces and exhibit a transition to an adsorbed state when certain conditions are met concerning the charge densities of the polymer and surface and the properties of the solution. In this review, we discuss two limiting cases for adsorption of flexible polyelectrolytes on curved surfaces: weak and strong adsorption. In the first case, adsorption is strongly influenced by the entropic degrees of freedom of a flexible polyelectrolyte. By contrast, in the strong adsorption limit, electrostatic interactions dominate, which leads to particular adsorption patterns, specifically on spherical surfaces. We discuss the corresponding theoretical approaches, applying a mean-field description for the polymer and the polymer-surface interaction. For weak adsorption, we discuss the critical adsorption behavior by exactly solvable models for planar and spherical geometries and a generic approximation scheme, which is additionally applied to cylindrical surfaces. For strong adsorption, we investigate various polyelectrolyte patterns on cylinders and spheres and evaluate their stability. The results are discussed in the light of experimental results, mostly of DNA adsorption experiments.
Y1  - 2014
SN  - 978-3-642-40734-5; 978-3-642-40733-8
U6  - https://doi.org/10.1007/12_2012_183
SN  - 0065-3195
VL  - 255
SP  - 1
EP  - 56
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Joulain, Karl
A1  - Ben-Abdallah, Philippe
A1  - Chapuis, Pierre-Olivier
A1  - De Wilde, Y.
A1  - Babuty, A.
A1  - Henkel, Carsten
T1  - Strong tip-sample coupling in thermal radiation scanning tunneling microscopy
JF  - Journal of quantitative spectroscopy & radiative transfer
KW  - Near-field thermal radiation
KW  - Infrared radiation
KW  - Local density of states
KW  - Scanning near-field optical microscopy
KW  - Tip-sample interactions
KW  - Local spectroscopy
Y1  - 2014
U6  - https://doi.org/10.1016/j.jqsrt.2013.12.006
SN  - 0022-4073
SN  - 1879-1352
VL  - 136
SP  - 1
EP  - 15
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Louis, Rohan E.
A1  - Puschmann, Klaus G.
A1  - Kliem, Bernhard
A1  - Balthasar, Horst
A1  - Denker, Carsten
T1  - Sunspot splitting triggering an eruptive flare
JF  - Astronomy and astrophysics : an international weekly journal
N2  - Aims. We investigate how the splitting of the leading sunspot and associated flux emergence and cancellation in active region NOAA 11515 caused an eruptive M5.6 flare on 2012 July 2.
 Methods. Continuum intensity, line-of-sight magnetogram, and dopplergram data of the Helioseismic and Magnetic Imager were employed to analyse the photospheric evolution. Filtergrams in H alpha and He I 10830 angstrom of the Chromospheric Telescope at the Observatorio del Teide, Tenerife, track the evolution of the flare. The corresponding coronal conditions were derived from 171 angstrom and 304 angstrom images of the Atmospheric Imaging Assembly. Local correlation tracking was utilized to determine shear flows.
 Results. Emerging flux formed a neutral line ahead of the leading sunspot and new satellite spots. The sunspot splitting caused a long-lasting flow towards this neutral line, where a filament formed. Further flux emergence, partly of mixed polarity, as well as episodes of flux cancellation occurred repeatedly at the neutral line. Following a nearby C-class precursor flare with signs of interaction with the filament, the filament erupted nearly simultaneously with the onset of the M5.6 flare and evolved into a coronal mass ejection. The sunspot stretched without forming a light bridge, splitting unusually fast (within about a day, complete approximate to 6 h after the eruption) in two nearly equal parts. The front part separated strongly from the active region to approach the neighbouring active region where all its coronal magnetic connections were rooted. It also rotated rapidly (by 4.9 degrees h(-1)) and caused significant shear flows at its edge.
 Conclusions. The eruption resulted from a complex sequence of processes in the (sub-)photosphere and corona. The persistent flows towards the neutral line likely caused the formation of a flux rope that held the filament. These flows, their associated flux cancellation, the emerging flux, and the precursor flare all contributed to the destabilization of the flux rope. We interpret the sunspot splitting as the separation of two flux bundles differently rooted in the convection zone and only temporarily joined in the spot. This explains the rotation as the continued rise of the separating flux, and it implies that at least this part of the sunspot was still connected to its roots deep in the convection zone.
KW  - Sun: flares
KW  - sunspots
KW  - Sun: photosphere
KW  - Sun: chromosphere
KW  - techniques: photometric
Y1  - 2014
U6  - https://doi.org/10.1051/0004-6361/201321106
SN  - 0004-6361
SN  - 1432-0746
VL  - 562
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - JOUR
A1  - Vlasov, Vladimir
A1  - Macau, Elbert E. N.
A1  - Pikovskij, Arkadij
T1  - Synchronization of oscillators in a Kuramoto-type model with generic coupling
JF  - Chaos : an interdisciplinary journal of nonlinear science
N2  - We study synchronization properties of coupled oscillators on networks that allow description in terms of global mean field coupling. These models generalize the standard Kuramoto-Sakaguchi model, allowing for different contributions of oscillators to the mean field and to different forces from the mean field on oscillators. We present the explicit solutions of self-consistency equations for the amplitude and frequency of the mean field in a parametric form, valid for noise-free and noise-driven oscillators. As an example, we consider spatially spreaded oscillators for which the coupling properties are determined by finite velocity of signal propagation. (C) 2014 AIP Publishing LLC.
Y1  - 2014
U6  - https://doi.org/10.1063/1.4880835
SN  - 1054-1500
SN  - 1089-7682
VL  - 24
IS  - 2
PB  - American Institute of Physics
CY  - Melville
ER  -