@article{MontanariFabianiCianietal.2007, author = {Montanari, Gian Carlo and Fabiani, Davide and Ciani, Franco and Motori, Antonio and Paajanen, Mika and Gerhard, Reimund and Wegener, Michael}, title = {Charging properties and time-temperature stability of innovative polymeric cellular ferroelectrets}, issn = {1070-9878}, doi = {10.1109/TDEI.2007.302892}, year = {2007}, abstract = {After appropriate mechanical and electrical treatments, some cellular polymers become able to retain space charge for a long time, i.e. they acquire electret behavior. The electrical treatment consists of charging under high levels of DC electric field. The mechanical treatment, based on the application of stretching forces to cellular polymer slabs that were before expanded under pressurized gas, affects the cavity size and shape, and therefore also the effectiveness of the charging process itself. An investigation of charging mechanisms, as well as of mechanical treatment, is therefore fundamental for optimizing the ferro- and piezo-electret properties. The aim of this paper is to discuss the effect of the physical dimension of the cavities on the charging behavior of cellular ferroelectrets and to focus on the time-temperature stability for two families of polymeric cellular ferroelectrets based on polypropylene (PP) and on a cyclo-olefin copolymer (COC). Emphasis will be given to the stretching process and in particular to the expansion rate applied during the manufacturing process (which affects the radial dimension and the height of the cavities, respectively). Space-charge and partial-discharge measurements as a function of time and temperature are the main tools to infer the influence of the cavity size on charging and stability characteristics.}, language = {en} } @article{SaalfrankNestAndrianovetal.2006, author = {Saalfrank, Peter and Nest, Mathias and Andrianov, Igor V. and Klamroth, Tillmann and Kroner, Dominic and Beyvers, Stephanie}, title = {Quantum dynamics of laser-induced desorption from metal and semiconductor surfaces, and related phenomena}, volume = {18}, number = {30}, publisher = {IOP Publ.}, address = {Bristol}, issn = {1361-648X}, doi = {10.1088/0953-8984/18/30/S05}, pages = {S1425 -- S1459}, year = {2006}, abstract = {Recent progress towards a quantum theory of laser-induced desorption and related phenomena is reviewed, for specific examples. These comprise the photodesorption of NO from Pt(111), the scanning tunnelling microscope and laser- induced desorption and switching of H at Si(100), and the electron stimulated desorption and dissociation of CO at Ru(0001). The theoretical methods used for nuclear dynamics range from open-system density matrix theory over nonadiabatically coupled multi-state models to electron-nuclear wavepackets. Also, aspects of time-dependent spectroscopy to probe ultrafast nonadiabatic processes at surfaces will be considered for the example of two-photon photoemission of solvated electrons in ice layers on Cu(111)}, language = {en} } @article{MittalPorcasWucknitzetal.2006, author = {Mittal, Rupal and Porcas, Richard and Wucknitz, Olaf and Biggs, Andy D. and Browne, Ian W. A.}, title = {VLBI phase-reference observations of the gravitational lens JVAS B0218+357}, doi = {10.1051/0004-6361:20054012}, year = {2006}, abstract = {We present the results of phase-referenced VLBA+Effelsberg observations at five frequencies of the double-image gravitational lens WAS B0218+357, made to establish the precise registration of the A and B lensed image positions. The motivation behind these observations is to investigate the anomalous variation of the image flux-density ratio (A[B) with frequency - this ratio changes by almost a factor of two over a frequency range from 1.65 GHz to 15.35 GHz. We investigate whether frequency dependent image positions, combined with a magnification gradient across the image field, could give rise to the anomaly. Our observations confirm the variation of image flux-density ratio with frequency. The results from Our phase-reference astrometry, taken together with the lens mass model of Wucknitz et al. (2004, MNRAS, 349, 14), show that shifts of the image peaks and centroids are too small to account for the observed frequency- dependent ratio}, language = {en} } @article{LiSunKurths2006, author = {Li, Changpin and Sun, Weigang and Kurths, J{\"u}rgen}, title = {Synchronization of complex dynamical networks with time delays}, issn = {0378-4371}, doi = {10.1016/j.physa.2005.07.007}, year = {2006}, abstract = {In the present paper, two kinds of dynamical complex networks are considered. The first is that elements of every node have different time delays but all nodes in Such networks have the same time-delay vector. The second is that different nodes have different time-delay vectors, and the elements of each node also have different time delays. Corresponding synchronization theorems are established. Numerical examples show the efficiency of the derived theorems.