Chemical studies of the passivation of GaAs surface recombination using sulfides and thiols

Steady-state photoluminescence, time-resolved photoluminescence, and x-ray photoelectron spectroscopy have been used to study the electrical and chemical properties of GaAs surfaces exposed to inorganic and organic sulfur donors. Despite a wide variation in S2–(aq) concentration, variation of the pH of aqueous HS–solutions had a small effect on the steady-state n-type GaAs photoluminescence intensity, with surfaces exposed to pH=8, 0.1-M HS–(aq) solutions displaying comparable luminescence intensity relative to those treated with pH=14, 1.0-M Na2S·9H2O(aq). Organic thiols (R-SH, where R=–CH2CH2SH or –C6H4Cl) dissolved in nonaqueous solvents were found to effect increases in steady-state luminescence yields and in time-resolved luminescence decay lifetimes of (100)-oriented GaAs. X-ray photoelectron spectroscopy showed that exposure of GaAs surfaces to these organic systems yielded thiols bound to the GaAs surface, but such exposure did not remove excess elemental As and did not form a detectable As2S3 overlayer on the GaAs. These results imply that complete removal of As0 or formation of monolayers of As2S3 is not necessary to effect a reduction in the recombination rate at etched GaAs surfaces. Other compounds that do not contain sulfur but that are strong Lewis bases, such as methoxide ion, also improved the GaAs steady-state photoluminescence intensity. These results demonstrate that a general class of electron-donating reagents can be used to reduce nonradiative recombination at GaAs surfaces, and also imply that prior models focusing on the formation of monolayer coverages of As2S3 and Ga2S3 are not adequate to describe the passivating behavior of this class of reagents. The time-resolved, high level injection experiments clearly demonstrate that a shift in the equilibrium surface Fermi-level energy is not sufficient to explain the luminescence intensity changes, and confirm that HS– and thiol-based reagents induce substantial reductions in the surface recombination velocity through a change in the GaAs surface state recombination rate

Follow-up services for improving long-term outcomes in intensive care unit (ICU) survivors

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: Our main objective is to assess the effectiveness of follow-up services for ICU survivors that aim to identify and address unmet health needs related to the ICU period. We aim to assess the effectiveness in relation to health-related quality of life, mortality, depression and anxiety, post-traumatic stress disorder, physical function, cognitive function, ability to return to work or education and adverse events. Our secondary objectives are, in general, to examine both the various ways that follow-up services are provided and any major influencing factors. Specifically, we aim to explore: the effectiveness of service organisation (physician versus nurse led, face to face versus remote, timing of follow-up service); possible differences in services related to country (developed versus developing country); and whether participants had delirium within the ICU setting

Cardiovascular Functional Changes in Chronic Kidney Disease:Integrative Physiology, Pathophysiology and Applications of Cardiopulmonary Exercise Testing

The development of cardiovascular disease during renal impairment involves striking multi-tiered, multi-dimensional complex alterations encompassing the entire oxygen transport system. Complex interactions between target organ systems involving alterations of the heart, vascular, musculoskeletal and respiratory systems occur in Chronic Kidney Disease (CKD) and collectively contribute to impairment of cardiovascular function. These systemic changes have challenged our diagnostic and therapeutic efforts, particularly given that imaging cardiac structure at rest, rather than ascertainment under the stress of exercise, may not accurately reflect the risk of premature death in CKD. The multi-systemic nature of cardiovascular disease in CKD patients provides strong rationale for an integrated approach to the assessment of cardiovascular alterations in this population. State-of-the-art cardiopulmonary exercise testing (CPET) is a powerful, dynamic technology that enables the global assessment of cardiovascular functional alterations and reflects the integrative exercise response and complex machinery that form the oxygen transport system. CPET provides a wealth of data from a single assessment with mechanistic, physiological and prognostic utility. It is an underutilized technology in the care of patients with kidney disease with the potential to help advance the field of cardio-nephrology. This article reviews the integrative physiology and pathophysiology of cardio-renal impairment, critical new insights derived from CPET technology, and contemporary evidence for potential applications of CPET technology in patients with kidney disease

The Connectedness of Ivory Towers and Inner Cities - Conversations About Us and Them

Also PCMA Working Paper #46.http://deepblue.lib.umich.edu/bitstream/2027.42/51291/1/527.pd

Follow-up services for improving long-term outcomes in intensive care unit (ICU) survivors

