321 research outputs found

    Wide Angle: Eadweard Muybridge, the Pacific Coast, and Trans-Indigenous Representation

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    Eadweard Muybridge's Pacific Coast photographs provide an important site for investigating Victorian visual practices and their relationship to imperial control. This essay's analysis of critical spatiality engages with the familiar temporal dimension of the "long nineteenth century" through discussions of periodicity and the representation of timescales in nineteenth-century media

    Resolved Magnetic Field Mapping of a Molecular Cloud Using GPIPS

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    We present the first resolved map of plane-of-sky magnetic field strength for a quiescent molecular cloud. GRSMC 45.60+0.30 subtends 40 x 10 pc at a distance of 1.88 kpc, masses 16,000 M_sun, and exhibits no star formation. Near-infrared background starlight polarizations were obtained for the Galactic Plane Infrared Polarization Survey using the 1.8 m Perkins telescope and the Mimir instrument. The cloud area of 0.78 deg2 contains 2684 significant starlight polarizations for Two Micron All Sky Survey matched stars brighter than 12.5 mag in the H band. Polarizations are generally aligned with the cloud's major axis, showing an average position angle dispersion of 15 \pm 2{\deg} and polarization of 1.8 \pm 0.6%. The polarizations were combined with Galactic Ring Survey 13CO spectroscopy and the Chandrasekhar-Fermi method to estimate plane-of-sky magnetic field strengths, with an angular resolution of 100 arcsec. The average plane-of-sky magnetic field strength across the cloud is 5.40 \pm 0.04 {\mu}G. The magnetic field strength map exhibits seven enhancements or "magnetic cores." These cores show an average magnetic field strength of 8.3 \pm 0.9 {\mu}G, radius of 1.2 \pm 0.2 pc, intercore spacing of 5.7 \pm 0.9 pc, and exclusively subcritical mass-to-flux ratios, implying their magnetic fields continue to suppress star formation. The magnetic field strength shows a power-law dependence on gas volume density, with slope 0.75 \pm 0.02 for n_{H_2} >=10 cm-3. This power-law index is identical to those in studies at higher densities, but disagrees with predictions for the densities probed here.Comment: 11 pages, 15 figures, published in ApJ (2012, 755, 130

    Variable Radio Sources in the Galactic Plane

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    Using three epochs of VLA observations of the Galactic Plane in the first quadrant taken ~15 years apart, we have conducted a search for a population of variable Galactic radio emitters in the flux density range 1-100 mJy at 6 cm. We find 39 variable sources in a total survey area of 23.2 sq deg. Correcting for various selection effects and for the extragalactic variable population of active galactic nuclei, we conclude there are ~1.6 Galactic sources per sq deg which vary by more than 50% on a time scale of years (or shorter). We show that these sources are much more highly variable than extragalactic objects; more than 50% show variability by a factor >2 compared to <10% for extragalactic objects in the same flux density range. We also show that the fraction of variable sources increases toward the Galactic center (another indication that this is a Galactic population), and that the spectral indices of many of these sources are flat or inverted. A small number of the variables are coincident with mid-IR sources and two are coincident with X-ray emitters, but most have no known counterparts at other wavelengths. Intriguingly, one lies at the center of a supernova remnant, while another appears to be a very compact planetary nebula; several are likely to represent activity associated with star formation regions. We discuss the possible source classes which could contribute to the variable cohort and followup observations which could clarify the nature of these sources.Comment: 11 pages, 7 figures; to be published in the Astronomical Journal; data available on MAGPIS website at http://third.ucllnl.org/gps

    The pseudo-mitochondrial genome influences mistakes in heteroplasmy interpretation

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    BACKGROUND: Nuclear mitochondrial pseudogenes (numts) are a potential source of contamination during mitochondrial DNA PCR amplification. This possibility warrants careful experimental design and cautious interpretation of heteroplasmic results. RESULTS: Here we report the cloning and sequencing of numts loci, amplified from human tissue and rho-zero (ρ(0)) cells (control) with primers known to amplify the mitochondrial genome. This paper is the first to fully sequence 46 paralogous nuclear DNA fragments that represent the entire mitochondrial genome. This is a surprisingly small number due primarily to the primer sets used in this study, because prior to this, BLAST searches have suggested that nuclear DNA harbors between 400 to 1,500 paralogous mitochondrial DNA fragments. Our results indicate that multiple numts were amplified simultaneously with the mitochondrial genome and increased the load of pseudogene signal in PCR reactions. Further, the entire mitochondrial genome was represented by multiple copies of paralogous nuclear sequences. CONCLUSION: These findings suggest that mitochondrial genome disease-associated biomarkers must be rigorously authenticated to preclude any affiliation with paralogous nuclear pseudogenes. Importantly, the common perception that mitochondrial template "swamps" numts loci precluding detectable amplification, depends on the region of the mitochondrial genome targeted by the PCR reaction and the number of pseudogene loci that may co-amplify. Cloning and relevant sequencing data will facilitate the correct interpretation. This is the first complete, wet-lab characterization of numts that represent the entire mitochondrial genome

