Multi-field modelling and simulation of large deformation ductile fracture

In the present contribution we focus on a phase-field approach to ductile fracture applied to large deformation contact problems. Phase-field approaches to fracture allow for an efficient numerical investigation of complex three-dimensional fracture problems, as they arise in contact and impact situations. To account for large deformations the underlying formulation is based on a multiplicative decomposition of the deformation gradient into an elastic and plastic part. Moreover, we make use of a fourth-order crack regularization combined with gradient plasticity. Eventually, a demonstrative example shows the capability of the proposed framework

Expectations of gains in the second half of life: a study of personal conceptions of enrichment in a lifespan perspective

Item does not contain fulltextThis research focuses on cognitive representations of the personal future during the second half of life. To investigate the developmental perspectives of people growing older, the anticipation of possible gains is studied. The participants of this study took part in the German Aging Survey and the sample comprises 2,934 subjects aged 40–85 years. To assess their anticipated ‘gains’, we selected the future-related items from the SELE-questionnaire, a sentence completion instrument administered for the Survey. We assumed that many would anticipate further enrichment by new social and societal activities in retirement, but the most frequently-mentioned gains referred to changes in life style and leisure activities, especially travelling. Plans and wishes feature a predominantly leisure-oriented life style. Among the anticipations, those concerned with generativity – caring for others, societal commitment, vocational ambitions – substantially decrease at about the age of 50 years. It was hypothesised that age, gender, living in the former East or West Germany, health, education, income, and perceived control would influence the cognitive representation of the future. To examine the effects of these personal and situational factors on gain anticipations, multiple regression analyses were performed. With respect to all independent variables, differences in the kinds of expected gains were found. The outcomes are discussed with reference to lifespan developmental theory and the role of older people in society

Personal concepts of stability in the second half of life

The study contributes to the conceptualization of stability in the development of later life by answering four questions: Are there certain concepts of no-change in the population of aging adults? What are the issues that people combine with the idea of no-change? Are the issues of different importance for different groups? What kind of time perspective is expressed in their expectations of no-change? Stability expectations were investigated within a representative sample of about 2934 Germans aged 40-85 who live independently in the community. By means of a sentence completion instrument subjects provided spontaneous statements about self and life conceptions. Content analysis indicated clearly two different concepts of stability among the respondents in the second half of life: One concerns the continuation of gains, the other the maintenance of the status quo. One third of the expectations deals with further gains. Two thirds of the statements, however, refers to the maintenance of the status quo. Expected maintenance of the status quo showed a strong association with older age. In terms of Raynor's [Raynor, J. O. (1982). A theory of personal functioning and change. In J. O. Raynor &amp; E. Entin (Eds.), Motivation, career striving and aging (pp. 249-302). Washington: Hemisphere Publishing Corporation] theory of the time-bound sense of self, the concept 'continuation of gains' reflects a future sense of self, while the concept 'maintenance of the status quo' refers to a more present sense of self. (C) 2003 Elsevier Inc. All rights reserved.</p

A DARPin-based molecular toolset to probe gephyrin and inhibitory synapse biology

Neuroscience currently requires the use of antibodies to study synaptic proteins, where antibody binding is used as a correlate to define the presence, plasticity, and regulation of synapses. Gephyrin is an inhibitory synaptic scaffolding protein used to mark GABAergic and glycinergic postsynaptic sites. Despite the importance of gephyrin in modulating inhibitory transmission, its study is currently limited by the tractability of available reagents. Designed Ankyrin Repeat Proteins (DARPins) are a class of synthetic protein binder derived from diverse libraries by in vitro selection, and tested by high-throughput screening to produce specific binders. In order to generate a functionally diverse toolset for studying inhibitory synapses, we screened a DARPin library against gephyrin mutants representing both phosphorylated and dephosphorylated states. We validated the robust use of anti-gephyrin DARPin clones for morphological identification of gephyrin clusters in rat neuron culture and mouse brain tissue, discovering previously overlooked clusters. This DARPin-based toolset includes clones with heterogenous gephyrin binding modes that allowed for identification of the most extensive gephyrin interactome to date, and defined novel classes of putative interactors, creating a framework for understanding gephyrin's non-synaptic functions. This study demonstrates anti-gephyrin DARPins as a versatile platform for studying inhibitory synapses in an unprecedented manner

