24,216 research outputs found

    Variability and polarization in the inner jet of 3C395

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    We present new results on the parsec-scale jet of the quasar 3C395, derived from VLBI polarization sensitive observations made in 1995.91 and 1998.50 at 8.4, 15.4 and 22.2 GHz. The observations show a complex one-sided jet extending up to 20 mas, with a projected magnetic field essentially aligned with the radio jet. The emission is strongly dominated, in total intensity and polarization, by the core and the inner jet region (of ~3 mas length). We have studied the details of this dominant region finding clear structural variations during this ~2.5 years period, in contrast with the apparent quietness of the jet structure inferred from lower resolution VLBI observations. We observe the ejection of a new component from the core and variations in the degree of polarization of the inner jet components. We estimate a high Faraday Rotation Measure close to the core, with a strong decrease along the inner jet.Comment: 7 pages, 4 figures, A&A in pres

    The Galactic cosmic-ray Sun shadow observed by HAWC

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    The magnetic field of the Solar corona is difficult to measure directly. However, indirect observations of the solar corona are possible using the deficit in flux of cosmic rays coming from the direction of the Sun. Low-energy cosmic rays (~GeV) are deflected by the inner magnetic field of the Sun and the interplanetary magnetic field frozen into the solar wind. In contrast, high-energy cosmic rays (~TeV and above) are absorbed in the Sun's photosphere producing a shadow in the Sun's nominal position viewed from Earth. Several ground-based instruments have observed the effects of the heliospheric magnetic field on the size of the sun shadow and its position. The High-Altitude Water Cherenkov Observatory (HAWC) is an air shower array located in the central region of Mexico that observes TeV cosmic rays at a rate of about 15 kHz. in this work, we present preliminary images of the sun shadow from data collected by HAWC during 2013 and 2014 for different energy ranges.Comment: Presented at the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. See arXiv:1508.03327 for all HAWC contribution

    The Serotonin Transporter Polymorphism (5-HTTLPR) and Alcohol Problems in Heavy Drinkers: Moderation by Depressive Symptoms.

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    Heavy alcohol use in young adults has been prospectively associated with a host of psychosocial and alcohol-related problems. Recent studies have supported the interaction between serotonin transporter polymorphism and adverse environmental factors, as a predictor of alcohol use and the development of alcohol dependence. The current study examined the role of depressive symptoms in combination with the serotonin transporter polymorphism as a predictor of alcohol use and alcohol-related problems. Results revealed a significant genotype by depressive symptom interaction, such that heavier alcohol use was associated with depressive symptoms in L allele homozygotes but not among S allele carriers. These results remained significant after controlling for ethnicity and gender effects. These findings extend the emerging literature supporting 5-HTTLPR genotype as a risk factor for alcohol-related problems in the context of co-occurring symptoms of depression

    Visible spatial contiguity of social information and reward affects social learning in brown capuchins (<i>Sapajus apella</i>) and children (<i>Homo sapiens</i>)

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    Animal social learning is typically studied experimentally by the presentation of artificial foraging tasks. Although productive, results are often variable even for the same species. We present and test the hypothesis that one cause of variation is that spatial distance between rewards and the means of reward release causes conflicts for participants’ attentional focus. We investigated whether spatial contiguity between a visible reward and the means of release would affect behavioral responses that evidence social learning, testing 21 brown capuchins (Sapajus apella), a much studied species with variant evidence for social learning, and 180 two- to four-year old human children (Homo sapiens), a benchmark species known for a strong social learning disposition. Participants were presented with a novel transparent apparatus where a reward was either proximal or distal to a demonstrated means of releasing it. A distal reward location decreased attention towards the location of the demonstration and impaired subsequent success in gaining rewards. Generally, the capuchins produced the alternative method to that demonstrated whereas children copied the method demonstrated, although a distal reward location reduced copying in younger children. We conclude that some design features in common social learning tasks may significantly degrade the evidence for social learning. We have demonstrated this for two different primates but suggest that it is a significant factor to control for in social learning research across all taxa

    A profile of the Monterey squid fleet in 1992

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    There were approximately 20 vessels active in the 1992 Monterey Bay squid fishery. The size of the fleet has not changed since the early 1970's when 15 to 20 vessels participated in the fishery. Since 1977, eleven steel hulled vessels have been added to the fleet, replacing smaller wooden hulled vessels that were in use during the 1960's. The hold capacity of the new fleet remains about 800 tons, because the new larger vessels replaced small vessels that used lighters (20 - 25 ton capacity non-motorized barges). Purse seines were legalized in 1989 and have replaced lamparas which were in use during the 1960'S and 1970's. Seines used in the squid fishery are small and shallow, ranging from 120 to 200 fm in length with most less than 25 fm deep. Crew size has been reduced nearly 50% by the addition of net reels, power blocks, submersible fish pumps, and vacuum pumps used for unloading at dockside. In the 1970's flasher type fathometers were used by the fleet and few vessels had navigational aids. Today most of the fleet have sonar, radar, and loran C. Three vessels carry global positioning systems. In 1988 squid attracting lights were legalized and the entire fleet used lights during the 1992 season. (21pp.

    Relationship between tonic and phasic craving for alcohol.

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    BackgroundMultiple measures are utilized to assess alcohol craving, often interchangeably. Little is known about the relationship between tonic and phasic craving. This study fills this gap in the literature by examining the association between tonic levels of alcohol craving and phasic craving for alcohol that is provoked by alcohol administration.MethodsForty-three non-treatment seeking problem drinkers underwent an initial interview and two laboratory testing sessions, where either alcohol or a saline placebo was administered intravenously. Tonic craving was assessed via the Penn Alcohol Craving Scale (PACS) and Obsessive Compulsive Drinking Scale (OCDS) at the initial interview. Phasic craving was assessed during the laboratory sessions (i.e., alcohol and saline administrations, single blinded) at baseline and at 3 subsequent breath alcohol concentrations (0.02, 0.04, and 0.06 g/dl).ResultsThere was a main effect of PACS in predicting phasic craving across both saline and alcohol administration conditions (p &lt; 0.05). The OCDS was predictive of phasic craving when alcohol, but not saline, was administered (p = 0.058); the obsessive subscale (p = 0.01), but not the compulsive subscale (p &gt; 0.10), predicted phasic craving during alcohol, as compared to saline administration.ConclusionIn sum, tonic craving captured by the OCDS was predictive of phasic craving during alcohol administration whereas the PACS more generally captured the increase in phasic craving. Therefore, these measures of tonic craving may function differently in capturing the experience of phasic craving. Implications for the utilization of the PACS and OCDS as well as assessments of craving in alcoholism research are discussed
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