413 research outputs found

    Telephone Transmission and Earwitnesses: Performance on Voice Parades Controlled for Voice Similarity.

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    The effect of telephone transmission on a listener's ability to recognise a speaker in a voice parade is investigated. A hundred listeners (25 per condition) heard 1 of 5 'target' voices, then returned a week later for a voice parade. The 4 conditions were: target exposure and parade both at studio quality; exposure and parade both at telephone quality; studio exposure with telephone parade, and vice versa. Fewer correct identifications followed from telephone exposure and parade (64%) than from studio exposure and parade (76%). Fewer still resulted for studio exposure/telephone parade (60%) and, dramatically, only 32% for telephone exposure/studio parade. Certain speakers were identified more readily than others across all conditions. Confidence ratings reflected this effect of speaker, but not the effect of exposure/parade condition.ESRC; British AcademyThis is the author accepted manuscript. The final version is available from Karger via http://dx.doi.org/10.1159/00043938

    Investigation of Systematic Bias in Radiometric Diameter Determination of Near-Earth Asteroids: the Night Emission Simulated Thermal Model (NESTM)

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    The Near-Earth Asteroid Thermal Model (NEATM, Harris, 1998) has proven to be a reliable simple thermal model for radiometric diameter determination. However NEATM assumes zero thermal emission on the night side of an asteroid. We investigate how this assumption affects the best-fit beaming parameter, overestimates the effective diameter and underestimates the albedo at large phase angles, by testing NEATM on thermal IR fluxes generated from simulated asteroid surfaces with different thermal inertia. We compare NEATM to radar diameters and find that NEATM overestimates the diameter when the beaming parameter is fitted to multi-wavelength observations and underestimates the diameter when the default beaming parameter is used. The Night Emission Simulated Thermal Model (NESTM) is introduced. NESTM models the night side temperature as an iso-latitudinal fraction (f) of the maximum day side temperature (Maximum temperature calculated for NEATM with beaming parameter = 1). A range of f is found for different thermal parameters, which depend on the thermal inertia. NESTM diameters are compared with NEATM and radar diameters, and it is shown that NESTM may reduce the systematic bias in overestimating diameters. It is suggested that a version of the NESTM which assumes the thermal inertia = 200 S.I. units is adopted as a default model when the solar phase angle is greater than 45 degrees.Comment: 48 pages, 10 Figures, 5 Table

    Orbits of Near-Earth Asteroid Triples 2001 SN263 and 1994 CC: Properties, Origin, and Evolution

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    Three-body model fits to Arecibo and Goldstone radar data reveal the nature of two near-Earth asteroid triples. Triple-asteroid system 2001 SN263 is characterized by a primary of ~10^13 kg, an inner satellite ~1% as massive orbiting at ~3 primary radii in ~0.7 days, and an outer satellite ~2.5% as massive orbiting at ~13 primary radii in ~6.2 days. 1994 CC is a smaller system with a primary of mass ~2.6 \times 10^11 kg and two satellites ~2% and ~1% as massive orbiting at distances of ~5.5 and ~19.5 primary radii. Their orbital periods are ~1.2 and ~8.4 days. Examination of resonant arguments shows that the satellites are not currently in a mean-motion resonance. Precession of the apses and nodes are detected in both systems (2001 SN263 inner body: d{\varpi}/dt ~1.1 deg/day, 1994 CC inner body: d{\varpi}/dt ~ -0.2 deg/day), which is in agreement with analytical predictions of the secular evolution due to mutually interacting orbits and primary oblateness. Nonzero mutual inclinations between the orbital planes of the satellites provide the best fits to the data in both systems (2001 SN263: ~14 degrees, 1994 CC: ~16 degrees). Our best-fit orbits are consistent with nearly circular motion, except for 1994 CC's outer satellite which has an eccentric orbit of e ~ 0.19. We examine several processes that can generate the observed eccentricity and inclinations, including the Kozai and evection resonances, past mean-motion resonance crossings, and close encounters with terrestrial planets. In particular, we find that close planetary encounters can easily excite the eccentricities and mutual inclinations of the satellites' orbits to the currently observed values.Comment: 17 pages, accepted to Astronomical Journa

    Validity of low-contrast letter acuity as a visual performance outcome measure for multiple sclerosis.

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    Low-contrast letter acuity (LCLA) has emerged as the leading outcome measure to assess visual disability in multiple sclerosis (MS) research. As visual dysfunction is one of the most common manifestations of MS, sensitive visual outcome measures are important in examining the effect of treatment. Low-contrast acuity captures visual loss not seen in high-contrast visual acuity (HCVA) measurements. These issues are addressed by the MS Outcome Assessments Consortium (MSOAC), including representatives from advocacy organizations, Food and Drug Administration (FDA), European Medicines Agency (EMA), National Institute of Neurological Disorders and Stroke (NINDS), academic institutions, and industry partners along with persons living with MS. MSOAC goals are acceptance and qualification by regulators of performance outcomes that are highly reliable and valid, practical, cost-effective, and meaningful to persons with MS. A critical step is elucidation of clinically relevant benchmarks, well-defined degrees of disability, and gradients of change that are clinically meaningful. This review shows that MS and disease-free controls have similar median HCVA, while MS patients have significantly lower LCLA. Deficits in LCLA and vision-specific quality of life are found many years after an episode of acute optic neuritis, even when HCVA has recovered. Studies reveal correlations between LCLA and the Expanded Disability Status Score (EDSS), Multiple Sclerosis Functional Composite (MSFC), retinal nerve fiber layer (RNFL) and ganglion cell layer plus inner plexiform layer (GCL + IPL) thickness on optical coherence tomography (OCT), brain magnetic resonance imaging (MRI), visual evoked potential (VEP), electroretinogram (ERG), pupillary function, and King-Devick testing. This review also concludes that a 7-point change in LCLA is clinically meaningful. The overall goal of this review is to describe and characterize the LCLA metric for research and clinical use among persons with MS

