Hybrid SGP4 orbit propagator

Two-Line Elements (TLEs) continue to be the sole public source of orbiter observations. The accuracy of TLE propagations through the Simplified General Perturbations-4 (SGP4) software decreases dramatically as the propagation horizon increases, and thus the period of validity of TLEs is very limited. As a result, TLEs are gradually becoming insufficient for the growing demands of Space Situational Awareness (SSA). We propose a technique, based on the hybrid propagation methodology, aimed at extending TLE validity with minimal changes to the current TLE-SGP4 system in a non-intrusive way. It requires that the institution in possession of the osculating elements distributes hybrid TLEs, HTLEs, which encapsulate the standard TLE and the model of its propagation error. The validity extension can be accomplished when the end user processes HTLEs through the hybrid SGP4 propagator, HSGP4, which comprises the standard SGP4 and an error corrector.Comment: 18 pages, 4 figure

Aplicació de residus orgànics com a fertilitzants agrícoles, com a mitjà per a evitar la contaminació ambiental

L'acumulació de residus és un dels aspectes que cal considerar a l'hora d'estudiar la problemàtica de contaminació del medi ambient. La concentració d'habitants en els nuclis urbans, així com també la d'animals en el medi rural —ramaderia intensiva— provoca l'aparició de grans quantitats de materials residuals corn: purins, fems, fangs de depuradores, deixalles, etc. El poder contaminant d'aquests residus es prou conegut: organismes patògens, metalls pesants, males olors, contaminació d'aigües subterrànies, etc. Aquests residus poden esser sotmesos a diferents tractaments per tal d'evitar o disminuir llur poder contaminant. Nosaltres apuntarem ací llur aprofitament agrícola —corn a adob—, com a possible solució. La necessitat que aquesta pràctica es faci d'una forma controlada implica un treball de recerca sobre quines han d'ésser les condicions idònies i sobre determinats mètodes analítics: fraccionament de la M.O. del sòl, contingut en macro i micronutrients i qualitat del producte. La present comunicació inclourà els aspectes següents: a) Exemples d'aplicació correcta i incorrecta de purins i fangs en diferents terrenys. Evolucio de la M.O. b) Efectes de l'aplicació del «compost» de deixalles-fang de depuradora en un cultiu de ray-grass. c) Exemple d'aplicació de «compost» de deixalles en cultiu de productes hortícoles; paràmetres de qualitat

Particle growing mechanisms in Ag-ZrO2 and Au-ZrO2 granular films obtained by pulsed laser deposition

Thin films consisting of Ag and Au nanoparticles embedded in amorphous ZrO2 matrix were grown by pulsed laser deposition in a wide range of metal volume concentrations in the dielectric regime (0.08<x(Ag)<0.28 and 0.08<x(Au)<0.52). High resolution transmission electron microscopy (TEM) showed regular distribution of spherical Au and Ag nanoparticles having very sharp interfaces with the amorphous matrix. Mean particle size determined from X-ray diffraction agreed with direct TEM observation. The silver mean diameter increases more abruptly with metal volume content than that corresponding to gold particles prepared under the same conditions. Two mechanisms of particle growing are observed: nucleation and particle coalescence, their relative significance being different in both granular systems, which yields very different values of the percolation threshold (xc(Ag)~0.28 and xc(Au)~0.52).Comment: 6 figure

Comparative analysis of attributional style and self-esteem in a sample of depressed patients and control subjects

