6,981 research outputs found

    After the games are over: life-history trade-offs drive dispersal attenuation following range expansion.

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    Increased dispersal propensity often evolves on expanding range edges due to the Olympic Village effect, which involves the fastest and fittest finding themselves together in the same place at the same time, mating, and giving rise to like individuals. But what happens after the ranges leading edge has passed and the games are over? Although empirical studies indicate that dispersal propensity attenuates following range expansion, hypotheses about the mechanisms driving this attenuation have not been clearly articulated or tested. Here, we used a simple model of the spatiotemporal dynamics of two phenotypes, one fast and the other slow, to propose that dispersal attenuation beyond preexpansion levels is only possible in the presence of trade-offs between dispersal and life-history traits. The Olympic Village effect ensures that fast dispersers preempt locations far from the ranges previous limits. When trade-offs are absent, this preemptive spatial advantage has a lasting impact, with highly dispersive individuals attaining equilibrium frequencies that are strictly higher than their introduction frequencies. When trade-offs are present, dispersal propensity decays rapidly at all locations. Our models results about the postcolonization trajectory of dispersal evolution are clear and, in principle, should be observable in field studies. We conclude that empirical observations of postcolonization dispersal attenuation offer a novel way to detect the existence of otherwise elusive trade-offs between dispersal and life-history traits

    Australian threshold quantities for ‘drug trafficking’: are they placing drug users at risk of unjustified sanction?

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    This study uses data on patterns of drug user consumption and purchasing to evaluate Australian legal threshold quantities to see whether Australian drug users are at risk of exceeding the thresholds for personal use alone. Introduction Drug trafficking in Australia is deemed a very serious offence, one for which legislators and courts have ruled general deterrence is paramount and ‘little mercy’ should be shown. A principal challenge has been how to effectively differentiate and sanction participants in the drug trade—particularly how to differentiate ‘traffickers’ from those who consume or purchase illicit drugs for personal use alone. To assist in this endeavour, all Australian states and territories have adopted legal thresholds that specify quantities of drugs over which offenders are either presumed to have possessed the drugs ‘for the purposes of supply’ and liable to sanction as ‘drug traffickers’ (up to 15 years imprisonment in most states), or in the case of Queensland, liable to sanctions equivalent to drug traffickers (up to 25 years imprisonment). Yet, in spite of known risks from adopting such thresholds, particularly of an unjustified conviction of a user as a trafficker, the capacity of Australian legal thresholds to deliver proportional sanctioning has been subject to limited research to date. This paper summarises key findings from a Criminology Research Grant funded project. The broader project examined this issue in two different ways—whether the thresholds are designed to filter traffickers from users and whether they enable appropriate sanctioning of traffickers of different controlled drugs. Herein, the focus is on the former—to what extent Australian legal thresholds unwittingly place users at risk of unjustified and disproportionate charge or sanction as traffickers

    Legacy effects of land cover and land use on painted turtle (Chrysemys picta) populations over a 20-year period in southeastern New Hampshire

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    More than half of all freshwater turtles and tortoises are threatened with extinction. Human land use practices and land cover conversion often decrease adult turtle survivorship and dampen the reproductive potential of turtle populations. The ability to make informed conservation and management decisions depends on understanding the relative impacts of different landscape contexts on turtle populations, and the spatial extent over which they have an impact. We surveyed painted turtle (Chrysemys picta) populations along an urbanization gradient in southeastern New Hampshire, USA to assess the relative impact of land cover, land use, and chemical contaminants on population density and sex ratio. We compared the findings from our comprehensive field surveys (2019-2021; “modern”) to earlier surveys (2001-2001; “historic”) conducted at identical and nearby ponds. In both time periods, population density increased with proportion of wetland and decreased with forest cover. Modern turtle density was best explained by historic land cover suggesting a lag between land cover change and a detectable impact on the population. Modern road length negatively influenced modern population density whereas historic road length did not have a measurable impact on density at that time. In both time periods we found increased forest cover associated with male-skewed populations. We tested 30 painted turtle blood sampled for 63 chemical contaminants. Organochlorine pesticides and synthetic pyrethroids were pervasive in turtle blood but not detected in water samples suggesting these chemicals are bioaccumulating in turtles despite low environmental concentrations. Our findings illustrate that effective management of turtle populations requires consideration of legacy effects of land use and land cover conversion as well as direct sources of mortality

    Exercises in general semantics for senior high school.