    THE K2 M67 STUDY: REVISITING OLD FRIENDS WITH K2 REVEALS OSCILLATING RED GIANTS IN THE OPEN CLUSTER M67

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    Observations of stellar clusters have had a tremendous impact in forming our understanding of stellar evolution. The open cluster M67 has a particularly important role as a calibration benchmark for stellar evolution theory due to its near-solar composition and age. As a result, it has been observed extensively, including attempts to detect solar-like oscillations in its main sequence and red giant stars. However, any asteroseismic inference has so far remained elusive due to the difficulty in measuring these extremely low-amplitude oscillations. Here we report the first unambiguous detection of solar-like oscillations in the red giants of M67. We use data from the Kepler ecliptic mission, K2, to measure the global asteroseismic properties. We find a model-independent seismic-informed distance of 816 ±11 pc, or (m - M)0 = 9.57 ± 0.03 mag, an average red giant mass of 1.36 ± 0.01 M⊙, in agreement with the dynamical mass from an eclipsing binary near the cluster turn-off, and ages of individual stars compatible with isochrone fitting. We see no evidence of strong mass loss on the red giant branch. We also determine seismic of all the cluster giants with a typical precision of ∼0.01 dex. Our results generally show good agreement with independent methods and support the use of seismic scaling relations to determine global properties of red giant stars with near-solar metallicity. We further illustrate that the data are of such high quality that future work on individual mode frequencies should be possible, which would extend the scope of seismic analysis of this cluster

    Arylsulfatase B Activity in Cultured Retinal Pigment Epithelium: Regional Studies in Feline Mucopolysaccharidosis VI

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    eline mucopolysaccharidosis VI (MPS VI) is a recessively inherited lysosomal storage disease resulting from a deficiency of arylsulfatase B (ASB). Previous histopathologic findings have indicated that the disease is expressed morphologically in non-pigmented retinal pigment epithelial cells (RPE) in the posterior pole and superior equatorial regions by the accumulation of vacuolated inclusions and eventual cellular hypertrophy, while pigmented regions in the periphery are minimally affected. To determine if the regional and age-dependent variations in disease severity result from differences in residual enzyme activity, primary cultures of feline MPS Vl-affected RPE were initiated from defined regions of the eye and maintained in vitro for 14 days. Cultures initiated from nonpigmented areas of affected adult eyes (posterior pole, superior equatorial) were more diseased than those from pigmented (inferior-equatorial, peripheral) areas. In the nonpigmented cultures, the disease was expressed by the accumulation of single membrane-bound inclusions and cellular hypertrophy. These inclusions were indistinguishable in their morphologic appearance and distribution from those found in situ. In contrast, the cultures initiated from pigmented areas remained normal or minimally affected. The same spatial disease distribution was present in young affected eyes, but the expression of the disease was much less severe. It is apparent that temporal, spatial, and pigmentation factors were correlated with disease expression in vitro as well as in situ. Arylsulfatase B activity was measured biochemically, and found to be deficient in all regions of young and adult eyes. It was notable that there was no correlation between the level of residual enzyme activity, and the pigmentation or spatial position from which the cells were obtained. Thus, variations in residual enzyme activities cannot account for the spatial and temporal differences in disease severity. Invest Ophthalmol Vi

    Bestrophin Gene Mutations Cause Canine Multifocal Retinopathy: A Novel Animal Model for Best Disease

