1,492 research outputs found
Dual-hop transmissions with fixed-gain relays over Generalized-Gamma fading channels
In this paper, a study on the end-to-end performance of dual-hop wireless communication systems equipped with fixed-gain relays and operating over Generalized-Gamma (GG) fading channels is presented. A novel closed form expression for the moments of the end-to-end signal-to-noise ratio (SNR) is derived. The average bit error probability for coherent and non-coherent modulation schemes as well as the end-to-end outage probability of the considered system are also studied. Extensive numerically evaluated and computer simulations results are presented that verify the accuracy of the proposed mathematical analysis.\u
Tidal Love numbers of neutron stars in gravity
The recent detection of gravitational waves from a neutron star merger was a
significant step towards constraining the nuclear matter equation of state by
using the tidal Love numbers (TLNs) of the merging neutron stars. Measuring or
constraining the neutron star TLNs allows us in principle to exclude or
constraint many equations of state. This approach, however, has the drawback
that many modified theories of gravity could produce deviations from General
Relativity similar to the deviations coming from the uncertainties in the
equation of state. The first and the most natural step in resolving the
mentioned problem is to quantify the effects on the TLNs from the modifications
of General Relativity. With this motivation in mind, in the present paper we
calculate the TLNs of (non-rotating) neutron stars in gravity. For this
purpose, we first derived the equations describing both the polar and the axial
stationary perturbations of neutron stars in a particular class of
gravity, the so-called -gravity. Then, by solving numerically the
perturbation equations, we calculate explicitly the polar and the axial
TLNs of the neutron stars in -gravity for three characteristic realistic
equations of state. Our results show that while the polar TLNs are slightly
influenced by the modification of General Relativity, the axial TLNs can
be several times larger (in terms of the absolute value) compared to the
general relativistic case.Comment: 10 pages, 3 figure
Oxidative protein folding in the mitochondrial intermembrane space
Disulfide bond formation is a crucial step for oxidative folding and necessary for the acquisition of a protein's native conformation. Introduction of disulfide bonds is catalyzed in specialized subcellular compartments and requires the coordinated action of specific enzymes. The intermembrane space of mitochondria has recently been found to harbor a dedicated machinery that promotes the oxidative folding of substrate proteins by shuttling disulfide bonds. The newly identified oxidative pathway consists of the redox-regulated receptor Mia40 and the sulfhydryl oxidase Erv1. Proteins destined to the intermembrane space are trapped by a disulfide relay mechanism that involves an electron cascade from the incoming substrate to Mia40, then on to Erv1, and finally to molecular oxygen via cytochrome c. This thiol–disulfide exchange mechanism is essential for the import and for maintaining the structural stability of the incoming precursors. In this review we describe the mechanistic parameters that define the interaction and oxidation of the substrate proteins in light of the recent publications in the mitochondrial oxidative folding field
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