609 research outputs found

    Spin Hot Spots in vertically-coupled Few-electron Quantum Dots

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    The effects of spin-orbit (SO) coupling arising from the confinement potential in single and two vertically-coupled quantum dots have been investigated. Our work indicates that a dot containing a single electron shows the lifting of the degeneracy of dipole-allowed transitions at B=0 due to the SO coupling which disappears for a dot containing two electrons. For coupled dots with one electron in each dot, the optical spectra is not affected by the coupling and is the same as the dot containing one electron. However, for the case of two coupled dots where one partner dot has two interacting electrons while the other dot has only one electron, a remarkable effect is observed where the oscillator strength of two out of four dipole-allowed transition lines disappears as the distance between the dots is decreased

    Stock assessment and management options for whelks along south-eastern Arabian Sea

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    Two species of whelks viz., Babylonia spirata and Babylonia zeylanica belonging to the family Buccinidae are commercially fished from Kollam, south-west coast of India, since early 1990’s and are exported from India under the trade name ‘Baigai’. The species is present all through the year in the fishing grounds, caught as by-catch in shrimp trawlers and is a targeted fishery from April to June, when more than 50% of the annual whelk catch is taken. B. zeylanica dominates the whelk catch (61% of the annual catch). The average catch rate in the modified trawlers for whelk was 400 kg unit-1 day-1. Following the von Bertalanffy growth function, asymptotic length and growth rate were estimated as 68.7 mm and 1.08 respectively for B. spirata and as 76 mm and 1.15 respectively for B. zeylanica. The L50 estimated for B. spirata and B. zeylanica were 35.2 and 41.7 mm respectively. The optimum length of capture and mean generation time were 40 mm and 0.55 years for B. spirata and 44 mm and 0.48 years for B. zeylanica respectively. The annual mean length of B. spirata showed an increase from 37.4 mm in 2001 to 40.1 mm in 2002 and multiple cohorts have been observed. The relative yield-per-recruit analysis shows that, present rate of exploitation of B. spirata has reached the optimum and that of B. zeylanica has nearly attained the optimum. The faster growth rate, early maturity and continuous breeding behaviour explain the sustained fishery of B. spirata and B. zeylanica under a high fishing pressure along Kollam coast

    Methodology in molecular genetics and its applications to diabetology

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    Charge Radius And Neutron Skin Thickness Of Platinum And Osmium Isotopes Near The Nuclear Drip Lines

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    Background: The density distributions of exotic nuclei are different from that of stable nuclei. For stable nuclei, charge radii can be obtained through electron scattering experiments. The excessive neutrons in neutron-rich nuclei make a decoupling of neutron and proton distribution and as a result nuclear skin structures are appeared.Purpose: The charge radius and the way by which nucleons are distributed can provide information about size, surface thickness and shell structure of nuclei. The information collected from such nuclei can be used for astrophysical studies to understand the origin of heavy elements. Methods: In the present study, we have made an attempt to investigate the charge radii, rms radii and skin thickness of Pt and Os isotopes. Here, the calculations were made by using the HFB solver which utilizes HO single-particle basis and iteratively diagonalizes the HFB Hamiltonian based on the Skyrme forces.Results: Here we can observe an increase in charge radius, rms radius and skin thickness with neutron number. The charge radii calculated are in good agreement with the experimental data and predictions of RCHB model. A linear dependence of skin thickness on neutron number is observed with the change in slope is noticed around N =126.Conclusion: Using HFB theory, we have analyzed the charge radius and neutron skin thickness of Pt and Os isotopes. The drip line nuclei have larger charge radius in comparison to the stable nuclei. The redistribution of the nucleons due to addition of neutrons leads to the gradual increase in neutron skin. The sudden increase of skin thickness may be due to the extra stability and shell closure around the magic number

    A Hartree-Fock-Bogoliubov Study on the Pairing Correlations of the Isotopes of Cobalt

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    Background: The phenomena of nucleon pairing could be outlined from the Bethe-Weizäcker semi-empirical formula, from which the nuclear properties, viz. the binding energy, stability, shape etc. could be clearly sketched. Though the pairing correlation seems to be a small correction to the binding energy term, it plays a determinative role in defining the structure of nuclear systems. The addition to the binding energy in turn affects the position of the isotope on the dripline and hence increases the stability. Purpose: To study the effects of pairing on the ground state properties of the isotopes of Cobalt. Methods: We use Hartree-Fock-Bogoliubov (HFB) theory for the study. The general wave functions for the HFB approach are determined from variational principle. The eigen functions for the Hamiltonian are connected with the particle operators through the Bogoliubov transformations. The Hartree-Fock energy is obtained through the minimization of the variational parameter and the HFB equation is solved by iterative diagonalization by restoring the particle number symmetry. Results: The HFB analysis substantiates the effect of pairing correlation on binding energies, neutron and proton pairing energies, neutron and proton pairing gaps and one- and two-neutron separation energies of the Cobalt isotopes. The binding energies and one and two-neutron separation energies match with the experimental values and for pairing energies and pairing gaps, the regions where pairing is significant and the effects of shell closure at the vicinity of magic configuration of neutrons could be recognized. Conclusion: The Hartree-Fock-Bogoliubov calculations of the effects of pairing could be used as an efficient tool to study the nuclear structure. It can be ascertained that pairing plays an important role in determining the ground state properties of atomic nuclei


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    In this paper, we propose a technique to measure the Elasticity Modulus of the textile material using flex LVDT. Elasticity modulus is measured indirectly by measuring stiffness of the material first. The material whose stiffness is to be measured is subjected to a known force and the deflection caused in the material due to applied load is measured using the LVDT. Here the whole measurement is done dynamically without halting the manufacturing line of process. The output of LVDT is AC voltage. AC-DC converter is used to convert the AC output voltage of LVDT to DC output voltage. This is cascaded to the ANN block programmed on the LabVIEW platform. The results show that the proposed technique has achieved its proposed objectives