    Cryptic Eimeria genotypes are common across the southern but not northern hemisphere

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    The phylum Apicomplexa includes parasites of medical, zoonotic and veterinary significance. Understanding the global distribution and genetic diversity of these protozoa is of fundamental importance for efficient, robust and long-lasting methods of control. Eimeria spp. cause intestinal coccidiosis in all major livestock animals and are the most important parasites of domestic chickens in terms of both economic impact and animal welfare. Despite having significant negative impacts on the efficiency of food production, many fundamental questions relating to the global distribution and genetic variation of Eimeria spp. remain largely unanswered. Here, we provide the broadest map yet of Eimeria occurrence for domestic chickens, confirming that all the known species (Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, Eimeria tenella) are present in all six continents where chickens are found (including 21 countries). Analysis of 248 internal transcribed spacer sequences derived from 17 countries provided evidence of possible allopatric diversity for species such as E. tenella (FST values ⩽0.34) but not E. acervulina and E. mitis, and highlighted a trend towards widespread genetic variance. We found that three genetic variants described previously only in Australia and southern Africa (operational taxonomic units x, y and z) have a wide distribution across the southern, but not the northern hemisphere. While the drivers for such a polarised distribution of these operational taxonomic unit genotypes remains unclear, the occurrence of genetically variant Eimeria may pose a risk to food security and animal welfare in Europe and North America should these parasites spread to the northern hemisphere

    Radar Observations and the Shape of Near-Earth Asteroid 2008 EV5

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    We observed the near-Earth asteroid 2008 EV5 with the Arecibo and Goldstone planetary radars and the Very Long Baseline Array during December 2008. EV5 rotates retrograde and its overall shape is a 400 /pm 50 m oblate spheroid. The most prominent surface feature is a ridge parallel to the asteroid's equator that is broken by a concavity 150 m in diameter. Otherwise the asteroid's surface is notably smooth on decameter scales. EV5's radar and optical albedos are consistent with either rocky or stony-iron composition. The equatorial ridge is similar to structure seen on the rubble-pile near-Earth asteroid (66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid in the past. We interpret the concavity as an impact crater. Shaking during the impact and later regolith redistribution may have erased smaller features, explaining the general lack of decameter-scale surface structure.Comment: This paper has been accepted for publication in Icarus: http://www.sciencedirect.com/science/article/B6WGF-5207B2F-4/2/d87cd2ae4da00c2b277e2dc79a532c4

    Evaluation and Validation of a Real-Time PCR Assay for Detection and Quantitation of Human Adenovirus 14 from Clinical Samples

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    In 2007, the Centers for Disease Control and Prevention (CDC) reported that Human adenovirus type 14 (HAdV-14) infected 106 military personnel and was responsible for the death of one U.S. soldier at Lackland Air Force Base in Texas. Identification of the responsible adenovirus, which had not previously been seen in North America and for which rapid diagnostic tools were unavailable, required retrospective analysis at reference laboratories. Initial quarantine measures were also reliant on relatively slow traditional PCR analysis at other locations. To address this problem, we developed a real-time PCR assay that detects a 225 base pair sequence in the HAdV-14a hexon gene. Fifty-one oropharyngeal swab specimens from the Naval Health Research Center, San Diego, CA and Advanced Diagnostic Laboratory, Lackland AFB, TX were used to validate the new assay. The described assay detected eight of eight and 19 of 19 confirmed HAdV-14a clinical isolates in two separate cohorts from respiratory disease outbreaks. The real-time PCR assay had a wide dynamic range, detecting from 102 to 107 copies of genomic DNA per reaction. The assay did not cross-react with other adenoviruses, influenza, respiratory syncytial virus, or common respiratory tract bacteria. The described assay is easy to use, sensitive and specific for HAdV-14a in clinical throat swab specimens, and very rapid since turnaround time is less than four hours to obtain an answer

    Physical characterisation of near-Earth asteroid (1620) Geographos: reconciling radar and thermal-infrared observations

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    Context. The Yarkovsky (orbital drift) and YORP (spin state change) effects play important roles in the dynamical and physical evolution of asteroids. Thermophysical modelling of these observed effects, and of thermal-infrared observations, allows a detailed physical characterisation of an individual asteroid to be performed. Aims. We perform a detailed physical characterisation of near-Earth asteroid (1620) Geographos, a potential meteor stream source and former spacecraft target, using the same techniques as previously used for (1862) Apollo. Methods. We use the advanced thermophysical model (ATPM) on published light-curve, radar, and thermal-infrared observations to constrain the thermophysical properties of Geographos. The derived properties are used to make detailed predictions of the Yarkovsky orbital drift and YORP rotational acceleration, which are then compared against published measurements to determine Geographos’s bulk density. Results. We find that Geographos has a thermal inertia of 340-100+140 J m-2 k-1s-1/2, a roughness fraction of ≥50%, and a bulk density of 2100-450+550 kg m-3 when using the light-curve-derived shape model with the radar-derived maximum equatorial diameter of 5.04 ± 0.07 km. It is also found that the radar observations had overestimated the z-axis in Geographos’s shape model because of their near-equatorial view. This results in a poor fit to the thermal-infrared observations if its effective diameter is kept fixed in the model fitting. Conclusions. The thermal inertia derived for Geographos is slightly higher than the typical values for a near-Earth asteroid of its size, and its derived bulk density suggests a rubble-pile interior structure. Large uncertainties in shape model z-axes are likely to explain why radar and thermal-infrared observations sometimes give inconsistent diameter determinations for other asteroids
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