678 research outputs found

    On the Geometry of Supersymmetric Quantum Mechanical Systems

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    We consider some simple examples of supersymmetric quantum mechanical systems and explore their possible geometric interpretation with the help of geometric aspects of real Clifford algebras. This leads to natural extensions of the considered systems to higher dimensions and more complicated potentials.Comment: 18 page

    Beyond expectations: the physiological basis of sensory-enhancement of satiety

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    Background/Objectives: Consumption of high-energy beverages has been implicated as a risk factor for weight gain, yet why nutrients ingested as beverages fail to generate adequate satiety remains unclear. In general consumers do not expect drinks to be satiating, but drinks generate greater satiety when their sensory characteristics imply they may be filling. These findings challenge traditional bottom-up models of how gut-based satiety signals modify behavior to suggest that beliefs at the point of ingestion modify gut-based satiety signaling. Subjects/Methods: Healthy volunteers (n = 23) consumed four different beverages, combining an overt sensory manipulation (thin, Low Sensory, LS, or thicker and more creamy, Enhanced Sensory, ES) and covert nutrient manipulation (low energy, LE, 78kcal; high energy, HE, 267 kcal) on different days. Effects on satiety were assessed through rated appetite and levels of glucose, insulin, pancreatic polypeptide (PP) and cholesystokinin (CCK) recorded periodically over 90 minutes, and through intake at an ad libitum test lunch. Results: Intake at the test lunch and rated appetite were both altered by both the sensory and nutrient manipulations, with lowest intake and greatest suppression of hunger post-drink in the ESHE condition. Insulin increased more after HE than LE drinks, and after ES than LS drinks, while PP levels were higher after ES than LS versions. CCK levels only increased after the ESHE drink. Conclusions: These data confirm acute sensitivity of satiety after consuming a drink both to the sensory characteristics and nutrient content of the drink, and suggest that this may be at least in part due to top-down modulation of release of satiety-related gut hormones

    Phytoplankton Community Dynamic: A Driver for Ciliate Trophic Strategies

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    Phytoplankton plays a key role as primary producers and mediating biogeochemical cycles in the water column. The understanding of the temporal dynamic of primary grazers channeling energy and carbon from primary producers is important for evaluating aquatic ecosystems functioning. This study investigates the coupling between phytoplankton and ciliates from live samples collected with approximately daily frequency during an almost 2-year cycle. The study site is a nutrient-rich temperate estuary, Roskilde Fjord (Denmark). Our aim is to evaluate the importance of protist grazers, especially ciliates, as predators on phytoplankton and to evaluate differences among multiple nutritional strategies through different seasons. The phytoplankton community, was mostly dominated by small organisms (<20 ÎŒm) with few observations of diatoms. In most of observations, heterotrophic dinoflagellates biomass was smaller than biomass of ciliates (<10%), indicating that ciliates are the main component of microzooplankton. Except for the spring 2016, the ciliate community closely followed the phytoplankton community, showing a tight coupling between the primary producers and grazers during all seasons. This somehow contradicts the general assumption that ciliate dominance is restricted to periods of nutrient limitation dominated by the microbial food web and suggests a year-round key role of ciliates as consumers of phytoplankton biomass. Biomasses of ciliates increased during spring and were highest during summer. Relative importance of mixotrophs were high due to occurrence of Mesodinium rubrum blooms as well as other mixotrophic ciliates in late spring/early summer. M. rubrum biomass had the opposite pattern of the cryptophyte prey Teleaulax spp., and the coupling between the two populations was very strong in late spring. Ciliates that grazed on selected phytoplankton, had a smaller potential grazing impact regarding their biomasses, likely due to food limitation; conversely ciliates that feed on diverse prey items were less constrained by food limitation, and their seasonality appear to be driven by other factors. These findings suggest that the ciliate community structure and dynamics is important in structuring the phytoplankton community on short and seasonal scale

    Simonsenia aveniformis sp nov (Bacillariophyceae), molecular phylogeny and systematics of the genus, and a new type of canal raphe system

