AlGaInP red-emitting light emitting diode under extremely high pulsed pumping

Efficiency of commercial 620 nm InAlGaP Golden Dragon-cased high-power LEDs has been studied under extremely high pump current density up to 4.5 kA/cm2 and pulse duration from microsecond down to sub-nanosecond range. No efficiency decrease and negligible red shift of the emission wavelength is observed in the whole range of drive currents at nanosecond-range pulses with duty cycles well below 1%. Analysis of the pulse-duration dependence of the LED efficiency and emission spectrum suggests the active region overheating to be the major mechanism of the LED efficiency reduction at higher pumping, dominating over the electron overflow and Auger recombination.

Donde esten mis hijos alli que me entierren. the migration history of Aura Lila Callejas

"Adonde esten mis hijos alli que me entierren," presents the migration history of my great-aunt Aura Lila Callejas. This work utilizes the oral history method to examine one woman's migration experience in an attempt to identify various theoretical issues. Aura Lila's immigration experience sheds light on a number of different issues, including the reasons why people migrate and how they adapt to an entirely new and often frightening set of circumstances in the country of arrival. The oral history method has proven useful in presenting some of the ways in which structural factors combine with personal motivations to provide the impetus for Aura Lila's journey of international migration. My work with Aura Lila has also served to highlight some of the existing gaps in the current literature regarding Nicaraguans in the United States and the importance of the family within the overall process of migration. Finally, this work explores the nature of the relationship between the researcher and subject within the ethnographic process. While much of Aura Lila's story remains unique and specific to her family's history, her narrative can be related to the growing body of literature focusing on women's life histories.

Degree of conversion of different composite resins photo-activated with light-emitting diode and argon ion laser

This study evaluated the degree of conversion (DC%) of one experimental and different brands of composite resins light-cured by two light sources (one LED and one argon laser). The percentage of unreacted C = C was determined from the ratio of absorbance intensities of aliphatic C = C (peak at 1637 cm−1) against internal standards before and after curing: aromatic C–C (peak at 1610 cm−1) except for P90, where %C = C bonds was given for C–O–C (883 cm−1) and C–C (1257 cm−1). ANOVA and Tukey’s test revealed no statistically significant difference among Z350 (67.17), Z250 (69.52) and experimental (66.61 ± 2.03) with LED, just among them and Evolu-X (75.51) and P90 (32.05) that showed higher and lower DC%, respectively. For the argon laser, there were no differences among Z250 (70.67), Z350 (69.60), experimental (65.66) and Evolu-X (73, 37), however a significant difference was observed for P90 (36.80), which showed lowest DC%. The light sources showed similar DC%, however the main difference was observed regarding the composite resins. The lowest DC% was observed for the argon laser. P90 showed the lowest DC% for both light-curing sources.

The Experience of Dis-placed Communities: Mis-placed Educational Opportunities

Newfoundland and Labrador (NL) has a long history of out-migration and internal migration between communities in coastal areas within the province. Resettlement programs initiated by the NL government between 1954 and 1975 accounted for the internal migration of approximately 30,000 people from 300 communities. Modern-day encounters with these abandoned communities are relevant to understanding the loss of place and home, as significant numbers of students in NL today are affected by migration. This dissertation is a phenomenological study of the experiences of educators as they explored the remnants of an abandoned community. The participants of the study were six experienced public school educators with teaching experience at the primary, elementary, intermediate, and secondary levels. The study took place in eight abandoned communities located on the western shore of Placentia Bay, where mainly the remnants of Isle Valen, St. Leonard’s, St. Kyran’s, and Great Paradise were explored. Data collection consisted of two personal interviews and one group hermeneutic circle, with the aim to answer one fundamental question: What is the experience of educators exploring the remnants of an abandoned community? Data in this study are represented by lived experience descriptions, which were interpreted hermeneutically and guided by four phenomenological existentials: temporality, corporeality, spatiality, and relationality. The most prominent themes emerging from the educators’ anecdotes were determined to be attunement, tension, and intensity. The results of this study not only provide deeper insight into communities abandoned through resettlement; they also reveal the significance of place in our lives, place as heuristic teacher, the pedagogical power of place, the need for local, meaningful place-based experiences in a curriculum as lived, and their potential for furthering personal and educational insight no matter where in this world we live or dwell.

