Density excitations of a harmonically trapped ideal gas

The dynamic structure factor of a harmonically trapped Bose gas has been calculated well above the Bose-Einstein condensation temperature by treating the gas cloud as a canonical ensemble of noninteracting classical particles. The static structure factor is found to vanish as wavenumber squared in the long-wavelength limit. We also incorporate a relaxation mechanism phenomenologically by including a stochastic friction force to study the dynamic structure factor. A significant temperature dependence of the density-fluctuation spectra is found. The Debye-Waller factor has been calculated for the trapped thermal cloud as function of wavenumber and of particle number. A substantial difference is found between clouds of small and large particle number

Systems development of a stall/spin research facility using remotely controlled/augmented aircraft models. Volume 1: Systems overview

A ground based, general purpose, real time, digital control system simulator (CSS) is specified, developed, and integrated with the existing instrumentation van of the testing facility. This CSS is built around a PDP-11/55, and its operational software was developed to meet the dual goal of providing the immediate capability to represent the F-18 drop model control laws and the flexibility for expansion to represent more complex control laws typical of control configured vehicles. Overviews of the two CSS's developed are reviewed as well as the overall system after their integration with the existing facility. Also the latest version of the F-18 drop model control laws (REV D) is described and the changes needed for its incorporation in the digital and analog CSS's are discussed

New attractor mechanism for spherically symmetric extremal black holes

We introduce a new attractor mechanism to find the entropy for spherically symmetric extremal black holes. The key ingredient is to find a two-dimensional (2D) dilaton gravity with the dilaton potential $V(\phi)$. The condition of an attractor is given by $\nabla^2\phi=V(\phi_0)$ and $\bar{R}_2=-V^{\prime}(\phi_0)$ and for a constant dilaton $\phi=\phi_0$, these are also used to find the location of the degenerate horizon $r=r_{e}$ of an extremal black hole. As a nontrivial example, we consider an extremal regular black hole obtained from the coupled system of Einstein gravity and nonlinear electrodynamics. The desired Bekenstein-Hawking entropy is successfully recovered from the generalized entropy formula combined with the 2D dilaton gravity, while the entropy function approach does not work for obtaining this entropy.Comment: 20 pages, 4 figures, Accepted for publication in Physical Review D. This version includes revisions suggested by the refere

The pathophysiology of edema formation in the nephrotic syndrome

The mechanism of edema formation in the nephrotic syndrome has long been a source of controversy. In this review, through the construct of Starling's forces, we examine the roles of albumin, intravascular volume, and neurohormones on edema formation and highlight the evolving literature on the role of primary sodium absorption in edema formation. We propose that a unifying mechanism of sodium retention is present in the nephrotic syndrome regardless of intravascular volume status and is due to the activation of epithelial sodium channel by serine proteases in the glomerular filtrate of nephrotic patients. Finally, we assert that mechanisms in addition to sodium retention are likely operant in the formation of nephrotic edema

Thermodynamic duality between RN black hole and 2D dilaton gravity

All thermodynamic quantities of the Reissner-Nordstr\"om (RN) black hole can be obtained from the dilaton and its potential of two dimensional (2D) dilaton gravity. The dual relations of four thermodynamic laws are also established. Furthermore, the near-horizon thermodynamics of the extremal RN black hole is completely described by the Jackiw-Teitelboim theory which is obtained by perturbing around the AdS$_2$-horizon.Comment: 10 pages, 3 figures, version accepted by MPL

Observations on Landslide Incidences in Himalayas in Kashmir Area

The Himalayas have been found to experience the highest frequency of landslide incidences, thereby, causing loss of life and property. The rocks of Himalaya are repeatedly deformed and are affected by the periodic reactivation of deepseated faults. The experiences in the area of landslide investigations reveal that these lineaments are characterised by the frequent occurrence of landslides. Recently, studies have been carried out on a number of landslides falling between Murree and Panjal thrust along the Karole-Kastigarh road in Ram ban area of Jammu & Kashmir. This paper is intended to present the salient features of some of these landslide studies