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    PURPOSE. Canine multifocal retinopathy (cmr) is an autosomal recessive disorder of multiple dog breeds. The disease shares a number of clinical and pathologic similarities with Best macular dystrophy (BMD), and cmr is proposed as a new large animal model for Best disease. METHODS. cmr was characterized by ophthalmoscopy and histopathology and compared with BMD-affected patients. BEST1 (alias VMD2), the bestrophin gene causally associated with BMD, was evaluated in the dog. Canine ortholog cDNA sequence was cloned and verified using RPE/choroid 5′- and 3′-RACE. Expression of the canine gene transcripts and protein was analyzed by Northern and Western blotting and immunocytochemistry. All exons and the flanking splice junctions were screened by direct sequencing. RESULTS. The clinical phenotype and pathology of cmr closely resemble lesions of BMD. Canine VMD2 spans 13.7 kb of genomic DNA on CFA18 and shows a high level of conservation among eukaryotes. The transcript is predominantly expressed in RPE/choroid and encodes bestrophin, a 580-amino acid protein of 66 kDa. Immunocytochemistry of normal canine retina demonstrated specific localization of protein to the RPE basolateral plasma membranes. Two disease-specific sequence alterations were identified in the canine VMD2 gene: a C73T stop mutation in cmr1 and a G482A missense mutation in cmr2. CONCLUSIONS. The authors propose these two spontaneous mutations in the canine VMD2 gene, which cause cmr, as the first naturally occurring animal model of BMD. Further development of the cmr models will permit elucidation of the complex molecular mechanism of these retinopathies and the development of potential therapies

    Detection of the Power Spectrum of Cosmic Microwave Background Lensing by the Atacama Cosmology Telescope

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    We report the first detection of the gravitational lensing of the cosmic microwave background through a measurement of the four-point correlation function in the temperature maps made by the Atacama Cosmology Telescope. We verify our detection by calculating the levels of potential contaminants and performing a number of null tests. The resulting convergence power spectrum at 2-degree angular scales measures the amplitude of matter density fluctuations on comoving length scales of around 100 Mpc at redshifts around 0.5 to 3. The measured amplitude of the signal agrees with Lambda Cold Dark Matter cosmology predictions. Since the amplitude of the convergence power spectrum scales as the square of the amplitude of the density fluctuations, the 4-sigma detection of the lensing signal measures the amplitude of density fluctuations to 12%.Comment: 4 pages, 4 figures, replaced title and author list with version accepted by Physical Review Letters. Likelihood code can be downloaded from http://bccp.lbl.gov/~sudeep/ACTLensLike.htm

    Planetary Candidates Observed by Kepler. VIII. A Fully Automated Catalog With Measured Completeness and Reliability Based on Data Release 25

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    We present the Kepler Object of Interest (KOI) catalog of transiting exoplanets based on searching four years of Kepler time series photometry (Data Release 25, Q1-Q17). The catalog contains 8054 KOIs of which 4034 are planet candidates with periods between 0.25 and 632 days. Of these candidates, 219 are new and include two in multi-planet systems (KOI-82.06 and KOI-2926.05), and ten high-reliability, terrestrial-size, habitable zone candidates. This catalog was created using a tool called the Robovetter which automatically vets the DR25 Threshold Crossing Events (TCEs, Twicken et al. 2016). The Robovetter also vetted simulated data sets and measured how well it was able to separate TCEs caused by noise from those caused by low signal-to-noise transits. We discusses the Robovetter and the metrics it uses to sort TCEs. For orbital periods less than 100 days the Robovetter completeness (the fraction of simulated transits that are determined to be planet candidates) across all observed stars is greater than 85%. For the same period range, the catalog reliability (the fraction of candidates that are not due to instrumental or stellar noise) is greater than 98%. However, for low signal-to-noise candidates between 200 and 500 days around FGK dwarf stars, the Robovetter is 76.7% complete and the catalog is 50.5% reliable. The KOI catalog, the transit fits and all of the simulated data used to characterize this catalog are available at the NASA Exoplanet Archive.Comment: 61 pages, 23 Figures, 9 Tables, Accepted to The Astrophysical Journal Supplement Serie

    The Atacama Cosmology Telescope: Sunyaev Zel'dovich Selected Galaxy Clusters at 148 GHz in the 2008 Survey

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    We report on twenty-three clusters detected blindly as Sunyaev-Zel'dovich (SZ) decrements in a 148 GHz, 455 square-degree map of the southern sky made with data from the Atacama Cosmology Telescope 2008 observing season. All SZ detections announced in this work have confirmed optical counterparts. Ten of the clusters are new discoveries. One newly discovered cluster, ACT-CL J0102-4915, with a redshift of 0.75 (photometric), has an SZ decrement comparable to the most massive systems at lower redshifts. Simulations of the cluster recovery method reproduce the sample purity measured by optical follow-up. In particular, for clusters detected with a signal-to-noise ratio greater than six, simulations are consistent with optical follow-up that demonstrated this subsample is 100% pure. The simulations further imply that the total sample is 80% complete for clusters with mass in excess of 6x10^14 solar masses referenced to the cluster volume characterized by five hundred times the critical density. The Compton y -- X-ray luminosity mass comparison for the eleven best detected clusters visually agrees with both self-similar and non-adiabatic, simulation-derived scaling laws.Comment: 13 pages, 7 figures, Accepted for publication in Ap
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