869 research outputs found

    Estimating vote-specific preferences from roll-call data using conditional autoregressive priors

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    Ideal point estimation in political science usually aims to reduce a matrix of votes to a small number of preference dimensions. We argue that taking a non-parametric perspective can yield measures that are more useful for some subsequent analyses. We propose a conditional autoregressive preference measurement model, which we use to generate case-specific preference estimates for US Supreme Court justices from 1946 to 2005. We show that the varying relative legal positions taken by justices across areas of law condition the opinion assignment strategy of the Chief Justice and the decisions of all justices as to whether to join the majority opinion. Unlike previous analyses that have made similar claims, using case-specific preference estimates enables us to hold constant the justices involved, providing stronger evidence that justices are strategically responsive to each others' relative positions on a case-by-case basis rather than simply their identities or average relative preferences

    The Car Sharer\u27s Companion: An Owner\u27s Manual for Car Sharing in Portland, Oregon

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    So, you want to start a car sharing organization. The Car Sharer\u27s Companion, researched and written by the team members of CarShare Cascadia Mobility Consultants, is your handbook and resource guide for starting a car sharing organization in Portland, Oregon. After your operation mobilizes, the Companion can continue to serve as a reference. It comes in two parts. Part I: An Ignition Guide presents the steps to start up a car sharing operation. Its four chapters cover how to build and incorporate your organization, how to find and serve a market for car sharing, what decisions to make in investment and insurance, and a what strategies to use for managing the operation. The Ignition Guide encourages you with evidence that, once knowing how, where, with whom to start an car sharing\u27 organization, you can develop an economically feasible, convenient, and marketable enterprise in Portland. The handbook format includes information, advice, and italicized illustrative case studies. Part II: A Resource Guide is useful for when you seek more in-depth information about the subjects discussed in Part I. It provides a subject index and an annotated bibliography to the sources that inform this handbook. Moreover, it provides a list of potential car sharers--the beginnings ofa network in Portland. Section I ofthe Resource Guide presents the subject-by-subject resource directory. Its subjects match the four chapters in the Ignition Guide above. For instance, after reading about the best corporate structure in section 1-2 of Chapter 1: Mobilizing Your Organization in the handbook, you can turn to the section 1-2 of the resource directory to find an index of sources on corporate form. Section II of the Resource guide is not arranged by subject. It is an alphabetized, fully annotated source bibliography. Sources include a variety of interviews, meetings, correspondences, and also annotated literature entries that support our findings. Finally, we have provided a glossary ofthe key car sharing concepts that drive the mobility sharing movement. Read these on the following page to prime yourself for your journey into the wonderful world of car sharing. And believe us, it is truly a beautiful place. So turn that page and twist that ignition key. Let\u27s hit the road

    Research and Practice in K-12 Online Learning: A Review of Open Access Literature

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    The literature related to online learning programs for K-12 students dates to the mid-1990s and builds upon a century of research and practice from K-12 distance education. While K-12 online learning programs have evolved and grown over the past decade, the amount of published research on virtual schooling practice and policy is limited. The current literature includes practitioner reports and experimental and quasi-experimental studies, both published and unpublished. This paper reviews open access literature in K-12 online learning and reports on a structured content analysis of the documents. Themes in the literature include steady growth and a focus on the benefits, challenges, and broad effectiveness of K-12 online learning. In addition, newly developed standards for K-12 online learning are emerging in descriptions of effective practices

    Physical characteristics explain ball-carrying capability in sub-elite rugby union players.

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    The aims of the present study were two-fold: (i) to investigate the relationship between physical characteristics and the game statistics associated with ball-carrying capability amongst sub-elite rugby union players; and (ii) to predict the level of change in these physical characteristics required to improve the associated game statistic via regression analysis. Thirty-eight senior professional players (forwards, n = 22; backs, n = 16) were assessed for body mass (BM), back squat (BS) single-repetition maximum (1RM) normalised to BM (1RM/BM), 10 m sprint velocity (S10), 10 m sprint momentum (SM10), and the game statistics from 22 games within the 2019/20 RFU Championship season. The relationship between these measures and the predicted level of change in a physical measure required to improve the total number of the associated game statistic by one were assessed by Pearson's correlation coefficient and simple regression analyses. In forwards, an ~ 11.5% reduction in BM, an ~ 11.8% improvement in BS 1RM/BM, or an ~ 11.5% increase in S10 was required to improve the game statistics associated with ball-carrying capability. In backs, a ~ 19.3% increase in BM or a ~ 15.6% improvement in SM10 was required. These findings demonstrate that improvements in lower-body relative strength, acceleration performance, and position-specific alterations in body mass are required to maximise the ball-carrying capability and therefore match outcome of sub-elite rugby union players

    Excluding Nontarget Species from Brown Tree Snake, \u3ci\u3eBoiga irregularis\u3c/i\u3e (Reptilia: Colubridae), Bait Stations: Experimental Tests of Station Design and Placement

