138 research outputs found

    Markovian Monte Carlo program EvolFMC v.2 for solving QCD evolution equations

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    We present the program EvolFMC v.2 that solves the evolution equations in QCD for the parton momentum distributions by means of the Monte Carlo technique based on the Markovian process. The program solves the DGLAP-type evolution as well as modified-DGLAP ones. In both cases the evolution can be performed in the LO or NLO approximation. The quarks are treated as massless. The overall technical precision of the code has been established at 0.05% precision level. This way, for the first time ever, we demonstrate that with the Monte Carlo method one can solve the evolution equations with precision comparable to the other numerical methods.Comment: 38 pages, 9 Postscript figure

    College Student Adjustment: Examination Of Personal And Environmental Characteristics

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    This study used a multi-dimensional model of college adjustment to examine the relationships between multiple layers of personal influences and college adjustment (academic, social, personal/emotional, attachment to the institution, and overall adjustment) among emerging adults in a large urban university. The sample included 177 undergraduate students, ages 18-25, attending Wayne State University, who completed on-line questionnaires. Race and cumulative college GPA were related to academic adjustment. Being Arabic/Middle-Eastern was a consistent predictor of college adjustment. It was found that higher college GPA and being White was related to higher academic adjustment, while being Arabic/Middle-Eastern was related to lower academic adjustment. College GPA was the only personal/demographic variable predicting social adjustment. A positive relationship was found between the self-reported social class and the personal-emotional adjustment. Being Arabic/Middle-Eastern, first generation college student, or on-campus living, were related to a lower sense of attachment to the institution, while higher college GPA was related to higher levels of attachment. Higher GPA was related to higher overall adjustment, while being Arabic/Middle Eastern was associated with lower overall adjustment. The perceived classroom comfort was positively related to all aspects of college adjustment. The number of hours spent socializing with students outside of class was positively related to social adjustment, attachment to the institution, and the overall adjustment. Current family obligations were related to stronger attachment to the institution as well as the overall adjustment. Lastly, conflict between school and family responsibilities was related to lower college adjustment scores. It would be helpful for university officials to pay special attention to students of various ethnic/racial backgrounds and first generation college students when designing special programs for students at-risk. In addition, enhancing classroom experiences could improve students\u27 adjustment. Lastly, support should be provided to students who are struggling with managing the conflict between family and school responsibilities

    Food Mass Reduction Trade Study

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    Future long duration manned space flights beyond low earth orbit will require the food system to remain safe, acceptable, and nutritious while efficiently balancing appropriate vehicle resources such as mass, volume, power, water, and crewtime. Often, this presents a challenge since maintaining the quality of the food system can result in a higher mass and volume. The Orion vehicle is significantly smaller than the Shuttle vehicle and the International Space Station and the mass and volume available for food is limited. Therefore, the food team has been challenged to reduce the mass of the packaged food from 1.82 kg per person per day to 1.14 kg per person per day. Past work has concentrated on how to reduce the mass of the packaging which contributes to about 15% of the total mass of the packaged food system. Designers have also focused on integrating and optimizing the Orion galley equipment as a system to reduce mass. To date, there has not been a significant effort to determine how to reduce the food itself. The objective of this project is to determine how the mass and volume of the packaged food can be reduced while maintaining caloric and hydration requirements. The following tasks are the key elements to this project: (1) Conduct further analysis of the ISS Standard Menu to determine moisture, protein, carbohydrate, and fat levels. (2) Conduct trade studies to determine how to bring the mass of the food system down. Trade studies may include removing the water of the total food system and/or increasing the fat content. (3) Determine the preferred method for delivery of the new food (e.g. bars, or beverages) and the degree of replacement. (4) Determine whether there are commercially available products that meet the requirements. By the end of this study, an estimate of the mass and volume savings will be provided to the Constellation Program. In addition, if new technologies need to be developed to achieve the mass savings, the technologies, timeline, and budget will be identified at the end of the project

    Annual temperature and precipitation trends in the United States

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    With rising global temperatures and clear trends in changing weather patterns, it is important to develop a framework for regional changes in climate since not all regions experience the same changes. As these regions begin to experience shifts in their climate, it is important to analyze not only general rising trends in temperature and precipitation, but more precise patterns that help flesh out how drastic these changes are. By utilizing indices created by the Expert Team on Climate Change Detection and Indices (ETCCDI), this project aims to better understand regional climate shifts in terms of annual temperature and precipitation trends in the United States. By first applying these indices to climate data from Agricultural Research Service the and then to the future projection based on Global Climate Model simulations available, we can determine what direction climate change has been headed in various parts of the United States and see if those trends will continue

    When They See Someone Who Is Poor, They Step on Them : The Social Determinants of Health Among Survivors of Sex Trafficking in Cambodia

