Some aspects of the biology of Otolithes cuvieri (Trewavas) and Johnius glaucus (Day) from Veraval

The length-weight relationship in O. cuvieri and J. glaucus can be described by the equations log W=-5.27997+3.13225 log L and log W=-4.93431+3.02556 log L respectively. The length at first maturity in O. cuvieri is estimated as 256 mm and in J. glaucus as 180 mm. Empty stomachs occurred in high percentage in both the species. A study on composition of food items revealed that O. cuvieri feeds on a variety of organisms while J. glaucus a selective feeder.

DEVELOPMENT OF MULTI-ANCHOR EARTH RETENTION SYSTEMS.

This paper discusses two projects, the first relating to tests on 'reinforced earth' conducted on the 1. 5 m radius centrifuge at U. M. I. S. T. and the second concerning a short pilot study on the T. R. R. L concept of 'anchored earth' carried out on the 5 m radius Cambridge Geotechnical Centrifuge. The paper proposes a role for centrifugal model testing in design evaluation, whether by the designer himself, his centrification authority, a rival patent holder, or a research worker.

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.

Detour behavior changes associated with prenatal morphine exposure in 11-day-old chicks

The central nervous system exhibits remarkable plasticity in early life. Prenatal morphine exposure may induce adverse behavioral effects on the neonate and the developing offspring. In the present study, we investigated the effect of prenatal morphine exposure (daily from embryonic days 12-16, 20 mg/kg) on 11-day-old chicks using two forms of spatial paradigms: one trial detour behavior task in which animals must bypass an obstacle to reach the desired goal without any training and detour learning task which required several trials of training to reach the detour criterion. The results showed that, on the condition that chicks could successfully detour in the first trial, morphine exposed chicks exhibited longer detour latency to finish the task, coupled by a preference for turning right versus turning left. In contrast, no significant difference in learning and memory was found in detour learning task between morphine exposed chicks and saline chicks. These findings suggest specific behavioral changes associated with prenatal exposure to opioids during mid to late gestation, also raise attention to the possible health hazard from pregnancy drug use in everyday life. (C) 2010 ISDN. Published by Elsevier Ltd. All rights reserved.

Effects of Prenatal Exposure to a 50-Hz Magnetic Field on One-Trial Passive Avoidance Learning in 1-Day-Old Chicks

We investigated memory impairment in newly hatched chicks following in ovo exposure to a 50-Hz magnetic field (MF) of 2 mT (60 min/day) on embryonic days 12-18. Isolated and paired chicks were used to test the effect of stress during training, and memory retention was tested at 10, 30, and 120 min, following exposure to a bitter-tasting bead (100% methylanthranilate). Results showed that memory was intact at 10 min in both isolated and paired chicks with or without MF exposure. However, while isolated chicks had good memory retention levels at 30 and 120 min, those exposed to MF did not. The results suggest a potential disruption of memory formation following in ovo exposure to MF, with this effect only evident in the more stressed, isolated chicks. Bioelectromagnetics 31:150-155, 2010. (C) 2009 Wiley-Liss. Inc.

The socio-economic effects of trawling on the present day fishermen

1. The introduction of trawlers to Lake Victoria to harvest fish will have far reaching effects on the men (and women) presently engaged in the fishery, on the diet of the nation as a whole. 2. However, the whole concept of trawling is so different to present techniques and the scale of operation so great, that disruption to the socio-economy of many people is possible. 3. The sociological studies outlined below will assist the governments in the formulatlon of policies aimed at minimising disruptive effects on the lives of many individuals.

The present-day fishery of the Uganda waters of Lake Victoria

The Uganda waters of Lake Victoria comprise an area of 28,500 square kilometres with a shore line of 2,380 kilometres extending from the Uganda/Tanzania border in the west to the Uganda/Kenya border in the east. A large part of the Uganda waters of the lake is less than 60 metres deep, waters deeper than 60 metres being on the eastern side of the lake. Thus the Uganda part of the lake is tilted towards the east. A number of rivers drain into the lake from the north and the River Nile flows out of the lake towards the Mediterranean Sea. The Ssese, Kome, Buvuma and Busoga Islands form a very distinctive feature of the lake. These are perhaps the remaining high hills which survived the drowning of the northern valleys during the formation of the lake. In fact, in T. P. O'Brien's book 'The Prehistoric Uganda Protectorate (1939)', Solmon gives a critical summary of the work on the formation of Lake Victoria and shows that the northern part of the lake has numerous drowned valleys, a feature which provides varying habitats for particular species of fish and which may have an effect on the species composition reflected in the catches in different areas along the northern shore of the lake. It is interesting to note that although Lake Victoria as a whole has a number of rivers draining into it, Halbfass (1923) calculated and found that 76 per cent of the water entering the lake is precipitation on the lake surface.

Fiber laser processing of amorphous rare earth NeFeB magnetic materials

Since the exchange coupling theory was proposed by Kneller and Hawig in 1991 there has been a significant effort within the magnetic materials community to enhance the performance of rare earth magnets by utilising nano-composite meta-materials. Inclusions of magnetically soft iron smaller than approximately 10 nm in diameter are exchange coupled to a surrounding magnetically hard Nd2Fe14B matrix and provide an enhanced saturisation magnetisation without reducing coercivity. For such a fine nanostructure to be produced, close control over the thermal history of the material is needed. A processing route which provides this is laser annealing from an amorphous alloy precursor. In the current work, relationships between laser parameters, thermal histories of laser processed amorphous stoichiometric NdFeB ribbons and the magnetic properties of the resulting nanocrystalline products have been determined with a view to applying the process to thick film nanocomposite magnet production.

Dynamic earth pressures and earth pressure cell measurements

Failure of retaining walls is observed after many recent seismic events. Design of these walls are based on the pseudo-static force designs based on the Mononobe-Okabe earth pressure coefficient equations. However, it is clear that there are limitations attached with this approach. This paper investigates the seismic behaviour of sheet pile retaining walls using dynamic centrifuge testing facilities. In addition to using bending moment strain gauges on the wall, new generation earth pressure cells have also been used to investigate the generation of active and passive earth pressures. The results indicate that Mononobe-Okabe equations give relatively good estimates of active earth pressures but may be over-predicting passive earth pressures at certain peak ground acceleration levels. Based on this series of centrifuge tests it is concluded that earth pressure cells are successful in providing good qualitative data, but need to be supplemented by good calibration methods. © 2010 Taylor & Francis Group, London.

Measurement of 5-day biochemical oxygen demand without sample dilution or bacterial and nutrient enhancement

A direct method for measuring the 5-day biochemical oxygen demand (BODS) of aquaculture samples that does not require sample dilution or bacterial and nutrient enrichment was evaluated. The regression coefficient (R-2) between the direct method and the standard method for the analyses of 32 samples from catfish ponds was 0.996. The slope of the regression line did not differ from 1.0 or the Y-intercept from 0.0 at P = 0.05. Thus, there was almost perfect agreement between the two methods. The control limits (three standard deviations of the mean) for a standard solution containing 15 mg/L each of glutamic acid and glucose were 17.4 and 20.4 mg/L. The precision of the two methods, based on eight replicate analyses of four pond water samples did not differ at P = 0.05. (c) 2005 Elsevier B.V All rights reserved.