Riemann solvers and undercompressive shocks of convex FPU chains

We consider FPU-type atomic chains with general convex potentials. The naive continuum limit in the hyperbolic space-time scaling is the p-system of mass and momentum conservation. We systematically compare Riemann solutions to the p-system with numerical solutions to discrete Riemann problems in FPU chains, and argue that the latter can be described by modified p-system Riemann solvers. We allow the flux to have a turning point, and observe a third type of elementary wave (conservative shocks) in the atomistic simulations. These waves are heteroclinic travelling waves and correspond to non-classical, undercompressive shocks of the p-system. We analyse such shocks for fluxes with one or more turning points. Depending on the convexity properties of the flux we propose FPU-Riemann solvers. Our numerical simulations confirm that Lax-shocks are replaced by so called dispersive shocks. For convex-concave flux we provide numerical evidence that convex FPU chains follow the p-system in generating conservative shocks that are supersonic. For concave-convex flux, however, the conservative shocks of the p-system are subsonic and do not appear in FPU-Riemann solutions

Cortical Resonance Frequencies Emerge from Network Size and Connectivity

Neural oscillations occur within a wide frequency range with different brain regions exhibiting resonance-like characteristics at specific points in the spectrum. At the microscopic scale, single neurons possess intrinsic oscillatory properties, such that is not yet known whether cortical resonance is consequential to neural oscillations or an emergent property of the networks that interconnect them. Using a network model of loosely-coupled Wilson-Cowan oscillators to simulate a patch of cortical sheet, we demonstrate that the size of the activated network is inversely related to its resonance frequency. Further analysis of the parameter space indicated that the number of excitatory and inhibitory connections, as well as the average transmission delay between units, determined the resonance frequency. The model predicted that if an activated network within the visual cortex increased in size, the resonance frequency of the network would decrease. We tested this prediction experimentally using the steady-state visual evoked potential where we stimulated the visual cortex with different size stimuli at a range of driving frequencies. We demonstrate that the frequency corresponding to peak steady-state response inversely correlated with the size of the network. We conclude that although individual neurons possess resonance properties, oscillatory activity at the macroscopic level is strongly influenced by network interactions, and that the steady-state response can be used to investigate functional networks

Supplementary Material for: What Kind of Patients Receive Inpatient and Day-Hospital Treatment in Departments of Psychosomatic Medicine and Psychotherapy in Germany?

Introduction: Germany is one of the few countries with a medical specialty of psychosomatic medicine and psychotherapy and many treatment resources of this kind. Objective: This observational study describes the psychosomatic treatment programs as well as a large sample of day-hospital and inpatients in great detail using structured diagnostic interviews. Methods: Mental disorders were diagnosed according to ICD-10 and DSM-IV by means of Mini-DIPS and SCID-II. In addition to the case records, a modified version of the CSSRI was employed to collect demographic data and service use. The PHQ-D was used to assess depression, anxiety, and somatization. Results: 2,094 patients from 19 departments participated in the study after giving informed consent. The sample consisted of a high proportion of “complex patients” with high comorbidity of mental and somatic diseases, severe psychopathology, and considerable social and occupational dysfunction including more than 50 days of sick leave per year in half of the sample. The most frequent diagnoses were depression, somatoform and anxiety disorders, eating disorders, personality disorders, and somato-psychic conditions. Conclusions: Inpatient and day-hospital treatment in German university departments of psychosomatic medicine and psychotherapy is an intensive multimodal treatment for complex patients with high comorbidity and social as well as occupational dysfunction

Getting the glycosylation right: Implications for the biotechnology industry

Glycosylation is the most extensive of all the posttranslational modifications, and has important functions in the secretion, antigenicity and clearance of glycoproteins. In recent years major advances have been made in the cloning of glycosyltransferase enzymes, in understanding the varied biological functions of carbohydrates, and in the accurate analysis of glycoprotein heterogeneity. In this review we discuss the impact of these advances on the choice of a recombinant host cell line, in optimizing cell culture processes, and in choosing the appropriate level of glycosylation analysis for each stage of product development