The Angular Size and Proper Motion of the Afterglow of GRB 030329

The bright, nearby (z=0.1685) gamma-ray burst of 29 March 2003 has presented us with the first opportunity to directly image the expansion of a GRB. This burst reached flux density levels at centimeter wavelengths more than 50 times brighter than any previously studied event. Here we present the results of a VLBI campaign using the VLBA, VLA, Green Bank, Effelsberg, Arecibo, and Westerbork telescopes that resolves the radio afterglow of GRB 030329 and constrains its rate of expansion. The size of the afterglow is found to be \~0.07 mas (0.2 pc) 25 days after the burst, and 0.17 mas (0.5 pc) 83 days after the burst, indicating an average velocity of 3-5 c. This expansion is consistent with expectations of the standard fireball model. We measure the projected proper motion of GRB 030329 in the sky to <0.3 mas in the 80 days following the burst. In observations taken 52 days after the burst we detect an additional compact component at a distance from the main component of 0.28 +/- 0.05 mas (0.80 pc). The presence of this component is not expected from the standard model.Comment: 12 pages including 2 figures, LaTeX. Accepted to ApJ Letters on May 14, 200

Food and feeding habit of a penaeid prawn Metapeneopsis stridulans (Alcock 1905)

Metapeneopsis stridulans feeds on a variety of food items, viz. diatoms, foraminiferans polychaetes, molluscs, crustaceans and detritus consisting of unidentifiable decaying matter along with sand and mud. The species does not show a preference for any particular food item. There is no significant difference in the food habits among the various size groups observed in the prawn. Monthwise feeding intensity for males and females shows males with empty stomach to be prevalent in most months

One-loop corrections, uncertainties and approximations in neutralino annihilations: Examples

The extracted value of the relic density has reached the few per-cent level precision. One can therefore no longer content oneself with calculations of this observable where the annihilation processes are computed at tree-level, especially in supersymmetry where radiative corrections are usually large. Implementing full one-loop corrections to all annihilation processes that would be needed in a scan over parameters is a daunting task. On the other hand one may ask whether the bulk of the corrections are taken into account through effective couplings of the neutralino that improve the tree-level calculation and would be easy to implement. We address this issue by concentrating in this first study on the neutralino coupling to i) fermions and sfermions and ii) Z. After constructing the effective couplings we compare their efficiency compared to the full one-loop calculation and comment on the failures and success of the approach. As a bonus we point out that large non decoupling effects of heavy sfermions could in principle be measured in the annihilation process, a point of interest in view of the latest limit on the squark masses from the LHC. We also comment on the scheme dependencies of the one-loop corrected results

The Rapidly Fading Afterglow from the Gamma-Ray Burst of 1999 May 6

We report on the discovery of the radio afterglow from the gamma-ray burst (GRB) of 1999 May 6 (GRB 990506) using the Very Large Array (VLA). The radio afterglow was detected at early times (1.5 days), but began to fade rapidly sometime between 1 and 5 days after the burst. If we attribute the radio emission to the forward shock from an expanding fireball, then this rapid onset of the decay in the radio predicts that the corresponding optical transient began to decay between 1 and 5 minutes after the burst. This could explain why no optical transient for GRB 990506 was detected in spite of numerous searches. The cause of the unusually rapid onset of the decay for the afterglow is probably the result of an isotropically energetic fireball expanding into a low density circumburst environment. At the location of the radio afterglow we find a faint (R ~ 24 mag) host galaxy with a double morphology.Comment: in press at ApJ Letters, 13 page LaTeX document includes 2 postscript figure

Giant single crystalline Au microplates

Single crystalline Au(111) surface is the most sought after platform for studying molecular and other inter-esting phenomena. Here we report the synthesis of giant Au(111) single crystalline microplates along with their prototype applications. The single-crystal surfaces are atomically flat and possess areas extending over &#8764;100,000 &#956;m2. The synthesis method is simple involv-ing a one-step thermolysis process, i.e. heating on a hot plate, of a alkylammonium salt, making the process flow easy and scalable for mass production. Other interesting anisotropic structures such as nanorods and microstars are also obtained by slightly varying the synthetic conditions

Impact of Guinea Grass, Congo Signal and \u3cem\u3eStylosanthes hamata\u3c/em\u3e on Soil Physico-Chemical Properties and Beneficial Micro Fauna in Mango and Sapota Plantations

Farming systems are considered to be most important upcoming enterprises to reduce soil erosion and land degradation besides provide timber, fruits, nutritious fodder for live stock population in the poor soil areas (Roy et.al., 2000). Horticulture based farming systems have been recommended as alternate land use systems for sustainable agriculture in semi arid ecosystem for efficient soil plant management and soil fertility management. Studies on micro flora and micro fauna under farming system are required to increase the farming system productivity. Higher species diversity of soil arthropods was observed in grassland system closely followed by the silvipasture systems when compared to areas having no vegetation in central India. Abundance, diversity and species richness decreased along the gradient, with the agricultural site presenting an impoverished community. Diversity descriptors were positively and significantly correlated with habitat diversity, measured on the basis of the proportion of the different soil-use types present at each land-use unit (Sousa et.al., 2004). The influence of three spatially hierarchical factors like local depth of the soil, ground cover type on the soil samples (bare ground, grass tufts, dead trees lying on the ground), dimensions of the grass tufts sampled (size and shape), significantly affected the morphospecies richness and/or density of the soil macrofauna. The type of ground cover had the strongest influence, affecting the total richness and density of the soil macro fauna and of almost all the groups represented. In the present study efforts were made to know the impact of guinea grass Panicum maximum, Congo signal grass Brachiaria ruziziensis and a legume Stylosanthes hamata on thephysico-chemical properties of mango and sapota based hortipasture systems

Towards a public analysis database for LHC new physics searches using MadAnalysis 5

We present the implementation, in the MadAnalysis 5 framework, of several ATLAS and CMS searches for supersymmetry in data recorded during the first run of the LHC. We provide extensive details on the validation of our implementations and propose to create a public analysis database within this framework.Comment: 20 pages, 15 figures, 5 recast codes; version accepted by EPJC (Dec 22, 2014) including a new section with guidelines for the experimental collaborations as well as for potential contributors to the PAD; complementary information can be found at http://madanalysis.irmp.ucl.ac.be/wiki/PhysicsAnalysisDatabas

OXIDATION OF IODIDE DURING RELEASE OF STORED ENERGY FROM GAMMA IRRADIATED CRYSTALLINE POTASSIUM BROMIDE IN AQUEOUS IODIDE SOLUTION

The stored energy in the form of color centers is released during dissolution of ?-irradiated crystalline   potassium bromide in aqueous potassium iodide solution. Various parameters like dose, amount and storage time of irradiated potassium bromide which control the yield of iodine have been studied. Similarly, the effect of concentration of potassium iodide has been investigated. The energy transfer parameter has been determined as the ratio of G/I2 obtained by the addition of irradiated crystalline potassium bromide on the basis of oxidation of iodide. Key words: - Irradiation, F-centre, Oxidation, Yield