51,311 research outputs found
Tail Asymptotics of Deflated Risks
Random deflated risk models have been considered in recent literatures. In
this paper, we investigate second-order tail behavior of the deflated risk X=RS
under the assumptions of second-order regular variation on the survival
functions of the risk R and the deflator S. Our findings are applied to
approximation of Value at Risk, estimation of small tail probability under
random deflation and tail asymptotics of aggregated deflated riskComment: 2
Towards Constraining Parity-Violations in Gravity with Satellite Gradiometry
Parity violation in gravity, if existed, could have important implications,
and it is meaningful to search and test the possible observational effects.
Chern-Simons modified gravity serves as a natural model for gravitational
parity-violations. Especially, considering extensions to Einstein-Hilbert
action up to second order curvature terms, it is known that theories of
gravitational parity-violation will reduce to the dynamical Chern-Simons
gravity. In this letter, we outline the theoretical principles of testing the
dynamical Chern-Simons gravity with orbiting gravity gradiometers, which could
be naturally incorporated into future satellite gravity missions. The secular
gravity gradient signals, due to the Mashhoon-Theiss (anomaly) effect, in
dynamical Chern-Simons gravity are worked out, which can improve the constraint
of the corresponding Chern-Simons length scale
obtained from such measurement scheme. For orbiting superconducting
gradiometers or gradiometers with optical readout, a bound
(or even better) could in principle be
obtained, which will be at least 2 orders of magnitude stronger than the
current one based on the observations from the GP-B mission and the LAGEOS I,
II satellites.Comment: 15 pages, 6 figures. arXiv admin note: text overlap with
arXiv:1606.0818
A general comparison theorem for 1-dimensional anticipated BSDEs
Anticipated backward stochastic differential equation (ABSDE) studied the
first time in 2007 is a new type of stochastic differential equations. In this
paper, we establish a general comparison theorem for 1-dimensional ABSDEs with
the generators depending on the anticipated term of .Comment: 8 page
Mesons and Nucleons in Soft-Wall AdS/QCD
We study further the soft-wall AdS/QCD model with a cubic potential for the
bulk scalar. We analyze the spectra of pseudoscalar, scalar, vector and
axial-vector mesons. We also study the spin-1/2 nucleon spectrum and the
pion-nucleon coupling. All of them have a good agreement with the experimental
data.Comment: 17 pages. v2: references added, minor improvement, to appear in PR
Contractor renormalization group theory of the SU() chains and ladders
Contractor renormalization group (CORE) method is applied to the SU()
chain and ladders in this paper. In our designed schemes, we show that these
two classes of systems can return to their original form of Hamiltonian after
CORE transformation. Successive iteration of the transformation leads to a
fixed point so that the ground state energy and the energy gap to the ground
state can be deduced. The result of SU() chain is compared with the one by
Bethe ansatz method. The transformation on spin-1/2 ladders gives a finite gap
in the excited energy spectra to the ground state in an intuitive way. The
application to SU(3) ladders is also discussed.Comment: 4 pages, 4 figures, submitted to Phys. Rev.
ST-Producing E. coli Oppose Carcinogen-Induced Colorectal Tumorigenesis in Mice.
There is a geographic inequality in the incidence of colorectal cancer, lowest in developing countries, and greatest in developed countries. This disparity suggests an environmental contribution to cancer resistance in endemic populations. Enterotoxigenic bacteria associated with diarrheal disease are prevalent in developing countries, including enterotoxigenic E. coli (ETEC) producing heat-stable enterotoxins (STs). STs are peptides that are structurally homologous to paracrine hormones that regulate the intestinal guanylyl cyclase C (GUCY2C) receptor. Beyond secretion, GUCY2C is a tumor suppressor universally silenced by loss of expression of its paracrine hormone during carcinogenesis. Thus, the geographic imbalance in colorectal cancer, in part, may reflect chronic exposure to ST-producing organisms that restore GUCY2C signaling silenced by hormone loss during transformation. Here, mice colonized for 18 weeks with control E. coli or those engineered to secrete ST exhibited normal growth, with comparable weight gain and normal stool water content, without evidence of secretory diarrhea. Enterotoxin-producing, but not control, E. coli, generated ST that activated colonic GUCY2C signaling, cyclic guanosine monophosphate (cGMP) production, and cGMP-dependent protein phosphorylation in colonized mice. Moreover, mice colonized with ST-producing E. coli exhibited a 50% reduction in carcinogen-induced colorectal tumor burden. Thus, chronic colonization with ETEC producing ST could contribute to endemic cancer resistance in developing countries, reinforcing a novel paradigm of colorectal cancer chemoprevention with oral GUCY2C-targeted agents
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