Gauge Theory Correlators from Non-Critical String Theory

We suggest a means of obtaining certain Green's functions in 3+1-dimensional ${\cal N} = 4$ supersymmetric Yang-Mills theory with a large number of colors via non-critical string theory. The non-critical string theory is related to critical string theory in anti-deSitter background. We introduce a boundary of the anti-deSitter space analogous to a cut-off on the Liouville coordinate of the two-dimensional string theory. Correlation functions of operators in the gauge theory are related to the dependence of the supergravity action on the boundary conditions. From the quadratic terms in supergravity we read off the anomalous dimensions. For operators that couple to massless string states it has been established through absorption calculations that the anomalous dimensions vanish, and we rederive this result. The operators that couple to massive string states at level $n$ acquire anomalous dimensions that grow as 2\left (n g_{YM} \sqrt {2 N} )^{1/2} for large `t Hooft coupling. This is a new prediction about the strong coupling behavior of large $N$ SYM theory.Comment: 15 pages, harvmac with btxmac; minor revisions, 1 reference added, the version to appear in Physics Letters

The gauge-string duality and heavy ion collisions

I review at a non-technical level the use of the gauge-string duality to study aspects of heavy ion collisions, with special emphasis on the trailing string calculation of heavy quark energy loss. I include some brief speculations on how variants of the trailing string construction could provide a toy model of black hole formation and evaporation. This essay is an invited contribution to "Forty Years of String Theory" and is aimed at philosophers and historians of science as well as physicists.Comment: 21 page

The Effects of Extended Depletion Region on Noise Modeling of HEMT ’s

In this paper we present a high frequency noise model for short channel HEMTs.This model takes into account the effect of depletion region that extends into gate to drain spacing.The effect of this high field extension region on the noise performance of three HEMT structures is analytically calculated and compared with measured data

Temperature dependent resistivity of spin-split subbands in GaAs 2D hole system

We calculate the temperature dependent resistivity in spin-split subbands induced by the inversion asymmetry of the confining potential in GaAs 2D hole systems. By considering both temperature dependent multisubband screening of impurity disorder and hole-hole scattering we find that the strength of the metallic behavior depends on the symmetry of the confining potential (i.e., spin-splitting) over a large range of hole density. At low density above the metal-insulator transition we find that effective disorder reduces the enhancement of the metallic behavior induced by spin-splitting. Our theory is in good qualitative agreement with existing experiments

Synthesis, Electrical Conductivity, and Dielectric Behaviour of Polyaniline Doped with H2SO4; HCl and (HCl + NaNO2) Mixture

Acid doped Polyaniline (PANI) due to their increased electrical conductivity, are considered to be the most promising conducting filler materials. Hence, the present study, reports the synthesis of the PANI followed by acid doping, electrical conductivity and dielectric properties measurements of H2SO4; HCl and (Conc. HCl + NaNO2mixture) doped PANI. In order to know the effect of acetone washing on the electrical properties of acid doped PANI samples, the electrical properties of the non-acetone washed acid doped PANI samples are compared with that of their acetone washed counterparts. The PANI salt was prepared by conventional route using aniline hydrochloride and ammonium persulphate as an oxidant. PANI salt was subjected to 0.5M NaOH to form PANI base, which was further doped separately with H2SO4; HCl and (Conc. HCl + NaNO2mixture) respectively followed by acetone washing. A comparative electrical conductivity study between the acetone washed and unwashed PANI salt and H2SO4, HCl and Conc. HCl + NaNO2 mixture doped PANI were characterized by dielectric and impedance study

Greybody Factors of Charged Dilaton Black Holes in 2 + 1 Dimensions

We have studied scalar perturbations of charged dilaton black holes in 2+1 dimensions. The black hole considered here is a solution to the low-energy string theory in 2+1 dimensions. The exact decay rates and the grey body factors for the massless minimally coupled scalar is computed for both the charged and the uncharged dilaton black holes. The charged and the uncharged black hole show similar behavior for grey body factors, reflection coefficients and decay rates.Comment: The equation for the potential and figure:1 are changed. The changes does not effect the result

Improvement of Strength and Radiation Protection Properties of Biodegradable Jute Fiber Reinforced Material

