1,744 research outputs found
Unidirectional hopping transport of interacting particles on a finite chain
Particle transport through an open, discrete 1-D channel against a mechanical
or chemical bias is analyzed within a master equation approach. The channel,
externally driven by time dependent site energies, allows multiple occupation
due to the coupling to reservoirs. Performance criteria and optimization of
active transport in a two-site channel are discussed as a function of reservoir
chemical potentials, the load potential, interparticle interaction strength,
driving mode and driving period. Our results, derived from exact rate
equations, are used in addition to test a previously developed time-dependent
density functional theory, suggesting a wider applicability of that method in
investigations of many particle systems far from equilibrium.Comment: 33 pages, 8 figure
Rate- and State-Dependent Friction Law and Statistical Properties of Earthquakes
In order to clarify how the statistical properties of earthquakes depend on
the constitutive law characterizing the stick-slip dynamics, we make an
extensive numerical simulation of the one-dimensional spring-block model with
the rate- and state-dependent friction law. Both the magnitude distribution and
the recurrence-time distribution are studied with varying the constitutive
parameters characterizing the model. While a continuous spectrum of seismic
events from smaller to larger magnitudes is obtained, earthquakes described by
this model turn out to possess pronounced ``characteristic'' features.Comment: Minor revisions are made in the text and in the figures. Accepted for
publication in Europhys. Letter
Pristionchus pacificus genomics: from genetics to genome sequence
Satellite systems are proving to be important players in understanding the differences between ontogenies during evolution. The satellite system P. pacificus, since its discovery nearly a decade ago (Sommer et al., 1996), has provided developmental biologists with new insights into various developmental processes (Eizinger and Sommer, 1997; Jungblut and Sommer, 1998; Sigrist and Sommer, 1999; Zheng et al., 2005). Further understanding of these developmental processes necessitated a genomic framework. Generation of an integrated genetic linkage map and a physical map for mapping of mutants has set a good foundation for such molecular studies (Srinivasan et al., 2003; Srinivasan et al., 2002). With the impending genome sequence being generated by the Washington Genome sequencing center (WUGSC) funded by NHGRI, P. pacificus is bound to cross the ‘next frontier’ in our understanding of evolution of developmental and behavioral processes. This review highlights the current status of P. pacificus genomics
Increasing dependence on industry-funded research creates higher risk of biased reporting in medical physics
No abstract availabl
Developments in CORG: a gene-centric comparative genomics resource
The CORG resource (Comparative Regulatory Genomics, ) provides extensive cross-species comparisons of promoter regions in particular and whole gene loci in general. Pairwise as well as multiple alignments of 10 vertebrate species form the key component of CORG. We implemented a rapid alignment approach based on weight matrix motif anchors to ensure efficient computation and biologically informative alignments. All CORG workbench components have been enhanced towards more flexibility and interactivity. Reference sequence based data presentation and analysis was put into the well-known and modular Generic Genome Browser framework. Herein, various plugins facilitate online data analysis and integration with static conservation data. Main emphasis was put on the design of a new JAVA WebStart application for comparative data display. Flexible data import and export options for standard formats complete the provided services
Unified Description of Aging and Rate Effects in Yield of Glassy Solids
The competing effects of slow structural relaxations (aging) and deformation
at constant strain rate on the shear yield stress of simple model
glasses are examined using molecular simulations. At long times, aging leads to
a logarithmic increase in density and . The yield stress also rises
logarithmically with rate, but shows a sharp transition in slope at a rate that
decreases with increasing age. We present a simple phenomenological model that
includes both intrinsic rate dependence and the change in properties with the
total age of the system at yield. As predicted by the model, all data for each
temperature collapse onto a universal curve.Comment: 4 pages, 3 figure
Teaching old NCATs new tricks: using non-canonical amino acid tagging to study neuronal plasticity
The non-canonical amino acid labeling techniques BONCAT (bioorthogonal non-canonical amino acid tagging) and FUNCAT (fluorescent non-canonical amino acid tagging) enable the specific identification and visualization of newly synthesized proteins. Recently, these techniques have been applied to neuronal systems to elucidate protein synthesis dynamics during plasticity, identify stimulation-induced proteomes and subproteomes and to investigate local protein synthesis in specific subcellular compartments. The next generation of tools and applications, reviewed here, includes the development of new tags, the quantitative identification of newly synthesized proteins, the application of NCAT to whole animals, and the ability to genetically restrict NCAT labeling. These techniques will enable not only improved detection but also allow new scientific questions to be tackled
PET-CT-Analyse von Patienten mit POCD:eine Pilotstudie
Die Diagnostik der post-operativen kognitiven Dysfunktion (POCD) beruht bisher auf der Analyse nicht-standardisierter Testbatterien. Das Ziel dieser Pilot-Studie war es deshalb zu untersuchen, ob im ZNS-Stoffwechsel von POCD-Patienten Auffälligkeiten im Sinne eines organischen Korrelats zu den verschlechterten Testergebnissen gefunden werden können. Zunächst wurden chirurgische Patienten der Universität Münster mit Hilfe einer neuropsychologischen Test-Batterie hinsichtlich der Entwicklung einer POCD untersucht. Von insgesamt 70 Patienten wurden 21 mit einer POCD diagnostiziert, wobei 10 der PET-CT-Untersuchung zustimmten. In 5 Fällen konnten globale, unspezifische Stoffwechselstörungen nachgewiesen werden, die als pathologisch eingestuft wurden. Es konnte jedoch weder ein für die POCD charakteristisches Muster, noch eine Übereinstimmung mit dem typischen PET-Befund einer Erkrankung anderer Genese, wie der Alzheimer Demenz, aufgezeigt werden
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