Exciton lifetime and emission polarization dispersion in strongly in-plane asymmetric nanostructures

We present experimental and theoretical investigation of exciton recombination dynamics and the related polarization of emission in highly in-plane asymmetric nanostructures. Considering general asymmetry- and size-driven effects, we illustrate them with a detailed analysis of InAs/AlGaInAs/InP elongated quantum dots. These offer a widely varied confinement characteristics tuned by size and geometry that are tailored during the growth process, which leads to emission in the application-relevant spectral range of 1.25-1.65 {\mu}m. By exploring the interplay of the very shallow hole confining potential and widely varying structural asymmetry, we show that a transition from the strong through intermediate to even weak confinement regime is possible in nanostructures of this kind. This has a significant impact on exciton recombination dynamics and the polarization of emission, which are shown to depend not only on details of the calculated excitonic states but also on excitation conditions in the photoluminescence experiments. We estimate the impact of the latter and propose a way to determine the intrinsic polarization-dependent exciton light-matter coupling based on kinetic characteristics.Comment: 11 pages, 8 figure

Coherent response of lakes in Ontario, Canada to reductions in sulphur deposition: the effects of climate on sulphate concentrations

International audienceSulphate deposition in south-central Ontario declined between 1976 and 2000 by more than 50%, whereas lake sulphate (SO42?) concentrations decreased by, on average, only half as much. To investigate the factors that controlled this slower than expected response, the temporal patterns in lake SO42? concentrations were compared with patterns in both deposition and climate, since climate has a major influence on the hydrological cycle in this part of the continent. To do this, the temporal coherence in SO42? concentrations between 9 lake basins was estimated using the intraclass correlation from a repeated-measures analysis of variance and two subsets of lakes were found (six in one group, four in the other), each with lakes having synchronous patterns. One subset (4 lakes) included the 3 with the longest water replenishment times (>3.4 yr) which are expected to respond to decreases in SO42? deposition more slowly. However, the average pattern reflecting the temporal changes of each of the two subsets was very similar. The response of both subsets of lakes to the decreasing SO42? deposition over two decades was independent of the degree of acidification or sensitivity to acidification of the lakes. In a determination of which factors best predicted each of those two subsets' SO42? time series, good predictive models were produced by regional/global-scale climate indices, specifically the Southern Oscillation Index (SOI) describing the El Niño Southern Oscillation (ENSO) and the North Atlantic Oscillation Index (NAOI), as well as by SO42? deposition indices. When the predictor variables were combined, models which described the long-term changes in lake SO42? concentration best included the SOI, the NAOI and SO42? deposition. Thus, large-scale climate factors play a major role in determining the response of aquatic systems to changes in SO42? deposition, perhaps through their influence on lake and/or catchment processes that effectively delay recovery. Keywords: Atmospheric deposition, lake recovery, temporal trends, climate, temporal coherenc

Conflicting rights: How the prohibition of human trafficking and sexual exploitation infringes the right to health of female sex workers in Phnom Penh, Cambodia

While repressive laws and policies in relation to sex work have the potential to undermine HIV prevention efforts, empirical research on their interface has been lacking. In 2008, Cambodia introduced anti-trafficking legislation ostensibly designed to suppress human trafficking and sexual exploitation. Based on empirical research with female sex workers, this article examines the impact of the new law on vulnerability to HIV and other adverse health outcomes. Following the introduction of the law, sex workers reported being displaced to streets and guesthouses, impacting their ability to negotiate safe sex and increasing exposure to violence. Disruption of peer networks and associated mobility also reduced access to outreach, condoms, and health care. Our results are consistent with a growing body of research which associates the violation of sex workers’ human rights with adverse public health outcomes. Despite the successes of the last decade, Cambodia’s AIDS epidemic remains volatile and the current legal environment has the potential to undermine prevention efforts by promoting stigma and discrimination, impeding prevention uptake and coverage, and increasing infections. Legal and policy responses which seek to protect the rights of the sexually exploited should not infringe the right to health of sex workers.NIH grants: U01AI0154241, 1R21 DA025441, and 1R01NR010995 and additional funding from a Faculty Initiative grant from the Pacific Rim Research Program of the University of California. Lisa Maher is supported by a National Health and Medical Research Council Senior Research Fellowshi

Amphetamine-type stimulant use and HIV/STI risk behaviour among young female sex workers in Phnom Penh, Cambodia

Background: Use of amphetamine-type substances (ATS) has been linked to increased risk of HIV and other sexually transmitted infections (STI) worldwide. In Cambodia, recent ATS use is independently associated with incident STI infection among young female sex workers (FSW). Methods: We conducted 33 in-depth interviews with women (15-29 years old) engaged in sex work to explore ATS use and vulnerability to HIV/STI. Results: Participants reported that ATS, primarily methamphetamine in pill and crystalline forms (yama), were cheap, widely available and commonly used. Yama was described as a “power drug” (thnam kamlang) which enabled women to work long hours and serve more customers. Use of ATS by clients was also common, with some providing drugs for women and/or encouraging their use, often resulting in prolonged sexual activity. Requests for unprotected sex were also more common among intoxicated clients and strategies typically employed to negotiate condom use were less effective. Conclusion: ATS use was highly functional for young women engaged in sex work, facilitating a sense of power and agency and highlighting the occupational significance and normalization of ATS in this setting. This highly gendered dynamic supports the limited but emerging literature on women's use of ATS, which to date has been heavily focused on men. Results indicate an urgent need to increase awareness of the risks associated with ATS use, to provide women with alternative and sustainable options for income generation, to better regulate the conditions of sex work, and to work with FSWs and their clients to develop and promote culturally appropriate harm reduction interventions. Keywords: sex work; amphetamine-type substances; HIV; sexually transmitted infections; risk behaviour; vulnerabilityNI

