448 research outputs found

    Negative evidence on negative evidence.

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    Effects of visual obstruction, prey resources, and satiety on bird use of simulated airport grasslands

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    Grasslands represent 39%–50% of U.S. airport properties, and a recent management framework recommended exploiting both antipredator behaviours and food resources in airport grasslands to curb use by birds considered hazardous to aviation safety. We evaluated framework predictions empirically by exposing unsated and sated brown-headed cowbirds (Molothrus ater) to visually obstructive (∼13-cm vegetation height; tall), higher-risk plots versus unobstructive (height; short) plots, and relative to prey resources. We predicted that 1) unsated birds (unfed since the previous day) would be present in greater numbers and forage more in short than tall vegetation plots 24 h post-mowing because of invertebrate flush resulting from mowing; 2) unsated birds would show increasing numbers and foraging in tall plots \u3e24 h post-mowing because of decreasing food abundance and availability in short plots; and 3) sated birds would be present in greater numbers and forage more in short vegetation overall, because vigilance needs would exceed that of food needs. We evaluated effects of visual obstruction (a metric correlated with both vegetation height and insect density) on behaviours within plots via generalized linear mixed models. Unsated cowbirds showed nearly equal numbers in tall and short plots (X [SE] individuals using tall plots: 9.5 [5.1]; short plots: 9.8 [5.1], P = 1.00, Wilcoxon Signed Ranks Test), and foraged nearly equally in both plots 24 h post-mowing (tall plots: 6.9 [4.7] individuals; short plots: 6.6 [4.1] individuals, P = 0.94). Prey availability was likely enhanced within short plots within 24 h of mowing, but possibly in adjacent tall plots as well. Over the course of the experiments (8–9 days) unsated cowbirds showed no difference in numbers between plots (tall plots: 8.2 [4.9] individuals; short plots: 11.4 [4.9] individuals, P = 0.13), but foraged more in short plots (tall plots: 4.4 [3.8] individuals; short plots: 7.8 [4.2] individuals, P = 0.01); visual obstruction was significantly and negatively correlated with foraging in tall plots. Sated cowbirds selected for short plots (use of tall plots: 5.9 [4.2] individuals; short plots: 11.7 [4.6] individuals, P \u3c 0.01; foraging in tall plots: 4.1 [3.3] individuals; short plots: 8.2 [4.6] individuals, P \u3c 0.01). Our findings support recommendations for use of visually obstructive vegetation in combination with proactive control of food resources to reduce use of airport grasslands by birds that select against visually obstructive cover

    Negative evidence on negative evidence.

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    Dramatic Plays as a Tool to Educate Young African-American Females about HIV/AIDS

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    Rates of HIV/AIDS transmission have increased substantially, particularly among young African American women. According to the Centers for Disease Control and Prevention (CDC), HIV/AIDS is the number one killer for African American women aged 25 to 34. Given that many of these young women are contracting the disease in their late teens and early twenties, there is a need to develop interventions that directly address the needs of this group. The current study sought to assess the effectiveness of theater in increasing knowledge of HIV/AIDS and the likelihood of healthier sexual behavior and choices among 219 young African American women 18 to 39 years of age. Paired sample t-tests revealed that there were significant mean differences in knowledge and intended safe sex behavior after viewing the play. Young women who viewed the play reported increased knowledge of HIV and reported a higher likelihood of engaging in safer sex. Given the high rates of HIV/AIDS among young African American women, more innovative educational and prevention techniques are needed

    Mesocorticolimbic monoamine correlates of methamphetamine sensitization and motivation.

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    Methamphetamine (MA) is a highly addictive psychomotor stimulant, with life-time prevalence rates of abuse ranging from 5-10% world-wide. Yet, a paucity of research exists regarding MA addiction vulnerability/resiliency and neurobiological mediators of the transition to addiction that might occur upon repeated low-dose MA exposure, more characteristic of early drug use. As stimulant-elicited neuroplasticity within dopamine neurons innervating the nucleus accumbens (NAC) and prefrontal cortex (PFC) is theorized as central for addiction-related behavioral anomalies, we used a multi-disciplinary research approach in mice to examine the interactions between sub-toxic MA dosing, motivation for MA and mesocorticolimbic monoamines. Biochemical studies of C57BL/6J (B6) mice revealed short- (1 day), as well as longer-term (21 days), changes in extracellular dopamine, DAT and/or D2 receptors during withdrawal from 10, once daily, 2 mg/kg MA injections. Follow-up biochemical studies conducted in mice selectively bred for high vs. low MA drinking (respectively, MAHDR vs. MALDR mice), provided novel support for anomalies in mesocorticolimbic dopamine as a correlate of genetic vulnerability to high MA intake. Finally, neuropharmacological targeting of NAC dopamine in MA-treated B6 mice demonstrated a bi-directional regulation of MA-induced place-conditioning. These results extend extant literature for MA neurotoxicity by demonstrating that even subchronic exposure to relatively low MA doses are sufficient to elicit relatively long-lasting changes in mesocorticolimbic dopamine and that drug-induced or idiopathic anomalies in mesocorticolimbic dopamine may underpin vulnerability/resiliency to MA addiction

