9,363 research outputs found

    Cannibalism as a life boat mechanism

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    Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one

    The cholesterol-raising diterpenes from coffee beans increase serum lipid transfer protein activity levels in humans

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    Cafestol and kahweol–diterpenes present in unfiltered coffee— strongly raise serum VLDL and LDL cholesterol and slightly reduce HDL cholesterol in humans. The mechanism of action is unknown. We determined whether the coffee diterpenes may affect lipoprotein metabolism via effects on lipid transfer proteins and lecithin:cholesterol acyltransferase in a randomized, double-blind cross-over study with 10 healthy male volunteers. Either cafestol (61–64 mg/day) or a mixture of cafestol (60 mg/day) and kahweol (48–54 mg/day) was given for 28 days. Serum activity levels of cholesterylester transfer protein, phospholipid transfer protein and lecithin:cholesterol acyltransferase were measured using exogenous substrate assays. Relative to baseline values, cafestol raised the mean (±S.D.) activity of cholesterylester transfer protein by 18±12% and of phospholipid transfer protein by 21±14% (both P<0.001). Relative to cafestol alone, kahweol had no significant additional effects. Lecithin:cholesterol acyltransferase activity was reduced by 11±12% by cafestol plus kahweol (P=0.02). It is concluded that the effects of coffee diterpenes on plasma lipoproteins may be connected with changes in serum activity levels of lipid transfer proteins

    Realization of a space reversal operator

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    In this paper we propose the realization of a bosonic-fermionic interaction in the context of trapped ions whose effect upon the ion center of mass degrees of freedom is properly speaking a spatial inversion. The physical system and its features are accurately described and some applications are briefly discussed.Comment: 9 pages; to appear in Rep. Math. Phys., in summer 200

    Levels of cafestol, kahweol, and related diterpenoids in wild species of the coffee plant coffea

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    Abstract Specific fatty acids and sterols in food composites from seven countries were analyzed. In the 1960s, groups of 8 to 49 men from 16 cohorts, ages 40–59 years and living in the United States, Finland, the Netherlands, Italy, Greece, the former Yugoslavia, or Japan recorded their food intake. In 1987, we collected food composites representing the average food intake per cohort sample in the 1960s. The foods were transported to the Netherlands, pooled, and centrally analyzed for energy, total fat, 42 fatty acids, cholesterol, and four plant sterols. The fat content ranged from 12% of total daily energy in the Tanushimaru, Japan, cohort to 50% in the U.S. cohort sample, and the polyunsaturated to saturated fat ratio ranged from 0.17 in the east Finland cohort to 1.2 in Tanushimaru. The amount oftransfatty acids with 16 or 18 carbon atoms varied between 0.2 g/day in Corfu, Greece, and 8.6 g/day in Zutphen, Netherlands, and that of -linolenic acid between 0.8 g/day in Rome and 2.5 g/day in east Finland. The sum of eicosapentaenoic and docosahexanoic acid ranged from 0.1 (U.S. railroad) to 2.0 g/day (Ushibuka, Japan), and phytosterols from 170 (U.S. railroad) to 358 mg/day (Corfu, Greece). Thus the intake of various fatty acids and sterols with potential relevance for coronary heart disease occurrence varied 10-fold or more between cohorts. Our data can be used to generate new hypotheses about the causes of differences in incidence of diseases between countries

    Accurate ab initio density fitting for multiconfigurational self-consistent field methods

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    Using Cholesky decomposition and density fitting to approximate the electron repulsion integrals, an implementation of the complete active space self-consistent field (CASSCF) method suitable for large-scale applications is presented. Sample calculations on benzene, diaquo-tetra-μ-acetato-dicopper(II), and diuraniumendofullerene demonstrate that the Cholesky and density fitting approximations allow larger basis sets and larger systems to be treated at the CASSCF level of theory with controllable accuracy. While strict error control is an inherent property of the Cholesky approximation, errors arising from the density fitting approach are managed by using a recently proposed class of auxiliary basis sets constructed from Cholesky decomposition of the atomic electron repulsion [email protected]

    A new approach to the exact solutions of the effective mass Schrodinger equation

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    Effective mass Schrodinger equation is solved exactly for a given potential. Nikiforov-Uvarov method is used to obtain energy eigenvalues and the corresponding wave functions. A free parameter is used in the transformation of the wave function. The effective mass Schrodinger equation is also solved for the Morse potential transforming to the constant mass Schr\"{o}dinger equation for a potential. One can also get solution of the effective mass Schrodinger equation starting from the constant mass Schrodinger equation.Comment: 14 page

