544 research outputs found

    The first cosmic ray albedo proton map of the Moon

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    [1] Neutrons emitted from the Moon are produced by the impact of galactic cosmic rays (GCRs) within the regolith. GCRs are high-energy particles capable of smashing atomic nuclei in the lunar regolith and producing a shower of energetic protons, neutrons and other subatomic particles. Secondary particles that are ejected out of the regolith become “albedo” particles. The neutron albedo has been used to study the hydrogen content of the lunar regolith, which motivates our study of albedo protons. In principle, the albedo protons should vary as a function of the input GCR source and possibly as a result of surface composition and properties. During the LRO mission, the total detection rate of albedo protons between 60 MeV and 150 MeV has been declining since 2009 in parallel with the decline in the galactic cosmic ray flux, which validates the concept of an albedo proton source. On the other hand, the average yield of albedo protons has been increasing as the galactic cosmic ray spectrum has been hardening, consistent with a disproportionately stronger modulation of lower energy GCRs as solar activity increases. We construct the first map of the normalized albedo proton emission rate from the lunar surface to look for any albedo variation that correlates with surface features. The map is consistent with a spatially uniform albedo proton yield to within statistical uncertainties

    AMCIS 2002 Panels and Workshops III: How Will Media Technology Evolve as an Academic Discipline?

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    Media Technology (MT) is a new, multidisciplinary field that integrates the knowledge, expertise, resources, and creativity of diverse, established, fertile artistic disciplines (visual design, art, music, radio, television) with new technological disciplines (digital media, information systems, information technology, computer science, network engineering) through rapidly-evolving technologies. Its application in electronic commerce into what will become a full synthesis of information technology and sensory interaction will be made possible by approaches to presenting and exchanging information visually, aurally--and eventually in combination with all of the senses. This article reports on a panel held at AMCIS 2002 in Dallas TX. The panel discussed the need to develop a literacy and understanding in the IT discipline of the MT and its importance in keeping IT research relevant. The panel also discussed strategies for attaining MT literacy, integrating MT into the IT curriculum, and discussed two universities where it is being done

    Radiation modeling in the Earth and Mars atmospheres using LRO/CRaTER with the EMMREM Module

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    Abstract We expand upon the efforts of Joyce et al. (2013), who computed the modulation potential at the Moon using measurements from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument on the Lunar Reconnaissance Orbiter (LRO) spacecraft along with data products from the Earth-Moon-Mars Radiation Environment Module (EMMREM). Using the computed modulation potential, we calculate galactic cosmic ray (GCR) dose and dose equivalent rates in the Earth and Mars atmospheres for various altitudes over the course of the LRO mission. While we cannot validate these predictions by directly comparable measurement, we find that our results conform to expectations and are in good agreement with the nearest available measurements and therefore may be used as reasonable estimates for use in efforts in risk assessment in the planning of future space missions as well as in the study of GCRs. PREDICCS (Predictions of radiation from REleASE, EMMREM, and Data Incorporating the CRaTER, COSTEP, and other solar energetic particles measurements) is an online system designed to provide the scientific community with a comprehensive resource on the radiation environments of the inner heliosphere. The data products shown here will be incorporated into PREDICCS in order to further this effort and daily updates will be made available on the PREDICCS website (http://prediccs.sr.unh.edu). Key Points We model GCR dose and dose equivalent rates in Earth and Mars atmospheres Dose rates are in reasonable agreement with nearby measurements Data products will soon be made available on PREDICCS website

    Radiation environment at the Moon: Comparisons of transport code modeling and measurements from the CRaTER instrument

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    The Cosmic Ray Telescope for the Effects of Radiation (CRaTER), an instrument carried on the Lunar Reconnaissance Orbiter spacecraft, directly measures the energy depositions by solar and galactic cosmic radiations in its silicon wafer detectors. These energy depositions are converted to linear energy transfer (LET) spectra. High LET particles, which are mainly high‐energy heavy ions found in the incident cosmic ray spectrum, or target fragments and recoils produced by protons and heavier ions, are of particular importance because of their potential to cause significant damage to human tissue and electronic components. Aside from providing LET data useful for space radiation risk analyses for lunar missions, the observed LET spectra can also be used to help validate space radiation transport codes, used for shielding design and risk assessment applications, which is a major thrust of this work. In this work the Monte Carlo transport code HETC‐HEDS (High‐Energy Transport Code‐Human Exploration and Development in Space) is used to estimate LET contributions from the incident primary ions and their charged secondaries produced by nuclear collisions as they pass through the three pairs of silicon detectors. Also in this work, the contributions to the LET of the primary ions and their charged secondaries are analyzed and compared with estimates obtained using the deterministic space radiation code HZETRN 2010, developed at NASA Langley Research Center. LET estimates obtained from the two transport codes are compared with measurements of LET from the CRaTER instrument during the mission. Overall, a comparison of the LET predictions of the HETC‐HEDS code to the predictions of the HZETRN code displays good agreement. The code predictions are also in good agreement with the CRaTER LET measurements above 15 keV/”m but differ from the measurements for smaller values of LET. A possible reason for this disagreement between measured and calculated spectra below 15 keV/”m is an inadequate representation of the light ion spectra in HETC‐HEDS and HZETRN code calculations. It is also clear from the results of this work that Vavilov distributions need to be incorporated into the HETC‐HJEDS code before it will be able to recreate the observed LET spectra measured by the CRaTER instrument. Key Points Vavilov corrections should be incorporated into simulated results The predictions of the transport codes reasonably agree with the CRaTER LET The observed LET can be used to help validate space radiation transport codesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108081/1/swe20145.pd

