1,952 research outputs found

    NASAs Orbital Debris JAO/ES-MCAT Optical Telescope Facility on Ascension Island

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    The NASA Orbital Debris Program Office has a long-standing optical program begun over three and a half decades ago in 1984, designed to observe the Earth-orbiting environment with optical telescopes. Photometrically calibrated optical data provides a statistical sample for input to NASA models of the debris population for understanding the current and future debris environment around the Earth. Tracked objects and orbits allow for analysis of break-up events. Both known (correlated target in the SSN catalogue, or CT) and unknown (uncorrelated target, or UCT) objects are of interest to better understand how to protect current spacecraft and design more robust future operational satellites, and advise on how policies and practices can lead to protecting the environment itself for future generations. In 2015, a joint NASA JSC Air Force Research Labs (AFRL) project culminated in the installation of the 1.3-meter Eugene Stansbery Meter Class Autonomous Telescope, ES-MCAT (a.k.a. MCAT) on Ascension Island. This DFM Engineering designed telescope provides nearly five-times greater light-collecting power than its predecessor, the 0.6-m MODEST telescope, and faster tracking capabilities by both the telescope and the 7-m ObservaDome. This allows for all orbital regimes to be easily within reach, ranging from low Earth to geosynchronous orbits. Extensive testing and commissioning activities of this custom system led to successfully reaching Initial Operational Capability in 2018, and the facility is currently on track to reach Full Operational Capability. The John Africano Observatory (JAO) comprises the primary 1.3-m ES-MCAT facility, the adjacent tower platform with a 0.4-m telescope, a sophisticated suite of weather instruments, and custom software by Euclid Research for autonomously running the entire system, including monitoring the weather and hardware, tasking all components, and collecting, processing, and analyzing the data. The mission of JAO and MCAT will be discussed, including survey and tracking tasking, a full discussion of data calibration, and both optics and weather-dependent performance

    Multi-filter spectrophotometry simulations

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    To complement both the multi-filter observations of quasar environments described in these proceedings, as well as the proposed UBC 2.7 m Liquid Mirror Telescope (LMT) redshift survey, we have initiated a program of simulated multi-filter spectrophotometry. The goal of this work, still very much in progress, is a better quantitative assessment of the multiband technique as a viable mechanism for obtaining useful redshift and morphological class information from large scale multi-filter surveys

    Rate constants and Arrhenius parameters for the reactions of OH radicals and Cl atoms with CF3CH2OCHF2, CF3CHClOCHF2 and CF3CH2OCClF2, using the discharge-flow/resonance fluorescence method

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    Rate constants have been determined for the reactions of OH radicals and Cl atoms with the three partially halogenated methyl-ethyl ethers, CF3_3CH2_2OCHF2_2, CF3_3CHClOCHF2_2 and CF3_3CH2_2OCClF2_2, using discharge-flow techniques to generate the OH radicals and the Cl atoms and resonance fluorescence to observe changes in their relative concentrations in the presence of added ether. For each combination of radical and ether, experiments were carried out at three temperatures between 292 and 410 K, yielding the following Arrhenius expressions for the rate constants within this range of temperature: OH + CF3_3CH2_2OCHF2_2: kk = (2.0±\pm0.8) ×\times 1011^{-11} exp( – 2110 ±\pm 150 K / T) cm3^3 molecule1^{-1} s1^{-1} OH + CF3_3CHClOCHF2_2: kk = (4.5 ±\pm 1.3) ×\times 1013^{-13} exp( – 940 ±\pm 100 K / T) cm3^3 molecule1^{-1} s1^{-1} OH + CF3_3CH2_2OCClF2_2: kk = (1.6 ±\pm 0.6) ×\times 1012^{-12} exp( – 1100 ±\pm 125 K / T) cm3^3 molecule1^{-1} s1^{-1} Cl + CF3_3CH2_2OCHF2_2: kk = (6.1 ±\pm 1.4) ×\times 1012^{-12} exp( – 1830 ±\pm 90 K / T) cm3^3 molecule1^{-1} s1^{-1} Cl + CF3_3CHClOCHF2_2: kk = (7.8 ±\pm 2.6) ×\times 1011^{-11} exp( – 2980 ±\pm 130 K / T) cm3^3 molecule1^{-1} s1^{-1} Cl + CF3_3CH2_2OCClF2_2: kk = (2.2 ±\pm 0.2) ×\times 1011^{-11} exp( – 2700 ±\pm 40 K / T) cm3^3 molecule1^{-1} s1^{-1} The results are compared with those obtained previously for the same and related reactions of OH radicals and Cl atoms, and the atmospheric implications of the results are considered briefly

    Optical observations of a newly identified compact galaxy group near the Zone of Avoidance

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    We have identified a new group of galaxies, CG J0247+44.9, at low Galactic latitude (l=143.64 deg, b=-13.29 deg), which satisfies Hickson's criteria (Hickson 1997) for Compact Groups (CGs). Our group consists of six members, two of which are in close interaction (IRAS 02443+4437). We present here optical photometry (BVRI) and low resolution spectroscopy of the individual galaxies and investigate the global properties of the group. Our morphological analysis reveals that two out of the six objects are lenticular galaxies. The others are spirals showing emission lines in their spectra through which we could classify them as a starburst galaxy (the spiral member of the IRAS 02443+4437 close pair), a Seyfert 2, a LINER and a weak H II galaxy. Since the S0/Sa is the prevailing morphology for the galaxies of this group, which is also characterized by a short crossing time and a relatively high velocity dispersion, we suggest that CG J0247+44.9 is a dynamically old compact group.Comment: 17 pages, 5 figures out of which 4 are in jpg format. A postscript version of the paper including all figures is available at: http://astro.uibk.ac.at/~giovanna/preprints/Temporins.ps.gz Accepted for publication in Astronomy and Astrophysic

