231 research outputs found
Feasibility study of a 110 watt per kilogram lightweight solar array system
An investigation of the feasibility of a solar array panel subsystem which will produce 10,000 watts of electrical output at 1 A.U. with an overall beginning-of-life power-to-weight ratio of at least 110 watt/kg is reported. A description of the current baseline configuration which meets these requirements is presented. A parametric analysis of the single boom, two blanket planar solar array system was performed to arrive at the optimum system aspect ratio. A novel concept for the stiffening of a lightweight solar array by canting the solar cell blankets at a small angle to take advantage of the inherent in-plane stiffness to increase the symmetric out-of-plane frequency is introduced along with a preliminary analysis of the stiffening effect. A comparison of welded and soldered solar cell interconnections leads to the conclusion that welding is required on this ultralightweight solar array. The use of a boron/aluminum composite material in a BI-STEM type deployable boom is investigated as a possible advancement in the state-of-the-art
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Interdecadal Pacific Oscillation reconstructed from trans-Pacific tree rings: 1350–2004 CE
The interdecadal Pacific Oscillation (IPO) represents the decadal mode of the El Niño-Southern Oscillation phenomenon. As such the IPO is one of the dominant modes of decadal climate variability on both sides of the Pacific Ocean basin. For this paper we utilized a newly developed tree-ring data network comprised of five multi-centennial Vietnamese cypress ring-width chronologies that range from around 11°N–23°N latitude. We combined these data with an average of tree-ring derived drought indices from the North American Drought Atlas over the south central USA, from a box that spans from
27.5°N–35.0°N, 85.0°–110.0°W and contains 55 gridpoints and more than 100 tree ring site chronologies, these 2 locations exhibit rainfall variations that are strongly, negatively correlated with each other and are representative of the influence of the IPO on terrestrial rainfall. The final reconstruction model, weighted most heavily on the three most southerly of the five Vietnamese cypress records, spans from 1350 to 2004, and explains nearly 57% of the variance in the original IPO data for the 5-month season of October–February. The reconstruction model passes all standard statistical tests using a split calibrationverification scheme. We reveal 15 positive and 15 negative phase shifts of the IPO prior to the period of instrumentation, suggesting that the IPO has been active for at least the past seven centuries with varying degrees of intensity. We compare our reconstruction with two related millennial records: the MacDonald and Case (Geophys Res Lett 32(8):L08703, 2005)
tree ring-derived reconstruction of the Pacific Decadal Oscillation, and an ice core-derived reconstruction of the IPO from the Law Dome Ice core in Antarctica by Vance et al. (Geophys Res Lett 33(6):L06712, 2015). While there is good general agreement with the latter record, there are three key periods of the past where the two records are out of phase, and we explore the reasons for this disparity. Direct comparison with the related Tripole Index (TPI) shows weaker correlation, likely owing
to the stronger relationship between our tree ring data and the equatorial Pacific region relative to the north and south regions of the Pacific that combine to comprise the TPI calculation
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Demography, baseline disease characteristics and treatment history of patients with psoriasis enrolled in a multicentre, prospective, disease-based registry (PSOLAR)*
