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At least 991 records · Page 55Linked to original sources
PubMed2001

Stable carbon isotope evidence for intrinsic bioremediation of tetrachloroethene and trichloroethene at area 6, Dover Air Force Base.

Area 6 at Dover Air Force Base (Dover, DE) has been the location of an in-depth study by the RTDF (Remediation Technologies Development Forum Bioremediation of Chlorinated Solvents Action Team) to evaluate the effectiveness of natural attenuation of chlorinated ethene contamination in groundwater. Compound-specific stable carbon isotope measurements for dissolved PCE and TCE in wells distributed throughout the anaerobic portion of the plume confirm that stable carbon isotope values are isotopically enriched in 13C consistent with the effects of intrinsic biodegradation. During anaerobic microbial reductive dechlorination of chlorinated hydrocarbons, the light (12C) versus heavy isotope (13C) bonds are preferentially degraded, resulting in isotopic enrichment of the residual contaminant in 13C. To our knowledge, this study is the first to provide definitive evidence for reductive dechlorination of chlorinated hydrocarbons at a field site based on the delta13C values of the primary contaminants spilled at the site, PCE and TCE. For TCE, downgradient wells show delta13C values as enriched as -18.0/1000 as compared to delta13C values for TCE in the source zone of -25.0 to -26.0/1000. The most enriched delta13C value on the site was observed at well 236, which also contains the highest concentrations of cis-DCE, VC, and ethene, the daughter products of reductive dechlorination. Stable carbon isotope signatures are used to quantify the relative extent of biodegradation between zones of the contaminant plume. On the basis of this approach, it is estimated that TCE in downgradient well 236 is more than 40% biodegraded relative to TCE in the proposed source area.

Biodegradation, Environmental↗
PubMed2003

Use of pretreatment zones and zero-valent iron for the remediation of chloroalkenes in an oxic aquifer.

Pretreatment zones (PTZs) composed of sand, 10% zero-valent iron [Fe(0)]/sand, and 10% pyrite (FeS2)/sand were examined for their ability to prolong Fe(0) reactivity in above ground column reactors and a subsurface permeable reactive barrier (PRB). The test site had an acidic, oxic aquifer contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE). The 10% FeS2 and 10% Fe(0) PTZs removed dissolved oxygen and affected the pH and E(h) in the PTZ. None of the PTZs had any effect on pH or E(h) in the 100% Fe(0) zone. Nitrate and sulfate were removed more quickly in the Fe(0) zones preceded by either the 10% Fe(0) PTZ or 10% FeS2. PCE first-order degradation rate constants (k(obs)) decreased significantly (> 80%) with increasing column pore volumes regardless of the PTZ material used. k(obs) finally leveled off after approximately 1 yr of operation. The column results predict that the PRB will experience a breakthrough of PCE in 3-5 yr and illustrate the importance of incorporating temporal variations in degradation rate constants when designing PRBs.

Biodegradation, Environmental↗
PubMed2005

Wet deposition of current use pesticides at a rural location on the Delmarva Peninsula: impact of rainfall patterns and agricultural activity.

Event-based precipitation samples were collected during the main agricultural season (April-September) over 4 years (2000-2003) at one site in the Choptank River Watershed on the Delmarva Peninsula. The samples were analyzed for 19 agricultural pesticides to determine the contribution of wet deposition as a source of these compounds to the Chesapeake Bay and the factors affecting the temporal trends in deposition. Chlorothalonil was detected most frequently (92% samples) followed by metolachlor (66%) and endosulfans (49%). Although chlorothalonil is the single biggest contributor to pesticide flux (33-46%), pesticide wet deposition is dominated by herbicides (46-61%), with the greatest fluxes occurring during the time of herbicide application on corn and soybeans. The analysis suggests that the extent of wet deposition of herbicides depends on the timing of precipitation relative to herbicide application. The insecticide and fungicide flux was greater in years with above-average rainfall (2001 and 2003), suggesting that for these pesticides deposition flux is dependent on the total amount of rainfall in the agricultural season. The data indicate that the use of chlorpyrifos, an organophosphate insecticide which is on the Toxics of Concern list for the Bay, is on the increase. Total pesticide flux ranged from 90 microg/m2 (2001) to 180 microg/m2 (2000). Wet deposition can account for up to 10-20% of the annual loadings of pesticides to the Bay.

Agriculture↗
PubMed2002

Crisis intervention program: an alternative to inpatient psychiatric treatment for children.

This study evaluated the impact of a Crisis Intervention program as an alternative to use of psychiatric treatment beds for young children. A multidisciplinary community-based intervention was utilized, including family therapy, psychiatric intervention, and school consultations. The impact of the service was evaluated in relation to the use of psychiatric treatment beds by the population of children eligible for Medicaid or uninsured. In comparison to an historical control group, the program resulted in a 23% reduction in the use of psychiatric treatment beds. A cost-minimization analysis indicated that in addition to the program reducing the use of psychiatric treatment beds, the cost of treatment was also slightly reduced.