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    Bait stations with toxic baits are an emerging technology for eradication of the invasive brown tree snake (Boiga irregularis) on Guam, yet potential interferences by nontarget species are largely unknown. We tested the efficacies of three bait station designs together with three commonly used station support structures to exclude nonnative rats (roof rat, Rattus rattus; Norway rat, Rattus norvegicus; Polynesian rat, Rattus exulans) and native coconut crabs (Birgus latro). When directly presented, all species readily consumed the dead neonatal mouse baits (nontoxic) including those replicating decomposing baits in the field. When bait stations were made easily accessible by placement near ground level, all rat species were able to enter all station types, but some individual roof rats and Norway rats exhibited apparent neophobia. When stations were placed up on support structures, simulating those in the field (~1 m above ground level), numbers of station accessions by roof rats and Norway rats remained essentially unchanged, but Polynesian rats then showed almost no inclination to enter stations. However, ability to access entrances of stations ( but not interiors) when on support structures was extremely high for roof rats and appreciable for the other rat species, including Polynesians. The station type currently in widest use, when placed on chain-link cyclone fence, had the highest probability of accession. Crabs readily accessed station entrances but never interiors. The two downward-angled station designs, when placed in simulated vegetation, had the lowest probabilities of accession. In areas where nontarget species are a concern, we recommend use of either of the downward-angled station designs and suspension from vegetation wherever possible

    Excluding Nontarget Species from Brown Tree Snake, \u3ci\u3eBoiga irregularis\u3c/i\u3e (Reptilia: Colubridae), Bait Stations: Experimental Tests of Station Design and Placement

    Get PDF
    Bait stations with toxic baits are an emerging technology for eradication of the invasive brown tree snake (Boiga irregularis) on Guam, yet potential interferences by nontarget species are largely unknown. We tested the efficacies of three bait station designs together with three commonly used station support structures to exclude nonnative rats (roof rat, Rattus rattus; Norway rat, Rattus norvegicus; Polynesian rat, Rattus exulans) and native coconut crabs (Birgus latro). When directly presented, all species readily consumed the dead neonatal mouse baits (nontoxic) including those replicating decomposing baits in the field. When bait stations were made easily accessible by placement near ground level, all rat species were able to enter all station types, but some individual roof rats and Norway rats exhibited apparent neophobia. When stations were placed up on support structures, simulating those in the field (~1 m above ground level), numbers of station accessions by roof rats and Norway rats remained essentially unchanged, but Polynesian rats then showed almost no inclination to enter stations. However, ability to access entrances of stations ( but not interiors) when on support structures was extremely high for roof rats and appreciable for the other rat species, including Polynesians. The station type currently in widest use, when placed on chain-link cyclone fence, had the highest probability of accession. Crabs readily accessed station entrances but never interiors. The two downward-angled station designs, when placed in simulated vegetation, had the lowest probabilities of accession. In areas where nontarget species are a concern, we recommend use of either of the downward-angled station designs and suspension from vegetation wherever possible

    Adult acclimation to combined temperature and pH stressors significantly enhances reproductive outcomes compared to short-term exposures

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    1.This study examined the effects of long-term culture under altered conditions on the Antarctic sea urchin, Sterechinus neumayeri. 2.Sterechinus neumayeri was cultured under the combined environmental stressors of lowered pH (−0·3 and −0·5 pH units) and increased temperature (+2 °C) for 2 years. This time-scale covered two full reproductive cycles in this species and analyses included studies on both adult metabolism and larval development. 3.Adults took at least 6–8 months to acclimate to the altered conditions, but beyond this, there was no detectable effect of temperature or pH. 4.Animals were spawned after 6 and 17 months exposure to altered conditions, with markedly different outcomes. At 6 months, the percentage hatching and larval survival rates were greatest in the animals kept at 0 °C under current pH conditions, whilst those under lowered pH and +2 °C performed significantly less well. After 17 months, performance was not significantly different across treatments, including controls. However, under the altered conditions urchins produced larger eggs compared with control animals. 5.These data show that under long-term culture adult S. neumayeri appear to acclimate their metabolic and reproductive physiology to the combined stressors of altered pH and increased temperature, with relatively little measureable effect. They also emphasize the importance of long-term studies in evaluating effects of altered pH, particularly in slow developing marine species with long gonad maturation times, as the effects of altered conditions cannot be accurately evaluated unless gonads have fully matured under the new conditions

    Adult acclimation to combined temperature and pH stressors significantly enhances reproductive outcomes compared to short-term exposures

    Get PDF
    This study examined the effects of long-term culture under altered conditions on the Antarctic sea urchin, Sterechinus neumayeri. Sterechinus neumayeri was cultured under the combined environmental stressors of lowered pH (−0·3 and −0·5 pH units) and increased temperature (+2 °C) for 2 years. This time-scale covered two full reproductive cycles in this species and analyses included studies on both adult metabolism and larval development. Adults took at least 6–8 months to acclimate to the altered conditions, but beyond this, there was no detectable effect of temperature or pH. Animals were spawned after 6 and 17 months exposure to altered conditions, with markedly different outcomes. At 6 months, the percentage hatching and larval survival rates were greatest in the animals kept at 0 °C under current pH conditions, whilst those under lowered pH and +2 °C performed significantly less well. After 17 months, performance was not significantly different across treatments, including controls. However, under the altered conditions urchins produced larger eggs compared with control animals. These data show that under long-term culture adult S. neumayeri appear to acclimate their metabolic and reproductive physiology to the combined stressors of altered pH and increased temperature, with relatively little measureable effect. They also emphasize the importance of long-term studies in evaluating effects of altered pH, particularly in slow developing marine species with long gonad maturation times, as the effects of altered conditions cannot be accurately evaluated unless gonads have fully matured under the new conditions
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