5,261 research outputs found

    Icing Characteristics and Anti-Icing Heat Requirements for Hollow and Ternally Modified Gas-Heated Inlet Guide Vanes

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    A two-dimensional inlet-guide-vane cascade was investigated to determine the effects of ice formations on the pressure losses across the guide vanes and to evaluate the heated gas flow and temperature required to prevent Icing at various conditions. A gas flow of approximately 0.4 percent of the inlet-air flow was necessary for anti-icing a hollow guide-vane stage at an inlet-gas temperature of 500 F under the following icing conditions: air velocity, 280 miles per hour; water content, 0.9 gram per cubic meter; and Inlet-air static temperature, 00 F. Also presented are the anti-icing gas flows required with modifications of the hollow Internal gas passage, which show heatinput savings greater than 50 percent

    Assessment of the environmental toxicity and carcinogenicity of tungsten-based shot.

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    The toxicity of elemental tungsten released from discharged shot was assessed against previous studies that established a 1% toxic threshold for soil organisms. Extremely heavy theoretical shot loadings of 69,000 shot/ha were used to generate estimated environmental concentrations (EEC) for two brands of tungsten-based shot containing 51% and 95% tungsten. The corresponding tungsten EEC values were 6.5–13.5 mg W/kg soil, far below the 1% toxic threshold. The same shot loading in water produced tungsten EEC values of 2.1–4.4 mg W/L, levels that are not toxic under experimental conditions. Pure tungsten has not been shown to exhibit carcinogenic properties when ingested or embedded in animal tissues, but nickel, with which it is often alloyed, has known carcinogenicity. Given the large number of waterfowl that carry shot embedded in their body, it is advisable to screen lead shot substitutes for their carcinogenic potential through intra-muscular implantation

    Event-related brain potential correlates of human auditory sensory memory-trace formation

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    The event-related potential (ERP) component mismatch negativity (MMN) is a neural marker of human echoic memory. MMN is elicited by deviant sounds embedded in a stream of frequent standards, reflecting the deviation from an inferred memory trace of the standard stimulus. The strength of this memory trace is thought to be proportional to the number of repetitions of the standard tone, visible as the progressive enhancement of MMN with number of repetitions (MMN memory-trace effect). However, no direct ERP correlates of the formation of echoic memory traces are currently known. This study set out to investigate changes in ERPs to different numbers of repetitions of standards, delivered in a roving-stimulus paradigm in which the frequency of the standard stimulus changed randomly between stimulus trains. Normal healthy volunteers (n = 40) were engaged in two experimental conditions: during passive listening and while actively discriminating changes in tone frequency. As predicted, MMN increased with increasing number of standards. However, this MMN memory-trace effect was caused mainly by enhancement with stimulus repetition of a slow positive wave from 50 to 250 ms poststimulus in the standard ERP, which is termed here "repetition positivity" (RP). This RP was recorded from frontocentral electrodes when participants were passively listening to or actively discriminating changes in tone frequency. RP may represent a human ERP correlate of rapid and stimulus-specific adaptation, a candidate neuronal mechanism underlying sensory memory formation in the auditory cortex

    Automated detection of asteroids in real-time with the Spacewatch telescope

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    The Spacewatch telescope on Kitt Peak is being used to survey for near-earth asteroids using a Tektronix TK2048 CCD in scanning mode. We hope to identify suitable low delta v candidates amongst the near-earth asteroid population as possible exploration targets, to identify those objects which pose a danger to life on earth, and to study the physical properties of the objects in near-earth space. Between Sep. 1990 and Jun. 1991, 14 new earth-approaching asteroids including 1 Aten, 9 Apollo, and 4 Amor type asteroids were detected by automated software and discriminated by their angular rates from the rest of the detected asteroids in near-real time by the observer. The average of about 1.5 earth-approaching asteroids per month is comparable to the total number found by all other observatories combined. One other Apollo type asteroid was detected by the observer as a long trailed image. The positions of this last object were measured and the object was tracked by the observer in real time. This object was determined to be a 5-10 meter diameter object which passed within 170,000 kilometers of earth. Of the 14 automatically detected earth-approaching asteroids, 10 have been found at distances in excess of 0.5 AU from earth. An average of more than 2000 asteroids are detected each month. Positions, angular rates, and brightnesses are determined for each of these asteroids in real-time

