Some aspects of the biology of Tachysurus tenuispinis Day from Veraval

The regression coefficients in length-weight relationship of males and females of Tachysurus tenuispinis differ significantly. The relative condition factor was calculated for females in relation to various lengths and months. The sex ratio in the catch varied widely in the different months. The number of eggs ranged from 72 to 89 for the fish of length 394 to 570 mm. Empty stomachs occurred in a very high percentage (63.5%) of the total stomachs examined. This is a bottom carnivorous feeder. The main food items found in the guts in order of preference were crustaceans, polychaetes, molluscs, fishes and echinoderms.

Switching aspects of hybrid semiconductor power devices

A hybrid semiconductor power device has been designed which combines IGBT switching and thyristor on-state characteristics. A single gate signal controls the switching and triggers the transitions between an IGBT and a thyristor mode of operation. This paper discusses aspects of the switching behaviour of this and of similar devices. Simulation results of an example structure are presented and conceivable developments in the switching characteristics of hybrid devices are discussed.

Eyes on their fingertips: some aspects of the arts, science, technology and culture of the fisherfolk of Trivandrum, India

Eyes on Their Finger Tips deals with the traditional marine wisdom of a set of people and the rarest of rare experiences they have had at sea. Through these numerous chapters he takes us into the seas of the fishers. It is a voyage which we cannot make in reality. But through the heroic deeds of his father, the riddles of oldman Sebesti, the shark story of brother Kamalappan, and the rituals of his mother, we get a fascinating peep into the wisdom of the watery world of the small-scale fishers of Trivandrum, Kerala, India.

Fault-tolerant aspects of MPC

The architecture of model predictive control (MPC), with its explicit internal model and constrained optimization is presented. Since MPC relies on an explicit internal model, one can imagine dealing with failures by updating the internal model, and letting the on-line optimizer work out how to control the system in its new condition. This aspects rely on assumptions such that the nature of the fault can be located, and the model can be updated automatically. A standard form of MPC, with linear inequality constraints on inputs and outputs, linear internal model, and quadriatic cost function.

Fault-tolerant aspects of MPC

The various aspects of fault-tolerant control systems that have the ability to survive major equipment failures or damages are discussed. Model predictive control (MPC) offers a promising basis for fault-tolerant control. Failures can be dealt with by updating internal models and letting the on-line optimizer control the system in its new condition. Fault detection and isolation (FDI) and the management of complex models are two emerging technologies in this field.

Switching aspects of hybrid semiconductor power devices

A hybrid semiconductor power device has been designed which combines IGBT switching and thyristor on-state characteristics. A single gate signal controls the switching and triggers the transitions between an IGBT and a thyristor mode of operation. This paper discusses aspects of the switching behaviour of this and of similar devices. Simulation results of an example structure are presented and conceivable developments in the switching characteristics of hybrid devices are discussed.

Some aspects of fisheries of the Sylhet basin, Northeast Bangladesh

A comprehensive study on the fisheries aspect was done in the Sylhet basin, Bangladesh during 1994 through 1998. Maximum fishing effort was engaged in the period of April to September while the bulk catch came during the September-January, when less effort was exerted. Barbs comprised 19%, catfishes 18% and major carps 16% of the total catch. Chatla beel, a three years pile, showed the highest fish production. Nine types of nets, four types of hooks and five types of traps were found in operation in the basin. The highest daily mean catch was recorded in glzer jal (26.5 kg/day) and the lowest in the clzandi jal (2.5 kg/day). Behundi jal was the most efficient (0.89 kg/man/h) while chandi jal was the worst (0.12 kg/man/h) gear. Gill net (/ash jal) seems to be the best selective gear. Actual catch/effort always remained less than the projected catch/effort. Maximum economic point of effort lies around 7.0 mandays/km2 and the fishery is gradually moving towards over-fishing. Income of professional fishermen was comparatively high than that of non-professional subsistence groups.

Study of the electric loading aspects of the BDFM using a lumped parameter thermal model

Details of a lumped parameter thermal model for studying thermal aspects of the frame size 180 nested loop rotor BDFM at the University of Cambridge are presented. Predictions of the model are verified against measured end winding and rotor bar temperatures that were measured with the machine excited from a DC source. The model is used to assess the thermal coupling between the stator windings and rotor heating. The thermal coupling between the stator windings is assessed by studying the difference of the steady state temperatures of the two stator end windings for different excitations. The rotor heating is assessed by studying the temperatures of regions of interest for different excitations.

