107 research outputs found
Dynamical evolution of rotating dense stellar systems with embedded black holes
Evolution of self-gravitating rotating dense stellar systems (e.g. globular
clusters, galactic nuclei) with embedded black holes is investigated. The
interaction between the black hole and stellar component in differential
rotating flattened systems is followed. The interplay between velocity
diffusion due to relaxation and black hole star accretion is investigated
together with cluster rotation using 2D+1 Fokker-Planck numerical methods. The
models can reproduce the Bahcall-Wolf solution () inside the zone of influence of the black hole. Gravo-gyro and
gravothermal instabilities conduce the system to a faster evolution leading to
shorter collapse times with respect to the non-rotating systems. Angular
momentum transport and star accretion support the development of central
rotation in relaxation time scales. We explore system dissolution due to
mass-loss in the presence of an external tidal field (e.g. globular clusters in
galaxies).Comment: 16 pages, 23 figures, 6 table
2D Fokker-Planck models of rotating clusters
Globular clusters rotate significantly, and with the increasing amount of
detailed morphologicaland kinematical data obtained in recent years on galactic
globular clusters many interesting features show up. We show how our
theoretical evolutionary models of rotating clusters can be used to obtain
fits, which at least properly model the overall rotation and its implied
kinematics in full 2D detail (dispersions, rotation velocities). Our simplified
equal mass axisymmetric rotatingmodel provides detailed two-dimensional
kinematical and morphological data for star clusters. The degree of rotation is
not dominant in energy, but also non-negligible for the phase space
distribution function, shape and kinematics of clusters. Therefore the models
are well applicable for galactic globular clusters. Since previously published
papers on that matter by us made it difficult to do detailed comparisons with
observations we provide a much more comprehensive and easy-to-use set of data
here, which uses as entries dynamical age and flattening of observed cluster
andthen offers a limited range of applicable models in full detail. The method,
data structure and some exemplary comparison with observations are presented.
Future work will improve modelling anddata base to take a central black hole, a
mass spectrum and stellar evolution into account
Cost-effectiveness analysis of pneumococcal conjugate vaccines in preventing pneumonia in Peruvian children
Pneumococcal pneumonia (PP) has a high burden of morbimortality in children. Use of pneumococcal conjugate vaccines (PCVs) is an effective preventive measure. After PCV 7-valent (PCV7) withdrawal, PCV 10-valent (PCV10) and PCV 13-valent (PCV13) are the alternatives in Peru. This study aimed to evaluate cost effectiveness of these vaccines in preventing PP in Peruvian children <5 years-old
Kinetics of the anaerobic purification of aerobically prebiotreated olive mill wastewater
Se ha efectuado un estudio cinético del proceso de depuración
anaerobia de un alpechín previamente tratado vía aerobia
con objeto de eliminar la mayor parte de los compuestos
fenólicos responsables de su poder inhibidor.
Se utilizan dos reactores anaerobios, uno con soporte Pansil
y un Testigo sin relleno, para estudiar la influencia del soporte
de inmovilización tanto sobre las constantes biocinéticas como
sobre la eficiencia del proceso de digestión anaerobia o biometanización
de este alpechín pretratado.
A diferencia de lo que ocurre con el alpechín natural, se
observa sólo una pequeñísima disminución de las constantes
aparentes de velocidad del proceso anaerobio al aumentar la
densidad de carga. Por otra parte, no se aprecian fenómenos
de inhibición en el proceso de biometanización de este agua
residual previamente tratada de forma aerobiaA kinetic study has been carried out on the process of
anaerobic purification of an olive mill wastewater pre-treated
aerobically to eliminate the greater part of the phenolic compounds
responsible for inhibition.
Two anaerobic digesters were used, one with Pansil support,
and the other a Reference without filling. The aim was to study
the influence of the immobilization support both on the biokinetic
constants and on the efficiency of the anaerobic digestion process
or biomethanization of this pre-treated olive mill wastewater. In contrast to what takes place with natural olive mill
wastewater, only a very small decrease in the apparent rate
constants of the anaerobic process was observed on increasing
load density. At the same time, no inhibition was found in the
biomethanization of this aerobically pre-treated wastewate
Biodegradation of phenolic compounds present in oil-mill wastewater
Las aguas residuales de la obtención del aceite de oliva
o alpechines son responsables de la mayor contaminación
medioambiental de Andalucía por su elevada carga de materia
orgánica. Su depuración por biometanización es difícil debido
a la actividad antimicrobiana de los compuestos fenólícos. Este
tipo de sustancias puede eliminarse en gran parte tratando
previamente el alpechín por vía aerobia con microorganismos
específicos, después de lo cual la depuración anaerobia tiene
lugar sin inhibiciones, siendo la constante de velocidad cinco
veces superior a la de antes del pretratamiento.
