241 research outputs found
A Modular Toolkit for Distributed Interactions
We discuss the design, architecture, and implementation of a toolkit which
supports some theories for distributed interactions. The main design principles
of our architecture are flexibility and modularity. Our main goal is to provide
an easily extensible workbench to encompass current algorithms and incorporate
future developments of the theories. With the help of some examples, we
illustrate the main features of our toolkit.Comment: In Proceedings PLACES 2010, arXiv:1110.385
Uniqueness Typing for Resource Management in Message-Passing Concurrency
We view channels as the main form of resources in a message-passing
programming paradigm. These channels need to be carefully managed in settings
where resources are scarce. To study this problem, we extend the pi-calculus
with primitives for channel allocation and deallocation and allow channels to
be reused to communicate values of different types. Inevitably, the added
expressiveness increases the possibilities for runtime errors. We define a
substructural type system which combines uniqueness typing and affine typing to
reject these ill-behaved programs
Two--magnon scattering and the spin--phonon interaction beyond the adiabatic approximation
We consider a model of Raman scattering for a two--dimensional
Heisenberg Anti-Ferromagnet which includes a {\it dynamical} spin--phonon
interaction. We observe a broadening of the line shape due to increased
coupling with excited high--energy spin states. Our results are close to a
model of random static exchange interactions, first introduced in this context
by Haas {\it et al.} [J. Appl. Phys. {\bf 75}, 6340, (1994)], which, when
extended to large numbers of spins, explains experiments in the parent
insulating compounds of high- superconductors.Comment: 14 pages (revtex format), 8 postscript figure
Vascular responses of the extremities to transdermal application of vasoactive agents in Caucasian and African descent individuals
This is an accepted manuscript of an article published by Springer in European Journal of Applied Physiology on 04/04/2015, available online: https://doi.org/10.1007/s00421-015-3164-2
The accepted version of the publication may differ from the final published version.© 2015, Springer-Verlag Berlin Heidelberg. Purpose: Individuals of African descent (AFD) are more susceptible to non-freezing cold injury than Caucasians (CAU) which may be due, in part, to differences in the control of skin blood flow. We investigated the skin blood flow responses to transdermal application of vasoactive agents. Methods: Twenty-four young males (12 CAU and 12 AFD) undertook three tests in which iontophoresis was used to apply acetylcholine (ACh 1 w/v %), sodium nitroprusside (SNP 0.01 w/v %) and noradrenaline (NA 0.5 mM) to the skin. The skin sites tested were: volar forearm, non-glabrous finger and toe, and glabrous finger (pad) and toe (pad). Results: In response to SNP on the forearm, AFD had less vasodilatation for a given current application than CAU (P = 0.027–0.004). ACh evoked less vasodilatation in AFD for a given application current in the non-glabrous finger and toe compared with CAU (P = 0.043–0.014) with a lower maximum vasodilatation in the non-glabrous finger (median [interquartile], AFD n = 11, 41[234] %, CAU n = 12, 351[451] %, P = 0.011) and non-glabrous toe (median [interquartile], AFD n = 9, 116[318] %, CAU n = 12, 484[720] %, P = 0.018). ACh and SNP did not elicit vasodilatation in the glabrous skin sites of either group. There were no ethnic differences in response to NA. Conclusion: AFD have an attenuated endothelium-dependent vasodilatation in non-glabrous sites of the fingers and toes compared with CAU. This may contribute to lower skin temperature following cold exposure and the increased risk of cold injuries experienced by AFD.Published versio
Nucleic acid recognition by Toll-like receptors is coupled to stepwise processing by cathepsins and asparagine endopeptidase
TLR3, TLR7, and TLR9 are cleaved in the same step-wise manner in all immune cell types examined
Lorentz and CPT Violation in Neutrinos
A general formalism is presented for violations of Lorentz and CPT symmetry
in the neutrino sector. The effective hamiltonian for neutrino propagation in
the presence of Lorentz and CPT violation is derived, and its properties are
studied. Possible definitive signals in existing and future
neutrino-oscillation experiments are discussed. Among the predictions are
direction-dependent effects, including neutrino-antineutrino mixing, sidereal
and annual variations, and compass asymmetries. Other consequences of Lorentz
and CPT violation involve unconventional energy dependences in oscillation
lengths and mixing angles. A variety of simple models both with and without
neutrino masses are developed to illustrate key physical effects. The
attainable sensitivities to coefficients for Lorentz violation in the
Standard-Model Extension are estimated for various types of experiments. Many
experiments have potential sensitivity to Planck-suppressed effects, comparable
to the best tests in other sectors. The lack of existing experimental
constraints, the wide range of available coefficient space, and the variety of
novel effects imply that some or perhaps even all of the existing data on
neutrino oscillations might be due to Lorentz and CPT violation.Comment: 25 pages REVTe
Renormalization Theory of Stochastic Growth
An analytical renormalization group treatment is presented of a model which,
for one value of parameters, is equivalent to diffusion limited aggregation.