Background: The intensive care unit (ICU) stay has been linked with a number of physical and psychological sequelae, known collectively as post‐intensive care syndrome (PICS). Specific ICU follow‐up services are relatively recent developments in health systems, and may have the potential to address PICS through targeting unmet health needs arising from the experience of the ICU stay. There is currently no single accepted model of follow‐up service and current aftercare programmes encompass a variety of interventions and materials. There is uncertain evidence about whether follow‐up services effectively address PICS, and this review assesses this. Objectives: Our main objective was to assess the effectiveness of follow‐up services for ICU survivors that aim to identify and address unmet health needs related to the ICU period. We aimed to assess effectiveness in relation to health‐related quality of life (HRQoL), mortality, depression and anxiety, post‐traumatic stress disorder (PTSD), physical function, cognitive function, ability to return to work or education and adverse effects. Our secondary objectives were to examine different models of follow‐up services. We aimed to explore: the effectiveness of service organisation (physician‐ versus nurse‐led, face‐to‐face versus remote, timing of follow‐up service); differences related to country (high‐income versus low‐ and middle‐income countries); and effect of delirium, which can subsequently affect cognitive function, and the effect of follow‐up services may differ for these participants. Search methods: We searched CENTRAL, MEDLINE, Embase and CINAHL on 7 November 2017. We searched clinical trials registers for ongoing studies, and conducted backward and forward citation searching of relevant articles. Selection criteria: We included randomised and non‐randomised studies with adult participants, who had been discharged from hospital following an ICU stay. We included studies that compared an ICU follow‐up service using a structured programme and co‐ordinated by a healthcare professional versus no follow‐up service or standard care. Data collection and analysis: Two review authors independently assessed studies for inclusion, extracted data, assessed risk of bias, and synthesised findings. We used the GRADE approach to assess the certainty of the evidence. Main results: We included five studies (four randomised studies; one non‐randomised study), for a total of 1707 participants who were ICU survivors with a range of illness severities and conditions. Follow‐up services were led by nurses in four studies or a multidisciplinary team in one study. They included face‐to‐face consultations at home or in a clinic, or telephone consultations or both. Each study included at least one consultation (weekly, monthly, or six‐monthly), and two studies had up to eight consultations. Although the design of follow‐up service consultations differed in each study, we noted that each service included assessment of participants' needs with referrals to specialist support if required. It was not feasible to blind healthcare professionals or participants to the intervention and we did not know whether this may have introduced performance bias. We noted baseline differences (two studies), and services included additional resources (two studies), which may have influenced results, and one non‐randomised study had high risk of selection bias. We did not combine data from randomised studies with data from one non‐randomised study. Follow‐up services for improving long‐term outcomes in ICU survivors may make little or no difference to HRQoL at 12 months (standardised mean difference (SMD) ‐0.0, 95% confidence interval (CI) ‐0.1 to 0.1; 1 study; 286 participants; low‐certainty evidence). We found moderate‐certainty evidence from five studies that they probably also make little or no difference to all‐cause mortality up to 12 months after ICU discharge (RR 0.96, 95% CI 0.76 to 1.22; 4 studies; 1289 participants; and in one non‐randomised study 79/259 deaths in the intervention group, and 46/151 in the control group) and low‐certainty evidence from four studies that they may make little or no difference to PTSD (SMD ‐0.05, 95% CI ‐0.19 to 0.10, 703 participants, 3 studies; and one non‐randomised study reported less chance of PTSD when a follow‐up service was used). It is uncertain whether using a follow‐up service reduces depression and anxiety (3 studies; 843 participants), physical function (4 studies; 1297 participants), cognitive function (4 studies; 1297 participants), or increases the ability to return to work or education (1 study; 386 participants), because the certainty of this evidence is very low. No studies measured adverse effects. We could not assess our secondary objectives because we found insufficient studies to justify subgroup analysis. Authors' conclusions: We found insufficient evidence, from a limited number of studies, to determine whether ICU follow‐up services are effective in identifying and addressing the unmet health needs of ICU survivors. We found five ongoing studies which are not included in this review; these ongoing studies may increase our certainty in the effect in future updates. Because of limited data, we were unable to explore whether one design of follow‐up service is preferable to another, or whether a service is more effective for some people than others, and we anticipate that future studies may also vary in design. We propose that future studies are designed with robust methods (for example randomised studies are preferable) and consider only one variable (the follow‐up service) compared to standard care; this would increase confidence that the effect is due to the follow‐up service rather than concomitant therapies

Passivation of GaAs surface recombination with organic thiols

Exposure of GaAs crystals to solutions of organic thiols resulted in substantial reductions in nonradiative GaAs surface recombination rates. This process yielded improvements in steady state photoluminescence signals that were comparable to those obtained after a Na2S·9H2O (aqueous) treatment. Use of a series of thiols indicated that the chemically important surface electrical trap levels behaved as a polarizable, electron deficient center. X-ray photoelectron spectroscopy indicated that the thiols did not remove excess As0 nor form detectable levels of As2S3-like phases, implying that neither of these factors is required for effective surface passivation chemistry

