Marine bacteria as indicators of upwelling in the Sea

The “oxidase reaction” (using p-amino-dimethyl-aniline oxalate as the reagent) has been used to distinguish oxidase-negative from oxidase-positive bacteria from the sea, when grown on membrane filters. By this means, it has been shown (a) that under conditions of stable stratification of the sea as in the tropics, a relationship exists between the percentage incidence of oxidase negative bacteria in the flora and the depth of the water; (b) that the maximum value for this percentage incidence (100) is reached at or immediately below the upper limit of the oxygen minimum layer; (c) that this percentage value (expressed as Oxⁿvalues) may be used to demonstrate the movements of water masses during upwelling. Such upwelling as indicated by theoretical findings and by temperature determinations along two transects off the west coast of Ceylon during the north east monsoon, has been confirmed by the distribution of Oxⁿvalues at these transects.

A Comparison of the bacterial flora of surface and sub-surface water of the sea off Ceylon

Under stable conditions of stratification of the sea, evidence of generic differences of the associated bacterial flora of the water masses has been obtained, between surface and sub-surface water. Gram negative rods, especially pseudomonads and achromobacters were more frequent at the surface. The fermentative and oxidase negative flora was more frequent in sub-surface water. The surface water in general had a greater variety of bacterial types while the sub-surface water had a flora with a greater range of biochemical activity. These results are discussed in relation to the hydrological condition of the water masses and the bacterial flora of freshly caught fish.

El estuario del Plata: donde el río se encuentra con el mar

The Rio de la Plata estuary is one of the largest estuarine environments of South America. It is characterized by a two-layer vertical salinity distribution and the existence of water masses convergence zones (fronts). Oceanographic scenario greatly influence the biology of the planktonic organisms that live in the water column, the benthic organisms that inhabit the soft sediment bottoms of the estuary, and the fishes, which show a differential degree of penetration into the diluted water of the estuary. Short and frequent events of strong weastward winds ('sudestada') alter completely the oceanographic conditions greatly influencing the especies ecology. Biological production of the estuary is high, and most of their organisms have a marine heritage.

Hydrology and fish distribution at the Sofala Bank (Mozambique)

A brief review is made of the hydrologic conditions at the Sofala Bank, mainly based on the research data obtained from 1978 to 1982. A description is attempted of the circulation pattern and the distribution of water masses in the area, four hydrologic regimes being identified. These are compared with the distributions of different pelagic and demersal fish species. A tendency is found for different groups of species to prefer different hydrologic regimes.

Tribological properties of mems materials measured on a small-scale device

Micro-electro-mechanical systems, MEMS, is a rapidly growing interdisciplinary technology within the general field of Micro-Systems Technology which deals with the design and manufacture of miniaturised machines with major dimensions at the scale of tens, to perhaps hundreds, of microns. Because they depend on the cube of a representative dimension, component masses and inertias rapidly become small as size decreases whereas surface and tribological effects, which often depend on area, become increasingly important. Although MEMS components and their areas of contact are small, tribological conditions, measured by contact pressures or acceptable wear rates, are demanding and technical and commercial success will require careful measurement and precise control of surface topography and properties. Fabrication of small numbers of MEMS devices designed to test potential material combinations can be prohibitively expensive and thus there is a need for small scale test facilities which mimic the contact conditions within a micro-machine without themselves requiring processing within a full semiconductor foundry. The talk will illustrate some initial experimental results from a small-scale experimental device which meets these requirements, examining in particular the performance of Diamond-Like-Carbon coatings on a silicon substrate. Copyright © 2005 by ASME.

Ground vibration generated by trains in underground tunnels

A popular method used to reduce vibration transmitted from underground railways into nearby buildings is floating-slab track, whereby a concrete slab supporting the two rails is mounted on rubber bearings or steel springs to isolate it from the tunnel invert. This paper adds a track model to a previously developed three-dimensional tunnel model in order to assess the effectiveness of floating-slab track. A slab beam coupled to the tunnel in the wavenumber domain, with the slab bearings represented by an elastic layer, is examined first. A second beam representing the two rails together is then coupled to the slab, and axle masses representing a train are added to the rail beam. Power-spectral densities and RMS levels of soil vibration due to random roughness-displacement excitation between the masses and the rail beam are calculated. Analytical techniques are used to minimise the computational requirements of the model. The results demonstrate the inadequacy of simple mass-spring and Winkler-beam models with rigid foundations for the assessment of the vibration-isolation performance of railway track. They suggest that the achievable insertion loss is modest and that floating the track slab may in fact cause increased transmission of vibration under certain conditions. © 2006 Elsevier Ltd. All rights reserved.