Electrical characterization of amorphous silicon MIS-based structures for HIT solar cell applications

A complete electrical characterization of hydrogenated amorphous silicon layers (a-Si:H) deposited on crystalline silicon (c-Si) substrates by electron cyclotron resonance chemical vapor deposition (ECR-CVD) was carried out. These structures are of interest for photovoltaic applications. Different growth temperatures between 30 and 200 °C were used. A rapid thermal annealing in forming gas atmosphere at 200 °C during 10 min was applied after the metallization process. The evolution of interfacial state density with the deposition temperature indicates a better interface passivation at higher growth temperatures. However, in these cases, an important contribution of slow states is detected as well. Thus, using intermediate growth temperatures (100–150 °C) might be the best choice.

Carlos Gowland y el ex-Banco Nacional: á mis amigos y al público

Signed on p. 27: Carlos Gowland.

Low-linewidth and tunable single frequency 1x2 multimode-interferometer-Fabry-Perot laser diode

In this paper, we present a novel 1x2 multi-mode-interferometer-Fabry-Perot (MMI-FP) laser diode, which demonstrated tunable single frequency operation with more than 30dB side mode suppression ratio (SMSR) and a tuning range of 25nm in the C and L bands, as well as a 750 kHz linewidth. These lasers do not require material regrowth and high resolution gratings; resulting in a simpler process that can significantly increase the yield and reduce the cost.

Stable isotope record and aklenonen index of MIS 11 sediments

The interglacial known as Marine Isotope Stage 11 has been proposed to be analogous to the Holocene, owing to similarities in the amplitudes of orbital forcing. It has been difficult to compare the periods, however, because of the long duration of Stage 11 and a lack of detailed knowledge of any extreme climate events that may have occurred. Here we use the distinctive phasing between seasurface temperatures and the oxygen-isotope records of benthic foraminifera in the southeast Atlantic Ocean to stratigraphically align the Holocene interglacial with the first half of the Marine Isotope Stage 11 interglacial optimum. This alignment suggests that the second half of Marine Isotope Stage 11 should not be used as a reference for 'pre-anthropogenic' greenhouse-gas emissions. By compiling benthic carbon-isotope records from sites in the Atlantic Ocean on a single timescale, we also find that meridional overturning circulation strengthened about 415,000 years ago, at a time of high orbital obliquity. We propose that this mechanism transported heat to the high northern latitudes, inhibiting significant ice-sheet build-up and prolonging interglacial conditions. We suggest that this mechanism may have also prolonged other interglacial periods throughout the past 800,000 years.

Planktic foraminifera isotopes, temperature and d18O of seawater at the central Walvis Ridge for Termination II (MIS 6 to 5), sediment core 64PE-174P13

Salty and warm Indian Ocean waters enter the South Atlantic via the Agulhas leakage, south of Africa. Model simulations and proxy evidence of Agulhas leakage strengthening during glacial terminations led to the hypothesis that it was an important modulator of the Atlantic Ocean circulation. Yet, the fate of the leakage salinity and temperature anomalies remains undocumented beyond the southern tip of Africa. Downstream of the leakage, new paleoceanographic evidence from the central Walvis Ridge (southeast Atlantic) shows that salinity increased at the thermocline, and less so at the surface, during glacial termination II. Thermocline salinity change coincided with higher frequency of Agulhas rings passage at the core location and with salinity maxima in the Agulhas leakage area, suggesting that leakage waters were incorporated in the Atlantic circulation through the thermocline. Hydrographic changes at the Walvis Ridge and in the leakage area display a distinct two-step structure, with a reversal at ca. 134 ka. This matched a wet interlude within the East Asia weak monsoon interval of termination II, and a short-lived North Atlantic warming. Such concurrence points to a Bølling-Allerød-like recovery of the Atlantic circulation amidst termination II, with a northward shift of the Intertropical Convergence Zone and Southern Hemisphere westerlies, and attendant curtailment of the interocean connection south of Africa.

Paleoceanographical studies of MIS 11 for sediment core MD99-2277

Paleoceanographical studies of Marine Isotope Stage (MIS) 11 have revealed higher-than-present sea surface temperatures (SSTs) in the North Atlantic and in parts of the Arctic, but lower-than-present SSTs in the Nordic Seas, the main throughflow-area of warm water into the Arctic Ocean. We resolve this contradiction by complementing SST data based on planktic foraminiferal abundances with surface salinity changes using hydrogen isotopic compositions of alkenones in a core from the central Nordic Seas. The data indicate the prevalence of a relatively cold, low-salinity, surface water layer in the Nordic Seas during most of MIS 11. In spite of the low-density surface layer, which was kept buoyant by continuous melting of surrounding glaciers, warmer Atlantic water was still propagating northward at the subsurface thus maintaining meridional overturning circulation. This study can help to better constrain the impact of continuous melting of Greenland and Arctic ice on high-latitude ocean circulation and climate.

