162 research outputs found

    Enriching the Academic Experience: The Library and Experiential Learning

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    This article will describe how academic libraries can (and should) be involved in experiential learning. The authors detail the impact experiential learning can have on the relevance of academic libraries to their universities. They discuss the benefits to libraries as well as students. In particular, the authors describe experiential learning at the James E. Walker Library and the partnerships formed, projects completed, lessons learned, and the benefits realized

    A Survey of Morcellator Preference and Cost Comparison of the Lumenis VersaCut and Wolf Piranha Morcellators

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    Objective To evaluate operating room (OR) costs associated with the 2 available morcellators in the United States in a matched cohort and to determine benign prostatic hyperplasia surgeon's morcellator preference. Materials and Methods Patients from 2013, the last year our institution exclusively used the VersaCut device, were matched 1:1 with the most recent patient cohort, utilizing the Wolf Piranha morcellator. Cost of morcellation including the expense of OR time and disposable instrument costs were calculated. A survey to the Endourological Society e-mail listserv was sent to determine morcellator preference. Results We identified 142 patients who underwent holmium laser enucleation of the prostate in 2013. When compared with the VersaCut group, morcellation efficiency (4.4 vs 7.0 g/min, P <.01) and expense of OR time (1420.80vs1420.80 vs 992.21, P <.005) both favored the Piranha morcellator system even when the costs of disposable instruments were factored into the analysis (1338.81vs1338.81 vs 1637.50, P <.05). A total of 126 urologists responded to the survey. Of these, 56 (44.5%) perform transurethral prostate enucleations, which included 48 (86%) holmium. More endourologists use the VersaCut (n = 33, 59%) than the Piranha (n = 24, 43%) morcellator. Qualities that impacted the preference of morcellator included the preferred device is safer, faster, easier to use, reusable, and less expensive. Conclusion We identified a significant improved efficiency and improved cost savings utilizing the Piranha morcellator even when controlling for disposable costs. Of the endourologists who responded to the survey, less than half perform transurethral enucleation. Morcellator preference is largely based on safety, efficiency, and ease of use, whereas cost and reusablility were of lesser importance

    Stone free outcomes of flexible ureteroscopy for renal calculi utilizing CT imaging

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    Objectives To assess stone free rates following URS for renal calculi at our institution using low dose renal only CT (LDCT). Methods A retrospective review of patients undergoing flexible URS for renal stones only with subsequent CT scan within 3 months. Meticulous basketing of all stone fragments was performed whenever possible. A “true” zero fragment SFR was determined by reviewing the CT scan and radiologist's report. Patients with nephrocalcinosis (as determined by visual inspection of papilla at the time of URS) were assigned the “stone free” category. Results Flexible URS was performed in 288 renal units of 214 patients with renal calculi from 2013 to 2016. Median pre-operative stone size was 6.2mm with the average kidney containing 6.4 stones. An access sheath was used in 92% of cases. A total of 73% (209/288) renal units were completely stone free by CT assessment. Patients with residual fragments were as follows: 1mm in 2% (7/288), 2-4 mm in 16% (46/288), and >4 mm in 9% of kidneys (26/288). Conclusions The true stone free rate in patients undergoing flexible URS for renal calculi utilizing active basketing of fragments as determined by strict CT assessment was 73%. In patients with residual fragments, the majority are 2-4 mm in size making URS a treatment option for renal calculi with excellent stone free results

    Principal Component Analysis of SDSS Stellar Spectra

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    We apply Principal Component Analysis (PCA) to ~100,000 stellar spectra obtained by the Sloan Digital Sky Survey (SDSS). In order to avoid strong non-linear variation of spectra with effective temperature, the sample is binned into 0.02 mag wide intervals of the g-r color (-0.20<g-r<0.90, roughly corresponding to MK spectral types A3 to K3), and PCA is applied independently for each bin. In each color bin, the first four eigenspectra are sufficient to describe the observed spectra within the measurement noise. We discuss correlations of eigencoefficients with metallicity and gravity estimated by the Sloan Extension for Galactic Understanding and Exploration (SEGUE) Stellar Parameters Pipeline. The resulting high signal-to-noise mean spectra and the other three eigenspectra are made publicly available. These data can be used to generate high quality spectra for an arbitrary combination of effective temperature, metallicity, and gravity within the parameter space probed by the SDSS. The SDSS stellar spectroscopic database and the PCA results presented here offer a convenient method to classify new spectra, to search for unusual spectra, to train various spectral classification methods, and to synthesize accurate colors in arbitrary optical bandpasses.Comment: 25 pages, 15 figures, accepted by the Astronomical Journa

    The Importance of Nebular Continuum and Line Emission in Observations of Young Massive Star Clusters

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    In this spectroscopic study of infant massive star clusters, we find that continuum emission from ionized gas rivals the stellar luminosity at optical wavelengths. In addition, we find that nebular line emission is significant in many commonly used broad-band HST filters including the F814W I-band, the F555W V-band and the F435W B-band. Two young massive clusters (YMCs) in NGC 4449 were targeted for spectroscopic observations after Reines et al. (2008a) discovered an F814W I-band excess in their photometric study of radio-detected clusters in the galaxy. The spectra were obtained with the Dual Imaging Spectrograph on the 3.5 m APO telescope. We supplement these data with HST and SDSS photometry. By comparing our data to the Starburst99 and GALEV models, we find that nebular continuum emission competes with the stellar light in our observations and that the relative contribution is largest in the U- and I-bands, where the Balmer and Paschen jumps are located. The spectra also exhibit strong line emission including the [SIII] 9069,9532 lines in the HST F814W I-band. We find that the combination of nebular continuum and line emission can account for the F814W I-band excess found by Reines et al. (2008a). In an effort to provide a benchmark for estimating the impact of ionized gas emission on photometric observations of YMCs, we compute the relative contributions of the stellar continuum, nebular continuum, and emission lines to the total flux of a 3 Myr-old cluster through various HST filter/instrument combinations, including filters in the WFC3. We urge caution when comparing observations of YMCs to evolutionary synthesis models since nebular emission can have a large impact on magnitudes and colors of young (< 5 Myr) clusters, significantly affecting inferred properties such as ages, masses and extinctions. (Abridged)Comment: 13 pages, 11 figures, Accepted for Publication in Ap

