Interacting Multiple Try Algorithms with Different Proposal Distributions

We propose a new class of interacting Markov chain Monte Carlo (MCMC) algorithms designed for increasing the efficiency of a modified multiple-try Metropolis (MTM) algorithm. The extension with respect to the existing MCMC literature is twofold. The sampler proposed extends the basic MTM algorithm by allowing different proposal distributions in the multiple-try generation step. We exploit the structure of the MTM algorithm with different proposal distributions to naturally introduce an interacting MTM mechanism (IMTM) that expands the class of population Monte Carlo methods. We show the validity of the algorithm and discuss the choice of the selection weights and of the different proposals. We provide numerical studies which show that the new algorithm can perform better than the basic MTM algorithm and that the interaction mechanism allows the IMTM to efficiently explore the state space

String-like Clusters and Cooperative Motion in a Model Glass-Forming Liquid

A large-scale molecular dynamics simulation is performed on a glass-forming Lennard-Jones mixture to determine the nature of dynamical heterogeneities which arise in this model fragile liquid. We observe that the most mobile particles exhibit a cooperative motion in the form of string-like paths (``strings'') whose mean length and radius of gyration increase as the liquid is cooled. The length distribution of the strings is found to be similar to that expected for the equilibrium polymerization of linear polymer chains.Comment: 6 pages of RevTex, 6 postscript figures, uses epsf.st

Objective Bayesian Analysis of the Yule-Simon Distribution with Applications

The Yule-Simon distribution is usually employed in the analysis of frequency data. As the Bayesian literature, so far, has ignored this distribution, here we show the derivation of two objective priors for the parameter of the Yule--Simon distribution. In particular, we discuss the Jeffreys prior and a loss-based prior, which has recently appeared in the literature. We illustrate the performance of the derived priors through a simulation study and the analysis of real datasets

Gesundheit und Leistungsfähigkeit von Milchkühen im ökologischen Landbau interdisziplinär betrachtet – eine (Interventions-) Studie zu Stoffwechselstörungen und Eutererkrankungen unter Berücksichtigung von Grundfuttererzeugung, Fütterungsmanagement und Tierhaltung

Im Mittelpunkt des Projektes stand die Stoffwechsel- und Eutergesundheit von ökologisch gehaltenen Milchkühen im prä- und peripartalen Zeitraum sowie in den ersten 100 Laktationstagen und deren Beeinflussung durch die Futter- und Nährstoffversorgung und die Haltungsumwelt im umfassenden Sinn. In einer bundesweiten Feldstudie auf 106 ökologisch wirtschaftenden Milchviehbetrieben erfolgten Erhebungen mit dem Ziel einer Risikomodellierung zu Stoffwechsel- und Eutererkrankungen. Vor diesem Hintergrund wurden die Produktionssysteme von der Pflanzenzusammensetzung im Grünland und im Ackerfutter über die Grobfutterproduktion, Futterqualität und Rationsgestaltung, Haltungsumwelt bis hin zur Tiergesundheit und Milchqualität analysiert, um hier einzelbetriebliche Risikoeinschätzungen vorzunehmen, Optimierungspotenziale aufzuzeigen und Handlungsempfehlungen abzuleiten, die anschließend betriebsindividuell implementiert wurden. Die Effektivität des so geschaffenen präventiv orientierten Tiergesundheitsmanagements wurde anhand der Entwicklung ausgewählter Kennzahlen der Euter- und Stoffwechselgesundheit geprüft. Es konnte gezeigt werden, dass sich mit dieser Vorgehensweise auch unter Praxisbedingungen die Tiergesundheitssituation signifikant verbes-sern lässt. Die Feldstudie wurde mit experimentellen Untersuchungen ergänzt, die sich speziellen Fragen der Analyse von nXP in Grasprodukten, des Kraftfuttereinsatzes, der Wahl der geeigneten Rasse, dem Infektionsgeschehen, der Nutzung von Haltungstechniken im Fütterungsmanagement und der Verbesserung der Grasnarbe widmeten. Die im Projekt generierten, aufgrund ihrer Ableitung aus der Praxis widerspruchsarmen Erkenntnisse wurden über vielfältige Formen des Wissenstransfers an die Akteure in der Ökologischen Milchviehhaltung vermittelt. Ein Merkblatt zur Euter- und Stoffwechselgesundheit bei Biomilchkühen und ein modular aufgebautes Wissenstransferkonzept wurden erarbeitet, um die Projektergebnisse nachhaltig nutzen zu können

