La Geografía a las puertas del tercer milenio a partir de las tesis doctorales leídas en los noventa

Tendencies of research in contemporary Geography were analysed by means of the latest PhD studies in Geography in Spanish Universities. Our analysis shows that research is still focused on local and regional environments with different techniques and methods. There is still need to actualise the descriptors of PhD studies classification.Se han analizado las tendencias de la investigación en la Geografía actual a través de las tesis doctorales de Geografía en los últimos años en las Universidades españolas. El análisis muestra que continua la tendencia a investigar sobre ámbitos locales y regionales con una gran pluralidad de técnicas. Se ha detectado también que existe una necesidad de actualizar los descriptores de clasificación de las tesis doctorales de la base de datos TESEO.Les tendences des ênquetes dans la géographie ont etés analysés a travers les théses doctorales dans les dernieres années dans les Universités Espagnoles. L´analise montre que la téndence continue a ênqueter sur les cadres locaux et regionaux avec une grande pluralité de techniques. Il a eté detecté aussi qu´il existe un besoin de metre a jour les déchifreurs de triage des théses doctorales sur les données TESEO

Spatial and temporal variability of CO2 emisions in soils under conventional tillage and no-till farming

Agricultural soils can act as a carbon sink depending on the soil management practices employed. As a result of this functional duality, soil management systems are present in international documents relating to climate change mitigation. Agricultural practices are responsible for 14% of total greenhouse gas emissions (GHG’s) (MMA, 2009)(1). Conservation agriculture (CA) is one of the most effective agricultural systems for reducing CO2 emissions, as it increases the sequestration of atmospheric carbon in the soil. In order to assess the performance of CA in terms of CO2 emissions, a field trial was conducted comparing soil derived CO2 fluxes under No-till (NT) farming and under conventional tillage. Three pilot farms were selected in the cereal-growing area of southern Spain, located in Las Cabezas de San Juan (Seville), Carmona (Seville) and Cordoba. Each pilot farm comprises six experimental plots with an approximate area of five hectares; three of the six plots implement CA practices, while the other three use conventional tillage techniques. The subdivision of each tillage system into 3 plots allowed the simultaneous cropping of the three crops of the wheat-sunflower-legume rotation each year. Results showed that carbon dioxide emissions were 31 to 91% higher in tilled soils than in untilled soils, and that there was a great seasonal variability of CO2 emissions, as weather conditions also differed considerably for the different sampling periods. In all cases, the CO2 fluxes emitted into the atmosphere were always higher when soil was subject to conventional tillage

Qué papel juega el hongo Phytophthora cinnamomi en el desarrollo de la regeneración natural y repoblaciones de encina y alcornoque