    The Impact of Transcatheter Atrial Septal Defect Closure in the Older Population A Prospective Study

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    ObjectivesWe sought to prove that device closure of atrial septal defect (ASD) in older patients not only improves cardiac function but also results in symptomatic relief by improving functional class.BackgroundAtrial septal defect accounts for approximately 10% of all congenital cardiac defects. It is possible that ASD closure in older patients may derive benefits, though this is not well established. We therefore aim to prospectively assess the clinical status and functional class of older patients after transcatheter ASD closure.MethodsThis was a prospective study of all patients age 40 years or more who underwent device closure of a secundum ASD between April 2004 and August 2006. Investigations including atrial and brain natriuretic peptide levels, electrocardiography, chest X-ray, transthoracic echocardiogram, 6-min walk test, and quality of life questionnaire were performed before and at 6 weeks and 1 year after the procedure.ResultsTwenty-three patients (median age 70 years, 13 women) had transcatheter device closure of ASD. Median ASD size was 18 mm (range 9 to 30 mm). Median pulmonary artery pressure was 22 mm Hg (range 12 to 27 mm Hg). At 1 year, New York Heart Association functional class improved (p = 0.004) in 16 patients with significant improvement in 6-min walk-test distance (p = 0.004) and physical (p = 0.002) as well as mental health score (p = 0.03). There were no major complications. One year following closure there was a significant change in left ventricular end-diastolic (p = 0.001) and end-systolic dimensions (p = 0.001) and also significant reduction in right ventricular end-diastolic dimension (p < 0.001).ConclusionsOur data demonstrated that ASD closure at advanced age results in favorable cardiac remodeling and improvement of functional class

    Nested Case–Control Study of Autoimmune Disease in an Asbestos-Exposed Population

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    OBJECTIVE: To explore the potential association between asbestos exposure and risk of autoimmune disease, we conducted a case–control study among a cohort of 7,307 current and former residents of Libby, Montana, a community with historical occupational and environmental exposure to asbestos-contaminated vermiculite. METHODS: Cases were defined as those who reported having one of three systemic autoimmune diseases (SAIDs): systemic lupus erythematosus, scleroderma, or rheumatoid arthritis (RA). Controls were randomly selected at a 3:1 ratio from among the remaining 6,813 screening participants using frequency-matched age and sex groupings. RESULTS: The odds ratios (ORs) and 95% confidence intervals (CIs) for SAIDs among those ≄ 65 years of age who had worked for the vermiculite mining company were 2.14 (95% CI, 0.90–5.10) for all SAIDs and 3.23 (95% CI, 1.31–7.96) for RA. In this age group, exposure to asbestos while in the military was also an independent risk factor, resulting in a tripling in risk. Other measures of occupational exposure to vermiculite indicated 54% and 65% increased risk for SAIDs and RA, respectively. Those who had reported frequent contact with vermiculite through various exposure pathways also demonstrated elevated risk for SAIDs and RA. We found increasing risk estimates for SAIDs with increasing numbers of reported vermiculite exposure pathways (p < 0.001). CONCLUSION: These preliminary findings support the hypothesis that asbestos exposure is associated with autoimmune disease. Refined measurements of asbestos exposure and SAID status among this cohort will help to further clarify the relationship between these variables

    Spectroscopy of formaldehyde in the 30140-30790cm^-1 range

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    Room-temperature absorption spectroscopy of formaldehyde has been performed in the 30140-30790cm^-1 range. Using tunable ultraviolet continuous-wave laser light, individual rotational lines are well resolved in the Doppler-broadened spectrum. Making use of genetic algorithms, the main features of the spectrum are reproduced. Spectral data is made available as Supporting Information

    Premature atherosclerosis is associated with hypovitaminosis d and angiotensin-converting enzyme inhibitor non-use in lupus patients

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    The ultimate goal is to identify and target modifiable risk factors that will reduce major cardiovascular events in African American lupus patients. As a first step toward achieving this goal, this study was designed to explore risk factor models of preclinical atherosclerosis in a predominantly African American group of patients with systemic lupus erythematosus (SLE) using variables historically associated with endothelial function in nonlupus populations. Fifty-one subjects with SLE but without a history of clinical cardiovascular events were enrolled. At entry, a Framingham risk factor history and medication list were recorded. Sera and plasma samples were analyzed for lipids, lupus activity markers and total 25-hydroxyvitamin D (25 OH)D) levels. Carotid ultrasound measurements were performed to determine total plaque area (TPA) in both carotids. Cases had TPA values above age-matched controls from a vascular prevention clinic population. Logistic regression and machine learning analyses were performed to create predictive models. 25(OH)D levels were significantly lower, and SLE disease duration was significantly higher in cases. 25(OH)D levels inversely correlated with age-adjusted TPA. Angiotensin-converting enzyme (ACE) inhibitor nonuse associated with case status. Logistic regression models containing ACE inhibitor use, 25(OH)D levels and low-density lipoprotein levels had a diagnostic accuracy of 84% for predicting accelerated atherosclerosis. Similar results were obtained with machine learning models, but hydroxychlo-roquine use associated with controls in these models. This is the first study to demonstrate an association between atherosclerotic burden and 25(OH)D insufficiency or ACE inhibitor nonuse in lupus patients. These findings provide strong rationale for the study of ACE inhibitors and vitamin D replenishment as preventive therapies in this high-risk population. © Copyright 2012 Southern Society for Clinical Investigation
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