1,549 research outputs found
Anomalous diffusion in polymers: long-time behaviour
We study the Dirichlet boundary value problem for viscoelastic diffusion in
polymers. We show that its weak solutions generate a dissipative semiflow. We
construct the minimal trajectory attractor and the global attractor for this
problem.Comment: 13 page
Structural subnetwork evolution across the life-span: rich-club, feeder, seeder
The impact of developmental and aging processes on brain connectivity and the
connectome has been widely studied. Network theoretical measures and certain
topological principles are computed from the entire brain, however there is a
need to separate and understand the underlying subnetworks which contribute
towards these observed holistic connectomic alterations. One organizational
principle is the rich-club - a core subnetwork of brain regions that are
strongly connected, forming a high-cost, high-capacity backbone that is
critical for effective communication in the network. Investigations primarily
focus on its alterations with disease and age. Here, we present a systematic
analysis of not only the rich-club, but also other subnetworks derived from
this backbone - namely feeder and seeder subnetworks. Our analysis is applied
to structural connectomes in a normal cohort from a large, publicly available
lifespan study. We demonstrate changes in rich-club membership with age
alongside a shift in importance from 'peripheral' seeder to feeder subnetworks.
Our results show a refinement within the rich-club structure (increase in
transitivity and betweenness centrality), as well as increased efficiency in
the feeder subnetwork and decreased measures of network integration and
segregation in the seeder subnetwork. These results demonstrate the different
developmental patterns when analyzing the connectome stratified according to
its rich-club and the potential of utilizing this subnetwork analysis to reveal
the evolution of brain architectural alterations across the life-span
Most vital segment barriers
We study continuous analogues of "vitality" for discrete network flows/paths,
and consider problems related to placing segment barriers that have highest
impact on a flow/path in a polygonal domain. This extends the graph-theoretic
notion of "most vital arcs" for flows/paths to geometric environments. We give
hardness results and efficient algorithms for various versions of the problem,
(almost) completely separating hard and polynomially-solvable cases
Rare B Decays with a HyperCP Particle of Spin One
In light of recent experimental information from the CLEO, BaBar, KTeV, and
Belle collaborations, we investigate some consequences of the possibility that
a light spin-one particle is responsible for the three Sigma^+ -> p mu^+ mu^-
events observed by the HyperCP experiment. In particular, allowing the new
particle to have both vector and axial-vector couplings to ordinary fermions,
we systematically study its contributions to various processes involving
b-flavored mesons, including B-Bbar mixing as well as leptonic, inclusive, and
exclusive B decays. Using the latest experimental data, we extract bounds on
its couplings and subsequently estimate upper limits for the branching ratios
of a number of B decays with the new particle. This can serve to guide
experimental searches for the particle in order to help confirm or refute its
existence.Comment: 17 pages, 3 figures; discussion on spin-0 case modified, few errors
corrected, main conclusions unchange
IJBNPA in 2016: Strategy for advancing the science of behavior change in nutrition and physical activity, and associated editorial priorities
Solution structure of a repeated unit of the ABA-1 nematode polyprotein allergen of ascaris reveals a novel fold and two discrete lipid-binding sites
Parasitic nematode worms cause serious health problems in humans and other animals. They can induce allergic-type immune responses, which can be harmful but may at the same time protect against the infections. Allergens are proteins that trigger allergic reactions and these parasites produce a type that is confined to nematodes, the nematode polyprotein allergens (NPAs). These are synthesized as large precursor proteins comprising repeating units of similar amino acid sequence that are subsequently cleaved into multiple copies of the allergen protein. NPAs bind small lipids such as fatty acids and retinol (Vitamin A) and probably transport these sensitive and insoluble compounds between the tissues of the worms. Nematodes cannot synthesize these lipids, so NPAs may also be crucial for extracting nutrients from their hosts. They may also be involved in altering immune responses by controlling the lipids by which the immune and inflammatory cells communicate. We describe the molecular structure of one unit of an NPA, the well-known ABA-1 allergen of Ascaris and find its structure to be of a type not previously found for lipid-binding proteins, and we describe the unusual sites where lipids bind within this structur
Neural network generated parametrizations of deeply virtual Compton form factors
We have generated a parametrization of the Compton form factor (CFF) H based
on data from deeply virtual Compton scattering (DVCS) using neural networks.