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    The genus Simonsenia is reviewed and S. aveniformis described as new for science by light and electron microscopy. The new species originated from estuarine environments in southern Iberia (Atlantic coast) and was isolated into culture. In LM, Simonsenia resembles Nitzschia, with bridges (fibulae) beneath the raphe, which is marginal. It is only electron microscope (EM) examination that reveals the true structure of the raphe system, which consists of a raphe canal raised on a keel (wing), supported by rib like braces (fenestral bars) and tube-like portulae; between the portulae the keel is perforated by open windows (fenestrae). Based on the presence of portulae and a fenestrated keel, Simonsenia has been proposed to be intermediate between Bacillariaceae and Surirellaceae. However, an rbcL phylogeny revealed that Simonsenia belongs firmly in the Bacillariaceae, with which it shares a similar chloroplast arrangement, rather than in the Surirellaceae. Lack of homology between the surirelloid and simonsenioid keels is reflected in subtle differences in the morphology and ontogeny of the portulae and fenestrae. The diversity of Simonsenia has probably been underestimated, particularly in the marine environment.Polish National Science Centre in Cracow within the Maestro program [N 2012/04/A/ST10/00544]; Sciences and Technologies Foundation-FCT (Portugal) [SFRH/BD/62405/2009]info:eu-repo/semantics/publishedVersio

    Ecological risk assessment of endocrine disruptors.

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    The European Centre for Ecotoxicology and Toxicology of Chemicals proposes a tiered approach for the ecological risk assessment of endocrine disruptors, integrating exposure and hazard (effects) characterization. Exposure assessment for endocrine disruptors should direct specific tests for wildlife species, placing hazard data into a risk assessment context. Supplementing the suite of mammalian screens now under Organization for Economic Cooperation and Development (OECD) validation, high priority should be given to developing a fish screening assay for detecting endocrine activity in oviparous species. Taking into account both exposure characterization and alerts from endocrine screening, higher tier tests are also a priority for defining adverse effects. We propose that in vivo mammalian and fish assays provide a comprehensive screening battery for diverse hormonal functions (including androgen, estrogen, and thyroid hormone), whereas Amphibia should be considered at higher tiers if there are exposure concerns. Higher tier endocrine-disruptor testing should include fish development and fish reproduction tests, whereas a full life-cycle test could be subsequently used to refine aquatic risk assessments when necessary. For avian risk assessment, the new OECD Japanese quail reproduction test guideline provides a valuable basis for developing a test to detecting endocrine-mediated reproductive effects; this species could be used, where necessary, for an avian life-cycle test. For aquatic and terrestrial invertebrates, data from existing developmental and reproductive tests remain of high value for ecological risk assessment. High priority should be given to research into comparative endocrine physiology of invertebrates to support data extrapolation to this diverse fauna

    Predictors of adolescents’ consent to use health records for research and results from data collection in a Swedish twin cohort

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    INTRODUCTION: Non-random selection into a study population due to differences between consenters and non-consenters may introduce participation bias. Past investigations of factors predicting consent to collection of medical health records for research imply that age, sex, health status, and education are of importance for participation, but disagree on the direction of effects. Very little is known about influences on consent from adolescents. METHODS: Two cohorts of Swedish 15-year-old twins (total n = 4,611) previously invited to the Child and Adolescent Twin Study in Sweden (CATSS) responded to a questionnaire with information on sex, individual's health, height, weight, and parental factors. The questionnaire included a question for consent to collection of medical health records. Predictors for consent were analyzed using logistic regression. Additionally, regional differences in the collection of health records of consenters were evaluated. RESULTS: Males were significantly less likely to consent compared to females (OR 0.74, 95% CI 0.64-0.85). The twin siblings' decision to consent was strongly associated with consent (OR 10.9, 95% CI 8.76-13.5), and individuals whose parents had responded to the original CATSS study were more likely to consent to record collection at age 15 (OR 2.2, 95% CI 1.81-2.75). Results of the subsequent collection of consenters' medical health records varied between geographical regions of Sweden. CONCLUSION: We identified several predictors for adolescents' consent to collection of their medical health records. Further selection was introduced through the subsequent record collection. Whether this will induce participation bias in future studies depends on the research questions' relationship to the identified predictors.NoneAccepte

    Causal Effects of the Timing of Life-course Events Age at Retirement and Subsequent Health

