267 research outputs found
Risk Assessment Plan for Petroleum Underground Storage Tanks in Kentucky, Part ll: Diesel, Heating Oil, Other Middle Distillates and Waste Oil
This report consists of an appendix :Risk Assessment Plan for Petroleum Underground Storage Tanks in Kentucky and a second appendix: Environmental Half-Life and Ecological Effects of PAH
A Halomethane thermochemical network from iPEPICO experiments and quantum chemical calculations
Internal energy selected halomethane cations CH3Cl+, CH2Cl2+, CHCl3+, CH3F+, CH2F2+, CHClF2+ and CBrClF2+ were prepared by vacuum ultraviolet photoionization, and their lowest energy dissociation channel studied using imaging photoelectron photoion coincidence spectroscopy (iPEPICO). This channel involves hydrogen atom loss for CH3F+, CH2F2+ and CH3Cl+, chlorine atom loss for CH2Cl2+, CHCl3+ and CHClF2+, and bromine atom loss for CBrClF2+. Accurate 0 K appearance energies, in conjunction with ab initio isodesmic and halogen exchange reaction energies, establish a thermochemical network, which is optimized to update and confirm the enthalpies of formation of the sample molecules and their dissociative photoionization products. The ground electronic states of CHCl3+, CHClF2+ and CBrClF2+ do not confirm to the deep well assumption, and the experimental breakdown curve deviates from the deep well model at low energies. Breakdown curve analysis of such shallow well systems supplies a satisfactorily succinct route to the adiabatic ionization energy of the parent molecule, particularly if the threshold photoelectron spectrum is not resolved and a purely computational route is unfeasible. The ionization energies have been found to be 11.47 ± 0.01 eV, 12.30 ± 0.02 eV and 11.23 ± 0.03 eV for CHCl3, CHClF2 and CBrClF2, respectively. The updated 0 K enthalpies of formation, âfHo0K(g) for the ions CH2F+, CHF2+, CHCl2+, CCl3+, CCl2F+ and CClF2+ have been derived to be 844.4 ± 2.1, 601.6 ± 2.7, 890.3 ± 2.2, 849.8 ± 3.2, 701.2 ± 3.3 and 552.2 ± 3.4 kJ molâ1, respectively. The âfHo0K(g) values for the neutrals CCl4, CBrClF2, CClF3, CCl2F2 and CCl3F and have been determined to be â94.0 ± 3.2, â446.6 ± 2.7, â702.1 ± 3.5, â487.8 ± 3.4 and â285.2 ± 3.2 kJ molâ1, respectively
Multilevel needs assessment of physical activity, sport, psychological needs, and nutrition in rural children and adults
IntroductionPhysical activity yields significant benefits, yet fewer than 1 in 4 youth meet federal guidelines. Children in rural areas from low socioeconomic (SES) backgrounds face unique physical activity contextual challenges. In line with Stage 0 with the NIH Stage Model for Behavioral Intervention Development, the objective of the present study was to conduct a community-engaged needs assessment survey with middle school children and adults to identify perceptions, barriers, and facilitators of physical activity, sport, psychological needs, and nutrition from a multi-level lens.MethodsA cross-sectional survey data collection was conducted with children (nâ=â39) and adults (nâ=â63) from one middle school community in the Midwestern United States. The child sample was 33% 6th grade; 51% 7th grade and was 49% female. The adult sample was primarily between 30 and 39 years old (70%) and comprised predominantly of females (85%). Multi-level survey design was guided by the psychological needs mini-theory within self-determination theory and aimed to identify individual perceptions, barriers, and facilitators in line with the unique context of the community.ResultsAt the individual level, 71.8% of children and 82.2% of the overall sample (children and adults) were interested in new physical activity/sport programming for their school. Likewise, 89.7% of children and 96.8% of adults agree that PA is good for physical health. For basic psychological needs in the overall sample, relatedness was significantly greater than the autonomy and competence subscales. Childrenâs fruit and vegetable intake were below recommended levels, yet only 43.6% of children were interested in nutritional programming. Conversely, 61.5% indicated interest at increasing leadership skills. At the policy-systems-environmental level, the respondentsâ feedback indicated that the condition and availability of equipment are areas in need of improvement to encourage more physical activity. Qualitative responses are presented within for physical activity-related school policy changes.DiscussionInterventions addressing childrenâs physical activity lack sustainability, scalability, and impact due to limited stakeholder involvement and often neglect early behavioral intervention stages. The present study identified perspectives, barriers, and facilitators of physical activity, sport, psychological needs, and nutrition in a multi-level context and forms the initial campus-community partnership between scientists and community stakeholders
Genetic Covariance Structure of Reading, Intelligence and Memory in Children
This study investigates the genetic relationship among reading performance, IQ, verbal and visuospatial working memory (WM) and short-term memory (STM) in a sample of 112, 9-year-old twin pairs and their older siblings. The relationship between reading performance and the other traits was explained by a common genetic factor for reading performance, IQ, WM and STM and a genetic factor that only influenced reading performance and verbal memory. Genetic variation explained 83% of the variation in reading performance; most of this genetic variance was explained by variation in IQ and memory performance. We hypothesize, based on these results, that children with reading problems possibly can be divided into three groups: (1) children low in IQ and with reading problems; (2) children with average IQ but a STM deficit and with reading problems; (3) children with low IQ and STM deficits; this group may experience more reading problems than the other two
Mini-laparoscopic versus laparoscopic approach to appendectomy