Salinity measurements and use of the Practical Salinity Scale (PSS)

Salinity, temperature and pressure are parameters which govern the oceanographic state of a marine water body and together they make up density of seawater. In this contribution we will focus our interest on one of these parameters, the salinity: accuracy in relation to different purposes as well as observation technique and instrumentation. We will also discuss the definition of salinity. For example most of the Indian Ocean waters are within the salinity range from 34.60-34.80, which emphasize the importance of careful observations and clear definitions of salinity, in such a way that it is possible to define water masses and predict their movements. In coastal waters the salinity usually features much larger variation in time and space and thus less accuracy is sometimes needed. Salinity has been measured and defined in several ways over the past century. While early measurements were based on the amount of salt in a sea water sample, today the salinity of seawater is most often determined from its conductivity. As conductivity is a function of salinity and temperature, determination involves also measurement of the density of seawater is now more precisely estimated and thus the temperature. As a result of this method the Practical Salinity Scale (PSS) was developed. The best determination of salinity from conductivity and the temperature measurements gives salinity with resolution of 0.001 psu, while the accuracy of titration method was about ± 0.02‰. Because of that, even calculation of movements in the ocean is also improved.

Occurrence of whale sharks in coastal waters in the Indian Ocean: an interesting coincidence

Salinity, temperature and pressure are parameters which govern the oceanographic state of a marine water body and together they make up density of seawater. In this contribution we will focus our interest on one of these parameters, the salinity: accuracy in relation to different purposes as well as observation technique and instrumentation. We will also discuss the definition of salinity. For example most of the Indian Ocean waters are within the salinity range from 34.60-34.80, which emphasize the importance of careful observations and clear definitions of salinity, in such a way that it is possible to define water masses and predict their movements. In coastal waters the salinity usually features much larger variation in time and space and thus less accuracy is sometimes needed. Salinity has been measured and defined in several ways over the past century. While early measurements were based on the amount of salt in a sea water sample, today the salinity of seawater is most often determined from its conductivity. As conductivity is a function of salinity and temperature, determination involves also measurement of the density of seawater is now more precisely estimated and thus the temperature. As a result of this method the Practical Salinity Scale (PSS) was developed. The best determination of salinity from conductivity and the temperature measurements gives salinity with resolution of 0.001 psu, while the accuracy of titration method was about ± 0.02‰. Because of that, even calculation of movements in the ocean is also improved.

Stejnulxin, a novel snake C-type lectin-like protein from Trimeresurus stejnegeri venom is a potent platelet agonist acting specifically via GPVl

Stejnulxin, a novel snake C-type lectin-like protein with potent platelet activating activity, was purified and characterized from Trimeresurus stejnegeri venom. Under non-reducing conditions, it migrated on a SDS-polyacrylamide gel with an apparent molecular mass of 120 kDa. On reduction, it separated into three polypeptide subunits with apparent molecular masses of 16 kDa (alpha), 20 kDa (beta(1)) and 22 kDa (beta(2)), respectively. The complete amino acid sequences of its subunits were deduced from cloned cDNAs. The N-terminal sequencing and cDNA cloning indicated that beta(1) and beta(2) subunits of stejnulxin have identical amino acid sequences and each contains two N-glycosylation sites. Accordingly, the molecular mass difference between 1 and 2 is caused by glycosylation heterogenity. The subunit amino acid sequences of stejnulxin are similar to those of convulxin, with sequence identities of 52.6% and 66.4% for the U. and beta, respectively. Stejnulxin induced human platelet aggregation in a dose-dependent manner. Antibodies against UNA inhibited the aggregation response to stejnulxin, indicating that activation of alpha(IIb)beta(3) and binding of fibrinogen are involved in stejnulxin-induced platelet aggregation. Antibodies against GPIbalpha or alpha(2)beta(1) as well as echicetin or rhodocetin had no significant effect on stejnulxin-induced platelet aggregation. However, platelet activation induced by stejnulxin was blocked by anti-GPVI antibodies. In addition, stejnulxin induced a tyrosine phosphorylation profile in platelets that resembled that produced by convulxin. Biotinylated stejnulxin bound specifically to platelet membrane GPVI.

Shock transmission and eigenvalue veering within a coupled system.

The operation of dynamical systems in harsh environments requires continuous monitoring. Internal sensors may be used to monitor the conditions in real time. A typical example is the sensor and electronic components used in space structures which, especially during launch, are subject to huge g force. The paper will present an experimental and theoretical study on a simplified model used to analyze the possible cause of high acceleration on the enclosed sensors and equipments due to impulsive loading. The model system consists of two beams coupled using compliant connections. An impulse hammer excites one beam, and vibrations are transmitted to the indirectly driven beam. A theoretical model is developed using a Rayleigh-Ritz approach and validated using experimental results in both the frequency and time domains. Monto Carlo simulation was done with random masses positioned on the indirectly driven beam to determine the worst-case conditions for maximum peak acceleration. Highest acceleration levels were found when mode matching in the two beams led to veering behavior in the coupled modes. The results suggest guidelines for the detailed design of internal components of a structure exposed to shock loading from its environment. [The authors thank Schlumberger Cambridge Research for financial support.].