American black bear den-site selection and characteristics in an urban environment

Selection of den sites is a crucial aspect of American black bear (Ursus americanus) life history. High-quality dens provide thermal insulation, protection from disturbance, suitable environment for parturition and cub development, and proximity to available forage upon emergence. Black bears are increasingly coexisting with people in human-dominated landscapes; however, little is known about whether urban environments influence characteristics of dens and den site selection. Our objective was to determine the effect of housing density (a proxy for human activity and availability of anthropogenic resources) on selection of den sites in years of good and poor natural forage.We additionally compared size, shape, and location of dens of males and females to describe den characteristics and explorewhether differences existed between males and females. We revisited 34 den locations detected during a 6-year (2005–2010) urban black bear study in Aspen, Colorado, USA, and measured den entrance and den volume. We fit a conditional logistic regression model using a resource selection function framework to determine the importance of housing density and other landscape variables (elevation, slope, aspect, and vegetation type) associated with den site selection. Slope was the best predictor of den site selection and there was no relationship between den selection and housing density, indicating that black bears were neither avoiding nor seeking urban areas for denning. Dens were smaller for females (x =3.30m3, SE = 1.94, n = 22) than for males (x = 7.56 m3, SE = 3.31, n = 8), supporting the idea that females have greater constraints in den characteristics, possibly related to cub development and security from predation or because females generally are smaller than males

Why Aboriginal and Torres Strait Islander Australians fall and fracture: the codesigned Study of Indigenous Muscle and Bone Ageing (SIMBA) protocol

OBJECTIVES: Aboriginal and Torres Strait Islander Australians have a substantially greater fracture risk, where men are 50% and women are 26% more likely to experience a hip fracture compared with non-Indigenous Australians. Fall-related injuries in this population have also increased by 10%/year compared with 4.3%/year in non-Indigenous Australians. This study aims to determine why falls and fracture risk are higher in Aboriginal and Torres Strait Islander Australians. SETTING: All clinical assessments will be performed at one centre in Melbourne, Australia. At baseline, participants will have clinical assessments, including questionnaires, anthropometry, bone structure, body composition and physical performance tests. These assessments will be repeated at follow-up 1 and follow-up 2, with an interval of 12 months between each clinical visit. PARTICIPANTS: This codesigned prospective observational study aims to recruit a total of 298 adults who identify as Aboriginal and Torres Strait Islander and reside within Victoria, Australia. Stratified sampling by age and sex will be used to ensure equitable distribution of men and women across four age-bands (35-44, 45-54, 55-64 and 65+ years). PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome is within-individual yearly change in areal bone mineral density at the total hip, femoral neck and lumbar spine assessed by dual energy X-ray absorptiometry. Within-individual change in cortical and trabecular volumetric bone mineral density at the radius and tibia using high-resolution peripheral quantitative computed tomography will be determined. Secondary outcomes include yearly differences in physical performance and body composition. ETHICAL APPROVAL: Ethics approval for this study has been granted by the Monash Health Human Research Ethics Committee (project number: RES-19-0000374A). TRIAL REGISTRATION NUMBER: ACTRN12620000161921

Intravenous versus inhalational maintenance of anaesthesia for postoperative cognitive outcomes in elderly surgical patients

This is the protocol for a review and there is no abstract. The objectives are as follows: To compare maintenance of general anaesthesia for elderly surgical patients using total intravenous anaesthesia (TIVA) or inhalational anaesthesia on postoperative cognitive function, mortality, risk of hypotension, length of stay in the postanaesthetic care unit (PACU), and hospital stay

The lexicocalorimeter: Gauging public health through caloric input and output on social media

We propose and develop a Lexicocalorimeter: an online, interactive instrument for measuring the caloric content of social media and other large-scale texts. We do so by constructing extensive yet improvable tables of food and activity related phrases, and respectively assigning them with sourced estimates of caloric intake and expenditure. We show that for Twitter, our naive measures of caloric input , caloric output , and the ratio of these measures are all strong correlates with health and well-being measures for the contiguous United States. Our caloric balance measure in many cases outperforms both its constituent quantities; is tunable to specific health and well-being measures such as diabetes rates; has the capability of providing a real-time signal reflecting a population\u27s health; and has the potential to be used alongside traditional survey data in the development of public policy and collective self-awareness. Because our Lexicocalorimeter is a linear superposition of principled phrase scores, we also show we can move beyond correlations to explore what people talk about in collective detail, and assist in the understanding and explanation of how population-scale conditions vary, a capacity unavailable to black-box type methods