4,303 research outputs found

    Automatic Detection of Seizures with Applications

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    There are an estimated two million people with epilepsy in the United States. Many of these people do not respond to anti-epileptic drug therapy. Two devices can be developed to assist in the treatment of epilepsy. The first is a microcomputer-based system designed to process massive amounts of electroencephalogram (EEG) data collected during long-term monitoring of patients for the purpose of diagnosing seizures, assessing the effectiveness of medical therapy, or selecting patients for epilepsy surgery. Such a device would select and display important EEG events. Currently many such events are missed. A second device could be implanted and would detect seizures and initiate therapy. Both of these devices require a reliable seizure detection algorithm. A new algorithm is described. It is believed to represent an improvement over existing seizure detection algorithms because better signal features were selected and better standardization methods were used

    Photoacclimatization by the coral Montastraea cavernosa in the mesophotic zone: light, food, and genetics

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    Most studies on coral reefs have focused on shallow reef (<30 m) systems due to the technical limitations of conducting scientific diving deeper than 30 m. Compared to their shallow-water counterparts, these mesophotic coral reefs (30–150 m) are understudied, which has slowed our broader understanding of the biodiversity, ecology, and connectivity of shallow and deep coral reef communities. We know that the light environment is an important component of the productivity, physiology, and ecology of corals, and it restricts the distribution of most species of coral to depths of 60 m or less. In the Bahamas, the coral Montastraea cavernosa has a wide depth distribution, and it is one of the most numerous corals at mesophotic depths. Using a range of optical, physiological, and biochemical approaches, the relative dependence on autotrophy vs. heterotrophy was assessed for this coral from 3 to 91 m. These measurements show that the quantum yield of PSII fluorescence increases significantly with depth for M. cavernosa while gross primary productivity decreases with depth. Both morphological and physiological photoacclimatization occurs to a depth of 91 m, and stable isotope data of the host tissues, symbionts, and skeleton reveal a marked decrease in productivity and a sharp transition to heterotrophy between 45 and 61 m. Below these depths, significant changes in the genetic composition of the zooxanthellae community, including genotypes not previously observed, occur and suggest that there is strong selection for zooxanthellae that are suited for survival in the light-limited environment where mesophotic M. cavernosa are occurring

    Ear, nose and throat manifestations of Lyme disease

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    The manifestations of Lyme disease as they may present to the ENT surgeon are discussed. The most important ENT symptom is facial palsy. Particularly when combined with other cranial palsies, systemic illness or signs of meningeal irritation, the diagnosis must be considered. Three case reports are used to illustrate the presentation and diagnosis and treatment of Lyme disease. The characteristics of the disease are reviewed and the limitations of serological testing outlined. The literature has concentrated on bilateral or relapsing facial palsy. A review of palsies in Zurich that presented to the ENT clinic found only unilateral and partial palsies. The diagnosis should be considered in every case of facial palsy of unknown aetiology especially in childre

    An extended view of the Pisces Overdensity from the SCUSS survey

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    SCUSS is a u-band photometric survey covering about 4000 square degree of the South Galactic Cap, reaching depths of up to 23 mag. By extending around 1.5 mag deeper than SDSS single-epoch u data, SCUSS is able to probe much a larger volume of the outer halo, i.e. with SCUSS data blue horizontal branch (BHB) stars can trace the outer halo of the Milky Way as far as 100-150 kpc. Utilizing this advantage we combine SCUSS u band with SDSS DR9 gri photometric bands to identify BHB stars and explore halo substructures. We confirm the existence of the Pisces overdensity, which is a structure in the outer halo (at around 80 kpc) that was discovered using RR Lyrae stars. For the first time we are able to determine its spatial extent, finding that it appears to be part of a stream with a clear distance gradient. The stream, which is ~5 degrees wide and stretches along ~25 degrees, consists of 20-30 BHBs with a total significance of around 6sigma over the background. Assuming we have detected the entire stream and that the progenitor has fully disrupted, then the number of BHBs suggests the original system was similar to smaller classical or a larger ultra-faint dwarf galaxy. On the other hand, if the progenitor still exists, it can be hunted for by reconstructing its orbit from the distance gradient of the stream. This new picture of the Pisces overdensity sheds new light on the origin of this intriguing system.Comment: 8 pages, 4 figures, accepted by Ap

