66 research outputs found
Health and Household Air Pollution from Solid Fuel Use: The Need for Improved Exposure Assessment
Background: Nearly 3 billion people worldwide rely on solid fuel combustion to meet basic household energy needs. The resulting exposure to air pollution causes an estimated 4.5% of the global burden of disease. Large variability and a lack of resources for research and development have resulted in highly uncertain exposure estimates.
Objective: We sought to identify research priorities for exposure assessment that will more accurately and precisely define exposure–response relationships of household air pollution necessary to inform future cleaner-burning cookstove dissemination programs.
Data Sources: As part of an international workshop in May 2011, an expert group characterized the state of the science and developed recommendations for exposure assessment of household air pollution.
Synthesis: The following priority research areas were identified to explain variability and reduce uncertainty of household air pollution exposure measurements: improved characterization of spatial and temporal variability for studies examining both short- and long-term health effects; development and validation of measurement technology and approaches to conduct complex exposure assessments in resource-limited settings with a large range of pollutant concentrations; and development and validation of biomarkers for estimating dose. Addressing these priority research areas, which will inherently require an increased allocation of resources for cookstove research, will lead to better characterization of exposure–response relationships.
Conclusions: Although the type and extent of exposure assessment will necessarily depend on the goal and design of the cookstove study, without improved understanding of exposure–response relationships, the level of air pollution reduction necessary to meet the health targets of cookstove interventions will remain uncertain
Blood pressure and endothelial function in healthy, pregnant women after acute and daily consumption of flavanol-rich chocolate: a pilot, randomized controlled trial
Thoracic index in the Negro
TypescriptM.A. University of Missouri 1905The following investigations were undertaken in order to determine the thoracic index, (i. e. the ratio of the antero-posterior to the transverse diameter) according to age and sex in the Negro, by means of a series of measurements made upon the living body. In addition, a number of observations were made to determine the character of the thoracic index in the embryo and foetus, (independent of race).Includes bibliographical reference
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Microbial Dynamics and Energetics in Microbially Induced Calcite Precipitation for Geotechnical Ground Improvement
Microbially induced calcite precipitation (MICP) is a ground improvement approach that has advanced rapidly over the past two decades given its potential application in geotechnical engineering systems. In this process ureolytic MICP uses urea-hydrolyzing bacteria to precipitate calcium carbonate in the soil matrix to rapidly change improve the mechanical properties of the soil while purporting to have fewer environmental impacts than many traditional cement-based ground improvement techniques. The engineering performance gains of the process is relatively well-studied, but far less has been published about the biological processes and phenomena that enable MICP.Ureolytic MICP has two main approaches: bioaugmentation, or the inoculation of the soil with, typically, the Gram-positive bacterium Sporosarcina pasteurii; and biostimulation, which uses sequential selective enrichments within the soil to generate a sufficiently ureolytic community. Presented herein is a conceptual synthesis of both methods from a microbiological perspective, with particular focus given to the current understanding of the factors that govern the effectiveness of biostimulation. A model for enrichment is proposed that includes the negative selectivity imposed by the synergistic effects of ammonia and elevated pH to suppress competitive growth as well as the positive selection based on energy-derived from the hydrolysis of urea to promote the targeted growth of important MICP species.
Biostimulated and bioaugmented MICP approaches yielded comparable precipitation in a 1.7 m diameter tank comparison, but the augmented S. pasteurii strain was seemingly outcompeted by native soil bacteria such that it was unable to be recovered one week after inoculation. Instead, other Sporosarcina species were cultured from both tanks with S. soli being the most abundant single species. These isolates manifested a wide range of whole-cell urease kinetics, but still demonstrated ureolytic rates that produce carbonate alkalinity as much as 100 times more rapidly than proposed biocementation processes dependent upon other types of bacterial energy metabolism.
The two methods were again compared using molecular approaches in small, less heterogeneous soil columns. Consistent with what was seen at the large-scale, the calcium carbonate precipitation was comparable between both methods. Moreover, the bioaugmented S. pasteurii strain, which was detected three days following the inoculation, was unable to be detected after seven, again an indication of its poor ability to compete with the native bacteria. The microbial communities in both columns were populated by Sporosarcina species (principally S. koreensis, S. luteola, S. ginsengisoli, S. soli, S. saromensis, S. pasteurii, and S. newyorkensis), reinforcing the importance of this genus for ureolytic MICP, though Lysinibacillus sphaericus and Lysinibacillus fusiformis came to prominence in the latter half of the treatments. The emergence of Lysinibacillus was not associated with a particular decrease in ureolytic activity. Instead, ureolytic activity continued to accrete, such that even generous estimates of ureolytic kinetics, when combined with measured suspended cell densities, explained only 10% of the observed ureolytic activity, implying analyses of the pore fluid neglect a substantial portion of the microbial participants.
Pure culture studies of the S. pasteurii strain typically used for MICP as well as MICP isolates demonstrate that some members of the genus Sporosarcina are able to generate energy from urea hydrolysis and the chemiosmotic gradients that result. These isolates appear to have the ability, upon repeated transfer of small inocula to fresh media, to indefinitely sustain urea-dependent multiplication under rigorously anoxic conditions. Furthermore, the energy yield of this metabolism is substantial, allowing the anaerobic growth and maintenance of cultures of 107-108 cfu/mL density, with an S. soli isolate having the potential to grow to even higher titers. The geotechnical importance of anaerobic, urea-fueled growth in this genus is emphasized by the demonstration that biostimulated soil columns experience anoxia for 80-90% of a typical treatment, an interval in which alternative modes of bacterial energy generation are ineffective. Modeling based on biomass yield did not exclude cytoplasmic alkalinization as a potential mechanism for energy generation, but ammonium transporters are predicted to be present to boost the efficiency in at least some species. The ability to grow with energy derived from urea could be an essential element to the function of biostimulation but may even play a more common role in urogenital pathogenesis
Foreword
During the past several years the NATURAL LAW FORUM has achieved a distinctive and honored place among legal and philosophical journals. This has primarily been due to the diligent efforts of the board of editors under the leadership first of Professor Anton-Hermann Chroust and more recently Professor John Noonan as editors and of Professor Andrew T. Smithberger as managing editor. This degree of excellence was continued with the first issue of the FORUM under its new name of THE AMERICAN JOURNAL OF JURISPRUDENCE.
With the resignation of Professor Noonan the Board of Editors has appointed us co-editors of THE AMERICAN JOURNAL OF JURISPRUDENCE. We are privileged and pleased to accept this appointment. It is our intention and hope that we will continue the successful record established by the past editors of this journal. THE AMERICAN JOURNAL OF JURISPRUDENCE, as Professor Noonan noted in the 1969 issue, will be continuous in policy and spirit with the NATURAL LAW FORUM. The NATURAL LAW FORUM has been dedicated to a critical examination of the significance of natural law for our times
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