    Maximum likelihood and pseudo score approaches for parametric time-to-event analysis with informative entry times

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    We develop a maximum likelihood estimating approach for time-to-event Weibull regression models with outcome-dependent sampling, where sampling of subjects is dependent on the residual fraction of the time left to developing the event of interest. Additionally, we propose a two-stage approach which proceeds by iteratively estimating, through a pseudo score, the Weibull parameters of interest (i.e., the regression parameters) conditional on the inverse probability of sampling weights; and then re-estimating these weights (given the updated Weibull parameter estimates) through the profiled full likelihood. With these two new methods, both the estimated sampling mechanism parameters and the Weibull parameters are consistently estimated under correct specification of the conditional referral distribution. Standard errors for the regression parameters are obtained directly from inverting the observed information matrix in the full likelihood specification and by either calculating bootstrap or robust standard errors for the hybrid pseudo score/profiled likelihood approach. Loss of efficiency with the latter approach is considered. Robustness of the proposed methods to misspecification of the referral mechanism and the time-to-event distribution is also briefly examined. Further, we show how to extend our methods to the family of parametric time-to-event distributions characterized by the generalized gamma distribution. The motivation for these two approaches came from data on time to cirrhosis from hepatitis C viral infection in patients referred to the Edinburgh liver clinic. We analyze these data here.Comment: Published in at http://dx.doi.org/10.1214/14-AOAS725 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Trego County Real Estate Assessment Plan

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    This study of the Trego County Real Estate Assessment Plan was undertaken in order to bring its main elements together into a systematic form. The philosophy of the plan and its technical application are explained.https://scholars.fhsu.edu/fort_hays_studies_series/1014/thumbnail.jp

    Employees\u27 Share of National Income, 1929 - 1941

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    Data in this paper indicate that employees are receiving an increasing share of the national income. This means that that employers, enterprisers, and property owners as a group have experienced a relative, although not absolute, decrease in their share in the national income.https://scholars.fhsu.edu/fort_hays_studies_series/1012/thumbnail.jp

    A critical examination of Paul Tillich’s doctrine of the Holy Spirit

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    This thesis expounds and analyses Paul Tillich’s doctrine of the Spirit as set out in the third volume of his Systematic Theology and other relevant passages from his writings. After a brief introduction to his theological method , his understanding of God and the symbolic nature of our knowledge of the divine is examined, specific reference being made to the meaning of 'Spirit’ and the Trinitarian symbols. A chapter on the nature of life and its ambiguities in the spheres of morality, culture and religion, with which the doctrine of the Spirit is correlated in Tillich's thought, prepares the way for a more detailed analysis of this doctrine. This analysis deals first with Tillich's understanding of the divine Spirit in relation to the spirit of man, the Spirit's manifestation in the world, and the marks of the Spiritual Presence in historical mankind, culminating in the Christ and the creation of the Spiritual Community. The importance of the Spirit's work in resolving life's ambiguities by means of an unambiguous life of transcendent unity is indicated. The succeeding chapters expand this discussion and deal with the Spirit's impact in the realm of religion, the life of the church and the individual within the church; in the realms of culture and morality, the wider life of society; and finally, in the total context of man's life in the work of healing. A concluding chapter points out the implications of the concept of the transcendent unity of unambiguous life, suggesting that Tillich's understanding of the Spirit significantly deviates from orthodox Christian pneumatology, but also emphasising that in the final analysis Tillich has made a significant contribution to contemporary theological study of the Spirit

    Coherent coupling between surface plasmons and excitons in semiconductor nanocrystals

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    We present an experimental demonstration of strong coupling between a surface plasmon propagating on a planar silver substrate, and the lowest excited state of CdSe nanocrystals. Variable-angle spectroscopic ellipsometry measurements demonstrated the formation of plasmon-exciton mixed states, characterized by a Rabi splitting of ∼\sim 82 meV at room temperature. Such a coherent interaction has the potential for the development of plasmonic non-linear devices, and furthermore, this system is akin to those studied in cavity quantum electrodynamics, thus offering the possibility to study the regime of strong light-matter coupling in semiconductor nanocrystals at easily accessible experimental conditions.Comment: 12 pages, 4 figure
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