    Advanced Camera for Surveys Observations of Young Star Clusters in the Interacting Galaxy UGC 10214

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    We present the first Advanced Camera for Surveys (ACS) observations of young star clusters in the colliding/merging galaxy UGC 10214. The observations were made as part of the Early Release Observation (ERO) program for the newly installed ACS during service mission SM3B for the Hubble Space Telescope (HST). Many young star clusters can be identified in the tails of UGC 10214, with ages ranging from ~3 Myr to 10 Myr. The extreme blue V-I (F606W-F814W) colors of the star clusters found in the tail of UGC 10214 can only be explained if strong emission lines are included with a young stellar population. This has been confirmed by our Keck spectroscopy of some of these bright blue stellar knots. The most luminous and largest of these blue knots has an absolute magnitude of M_V = -14.45, with a half-light radius of 161 pc, and if it is a single star cluster, would qualify as a super star cluster (SSC). Alternatively, it could be a superposition of multiple scaled OB associations or clusters. With an estimated age of ~ 4-5 Myr, its derived mass is < 1.3 x 10^6 solar masses. Thus the young stellar knot is unbound and will not evolve into a normal globular cluster. The bright blue clusters and associations are much younger than the dynamical age of the tail, providing strong evidence that star formation occurs in the tail long after it was ejected. UGC 10214 provides a nearby example of processes that contributed to the formation of halos and intra-cluster media in the distant and younger Universe.Comment: 6 pages with embedded figures, ApJ in pres

    Discovery of Globular Clusters in the Proto-Spiral NGC2915: Implications for Hierarchical Galaxy Evolution

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    We have discovered three globular clusters beyond the Holmberg radius in Hubble Space Telescope Advanced Camera for Surveys images of the gas-rich dark matter dominated blue compact dwarf galaxy NGC2915. The clusters, all of which start to resolve into stars, have M_{V606} = -8.9 to -9.8 mag, significantly brighter than the peak of the luminosity function of Milky Way globular clusters. Their colors suggest a metallicity [Fe/H] ~ -1.9 dex, typical of metal-poor Galactic globular clusters. The specific frequency of clusters is at a minimum normal, compared to spiral galaxies. However, since only a small portion of the system has been surveyed it is more likely that the luminosity and mass normalized cluster content is higher, like that seen in elliptical galaxies and galaxy clusters. This suggests that NGC2915 resembles a key phase in the early hierarchical assembly of galaxies - the epoch when much of the old stellar population has formed, but little of the stellar disk. Depending on the subsequent interaction history, such systems could go on to build-up larger elliptical galaxies, evolve into normal spirals, or in rare circumstances remain suspended in their development to become systems like NGC2915.Comment: ApJ Letters accepted; 6 pages, 2 figures, 3 table

    The Luminosity Function of Early-Type Galaxies at z~0.75

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    We measure the luminosity function of morphologically selected E/S0 galaxies from z=0.5z=0.5 to z=1.0z=1.0 using deep high resolution Advanced Camera for Surveys imaging data. Our analysis covers an area of 48\Box\arcmin (8×\times the area of the HDF-N) and extends 2 magnitudes deeper (I24I\sim24 mag) than was possible in the Deep Groth Strip Survey (DGSS). At 0.5<z<0.750.5<z<0.75, we find MB5logh0.7=21.1±0.3M_B^*-5\log h_{0.7}=-21.1\pm0.3 and α=0.53±0.2\alpha=-0.53\pm0.2, and at 0.75<z<1.00.75<z<1.0, we find MB5logh0.7=21.4±0.2M_B^*-5\log h_{0.7}=-21.4\pm0.2. These luminosity functions are similar in both shape and number density to the luminosity function using morphological selection (e.g., DGSS), but are much steeper than the luminosity functions of samples selected using morphological proxies like the color or spectral energy distribution (e.g., CFRS, CADIS, or COMBO-17). The difference is due to the `blue', (UV)0<1.7(U-V)_0<1.7, E/S0 galaxies, which make up to 30\sim30% of the sample at all magnitudes and an increasing proportion of faint galaxies. We thereby demonstrate the need for {\it both morphological and structural information} to constrain the evolution of galaxies. We find that the `blue' E/S0 galaxies have the same average sizes and Sersic parameters as the `red', (UV)0>1.7(U-V)_0>1.7, E/S0 galaxies at brighter luminosities (MB<20.1M_B<-20.1), but are increasingly different at fainter magnitudes where `blue' galaxies are both smaller and have lower Sersic parameters. Fits of the colors to stellar population models suggest that most E/S0 galaxies have short star-formation time scales (τ<1\tau<1 Gyr), and that galaxies have formed at an increasing rate from z8z\sim8 until z2z\sim2 after which there has been a gradual decline.Comment: 39 pages, 21 figures, accepted in A

