A bioeconomic model of a ratio-dependent predator-prey system and optimal harvesting

This paper deals with the problem of a ratio-dependent prey-predator model with combined harvesting. The existence of steady states and their stability are studied using eigenvalue analysis. Boundedness of the exploited system is examined. We derive conditions for persistence and global stability of the system. The possibility of existence of bionomic equilibria has been considered. The problem of optimal harvest policy is then solved by using Pontryagin’s maximal principle.     

Efficient and high-power intracavity frequency doubled diode-side-pumped Nd:YAG/KTP continuous wave (CW) green laser

Highly efficient continuous wave (CW) green beam generation by intracavity frequency doubling of a diode side-pumped Nd:YAG laser using a single pump head based on a copper-coated flow tube in a V-shaped cavity geometry has been demonstrated. A maximum 30.5 W of CW green power was obtained at a total diode pumping power of 260 W corresponding to 11.7% conversion efficiency of diode pump power to CW green power and 4.7% conversion efficiency of electrical power to CW green power. The performance of the laser by considering the pump power induced thermal lensing effect and the M²-parameter at the fundamental wavelength has been analyzed.     

Second order Coriolis resonance between the C–O stretch and the CH3 rock levels of methanol involving excited torsional state

In this paper, it is shown that the interaction responsible for making the series of ‘forbidden' transitions from the state (nτK)=(110) in the ground vibrational (v=0) state to the levels of (122+) in the CH₃-rocking vibrational state (v=r) of methanol is ‘Coriolis' resonance and not ‘Fermi' resonance as proposed in a recent publication. This has been established from the J-dependence of the observed perturbed energy spacings between the two interacting pairs from high resolution spectroscopic analysis. The J-dependence clearly follows the classic ‘Coriolis' interaction matrix elements for ΔK=2, which would not occur if the interaction were due to ‘Fermi' resonance.     

Intermittency and fractals in nuclear collisions at 1.52 A GeV

The techniques of scaled factorial moments and multifractals have been employed to study the dynamical fluctuations of the produced singly charged particles in collisions of⁸⁴Kr ions at 1.52 A GeV in nuclear emulsion. The power law behaviors are observed in the data. The generalized dimensions are determined by using the methods of intermittency and multifractals.     

Carrier repopulation from plasma frequency measurement in many-valley semiconductors under high-field condition

The plasma frequency in many-valley semiconductors has been calculated under high field conditions. It is observed that the carrier population in the different valleys can be obtained from a measurement of the plasma frequency under high-field condition.     

Van der Waals interaction between spherical voids

The problem of calculating the non-retarded Van der Waals type of interaction between two spherical voids in an electron gas is presented from a new approach. The formulation is based on an integral equation for the self-induced density oscillations derived from a semi-classical treatment of the density-density response theory for inhomogeneous electron systems. The interaction energy between two identical voids is found to obey d^-6 law for large separation d between the voids, the law being determined by the dipolar plasma oscillations alone.     

Subharmonic gap structures in asymmetric superconducting tunnel junctions

Tunneling in the asymmetric superconducting junctions of PbIn and PbTl shows sharp current steps at voltages eV = Δ₁ + Δ₂,$\text{2Δ}{}_2\text{2n}\text{and}\text{2Δ}{}_1\text{2n}$ (structures for n > 1 not readily observed); 2Δ₁ and 2Δ₂ are the energy gaps and n is an integer. We obtain new results for the relative magnitude of the structures, where the larger of the two structures is observed at the larger of the two voltages $\text{Δ}{}_1\text{ρ}\text{and}\text{Δ}{}_2\text{ρ}$. These results, in contrast to other available experimental results on different superconductors, seem to exclude self-coupling theory as the mechanism.     

Polarization dynamics for spin 12-spin I systems with Breit-Rabi interaction

We study the full polarization dynamics of two interacting systems of spin $\text{1}\text{2}$ and spin I for the Breit-Rabi hamiltonian, the sum of contact hyperfine and Zeeman terms. We obtain the time dependence of the polarizations by solving the eigenvalue problems for the interaction hamiltonian and discuss some applications.     

Almost sure convergence of sums of maxima and minima of positive random variables

For a sequence of independent and identically distributed positive random variables, the almost sure convergence of sums of maxima (when suitably normalized) to appropriate constants is proved for both bounded and unbounded random variables. A similar result is also proved for sums of minima of such variables.