Fluid Induced Particle Size Segregation in Sheared Granular Assemblies

We perform a two-dimensional molecular-dynamics study of a model for sheared bidisperse granular systems under conditions of simple shear and Poiseuille flow. We propose a mechanism for particle-size segregation based on the observation that segregation occurs if the viscous length scale introduced by a liquid in the system is smaller than of the order of the particle size. We show that the ratio of shear rate to viscosity must be small if one wants to find size segregation. In this case the particles in the system arrange themselves in bands of big and small particles oriented along the direction of the flow. Similarly, in Poiseuille flow we find the formation of particle bands. Here, in addition, the variety of time scales in the flow leads to an aggregation of particles in the zones of low shear rate and can suppress size segregation in these regions. The results have been verified against simulations using a full Navier-Stokes description for the liquid.Comment: 11 pages, REVTEX format, ps figures compressed uuencoded separately or by e-mail from [email protected]. A postscript version of the paper will be available from http://www.ica1.uni-stuttgart.de/local/WWW/papers/papers.htm

Effect of Inhibition of Colony Stimulating Factor 1 Receptor on Choroidal Neovascularization in Mice.

Neovascular age-related macular degeneration is one of the leading causes of blindness. Microglia and macrophages play critical role in choroidal neovascularization (CNV) and may therefore be potential targets to modulate the disease course. This study evaluated the effect of the colony stimulating factor-1 receptor (CSF-1R) inhibitor PLX5622 on experimental laser-induced CNV. A 98% reduction of retinal microglia cells was observed in the retina one week after initiation of PLX5622 treatment, preventing accumulation of macrophages within the laser site and leading to a reduction of leukocytes within the choroid after CNV induction. Mice treated with PLX5622 had a significantly faster decrease of the CNV lesion size as revealed by in vivo imaging and immunohistochemistry from day 3 to day 14 compared to untreated mice. Several inflammatory modulators, such as CCL9, granulocyte-macrophage colony-stimulating factor, ssoluble tumor necrosis factor receptor-I, interleukin-1α, and matrix metallopeptidase-2 were elevated in the acute phase of the disease when microglia were ablated with PLX5622, whereas other cytokines (eg, interferon-γ, interleukin-4, and interleukin-10) were reduced. Our results suggest that CSF-1R inhibition may be a novel therapeutic target in patients with neovascular age-related macular degeneration

Soliton trains in Bose-Fermi mixtures

We theoretically consider the formation of bright solitons in a mixture of Bose and Fermi degenerate gases. While we assume the forces between atoms in a pure Bose component to be effectively repulsive, their character can be changed from repulsive to attractive in the presence of fermions provided the Bose and Fermi gases attract each other strongly enough. In such a regime the Bose component becomes a gas of effectively attractive atoms. Hence, generating bright solitons in the bosonic gas is possible. Indeed, after a sudden increase of the strength of attraction between bosons and fermions (realized by using a Feshbach resonance technique or by firm radial squeezing of both samples) soliton trains appear in the Bose-Fermi mixture.Comment: 4 pages, 4 figure

Self-rated mentalizing mediates the relationship between stress and coping in a non-clinical sample

Background: The clinical concept of mentalizing has recently been extended into non-clinical contexts. In particular, the protective function of robust mentalizing as a processing capacity of interpersonal and intrapsychic events has become a focus of consideration. Theoretical approaches hypothesize that mentalizing may allow for an adequate self-awareness in the face of aversive experiences such as stress, leading to a reappraisal of these experiences and therefore enables the use of adaptive coping behaviors. Objective: The study aimed to investigate the association between coping behavior, mentalizing and experiences of stress. Method: 534 healthy adults completed the German-language Stress Processing Questionnaire (SVF), the Mentalization Questionnaire (MZQ), and a short scale of the Trierer Inventory of Chronic Stress (TICS) in a cross-sectional research design. Results: Correlational analyses suggested associations between coping and mentalizing. Furthermore, MZQ scores predicted both positive and negative coping behavior. The relationship between stress and both negative and positive coping was mediated by mentalizing capacity. Conclusion: Findings confirm the hypothesis that mentalizing may represent a coping resource within a resilience framework. An implementation of the concept in preventive mental health interventions is discussed