Summary Background: Psoriasis is associated with several comorbidities and behavioural risk factors. Objectives: To evaluate demographic and disease characteristics in patients enrolled in the Psoriasis Longitudinal Assessment and Registry (PSOLAR). Methods: PSOLAR is a global, prospective, longitudinal, disease-based registry that includes a postmarketing commitment to evaluate safety in patients with psoriasis. Enrolled patients had to be receiving, or be eligible to receive, conventional systemic or biological agents. Demographic/disease characteristics, medical histories, lifestyle risk factors and previous treatments are collected at enrolment. Efficacy and safety data are collected every 6 months for 8 years, and data are extracted annually. Selected parameters are evaluated by age quartile using post hoc analyses. Results: As of 23 August 2012, 11 900 patients were enrolled at 301 sites in North America, Europe and Latin America. Over half of the PSOLAR population (54·7%) is male, with a mean age of 48·6 years and mean body mass index of 30·9 kg m−2 at enrolment. Mean duration of disease at enrolment was 17·5 years, and mean Physician's Global Assessment score was 2·0. Psoriatic arthritis (35·5%) and cardiovascular diseases (38·2%) were highly prevalent. Diabetes mellitus type II was reported in 11·4% of patients. Depression and anxiety were noted in 14·7% and 11·1% of patients, respectively; 79·0% reported any alcohol use and 56·7% reported smoking or a history of smoking. The occurrence of most comorbidities, including cardiovascular disease and risk factors, increased with age. Conclusions: In the PSOLAR population, multiple and age-appropriate comorbidities are associated with psoriasis and may affect the selection of psoriasis treatments. What's already known about this topic? Psoriasis is a complicated disorder, often accompanied by multiple comorbidities. Demographic and disease characteristics of patients with psoriasis reported from large claims datasets may be affected by misclassification bias or coding errors. In clinical trials, many patients are excluded owing to strict inclusion criteria. What does this study add? Data collected by the Psoriasis Longitudinal Assessment and Registry reveal that the demographics and disease characteristics of patients with psoriasis who are receiving, or are candidates for, systemic therapy in actual clinical care resemble those reported in clinical trials. Most comorbidities occur more frequently in older patients, who, in turn, may require more comprehensive overall medical care
Intentional and unintentional medication nonadherence in psoriasis: the role of patients’ medication beliefs and habit strength [abstract only]
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
A Microcalorimeter and Bolometer Model
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
Characteristics and outcomes of patients treated with apremilast in the real world: results from the APPRECIATE study
Background
APPRECIATE is a multinational, observational, retrospective, cross‐sectional study in patients treated for psoriasis with apremilast, an oral phosphodiesterase 4 inhibitor.
Objectives
To describe the characteristics of patients with psoriasis treated with apremilast in the clinical setting, to evaluate real‐world outcomes of psoriasis treatment with apremilast and to better understand the perspectives of patients and physicians on treatment outcomes.
Methods
In six European countries, patients with chronic plaque psoriasis treated in clinical practice who could be contacted 6 (±1) months after apremilast initiation were enrolled. Patient characteristics, Dermatology Life Quality Index (DLQI) and Psoriasis Area and Severity Index (PASI) were obtained from medical records when available. Outcomes were evaluated using patient/physician questionnaires.
Results
In 480 patients at treatment initiation, mean [median; 95% confidence interval (CI)] PASI and DLQI scores were 12.5 (10.7; 11.6–13.4) and 13.4 (13.0; 11.4–14.2), respectively. At 6 (±1) months, 72.3% of patients (n = 347) continued apremilast treatment [discontinuations: lack of efficacy (13.5%), safety (11.7%), other (2.5%)]. In patients continuing treatment, 48.6% achieved a ≥75% reduction in PASI score; mean (95% CI) DLQI score was 5.7 (4.5–6.9), and mean (SD) Patient Benefit Index score was 2.8 (1.2). Physicians perceived clinical improvement in 75.6% of patients. Physicians’ perspective on overall success of apremilast in meeting expectations correlated with patients’ perception of treatment benefit (r = 0.691). Most commonly reported adverse events (>5% of patients) were diarrhoea, nausea and headache.
