2,068 research outputs found
A grid-based infrastructure for distributed retrieval
In large-scale distributed retrieval, challenges of latency, heterogeneity, and dynamicity emphasise the importance of infrastructural support in reducing the development costs of state-of-the-art solutions. We present a service-based infrastructure for distributed retrieval which blends middleware facilities and a design framework to ‘lift’ the resource sharing approach and the computational services of a European Grid platform into the domain of e-Science applications. In this paper, we give an overview of the DILIGENT Search Framework and illustrate its exploitation in the field of Earth Science
Molecular signatures distinguish human central memory from effector memory CD8 T cell subsets
Abstract
Memory T cells are heterogeneous in terms of their phenotype and functional properties. We investigated the molecular profiles of human CD8 naive central memory (TCM), effector memory (TEM), and effector memory RA (TEMRA) T cells using gene expression microarrays and phospho-protein-specific intracellular flow cytometry. We demonstrate that TCM have a gene expression and cytokine signaling signature that lies between that of naive and TEM or TEMRA cells, whereas TEM and TEMRA are closely related. Our data define the molecular basis for the different functional properties of central and effector memory subsets. We show that TEM and TEMRA cells strongly express genes with known importance in CD8 T cell effector function. In contrast, TCM are characterized by high basal and cytokine-induced STAT5 phosphorylation, reflecting their capacity for self-renewal. Altogether, our results distinguish TCM and TEM/TEMRA at the molecular level and are consistent with the concept that TCM represent memory stem cells.</jats:p
Exact C=1 Boundary Conformal Field Theories
We present a solution of the problem of a free massless scalar field on the
half line interacting through a periodic potential on the boundary. For a
critical value of the period, this system is a conformal field theory with a
non-trivial and explicitly calculable S-matrix for scattering from the
boundary. Unlike all other exactly solvable conformal field theories, it is
non-rational ({\it i.e.} has infinitely many primary fields). It describes the
critical behavior of a number of condensed matter systems, including
dissipative quantum mechanics and of barriers in ``quantum wires''.Comment: harvmac, 10 pages, PUPT-1432/IASSNS-HEP-93/7
Human naive CD8 T cells down-regulate expression of the WNT pathway transcription factors lymphoid enhancer binding factor 1 and transcription factor 7 (T cell factor-1) following antigen encounter in vitro and in vivo
Abstract
The transcription factors lymphoid enhancer binding factor 1 (LEF1) and transcription factor 7 (TCF7) (T cell factor-1 (TCF-1)) are downstream effectors of the WNT signaling pathway, which is a critical regulator of T cell development in the thymus. In this study, we show that LEF1 and TCF7 (TCF-1) are not only expressed in thymocytes, but also in mature T cells. Our data demonstrate that Ag encounter in vivo and engagement of the TCR or IL-15 receptor in vitro leads to the down-regulation of LEF1 and TCF7 (TCF-1) expression in human naive CD8 T cells. We further show that resting T cells preferentially express inhibitory LEF1 and TCF7 (TCF-1) isoforms and that T cell activation changes the isoform balance in favor of stimulatory TCF7 (TCF-1) isoforms. Altogether, our study suggests that proteins involved in the WNT signaling pathway not only regulate T cell development, but also peripheral T cell differentiation.</jats:p
Loop Corrections in the Spectrum of 2D Hawking Radiation
We determine the one-loop and the two-loop back-reaction corrections in the
spectrum of the Hawking radiation for the CGHS model of 2d dilaton gravity by
evaluating the Bogoliubov coefficients for a massless scalar field propagating
on the corresponding backgrounds. Since the back-reaction can induce a small
shift in the position of the classical horizon, we find that a positive shift
leads to a non-Planckian late-time spectrum, while a null or a negative shift
leads to a Planckian late-time spectrum in the leading-order stationary-point
approximation. In the one-loop case there are no corrections to the classical
Hawking temperature, while in the two-loop case the temperature is three times
greater than the classical value. We argue that these results are consistent
with the behaviour of the Hawking flux obtained from the operator quantization
only for the times which are not too late, in accordance with the limits of
validity of the semiclassical approximation.Comment: 20 pages, latex, no figure
Boundary susceptibility in the spin-1/2 chain: Curie like behavior without magnetic impurities
We investigate the low-temperature thermodynamics of the spin-1/2 Heisenberg
chain with open ends. On the basis of boundary conformal field theory arguments
and numerical density matrix renormalization group calculations, it is
established that in the isotropic case the impurity susceptibility exhibits a
Curie-like divergent behavior as the temperature decreases, even in the absence
of magnetic impurities. A similar singular temperature dependence is also found
in the boundary contributions of the specific heat coefficient. In the
anisotropic case, for , these boundary quantities still show
singular temperature dependence obeying a power law with an anomalous
dimension. Experimental consequences will be discussed.Comment: 5 pages, 1 figure, final versio
The Effects of Offering Hay, Pit-Stored Grass Silage or Big-Bale Silage to Pregnant Ewes on Ewe and Lamb Performance
Hay and pit silage have been used extensively for feeding sheep over the winter period, but in recent years, especially on smaller farms, big-bale silage has become increasingly popular. However, there is limited comparative information on the use of big-bale silage for sheep, especially in relation to the effects of chopping and growth stage at harvest. This study compared the performance of ewes offered hay, pit silage, or big-bale grass silage made from either chopped or unchopped grass and cut from the same field at the same time
Refining Fitness Functions for Search-Based Automated Program Repair: A Case Study with ARJA and ARJA-e
Several tools support code templates as a means to specify searches within a program’s source code. Despite their ubiquity, code templates can often prove difficult to specify, and may produce too many or too few match results. In this paper, we present a search-based approach to support developers in specifying templates. This approach uses a suite of mutation operators to recommend changes to a given template, such that it matches with a desired set of code snippets. We evaluate our approach on the problem of inferring a code template that matches all instances of a design pattern, given one instance as a starting template
Theory of nematic and polar active fluid surfaces
We derive a fully covariant theory of the hydrodynamics of nematic and polar active surfaces, subjected to internal and external forces and torques. We study the symmetries of polar and nematic surfaces and find that in addition to five different types of in-plane isotropic surfaces, polar and nematic surfaces can be classified into five polar, two pseudopolar, five nematic and two pseudonematic types of surfaces. We give examples of physical realisations of the different types of surfaces we have identified. We obtain expressions for the equilibrium tensions, moments, and external forces and torques acting on a passive polar or nematic surface. We calculate the entropy production rate using the framework of thermodynamics close to equilibrium and find constitutive equations for polar and nematic active surfaces with different symmetries. We study the instabilities of a confined flat planar-chiral polar active layer and of a confined deformable polar active surface with broken up-down symmetry
Gravitational Radiation from Travelling Waves on D-Strings
Boundary states that preserve supersymmetry are constructed for fractional
D-strings with travelling waves on a
orbifold. The gravitational radiation emitted between two D-strings with
antiparallel travelling waves is calculated.Comment: improvements and correction
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