3,509 research outputs found

    An inertial velocity reference for the NASA airborne Doppler lidar

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    The following four tasks were studied: (1) modification of the calibration routines to calibrate the Inertial Measurement Unit gyroscope drifts with fixed platform heading; (2) modification of the calibration routines to calibrate the Inertial Measurement Unit accelerometers; (3) checking overall software again for errors; and (4) providing documentation on the above work describing changes to the present software, results of these changes and future operating procedures

    Preparatory studies of zero-g cloud drop coalescence experiment

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    Experiments to be performed in a weightless environment in order to study collision and coalescence processes of cloud droplets are described. Rain formation in warm clouds, formation of larger cloud drops, ice and water collision processes, and precipitation in supercooled clouds are among the topics covered

    Evaluation of data obtained from atmospheric laser Doppler velocimeter

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    The Doppler lidar velocimeter produces a variety of kinds of data. Besides the line of sight velocity components, there are the reflected amplitudes and the Doppler widths. Computer graphics software for displaying these data was produced. Different methods of presentation are needed for the various items. A picture was produced as pictures are often the best way to gain understanding. The individual lidar scans form a crosshatch pattern. Thus one-dimensional measurements fit together to form a two-dimensional whole. A pair of velocity measurements at a point combine to form a wind measurement with direction and magnitude. This gives a forest of wind vectors. The goal is to find a recognizable pattern to these trees. Often it is necessary to show only part of the information. That is, show only the wind direction not its magnitude or reduce the wind to streamlines of air flow. In other cases data are reduced to contour plots. Just enough contour lines are included to show the picture described

    Star Clusters in Virgo and Fornax Dwarf Irregular Galaxies

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    We present the results of a search for clusters in dwarf irregular galaxies in the Virgo and Fornax Cluster using HST WFPC2 snapshot data. The galaxy sample includes 28 galaxies, 11 of which are confirmed members of the Virgo and Fornax clusters. In the 11 confirmed members, we detect 237 cluster candidates and determine their V magnitudes, V-I colors and core radii. After statistical subtraction of background galaxies and foreground stars, most of the cluster candidates have V-I colors of -0.2 and 1.4, V magnitudes lying between 20 and 25th magnitude and core radii between 0 and 6 pc. Using H-alpha observations, we find that 26% of the blue cluster candidates are most likely HII regions. The rest of the cluster candidates are most likely massive (>10^4 Msol) young and old clusters. A comparison between the red cluster candidates in our sample and the Milky Way globular clusters shows that they have similar luminosity distributions, but that the red cluster candidates typically have larger core radii. Assuming that the red cluster candidates are in fact globular clusters, we derive specific frequencies (S_N) ranging from ~0-9 for the galaxies. Although the values are uncertain, seven of the galaxies appear to have specific frequencies greater than 2. These values are more typical of ellipticals and nucleated dwarf ellipticals than they are of spirals or Local Group dwarf irregulars.Comment: 46 pages, 14 figures, 3 tables, accepted by AJ. Higher quality PS version of entire paper available at http://www.astro.washington.edu/seth/dirr_gcs.htm

    Dynamical Friction in dE Globular Cluster Systems

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    The dynamical friction timescale for globular clusters to sink to the center of a dwarf elliptical galaxy (dE) is significantly less than a Hubble time if the halos have King-model or isothermal profiles and the globular clusters formed with the same radial density profile as the underlying stellar population. We examine the summed radial distribution of the entire globular cluster systems and the bright globular cluster candidates in 51 Virgo and Fornax Cluster dEs for evidence of dynamical friction processes. We find that the summed distribution of the entire globular cluster population closely follows the exponential profile of the underlying stellar population. However, there is a deficit of bright clusters within the central regions of dEs (excluding the nuclei), perhaps due to the orbital decay of these massive clusters into the dE cores. We also predict the magnitude of each dE's nucleus assuming the nuclei form via dynamical friction. The observed trend of decreasing nuclear luminosity with decreasing dE luminosity is much stronger than predicted if the nuclei formed via simple dynamical friction processes. We find that the bright dE nuclei could have been formed from the merger of orbitally decayed massive clusters, but the faint nuclei are several magnitudes fainter than expected. These faint nuclei are found primarily in M_V > -14 dEs which have high globular cluster specific frequencies and extended globular cluster systems. In these galaxies, supernovae-driven winds, high central dark matter densities, extended dark matter halos, the formation of new star clusters, or tidal interactions may act to prevent dynamical friction from collapsing the entire globular cluster population into a single bright nucleus.Comment: 15 pages, 2 tables, 7 figures; to appear in the Astrophysical Journal, April 20, 200

    Changes in rod and frame test scores recorded in schoolchildren during development--a longitudinal study.

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    The Rod and Frame Test has been used to assess the degree to which subjects rely on the visual frame of reference to perceive vertical (visual field dependence-independence perceptual style). Early investigations found children exhibited a wide range of alignment errors, which reduced as they matured. These studies used a mechanical Rod and Frame system, and presented only mean values of grouped data. The current study also considered changes in individual performance. Changes in rod alignment accuracy in 419 school children were measured using a computer-based Rod and Frame test. Each child was tested at school Grade 2 and retested in Grades 4 and 6. The results confirmed that children displayed a wide range of alignment errors, which decreased with age but did not reach the expected adult values. Although most children showed a decrease in frame dependency over the 4 years of the study, almost 20% had increased alignment errors suggesting that they were becoming more frame-dependent. Plots of individual variation (SD) against mean error allowed the sample to be divided into 4 groups; the majority with small errors and SDs; a group with small SDs, but alignments clustering around the frame angle of 18°; a group showing large errors in the opposite direction to the frame tilt; and a small number with large SDs whose alignment appeared to be random. The errors in the last 3 groups could largely be explained by alignment of the rod to different aspects of the frame. At corresponding ages females exhibited larger alignment errors than males although this did not reach statistical significance. This study confirms that children rely more heavily on the visual frame of reference for processing spatial orientation cues. Most become less frame-dependent as they mature, but there are considerable individual differences

