Ratio dependent predation :A bifurcation analysis

In this study, we have considered a prey-predator model reflecting the predator interference with discrete time delay. This delay is regarded as the lag due to gestation. In absence of delay, the criteria for existence of interior equilibrium and its global stability are derived. By choosing the delay as a bifurcation parameter, we have shown that a Hopf bifurcation may occur when the delay passes its critical value. Finally, we have derived the criteria for stability switches and verified the results through computer simulation.     

An Extensive Survey of the Characteristics of Pseudorapidity Distributions in Hadron-Nucleus Collisions at High and Ultra High Energies

This paper presents an extensive study of the nature of the pseudorapidity distribution in hadron-nucleus collision in emulsion from accelerator energy to super high cosmic ray energies (24 GeV/c to 4 TeV). The energy and the target dependence of the distributions and their possible significance are also discussed.     

Exploiting silver trifluoromethanesulfonate as efficient and reusable catalyst for the synthesis of dihydropyrimidine derivatives under different reaction environments

Different results were generated under different reaction conditions for the multicomponent reactions. Herein, an efficiently improved and mild protocol for the synthesis of dihydropyrimidine derivatives using cheap silver trifluoromethanesulfonate (CF₃SO₃Ag) as reusable catalyst is explained. With conventional heating and microwave irradiation method, the synthesis of substituted 3,4‐dihydropyrimidine‐2(1H)‐one and 3,4‐dihydropyrimidine‐2(1H)‐thione was achieved in different solvent environments like acetonitrile, water, and under solvent free neat condition. Moreover, the solvents (CH₃CN and H₂O) containing the CF₃SO₃Ag were reused for several times without loss of much catalytic activity after separation from the desired products. Thus, the method provides much improved and efficient alternative pathway to the original Biginelli reaction.     

Cosmology with weak lensing surveys

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future.     

Indium(III) catalysed substrate selective hydrothiolation of terminal alkynes

In(OTf)(3) is reported as the first catalyst having the ability to selectively catalyse both Markovnikov and anti-Markovnikov hydrothiolation of terminal alkynes under identical reaction conditions depending upon the nature of the thiol employed.     

Strategies and tactics in olefin metathesis

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Wavelet modeling of priors on triangles

Parameters in statistical problems often live in a geometry of certain shape. For example, count probabilities in a multinomial distribution belong to a simplex. For these problems, Bayesian analysis needs to model priors satisfying certain constraints imposed by the geometry. This paper investigates modeling of priors on triangles by use of wavelets constructed specifically for triangles. Theoretical analysis and numerical simulations show that our modeling is flexible and is superior to the commonly used Dirichlet prior.     

Target mass dependence of mean slow particle multiplicity in high energy hadron-nucleus interaction

This work presents a study on the dependence of mean slow particle multiplicity (N_h) on the mass numberA of the target nucleus for a wide range of target mass and energy. It has been shown that this dependence can be best expressed by the relation N _h= 0.57A^0.61.The author would like to express his indebtedness to Prof. A. Herz (CERN), Prof. K. D. Tolostov (JINR), Prof. R. Wilkes (University of Washington) for kindly supplying the exposed emulsion plates.     

Hydrothermal synthesis of dimeric lanthanide compounds: X-ray structure,magnetic study and heterogeneous catalytic epoxidation of olefins

A series of dimeric lanthanide carboxylato complexes [La(5-Br-NIC)₃(H₂O)₂]₂·H₂O (1); [Gd(5-Br-NIC)₃(H₂O)₂]₂ (2), [5-Br-NIC = 5-bromonicotinate] and [Sm(NIC)₃(H₂O)₂]₂ (3) [NIC = nicotinate], have been hydrothermally synthesized and structurally characterized by single crystal X-ray analysis. Complexes 1, 2 and 3 are of similar structure and consist of a basic unit [La(carboxylato)₃(H₂O)₂]₂. In compound 1 lanthanide cation is surrounded by one chelating 5-bromo-nicotinato ligand, two bridging oxygen atoms from 5-bromo-nicotinato and two water molecules, in which each La(III) ion is nine coordinated in a tricapped prismatic geometry. However, in compounds 2 and 3 four carboxylate groups link a pair of lanthanide atoms in the O,O′-bridging mode to generate a paddle-wheel-like centrosymmetric dimer. All the compounds exhibit excellent catalytic performance in olefin epoxidation reaction. The variable temperature magnetic susceptibility measurements showed that the magnetic interaction in [Gd(5-Br-NIC)₃(H₂O)₂]₂ (2), is antiferromagnetic (J = −0.048 cm⁻¹), while compound [Sm(NIC)₃(H₂O)₂]₂ (3), showed a complicated low-temperature magnetic property.     

A Novel Chiral Auxiliary for Enantioselective Synthesis of Tertiary Alcohol

The use of 1-menthyl ester of 1,3-dithiane-2-carboxylic acid as a chiral auxilary for the conversion of acetophenone, propiophenone and butyrophenone to the corresponding optically active tertiary alcohols 2-phenylhexan-2-ol, 3-phenylheptan-3-ol and 4-phenyloctan-4-ol, has been demonstrated.