2,003 research outputs found

    A Regional Comparison of Intellectual Disability Rates in Appalachia

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    This study examined administrative prevalence rates of Intellectual Disability for children and adolescents within Southern West Virginia over a three-year-period compared to rates in neighboring Virginia counties with designated Appalachian status to determine if significantly different rates were evident, and if prevalence varied according to poverty, maternal age, and race/ethnicity across all districts. The results revealed that despite Southern West Virginia and Western Virginia being geographically similar, Southern West Virginia LEAs maintain significantly higher ID rates. Findings indicated poverty and teen pregnancy are correlated with higher ID rates but not race/ethnicity. The prevalence study points to the need for additional research including direct examination of identification practices in Appalachia, school psychologist-to-student ratios in high ID areas, and the disparities between state categories and identification of secondary disabilities, which aren’t reported through annual child counts

    Cover slip external cavity diode laser

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    The design of a 671 nm diode laser with a mode-hop-free tuning range of 40 GHz is described. This long tuning range is achieved by simultaneously ramping the external cavity length with the laser injection current. The external cavity consists of a microscope cover slip mounted on piezoelectric actuators. In such a configuration the laser output pointing remains fixed, independent of its frequency. Using a diode with an output power of 5-7 mW, the laser linewidth was found to be smaller than 30 MHz. This cover slip cavity and feedforward laser current control system is simple, economical, robust, and easy to use for spectroscopy, as we demonstrate with lithium vapor and lithium atom beam experiments.Comment: 7 pages, 6 figures, submitted to Review of Scientific Instruments 7/29/0

    Environmental Aspects of Advanced Nuclear Fuel Cycles: Parametric Modeling and Preliminary Analysis

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    Nuclear power has the potential to help reduce rising carbon emissions, but to be considered sustainable, it must also demonstrate the availability of an indefinite fuel supply as well as not produce any significant negative environmental effects. The objective of this research was to evaluate the sustainability of nuclear power and to explore the nuclear fuel cycles that best meet this goal. First, the study quantified current and promising nuclear fuel cycles to be further evaluated and developed a set of objective metrics to describe the environmental effects of each cycle. The metrics included such factors as the amount of waste generated and the isotopic composition of the waste. Next, the evaluation used the International Atomic Energy Agency's Nuclear Fuel Cycle Simulation System to compute nuclide compositions at various stages of the fuel cycles. Finally, the study looked at the radioactivity of the waste generated and used this and other characteristics to determine which fuel cycle meets the objectives of sustainability. Results confirm that incorporating recycling into the fuel cycle would help reduce the volume of waste needing to be stored long-term. Also, calculations made with data from the Nuclear Fuel Cycle Simulation System predicted that the waste from fuel cycles using recycling would be slightly more radiotoxic than the open fuel cycle?s waste. However, the small increase in radiotoxicity is a manageable issue and would not detract from the benefits of recycling. Therefore, recycling and reprocessing spent fuel must be incorporated into the nuclear fuel cycle to achieve sustainability

    Multi-messenger astronomy of gravitational-wave sources with flexible wide-area radio transient surveys

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    We explore opportunities for multi-messenger astronomy using gravitational waves (GWs) and prompt, transient low-frequency radio emission to study highly energetic astrophysical events. We review the literature on possible sources of correlated emission of gravitational waves and radio transients, highlighting proposed mechanisms that lead to a short-duration, high-flux radio pulse originating from the merger of two neutron stars or from a superconducting cosmic string cusp. We discuss the detection prospects for each of these mechanisms by low-frequency dipole array instruments such as LWA1, LOFAR and MWA. We find that a broad range of models may be tested by searching for radio pulses that, when de-dispersed, are temporally and spatially coincident with a LIGO/Virgo GW trigger within a \usim 30 second time window and \usim 200 \mendash 500 \punits{deg}^{2} sky region. We consider various possible observing strategies and discuss their advantages and disadvantages. Uniquely, for low-frequency radio arrays, dispersion can delay the radio pulse until after low-latency GW data analysis has identified and reported an event candidate, enabling a \emph{prompt} radio signal to be captured by a deliberately targeted beam. If neutron star mergers do have detectable prompt radio emissions, a coincident search with the GW detector network and low-frequency radio arrays could increase the LIGO/Virgo effective search volume by up to a factor of \usim 2. For some models, we also map the parameter space that may be constrained by non-detections.Comment: 31 pages, 4 figure

