LONGITUDINAL DISPERSION IN SEDIMENT-LADEN OPEN CHANNEL FLOWS

Laboratory experiments on longitudinal dispersion in clear-water and sediment-laden open channel flows are reported. Data from these experiments and those available from previous studies indicate that the suspended sediment present in the flow affects the longitudinal dispersion process. The observed velocity distributions over the depth of sediment-laden flows indicate that the velocity deviates from the mean velocity more in sediment-laden flows than in clear-water flows. The velocity distributions over the cross section and secondary flow in the channel are also expected to be altereddue to the presence of suspended sediments in the flow. For these reasons, more dispersion is found in sediment-laden flows than in corresponding clear-water flows. A predictor for the dispersion coefficient in sediment-laden flows is proposed.     

Integrated geophysical and chemical study of saline water intrusion

Surface geophysical surveys provide an effective way to image the subsurface and the ground water zone without a large number of observation wells. DC resistivity sounding generally identifies the subsurface formations-the aquifer zone as well as the formations saturated with saline/brackish water. However, the method has serious ambiguities in distinguishing the geological formations of similar resistivities such as saline sand and saline clay, or water quality such as fresh or saline, in a low resistivity formation. In order to minimize the ambiguity and ascertain the efficacy of data integration techniques in ground water and saline contamination studies, a combined geophysical survey and periodic chemical analysis of ground water were carried out employing DC resistivity profiling, resistivity sounding, and shallow seismic refraction methods. By constraining resistivity interpretation with inputs from seismic refraction and chemical analysis, the data integration study proved to be a powerful method for identification of the subsurface formations, ground water zones, the subsurface saline/brackish water zones, and the probable mode and cause of saline water intrusion in an inland aquifer. A case study presented here illustrates these principles. Resistivity sounding alone had earlier failed to identify the different formations in the saline environment. Data integration and resistivity interpretation constrained by water quality analysis led to a new concept of minimum resistivity for ground water-bearing zones, which is the optimum value of resistivity of a subsurface formation in an area below which ground water contained in it is saline/brackish and unsuitable for drinking.     

Polycyclic aromatic hydrocarbons in commercial fish and lobsters from the coastal waters of Madagascar following an oil spill in August 2009

Concentrations of polycyclic aromatic hydrocarbons were determined in species of commercial fish and lobsters following an oil-spill just off the protected Madagascan coastline. Samples were collected along the coastline within and outside the affected area. Summed PAH concentrations ranged from 1.9 μg kg⁻¹ to 63 μg kg⁻¹ wet weight, but with no higher molecular weight PAHs (>202 Da) being detected. All concentrations of benzo[a]pyrene, benz[a]anthracene and dibenz[a,h]anthracene were <0.1 μg kg⁻¹ wet weight, well within the EU and UK set limits for the protection of human health. Additionally, samples were calculated as the benzo[a]pyrene toxic equivalency quotient (TEQ) and found to be well below the level of concern in relation to health of human consumers. Evaluation of the biota PAH data indicated the origin of PAH was predominantly petrogenic with >80% arising from oil sources. Profile studies indicate a low-level multisource petrogenic contamination probably representing a pre-spill background for the area.     

A cDNA microarray technique applied for analysis of global gene expression profiles in tributyltin-exposed ascidians

To analyze global gene expressions, we constructed a cDNA microarray from a basal chordate, the ascidian Ciona intestinalis. Ciona is a cosmopolitan species and a genomic analysis of Ciona revealed that ascidians had approximately 15,500 protein-coding genes. Our "Ciona intestinalis cDNA chip version 1 (Ci cDNA chip ver. 1)" has arrayed 13,400 unique Ciona cDNAs. To establish a detection system for gene expression profiles in wild ascidians using a cDNA microarray, we analyzed gene expressions in the whole body of Ciona adults after exposure to 100 nM tributyltin (TBT) for 24 h. In our preliminary array data using Ci cDNA chip ver. 1, we found more than 200 genes that showed strong differential expressions. These genes encoded proteins that were concerned with stress response, detoxification, oxidoreduction reaction, biosynthesis, and catabolism. This, the first large cDNA microarray of this animal, should facilitate analyses of global gene expressions following exposure to TBT.     