    3D printing of medicines: Engineering novel oral devices with unique design and drug release characteristics

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    YesThree dimensional printing (3DP) was used to engineer novel oral drug delivery devices, with specialised design configurations loaded with multiple actives, with applications in personalised medicine. A filament extruder was used to obtain drug-loaded - paracetamol (acetaminophen) or caffeine - filaments of polyvinyl alcohol with characteristics suitable for use in fused-deposition modelling 3D printing. A multi-nozzle 3D printer enabled fabrication of capsule-shaped solid devices, containing paracetamol and caffeine, with different internal structures. The design configurations included a multilayer device, with each layer containing drug, whose identity was different from the drug in the adjacent layers; and a two-compartment device comprising a caplet embedded within a larger caplet (DuoCaplet), with each compartment containing a different drug. Raman spectroscopy was used to collect 2-dimensional hyper spectral arrays across the entire surface of the devices. Processing of the arrays using direct classical least squares component matching to produce false colour representations of distribution of the drugs showed clearly the areas that contain paracetamol and caffeine, and that there is a definitive separation between the drug layers. Drug release tests in biorelevant media showed unique drug release profiles dependent on the macrostructure of the devices. In the case of the multilayer devices, release of both drugs was simultaneous and independent of drug solubility. With the DuoCaplet design it was possible to engineer either rapid drug release or delayed release by selecting the site of incorporation of the drug in the device, and the lag-time for release from the internal compartment was dependent on the characteristics of the external layer. The study confirms the potential of 3D printing to fabricate multiple-drug containing devices with specialized design configurations and unique drug release characteristics, which would not otherwise be possible using conventional manufacturing methods.The full-text of this article will be released for public view at the end of the publisher embargo on 10 Oct 2016

    Babesia microti-like en un perro inmunocompetente

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    La babesiosis canina es una enfermedad infecciosa de distribución mundial causada por parásitos intraeritrocitarios transmitidos por garrapatas. Si bien ha sido tradicionalmente asumido que sólo dos de las 73 especies de babesias identificadas causan enfermedad en la especie canina, Babesia canis y Babesia gibsoni, recientes publicaciones demuestran que una tercera especie (Babesia microti-like) también puede parasitar a perros. Este último parásito, genéticamente relacionado con Babesia microti, es el origen de una enfermedad endémica entre la población canina del noroeste de España. Este trabajo presenta un caso no experimental de esta forma de Babesia microti-like en un perro cocker spaniel de 9 años, sin antecedentes de inmunodeficiencia ni de esplenectomía, que se presenta en la clínica veterinaria con signos de hipertermia, hemoglobinuria, escalofríos y apatía. Una muy intensa parasitemia (24%), junto con trombopenia y una acusada anemia hemolítica regenerativa fueron los hallazgos más caractéristicos. En la extensión de sangre periférica se visualizaron múltiples merozoitos intraeritrocitarios (parasitemia de un 24%) de pequeño tamaño (1-2 um) y presentación única en cada hematíe. Cuarenta y ocho horas después del comienzo de los síntomas, y tras tratamiento específico con dipropionato de imidocarb el perro evolucionó hacia la curación

    Aquatic community response to volcanic eruptions on the Ecuadorian Andean flank: evidence from the palaeoecological record

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    Aquatic ecosystems in the tropical Andes are under increasing pressure from human modification of the landscape (deforestation and dams) and climatic change (increase of extreme events and 1.5 °C on average temperatures are projected for AD 2100). However, the resilience of these ecosystems to perturbations is poorly understood. Here we use a multi-proxy palaeoecological approach to assess the response of aquatic ecosystems to a major mechanism for natural disturbance, volcanic ash deposition. Specifically, we present data from two Neotropical lakes located on the eastern Andean flank of Ecuador. Laguna Pindo (1°27.132′S–78°04.847′W) is a tectonically formed closed basin surrounded by a dense mid-elevation forest, whereas Laguna Baños (0°19.328′S–78°09.175′W) is a glacially formed lake with an inflow and outflow in high Andean Páramo grasslands. In each lake we examined the dynamics of chironomids and other aquatic and semi-aquatic organisms to explore the effect of thick (> 5 cm) volcanic deposits on the aquatic communities in these two systems with different catchment features. In both lakes past volcanic ash deposition was evident from four large tephras dated to c.850 cal year BP (Pindo), and 4600, 3600 and 1500 cal year BP (Baños). Examination of the chironomid and aquatic assemblages before and after the ash depositions revealed no shift in composition at Pindo, but a major change at Baños occurred after the last event around 1500 cal year BP. Chironomids at Baños changed from an assemblage dominated by Pseudochironomus and Polypedilum nubifer-type to Cricotopus/Paratrichocladius type-II, and such a dominance lasted for approximately 380 years. We suggest that, despite potential changes in the water chemistry, the major effect on the chironomid community resulted from the thickness of the tephra being deposited, which acted to shallow the water body beyond a depth threshold. Changes in the aquatic flora and fauna at the base of the trophic chain can promote cascade effects that may deteriorate the ecosystem, especially when already influenced by human activities, such as deforestation and dams, which is frequent in the high Andes
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