Over past few years, polymer composites with natural fiber reinforcement, called eco-composites, have achieved a worldwide compliance due to their strong potentiality to save the environment from pollution as a result of their ultimate disposability, as compared to glass-filled composites. Since natural fibers combine a low cost and low density with high toughness, biodegradability, renewability, reduced tool wear, and higher energy recovery. They are carbon dioxide neutral when burned and are present in abundance, which make composites made from them also sustainable and economical. We report a facile method for the improvement of strength and radiation protection properties of biodegradable jute fiber reinforced material by ceramic treatment of red mud. The developed powder was further blended with polyester resin to form thick, viscous radiation protection organic gel-based material. The developed protection gel material was then cured for making advanced non-toxic, biodegradable radiation protection panels using jute as natural fiber reinforcement. The developed radiation protection panels were analyzed by X-ray method with different energies of X-ray photons found to possess highly competent properties. Their various mechanical properties, like tensile, flexural, and impact strength values and morphological features were evaluated. The developed non-toxic, biodegradable, jute fiber reinforced, X-ray radiation protection panels combine good shielding and mechanical properties, which ensures their broad application spectrum ranging from diagnostic X-ray and CT scanner room installations to nuclear power plant and other strategic radiation shielding tasks.В настоящее время широкое применение получили композиты, армированные натуральными волокнами (экокомпозиты). В отличие от стеклопластиков, они подвержены биодеградации и безвредны для окружающей среды, имеют низкую стоимость и плотность, не выделяют вредных веществ при горении и расщепляются микроорганизмами. Предложена новая технология производства из краснозема биодеградируемого джутоволоконного материала с высокими прочностными и радиационно-защитными свойствами. Оценены проницаемость его рентгеновскими лучами, статическая прочность при разрыве и изгибе, а также ударная прочность. Проведены микроструктурные исследования. Полученные результаты подтверждают перспективность предложенной технологии производства из данного материала защитных панелей для рентгеновских кабинетов и другого оборудования радиационной защиты..На сьогодні широке застосування отримали композити, армовані натуральними волокнами (екокомпозити). На відміну від склопластиків, вони схильні до біодеградації і нешкідливі для навколишнього середовища, мають низьку вартість і щільність, не виділяють шкідливих речовин при горінні і розщеплюються мікроорганізмами. Запропоновано нову технологію виробництва з червонозему здатного до біодеградації джутоволоконного матеріалу з високими міцнісними та радіаційно-захисними властивостями. Оцінено проникність його рентгенівськими променями, статичну міцність при розриві і згині, а також ударну міцність. Проведено мікроструктурні дослідження. Отримані результати підтверджують перспективність запропонованої технології виробництва з цього матеріалу захисних панелей для рентгенівських кабінетів та іншого обладнання радіаційного захисту

AdS/CFT, Multitrace Deformations and New Instabilities of Nonlocal String Theories

We study "multitrace" deformations of large N master fields in models with a mass gap. In particular, we determine the conditions for the multitrace couplings to drive tachyonic instabilities. These tachyons represent new local instabilities of the associated nonlocal string theories. In the particular case of Dp-branes at finite temperature, we consider topology-changing phase transitions and the effect of multitrace perturbations on the corresponding phase diagrams.Comment: harvmac. 28 pages. 9 eps figure

Particle Production in Matrix Cosmology

We consider cosmological particle production in 1+1 dimensional string theory. The process is described most efficiently in terms of anomalies, but we also discuss the explicit mode expansions. In matrix cosmology the usual vacuum ambiguity of quantum fields in time-dependent backgrounds is resolved by the underlying matrix model. This leads to a finite energy density for the "in" state which cancels the effect of anomalous particle production.Comment: 24 pages, 1 figure; v2: references added, minor change

Landmark-based morphometric and meristic variations of endangered mrigal carp, Cirrhinus cirrhosus (Bloch 1795), from wild and hatchery stocks

Wild stocks of endangered mrigal carp, Cirrhinus cirrhosus (Bloch 1795), continues to decline rapidly in the Indo-Ganges river basin. With an objective to evaluate its population status, landmark-based morphometric and meristic variations among three different stocks viz., hatchery (Jessore), baor (Gopalganj) and river (Faridpur) in Bangladesh were studied. Significant differences were observed in 10 of the 15 morphometric measurements viz., head length, standard length, fork length, length of base of spinous, pre-orbital length, eye length, post-orbital length, length of upper jaw, height of pelvic fin and barbel length, two of the 8 meristic counts viz., scales above the lateral line and pectoral fin rays and 10 of the 22 truss network measurements viz., 1 to 10, 2 to 3, 2 to 8, 2 to 9, 2 to 10, 3 to 4, 3 to 8, 4 to 5, 4 to 7 and 9 to 10 among the stocks. For morphometric and landmark measurements, the 1st discriminant function (DF) accounted for 58.1% and the 2nd DF accounted for 41.9% of the among-group variability. In discriminant space, the river stock was isolated from the other two stocks. On the other hand, baor and hatchery stocks formed a very compact cluster. A dendrogram based on the hierarchical cluster analysis using morphometric and truss distance data placed the hatchery and baor in one cluster and the river in another cluster and the distance between the river and hatchery populations was the highest. Morphological differences among stocks are expected, because of their geographical isolation and their origin from different ancestors. The baseline information derived from the present study would be useful for genetic studies and in the assessment of environmental impacts on C. cirrhosus populations in Bangladesh