479 research outputs found
Pedagogies, perspectives, and practices: mobile leraning through the experiences of faculty developers and instructional designers in centers for teaching and learning
Higher-dimensional solitons and black holes with a non-minimally coupled scalar field
We study higher-dimensional soliton and hairy black hole solutions of the
Einstein equations non-minimally coupled to a scalar field. The scalar field
has no self-interaction potential but a cosmological constant is included.
Non-trivial solutions exist only when the cosmological constant is negative and
the constant governing the coupling of the scalar field to the Ricci scalar
curvature is positive. At least some of these solutions are stable when this
coupling constant is not too large.Comment: 17 pages, revtex4, 21 figures, minor changes to match published
versio
Information gap for classical and quantum communication in a Schwarzschild spacetime
Communication between a free-falling observer and an observer hovering above
the Schwarzschild horizon of a black hole suffers from Unruh-Hawking noise,
which degrades communication channels. Ignoring time dilation, which affects
all channels equally, we show that for bosonic communication using single and
dual rail encoding the classical channel capacity reaches a finite value and
the quantum coherent information tends to zero. We conclude that classical
correlations still exist at infinite acceleration, whereas the quantum
coherence is fully removed.Comment: 5 pages, 4 figure
Clinical surveillance of thrombotic microangiopathies in Scotland, 2003-2005
The prevalence, incidence and outcomes of haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP) are not well established in adults or children from prospective studies. We sought to identify both outcomes and current management strategies using prospective, national surveillance of HUS and TTP, from 2003 to 2005 inclusive. We also investigated the links between these disorders and factors implicated in the aetiology of HUS and TTP including infections, chemotherapy, and immunosuppression. Most cases of HUS were caused by verocytotoxin-producing Escherichia coli (VTEC), of which serotype O157 predominated, although other serotypes were identified. The list of predisposing factors for TTP was more varied although use of immunosuppressive agents and severe sepsis, were the most frequent precipitants. The study demonstrates that while differentiating between HUS and TTP is sometimes difficult, in most cases the two syndromes have quite different predisposing factors and clinical parameters, enabling clinical and epidemiological profiling for these disorders
NASA/ASEE Summer Faculty Fellowship Program. 1994 research reports
This document is a collection of technical reports on research conducted by the participants in the 1994 NASA/ASEE Summer Faculty Fellowship Program at Kennedy Space Center (KSC). This was the tenth year that a NASA/ASEE program has been conducted at KSC. The 1994 program was administered by the University of Central Florida in cooperation with KSC. The program was operated under the auspices of the American Society for Engineering Education (ASEE) with sponsorship and funding from the Office of Educational Affairs, NASA Headquarters, Washington, D.C. The KSC Program was one of nine such Aeronautics and Space Research Programs funded by NASA Headquarters in 1994. The NASA/ASEE program is intended to be a two-year program to allow in-depth research by the University faculty member. The editors of this document were responsible for selecting appropriately qualified faculty to address some of the many problems of current interest to NASA/KSC
The Yeast Mitochondrial Proteins Rcf1 And Rcf2 Support the Enzymology of The Cytochrome C Oxidase Complex and Generation of The Proton Motive Force
The yeast mitochondrial proteins Rcf1 and Rcf2 are associated with a subpopulation of the cytochrome bc1–cytochrome c oxidase supercomplex and have been proposed to play a role in the assembly and/or modulation of the activity of the cytochrome c oxidase (complex IV, CIV). Yeast mutants deficient in either Rcf1 or Rcf2 proteins can use aerobic respiration–based metabolism for growth, but the absence of both proteins results in a strong growth defect. In this study, using assorted biochemical and biophysical analyses of Rcf1/Rcf2 single and double null-mutant yeast cells and mitochondria, we further explored how Rcf1 and Rcf2 support aerobic respiration and growth. We show that the absence of Rcf1 physically reduces the levels of CIV and diminishes the ability of the CIV that is present to maintain a normal mitochondrial proton motive force (PMF). Although the absence of Rcf2 did not noticeably affect the physical content of CIV, the PMF generated by CIV was also lower than normal. Our results indicate that the detrimental effects of the absence of Rcf1 and Rcf2 proteins on the CIV complex are distinct in terms of CIV assembly/accumulation and additive in terms of the ability of CIV to generate PMF. Thus, the combined absence of Rcf1 and Rcf2 alters both CIV physiology and assembly. We conclude that the slow aerobic growth of the Rcf1/Rcf2 double null mutant results from diminished generation of mitochondrial PMF by CIV and limits the level of CIV activity required for maintenance of the PMF and growth under aerobic conditions
Hypoxia-inducible Gene Domain 1 Proteins in Yeast Mitochondria Protect Against Proton Leak Through Complex IV
Hypoxia-inducible gene domain 1 (HIGD1) proteins are small integral membrane proteins, conserved from bacteria to humans, that associate with oxidative phosphorylation supercomplexes. Using yeast as a model organism, we have shown previously that its two HIGD1 proteins, Rcf1 and Rcf2, are required for the generation and maintenance of a normal membrane potential (ΔΨ) across the inner mitochondrial membrane (IMM). We postulated that the lower ΔΨ observed in the absence of the HIGD1 proteins may be due to decreased proton pumping by complex IV (CIV) or enhanced leak of protons across the IMM. Here we measured the ΔΨ generated by complex III (CIII) to discriminate between these possibilities. First, we found that the decreased ΔΨ observed in the absence of the HIGD1 proteins cannot be due to decreased proton pumping by CIV because CIII, operating alone, also exhibited a decreased ΔΨ when HIGD1 proteins were absent. Because CIII can neither lower its pumping stoichiometry nor transfer protons completely across the IMM, this result indicates that HIGD1 protein ablation enhances proton leak across the IMM. Second, we demonstrate that this proton leak occurs through CIV because ΔΨ generation by CIII is restored when CIV is removed from the cell. Third, the proton leak appeared to take place through an inactive population of CIV that accumulates when HIGD1 proteins are absent. We conclude that HIGD1 proteins in yeast prevent CIV inactivation, likely by preventing the loss of lipids bound within the Cox3 protein of CIV
Fundamental limitations to information transfer in accelerated frames
We study communication between an inertial observer and one of two
causally-disconnected counter accelerating observers. We will restrict the
quantum channel considering inertial-to-accelerated bipartite classical and
quantum communication over different sets of Unruh modes (single-rail or
dual-rail encoding). We find that the coherent information (and therefore, the
amount of entanglement that can be generated via state merging protocol) in
this strongly restricted channel presents some interesting monogamy properties
between the inertial and only one of the accelerated observers if we take a
fixed choice of the Unruh mode used in the channel. The optimization of the
controllable parameters is also studied and we find that they deviate from the
values usually employed in the literature.Comment: 7 pages, 6 figure
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