1,122 research outputs found

    Relaxation of Collective Excitations in LJ-13 Cluster

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    We have performed classical molecular dynamics simulation of Ar13Ar_{13} cluster to study the behavior of collective excitations. In the solid ``phase'' of the cluster, the collective oscillation of the monopole mode can be well fitted to a damped harmonic oscillator. The parameters of the equivalent damped harmonic oscillator-- the damping coefficient, spring constant, time period of oscillation and the mass of the oscillator -- all show a sharp change in behavior at a kinetic temperature of about 7.0oK7.0^oK. This marks yet another characteristic temperature of the system, a temperature TsT_s below which collective excitations are very stable, and at higher temperatures the single particle excitations cause the damping of the collective oscillations. We argue that so long as the cluster remains confined within the global potential energy minimum the collective excitations do not decay; and once the cluster comes out of this well, the local potential energy minima pockets act as single particle excitation channels in destroying the collective motion. The effect is manifest in almost all the physical observables of the cluster.Comment: Revised and enlarged. 6 pages RevTeX style. 7 eps figures available on request. To appear in J Chem Phy

    Studies on the fishery of the penaeid prawn Metapenaeus affinis (Milne Edwards) Along the Mangalore coast

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    Tbe fishery anl certain features of the population structures of M. affiMs caught by the trawlers fran 1962 through 1971 are reported. The fishery was chiefly i^odal and was dominated by large size groups early in the season and smaller size groups later. The maximum number of broods entering the fishery was observed to be four. Age and growth studies indicated that tbe males attain a length of about 95, 140 and 160 mm and females, lOO, 143 and 170 mm at the end of one, two and three years, respectively. The miniminn size at first maturity for males was found tp be 116 mm. The average annual instantaneous fishing mwtality was found to be 3.76 for males and 2.50 for females between one and two year olds

    Comfort Level Refinement of Military Tracked Vehicle Crew through Optimal Control Study

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    Military tracked vehicle and crew are modelled together in this paper as integrated man-machine lumped parameter model, by integrating the simplified 5 degrees of freedom (DoF) tracked vehicle model, including seat and 4 DoF human bio-dynamic model, thus resulting in a 9 DoF simplified vehicle-occupant model. Then the natural frequency of major mass segment namely the chassis mass is obtained through simulation study, for a known road input. The value obtained is compared with that of an earlier research work, for validation of said man-machine model. Then focusing our study locally at crew seat location, parameters of crew seat suspension for ride comfort are optimised using the optimal digital state space controller designed for this purpose by implementing it in a 2 DoF occupant - seat suspension model and its Simulink model constructed. Simulation results illustrate the attainment of the goal by meeting the controller design requirements

    Ergonomic Level Improving of Armoured Fighting Vehicle Crew

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    The armoured fighting vehicle (AFV)-occupant composite system is modelled as a lumped parameter system, in this paper, wherein the 4 degrees of freedom (dof) biodynamic occupant model is integrated with 10 dof in-plane AFV model including the crew seat, thus leading to the 14 dof vehicle-occupant composite model and the governing equations of motion are obtained. The composite model is subjected to idealised road input simulating the ground reaction forces. Natural frequencies and the frequency domain vibration responses of various masses of model are obtained. The natural frequency of chassis thus obtained is compared with the result established by an earlier research work, to validate the model. The study is focused on crew seat location. A 2 dof occupant-seat suspension model is formulated and validated through case study. The optimised values of seat suspension parameters for ride comfort are obtained using the said model, through two methods of Invariant points theory and genetic algorithm toolbox of Matlab 2014a software. Acceleration responses of body for the current and optimised parameter values obtained illustrate that comfort of crew is improved with optimised values through minimization in the acceleration responses

    Trichodesmium bloom and the failure of oil sardine fishery

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    The occurrence of Trichodesmium blooms off Mangalore from the lalter half of February to early March in 1968 and its adverse effect on the oil sardine fishery have been reported in this account. Some of the environmental factors such as temperature, salinity, oxygen content and wind velocity and direction associated with the blooming have also been discusse

    Age for measles immunization seroconversion after measles vaccination at 6-8 months of age - A randomised controlled trial