The Influence of Quadrature Errors on Isogeometric Mortar Methods

Mortar methods have recently been shown to be well suited for isogeometric analysis. We review the recent mathematical analysis and then investigate the variational crime introduced by quadrature formulas for the coupling integrals. Motivated by finite element observations, we consider a quadrature rule purely based on the slave mesh as well as a method using quadrature rules based on the slave mesh and on the master mesh, resulting in a non-symmetric saddle point problem. While in the first case reduced convergence rates can be observed, in the second case the influence of the variational crime is less significant

Bures volume of the set of mixed quantum states

We compute the volume of the N^2-1 dimensional set M_N of density matrices of size N with respect to the Bures measure and show that it is equal to that of a N^2-1 dimensional hyper-halfsphere of radius 1/2. For N=2 we obtain the volume of the Uhlmann 3-D hemisphere, embedded in R^4. We find also the area of the boundary of the set M_N and obtain analogous results for the smaller set of all real density matrices. An explicit formula for the Bures-Hall normalization constants is derived for an arbitrary N.Comment: 15 revtex pages, 2 figures in .eps; ver. 3, Eq. (4.19) correcte

Effective lattice theories for Polyakov loops

We derive effective actions for SU(2) Polyakov loops using inverse Monte Carlo techniques. In a first approach, we determine the effective couplings by requiring that the effective ensemble reproduces the single-site distribution of the Polyakov loops. The latter is flat below the critical temperature implying that the (untraced) Polyakov loop is distributed uniformly over its target space, the SU(2) group manifold. This allows for an analytic determination of the Binder cumulant and the distribution of the mean-field, which turns out to be approximately Gaussian. In a second approach, we employ novel lattice Schwinger-Dyson equations which reflect the SU(2) x SU(2) invariance of the functional Haar measure. Expanding the effective action in terms of SU(2) group characters makes the numerics sufficiently stable so that we are able to extract a total number of 14 couplings. The resulting action is short-ranged and reproduces the Yang-Mills correlators very well.Comment: 27 pages, 8 figures, v2: method refined, chapter and references adde

BioSecure: white paper for research in biometrics beyond BioSecure

This report is the output of a consultation process of various major stakeholders in the biometric community to identify the future biometrical research issues, an activity which employed not only researchers but representatives from the entire biometrical community, consisting of governments, industry, citizens and academia. It is one of the main efforts of the BioSecure Network of Excellence to define the agenda for future biometrical research, including systems and applications scenarios

Transport limits in defect-engineered LaAlO3/SrTiO3 bilayers

The electrical properties of the metallic interface in LaAlO3/SrTiO3 (LAO/STO) bilayers are investigated with focus on the role of cationic defects in thin film STO. Systematic growth-control of the STO thin film cation stoichiometry (defect-engineering) yields a relation between cationic defects in the STO layer and electronic properties of the bilayer-interface. Hall measurements reveal a stoichiometry-effect primarily on the electron mobility. The results indicate an enhancement of scattering processes in as-grown non-stoichiometric samples indicating an increased density of defects. Furthermore, we discuss the thermodynamic processes and defect-exchange reactions at the LAO/STO-bilayer interface determined in high temperature equilibrium. By quenching defined defect states from high temperature equilibrium, we finally connect equilibrium thermodynamics with room temperature transport. The results are consistent with the defect-chemistry model suggested for LAO/STO interfaces. Moreover, they reveal an additional healing process of extended defects in thin film STO

Covariance and Fisher information in quantum mechanics

Variance and Fisher information are ingredients of the Cramer-Rao inequality. We regard Fisher information as a Riemannian metric on a quantum statistical manifold and choose monotonicity under coarse graining as the fundamental property of variance and Fisher information. In this approach we show that there is a kind of dual one-to-one correspondence between the candidates of the two concepts. We emphasis that Fisher informations are obtained from relative entropies as contrast functions on the state space and argue that the scalar curvature might be interpreted as an uncertainty density on a statistical manifold.Comment: LATE