This approach offers an essentially model-independent fitting procedure, which
provides realistic uncertainties. Furthermore, it facilitates propagation of
uncertainties from experimental data to CFFs. We assumed dominance of the CFF H
and used HERMES data on DVCS off unpolarized protons. We predict the beam
charge-spin asymmetry for a proton at the kinematics of the COMPASS II
experiment.Comment: 16 pages, 5 figure
Lewis X antigen mediates adhesion of human breast carcinoma cells to activated endothelium. Possible involvement of the endothelial scavenger receptor C-Type lectin
Lewis x (Lex, CD15), also known as SSEA-1 (stage specific embryonic antigen-1), is a trisaccharide with the structure Galβ(1–4)Fucα(1–3)GlcNAc, which is expressed on glycoconjugates in human polymorphonuclear granulocytes and various tumors such as colon and breast carcinoma. We have investigated the role of Lex in the adhesion of MCF-7 human breast cancer cells and PMN to human umbilical endothelial cells (HUVEC) and the effects of two different anti-Lex mAbs (FC-2.15 and MCS-1) on this adhesion. We also analyzed the cytolysis of Lex+-cells induced by anti-Lex mAbs and complement when cells were adhered to the endothelium, and the effect of these antibodies on HUVEC. The results indicate that MCF-7 cells can bind to HUVEC, and that MCS-1 but not FC-2.15 mAb inhibit this interaction. Both mAbs can efficiently lyse MCF-7 cells bound to HUVEC in the presence of complement without damaging endothelial cells. We also found a Lex-dependent PMN interaction with HUVEC. Although both anti-Lex mAbs lysed PMN in suspension and adhered to HUVEC, PMN aggregation was only induced by mAb FC-2.15. Blotting studies revealed that the endothelial scavenger receptor C-type lectin (SRCL), which binds Lex-trisaccharide, interacts with specific glycoproteins of Mr␣∼␣28 kD and 10 kD from MCF-7 cells. The interaction between Lex+-cancer cells and vascular endothelium is a potential target for cancer treatment.Fil: Elola, Maria Teresa. Fundación Instituto Leloir; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Capurro, Mariana Isabel. University of Toronto; CanadáFil: Barrio, Maria Marcela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Investigación, Docencia y Prevención del Cáncer; ArgentinaFil: Coombs, Peter J.. Imperial College London; Reino UnidoFil: Taylor, Maureen E.. Imperial College London; Reino UnidoFil: Drickamer, Kurt. Imperial College London; Reino UnidoFil: Mordoh, Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Fundación para la Investigación, Docencia y Prevención del Cáncer; Argentin
Modelling avalanches in martensites
Solids subject to continuous changes of temperature or mechanical load often
exhibit discontinuous avalanche-like responses. For instance, avalanche
dynamics have been observed during plastic deformation, fracture, domain
switching in ferroic materials or martensitic transformations. The statistical
analysis of avalanches reveals a very complex scenario with a distinctive lack
of characteristic scales. Much effort has been devoted in the last decades to
understand the origin and ubiquity of scale-free behaviour in solids and many
other systems. This chapter reviews some efforts to understand the
characteristics of avalanches in martensites through mathematical modelling.Comment: Chapter in the book "Avalanches in Functional Materials and
Geophysics", edited by E. K. H. Salje, A. Saxena, and A. Planes. The final
publication is available at Springer via
http://dx.doi.org/10.1007/978-3-319-45612-6_
Autosomal and Z-linked microsatellite markers enhanced for cross-species utility and assessed in a range of birds, including species of conservation concern
Microsatellite markers were designed to be of utility for genotyping multiple species of birds, including those of conservation concern, hence saving resources and enabling species/genome comparisons. We used the proven approach of Dawson et al. (Mol Ecol Resour 10:475–494, 2010) and assessed markers in multiple species, including nine species of conservation interest. We ensured both primer sequences matched multiple species (13 loci) or designed primer sets from expressed sequence tags (2 loci). Eleven primer sets were 100 % identical to the zebra finch (Taeniopygia guttata) and a second passerine species and/or the chicken (Gallus gallus). All 15 loci were polymorphic when assessed in a non-source species (Gouldian finch, Erythrura gouldiae) suggesting utility in multiple species. Four of the five Z-linked loci were assessed in at least nine additional species each (including ratites). All were variable in multiple species, demonstrating cross-species utility and potential for identifying Z chromosome rearrangements
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