20,888 research outputs found
Modeling of Euclidean braided fiber architectures to optimize composite properties
Three-dimensional braided fiber reinforcements are a very effective toughening mechanism for composite materials. The integral yarn path inherent to this fiber architecture allows for effective multidirectional dispersion of strain energy and negates delamination problems. In this paper a geometric model of Euclidean braid fiber architectures is presented. This information is used to determine the degree of geometric isotropy in the braids. This information, when combined with candidate material properties, can be used to quickly generate an estimate of the available load-carrying capacity of Euclidean braids at any arbitrary angle
Avalanche-Induced Current Enhancement in Semiconducting Carbon Nanotubes
Semiconducting carbon nanotubes under high electric field stress (~10 V/um)
display a striking, exponential current increase due to avalanche generation of
free electrons and holes. Unlike in other materials, the avalanche process in
such 1D quantum wires involves access to the third sub-band, is insensitive to
temperature, but strongly dependent on diameter ~exp(-1/d^2). Comparison with a
theoretical model yields a novel approach to obtain the inelastic optical
phonon emission length, L_OP,ems ~ 15d nm. The combined results underscore the
importance of multi-band transport in 1D molecular wires
Spontaneous Ratchet Effect in a Granular Gas
The spontaneous clustering of a vibrofluidized granular gas is employed to
generate directed transport in two different compartmentalized systems: a
"granular fountain" in which the transport takes the form of convection rolls,
and a "granular ratchet" with a spontaneous particle current perpendicular to
the direction of energy input. In both instances, transport is not due to any
system-intrinsic anisotropy, but arises as a spontaneous collective symmetry
breaking effect of many interacting granular particles. The experimental and
numerical results are quantitatively accounted for within a flux model.Comment: 4 pages, 5 figures; Fig. 4 has been reduced in size and qualit
The Construction of a Partially Regular Solution to the Landau-Lifshitz-Gilbert Equation in
We establish a framework to construct a global solution in the space of
finite energy to a general form of the Landau-Lifshitz-Gilbert equation in
. Our characterization yields a partially regular solution,
smooth away from a 2-dimensional locally finite Hausdorff measure set. This
construction relies on approximation by discretization, using the special
geometry to express an equivalent system whose highest order terms are linear
and the translation of the machinery of linear estimates on the fundamental
solution from the continuous setting into the discrete setting. This method is
quite general and accommodates more general geometries involving targets that
are compact smooth hypersurfaces.Comment: 43 pages, 2 figure
Lymphotoxins and cytomegalovirus cooperatively induce interferon-beta, establishing host-virus détente
Tumor necrosis factor (TNF)-related cytokines regulate cell death and survival and provide strong selective pressures for viruses, such as cytomegalovirus (CMV), to evolve counterstrategies in order to persist in immune-competent hosts. Signaling by the lymphotoxin (LT)-β receptor or TNF receptor-1, but not Fas or TRAIL receptors, inhibits the cytopathicity and replication of human CMV by a nonapoptotic, reversible process that requires nuclear factor κB (NF-κB)-dependent induction of interferon-β (IFN-β). Efficient induction of IFN-β requires virus infection and LT signaling, demonstrating the need for both host and viral factors in the curtailment of viral replication without cellular elimination. LTα-deficient mice and LTβR-Fc transgenic mice were profoundly susceptible to murine CMV infection. Together, these results reveal an essential and conserved role for LTs in establishing host defense to CMV
Far Ultraviolet Observations of the Dwarf Nova VW Hyi in Quiescence
We present a 904-1183 A spectrum of the dwarf nova VW Hydri taken with the
Far Ultraviolet Spectroscopic Explorer during quiescence, eleven days after a
normal outburst, when the underlying white dwarf accreter is clearly exposed in
the far ultraviolet. However, model fitting show that a uniform temperature
white dwarf does not reproduce the overall spectrum, especially at the shortest
wavelengths. A better approximation to the spectrum is obtained with a model
consisting of a white dwarf and a rapidly rotating ``accretion belt''. The
white dwarf component accounts for 83% of the total flux, has a temperature of
23,000K, a v sin i = 400 km/s, and a low carbon abundance. The best-fit
accretion belt component accounts for 17% of the total flux, has a temperature
of about 48,000-50,000K, and a rotation rate Vrot sin i around 3,000-4,000
km/s. The requirement of two components in the modeling of the spectrum of VW
Hyi in quiescence helps to resolve some of the differences in interpretation of
ultraviolet spectra of VW Hyi in quiescence. However, the physical existence of
a second component (and its exact nature) in VW Hyi itself is still relatively
uncertain, given the lack of better models for spectra of the inner disk in a
quiescent dwarf nova.Comment: 6 figures, 10 printed page in the journal, to appear in APJ, 1 Sept.
