568 research outputs found

    Blocking contacts for N-type cadmium zinc telluride

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    A process for applying blocking contacts on an n-type CdZnTe specimen includes cleaning the CdZnTe specimen; etching the CdZnTe specimen; chemically surface treating the CdZnTe specimen; and depositing blocking metal on at least one of a cathode surface and an anode surface of the CdZnTe specimen

    Long-term Reconstruction and Analysis of White River Streamflow

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    A 281-year reconstruction of White River annual runoff at Clarendon, Arkansas, was developed from a regional average of nine Oklahoma, Missouri, and Arkansas tree-ring chronologies (six post oak, Quercus stellata, and three baldcypress, Taxodium distichum). Inhomogeneity of the gaged series was detected with both double mass analysis (using state average total annual Arkansas precipitation) and regression (using the regional tree-ring average). Simple regression calibrated the homogeneous runoff data with the average ring width data from 1930 to 1980. Comparing the reconstruction with independent data verified the regression model. Variance of the reconstruction increases significantly during the 20th century, a change that may be caused by climatic shifts or by anthropogenic disturbances in the watershed. Years of surplus and deficit runoff are non-randomly distributed in both gaged and reconstructed series. This non-randomness appears to be caused by a significant tendency for inter-annual persistence of runoff extremes, which may provide a basis for improvement of probabilistic forecasts of White River runoff

    Bias Selectable Dual Band AlGaN Ultra-violet Detectors

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    Bias selectable dual band AlGaN ultra-violet (UV) detectors, which can separate UV-A and UV-B using one detector in the same pixel by bias switching, have been designed, fabricated and characterized. A two-terminal n-p-n photo-transistor-like structure was used. When a forward bias is applied between the top electrode and the bottom electrode, the detectors can successfully detect W-A and reject UV-B. Under reverse bias, they can detect UV-B and reject UV-A. The proof of concept design shows that it is feasible to fabricate high performance dual-band UV detectors based on the current AlGaN material growth and fabrication technologies

    AlGaN Ultraviolet Detectors for Dual-Band UV Detection

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    This innovation comprises technology that has the ability to measure at least two ultraviolet (UV) bands using one detector without relying on any external optical filters. This allows users to build a miniature UVA and UVB monitor, as well as to develop compact, multicolor imaging technologies for flame temperature sensing, air-quality control, and terrestrial/counter-camouflage/biosensing applications

    Disease activity in and quality of life of patients with psoriatic arthritis mutilans : the Nordic PAM Study

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    Objective: To describe the social status and health-related quality of life of patients with psoriatic arthritis mutilans (PAM) in the Nordic countries.Method: Patients with at least one mutilated joint confirmed by radiology were studied. Disease activity involving joints and skin, physician-assessed disease activity, and patient's education and work status were recorded. Data from the 36-item Short Form Health Survey, Health Assessment Questionnaire and Dermatology Life Quality Index questionnaire were gathered and correlated with disease duration, pain, and general well-being (visual analogue scale). The controls were 58 Swedish patients with long-standing psoriatic arthritis sine PAM.Results: Sixty-seven patients were included. Patients with PAM had a protracted disease history (3314years) and disease onset at a relatively early age (30 +/- 12years). Overall inflammatory activity at inclusion was mild to moderate. The mean number of mutilated joints was 8.2 and gross deformity was found in 16% of patients. Forty per cent were treated with biological and 32% with conventional synthetic disease-modifying anti-rheumatic drugs. Forty-two per cent had retired early or were on sick leave. Impaired functional capacity with little or no ability to perform self-care or everyday tasks was reported by 21% of the patients. Patients between 45 and 60years of age reported the most impaired quality of life in comparison to the control group.Conclusion: PAM seriously affects social functioning. Whether early recognition of PAM and new forms of therapy can improve disease outcome and quality of life remains to be studied.Peer reviewe

    Intentional and unintentional medication nonadherence in psoriasis: the role of patients’ medication beliefs and habit strength [abstract only]

