130 research outputs found

    On the Nature of the Strong Emission-Line Galaxies in Cluster Cl 0024+1654: Are Some the Progenitors of Low Mass Spheroidals?

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    We present new size, line ratio, and velocity width measurements for six strong emission-line galaxies in the galaxy cluster, Cl 0024+1654, at redshift z~0.4. The velocity widths from Keck spectra are all narrow (30<sigma<120 km/s), with three profiles showing double peaks. Four galaxies have low masses (M<10^{10} Mo). Whereas three galaxies were previously reported to be possible AGNs, none exhibit AGN-like emission line ratios or velocity widths. Two or three appear as very blue spirals with the remainder more akin to luminous H-II galaxies undergoing a strong burst of star formation. We propose that after the burst subsides, these galaxies will transform into quiescent dwarfs, and are thus progenitors of some cluster spheroidals (We adopt the nomenclature suggested by Kormendy & Bender (1994), i.e., low-density, dwarf ellipsoidal galaxies like NGC 205 are called `spheroidals' instead of `dwarf ellipticals') seen today.Comment: 14 pages + 2 figures + 1 table, LaTeX, Acc. for publ. in ApJL also available at http://www.ucolick.org/~deep/papers/papers.htm

    HST Observations of the Distant Cluster 0016+16: Quantitative Morphology of Confirmed Cluster Members

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    We present HST images of 24 confirmed members of the distant galaxy cluster Cl0016+16 at redshift 0.55. The Balmer-strong (``E+A'') and emission- line galaxies frequently show unusual visual morphology, implying that galaxian interactions produce ``active'' galaxies in moderate-redshift clusters. We use the image concentration index as a quantitative measure of morphology to show that these unusual galaxies appear disklike, while the normal red galaxies resemble E/S0s. Although consistent with HST observations by Dressler et al. in Cl0939+4713 (z=0.41z=0.41), our results differ from the Couch et al. finding that most Balmer-strong galaxies in AC114 (z=0.31z=0.31) resemble ellipticals. The entire ``E+A'' sample is small, but if future studies confirm their diversity, it will suggest that they have different origins.Comment: 11 pages, uuencoded compressed PostScript, accepted to ApJ Letters, LICK-3

    The Slitmask Alignment Tool: robust, efficient, and astronomer-friendly software for aligning multi-object slitmasks

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    Multi-object spectroscopy via custom slitmasks is a key capability on three instruments at the W. M. Keck Observatory. Before observers can acquire spectra they must complete a complex procedure to align each slit with its corresponding science target. We developed the Slitmask Alignment Tool (SAT), to replace a complex, inefficient, and error-prone slitmask alignment process that often resulted in lost sky time for novice and experienced observers alike. The SAT accomplishes rapid initial mask alignment, prevents field misidentification, accurately predicts alignment box image locations, corrects for flexure-induced image displacement, verifies the instrument and exposure configuration, and accommodates both rectangular and trapezoidal alignment box shapes. The SAT is designed to lead observers through the alignment process and coordinate image acquisition with instrument and telescope moves to improve efficiencies. By simplifying the process to just a few mouse clicks, the SAT enables even novice observers to achieve robust, efficient, and accurate alignment of slitmasks on all three Keck instruments supporting multislit spectroscopy, saving substantial observing time

    Association of Markers of Inflammation with Sleep and Physical Activity among People Living with HIV or AIDS

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    This study examined associations of sleep and minutes spent in moderate-vigorous physical activity (MVPA) with C-reactive protein (CRP) and interleukin (IL)-6 among persons living with HIV (PLWH). Cross-sectional analyses (n=45) focused on associations of inflammatory outcomes (i.e., CRP and IL-6) with actigraph-derived sleep duration, latency, and efficiency; bedtime; wake time; and wake-after-sleep-onset; as well as MVPA. Least square means for CRP and IL-6 by levels of sleep and MVPA were computed from general linear models. Individuals below the median of sleep duration, above the median for bedtime, and below the median of MVPA minutes had higher CRP or IL-6 levels. Generally, individuals with both low MVPA and poor sleep characteristics had higher inflammation levels than those with more MVPA and better sleep. Understanding the combined impact of multiple lifestyle/behavioral factors on inflammation could inform intervention strategies to reduce inflammation and therefore, chronic disease risk

    The Association of Physical Activity during Weekdays and Weekend with Body Composition in Young Adults

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    Physical activity (PA) is a key contributor in long-term weight management but there remains limited research on the association between weekly PA patterns and weight change. The purpose of the present study was to examine the prospective association between weekly PA patterns and weight change in generally healthy young adults. Anthropometric measurements, including dual X-ray absorptiometry, were obtained every 3 months over a period of one year in 338 adults (53% male). At each measurement time, participants wore a multisensor device for a minimum of 10 days to determine total daily energy expenditure and time spent sleeping, sedentary, in light PA (LPA), in moderate PA (MPA), and in vigorous PA (VPA). PA did not differ between weekdays and the weekend at baseline. Twenty-four-hour sleep time, however, was significantly longer during weekends compared to weekdays, which was associated with less time spent sedentary. Weight loss was associated with a significant increase in LPA at the expense of sedentary time during the weekend but not during weekdays. Regression analyses further revealed an inverse association between change in VPA during the weekend and body composition at 12-month follow-up. Taken together, these results suggest that weekend PA plays an important role in long-term weight management

    The Association of Physical Activity during Weekdays and Weekend with Body Composition in Young Adults

    Get PDF
    Physical activity (PA) is a key contributor in long-term weight management but there remains limited research on the association between weekly PA patterns and weight change. The purpose of the present study was to examine the prospective association between weekly PA patterns and weight change in generally healthy young adults. Anthropometric measurements, including dual X-ray absorptiometry, were obtained every 3 months over a period of one year in 338 adults (53% male). At each measurement time, participants wore a multisensor device for a minimum of 10 days to determine total daily energy expenditure and time spent sleeping, sedentary, in light PA (LPA), in moderate PA (MPA), and in vigorous PA (VPA). PA did not differ between weekdays and the weekend at baseline. Twenty-four-hour sleep time, however, was significantly longer during weekends compared to weekdays, which was associated with less time spent sedentary. Weight loss was associated with a significant increase in LPA at the expense of sedentary time during the weekend but not during weekdays. Regression analyses further revealed an inverse association between change in VPA during the weekend and body composition at 12-month follow-up. Taken together, these results suggest that weekend PA plays an important role in long-term weight management

    The Slitmask Alignment Tool: robust, efficient, and astronomer-friendly software for aligning multi-object slitmasks

    Get PDF
    Multi-object spectroscopy via custom slitmasks is a key capability on three instruments at the W. M. Keck Observatory. Before observers can acquire spectra they must complete a complex procedure to align each slit with its corresponding science target. We developed the Slitmask Alignment Tool (SAT), to replace a complex, inefficient, and error-prone slitmask alignment process that often resulted in lost sky time for novice and experienced observers alike. The SAT accomplishes rapid initial mask alignment, prevents field misidentification, accurately predicts alignment box image locations, corrects for flexure-induced image displacement, verifies the instrument and exposure configuration, and accommodates both rectangular and trapezoidal alignment box shapes. The SAT is designed to lead observers through the alignment process and coordinate image acquisition with instrument and telescope moves to improve efficiencies. By simplifying the process to just a few mouse clicks, the SAT enables even novice observers to achieve robust, efficient, and accurate alignment of slitmasks on all three Keck instruments supporting multislit spectroscopy, saving substantial observing time
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