Simple solutions to the Einstein Equations in spaces with unusual topology

We discuss simple vacuum solutions to the Einstein Equations in five dimensional space-times compactified in two different ways. In such spaces, one black hole phase and more then one black string phase may exist. Several old metrics are adapted to new background topologies to yield new solutions to the Einstein Equations. We then briefly talk about the angular momentum they may carry, the horizon topology and phase transitions that may occur.Comment: Published versions. Includes referee input. 10 pages, 3 figure

Higher Order and Secondary Hochschild Cohomology

In this note we give a generalization for the higher order Hochschild cohomology and show that the secondary Hochschild cohomology is a particular case of this new construction

Measurement Method for Evaluating the Probability Distribution of the Quality Factor of Mode-Stirred Reverberation Chambers

An original experimental method for determining the empirical probability distribution function (PDF) of the quality factor (Q) of a mode-stirred reverberation chamber is presented. Spectral averaging of S-parameters across a relatively narrow frequency interval at a single pair of locations for the transmitting and receiving antennas is applied to estimate the stored and dissipated energy in the cavity, avoiding the need for spatial scanning to obtain spatial volume or surface averages. The effective number of simultaneously excited cavity modes per stir state, M, can be estimated by fitting the empirical distribution to the parametrized theoretical distribution. The measured results support a previously developed theoretical model for the PDF of Q and show that spectral averaging over a bandwidth as small as a few hundred kHz is sufficient to obtain accurate results.Comment: submitted for publicatio

Exact and heuristic allocation of multi-kernel applications to multi-FPGA platforms

FPGA-based accelerators demonstrated high energy efficiency compared to GPUs and CPUs. However, single FPGA designs may not achieve sufficient task parallelism. In this work, we optimize the mapping of high-performance multi-kernel applications, like Convolutional Neural Networks, to multi-FPGA platforms. First, we formulate the system level optimization problem, choosing within a huge design space the parallelism and number of compute units for each kernel in the pipeline. Then we solve it using a combination of Geometric Programming, producing the optimum performance solution given resource and DRAM bandwidth constraints, and a heuristic allocator of the compute units on the FPGA cluster.Peer ReviewedPostprint (author's final draft

Hidden symmetries in a gauge covariant approach, Hamiltonian reduction and oxidation

Hidden symmetries in a covariant Hamiltonian formulation are investigated involving gauge covariant equations of motion. The special role of the Stackel-Killing tensors is pointed out. A reduction procedure is used to reduce the original phase space to another one in which the symmetries are divided out. The reverse of the reduction procedure is done by stages performing the unfolding of the gauge transformation followed by the Eisenhart lift in connection with scalar potentials.Comment: 15 pages; based on a talk at QTS-7 Conference, Prague, August 7-13, 201

Vasopressin Antagonism in Heart Failure

Treatment of chronic heart failure (HF) is based on interference with the renin-angiotensin-aldosterone system and the adrenergic nervous system. Diuretics are used in volume-expanded patients. Insights from clinical trials and registries establish the need to consider correcting both cardiac loading conditions and nonload-related biological factors if HF therapy is to be optimized. Arginine vasopressin (AVP) represents a potentially attractive target for therapy in both acute and chronic HF. Excessive AVP secretion could contribute to both systolic and diastolic wall stress via V1a- and V2-mediated effects on the peripheral vasculature and on water retention. Arginine vasopressin also may directly and adversely affect myocardial function due to the effect of V1a activation on myocardial contractility and cell growth. Last, AVP may contribute to hyponatremia, a powerful predictor of poor outcome in HF. The development of effective nonpeptide antagonists to both the V1a and V2 receptors for AVP now allows for testing the hypotheses that interfering with AVP-mediated signaling could be beneficial in HF. This review summarizes the theoretical rationale for further development of such therapy, reviews the status of current compounds under development, and suggests key issues that need to be addressed as these agents undergo further clinical testing