169 research outputs found

    Examining the Central and Peripheral Processes of Written Word Production Through Meta-Analysis

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    Producing written words requires “central” cognitive processes (such as orthographic long-term and working memory) as well as more peripheral processes responsible for generating the motor actions needed for producing written words in a variety of formats (handwriting, typing, etc.). In recent years, various functional neuroimaging studies have examined the neural substrates underlying the central and peripheral processes of written word production. This study provides the first quantitative meta-analysis of these studies by applying activation likelihood estimation (ALE) methods (Turkeltaub et al., 2002). For alphabet languages, we identified 11 studies (with a total of 17 experimental contrasts) that had been designed to isolate central and/or peripheral processes of word spelling (total number of participants = 146). Three ALE meta-analyses were carried out. One involved the complete set of 17 contrasts; two others were applied to subsets of contrasts to distinguish the neural substrates of central from peripheral processes. These analyses identified a network of brain regions reliably associated with the central and peripheral processes of word spelling. Among the many significant results, is the finding that the regions with the greatest correspondence across studies were in the left inferior temporal/fusiform gyri and left inferior frontal gyrus. Furthermore, although the angular gyrus (AG) has traditionally been identified as a key site within the written word production network, none of the meta-analyses found it to be a consistent site of activation, identifying instead a region just superior/medial to the left AG in the left posterior intraparietal sulcus. These meta-analyses and the discussion of results provide a valuable foundation upon which future studies that examine the neural basis of written word production can build

    Ischemia Induces P-Selectin-Mediated Selective Progenitor Cell Engraftment in the Isolated-Perfused Heart

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    Clinical trials infusing Bone Marrow Cells (BMCs) into injured hearts have produced measureable improvements in cardiac performance, but were insufficient to improve patient outcomes. Low engraftment rates are cited as probable contributor to limited improvements. To understand the mechanisms that control myocardial engraftment of BMCs following ischemia-reperfusion injury, in isolated–perfused mouse hearts, stop-flow ischemia was followed by variable-duration reperfusion (0–60 min) before addition of labeled syngenic BMCs to the perfusate. After a buffer-only wash, the heart was disaggregated. Retained BMCs (digest) and infused BMCs (aliquot) were compared by flow cytometry for c-kit and CD45 expression to determine the proportion of cell subtypes engrafted versus delivered (selectivity ratio). In these studies, a time-dependent selective retention of c-kit+ cells was apparent starting at 30 min of reperfusion, at which time c-kit+/CD45+ BMCs showed a selectivity ratio of 18 ± 2 (versus 2 ± 1 in sham-ischemic controls). To study the underlying mechanism for this selective retention, neutralizing antibodies for P-selectin or L-selectin were infused into the heart preparation and incubated with BMCs prior to BMC infusion. Blocking P-selectin in ischemic hearts ablated selectivity for c-kit+/CD45+ BMCs at 30 min reperfusion (selectivity ratio of 3 ± 1) while selectivity persisted in the presence of L-selectin neutralization (selectivity ratio of 17 ± 2). To corroborate this finding, a parallel plate flow chamber was used to study capture and rolling dynamics of purified c-kit+ versus c-kit- BMCs on various selectin molecules. C-kit+ BMCs interacted weakly with L-selectin substrates (0.03 ± 0.01% adhered) but adhered strongly to P-selectin (0.28 ± 0.04% adhered). C-kit- BMCs showed intermediate binding regardless of substrate (0.18 ± 0.04% adhered on L-selectin versus 0.17 ± 0.04% adhered on P-selectin). Myocardial ischemia–reperfusion stress induces selective engraftment of c-kit+ bone marrow progenitor cells via P-selectin activation

    Found in Translation: Collaborative Contemplations of Tibetan Buddhism and Western Science

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    Development of an inclusive scientific community necessitates doing more than simply bringing science to diverse groups of people. Ideally, the sciences evolve through incorporation of diverse backgrounds, experiences, and worldviews. Efforts to promote inclusion of historically underrepresented racial, ethnic, cultural, religious, gender, and socioeconomic groups among science scholars are currently underway. Examination of these efforts yields valuable lessons to inform next steps in engaging diverse audiences with science. The Emory-Tibet Science Initiative may serve as one example of such efforts. The Dalai Lama invited Emory University to develop and teach a curriculum in Western science to Tibetan Buddhist monks and nuns. As the science curriculum has been taught and refined over the past decade, monastic scholars increasingly have taken ownership of the material. As Western scientific ideas and practices take hold in this setting, the experiences of monks and nuns offer unique insights into the process of translation, modes of communication, and long-term impacts of integrating diverse systems of knowledge. Given that the dominant language of science is English, Tibetan interpreters have been essential throughout the implementation of this project. Through the process of translating scientific terms, interpreters have considered differences in how words categorize, and therefore how people conceptualize, the world. Through comprehensive, culturally-responsive communication, scientific language is used as a tool to build and strengthen connections between monastics and their local and global communities. The intertwining of these complementary systems of knowledge iteratively informs translation, modes of communication, and broader impacts in the community

