3,886 research outputs found

    Large scale correlations of quasar polarisation vectors: Hints of extreme scale structures?

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    A survey measuring quasar polarization vectors has been started in two regions towards the North and South Galactic Poles. Here, We review the discovery of significant correlations of orientations of polarization vectors over huge angular distances. We report new results including a larger sample of the quasars confirming the existence of coherent orientations at redshifts z>1.Comment: Proc. of Astronomical Polarimetry - Current Status and Future Directions March 15-19, 2004. Waikoloa Beach Marriott, Hawaii. 5 pages, 3 figure

    The Influence of oral environment on diet choices in goats: a focus on saliva protein composition

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    There is ample evidence that ruminants are capable of making choices between different foods that provide a more balanced diet that would be obtained by eating at random. In the particular case of goats, they occupy a diversity of habitats and different breeds present variability of feeding behaviors resultant from adaptations to the existent plant species. In their food search activity, individuals are faced with variable amounts of plant secondary metabolites (PSMs), which may present some toxic and anti-nutritional effects depending on the individual’s ability to deal with it. The oral cavity has a key role in the recognition and decision processes of ingestion or rejection. In this chapter we will first consider how goats identify foods and behave according to the food items available. Focus will be done on the importance of taste sense in this process and the information available on the main structures involved in taste detection and perception in goats will be reviewed. In a second section we will focus on the characteristics of goat’s saliva, particularly in terms of their protein composition, presenting results obtained by our research team

    Hubble Space Telescope Observations of Comet 9P/Tempel 1 during the Deep Impact Encounter

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    We report on the Hubble Space Telescope program to observe periodic comet 9P/Tempel 1 in conjunction with NASA's Deep Impact mission. Our objectives were to study the generation and evolution of the coma resulting from the impact and to obtain wide-band images of the visual outburst generated by the impact. Two observing campaigns utilizing a total of 17 HST orbits were carried out: the first occurred on 2005 June 13-14 and fortuitously recorded the appearance of a new, short-lived fan in the sunward direction on June 14. The principal campaign began two days before impact and was followed by contiguous orbits through impact plus several hours and then snapshots one, seven, and twelve days later. All of the observations were made using the Advanced Camera for Surveys (ACS). For imaging, the ACS High Resolution Channel (HRC) provides a spatial resolution of 36 km (16 km/pixel) at the comet at the time of impact. Baseline images of the comet, made prior to impact, photometrically resolved the comet's nucleus. The derived diameter, 6.1 km, is in excellent agreement with the 6.0 +/- 0.2 km diameter derived from the spacecraft imagers. Following the impact, the HRC images illustrate the temporal and spatial evolution of the ejecta cloud and allow for a determination of its expansion velocity distribution. One day after impact the ejecta cloud had passed out of the field-of-view of the HRC.Comment: 15 pages, 14 postscript figures. Accepted for publication in Icarus special issue on Deep Impac

    Ensemble Properties of Comets in the Sloan Digital Sky Survey

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    We present the ensemble properties of 31 comets (27 resolved and 4 unresolved) observed by the Sloan Digital Sky Survey (SDSS). This sample of comets represents about 1 comet per 10 million SDSS photometric objects. Five-band (u,g,r,i,z) photometry is used to determine the comets' colors, sizes, surface brightness profiles, and rates of dust production in terms of the Af{\rho} formalism. We find that the cumulative luminosity function for the Jupiter Family Comets in our sample is well fit by a power law of the form N(< H) \propto 10(0.49\pm0.05)H for H < 18, with evidence of a much shallower fit N(< H) \propto 10(0.19\pm0.03)H for the faint (14.5 < H < 18) comets. The resolved comets show an extremely narrow distribution of colors (0.57 \pm 0.05 in g - r for example), which are statistically indistinguishable from that of the Jupiter Trojans. Further, there is no evidence of correlation between color and physical, dynamical, or observational parameters for the observed comets.Comment: 19 pages, 8 tables, 11 figures, to appear in Icaru

    Photometry of cometary nuclei: Rotation rates, colours and a comparison with Kuiper Belt Objects

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    We present time-series data on Jupiter Family Comets (JFCs) 17P/Holmes, 47P/Ashbrook-Jackson and 137P/Shoemaker-Levy 2. In addition we also present results from `snap-shot' observations of comets 43P/Wolf-Harrington, 44P/Reinmuth 2, 103P/Hartley 2 and 104P/Kowal 2 taken during the same run. The comets were at heliocentric distances of between 3 and 7 AU at this time. We present measurements of size and activity levels for the snap-shot targets. The time-series data allow us to constrain rotation periods and shapes, and thus bulk densities. We also measure colour indices (V-R) and (R-I) and reliable radii for these comets. We compare all of our findings to date with similar results for other comets and Kuiper Belt Objects (KBOs). We find that the rotational properties of nuclei and KBOs are very similar, that there is evidence for a cut-off in bulk densities at ~ 0.6 g cm^{-3} in both populations, and the colours of the two populations show similar correlations. For JFCs there is no observational evidence for the optical colours being dependant on either position in the orbit or on orbital parameters.Comment: 15 pages, 19 figures, accepted for publication in MNRA

    Large granular lymphocyte leukemia (LGL) in a child with hyper IgM syndrome and autoimmune hemolytic anemia

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    We describe a female with a history of autosomal recessive hyper-IgM (HIGM) syndrome along with a history of autoimmune hemolytic anemia and intermittent lymphadenopathy. She subsequently developed neutropenia, lymphocyostosis and mild thrombocytopenia. Flow cytometry of the peripheral blood revealed the presence of a marked predominance of cytotoxic T lymphocytes, shown to be clonal, with concomitant natural killer (NK) antigen expression. She responded to weekly methotrexate therapy. Pediatr Blood Cancer 2008;50:142–145. © 2006 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/57398/1/20902_ftp.pd

    Differences in salivary α-amylase levels among women with different taste sensitivities

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    Saliva is the main component of taste receptor cells external environment, and consequently it may have a decisive role in taste perception. Taste sensitivity varies among different individuals. Sensitivity to the compound n-6-propylthiouracil (PROP) has been considerably studied and besides the known influence of genetic background, the contribution of perireceptor environment is not completely clear yet. Salivary α-amylase (one of the main proteins of saliva) is involved in carbohydrate digestion and its enzymatic activity may change the levels of sugars present in the mouth, influencing food perception. To evaluate differences in salivary total protein content and α-amylase activity and expression among individuals with different PROP taste sensitivities. Sixty seven female women (18-30 years old) were classified in one of the three groups of taste sensitivity (non-taster, medium-taster or super-taster), according to the perceived intensity for PROP, using Labeled Magnitude Scales. Saliva was collected without stimulation. Flow rate was calculated by dividing total volume for the 5 minutes collection. Bradford method was used for total protein assessment. Dinitrosalicylic acid assay was used for measuring the starch-hydrolyzing activity of salivary α-amylase, while the expression of this enzyme was evaluated by Wester blot. 20,9% of the subjects were classified as non-taters. The three groups presented similar saliva flow rates and total protein content was not significantly different although a tendency for lower protein concentration in medium-tasters individuals was observed. Salivary α-amylase activity (U/min) was higher in supertasters (P<0,05). Salivary α-amylase activity (U/min) was higher in super-tasters (P<0,05) without any significant differences in expression. In women individual differences in saliva composition can contribute to the different taste sensitivity. One of the differences appears to be α-amylase enzymatic activity. The reason for this deserves to be elucidated, as well as the potential involvement of others salivary proteins
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