Closed root canals likely have an oxygen-free environment; most bacteria in canals are anaerobic. These bacteria and other debris are difficult to remove. Unknown is tissue dissolution with chemicals ...under these anaerobic conditions. This study evaluated and compared dissolving properties of calcium hydroxide (Ca(OH)
2) and sodium hypochlorite (NaOCI) on bovine pulp tissue in aerobic and anaerobic environments. Sixty bovine pulp specimens were dried, then randomly divided into six groups. Groups A and B were immersed in Ca(OH)
2 + water solution, whereas group C and D were in 2.5% NaOCI. Groups E and F (controls) specimens were placed in distilled water. Groups A, C, and E were incubated anaerobically, and groups B, D, and F were incubated under regular atmospheric conditions, all for 7 days. Percentages of weight loss were compared between groups. Results showed the following: (a) both chemicals partially dissolved pulp tissue, (b) anaerobic environment did not alter tissue-dissolving properties of Ca(OH)
2 or NaOCI, and (c) Ca(OH)
2 and NaOCI were equal and more effective than water.
A prospective, randomized, clinical trial was conducted to investigate whether a postpartum visit between a mother and her neonate's future primary care provider combined with telephone access would ...improve health care utilization, enhance identification of the provider as a source of advice, increase maternal knowledge of infant care, and decrease maternal anxiety and depression. Of 251 mother-neonate pairs, 122 were randomized to the control group and 129 to the intervention group. Outcome variables included health care utilization and results of maternal interviews. More mothers in the intervention group made a scheduled clinic visit in the first 30 days (P = .003), were more likely to seek some form of care at the clinic (P = .006), and tried to reach their physician by phone more often than the control group (P less than .001). There were no differences between the groups' emergency room utilization, the percent who received immunizations by 90 days of age, maternal knowledge of infant care, maternal anxiety, or postpartum depression. The intervention succeeded in improving some measures of health care utilization and results suggest that the relationship between the mother and clinician was strengthened.
Receptor modeling study of Denver winter haze Lewis, Charles W; Baumgardner, Ralph H; Stevens, Robert K ...
Environmental science & technology,
11/1986, Letnik:
20, Številka:
11
Journal Article
Recenzirano
Source contributions to fine and coarse aerosol mass and light extinction measured in Denver, Co, during January 1982 were estimated. Estimates were generated by a multiple regression single element ...tracer method in combination with sulfur dioxide and nitrogen oxides emissions inventory scaling. Motor vehicles were the largest contributor to average fine particle mass and daytime light extinction, accounting for 42% and 47% of these parameters, respectively. Electric power generation was next largest, at 23% and 44%, respectively. Wood burning contributed 12% and 14%, respectively. During high pollution periods, the motor vehicle impact during the day and the woodsmoke impact at night were relatively greater than their averages.
A LINGUISTIC ARGUMENT FOR GOD'S EXISTENCE Baumgardner, John R; Lyon, Jeremy D
Journal of the Evangelical Theological Society,
12/2015, Letnik:
58, Številka:
4
Journal Article
The U.S. EPA （Environmental Protection Agency） established the CASTNET （Clean Air Status and Trends Network） and its predecessor, the NDDN （national dry deposition network）, as national air quality ...and meteorological monitoring networks. Both CASTNET and NDDN were designed to measure concentrations of sulfur and nitrogen gases and particles. Both networks also estimate dry deposition using an inferential model. The design was based on the concept that atmospheric dry deposition flux could be estimated as the product of a measured air pollutant concentration and a modeled deposition velocity （Vd）. The MLM （multi-layer model）, the computer model used to simulate dry deposition, requires information on meteorological conditions and vegetative cover as model input. The MLM calculates hourly Fa for each pollutant, but any missing meteorological data for an hour renders Vd missing for that hour. Because of percent completeness requirements for aggregating data for long-term estimates, annual deposition rates for some sites are not always available primarily because of missing or invalid meteorological input data. In this work, three methods for replacing missing on-site measurements are investigated. These include （1） using historical values of deposition velocity or （2） historical meteorological measurements from the site being modeled or （3） current meteorological data from nearby sites to substitute for missing inputs and thereby improve data completeness for the network＇s dry deposition estimates. Results for a CASTNET site used to test the methods show promise for using historical measurements of weekly average meteorological parameters.
