655 research outputs found
Environmental effects of James River sewage treatment plant outfall construction
In the spring of 1975 the Institute began a program to determine whether significant environmental changes would occur in the area of the new James River Plant outfall that might be related to its construction and/or initial operation. Parameters measured in the study were benthic animal and oyster populations, coliform levels and chlorine residuals. The primary emphasis of the study centered on the estimation of the impact of the construction activity on shellfish beds in the area. The results of the investigation are presented in three segments, the first dealing with shellfish populations, the second with other benthic animals and the third with coliforms and chlorine.
Section I. Environmental Effects of James River Sewage Treatment Plant Outfall Construction on Oyster Beds in the James River by Dexter S. Haven and Paul C . Kendall
Section II. Environmental Effects of the James River Sewage Treatment Plant Outfall Construction: Soft Bottom Macrobenthos by Robert J. Diaz and Donald F. Boesch
Section III. Water Quality in the Vicinity of James River Sewage Treatment Plant Outfall by Michael E. Bende
The Onfp Class in the Magellanic Clouds
The Onfp class of rotationally broadened, hot spectra was defined some time
ago in the Galaxy, where its membership to date numbers only eight. The
principal defining characteristic is a broad, centrally reversed He II
4686 emission profile; other emission and absorption lines are also
rotationally broadened. Recent surveys in the Magellanic Clouds (MCs) have
brought the class membership there, including some related spectra, to 28. We
present a survey of the spectral morphology and rotational velocities, as a
first step toward elucidating the nature of this class. Evolved, rapidly
rotating hot stars are not expected theoretically, because the stellar winds
should brake the rotation. Luminosity classification of these spectra is not
possible, because the principal criterion (He II 4686) is peculiar;
however, the MCs provide reliable absolute magnitudes, which show that they
span the entire range from dwarfs to supergiants. The Onfp line-broadening
distribution is distinct and shifted toward larger values from those of normal
O dwarfs and supergiants with >99.99% confidence. All cases with multiple
observations show line-profile variations, which even remove some objects from
the class temporarily. Some of them are spectroscopic binaries; it is possible
that the peculiar profiles may have multiple causes among different objects.
The origin and future of these stars are intriguing; for instance, they could
be stellar mergers and/or gamma-ray-burst progenitors.Comment: 27 pages, 8 figures, 2 tables; AJ accepte
Recommended from our members
Alcohol, Hospital Discharge, and Socioeconomic Risk Factors for Default from Multidrug Resistant Tuberculosis Treatment in Rural South Africa: A Retrospective Cohort Study
Background: Default from multidrug-resistant tuberculosis (MDR-TB) treatment remains a major barrier to cure and epidemic control. We sought to identify patient risk factors for default from MDR-TB treatment and high-risk time periods for default in relation to hospitalization and transition to outpatient care. Methods: We retrospectively analyzed a cohort of 225 patients who initiated MDR-TB treatment between 2007 through 2010 at a rural TB hospital in the Western Cape Province, South Africa. Results: Fifty percent of patients were cured or completed treatment, 27% defaulted, 14% died, 4% failed treatment, and 5% transferred out. Recent alcohol use was common (63% of patients). In multivariable proportional hazards regression, older age (hazard ratio [HR]= 0.97 [95% confidence interval 0.94-0.99] per year of greater age), formal housing (HR=0.38 [0.19-0.78]), and steady employment (HR=0.41 [0.19-0.90]) were associated with decreased risk of default, while recent alcohol use (HR=2.1 [1.1-4.0]), recent drug use (HR=2.0 [1.0-3.6]), and Coloured (mixed ancestry) ethnicity (HR=2.3 [1.1-5.0]) were associated with increased risk of default (P<0.05). Defaults occurred throughout the first 18 months of the two-year treatment course but were especially frequent among alcohol users after discharge from the initial four-to-five-month in-hospital phase of treatment, with the highest default rates occurring among alcohol users within two months of discharge. Default rates during the first two months after discharge were also elevated for patients who received care from mobile clinics. Conclusions: Among patients who were not cured or did not complete MDR-TB treatment, the majority defaulted from treatment. Younger, economically-unstable patients and alcohol and drug users were particularly at risk. For alcohol users as well as mobile-clinic patients, the early outpatient treatment phase is a high-risk period for default that could be targeted in efforts to increase treatment completion rates
