749 research outputs found

    A Study of Factors Influential In The Mobility of Superintendents of Fifty-Eight Common School Districts, State of Kansas, 1953

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    The specific problem of this study is to isolate, if possible, the factors responsible for the mobility of superintendents. The over-all objective is to discover why the mean tenure of superintendents is short and the extent to which various factors weigh up on the situation

    Evaluation and study of advanced optical contamination, deposition, measurement, and removal techniques

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    A program is described to design, fabricate and install an experimental work chamber assembly (WCA) to provide a wide range of experimental capability. The WCA incorporates several techniques for studying the kinetics of contaminant films and their effect on optical surfaces. It incorporates the capability for depositing both optical and contaminant films on temperature-controlled samples, and for in-situ measurements of the vacuum ultraviolet reflectance. Ellipsometer optics are mounted on the chamber for film thickness determinations, and other features include access ports for radiation sources and instrumentation. Several supporting studies were conducted to define specific chamber requirements, to determine the sensitivity of the measurement techniques to be incorporated in the chamber, and to establish procedures for handling samples prior to their installation in the chamber. A bibliography and literature survey of contamination-related articles is included

    Integration of a Fire Detector into a Spacecraft

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    A detector sensitive to only the ultraviolet radiation emitted by flames has been selected as the basic element of the NASA Skylab fire detection system. It is sensitive to approximately 10(exp -12)W of radiation and will detect small flames at distances in excess of 3m. The performance of the detector was verified by experiments in an aircraft flying zero-gravity parabolas to simulate the characteristics of a fire which the detector must sense. Extensive investigation and exacting design was necessary to exclude all possible sources of false alarms. Optical measurements were made on all the spacecraft windows to determine the amount of solar radiation transmitted. The lighting systems and the onboard experiments also were appraised for ultraviolet emissions. Proton-accelerator tests were performed to determine the interaction of the Earth's trapped radiation belts with the detectors and the design of the instrument was modified to negate these effects

    Rural learners’ patterns of engagement in synchronous online mentoring group chats to advance conceptions of career development

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    Learners in the rural settings are deprived of necessary support mechanism (mentorship, motivation and guidance) for career consciousness and lack sufficient exposure to diverse careers. This study reports on an online-based mentoring programme designed to expose learners to multiple mentors from distinct career fields, institutions and occupations. The online mentoring program was conducted through regular WhatsApp group chats in which mentors (identified as guests) engaged with learners in sharing their social and personal backgrounds, career history and advancement. A group of 35 learners participated in the intervention and data comprised of activity logs of conversations. These were analysed using the Exchange Structure Analysis (ESA) model, and codes were generated pertaining to instances of orientation. The emergent interactional patterns suggest that in greater open and informative conversations, learners benefit from online mentors who assume roles of mediators between unique careers and the real-world situation. These interactional patterns further suggest that synchronous conversations with rural learners need to comprise of more teaching exchanges and less boundary exchanges to allow informal and spontaneous flourishing of conversations. Recommendations for good practice are emphasized for educators striving to narrow the knowledge gap between the learners in disadvantaged and advantaged settings through digital media.Institute for Science and Technology Education (ISTE

    Flame detector operable in presence of proton radiation

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    A detector of ultraviolet radiation for operation in a space vehicle which orbits through high intensity radiation areas is described. Two identical ultraviolet sensor tubes are mounted within a shield which limits to acceptable levels the amount of proton radiation reaching the sensor tubes. The shield has an opening which permits ultraviolet radiation to reach one of the sensing tubes. The shield keeps ultraviolet radiation from reaching the other sensor tube, designated the reference tube. The circuitry of the detector subtracts the output of the reference tube from the output of the sensing tube, and any portion of the output of the sensing tube which is due to proton radiation is offset by the output of the reference tube. A delay circuit in the detector prevents false alarms by keeping statistical variations in the proton radiation sensed by the two sensor tubes from developing an output signal

    The impact of cyberstalking: the lived experience - a thematic analysis.

