1,761 research outputs found
Large-scale Reservoir Simulations on IBM Blue Gene/Q
This paper presents our work on simulation of large-scale reservoir models on
IBM Blue Gene/Q and studying the scalability of our parallel reservoir
simulators. An in-house black oil simulator has been implemented. It uses MPI
for communication and is capable of simulating reservoir models with hundreds
of millions of grid cells. Benchmarks show that our parallel simulator are
thousands of times faster than sequential simulators that designed for
workstations and personal computers, and the simulator has excellent
scalability
Degradation of isazofos in the soil environment
Field and laboratory studies were conducted to investigate the degradation of the organophosphorus insecticide isazofos (0-5-chloro-l-isopropyl-1H-l,2,4-triazol-3-ylO,O-diethyl phosphorothioate) in soil. In a 6-year field study, soil pH was an important factor influencing the degradation of isazofos inasmuch as an increased rate of degradation was observed in soils with previous isazofos applications and pH of 6.9 or more. A laboratory study of [14Clisazofos confirmed the rapid degradation of this insecticide in high pH soils. No increased degradation rate, however, was observed in sterilized high-pH soils. The availability of isazofos to microorganisms, based on sorption of isazofos to soil, seems to be an important factor influencing the degradation of isazofos in soil. Sorption coefficients were negatively correlated with isazofos degradation rate
Detoxification of Pesticide Residues in Soil Using Phytoremediation
During the past few years, we have conducted a series of experiments to investigate the potential of using plants as tools for the remediation of pesticide-contaminated soil. We have demonstrated that a blend of prairie grasses increases dissipation rates of several pesticides including metolachlor, trifluralin, and pendimethalin. However, in other studies, mulberry trees were not shown to influence pesticide dissipation. Additional studies have demonstrated that metolachlor movement in the soil column may be reduced by the presence of prairie grasses, bioavailability of dinitroanaline herbicides may be reduced during phytoremediation, and soil and leachate from remediated soil may have less toxicity than expected. Current studies within our laboratory are being conducted to determine the role of prairie grass blends in the phytoremediation procedure as compared to individual species and the role of plant uptake of pesticides in the phytoremediation process
Persistence, Mobility, and Bioavailability of Pendimethalin and Trifluralin in Soil
Pendimethalin and trifluralin are current-use pesticides that have been previously reported as persistent, bioaccumulative, and toxic. In the studies presented here, dissipation of aged and fresh residues of pendimethalin and trifluralin were evaluated in soil, as well as the bioavailability of residues to earthworms and the movement of pendimethalin in a soil column. In a separate study, pond water receiving runoff from a golf course was measured for the presence of pendimethalin. Dissipation measurements of pendimethalin and trifluralin in soil indicated very slow dissipation with 40-60% of the compounds extractable at 1026 days after the first measurement. In a second study, dissipation of pendimethalin was more rapid, however more than 30% was present after 310 days of soil treatment. Biovailability, as measured by earthworm biological accumulation factors, was reduced over time. Mobility of pendimethalin was very limited. Almost no downward movement was measured in the column study, and no detectable levels were found in runoff from turf grass
Longitudinal Evaluation of Eye Misalignment and Eye Movements Following Surgical Correction of Strabismus in Monkeys
Purpose: Strabismus correction surgery is well documented in both the literature and practice with varying levels of success and permanence. Our goal was to characterize longitudinal changes in eye alignment and eye movements following strabismus correction surgery in a monkey model for developmental strabismus. Methods: We studied two juvenile rhesus monkeys with exotropia previously induced via an optical prism-rearing paradigm in infancy. Eye misalignment was corrected via a resection–recession surgery of the horizontal rectus muscles of one eye. Binocular search coils were used to collect eye movement data during smooth-pursuit, saccades, and fixation tasks before surgical treatment, immediately after surgery, and through 6 months after treatment. Results: Both animals showed an immediate ?70% reduction in misalignment as a consequence of surgery that regressed to a 20%–40% improvement by 6 months after treatment. Significant changes were observed in saccade and smooth-pursuit gain of the nonviewing eye after surgery, which also reverted to presurgical values by 6 months. A temporary improvement in fixation stability of the nonviewing eye was observed after surgery; naso-temporal (N/T) asymmetry of monocular smooth-pursuit remained unchanged. Conclusions: Surgical realignment is followed by plastic changes that often lead to reversal of surgery effects. Immediate improvement in misalignment and changes in eye movement gains are likely a result of contractility changes at the level of the extraocular muscle, whereas longer-term effects are likely a combination of neural and muscle adaptation
Occurrence of Atrazine and Degradates as Contaminants of Subsurface Drainage and Shallow Groundwater
Atrazine is a commonly used herbicide in corn (Zea mays L.) growing areas of the USA. Because of its heavy usage, moderate persistence, and mobility in soil, monitoring of atrazine movement under field conditions is essential to assess its potential to contaminate groundwater. Concentrations of atrazine, deisopropylatrazine (DIA), and deethylatrazine (DEA) were measured in subsurface drainage and shallow groundwater beneath continuous, no-till corn. Water samples were collected from the subsurface drain (tile) outlets and suction lysimeters in the growing seasons of 1990 and 1991, and analyzed for atrazine and two principle degradates using solid-phase extraction and HPLC. In 1990, atrazine concentration ranged from 1.3 to 5.1 µg L−1 in tile-drain water and from 0.5 to 20.5 µg L−1 in lysimeter water. In general, concentrations of parent and degradates in solution were atrazine \u3e DEA \u3e DIA. Lesser levels of atrazine were measured in 1991 from Plots 2 and 4; however, greater concentrations of atrazine (6.0–8.4 µg L−1) were measured from Plot 5. Throughout the two growing seasons, atrazine concentration in Plot 5 tile-drain water was greater than that of Plots 2 and 4, suggesting a preferential movement of atrazine. Concentrations of DIA and DEA ranged from 0.1 to 2.2 and 0.9 to 3.2 µg L−1, respectively, indicating that the degradation products by themselves or in combination with parent atrazine can exceed the maximum contaminant level (mcl) of 3 µg L−1 even though atrazine by itself may be \u3c3 µg L−1. The deethylatrazineto-atrazine ratio (DAR) is an indicator of residence time in soil during transport of atrazine to groundwater. In Plots 2 and 4, DAR values for tile-drain water ranged from 0.43 to 2.70 and 0.50 to 2.66, respectively. By comparison, a DAR of 0.38 to 0.60 was observed in Plot 5, suggesting less residence time in the soil
Helicopter and ground emergency medical services transportation to hospital after major trauma in England: a comparative cohort study
Background: The utilization of helicopter emergency medical services (HEMS) in modern trauma systems has been a source of debate for many years. This study set to establish the true impact of HEMS in England on survival for patients with major trauma.