Child↗
PubMed2004

Utilization of public mental health services by adults with serious mental illness.

Public mental health (MH) services were examined for non-elderly adults with serious mental illness (SMI) using a database combining information from Medicaid, MH, and substance abuse agencies in three states. These data show that between 23% and 39% of those with SMI received MH services only through Medicaid. Relative use of community versus state hospitals for delivery of psychiatric inpatient care varied across the three states. However, state hospitals accounted for a large proportion of total inpatient days, due to high mean annual days of care. In two states, Medicaid paid for fewer psychiatric inpatient days than expected.

Adult↗
PubMed2004

Landscape ecological assessment of the Chesapeake Bay watershed.

The Chesapeake Bay Watershed, located in the Mid-Atlantic Region of the United States, is experiencing rapid habitat loss and fragmentation from sprawling low-density development. The bay itself is heavily stressed by excess sediment and nutrient runoff. Three states, the District of Columbia, and the federal government signed an agreement in 2000 to address these problems. The commitments included an assessment of the watershed's resource lands, and targeting the most valued lands for protection. As part of this task, the Resource Lands Assessment identified an ecological network comprised of large contiguous blocks (hubs) of forests, wetlands, and streams, interconnected by corridors to allow animal and plant propagule dispersal and migration. Hubs were prioritized by ecoregion, by analyzing a variety of ecological parameters, including: rare species presence, rarity and population viability; vegetation and vertebrate richness; habitat area, condition, and diversity; intactness and remoteness; connectivity potential; and the nature of the surrounding landscape. I found that much of the watershed was still fairly intact, although this varied dramatically by ecoregion. Current protection also varied, and an assessment of vulnerability will help focus protection efforts among the most valuable hubs and corridors.

Animals↗
PubMed2004

Assessing development pressure in the Chesapeake Bay watershed: an evaluation of two land-use change models.

Natural resource lands in the Chesapeake Bay watershed are increasingly susceptible to conversion into developed land uses, particularly as the demand for residential development grows. We assessed development pressure in the Baltimore-Washington, DC region, one of the major urban and suburban centers in the watershed. We explored the utility of two modeling approaches for forecasting future development trends and patterns by comparing results from a cellular automata model, SLEUTH (slope, land use, excluded land, urban extent, transportation), and a supply/demand/allocation model, the Western Futures Model. SLEUTH can be classified as a land-cover change model and produces projections on the basis of historic trends of changes in the extent and patterns of developed land and future land protection scenarios. The Western Futures Model derives forecasts from historic trends in housing units, a U.S. Census variable, and exogenously supplied future population projections. Each approach has strengths and weaknesses, and combining the two has advantages and limitations.

Baltimore↗
PubMed2006

Racial differences in prenatal care of mothers delivering very low birth weight infants.

OBJECTIVES: To determine whether there are any racial differences in the prenatal care of mothers delivering very low birth weight infants (VLBW). STUDY DESIGN: Retrospective cohort study of infants cared for at a single regional level III neonatal intensive care unit over a 9-year period, July 1993-June 2002, N = 1234. The main outcome variables investigated included antenatal administration of steroids, delivery by cesarean section, and use of tocolytic medications. Both univariate and multivariate analyses were performed. RESULTS: After controlling for potential confounding variables, white mothers delivering VLBWs had an increased odds of cesarean delivery (odds ratio 1.5, 95% confidence intervals (CI) 1.1-2.0), receiving antenatal steroids (1.3, CI 1.01-1.8), and tocolysis (1.4, CI 1.1-2.0) compared to black mothers. The models controlled for gestational age, multiple gestation, premature labor, clinical chorioamnionitis, maternal age, income, year of birth, and presentation. CONCLUSIONS: In our population of VLBWs, white mothers are more likely to receive antenatal steroids, tocolytic medications, and deliver by cesarean section when compared to black mothers. From our data we cannot determine the reasons behind these racial differences in care of mothers delivering VLBWs.

Black or African American↗
PubMed2005

Reactions of a stable silylene with halocarbons.

An unusual product formation is observed for the insertion reaction of the thermally stable silylene Si[(NCH(2)Bu(t))(2)C(6)H(4)-1,2][abbrev. as Si(NN)] into the carbon-halogen bond of alkyl or aryl halides RHal (Hal=Cl, Br). In general, depending on the halogen, the reaction either results in a disilane of type (NN)Si(Hal)-(R)Si(NN) for Hal=Cl or a mixture of disilane and the monosilane (NN)Si(R)(Hal) for Hal=Br. The results are put into context to previously suggested mechanisms. The disilane (NN)Si(Hal)-(R)Si(NN)(Hal=Cl or Br) is thermally labile and mild thermolysis yields the corresponding monosilane (NN)Si(R)(Hal) and silylene 1. Additionally, strong evidence is presented for a radical pathway for the reaction of 1 and RHal.

