1,596 research outputs found

    From Statehouse to Schoolhouse: Anti-Bullying Policy Efforts in U.S. States and School Districts

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    In 2011, 29.5 percent of U.S. public school districts didn't have anti-bullying policies, including many districts in states that require them, according to a report published by GLSEN. In states with such mandates, 26.3 percent of districts didn't have local policies. The report shows the gap that can emerge between the intentions of a law and the effectiveness of its implementation via policy and regulations

    Distribution and growth dynamics of invasive goldenrod (Solidago canadensis) in its introduced range in Estonia, and some Australian comparisons

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    Understanding the distribution and population dynamics of invasive plant species is fundamental to our capacity to appropriately predict and manage plant invasions. The invasion biology of non-native Solidago canadensis in Estonia was investigated for the first time by assessing its distribution patterns and growth dynamics. First, fifty-two peri-urban populations were surveyed, and population location, size, adjacent communities, number of shoots as well as shoot height were recorded. Then, thirty genets were excavated from previously surveyed populations in order to analyze their age and growth traits in the vicinity of Tartu. The majority of S. canadensis populations were small, i.e. occupying less than 50 m2, had 1 to 50 plants per population and were located predominantly on disturbed roadsides. The surveyed populations were young, with the average age of genets estimated to be five years at the time of sampling in 2006. We suggest that S. canadensis is well adapted to a wide range of habitats but predominantly occurs in human-disturbed habitats adjacent to settlements and roads. We found that Solidago canadensis genet age did not affect significantly its growth traits suggesting that growth traits are similar between younger and older genets

    Approaching invasive species in Madagascar

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    While a number of plants, animals, and insects in Madagascar have been called ’invasive’, the topic of invasive species has until recently received less attention here than in other island contexts. Some species, often alien to Madagascar and introduced by humans, have expanded their range rapidly and have had both negative and positive effects on landscapes, on native biodiversity, and on livelihoods. Examples include the prickly pear (raketa), the silver wattle (mimosa), and, recently, the Asian common toad (radaka boka). Building on a conceptual approach to ’invasive species’, this paper emphasizes the importance of inclusive and deliberative site- and population - specific management of invasive species. It analyses three separate concepts commonly used in definitions of invasion: the origin, behaviour, and effects of particular species. It places these concepts in their broader social and ecological context, with particular attention to local perspectives on invasive species. We illustrate these concepts with Malagasy examples and data. The examples demonstrate that while invasions can have dramatic consequences, there can be multiple, often competing, interests as well as site - specific biophysical, environmental, and cultural considerations that need to be taken into account when designing policy and management interventions. We conclude with a number of lessons learned

    Approaching invasive species in Madagascar

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    While a number of plants, animals, and insects in Madagascar have been called 'invasive', the topic of invasive species has until recently received less attention here than in other island contexts. Some species, often alien to Madagascar and introduced by humans, have expanded their range rapidly and have had both negative and positive effects on landscapes, on native biodiversity, and on livelihoods. Examples include the prickly pear (raketa), the silver wattle (mimosa), and, recently, the Asian common toad (radaka boka). Building on a conceptual approach to 'invasive species', this paper emphasizes the importance of inclusive and deliberative site- and population - specific management of invasive species. It analyses three separate concepts commonly used in definitions of invasion: the origin, behaviour, and effects of particular species. It places these concepts in their broader social and ecological context, with particular attention to local perspectives on invasive species. We illustrate these concepts with Malagasy examples and data. The examples demonstrate that while invasions can have dramatic consequences, there can be multiple, often competing, interests as well as site - specific biophysical, environmental, and cultural considerations that need to be taken into account when designing policy and management interventions. We conclude with a number of lessons learned. RESUME FRANCAIS Contrairement à la plupart des autres îles, et en dépit du qualificatif 'invasif' rattaché depuis longtemps à certaines espèces qui s'y sont naturalisées, les réflexions autour de l'approche des espèces invasives à Madagascar demeurent récentes. L'opuntia (Opuntia spp.) figure certes parmi les plus anciens exemples d'espèces traités dans la littérature sur les invasions biologiques. Mais ce n'est vraiment qu'avec le retentissement médiatique autour de la détection en 2011 de la présence du crapaud masqué (Duttaphrynus melanostictus) et la recherche d'une parade appropriée que s'est affirmée la nécessité de traiter cette question des espèces invasives en tant que telle. Une posture nativiste et uniforme qui ignorerait la spécificité des contextes biophysiques et socio - économiques locaux, mais aussi la pluralité des formes d'invasion biologique et des défi- nitions qui s'y rattachent, ne saurait être privilégiée. L'article montre qu'il s'agit de situer les réflexions dans un contexte insulaire socio - économique dans lequel les espèces allogènes tiennent depuis longtemps une large place. Il défend en outre la nécessité d'envisager les espèces invasives non pas selon une forme de perception unique et autoritariste, mais selon une diversité de points de vue, conforme aux conflits d'intérêts qui se manifestent parfois, et mettant plutôt en avant le caractère exogène des espèces invasives, leurs effets (négatifs, mais aussi positifs) sur le milieu, ou leur mode de fonctionnement (disper- sion, dominance) dans des contextes spécifiques et locaux. Il convient en particulier d'observer qu'aux coûts générés par les invasions biologiques peuvent s'ajouter des bénéfices économiques, et que les impacts écologiques néfastes peuvent se combiner avec des incidences heureuses, y compris auprès d'espèces indigènes en situation critique. En outre, le point de vue des populations humaines, leur connaissance d'espèces invasives quotidiennement rencontrées, leur réticence à scin- der le vivant en espèces indigènes et allogène, mais aussi leur vision pragmatique, ne sauraient être mésestimés, et moins encore oubliés. Enfin, l'article invite à prendre du recul face aux effets rhétoriques liés aux discours conventionnels sur les inva- sions biologiques, à éviter les amalgames et les généralisations excessives, à tenir compte des contraintes environnementales mais aussi des aspirations socio - économiques des populations locales, et à prendre en compte la diversité des spécificités locales, qu'elles soient biophysiques ou sociales. En conclusion, il est sans doute heureux que Madagascar n'ait rejoint que très récemment la mouvance internationale des réflexions sur les espèces invasives : cela lui permet en effet d'être en mesure de disposer d'une position équilibrée, déjouant certains discours catastrophistes, et préférant une approche résolument contextualisée, à l'échelle nationale comme aux échelles régionales

