4,337 research outputs found
The use of computer-generated color graphic images for transient thermal analysis
Color computer graphics techniques were investigated as a means of rapidly scanning and interpreting large sets of transient heating data. The data presented were generated to support the conceptual design of a heat-sink thermal protection system (TPS) for a hypersonic research airplane. Color-coded vector and raster displays of the numerical geometry used in the heating calculations were employed to analyze skin thicknesses and surface temperatures of the heat-sink TPS under a variety of trajectory flight profiles. Both vector and raster displays proved to be effective means for rapidly identifying heat-sink mass concentrations, regions of high heating, and potentially adverse thermal gradients. The color-coded (raster) surface displays are a very efficient means for displaying surface-temperature and heating histories, and thereby the more stringent design requirements can quickly be identified. The related hardware and software developments required to implement both the vector and the raster displays for this application are also discussed
Quark mass dependence of the pion vector form factor
We examine the quark mass dependence of the pion vector form factor, particularly the curvature (mean quartic radius). We focus our study on the consequences of assuming that the coupling constant of the rho to pions, g(rho pi pi), is largely independent of the quark mass while the quark mass dependence of the rho mass is given by recent lattice data. By employing the Omnes representation we can provide a very clean estimate for a certain combination of the curvature and the square radius, whose quark mass dependence could be determined from lattice computations. This study provides an independent access to the quark mass dependence of the rho pi pi coupling and in this way a non-trivial check of the systematics of chiral extrapolations. We also provide an improved value for the curvature for physical values for the quark masses. namely (r(4)) = 0.73 +/- 0.09 fm(4) or equivalently c(v) = 4.00 +/- 0.50 GeV-4. (C) 2009 Elsevier B.V. All rights reserved
Crystallographic disorder and electron scattering on structural two-level systems in ZrAs1.4Se0.5
Single crystals of ZrAs1.4Se0.5 (PbFCl type structure) were grown by chemical
vapour transport. While their thermodynamic and transport properties are
typical for ordinary metals, the electrical resistivity exhibits a shallow
minimum at low temperatures. Application of strong magnetic fields does not
influence this anomaly. The minimum of the resistivity in ZrAs1.4Se0.5
apparently originates from interaction between the conduction electrons and
structural two-level systems. Significant disorder in the As-Se substructure is
inferred from X-ray diffraction and electron microprobe studies
Higher excitations of and in dilepton spectra
We consider lepton pair production via two-hadron annihilation through
various isoscalar vector mesons within hot, baryon-free matter. This is
tantamount to constructing effective form factors which we model using a
vector-meson-dominance approach and compare with experiment. In particular, we
consider the reactions and + c.c. . We find that and are visible in the mass
spectrum for the thermal production rate above the
tail and even above the results---both of which were
considered important in their respective mass regions.Comment: RevTeX, 9 pages, 6 (uuencoded) figures; to appear in Phys. Rev
Quantitative and Dynamic Catalogs of Proteins Released during Apoptotic and Necroptotic Cell Death
The inflammatory functions of the cytokine tumor necrosis factor (TNF) rely on its ability to induce cytokine production and to induce cell death. Caspase-dependent and caspase-independent pathways-apoptosis and necroptosis, respectively-regulate immunogenicity by the release of distinct sets of cellular proteins. To obtain an unbiased, systems-level understanding of this important process, we here applied mass spectrometry-based proteomics to dissect protein release during apoptosis and necroptosis. We report hundreds of proteins released from human myeloid cells in time course experiments. Both cell death types induce receptor shedding, but only apoptotic cells released nucleosome components. Conversely, necroptotic cells release lysosomal components by activating lysosomal exocytosis at early stages of necroptosis-induced membrane permeabilization and show reduced release of conventionally secreted cytokines
Desenvolvimento de linhagens de mamoeiro geneticamente modificadas para resistência a vírus.
O mamoeiro (Carica papaya L.) é umas das fruteiras mais comuns nos países da América Tropical, além de ser cultivado amplamente por vários países do mundo como Sri-Lanka, Malásia, Havaí, Austrália, Ásia e África do Sul. O mamoeiro tem grande importância na alimentação humana, bem como em usos medicinal, indústria têxtil e cosmético. O ataque de viroses ao mamoeiro tem papel fundamental na diminuição da produtividade e, consequentemente, dos lucros gerados pela cultura
Computing Black Hole entropy in Loop Quantum Gravity from a Conformal Field Theory perspective
Motivated by the analogy proposed by Witten between Chern-Simons and
Conformal Field Theories, we explore an alternative way of computing the
entropy of a black hole starting from the isolated horizon framework in Loop
Quantum Gravity. The consistency of the result opens a window for the interplay
between Conformal Field Theory and the description of black holes in Loop
Quantum Gravity.Comment: 9 page
Cell Death Dis.
The Gram-negative bacterium Shigella flexneri invades the colonic epithelium and causes bacillary dysentery. S. flexneri requires the virulence factor invasion plasmid antigen B (IpaB) to invade host cells, escape from the phagosome and induce macrophage cell death. The mechanism by which IpaB functions remains unclear. Here, we show that purified IpaB spontaneously oligomerizes and inserts into the plasma membrane of target cells forming cation selective ion channels. After internalization, IpaB channels permit potassium influx within endolysosomal compartments inducing vacuolar destabilization. Endolysosomal leakage is followed by an ICE protease-activating factor-dependent activation of Caspase-1 in macrophages and cell death. Our results provide a mechanism for how the effector protein IpaB with its ion channel activity causes phagosomal destabilization and induces macrophage death. These data may explain how S. flexneri uses secreted IpaB to escape phagosome and kill the host cells during infection and, may be extended to homologs from other medically important enteropathogenic bacteria
One-loop effects of extra dimensions on the WW\gamma and WWZ vertices
The one-loop contribution of the excited Kaluza-Klein (KK) modes of the
gauge group on the off-shell and vertices is
calculated in the context of a pure Yang-Mills theory in five dimensions and
its phenomenological implications discussed. The use of a gauge-fixing
procedure for the excited KK modes that is covariant under the standard gauge
transformations of the group is stressed. A gauge-fixing term and the
Faddeev-Popov ghost sector for the KK gauge modes that are separately invariant
under the standard gauge transformations of are presented. It is
shown that the one-loop contributions of the KK modes to the off-shell
and vertices are free of ultraviolet divergences and
well-behaved at high energies. It is found that for a size of the fifth
dimension of , the one-loop contribution of the KK modes to
these vertices is about one order of magnitude lower than the corresponding
standard model radiative correction. This contribution is similar to the one
estimated for new gauge bosons contributions in other contexts. Tree-level
effects on these vertices induced by operators of higher canonical dimension
are also investigated. It is found that these effects are lower than those
generated at the one-loop order by the KK gauge modes.Comment: 19 pages, 9 figures. Some typos were correcte
Incidência de couro de sapo em mandioca (Manihot esculenta Crantz) no Estado do Pará.
Resumo 622
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