2,577 research outputs found

    Using an Aerial Drone to Examine Lateral Movement in Sweep Rowers

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    Rowing is a sport that is performed on the water, because of this there are many challenges associated with studying rowing. The primary challenges are an inability to control the environment and limitations with the equipment that can be used to collect data on the water. In order to try and overcome some of these challenges an aerial drone fitted with a high resolution camera was used to examine an understudied element of the rowing stroke, lateral movement in sweep rowers. Oar and shoulder angles and lateral movement of the shoulders and hands were calculated and compared between five different eight person rowing boats. Rowers were found to lean and rotate towards the oar side of the boat. More experienced and larger athletes had longer oar arcs, however, these differences did not necessarily extend to shoulder angle and lateral lean. Individual rowers were also observed to have their own individual styles of movement particularly in the shoulders. Further research needs to be performed to both examine lean and twist in a sweep rowing stroke and to evaluate the utility of drones as data collection tools

    Alien Registration- Munn, Fred S. (Portland, Cumberland County)

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    https://digitalmaine.com/alien_docs/21909/thumbnail.jp

    The PPMXL catalog of positions and proper motions on the ICRS. Combining USNO-B1.0 and 2MASS

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    USNO-B1.0 and 2MASS are the most widely used full-sky surveys. However, 2MASS has no proper motions at all, and USNO-B1.0 published only relative, not absolute (i.e. on ICRS) proper motions. We performed a new determination of mean positions and proper motions on the ICRS system by combining USNO-B1.0 and 2MASS astrometry. This catalog is called PPMXL {VO-access to the catalog is possible via http://vo.uni-hd.de/ppmxl}, and it aims to be complete from the brightest stars down to about V20V \approx 20 full-sky. PPMXL contains about 900 million objects, some 410 million with 2MASS photometry, and is the largest collection of ICRS proper motions at present. As representative for the ICRS we chose PPMX. The recently released UCAC3 could not be used because we found plate-dependent distortions in its proper motion system north of -20^\circ declination. UCAC3 served as an intermediate system for δ20\delta \leq -20^\circ. The resulting typical individual mean errors of the proper motions range from 4 mas/y to more than 10 mas/y depending on observational history. The mean errors of positions at epoch 2000.0 are 80 to 120 mas, if 2MASS astrometry could be used, 150 to 300 mas else. We also give correction tables to convert USNO-B1.0 observations of e.g. minor planets to the ICRS system.Comment: 9 pages, 9 figure

    Synthesis and characterisation of metal-organic framework materials with carboxylate ligands

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    The adsorption of various guest molecules by the flexible 1,4-benzenedicarboxylate metal-organic framework (MOF), MIL-53, has been followed using in situ diffraction techniques. This crystalline MOF displays a structural expansion upon the adsorption of guest molecules, evident by a change in unit cell parameters, which allows adsorption to be followed using diffraction techniques. Adsorption studies were performed with the Fe(III) form of MIL-53 using both liquidand gas-phase guest molecules. The results from in situ X-ray diffraction (XRD) studies show that small aliphatic-alcohols give rise to a two-step expansion whereas branchedalcohols and larger aromatic molecules result in only a one-step expansion. The solvent used for liquid phase studies was shown to affect guest adsorption; benzothiophene and benzothiazole were adsorbed more quickly from a solution of heptane than from a solution of isopropanol. Gas phase studies were used to investigate the effect of occluded water molecules inside the pores of the framework upon the adsorption of methanol. A combination of XRD, thermogravimetry and inelastic neutron scattering studies were used to show that methanol does not displace water when hydrated MIL- 53(Fe) is used as an adsorbent. Two equivalents of methanol can be packed inside the pores of the framework, irrespective of the adsorbent being hydrated or dehydrated. Eight linker-modified MIL-53(Al) materials were supplied by research partners and in situ XRD studies were performed to reveal the effect of the modifications upon the adsorption of gas-phase molecules. The results show that the linkers change the behaviour of the material towards certain guest molecules and the most dramatic effect was seen when the benzene ring of the linker was replaced by cyclohexane. A series of cobalt (II) MOFs synthesised with carboxylate and pyridine-N-oxide linkers is presented. The effect of functionalising the pyridine ring upon the topology of the resulting framework was studied. Resonance and steric effects were found to influence the structure of the final product. One of the new materials has the potential to be used as an adsorbent due to a 3D porous structure

    The heritability of premenstrual syndrome

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    We aimed to determine (1) the prevalence of premenstrual syndrome in a sample of twins and (2) the relative contribution of genes and environment in premenstrual syndrome. A group of 193 subjects inclusive of same gender twins (n = 176) and females from opposite sex twin sets (n = 17) entered the study. Heritability analysis used same gender twin data only. The probandwise concordance rate for the presence or absence of premenstrual syndrome was calculated and the heritability of premenstrual syndrome was assessed by a quantitative genetic model fitting approach using MX software. The prevalence of premenstrual syndrome was 43.0% and 46.8% in monozygotic and dizygotic twins, respectively. The probandwise concordance for premenstrual syndrome was higher in monozygotic (0.81) than in dizygotic twins (0.67), indicating a strong genetic effect. Quantitative genetic modeling found that a model comprising of additive genetic (A) and unique environment (E) factors provided the best fit (A: 95%, E: 5%). No association was found between premenstrual symptom and the following variables: belonging to the opposite gender twin set, birth weight, being breast fed and vaccination. These results established a clear genetic influence in premenstrual syndrome