The fractal dimension of DLA is computed to be 2-1/2+1/5=1.7. Higher
multifractal exponents are also calculated and found in agreement with
numerical results. It may be possible to use this technique to describe the
dielectric breakdown model as well, which is given by different parameter
values.Comment: 39 pages, LaTeX, 11 figure
IRF4 transcription factor-dependent CD11b+ dendritic cells in human and mouse control mucosal IL-17 cytokine responses.
Mouse and human dendritic cells (DCs) are composed of functionally specialized subsets, but precise interspecies correlation is currently incomplete. Here, we showed that murine lung and gut lamina propria CD11b+ DC populations were comprised of two subsets: FLT3- and IRF4-dependent CD24(+)CD64(-) DCs and contaminating CSF-1R-dependent CD24(-)CD64(+) macrophages. Functionally, loss of CD24(+)CD11b(+) DCs abrogated CD4+ T cell-mediated interleukin-17 (IL-17) production in steady state and after Aspergillus fumigatus challenge. Human CD1c+ DCs, the equivalent of murine CD24(+)CD11b(+) DCs, also expressed IRF4, secreted IL-23, and promoted T helper 17 cell responses. Our data revealed heterogeneity in the mouse CD11b+ DC compartment and identifed mucosal tissues IRF4-expressing DCs specialized in instructing IL-17 responses in both mouse and human. The demonstration of mouse and human DC subsets specialized in driving IL-17 responses highlights the conservation of key immune functions across species and will facilitate the translation of mouse in vivo findings to advance DC-based clinical therapies
An extended set of PRDM1/BLIMP1 target genes links binding motif type to dynamic repression
The transcriptional repressor B lymphocyte-induced maturation protein-1 (BLIMP1) regulates gene expression and cell fate. The DNA motif bound by BLIMP1 in vitro overlaps with that of interferon regulatory factors (IRFs), which respond to inflammatory/immune signals. At such sites, BLIMP1 and IRFs can antagonistically regulate promoter activity. In vitro motif selection predicts that only a subset of BLIMP1 or IRF sites is subject to antagonistic regulation, but the extent to which antagonism occurs is unknown, since an unbiased assessment of BLIMP1 occupancy in vivo is lacking. To address this, we identified an extended set of promoters occupied by BLIMP1. Motif discovery and enrichment analysis demonstrate that multiple motif variants are required to capture BLIMP1 binding specificity. These are differentially associated with CpG content, leading to the observation that BLIMP1 DNA-binding is methylation sensitive. In occupied promoters, only a subset of BLIMP1 motifs overlap with IRF motifs. Conversely, a distinct subset of IRF motifs is not enriched amongst occupied promoters. Genes linked to occupied promoters containing overlapping BLIMP1/IRF motifs (e.g. AIM2, SP110, BTN3A3) are shown to constitute a dynamic target set which is preferentially activated by BLIMP1 knock-down. These data confirm and extend the competitive model of BLIMP1 and IRF interaction
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