Electrical Spin Pumping of Quantum Dots at Room Temperature

We report electrical control of the spin polarization of InAs/GaAs self-assembled quantum dots (QDs) at room temperature. This is achieved by electrical injection of spin-polarized electrons from an Fe Schottky contact. The circular polarization of the QD electroluminescence shows that a 5% electron spin polarization is obtained in the InAs QDs at 300 K, which is remarkably insensitive to temperature. This is attributed to suppression of the spin relaxation mechanisms in the QDs due to reduced dimensionality. These results demonstrate that practical regimes of spin-based operation are clearly attainable in solid state semiconductor devices.Comment: 4 figures, accepted by Appl. Phys. Let

A jump-growth model for predator-prey dynamics: derivation and application to marine ecosystems

This paper investigates the dynamics of biomass in a marine ecosystem. A stochastic process is defined in which organisms undergo jumps in body size as they catch and eat smaller organisms. Using a systematic expansion of the master equation, we derive a deterministic equation for the macroscopic dynamics, which we call the deterministic jump-growth equation, and a linear Fokker-Planck equation for the stochastic fluctuations. The McKendrick--von Foerster equation, used in previous studies, is shown to be a first-order approximation, appropriate in equilibrium systems where predators are much larger than their prey. The model has a power-law steady state consistent with the approximate constancy of mass density in logarithmic intervals of body mass often observed in marine ecosystems. The behaviours of the stochastic process, the deterministic jump-growth equation and the McKendrick--von Foerster equation are compared using numerical methods. The numerical analysis shows two classes of attractors: steady states and travelling waves.Comment: 27 pages, 4 figures. Final version as published. Only minor change

Border skirmishes and the question of belonging: An authoethnographic account of everyday exclusion in multicultural society

Transnational migration has transformed most European countries, making the problem of how to 'integrate' an increasingly popular topic in public debates and social policy. It is assumed that as long as the newcomer learns the language, adapts to the local customs and finds work, s/he will be integrated and welcomed with open arms as a full-fledged member of society. Based on an autoethnography of our experiences as US-born, long-term and fully 'integrated' residents of the Netherlands, one of Europe's most multicultural societies, we have explored some of the subtle, well-intentioned practices of distancing and exclusion that are part of the fabric of everyday life. We will show how, contrary to the official discourse of integration, 'Dutch-ness' as a white/ethnic national identity is continuously constructed as a 'we', which excludes all 'others'. And, indeed, we have discovered that, paradoxically, the closer the 'other' comes to being completely assimilated into Dutch society, the more the symbolic borders of national belonging may need to be policed and tightened. © The Author(s) 2011

How community ART delivery may improve HIV treatment outcomes: Qualitative inquiry into mechanisms of effect in a randomized trial of community-based ART initiation, monitoring and re-supply (DO ART) in South Africa and Uganda

INTRODUCTION: UNAIDS fast track targets for ending the AIDS epidemic by 2030 call for viral suppression in 95% of people using antiretroviral therapy (ART) to treat HIV infection. Difficulties in linking to care following a positive HIV test have impeded progress towards meeting treatment targets. Community-based HIV services may reduce linkage barriers and have been associated with high retention and favourable clinical outcomes. We use qualitative data from The Delivery Optimization of Antiretroviral Therapy (DO ART) Study, a three-arm randomized trial of community ART initiation, monitoring and re-supply conducted in western Uganda and KwaZulu-Natal South Africa, to identify mechanisms through which community ART delivery may improve treatment outcomes, defined as viral suppression in people living with HIV (PLHIV). METHODS: We conducted open-ended interviews with a purposeful sample of 150 DO ART participants across study arms and study sites, from October 2016 to November 2019. Interviews covered experiences of: (1) HIV testing; (2) initiating and refilling ART; and (3) participating in the DO ART Study. A combined inductive content analytic and thematic approach was used to characterize mechanisms through which community delivery of ART may have contributed to viral suppression in the DO ART trial. RESULTS: The analysis yielded four potential mechanisms drawn from qualitative data representing the perspectives and priorities of DO ART participants. Empowering participants to schedule, re-schedule and select the locations of community-based visits via easy phone contact with clinical staff is characterized as flexibility. Integration refers to combining the components of clinic-based visits into single interaction with a healthcare provider. Providers" willingness to talk at length with participants during visits, addressing non-HIV as well as HIV-related concerns, is termed "a slower pace". Finally, increased efficiency denotes the time savings and increased income-generating opportunities for participants brought about by delivering services in the community. CONCLUSIONS: Understanding the mechanisms through which HIV service delivery innovations produce an effect is key to transferability and potential scale-up. The perspectives and priorities of PLHIV can indicate actionable changes for HIV care programs that may increase engagement in care and improve treatment outcomes

Limits on Gravitational-Wave Emission from Selected Pulsars Using LIGO Data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10^(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10^(-5) for the four closest pulsars

Health-related quality of life in patients with surgically treated lumbar disc herniation: 2- and 7-year follow-up of 117 patients

