1,461 research outputs found

    Oxidized basalts on the surface of Venus: Compositional implications of measured spectral properties

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    Venera Lander reflectance data are compared with high temperature spectra of the same basaltic materials. The dark, flat unoxidized basalts are still inconsistent with the Venera data in the near-infrared. Basaltic material with a ferric component, however, would satisfy both the increase in reflectance beyond 0.7 microns as well as the dark, relatively colorless character in the visible. Therefore, it is concluded that besaltic surfaces of Venus represented by these measurements either contain minerals with uncommon characteristics, or, more likely, are relatively oxidized

    Pagetʼs Disease (Osteitis Deformans) in Archaeological Remains: A Radiographic Differential

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    Paget’s disease of bone is a metabolic bone disease of unknown etiology and is the most likely disease to cause secondary bone cancer; a prevalence that increases with age[1]. With the increasing age of modern populations, the importance of better understanding this disease will likewise increase. While in vivo tests for the disease cannot be performed in skeletal samples, radiographic views of archaeological remains can provide insight into the origins and natural history of the disease

    Assessment of Human Trabecular Architecture in the Pubis by Three Radiographic Modalities

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    This poster discusses technical aspects of an investigation into the use of non-destructive radiological analyses of pubic cancellous bone structure to estimate age-at-death from human skeletal remains. This study stems from findings, in X-ray plain films, of increased rarification and orientation of trabeculae with age [1]; likely in concert with the macroscopic remodelling of the symphyseal surface currently used in estimation of age-at-death. The study uses three non-destructive X-ray imaging modalities: plain film radiography, computed tomography (CT), and micro-CT (μCT). Plain film radiography has greater spatial resolution than CT [2] and is relatively inexpensive, widely available, and, with portable X-ray units, even accessible in the field for archaeological and forensic applications. CT scanners are largely restricted to clinical settings due to the size, sensitivity, and cost of the machine, but offer a greater contrast resolution than plain film radiography [2]. More expensive and more precise, μCTscanners are further restricted in their availability and accessibility, but CT andμCTmodalities provide volumetric data, avoiding the confusion of overlying cortical and cancellous structures and the apparent increases in density with element thickness seen in plain film radiography

    Committee Reports

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    Contains reports from the following committees of the Washington State Bar Association: Administrative Law, Civil Rights, Code Commission, Cooperation with American Bar Association, Federal Legislation, Improvement of Probate Statutes, Law Examiners, Legal Education, Legal Ethics, Legal Institutes, Legislative, Obituary, Selection of Judges, and Unauthorized Practice of Law. Also includes the auditor\u27s report

    NuSTAR Hard X-ray Observation of the Gamma-ray Binary Candidate HESS J1832-093

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    We present a hard X-ray observation of the TeV gamma-ray binary candidate HESS J1832-093 coincident with supernova remnant (SNR) G22.7-0.2 using the Nuclear Spectroscopic Telescope Array (NuSTAR). Non-thermal X-ray emission from XMMU J183245-0921539, the X-ray source associated with HESS J1832-093, is detected up to ~30 keV and is well-described by an absorbed power-law model with the best-fit photon index Γ=1.5±0.1\Gamma = 1.5\pm0.1. A re-analysis of archival Chandra and XMM-Newton data finds that the long-term X-ray flux increase of XMMU J183245-0921539 is 5020+4050^{+40}_{-20}% (90% C.L.), much less than previously reported. A search for a pulsar spin period or binary orbit modulation yields no significant signal to a pulse fraction limit of fp < 19% in the range 4 ms < P < 40 ks. No red noise is detected in the FFT power spectrum to suggest active accretion from a binary system. While further evidence is required, we argue that the X-ray and gamma-ray properties of XMMU J183245-0921539 are most consistent with a non-accreting binary generating synchrotron X- rays from particle acceleration in the shock formed as a result of the pulsar and stellar wind collision. We also report on three nearby hard X-ray sources, one of which may be associated with diffuse emission from a fast-moving supernova fragment interacting with a dense molecular cloud.Comment: ApJ in press. 9 page

