Instabilities of the Small Black Hole: a view from N=4 SYM

We compute a one-loop effective action for the constant modes of the scalars and the Polyakov loop matrix of N=4 SYM on S^3 at finite temperature and weak 't Hooft coupling. Above a critical temperature, the effective potential develops new unstable directions accompanied by new saddle points which only preserve an SO(5) subgroup of the SO(6) global R-symmetry. We identify this phenomenon as the weak coupling version of the well known Gregory-Laflamme localization instability in the gravity dual of the strongly coupled field theory: The small AdS_5 black hole when viewed as a ten dimensional, asymptotically AdS_5 X S^5 solution smeared on the S^5 is unstable to localization on S^5. Our effective potential, in a specific Lorentzian continuation, can provide a qualitative holographic description of the decay of the "topological black hole'' into the AdS bubble of nothing.Comment: 39 pages, 6 figures, uses JHEP3.cls, references adde

Biodegradation of rocket propellant waste, ammonium perchlorate

The short term effects of ammonium perchlorate on selected organisms were studied. A long term experiment was also designed to assess the changes incurred by ammonium perchlorate on the nitrogen and chloride contents of soil within a period of 3 years. In addition, an attempt was made to produce methane gas from anaerobic fermentation of the aquatic weed, Alternanthera philoxeroides

Chemical sensing by nonequilibrium cooperative receptors

Cooperativity arising from local interactions in equilibrium receptor systems provides gain, but does not increase sensory performance, as measured by the signal-to-noise ratio (SNR) due to a fundamental tradeoff between gain and intrinsic noise. Here we allow sensing to be a nonequilibrium process and show that energy dissipation cannot circumvent the fundamental tradeoff, so that SNR is still optimal for independent receptors. For systems requiring high gain, nonequilibrium 2D-coupled receptors maximize SNR, revealing a new design principle for biological sensors

Modified quasilinearization method for solving nonlinear equations

Modified quasilinearization algorithm for solving nonlinear equation

Is it time for physician assistant (PA)/nurse practitioner (NP) hospital medicine residency training?

The roles of non-physician providers, such as physician assistants (PA) and nurse practitioners (NP), are constantly evolving in the United States healthcare system. They are a vital part of many inpatient multi-disciplinary teams and their role is even more challenging on the busy hospitalist services. The demand for hospitalists is constantly increasing and the current supply of physicians has been unable to keep up with the increase in demand. Residents' now restricted duty hours and regulations have further widened the gap. With a record number of patients seeking healthcare, a reliance on mid-level providers has increased tremendously in the last few years.Includes bibliographical reference

N=4 SYM on S^3 with Near Critical Chemical Potentials

We study the N = 4 theory at weak coupling, on a three sphere in the grand canonical ensemble with R symmetry chemical potentials. We focus attention on near critical values for the chemical potentials, above which the classical theory has no ground state. By computing a one loop effective potential for the light degrees of freedom in this regime, we show the existence of flat directions of complex dimension N, 2N and 3N for one, two and three critical chemical potentials respectively; these correspond to one half, one quarter and one-eighth BPS states becoming light respectively at the critical values. At small finite temperature we show that the chemical potentials can be continued beyond their classical limiting values to yield a deconfined metastable phase with lifetime diverging in the large N limit. Our low temperaure analysis complements the high temperature metastability found by Yamada and Yaffe. The resulting phase diagram at weak coupling bears a striking resemblance to the strong coupling phase diagram for charged AdS black holes. Our analysis also reveals subtle qualitative differences between the two regimes.Comment: 34 pages, 4 figure

Some aspects of the oxygen-deficient conditions and denitrification in the Arabian Sea

