9,188 research outputs found

    Homosexual Orientation in Males: Evolutionary and Ethological Aspects

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    Evolutionary theory proposes that adaptive traits are reproduced more successfully than maladaptive traits. Accordingly, natural selection should favour heterosexuality as it facilitates reproduction and the propagation of genes. However, the question becomes, what has maintained homosexuality in a small but consistent percentage of the human population? Research into the evolutionary and hormonal factors associated with a homosexual orientation have yielded provocative but inconsistent results. It also suggests that human sexual orientation, and in particular homosexual orientation, is too complex to be described by one simple model or a single research discipline. The current paper treads a new path and emphasises an integrative approach for the understanding of homosexuality. The authors examine the combined effects of evolutionary factors and neurohormonal processes on the development of a homosexual orientation. It is suggested that research into the topic could benefit from an examination of and change in some of the assumptions upon which much past research has been based

    From single gene to phenotype: questioning a discrete gene in explaining phenotype diversity

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    The great diversity of phenotypes across organisms raises the question of how it emerged from the digital DNA sequence. Often the question is summarized as ‘how many genes do we really need?’ The benefit of answering this is readily apparent; particularly since sequencing the genome, research has sought the origin of normative and pathological phenotypes in our genes. However, in response, the literature will retort that neither the number of genes nor the size of the genome make robust predictions about phenotype complexity or diversity. For example, a common sea flea, Daphnia pulex, has ~31,000 genes, compared with our ~23,000. Given the gene-centric state of current biology, the questions these comparisons advance about the power of the gene are disconcerting. The remit of what follows is to address the value of quantifying genes to explain the phenotype. The heterogeneous nature of gene definitions in the literature necessitates brief discussion of gene ontology. Following this, I will discuss how function emerges from the transcript, and the resultant translated functional product. However, questioning the power of the gene should be taken in tandem with questioning its scope; this discussion will end on a brief survey of the proportion of the phenotype that should readily be attributed to non-DNA inheritance information, which highlights the need or systems-based approaches to phenotype variability.ReiDoCrea. Departamento de Psicología Social. Universidad de Granada

    A UV-visible prime focus camera for the Keck telescopes

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    Many areas of astronomical research rely on deep blue wide-field imaging. Mauna Kea enjoys the very best UV transparency from the ground and the Keck telescopes with 10 meter f/1.75 primaries are well suited to a prime focus camera with a large angular field. Swinburne University leads a proposal to provide a camera (KWFI, for Keck Wide Field Imager) that is optimized in the UV but works well to 1μm wavelength. Keck has interchangeable top end modules, of which one is now unused and easily capable of housing the required corrector lens and detector enclosure. This paper concentrates on details of the KWFI optical design

    Orbitofrontal epilepsy: Electroclinical analysis of surgical cases and literature review

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    Clinical and electrographic data were reviewed on 2 of our patients with orbitofrontal epilepsy who were seizure free at 5-year follow-up, and on 2 similar patients from the literature. One of our patients was lesional, and the other was nonlesional. Interictal EEG discharges were lateralized to the side of invasively recorded orbitofrontal seizures in the nonlesional case. In this case, no clinical manifestations occurred until the orbitofrontal discharge had spread to the opposite orbitofrontal and both mesial temporal areas. Unresponsiveness or arrest of activity were the initial manifestations of complex partial seizures in both cases. The 2 cases from the literature with long-term seizure-free follow-up had little impairment of awareness and displayed vigorous motor automatisms. Interictal epileptiform activity was bifrontally synchronous in 1 case. Ipsilateral frontotemporal discharges were seen in both. Invasive ictal epileptiform activity appeared maximal in the ipsilateral orbitofrontal region in both patients. No consistent electrographic or clinical pattern characterized these 4 cases. Seizures of orbitofrontal origin may be characterized by either unresponsiveness associated with oroalimentary automatisms or limited alteration of awareness and associated with vigorous motor automatisms. Invasive monitoring of the orbitofrontal cortex should be considered in nonlesional cases with complex partial seizures that show nonlocalizing ictal patterns and interictal frontal or frontotemporal epileptiform discharges. Copyright (C) 2004 S. Karger AG, Basel

    Unified dynamics of electrons and photons via Zitterbewegung and spin-orbit interaction

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    We show that when an electron or photon propagates in a cylindrically symmetric waveguide, it experiences both a Zitterbewegung effect and a spin-orbit interaction leading to identical propagation dynamics for both particles. Applying a unified perturbative approach to both particles simultaneously, we find that to first order in perturbation theory, their Hamiltonians each contain identical Darwin (Zitterbewegung) and spin-orbit terms, resulting in the unification of their dynamics. The presence of the Zitterbewegung effect may be interpreted physically as the delocalization of the electron on the scale of its Compton wavelength, or the delocalization of the photon on the scale of its wavelength in the waveguide. The presence of the spin-orbit interaction leads to the prediction of several rotational effects: the spatial or time evolution of either particle\u27s spin or polarization vector is controlled by the sign of its orbital angular momentum quantum number or, conversely, its spatial wave function is controlled by its spin angular momentum

    The Magic of Moonlight and Love

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    Contains advertisements and/or short musical examples of pieces being sold by publisher.https://digitalcommons.library.umaine.edu/mmb-vp/6960/thumbnail.jp
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