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    Leadership Self-efficacy of Students Participating in On-Campus Leadership Programming

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    Colleges and universities across the United States are facing continued pressure to meet enrollment and retention goals, as budgets continue to become more important, specifically, being performance-based. On-campus involvement has shown to have a positive influence on a student’s decision to stay at their particular institution and thus being retained. One area of on-campus involvement that has been identified is undergraduate leadership development programs. Students participating in an undergraduate leadership development program, such as assuming an on-campus leadership position often results in higher rates of student success. The purpose of this quantitative, cross-sectional study utilizing a correlational design via survey methods was to examine the leadership self-efficacy and engagement of undergraduate students that participated in on-campus leadership development opportunities, and explore some of the motivators and barriers to involvement in these programs. The responses to the survey revealed that female (77%) students participate in these programs at a much higher rate than male (20.7%), or non-binary (2.3%) students and that White (64.4%) students participate at a higher rate than non-White students (35.6%). Black (29.9%) students participated at the highest rate among non-white participants, followed by Asian (1.1%) and Native Hawaiian or Pacific Islander (1.1%). A theme that emerged with the contributing factors to participation was alignment with personal goals, with 74.7% of participants reported that as a contributing factor. A theme that emerged with the detracting factors to participation was lack of time to invest in the opportunity with 51.1% of participants reported that as a detracting factor. Exploring how the factors that contributed to and detracted from leadership development participation showed that contributing factors were a positive and significant predictor in leadership self-efficacy. For every one unit increase in contributing factors, leadership self-efficacy score increased by β - = .38 standard deviations. This study provides valuable information for leadership educators that work in student leadership programming. This study can encourages leadership educators to examine their own leadership development programs, and build recruitment strategies and programs that seek to increase engagement among student demographics such as male students, non-White students, and first-generation college students. Given that this study only examined students that participate in leadership programming, there were more insights on the factors that led them to participate in leadership programming. For future research, researchers could consider including students that did not participate in leadership programs to gain more valuable insights on the motivators and the barriers that students face to participating in leadership programs could be gathered. This information would be valuable to leadership educators as they try to grow their programs numerically, or grow access to their programs

    William Arbuthnot Lane (1856-1943): Surgical Innovator and His Theory of Autointoxication.

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    William Arbuthnot Lane contributed to the advancement of many fields of orthopedics, otolaryngology, and general surgery. He is credited for his no-touch technique and the invention of long-handled instruments, some of which are still in use today, to minimize tissue handling. He is most well known for his hypothesis that slowing of gastric contents could cause a variety of ailments and this became known as Lane\u27s disease. Although his surgical treatment of Lane\u27s disease is now defunct, it advanced the surgical technique in colorectal surgery. It seems likely that some of Lane\u27s autointoxication patients would be classified today as patients with colonic inertia, diverticulitis, colonic volvulus, and megacolon or, which are all treated with colectomy. Lane was a pioneer in multiple fields and a true general surgeon. He advanced colorectal surgery immensely and propelled the field of surgery into a new era

    The potential for Port 4.0 in a small Norwegian seaport - A case study of the Port of Kristiansand's container terminal

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    The Port and Maritime industry has since the 2010s undergone a significant digital transformation and is facing new challenges such as increased pressure regarding productivity, sustainability, as well as security and safety risks. This has, among other things, led to the development of smart ports. However, the adoption of automation has taken place in a slower pace than comparable sectors. Moreover, the literature related to smart port development in Norway is perceived as limited. Therefore, this study has attempted to elaborate a field of research to aid the port of Kristiansand and similar ports in Norway to develop into smart ports. The methodology of this thesis provides a qualitative approach for investigating the smart port potential in a small container terminal. Our study shows that the Port of Kristiansand is in an early stage towards a smart port status. Additionally, our findings indicate that there are substantial opportunities and potential for further development

    The potential for Port 4.0 in a small Norwegian seaport - A case study of the Port of Kristiansand’s container terminal

    Get PDF
    The Port and Maritime industry has since the 2010s undergone a significant digital transformation and is facing new challenges such as increased pressure regarding productivity, sustainability, as well as security and safety risks. This has, among other things, led to the development of smart ports. However, the adoption of automation has taken place in a slower pace than comparable sectors. Moreover, the literature related to smart port development in Norway is perceived as limited. Therefore, this study has attempted to elaborate a field of research to aid the port of Kristiansand and similar ports in Norway to develop into smart ports. The methodology of this thesis provides a qualitative approach for investigating the smart port potential in a small container terminal. Our study shows that the Port of Kristiansand is in an early stage towards a smart port status. Additionally, our findings indicate that there are substantial opportunities and potential for further development
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