On the fishing power of monofilament and multifilament gill nets

The authors have discussed the results of comparative fishing, conducted in the Govindsagar reservoir, with simple monofilament and multifilament gill nets. The experiments were conducted both in clear and turbid water. In both these water masses, the monofilament gill net has been found to be more efficient. It is also found that the four major species of fishes of the reservoir have not shown any preference towards a specific gear.

Arabian Sea sub-surface salinity minima (ASSM)

This paper presents the results of the study on the Arabian Sea sub-surface salinity minima (ASSM). The data collected under the North Arabian Sea Environment and Ecosystem Research (NASEER) programme and World Ocean Circulation Experiment (WOCE) has been used in the study. Study of the Arabian Sea water masses is most significant in understanding marine productivity and monsoonal reversal features. Analysis of the data shows that the Arabian Sea sub-surface salinity minima (ASSM) can be found between 25.8 to 26.0 Sigma Theta surfaces. ASSM originates from the south and south east. It is inferred from the results that the salt content of the ASSM varies during different seasons. Appreciable mixing of Arabian Sea salinity minima is observed over Murray Ridge.

Spreading of Persian Gulf water in the northwestern Arabian sea during the month of January

The presence of different water masses in the North Arabian Sea continues to remain of interest to scientists and researchers. Focus on these water masses is due to the unique monsoonal reversal features of the Arabian Sea. The encroachment of Persian Gulf water into the Arabian Sea has been acknowledged and traced. This paper presents the results of an investigation on the spreading patterns of Persian Gulf water in the northwestern Arabian Sea. The study incorporated two different techniques: the core-layer method and the constant sigma-theta surface method on data collected during the North Arabian Sea Environment and Ecosystem Research (NASEER) programme. Horizontal curves of temperature and salinity plotted by both methods show that the Persian Gulf water reduces in concentration as it moves from west to east, whereas the major direction of flow is along the coast of Oman. The results of the study indicate that features of the Persian Gulf water in the northwestern Arabian Sea are so pronounced that either of the method can be used to study and identify the water mass fairly well.

兔抗人外周血单核细胞、兔抗猴脾脏淋巴细胞免疫血清的制备及其在分离人和猕猴胚胎内细胞团中的应用

采用梯度离心的方法用淋巴细胞分离液从浓缩的人白细胞悬液中分离人外周血单核细胞，从猕猴新 鲜脾脏中研磨分离猕猴脾脏淋巴细胞；分别将人外周血单核细胞和猕猴脾脏淋巴细胞作为免疫原，每次通过耳 缘静脉注射4×10s个细胞免疫日本大耳白兔，每周免疫一次，共免疫3次，制备兔抗人外周血单核细胞和兔抗 猕猴脾脏淋巴细胞免疫血清。体外培养人和猕猴胚胎至囊胚，采用制备的免疫血清，分离人和猕猴囊胚内细胞 团，用于建立人和猕猴胚胎干细胞系。结果如下：(1)用半微量细胞毒实验法测得兔抗人外周血单核细胞免疫 血清和兔抗猕猴脾脏淋巴细胞免疫血清的效价分别为1：320和1：640；(2)两种免疫血清成功地裂解了15个人 囊胚和33个猕猴囊胚的滋养层细胞，分离出了内细胞团，表明免疫血清的制备取得了成功，为建立人和猕猴 胚胎干细胞系奠定了基础。

The nuclear matrix of Euglena gracilis (Euglenophyta): A stage of nuclear matrix evolution?

Euglena gracilis cell was extracted sequentially with CSK-Triton buffer, RSB-Magik solution and DNase-As solution. DGD embedment-free electron microscopy showed that in the extracted nucleus there was a residual non-chromatin fibrous network. That it could not be removed by hot trichloroacetic acid further supported the idea that it was a non-histone, non-chromatin fibrous protein network, and should be the internal network of the nuclear matrix. After the sequential extraction, the nuclear membrane was removed, leaving behind a layer of lamina; the chromatin was digested and eluted from the dense chromosomes and residual chromosomal structures that should be chromosomal scaffold were revealed. Western blot analysis with antiserum against rat lamins showed that nuclear lamina of the cell possessed two positive polypeptides, a major one and a minor one, which had molecular masses similar to lamin B and lamin A, respectively. Comparing these data with those of the most primitive eukaryote Archezoa and of higher eukaryotes, it was suggested that the lower unicellular eukaryote E. gracillis already had the nuclear matrix structure, and its nuclear matrix (especially the lamina) might represent a stage of evolutionary history of the nuclear matrix. (C) 2000 Editions scientifiques et medicales Elsevier SAS.