2,440 research outputs found

    Ranking the importance of nuclear reactions for activation and transmutation events

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    Pathways-reduced analysis is one of the techniques used by the Fispact-II nuclear activation and transmutation software to study the sensitivity of the computed inventories to uncertainties in reaction cross-sections. Although deciding which pathways are most important is very helpful in for example determining which nuclear data would benefit from further refinement, pathways-reduced analysis need not necessarily define the most critical reaction, since one reaction may contribute to several different pathways. This work examines three different techniques for ranking reactions in their order of importance in determining the final inventory, comparing the pathways based metric (PBM), the direct method and one based on the Pearson correlation coefficient. Reasons why the PBM is to be preferred are presented.Comment: 30 pages, 10 figure

    Quantitative Genomics of Aggressive Behavior in Drosophila melanogaster

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    Aggressive behavior is important for animal survival and reproduction, and excessive aggression is an enormous social and economic burden for human society. Although the role of biogenic amines in modulating aggressive behavior is well characterized, other genetic mechanisms affecting this complex behavior remain elusive. Here, we developed an assay to rapidly quantify aggressive behavior in Drosophila melanogaster, and generated replicate selection lines with divergent levels of aggression. The realized heritability of aggressive behavior was approximately 0.10, and the phenotypic response to selection specifically affected aggression. We used whole-genome expression analysis to identify 1,539 probe sets with different expression levels between the selection lines when pooled across replicates, at a false discovery rate of 0.001. We quantified the aggressive behavior of 19 mutations in candidate genes that were generated in a common co-isogenic background, and identified 15 novel genes affecting aggressive behavior. Expression profiling of genetically divergent lines is an effective strategy for identifying genes affecting complex traits

    Age Determination by Back Length for African Savanna Elephants: Extending Age Assessment Techniques for Aerial-Based Surveys

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    Determining the age of individuals in a population can lead to a better understanding of population dynamics through age structure analysis and estimation of age-specific fecundity and survival rates. Shoulder height has been used to accurately assign age to free-ranging African savanna elephants. However, back length may provide an analog measurable in aerial-based surveys. We assessed the relationship between back length and age for known-age elephants in Amboseli National Park, Kenya, and Addo Elephant National Park, South Africa. We also compared age- and sex-specific back lengths between these populations and compared adult female back lengths across 11 widely dispersed populations in five African countries. Sex-specific Von Bertalanffy growth curves provided a good fit to the back length data of known-age individuals. Based on back length, accurate ages could be assigned relatively precisely for females up to 23 years of age and males up to 17. The female back length curve allowed more precise age assignment to older females than the curve for shoulder height does, probably because of divergence between the respective growth curves. However, this did not appear to be the case for males, but the sample of known-age males was limited to ≤27 years. Age- and sex-specific back lengths were similar in Amboseli National Park and Addo Elephant National Park. Furthermore, while adult female back lengths in the three Zambian populations were generally shorter than in other populations, back lengths in the remaining eight populations did not differ significantly, in support of claims that growth patterns of African savanna elephants are similar over wide geographic regions. Thus, the growth curves presented here should allow researchers to use aerial-based surveys to assign ages to elephants with greater precision than previously possible and, therefore, to estimate population variables

    A school-based intervention to promote physical activity among adolescent girls: Rationale, design, and baseline data from the Girls in Sport group randomised controlled trial

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    Background: Physical activity levels decline markedly among girls during adolescence. School-based interventions that are multi-component in nature, simultaneously targeting curricular, school environment and policy, and community links, are a promising approach for promoting physical activity. This report describes the rationale, design and baseline data from the Girls in Sport group randomised trial, which aims to prevent the decline in moderate-to-vigorous intensity physical activity (MVPA) among adolescent girls. Methods/design: A community-based participatory research approach and action learning framework are used with measurements at baseline and 18-month follow-up. Within each intervention school, a committee develops an action plan aimed at meeting the primary objective (preventing the decline in accelerometer-derived MVPA). Academic partners and the State Department of Education and Training act as critical friends. Control schools continue with their usual school programming. 24 schools were matched then randomized into intervention (n = 12) and control (n = 12) groups. A total of 1518 girls (771 intervention and 747 control) completed baseline assessments (86% response rate). Useable accelerometer data (≥ 10 hrs/day on at least 3 days) were obtained from 79% of this sample (n = 1199). Randomisation resulted in no differences between intervention and control groups on any of the outcomes. The mean age (SE) of the sample was 13.6 (± 0.02) years and they spent less than 5% of their waking hours in MVPA (4.85 ± 0.06). Discussion: Girls in Sport will test the effectiveness of schools working towards the same goal, but developing individual, targeted interventions that bring about changes in curriculum, school environment and policy, and community links. By using community-based participatory research and an action learning framework in a secondary school setting, it aims to add to the body of literature on effective school-based interventions through promoting and sustaining increased physical activity participation among adolescent girls