    Sensible heat loss from Muskoxen (Ovibos moschatus) feeding in winter: small calves are not at a thermal disadvantage compared with adult cows

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    Muskoxen (Ovibos moschatus) are large (\u3e200 kg adult body mass) mammalian herbivores that overwinter in the polar regions. Calves are around one-third the body mass of mature females and may be expected to suffer greater thermal stresses in winter compared with adults because the ratio of surface area to volume (SA : vol) is much greater for calves than for adults. We found that during feeding bouts, when animals are fully exposed to environmental conditions, calves did lose sensible (dry) heat more readily than adults (W m(-2)) in still air conditions. However, calves and cows lost less than 2%-6% of their estimated daily digestible energy intake as conductive, convective, and radiant heat losses accumulated during feeding bouts. More important, calves did not lose relatively more heat than larger adults in terms of sensible losses as part of their daily energy intake. Coat surface temperatures were only 2 degrees-5 degrees C above ambient even when air temperature fell to -40 degrees C. Body temperatures recorded deep within the ear canal near the tympanum fluctuated in both cows and calves. Muskoxen combine peripheral heterothermy and an exceptional winter coat to minimize sensible heat loss in winter. These mechanisms appear to have circumvented some of the thermal problems normally associated with a high SA : vol ratio in calves, which reflects the strong selection to conserve energy in winter

    Cross-Identification of Stars with Unknown Proper Motions

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    The cross-identification of sources in separate catalogs is one of the most basic tasks in observational astronomy. It is, however, surprisingly difficult and generally ill-defined. Recently Budav\'ari & Szalay (2008) formulated the problem in the realm of probability theory, and laid down the statistical foundations of an extensible methodology. In this paper, we apply their Bayesian approach to stars that, we know, can move measurably on the sky, with detectable proper motion, and show how to associate their observations. We study models on a sample of stars in the Sloan Digital Sky Survey, which allow for an unknown proper motion per object, and demonstrate the improvements over the analytic static model. Our models and conclusions are directly applicable to upcoming surveys such as PanSTARRS, the Dark Energy Survey, Sky Mapper, and the LSST, whose data sets will contain hundreds of millions of stars observed multiple times over several years.Comment: 10 pages, 5 figure

    The High-Order-Multiplicity of Unusually Wide M-dwarf Binaries: Eleven New Triple and Quadruple Systems

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    M-dwarfs in extremely wide binary systems are very rare, and may thus have different formation processes from those found as single stars or close binaries in the field. In this paper we search for close companions to a new sample of 36 extremely wide M-dwarf binaries, covering a spectral type range of M1 to M5 and a separation range of 600 - 6500 AU. We discover 10 new triple systems and one new quadruple system. We carefully account for selection effects including proper motion, magnitude limits, the detection of close binaries in the SDSS, and other sample biases. The bias-corrected total high-order-multiple fraction is 45% (+18%/-16%) and the bias-corrected incidence of quadruple systems is < 5%, both statistically compatible with that found for the more common close M-dwarf multiple systems. Almost all the detected companions have similar masses to their primaries, although two very low mass companions, including a candidate brown dwarf, are found at relatively large separations. We find that the close-binary separation distribution is strongly peaked towards < 30AU separations. There is marginally significant evidence for a change in high-order M-dwarf multiplicity with binding energy and total mass. We also find 2-sigma evidence of an unexpected increased high-order-multiple fraction for the widest targets in our survey, with a high-order-multiple fraction of 21% (+17%/-7%) for systems with separations up to 2000AU, compared to 77% (+9%/-22%) for systems with separations > 4000AU. These results suggest that the very widest M-dwarf binary systems need higher masses to form or to survive.Comment: 11 pages, 14 figures, accepted for publication in Ap

    Modulation of Tumor Tolerance in Primary Central Nervous System Malignancies

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    Central nervous system tumors take advantage of the unique immunology of the CNS and develop exquisitely complex stromal networks that promote growth despite the presence of antigen-presenting cells and tumor-infiltrating lymphocytes. It is precisely this immunological paradox that is essential to the survival of the tumor. We review the evidence for functional CNS immune privilege and the impact it has on tumor tolerance. In this paper, we place an emphasis on the role of tumor-infiltrating myeloid cells in maintaining stromal and vascular quiescence, and we underscore the importance of indoleamine 2,3-dioxygenase activity as a myeloid-driven tumor tolerance mechanism. Much remains to be discovered regarding the tolerogenic mechanisms by which CNS tumors avoid immune clearance. Thus, it is an open question whether tumor tolerance in the brain is fundamentally different from that of peripheral sites of tumorigenesis or whether it simply stands as a particularly strong example of such tolerance
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