En este trabajo se hace un estudio cualitativo de los fenoles
por cromatografía en capa fina y cuantitativo de los fenoles
totales, orto- y meta-difenoles, así como de la Demanda Química
de Oxígeno del alpechín antes del tratamiento, después
del pretratamiento y después de la biometanización.
Se ha comprobado también la ausencia de leucoantocianinas
que pudieran dar origen a fenoles polimerizadosOil-mill wastewater is the main responsible of the pollution
in Andalusian due to high content of organic substances. Its
depuration by methanization is difficult because of the antimicrobial
activity of phenolic derivatives. These compounds can be
drastically reduced by a previous aerobic treatment of the oilmill
wastewater with specific microorganisms. After this pretreatment,
anaerobic depuration takes place without inhibition, the
velocity of the reaction being 5 times higher than before the pretreatment.
In this paper a qualitative study of the phenols present in
oil-mill wastewater by thin layer chromatography has been done.
Beside that, quantitative determination of total phenols, ortoand
meta-diphenols as well as Chemical Oxigen Demand (COD) before the treatment, after the pretreatment and after biomethanization
have been carried out.
Finally, leucoanthocyanins that could originate polymerized
phenols have not been foun
Epidemiological and transmissibility analysis of influenza A(H1N1)v in a southern hemisphere setting: Peru
We present a preliminary analysis of 1,771 confirmed cases of influenza A(H1N1)v reported in Peru by 17 July including the frequency of the clinical characteristics, the spatial and age distribution of the cases and the estimate of the transmission potential. Age-specific frequency of cases was highest among school age children and young adults, with the lowest frequency of cases among seniors, a pattern that is consistent with reports from other countries. Estimates of the reproduction number lie in the range of 1.2 to 1.7, which is broadly consistent with previous estimates for this pandemic in other regions. Validation of these estimates will be possible as additional data become available
Utilización y tratamiento del alpechín: situación actual y perspectivas en España
The characteristics of olive mill wastewater are set out the viewpoint of their pollutant capacity and the problems arising from their tipping in olive-growing areas. The national administration's solutions for preventing pollutions of surface waters are also stated.
Special detail is given to the action taken within a research and development program financed by the Spanish Government and the EEC through the Commission MEDSPA 89 for the technical-economic evaluation of different systems for eliminating and treating olive mill wastewater, in order to determine the feasibility of their introduction at industrial level.
At the same time the systems currently under evaluation are described:
- Intensification of natural evaporation from olive mill wastewater stored in ponds (two systems).
- Physical processes using forced evaporation to eliminate the olive mill wastewater, followed by aerobic biological processes or systems of ultrafiltration and inverse osmosis for final treatment of the condensate (two systems).
- Application of physico-chemical processes to eliminate the greater part of the organic components of the olive mill wastewaters and the use of aerobic biological processes or systems of ultrafiltration and inverse osmosis for final treatment of the clarified fraction (three systems).
- Biological process for the complete treatment of the olive mill wastewaters by the successive application of processes: bioconversion, biomethanisation, aerobic treatment, and physico-chemical treatment. Treatment yields of the order of 99,6% are achieved, at the same time obtaining by-products of commercial interest (one system).Las características de los alpechines se establecen desde el punto de vista de su capacidad contaminante y de los problemas típicos que surgen en las zonas de cultivo del olivo. También están descritas las soluciones de la administración del Estado para la prevención de la contaminación de aguas de superficie.
Se detallan especialmente los puntos de acción incluidos dentro de un programa de Investigación y Desarrollo financiado por el Gobierno Español y la CEE a través de la comisión MEDSPA 89, para la evaluación técnica y económica de diferentes sistemas de eliminación y tratamiento de alpechines, con el fin de determinar la conveniencia de su introducción a nivel industrial.
Al mismo tiempo se describen los sistemas actuales sometidos a evaluación:
- Intensificación de la evaporación natural de alpechines almacenados en balsas.
- Procesos físicos de evaporación forzada para eliminar este agua residual, seguido de procesos biológicos aerobios o sistemas de ultrafiltración y osmosis inversa para el tratamiento final de los condensados (dos sistemas).
- Aplicación de procesos físico-químicos para eliminar la mayor parte de la materia orgánica del alpechín, y uso de procesos biológicos aerobios o sistemas de ultrafiltración y osmosis inversa para el tratamiento final de la fracción clarificada (tres sistemas).