    The SDSS-IV extended Baryon Oscillation Spectroscopic Survey: selecting emission line galaxies using the Fisher discriminant

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    We present a new selection technique of producing spectroscopic target catalogues for massive spectroscopic surveys for cosmology. This work was conducted in the context of the extended Baryon Oscillation Spectroscopic Survey (eBOSS), which will use ~200 000 emission line galaxies (ELGs) at 0.6<zspec<1.0 to obtain a precise baryon acoustic oscillation measurement. Our proposed selection technique is based on optical and near-infrared broad-band filter photometry. We used a training sample to define a quantity, the Fisher discriminant (linear combination of colours), which correlates best with the desired properties of the target: redshift and [OII] flux. The proposed selections are simply done by applying a cut on magnitudes and this Fisher discriminant. We used public data and dedicated SDSS spectroscopy to quantify the redshift distribution and [OII] flux of our ELG target selections. We demonstrate that two of our selections fulfil the initial eBOSS/ELG redshift requirements: for a target density of 180 deg^2, ~70% of the selected objects have 0.6<zspec<1.0 and only ~1% of those galaxies in the range 0.6<zspec<1.0 are expected to have a catastrophic zspec estimate. Additionally, the stacked spectra and stacked deep images for those two selections show characteristic features of star-forming galaxies. The proposed approach using the Fisher discriminant could, however, be used to efficiently select other galaxy populations, based on multi-band photometry, providing that spectroscopic information is available. This technique could thus be useful for other future massive spectroscopic surveys such as PFS, DESI, and 4MOST.Comment: Version published in A&

    Internal Color Properties of Resolved Spheroids in the Deep HST/ACS field of UGC 10214

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    (Abridged) We study the internal color properties of a morphologically selected sample of spheroidal galaxies taken from HST/ACS ERO program of UGC 10214 (``The Tadpole''). By taking advantage of the unprecedented high resolution of the ACS in this very deep dataset we are able to characterize spheroids at sub-arcseconds scales. Using the V_606W and I_814W bands, we construct V-I color maps and extract color gradients for a sample of spheroids at I_814W < 24 mag. We investigate the existence of a population of morphologically classified spheroids which show extreme variation in their internal color properties similar to the ones reported in the HDFs. These are displayed as blue cores and inverse color gradients with respect to those accounted from metallicity variations. Following the same analysis we find a similar fraction of early-type systems (~30%-40%) that show non-homologous internal colors, suggestive of recent star formation activity. We present two statistics to quantify the internal color variation in galaxies and for tracing blue cores, from which we estimate the fraction of non-homogeneous to homogeneous internal colors as a function of redshift up to z<1.2. We find that it can be described as about constant as a function of redshift, with a small increase with redshift for the fraction of spheroids that present strong color dispersions. The implications of a constant fraction at all redshifts suggests the existence of a relatively permanent population of evolving spheroids up to z~1. We discuss the implications of this in the context of spheroidal formation.Comment: Fixed URL for high resolution version. 13 Pages, 10 Figures. Accepted for Publication in ApJ. Sep 1st issue. Higher resolution version and complete table3B at http://acs.pha.jhu.edu/~felipe/e-prints/Tadpol
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