Tube Models for Rubber-Elastic Systems

In the first part of the paper we show that the constraining potentials introduced to mimic entanglement effects in Edwards' tube model and Flory's constrained junction model are diagonal in the generalized Rouse modes of the corresponding phantom network. As a consequence, both models can formally be solved exactly for arbitrary connectivity using the recently introduced constrained mode model. In the second part, we solve a double tube model for the confinement of long paths in polymer networks which is partially due to crosslinking and partially due to entanglements. Our model describes a non-trivial crossover between the Warner-Edwards and the Heinrich-Straube tube models. We present results for the macroscopic elastic properties as well as for the microscopic deformations including structure factors.Comment: 15 pages, 8 figures, Macromolecules in pres

Advances in methods to obtain and characterise room temperature magnetic ZnO

We report the existence of magnetic order at room temperature in Li-doped ZnO microwires after low energy H+ implantation. The microwires with diameters between 0.3 and 10 μm were prepared by a carbothermal process. We combine spectroscopy techniques to elucidate the influence of the electronic structure and local environment of Zn, O, and Li and their vacancies on the magnetic response. Ferromagnetism at room temperature is obtained only after implanting H+ in Li-doped ZnO. The overall results indicate that low-energy proton implantation is an effective method to produce the necessary amount of stable Zn vacancies near the Li ions to trigger the magnetic order.Fil: Lorite, I.. Fakultät für Physik und Geowissenschaften; AlemaniaFil: Straube, Benjamin. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ohldag, H.. University Of Stanford; Estados UnidosFil: Kumar, P.. Fakultät für Physik und Geowissenschaften; AlemaniaFil: Villafuerte, Manuel Jose. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Esquinazi, P.. Fakultät für Physik und Geowissenschaften; AlemaniaFil: Rodriguez Torres, Claudia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Física La Plata; ArgentinaFil: Perez de Huelani, S.. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Física. Laboratorio de Física del Solido; ArgentinaFil: Antonov, V. N.. Institute for Metal Physics; Ucrania. Max Planck Institut für Mikrostrukturphysik; AlemaniaFil: Bekenov, L. V.. Institute for Metal Physics; Ucrania. Max Planck Institut für Mikrostrukturphysik; AlemaniaFil: Ernst, A.. Max Planck Institut für Mikrostrukturphysik; Alemania. Universitat Leipzig; AlemaniaFil: Hoffmann, M.. Max Planck Institut für Mikrostrukturphysik; Alemania. Martin Luther University Halle-Wittenberg; AlemaniaFil: Nayak, S. K.. Martin Luther University Halle-Wittenberg; AlemaniaFil: Adeagbo, W. A.. Martin Luther University Halle-Wittenberg; AlemaniaFil: Fischer, G.. Max Planck Institut für Mikrostrukturphysik; AlemaniaFil: Hergert. W.. Martin Luther University Halle-Wittenberg; Alemani

On the Lebesgue measure of Li-Yorke pairs for interval maps

We investigate the prevalence of Li-Yorke pairs for $C^2$ and $C^3$ multimodal maps $f$ with non-flat critical points. We show that every measurable scrambled set has zero Lebesgue measure and that all strongly wandering sets have zero Lebesgue measure, as does the set of pairs of asymptotic (but not asymptotically periodic) points. If $f$ is topologically mixing and has no Cantor attractor, then typical (w.r.t. two-dimensional Lebesgue measure) pairs are Li-Yorke; if additionally $f$ admits an absolutely continuous invariant probability measure (acip), then typical pairs have a dense orbit for $f \times f$. These results make use of so-called nice neighborhoods of the critical set of general multimodal maps, and hence uniformly expanding Markov induced maps, the existence of either is proved in this paper as well. For the setting where $f$ has a Cantor attractor, we present a trichotomy explaining when the set of Li-Yorke pairs and distal pairs have positive two-dimensional Lebesgue measure.Comment: 41 pages, 3 figure

