1,441 research outputs found

    Characterization and evaluation of acid rain in East Central Florida from 1978 to 1987: Ten year summary report

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    Rainfall was collected on the University of Central Florida (UCF) campus near Orlando since July 1977 and at the Kennedy Space Center (KSC), Florida since August 1977. Since November 1983, the KSC site has been affiliated with the National Atmospheric Deposition Network. Annual volume weighted pH was slightly above the 10 year mean of 4.58 during four of the past five years. Nitrate concentrations have risen somewhat during recent years while excess sulfate concentrations have remained below the 10 year mean during four of the past years. These observations hold for both the UCF and KSC data. The distribution of individual sample pH was nearly identical at UCF and KSC. Stepwise regression suggests that sulfate, nitrate, ammonium ion, and calcium play major roles in the description of rainwater acidity. Annual acid deposition and annual rainfall have varied from 30 to 50 meq/m2-yr and 100 to 180 cm/yr, respectively. Sea salt comprises about 25 percent (UCF) and greater than 50 percent (KSC) of total ionic composition

    Acid rain monitoring in East-Central Florida from 1977 to present

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    Rainfall has been collected on the University of Central Florida campus and at the Kennedy Space Center over a 12 year period. The chemical composition has been determined and summarized by monthly, annual periods, and for the entire 12 year period at both locations. The weighted average pH at each site is 4.58; however, annual weighted average pH has been equal to or above the 12 year average during six of the past eight years. Nitrate concentrations have increased slightly during recent years while excess sulfate concentrations have remained below the 12 year weighted average during six of the past seven years. Stepwise regression suggests that sulfate, nitrate, ammonium ion and calcium play major roles in the description of rainwater acidity. Annual acid deposition and annual rainfall have varied from 20 to 50 meg/(m(exp 2) year) and 100 to 180 cm/year, respectively. Sea salt comprises at least 25 percent of the total ionic composition

    A summary of porous tube plant nutrient delivery system investigations from 1985 to 1991

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    The Controlled Ecological Life Support System (CELSS) Program is a research effort to evaluate biological processes at a one person scale to provide air, water, and food for humans in closed environments for space habitation. This program focuses currently on the use of conventional crop plants and the use of hydroponic systems to grow them. Because conventional hydroponic systems are dependent on gravity to conduct solution flow, they cannot be used in the microgravity of space. Thus, there is a need for a system that will deliver water and nutrients to plant roots under microgravity conditions. The Plant Space Biology Program is interested in investigating the effect that the space environment has on the growth and development of plants. Thus, there is also a need to have a standard nutrient delivery method for growing plants in space for research into plant responses to microgravity. The Porous Tube Plant Nutrient Delivery System (PTPNDS) utilizes a hydrophilic, microporous material to control water and nutrient delivery to plant roots. It has been designed and analyzed to support plant growth independent of gravity and plans are progressing to test it in microgravity. It has been used successfully to grow food crops to maturity in an earth-bound laboratory. This document includes a bibliography and summary reports from the growth trials performed utilizing the PTPNDS

    Post-Outburst Observations of V1647 Ori: Detection of a Brief Warm, Molecular Outflow

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    We present new observations of the fundamental ro-vibrational CO spectrum of V1647 Ori, the young star whose recent outburst illuminated McNeil's Nebula. Previous spectra, acquired during outburst in 2004 February and July, had shown the CO emission lines to be broad and centrally peaked-similar to the CO spectrum of a typical classical T Tauri star. In this paper, we present CO spectra acquired shortly after the luminosity of the source returned to its pre-outburst level (2006 February) and roughly one year later (2006 December and 2007 February). The spectrum taken in 2006 February revealed blue-shifted CO absorption lines superimposed on the previously observed CO emission lines. The projected velocity, column density, and temperature of this outflowing gas was 30 km/s, 3^{+2}_{-1}E18 cm^{-2$, and 700^{+300}_{-100} K, respectively. The absorption lines were not observed in the 2006 December and 2007 February data, and so their strengths must have decreased in the interim by a factor of 9 or more. We discuss three mechanisms that could give rise to this unusual outflow.Comment: 14 pages, 2 figures, accepted for publication in ApJ

    Molecular astronomy of cool stars and sub-stellar objects

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    The optical and infrared spectra of a wide variety of `cool' astronomical objects including the Sun, sunspots, K-, M- and S-type stars, carbon stars, brown dwarfs and extrasolar planets are reviewed. The review provides the necessary astronomical background for chemical physicists to understand and appreciate the unique molecular environments found in astronomy. The calculation of molecular opacities needed to simulate the observed spectral energy distributions is discussed

    Effects of space shuttle launches STS-1 through STS-9 on terrestrial vegetation of John F. Kennedy Space Center, Florida

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    Space Shuttle launches produce a cloud containing hydrochloric acid (HCl), aluminum oxide (Al203), and other substances. Acidities of less than 0.5 pH have been measured routinely in association with the launch cloud. In an area of about 22 ha regularly exposed to the exhaust cloud during most Shuttle launches, acute vegetation damage has resulted from the first nine Shuttle launches. Changes include loss of sensitive species, loss of plant community structure, reduction in total cover, and replacement of some species by weedy invaders. Community level changes define a retrogressive sequence. One-time impacts to strand and dune vegetation occurred after launches of STS-8 and STS-9. Acute vegetation damage occurred especially to sensitive species. Within six months, however, recovery was nearly complete. Sensitivity of species to the launch cloud was partially predicted by previous laboratory studies. Far-field acidic and dry fallout from the cloud as it rises to stabilization and moves with the prevailing winds causes vegetation spotting. Damage from this deposition is minor; typically at most 1% to 5% of leaf surface area is affected. No plant mortality or community changes have occurred from far-field deposition