Population-Based Incidence and Prevalence of Systemic Lupus Erythematosus: The Michigan Lupus Epidemiology and Surveillance Program

Objective To estimate the incidence and prevalence of systemic lupus erythematosus (SLE) in a sociodemographically diverse southeastern Michigan source population of 2.4 million people. Methods SLE cases fulfilling the American College of Rheumatology classification criteria (primary case definition) or meeting rheumatologist-judged SLE criteria (secondary definition) and residing in Wayne or Washtenaw Counties during 2002–2004 were included. Case finding was performed from 6 source types, including hospitals and private specialists. Age-standardized rates were computed, and capture–recapture was performed to estimate underascertainment of cases. Results The overall age-adjusted incidence and prevalence (ACR definition) per 100,000 persons were 5.5 (95% confidence interval [95% CI] 5.0–6.1) and 72.8 (95% CI 70.8–74.8). Among females, the incidence was 9.3 per 100,000 persons and the prevalence was 128.7 per 100,000 persons. Only 7 cases were estimated to have been missed by capture–recapture, adjustment for which did not materially affect the rates. SLE prevalence was 2.3-fold higher in black persons than in white persons, and 10-fold higher in females than in males. Among incident cases, the mean ± SD age at diagnosis was 39.3 ± 16.6 years. Black SLE patients had a higher proportion of renal disease and end-stage renal disease (ESRD) (40.5% and 15.3%, respectively) as compared to white SLE patients (18.8% and 4.5%, respectively). Black patients with renal disease were diagnosed as having SLE at younger age than white patients with renal disease (mean ± SD 34.4 ± 14.9 years versus 41.9 ± 21.3 years; P = 0.05). Conclusion SLE prevalence was higher than has been described in most other population-based studies and reached 1 in 537 among black female persons. There were substantial racial disparities in the burden of SLE, with black patients experiencing earlier age at diagnosis, >2-fold increases in SLE incidence and prevalence, and increased proportions of renal disease and progression to ESRD as compared to white patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106579/1/Somers_AandR 2014_MILES SLE inc prev.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106579/3/license_rdf1611

Spatially controlled cell adhesion on three-dimensional substrates

The microenvironment of cells in vivo is defined by spatiotemporal patterns of chemical and biophysical cues. Therefore, one important goal of tissue engineering is the generation of scaffolds with defined biofunctionalization in order to control processes like cell adhesion and differentiation. Mimicking extrinsic factors like integrin ligands presented by the extracellular matrix is one of the key elements to study cellular adhesion on biocompatible scaffolds. By using special thermoformable polymer films with anchored biomolecules micro structured scaffolds, e.g. curved and µ-patterned substrates, can be fabricated. Here, we present a novel strategy for the fabrication of µ-patterned scaffolds based on the “Substrate Modification and Replication by Thermoforming” (SMART) technology: The surface of a poly lactic acid membrane, having a low forming temperature of 60°C and being initially very cell attractive, was coated with a photopatterned layer of poly(L-lysine) (PLL) and hyaluronic acid (VAHyal) to gain spatial control over cell adhesion. Subsequently, this modified polymer membrane was thermoformed to create an array of spherical microcavities with diameters of 300 µm for 3D cell culture. Human hepatoma cells (HepG2) and mouse fibroblasts (L929) were used to demonstrate guided cell adhesion. HepG2 cells adhered and aggregated exclusively within these cavities without attaching to the passivated surfaces between the cavities. Also L929 cells adhering very strongly on the pristine substrate polymer were effectively patterned by the cell repellent properties of the hyaluronic acid based hydrogel. This is the first time cell adhesion was controlled by patterned functionalization of a polymeric substrate with UV curable PLL-VAHyal in thermoformed 3D microstructures