Design approaches and materials processes for ultrahigh efficiency lattice mismatched multi-junction solar cells

In this study, we report synthesis of large area (>2cm^2), crack-free GaAs and GaInP double heterostructures grown in a multi-junction solar cell-like structure by MOCVD. Initial solar cell data are also reported for GaInP top cells. These samples were grown on Ge/Si templates fabricated using wafer bonding and ion implantation induced layer transfer techniques. The double heterostructures exhibit radiative emission with uniform intensity and wavelength in regions not containing interfacial bubble defects. The minority carrier lifetime of ~1ns was estimated from photoluminescence decay measurements in both double heterostructures. We also report on the structural characteristics of heterostructures, determined via atomic force microscopy and transmission electron microscopy, and correlate these characteristics to the spatial variation of the minority carrier lifetime

Endothelial preconditioning by transient oxidative stress reduces inflammatory responses of cultured endothelial cells to TNF-α

Brief episodes of ischemia can render an organ resistant to subsequent severe ischemia. This ‘ischemic preconditioning’ is ascribed to various mechanisms, including oxidative stress. We investigated whether preconditioning exists on an endothelial level. Human umbilical vein endothelial cells (HUVECs) were transiently confronted with oxidative stress (1 mM H2O2, 5 min). Adhesion molecules ICAM-1 and E-selectin and release of cytokines IL-6 and IL-8 to subsequent stimulation with TNF-α (2.5 ng/ml, 4 h) were measured (flow cytometry and immunoassay), as were nuclear translocation of the transcription factor NFkB (Western blotting, confocal microscopy) and redox status of HUVECs (quantification of glutathione by HPLC). TNF-α elevated IL-6 in the cell supernatant from 8.8 ± 1 to 41 ± 3 pg/ml and IL-8 from 0.5 ± 0.03 to 3 ± 0.2 ng/ml. ICAM-1 was increased threefold and E-selectin rose eightfold. Oxidative stress (decrease of glutathione by 50%) reduced post-TNF-α levels of IL-6 to 14 ± 3 and IL-8 to 1 ± 0.2; the rise of ICAM-1 was completely blocked and E-selectin was only doubled. The anti-inflammatory effects of preconditioning via oxidative stress were paralleled by reduction of the translocation of NFkB on stimulation with TNF-α, and antagonized by the intracellular radical scavenger N-acetylcysteine. ‘Anti-inflammatory preconditioning’ of endothelial cells by oxidative stress may account for the inhibitory effects of preconditioning on leukocyte adhesion in vivo

Community-Based User Experience: Evaluating the Usability of Health Insurance Information With Immigrant Patients

User experience (UX), a common practice in corporate settings, is new for many nonprofit organizations. This case study details a community-based research project between nonprofit staff at a community health center and UX professionals to improve the design and usability of a document designed to help immigrant patients sign up for health insurance. UX professionals may need to adapt and be flexible with their efforts, but can offer valuable skills to community partners. Research questions: (1) What are the information needs and barriers faced by immigrant populations signing up for health insurance? (2) How does a usability study, adapted to meet the needs of immigrant populations, inform the design of a supplemental guidebook about health insurance? (3) What are the challenges and opportunities when engaging in community-based UX research projects? Situating the case: Other community-based research projects in technical communication and UX point to the need for a clear conceptualization of participation, a strong partnership with nonprofits, and the need to develop meaningful and actionable insights. Furthermore, when conducting studies with immigrant populations, the role of the translator on the research team is crucial. Methodology: As a community-based research project focused on the collaborative generation of practical knowledge, we conducted a usability study with 12 participants in two language groups, Chinese and Vietnamese, to evaluate the design and usability of a guidebook designed to provide guidance about enrolling in a health insurance plan. Data were analyzed to identify usability concerns and used to inform a second iteration of the guidebook. About the case: Immigrant populations struggle to sign up for health insurance for a variety of reasons, including limited English and health insurance literacy. As a result, a nonprofit community health center developed a guidebook to support immigrant populations. Version 1 of this guidebook was evaluat- d in a usability study, with results showing that users struggled to correctly choose a plan, determine their eligibility, and interpret abstract examples. As a result, Version 2 was designed to support the in-person experience, reduce visual complexity, and support patients\u27 key questions. Conclusions: Community-based UX collaborations can amplify the expertise of UX and nonprofit professionals. However, UX methods may need to be adapted in community-based projects to better incorporate local knowledge and needs

Macroeconomic stability and investment allocation of domestic pension funds in emerging economies: the case of Chile

Includes bibliograph

Investigation of catalysis by bacterial RNase P via LNA and other modifications at the scissile phosphodiester

