962 research outputs found
Cosmic positron and antiproton constraints on the gauge-Higgs Dark Matter
We calculate the cosmic ray positron and antiproton spectra of a gauge-Higgs
dark matter candidate in a warped five-dimensional
gauge-Higgs unification model. The stability of the gauge-Higgs boson is
guaranteed by the H parity under which only the Higgs boson is odd at low
energy. The 4-point vertices of HHW^+W^- and HHZZ, allowed by H parity
conservation, have the same magnitude as in the standard model, which yields
efficient annihilation rate for . The most dominant annihilation
channel is followed by the subsequent decays of the
bosons into positrons or quarks, which undergo fragmentation into antiproton.
Comparing with the observed positron and antiproton spectra with the PAMALA and
Fermi/LAT, we found that the Higgs boson mass cannot be larger than 90 GeV, in
order not to overrun the observations. Together with the constraint on not
overclosing the Universe, the valid range of the dark matter mass is restricted
to 70-90 GeV.Comment: 13 pages, 3 figure
Relationship between Obesity-related Hormone Peptides and Quality of Life in Obese Women among Different Traditional Chinese Medicine Syndrome Groups
AbstractThe aim of this study was to explore the relationship between obesity-related hormone peptides and quality of life in obese women among different traditional Chinese medicine (TCM) syndrome groups (證型 zhèng xíng). 260 obese women met with age between 20 and 65years old and body mass index (BMI) ≧ 27kg/m2, were recruited. The participants filled out a questionnaire on obese TCM syndrome groups, which was designed by professional TCM doctors, and two questionnaires on quality of life (QOL), WHOQOL-BREF Taiwan version and MOS Short Form-12 (SF-12). Data of biochemical characteristics and obesity-related hormone peptides were collected at the same time. According to the responses provided, the obese subjects were classified into spleen deficiency with dampness encumbrance syndrome (脾虛濕阻證 pí xū shī zǔ zhèng; SDD), stomach heat with dampness encumbrance syndrome (胃熱濕阻證 wèi rè shī zǔ zhèng; SHD), liver depression and qi stagnation syndrome (肝鬱氣滯證 gān yù qì zhì zhèng; LDQ), dual spleen-kidney deficiency syndrome (脾腎兩虛證 pí shèn liǎng xū zhèng; SKD), yin deficiency with internal heat syndrome (陰虛內熱證 yīn xū nèi rè zhèng; YDI) and a control group. For physical conditions, SDD group had significantly higher means in weight and BMI compared with the control group. The insulin and leptin levels in SHD group were significantly higher than those in the control group. The LDQ group showed marked decrease in mental condition scores compared with the control group. This study found that obese women in the SDD group were fatter than those in the control group. SHD group might have greater influence on the regulation of obesity-related hormone peptides. The LDQ group had poor QOL than the control group. Analysis of TCM syndrome groups among obese women merits further investigation
Four-quark Operators Relevant to B Meson Lifetimes from QCD Sum Rules
At the order of 1/m_b^3, the B meson lifetimes are controlled by the hadronic
matrix elements of some four-quark operators. The nonfactorizable magnitudes of
these four-quark operator matrix elements are analyzed by QCD sum rules in the
framework of heavy quark effective theory. The vacuum saturation for
color-singlet four-quark operators is justified at hadronic scale, and the
nonfactorizable effect is at a few percent level. However for color-octet
four-quark operators, the vacuum saturation is violated sizably that the
nonfactorizable effect cannot be neglected for the B meson lifetimes. The
implication to the extraction of some of the parameters from B decays is
discussed. The B meson lifetime ratio is predicted as
\tau(B^-)/\tau(B^0)=1.09\pm 0.02. However, the experimental result of the
lifetime ratio \tau(\Lambda_b)/\tau(B^0) still cannot be explained.Comment: 20 pages, latex, 6 figures, discussion on non-factorizable effect of
the four-quark condensate added, to appear in Phys. Rev. D57 (1998
Greenhouse gas emissions in a subtropical jasmine plantation managed with straw combined with industrial and agricultural wastes
The effects of straw alone or combined with industrial and agricultural wastes as fertilizers on greenhouse gas (GHG) emissions are still poorly known in cropland areas. Here, we studied the effects of 3.5 Mg ha−1 straw and 3.5 Mg ha−1 straw combined with 8 Mg ha−1 of diverse wastes on GHG emission in a subtropical Jasminum sambac plantation in southeastern China. There were five treatments in a completely randomized block design: control, straw only, straw + biochar, straw + steel slag, and straw + gypsum slag. Emissions of carbon dioxide were generally higher in the treatments with waste than in the control or straw-only treatments, whereas the contrary pattern was observed in CH4 and N2O emission rates. Moreover, the total global warming potentials (GWPs) were no significantly higher in most of the amended treatments as compared to the control and straw-only treatments. In relation to the treatment with only straw, GWPs were 9.4% lower when steel slag was used. This finding could be a consequence of Fe amount added by steel slag, which would limit and inhibit the emissions of GHGs and their transport from soil to atmosphere. Our results showed that the application of slags did not increase the emission of GHGs and that the combination of straw with steel slag or biochar could be more effective than straw alone for controlling GHGs emission and improve soil C and nutrient provision
Nonlinear and nonreciprocal transport effects in untwinned thin films of ferromagnetic Weyl metal SrRuO
The identification of distinct charge transport features, deriving from
nontrivial bulk band and surface states, has been a challenging subject in the
field of topological systems. In topological Dirac and Weyl semimetals,
nontrivial conical bands with Fermi-arc surfaces states give rise to negative
longitudinal magnetoresistance due to chiral anomaly effect and unusual
thickness dependent quantum oscillation from Weyl-orbit effect, which were
demonstrated recently in experiments. In this work, we report the experimental