2004 issue, vol. 61
Hadron widths in mixed-phase matter
We derive classically an expression for a hadron width in a two-phase region
of hadron gas and quark-gluon plasma (QGP). The presence of QGP gives hadrons
larger widths than they would have in a pure hadron gas. We find that the
width observed in a central Au+Au collision at
GeV/nucleon is a few MeV greater than the width in a pure hadron gas. The part
of observed hadron widths due to QGP is approximately proportional to
.Comment: 8 pages, latex, no figures, KSUCNR-002-9
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Antrodia cinnamomea reduces obesity and modulates the gut microbiota in high-fat diet-fed mice.
BackgroundObesity is associated with gut microbiota dysbiosis, disrupted intestinal barrier and chronic inflammation. Given the high and increasing prevalence of obesity worldwide, anti-obesity treatments that are safe, effective and widely available would be beneficial. We examined whether the medicinal mushroom Antrodia cinnamomea may reduce obesity in mice fed with a high-fat diet (HFD).MethodsMale C57BL/6J mice were fed a HFD for 8 weeks to induce obesity and chronic inflammation. The mice were treated with a water extract of A. cinnamomea (WEAC), and body weight, fat accumulation, inflammation markers, insulin sensitivity and the gut microbiota were monitored.ResultsAfter 8 weeks, the mean body weight of HFD-fed mice was 39.8±1.2 g compared with 35.8±1.3 g for the HFD+1% WEAC group, corresponding to a reduction of 4 g or 10% of body weight (P<0.0001). WEAC supplementation reduced fat accumulation and serum triglycerides in a statistically significant manner in HFD-fed mice. WEAC also reversed the effects of HFD on inflammation markers (interleukin-1β, interleukin-6, tumor necrosis factor-α), insulin resistance and adipokine production (leptin and adiponectin). Notably, WEAC increased the expression of intestinal tight junctions (zonula occludens-1 and occludin) and antimicrobial proteins (Reg3g and lysozyme C) in the small intestine, leading to reduced blood endotoxemia. Finally, WEAC modulated the composition of the gut microbiota, reducing the Firmicutes/Bacteroidetes ratio and increasing the level of Akkermansia muciniphila and other bacterial species associated with anti-inflammatory properties.ConclusionsSupplementation with A. cinnamomea produces anti-obesogenic, anti-inflammatory and antidiabetic effects in HFD-fed mice by maintaining intestinal integrity and modulating the gut microbiota
Flavor ordering of elliptic flows at high transverse momentum
Based on the quark coalescence model for the parton-to-hadron phase
transition in ultra-relativistic heavy ion collisions, we relate the elliptic
flow () of high \pt hadrons to that of high \pt quarks. For high \pt
hadrons produced from an isospin symmetric and quark-antiquark symmetric
partonic matter, magnitudes of their elliptic flows follow a flavor ordering as
if strange quarks have a
smaller elliptic flow than light quarks. The elliptic flows of high \pt
hadrons further follow a simple quark counting rule if strange quarks and light
quarks have same high \pt spectrum and coalescence probability.Comment: 4 pages, 1 figure, revte
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