Prospects of inflation in delicate D-brane cosmology

We study D-brane inflation in a warped conifold background that includes brane-position dependent corrections for the nonperturbative superpotential. Instead of stabilizing the volume modulus chi at instantaneous minima of the potential and studying the inflation dynamics with an effective single field (radial distance between a brane and an anti-brane) phi, we investigate the multi-field inflation scenario involving these two fields. The two-field dynamics with the potential V(phi,chi) in this model is significantly different from the effective single-field description in terms of the field phi when the field chi is integrated out. The latter picture underestimates the total number of e-foldings even by one order of magnitude. We show that a correct single-field description is provided by a field psi obtained from a rotation in the two-field space along the background trajectory. This model can give a large number of e-foldings required to solve flatness and horizon problems at the expense of fine-tunings of model parameters. We also estimate the spectra of density perturbations and show that the slow-roll parameter eta_{psi psi}=M_{pl}^2 V_{,psi psi}/V in terms of the rotated field psi determines the spectral index of scalar metric perturbations. We find that it is generally difficult to satisfy, simultaneously, both constraints of the spectral index and the COBE normalization, while the tensor to scalar ratio is sufficiently small to match with observations.Comment: 12 pages, 8 figures, version to appear in Physical Review

Comparison of Erosional Features by Tsunami and Wind Waves

The erosion features from tsunami wave and wind wave are different according to the characteristics of the two kinds of waves. The tsunami wave is a shallow water wave, even in Deep Ocean, with very long wavelength and relatively high especially near shore. It does not break when attacking the shore. It composed of run-up and run-down. The waves which can scour the offshore sea bottom and deposit the sediment mostly sand on the coast called storm or tsunami over washes. The erosion features from storm wave are caused by the breaking waves and wind-driven currents. However, the erosion features from tsunami wave are caused by both run-up and run-down. The scouring pit and trough by tsunami run-down usually are larger and deeper than those by tsunami run-up due to the stronger run-down which flow down slope and carrying debris. Examples of these features on Indian coasts are shown. Investigations of these features are important to the preventive measures for coastal erosion by these natural disasters. The characteristics of the flows of tsunami and wind wave cause the different erosion features and degree of erosion. The morphology of the coast modifies the intensity of the flow and the detail features along the coast. Examples of erosion features by strong wind and tsunami 2004 are shown on the Indian coasts

Effect of heating or cooling in a suspension of phototactic algae with no-slip boundary conditions

In this study, we investigate the impact of heating or cooling in a suspension experiencing phototactic bioconvection. The suspension is illuminated by collimated irradiation from the top and subjected to heating or cooling from the bottom. The governing equations include the Navier Stokes equations with the Boussinesq approximation, the diffusion equation for motile microorganisms, and the energy equation for temperature. Employing linear perturbation theory, we analyse the linear stability of the suspension. The findings predict that the suspension undergoes destabilization when heated from below and stabilization when cooled from below. This suggests a sensitive dependence of the system's stability on the thermal conditions, providing valuable insights into the behavior of phototactic bioconvection under different heating or cooling scenarios

Estimation of unsteady lift on a pitching airfoil from wake velocity surveys

The results of a joint experimental and computational study on the flowfield over a periodically pitched NACA0012 airfoil, and the resultant lift variation, are reported in this paper. The lift variation over a cycle of oscillation, and hence the lift hysteresis loop, is estimated from the velocity distribution in the wake measured or computed for successive phases of the cycle. Experimentally, the estimated lift hysteresis loops are compared with available data from the literature as well as with limited force balance measurements. Computationally, the estimated lift variations are compared with the corresponding variation obtained from the surface pressure distribution. Four analytical formulations for the lift estimation from wake surveys are considered and relative successes of the four are discussed

Compact stars within an asy-soft quark-meson-coupling model

We investigate compact star properties within the quark meson coupling model (QMC) with a soft symmetry energy density dependence at large densities. In particular, the hyperon content and the mass/radius curves for the families of stars obtained within the model are discussed. The hyperon-meson couplings are chosen according to experimental values of the hyperon nuclear matter potentials, and possible uncertainties are considered. It is shown that a softer symmetry energy gives rise to stars with less hyperons, smaller radii and larger masses. Hyperon-meson couplings may also have a strong effect on the mass of the star.Comment: 7 pages, revtex, accepted in Phys. Rev.

