42,587 research outputs found
Comparison of Triple Combination Oral Sedation Regimens for Pediatric Dental Treatment
Purpose: Compare the efficacy of two benzodiazepines (diazepam or midazolam) in combination with meperidine and hydroxyzine for pediatric dental sedation. Methods: A randomized, double blind observation study of behaviors and outcomes related to two sedation groups. Frankl and Houpt behavior scores were recorded at three time points: injection time, initiation of treatment and at the end of treatment. Postoperative phone call surveys were conducted within eight hours of discharge to assess sleep, activity, and behavior. Results: A total of 40 sedation subjects were included in the study, of which 20 were treated with diazepam triple Combination (Di+M+H) and 20 with midazolam triple regime (Mi+M+H). Treatment was successful for 45% of cases with midazolam and 70% with diazepam (P value=.20). Houpt sleep scores were significantly higher for diazepam than midazolam at injection (P-value=.0043) and during treatment (P-value=.0152). Although Frankl scores, Houpt move and Houpt cry scores tended to favor diazepam, none were statistically significantly different. More abnormal behavior was reported with midazolam, though not statistically significant (35% vs 6%, P-value=.0854). Postoperative sleep time was longer for midazolam, but not significantly different (median sleep time: 61 vs 45 minutes, P-value=.2071). Conclusion: The diazepam, meperidine, hydroxyzine triple combination sedation regimen shows promising results as a successful alternative to midazolam triple combination. Longer postoperative monitoring may be required with diazepam, but this study has shown postoperative sleep times to be less than previously reported. Larger sample size is needed to determine if the current trend will be maintained
Sonic boom measurement test plan for Space Shuttle STS-4 reentry
Formal documentation for measurement procedures and system specifications, and general information relating to the Space Shuttle STS-4 Sonic Boom Measurement Program are supplied. This test plan is designed to provide information, guidance, and assignment of responsibilities for the acquisition of sonic boom and atmospheric measurements, timing correlation, communications and other necessary supporting tasks. Specifically included are details such as mobile data acquisition station locations, measurement systems calibration levels, predicted sonic boom overpressure levels, overpressure level assignment for each data acquisition station, data recording times on and off, universal coordinated time, and measurement system descriptions
Complex Bifurcation from Real Paths
A new bifurcation phenomenon, called complex bifurcation, is studied. The basic idea is simply that real solution paths of real analytic problems frequently have complex paths bifurcating from them. It is shown that this phenomenon occurs at fold points, at pitchfork bifurcation points, and at isola centers. It is also shown that perturbed bifurcations can yield two disjoint real solution branches that are connected by complex paths bifurcating from the perturbed solution paths. This may be useful in finding new real solutions.
A discussion of how existing codes for computing real solution paths may be trivially modified to compute complex paths is included, and examples of numerically computed complex solution paths for a nonlinear two point boundary value problem, and a problem from fluid mechanics are given
A nonlinear equation for ionic diffusion in a strong binary electrolyte
The problem of the one dimensional electro-diffusion of ions in a strong
binary electrolyte is considered. In such a system the solute dissociates
completely into two species of ions with unlike charges. The mathematical
description consists of a diffusion equation for each species augmented by
transport due to a self consistent electrostatic field determined by the
Poisson equation. This mathematical framework also describes other important
problems in physics such as electron and hole diffusion across semi-conductor
junctions and the diffusion of ions in plasmas. If concentrations do not vary
appreciably over distances of the order of the Debye length, the Poisson
equation can be replaced by the condition of local charge neutrality first
introduced by Planck. It can then be shown that both species diffuse at the
same rate with a common diffusivity that is intermediate between that of the
slow and fast species (ambipolar diffusion). Here we derive a more general
theory by exploiting the ratio of Debye length to a characteristic length scale
as a small asymptotic parameter. It is shown that the concentration of either
species may be described by a nonlinear integro-differential equation which
replaces the classical linear equation for ambipolar diffusion but reduces to
it in the appropriate limit. Through numerical integration of the full set of
equations it is shown that this nonlinear equation provides a better
approximation to the exact solution than the linear equation it replaces.Comment: 4 pages, 1 figur
A comparison of measured and theoretical predictions for STS ascent and entry sonic booms
