आँध्रप्रदेश की परुषकवचि (क्रस्टेशियाई) मात्स्यिकी संपदाएं

आँध्रप्रदेश की परुषकवचि (क्रस्टेशियाई) मात्स्यिकी संपदाए

Machine-Learned Potential Energy Surfaces for Free Sodium Clusters with Density Functional Accuracy: Applications to Melting

Gaussian Process Regression-based Gaussian Approximation Potential has been used to develop machine-learned interatomic potentials having density-functional accuracy for free sodium clusters. The training data was generated from a large sample of over 100,000 data points computed for clusters in the size range of N = 40 - 200, using the density-functional method as implemented in the VASP package. Two models have been developed, model M1 using data for N=55 only, and model M2 using additional data from larger clusters. The models are intended for computing thermodynamic properties using molecular dynamics. Hence, particular attention has been paid to improve the fitting of the forces. Interestingly, it turns out that the best fit can be obtained by carefully selecting a smaller number of data points viz. 1,900 and 1,300 configurations, respectively, for the two models M1 and M2. Although it was possible to obtain a good fit using the data of Na55 only, additional data points from larger clusters were needed to get better accuracies in energies and forces for larger sizes. Surprisingly, the model M1 could be significantly improved by adding about 50 data points per cluster from the larger sizes. Both models have been deployed to compute the heat capacities of Na55 and Na147 and to obtain about 40 isomers for larger clusters of sizes N = 147, 200, 201, and 252. There is an excellent agreement between the computed and experimentally measured melting temperatures. The geometries of these isomers when further optimized by DFT, the mean absolute error in the energies between DFT results and those of our models is about 7 meV/atom or less. The errors in the interatomic bond lengths are estimated to be below 2% in almost all the cases

Dynamical renormalization group methods in theory of eternal inflation

Dynamics of eternal inflation on the landscape admits description in terms of the Martin-Siggia-Rose (MSR) effective field theory that is in one-to-one correspondence with vacuum dynamics equations. On those sectors of the landscape, where transport properties of the probability measure for eternal inflation are important, renormalization group fixed points of the MSR effective action determine late time behavior of the probability measure. I argue that these RG fixed points may be relevant for the solution of the gauge invariance problem for eternal inflation.Comment: 11 pages; invited mini-review for Grav.Cos

El-Nino and its impacts on coral reef ecosystem in 289 the eastern Indian Ocean

The coral reef bleaching associated with the elevated Ocean temperature has been widely reported in the last three decades from different regions of the world. The rising temperature and acidification of Oceans makes a big challenge for the survival of reefs in the world. The other important stresses for the reefs include increased UV radiation, sea level variations, suspended sediments and increased turbidity of water. There are different studies which relate bleaching events with global warming and climate change. However, the increased frequency of mass bleaching events could not be sufficiently explained with current warming rates of the Ocean. Stone et al., (1999) put forward a new theory that recent increases in mass bleaching events were in response to the relative increase in El Niño experienced over the last two decades

Exploitation of penaeid shrimp resources by small mechanised trawlers off Visakhapatnam, Andhra Pradesh

Small trawlers (9-11 m OAL) fit for short-term cruises (2-7 days) exploit penaeid shrimps up to a depth of 70 m in the Bay of Bengal off Visakhapatnam both in the northern and southern directions. During the period 2001 to 2010, average annual fishing effort was 5,97,412 h. Penaeid shrimp catch varied from 703 t to 4,323 t with average catch per hour (cph) being 3.54 kg. The contribution of penaeid shrimps to total fish landings ranged from 6.7 to 18.32%, both fishing effort and landings of the resource showing increasing trend. Penaeid shrimp landing was supported by 24 species, dominated by Metapenaeus monoceros followed by Metapenaeus dobsoni. Mean annual species composition and cph for each species were estimated for two spells i.e., 2001 to 2005 and 2006 to 2010. Catch per hour for five species declined whereas it increased for the rest 19 species. The cph for penaeid shrimps increased by 103% from spell 1 to spell 2. Expected catch for each year was estimated by Schaefer production model (CEDA; r2=0.72) which showed that the resource was under exploitated during 2001-2005 and overexploited during 2006-2010, which indicate the necessity for restricting fishing effort at present level

Trends in penaeid shrimp landings by sona boats at Visakhapatnam Fishing Harbour, Andhra Pradesh