To access publisher full text version of this article. Please click on the hyperlink in Additional Links field.BACKGROUND AND PURPOSE: Health-related quality of life (HRQoL) instruments have been of increasing interest for evaluation of medical treatments over the past 10-15 years. In this prospective, long-term follow-up study we investigated the influence of preoperative factors and the change in HRQoL over time after lumbar disc herniation surgery. METHODS: 117 patients surgically treated for lumbar disc herniation (L4-L5 or L5-S1) were evaluated with a self-completion HRQoL instrument (EQ-5D) preoperatively, after 2 years (96 patients) and after 7 years (89 patients). Baseline data (age, sex, duration of leg pain, surgical level) and degree of leg and back pain (VAS) were obtained preoperatively. The mean age was 39 (18-66) years, 54% were men, and the surgical level was L5-S1 in 58% of the patients. The change in EQ-5D score at the 2-year follow-up was analyzed by testing for correlation and by using a multiple regression model including all baseline factors (age, sex, duration of pain, degree of leg and back pain, and baseline EQ-5D score) as potential predictors. RESULTS: 85% of the patients reported improvement in EQ-5D two years after surgery and this result remained at the long-term follow-up. The mean difference (change) between the preoperative EQ-5D score and the 2-year and 7-year scores was 0.59 (p < 0.001) and 0.62 (p < 0.001), respectively. However, the HRQoL for this patient group did not reach the mean level of previously reported values for a normal population of the same age range at any of the follow-ups. The changes in EQ-5D score between the 2- and 7-year follow-ups were not statistically significant (mean change 0.03, p = 0.2). There was a correlation between baseline leg pain and the change in EQ-5D at the 2-year (r = 0.33, p = 0.002) and 7-year follow-up (r = 0.23, p = 0.04). However, when using regression analysis the only statistically significant predictor for change in EQ-5D was baseline EQ-5D score. INTERPRETATION: Our findings suggest that HRQoL (as measured by EQ-5D) improved 2 years after lumbar disc herniation surgery, but there was no further improvement after 5 more years. Low quality of life and severe leg pain at baseline are important predictors of improvement in quality of life after lumbar disc herniation surgery.Marianne och Marcus Wallenberg Foundation ALF Vastra Gotaland. Gothenburg Medical Association. Swedish Society of Medicine. Felix Neubergh Foundation

Developing a digital intervention for cancer survivors: an evidence-, theory- and person-based approach

This paper illustrates a rigorous approach to developing digital interventions using an evidence-, theory- and person-based approach. Intervention planning included a rapid scoping review which identified cancer survivors’ needs, including barriers and facilitators to intervention success. Review evidence (N=49 papers) informed the intervention’s Guiding Principles, theory-based behavioural analysis and logic model. The intervention was optimised based on feedback on a prototype intervention through interviews (N=96) with cancer survivors and focus groups with NHS staff and cancer charity workers (N=31). Interviews with cancer survivors highlighted barriers to engagement, such as concerns about physical activity worsening fatigue. Focus groups highlighted concerns about support appointment length and how to support distressed participants. Feedback informed intervention modifications, to maximise acceptability, feasibility and likelihood of behaviour change. Our systematic method for understanding user views enabled us to anticipate and address important barriers to engagement. This methodology may be useful to others developing digital interventions

First upper limits from LIGO on gravitational wave bursts

We report on a search for gravitational wave bursts using data from the first science run of the LIGO detectors. Our search focuses on bursts with durations ranging from 4 ms to 100 ms, and with significant power in the LIGO sensitivity band of 150 to 3000 Hz. We bound the rate for such detected bursts at less than 1.6 events per day at 90% confidence level. This result is interpreted in terms of the detection efficiency for ad hoc waveforms (Gaussians and sine-Gaussians) as a function of their root-sum-square strain h_{rss}; typical sensitivities lie in the range h_{rss} ~ 10^{-19} - 10^{-17} strain/rtHz, depending on waveform. We discuss improvements in the search method that will be applied to future science data from LIGO and other gravitational wave detectors.Comment: 21 pages, 15 figures, accepted by Phys Rev D. Fixed a few small typos and updated a few reference

Analysis of LIGO data for gravitational waves from binary neutron stars

We report on a search for gravitational waves from coalescing compact binary systems in the Milky Way and the Magellanic Clouds. The analysis uses data taken by two of the three LIGO interferometers during the first LIGO science run and illustrates a method of setting upper limits on inspiral event rates using interferometer data. The analysis pipeline is described with particular attention to data selection and coincidence between the two interferometers. We establish an observational upper limit of $\mathcal{R}<$1.7 \times 10^{2}$per year per Milky Way Equivalent Galaxy (MWEG), with 90coalescence rate of binary systems in which each component has a mass in the range 1--3$M_\odot$.Comment: 17 pages, 9 figure

Searching for gravitational waves from known pulsars

We present upper limits on the amplitude of gravitational waves from 28 isolated pulsars using data from the second science run of LIGO. The results are also expressed as a constraint on the pulsars' equatorial ellipticities. We discuss a new way of presenting such ellipticity upper limits that takes account of the uncertainties of the pulsar moment of inertia. We also extend our previous method to search for known pulsars in binary systems, of which there are about 80 in the sensitive frequency range of LIGO and GEO 600.Comment: Accepted by CQG for the proceeding of GWDAW9, 7 pages, 2 figure