    PT-symmetric Solutions of Schrodinger Equation with position-dependent mass via Point Canonical Transformation

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    PT-symmetric solutions of Schrodinger equation are obtained for the Scarf and generalized harmonic oscillator potentials with the position-dependent mass. A general point canonical transformation is applied by using a free parameter. Three different forms of mass distributions are used. A set of the energy eigenvalues of the bound states and corresponding wave functions for target potentials are obtained as a function of the free parameter.Comment: 13 page

    Implementation conditions for diet and physical activity interventions and policies : an umbrella review

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    BACKGROUND: This umbrella review aimed at identifying evidence-based conditions important for successful implementation of interventions and policies promoting a healthy diet, physical activity (PA), and a reduction in sedentary behaviors (SB). In particular, we examined if the implementation conditions identified were intervention-specific or policy-specific. This study was undertaken as part of the DEterminants of DIet and Physical Activity (DEDIPAC) Knowledge Hub, a joint action as part of the European Joint Programming Initiative a Healthy Diet for a Healthy Life. METHODS: A systematic review of reviews and stakeholder documents was conducted. Data from nine scientific literature databases were analyzed (95 documents met the inclusion criteria). Additionally, published documentation of eight major stakeholders (e.g., World Health Organization) were systematically searched (17 documents met the inclusion criteria). The RE-AIM framework was used to categorize elicited conditions. Across the implementation conditions 25 % were identified in at least four documents and were subsequently classified as having obtained sufficient support. RESULTS: We identified 312 potential conditions relevant for successful implementation; 83 of these received sufficient support. Using the RE-AIM framework eight implementation conditions that obtained support referred to the reach in the target population; five addressed efficacy of implementation processes; 24 concerned adoption by the target staff, setting, or institutions; 43 referred to consistency, costs, and adaptations made in the implementation process; three addressed maintenance of effects over time. The vast majority of implementation conditions (87.9 %; 73 of 83) were supported by documents referring to both interventions and policies. There were seven policy-specific implementation conditions, which focused on increasing complexities of coexisting policies/legal instruments and their consequences for implementation, as well as politicians' collaboration in implementation. CONCLUSIONS: The use of the proposed list of 83 conditions for successful implementation may enhance the implementation of interventions and policies which pursue identification of the most successful actions aimed at improving diet, PA and reducing SB

    Genotyping of Giardia in Dutch patients and animals: a phylogenetic analysis of human and animal isolates.

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    Giardia duodenalis (syn. Giardia lamblia, Giardia intestinalis) is a protozoan organism that can infect the intestinal tract of many animal species including mammals. Genetic heterogeneity of G. duodenalis is well described but the zoonotic potential is still not clear. In this study, we analysed 100 Giardia DNA samples directly isolated from human stool specimens, to get more insight in the different G. duodenalis assemblages present in the Dutch human population. Results showed that these human isolates could be divided into two main Assemblages A and B within the G. duodenalis group on the basis of PCR assays specific for the Assemblages A and B and the DNA sequences of 18S ribosomal RNA and the glutamate dehydrogenase (gdh) genes. Genotyping results showed that G. duodenalis isolates originating from Dutch human patients belonged in 35% of the cases to Assemblage A (34/98) and in 65% of the cases to Assemblage B (64/98) whereas two human cases remained negative in all assays tested. In addition, we compared these human samples with animal samples from the Netherlands and human and animal samples from other countries. A phylogenetic analysis was carried out on the DNA sequences obtained from these Giardia and those available in GenBank. Using gdh DNA sequence analysis, human and animal Assemblage A and B Giardia isolates could be identified. However, phylogenetic analysis revealed different sub-clustering for human and animal isolates where host-species-specific assemblages (C, D, E, F and G) could be identified. The geographic origin of the human and animal samples was not a discriminating factor

    Exceptional orthogonal polynomials and exactly solvable potentials in position dependent mass Schroedinger Hamiltonians

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    Some exactly solvable potentials in the position dependent mass background are generated whose bound states are given in terms of Laguerre- or Jacobi-type X1X_1 exceptional orthogonal polynomials. These potentials are shown to be shape invariant and isospectral to the potentials whose bound state solutions involve classical Laguerre or Jacobi polynomials.Comment: To appear in Physics Letters
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