Methods: A comparative cohort design using prospectively recorded data from the UK Trauma Audit and Research Network registry. 279 107 patients were identified between January 2012 and March 2017. The primary outcome measure was risk adjusted in-hospital mortality within propensity score matched cohorts using logistic regression analysis. Subset analyses were performed for subjects with prehospital Glasgow Coma Scale 29 and systolic blood pressure <90.
Results: The analysis was based on 61 733 adult patients directly admitted to major trauma centers: 54 185 ground emergency medical services (GEMS) and 7548 HEMS. HEMS patients were more likely male, younger, more severely injured, more likely to be victims of road traffic collisions and intubated at scene. Crude mortality was higher for HEMS patients. Logistic regression demonstrated a 15% reduction in the risk adjusted odds of death (OR=0.846; 95% CI 0.684 to 1.046) in favor of HEMS. When analyzed for patients previously noted to benefit most from HEMS, the odds of death were reduced further but remained statistically consistent with no effect. Sensitivity analysis on 5685 patients attended by a doctor on scene but transported by GEMS demonstrated a protective effect on mortality versus the standard GEMS response (OR 0.77; 95% CI 0.62 to 0.95).
Discussion: This prospective, level 3 cohort analysis demonstrates a non-significant survival advantage for patients transported by HEMS versus GEMS. Despite the large size of the cohort, the intrinsic mismatch in patient demographics limits the ability to statistically assess HEMS true benefit. It does, however, demonstrate an improved survival for patients attended by doctors on scene in addition to the GEMS response. Improvements in prehospital data and increased trauma unit reporting are required to accurately assess HEMS clinical and cost-effectiveness
Exercise-based rehabilitation for heart failure: systematic review and meta-analysis
This is the final version of the article. Available from BMJ Publishing Group via the DOI in this record.OBJECTIVE: To update the Cochrane systematic review of exercise-based cardiac rehabilitation (CR) for heart failure. METHODS: A systematic review and meta-analysis of randomised controlled trials was undertaken. MEDLINE, EMBASE and the Cochrane Library were searched up to January 2013. Trials with 6 or more months of follow-up were included if they assessed the effects of exercise interventions alone or as a component of comprehensive CR programme compared with no exercise control. RESULTS: 33 trials were included with 4740 participants predominantly with a reduced ejection fraction (<40%) and New York Heart Association class II and III. Compared with controls, while there was no difference in pooled all-cause mortality between exercise CR with follow-up to 1 year (risk ratio (RR) 0.93; 95% CI 0.69 to 1.27, p=0.67), there was a trend towards a reduction in trials with follow-up beyond 1 year (RR 0.88; 0.75 to 1.02, 0.09). Exercise CR reduced the risk of overall (RR 0.75; 0.62 to 0.92, 0.005) and heart failure-specific hospitalisation (RR 0.61; 0.46 to 0.80, 0.0004) and resulted in a clinically important improvement in the Minnesota Living with Heart Failure questionnaire (mean difference: -5.8 points, -9.2 to -2.4, 0.0007). Univariate meta-regression analysis showed that these benefits were independent of the type and dose of exercise CR, and trial duration of follow- up, quality or publication date. CONCLUSIONS: This updated Cochrane review shows that improvements in hospitalisation and health-related quality of life with exercise-based CR appear to be consistent across patients regardless of CR programme characteristics and may reduce mortality in the longer term. An individual participant data meta-analysis is needed to provide confirmatory evidence of the importance of patient subgroup and programme level characteristics (eg, exercise dose) on outcome.This publication presents independent research funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (Grant Reference Number RP-PG-1210-12004)
Устроєві засади громадського судочинства й народна правосвідомість на українських землях у складі Великого Князівства Литовського
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