7,225 research outputs found

    Zombies, Epiphenomenalism and Personal Explanations: A Tension in Moreland's Argument from Consciousness

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    In his so-called argument from consciousness (AC), J. P. Moreland argues that the phenomenon of consciousness furnishes us with evidence for the existence of God. In defending AC, however, Moreland makes claims that generate an undesirable tension. This tension can be posed as a dilemma based on the contingency of the correlation between mental and physical states. The correlation of mental and physical states is either contingent or necessary. If the correlation is contingent then epiphenomenalism is true. If the correlation is necessary then a theistic explanation for the correlation is forfeit. Both are unwelcome results for A

    The Influence of Suffering, Social Class, and Social Power on Prosociality: An Empirical Review

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    An emerging body of research has shed light on the effects of social‐environmental factors, such as exposure to suffering, social class, and social power on prosocial orientation (i.e., empathy and compassion). This chapter aims to provide an overview of these areas of research that examined how the aforementioned social‐environmental factors may accentuate or attenuate one’s tendency to be prosocial. In addition, this chapter explores the theoretical implications across these areas and its potential for future research

    A Niche for Adult Neurogenesis: Analysis of BMP Signaling and Transcriptional Profiles of Adult Subventricular Zone Cells

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    Neurogenesis persists in restricted regions of the adult vertebrate brain. The largest region of adult neurogenesis is the subventricular zone (SVZ) of the lateral ventricle wall. Neural stem cells reside in the SVZ. The S V Z cell types and molecular signals necessary for this neurogenic niche were poorly understood. Here, I first demonstrate that astrocyte-like cells in the SVZ (type B cells) can self-renew and differentiate into mature brain cells. This data contributed to the identification of type B cells as the S V Z stem cell. In vivo, all S V Z cell types are in direct contact with type B cells. By reconstituting cell-cell interactions of dissociated SVZ cells in culture, I defined an in vitro cellular environment that recapitulates SVZ neurogenesis; these cultures provided an in vitro assay for the study of external molecular signals that regulate S V Z neurogenesis. Ependymal cells lie adjacent to the SVZ. I show that the bone morphogenetic protein (BMP) antagonist Noggin is expressed by ependymal cells and that S V Z cells express B M P s as well as their receptors. In vitro, B M P signaling potently inhibited neurogenesis. Conversely, Noggin protein in vitro promoted neurogenesis. Overexpression of BMPs in ependymal cells decreased SVZ cell proliferation and abolished type A cell regeneration. Ectopic Noggin expression in the normally nonneurogenic striatum promoted neuronal differentiation of transplanted S V Z cells. I thus propose that ependymal Noggin production creates a neurogenic niche in the adjacent SVZ by antagonizing B M P signaling. To identify other genes with roles in the SVZ, I utilized high-density oligonucleotide arrays to determine the transcriptional profiles of the S V Z region as well as purified type B and ependymal cells. SVZ regional and cell-specific expression profiles were compared to those of other brain regions. Differential gene expression was validated by Northern blot and histological techniques. This transcriptional profile data provides new markers and candidate regulatory genes for future investigations into the SVZ neurogenic niche

    Hydrides in zirconium alloys.

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    Hubble Frontier Field Free-Form Mass Mapping of the Massive Multiple-Merging Cluster MACSJ0717.5+3745

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    We examine the latest data on the cluster MACSJ0717.5+3745 from the Hubble Frontier Fields campaign. The critically lensed area is the largest known of any lens and very irregular making it a challenge for parametric modelling. Using our Free-Form method we obtain an accurate solution, identify here many new sets of multiple images, doubling the number of constraints and improving the reconstruction of the dark matter distribution. Our reconstructed mass map shows several distinct central substructures with shallow density profiles, clarifying earlier work and defining well the relation between the dark matter distribution and the luminous and X-ray peaks within the critically lensed region. Using our free-form method, we are able to meaningfully subtract the mass contribution from cluster members to the deflection field to trace the smoothly distributed cluster dark matter distribution. We find 4 distinct concentrations, 3 of which are coincident with the luminous matter. The fourth peak has a significant offset from both the closest luminous and X-ray peaks. These findings, together with dynamical data from the motions of galaxies and gas will be important for uncovering the potentially important implications of this extremely massive and intriguing system.Comment: 16 pages, 10 figures, 2 tables. Matches the verson submitted to mnras. New table (A2) included with additional system candidate

    From the trap to the basket: getting to the bottom of the nuclear pore complex

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    Nuclear pore complexes (NPCs) are large supramolecular assemblies that perforate the double-membraned nuclear envelope and serve as the sole gateways of molecular exchange between the cytoplasm and the nucleus in interphase cells. Combining novel specimen preparation regimes with innovative use of high-resolution scanning electron microscopy, Hans Ris produced in the late eighties stereo images of the NPC with unparalleled clarity and structural detail, thereby setting new standards in the field. Since that time, efforts undertaken to resolve the molecular structure and architecture, and the numerous interactions that occur between NPC proteins (nucleoporins), soluble transport receptors, and the small GTPase Ran, have led to a deeper understanding of the functional role of NPCs in nucleocytoplasmic transport. In spite of these breakthroughs, getting to the bottom of the actual cargo translocation mechanism through the NPC remains elusive and controversial. Here, we review recent insights into NPC function by correlating structural findings with biochemical data. By introducing new experimental and computational results, we reexamine how NPCs can discriminate between receptor-mediated and passive cargo to promote vectorial translocation in a highly regulated manner. Moreover, we comment on the importance and potential benefits of identifying and experimenting with individual key components implicated in the translocation mechanism. We conclude by dwelling on questions that we feel are pertinent to a more rational understanding of the physical aspects governing NPC mechanics. Last but not least, we substantiate these uncertainties by boldly suggesting a new direction in NPC research as a means to verify such novel concepts, for example, a de novo designed ‘minimalist' NP

    A Rigorous Free-form Lens Model of Abell 2744 to Meet the Hubble Frontier Fields Challenge

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    Hubble Frontier Fields (HFF) imaging of the most powerful lensing clusters provides access to the most magnified distant galaxies. The challenge is to construct lens models capable of describing these complex massive, merging clusters so that individual lensed systems can be reliably identified and their intrinsic properties accurately derived. We apply the free-form lensing method (WSLAP+) to A2744, providing a model independent map of the cluster mass, magnification, and geometric distance estimates to multiply-lensed sources. We solve simultaneously for a smooth cluster component on a pixel grid, together with local deflections by the cluster member galaxies. Combining model prediction with photometric redshift measurements, we correct and complete several systems recently claimed, and identify 4 new systems - totalling 65 images of 21 systems spanning a redshift range of 1.4<z<9.8. The reconstructed mass shows small enhancements in the directions where significant amounts of hot plasma can be seen in X-ray. We compare photometric redshifts with "geometric redshifts", finding a high level of self-consistency. We find excellent agreement between predicted and observed fluxes - with a best-fit slope of 0.999+-0.013 and an RMS of ~0.25 mag, demonstrating that our magnification correction of the lensed background galaxies is very reliable. Intriguingly, few multiply-lensed galaxies are detected beyond z~7.0, despite the high magnification and the limiting redshift of z~11.5 permitted by the HFF filters. With the additional HFF clusters we can better examine the plausibility of any pronounced high-z deficit, with potentially important implications for the reionization epoch and the nature of dark matter.Comment: Accepted for publication in ApJ with newly identified lensed images in complete HFF dat
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