Concave grating spectrometer Patent

Concave grating spectrometer for use in near and vacuum ultraviolet region

The fundamental group of reductive Borel-Serre and Satake compactifications

Let $G$ be an almost simple, simply connected algebraic group defined over a number field $k$, and let $S$ be a finite set of places of $k$ including all infinite places. Let $X$ be the product over $v\in S$ of the symmetric spaces associated to $G(k_v)$, when $v$ is an infinite place, and the Bruhat-Tits buildings associated to $G(k_v)$, when $v$ is a finite place. The main result of this paper is an explicit computation of the fundamental group of the reductive Borel-Serre compactification of $\Gamma\backslash X$, where $\Gamma$ is an $S$-arithmetic subgroup of $G$. In the case that $\Gamma$ is neat, we show that this fundamental group is isomorphic to $\Gamma/E\Gamma$, where $E\Gamma$ is the subgroup generated by the elements of $\Gamma$ belonging to unipotent radicals of $k$-parabolic subgroups. Analogous computations of the fundamental group of the Satake compactifications are made. It is noteworthy that calculations of the congruence subgroup kernel $C(S,G)$ yield similar results.Comment: 21 pages, 1 figure, uses Xy-pic 3.8.6; in version 2, title changed to more accurately reflect main result, expository material on congruence subgroup problem removed, many small corrections and improvements in expositio

Ornamental fish resources of Lakshadweep

In the lagoons of Lakshadweep islands, omamental fishes of the families Labridae, Pomacentridae, Serranidae, Acanthuridae, Chaetodontidae, Callyodontidae, Mullidae, Balistidae, Holocentridae, Canthigasteridae, Pomacanthidae and Zanclidae, represented by a total of 191 species are important. Preliminary estimates show that Kalpeni has the largest population size, followed by Amini, Kadamat, Chetlat, Kavaratti, Agatti, Kiltan and Bitra; population per hectare was found to be highest in Amini, followed by Chetlat, Kalpeni, Kiltan, Kadamat, Kavaratti, Bitra and Agatti. Certain measures for sustainable exploitation of omamental fishes are indicate

Multispecies stock assessment with particular reference to major demersal fish species in the trawling grounds off Kakinada

On the basis of data of four dominant demersal finfish species landed by trawlers at Kakinada, the method of multispecies stock assessment using the Beverton and Holt model is described and the problems involved are discussed. It is shown that with the presmt gear in use, the effort has to be reduced by about 6% to get MSY or with the present effort unchanged, the cod end mesh size has to he increased by 28 % to get MSY. The latter option is considered to be the best because the present lengths at first capture are less than the lengths at first maturity, a situation that, if allowed to continue, can l«ad to recruitment overfishing

Mixed fisheries assessment with reference to five important demersal fish species landed by shrimp trawlers at Kakinada

Data collected on five species in the by-catch of shrimp trawlers at Kakinada (Andra Pradesh) during 1984-86 are used for a length based cohort analysis and Thompson and Bell assessments. An assessment of this mixed fishery is also carried out. The methods used are described in detail and problems involved in estimating the important parameters to assess mixed trawl fisheries are discussed

Catalogue of Fishes (excluding from the Laccadives) in the Reference Collections of the Central Marine Fisheries Research Institute

This Bulletin, a catalogue of fishes, is in continuation of the previous three in the series dealing with the biological specimens kept in the Reference Collections of the Central Marine Fisheries Research Institute, Mandapam Camp. The present catalogue lists 569 species of fishes (excluding those from the Laccadives which appeared in Bulletin No. 8); 35 of them are under 9 families of Elasmobranchii and the rest under 131 families of Teleostomi. Most of them are marine, the fresh water fishes in the collections forming only a very small proportion. There is adequate representation of the major exploited species supporting fisheries of coastal waters. Since the main objective has been the collection of commercially important fish species by the research workers engaged in investigations on specified groups, the material listed does not adequately represent the marine fish fauna around India, which has on record very many more than the number of species listed here. The collections have been made by a number of scientific workers of this Institute from the time of its inception, but the task of cataloguing the material has been entrusted to Mr. V. Sriramachandra Murty, who I am glad to say has accomplished this work in a very satisfactory manner. To him and to my other colleagues of thi