4,092 research outputs found

    A historical perspective on the Federal Reserve's monetary aggregates

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    Data on the monetary aggregates are the fundamental raw material for research in many facets of economics and finance. Money demand modeling, measurement of money stock announcement effects, tests of the rationality of preliminary money stock forecasts and financial market efficiency, and comparison of alternative seasonal adjustment procedures are just a few such areas. Working in the spirit of Friedman and Schwartz, we chronicle the evolution of the Federal Reserve's monetary aggregates. Numerous changes in data sources, definitions, revision procedures, and seasonal adjustment methods suggest caution for all researchers using monetary aggregate time series data. A timeline compiled by Kenneth Kavajecz shows each redefinition, revision and special event that affected the monetary aggregates from 1960-1993.Monetary policy - United States ; Money supply

    Design, building, and testing of the postlanding systems for the assured crew return vehicle

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    The design, building, and testing of the postlanding support systems for a water-landing Assured Crew Return Vehicle (ACRV) are presented. One ACRV will be permanently docked to Space Station Freedom, fulfilling NASA's commitment to Assured Crew Return Capability in the event of an accident or illness. The configuration of the ACRV is based on an Apollo Command Module (ACM) derivative. The 1990-1991 effort concentrated on the design, building, and testing of a one-fifth scale model of the egress and stabilization systems. The objective was to determine the feasibility of (1) stabilizing the ACM out of the range of motions that cause seasickness and (2) the safe and rapid removal of a sick or injured crew member from the ACRV. The development of the ACRV postlanding systems model was performed at the University of Central Florida with guidance from the Kennedy Space Center ACRV program managers. Emphasis was placed on four major areas. First was design and construction of a one-fifth scale model of the ACM derivative to accommodate the egress and stabilization systems for testing. Second was the identification of a water test facility suitable for testing the model in all possible configurations. Third was the construction of the rapid egress mechanism designed in the previous academic year for incorporation into the ACRV model. The fourth area was construction and motion response testing of the attitude ring and underwater parachute systems

    A preliminary investigation into worry about mental health: Development of the mental health anxiety inventory

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    Background: Worry about physical health is broadly referred to as health anxiety and can range from mild concern to severe or persistent anxiety such as that found in DSM-IV hypochondriasis. While much is known about anxiety regarding physical health, little is known about anxiety regarding mental health. However, recent conceptualizations of health anxiety propose that individuals can experience severe and problematic worry about mental health in similar ways to how people experience extreme worry about physical health. Aims: Given the paucity of research in this area, the aim of the current study was to explore anxiety regarding mental health through validation of the Mental Health Anxiety Inventory (MHAI), a modified version of the Short Health Anxiety Inventory. Method: The MHAI, and measures of state anxiety (Depression, Anxiety and Stress Scales-21), trait worry (Penn State Worry Questionnaire), and health anxiety (Short Health Anxiety Inventory) were administered to 104 adult volunteers from the general community. Results: The MHAI demonstrated high internal consistency, acceptable test-retest reliability, and good construct validity when correlated with other measures of anxiety. Results also indicated that participants worried about their mental health and physical health equally, and that almost 9% of participants reported levels of mental health anxiety that were potentially problematic. Conclusion: Preliminary results suggest that a small proportion of adults in the community may experience high levels of mental health anxiety requiring treatment, and that the MHAI, if validated further, could be a useful tool for assessing this form of anxiet

    Modern Spectroscopy with a Spectrometer by the Optogalvanic Effect

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    An Experiment Involving the Optogalvanic Effect Suitable for the Advanced Physics Laboratory is Described. This Experiment Complements the Usual Basic Experiment in Atomic Spectroscopy Where Spectra Are Recorded on Photographic Film with a Spectrograph or with a Monochromator and Photomultiplier. the Optogalvanic Effect Used the Atoms Being Studied as the Detector and a Tunable Dye Laser as the Source. Linewidths Observed Are Those of the Dye Laser that Are Considerably Smaller Than Those Obtained with the Usual Laboratory Monochromator. the student is Introduced to the Techniques of Spectroscopy with Pulsed Dye Lasers and to a Spectrum for Which LS Coupling Does Not Hold. © 1981, American Association of Physics Teacher

    Evaluation of Four Intermediate Wheatgrass Populations under Grazing

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    The grazing season in the central and northern Great Plains could be extended by use of adapted cool-season grass pastures for spring and fall grazing to augment the native warm-season range. A grazing trial was conducted to evaluate the forage quality of four intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey] populations for use in forage-livestock systems. The cultivars Slate and Oahe and two populations selected for improved IVDMD, ‘Manska’ and NE TI 1, were evaluated. Each population was seeded in the fall of 1987 in three replicated 0.4-ha pastures arranged in a randomized complete block design. Pastures were stocked with three beef yearlings for 28 d in spring 1989 and 42 d in spring 1990 to provide a stocking rate of 7.5 steers ha-’. Duration of grazing was shorter in 1989 because of inadequate soil moisture. Average daily gain (ADG) and gain per hectare were higher (P 5 0.10) in 1989 than 1990, despite the lower (P 5 0.10) forage availability and lesser number of grazing days in 1989. Steers grazing Manska in 1989 gained 1.59 kg d-’, compared with 1.42,1.27, and 1.43 for Oahe, Slate, and NE TI 1, respectively. There were no differences (P \u3e 0.10) in ADG or gain per hectare among populations in 1990. The improvement in ADG resulted in 30 to 65 kg more gain per hectare from Manska compared with the other populations in l989. These results demonstrate the excellent quality of intermediate wheatgrass for grazing livestock and the impact that modest improvements in forage quality can have on animal performance

