1,039 research outputs found

    Cultural selection drives the evolution of human communication systems

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    Human communication systems evolve culturally, but the evolutionary mechanisms that drive this evolution are not well understood. Against a baseline that communication variants spread in a population following neutral evolutionary dynamics (also known as drift models), we tested the role of two cultural selection models: coordination- and content-biased. We constructed a parametrized mixed probabilistic model of the spread of communicative variants in four 8-person laboratory micro-societies engaged in a simple communication game. We found that selectionist models, working in combination, explain the majority of the empirical data. The best-fitting parameter setting includes an egocentric bias and a content bias, suggesting that participants retained their own previously used communicative variants unless they encountered a superior (content-biased) variant, in which case it was adopted. This novel pattern of results suggests that (i) a theory of the cultural evolution of human communication systems must integrate selectionist models and (ii) human communication systems are functionally adaptive complex systems

    Cancer Information Seeking Preferences among health professionals serving American Indians in Minnesota, North Dakota, and Wisconsin

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    This article identifies cancer information resources used by health professionals in tribal health departments or Indian Health Service clinics serving American Indian communities in Wisconsin, Minnesota and North Dakota

    Mycotoxin exposure and human cancer risk : a systematic review of epidemiological studies

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    In recent years, there has been an increasing interest in investigating the carcinogenicity of mycotoxins in humans. This systematic review aims to provide an overview of data linking exposure to different mycotoxins with human cancer risk. Publications (2019 and earlier) of case–control or longitudinal cohort studies were identified in PubMed and EMBASE. These articles were then screened by independent reviewers and their quality was assessed according to the Newcastle–Ottawa scale. Animal, cross‐sectional, and molecular studies satisfied criteria for exclusion. In total, 14 articles were included: 13 case–control studies and 1 longitudinal cohort study. Included articles focused on associations of mycotoxin exposure with primary liver, breast, and cervical cancer. Overall, a positive association between the consumption of aflatoxin‐contaminated foods and primary liver cancer risk was verified. Two case–control studies in Africa investigated the relationship between zearalenone and its metabolites and breast cancer risk, though conflicting results were reported. Two case–control studies investigated the association between hepatocellular carcinoma and fumonisin B1 exposure, but no significant associations were observed. This systematic review incorporates several clear observations of dose‐dependent associations between aflatoxins and liver cancer risk, in keeping with IARC Monograph conclusions. Only few human epidemiological studies investigated the associations between mycotoxin exposures and cancer risk. To close this gap, more in‐depth research is needed to unravel evidence for other common mycotoxins, such as deoxynivalenol and ochratoxin A. The link between mycotoxin exposures and cancer risk has mainly been established in experimental studies, and needs to be confirmed in human epidemiological studies to support the evidence‐based public health strategies

    IL-4 alpha chain receptor (IL-4Rα) polymorphisms in allergic bronchopulmonary sspergillosis

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    BACKGROUND: Allergic bronchopulmonary aspergillosis occurs in 7–10% of cystic fibrosis (CF) and 1–2% of asthmatic patients. HLA-DR restriction and increased sensitivity to IL-4 stimulation have been proposed as risk factors in these populations. OBJECTIVE: We examined for the presence of IL-4 receptor alpha chain (IL-4Rα) single nucleotide polymorphisms (SNPs) in ABPA and whether these accounted for increased sensitivity to IL-4 stimulation. METHODS: One extracellular (ile75val) and four cytoplasmic IL-4Rα SNPs were analyzed in 40 CF and 22 asthmatic patients and in 56 non-ABPA CF and asthmatic patients. Sensitivity to IL-4 stimulation was measured by induction of CD23 expression on B cells. RESULTS: IL-4Rα SNPs were observed in 95% of ABPA patients. The predominant IL-4Rα SNP was the extracellular IL-4Rα SNP, ile75val, observed in 80% of ABPA patients. CONCLUSION: The presence of IL-4Rα SNPs, principally ile75val, appears to be a genetic risk for the development of ABPA

    Invariant construction of solutions to Einstein's field equations - LRS perfect fluids II

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    The properties of LRS class II perfect fluid space-times are analyzed using the description of geometries in terms of the Riemann tensor and a finite number of its covariant derivatives. In this manner it is straightforward to obtain the plane and hyperbolic analogues to the spherical symmetric case. For spherically symmetric static models the set of equations is reduced to the Tolman-Oppenheimer-Volkoff equation only. Some new non-stationary and inhomogeneous solutions with shear, expansion, and acceleration of the fluid are presented. Among these are a class of temporally self-similar solutions with equation of state given by p=(γ−1)ÎŒ,1<Îł<2p=(\gamma-1)\mu, 1<\gamma<2, and a class of solutions characterized by σ=−Θ/6\sigma=-\Theta/6. We give an example of geometry where the Riemann tensor and the Ricci rotation coefficients are not sufficient to give a complete description of the geometry. Using an extension of the method, we find the full metric in terms of curvature quantities.Comment: 24 pages, 1 figur

    Non-adiabatic radiative collapse of a relativistic star under different initial conditions

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    We examine the role of space-time geometry in the non-adiabatic collapse of a star dissipating energy in the form of radial heat flow, studying its evolution under different initial conditions. The collapse of a star with interior comprising of a homogeneous perfect fluid is compared with that of a star filled with inhomogeneous imperfect fluid with anisotropic pressure. Both the configurations are spherically symmetric, however, in the latter case, the physical space t=constantt= constant of the configurations is assumed to be inhomogeneous endowed with spheroidal or pseudo-spheroidal geometry. It is observed that as long as the collapse is shear-free, its evolution depends only on the mass and size of the star at the onset of collapse.Comment: To appear in Pramana- j. of physic

    Using the tectophase conceptual model to assess late Triassic–Early Jurassic far-field tectonism across the South-central Barents Sea shelf

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    The Upper Triassic–Lower Jurassic succession of the Barents Sea Shelf (BSS) represents one of Europe’s most prolific and strategic petroleum systems. This succession reflects various depositional environments and tectonostratigraphic events. Even though these strata are considered largely well-understood, connections with far-field stresses triggered by regional tectonics remain a subject of investigation. This study presents new interpretations that focus on relationships between the stratigraphic succession across the south-central BSS and Triassic–Jurassic Novaya Zemlya compressional tectonics. By applying the “tectophase model,” developed in the Appalachian Basin, to analyze this succession, the presence of foreland-basin depozones and associated far-field processes related to compressional tectonics in an adjacent orogen are suggested. This model addresses unconformity development, lithostratigraphic succession, and reactivation of structures. Use of this model suggests far-field tectonostratigraphic responses during two episodes of Novaya Zemlya tectonism, reflected in the coeval BSS stratigraphy. Overall, this tectonostratigraphic study aligns with other research suggesting a Late Triassic inception for Novaya Zemlya compressional tectonism, which influenced larger parts of the BSS through extensive clastic sedimentation, far-field structural reactivation, and flexural responses to deformational loading triggered by tectonics

    A few questions about curves on surfaces

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    In this note we address the following kind of question: let X be a smooth, irreducible, projective surface and D a divisor on X satisfying some sort of positivity hypothesis, then is there some multiple of D depending only on X which is effective or movable? We describe some examples, discuss some conjectures and prove some results that suggest that the answer should in general be negative, unless one puts some really strong hypotheses either on D or on X
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