Hybrid Quantum Dot-2D Electron Gas Devices for Coherent Optoelectronics

We present an inverted GaAs 2D electron gas with self-assembled InAs quantum dots in close proximity, with the goal of combining quantum transport with quantum optics experiments. We have grown and characterized several wafers -- using transport, AFM and optics -- finding narrow-linewidth optical dots and high-mobility, single subband 2D gases. Despite being buried 500 nm below the surface, the dots are clearly visible on AFM scans, allowing precise localization and paving the way towards a hybrid quantum system integrating optical dots with surface gate-defined nanostructures in the 2D gas.Comment: 4 pages, 5 figures (color

Impedance model for the polarization-dependent optical absorption of superconducting single-photon detectors

We measured the single-photon detection efficiency of NbN superconducting single photon detectors as a function of the polarization state of the incident light for different wavelengths in the range from 488 nm to 1550 nm. The polarization contrast varies from ~5% at 488 nm to ~30% at 1550 nm, in good agreement with numerical calculations. We use an optical-impedance model to describe the absorption for polarization parallel to the wires of the detector. For lossy NbN films, the absorption can be kept constant by keeping the product of layer thickness and filling factor constant. As a consequence, we find that the maximum possible absorption is independent of filling factor. By illuminating the detector through the substrate, an absorption efficiency of ~70% can be reached for a detector on Si or GaAs, without the need for an optical cavity.Comment: 15 pages, 5 figures, submitted to Journal of Applied Physic

Quantum physics meets biology

Quantum physics and biology have long been regarded as unrelated disciplines, describing nature at the inanimate microlevel on the one hand and living species on the other hand. Over the last decades the life sciences have succeeded in providing ever more and refined explanations of macroscopic phenomena that were based on an improved understanding of molecular structures and mechanisms. Simultaneously, quantum physics, originally rooted in a world view of quantum coherences, entanglement and other non-classical effects, has been heading towards systems of increasing complexity. The present perspective article shall serve as a pedestrian guide to the growing interconnections between the two fields. We recapitulate the generic and sometimes unintuitive characteristics of quantum physics and point to a number of applications in the life sciences. We discuss our criteria for a future quantum biology, its current status, recent experimental progress and also the restrictions that nature imposes on bold extrapolations of quantum theory to macroscopic phenomena.Comment: 26 pages, 4 figures, Perspective article for the HFSP Journa

Home birth and barriers to referring women with obstetric complications to hospitals: a mixed-methods study in Zahedan, southeastern Iran

<p>Abstract</p> <p>Background</p> <p>One factor that contributes to high maternal mortality in developing countries is the delayed use of Emergency Obstetric-Care (EmOC) facilities. The objective of this study was to determine the factors that hinder midwives and parturient women from using hospitals when complications occur during home birth in Sistan and Baluchestan province, Iran, where 23% of all deliveries take place in non- hospital settings.</p> <p>Methods</p> <p>In the study and data management, a mixed-methods approach was used. In the quantitative phase, we compared the existing health-sector data with World Health Organization (WHO) standards for the availability and use of EmOC services. The qualitative phase included collection and analysis of interviews with midwives and traditional birth attendants and twenty-one in-depth interviews with mothers. The data collected in this phase were managed according to the principles of qualitative data analysis.</p> <p>Results</p> <p>The findings demonstrate that three distinct factors lead to indecisiveness and delay in the use of EmOC by the midwives and mothers studied. Socio-cultural and familial reasons compel some women to choose to give birth at home and to hesitate seeking professional emergency care for delivery complications. Apprehension about being insulted by physicians, the necessity of protecting their professional integrity in front of patients and an inability to persuade their patients lead to an over-insistence by midwives on completing deliveries at the mothers' homes and a reluctance to refer their patients to hospitals. The low quality and expense of EmOC and the mothers' lack of health insurance also contribute to delays in referral.</p> <p>Conclusions</p> <p>Women who choose to give birth at home accept the risk that complications may arise. Training midwives and persuading mothers and significant others who make decisions about the value of referring women to hospitals at the onset of life-threatening complications are central factors to increasing the use of available hospitals. The hospitals must be safe, comfortable and attractive environments for parturition and should give appropriate consideration to the ethical and cultural concerns of the women. Appropriate management of financial and insurance-related issues can help midwives and mothers make a rational decision when complications arise.</p

