Reduction of the effect of aberrations in a joint transform correlator

We report the study of the influence of optical aberrations in a joint-transform correlator: The wave aberration of the optical system is computed from data obtained by ray tracing. Three situations are explored: We consider the aberration only in the first diffraction stage (generation of power spectrum), then only in the second (transformation of the power spectrum into correlation), and finally in both stages simultaneously. The results show that the quality of the correlation is determined mostly by the aberrations of the first diffraction stage and that we can optimize the setup by moving the cameras along the optical axis to a suitable position. The good agreement between the predicted data and the experimental results shows that the method explains well the behavior of optical diffraction systems when aberrations are taken into account.

A reduction of order two for infinite-order Lagrangians

Given a Lagrangian system depending on the position derivatives of any order, and assuming that certain conditions are satisfied, a second-order differential system is obtained such that its solutions also satisfy the Euler equations derived from the original Lagrangian. A generalization of the singular Lagrangian formalism permits a reduction of order keeping the canonical formalism in sight. Finally, the general results obtained in the first part of the paper are applied to Wheeler-Feynman electrodynamics for two charged point particles up to order 1/c4.

Fossil resource depletion and climate change emissions: the role of physical constrictions

[spa] En lo que concierne al cambio climático, los pronósticos de cercanos picos de combustible fósiles parecen buenas noticias pues la mayoría de las emisiones proceden de la quema de combustibles fósiles. Sin embargo, esto podría resultar engañoso de confirmarse las enormes estimaciones de reservas de carbón pues puede divisarse un intercambio de combustible fósiles con baja concentración de carbono (petróleo y gas) por otros de mayor (carbón). Ciñéndonos a esta hipótesis desarrollamos escenarios donde tan pronto el petróleo y el gas natural alcanzan su cénit la extracción de carbón crece lo necesario para compensar el descenso de los primeros. Estimamos las emisiones que se deriva de tales supuestos y las comparamos con el peor escenario del IPCC. Si bien dicho escenario parece improbable concluimos que los picos de petróleo y gas no son suficientes para evitar peligrosas sendas de gases de efecto invernadero. Las concentraciones de CO2 halladas superan con creces las 450 ppm sin signos de remisión.

Embodied pollution in Spanish household consumption: a disaggregate analysis

[spa] En este artículo aplicamos un modelo input-output ampliado medioambientalmente para analizar un aspecto específico de la hipótesis de la curva de Kuznets ambiental. El propósito del estudio es analizar si las estructuras de consumo de los hogares con una mejor ‘posición económica’ pueden tener un efecto positivo para reducir las presiones medioambientales. Para ello combinamos información de diferentes bases de datos para analizar el impacto de la contaminación atmosférica del consumo de diferentes hogares españoles en el año 2000. Consideramos nueve gases, i.e. los seis gases de efecto invernadero (CO2, CH4, N2O, SF6, HFCs, y PFCs) y otros tres gases (SO2, NOx, y NH3). Clasificamos los hogares en quintiles de gasto per capita y quintiles de gasto equivalente. Los resultados obtenidos muestran que hay una relación positiva y elevada entre el nivel de gasto y las emisiones directas e indirectas generadas por el consumo de los hogares; sin embargo, las intensidades de emisión tienden a disminuir con el nivel de gasto para los diferentes gases, con la excepción de SF6, HFCs, y PFCs.

International Equity on Greenhouse Gas Emissions and World Levels: an integrated analysis through distributive welfare indices

Up until now, analyses of the international distribution of pollutant emissions have not paid sufficient attention to the implications that, in terms of social welfare, the combined evolution of the global world average entails. In this context, this paper proposes the use of environmental welfare indices, taken and adapted from the literature on social welfare and inequality, in order to make a comprehensive examination of the international equity factor and the mean factor in this field. The proposed methodology is implemented empirically in order to explore the evolution in distributive-based environmental welfare on a global level for the three main pollutants with greenhouse gas effects: CO2, CH4 and NO, both globally and for selected years during the period of 1990- 2005. The main results found are as follows: firstly, typically, the environmental welfare associated with the overall greenhouse gases decreased significantly over the period, due primarily to the role of CO2; secondly, in contrast, the global welfare associated with CH4 and NO improved; and thirdly, typically, the evolutions can be attributed to a greater extent to the mean component than to the distributive component, although there are exceptions. These results would seem to be relevant in policy terms. JEL codes: D39; Q43; Q56. Keywords: environmental welfare: greenhouse gases; environmental equity.