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    The, objective of the study was to compare the effectiveness of measles vaccine by seroconversion in vaccinated children with non-vaccinated children of 6 to 8 months age group in a city slam community so as to study the feasibility of advancing the age of immunization. Live attenuated lyophilized Schwartz strain of measles vaccine was used. Hemagglutination inhibition (HI) antibody was estimated. Seroconversion was defined as either the conversion of negative to positive or a two fold rise in titre. One hundred and thirty two children completed the study. There was no difference in the age, sex and nutritional status between vaccinated and non-vaccinated groups (p>0.7). The seroconversion rate in the vaccinated group was 65% and in the non-vaccinated group was 26%. The age, sex and nutritional status did not significantly affect the seroconversion. Oar data suggest that immunization with measles vaccine may be effective as early as 6 months of age. Immunization at 6 months may be needed at least for children in densely populated areas like cities and towns

    Polyphenol-rich pomegranate fruit extract (POMx) suppresses PMACI-induced expression of pro-inflammatory cytokines by inhibiting the activation of MAP Kinases and NF-╬║B in human KU812 cells

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    <p>Abstract</p> <p>Background</p> <p>Mast cells and basophils are multifunctional effector cells and contain plentiful secretary granules in their cytoplasm. These cell types are involved in several inflammatory and immune events and are known to produce an array of mediators including a broad spectrum of cytokines. Pomegranate fruit is rich in anthocyanins and hydrolysable tannins; a group of polyphenolic compounds shown to be potent antioxidant with anti-inflammatory activity. However, no studies have been undertaken to investigate whether a polyphenol-rich pomegranate fruit extract (POMx) inhibits the inflammatory activity of activated human mast cells and basophils. The aim of this study was to examine whether POMx modulates inflammatory reactions using human basophilic cell line KU812.</p> <p>Methods</p> <p>KU812 cells were stimulated with phorbol-12-myristate 13-acetate plus calcium inophore A23187 (PMACI). The inhibitory effect of POMx on pro-inflammatory cytokine gene expression and production by stimulated KU812 cells was measured by quantitative RT-PCR, and cytokine-specific ELISA assays, respectively. Western blotting was used to analyze the effect of POMx on the activation of mitogen-activated protein kinases (MAPKs), and the nuclear factor (NF)-╬║B in PMACI stimulated KU812 cells. Effect on the activity of NF-╬║B was determined using Luciferase reporter assay. Significance of differences from control values were analyzed by means of standard statistical methods.</p> <p>Results</p> <p>POMx significantly decreased PMACI stimulated inflammatory gene expression and production of interleukin (IL)-6 and IL-8 in KU812 cells. The inhibitory effect of POMx on the pro-inflammatory cytokines was MAPK subgroups c-jun N-terminal kinase (JNK)- and extracellular-regulated kinase (ERK) dependent. In addition, POMx suppressed the NF-╬║B activation induced by PMACI by inhibiting I╬║B-degradation in human basophil cells. POMx also suppressed the powerful induction of NF-╬║B promoter-mediated luciferase activity in transiently transfected KU812 cells.</p> <p>Conclusion</p> <p>These novel pharmacological actions of POMx provide new suggestion that POMx or POMx-derived compounds may be of therapeutic use for the treatment of inflammatory diseases by suppressing mast cells/basophils activation.</p

    Fishery resources of Ullal (Mangalore) in relation to certain environmental factors during 1963-67

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    Ullal, an important fishing centre situated 3 Km south of Mangalore, was known for shark fishery in the past. However, owing to the decline in the shark fishery, fishing for sardine, mackerel etc has been resorted to bottom dwelling during the past two decades. While Mangalore is at present a landing centre for ground fishes of the mechanised boats, Ullal is of special significance, being the nearest fishing village where variout' types of indigenous gears are employed mainly for pelagic fishes. Yet, the fishery potentiality of this area has remained unknown

    An indigenous cluster beam apparatus with a reflectron time-of-flight mass spectrometer

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    The design and fabrication of a Smalley-type cluster source in combination with a reflectron based time-of-flight (TOF) mass spectrometer are reported. The generation of clusters is based on supersonic jet expansion of the sampling plume. Sample cells for both liquid and solid targets developed for this purpose are described. Two pulsed Nd-YAG lasers are used in tandem, one (532 nm) for target vapourization and the other (355 nm) for cluster ionization. Methanol clusters of nuclearity up to 14 (mass 500 amu) were produced from liquid methanol as the test sample. The clusters were detected with a mass resolution of ~2500 in the R-TOF geometry. Carbon clusters up to a nuclearity of 28 were obtained using a polyimide target. The utility of the instrument is demonstrated by carrying out experiments to generate mixed clusters from alcohol mixtures
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