(MIS)PERCEIVED DRINKING NORMS AND HAZARDOUS DRINKING BEHAVIOURS IN UNIVERSITY FIRST-YEAR UNDERGRADUATE STUDENTS AND THE EFFECTS OF GENDER

Purpose: Across Canada, undergraduate university students are one of the highest alcohol-consuming populations. Many students engage in hazardous drinking and are at risk for negative health and social consequences. Social Norms Theory suggests that students’ overestimation of drinking norms can result in an increase in their drinking behaviour. As of yet, none of the literature addresses the possible link between drinking norm (mis)perception and hazardous drinking in a Canadian undergraduate context. This is the first Canadian study to examine this potential association in first-year undergraduate students across multiple universities using gender as an effect modifier. Methods: Using data collected by the Caring Campus Project, for 2347 first-year students from three Canadian universities, I evaluated the prevalence of drinking norm misperceptions by site and gender. Using multiple-logistic regression models, I analyzed the relationship between misperceived drinking norms and hazardous drinking behaviours (assessed via AUDIT-C). Results: The proportion of students who overestimated drinking and binge drinking frequency norms varied by site and gender. There was a positive relationship between overestimated drinking/ binge drinking frequency norms and hazardous drinking, modified by gender. Controlling for living arrangement and site, the odds of female students being hazardous drinkers increased by a factor of 2.27 (CI: 1.73-2.99) when the drinking frequency norm was overestimated. A non-significant association was found for male students. Among female students, when living arrangement and site were controlled, the odds of being a hazardous drinker were 1.83 (0.84-3.95) and 2.69 (1.24-5.83) times greater when the drinking frequency norm was perceived at “2-4 times per month” and “2 or more times per week”, respectively. Among male students, when living arrangement, previous residence and site were controlled, the odds of being a hazardous drinker were 4.03 (2.62-6.19) and 8.54 (5.41-13.49) times greater when the binge drinking frequency norm was perceived at “2-4 times per month” and “2 or more times per week”, respectively. Conclusion: This novel study enhances the understanding of the association between (mis)perceived drinking norms and drinking behaviours in Canadian undergraduate students. The demonstrated importance of gender and site provides a strong impetus for Canadian universities to develop targeted alcohol reduction interventions.

"I Forbid You To Like It:" The Smiths, David Cameron, and the Politics of (Mis)appropriating Popular Culture

The Smiths were a critically acclaimed 1980s “indie” band that achieved cult-status within the five years they were musically active. Several studies on fandom have focused on The Smiths, particularly its frontman Morrissey, whose “apostles” are among the most committed on the popular music circuit. Yet British Prime Minister David Cameron’s repeated claims to Smiths fandom have been rebuked by fans, and the band themselves, as being incompatible with his right-wing political program; former Smiths guitarist and songwriter Johnny Marr tweeted: “David Cameron, stop saying you like The Smiths, no you don’t. I forbid you to like it.”

This article proceeds from the possibility that David Cameron was not being cynical in professing his admiration for The Smiths and considers music’s role in the embodiment of a social identity. Drawing on recent examples in the UK and the US, the article explores politicians’ problematic relationship with popular culture, alongside the notion that when an artist’s music is appropriated, they themselves are appropriated.

Tropical limestone forest resilience and late Pleistocene foraging during MIS-2 in the Tràng An massif, Vietnam

In this paper we present a multi-proxy study of tropical limestone forest and its utilization by human groups during the major climatic and environmental upheavals of MIS-2 (29-11.7 kBP). Our data are drawn from new field research within the Tràng An World Heritage property on the edge of the Red River Delta, northern Vietnam. Key findings from this study include 1) that limestone forest formations were resilient to the large-scale landscape transformation of the Sunda continent at the end of the last glaciation; 2) that prehistoric human groups were probably present in this habitat through-out MIS-2; and 3) that the forested, insular, karst of Tràng An provided foragers with a stable resource-base in a wider changing landscape. These results have implications for our understanding of the prehistoric utilization of karst environments, and resonance for their conservation in the face of climate and environmental change today.