7,989 research outputs found

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    The Minimally Tuned Minimal Supersymmetric Standard Model

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    The regions in the Minimal Supersymmetric Standard Model with the minimal amount of fine-tuning of electroweak symmetry breaking are presented for general messenger scale. No a priori relations among the soft supersymmetry breaking parameters are assumed and fine-tuning is minimized with respect to all the important parameters which affect electroweak symmetry breaking. The superpartner spectra in the minimally tuned region of parameter space are quite distinctive with large stop mixing at the low scale and negative squark soft masses at the high scale. The minimal amount of tuning increases enormously for a Higgs mass beyond roughly 120 GeV.Comment: 38 pages, including 2 appendices, 8 figure

    Prebiotics, faecal transplants and microbial network units to stimulate biodiversity of the human gut microbiome

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    Accumulating evidence demonstrates the intimate association between human hosts and the gut microbiome. Starting at birth, the sterile gut of the newborn acquires a diverse spectrum of microbes, needed for immunological priming. However, current practices (caesarean sections, use of formula milk) deprive newborns from being exposed to this broad spectrum of microbes. Unnecessary use of antibiotics and excessive hygienic precautions (e.g. natural versus chlorinated drinking water) together with the Western diet further contribute to a decreased microbial diversity in the adult gut. This has been correlated with recurrent Clostridium difficile infection, inflammatory bowel diseases and obesity, among others. A healthy gut microbiome is thus characterized by a diverse network of metabolically interacting microbial members. In this context, we review several existing and novel approaches to manage the gut microbiome. First, prebiotic compounds should be re-defined in the sense that they should enhance the ecological biodiversity rather than stimulating single species. Recent studies highlight that structurally different polysaccharides require specific primary degraders but also enhance a similar network of secondary degraders that benefit from cross-feeding. A faecal transplantation is a second approach to restore biodiversity when the microbiota is severely dysbiosed, with promising results regarding C.difficile-associated disease and obesity-related metabolic syndromes. A final strategy is the introduction of key microbial network units, i.e. pre-organized microbial associations, which strengthen the overall microbial network of the gut microbiome that supports human health

    Bayesian approach and Naturalness in MSSM analyses for the LHC

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    The start of LHC has motivated an effort to determine the relative probability of the different regions of the MSSM parameter space, taking into account the present, theoretical and experimental, wisdom about the model. Since the present experimental data are not powerful enough to select a small region of the MSSM parameter space, the choice of a judicious prior probability for the parameters becomes most relevant. Previous studies have proposed theoretical priors that incorporate some (conventional) measure of the fine-tuning, to penalize unnatural possibilities. However, we show that such penalization arises from the Bayesian analysis itself (with no ad hoc assumptions), upon the marginalization of the mu-parameter. Furthermore the resulting effective prior contains precisely the Barbieri-Giudice measure, which is very satisfactory. On the other hand we carry on a rigorous treatment of the Yukawa couplings, showing in particular that the usual practice of taking the Yukawas "as required", approximately corresponds to taking logarithmically flat priors in the Yukawa couplings. Finally, we use an efficient set of variables to scan the MSSM parameter space, trading in particular B by tan beta, giving the effective prior in the new parameters. Beside the numerical results, we give accurate analytic expressions for the effective priors in all cases. Whatever experimental information one may use in the future, it is to be weighted by the Bayesian factors worked out here.Comment: LaTeX, 19 pages, 3 figure

    We navel-string bury here: Landscape history, representation and identity in the Grenada islandscape

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    This study explores the process of identity creation in the Caribbean archipelagic space by examining the last five centuries of Grenada’s layered history through detailing and analyzing the major human-environment interactions that have transformed its landscape, particularly following the invasion of Europeans since the 17th century and the establishment of plantation agriculture and slavery (utilizing enslaved Africans and their descendants), village settlements and subsistence agriculture, and much later tourism. It will analyze its landscape transformations by examining land use and settlement patterns of its human occupants from the Indigenous Kali’nago to its current inhabitants via the concept of creolization. Centuries of interactions between and among these various groups of people and the Grenadian environment have created a landscape best described as a palimpsest where layer upon layer of interactions intertwine, overwrite and blend with each other through time. Yet leaving glimpses or blurred pictures of impacts in various and discernable ways, thus creating a long-term biography of this islandscape. By examining the Grenadian palimpsest and analyzing the concept of landscape identity through historical representations and memory-traces embedded in the Creole cultural landscape this study explores the relationship between people and the landscape over time.The research leading to this dissertation received funding from the European Research Council (ERC) under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC-Synergy project NEXUS1492, grant agreement nr. 319209.Archaeology of the America

    Low birth weight and small for gestational age are associated with complications of childhood and adolescence obesity: systematic review and meta-analysis

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    In recent decades, the incidence of type 2 diabetes (T2D) has increased dramatically in children and adolescents, posing a real public health problem. Beyond unhealthy diets and sedentary lifestyles, growing evidence suggests that some perinatal factors, such as low birth weight (LBW), are associated with higher risk of T2D in adulthood. In this regard, it remains unclear whether the increased risk is already present in childhood and adolescence. We conducted a systematic review and meta-analysis to clarify the association of LBW or being small for gestational age (SGA) with insulin resistance in childhood and adolescence. The systematic review resulted in 28 individual studies, and those with the same outcome were included within two random-effects meta-analyses. Compared with children or adolescents born with adequate size for gestational age, those SGA had 2.33-fold higher risk of T2D (95% confidence interval [CI]: 1.05–5.17). Furthermore, LBW and being SGA were associated with 0.20 higher mean homeostasis model assessment of insulin resistance (HOMA-IR) values (95% CI: 0.02–0.38). Given the high prevalence of preterm babies, from a population perspective, these results may be of great importance as they point to the existence of a potentially vulnerable subgroup of children and adolescents that could benefit from screening tests and early preventive strategies

    Age and Grip Strength Predict Hand Dexterity in Adults.

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    In the scientific literature, there is much evidence of a relationship between age and dexterity, where increased age is related to slower, less nimble and less smooth, less coordinated and less controlled performances. While some suggest that the relationship is a direct consequence of reduced muscle strength associated to increased age, there is a lack of research that has systematically investigated the relationships between age, strength and hand dexterity. Therefore, the aim of this study was to examine the associations between age, grip strength and dexterity. 107 adults (range 18-93 years) completed a series of hand dexterity tasks (i.e. steadiness, line tracking, aiming, and tapping) and a test of maximal grip strength. We performed three phases of analyses. Firstly, we evaluated the simple relationships between pairs of variables; replicating the existing literature; and found significant relationships of increased age and reduced strength; increased age and reduced dexterity, and; reduced strength and reduced dexterity. Secondly, we used standard Multiple Regression (MR) models to determine which of the age and strength factors accounted for the greater variance in dexterity. The results showed that both age and strength made significant contributions to the data variance, but that age explained more of the variance in steadiness and line tracking dexterity, whereas strength explained more of the variance in aiming and tapping dexterity. In a third phase of analysis, we used MR analyses to show an interaction between age and strength on steadiness hand dexterity. Simple Slopes posthoc analyses showed that the interaction was explained by the middle to older aged adults showing a relationship between reduced strength and reduced hand steadiness, whereas younger aged adults showed no relationship between strength and steadiness hand dexterity. The results are discussed in terms of how age and grip strength predict different types of hand dexterity in adults
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