970 resultados para C. Lewis
Resumo:
We have used XUV lasers to make absolute measurements of the photoabsorption coefficient of Al at energies just below that of the L3 absorption edge at 72.7 eV. Transmission measurements at photon energies of 53.7 and 63.3 eV have been made using Ne-like Ni and Ge XUV lasers. The XUV laser output was recorded in first and second orders using a flat-field spectrometer. Al foils with steps of various thicknesses were placed over the first order diffracted signal, while the second order diffraction was used to monitor the beam profile at each position. The transmission data agree extremely well with the original measurements at these wavelengths made by Henke and co-workers (Henke B L, Gullikson E M and Davis J C 1993 At. Data Nucl. Data Tables 54 18 1), but are in conflict with subsequent measurements which are currently in common use (Gullikson E M, Denham P, Mrowka S and Underwood J H 1994 Phys. Rev. B 49 16 283). The exact values of the absorption coefficients in this region of the spectrum have significant implications for the diagnosis of the energy and intensity output of XUV lasers.
Resumo:
Saturated output has been observed for both Ne and Ni-like X-ray lasers when Pumped in the transient mode. As these 'normal' transitions display very high gain, attempts have been made to observe a 2p --> 2s inner shell transition in Ne-like ions, which scale well towards the water window. Modelling of the pump conditions for Ge lasing at 6.2 run is presented. As the predicted gain is low the experiment was set up for 18 mm targets. Shots were taken on Ti, Fe, Ni and Ge. A similar to1.5 ps travelling wave pulse is applied at various times after the peak of a long, preforming Pulse. Various pump conditions were attempted but no inner shell X-ray laser was detected.
Resumo:
This paper aims to contribute to the ongoing debate on the use of resource accounting tools in regional policy making. The Northern Limits project applied Material Flow Analysis and Ecological Footprinting to regional policy making in Northern Ireland over a number of years. The early phase of the research informed the regions first sustainable development strategy which was published in 2006 with key targets relating to the Ecological Footprint and improving the resource efficiency of the economy. Phase II identified the next steps required to address data availability and quality and the use of MFA and EF in providing a measurement and monitoring framework for the strategy and in the development of the strategy implementation plan. The use of MFA and Ecological Footprinting in sustainable regional policy making and the monitoring of its implementation is an ongoing process which has raised a number of research issues which can inform the ongoing application and development of these and other resource accounting tools to within Northern Ireland, provide insights for their use in other regions and help set out the priorities for research to support this important policy area.
Resumo:
Introduction. Auditory hallucinations exist in psychotic disorders as well as the general population. Proneness to hallucinations, as measured by positive schizotypy, predicts false perceptions during an auditory signal detection task (Barkus, Stirling, Hopkins, McKie, & Lewis, 2007). Our aim was to replicate this result and extend it by examining effects of age and sex, both important demographic predictors of psychosis.
Method. A sample of 76 healthy volunteers split into 15-17 years (n = 46) and 19 years plus (n = 30) underwent a signal detection task designed to detect propensity towards false perceptions under ambiguous auditory conditions. Scores on the Unusual Experiences subscale (UE) of the O-LIFE schizotypy scale, IQ, and a measure of working memory were also assessed.
Results. We replicated our initial finding (Barkus et al., 2007): High scores on positive schizotypy were associated with false perceptions. Younger participants who scored highly on positive schizotypy reported significantly more false perceptions compared to other groups (p = .04). Older participants who had had an imaginary friend reported more false perceptions during the signal detection task (p <. 01).
Conclusions. Younger participants seem most vulnerable to the effects of positive schizotypal traits in terms of a signal detection deficit that underlies auditory hallucinations. Schizotypy may have greatest impact closer to the risk period for development of psychotic disorders.
Resumo:
Extreme ultraviolet (XUV) and X-ray harmonic spectra produced by intense laser-solid interactions have, so far, been consistent with Doppler upshifted reflection from collective relativistic plasma oscillations-the relativistically oscillating mirror mechanism(1-6). Recent theoretical work, however, has identified a new interaction regime in which dense electron nanobunches are formed at the plasma-vacuum boundary resulting in coherent XUV radiation by coherent synchrotron emission(7,8) (CSE). Our experiments enable the isolation of CSE from competing processes, demonstrating that electron nanobunch formation does indeed occur. We observe spectra with the characteristic spectral signature of CSE-a slow decay of intensity, I, with high-harmonic order, n, as I(n) proportional to n(-1.62) before a rapid efficiency rollover. Particle-in-cell code simulations reveal how dense nanobunches of electrons are periodically formed and accelerated during normal-incidence interactions with ultrathin foils and result in CSE in the transmitted direction. This observation of CSE presents a route to high-energy XUV pulses(7,8) and offers a new window on understanding ultrafast energy coupling during intense laser-solid density interactions.