En la presente investigación se ha analizado el papel que desempeñan la variable atribucional y la autoestima en estados depresivos. El estudio atribucional es de capital importancia en la dinámica de la personalidad, ya que las atribuciones causales son mecanismos sesgados de afrontamiento que guían la conducta del sujeto. Metodología. Para llevar a cabo esta investigación se ha evaluado la autoestima y los sesgos atribucionales en una muestra de 40 pacientes depresivos y se ha comparado con 80 sujetos control normales. Resultados. Los resultados de esta investigación muestran que los pacientes depresivos realizaron atribuciones más internas para los eventos negativos que el grupo control normal y atribuciones más externas que los normales para los sucesos positivos, presentando un exagerado sesgo atribucional. Conclusiones. Estos datos nos sugieren que los pacientes depresivos tienden a culparse de sus fallos a sí mismos. Los pacientes depresivos realizaron atribuciones más estables y globales para los hechos negativos que para los positivos en comparación con los sujetos normales, considerando que dicha situación negativa se mantendrá en el tiempo y se globalizará a otras áreas de su vida. Este tipo de estudios resultan de utilidad para el desarrollo de programas eficaces de tratamiento y de instrumentos de evaluación de la depresión.The present study assesses the role of attributions and self-esteem in depressive states. In depression, attributions can become central biased coping mechanisms that guide individual behavior. Methods. Self-esteem and attribution bias was assessed in 40 depressed and 80 normal controls. Results. Results of this investigation show that depressed patients made more internal attributions to negative events, and more external attributions for positive events than their normal counterparts, confirming an exaggerated attributional bias. Conclusions. The results suggest that depressed patients tend to blame themselves for their mistakes. Depressed patients made more stable and global attributions for negative events than for positive events, as opposed to what happens with the normal controls, making us believe that this bias will be maintained in time, and will eventually generalize to other life areas. This kind of study seems useful to develop efficient treatment programs and evaluation tools of depression

Tell me what you smell and your protein i will guess

Comunicaciones a congreso

Differential expression of genes involved in iron metabolism in Aspergillus fumigatus

The ability of fungi to survive in many environments is linked to their capacity to acquire essential nutrients. Iron is generally complexed and available in very limited amounts. Like bacteria, fungi have evolved highly specific systems for iron acquisition. Production and uptake of iron-chelating siderophores has been shown to be important for certain human bacterial pathogens, as well as in fungal pathogens such as Cryptococcus neoformans and Fusarium graminearum. This system also enables the opportunistic fungal pathogen Aspergillus fumigatus to infect and subsequently colonize the human lung. In this study, advantage was taken of genome sequence data available for both Aspergillus nidulans and A. fumigatus either to partially clone or to design PCR primers for 10 genes putatively involved in siderophore biosynthesis or uptake in A. fumigatus. The expression of these genes was then monitored by semi-quantitative and quantitative real-time PCR over a range of iron concentrations. As expected, the putative biosynthetic genes sidA, sidC and sidD were all strongly up-regulated under iron starvation conditions, although the variable degree of induction indicates complex regulation by a number of transcriptional factors, including the GATA family protein SreA. In contrast, the gene sidE shows no iron-regulation, suggesting that SidE may not be involved in siderophore biosynthesis. The characterisation of the expression patterns of this subset of genes in the iron regulon facilitates further studies into the importance of iron acquisition for pathogenesis of A. fumigatus. [Int Microbiol 2006; 9(4):281-287

Psychotherapy to treat consequences of interpersonal violence suffered in childhood and adolescence in Latin America:A systematic review

Introduction/Objective. As in the rest of the world, in Latin America there is a high prevalence of interpersonal violence (IV) in childhood and adolescence, which is associated with psychological consequences in the short, medium and long term. At the international level, progress has been made in the recognition of evidence-based psychotherapies, but the situation in Latin America is unknown. The objective of this systematic review of the literature is to identify which models or modalities of psychotherapy have been shown to be effective in Latin America. Methods. A systematic search of five databases was carried out with search terms relating to psychosocial interventions people exposed to IV during childhood, based in Latin America. Studies on Latino populations based in United States were excluded.Results. 14 papers describing 13 studies and one follow-up were identified. Individual and group interventions (mainly cognitive-behavioural and with psychodynamic influence) were included. Although all showed clinically or statistically significant changes in symptoms of post-traumatic stress, anxiety and depression, most were pilot studies with important methodological limitations and high risk of bias.Conclusions. It is necessary to progress clinical practice in Latin America with more robust research (i.e. controlled and randomized clinical trials) that produce more reliable evidence of the effectiveness of psychosocial interventions for IV in children and adolescents in in the Latin American context