MOD-1 WTG dynamic analysis

An analysis of the MOD-1 2000 kW horizontal axis wind turbine was given. The MOD-1 design was briefly described, and the analysis used to evaluate the dynamic loads and structural interactions is discussed. The resonant frequency placement, the treatment of unsteady wind loading, and the dynamic load sensitivity to frequency shifts were reviewed for the design

Ground vibration testing of complex structures

A method of measuring separately the in-phase and quadrature components of the vibration response, designed by APL, was developed and applied. Both analysis and test results show immediately a much improved definition of mode shapes and frequencies. The approach was further developed. It allows the measurement of damping in the different natural modes, and the determination of the exact shape of the normal modes, i.e., to eliminate the coupling effect due to structural damping. It is also expected to be used in flight flutter testing

Shuttle payload vibroacoustic test plan evaluation. Free flyer payload applications and sortie payload parametric variations

A preliminary assessment of vibroacoustic test plan optimization for free flyer STS payloads is presented and the effects on alternate test plans for Spacelab sortie payloads number of missions are also examined. The component vibration failure probability and the number of components in the housekeeping subassemblies are provided. Decision models are used to evaluate the cost effectiveness of seven alternate test plans using protoflight hardware

Vibroacoustic test plan evaluation: Parameter variation study

Statistical decision models are shown to provide a viable method of evaluating the cost effectiveness of alternate vibroacoustic test plans and the associated test levels. The methodology developed provides a major step toward the development of a realistic tool to quantitatively tailor test programs to specific payloads. Testing is considered at the no test, component, subassembly, or system level of assembly. Component redundancy and partial loss of flight data are considered. Most and probabilistic costs are considered, and incipient failures resulting from ground tests are treated. Optimums defining both component and assembly test levels are indicated for the modified test plans considered. modeling simplifications must be considered in interpreting the results relative to a particular payload. New parameters introduced were a no test option, flight by flight failure probabilities, and a cost to design components for higher vibration requirements. Parameters varied were the shuttle payload bay internal acoustic environment, the STS launch cost, the component retest/repair cost, and the amount of redundancy in the housekeeping section of the payload reliability model

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

ATLAST detector needs for direct spectroscopic biosignature characterization in the visible and near-IR

Are we alone? Answering this ageless question will be a major focus for astrophysics in coming decades. Our tools will include unprecedentedly large UV-Optical-IR space telescopes working with advanced coronagraphs and starshades. Yet, these facilities will not live up to their full potential without better detectors than we have today. To inform detector development, this paper provides an overview of visible and near-IR (VISIR; $\lambda=0.4-1.8~\mu\textrm{m}$) detector needs for the Advanced Technology Large Aperture Space Telescope (ATLAST), specifically for spectroscopic characterization of atmospheric biosignature gasses. We also provide a brief status update on some promising detector technologies for meeting these needs in the context of a passively cooled ATLAST.Comment: 8 pages, Presented 9 August 2015 at SPIE Optics + Photonics, San Diego, C

Dual Band Deep Ultraviolet AlGaN Photodetectors

We report on the design, fabrication and characterization of a back-illuminated voltage bias selectable dual-band AlGaN UV photodetector. The photodetector can separate UVA and W-B band radiation by bias switching a two terminal n-p-n homojunction structure that is fabricated in the same pixel. When a forward bias is applied between the top and bottom electrodes, the detector can sense UV-A and reject W-B band radiation. Alternatively, under reverse bias, the photodetector can sense UV-B and reject UV-A band radiation

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

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

Dynamic Regulation of Fibrinogen: Integrin αIIbβ3 Binding

This study demonstrates that two orthogonal events regulate integrin αIIbβ3’s interactions with fibrinogen, its primary physiological ligand: (1) conformational changes at the αIIb–β3 interface and (2) flexibility in the carboxy terminus of fibrinogen’s γ-module. The first postulate was tested by capturing αIIbβ3 on a biosensor and measuring binding by surface plasmon resonance. Binding of fibrinogen to eptifibatide-primed αIIbβ3 was characterized by a kon of ~2 × 104 L mol−1 s−1 and a koff of ~8 × 10−5 s−1 at 37 °C. In contrast, even at 150 nM fibrinogen, no binding was detected with resting αIIbβ3. Eptifibatide competitively inhibited fibrinogen’s interactions with primed αIIbβ3 (Ki ~ 0.4 nM), while a synthetic γ-module peptide (HHLGGAKQAGDV) was only weakly inhibitory (Ki > 10 µM). The second postulate was tested by measuring αIIbβ3’s interactions with recombinant fibrinogen, both normal (rFgn) and a deletion mutant lacking the γ-chain AGDV sites (rFgn γΔ408–411). Normal rFgn bound rapidly, tightly, and specifically to primed αIIbβ3; no interaction was detected with rFgn γΔ408–411. Equilibrium and transition-state thermodynamic data indicated that binding of fibrinogen to primed αIIbβ3, while enthalpy-favorable, must overcome an entropy-dominated activation energy barrier. The hypothesis that fibrinogen binding is enthalpy-driven fits with structural data showing that its γ-C peptide and eptifibatide exhibit comparable electrostatic contacts with αIIbβ3’s ectodomain. The concept that fibrinogen’s αIIbβ3 targeting sequence is intrinsically disordered may explain the entropy penalty that limits its binding rate. In the hemostatic milieu, platelet–platelet interactions may be localized to vascular injury sites because integrins must be activated before they can bind their most abundant ligand