Sonic boom measurements have been obtained during the flights of STS-1 through 5. During STS-1, 2, and 4, entry sonic boom measurements were obtained and ascent measurements were made on STS-5. The objectives of this measurement program were (1) to define the sonic boom characteristics of the Space Transportation System (STS), (2) provide a realistic assessment of the validity of xisting theoretical prediction techniques, and (3) establish a level of confidence for predicting future STS configuration sonic boom environments. Detail evaluation and reporting of the results of this program are in progress. This paper will address only the significant results, mainly those data obtained during the entry of STS-1 at Edwards Air Force Base (EAFB), and the ascent of STS-5 from Kennedy Space Center (KSC). The theoretical prediction technique employed in this analysis is the so called Thomas Program. This prediction technique is a semi-empirical method that required definition of the near field signatures, detailed trajectory characteristics, and the prevailing meteorological characteristics as an input. This analytical procedure then extrapolates the near field signatures from the flight altitude to an altitude consistent with each measurement location
Mercury Levels in Marine and Estuarine Fishes of Florida 1989–2001. 2nd edition revised
The Florida Fish and Wildlife Conservation Commission’s Florida Marine Research Institute (FWC-FMRI) has
examined total mercury levels in muscle tissue from a variety of economically and ecologically important species
as part of an ongoing study to better understand mercury contamination in marine fishes.The FWC-FMRI Mercury
Program is one of the most comprehensive programs in the United States for monitoring mercury levels in
marine and estuarine fishes. Because mercury, a toxic metallic element, has been shown to bioaccumulate in fish
tissue, humans consuming fish can potentially consume significant levels of mercury.We examined the concentration
of total mercury in 6,806 fish, representing 108 species from 40 families. Species represented all major trophic
groups, from primary consumers to apex predators.The majority of individuals we examined contained low concentrations
of mercury, but concentrations in individual fish varied greatly within and among species. Species
with very low mean or median mercury concentrations tended to be planktivores, detritivores, species that feed
on invertebrates, or species that feed on invertebrates and small fish prey.Apex predators typically had the highest
mercury concentrations. In most species, mercury concentration increased as fish size increased. Sampling
in Florida waters is continuing, and future research relating mercury levels to fish age, feeding ecology, and the
trophic structure of Florida’s marine and estuarine ecosystems will help us better understand concentrations of
this element in marine fishes. (64pp.
Do television and electronic games predict children's psychosocial adjustment? Longitudinal research using the UK Millennium Cohort Study
Background: Screen entertainment for young children has been associated with several aspects of psychosocial adjustment. Most research is from North America and focuses on television. Few longitudinal studies have compared the effects of TV and electronic games, or have investigated gender differences.
Purpose: To explore how time watching TV and playing electronic games at age 5 years each predicts change in psychosocial adjustment in a representative sample of 7 year-olds from the UK.
Methods: Typical daily hours viewing television and playing electronic games at age 5 years were reported by mothers of 11 014 children from the UK Millennium Cohort Study. Conduct problems, emotional symptoms, peer relationship problems, hyperactivity/inattention and prosocial behaviour were reported by mothers using the Strengths and Difficulties Questionnaire. Change in adjustment from age 5 years to 7 years was regressed on screen exposures; adjusting for family characteristics and functioning, and child characteristics.
Results: Watching TV for 3 h or more at 5 years predicted a 0.13 point increase (95% CI 0.03 to 0.24) in conduct problems by 7 years, compared with watching for under an hour, but playing electronic games was not associated with conduct problems. No associations were found between either type of screen time and emotional symptoms, hyperactivity/inattention, peer relationship problems or prosocial behaviour. There was no evidence of gender differences in the effect of screen time.
Conclusions: TV but not electronic games predicted a small increase in conduct problems. Screen time did not predict other aspects of psychosocial adjustment. Further work is required to establish causal mechanisms
The Specification and Influence of Asset Markets
This paper is a chapter in the forthcoming Handbook of International Economics. It surveys the literature on the specification of models of asset markets and the implications of differences in specification for the macroeconomic adjustment process. Builders of portfolio balance models have generally employed "postulated" asset demand functions, rather than deriving these directly from micro foundations. The first major sec-tion of the paper lays out a postulated general specification of asset markets and summarizes the fundamental short-run results of portfolio balance models using a very basic specification of asset markets. Then,rudimentary specifications of a balance of payments equation and goods market equilibrium conditions are supplied, so that the dynamic distribution effects of the trade account under static and rational expectations with both fixed goods prices and flexible goods prices can be analyzed.The second major section of the paper surveys and analyzes microfoundation models of asset demands using stochastic calculus. The microeconomic theory of asset demands implies some but not all of the properties of the basic specification of postulated asset demands at the macrolevel. Since the conclusions of macroeconomic analysis depend crucially on the form of asset demand functions, it is important to continue to explore the implications of micro foundations for macro specification.
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