Continuous spectra in high-harmonic generation driven by multicycle laser pulses

We present observations of the emission of XUV continua in the 20-37 eV region by high harmonic generation (HHG) with $4$-$7\ \mathrm{fs}$ pulses focused onto a Kr gas jet. The underlying mechanism relies on coherent control of the relative delays and phases between individually generated attosecond pulse, achievable by adjusting the chirp of the driving pulses and the interaction geometry. Under adequate negative chirp and phase matching conditions, the resulting interpulse interference yields a continuum XUV spectrum, which is due to both microscopic and macroscopic (propagation) contributions. This technique opens the route for modifying the phase of individual attosecond pulses and for the coherent synthesis of XUV continua from multicycle driving laser pulses without the need of an isolated attosecond burst.Comment: 14 pages, 5 figures. Submitted to Physical Review

Mitochondrial inhibitors activate influx of external Ca2+ in sea urchin sperm

AbstractSea urchin sperm have a single mitochondrion which, aside from its main ATP generating function, may regulate motility, intracellular Ca2+ concentration ([Ca2+]i) and possibly the acrosome reaction (AR). We have found that acute application of agents that inhibit mitochondrial function via differing mechanisms (CCCP, a proton gradient uncoupler, antimycin, a respiratory chain inhibitor, oligomycin, a mitochondrial ATPase inhibitor and CGP37157, a Na+/Ca2+ exchange inhibitor) increases [Ca2+]i with at least two differing profiles. These increases depend on the presence of extracellular Ca2+, which indicates they involve Ca2+ uptake and not only mitochondrial Ca2+ release. The plasma membrane permeation pathways activated by the mitochondrial inhibitors are permeable to Mn2+. Store-operated Ca2+ channel (SOC) blockers (Ni2+, SKF96365 and Gd2+) and internal-store ATPase inhibitors (thapsigargin and bisphenol) antagonize Ca2+ influx induced by the mitochondrial inhibitors. The results indicate that the functional status of the sea urchin sperm mitochondrion regulates Ca2+ entry through SOCs. As neither CCCP nor dicycloexyl carbodiimide (DCCD), another mitochondrial ATPase inhibitor, eliminate the oligomycin induced increase in [Ca2+]i, apparently oligomycin also has an extra mitochondrial target

Water maser detections in southern candidates to post-AGB stars and Planetary Nebulae

We intended to study the incidence and characteristics of water masers in the envelopes of stars in the post-AGB and PN evolutionary stages. We have used the 64-m antenna in Parkes (Australia) to search for water maser emission at 22 GHz, towards a sample of 74 sources with IRAS colours characteristic of post-AGB stars and PNe, at declination $< -32 \deg$. In our sample, 39% of the sources are PNe or PNe candidates, and 50% are post-AGB stars or post-AGB candidates. We have detected four new water masers, all of them in optically obscured sources: three in PNe candidates (IRAS 12405-6219, IRAS 15103-5754, and IRAS 16333-4807); and one in a post-AGB candidate (IRAS 13500-6106). The PN candidate IRAS 15103-5754 has water fountain characteristics, and it could be the first PN of this class found. We confirm the tendency suggested in Paper I that the presence of water masers in the post-AGB phase is favoured in obscured sources with massive envelopes. We propose an evolutionary scenario for water masers in the post-AGB and PNe stages, in which ``water fountain'' masers could develop during post-AGB and early PN stages. Later PNe would show lower velocity maser emission, both along jets and close to the central objects, with only the central masers remaining in more evolved PNe.Comment: 11 pages, 5 figures. Accepted by Astronomy and Astrophysic

Evaluation of organic, conventional and intensive beef farm systems: health, management and animal production

The overall aim of the present study was to analyse and compare organic beef cattle farming in Spain with intensive and conventional systems. An on-farm study comparing farm management practices and animal health was carried out. The study also focussed on a slaughterhouse analysis by comparing impacts on the safety and quality of the cattle products. Twenty-four organic and 26 conventional farms were inspected, and farmers responded to a questionnaire that covered all basic data on their husbandry practices, farm management, veterinary treatments and reproductive performance during 2007. Furthermore, data on the hygiene and quality of 244, 2596 and 3021 carcasses of calves from organic, intensive and conventional farms, respectively, were retrieved from the official yearbook (2007) of a slaughterhouse. Differences found between organic and conventional farms across the farm analysis did not substantially reflect differences between both farm types in the predominant diseases that usually occur on beef cattle farms. However, calves reared organically presented fewer condemnations at slaughter compared with intensive and to a lesser extent with conventionally reared calves. Carcass performance also reflected differences between farm type and breed and was not necessarily better in organic farmsThis study was supported by the Xunta de Galicia (Spain;PGIDT02RA6261001PR) and I.B.P. received a research fellow-ship (AP2003-3835) from the Ministry of Science of SpainS

