5,225 research outputs found
A PARAMETRIC INVESTIGATION OF THE LUNAR-ORBIT-RENDEZVOUS SCHEME
Lunar orbit rendezvous scheme - mission analysi
Direct conversion of rheological compliance measurements into storage and loss moduli
We remove the need for Laplace/inverse-Laplace transformations of
experimental data, by presenting a direct and straightforward mathematical
procedure for obtaining frequency-dependent storage and loss moduli
( and respectively), from time-dependent experimental
measurements. The procedure is applicable to ordinary rheological creep
(stress-step) measurements, as well as all microrheological techniques, whether
they access a Brownian mean-square displacement, or a forced compliance. Data
can be substituted directly into our simple formula, thus eliminating
traditional fitting and smoothing procedures that disguise relevant
experimental noise.Comment: 4 page
Isohemagglutinins of Graft Origin after ABO-Unmatched Liver Transplantation
THE increasing success of liver transplantation in recent years has provided an experimental model to study and document the hepatic synthesis of many plasma proteins.12345 The normal hepatobiliary tract has not been regarded as a major source of antibody,6,7 aside from the enteric IgA secreted from plasma into the biliary tree.8 Liver transplantation affords the opportunity to study the production of antibody to red cells. Recipient ABO incompatibility to the donor (a mismatched transplant, e.g., a group A liver transplanted into a group B recipient), although not absolutely contraindicated in liver transplantation, is avoided when possible. However, ABO-unmatched transplants (defined. © 1984, Massachusetts Medical Society. All rights reserved
Beating patterns of filaments in viscoelastic fluids
Many swimming microorganisms, such as bacteria and sperm, use flexible
flagella to move through viscoelastic media in their natural environments. In
this paper we address the effects a viscoelastic fluid has on the motion and
beating patterns of elastic filaments. We treat both a passive filament which
is actuated at one end, and an active filament with bending forces arising from
internal motors distributed along its length. We describe how viscoelasticity
modifies the hydrodynamic forces exerted on the filaments, and how these
modified forces affect the beating patterns. We show how high viscosity of
purely viscous or viscoelastic solutions can lead to the experimentally
observed beating patterns of sperm flagella, in which motion is concentrated at
the distal end of the flagella
Clustering in Highest Energy Cosmic Rays: Physics or Statistics?
Directional clustering can be expected in cosmic ray observations due to
purely statistical fluctuations for sources distributed randomly in the sky. We
develop an analytic approach to estimate the probability of random cluster
configurations, and use these results to study the strong potential of the
HiRes, Auger, Telescope Array and EUSO/OWL/AirWatch facilities for deciding
whether any observed clustering is most likely due to non-random sources.Comment: 19 pages, LaTeX, 3 figure
The tau tubulin kinases TTBK1/2 promote accumulation of pathological TDP-43
Pathological aggregates of phosphorylated TDP-43 characterize amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-TDP), two devastating groups of neurodegenerative disease. Kinase hyperactivity may be a consistent feature of ALS and FTLD-TDP, as phosphorylated TDP-43 is not observed in the absence of neurodegeneration. By examining changes in TDP-43 phosphorylation state, we have identified kinases controlling TDP-43 phosphorylation in a C. elegans model of ALS. In this kinome-wide survey, we identified homologs of the tau tubulin kinases 1 and 2 (TTBK1 and TTBK2), which were also identified in a prior screen for kinase modifiers of TDP-43 behavioral phenotypes. Using refined methodology, we demonstrate TTBK1 and TTBK2 directly phosphorylate TDP-43 in vitro and promote TDP-43 phosphorylation in mammalian cultured cells. TTBK1/2 overexpression drives phosphorylation and relocalization of TDP-43 from the nucleus to cytoplasmic inclusions reminiscent of neuropathologic changes in disease states. Furthermore, protein levels of TTBK1 and TTBK2 are increased in frontal cortex of FTLD-TDP patients, and TTBK1 and TTBK2 co-localize with TDP-43 inclusions in ALS spinal cord. These kinases may represent attractive targets for therapeutic intervention for TDP-43 proteinopathies such as ALS and FTLD-TDP
Solitary coherent structures in viscoelastic shear flow: computation and mechanism
Starting from stationary bifurcations in Couette-Dean flow, we compute
nontrivial stationary solutions in inertialess viscoelastic circular Couette
flow. These solutions are strongly localized vortex pairs, exist at arbitrarily
large wavelengths, and show hysteresis in the Weissenberg number, similar to
experimentally observed ``diwhirl'' patterns. Based on the computed velocity
and stress fields, we elucidate a heuristic, fully nonlinear mechanism for
these flows. We propose that these localized, fully nonlinear structures
comprise fundamental building blocks for complex spatiotemporal dynamics in the
flow of elastic liquids.Comment: 5 pages text and 4 figures. Submitted to Physical Review Letter
The potential of trading activity income to fund third sector organisations operating in deprived areas
In the United Kingdom, as in other countries, Third Sector Organisations (TSOs) have been drawn towards income sources associated with trading activities (Teasdale, 2010), but many remain reliant on grant funding to support such activities (Chell, 2007). Using a multivariate analysis approach and data from the National Survey of Charities and Social Enterprises (NSCSE), it is found that trading activities are used relatively commonly in deprived areas. These organisations are also more likely to attempt to access public sector funds. This suggests policy-makers need to consider the impact of funding cuts on TSOs in the most deprived areas as TSOs are unlikely achieve their objectives without continuing support
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