    Observations of Giant Pulses from Pulsar PSR B0950+08 using LWA1

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    We report the detection of giant pulse emission from PSR B0950+08 in 24 hours of observations made at 39.4 MHz, with a bandwidth of 16 MHz, using the first station of the Long Wavelength Array, LWA1. We detected 119 giant pulses from PSR B0950+08 (at its dispersion measure), which we define as having SNRs at least 10 times larger than for the mean pulse in our data set. These 119 pulses are 0.035% of the total number of pulse periods in the 24 hours of observations. The rate of giant pulses is about 5.0 per hour. The cumulative distribution of pulse strength SS is a steep power law, N(>S)S4.7N(>S)\propto S^{-4.7}, but much less steep than would be expected if we were observing the tail of a Gaussian distribution of normal pulses. We detected no other transient pulses in a dispersion measure range from 1 to 90 pc cm3^{-3}, in the beam tracking PSR B0950+08. The giant pulses have a narrower temporal width than the mean pulse (17.8 ms, on average, vs. 30.5 ms). The pulse widths are consistent with a previously observed weak dependence on observing frequency, which may be indicative of a deviation from a Kolmogorov spectrum of electron density irregularities along the line of sight. The rate and strength of these giant pulses is less than has been observed at \sim100 MHz. Additionally, the mean (normal) pulse flux density we observed is less than at \sim100 MHz. These results suggest this pulsar is weaker and produces less frequent giant pulses at 39 MHz than at 100 MHz.Comment: 27 pages, 12 figures, typos correcte

    Fishes of the hadal zone including new species, in situ observations and depth records of Liparidae

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    AbstractObservations and records for fish exceeding 6000m deep are few and often spurious. Recent developments in accessing and sampling the hadal zone 6000–11,000m) have led to an acceleration in new findings in the deep subduction trenches, particularly in the Pacific Ocean. This study describes the discovery of two new species of snailfish (Liparidae) from the Mariana Trench; the ‘Mariana snailfish’ (6198–8076m) and the ‘Ethereal snailfish’ (7939–8145m). These new findings represent respectively the deepest known specimen caught with corroborating depth data, and the deepest fish seen alive. Further specimens and observations of the Kermadec Trench snailfish, Notoliparis kermadecensis, are also presented, as well as the first hadal records of Synaphobranchidae and Zoarcidae (6068 and 6145m respectively) and a depth extension for the Macrouridae (maximum depth now 7012m). Details of these new snailfish specimens caught by baited trap and behaviour observations filmed by baited cameras are presented. An updated assessment of fishes from hadal depths is also reported

    Distribution, composition and functions of gelatinous tissues in deep-sea fishes

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    Many deep-sea fishes have a gelatinous layer, or subdermal extracellular matrix, below the skin or around the spine. We document the distribution of gelatinous tissues across fish families (approx. 200 species in ten orders), then review and investigate their composition and function. Gelatinous tissues from nine species were analysed for water content (96.53 ± 1.78% s.d.), ionic composition, osmolality, protein (0.39 ± 0.23%), lipid (0.69 ± 0.56%) and carbohydrate (0.61 ± 0.28%). Results suggest that gelatinous tissues are mostly extracellular fluid, which may allow animals to grow inexpensively. Further, almost all gelatinous tissues floated in cold seawater, thus their lower density than seawater may contribute to buoyancy in some species. We also propose a new hypothesis: gelatinous tissues, which are inexpensive to grow, may sometimes be a method to increase swimming efficiency by fairing the transition from trunk to tail. Such a layer is particularly prominent in hadal snailfishes (Liparidae); therefore, a robotic snailfish model was designed and constructed to analyse the influence of gelatinous tissues on locomotory performance. The model swam faster with a watery layer, representing gelatinous tissue, around the tail than without. Results suggest that the tissues may, in addition to providing buoyancy and low-cost growth, aid deep-sea fish locomotion. © 2017 The Authors

    Increasing Character Strength Knowledge, Interest, and Skill: Preliminary Evidence for a Collaborative and Multimethod Assessment Procedure

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    Introduction: The study’s objective was to evaluate whether a qualitative, collaborative, and multimethod assessment protocol increased reports of character strength interest, knowledge, and perceived skills. Methods: Thirty-two participants completed three phases of data collection. Participants were first screened for well-being, which was used as an auxiliary covariate to order participants into experimental conditions. Selected participants were randomly assigned to a control or collaborative and multimethod assessment (card sort × qualitative interview) condition. Participants completed pre- and post-measures of strength interest, knowledge, and perceived skill. In the final phase, second phase participants were invited to report on strength-related outcomes 24 h post-administration using an online survey. Results: A series of 2 (Assessment Condition) × 3 (Time) mixed ANOVAs were analyzed. Results revealed a significant assessment condition by time interaction for strength knowledge and perceived skill. Participants in the collaborative and multimethod assessment condition reported higher strength knowledge and perceived skills compared to control participants. These effects were maintained for 24 h. Conclusion: The findings offer preliminary yet sizable support for using collaborative and multimethod assessment procedures to increase strength knowledge and perceived skill. Because of the qualitative, collaborative, and individualized nature of our assessment protocol, the findings offer a low-cost and contextually bound pathway to increase strength-based outcomes

    Quantitative Nondestructive Density Determinations of Very Low-Density Carbon Foams

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    Carbon foams have been manufactured at EG&G Mound Applied Technologies through the use of a salt replica process [1,2] that has been modified by a Mound propriety process [3]. Applications of these foams have been described in an early publication [4]. In the basic process [1,2] of manufacturing the foams, salt is pressed into bars; the bars are then cured, infused with polymer and cured again. The salt is then removed by copious solvent rinsings and finally carbonized into very porous and light-weight, briquette-like material [2,5]. In this paper, the carbon density and the carbon distribution in various foams were determined either by bulk measurements of weight and volume or by x-ray computed tomography (CT)
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