    Breakthrough capability for the NASA Astrophysics Explorer Program: Reaching the darkest sky

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    We describe a mission architecture designed to substantially increase the science capability of the NASA Science Mission Directorate (SMD) Astrophysics Explorer Program for all AO proposers working within the near-UV to far-infrared spectrum. We have demonstrated that augmentation of Falcon 9 Explorer launch services with a 13 kW Solar Electric Propulsion (SEP) stage can deliver a 700 kg science observatory payload to extra-Zodiacal orbit. This new capability enables up to ~13X increased photometric sensitivity and ~160X increased observing speed relative to a Sun-Earth L2, Earth-trailing, or Earth orbit with no increase in telescope aperture. All enabling SEP stage technologies for this launch service augmentation have reached sufficient readiness (TRL-6) for Explorer Program application in conjunction with the Falcon 9. We demonstrate that enabling Astrophysics Explorers to reach extra-zodiacal orbit will allow this small payload program to rival the science performance of much larger long development time systems; thus, providing a means to realize major science objectives while increasing the SMD Astrophysics portfolio diversity and resiliency to external budget pressure. The SEP technology employed in this study has strong applicability to SMD Planetary Science community-proposed missions. SEP is a stated flight demonstration priority for NASA's Office of the Chief Technologist (OCT). This new mission architecture for astrophysics Explorers enables an attractive realization of joint goals for OCT and SMD with wide applicability across SMD science disciplines.Comment: Submitted to proceedings of the SPIE Astronomical Telescopes and Instrumentation conference, Amsterdam, The Netherlands, July 201

    The effect of social media communication on consumer perceptions of brands

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    Researchers and brand managers have limited understanding of the effects social media communication has on how consumers perceive brands. We investigated 504 Facebook users in order to observe the impact of firm-created and user-generated social media communication on brand equity, brand attitude and purchase intention by using a standardized online survey throughout Poland. To test the conceptual model, we analyzed 60 brands across three different industries: non-alcoholic beverages, clothing and mobile network operators. When analyzing the data, we applied the structural equation modeling technique to both investigate the interplay of firm-created and user-generated social media communication and examine industry-specific differences. The results of the empirical studies showed that user-generated social media communication had a positive influence on both brand equity and brand attitude, whereas firm-created social media communication affected only brand attitude. Both brand equity and brand attitude were shown to have a positive influence on purchase intention. In addition, we assessed measurement invariance using a multi-group structural modeling equation. The findings revealed that the proposed measurement model was invariant across the researched industries. However, structural path differences were detected across the models

    Ion rocket engine development Quarterly report no. 3, 1 Apr. - 30 Jun. 1965

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    Integral focus cesium contact ion rocket engine and iridium and rhenium coated porous tungsten ionizer evaluation

    Isolation Effects on the Moon: High Topographic Slope Observations from the LRO and LOLA Instruments

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    The extremely low temperatures in the Moon's polar permanent shadow regions (PSR) has long been considered a unique factor necessary for entrapping volatile Hydrogen (H). However, recent discoveries indicate some H concentrations lie outside PSR, suggesting other geophysical factors may also influence H distributions. In this study we consider insolation and its resulting thermal effects as a loss/redistribution process influencing the Moon's near-surface < 1m volatile H budget. To isolate regional (5deg latitude band) insolation effects we correlate two data sets collected from the ongoing, 1.5 year long mapping mission of the Lunar Reconnaissance Orbiter (LRO). Epithermal neutron mapping data from the Lunar Exploration Neutron Detector (LEND) is registered and analyzed in the context of slope derivations from Lunar topography maps produced by the Lunar Observing Laser Altimeter (LOLA). Lunar epithermal neutrons are inferred to be direct geochemical evidence for near-surface H due to the correlated suppression of surface leakage fluxes of epithermal neutrons with increased H concentration. Regional suppressions of neutrons seen in LEND maps are considered localized evidence of H concentration increase in the upper 1 m of the Lunar surface. To quantify spatially localized insolation effects, LEND data are averaged from sparsely distributed pixels, classed as a function of the LOLA slope derivations
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