Delayed Gastric Emptying in Patients with Prader Willi Syndrome

Background: A 15 year old girl with Prader-Willi Syndrome (PWS) died of gastric rupture. Systematic literature research revealed seven case reports of PWS patients with acute gastric dilatation, two had a lethal course. The objective of this study was to determine if delayed gastric emptying in PWS patients might contribute to gastric dilatation. Methods: Gastric emptying was measured in eight patients with PWS by nucleotid scintigraphy after a standardized test meal. Results: Median age was 17.8 years (range 10.1-19.5). Median BMI of the male patients was 29.5 (range 18.4-34.8), of the female patients 28 (range 20.0-44.8). Half time of gastric emptying was delayed in five of the eight patients (median 78.5 minutes, range 59-134). Conclusion: Scintigraphic measurement of gastric emptying in eight PWS patients revealed delay in comparison to normal values. This might be a risk factor for gastric dilatation and rupture in patients with PW

Steric Hindrance of NH3 Diffusion on Pt(111) by Co-Adsorbed O-Atoms

A detailed velocity-resolved kinetics study of NH3 thermal desorption rates from p(2 × 2) O/Pt(111) is presented. We find a large reduction in the NH3 desorption rate due to adsorption of O-atoms on Pt(111). A physical model describing the interactions between adsorbed NH3 and O-atoms explains these observations. By fitting the model to the derived desorption rate constants, we find an NH3 stabilization on p(2 × 2) O/Pt(111) of 0.147–0.014+0.023 eV compared to Pt(111) and a rotational barrier of 0.084–0.022+0.049 eV, which is not present on Pt(111). The model also quantitatively predicts the steric hindrance of NH3 diffusion on Pt(111) due to co-adsorbed O-atoms. The derived diffusion barrier of NH3 on p(2 × 2) O/Pt(111) is 1.10–0.13+0.22 eV, which is 0.39–0.14+0.22 eV higher than that on pristine Pt(111). We find that Perdew Burke Ernzerhof (PBE) and revised Perdew Burke Ernzerhof (RPBE) exchange–correlation functionals are unable to reproduce the experimentally observed NH3–O adsorbate–adsorbate interactions and NH3 binding energies at Pt(111) and p(2 × 2) O/Pt(111), which indicates the importance of dispersion interactions for both systems

Multimodal imaging of experimental choroidal neovascularization.

AIM To compare choroidal neovascularization (CNV) lesion measurements obtained by in vivo imaging modalities, with whole mount histological preparations stained with isolectin GS-IB4, using a murine laser-induced CNV model. METHODS B6N.Cg-Tg(Csf1r-EGFP)1Hume/J heterozygous adult mice were subjected to laser-induced CNV and were monitored by fluorescein angiography (FA), multicolor (MC) fundus imaging and optical coherence tomography angiography (OCTA) at day 14 after CNV induction. Choroidal-retinal pigment epithelium (RPE) whole mounts were prepared at the end of the experiment and were stained with isolectin GS-IB4. CNV areas were measured in all different imaging modalities at day 14 after CNV from three independent raters and were compared to choroidal-RPE whole mounts. Intraclass correlation coefficient (ICC) type 2 (2-way random model) and its 95% confidence intervals (CI) were calculated to measure the correlation between different raters' measurements. Spearman's rank correlation coefficient (Spearman's r) was calculated for the comparison between FA, MC and OCTA data and histology data. RESULTS FA (early and late) and MC correlates well with the CNV measurements ex vivo with FA having slightly better correlation than MC (FA early Spearman's r=0.7642, FA late Spearman's r=0.7097, and MC Spearman's r=0.7418), while the interobserver reliability was good for both techniques (FA early ICC=0.976, FA late ICC=0.964, and MC ICC=0.846). In contrast, OCTA showed a poor correlation with ex vivo measurements (Spearman's r=0.05716) and high variability between different raters (ICC=0.603). CONCLUSION This study suggests that FA and MC imaging could be used for the evaluation of CNV areas in vivo while caution must be taken and comparison studies should be performed when OCTA is employed as a CNV monitoring tool in small rodents