4,645 research outputs found

    A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

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    A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location

    The effects of isometric work on heart rate, blood pressure, and net oxygen cost

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    Isometric exercise effects on heart rate, blood pressure, and net oxygen cos

    Far-UV Emission from Elliptical Galaxies at z=0.55

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    The restframe UV-to-optical flux ratio, characterizing the ``UV upturn'' phenomenon, is potentially the most sensitive tracer of age in elliptical galaxies; models predict that it may change by orders of magnitude over the course of a few Gyr. In order to trace the evolution of the UV upturn as a function of redshift, we have used the far-UV camera on the Space Telescope Imaging Spectrograph to image the galaxy cluster CL0016+16 at z=0.55. Our 25''x25'' field includes four bright elliptical galaxies, spectroscopically confirmed to be passively evolving cluster members. The weak UV emission from the galaxies in our image demonstrates that the UV upturn is weaker at a lookback time 5.6 Gyr earlier than our own, as compared to measurements of the UV upturn in cluster E and S0 galaxies at z=0 and z=0.375. These images are the first with sufficient depth to demonstrate the fading of the UV upturn expected at moderate redshifts. We discuss these observations and the implications for the formation history of galaxies.Comment: 4 pages, Latex. 2 figures. Uses corrected version of emulateapj.sty and apjfonts.sty (included). Accepted for publication in ApJ Letter

    1 May 1913 property agreement

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    Agreement between G. M. D. Bowers, W. W. Colson, and B. R. Colson to hold Dixieland Park land for Theophilus Brown Larimore. The one-page typewritten document is dated 1 May 1913

    Defining Quality in Undergraduate Education

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    Objectives: This research brief explores the literature addressing quality in undergraduate education to identify what previous research has said about quality and to offer future directions for research on quality in undergraduate education. Method: We conducted a scoping review to provide a broad overview of existing research. Using targeted search terms in academic databases, we identified and reviewed relevant academic literature to develop emergent themes and implications for future research. Results: The exploratory review of the literature revealed a range of thoughtful discussions and empirical studies attempting to define quality in undergraduate education. Many publications highlighted the importance of including different stakeholder perspectives and presented some of the varying perceptions of quality among different stakeholders. Conclusions: While a number of researchers have explored and written about how to define quality in undergraduate education, there is not a general consensus regarding a definition of quality in undergraduate education. Past research offers a range of insights, models, and data to inform future research. Implication for Theory and/or Practice: We provide four recommendations for future research to contribute to a high quality undergraduate educational experience. We suggest more comprehensive systematic reviews of the literature as a next step

    [Unsigned agreement to hold land unchanged for Larimore]

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    Unsigned agreement on Our Florida Friend letterhead where G. M. D. Bowers, W. W. Colson, and B. R. Colson agree to hold land for Theophilus Brown Larimore unchanged. The agreement is one-page typewritten and dated 1 May 1913

    Far-Ultraviolet Emission from Elliptical Galaxies at z=0.33

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    We present far-ultraviolet (far-UV) images of the rich galaxy cluster ZwCl1358.1+6245, taken with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope (HST). When combined with archival HST observations, our data provide a measurement of the UV-to-optical flux ratio in 8 early-type galaxies at z=0.33. Because the UV flux originates in a population of evolved, hot, horizontal branch (HB) stars, this ratio is potentially one of the most sensitive tracers of age in old populations -- it is expected to fade rapidly with lookback time. We find that the UV emission in these galaxies, at a lookback time of 3.9 Gyr, is significantly weaker than it is in the current epoch, yet similar to that in galaxies at a lookback time of 5.6 Gyr. Taken at face value, these measurements imply different formation epochs for the massive ellipticals in these clusters, but an alternative explanation is a "floor" in the UV emission due to a dispersion in the parameters that govern HB morphology.Comment: 4 pages, Latex. 2 figures. Uses corrected version of emulateapj.sty and apjfonts.sty (included). Accepted for publication in ApJ Letter

    Discovery of Enhanced Germanium Abundances in Planetary Nebulae with FUSE

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    We report the discovery of Ge III λ\lambda1088.46 in the planetary nebulae (PNe) SwSt 1, BD+30o^{\rm o}3639, NGC 3132, and IC 4593, observed with the Far Ultraviolet Spectroscopic Explorer. This is the first astronomical detection of this line and the first measurement of Ge (Z = 32) in PNe. We estimate Ge abundances using S and Fe as reference elements, for a range of assumptions about gas-phase depletions. The results indicate that Ge, which is synthesized in the initial steps of the s-process and therefore can be self-enriched in PNe, is enhanced by factors of > 3-10. The strongest evidence for enrichment is seen for PNe with Wolf-Rayet central stars, which are likely to contain heavily processed material.Comment: 11 pages, 1 figure, accepted for publication in ApJ Letter

    ROObockey: Remote Controlled, Aim-Assisted Street Hockey Robot

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    The goal of the ROObockey project is to design and construct a floor hockey robot that can competitively shoot a puck. The robot design quickly locates a specific beacon through the use of image processing and uses a pneumatic shooting mechanism to send a puck to a specified target. The beacons act as possible player or goal positions in a hockey game. The robot also utilizes a wireless controller device to allow a user to maneuver the robot across a hockey field

    The Lemaitre-Schwarzschild Problem Revisited

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    The Lemaitre and Schwarzschild analytical solutions for a relativistic spherical body of constant density are linked together through the use of the Weyl quadratic invariant. The critical radius for gravitational collapse of an incompressible fluid is shown to vary continuously from 9/8 of the Schwarzschild radius to the Schwarzschild radius itself while the internal pressures become locally anisotropic.Comment: Final version as accepted by GR&G (to appear in vol. 34, september 2002
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