The bottomside parameters <i>B0</i>, <i>B1</i> obtained from incoherent scatter measurements during a solar maximum and their comparisons with the IRI-2001 model

International audienceHigh resolution electron density profiles (Ne) measured with the Arecibo (18.4 N, 66.7 W), Incoherent Scatter radar (I. S.) are used to obtain the bottomside shape parameters B0, B1 for a solar maximum period (1989?90). Median values of these parameters are compared with those obtained from the IRI-2001 model. It is observed that during summer, the IRI values agree fairly well with the Arecibo values, though the numbers are somewhat larger during the daytime. Discrepancies occur during winter and equinox, when the IRI underestimates B0 for the local times from about 12:00 LT to about 20:00 LT. Furthermore, the IRI model tends to generally overestimate B1 at all local times. At Arecibo, B0 increases by about 50%, and B1 decreases by about 30% from solar minimum to solar maximum

Status of Bioprospecting of Marine Molluscs in India

Continuous pressure on the environment arising inevitably or otherwise out of technological progress and human population growth has made it necessary to place a commodity value on biodiversity (Randall, 1991)

Effect of immunostimulant on enhancement of the immune response of kuruma shrimp Marsupenaeus japonicus and its resistance against White Spot Syndrome Virus (WSSV)

An experiment of 45 days duration to test the efficacy of the Vibrio alginolyticus as an immunostimulant was conducted in Marsupenaeus japonicus against white spot syndrome virus (WSSV) infection, considered as one of the serious pathogens of shrimps. The shrimps were fed with the experimental diets coated with different concentrations of bacteria of 17 ml / kg feed and 10 % of animal body wt. They were challenged with WSSV to assess the increase in survival rate and growth if any due to immune enhancement. Another group of shrimp was used for drawing the haemolymph to estimate the increase in the level of prophenoloxidase activity. Samplings for the above said analysis were carried out at 15 days interval for a period of 45 days. The highest prophenoloxidase activity (39.78 with sand substrate-T1) and the highest survival rate (66.66 % with sand substrate-T1) and highest growth rate (7.04 % in 17ml/kg- with sand substrate-T1) were recorded in experimental diet (17 ml / kg feed). Hence the 17 ml / kg feed of Vibrio alginolyticus formalin killed added to the diet could be an eco-friendly and economically viable immunostimulant for penaeid shrimps

Diurnal and seasonal variations of <i>hm</i>F2 deduced from digitalionosonde over New Delhi and its comparison with IRI 2001

International audienceUsing digital ionosonde observations at a low mid-latitude station, New Delhi (28.6°N, 77.2°E, dip 42.4°N), we have derived hourly monthly values of hmF2 (the real height corresponding to the peak electron density in the F2-region), employing both the Dudeney (1983) and Bilitza (1990) empirical formulations for the period from January 2001 to August 2002. The diurnal and seasonal variations of hmF2 are analyzed. Further, to assess the predictability of the latest available model, International Reference Ionosphere, (IRI-2001), we have obtained the median values of hmF2 derived from M(3000)F2 for each hour during different seasons and compare these with the model. Our results show that both the Dudeney (1983) and Bilitza (1990) formulations reveal more or less a similar diurnal trend of hmF2, with higher values around midnight and lower during sunrise, in all the seasons. It is also noted that the hmF2 shows a larger variability around midnight than by daytime, in all the seasons. Further, the study shows that median values of observed hmF2, using both formulations, are somewhat larger than those predicted by the IRI, in all seasons and at all local times. During summer, the IRI values agree comparatively well with the observations, especially during daytime. Major discrepancies occur when the IRI underestimates observed hmF2 for local times from about 14:00 LT to 18:00 LT and 04:00 LT to 05:00 LT during winter and equinox, where the percentage deviation of the observed hmF2 values with respect to the IRI model varies from 15 to 25%. The difference between the model and observations, outside this time period, remains less than 20% during all the seasons. Key words. Ionosphere (modelling and forecasting; equatorial ionosphere

DLCQ of Fivebranes, Large N Screening, and L^2 Harmonic Forms on Calabi Manifolds

We find one explicit L^2 harmonic form for every Calabi manifold. Calabi manifolds are known to arise in low energy dynamics of solitons in Yang-Mills theories, and the L^2 harmonic form corresponds to the supersymmetric ground state. As the normalizable ground state of a single U(N) instanton, it is related to the bound state of a single D0 to multiple coincident D4's in the non-commutative setting, or equivalently a unit Kaluza-Klein mode in DLCQ of fivebrane worldvolume theory. As the ground state of nonabelian massless monopoles realized around a monopole-``anti''-monopole pair, it shows how the long range force between the pair is screened in a manner reminiscent of large N behavior of quark-anti-quark potential found in AdS/CFT correspondence.Comment: LaTeX, 23 page

Identification of Gut Microflora from Green Mussel (Perna viridis)

The main source of Bacterial contamination of Estuary waters are domestic waste water and sewage discharge. In this present investigation, Green Mussels were collected from three different stations of Chennai Coast - Ennore, Royapuram and Muttukadu. The mussels were degutted and bacteria were isolated using selective and non-selective agar medium and further confirmed by biochemical tests. The organisms were ident illed to generic or group level according to Bergey's manual of systematic Bacteriology. Different group of fecal coli forms and Vibrio spp. have been isolated. Escherichia coli, Vibrio alginolyticus, V. parahaemolyticus and V. harveyi were the dominant species. Vibrio parahaemolyticus, a facultative pathogen widely complicated in outbreaks of gastroenteritis related to the consumption of improperly processed seafood was present in the gut of Green Mussels

Seasonal Variations and Identification of Pathogenic Pollution Indicators from Royapuram Backwaters

Sewage and industrial effluents from Ennore, Chennai harbour and surrounding area have a greater impact on the Royapuram back water affecting the aquatic animals and in tum the human population. These waste carry enormous number of microbial pathogens and other heavy metals resulting in greater economic loss. The current study is aimed at analysing the total viable count of bacteria and pathogenic bacterial species in the water and sediment samples taken from different places of Royapuram fishing area, from where many kind of fishes and molluscans are taken for human consumption .The samples werc collected in pre monsoon, monsoon and post monsoon seasons. Water analysis was done by multiple tube tests to assess the MPN values. The bacteria were isolated using Zobell's agar medium, selective and non selective medias and identified using biochemical test. The organisms were identified to genus, level according to Bergey's manual. Results of field Investigations showed a definite association between the levels pollution and microbial population. Results showed a higher distribution of pathogenic and non pathogenic bacteria in the sediment than in the water sample both in monsoon and post monsoon seasons. Analysis showed the prevalence of human pathogens and fecal indicator organisms like Escherichia coli, Salmonella sp.,Vibrio sp., Shigella sp. in water and in the sediment samples