Some socio-economic aspects of the fishermen of twin pronged floodplain wetlands in West Bengal

A socio-economic investigation was carried out in two fishermen cooperative societies namely Purba Helatala Fishermen Co-operative Society (E-1), Barhal Fishermen Co-operative Society (E-2), under Maldah district, West Bengal to which the beels (flood plains) under study belong. A total of 132 member fishermen, which constituted the sample, were personally interviewed. The age group of the fishermen of the sample in E-1 varied between 20 and 66 years whereas in E-2 it was 22 and 61 years. All the members of the sample belonged to Scheduled Caste (SC) community. The primary occupation of all the respondents of both the beels was observed to be fishing (100%). Maximum number of illiterate respondents was observed to 56% in E-2 and 35% in E-1. It has been observed that as many as 38.3% of fishermen were having fishing experience which ranging from 16 to 20 years in E-1 whereas it was 6 - 10 years (36.1%) in E-2. Maximum number of fishermen lived in thatched houses (41.66%) in E-1 whereas in E-2 most of them lived in houses made of corrugated tin/tile shed (41.66%). As many as 41.55% of E-1 and 30.55% of E-2 used dug-out canoes for their fishing. Maximum number of fishermen used cast net with individualistic approach (100%) followed by Gill net (E-1:41.56% and E-2:55.55%). Most of the fishermen of the sample participated in fishing activities for 241 to 270 days (41.66%) in E-2 whereas it was 211 to 240 days (33.33 %) in E-1 in a year. During fishing season as many as 40.0% of the respondents of E-1 earned on an average Rs. 801.00 to Rs. 900.00 per month whereas it was Rs. 901.00 to Rs.1,000.00 (43.05%) in case of E-2. A section of fishermen of the sample borrowed money often (51.6%) E-1 whereas it was most often (27.27%) of E-2. The respondents of E-2 made regular repayment of the loan to the maximum extent (79.48%) whereas it was 57.44% in E-1. Higher fish production vis-a-vis higher income for the fishermen was observed in the beel (E2) having close characteristic.

Some aspects of the biology of Johnieops sina (Cuvier, 1830) from Mumbai waters

Investigations on food and feeding of Johnieops sina indicated that it feeds mainly on penaeid prawns, Acetes spp. and fishes. Penaeid prawns were found to be its preferred food item. The spawning activity was observed throughout the year with two peaks in February and August, supported by prominent peaks of gonadosomatic index in the same months. The minimum size at first maturity for females was 153 mm. The absolute fecundity ranged from 28,495 to 135,346 eggs for the ovaries weighing 1.30 to 9.49 g.

Structure of a fig wasp community: Temporal segregation of oviposition and larval diets

Observations were made on six fig wasp species on Ficus racemosa growing in the Xishuangbanna Tropical Botanic Garden, Yunnan Province, China. The oviposition sequence was determined for Apocryptophagus testacea, Apocrypta sp2, Apocryptophagus mayri, Cera

Temporal and Spatial Expression Patterns of Sox1 Gene in Xenopus laevis

克隆了非洲爪蟾的Sox1基因并研究了它在非洲爪蟾早期发育过程中的时空表达图式,比较了Sox1-3基因在发育的脑和眼中的表达图式.序列比对分析显示Sox1-3蛋白在其HMG框结构域具有高度的保守性.通过RT-PCR方法分析了Sox1基因在爪蟾早期不同发育时段的表达情况,结果显示Sox1基因从未受精卵到尾芽期均有表达,但表达强度有所差异.原位杂交结果显示,在早期卵裂阶段和囊胚期,Sox1基因主要在动物极表达;从神经板期开始,Sox1基因主要在中枢神经系统和眼原基中表达.在蝌蚪期,Sox1与Sox2、Sox3在脑部和眼睛的表达区域有所不同.对于爪蟾Sox1基因时空表达图式的研究将有助于阐明SoxB1基因家族在脊椎动物神经系统发生过程中的作用.

Technological aspects of preservation and processing of edible shell fish 2. Influence of season on the chemical composition of crab (Scylla serrata)

The purpose of this communication is to bring out the influence of season on the chemical composition of crab, covering a period of 2 years. Changes in moisture, protein, water extractable nitrogen, non-protein nitrogen, glycogen, lactic acid, fat and free amino acid composition of crab meat have been reported on a monthly basis.

Technological aspects of preservation and processing of edible shell fishes III. Factors influencing the keeping quality of crab (Scylla serrata) during freezing and frozen storage

The possible factors leading to the loss of flavour and general quality of crab during freezing and frozen storage have been studied. The preprocess ice storage condition of the raw material was found to be one such important factor while the fresh frozen crab meat remained in good organoleptic condition for about 51 weeks at -23°C, the 7 days iced material held frozen was found to have a shelf life of about 21 weeks. The fall in myofibrillar protein noted during frozen storage together with the loss of myosin ATPase activity correlated well with the loss of organoleptic qualities.