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    In this article, we combine the extensive literature on the analysis of life-course trajectories as sequences with the literature on causal inference and propose a new matching approach to investigate the causal effect of the timing of life-course events on subsequent outcomes. Our matching approach takes into account pre-event confounders that are both time-independent and time-dependent as well as life-course trajectories. After matching, treated and control individuals can be compared using standard statistical tests or regression models. We apply our approach to the study of the consequences of the age at retirement on subsequent health outcomes, using a unique data set from Swedish administrative registers. Once selectivity in the timing of retirement is taken into account, effects on hospitalization are small, while early retirement has negative effects on survival. Our approach also allows for heterogeneous treatment effects. We show that the effects of early retirement differ according to preretirement income, with higher income individuals tending to benefit from early retirement, while the opposite is true for individuals with lower income

    Effect of eicosapentaenoic acid, protein and amino acids on protein synthesis and degradation in skeletal muscle of cachectic mice

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    Atrophy of skeletal muscle reduces both the quality and quantity of life of patients with cancer cachexia. Loss of muscle mass is thought to arise from a reduction in protein synthesis combined with an enhanced rate of protein degradation, and few treatments are available to counteract this process. Eicosapentaenoic acid (EPA) has been shown to attenuate the enhanced protein degradation, but to have no effect on protein synthesis. This study examines the effect of EPA combined with a protein and amino-acid supplementation on protein synthesis and degradation in gastrocnemius muscle of mice bearing the cachexia-inducing MAC16 tumour. Muscles from cachectic mice showed an 80% reduction in protein synthesis and about a 50-fold increase in protein degradation compared with muscles from nontumour-bearing mice of the same age and weight. Treatment with EPA (1 g kg-1) daily reduced protein degradation by 88%, but had no effect on protein synthesis. Combination of EPA with casein (5.35 g kg-1) also had no effect on protein synthesis, but when combined with the amino acids leucine, arginine and methionine there was almost a doubling of protein synthesis. The addition of carbohydrate (10.7 g kg-1) to stimulate insulin release had no additional effect. The combination involving the amino acids produced almost a doubling of the ratio of protein synthesis to protein degradation in gastrocnemius muscle over that of EPA alone. No treatment had a significant effect on tumour growth rate, but the inclusion of amino acids had a more significant effect on weight loss induced by the MAC16 tumour than that of EPA alone. The results suggest that combination therapy of cancer cachexia involving both inhibition of the enhanced protein degradation and stimulation of the reduced protein synthesis may be more effective than either treatment alone. © 2004 Cancer Research UK

    Additive sustainability footprint: Rationale and pilot evaluation of a tool for assessing the sustainable use of PVC additives

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    © 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers. PVC compounds contain additives necessary for processing and stability, and to modify the plastic's properties. The Europe-wide VinylPlusŸ voluntary commitment includes a challenge to make progress toward sustainable use of additives. Additive Sustainability Footprint (ASF) was developed to assess sustainable use of additives across the whole societal life cycles of finished PVC articles, taking a risk-based approach rather than simplistic hazard assessment. ASF addresses impacts across six life cycle assessment (LCA) stages established by ISO Standard 14040, using the four System Conditions (sustainability principles) developed by The Natural Step (TNS) covering social as well as environmental factors. For each LCA stage/System Condition combination, seven generically similar questions cover negative impacts (many covered by existing tools and regulations) but also the additive's positive contributions to the sustainability of finished articles. Positive contributions include ethical sourcing, longevity of service life, low maintenance inputs, and recyclability. Answers to questions determine a score, which can be combined across the life cycle and with other additives. Testing on a generic EU PVC window profile supported ASF development and demonstrated applicability and potential benefits including use for sensitivity analysis of alternative additives from different geopolitical regions or from recycled as opposed to virgin sources. J. VINYL ADDIT. TECHNOL., 2019. © 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers

    A prospective longitudinal study of performance status, an inflammation-based score (GPS) and survival in patients with inoperable non-small-cell lung cancer

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    The value of an inflammation-based prognostic score (Glasgow Prognostic score, GPS) was compared with performance status (ECOG-ps) in a longitudinal study of patients (n=101) with inoperable non-small-cell lung cancer (NSCLC). At diagnosis, stratified for treatment, only the GPS (HR 2.32, 95% CI 1.52–3.54, P<0.001) was a significant predictor of survival. In contrast, neither the GPS nor ECOG-ps measured at 3–6 months follow-up were significant predictors of residual survival. This study confirms the prognostic value of the GPS, at diagnosis, in patients with inoperable NSCLC. However, the role of the GPS and ECOG-ps during follow-up has not been established
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