Tenure, gender and household structure

Starting with a review of recent literature on gender and housing, this paper goes on to develop a new theory of household structure, in which concepts of gender and generation play a key role. The utility of this theory is then demonstrated in the analysis of data from a survey of households in the City of Salford

Evidence-Based Security in Aerospace: From Safety to Security and Back Again

Security concerns of safety-critical systems increase due to interconnections of systems. This paper tries to outline future security requirements in avionics and issues in assessing the reliability of software from the safety and security perspective. Quantitative work on software reliability has focused on requirements-to-code translation; software security has focused more on requirements correctness. Future work must take advantage of results from both the security and safety areas

Microrganismos associados a frutos de diferentes cultivares de noz Pecan Microorganisms associated with fruits of different cultivars of Pecan nut

O conhecimento do comportamento natural da nogueira Pecan às principais doenças é de suma importância para o estabelecimento do planejamento da implantação da cultura. O controle fitossanitário e tratos culturais devem ser realizados de modo a não comprometerem a qualidade do produto final, as amêndoas. Foram avaliadas nozes produzidas na safra de 2005 e oriundas de Uraí-PR, pelas cultivares Burkett, Frotscher e Moneymaker, para identificar e quantificar os microrganismos associados à amêndoas e cascas dos frutos, bem como observar diferenças entre organismos colonizadores das cultivares. Os frutos foram avaliados na pós-colheita, aos trinta dias de armazenamento em ambiente, através da metodologia do papel de filtro, sendo submetidos ou não à assepsia superficial. O fungo Cladosporium caryigenum, promotor da rancificação das amêndoas foi observado, em amêndoas e cascas, nas cultivares Burkett, Frotscher e Moneymaker; Fusarium sp., foi encontrado em porcentuais elevados, tanto em amêndoas quanto em cascas das três cultivares estudadas; Cephalothecium roseum, causador do mofo róseo em amêndoas, na cultivar Frotscher. Aspergillus sp. e Penicillium sp., causadores de emboloramento e produtores de aflotoxinas foram observados em porcentuais representativos, em amêndoas da cultivar Frotscher e em amêndoas e cascas das cultivares Frotscher, Burkett e Moneymaker, respectivamente. Os maiores porcentuais de perda do rendimento foram observados na cultivar Burkett, por causa da incidência de Colletotrichum sp., causador da antracnose em amêndoas, que acarreta escurecimento e deterioração do produto final, levando-o ao descarte.<br>The knowledgement of the natural behavior of the main diseases of Pecan nut is of utmost importance for the stablishment of an implantation plan for that culture. The phytosanitary control and cultural treatments should be performed in order not to change the quality of the final product. Nuts harvest in 2005 from Uraí-PR of Burkett, Frotscher and Moneymaker cultivars, were evaluated in order to identify and quantify associated microorganisms in the nuts and fruit cover, as well to observe the differences among the microorganisms that colonize the different cultivars. The fruits were evaluated at post-harvest, thirty days kept in natural temperature, through filter paper method, being submitted or not to surface assepsy. The fungi Cladosporium caryigenum, rancification promoter to the almonds was observed on almonds and covers on the cultivars Burkett, Frotscher and Moneymaker; Fusarium sp., was observed in high concentration, on almonds as well as on the cover of all the studied cultivars; Cephalothecium roseum, responsible for the pink mildew, in almonds in the Frotscher cultivar. Aspergillus sp. and Penicillium sp., responsible for mold and aflatoxins formation, were observed in high amount on almonds of the Frotscher cultivar and in almonds and cover of Frotscher, Burkett and Moneymaker, respectively. The highest percentage of loss in yield was observed on the Burkett cultivar, cause of the incidence of Colletotrichum sp., agent responsible for antracnosis on the almonds which provokes causer darkness and deterioration of final product, leading it to discarding