    Twenty Years of Timing SS433

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    We present observations of the optical ``moving lines'' in spectra of the Galactic relativistic jet source SS433 spread over a twenty year baseline from 1979 to 1999. The red/blue-shifts of the lines reveal the apparent precession of the jet axis in SS433, and we present a new determination of the precession parameters based on these data. We investigate the amplitude and nature of time- and phase-dependent deviations from the kinematic model for the jet precession, including an upper limit on any precessional period derivative of P˙<5×105\dot P < 5 \times 10^{-5}. We also dicuss the implications of these results for the origins of the relativistic jets in SS433.Comment: 21 pages, including 9 figures. To appear in the Astrophysical Journa

    Background Check:A General Technique to Build More Reliable and Versatile Classifiers

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    Chance long-distance or human-mediated dispersal? How Acacia s.l. farnesiana attained its pan-tropical distribution

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    Acacia s.l. farnesiana, which originates from Mesoamerica, is the most widely distributed Acacia s.l. species across the tropics. It is assumed that the plant was transferred across the Atlantic to southern Europe by Spanish explorers, and then spread across the Old World tropics through a combination of chance long-distance and human-mediated dispersal. Our study uses genetic analysis and information from historical sources to test the relative roles of chance and human-mediated dispersal in its distribution. The results confirm the Mesoamerican origins of the plant and show three patterns of human- mediated dispersal. Samples from Spain showed greater genetic diversity than those from other Old World tropics, suggesting more instances of transatlantic introductions from the Americas to that country than to other parts of Africa and Asia. Individuals from the Philippines matched a population from South Central Mexico and were likely to have been direct, trans-Pacific introductions. Australian samples were genetically unique, indicating that the arrival of the species in the continent was independent of these European colonial activities. This suggests the possibility of pre-European human- mediated dispersal across the Pacific Ocean. These significant findings raise new questions for biogeographic studies that assume chance or transoceanic dispersal 2 for disjunct plant distributions

    OAO-3 end of mission tests report

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    Twelve engineering type tests were performed on several subsystems and experiment(s) of the OAO 3 spacecraft near its end of mission. The systems tested include: Princeton experiment package (PEP), fine error system guidance, inertial reference unit, star trackers, heat pipes, thermal control coatings, command and data handling, solar array; batteries, and onboard processor/power boost regulator. Generally, the systems performed well for the 8 1/2 years life of OAO 3, although some degradation was noted in the sensitivity of PEP and in the absorptivity of the skin coatings. Battery life was prolonged during the life of the mission in large part by carefully monitoring the charge-discharge cycle with careful attention not to overcharge

    Large-Scale Sunyaev-Zel'dovich Effect: Measuring Statistical Properties with Multifrequency Maps

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    We study the prospects for extracting detailed statistical properties of the Sunyaev-Zel'dovich (SZ) effect associated with large scale structure using upcoming multifrequency CMB experiments. The greatest obstacle to detecting the large-angle signal is the confusion noise provided by the primary anisotropies themselves, and to a lesser degree galactic and extragalactic foregrounds. We employ multifrequency subtraction techniques and the latest foregrounds models to determine the detection threshold for the Boomerang, MAP (several microK) and Planck CMB (sub microK) experiments. Calibrating a simplified biased-tracer model of the gas pressure off recent hydrodynamic simulations, we estimate the SZ power spectrum, skewness and bispectrum through analytic scalings and N-body simulations of the dark matter. We show that the Planck satellite should be able to measure the SZ effect with sufficient precision to determine its power spectrum and higher order correlations, e.g. the skewness and bispectrum. Planck should also be able to detect the cross correlation between the SZ and gravitational lensing effect in the CMB. Detection of these effects will help determine the properties of the as yet undetected gas, including the manner in which the gas pressure traces the dark matter.Comment: 13 ApJ pages, 11 figures; typos and figure 5 revised; submitted to Ap
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