Absorption tails and extinction in luminescent solar concentrators

Non-ultraviolet (UV) photoexposure of luminescent solar concentrators (LSCs) can produce photoproducts that cause additional extinction at wavelengths somewhat longer than the main dye absorption peak. This photo-induced 'tails' extinction is deleterious to luminous output in collectors of useful lengths. An experimental method that enables the subdivision of tails extinction in an LSC into absorbed and scattered components is described. The relevant theory is outlined, and experimental results are presented for a polymethyl methacrylate (PMMA) LSC containing Lumogen F083 dye. For this sample, tails absorption increased significantly with outdoor exposure, while tails scattering remained constant. Further measurements indicate that LSC luminous output is around five times more sensitive to tails absorption than to fluorescence quenching. This work also indicates that merely checking for dye quenching, as is often done, can be a misleading indicator of long-term LSC output. © 2010 Elsevier B.V. All rights reserved

Uniform white light distribution with low loss from coloured LEDs using polymer doped polymer mixing rods

Colour mixing of red, green and blue (RGB) LEDs is demonstrated for a 6 cm long PMMA cylindrical rod with a transparent refractive index matched micro particle (TRIMM) diffuser sheet at the output end. Ray tracing simulations have been performed, and the output light distributions, transmittances and losses modelled and compared with experiment. Photographed and modelled colour mixing results are presented for rods with and without TRIMM sheet mixers. The TRIMM particles homogenize the light output of plain PMMA rods to form white light, with negligible backscattering. A simple method for measuring the concentration of the particles in the diffuser sheet is described, and computer modeling and analysis of TRIMM particle systems is discussed

Perylene dye photodegradation due to ketones and singlet oxygen

The photodegradation rate of a perylene dye (Lumogen F Yellow 083) in methyl isobutyrate was found to increase with ketone concentration for two different ketones. Of the ketones employed, methyl pyruvate, an impurity in methyl methacrylate, was found to be particularly deleterious to dye stability. In agreement with other published studies, the addition of the anti-oxidant DABCO (1,4-diazabicyclo-[2.2.2] octane) to the dye matrix was found to increase dye stability; however when ketones were present, DABCO lead to increased photodegradation. These results highlight the importance of removing ketone impurities from dye matrices during production of Luminescent Solar Concentrators (LSCs). © 2009 Elsevier Ltd. All rights reserved

Satisfaction with democracy and voter turnout

Numerous studies conclude that countries in which citizens express higher levels of satisfaction with democracy also tend to display higher levels of voter turnout in national elections. Yet it is difficult to draw causal inferences from this positive cross-sectional relationship, because democracies feature many historical, cultural, and institutional differences that are not easily controlled for in cross-sectional comparisons. We apply an alternative, temporal approach to this issue by asking the question: Are over-time declines (increases) in aggregate levels of satisfaction within democracies associated with increases (declines) in levels of voter turnout within these democracies? Our temporal analysis of this relationship in 12 democracies over the period 1976–2011 reveals a pattern that is the opposite of that suggested by previous cross-sectional studies: namely, we find that over-time increases in citizens’ satisfaction with democracy are associated with significant decreases in voter turnout in national elections in these countries. </jats:p

Spatial ecology of jaguars, pumas, and ocelots: a review of the state of knowledge

Knowledge of the spatial ecology of mammalian carnivores is critical for understanding species’ biology and designing effective conservation and management interventions. We reviewed the available information about the spatial ecology of jaguars Panthera onca, pumas Puma concolor, and ocelots Leopardus pardalis, and we examined how sex and extrinsic variables affect their spatial behaviour. Sixty-one articles addressing home range, home range overlap, daily net displacement (straight-line distance between two locations on consecutive days), and/or distance of dispersal of the three species were included. Meta-analysis, ANOVA, ANCOVA, and beta regression tests were run to analyse differences among species and sexes and to elucidate the influence of other variables, such as latitude and ecoregion, on spatial behaviour. Pumas had on average larger home ranges (mean ± SE: 281.87 ± 35.76 km) than jaguars (128.61 ± 49.5 km) and ocelots (12.46 ± 3.39 km). Intersexual range overlap was higher than intrasexual range overlap in jaguars and pumas. Sex affected the home range size of all three species, but only influenced daily net displacement in ocelots. Ecoregion affected the home range size of all three species but did not significantly affect either the daily net displacement or the dispersal distance of pumas. Latitude affected the home range size of jaguars and pumas. It did not affect daily net displacement or dispersal distance in jaguars and pumas, but did affect daily net displacement in ocelots. Although there was a lack of studies in most countries for the three species, information was particularly lacking in the Neotropics for jaguars and pumas and in North America for ocelots. Researchers usually presented low sample sizes and used different methods to examine the ecological issues considered here. Homogenisation of methods is needed to clarify the ecology of these species and to allow a better understanding of the threats to their populations.Peer Reviewe

Improved Upper Limit on the Neutrino Mass from a Direct Kinematic Method by KATRIN.

We report on the neutrino mass measurement result from the first four-week science run of the Karlsruhe Tritium Neutrino experiment KATRIN in spring 2019. Beta-decay electrons from a high-purity gaseous molecular tritium source are energy analyzed by a high-resolution MAC-E filter. A fit of the integrated electron spectrum over a narrow interval around the kinematic end point at 18.57&nbsp;keV gives an effective neutrino mass square value of (-1.0_{-1.1}^{+0.9})  eV^{2}. From this, we derive an upper limit of 1.1&nbsp;eV (90%&nbsp;confidence level) on the absolute mass scale of neutrinos. This value coincides with the KATRIN sensitivity. It improves upon previous mass limits from kinematic measurements by almost a factor of 2 and provides model-independent input to cosmological studies of structure formation

The effects of an enhanced simulation programme on medical students' confidence responding to clinical deterioration

BACKGROUND: Clinical deterioration in adult hospital patients is an identified issue in healthcare practice globally. Teaching medical students to recognise and respond to the deteriorating patient is crucial if we are to address the issue in an effective way. The aim of this study was to evaluate the effects of an enhanced simulation exercise known as RADAR (Recognising Acute Deterioration: Active Response), on medical students’ confidence. METHODS: A questionnaire survey was conducted; the instrument contained three sections. Section 1 focused on students’ perceptions of the learning experience; section 2 investigated confidence. Both sections employed Likert-type scales. A third section invited open responses. Questionnaires were distributed to a cohort of third-year medical students (n = 158) in the North East of Scotland 130 (82 %) were returned for analysis, employing IBM SPSS v18 and ANOVA techniques. RESULTS: Students’ responses pointed to many benefits of the sessions. In the first section, students responded positively to the educational underpinning of the sessions, with all scores above 4.00 on a 5-point scale. There were clear learning outcomes; the sessions were active and engaging for students with an appropriate level of challenge and stress; they helped to integrate theory and practice; and effective feedback on their performance allowed students to reflect and learn from the experience. In section 2, the key finding was that scores for students’ confidence to recognise deterioration increased significantly (p. < .001) as a result of the sessions. Effect sizes (Eta(2)) were high, (0.68–0.75). In the open-ended questions, students pointed to many benefits of the RADAR course, including the opportunity to employ learned procedures in realistic scenarios. CONCLUSIONS: The use of this enhanced form of simulation with simulated patients and the judicious use of moulage is an effective method of increasing realism for medical students. Importantly, it gives them greater confidence in recognising and responding to clinical deterioration in adult patients. We recommend the use of RADAR as a safe and cost-effective approach in the area of clinical deterioration and suggest that there is a need to investigate its use with different patient groups