Journal Article↗
PubMed1993

Informed consent for blood transfusion: a regional hospital survey.

Ninety-two hospitals in a three-state mid-Atlantic region were surveyed to determine their policy toward obtaining written informed consent for transfusion and to examine the content of written consent documents and the process by which consent is obtained. Of 81 hospitals responding, 50 (62%) required written informed consent. Hospitals with fewer than 200 beds were more likely to require written informed consent. The attending physicians had responsibility for obtaining consent in 28 (57%) of 49 institutions, most often on the day or evening before surgery. Twenty-seven of 48 forms mentioned complications: hepatitis in 80 percent, human immunodeficiency virus infection in 46 percent, nonhemolytic reactions in 32 percent, and hemolysis in 25 percent. Alternatives to allogeneic transfusion were mentioned infrequently; eight hospital forms listed autologous transfusion options and only two mentioned designated donation. The reading level required to comprehend 34 consent forms submitted was grade 14.6, which has been attained by only 23 percent of the adult United States population. Although the majority of respondent institutions require written informed consent, those forms, per se, do not document that the fundamental tenets of informed choice have been applied to the decision to transfuse blood.

Blood Banks↗
PubMed2000

Ambulance use by high-acuity patients in a pediatric ED.

The objective of this study was to analyze ambulance usage by highest acuity patients as compared with all patients in a suburban pediatric hospital ED. A 1-year retrospective records analysis was conducted of all highest acuity patients (those patients triaged as emergent or critical or admitted to the intensive care unit). A total of 245 patients made 270 high-acuity visits to the ED in 1995. Thirty-one (13%) of the high-acuity patients arrived via ambulance; the rest arrived via private vehicle. The 31 high-acuity patients constituted 8% of the total number of patients arriving by ambulance. There was no significant difference in ambulance usage between insurance groups in the high-acuity patients. Only high-acuity patients with neurologic symptoms (primarily seizures) had a greater relative use of EMS transportation, with 39% of these patients arriving via ambulance (odds ratio 6.6, 95% confidence interval 2.6,16.6). High-acuity patients account for the minority of total ambulance usage in our ED.

Ambulances↗
PubMed2004

Uterine rupture in patients with a prior cesarean delivery: the impact of cervical ripening.

The purpose of this study was to examine factors that were associated with uterine rupture in patients attempting vaginal birth after cesarean delivery. We analyzed the results of all patients attempting vaginal birth after cesarean delivery between September 1996 to December 1999 at a single institution using a contemporaneously maintained registry. Maternal factors, fetal factors, and management of labor were all assessed to determine the risk factors associated with symptomatic uterine rupture at the time of attempted vaginal birth after cesarean delivery. Twenty-eight symptomatic ruptures were identified in 972 attempts of vaginal birth after cesarean delivery at a gestational age greater than 24 weeks (2.88%). The use of preinduction cervical ripening was significantly associated with an increased risk of symptomatic uterine rupture (odds ratio, 3.92; 95% confidence interval, 1.78 to 8.62). Patients who underwent preinduction cervical ripening were significantly less likely to delivery vaginally than women who had not (46.71 versus 76.87%; p < 0.001). No other differences were noted between the two groups. Preinduction cervical ripening is associated with an increased risk of uterine rupture in women attempting vaginal birth after cesarean delivery.

Adult↗
PubMed1985

Trends in the incidence of myocardial infarction and in associated mortality and morbidity in a large employed population, 1957-1983.

We analyzed long-term trends in the incidence of a first acute myocardial infarction and in case-fatality rates among employees of the Du Pont Company from 1957 through 1983. A steady decline in incidence was observed among male employees. The annual age-adjusted rate in the 1957-1959 period was 3.19 per 1000, as compared with 2.29 per 1000 in the 1981-1983 period--a decline of 28.2 per cent. The rate of decline was higher among salaried (white-collar) employees than among production workers receiving hourly wages. No trend was seen among female employees, but the number of cases may have been to small to detect a decline. Beginning in 1969, the 24-hour case-fatality rate showed a moderate decline, but after 1975, there was a sharp drop in the 30-day case-fatality rate among persons who survived 24 hours after the attack. These declines did not begin until several years after the decline in incidence had begun. This study and others suggest that improved medical care probably made some contribution to the decline in mortality associated with coronary heart disease, but the major source of the decline has been a reduction in the incidence of the disease.

Adult↗