We analyzed cleavage of precursor tRNAs with an LNA, 2′-OCH3, 2′-H or 2′-F modification at the canonical (c0) site by bacterial RNase P. We infer that the major function of the 2′-substituent at nt −1 during substrate ground state binding is to accept an H-bond. Cleavage of the LNA substrate at the c0 site by Escherichia coli RNase P RNA demonstrated that the transition state for cleavage can in principle be achieved with a locked C3′ -endo ribose and without the H-bond donor function of the 2′-substituent. LNA and 2′-OCH3 suppressed processing at the major aberrant m−1 site; instead, the m+1 (nt +1/+2) site was utilized. For the LNA variant, parallel pathways leading to cleavage at the c0 and m+1 sites had different pH profiles, with a higher Mg2+ requirement for c0 versus m+1 cleavage. The strong catalytic defect for LNA and 2′-OCH3 supports a model where the extra methylene (LNA) or methyl group (2′-OCH3) causes a steric interference with a nearby bound catalytic Mg2+ during its recoordination on the way to the transition state for cleavage. The presence of the protein cofactor suppressed the ground state binding defects, but not the catalytic defects

Preparation and control of a cavity-field state through atom-driven field interaction: towards long-lived mesoscopic states

The preparation of mesoscopic states of the radiation and matter fields through atom-field interactions has been achieved in recent years and employed for a range of striking applications in quantum optics. Here we present a technique for the preparation and control of a cavity mode which, besides interacting with a two-level atom, is simultaneously submitted to linear and parametric amplification processes. The role of the amplification-controlling fields in the achievement of real mesoscopic states, is to produce highly-squeezed field states and, consequently, to increase both: i) the distance in phase space between the components of the prepared superpositions and ii) the mean photon number of such superpositions. When submitting the squeezed superposition states to the action of similarly squeezed reservoirs, we demonstrate that under specific conditions the decoherence time of the states becomes independent of both the distance in phase space between their components and their mean photon number. An explanation is presented to support this remarkable result, together with a discussion on the experimental implementation of our proposal. We also show how to produce number states with fidelities higher than those derived as circular states

A previously unidentified Chorioptes species infesting outer ear canals of moose (Alces alces): characterization of the mite and the pathology of infestation

<p>Abstract</p> <p>Background</p> <p>During the past decade, <it>Chorioptes </it>mites occupying the outer ear canals have been a common finding at routine necropsies of moose (<it>Alces alces</it>) in Sweden, but neither the taxonomy of the mites nor lesions from the infestation have been investigated. In this study, the mites are characterized by morphological and molecular techniques, and the histopathology of the skin of the outer ear canal is described.</p> <p>Methods</p> <p>External auditory meatuses from 53 necropsied moose were examined for the presence of <it>Chorioptes</it>, and samples from outer ear canals were taken for histopathological and microbiological examination. A proportion of the mites from each moose was identified to species. The DNA was extracted from mites from three moose, and their ITS-2 sequences were determined; these sequences were compared phylogenetically to sequences from other <it>Chorioptes </it>taxa.</p> <p>Results</p> <p><it>Chorioptes </it>mites were found in 43 (81%) of the 53 moose. The mites had morphological and genetic characteristics distinct from those of <it>C. texanus </it>and <it>C. bovis</it>, the two species generally accepted within the genus. Morphology also did not argue for a diagnosis as <it>C. crewei</it>, <it>C. mydaus </it>or <it>C. panda</it>. On histopathology, lesions were characterized by a hyperplastic perivascular to interstitial dermatitis with epidermal hyperkeratosis and crust formation. Dermal inflammatory infiltrates were composed of mixed T- and B-lymphocytes, plasma cells and macrophages, whereas eosinophils were notably uncommon. <it>Staphylococcus aureus </it>was grown from the infested epidermis of five of 14 examined moose.</p> <p>Conclusion</p> <p><it>Chorioptes </it>mite infestation was frequently detected in the outer ear canals of moose in Sweden. The mites were evidently pathogenic, being associated with inflammatory lesions of the external auditory meatus. Our studies indicate infestations with a previously undescribed <it>Chorioptes </it>species.</p

Management of Mongolian gazelles as a sustainable resource

An international workshop on gazelle harvesting and management was held in Ulaanbaatar, Mongolia, in October, 2003. The major output from this workshop was the general agreement that no commercial hunt can be recommended at this time. This is because of the high level of poaching that is appearing to be having a negative impact on gazelle numbers. Best estimates put the existing gazelle population at about one million and decreasing. Models have suggested that this population could sustain an annual 6% commercial offtake. However, it is estimated that the illegal offtake may be near or exceed 10% annually. If so, this would explain why the population of gazelles is decreasing even without a legal commercial hunt. While there are adequate laws to deal with poaching, there is extremely poor enforcement due to a lack of funding, equipment, and will. We recommend against a commercial harvest until poaching is controlled, and there is a sound monitoring system in place, and until monitoring shows gazelle populations to be stable or increasing