On a global scale basalts from mid-ocean ridges are strikingly more homogeneous than basalts from intraplate volcanism. The observed geochemical heterogeneity argues strongly for the existence of ...distinct reservoirs in the Earth's mantle. It is an unresolved problem of Geodynamics as to how these findings can be reconciled with large-scale convection. We review observational constraints, and investigate stirring properties of numerical models of mantle convection.
Conditions in the early Earth may have supported layered convection with rapid stirring in the upper layers. Material that has been altered near the surface is transported downwards by small-scale convection. Thereby a layer of homogeneous depleted material develops above pristine mantle.
As the mantle cools over Earth history, the effects leading to layering become reduced and models show the large-scale convection favoured for the Earth today. Laterally averaged, the upper mantle below the lithosphere is least affected by material that has experienced near-surface differentiation. The geochemical signature obtained during the previous episode of small-scale convection may be preserved there for the longest time. Additionally, stirring is less effective in the high viscosity layer of the central lower mantle 1, 2, supporting the survival of medium-scale heterogeneities there.
These models are the first, using 3-d spherical geometry and mostly Earth-like parameters, to address the suggested change of convective style. Although the models are still far from reproducing our planet, we find that proposal might be helpful towards reconciling geochemical and geophysical constraints.
Objective. To examine the distribution of superoxide in the uninflamed and inflamed dental pulp by characterizing the immunoreactivity of the detoxifying antioxidant enzymes, manganese and ...copper-zinc superoxide dismutases (MnSOD and CuZnSOD, respectively).
Study design. In 12 rats, mesial cavity preparations were made on the maxillary right first molar; left molars were unoperated controls. After 5 days, the rats were killed, and histologic sections were processed by using MnSOD and CuZnSOD immunoreactivity, and the extent of inflammation was evaluated on alternate sections stained with hematoxylin and eosin.
Results. In the hematoxylin and eosin-stained sections, inflammation was consistent with
round-cells: macrophages, lymphocytes, and plasma cells that coalesced into a distinct leukocytic “lesion,” which obliterated portions of the underlying pulp. Both MnSOD and CuZnSOD immunoreactivity increased dramatically in inflammatory cells within the leukocytic lesion and in the tissue surrounding the lesion.
Conclusions. The findings suggest that the protective role of SOD increases within pulp cells that are undergoing inflammatory stimulation. SOD immunoreactivity may be an early indicator of stress in pulp.
(Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;88:488-95)
The U.S. Environmental Protection Agency Clean Air Status and Trends Network (CASTNET) utilizes an open-face filter pack system to measure concentrations of atmospheric sulfur and nitrogen species. ...Concentration data for nitrogen species measured with filter packsystems sometimes deviate from data collected by other measurement systems used to measure the same species. The nature of these differences suggests that more than one sampling mechanism or atmospheric process is involved. The study presented here examines these differences by intercomparing CASTNET data with data from other studies, examining the results from earlier intercomparison studies, and conducting a field test to investigate the effect of particle size on filter pack measurement systems. Measurements of nitrogen species from the Maryland Aerosol Research and Characterization (MARCH) monitoring site were compared with nitrogen concentrations at three nearby CASTNET sites. Results indicate thatCASTNET measured higher paniculate nitrate (N03 -) and lower gaseous nitric acid (HN03)concentrations Comparisons of NO3 - from 34 collocated CASTNET and Interagency MonitoringofProtected Visual Environments (IMPROVE) sites show that CASTNET NO3 - measurements were typically higher than the corresponding IMPROVE values Also, results from the Lake Michigan Air Director's Consortium Midwest Ammonia Monttonng Project demonstrated NO3 - dissociation on Teflon filters To investigate the effect of particle size, filter pack measurement systems were operated at three CASTNET sites with and without cyclones dunng six 7-day measurement penods from March to August 2006. Results indicate the size-selection cyclones had a significant effect on both NO3 - ana HNO3 concentrations but little effect on sulfate (S04 2-) and ammonium (NH4 + levels NO3 - concentrations sampled with the open-face filters were significantly higher than concentrations measured with a 2.5- m cut point, as were HN03 concentrations. Although limited in spatial and temporal coverage, the fieldstudy showed that the use of an open-face filter pack may allow for the collection of coarse NO3 - particles and for the reaction of HNO3 with metals/ salts on the Teflon filter.
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