Se presentan los resultados resumidos de tres trabajos realizados para conocer el papel que juega el hongo Phytophthora cinnamomi en el desarrollo de plántulas de encina (Quercus ilex) y alcornoque (Quercus suber). Se realizaron dos prospecciones para detectar la presencia de P.cinnamomi en focos de seca en dehesas de encina y alcornoque de Extremadura en 1991-1992 y 1999-2000. El porcentaje de focos en los que se detectó la presencia de P. cinnamomi ha permanecido relativamente estable entre las dos prospecciones. También se determinó la tasa de crecimiento relativo para nueve aislados de P. cinnamomi a diferentes temperaturas, observando una elevada variabilidad tanto en la temperatura óptima de crecimiento como en el valor de la propia tasa diaria de crecimiento máxima. También se estudió la emergencia y supervivencia de plántulas de encina y alcornoque procedentes de dos dehesas ecológicamente diferentes, cultivadas en condiciones controladas en suelos de estas dehesas infectados naturalmente con P. cinnamomi y en estos mismos suelos previamente desinfectados en autoclave. Un factor limitante en los procesos de regeneración natural y en las repoblaciones por siembra directa de encinas y alcornoque puede ser su alta susceptibilidad a las infecciones por P. cinnamomi.Por último, se estudió durante dos años consecutivos, la supervivencia de las plantas de encina de una repoblación sobre un suelo naturalmente infectado con P. cinnamomi en la provincia de Badajoz (SO de España). Los resultados obtenidos se discuten teniendo en cuenta el déficit hídrico, los daños por P. cinnamomi, la competencia con otras especies y las posibles medidas sanitarias que amortigüen los daños en las repoblaciones con encinas._______________________________Three different studies were performed with the aim to determine the role of Phytophthora cinnamomi in the early development of seedlings of holm oak (Quercus ilex) and cork oak (Quercus suber). Two surveys, for the presence of Phytophthora cinnamomi in declining holm oak and cork oak stands in Extremadura (SW Spain) were performed in 1991-1992 and 1999-2000. The percentage of decline foci where P. cinnamomi is envolved has remained relatively stable in the lapse of time between the two surveys. Growth rates were determined for 9 P. cinnamomi isolates. Considerable variation in optimum growth temperatures and in daily growth rates occurred among isolates. The emergence and survival of pregerminated holm oak and cork oak acorns from two ecologically different dehesas (Mediterranean open woodlands) were studied in two soils from these stands naturally infected with P. cinnamomi, and in the same soils previously sterilized in the autoclave. The demonstrated high susceptibility of holm and cork oak young seedlings to P. cinnamomi could be a limiting factor in mediterranean opend woodlands (dehesas) not only in natural regenerationprocesses but also when reforestation by direct sowing is implemented. Finally, the viability of 1 year old holm oak seedlings in a soil naturally infected with P. cinnamomi was studied during two consecutive years in a plot located in SW Spain. Results obtained are discussed in the framework of seasonal water deficit, P. cinnamomi damage, weed competition and sanitation thechniques to be used in declined holm oak stands in Spain

Super star clusters and Supernovae in interacting LIRGs unmasked by NIR adaptive optics

We report on an on-going near-IR adaptive optics survey targeting interacting luminous IR galaxies. High-spatial resolution NIR data are crucial to enable interpretation of kinematic, dynamical and star formation (SF) properties of these very dusty objects. Whole progenitor nuclei in the interactions can be missed if only optical HST imaging is used. Here we specifically present the latest results regarding core-collapse supernovae found within the highly extincted nuclear regions of these galaxies. Direct detection and study of such highly obscured CCSNe is crucial for revising the optically-derived SN rates used for providing an independent measurement of the SF history of the Universe. We also present thus-far the first NIR luminosity functions of super star cluster (SSC) candidates. The LFs can then be used to constrain the formation and evolution of SSCs via constraints based on initial mass functions and cluster disruption models.Comment: 6 pages. To appear in proceedings of 'Galaxies and their Masks' (Namibia, April 2010), published by Springer, New York, eds. D.L. Block, K.C. Freeman, I. Puerar

Histological findings in two renal transplants accomplishing operational tolerance criteria

Operational tolerance is defined as stable renal function in transplants without immunosuppression for at least 1 year. We present histological assessments of two patients with operational tolerance. The first withdrew immunosuppression in 2005 and presents stable renal function (creatinine 1.5 mg/dL) without proteinuria. The biopsy showed mild chronic tubulointerstitial changes without inflammation. The second withdrew immunosuppression in 2009 and maintains stable renal function (creatinine 1.6 mg/dL) with mild proteinuria. Histology showed chronic humoural rejection and Class II anti-human leukocyte antigen antibodies were detected. These cases suggest that a renal biopsy may be useful to rule out subclinical pathology in patients with operational tolerance

Equation of state for hot dense matter using a relativistic screened hydrogenic model

The study of matter under conditions of high density, pressure, and temperature is a valuable subject for inertial confinement fusion (ICF), astrophysical phenomena, high-power laser interaction with matter, etc. In all these cases, matter is heated and compressed by strong shocks to high pressures and temperatures, becomes partially or completely ionized via thermal or pressure ionization, and is in the form of dense plasma. The thermodynamics and the hydrodynamics of hot dense plasmas cannot be predicted without the knowledge of the equation of state (EOS) that describes how a material reacts to pressure and how much energy is involved. Therefore, the equation of state often takes the form of pressure and energy as functions of density and temperature. Furthermore, EOS data must be obtained in a timely manner in order to be useful as input in hydrodynamic codes. By this reason, the use of fast, robust and reasonably accurate atomic models, is necessary for computing the EOS of a material