The properties of active galaxies at the extreme of eigenvector 1

Eigenvector 1 (EV1) is the formal parameter which allows the introduction of some order in the properties of the unobscured type 1 active galaxies. We aim to understand the nature of this parameter by analyzing the most extreme examples of quasars with the highest possible values of the corresponding eigenvalues $R_{Fe}$. We selected the appropriate sources from the Sloan Digital Sky Survey (SDSS) and performed detailed modeling, including various templates for the Fe II pseudo-continuum and the starlight contribution to the spectrum. Out of 27 sources with $R_{Fe}$ larger than 1.3 and with the measurement errors smaller than 20\% selected from the SDSS quasar catalog, only six sources were confirmed to have a high value of $R_{Fe}$, defined as being above 1.3. All other sources have $an R_{Fe}$ of approximately 1. Three of the high $R_{Fe}$ objects have a very narrow H$\beta$ line, below 2100 km s$^{-1}$ but three sources have broad lines, above 4500 km s$^{-1}$, that do not seem to form a uniform group, differing considerably in black hole mass and Eddington ratio; they simply have a very similar EW([OIII]5007) line. Therefore, the interpretation of the EV1 remains an open issue.Comment: Astronomy and Astrophysics (in press

Damage and Degradation Study of FRP Composites

The present experimental study aims at assessing the different effects of the varying environments on the mechanical properties of FRP composites. The mechanical performance of a composite material is decisively controlled by the state of fiber-matrix interface . Its properties influence the integrity of composite behavior because of its role in transferring stress between the fiber and the matrix. The factors affecting the interface are too complex to be precisely concluded. Fibrous composites are increasingly being used in many casual as well as critical applications owing to various desirable properties including high specific strength, high specific stiffness and controlled anisotropy. But unfortunately polymeric composites are susceptible to heat and moisture when operating in changing environmental conditions. Samples of several Glass-Epoxy composites were manufactured using the traditional hand layup method where the stacking of the plies were alternate and the weight fraction of fiber and matrix was kept at 40-60%.Specimens were cut according to the ASTM D 2344-84(1989) standards. Some of the specimens were kept in the As-cured condition so as to obtain the base properties. Experimental studies have been carried out to study the effects of thermal ageing, liquid nitrogen temperature, thermal shocks, sea and distilled water. Also, tests have been performed to study the effect of ultraviolet rays and microwave conditions on the mechanical behavior of Glass-epoxy composites. The specimens were divided into groups. One group was subjected to cryogenic conditions at -750C for 3 hours and 6 hours. Another group was subjected to elevated temperature at +750C for 5 hours and 10 hours. A separate group samples were immersed in the two mediums separately namely sea water , distilled water at their boiling temperatures .Of the remaining samples a group of samples were kept in a microwave oven for 60 , 90 and 120 secs. whereas the other part of it was kept in a ultraviolet chamber for a period of 100 hrs. Thermal shocks of two types, up-cycle (lower to higher temperature immersion) and down-cycle (higher to lower temperature immersion) were applied The aged samples were subjected to 3-point short beam shear tests. The tests were performed at room temperature with 1 mm/min and 500 mm/min crosshead speeds. The weakening effects were sensitive to loading rate. The ILSS(shear strength) values were then compared with the base values of as cured specimen SEM analysis was done to ascertain the mode of failure

Self-consistent quantum effects in the quark meson coupling model

We derive the equation of state of nuclear matter including vacuum polarization effects arising from the nucleons and the sigma mesons in the quark-meson coupling model which incorporates explicitly quark degrees of freedom with quark coupled to the scalar and vector mesons. This leads to a softer equation of state for nuclear matter giving a lower value of incompressibility than would be reached without quantum effects. The {\it in-medium} nucleon and sigma meson masses are also calculated in a self-consistent manner.Comment: 10 pages, latex, 5 figure

Occurrence of algal stem blotch in ber (Ziziphus mauritiana) under coastal Odisha conditions in India

The investigation was carried out during 2017-18 to identify and document the emerging diseases of Indian Jujube or ber (Ziziphus mauritiana Lamk.) in Odisha state located in Eastern part of India. Periodical visit and subsequent investigations revealed the occurrence of a new kind of stem blotch disease in ber caused by alga. Symptoms were observed on bark of the stem and branches as bright red velvety blotch colonies during July- September 2017. However dull grey blotches were visible throughout the year. Leaves and fruits were left unaffected. The algal stem blotch occurrence was assessed during the year 2018 and disease severity rangedfrom 9.4-14.8 per cent. The green alga was identified and confirmed as Trentepohlia arborum (Agardh) Hariot based on key morphological characters. The stem blotches lead to death of young twigs measured between 3 to 8 mm thickness on primary and secondary branches wherein thickness of branches was more than 10 mm, algal blotches caused cracking of bark. Present study highlights the causal agent of stem blotch of ber, its symptomatology, impact of disease and suggested management practices