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    The accurate diagnosis of psoriasis has remained a challenge, as no disease-specific biomarkers have yet been identified. Currently, the diagnosis of chronic inflammatory diseases relies mainly on the assessment of visible symptoms or the histological features of the biopsy. This approach is heavily reliant on the experience of the clinician and, therefore, may lead to misdiagnosis as there are numerous different chronic inflammatory skin diseases that may present similar clinical features. Hence, the need for diagnostic biomarkers is clear. Although different investigations have reported the discovery of potential psoriasis biomarkers, still no accurate and reliable biomarker is available. Rather than searching for a single valid biomarker, we propose that applying a multicomponent bio-marker-based approach would result in a higher degree of success and translation into clinical practice. An extensive review of published studies to identify the most relevant psoriasis-specific biomarker candidates was conducted. This led us to conclude that the expression levels of specific genes in the skin hold the most promise as discriminatory biomarkers, resulting in the selection of five genes, the expression levels of which have been demonstrated to be exclusive for psoriasis vulgaris. We first conducted a preliminary validation study applying support vector machine-based classification and principle component analysis on the skin-derived expression data of 12 patients with psoriasis vulgaris and 12 healthy controls, previously produced in our departments. We then confirmed that the expression levels of the five genes in psoriatic lesions indeed present a unique pattern. Encouraged by these results, we continued to develop a quantitative polymerase chain reaction panel to allow the accurate measurement of expression levels for the five genes to be used in the studies to follow. Although we have yet to confirm these results in the context of other chronic inflammatory skin diseases, the results of previously published studies regarding these five genes are promising. Therefore, we are in the process of collecting additional skin samples from patients with chronic inflammatory disease (including different papulosquamous disorders and atopic dermatitis) to validate the discriminatory power of our panel. These results may further be translated to viable clinical diagnostic tests in the near future. This work was supported by the ERA Chair for Translational Genomics and Personalized Medicine at the University of Tartu

    Development of Ultra-High Sensivity Silicon Carbide Detectors

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    A variety of silicon carbide (SiC) detectors have been developed to study the sensitivity of SiC ultraviolet (UV) detectors, including Schottky photodiodes, p-i-n photodiodes, avalanche photodiodes (APDs), and single photon-counting APDs. Due to the very wide bandgap and thus extremely low leakage current, Sic photo-detectors showed excellent sensitivity. The specific detectivity, D*, of SiC photodiodes are orders of magnitude higher than that of their competitors, such as Si photodiodes, and comparable to the D* of photomultiplier tubes (PMTs). To pursue the ultimate detection sensitivity, SiC APDs and single photon-counting avalanche diodes (SPADs) have also been fabricated. By operating the SiC APDs at a linear mode gain over 10(exp 6), SPADs in UV have been demonstrated. SiC UV detectors have great potential for use in solar blind UV detection and biosensing. Moreover, SiC detectors have excellent radiation hardness and high temperature tolerance which makes them ideal for extreme environment applications such as in space or on the surface of the Moon or Mars

    Pre-instrumental perspectives on Arkansas River cross-watershed flow variability

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    We present four reconstruction estimates of Arkansas River baseflow and streamflow using a total of 78 tree-ring chronologies for three streamflow gages, geographically spanning the headwaters in Colorado to near the confluence of the Arkansas-Mississippi rivers. The estimates represent different seasonal windows, which are dictated by the shared limiting forcing of precipitation on seasonal tree growth and soil moisture—and subsequently on the variability of Arkansas River discharge. Flow extremes that were higher and lower than what has been observed in the instrumental era are recorded in each of the four reconstructions. Years of concurrent, cross-basin (all sites) low flow appear more frequently during the 20th and 21st Centuries compared to any period since 1600 A.D., however, no significant trend in cross-basin low flow is observed. As the most downstream major tributary of the Mississippi River, the Arkansas River directly influences flood risk in the Lower Mississippi River Valley. Estimates of extreme high flow in downstream reconstructions coincide with specific years of historic flooding documented in New Orleans, Louisiana, just upstream of the Mississippi River Delta. By deduction, Mississippi River flooding in years of low Arkansas River flow imply exceptional flooding contributions from the Upper Mississippi River catchments

    A Microcalorimeter and Bolometer Model

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    The standard non-equilibrium theory of noise in ideal bolometers and microcalorimeters fails to predict the performance of real devices due to additional effects that become important at low temperature. In this paper we extend the theory to include the most important of these effects, and find that the performance of microcalorimeters operating at 60 mK can be quantitatively predicted. We give a simple method for doing the necessary calculations, borrowing the block diagram formalism from electronic control theory.Comment: 20 pages, 15 figure
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