12,817 research outputs found
The human value of scientific investigations of the origin and evolution of the solar system
The value of space exploration in relation to such earth bound problems as poverty, hunger, overpopulation, pollution, disease, and urban blight is discussed
User community development for the space transportation system/Skylab
The New User Function plan for identifying beneficial uses of space is described. Critical issues such as funding, manpower, and protection of user proprietary rights are discussed along with common barriers which impede the development of a user community. Studies for developing methodologies of identifying new users and uses of the space transportation system are included
Change in Working Length at Different Stages of Instrumentation as a Function of Canal Curvature
The aim of this study was to determine the change in working length (∆WL) before and after coronal flaring and after complete rotary instrumentation as a function of canal curvature. One mesiobuccal or mesiolingual canal from each of 43 extracted molars had coronal standardization and access performed. Once the access was completed, canal preparation was accomplished using Gates Glidden drills for coronal flaring and EndoSequence files for rotary instrumentation. WLs were obtained at 3 time points: pre-instrumentation (unflared), mid-instrumentation (flared) and post-instrumentation (concluded). Measurements were made via direct visualization (DV) and the CanalPro apex locator (EM) in triplicate by a single operator with blinding within the time points. Root curvature was measured using Schneider’s technique. The change in working length was assessed using repeated-measures ANCOVA. The direct visualization measurements were statistically larger than the electronic measurements (paired t-test difference = 0.20 mm, SE = 0.037, P \u3c .0001), although a difference this large may not be clinically important. Overall, a greater change in working length was observed in straight canals than in curved canals, and this trend was more pronounced when measured electronically than via direct visualization, especially in the unflared-concluded time points compared with unflared-flared time points. A greater change in working length was also observed in longer canals than in shorter canals.https://scholarscompass.vcu.edu/gradposters/1032/thumbnail.jp
User benefits and funding strategies
The justification, economic and technological benefits of NASA Space Programs (aside from pure scientific objectives), in improving the quality of life in the United States is discussed and outlined. Specifically, a three-step, systematic method is described for selecting relevant and highly beneficial payloads and instruments for the Interim Upper Stage (IUS) that will be used with the space shuttle until the space tug becomes available. Viable Government and private industry cost-sharing strategies which would maximize the number of IUS payloads, and the benefits obtainable under a limited NASA budget were also determined. Charts are shown which list the payload instruments, and their relevance in contributing to such areas as earth resources management, agriculture, weather forecasting, and many others
Soft core fluid in a quenched matrix of soft core particles: A mobile mixture in a model gel
We present a density-functional study of a binary phase-separating mixture of
soft core particles immersed in a random matrix of quenched soft core particles
of larger size. This is a model for a binary polymer mixture immersed in a
crosslinked rigid polymer network. Using the replica `trick' for
quenched-annealed mixtures we derive an explicit density functional theory that
treats the quenched species on the level of its one-body density distribution.
The relation to a set of effective external potentials acting on the annealed
components is discussed. We relate matrix-induced condensation in bulk to the
behaviour of the mixture around a single large particle. The interfacial
properties of the binary mixture at a surface of the quenched matrix display a
rich interplay between capillary condensation inside the bulk matrix and
wetting phenomena at the matrix surface.Comment: 20 pages, 5 figures. Accepted for Phys. Rev.
MECHANISMS OF DISEASE Acute Oxygen-Sensing Mechanisms
JOSEPH PRIESTLEY, ONE OF THE THREE SCIENTISTS CREDITED WITH THE discovery of oxygen, described the death of mice that were deprived of oxygen. However, he was also well aware of the toxicity of too much oxygen, stating, “For as a candle burns much faster in dephlogisticated [oxygen enriched] than in common air, so we might live out too fast, and the animal powers be too soon exhausted in this pure kind of air. A moralist, at least, may
say, that the air which nature has provided for us is as good as we deserve.”1
In this review we examine the remarkable mechanisms by which different organs detect and respond to acute changes in oxygen tension. Specialized tissues that sense the local oxygen tension include glomus cells of the carotid body, neuroepithelial bodies in the lungs, chromaffin cells of the fetal adrenal medulla, and smooth-muscle cells of the resistance pulmonary arteries,
fetoplacental arteries, systemic arteries, and the ductus arteriosus. Together, they constitute a specialized homeostatic oxygen-sensing system. Although all tissues are sensitive to severe hypoxia, these specialized tissues respond rapidly to moderate changes in oxygen tension within the physiologic range (roughly 40 to 100 mm Hg in an adult and 20 to 40 mm Hg in a fetus)Junta de Andalucí
Validation of an automated enzyme immunoassay for the measurement of serum total thyroxine in cats.
BACKGROUND: Hyperthyroidism is common in older cats, which necessitates frequent screening of serum total thyroxine (TT4) concentrations. Fast, cheap, and reliable methods to measure TT4 in cats are needed. OBJECTIVES: The purpose of the study was the validation of a human TT4 enzyme immunoassay (EIA) for use with feline serum, and derivation of a TT4 reference interval (RI) for cats aged 9 years and older. METHODS: Assay precision, reproducibility, and linearity were evaluated. Interference by hemolysis was also assessed. Method comparison studies between the human EIA and a previously validated radioimmunoassay (RIA) and chemiluminescent-enzyme immunoassay (CEIA) were performed. Healthy cats (> 9 years) were recruited from 3 UK first opinion practices. RESULTS: The human TT4 EIA demonstrated good precision and reproducibility, and adequate linearity. Hemolysis did not significantly alter measured TT4 concentrations until HGB > 8 g/L. Method comparison revealed proportional and constant errors between EIA and RIA/CEIA. The TT4 RI for cats (> 9 years) was calculated as 7.1-45.1 nmol/L (n = 49). CONCLUSIONS: The human TT4 EIA was successfully validated for use with feline serum and offers a rapid, cheap, and reliable method for determination of serum TT4 concentrations in cats.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1111/vcp.1232
Development of methodologies and procedures for identifying STS users and uses
A study was conducted to identify new uses and users of the new Space Transporation System (STS) within the domestic government sector. The study develops a series of analytical techniques and well-defined functions structured as an integrated planning process to assure efficient and meaningful use of the STS. The purpose of the study is to provide NASA with the following functions: (1) to realize efficient and economic use of the STS and other NASA capabilities, (2) to identify new users and uses of the STS, (3) to contribute to organized planning activities for both current and future programs, and (4) to air in analyzing uses of NASA's overall capabilities
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