BACKGROUND: The purpose of this clinical study is to evaluate the feasibility of using 2-mm laparoscopic instruments to perform an appendectomy in patients with clinically suspected acute appendicitis and compare the outcome of this mini-laparoscopic or "needlescopic" approach to the conventional laparoscopic appendectomy. METHODS: Two groups of patients undergoing appendectomy over 24 months were studied. In the first group, needlescopic appendectomy was performed in 15 patients by surgeons specializing in advanced laparoscopy. These patients were compared with the second or control group that included 21 consecutive patients who underwent laparoscopic appendectomy. We compared the patients' demographic data, operative findings, complications, postoperative pain medicine requirements, length of hospital stay, and recovery variables. Differences were considered statistically significant at a p-value < 0.05. RESULTS: Patient demographics, history of previous abdominal surgery, and operative findings were similar in both groups. There was no conversion to open appendectomy in either group. No postoperative morbidity or mortality occurred in either group. The needlescopic group had a significantly shorter mean operative time (p = 0.02), reduced postoperative narcotics requirements (p = 0.05), shorter hospital stay (p = 0.04), and quicker return to work (p = 0.03) when compared with the laparoscopic group. CONCLUSIONS: We conclude that the needlescopic technique is a safe and effective approach to appendectomy. When performed by experienced laparoscopic surgeons, the needlescopic technique results in significantly shorter postoperative convalescence and a prompt recovery
Reactive nitrogen partitioning and its relationship to winter ozone events in Utah
High wintertime ozone levels have been observed in the Uintah Basin, Utah, a
sparsely populated rural region with intensive oil and gas operations. The
reactive nitrogen budget plays an important role in tropospheric ozone
formation. Measurements were taken during three field campaigns in the
winters of 2012, 2013 and 2014, which experienced varying climatic
conditions. Average concentrations of ozone and total reactive nitrogen were
observed to be 2.5 times higher in 2013 than 2012, with 2014 an intermediate
year in most respects. However, photochemically active NO<sub><i>x</i></sub>
(NOâŻ+âŻNO<sub>2</sub>) remained remarkably similar all three years. Nitric acid
comprised roughly half of NO<sub><i>z</i></sub> (ââĄââŻNO<sub><i>y</i></sub>âŻââŻNO<sub><i>x</i></sub>) in 2013,
with nighttime nitric acid formation through heterogeneous uptake of
N<sub>2</sub>O<sub>5</sub> contributing approximately 6 times more than daytime formation. In
2012, N<sub>2</sub>O<sub>5</sub> and ClNO<sub>2</sub> were larger components of NO<sub><i>z</i></sub> relative to
HNO<sub>3</sub>. The nighttime N<sub>2</sub>O<sub>5</sub> lifetime between the high-ozone year 2013
and the low-ozone year 2012 is lower by a factor of 2.6, and much of this is
due to higher aerosol surface area in the high-ozone year of 2013. A
box-model simulation supports the importance of nighttime chemistry on the
reactive nitrogen budget, showing a large sensitivity of NO<sub><i>x</i></sub> and ozone
concentrations to nighttime processes
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Propagation of Reactions in Thermally-damaged PBX-9501
A thermally-initiated explosion in PBX-9501 (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) is observed in situ by flash x-ray imaging, and modeled with the LLNL multi-physics arbitrary-Lagrangian-Eulerian code ALE3D. The containment vessel deformation provides a useful estimate of the reaction pressure at the time of the explosion, which we calculate to be in the range 0.8-1.4 GPa. Closely-coupled ALE3D simulations of these experiments, utilizing the multi-phase convective burn model, provide detailed predictions of the reacted mass fraction and deflagration front acceleration. During the preinitiation heating phase of these experiments, the solid HMX portion of the PBX-9501 undergoes a {beta}-phase to {delta}-phase transition which damages the explosive and induces porosity. The multi-phase convective burn model results demonstrate that damaged particle size and pressure are critical for predicting reaction speed and violence. In the model, energetic parameters are taken from LLNL's thermochemical-kinetics code Cheetah and burn rate parameters from Son et al. (2000). Model predictions of an accelerating deflagration front are in qualitative agreement with the experimental images assuming a mode particle diameter in the range 300-400 {micro}m. There is uncertainty in the initial porosity caused by thermal damage of PBX-9501 and, thus, the effective surface area for burning. To better understand these structures, we employ x-ray computed tomography (XRCT) to examine the microstructure of PBX-9501 before and after thermal damage. Although lack of contrast between grains and binder prevents the determination of full grain size distribution in this material, there are many domains visible in thermally damaged PBX-9501 with diameters in the 300-400 {micro}m range
Rapid evolution of A(H5N1) influenza viruses after intercontinental spread to North America
Highly pathogenic avian influenza A(H5N1) viruses of clade 2.3.4.4b underwent an explosive geographic expansion in 2021 among wild birds and domestic poultry across Asia, Europe, and Africa. By the end of 2021, 2.3.4.4b viruses were detected in North America, signifying further intercontinental spread. Here we show that the western movement of clade 2.3.4.4b was quickly followed by reassortment with viruses circulating in wild birds in North America, resulting in the acquisition of different combinations of ribonucleoprotein genes. These reassortant A(H5N1) viruses are genotypically and phenotypically diverse, with many causing severe disease with dramatic neurologic involvement in mammals. The proclivity of the current A(H5N1) 2.3.4.4b virus lineage to reassort and target the central nervous system warrants concerted planning to combat the spread and evolution of the virus within the continent and to mitigate the impact of a potential influenza pandemic that could originate from similar A(H5N1) reassortants
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