Conclusions
Patients in APPRECIATE reported high disease burden despite more moderate skin involvement than those who enrolled in clinical trials of apremilast. Findings from APPRECIATE demonstrate the real‐world value of apremilast for psoriasis treatment, as 7 of 10 patients continued therapy and showed notable improvement in disease severity and quality of life 6 (±1) months after apremilast initiation
Pan American interactions of Amazon precipitation, streamflow, and tree growth extremes
Rainfall and river levels in the Amazon are associated with significant precipitation anomalies of opposite sign in temperate North and South America, which is the dominant mode of precipitation variability in the Americas that often arises during extremes of the El Niño/Southern Oscillation (ENSO). This co-variability of precipitation extremes across the Americas is imprinted on tree growth and is detected when new tree-ring chronologies from the eastern equatorial Amazon are compared with hundreds of moisture-sensitive tree-ring chronologies in mid-latitude North and South America from 1759 to 2016. Pan-American co-variability exists even though the seasonality of precipitation and tree growth only partially overlaps between the Amazon and mid-latitudes because ENSO forcing of climate can persist for multiple seasons and can orchestrate a coherent response, even where the growing seasons are not fully synchronized. The tree-ring data indicate that the El Niño influence on inter-hemispheric precipitation and tree growth extremes has been strong and stable over the past 258-years, but the La Niña influence has been subject to large multi-decadal changes. These changes have implications for the dynamics and forecasting of hydroclimatic variability over the Americas and are supported by analyses of the available instrumental data and selected climate model simulations.Fil: Stahle, D.W.. University of Arkansas for Medical Sciences; Estados UnidosFil: Torbenson, Max Carl Arne. Ohio State University; Estados UnidosFil: Howard, I. M.. University of Arkansas for Medical Sciences; Estados UnidosFil: Granato Souza, D.. University of Arkansas for Medical Sciences; Estados UnidosFil: Barbosa, A. C.. Universidad Federal de Lavras; BrasilFil: Feng, S.. University of Arkansas for Medical Sciences; Estados UnidosFil: Schöngart, J.. National Institute For Amazon Research; BrasilFil: Lopez Callejas, Lidio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Villalba, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Villanueva, J.. Instituto Nacional de Investigaciones Forestales Agrícolas y Pecuarias; MéxicoFil: Fernandes, K.. Columbia University; Estados Unido
The Advanced Technology Large-Aperture Space Telescope (ATLAST) Technology Roadmap
We present the key technologies and capabilities that will enable a future, large-aperture ultravioletopticalinfrared (UVOIR) space observatory. These include starlight suppression systems, vibration isolation and control systems, lightweight mirror segments, detector systems, and mirror coatings. These capabilities will provide major advances over current and near-future observatories for sensitivity, angular resolution, and starlight suppression. The goals adopted in our study for the starlight suppression system are 10-10 contrast with an inner working angle of 40 milliarcsec and broad bandpass. We estimate that a vibration and isolation control system that achieves a total system vibration isolation of 140 dB for a vibration-isolated mass of 5000 kg is required to achieve the high wavefront error stability needed for exoplanet coronagraphy. Technology challenges for lightweight mirror segments include diffraction-limited optical quality and high wavefront error stability as well as low cost, low mass, and rapid fabrication. Key challenges for the detector systems include visible-blind, high quantum efficiency UV arrays, photon counting visible and NIR arrays for coronagraphic spectroscopy and starlight wavefront sensing and control, and detectors with deep full wells with low persistence and radiation tolerance to enable transit imaging and spectroscopy at all wavelengths. Finally, mirror coatings with high reflectivity ( 90), high uniformity ( 1) and low polarization ( 1) that are scalable to large diameter mirror substrates will be essential for ensuring that both high throughput UV observations and high contrast observations can be performed by the same observatory
Is eastern Mongolia drying? A long-term perspective of a multidecadal trend
Temperatures in semiarid Mongolia have rapidly risen over the past few decades, and increases in drought, urban development, mining, and agriculture have intensified demands on limited water resources. Understanding long-term streamflow variation is critical for Mongolia, particularly if alterations in streamflow are being considered and because of the potential negative impacts of drought on the animal agriculture sector. Here, we present a temporally and spatially improved streamflow reconstruction for the Kherlen River. We have added 11 new records in comparison with two in the original 2001 reconstruction. This new reconstruction extends from 1630 to 2007 and places the most recent droughts in a multicentennial perspective. We find that variations in streamflow have been much greater in the past than in the original study. There was higher variability in the mid to late 1700s, ranging from severe and extended drought conditions from 1723 to 1739 and again in 1768–1778 to two decadal length episodes of very wet conditions in the mid 1700s and late 1700s. Reduced amplitude is seen in the mid-1800s, and several pluvial events are reconstructed for the 1900s. Although recent droughts are severe and disturbing economic and ecological systems in Mongolia and it appears that eastern Mongolia is drying, the drying trend since the late 1900s might in fact be accentuated by a change from a particularly wet era in Mongolia. The recent drought might be a return to more characteristic hydroclimatic conditions of the past four centuries in Mongolia
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