    To use constructed-response questions, or not to use constructed-response questions? that is the question

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    RePEc Working Paper Series: No. 69/2010Advocates of Constructed Response (CR) questions argue that CR questions provide a different assessment of student knowledge than is available from Multiple Choice (MC) questions. If that is the case, and if the benefit in terms of improved assessment is substantial, then it follows that grade outcomes using CR questions should be different from those using MC questions. We investigate this using a large dataset composed of individual assessment results from thousands of students in introductory economics classes at a large public university. Empirical analysis of our large sample of students indicates that a switch to an all-MC format would result in grade changes that are in the “small” to moderate range when compared to grade changes that occur between assessments. This evidence suggests that CR questions could be abandoned at relatively little cost in grading accuracy. However, there are other arguments in favour of keeping CR questions. In particular, it has been suggested that students perceive a mix of CR and MC as “fairer” than an assessment composed exclusively of one or the other question type. Further, some instructors believe that CR questions encourage students to study harder. We provide survey evidence that supports both arguments

    II. On the structure and biology of archotermopsis, together with descriptions of new species of intestinal protozoa, and general observations on the isoptera

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    The following paper is intended as a contribution towards a knowledge of the structure and biology of Archotermopsis wroughtoni, Desn., one of the most primitive of living Termites. Included herewith are also observations and deductions bearing upon some of the more important general biological problems which are associated with the Isoptera. Archotermopsis wroughtoni was described 12 years ago by Desneux from examples taken by Wroughton in June, 1903. They were discovered in old stumps of trees, chiefly Pinus excelsa, in the Kashmir Valley. Since its discovery, this species has remained a great rarity, and practically nothing had been ascertained concerning its biology. In June, 1910, I first came across this insect in a decaying fallen trunk of Pinus excelsa, in a forest area situated between the Kuari Pass and Ramni, at an altitude of about 8,500 feet, in the Himalayas of British Garwhal. In the same month during 1912 I had the good fortune to meet with it in great abundance in a dead fallen trunk of Pinus longifolia near Dharmoti, in the Ranikhet District. This locality is situated at an altitude of about 4,000 feet in the Kumaon Himalaya. Being aware of the biological and phylogenetic interest likely to be afforded by a study of this species, I made a prolonged search in many other likely localities in the North Western Himalayas during the years 1912-13. It was subsequently found plentifully at Bhowali, near Naini Tal, at an elevation of 5,800 feet, near Nadh in the Ohakrata District of Jaunsar, and I have also been able to procure examples from near Gulmerg in Kashmir. It seems probable, therefore, that it will eventually be found to be generally distributed in the lower-level coniferous forests of the North Western Himalayas, up to an elevation of about 9,000 feet

    Are you a researcher as well as a medical illustrator?

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    When we list the areas of practice for medical illustrators we always include research, but how involved in research are we? The aim of this activity is to encourage your professional development not just as a medical illustrator but your involvement with research whether that is undertaking your own research, undertaking evidence based practice (1) , working as part of a research team, advising researchers on the value of medical illustration or supporting a student undertaking a research project for their degree or post-graduate qualification

    A New Ultra-dense Group of Obscured Emission-Line Galaxies

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    We present the discovery of an isolated compact group of galaxies that is extremely dense (median projected galaxy separation: 6.9 kpc), has a very low velocity dispersion (σ2D\sigma_{\rm 2D} = 67 km s1^{-1}), and where all observed members show emission lines and are morphologically disturbed. These properties, together with the lack of spirals and the presence of a prominent tidal tail make this group one of the most evolved compact groups.Comment: 15 pages,LaTeX, 2figures. A Postscript figure with spectra is available at ftp://astro.uibk.ac.at/pub/weinberger/ . Accepted for publication in ApJ Letter

    Micronutrient deficiency following esophagectomy for cancer of the upper gastrointestinal tract

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    Objectives: For those patients who achieve long-term survival following esophagectomy, altered digestion and malabsorption may lead to a range of adverse gastrointestinal sequelae, including micronutrient deficiencies. The aim of the current study was to determine the prevalence of specific micronutrient deficiencies in patients following esophagectomy. Methods: Levels of vitamin A, vitamin E, vitamin D, vitamin B1, vitamin B12, folate, ferritin, zinc and calcium were measured in a single non-fasting blood sample in patients who has undergone esophagectomy. Findings were compared to both patients who had undergone gastrectomy and an age matched Western control population. Results: Forty-Four patients (33 male, 65.5 ± 10.2 yrs) a median of 26 months (IQR 12-46) following either two or three stage esophagectomy were recruited. Deficiency in one or more micronutrients was observed in 64% of patients who underwent esophagectomy. Micronutrients most commonly deficient following esophagectomy were vitamin D (21%), vitamin B12 (32%), ferritin (16%) and zinc (25%). Compared to patients who underwent gastrectomy, levels of vitamin B12 and red cell folate were significantly lower, and levels of vitamin E were significantly higher in the blood of patients following esophagetomy. Compared to a Western control population the mean levels of vitamins A, E, D and B12, ferritin and zinc were lower in patients following esophagectomy. Conclusion: Micronutrient deficiency is common after esophagectomy affecting two thirds of all patients. Regular screening of vitamin D, vitamin B12, ferritin and Zinc levels should be considered as well as prophylactic supplementation in this patient group to prevent deficiency
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