    Time since injury influences eccentric hamstring force imbalance in collegiate American football players

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    Hamstring injuries (HSI) are among the most common non-contact injuries in American football. Understanding effects of duration since injury may inform how coaches, trainers, and athletes approach rehabilitation and return to play decisions. PURPOSE: To compare hamstring imbalance in athletes injured more than 12 months ago to hamstring imbalance in athletes with no HSI and compare hamstring imbalance in athletes injured within the last 12 months to imbalance in those with no HSI. METHODS: Sixty-one collegiate football players (age: 22.5 ± 1.8, height: 187.6 ± 6.2 cm, weight: 105 ± 21.6 kg) rostered in 2022 self-identified as having either (1) no HSI (n=45), or (2) having injured only one hamstring since grade 9. We separated those reporting previous injuries into two groups: those with injury longer ago than 12 months (historical HSI, n=12) and those injured with the last 12 months (recent HSI, n=4). All players performed eccentric hamstring curls on a Nordbord. For the group with no HSI, imbalance between legs was calculated as the stronger minus weaker leg. For both injured groups, imbalance was calculated as the difference between uninjured and injured legs. RESULTS: Analysis of the means was performed via Bayesian methods, assuming separate standard deviations for each group. Analysis of posterior chains indicated all parameters converged appropriately. The posterior mean of imbalance for players with no HSI was 34.7 ± 27.4 N. The posterior mean of imbalance in those with historical HSI was 10.8 ± 51.1 N. The posterior mean of imbalance in players with recent HSI was 48.9 ± 46.4 N. The posterior probability that the difference between imbalance of the no HSI group and the imbalance of the historical HSI group is greater than zero was 0.948, and the posterior probability that the imbalance of those with recent HSI and the imbalance of the no HSI group is greater than zero is 0.767. CONCLUSION: Collegiate football players with no HSI have greater hamstring imbalance than do those with historical HSI, implying healing process, rehabilitation efforts, and habitual movement patterns may reduce imbalance between hamstrings over a period of at least 12 months. As expected, players who have recent HSI demonstrate greater hamstring imbalance than players with no HSI

    Sensitivity analysis of the reactor safety study

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    Originally presented as the first author's thesis, (M.S.)--in the M.I.T. Dept. of Nuclear Engineering, 1979Includes bibliographical references (p. 232-233)Final research project reportFinal report for research project sponsored by Northeast Utilities Service Company, Yankee Atomic Electric Company under the M.I.T. Energy Laboratory Electric Utility Progra

    Twelve Tips for Just in Time Teaching of Communication Skills for Difficult Conversations in the Clinical Setting

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    The ability to communicate well with patients and other members of the healthcare team is a vital skill for physicians to have, but one that is often not emphasized in medical education. Learners of all levels can obtain and develop good communication skills regardless of their natural ability in this area, and the clinical setting represents an underutilized resource to accomplish this task. With this in mind, we have reviewed the growing body of literature on the subject and organized our findings into twelve tips to help educators capitalize on these missed opportunities. While our emphasis is helping learners with difficult discussions, these tips can be easily adapted to any other clinical encounter requiring clear communication. Teaching effective communication skills in the clinical setting requires some extra time, but the steps outlined should not take more than a few minutes to complete. Taking the time to develop these skills in our learners will make a significant difference not only their lives but also their patients and their families

    Coronal Line Emitters are Tidal Disruption Events in Gas-Rich Environments

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    Some galaxies show little to no sign of active galactic nucleus (AGN) activity, yet exhibit strong coronal emission lines (CLs) relative to common narrow emission lines. Many of these coronal lines have ionization potentials of ≥100\geq 100 eV, thus requiring strong extreme UV and/or soft X-ray flux. It has long been thought that such events are powered by tidal disruption events (TDEs), but owing to a lack of detailed multi-wavelength follow-up, such a connection has not been firmly made. Here we compare coronal line emitters (CLEs) and TDEs in terms of their host-galaxy and transient properties. We find that the mid-infrared (MIR) colors of CLE hosts in quiescence are similar to TDE hosts. Additionally, many CLEs show evidence of a large dust reprocessing echo in their mid-infrared colors, a sign of significant dust in the nucleus. The stellar masses and star formation rates of the CLE hosts are consistent with TDE hosts, and both populations reside within the green valley. The blackbody properties of CLEs and TDEs are similar, with some CLEs showing hot (T ≥40,000\geq 40,000 K) blackbody temperatures. Finally, the location of CLEs on the peak-luminosity/decline-rate parameter space is much closer to TDEs than many other major classes of nuclear transients. Combined, these provide strong evidence to confirm the previous claims that CLEs are indeed TDEs in gas-rich environments. We additionally propose a stricter threshold of CL flux ≥1/3\geq 1/3 ×\times [O III] flux to better exclude AGNs from the sample of CLEs.Comment: 9 pages, 7 figures. Will be submitted to MNRAS. Comments welcom
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