Paralelización de la obtención de datos de entrada del modelo de concentraciones de HYSPLIT

En esta memoria se presenta un estudio del funcionamiento del programa HYSPLIT realizado con el objetivo de detectar puntos débiles que permitan mejorar su eficiencia. HYSPLIT es un software que implementa un modelo de cálculo de trayectorias, concentraciones y dispersión de partículas atmosféricas y contaminantes ampliamente utilizado en meteorología. El trabajo se ha desarrollado en el marco de un convenio de colaboración entre la Universidad de La Laguna y la Agencia Estatal de Meteorología (AEMET)

Temporary analysis of land use changes in Pine and mixed forests in Mexico

Objective: To assess the surface changes that occurred in pine forests, mixed forests and secondary vegetation of pine and mixed forests, at the national level, during the period 2001 to 2013. Design/methodology/approach: We used the Land Use and Vegetation (USV) coverages of Series II (from 2001) and V (from 2013) of the National Institute of Statistics and Geography, of scales 1: 250,000 as primary sources of information. The classes on both coverages were grouped and homogenized, focusing on pine and mixed forests. The exchange rates and transition indicators were estimated for the analysis: estimated profit and loss surfaces, persistence indices, of exchanges and net changes, as well as the gain and loss indices to persistence. Results: The rate of changes are negative for primary forests (pine and mixed) is in a range of 0.80 to 1.84. It was observed that 120,047 km2 (57.72%) were stable surfaces; however, 36 986 km2 (18.00%) were from losses, 14 369 km2 from gains and 28 738 km2 (14.00%) from different categories. During the period analyzed, 13.69% of the primary forests(2001)&nbsp; passed to secondary vegetation in 2013. Study limitations/implications: To observe the influence of other categories, it would be important to incorporate them through the study to analyze the system globally through the country. Findings/Conclusions: The persistence area of primary forests is important for generating conservation policies.Objective: to evaluate the changes in land use that occurred in Pine and mixed forests, at the national level during the period 2001 to 2013.Design/Methodology/Approach: layers of Land Use and Vegetation (Sp. equ. USV) of Series II (from 2001) and V (from 2013) of the Instituto Nacional de Estadística y Geografía, scale 1: 250,000 were used. Different categories of vegetation under study were reclassified and homogenized for both covers. Rates of change and indicators of transitions were estimated for the spatial-temporary analysis: surfaces of estimated losses and gains, indices of persistence, exchanges and net changes; also, indices of gain and loss to persistence.Results: the rate of negative change for primary forests (Pine and mixed) ranges from 0.80 to 1.84. It was observed that 120 047 km2 (57.72%) were stable surfaces. However, 36 986 km2 (18.00%) were losses, 14 369 km2 gains and 28 738 km2 (14.00%) between categories. It was observed from 2001 to 2013 that 13.69% of the area corresponding to primary forests which existed in 2001 became part of secondary vegetation in 2013.Study limitations/Implications: in order to observe the influence of other categories, it would be important to incorporate more classes throughout the study to be analyzed globally in the system throughout the country.Findings/Conclusions: The persistence of the coverage of primary forests is important to design conservation policie

Percepción sobre la violencia en las relaciones amorosas de los estudiantes de una Facultad de Derecho y Criminología en una Universidad del Norte de México

This article presents the results of the research in which an analysis is made of the students' perception of the Faculty of Law and Criminology of a University in northern Mexico, about violence in love relationships. For this, a questionnaire was applied that is composed of 10 items of closed answers, which evaluates the prevalence, perception and violence in the courtship of 280 university students of different semesters. The general results found were the level of prevalence, perception and existence of violence were low even though there is about 20% of these 3 elements that show signs of the existence of violent behavior. It can be concluded that the educational level is an element that helps to improve the violent ways of relating, also transforms the mentally established mental schemes, promoting healthy relationships, evidenced in low prevalence, perception and existence of violent behaviors in love relationships.En este artículo se presentan los resultados de la investigación en la que se hace un análisis de la percepción que tienen los estudiantes de la Facultad de Derecho y Criminología de una Universidad del norte de México, sobre violencia en las relaciones amorosas. Para esto se aplicó un cuestionario que está compuesto por 10 ítems de respuestas cerradas, que evalúa la prevalencia, la percepción y la violencia en el noviazgo de 280 estudiantes universitarios de diferentes semestres. Los resultados generales encontrados fueron el nivel de prevalencia, percepción y existencia de violencia fueron bajos aun así existe alrededor de un 20% de estos 3 elementos que muestran indicios de la existencia de conductas violentas. Se puede concluir que el nivel educativo es un elemento que ayuda a mejorar las formas violentas de relacionarse, así mismo transforma los esquemas mentales instaurados culturalmente, promoviendo relaciones sanas, evidenciado en baja prevalencia, percepción y existencias de conductas violentas en las relaciones amorosas