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    Social determinants of health (SDH) are defined as the non-medical yet health-affecting conditions of a person’s life. They include such considerations as working conditions, discrimination, and access to health services. The aim of this study was to explore the SDH impacting those who have survived sex trafficking in Cambodia. This study employed a mixed methods, secondary analysis, focusing on 52 survivors of sex trafficking in the Butterfly Longitudinal Research Project from 2010 through 2019. Participants described myriad social determinants of health, including: gender, age, relationship status (marriage), ethnicity, national identification documentation (statelessness), social class, formal education, vocational training, occupation, and monthly income. The negative impacts of these social determinants of health included: poor access to basic needs of food and clean water, unstable housing, low education rates, worsening physical health, depression, and suicidal ideation, along with long unresolved STI-like symptoms. As these are multidisciplinary issues, the study concludes with recommendations for remedial actions to be taken by multidisciplinary stakeholders, namely government agencies, healthcare professionals, and survivor aftercare service providers

    Small population size and extremely low levels of genetic diversity in island populations of the platypus, Ornithorhynchus anatinus

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    Genetic diversity generally underpins population resilience and persistence. Reductions in population size and absence of gene flow can lead to reductions in genetic diversity, reproductive fitness, and a limited ability to adapt to environmental change increasing the risk of extinction. Island populations are typically small and isolated, and as a result, inbreeding and reduced genetic diversity elevate their extinction risk. Two island populations of the platypus, Ornithorhynchus anatinus, exist; a naturally occurring population on King Island in Bass Strait and a recently introduced population on Kangaroo Island off the coast of South Australia. Here we assessed the genetic diversity within these two island populations and contrasted these patterns with genetic diversity estimates in areas from which the populations are likely to have been founded. On Kangaroo Island, we also modeled live capture data to determine estimates of population size. Levels of genetic diversity in King Island platypuses are perilously low, with eight of 13 microsatellite loci fixed, likely reflecting their small population size and prolonged isolation. Estimates of heterozygosity detected by microsatellites (H(E)= 0.032) are among the lowest level of genetic diversity recorded by this method in a naturally outbreeding vertebrate population. In contrast, estimates of genetic diversity on Kangaroo Island are somewhat higher. However, estimates of small population size and the limited founders combined with genetic isolation are likely to lead to further losses of genetic diversity through time for the Kangaroo Island platypus population. Implications for the future of these and similarly isolated or genetically depauperate populations are discussed

    Constrained MC for QCD evolution with rapidity ordering and minimum kT

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    With the imminent start of LHC experiments, development of phenomenological tools, and in particular the Monte Carlo programs and algorithms, becomes urgent. A new algorithm for the generation of a parton shower initiated by the single initial hadron beam is presented. The new algorithm is of the class of the so called ``constrained MC'' type algorithm (an alternative to the backward evolution MC algorithm), in which the energy and the type of the parton at the end of the parton shower are constrained (predefined). The complete kinematics configurations with explicitly constructed four momenta are generated and tested. Evolution time is identical with rapidity and minimum transverse momentum is used as an infrared cut-off. All terms of the leading-logarithmic approximation in the DGLAP evolution are properly accounted for. In addition, the essential improvements towards the so-called CCFM/BFKL models are also properly implemented. The resulting parton distributions are cross-checked up to the 0.1% precision level with the help of a multitude of comparisons with other MC and non-MC programs. We regard these tests as an important asset to be exploited at the time when the presented MC will enter as a building block in a larger MC program for W/Z production process at LHC.Comment: Submitted to Computer Physics Communication

    Does morphology predict trophic position and habitat use of ant species and assemblages?

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    A functional traits-based theory of organismal communities is critical for understanding the principles underlying community assembly, and predicting responses to environmental change. This is particularly true for terrestrial arthropods, of which only 20 % are described. Using epigaeic ant assemblages, we asked: (1) can we use morphological variation among species to predict trophic position or preferred microhabitat; (2) does the strength of morphological associations suggest recent trait divergence; (3) do environmental variables at site scale predict trait sets for whole assemblages? We pitfall-trapped ants from a revegetation chronosequence and measured their morphology, trophic position [using C:N stoichiometry and stable isotope ratios (δ)] and characteristics of microhabitat and macrohabitat. We found strong associations between high trophic position (low C:N and high δ¹⁵N) in body tissue and morphological traits: predators were larger, had more laterally positioned eyes, more physical protection and tended to be monomorphic. In addition, morphological traits were associated with certain microhabitat features, e.g. smaller heads were associated with the bare ground microhabitat. Trait-microhabitat relationships were more pronounced when phylogenetic adjustments were used, indicating a strong influence of recent trait divergences. At the assemblage level, our fourth corner analysis revealed associations between the prevalence of traits and macrohabitat, although these associations were not the same as those based on microhabitat associations. This study shows direct links between species-level traits and both diet and habitat preference. Trait-based prediction of ecological roles and community structure is thus achievable when integrating stoichiometry, morphology and phylogeny, but scale is an important consideration in such predictions

    Markovian MC simulation of QCD evolution at NLO level with minimum k_T

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    We present two Monte Carlo algorithms of the Markovian type which solve the modified QCD evolution equations at the NLO level. The modifications with respect to the standard DGLAP evolution concern the argument of the strong coupling constant alpha_S. We analyze the z - dependent argument and then the k_T - dependent one. The evolution time variable is identified with the rapidity. The two algorithms are tested to the 0.05% precision level. We find that the NLO corrections in the evolution of parton momentum distributions with k_T - dependent coupling constant are of the order of 10 to 20%, and in a small x region even up to 30%, with respect to the LO contributions.Comment: 32 pages, 9 pdf figure
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