Euro+Med-Checklist Notulae, 13

This is the thirteenth of a series of miscellaneous contributions, by various authors, where hitherto unpublished data relevant to both the Med-Checklist and the Euro+Med (or Sisyphus) projects are presented. This instalment deals with the families Amaryllidaceae (incl. Alliaceae), Apocynaceae, Caryophyllaceae, Chenopodiaceae, Compositae, Crassulaceae, Cucurbitaceae, Gramineae, Hydrocharitaceae, Iridaceae, Labiatae, Liliaceae, Malvaceae, Meliaceae, Myrtaceae, Orobanchaceae, Oxalidaceae, Papaveraceae, Pittosporaceae, Primulaceae (incl. Myrsinaceae), Ranunculaceae, Rhamnaceae, Rubiaceae, Solanaceae and Umbelliferae. It includes new country and area records and taxonomic and distributional considerations for taxa in Allium, Anthemis, Atriplex, Centaurea, Chasmanthe, Chenopodium, Delphinium, Digitaria, Elodea, Erigeron, Eucalyptus, Hypecoum, Leptorhabdos, Luffa, Malvaviscus, Melia, Melica, Momordica, Nerium, Oxalis, Pastinaca, Phelipanche, Physalis, Pittosporum, Salvia, Scorzoneroides, Sedum, Sesleria, Silene, Spartina, Stipa, Tulipa and Ziziphus, new combinations in Cyanus, Lysimachia, Rhaponticoides and Thliphthisa, and the reassessment of a replacement name in Sempervivum

Neurons in the human amygdala encode face identity, but not gaze direction

The amygdala is important for face processing, and direction of eye gaze is one of the most socially salient facial signals. Recording from over 200 neurons in the amygdala of neurosurgical patients, we found robust encoding of the identity of neutral-expression faces, but not of their direction of gaze. Processing of gaze direction may rely on a predominantly cortical network rather than the amygdala

Exploring the Fundamental Dynamics of Error-Based Motor Learning Using a Stationary Predictive-Saccade Task

The maintenance of movement accuracy uses prior performance errors to correct future motor plans; this motor-learning process ensures that movements remain quick and accurate. The control of predictive saccades, in which anticipatory movements are made to future targets before visual stimulus information becomes available, serves as an ideal paradigm to analyze how the motor system utilizes prior errors to drive movements to a desired goal. Predictive saccades constitute a stationary process (the mean and to a rough approximation the variability of the data do not vary over time, unlike a typical motor adaptation paradigm). This enables us to study inter-trial correlations, both on a trial-by-trial basis and across long blocks of trials. Saccade errors are found to be corrected on a trial-by-trial basis in a direction-specific manner (the next saccade made in the same direction will reflect a correction for errors made on the current saccade). Additionally, there is evidence for a second, modulating process that exhibits long memory. That is, performance information, as measured via inter-trial correlations, is strongly retained across a large number of saccades (about 100 trials). Together, this evidence indicates that the dynamics of motor learning exhibit complexities that must be carefully considered, as they cannot be fully described with current state-space (ARMA) modeling efforts

Neuroimaging in anxiety disorders

Neuroimaging studies have gained increasing importance in validating neurobiological network hypotheses for anxiety disorders. Functional imaging procedures and radioligand binding studies in healthy subjects and in patients with anxiety disorders provide growing evidence of the existence of a complex anxiety network, including limbic, brainstem, temporal, and prefrontal cortical regions. Obviously, “normal anxiety” does not equal “pathological anxiety” although many phenomena are evident in healthy subjects, however to a lower extent. Differential effects of distinct brain regions and lateralization phenomena in different anxiety disorders are mentioned. An overview of neuroimaging investigations in anxiety disorders is given after a brief summary of results from healthy volunteers. Concluding implications for future research are made by the authors

Adaptation of eye and hand movements to target displacements of different size

Previous work has documented that the direction of eye and hand movements can be adaptively modified using the double-step paradigm. Here we report that both motor systems adapt not only to small direction steps (5° gaze angle) but also to large ones (28° gaze angle). However, the magnitude of adaptation did not increase with step size, and the relative magnitude of adaptation therefore decreased from 67% with small steps to 15% with large steps. This decreasing efficiency of adaptation may reflect the participation of directionally selective neural circuits in double-step adaptation