2,158 research outputs found
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
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Notch pathway inhibition controls myeloma bone disease in the murine MOPC315.BM model
Despite evidence that deregulated Notch signalling is a master regulator of multiple myeloma (MM) pathogenesis, its contribution to myeloma bone disease remains to be resolved. Notch promotes survival of human MM cells and triggers human osteoclast activity in vitro. Here, we show that inhibition of Notch through the Îł-secretase inhibitor XII (GSI XII) induces apoptosis of murine MOPC315.BM myeloma cells with high Notch activity. GSI XII impairs murine osteoclast differentiation of receptor activator of NF-ÎșB ligand (RANKL)-stimulated RAW264.7 cells in vitro. In the murine MOPC315.BM myeloma model GSI XII has potent anti-MM activity and reduces osteolytic lesions as evidenced by diminished myeloma-specific monoclonal immunoglobulin (Ig)-A serum levels and quantitative assessment of bone structure changes via high-resolution microcomputed tomography scans. Thus, we suggest that Notch inhibition through GSI XII controls myeloma bone disease mainly by targeting Notch in MM cells and possibly in osteoclasts in their microenvironment. We conclude that Notch inhibition is a valid therapeutic strategy in MM
Quality of life and well-being of carers of people with dementia: are there differences between working and nonworking carers? Results from the IDEAL program
The aim of this study was to identify the differences in quality of life (QoL) and well-being between working and nonworking dementia carers and the relative contribution of psychological characteristics, caregiving experience, and social support. Multiple regressions modeled the contribution of working status, caregiver experiences, and psychological and social resources to carer QoL (EQ-5D) and well-being (WHO-5). After controlling for age, gender, carerâdyad relationship, and severity of dementia, working status contributed significant variance to EQ-5D (2%) but not to WHO-5 scores. Independent of working status, higher self-esteem and reduced stress contributed to variance in both models. Self-efficacy, social support, and positive perceptions of caregiving additionally contributed to higher WHO-5 scores. Working status associated with higher EQ-5D QoL; this may reflect the sustained sense of independence associated with supported work opportunities for carers. Outside of working status, the findings support the importance of psychological and social factors as targets to improved mental health for dementia carers
Structural mechanism of GTPase-powered ribosome-tRNA movement
GTPases are regulators of cell signaling acting as molecular switches. The translational GTPase EF-G stands out, as it uses GTP hydrolysis to generate force and promote the movement of the ribosome along the mRNA. The key unresolved question is how GTP hydrolysis drives molecular movement. Here, we visualize the GTPase-powered step of ongoing translocation by time-resolved cryo-EM. EF-G in the active GDPâPi form stabilizes the rotated conformation of ribosomal subunits and induces twisting of the sarcin-ricin loop of the 23âS rRNA. Refolding of the GTPase switch regions upon Pi release initiates a large-scale rigid-body rotation of EF-G pivoting around the sarcin-ricin loop that facilitates back rotation of the ribosomal subunits and forward swiveling of the head domain of the small subunit, ultimately driving tRNA forward movement. The findings demonstrate how a GTPase orchestrates spontaneous thermal fluctuations of a large RNA-protein complex into force-generating molecular movement
Neuer Anlauf fĂŒr die Eurozone: drei MaĂnahmen wĂŒrden kurzfristige Risiken mildern und die Chance auf eine notwendige Vertragsreform verbessern
Auch wenn sich die Krise in der Eurozone vordergrĂŒndig beruhigt hat, bestehen nach wie vor groĂe Risiken im Bereich der Staatsfinanzen, im Bankensektor und durch soziale und politische InstabilitĂ€ten. Die neue Bundesregierung sollte hierauf zunĂ€chst mit drei Initiativen reagieren. Erster Schritt wĂ€re eine Neuausrichtung der deutschen Wirtschaftspolitik. Mehr Investitionen, eine Liberalisierung des Dienstleistungssektors sowie eine StĂ€rkung der grenzĂŒberschreitenden ArbeitskrĂ€ftemobilitĂ€t wĂŒrden der deutschen Wirtschaft nutzen und den Abbau makroökonomischer Ungleichgewichte in der Eurozone fördern. Zweitens sollte die Bundesregierung einer Bankenunion mit einem zentralen Abwicklungsmechanismus zustimmen, der eine Konsolidierung des europĂ€ischen Bankensystems erlaubt und die Fragmentierung im europĂ€ischen Finanzmarkt umkehren könnte. Drittens wĂŒrden eine Wachstumsinitiative und ein europĂ€ischer Jugendbildungsfonds einer »verlorenen Generation« Perspektiven eröffnen. Dieses MaĂnahmenbĂŒndel wĂŒrde die Voraussetzungen fĂŒr eine spĂ€tere, politische Vertiefung der Eurozone verbessern: Demokratisch legitimierte Entscheidungsstrukturen, die nur ĂŒber eine Vertragsreform umzusetzen sind, sollten den in der Krise erstarkten Intergouvernementalismus ablösen. (Autorenreferat
A new polymorph of N-phenylÂphthalimide
During an attempt to prepare a cocrystal of N-phenylÂphthalimide, C14H9NO2, with N-(2,3,4,5,6-pentaÂfluoroÂphenÂyl)phthalimide, a new orthoÂrhomÂbic polymorph of the first component was obtained. This new form has ZâČ = 0.5 and the molÂecule is located around a twofold axis, whereas in the previously reported polymorph (space group Pbca), the molÂecule has no crystallographically imposed symmetry. Pairs of CâHâŻO interÂactions between inversion-related phthalimide units arrange molÂecules into tapes that are further assembled into (010) layers via stacking interÂactions between phthalimide fragments [interÂplanar distance = 3.37â
(5)â
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]
The intention-behaviour gap: An empirical examination of an integrative perspective to explain exercise behaviour
This study tested the Theory of Planned Behavior (TPB) in conjunction with two sets of variables from the Health Action Process Approach (HAPA) and the Subjective Exercise Experience Scale (SEE) to predict exercise behavior. This study included 454 participants who exercised in a fitness center. We collected measures of the TPB (attitudes, subjective norms, perceived behavioral control, and intention), HAPA (planning), and SEE (positive well-being, psychological distress, and fatigue) and assessed exercise behavior at a three-month follow-up. Structural equation modeling found partial support for the TPB model (explaining 10% of the variance in exercise behavior) and adequate fit indices for an adjusted model of the TPB that includes a positive well-being dimension (explaining 11% of the variance in exercise behavior). In sum, the original TPB partially predicts exercise behavior; when considered together with other predictors, limited evidence was found for its utility in explaining exercise behavior.This study was conducted at Psychology Research Centre (UID/PSI/01662/2013), University of Minho, and supported by the Portuguese Foundation for Science and Technology and the Portuguese Ministry of Science, Technology and Higher Education through national funds and co-financed by FEDER through COMPETE2020 under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007653).info:eu-repo/semantics/submittedVersio
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