    Larger females have more calves: influence of maternal body length on fecundity in North Atlantic right whales

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    © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Stewart, J., Durban, J., Europe, H., Fearnbach, H., Hamilton, P., Knowlton, A., Lynn, M., Miller, C., Perryman, W., Tao, B., & Moore, M. Larger females have more calves: influence of maternal body length on fecundity in North Atlantic right whales. Marine Ecology Progress Series, 689, (2022): 179–189, https://doi.org/10.3354/meps14040.North Atlantic right whales (NARW) are critically endangered and have been declining in abundance since 2011. In the past decade, human-caused mortalities from vessel strikes and entanglements have been increasing, while birth rates in the population are at a 40 yr low. In addition to declining abundance, recent studies have shown that NARW length-at-age is decreasing due to the energetic impacts of sub-lethal entanglements, and that the body condition of the population is poorer than closely related southern right whales. We examined whether shorter body lengths are associated with reduced fecundity in female NARW. We compared age-corrected, modeled metrics of body length with 3 metrics of fecundity: age at first reproduction, average inter-birth interval, and the number of calves produced per potential reproductive year. We found that body length is significantly related to birth interval and calves produced per reproductive year, but not age at first reproduction. Larger whales had shorter inter-birth intervals and produced more calves per potential reproductive year. Larger whales also had higher lifetime calf production, but this was a result of larger whales having longer potential reproductive spans, as body lengths have generally been declining over the past 40 yr. Declining body sizes are a potential contributor to low birth rates over the past decade. Efforts to reduce entanglements and vessel strikes could help maintain population viability by increasing fecundity and improving resiliency of the population to other anthropogenic and climate impacts.Funding to the New England Aquarium for curation of the photo-identification catalog is provided by NOAA Contract 1305M2- 18-P-NFFM-0108

    The Floor of Yellowstone Lake is Anything but Quiet—New Discoveries from High-Resolution Sonar Imaging, Seismic- Reflection Profiling, and Submersible Studies

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    Discoveries from multibeam sonar mapping and seis-mic-reflection surveys of Yellowstone Lake provide new insight into the recent geologic forces that have shaped a large lake at the active front of the Yellowstone hot spot, a region strongly affected by young (\u3c2 \u3em.y.), large-volume (\u3e100–1,000s km3) silicic volcanism, active tectonism, and accompanying uplift. Specifically, our mapping has identified the extent of postcaldera-collapse volcanism and active hydrothermal processes occurring above a large magma chamber beneath the lake floor. Multiple advances and recessions of thick glacial ice have overlapped volcanic and hydrothermal activity leaving a lake basin that has been shaped predominantly by fire and ice. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic,and sedimentary processes. Detailed bathymetric, seismic-reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake morphology and localization of hydrothermal activity in the northern, West Thumb, and central basins. Many previously unknown features have been identified and include more than 660 hydrothermal vents, several very large (\u3e500-m diameter) hydrothermal-explosion craters, many small hydrothermal-vent craters (~1-to 200-m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting postglacial sediments, siliceous hydrothermal-spire structures, sublacustrine landslide deposits, submerged former shorelines, large glacial melting features, incipient faulting along the trace of the Eagle Bay fault zone, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal-explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem

    The Floor of Yellowstone Lake is Anything but Quiet—New Discoveries from High-Resolution Sonar Imaging, Seismic- Reflection Profiling, and Submersible Studies

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    Discoveries from multibeam sonar mapping and seis-mic-reflection surveys of Yellowstone Lake provide new insight into the recent geologic forces that have shaped a large lake at the active front of the Yellowstone hot spot, a region strongly affected by young (\u3c2 \u3em.y.), large-volume (\u3e100–1,000s km3) silicic volcanism, active tectonism, and accompanying uplift. Specifically, our mapping has identified the extent of postcaldera-collapse volcanism and active hydrothermal processes occurring above a large magma chamber beneath the lake floor. Multiple advances and recessions of thick glacial ice have overlapped volcanic and hydrothermal activity leaving a lake basin that has been shaped predominantly by fire and ice. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic,and sedimentary processes. Detailed bathymetric, seismic-reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake morphology and localization of hydrothermal activity in the northern, West Thumb, and central basins. Many previously unknown features have been identified and include more than 660 hydrothermal vents, several very large (\u3e500-m diameter) hydrothermal-explosion craters, many small hydrothermal-vent craters (~1-to 200-m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting postglacial sediments, siliceous hydrothermal-spire structures, sublacustrine landslide deposits, submerged former shorelines, large glacial melting features, incipient faulting along the trace of the Eagle Bay fault zone, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal-explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem
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