Caracterización mediante simulación de sistemas fotovoltaicos para riegos agricolas y análisis de su rentabilidad económica

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: Este trabajo presenta un modelo desarrollado con la herramienta Simulink de Matlab de un sistema fotovoltaico de bombeo para riego agrícola. El modelo se ha aplicado en la simulación de los sistemas de riego de una finca típica de 20 ha en varios lugares. A partir de los resultados de la simulación se ha realizado el análisis económico de los sistemas fotovoltaicos necesarios. Se puede concluir que el modelo desarrollado caracteriza con éxito el funcionamiento de los sistemas fotovoltaicos. Los resultados del análisis económico muestran que la energía fotovoltaica permite una reducción de costes de la energía eléctrica utilizada por los agricultores.ABSTRACT: A photovoltaic pumping system for irrigation in agriculture has been modelled using Matlab’s Simulink. The model has been applied to simulate the irrigation systems of a typical 20 ha farm in various locations. From the results of the simulation, the economic analysis of the required photovoltaic systems has been carried out. It can be concluded that the developed model successfully characterizes the operation of the photovoltaic systems. The results of the economic analysis show that photovoltaic energy lets a cost reduction of the electric power used by farmers.info:eu-repo/semantics/publishedVersio

Analysis of the influence of the plasma thermodynamic regime in the spectrally resolved and mean radiative opacity calculations of carbon plasmas in a wide range of density and temperature

In this work the spectrally resolved, multigroup and mean radiative opacities of carbon plasmas are calculated for a wide range of plasma conditions which cover situations where corona, local thermodynamic and non-local thermodynamic equilibrium regimes are found. An analysis of the influence of the thermodynamic regime on these magnitudes is also carried out by means of comparisons of the results obtained from collisional-radiative, corona or Saha–Boltzmann equations. All the calculations presented in this work were performed using ABAKO/RAPCAL code

The Effect of Conservation Agriculture and Environmental Factors on CO2 Emissions in a Rainfed Crop Rotation

There are many factors involved in the release of CO2 emissions from the soil, such as the type of soil management, the soil organic matter, the soil temperature and moisture conditions, crop phenological stage, weather conditions, residue management, among others. This study aimed to analyse the influence of these factors and their interactions to determine the emissions by evaluating the environmental cost expressed as the kg of CO2 emitted per kg of production in each of the crops and seasons studied. For this purpose, a field trial was conducted on a farm in Seville (Spain). The study compared Conservation Agriculture, including its three principles (no-tillage, permanent soil cover, and crop rotations), with conventional tillage. Carbon dioxide emissions measured across the four seasons of the experiment showed an increase strongly influenced by rainfall during the vegetative period, in both soil management systems. The results of this study confirm that extreme events of precipitation away from the normal means, result in episodes of high CO2 emissions into the atmosphere. This is very important because one of the consequences for future scenarios of climate change is precisely the increase of extreme episodes of precipitation and periods extremely dry, depending on the area considered. The total of emission values of the different plots of the study show how the soils under the conventional system (tillage) have been emitting 67% more than soils under the conventional agriculture system during the 2010/11 campaign and 25% for the last campaign where the most appreciable differences are observed

Parametrization of the average ionization and radiative cooling rates of carbon plasmas in a wide range of density and temperature

In this work we present an analysis of the influence of the thermodynamic regime on the monochromatic emissivity, the radiative power loss and the radiative cooling rate for optically thin carbon plasmas over a wide range of electron temperature and density assuming steady state situations. Furthermore, we propose analytical expressions depending on the electron density and temperature for the average ionization and cooling rate based on polynomial fittings which are valid for the whole range of plasma conditions considered in this work