FAM-MDR: a flexible family-based multifactor dimensionality reduction technique to detect epistasis using related individuals

We propose a novel multifactor dimensionality reduction method for epistasis detection in small or extended pedigrees, FAM-MDR. It combines features of the Genome-wide Rapid Association using Mixed Model And Regression approach (GRAMMAR) with Model-Based MDR (MB-MDR). We focus on continuous traits, although the method is general and can be used for outcomes of any type, including binary and censored traits. When comparing FAM-MDR with Pedigree-based Generalized MDR (PGMDR), which is a generalization of Multifactor Dimensionality Reduction (MDR) to continuous traits and related individuals, FAM-MDR was found to outperform PGMDR in terms of power, in most of the considered simulated scenarios. Additional simulations revealed that PGMDR does not appropriately deal with multiple testing and consequently gives rise to overly optimistic results. FAM-MDR adequately deals with multiple testing in epistasis screens and is in contrast rather conservative, by construction. Furthermore, simulations show that correcting for lower order (main) effects is of utmost importance when claiming epistasis. As Type 2 Diabetes Mellitus (T2DM) is a complex phenotype likely influenced by gene-gene interactions, we applied FAM-MDR to examine data on glucose area-under-the-curve (GAUC), an endophenotype of T2DM for which multiple independent genetic associations have been observed, in the Amish Family Diabetes Study (AFDS). This application reveals that FAM-MDR makes more efficient use of the available data than PGMDR and can deal with multi-generational pedigrees more easily. In conclusion, we have validated FAM-MDR and compared it to PGMDR, the current state-of-the-art MDR method for family data, using both simulations and a practical dataset. FAM-MDR is found to outperform PGMDR in that it handles the multiple testing issue more correctly, has increased power, and efficiently uses all available information.

Influència de l'ús del biodièsel en les emissions contaminants i en el consum de combustible en vehicles pesants

L’objecte d’aquest estudi consisteix en determinar la influència de l’ús del biodièsel en:1.- Les variacions en comparació amb el combustible convencional(gasoil A) en les emissions de gasos i partícules contaminants enmotors de vehicles pesants de transport de mercaderies.2.- Les variacions en comparació amb el combustible convencional(gasoil A) en el nivell de so emès per motors de vehicles pesants detransport de mercaderies.3.- Els canvis en el consum de combustible en vehicles pesants encomparació amb la utilització de gasoil A.4.- Els problemes tècnics observats en motors de vehicles pesants detransport de mercaderies durant un període de funcionament elevat

Potential of local bio-geoengineering to mitigate dangerous temperature increases in a global warming scenario

Crops and forests are already responding to rising atmospheric carbon dioxide and air temperatures. Increasing atmospheric CO2 concentrations are expected to enhance plant photosynthesis. Nevertheless, after long-term exposure, plants acclimate and show a reduction in photosynthetic activity (i.e. down-regulation). If in the future the Earth"s temperature is allowed to rise further, plant ecosystems and food security will both face significant threats. The scientific community has recognized that an increase in global temperatures should remain below 2°C in order to combat climate change. All this evidence suggests that, in parallel with reductions in CO2 emissions, a more direct approach to mitigate global warming should be considered. We propose here that global warming could be partially mitigated directly through local bio-geoengineering approaches. For example, this could be done through the management of solar radiation at surface level, i.e. by increasing global albedo. Such an effect has been documented in the south-eastern part of Spain, where a significant surface air temperature trend of -0.3°C per decade has been observed due to a dramatic expansion of greenhouse horticulture.

Nitrogen metabolism in Zucker rats is affected by moderate reduction, but not by moderate incerase in dietary protein

Marked changes in the content of protein in the diet affects the rat"s pattern of growth, but there is not any data on the effects to moderate changes. Here we used a genetically obese rat strain (Zucker) to examine the metabolic modifications induced to moderate changes in the content of protein of diets, doubling (high-protein (HP): 30%) or halving (low-protein (LP): 8%) the content of protein of reference diet (RD: 16%). Nitrogen, energy balances, and amino acid levels were determined in lean (L) and obese (O) animals after 30 days on each diet. Lean HP (LHP) animals showed higher energy efficiency and amino acid catabolism but maintained similar amino acid accrual rates to the lean RD (LRD) group. Conversely, the lean LP (LLP) group showed a lower growth rate, which was compensated by a relative increase in fat mass. Furthermore, these animals showed greater efficiency accruing amino acids. Obesity increased amino acid catabolism as a result of massive amino acid intake; however, obese rats maintained protein accretion rates, which, in the OHP group, implied a normalization of energy efficiency. Nonetheless, the obese OLP group showed the same protein accretion pattern as in lean animals (LLP). In the base of our data, concluded that the Zucker rats accommodate their metabolism to support moderates increases in the content of protein in the diet, but do not adjust in the same way to a 50% decrease in content of protein, as shown by an index of growth reduced, both in lean and obese rats.

SAR Interferometric phase noise reduction using wavelet transform

The problem of synthetic aperture radar interferometric phase noise reduction is addressed. A new technique based on discrete wavelet transforms is presented. This technique guarantees high resolution phase estimation without using phase image segmentation. Areas containing only noise are hardly processed. Tests with synthetic and real interferograms are reported.