    Evaluation of Four Intermediate Wheatgrass Populations under Grazing

    Get PDF
    The grazing season in the central and northern Great Plains could be extended by use of adapted cool-season grass pastures for spring and fall grazing to augment the native warm-season range. A grazing trial was conducted to evaluate the forage quality of four intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey] populations for use in forage-livestock systems. The cultivars Slate and Oahe and two populations selected for improved IVDMD, ‘Manska’ and NE TI 1, were evaluated. Each population was seeded in the fall of 1987 in three replicated 0.4-ha pastures arranged in a randomized complete block design. Pastures were stocked with three beef yearlings for 28 d in spring 1989 and 42 d in spring 1990 to provide a stocking rate of 7.5 steers ha-’. Duration of grazing was shorter in 1989 because of inadequate soil moisture. Average daily gain (ADG) and gain per hectare were higher (P 5 0.10) in 1989 than 1990, despite the lower (P 5 0.10) forage availability and lesser number of grazing days in 1989. Steers grazing Manska in 1989 gained 1.59 kg d-’, compared with 1.42,1.27, and 1.43 for Oahe, Slate, and NE TI 1, respectively. There were no differences (P \u3e 0.10) in ADG or gain per hectare among populations in 1990. The improvement in ADG resulted in 30 to 65 kg more gain per hectare from Manska compared with the other populations in l989. These results demonstrate the excellent quality of intermediate wheatgrass for grazing livestock and the impact that modest improvements in forage quality can have on animal performance

    Size, shape and flow of powders for use in Selective Laser Sintering (SLS)

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    6th International Conference on Advanced Research in Virtual and Rapid Prototyping, Leiria, Portugal, 1-5 October 2013This paper investigates the effects of particles size and morphology on flowability of a range of polymeric powders (SLS and non-SLS grades). The effect of additives incorporation, as well as drying or sieving, on the flowability characteristics of the powders is also analyzed. The results show that the particle morphology has a stronger influence on the flowability than the particle size distribution. Moreover, the incorporation of additives has to be carefully considered in order to have positive effects on the powder flowability

    Wake structure and kinematics in two insectivorous bats

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    We compare kinematics and wake structure over a range of flight speeds (4.0–8.2 m s(−1)) for two bats that pursue insect prey aerially, Tadarida brasiliensis and Myotis velifer. Body mass and wingspan are similar in these species, but M. velifer has broader wings and lower wing loading. By using high-speed videography and particle image velocimetry of steady flight in a wind tunnel, we show that three-dimensional kinematics and wake structure are similar in the two species at the higher speeds studied, but differ at lower speeds. At lower speeds, the two species show significant differences in mean angle of attack, body–wingtip distance and sweep angle. The distinct body vortex seen at low speed in T. brasiliensis and other bats studied to date is considerably weaker or absent in M. velifer. We suggest that this could be influenced by morphology: (i) the narrower thorax in this species probably reduces the body-induced discontinuity in circulation between the two wings and (ii) the wing loading is lower, hence the lift coefficient required for weight support is lower. As a result, in M. velifer, there may be a decreased disruption in the lift generation between the body and the wing, and the strength of the characteristic root vortex is greatly diminished, both suggesting increased flight efficiency. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’

    Analysis of Histocial Distribution of SAV in the Eastern Shore Coastal Basins and Mid-Bay Island Complexes as Evidence of Historical Water Quality Conditions and a Restored Bay Ecosystem

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    Historical black and white format photographs at scales of approximately 1:20,000, dating from 1952 to 1956 were used to delineate the maximum coverage of SAV in the study region. Coverage of photography from decades before and after this period were found to generally to be of poorer quality and show less SAV presence. Photo-interpretation of the aerial photographs was accomplished using a head-up, on-screen digitizing system at fixed image scale of 1:12,000 and followed as closely as possible the methods currently used to delineate SAV beds throughout the Chesapeake Bay as well as the delineation of historical SAV coverage for other region. A total of 13,046 hectares of sub-tidal bottom in the Eastern Shore bay region between the tip of Fisherman’s Island to the Virginia-Maryland border, including the mid-bay island complex, were found to display SAV signatures. Of this historical total, approximately 10,451 ha, or 80%, were determined to be growing at depths shallower than 1 m MLW (Mean Low Water), 2,511 ha or 19% between 1 m and 2 m MLW, and 84 ha o
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