860 research outputs found

    Neural correlates of economic game playing

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    The theory of games provides a mathematical formalization of strategic choices, which have been studied in both economics and neuroscience, and more recently has become the focus of neuroeconomics experiments with human and non-human actors. This paper reviews the results from a number of game experiments that establish a unitary system for forming subjective expected utility maps in the brain, and acting on these maps to produce choices. Social situations require the brain to build an understanding of the other person using neuronal mechanisms that share affective and intentional mental states. These systems allow subjects to better predict other players' choices, and allow them to modify their subjective utility maps to value pro-social strategies. New results for a trust game are presented, which show that the trust relationship includes systems common to both trusting and trustworthy behaviour, but they also show that the relative temporal positions of first and second players require computations unique to that role

    Earliest hominin cancer: 1.7-million-year- old osteosarcoma from Swartkrans Cave, South Africa

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    The reported incidence of neoplasia in the extinct human lineage is rare, with only a few confirmed cases of Middle or Later Pleistocene dates reported. It has generally been assumed that premodern incidence of neoplastic disease of any kind is rare and limited to benign conditions, but new fossil evidence suggests otherwise. We here present the earliest identifiable case of malignant neoplastic disease from an early human ancestor dated to 1.8–1.6 million years old. The diagnosis has been made possible only by advances in 3D imaging methods as diagnostic aids. We present a case report based on re-analysis of a hominin metatarsal specimen (SK 7923) from the cave site of Swartkrans in the Cradle of Humankind, South Africa. The expression of malignant osteosarcoma in the Swartkrans specimen indicates that whilst the upsurge in malignancy incidence is correlated with modern lifestyles, there is no reason to suspect that primary bone tumours would have been any less frequent in ancient specimens. Such tumours are not related to lifestyle and often occur in younger individuals. As such, malignancy has a considerable antiquity in the fossil record, as evidenced by this specimen.NCS201

    Valence nucleon populations in the Ni isotopes

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    Measurements of neutron-adding, neutron-removing, and proton-adding reactions were carried out for the four stable even Ni isotopes. Particular attention was paid to obtaining precise values of the cross sections at the peaks of the angular distributions. Tests with sum rules for the neutron data indicate that the results are self-consistent at the level of a few tenths of a nucleon. Data on proton-adding reactions were also obtained and analyzed with a slightly different method—while these data are also consistent, the ambiguities are larger. The occupancies of the neutron orbits derived from the data, the proton vacancies, and the energy centroids of the neutron, neutron-hole, and proton single-particle excitations are obtained. The data also provide some estimate about the closure of the 0f7/2 shell. The results are compared to shell-model calculations and may serve as a reference point for future exploration

    Reasons for hormonal contraceptive use in a cohort of African-American women living in the Detroit area

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    Objectives: To characterize reasons for hormonal contraceptive (HC) use in 1,455 African-American women, aged 23–35 years. Study design: The community-based cohort members were recruited from the Detroit, Michigan area in 2010–2012. HC history was collected via telephone interview. Results: Seven percent reported HC use exclusively for non-contraceptive purposes, and 49% reported non-contraceptive reasons in addition to contraception. Non-contraceptive reasons were reported for all HC types, but were most common for combined oral contraceptives. Primary reasons were for irregular cycles, heavy bleeding, and pain. Conclusions: In this large cohort of Black women, HC use to treat menstrual problems was common. Implications: HCs were commonly used for both pregnancy prevention and management of menstrual symptoms, but some women used HCs exclusively for menstrual symptom relief. The importance for women of non-contraceptive reasons for HC use may not be adequately recognized, and published data on Black women's reasons for HC use remain limited

    Search for Global Dipole Enhancements in the HiRes-I Monocular Data above 10^{18.5} eV

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    Several proposed source models for Ultra-High Energy Cosmic Rays (UHECRs) consist of dipole distributions oriented towards major astrophysical landmarks such as the galactic center, M87, or Centaurus A. We use a comparison between real data and simulated data to show that the HiRes-I monocular data for energies above 10^{18.5} eV is, in fact, consistent with an isotropic source model. We then explore methods to quantify our sensitivity to dipole source models oriented towards the Galactic Center, M87, and Centaurus A.Comment: 17 pages, 31 figure

    Red Queen Coevolution on Fitness Landscapes

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    Species do not merely evolve, they also coevolve with other organisms. Coevolution is a major force driving interacting species to continuously evolve ex- ploring their fitness landscapes. Coevolution involves the coupling of species fit- ness landscapes, linking species genetic changes with their inter-specific ecological interactions. Here we first introduce the Red Queen hypothesis of evolution com- menting on some theoretical aspects and empirical evidences. As an introduction to the fitness landscape concept, we review key issues on evolution on simple and rugged fitness landscapes. Then we present key modeling examples of coevolution on different fitness landscapes at different scales, from RNA viruses to complex ecosystems and macroevolution.Comment: 40 pages, 12 figures. To appear in "Recent Advances in the Theory and Application of Fitness Landscapes" (H. Richter and A. Engelbrecht, eds.). Springer Series in Emergence, Complexity, and Computation, 201

    Circumstellar interaction in supernovae in dense environments - an observational perspective

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    In a supernova explosion, the ejecta interacting with the surrounding circumstellar medium (CSM) give rise to variety of radiation. Since CSM is created from the mass lost from the progenitor star, it carries footprints of the late time evolution of the star. This is one of the unique ways to get a handle on the nature of the progenitor star system. Here, I will focus mainly on the supernovae (SNe) exploding in dense environments, a.k.a. Type IIn SNe. Radio and X-ray emission from this class of SNe have revealed important modifications in their radiation properties, due to the presence of high density CSM. Forward shock dominance of the X-ray emission, internal free-free absorption of the radio emission, episodic or non-steady mass loss rate, asymmetry in the explosion seem to be common properties of this class of SNe.Comment: Fixed minor typos. 31 pages, 9 figures, accepted for publication in Space Science Reviews. Chapter in International Space Science Institute (ISSI) Book on "Supernovae" to be published in Space Science Reviews by Springe

    Estimating syphilis seroprevalence among patients in a sexually transmitted infections clinic in Lilongwe, Malawi

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    The syndromic management of genital ulcer disease (GUD) misses asymptomatic syphilis cases but is widely utilized in resource-limited settings without diagnostic capabilities to ensure treatment for the most common etiologies of GUD. We used rapid serology tests for syphilis screening at a Malawian sexually transmitted infections clinic. The estimated seroprevalence was 9% and was highest among patients with genital ulcers (26%) and newly diagnosed HIV infection (19%). Rapid syphilis screening has the potential to increase syphilis detection, but accurate patient histories regarding syphilis diagnosis and prior treatment are needed
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