Effect of dielectric medium anisotropy on the polarization degree of emission from a single quantum dash

This research was supported by the Polish Ministry of Science and Higher Education/the National Science Center Grant No. 2011/02/A/ST3/00152. The experiments have partially been performed within the laboratory infrastructure financed by the Polish Ministry of Science and Higher Education Grant No. 6167/IA/119/2012.Excitonic emission from single InAs/InGaAlAs/InP quantum dashes has been investigated in the context of degree of linear polarization by post-growth modification of its surrounding dielectric medium. We present optical spectroscopy measurements on a symmetric squared pedestal structures (mesas), and asymmetric rectangular ones oriented parallel or perpendicular to the main in-plane axis of the dashes [1-10]. Polarization resolved microphotoluminescence shows a significant quantitative modification of the degree of linear polarization value from -20% up to 70%. These results have been confronted with calculations of the coupling between the exciton transition dipole moment and electromagnetic field distributed in the vicinity of a quantum dash inside a processed mesa.Postprin

Geriatric pharmacotherapy : optimisation through integrated approach in the hospital setting

Since older patients are more vulnerable to adverse drug-related events, there is a need to ensure appropriate prescribing in these patients in order to prevent misuse, overuse and underuse of drugs. Different tools and strategies have been developed to reduce inappropriate prescribing; the available measures can be divided into medication assessment tools, and specific interventions to reduce inappropriate prescribing. Implicit criteria of inappropriate prescribing focus on appropriate dosing, search for drug-drug interactions, and increase adherence. Explicit criteria are consensus-based standards focusing on drugs and diseases and include lists of drugs to avoid in general or lists combining drugs with clinical data. These criteria take into consideration differences between patients, and stand for a medication review, by using a systematic approach. Different types of interventions exist in order to reduce inappropriate prescribing in older patients, such as: educational interventions, computerized decision support systems, pharmacist-based interventions, and geriatric assessment. The effects of these interventions have been studied, sometimes in a multifaceted approach combining different techniques, and all types seem to have positive effects on appropriateness of prescribing. Interdisciplinary teamwork within the integrative pharmaceutical care is important for improving of outcomes and safety of drug therapy. The pharmaceutical care process consists offour steps, which are cyclic for an individual patient. These steps are pharmaceutical anamnesis, medication review, design and follow-up of a pharmaceutical care plan. A standardized approach is necessary for the adequate detection and evaluation of drug-related problems. Furthermore, it is clear that drug therapy should be reviewed in-depth, by having full access to medical records, laboratory values and nursing notes. Although clinical pharmacists perform the pharmaceutical care process to manage the patient’s drug therapy in every day clinical practice, the physician takes the ultimate responsibility for the care of the patient in close collaboration with nurses

Adaptive servo-ventilation for central sleep apnea in heart failure

Background Central sleep apnea is associated with poor prognosis and death in patients with heart failure. Adaptive servo-ventilation is a therapy that uses a noninvasive ventilator to treat central sleep apnea by delivering servo-controlled inspiratory pressure support on top of expiratory positive airway pressure. We investigated the effects of adaptive servo-ventilation in patients who had heart failure with reduced ejection fraction and predominantly central sleep apnea. Methods We randomly assigned 1325 patients with a left ventricular ejection fraction of 45% or less, an apnea–hypopnea index (AHI) of 15 or more events (occurrences of apnea or hypopnea) per hour, and a predominance of central events to receive guideline-based medical treatment with adaptive servo-ventilation or guideline-based medical treatment alone (control). The primary end point in the time-to-event analysis was the first event of death from any cause, lifesaving cardiovascular intervention (cardiac transplantation, implantation of a ventricular assist device, resuscitation after sudden cardiac arrest, or appropriate lifesaving shock), or unplanned hospitalization for worsening heart failure. Results In the adaptive servo-ventilation group, the mean AHI at 12 months was 6.6 events per hour. The incidence of the primary end point did not differ significantly between the adaptive servo-ventilation group and the control group (54.1% and 50.8%, respectively; hazard ratio, 1.13; 95% confidence interval [CI], 0.97 to 1.31; P=0.10). All-cause mortality and cardiovascular mortality were significantly higher in the adaptive servo-ventilation group than in the control group (hazard ratio for death from any cause, 1.28; 95% CI, 1.06 to 1.55; P=0.01; and hazard ratio for cardiovascular death, 1.34; 95% CI, 1.09 to 1.65; P=0.006). Conclusions Adaptive servo-ventilation had no significant effect on the primary end point in patients who had heart failure with reduced ejection fraction and predominantly central sleep apnea, but all-cause and cardiovascular mortality were both increased with this therapy. (Funded by ResMed and others; SERVE-HF ClinicalTrials.gov number, NCT00733343. opens in new tab.