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    Cyberstalking (CS) can have major psychosocial impacts on individuals. Victims report a number of serious consequences of victimization such as increased suicidal ideation, fear, anger, depression, and post traumatic stress disorder (PTSD) symptomology. Research is largely limited to quantitative outcome research. This study examines the diversity of experiences reported by people who define themselves as having been cyberstalked. Thematic analysis was used to explore 100 CS victim narratives, gathered by means of an online survey questionnaire designed to capture structured text responses. Five emergent themes were evident in the data: control and intimidation; determined offender; development of harassment; negative consequences; and lack of support. Findings identify similarities and differences to traditional stalking, along with the necessity of support for victims and illustration of the negative impacts this form of harassment produces

    Polymer electrolytes based on modified natural rubber

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    Modified natural rubber polymer hosts having low transition glass temperatures have been investigated for use in polymer electrolytes. Two types of modified natural rubber, namely 25% epoxidised natural rubber (ENR-25) and 50% epoxidised natural rubber (ENR-50) were employed in conjunction with poly(ethylene oxide), PEO. Results are reported for ionic conductivity and thermal properties for both unplasticized and plasticized polymer electrolyte systems with lithium triflate. The samples were in the form of free standing films with the thickness 0.2–0.5 mm and mixtures of ethylene carbonate (EC) and propylene carbonate (PC) were used as plasticizers. Unplasticized modified natural rubber-based systems exhibit ionic conductivities in the range 10−6 to 10−5 S cm−1 at ambient temperatures. Incorporating 100% of EC/PC by weight fraction of polymer (ENR/PEO) to the systems yielded mechanically stable films and ionic conductivities in the range of 10−4 S cm−1 at ambient temperature

    The Distance to Nova V959 Mon from VLA Imaging

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    Determining reliable distances to classical novae is a challenging but crucial step in deriving their ejected masses and explosion energetics. Here we combine radio expansion measurements from the Karl G. Jansky Very Large Array with velocities derived from optical spectra to estimate an expansion parallax for nova V959 Mon, the first nova discovered through its gamma-ray emission. We spatially resolve the nova at frequencies of 4.5-36.5 GHz in nine different imaging epochs. The first five epochs cover the expansion of the ejecta from 2012 October to 2013 January, while the final four epochs span 2014 February to 2014 May. These observations correspond to days 126 through 199 and days 615 through 703 after the first detection of the nova. The images clearly show a non-spherical ejecta geometry. Utilizing ejecta velocities derived from 3D modelling of optical spectroscopy, the radio expansion implies a distance between 0.9 +/- 0.2 and 2.2 +/- 0.4 kpc, with a most probable distance of 1.4 +/- 0.4 kpc. This distance implies a gamma-ray luminosity much less than the prototype gamma-ray-detected nova, V407 Cyg, possibly due to the lack of a red giant companion in the V959 Mon system. V959 Mon also has a much lower gamma-ray luminosity than other classical novae detected in gamma-rays to date, indicating a range of at least a factor of 10 in the gamma-ray luminosities for these explosions.Comment: 11 pages, 8 figures, 3 tables, submitted to ApJ 2015-01-21, under revie

    The Peculiar Multi-Wavelength Evolution Of V1535 Sco

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    We present multi-wavelength observations of the unusual nova V1535 Sco throughout its outburst in 2015. Early radio observations were consistent with synchrotron emission, and early X-ray observations revealed the presence of high-energy (>1 keV) photons. These indicated that strong shocks were present during the first ~2 weeks of the nova's evolution. The radio spectral energy distribution was consistent with thermal emission from week 2 to week 6. Starting in week 7, the radio emission again showed evidence of synchrotron emission and there was an increase in X-ray emission, indicating a second shock event. The optical spectra show evidence for at least two separate outflows, with the faster outflow possibly having a bipolar morphology. The optical and near infrared light curves and the X-ray measurements of the hydrogen column density indicated that the companion star is likely a K giant.Comment: 20 pages, 13 figures, under review at ApJ, updated to match the most recent version submitted to the refere

    Multisensory attention training for treatment of tinnitus

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    Spiegel, D. P. et al. Multisensory attention training for treatment of tinnitus. Sci. Rep. 5, 10802; doi: 10.1038/srep10802 (2015).Tinnitus is the conscious perception of sound with no physical sound source. Some models of tinnitus pathophysiology suggest that networks associated with attention, memory, distress and multisensory experience are involved in tinnitus perception. The aim of this study was to evaluate whether a multisensory attention training paradigm which used audio, visual, and somatosensory stimulation would reduce tinnitus. Eighteen participants with predominantly unilateral chronic tinnitus were randomized between two groups receiving 20 daily sessions of either integration (attempting to reduce salience to tinnitus by binding with multisensory stimuli) or attention diversion (multisensory stimuli opposite side to tinnitus) training. The training resulted in small but statistically significant reductions in Tinnitus Functional Index and Tinnitus Severity Numeric Scale scores and improved attentional abilities. No statistically significant improvements in tinnitus were found between the training groups. This study demonstrated that a short period of multisensory attention training reduced unilateral tinnitus, but directing attention toward or away from the tinnitus side did not differentiate this effect.This work was supported by a grant from Links Research and Grants Corporation to G.D.S
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