    The Resolved Stellar Halo of NGC 253

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    We have obtained Magellan/IMACS and HST/ACS imaging data that resolve red giant branch stars in the stellar halo of the starburst galaxy NGC 253. The HST data cover a small area, and allow us to accurately interpret the ground-based data, which cover 30% of the halo to a distance of 30 kpc, allowing us to make detailed quantitative measurements of the global properties and structure of a stellar halo outside of the Local Group. The geometry of the halo is significantly flattened in the same sense as the disk, with a projected axis ratio of b/a ~ 0.35 +/- 0.1. The total stellar mass of the halo is estimated to be M_halo ~ 2.5 +/- 1.5 x 10^9 M_sun, or 6% of the total stellar mass of the galaxy, and has a projected radial dependence that follows a power law of index -2.8 +/- 0.6, corresponding to a three-dimensional power law index of ~ -4. The total luminosity and profile shape that we measure for NGC 253 are somewhat larger and steeper than the equivalent values for the Milky Way and M31, but are well within the scatter of model predictions for the properties of stellar halos built up in a cosmological context. Structure within the halo is seen at a variety of scales: there is small kpc-scale density variation and a large shelf-like feature near the middle of the field. The techniques that have been developed will be essential for quantitatively comparing our upcoming larger sample of observed stellar halos to models of halo formation.Comment: ApJ, in press. Version with full resolution figures available at http://www.astro.lsa.umich.edu/~jbailin/papers/bailin_n253halo.pd

    UV Circular Polarisation in Star Formation Regions : The Origin of Homochirality?

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    Ultraviolet circularly polarised light has been suggested as the initial cause of the homochirality of organic molecules in terrestrial organisms, via enantiomeric selection of prebiotic molecules by asymmetric photolysis. We present a theoretical investigation of mechanisms by which ultraviolet circular polarisation may be produced in star formation regions. In the scenarios considered here, light scattering produces only a small percentage of net circular polarisation at any point in space, due to the forward throwing nature of the phase function in the ultraviolet. By contrast, dichroic extinction can produce a fairly high percentage of net circular polarisation (∼10%) and may therefore play a key role in producing an enantiomeric excessPeer reviewe

    Transient Astrophysics Probe: White Paper

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    The Transient Astrophysics Probe (TAP) is a wide-field multi-wavelength transient mission proposed for flight starting in the late 2020s. The mission instruments include unique ``Lobster-eye'' imaging soft X-ray optics that allow an approximately 1600-degrees-squared Field of View (FoV); a high sensitivity, 1-degree-squared FoV soft X-ray telescope; a 1-degree-squared FoV Infrared telescope with bandpass 0.6 to 3 microns; and a set of 8 NaI gamma-ray detectors. TAP's most exciting capability will be the observation of tens per year of X-ray and Infrared counterparts of gravitational waves (GWs) involving stellar-mass black holes and neutron stars detected by LIGO (Laser Interferometer Gravitational-Wave Observatory ) / Virgo / KAGRA (Kamioka (Japan) Gravitational Wave Detector) / LIGO-India, and possibly several per year X-ray counterparts of GWs from supermassive black holes, detected by LISA (Laser Interferometer Space Antenna) and Pulsar Timing Arrays. TAP will also discover hundreds of X-ray transients related to compact objects, including tidal disruption events, supernova shock breakouts, and Gamma-Ray Bursts from the epoch of reionization

    THE ONSET OF MASSIVE STAR FORMATION: THE EVOLUTION OF TEMPERATURE AND DENSITY STRUCTURE IN AN INFRARED DARK CLOUD

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    We present new NH3 (1, 1), (2, 2), and (4, 4) observations from the Karl G. Jansky Very Large Array compiled with work in the literature to explore the range of conditions observed in young, massive star-forming regions. To sample the effects of evolution independent from those of distance/resolution, abundance, and large-scale environment, we compare clumps in different evolutionary stages within a single infrared dark cloud (IRDC), G32.02+0.06. We find that the early stages of clustered star formation are characterized by dense, parsec-scale filamentary structures interspersed with complexes of dense cores (60 pc) hosting the IRDC, hypothesizing that it may have been shaped by previous generations of massive stars

    A candidate regulatory variant at the TREM gene cluster associates with decreased Alzheimer's disease risk and increased TREML1 and TREM2 brain gene expression

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    Introduction: We hypothesized that common Alzheimer's disease (AD)-associated variants within the triggering receptor expressed on myeloid (TREM) gene cluster influence disease through gene expression. Methods: Expression microarrays on temporal cortex and cerebellum from ∼400 neuropathologically diagnosed subjects and two independent RNAseq replication cohorts were used for expression quantitative trait locus analysis. Results: A variant within a DNase hypersensitive site 5′ of TREM2, rs9357347-C, associates with reduced AD risk and increased TREML1 and TREM2 levels (uncorrected P = 6.3 × 10−3 and 4.6 × 10−2, respectively). Meta-analysis on expression quantitative trait locus results from three independent data sets (n = 1006) confirmed these associations (uncorrected P = 3.4 × 10−2 and 3.5 × 10−3, Bonferroni-corrected P = 6.7 × 10−2 and 7.1 × 10−3, respectively). Discussion: Our findings point to rs9357347 as a functional regulatory variant that contributes to a protective effect observed at the TREM locus in the International Genomics of Alzheimer's Project genome-wide association study meta-analysis and suggest concomitant increase in TREML1 and TREM2 brain levels as a potential mechanism for protection from AD
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