    Depression and suicide literacy among Canadian sexual and gender minorities

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    The purpose of this study was to examine and compare depression and suicide literacy among Canadian sexual and gender minorities (SGM). Online surveys comprised of the 22-item depression literacy scale (D-LIT) and the 12-item literacy of suicide scale (LOSS) were completed by 2,778 individuals identifying as SGM. Relationships between depression and suicide literacy and demographic characteristics were evaluated using multivariable linear regression. Overall, SGM correctly answered 71.3% of the questions from the D-LIT and 76.5% of the LOSS. D-LIT scores were significantly lower among cisgender men and D-LIT and LOSS scores were lower among transgender women when compared to cisgender women. LOSS and D-LIT scores were significantly lower among SGM without a university degree (compared to those with a university degree) and among SGM from ethnic minority groups (compared to White SGM). D-LIT scores, but not LOSS scores, were significantly lower among Indigenous SGM compared to White SGM. The findings provide evidence of differences in suicide and depression literacy between SGM subgroups along multiple social axes. Interventions to increase depression and suicide literacy should be prioritized as part of a mental health promotion strategy for SGM, targeting subgroups with lower literacy levels, including cisgender men, transgender women, Indigenous people, racialized minorities, and those without a university degree

    Annex 6: Changing Ocean Impacts on the Key Forage Fish Species Arctic Cod in the Western Canadian Arctic – Linking Climate Model Projections to Subsistence Fisheries

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    This annex highlights the results of a study focusing on the potential impacts of ocean acidification and other climate- related stressors on marine species relevant for subsistence fisheries in the Western Arctic Bioregion. The study uses a knowledge co-production approach developed in the form of a multi-step process based on a combination of modelling and analysis tools including the Scientific Method and Indigenous Traditional Knowledge (Figure A6.1). Once all steps have been completed, uncertainties can be estimated and improvements can be made either with respect to the individual steps or to the linkages between them. The process can then be repeated, including those improvements to provide a revised assessment with reduced uncertainty ranges. The steps can be summarized as follows: (1) analyze past observed trends; (2) perform projection simulations with global and regional climate models, allowing trend estimates on 20–50 year timescales; (3) assess physiological responses and thresholds in marine species via literature research, Indigenous Traditional Knowledge, observations and focused laboratory experiments; (4) add trends, climate model projections and physiological response data to species distribution / habitat suitability and higher trophic level Ecosim/ Ecopath (see Section A6.3) models; (5) assess socio-economic impacts by applying bio-economic models, evaluating current fishery-economic activities, and discussion with communities/ community representatives; and (6) review law and governance. The latter addresses adaptation measures on global, regional and national scales. This annex describes the first application of the multi-step framework in the Western Arctic Bioregion. At this point in time all the required tools have been developed, but not all components have been adequately linked. For example, while higher resolution model projections are available for the area the habitat suitability and economic models are still driven by global climate models, the Ecopath model (see Section on The Beaufort Sea food web model) has not yet been run into the future and physiological responses are reflected in the higher trophic level models to a limited extent, if at all. In addition, while collaboration with local communities has been established (see Section on Community interests), Indigenous Traditional Knowledge has been included to a very limited extent. To summarize, this case study provides an assessment that includes all required tools, but limited linkages. It has a strong focus on uncertainty analyses and the identification of gaps in knowledge. Particular emphasis is given to the key forage fish species Arctic cod (Boreogadus saida), since climate model projections can be linked more directly to key forage species than to the (mostly) higher trophic level species harvested

    Stability of Satellite Planes in M31 II: Effects of the Dark Subhalo Population

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    The planar arrangement of nearly half the satellite galaxies of M31 has been a source of mystery and speculation since it was discovered. With a growing number of other host galaxies showing these satellite galaxy planes, their stability and longevity have become central to the debate on whether the presence of satellite planes are a natural consequence of prevailing cosmological models, or represent a challenge. Given the dependence of their stability on host halo shape, we look into how a galaxy plane's dark matter environment influences its longevity. An increased number of dark matter subhalos results in increased interactions that hasten the deterioration of an already-formed plane of satellite galaxies in spherical dark halos. The role of total dark matter mass fraction held in subhalos in dispersing a plane of galaxies present non trivial effects on plane longevity as well. But any misalignments of plane inclines to major axes of flattened dark matter halos lead to their lifetimes being reduced to < 3 Gyrs. Distributing > 40% of total dark mass in subhalos in the overall dark matter distribution results in a plane of satellite galaxies that is prone to change through the 5 Gyr integration time period.Comment: 11 pages, 9 figures, accepted to MNRAS September 22 201

    Reading related white matter structures in adolescents are influenced more by dysregulation of emotion than behavior

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    Mood disorders and behavioral are broad psychiatric diagnostic categories that have different symptoms and neurobiological mechanisms, but share some neurocognitive similarities, one of which is an elevated risk for reading deficit. Our aim was to determine the influence of mood versus behavioral dysregulation on reading ability and neural correlates supporting these skills in youth, using diffusion tensor imaging in 11- to 17-year-old children and youths with mood disorders or behavioral disorders and age-matched healthy controls. The three groups differed only in phonological processing and passage comprehension. Youth with mood disorders scored higher on the phonological test but had lower comprehension scores than children with behavioral disorders and controls; control participants scored the highest. Correlations between fractional anisotropy and phonological processing in the left Arcuate Fasciculus showed a significant difference between groups and were strongest in behavioral disorders, intermediate in mood disorders, and lowest in controls. Correlations between these measures in the left Inferior Longitudinal Fasciculus were significantly greater than in controls for mood but not for behavioral disorders. Youth with mood disorders share a deficit in the executive-limbic pathway (Arcuate Fasciculus) with behavioral-disordered youth, suggesting reduced capacity for engaging frontal regions for phonological processing or passage comprehension tasks and increased reliance on the ventral tract (e.g., the Inferior Longitudinal Fasciculus). The low passage comprehension scores in mood disorder may result from engaging the left hemisphere. Neural pathways for reading differ mainly in executive-limbic circuitry. This new insight may aid clinicians in providing appropriate intervention for each disorder
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