Exciton lifetime and emission polarization dispersion in strongly in-plane asymmetric nanostructures

The work was supported by the Grant No. 2011/02/A/ST3/00152 from the Polish National Science Centre (Narodowe Centrum Nauki). K. G. acknowledges support by the Grant No. 2014/12/B/ST3/04603 from the Polish National Science Centre (Narodowe Centrum Nauki). S. H. acknowledges support from the State of Bavaria in Germany.We present experimental and theoretical investigation of exciton recombination dynamics and the related polarization of emission in highly in-plane asymmetric nanostructures. Considering general asymmetry- and size-driven effects, we illustrate them with a detailed analysis of InAs/AlGaInAs/InP elongated quantum dots. These offer a widely varied confinement characteristics tuned by size and geometry that are tailored during the growth process, which leads to emission in the application-relevant spectral range of 1.25-1.65 μm. By exploring the interplay of the very shallow hole confining potential and widely varying structural asymmetry, we show that a transition from the strong through intermediate to even weak confinement regime is possible in nanostructures of this kind. This has a significant impact on exciton recombination dynamics and the polarization of emission, which are shown to depend not only on details of the calculated excitonic states but also on excitation conditions in the photoluminescence experiments. We estimate the impact of the latter and propose a way to determine the intrinsic polarization-dependent exciton light-matter coupling based on kinetic characteristics.PostprintPeer reviewe

Selling sex in unsafe spaces: Sex work risk environments in Phnom Penh, Cambodia

Background The risk environment framework provides a valuable but under-utilised heuristic for understanding environmental vulnerability to HIV and other sexually transmitted infections among female sex workers. Brothels have been shown to be safer than street-based sex work, with higher rates of consistent condom use and lower HIV prevalence. While entertainment venues are also assumed to be safer than street-based sex work, few studies have examined environmental influences on vulnerability to HIV in this context. Methods As part of the Young Women's Health Study, a prospective observational study of young women (15-29 years) engaged in sex work in Phnom Penh, we conducted in-depth interviews (n = 33) to explore vulnerability to HIV/STI and related harms. Interviews were conducted in Khmer by trained interviewers, transcribed and translated into English and analysed for thematic content. Results The intensification of anti-prostitution and anti-trafficking efforts in Cambodia has increased the number of women working in entertainment venues and on the street. Our results confirm that street-based sex work places women at risk of HIV/STI infection and identify significant environmental risks related to entertainment-based sex work, including limited access to condoms and alcohol-related intoxication. Our data also indicate that exposure to violence and interactions with the police are mediated by the settings in which sex is sold. In particular, transacting sex in environments such as guest houses where there is little or no oversight in the form of peer or managerial support or protection, may increase vulnerability to HIV/STI. Conclusions Entertainment venues may also provide a high risk environment for sex work. Our results indicate that strategies designed to address HIV prevention among brothel-based FSWs in Cambodia have not translated well to street and entertainment-based sex work venues in which increasing numbers of women are working. There is an urgent need for targeted interventions, supported by legal and policy reforms, designed to reduce the environmental risks of sex work in these settings. Future research should seek to investigate sex work venues as risk environments, explore the role of different business models in mediating these environments, and identify and quantify exposure to risk in different occupational settings. Keywords: sex work; risk; environment; vulnerability; HIV; STI; young women; entertainment; Cambodi

Coalition unionism : exploring how and when coalitions contribute to union renewal in Sydney, Toronto and Chicago

Item does not contain fulltextWe have previously identified eight novel autoantibody targets in the cerebrospinal fluid of multiple sclerosis (MS) patients, including sperm-associated Ag 16 (SPAG16). In the current study, we further investigated the autoantibody response against SPAG16-a protein with unknown function in the CNS-and its expression in MS pathology. Using isoelectric focusing, we detected SPAG16-specific oligoclonal bands in the cerebrospinal fluid of 5 of 23 MS patients (22%). Analysis of the anti-SPAG16 Ab reactivity in the plasma of a total of 531 donors using ELISA demonstrated significantly elevated anti-SPAG16 Ab levels (p = 0.002) in 32 of 153 MS patients (21%) compared with all other control groups with 95% specificity for the disease. To investigate the pathologic relevance of anti-SPAG16 Abs in vivo, anti-SPAG16 Abs were injected in mice with experimental autoimmune encephalomyelitis, resulting in a significant disease exacerbation. Finally, we demonstrated a consistent upregulation of SPAG16 in MS brain and experimental autoimmune encephalomyelitis spinal cord lesions, more specifically in reactive astrocytes. We conclude that SPAG16 is a novel autoantibody target in a subgroup of MS patients and in combination with other diagnostic criteria, elevated levels of anti-SPAG16 Abs could be used as a biomarker for diagnosis. Furthermore, the pathologic relevance of anti-SPAG16 Abs was shown in vivo