- Proceso biológico para la depuración integral del alpechín mediante la aplicación sucesiva de los procesos: bioconversión, biometanización, tratamiento aerobio, y tratamiento físico-químico. Se consiguieron rendimientos del orden del 99,6%, con la obtención simultánea de subproductos de interés comercial (un sistema)
N-body Models of Rotating Globular Clusters
We have studied the dynamical evolution of rotating globular clusters with
direct -body models. Our initial models are rotating King models; we
obtained results for both equal-mass systems and systems composed out of two
mass components. Previous investigations using a Fokker-Planck solver have
revealed that rotation has a noticeable influence on stellar systems like
globular clusters, which evolve by two-body relaxation. In particular, it
accelerates their dynamical evolution through the gravogyro instability. We
have validated the occurence of the gravogyro instability with direct -body
models. In the case of systems composed out of two mass components, mass
segregation takes place, which competes with the rotation in the acceleration
of the core collapse. The "accelerating" effect of rotation has not been
detected in our isolated two-mass -body models. Last, but not least, we have
looked at rotating -body models in a tidal field within the tidal
approximation. It turns out that rotation increases the escape rate
significantly. A difference between retrograde and prograde rotating star
clusters occurs with respect to the orbit of the star cluster around the
Galaxy, which is due to the presence of a ``third integral'' and chaotic
scattering, respectively.Comment: 16 pages, 17 figures, accepted by MNRA
Influencia de la concentración de sustrato sobre la cinética del proceso de biometanización del alpechín, en biorreactores de lecho fluidizado con microorganismos inmovilizados
A kinetic study has been made of the anaerobic olive mill wastewater fermentation process in fluid bed bioreactors containing clay supports in suspension, on which the microorganisms responsible for the process have been immobilized.
Four concentrations of wastewater have been used (10%, 20%, 40% and 80%) to study the influence of the substrate concentration, and at the same time, of the immobilization support, on the biokinetic constants of the continuous process.
The Chen-Hashimoto model of methane production has been applied, obtaining the values of the kinetic parameters μmax and K for each case studied.
The values of these parameters decreased considerably with increasing concentration of influent wastewater, though this decrease varied depending on the support used.Se ha efectuado un estudio cinético del proceso de fermentación anaerobia del alpechín en biorreactores de lecho fluidizado que contienen en suspensión soportes de tipo arcilloso sobre los que se han inmovilizado los microorganismos responsables del proceso.
Se utilizan cuatro concentraciones de alpechín (10%, 20%, 40% y 80%) para estudiar la influencia de la concentración de sustrato sobre las constantes biocinéticas del proceso en régimen continuo, estudiándose al mismo tiempo la influencia del soporte de inmovilización sobre las mismas.
Para ello, se aplica el modelo de Chen-Hashimoto de producción de metano, obteniéndose los valores de los parámetros cinéticos μmax y K, para cada uno de los casos estudiados.
Se obtiene una disminución considerable de los valores de estos parámetros al aumentar la concentración de alpechín utilizada como influente, si bien este descenso de las constantes cinéticas varia según el soporte considerado
Influencia de la concentración de sustrato sobre la cinética del proceso de biometanización del alpechín, en biorreactores de lecho fluidizado con microorganismos inmovilizados
A kinetic study has been made of the anaerobic olive mill wastewater fermentation process in fluid bed bioreactors containing clay supports in suspension, on which the microorganisms responsible for the process have been immobilized. Four concentrations of wastewater have been used (10%, 20%, 40% and 80%) to study the influence of the substrate concentration, and at the same time, of the immobilization support, on the biokinetic constants of the continuous process. The Chen-Hashimoto model of methane production has been applied, obtaining the values of the kinetic parameters μ<sub>max</sub> and K for each case studied. The values of these parameters decreased considerably with increasing concentration of influent wastewater, though this decrease varied depending on the support used.<br><br>Se ha efectuado un estudio cinético del proceso de fermentación anaerobia del alpechín en biorreactores de lecho fluidizado que contienen en suspensión soportes de tipo arcilloso sobre los que se han inmovilizado los microorganismos responsables del proceso. Se utilizan cuatro concentraciones de alpechín (10%, 20%, 40% y 80%) para estudiar la influencia de la concentración de sustrato sobre las constantes biocinéticas del proceso en régimen continuo, estudiándose al mismo tiempo la influencia del soporte de inmovilización sobre las mismas. Para ello, se aplica el modelo de Chen-Hashimoto de producción de metano, obteniéndose los valores de los parámetros cinéticos μ<sub>max</sub> y K, para cada uno de los casos estudiados. Se obtiene una disminución considerable de los valores de estos parámetros al aumentar la concentración de alpechín utilizada como influente, si bien este descenso de las constantes cinéticas varia según el soporte considerado
- …