Resumo:
Type 1 diabetes (T1D) increases risk of the development of microvascular complications and cardiovascular disease (CVD). Dyslipidemia is a common risk factor in the pathogenesis of both CVD and diabetic nephropathy (DN), with CVD identified as the primary cause of death in patients with DN. In light of this commonality, we assessed single nucleotide polymorphisms (SNPs) in thirty-seven key genetic loci previously associated with dyslipidemia in a T1D cohort using a casecontrol design. SNPs (n = 53) were genotyped using Sequenom in 1467 individuals with T1D (718 cases with proteinuric nephropathy and 749 controls without nephropathy i.e. normal albumin excretion). Cases and controls were white and recruited from the UK and Ireland. Association analyses were performed using PLINK to compare allele frequencies in cases and controls. In a sensitivity analysis, samples from control individuals with reduced renal function (estimated glomerular filtration rate,60 ml/min/1.73 m2) were excluded. Correction for multiple testing was performed by permutation testing. A total of 1394 samples passed quality control filters. Following regression analysis adjusted by collection center, gender, duration of diabetes, and average HbA1c, two SNPs were significantly associated with DN. rs4420638 in the APOC1 region (odds ratio [OR] = 1.51; confidence intervals [CI]: 1.19–1.91; P = 0.001) and rs1532624 in CETP (OR = 0.82; CI: 0.69–0.99; P = 0.034); rs4420638 was also significantly associated in a sensitivity analysis (P = 0.016) together with rs7679 (P = 0.027). However, no association was significant following correction for multiple testing. Subgroup analysis of end-stage renal disease status failed to reveal any association. Our results suggest common variants associated with dyslipidemia are not strongly associated with DN in T1D among white individuals. Our findings, cannot entirely exclude these key genes which are central to the process of dyslipidemia, from involvement in DN pathogenesis as our study had limited power to detect variants of small effect size. Analysis in larger independent cohorts is required.
Resumo:
Climate change is expected to have an impact on plant communities as increased temperatures are expected to drive individual species' distributions polewards. The results of a revisitation study after c. 34years of 89 coastal sites in Scotland, UK, were examined to assess the degree of shifts in species composition that could be accounted for by climate change. There was little evidence for either species retreat northwards or for plots to become more dominated by species with a more southern distribution. At a few sites where significant change occurred, the changes were accounted for by the invasion, or in one instance the removal, of woody species. Also, the vegetation types that showed the most sensitivity to change were all early successional types and changes were primarily the result of succession rather than climate-driven changes. Dune vegetation appears resistant to climate change impacts on the vegetation, either as the vegetation is inherently resistant to change, management prevents increased dominance of more southerly species or because of dispersal limitation to geographically isolated sites.
Resumo:
El dolor oncológico representa una de las principales causas de dolor crónico, siendo los opioides la primera línea de manejo, sin embargo 10% de los pacientes requieren estrategias analgésicas multimodales. La eficacia analgésica de la clonidina como coadyuvante ha sido demostrada para diversos modelos de dolor. Sin embargo no hay revisiones sistemáticas que validen su eficacia y seguridad en dolor crónico oncológico. Se realizó una revisión sistemática de la literatura a noviembre 26 de 2012, encontrando 15 trabajos (12 reportes de caso y tres ensayos clínicos controlados), n=138 pacientes. La intervención tuvo una eficacia entre 44,7 y 100%, mostrando mayor beneficio en pacientes con componente de dolor neuropático. La adición de clonidina fue bien tolerada, siendo la sedación y la disminución en tensión arterial y frecuencia cardiaca los efectos secundarios más frecuentes, con relación dosis dependiente, de resolución espontánea y en ninguno de los casos se documentó lesión secundaria en los pacientes. La vía de administración más frecuente fue neuroaxial (intratecal y peridural). La revisión sistemática no fue susceptible de metaanálisis por la heterogeneidad clínica de los estudios. Los resultados obtenidos sugieren que la adición de clonidina puede ser una opción terapeútica eficaz y segura en los pacientes con dolor crónico oncológico severo refractario a opioides a altas dosis asociado o no a infusión neuroaxial de anestésico local, en especial en presencia de componente neuropático. Sin embargo se identific la necesidad de un mayor número de ensayos clínicos controlados aleatorios que permitan establecer conclusiones definitivas.
Resumo:
El propósito de este estudio fue analizar los resultados de una intervención primaria en salud oral de una población infantil entre edades de 7 a 12 años y establecer el comportamiento presentado en la población estudiada con respecto al índice internacional de salud oral COE Y COP, determinando aumento o disminución luego de la intervención. Para ello se utilizó un instrumento de recolección de datos, posterior a la observación de los registros clínicos, logrando conocer las características de las variables planteadas en el estudio en relación al Índice de Salud Oral COE y COP – D al inicio, final y comparativo de la intervención; número de eventos requeridos para la intervención, adherencia y cambios en patrón de morbilidad luego de la intervención. De acuerdo con los resultados se encontró que el comportamiento presentado en la población estudiada con respecto al índice de salud oral COE Y COP muestra una disminución que luego del análisis de resultados concluye con el cumplimiento de la meta internacional establecida por la OMS, estableciendo como objetivo para América Latina un COP-D de 1 a 2.9 para el año 2015; lo cual para esta investigación demuestra efectividad de la intervención al obtener un índice COP-D de 2,67.