Utilizing a fairly large amount of recently collected data, some outstanding questions concerning the Arabian Sea denitrification problem are addressed. The true levels of dissolved oxygen, determined colorimetrically, are about an order of magnitude lower than those reported previously from the oxygen minimum zone. Lateral advection of waters from south into the oxygen-deficient layer is suggested by the presence of an intermediate oxygen maximum discernible even at very low oxygen levels. An unusual minimum in nitrate and a corresponding maximum in nitrite are observed occasionally within the depth range 700–1,200 m at several stations, generally located in the northeastern Arabian Sea. These features probably represent the development of a deeper denitrifying layer, in addition to the main denitrifying layer invariably found in the northern Arabian Sea at shallower depths. The deeper layer appears to be related to an increase in particulate organic carbon, probably resulting from seasonal changes in primary production, lateral advection of waters from the slope region off the Indian coast, or an in-situ production of organic matter. Reoccupation of a number of stations reveals large short-term variability in denitrification intensity. Associated with the temporal variability, the southern boundary of denitrification appears to oscillate between Lats. 12 and 14N, except in the western Arabian Sea where it might shift to 18N during the southwest monsoon. Peak values of the integrated deficits do not occur within or near zones of high biological productivity; i.e., along the eastern and western boundaries. This is attributed to a more intense renewal of waters along these margins, through the northerly flow of waters, relatively rich in oxygen, to compensate for the vertical advection (upwelling) off Arabia, and through a hitherto undetected undercurrent off the west coast of India. Well-defined tongues of high and low integrated deficits, alternately extending northward and southward, respectively, possibly reflect net transports within the oxygen-deficient layer.Rate of denitrification in the Arabian Sea is estimated from the exports of nitrate deficits out of the denitrification zone. The results indicate that the horizontal processes are responsible for the removal of the bulk (\u3e85%) of the deficits. The deduced rate (29.5 × 1012 gN y−1) is at least an order of magnitude higher than the previous estimates. Combining this value with the estimated standing crop of denitrified nitrogen, the renewal time of the oxygen-deficient layer is deduced as ∼4 y. The short renewal time, supported by tritium data, is consistent with the observed short-term variability in denitrification intensity. The high rate of denitrification deduced in the present study appears to conform to global trends. It is suggested that currently accepted estimates of oceanic water column denitrification should be scaled-up by 40 to 100% in view of the present results

Study Of Phenothiazine On p53 Core Domain Mutant Y220C: Finding The Anti-tumor Activity Of Phenothiazine

The tumor suppressor protein p53 is a transcription factor that plays a key role in the prevention of cancer development. The p53 cancer mutation Y220C induces formation of a cavity on the protein's surface that can accommodate stabilizing small molecules. We have attempted with the help of virtual screening and molecular docking approach using Lamarckian Genetic Algorithm to elucidate the extent of specificity of p53 cancer mutation Y220C towards different class of Phenothiazines (an anti-cancer agent). 

The 393 residue p53 tumor suppressor protein exists in a dynamic equilibrium to form homotetramers. Each chain comprises several functional domains. The N terminal part of the protein consists of the trans-activation domain (residues 1–63) followed by a proline rich region (64– 92). The central (core) domain (p53 core domain) is responsible for binding. The C terminal part of p53 contains the tetramerization domain (residues 326–355) and the negative regulatory domain at the extreme C terminus (363–393), which contains phosphorylation and acetylation sites and regulates the DNA binding activity of p53.

The docking result of the study of 2,000 Phenothiazines demonstrated that the binding energies were in the range of -10.54 kcal/mol to -1.14 kcal/mol, with 8 molecules showing hydrogen bonds with the active site residues (Lys 164). All the selected 2000 inhibitors were selected on the basis of the structural specificity to the enzyme towards its substrate and inhibitors. Our research provides a blueprint for the design of more potent and specific drugs that rescue p53-Y220C

Portfolio optimisation with higher moments of risk at the Pakistan Stock Exchange

Stock markets play an important role in spurring economic growth and development through diversification opportunities. However, diversification cannot be truly achieved if we continue to ignore additional dimensions of risk, namely skewness and kurtosis. This study incorporates higher moments of risk to form a mean-varianceskewness-kurtosis based framework for portfolio optimisation. Inclusion of higher moments in optimisation framework acknowledges the risk of asymmetric returns and fat-tail risk and can help investors in formulating optimal portfolios of stocks which can be significantly divergent from the ones they obtain through the Markowitz meanvariance optimisation. Our results confirm the presence of tradeoff between returns and additional dimensions of risk in Pakistan Stock Exchange (PSX) and strongly suggest including them in the optimisation framework to avoid sub-optimal decisions and to curtail exposure towards higher moments of risks