Maximum likelihood analysis of systematic errors in interferometric observations of the cosmic microwave background
We investigate the impact of instrumental systematic errors in
interferometric measurements of the cosmic microwave background (CMB)
temperature and polarization power spectra. We simulate interferometric CMB
observations to generate mock visibilities and estimate power spectra using the
statistically optimal maximum likelihood technique. We define a quadratic error
measure to determine allowable levels of systematic error that do not induce
power spectrum errors beyond a given tolerance. As an example, in this study we
focus on differential pointing errors. The effects of other systematics can be
simulated by this pipeline in a straightforward manner. We find that, in order
to accurately recover the underlying B-modes for r=0.01 at 28<l<384,
Gaussian-distributed pointing errors must be controlled to 0.7^\circ rms for an
interferometer with an antenna configuration similar to QUBIC, in agreement
with analytical estimates. Only the statistical uncertainty for 28<l<88 would
be changed at ~10% level. With the same instrumental configuration, we find the
pointing errors would slightly bias the 2-\sigma upper limit of the
tensor-to-scalar ratio r by ~10%. We also show that the impact of pointing
errors on the TB and EB measurements is negligibly small.Comment: 10 pages, 4 figures, accepted for publication in ApJS. Includes
improvements in clarity of presentation and Fig.4 added, in response to
refere
Incidence of propofol-related infusion syndrome in critically ill adults: a prospective, multicenter study
Age determination of the Lower Watrous red-beds of the Williston Basin, Saskatchewan, Canada
The age of the Lower Watrous red-beds, which host hydrocarbon reserves in the Williston Basin, along with equivalent formations in Manitoba (Lower Amaranth Formation) and the U.S.A. (Saude Member of the Spearfish Formation) is a controversial subject, with this succession being assigned ages from Mississippian to Middle Jurassic; a timespan of over 150 million years. Using existing published data and new geochemical analyses on the Watrous Formation, we present a Triassic age for the Lower Watrous red-beds.
An established well-log correlation dates the Saude Member red-beds as post-Middle Permian. Some previously published geochemical and palynological data from equivalent formations are in agreement with this age, but several palaeomagnetic studies have provided conflicting results, with age assignments of Mississippian through to Late Triassic. Our study demonstrates the equivalency of the Saude Member and Lower Watrous red-beds by extending the well-log correlation north, from the U.S.A. into Saskatchewan. The combined new strontium, sulfur and oxygen isotopic analyses of isolated Lower Watrous anhydrite nodules are most consistent with an Early or Late Triassic age, which is in agreement with the well-log correlation and potassium-argon dating of a pre-red-beds impact structure. A Pennsylvanian age for the Lower Watrous red-beds is considered most unlikely
Social research on neglected diseases of poverty: Continuing and emerging themes
Copyright: © 2009 Manderson et al.Neglected tropical diseases (NTDs) exist and persist for social and economic reasons that enable the vectors and pathogens to take advantage of changes in the behavioral and physical environment. Persistent poverty at household, community, and national levels, and inequalities within and between sectors, contribute to the perpetuation and re-emergence of NTDs. Changes in production and habitat affect the physical environment, so that agricultural development, mining and forestry, rapid industrialization, and urbanization all result in changes in human uses of the environment, exposure to vectors, and vulnerability to infection. Concurrently, political instability and lack of resources limit the capacity of governments to manage environments, control disease transmission, and ensure an effective health system. Social, cultural, economic, and political factors interact and influence government capacity and individual willingness to reduce the risks of infection and transmission, and to recognize and treat disease. Understanding the dynamic interaction of diverse factors in varying contexts is a complex task, yet critical for successful health promotion, disease prevention, and disease control. Many of the research techniques and tools needed for this purpose are available in the applied social sciences. In this article we use this term broadly, and so include behavioral, population and economic social sciences, social and cultural epidemiology, and the multiple disciplines of public health, health services, and health policy and planning. These latter fields, informed by foundational social science theory and methods, include health promotion, health communication, and heath education