    Ovariectomy results in differential shifts in gut microbiota in low versus high aerobic capacity rats

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    The increased risk for cardiometabolic disease with the onset of menopause is widely studied and likely precipitated by the decline in endogenous estradiol (E2), yet the precise mechanisms are unknown. The gut microbiome is involved in estrogen metabolism and has been linked to metabolic disease, suggesting its potential involvement in the postmenopausal phenotype. Furthermore, menopause‐associated risk factors, as well as gut ecology, are altered with exercise. Therefore, we studied microbial changes in an ovariectomized (OVX vs. Sham) rat model of high (HCR) and low (LCR) intrinsic aerobic capacity (n = 8–10/group) in relation to changes in body weight/composition, glucose tolerance, and liver triglycerides (TG). Nine weeks after OVX, HCR rats were moderately protected against regional adipose tissue gain and liver TG accumulation (P < 0.05 for both). Microbial diversity and number of the Bacteroidetes phylum were significantly increased in LCR with OVX, but unchanged in HCR OVX relative to Sham. Plasma short‐chain fatty acids (SCFA), produced by bacteria in the gut and recognized as metabolic signaling molecules, were significantly greater in HCR Sham relative to LCR Sham rats (P = 0.05) and were decreased with OVX in both groups. These results suggest that increased aerobic capacity may be protective against menopause‐associated cardiometabolic risk and that gut ecology, and production of signaling molecules such as SCFA, may contribute to the mediation.We have demonstrated modest protection from the metabolic effects of surgical menopause (ovariectomy, OVX) in rats with increased aerobic capacity (high running capacity, HCR) relative to those with low aerobic capacity (low running capacity, LCR). These results are associated with significant differences in gut microbiota and their products (short chain fatty acids) between the two groups.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113123/1/phy212488.pd

    Surveying the Dynamic Radio Sky with the Long Wavelength Demonstrator Array

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    This paper presents a search for radio transients at a frequency of 73.8 MHz (4 m wavelength) using the all-sky imaging capabilities of the Long Wavelength Demonstrator Array (LWDA). The LWDA was a 16-dipole phased array telescope, located on the site of the Very Large Array in New Mexico. The field of view of the individual dipoles was essentially the entire sky, and the number of dipoles was sufficiently small that a simple software correlator could be used to make all-sky images. From 2006 October to 2007 February, we conducted an all-sky transient search program, acquiring a total of 106 hr of data; the time sampling varied, being 5 minutes at the start of the program and improving to 2 minutes by the end of the program. We were able to detect solar flares, and in a special-purpose mode, radio reflections from ionized meteor trails during the 2006 Leonid meteor shower. We detected no transients originating outside of the solar system above a flux density limit of 500 Jy, equivalent to a limit of no more than about 10^{-2} events/yr/deg^2, having a pulse energy density >~ 1.5 x 10^{-20} J/m^2/Hz at 73.8 MHz for pulse widths of about 300 s. This event rate is comparable to that determined from previous all-sky transient searches, but at a lower frequency than most previous all-sky searches. We believe that the LWDA illustrates how an all-sky imaging mode could be a useful operational model for low-frequency instruments such as the Low Frequency Array, the Long Wavelength Array station, the low-frequency component of the Square Kilometre Array, and potentially the Lunar Radio Array.Comment: 20 pages; accepted for publication in A

    Ultracool Field Brown Dwarf Candidates Selected at 4.5 microns

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    We have identified a sample of cool field brown dwarf candidates using IRAC data from the Spitzer Deep, Wide-Field Survey (SDWFS). The candidates were selected from 400,000 SDWFS sources with [4.5] <= 18.5 mag and required to have [3.6]-[4.5] >= 1.5 and [4.5] - [8.0] <= 2.0 on the Vega system. The first color requirement selects objects redder than all but a handful of presently known brown dwarfs with spectral classes later than T7, while the second eliminates 14 probable reddened AGN. Optical detection of 4 of the remaining 18 sources implies they are likely also AGN, leaving 14 brown dwarf candidates. For two of the brightest candidates (SDWFS J143524.44+335334.6 and SDWFS J143222.82+323746.5), the spectral energy distributions including near-infrared detections suggest a spectral class of ~ T8. The proper motion is < 0.25 "/yr, consistent with expectations for a luminosity inferred distance of >70 pc. The reddest brown dwarf candidate (SDWFS J143356.62+351849.2) has [3.6] - [4.5]=2.24 and H - [4.5] > 5.7, redder than any published brown dwarf in these colors, and may be the first example of the elusive Y-dwarf spectral class. Models from Burrows et al. (2003) predict larger numbers of cool brown dwarfs should be found for a Chabrier (2003) mass function. Suppressing the model [4.5] flux by a factor of two, as indicated by previous work, brings the Burrows models and observations into reasonable agreement. The recently launched Wide-field Infrared Survey Explorer (WISE) will probe a volume ~40x larger and should find hundreds of brown dwarfs cooler than T7.Comment: 13 pages, 6 figures, accepted for publication in the June 2010 issue of The Astronomical Journa
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