Morphological and molecular evidence supports the first occurrence of two fishes,Siganus sutor(Valenciennes, 1835)and Seriolina nigrofasciata(Rüppell, 1829)(Actinopterygii:Perciformes), from marine waters of Odisha coast,Bay of Bengal,India

Marine ecosystems provide a wide variety of diverse habitats that frequently promote migration and ecological adaptation. The extent to which the geographic distribution of marine organism has reshaped by human activities remains underappreciated. The limitations intrinsic to morphology-based identification systems have engendered an urgent need for reliable genetic methods that enable the unequivocal recognition of fish species,particularly those that are prone to overexploitation and/or market substitution. In the present study, however, an attempt has been taken to identify two locally adapted fish species, Siganus sutor(Valenciennes, 1835) and Seriolina nigrofasciata(Rüppell, 1829) of order Perciformes, which happens to be the first record in Odisha coast,Bay of Bengal. The diagnostic characteristics of Siganus sutor are: dorsal fin XIII-10, anal fin VII-9, pectoral fin 15,pelvic fin II-3, while that of Seriolina nigrofasciata dorsal fin VI-I-35, anal fin I-17, pectoral fin 16, pelvic fin 5. All COI barcodes generated in this study were matched with reference sequences of expected species, according to morphological identification. Bayesian and likelihood phylogenetic trees were drawn based on DNA barcodes and all the specimens clustered in agreement with their taxonomic classification at the species level. The phylogeographic studies based on haplotype network and migration rates suggest that both the species were not panmitic and the high-frequency population distribution indicates successful migration. The result of this study provides an important validation of the use of DNA barcode sequences for monitoring species diversity and changes within a complex marine ecosystem.     

An Experi mental Study on Wave-Induced Dynamic Stresses in Seabed

1 .IntroductionEvery year ,Taiwanis subjectedtotwo or three typhoonintrusions in average which always causedisasters . Most of the disasters which occur around the coastal zone are due to seabed instability andcoastal structure destruction caused bytyphoo…     

Simulation Study on High Energy Cosmic Electron Detection by Shower Image

Many projects have recently been carried out and proposed for observing high energy electrons since it is realized that cosmic ray electrons are very important when studying the dark matter particles and the acceleration mechanism of cosmic rays. An imaging calorimeter, BETS （Balloon-borne Electron Telescope with Scintillator fiber）, has been developed for this purpose. Using pattern analysis of the shower development, the electrons can be selected from those primary cosmic ray proton events with flux heights one-tenth that of the electrons. The Monte-Carlo simulation is indispensable for the instrument design, the signal trigger and the data analysis. We present different shower simulation codes and compare the simulation results with the beam test and the flight data of BETS. We conclude that the code FLUKA2002 gives the most consistent results with the experimental data.     

A Model for the Quiescent Phase of the Recurrent Nova U Scorpii

A theoretical light curve is constructed for the quiescent phase of the recurrent nova U Scorpii in order to resolve the existing distance discrepancy between the outbursts (d approximately 6 kpc) and the quiescences (d approximately 14 kpc). Our U Sco model consists of a very massive white dwarf (WD), an accretion disk (ACDK) with a flaring-up rim, and a lobe-filling, slightly evolved, main-sequence star (MS). The model properly includes an accretion luminosity of the WD, a viscous luminosity of the ACDK, and a reflection effect of the MS and the ACDK irradiated by the WD photosphere. The B light curve is well reproduced by a model of 1.37 M middle dot in circle WD + 1.5 M middle dot in circle MS (0.8-2.0 M middle dot in circle MS is acceptable) with an ACDK having a flaring-up rim and the inclination angle of the orbit i approximately 80&j0;. The calculated color is rather blue (B-V approximately 0.0) for a suggested mass accretion rate of 2.5x10-7 M middle dot in circle yr-1, thus indicating a large color excess of E(B-V) approximately 0.56 with the observational color of B-V=0.56 in quiescence. Such a large color excess corresponds to an absorption of AV approximately 1.8 and AB approximately 2.3, which reduces the distance to 6-8 kpc. This is in good agreement with the distance estimation of 4-6 kpc for the latest outburst. Such a large intrinsic absorption is very consistent with the recently detected period change of U Sco, which is indicating a mass outflow of approximately 3x10-7 M middle dot in circle yr-1 through the outer Lagrangian points in quiescence.     

The Properties of Supernova 1997cy Associated with GRB 970514

The extraordinary SN 1997cy associated with GRB 970514 has been observed photometrically and spectroscopically for nearly 2 yr. At the time of discovery, SN 1997cy was the brightest supernova (SN) ever observed (MV相似文献