Seasonal abundance of brachyuran crab larvae in a tropical estuary: Gulf of Nicoya,Costa Rica,Central America

Brachyuran crab larvae were sampled approximately monthly at four stations in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Costa Rica, Central America. The gulf was divided into two regions based on physical and chemical characteristics. Larvae were identified to five families: Ocypodidae, Pinnotheridae, Portunidae, Majidae, Xanthidae. The abundance and distribution of these taxa were similar to that found in temperature estuaries of North America. Ocypodids, pinnixids, and xanthids were most common in the estuarine upper-gulf region while portunids were more common in the lower gulf. Majids were found in small numbers in the lower gulf. Only the ocypodids showed a consistent pattern in vertical distribution; larvae of this taxon were always more common in surface water. There was no consistent pattern in the seasonal abundance of the various taxa when compared among stations.     

DOWN HOLE FLOWMETER ANALYSIS USING AN ASSOCIATED CALIPER LOG

Abstract From flowmeter interpretation studies using wells with no available caliper data has emerged information which is also pertinent to flowmeter analysis in conjunction with a caliper log. A simple method for interpreting flowmeter and caliper log pairs incorporating this insight has been developed. Location of constant-flow regions, inflow and outflow zones is done by manually comparing the shapes of the caliper and flowmeter logs. A flowrate log is then produced using quantitative volumetric flowrates calculated for several depths in the well. The log contains all the significant flow information without spurious noise and would be suitable for converting to an apparent hydraulic conductivity log.     

Are Taxonomic Distinctness measures compliant to other ecological indicators in assessing ecological status?

Assessing the ecological status, a concept implemented in the European Water Framework Directive [EC, 2000. Directive of the European Parliament and of the Council 2000/60/EC establishing a framework for community action in the field of water policy PE-CONS 3639/1/00, p. 72], requires the application of methods capable of distinguishing different levels of ecological quality. The Average Taxonomic Distinctness has been used as tool in this context, and we tested the robustness of Taxonomic Distinctness measures applying it in different scenarios (estuarine eutrophication, organic pollution, and re-colonisation after physical disturbance), analysing simultaneously its compliance to other types of ecological indicators. Results show that, in most of the case studies, only Total Taxonomic Distinctness was relatively satisfactory in discriminating between disturbed situations. Other Taxonomic Distinctness measures have not proved to be more sensitive than other ecological indicators (Shannon-Wiener, Margalef, and Eco-Exergy indices). Therefore, this approach does not seem to be particularly helpful in assessing systems' ecological status with regard to the WFD implementation.     

New Calculation of the Electrical Microfield Distribution in Plasma

Recently new calculations for the probability field distribution in plasma generating a new expression for the Debye screening fields was carried out by Martin and Perez (1996). This field is a very accurate solution of the Poisson equation for a point test charge in a plasma described by a uniform charge density at Boltzmann thermal equilibrium. The method that we here present is based mainly on the introduction of this adequate field considering the dependence of the potential with the magnitude of the test charge in the calculus of the distribution. First we find the spectral function F(k) carrying out the Fourier transform of the field which is numerically calculated for each representative value of the variable in k space and then fitting these data in order to get F(k). Thus, after the usual numerical integration on the wave number space d³k, the field strength distribution is achieved. This approximation recovers the Holtsmark distribution in the limit of high temperature, and/or, small densities as also these where 0. As in previous works (Ecker, 1972; Spatschek, 1990) the most probable value of the field decreases as the temperature is reduced, and/or, the density increased.