Inorganic sulphate extraction from SO2-impacted Andosols

info:eu-repo/semantics/published

Stimulation of apolipoprotein D secretion by steroids coincides with inhibition of cell proliferation in human LNCaP prostate cancer cells

Although steroid hormones are known to play a predominant role in the regulation of cell growth in hormone-sensitive cancers, their mechanisms of action, especially their interaction with growth factors and/or growth inhibitors, is poorly understood. We have recently observed that the effects of androgens and estrogens on the expression of the major protein found in human breast gross cystic disease fluid, protein-24, are opposite to their respective action on cell proliferation in human breast cancer cell lines. Somewhat surprisingly, the recent elucidation of the amino acid sequence of this progesterone binding protein reveals that this tumor marker is apolipoprotein D (apo D), a member of a superfamily of lipophilic ligand carrier proteins. The present study was designed to determine whether apo D is secreted by human prostate cancer cells and could thus be a new marker of steroid action in these cancer cells, and whether the sex steroid-induced stimulation of apo D secretion coincides with inhibition of cell proliferation. We took advantage of the biphasic pattern of the effect of steroids on the proliferation of the human prostate cancer LNCaP cell line, which offers the opportunity to discriminate between positive and negative steroid receptor-regulated cell growth processes. A 10-day exposure to low concentrations of dihydrotestosterone and testosterone caused a potent stimulation of LNCaP cell proliferation, whereas incubation with higher concentrations of these androgens led to a progressive decrease in cell proliferation towards basal levels. The biphasic action of androgens was also observed on apo D secretion, the effects on apo D secretion being inversely related to their action on LNCaP cell proliferation. Similar opposite biphasic effects were also observed with 9 other steroids, thus indicating that the stimulation of secretion of this new biochemical marker coincides with inhibition of cell proliferation in LNCaP human prostatic cancer cells.

Transporte de microorganismos indicadores de contaminación fecal en una cuenca de la pampa ondulada : el rol de las propiedades físicas y químicas de los suelos y de los sedimentos

Dentro de las actividades agropecuarias, es la ganadería sobre pastizales una de las principales producciones que favorece la contaminación biológica de las aguas superficiales. Uno de los principales factores que afecta este proceso es la absorción bacteriana. Por ello se analizó la interrelación entre el suelo y los fenómenos absortivos en tres escalas de percepción en una cuenca agropecuaria de la pampa ondulada. En la escala de laboratorio se pudo demostrar el importante rol de las propiedades físicas y químicas de los suelos en la absorción y coeficiente de partición bacteriana. Entre estas se destacaron la CIC, contenido de arcillas y PSI como predictores de estos parámetros biolóbicos. Además, los suelos evaluados mostraron una alta heterogeneidad en la capacidad de absorción bacteriana (45 por ciento a 73,3 por ciento) lo cual permitió separar ambientes con capacidades de absorción diferentes, encontrándose en los Argiudoles una abserción significativamente mayor que en los Natracualfes. En esta misma escala fue probado la importancia del tamaño de agregados y la calidad del medio líquido circundante en la regulación de los procesos abserotivos. El tamaño de agregado clave en estos procesos fue el de 20 a 50 µm mientras que un medio líquido con alta fuerza iónica intensificaba estos procesos. A escala de parche, en parcelas inoculadas con E. coli bajo lluvia simulada, se corroboró la importancia de la absorción y coeficiente de partición en la retención bacteriana por parte del suelo y se comprobó el rol de las propiedades del suelo sobre estos parámetros a semejanza de lo encontrado en laboratorio. Por último a escala de cuenca se puso de manifiesto la incidencia de la absorción y Kd bacteriano en el transporte de contaminantes biolóbiocos a través del escurrido superficial. Esta escala permitió la consideración de parámetros claves en el transporte bacteriano como la supervicencia bacteriana, la temporalidad de ocurrencia de las lluvias así como su intensidad. Los resultados obtenidos a nivel de laboratorio, parche y cuenca constituyen un avance en el estudio de la dinámica de la contaminación biológica de los suelos y los cursos de agua en ambientes frágiles destinados a la producción animal

Monitoreo descriptivo de parásitos de origen fecal hallados en hortalizas de hojas

p.271-276

A coarse grid extraction of sound signals for computational aeroacoustics

Sound waves are propagating pressure fluctuations, which are typically several orders of magnitude smaller than the pressure variations in the flow field that account for flow acceleration. On the other hand, these fluctuations travel at the speed of sound in the medium, not as a transported fluid quantity. Due to the above two properties, the Reynolds averaged Navier–Stokes equations do not resolve the acoustic fluctuations. This paper discusses a defect correction method for this type of multi-scale problems in aeroacoustics. Numerical examples in one dimensional and two dimensional are used to illustrate the concept. Copyright (C) 2002 John Wiley & Sons, Ltd.

Numerical investigation of a source extraction technique based on an acoustic correction method

An aerodynamic sound source extraction from a general flow field is applied to a number of model problems and to a problem of engineering interest. The extraction technique is based on a variable decomposition, which results to an acoustic correction method, of each of the flow variables into a dominant flow component and a perturbation component. The dominant flow component is obtained with a general-purpose Computational Fluid Dynamics (CFD) code which uses a cell-centred finite volume method to solve the Reynolds-averaged Navier–Stokes equations. The perturbations are calculated from a set of acoustic perturbation equations with source terms extracted from unsteady CFD solutions at each time step via the use of a staggered dispersion-relation-preserving (DRP) finite-difference scheme. Numerical experiments include (1) propagation of a 1-D acoustic pulse without mean flow, (2) propagation of a 2-D acoustic pulse with/without mean flow, (3) reflection of an acoustic pulse from a flat plate with mean flow, and (4) flow-induced noise generated by the an unsteady laminar flow past a 2-D cavity. The computational results demonstrate the accuracy for model problems and illustrate the feasibility for more complex aeroacoustic problems of the source extraction technique.