observations of large nonlinear and nonreciprocal transport effects for both
longitudinal and transverse channels in an untwinned Weyl metal of SrRuO
thin film grown on a SrTiO substrate. From rigorous measurements with
bias current applied along various directions with respect to the crystalline
principal axes, the magnitude of nonlinear Hall signals from the transverse
channel exhibits a simple sin dependent at low temperatures, where
is the angle between bias current direction and orthorhombic
[001], reaching a maximum when current is along orthorhombic
[1-10]. On the contrary, the magnitude of nonlinear and nonreciprocal
signals in the longitudinal channel attains a maximum for bias current along
[001], and it vanishes for bias current along [1-10]. The
observed -dependent nonlinear and nonreciprocal signals in longitudinal
and transverse channels reveal a magnetic Weyl phase with an effective Berry
curvature dipole along [1-10] from surface states, accompanied by 1D
chiral edge modes along [001].Comment: 24 pages, 6 figure
Tuning ultrafast electron thermalization pathways in a van der Waals heterostructure
Ultrafast electron thermalization - the process leading to Auger
recombination, carrier multiplication via impact ionization and hot carrier
luminescence - occurs when optically excited electrons in a material undergo
rapid electron-electron scattering to redistribute excess energy and reach
electronic thermal equilibrium. Due to extremely short time and length scales,
the measurement and manipulation of electron thermalization in nanoscale
devices remains challenging even with the most advanced ultrafast laser
techniques. Here, we overcome this challenge by leveraging the atomic thinness
of two-dimensional van der Waals (vdW) materials in order to introduce a highly
tunable electron transfer pathway that directly competes with electron
thermalization. We realize this scheme in a graphene-boron nitride-graphene
(G-BN-G) vdW heterostructure, through which optically excited carriers are
transported from one graphene layer to the other. By applying an interlayer
bias voltage or varying the excitation photon energy, interlayer carrier
transport can be controlled to occur faster or slower than the intralayer
scattering events, thus effectively tuning the electron thermalization pathways
in graphene. Our findings, which demonstrate a novel means to probe and
directly modulate electron energy transport in nanoscale materials, represent
an important step toward designing and implementing novel optoelectronic and
energy-harvesting devices with tailored microscopic properties.Comment: Accepted to Nature Physic
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Pyk2 activates the NLRP3 inflammasome by directly phosphorylating ASC and contributes to inflammasome-dependent peritonitis
The inflammasome adaptor protein, ASC, contributes to both innate immune responses and inflammatory diseases via self-oligomerization, which leads to the activation of the protease, caspase-1. Here, we report that the cytosolic tyrosine kinases, FAK and Pyk2, are differentially involved in NLRP3 and AIM2 inflammasome activation. The inhibition of FAK and Pyk2 with RNA interference or chemical inhibitors dramatically abolished ASC oligomerization, caspase-1 activation, and IL-1β secretion in response to NLRP3 or AIM2 stimulation. Pyk2 is phosphorylated by the kinase Syk and relocalizes to the ASC specks upon NLRP3 inflammasome activation. Pyk2, but not FAK, could directly phosphorylate ASC at Tyr146, and only the phosphorylated ASC could participate in speck formation and trigger IL-1β secretion. Moreover, the clinical-trial-tested Pyk2/FAK dual inhibitor PF-562271 reduced monosodium urate-mediated peritonitis, a disease model used for studying the consequences of NLRP3 activation. Our results suggest that although Pyk2 and FAK are involved in inflammasome activation, only Pyk2 directly phosphorylates ASC and brings ASC into an oligomerization-competent state by allowing Tyr146 phosphorylation to participate ASC speck formation and subsequent NLRP3 inflammation
Controlling crystallization and its absence: Proteins, colloids and patchy models
The ability to control the crystallization behaviour (including its absence)
of particles, be they biomolecules such as globular proteins, inorganic
colloids, nanoparticles, or metal atoms in an alloy, is of both fundamental and
technological importance. Much can be learnt from the exquisite control that
biological systems exert over the behaviour of proteins, where protein
crystallization and aggregation are generally suppressed, but where in
particular instances complex crystalline assemblies can be formed that have a
functional purpose. We also explore the insights that can be obtained from
computational modelling, focussing on the subtle interplay between the
interparticle interactions, the preferred local order and the resulting
crystallization kinetics. In particular, we highlight the role played by
``frustration'', where there is an incompatibility between the preferred local
order and the global crystalline order, using examples from atomic glass
formers and model anisotropic particles.Comment: 11 pages, 7 figure
New Family of Robust 2D Topological Insulators in van der Waals Heterostructures
We predict a new family of robust two-dimensional (2D) topological insulators
in van der Waals heterostructures comprising graphene and chalcogenides BiTeX
(X=Cl, Br and I). The layered structures of both constituent materials produce
a naturally smooth interface that is conducive to proximity induced new
topological states. First principles calculations reveal intrinsic
topologically nontrivial bulk energy gaps as large as 70-80 meV, which can be
further enhanced up to 120 meV by compression. The strong spin-orbit coupling
in BiTeX has a significant influence on the graphene Dirac states, resulting in
the topologically nontrivial band structure, which is confirmed by calculated
nontrivial Z2 index and an explicit demonstration of metallic edge states. Such
heterostructures offer an unique Dirac transport system that combines the 2D
Dirac states from graphene and 1D Dirac edge states from the topological
insulator, and it offers new ideas for innovative device designs
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