Mapping of Mycobacterium tuberculosis Complex Genetic Diversity Profiles in Tanzania and Other African Countries
The aim of this study was to assess and characterize Mycobacterium tuberculosis complex (MTBC) genotypic diversity in Tanzania, as well as in neighbouring East and other several African countries. We used spoligotyping to identify a total of 293 M. tuberculosis clinical isolates (one isolate per patient) collected in the Bunda, Dar es Salaam, Ngorongoro and Serengeti areas in Tanzania. The results were compared with results in the SITVIT2 international database of the Pasteur Institute of Guadeloupe. Genotyping and phylogeographical analyses highlighted the predominance of the CAS, T, EAI, and LAM MTBC lineages in Tanzania. The three most frequent Spoligotype International Types (SITs) were: SIT21/CAS1-Kili (n = 76; 25.94%), SIT59/LAM11-ZWE (n = 22; 7.51%), and SIT126/EAI5 tentatively reclassified as EAI3-TZA (n = 18; 6.14%). Furthermore, three SITs were newly created in this study (SIT4056/EAI5 n = 2, SIT4057/T1 n = 1, and SIT4058/EAI5 n = 1). We noted that the East-African-Indian (EAI) lineage was more predominant in Bunda, the Manu lineage was more common among strains isolated in Ngorongoro, and the Central-Asian (CAS) lineage was more predominant in Dar es Salaam (p-value<0.0001). No statistically significant differences were noted when comparing HIV status of patients vs. major lineages (p-value = 0.103). However, when grouping lineages as Principal Genetic Groups (PGG), we noticed that PGG2/3 group (Haarlem, LAM, S, T, and X) was more associated with HIV-positive patients as compared to PGG1 group (Beijing, CAS, EAI, and Manu) (p-value = 0.03). This study provided mapping of MTBC genetic diversity in Tanzania (containing information on isolates from different cities) and neighbouring East African and other several African countries highlighting differences as regards to MTBC genotypic distribution between Tanzania and other African countries. This work also allowed underlining of spoligotyping patterns tentatively grouped within the newly designated EAI3-TZA lineage (remarkable by absence of spacers 2 and 3, and represented by SIT126) which seems to be specific to Tanzania. However, further genotyping information would be needed to confirm this specificity
Electron affinities of the first- and second- row atoms: benchmark ab initio and density functional calculations
A benchmark ab initio and density functional (DFT) study has been carried out
on the electron affinities of the first- and second-row atoms. The ab initio
study involves basis sets of and quality, extrapolations to
the 1-particle basis set limit, and a combination of the CCSD(T), CCSDT, and
full CI electron correlation methods. Scalar relativistic and spin-orbit
coupling effects were taken into account. On average, the best ab initio
results agree to better than 0.001 eV with the most recent experimental
results. Correcting for imperfections in the CCSD(T) method improves the mean
absolute error by an order of magnitude, while for accurate results on the
second-row atoms inclusion of relativistic corrections is essential. The latter
are significantly overestimated at the SCF level; for accurate spin-orbit
splitting constants of second-row atoms inclusion of (2s,2p) correlation is
essential. In the DFT calculations it is found that results for the 1st-row
atoms are very sensitive to the exchange functional, while those for second-row
atoms are rather more sensitive to the correlation functional. While the LYP
correlation functional works best for first-row atoms, its PW91 counterpart
appears to be preferable for second-row atoms. Among ``pure DFT'' (nonhybrid)
functionals, G96PW91 (Gill 1996 exchange combined with Perdew-Wang 1991
correlation) puts in the best overall performance. The best results overall are
obtained with the 1-parameter hybrid modified Perdew-Wang (mPW1) exchange
functionals of Adamo and Barone [J. Chem. Phys. {\bf 108}, 664 (1998)], with
mPW1LYP yielding the best results for first-row, and mPW1PW91 for second-row
atoms. Indications exist that a hybrid of the type mPW1LYP +
mPW1PW91 yields better results than either of the constituent functionals.Comment: Phys. Rev. A, in press (revised version, review of issues concerning
DFT and electron affinities added
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