}, language = {en} } @article{LeitenbergerPietsch2007, author = {Leitenberger, Wolfram and Pietsch, Ullrich}, title = {A monolithic Fresnel bimirror for hard X-rays and its application for coherence measurements}, issn = {0909-0495}, doi = {10.1107/S0909049507003846}, year = {2007}, abstract = {Experiments using a simple X-ray interferometer to measure the degree of spatial coherence of hard X-rays are reported. A monolithic Fresnel bimirror is used at small incidence angles to investigate synchrotron radiation in the energy interval 5-50 keV with monochromatic and white beam. The experimental setup was equivalent to a Young's double-slit experiment for hard X-rays with slit dimensions in the micrometre range. From the high-contrast interference pattern the degree of coherence was determined.}, language = {en} } @article{ThielRomanoKurths2006, author = {Thiel, Marco and Romano, Maria Carmen and Kurths, J{\"u}rgen}, title = {Spurious structures in recurrence plots induced by embedding}, doi = {10.1007/s11071-006-2010-9}, year = {2006}, abstract = {In this paper we show that delay embedding produces spurious structures in a recurrence plot (RP) that are not present in the real attractor. We analyze typical sets of simulated data, such as white noise and data from the chaotic Rossler system to show the relevance of this effect. In the second part of the paper we show that the second order Renyi entropy and the correlation dimension are dynamical invariants that can be estimated from Recurrence Plots with arbitrary embedding dimension and delay}, language = {en} } @article{TinoCacciapuotiBongsetal.2007, author = {Tino, G. M. and Cacciapuoti, L. and Bongs, K. and Bord{\´e}, Ch. J. and Bouyer, P. and Dittus, H. and Ertmer, W. and G{\"o}rlitz, A. and Inguscio, M. and Landragin, A. and Lemonde, P. and L{\"a}mmerzahl, C. and Peters, A. and Rasel, E. and Reichel, J. and Salomon, C. and Schiller, S. and Schleich, W. and Sengstock, K. and Sterr, U. and Wilkens, Martin}, title = {Atom interferometers and optical atomic clocks : new quantum sensors for fundamental physics experiments in space}, year = {2007}, abstract = {We present projects for future space missions using new quantum devices based on ultracold atoms. They will enable fundamental physics experiments testing quantum physics, physics beyond the standard model of fundamental particles and interactions, special relativity, gravitation and general relativity.}, language = {en} } @article{GoldobinPikovskij2006, author = {Goldobin, Denis S. and Pikovskij, Arkadij}, title = {Effects of delayed feedback on Kuramoto transition}, issn = {0375-9687}, doi = {10.1143/PTPS.161.43}, year = {2006}, abstract = {We develop a weakly nonlinear theory of the Kuramoto transition in an ensemble of globally coupled oscillators in presence of additional time-delayed coupling terms. We show that a linear delayed feedback not only controls the transition point, but effectively changes the nonlinear terms near the transition. A purely nonlinear delayed coupling does not effect the transition point, but can reduce or enhance the amplitude of collective oscillations}, language = {en} } @article{GarnierLaschewskyStorsberg2006, author = {Garnier, Sebastien and Laschewsky, Andr{\´e} and Storsberg, J}, title = {Polymeric surfactants : novel agents with exceptional properties}, issn = {0932-3414}, year = {2006}, abstract = {This article presents recent progress in the field of polymeric surfactants made of permanently amphiphilic block copolymers or of stimulus-sensitive ones. We highlight key points in the design of amphiphilic macromolecules, to yield polymer surfactants with tailor-made properties, as well as recently developed and still challenging application fields for this new class of surfactants. The efficiency boosting of amphiphilic block copolymers as co-surfactants in microemulsions is discussed, as are surface modification by polymer surfactants, and stabilization of dispersions. Moreover, the use of block copolymers in nanosciences is presented, for instance as a tool for nanomaterial fabrication, or for biomedical and cosmetic applications in bio-nanotechnology. Finally, self-assembly and applications of some newly developed "exotic" amphiphilic block copolymer structures as new surface-active materials will be highlighted}, language = {en} } @article{ZhangHayerAlSutietal.2006, author = {Zhang, Ning and Hayer, Anna and Al-Suti, Mohammed K. and Al-Belushi, Rayya A. and Khan, Muhammad S. and K{\"o}hler, Anna}, title = {The effect of delocalization on the exchange energy in meta- and para-linked Pt-containing carbazole polymers and monomers}, doi = {10.1063/1.2200351}, year = {2006}, abstract = {A series of novel platinum-containing carbazole monomers and polymers was synthesized and fully characterized by UV-VIS absorption, luminescence, and photoinduced absorption studies. In these compounds, a carbazole unit is incorporated into the main chain via either a para- or a meta-linkage. We discuss the effects of linkage and polymerization on the energy levels of S-1, T-1, and T-n. The S-1-T-1 splitting observed for the meta-linked monomer (0.4 eV) is only half of that in the para-linked monomer (0.8 eV). Upon polymerization, the exchange energy in the para- linked compound reduces, yet still remains larger than in the meta-linked polymer. We attribute the difference in exchange energy to the difference in wave function overlap between electron and hole in these compounds. (c) 2006 American Institute of Physics}, language = {en} }