16,501 research outputs found
Dual Actions for Born-Infeld and Dp-Brane Theories
Dual actions with respect to U(1) gauge fields for Born-Infeld and -brane
theories are reexamined. Taking into account an additional condition, i.e. a
corollary to the field equation of the auxiliary metric, one obtains an
alternative dual action that does not involve the infinite power series in the
auxiliary metric given by ref. \cite{s14}, but just picks out the first term
from the series formally. New effective interactions of the theories are
revealed. That is, the new dual action gives rise to an effective interaction
in terms of one interaction term rather than infinite terms of different
(higher) orders of interactions physically. However, the price paid for
eliminating the infinite power series is that the new action is not quadratic
but highly nonlinear in the Hodge dual of a -form field strength. This
non-linearity is inevitable to the requirement the two dual actions are
equivalent.Comment: v1: 11 pages, no figures; v2: explanation of effective interactions
added; v3: concision made; v4: minor modification mad
Exploring the Latest Union2 SNIa Dataset by Using Model-Independent Parametrization Methods
We explore the cosmological consequences of the recently released Union2
sample of 557 Type Ia supernovae (SNIa). Combining this latest SNIa dataset
with the Cosmic microwave background (CMB) anisotropy data from the Wilkinson
Microwave Anisotropy Probe 7 year (WMAP7) observations and the baryon acoustic
oscillation (BAO) results from the Sloan Digital Sky Survey (SDSS) Data Release
7 (DR7), we measure the dark energy density function as a free function of redshift. Two
model-independent parametrization methods (the binned parametrization and the
polynomial interpolation parametrization) are used in this paper. By using the
statistic and the Bayesian information criterion, we find that the
current observational data are still too limited to distinguish which
parametrization method is better, and a simple model has advantage in fitting
observational data than a complicated model. Moreover, it is found that all
these parametrizations demonstrate that the Union2 dataset is still consistent
with a cosmological constant at 1 confidence level. Therefore, the
Union2 dataset is different from the Constitution SNIa dataset, which more
favors a dynamical dark energy.Comment: 11 pages, 8 figures, 2 tables, accepted for publication in PR
The transcription factors Egr2 and Egr3 are essential for the control of inflammation and antigen-induced proliferation of B and T cells
This article is available open access under a Creative Commons license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Copyright @ 2012 Elsevier Inc.Lymphocytes provide optimal responses against pathogens with minimal inflammatory pathology. However, the intrinsic mechanisms regulating these responses are unknown. Here, we report that deletion of both transcription factors Egr2 and Egr3 in lymphocytes resulted in a lethal autoimmune syndrome with excessive serum proinflammatory cytokines but also impaired antigen receptor-induced proliferation of B and T cells. Egr2- and Egr3-defective B and T cells had hyperactive signal transducer and activator of transcription-1 (STAT1) and STAT3 while antigen receptor-induced activation of transcription factor AP-1 was severely impaired. We discovered that Egr2 and/or Egr3 directly induced expression of suppressor of cytokine signaling-1 (SOCS1) and SOCS3, inhibitors of STAT1 and STAT3, and also blocked the function of Batf, an AP-1 inhibitor, in B and T cells. Thus, Egr2 and Egr3 regulate B and T cell function in adaptive immune responses and homeostasis by promoting antigen receptor signaling and controlling inflammation.Arthritis Research U
A no-go on strictly stationary spacetimes in four/higher dimensions
We show that strictly stationary spacetimes cannot have non-trivial
configurations of form fields/complex scalar fields and then the spacetime
should be exactly Minkowski or anti-deSitter spacetimes depending on the
presence of negative cosmological constant. That is, self-gravitating complex
scalar fields and form fields cannot exist.Comment: 8 page
Duality Symmetry in Momentum Frame
Siegel's action is generalized to the D=2(p+1) (p even) dimensional
space-time. The investigation of self-duality of chiral p-forms is extended to
the momentum frame, using Siegel's action of chiral bosons in two space-time
dimensions and its generalization in higher dimensions as examples. The whole
procedure of investigation is realized in the momentum space which relates to
the configuration space through the Fourier transformation of fields. These
actions correspond to non-local Lagrangians in the momentum frame. The
self-duality of them with respect to dualization of chiral fields is uncovered.
The relationship between two self-dual tensors in momentum space, whose similar
form appears in configuration space, plays an important role in the
calculation, that is, its application realizes solving algebraically an
integral equation.Comment: 11 pages, no figures, to appear in Phys. Rev.
Thermal Analysis of a New Neutron Shielding Vacuum Multiple Glass
The neutron shielding glass is widely used in nuclear/fusion plants. To improve its temperature resistance and heat insulation, a Gadolinium (Gd)-containing laminate vacuum multiple glass is proposed by using the vacuum insulation method. A 3D finite element model validated by theoretical calculation was developed to analyse the heat transfer path and numerical simulation of the multiple glass was carried out to obtain the temperature distribution and the maximum temperatures of the organic glass in relation to dynamic working temperatures, the sealing agent width, view size, and vacuum thermal conductivity. The results show that the vacuum layer between common glasses can make the work temperature of neutron shielding glass increase. The multiple glass has good heat-shielding performance and it is expected to work in a high-temperature environment. In addition, the vacuum layer between the common glasses and the sealing agent width decay with respect to the view size and vacuum thermal conductivity show an increase in the working temperature of the neutron shielding glass. It was concluded that the order of affecting the temperatures of the organic glass follows the pattern of: view size; vacuum thermal conductivity; sealing agent width
Selective Jamming of LoRaWAN using Commodity Hardware
Long range, low power networks are rapidly gaining acceptance in the Internet
of Things (IoT) due to their ability to economically support long-range sensing
and control applications while providing multi-year battery life. LoRa is a key
example of this new class of network and is being deployed at large scale in
several countries worldwide. As these networks move out of the lab and into the
real world, they expose a large cyber-physical attack surface. Securing these
networks is therefore both critical and urgent. This paper highlights security
issues in LoRa and LoRaWAN that arise due to the choice of a robust but slow
modulation type in the protocol. We exploit these issues to develop a suite of
practical attacks based around selective jamming. These attacks are conducted
and evaluated using commodity hardware. The paper concludes by suggesting a
range of countermeasures that can be used to mitigate the attacks.Comment: Mobiquitous 2017, November 7-10, 2017, Melbourne, VIC, Australi
Massive charged particle's tunneling from spherical charged black hole
We generalize the Parikh-Wilczek scheme to the tunneling of a massive charged
particle from a general spherical charged black hole. We obtain that the
tunneling probability depends on the energy, the mass and the charge of the
particle. In particular, the modified Hawking temperature is related to the
charge. Only at the leading order approximation can the standard Hawking
temperature be reproduced. We take the Reissner-Nordstr\"{o}m black hole as an
example to clarify our points of view, and find that the accumulation of
Hawking radiation makes it approach an extreme black hole.Comment: 10 pages, no figures; v2: a minor typo corrected; v3: 11 pages,
clarification and reference added, final version to be published in EPL; v4:
minor modifications to match the published versio
- …