Sona boats operate mostly in the northern part of the Bay of Bengal up to sand heads. The boats (13-15 m OAL) worthy to conduct voyage fishing for 10-20 days exploit resources upto a depth of 100 m. The present study analysed the trends in penaeid shrimp landings by sona boats at Visakhapatnam Fishing Harbour, for the period from 2001 to 2010. During the period, annual fishing effort ranged from 4,77,710 to 16,31,507 h with an average of 10,15, 230 h. Annual penaeid shrimp catch varied from 1,409 to 7,496 t, average being 4,892 t. Average catch per hour (CPH) was estimated at 4.81 kg. Annual penaeid shrimp contribution from the sona boats to the total fish landings was 10.2 to 22% (average 15.9). Both fishing effort and penaeid shrimp catch showed increasing trend during the period. Penaeid shrimp fishery was supported by 14 genera/species dominated by Metapenaeus monoceros followed by M. dobsoni. Mean annual species composition and CPH for each species were computed for two span, first being 2001-2005 and the second during 2006-2010. The CPH for the penaeid shrimps increased by 1.5% from span-1 to span-2. CPH for smaller shrimp species declined whereas increased for commercial species. Expected catch for each year estimated by Schaefer production model (CEDA; r2=0.72) showed underexploitation during 2001 and 2004; optimum state of exploitation for four years during 2005, 2006, 2007 and 2009 and overexploitation for four years during 2002, 2003, 2008 and 2010. In terms of total fish landings, 2001 and 2002 showed underexploitation, optimum state during six years i.e., 2003, 2006, 2007, 2008, 2009 and 2010; while overexploitation during 2004 and 2005. Considering the exploitation rate of both penaeid shrimps and total fish, by sona boats, the study suggests restriction of fishing effort at the 2009-2010 level to ensure sustainability of the resources

Interactive video games to reduce paediatric procedural pain and anxiety: a systematic review and meta-analysis

Background: Procedural pain and anxiety in children can be poorly controlled, leading to significant short- and long-term sequelae, such as longer procedure times or future healthcare avoidance. Caregiver anxiety can exacerbate these effects. We aimed to evaluate the effect of interactive video game interventions on children's procedural pain and anxiety, including the effect of different types of video games on those outcomes. Methods: We conducted a systematic review and meta-analysis of the effectiveness of interactive video games compared with standard care in children (0–18 yr) undergoing painful procedures. We searched the databases MEDLINE, Embase, and PsycINFO. We conducted random-effects meta-analysis using ‘R’ of children's procedural pain and anxiety and caregivers' anxiety. Results: Of 2185 studies screened, 36 were eligible (n=3406 patients). Studies commonly involved venous access (33%) or day surgery (31%). Thirty-four studies were eligible for meta-analyses. Interactive video games appear to reduce children's procedural pain (standardised mean difference [SMD]=–0.43; 95% confidence interval [CI]: –0.67 to –0.20), anxiety (SMD=0.61; 95% CI: –0.88 to –0.34), and caregivers' procedural anxiety (SMD=–0.31; 95% CI: –0.58 to –0.04). We observed no difference between preparatory and distracting games, or between virtual reality and non-virtual reality games. We also observed no difference between interactive video games compared with standard care for most medical outcomes (e.g. procedure length), except a reduced need for restraint. Studies reported minimal adverse effects and typically had high intervention acceptability and satisfaction. Conclusions: Our findings support introducing easily available video games, such as distraction-based conventional video games, into routine practice to minimise paediatric procedural pain and child/caregiver anxiety

Autoionizing Resonances in Time-Dependent Density Functional Theory

Autoionizing resonances that arise from the interaction of a bound single-excitation with the continuum can be accurately captured with the presently used approximations in time-dependent density functional theory (TDDFT), but those arising from a bound double excitation cannot. In the former case, we explain how an adiabatic kernel, which has no frequency-dependence, can yet generate the strongly frequency-dependent resonant structures in the interacting response function, not present in the Kohn-Sham response function. In the case of the bound double-excitation, we explain that a strongly frequency-dependent kernel is needed, and derive one for the vicinity of a resonance of the latter type, as an {\it a posteriori} correction to the usual adiabatic approximations in TDDFT. Our approximation becomes exact for an isolated resonance in the limit of weak interaction, where one discrete state interacts with one continuum. We derive a "Fano TDDFT kernel" that reproduces the Fano lineshape within the TDDFT formalism, and also a dressed kernel, that operates on top of an adiabatic approximation. We illustrate our results on a simple model system.Comment: 10 pages, appeared in Special Issue in TDDFT in PCCP (2009

Three-dimensional femtosecond laser nanolithography of crystals

Nanostructuring hard optical crystals has so far been exclusively feasible at their surface, as stress induced crack formation and propagation has rendered high precision volume processes ineffective. We show that the inner chemical etching reactivity of a crystal can be enhanced at the nanoscale by more than five orders of magnitude by means of direct laser writing. The process allows to produce cm-scale arbitrary three-dimensional nanostructures with 100 nm feature sizes inside large crystals in absence of brittle fracture. To showcase the unique potential of the technique, we fabricate photonic structures such as sub-wavelength diffraction gratings and nanostructured optical waveguides capable of sustaining sub-wavelength propagating modes inside yttrium aluminum garnet crystals. This technique could enable the transfer of concepts from nanophotonics to the fields of solid state lasers and crystal optics.Comment: Submitted Manuscript and Supplementary Informatio