51,455 research outputs found
Toxicological approach to setting spacecraft maximum allowable concentrations for carbon monoxide
The Spacecraft Maximum Allowable Concentrations (SMACs) are exposure limits for airborne chemicals used by NASA in spacecraft. The aim of these SMACs is to protect the spacecrew against adverse health effects and performance decrements that would interfere with mission objectives. Because of the 1 and 24 hr SMACs are set for contingencies, minor reversible toxic effects that do not affect mission objectives are acceptable. The 7, 30, or 180 day SMACs are aimed at nominal operations, so they are established at levels that would not cause noncarcinogenic toxic effects and more than one case of tumor per 1000 exposed individuals over the background. The process used to set the SMACs for carbon monoxide (CO) is described to illustrate the approach used by NASA. After the toxicological literature on CO was reviewed, the data were summarized and separated into acute, subchronic, and chronic toxicity data. CO's toxicity depends on the formation of carboxyhemoglobin (COHb) in the blood, reducing the blood's oxygen carrying capacity. The initial task was to estimate the COHb levels that would not produce toxic effects in the brain and heart
The Exchange Rate and Interest Rate Differential Relationship: Evidence from Two Financial Crises
This paper examines the contemporaneous and inter-temporal interaction between real exchange rate and real interest rate differential in the two financial crises of 1997 and 2008 by using data from thirteen countries from different world regions. The empirical result shows that negative contemporaneous relationship exists in most countries. In addition, there is little evidence on a systematic inter-temporal relationship between the real interest rate differential and the real exchange rate, and an absence of consistent result in supporting a negative relationship among the thirteen economies. An extremely low change in the conditional correlation between real interest rate differential and real exchange rates can be found in small countries.Contemporaneous, inter-temporal relationship, exchange rate, interest rate differential, financial crisis
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Comparing Outcomes Between the Over-the-Top and All-Epiphyseal Techniques for Physeal-Sparing ACL Reconstruction: A Narrative Review.
A variety of techniques are used for physeal-sparing anterior cruciate ligament (ACL) reconstruction; however, there is no clear consensus on the ideal surgical technique, the frequency of complications, and how to best avoid growth disturbance. The purpose of this study was to compare outcomes and complications between over-the-top and all-epiphyseal ACL reconstruction techniques. The hypothesis was that both physeal-sparing reconstruction techniques are efficacious, with similar risk of growth disturbance and complications. The Embase and PubMed databases were queried for studies on ACL ruptures in the skeletally immature population from 1985 to 2018. Full-text English studies were included (N = 160). Studies reporting rerupture and/or complications after physeal-sparing ACL reconstruction, specifically growth disturbance, were included (n = 10). Studies were separated into 2 groups: an all-epiphyseal group with femoral and tibial fixation points within the epiphysis and a group that had over-the-top femoral and tibial physeal-sparing reconstruction. Complications not specific to the pediatric population were excluded. Demographics, evaluation of skeletal maturity, surgical technique, growth disturbance, rerupture, and patient-reported outcome scores were collected. Data were analyzed in aggregate. The 10 studies included 482 knees. The mean age was 12.0 years; 81% of patients were male; and mean follow-up was 47.7 months. A total of 178 patients underwent all-epiphyseal reconstruction, and 298 had the femoral graft placed over the top. The rerupture rate was 9.0% (16 of 178) in the all-epiphyseal group and 7.2% (14 of 195) in the over-the-top group, of which 82% required revision reconstruction. Six patients had overgrowth in the all-epiphyseal group (mean, 1.8 cm) and 1 patient in the over-the-top group (1.5 cm). Three angular deformities occurred, all of which were in the over-the-top group. Both physeal-sparing ACL reconstruction techniques are successful. Overgrowth was more common in the all-epiphyseal group and angular deformity in the over-the-top group. Rerupture rates were similar between the groups. The authors recommend standardization of skeletal age assessment and baseline lower extremity alignment films
Covariant hamiltonian dynamics
We discuss the covariant formulation of the dynamics of particles with
abelian and non-abelian gauge charges in external fields. Using this
formulation we develop an algorithm for the construction of constants of
motion, which makes use of a generalization of the concept of Killing vectors
and tensors in differential geometry. We apply the formalism to the motion of
classical charges in abelian and non-abelian monopole fieldsComment: 15 pages, no figure
Compositional strategy of the book of Judges: an inductive, rhetorical study
Under historical critical scholarship, the book of Judges is generally
considered a composite work comprising three distinct and essentially unrelated
sections. The central section (2:6-16:31), redacted out of traditional source material,
is believed to be originally a part of the larger Deuteronomistic History that runs
from Deuteronomy to Kings. The prologue (1:1-2:5) and epilogue (17:1-21:25), on
the other hand, are seen as independent compositions that are only artificially
appended onto the central section at a later stage of the book's redactional history.In the last two decades, there has been an increasing tendency for the book to
be read synchronically as an integrated whole. Although synchronic scholars have
drawn attention to the presence of thematic links that connect the different sections
of the book, they have yet to justify their integrative approach by exploring whether
such links are established by design, and if so, whether they imply compositional
unity for the book as a whole in its current canonical form. The present thesis thus
seeks to remedy this lack.In Chapter 1, the present thesis is placed in its historical context as
scholarship on Judges in the past century is critically surveyed. In Chapters 2-4,
rhetorical links between the prologue and the epilogue, the epilogue and central
section, and the prologue and central sections are respectively examined in detail. As
the evidence seems to suggest that such links are established by conscious design, the
implication is that at the compositional level, a closer relationship than has been
recognised thus far may indeed exist between the three sections.Recognising that any claim of compositional unity for Judges would
inevitably have to answer questions regarding apparent discrepancies in viewpoints
within the book, in Chapter 5, the issue of kingship, concerning which critical
scholars have discerned divergent voices within the book, is explored. Specifically,
it is argued that the "king" referred to in the allegedly pro-monarchic refrain cannot
be a reference to the Israelite monarchy to come, but is more likely a reference to
YHWH's kingship over His people. Such an understanding would therefore
eliminate the problem of divergent viewpoints within the bookIn the final chapter, the various observations and conclusions drawn in
previous chapters are brought together, and a case is put forth that the person
responsible for the selection and arrangement of the material in the central section
must have been the very same person who composed the prologue and epilogue of
Judges. This means that the current canonical form of Judges may indeed be a
unified piece of composition that can justifiably be read as an integrative whole.
Moreover, based on the rhetorical concerns discernible through the various links, it is
also possible to identify the implied rhetorical agenda of the book as a call for the rerecognition
of the kingly authority of YHWH. This would constitute an implied
solution to the progressive deterioration witnessed throughout the book, both at the
national and leadership level
Universal Behavior in Large-scale Aggregation of Independent Noisy Observations
Aggregation of noisy observations involves a difficult tradeoff between
observation quality, which can be increased by increasing the number of
observations, and aggregation quality which decreases if the number of
observations is too large. We clarify this behavior for a protypical system in
which arbitrarily large numbers of observations exceeding the system capacity
can be aggregated using lossy data compression. We show the existence of a
scaling relation between the collective error and the system capacity, and show
that large scale lossy aggregation can outperform lossless aggregation above a
critical level of observation noise. Further, we show that universal results
for scaling and critical value of noise which are independent of system
capacity can be obtained by considering asymptotic behavior when the system
capacity increases toward infinity.Comment: 10 pages, 3 figure
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