Effectiveness of early detection on breast cancer mortality reduction in Catalonia (Spain)

Background: At present, it is complicated to use screening trials to determine the optimal age intervals and periodicities of breast cancer early detection. Mathematical models are an alternative that has been widely used. The aim of this study was to estimate the effect of different breast cancer early detection strategies in Catalonia (Spain), in terms of breast cancer mortality reduction (MR) and years of life gained (YLG), using the stochastic models developed by Lee and Zelen (LZ). Methods: We used the LZ model to estimate the cumulative probability of death for a cohort exposed to different screening strategies after T years of follow-up. We also obtained the cumulative probability of death for a cohort with no screening. These probabilities were used to estimate the possible breast cancer MR and YLG by age, period and cohort of birth. The inputs of the model were: incidence of, mortality from and survival after breast cancer, mortality from other causes, distribution of breast cancer stages at diagnosis and sensitivity of mammography. The outputs were relative breast cancer MR and YLG. Results: Relative breast cancer MR varied from 20% for biennial exams in the 50 to 69 age interval to 30% for annual exams in the 40 to 74 age interval. When strategies differ in periodicity but not in the age interval of exams, biennial screening achieved almost 80% of the annual screening MR. In contrast to MR, the effect on YLG of extending screening from 69 to 74 years of age was smaller than the effect of extending the screening from 50 to 45 or 40 years. Conclusion: In this study we have obtained a measure of the effect of breast cancer screening in terms of mortality and years of life gained. The Lee and Zelen mathematical models have been very useful for assessing the impact of different modalities of early detection on MR and YLG in Catalonia (Spain).

Reduction of oxidative cellular damage by overexpression of the thioredoxin TRX2 gene improves yield and quality of wine yeast dry active biomass

Background: Wine Saccharomyces cerevisiae strains, adapted to anaerobic must fermentations, suffer oxidative stress when they are grown under aerobic conditions for biomass propagation in the industrial process of active dry yeast production. Oxidative metabolism of sugars favors high biomass yields but also causes increased oxidation damage of cell components. The overexpression of the TRX2 gene, coding for a thioredoxin, enhances oxidative stress resistance in a wine yeast strain model. The thioredoxin and also the glutathione/glutaredoxin system constitute the most important defense against oxidation. Trx2p is also involved in the regulation of Yap1p-driven transcriptional response against some reactive oxygen species. Results: Laboratory scale simulations of the industrial active dry biomass production process demonstrate that TRX2 overexpression increases the wine yeast final biomass yield and also its fermentative capacity both after the batch and fed-batch phases. Microvinifications carried out with the modified strain show a fast start phenotype derived from its enhanced fermentative capacity and also increased content of beneficial aroma compounds. The modified strain displays an increased transcriptional response of Yap1p regulated genes and other oxidative stress related genes. Activities of antioxidant enzymes like Sod1p, Sod2p and catalase are also enhanced. Consequently, diminished oxidation of lipids and proteins is observed in the modified strain, which can explain the improved performance of the thioredoxin overexpressing strain. Conclusions: We report several beneficial effects of overexpressing the thioredoxin gene TRX2 in a wine yeast strain. We show that this strain presents an enhanced redox defense. Increased yield of biomass production process in TRX2 overexpressing strain can be of special interest for several industrial applications.

Reduction of conjugated dienoic carboxylic acids and esters with sodium dithionite

Reduction of 2,4-alkadienoic acids and esters with sodium dithionite was carried out in aqueous solution or under PTC conditions to give, almost exclusively, Z:E isomeric mixtures of the corresponding 3-alkenoic acids and esters, respectively, in good yields.

Contribution of early detection and adjuvant treatments to breast cancer mortality reduction in Catalonia, Spain

Background: Reductions in breast cancer (BC) mortality in Western countries have been attributed to the use of screening mammography and adjuvant treatments. The goal of this work was to analyze the contributions of both interventions to the decrease in BC mortality between 1975 and 2008 in Catalonia. Methodology/Principal Findings: A stochastic model was used to quantify the contribution of each intervention. Age standardized BC mortality rates for calendar years 1975-2008 were estimated in four hypothetical scenarios: 1) Only screening, 2) Only adjuvant treatment, 3) Both interventions, and 4) No intervention. For the 30-69 age group, observed Catalan BC mortality rates per 100,000 women-year rose from 29.4 in 1975 to 38.3 in 1993, and afterwards continuously decreased to 23.2 in 2008. If neither of the two interventions had been used, in 2008 the estimated BC mortality would have been 43.5, which, compared to the observed BC mortality rate, indicates a 46.7% reduction. In 2008 the reduction attributable to screening was 20.4%, to adjuvant treatments was 15.8% and to both interventions 34.1%. Conclusions/Significance: Screening and adjuvant treatments similarly contributed to reducing BC mortality in Catalonia. Mathematical models have been useful to assess the impact of interventions addressed to reduce BC mortality that occurred over nearly the same periods.

1.48 and 1.84 µm thulium emissions in monoclinic KGd(WO4)2 single crystals

By exciting at 788 nm, we have characterized the near infrared emissions of trivalent thulium ions in monoclinic KGd(WO4)2 single crystals at 1.48 and 1.84 mm as a function of dopant concentration from 0.1% to 10% and temperature from 10 K to room temperature. We used the reciprocity method to calculate the maximum emission cross-section of 3.0310220 cm2 at 1.838 mm for the polarization parallel to the Nm principal optical direction. These results agrees well with the experimental data. Experimental decay times of the 3H4!3F4 and 3F4!3H6 transitions have been measured as a function of thulium concentration.