5,804 research outputs found
Corotational Damping of Diskoseismic C-modes in Black Hole Accretion Discs
Diskoseismic c-modes in accretion discs have been invoked to explain
low-frequency variabilities observed in black-hole X-ray binaries. These modes
are trapped in the inner-most region of the disc and have frequencies much
lower than the rotation frequency at the disc inner radius. We show that
because the trapped waves can tunnel through the evanescent barrier to the
corotational wave zone, the c-modes are damped due to wave absorption at the
corotation resonance. We calculate the corotational damping rates of various
c-modes using the WKB approximation. The damping rate varies widely depending
on the mode frequency, the black hole spin parameter and the disc sound speed,
and is generally much less than 10% of the mode frequency. A sufficiently
strong excitation mechanism is needed to overcome this corotational damping and
make the mode observable.Comment: 10 pages, 5 figures, MNRAS in pres
Project Artemis
The goals of Project Artemis are designed to meet the challege of President Bush to return to the Moon, this time to stay. The first goal of the project is to establish a permanent manned base on the Moon for the purposes of scientific research and technological development. The knowledge gained from the establishment and operations of the lunar base will then be used to achieve the second goal of Project Artemis, the establishment of a manned base on the Martian surface. Throughout both phases of the program, crew safety will be the number one priority. There are four main issues that have governed the entire program: crew safety and mission success, commonality, growth potential, and costing and scheduling. These issues are discussed in more detail
Class A scavenger receptor 1 (MSR1) restricts hepatitis C virus replication by mediating toll-like receptor 3 recognition of viral RNAs produced in neighboring cells
Persistent infections with hepatitis C virus (HCV) may result in life-threatening liver disease, including cirrhosis and cancer, and impose an important burden on human health. Understanding how the virus is capable of achieving persistence in the majority of those infected is thus an important goal. Although HCV has evolved multiple mechanisms to disrupt and block cellular signaling pathways involved in the induction of interferon (IFN) responses, IFN-stimulated gene (ISG) expression is typically prominent in the HCV-infected liver. Here, we show that Toll-like receptor 3 (TLR3) expressed within uninfected hepatocytes is capable of sensing infection in adjacent cells, initiating a local antiviral response that partially restricts HCV replication. We demonstrate that this is dependent upon the expression of class A scavenger receptor type 1 (MSR1). MSR1 binds extracellular dsRNA, mediating its endocytosis and transport toward the endosome where it is engaged by TLR3, thereby triggering IFN responses in both infected and uninfected cells. RNAi-mediated knockdown of MSR1 expression blocks TLR3 sensing of HCV in infected hepatocyte cultures, leading to increased cellular permissiveness to virus infection. Exogenous expression of Myc-MSR1 restores TLR3 signaling in MSR1-depleted cells with subsequent induction of an antiviral state. A series of conserved basic residues within the carboxy-terminus of the collagen superfamily domain of MSR1 are required for binding and transport of dsRNA, and likely facilitate acidification-dependent release of dsRNA at the site of TLR3 expression in the endosome. Our findings reveal MSR1 to be a critical component of a TLR3-mediated pattern recognition receptor response that exerts an antiviral state in both infected and uninfected hepatocytes, thereby limiting the impact of HCV proteins that disrupt IFN signaling in infected cells and restricting the spread of HCV within the liver
Breaking of equipartition in one-dimensional heat-conducting systems
Using information-theoretical methods, we studied how energy equipartition is broken in one-dimensional systems under a heat flow composed of alternating particles of two different masses. The average energy stored in particles of different masses is seen to be different in both ideal gases and harmonic lattices
Coleman maps and the p-adic regulator
This paper is a sequel to our earlier paper "Wach modules and Iwasawa theory
for modular forms" (arXiv: 0912.1263), where we defined a family of Coleman
maps for a crystalline representation of the Galois group of Qp with
nonnegative Hodge-Tate weights. In this paper, we study these Coleman maps
using Perrin-Riou's p-adic regulator L_V. Denote by H(\Gamma) the algebra of
Qp-valued distributions on \Gamma = Gal(Qp(\mu (p^\infty) / Qp). Our first
result determines the H(\Gamma)-elementary divisors of the quotient of
D_{cris}(V) \otimes H(\Gamma) by the H(\Gamma)-submodule generated by (\phi *
N(V))^{\psi = 0}, where N(V) is the Wach module of V. By comparing the
determinant of this map with that of L_V (which can be computed via
Perrin-Riou's explicit reciprocity law), we obtain a precise description of the
images of the Coleman maps. In the case when V arises from a modular form, we
get some stronger results about the integral Coleman maps, and we can remove
many technical assumptions that were required in our previous work in order to
reformulate Kato's main conjecture in terms of cotorsion Selmer groups and
bounded p-adic L-functions.Comment: 27 page
- …