Showing papers by "Brigham Young University published in 1992"
TL;DR: The relative risk of death increased monotonically with PM10, and the relationship was observed at PM10 levels that were well below the current National Ambient Air Quality Standard of 150 micrograms/m3.
Abstract: The association between daily mortality and respirable particulate pollution (PM10) in Utah County was assessed from April 1985 through December 1989. Poisson regression analysis was used to regress daily death counts on PM10 pollution levels, controlling for variability in the weather. A significant positive association between nonaccidental mortality and PM10 pollution was observed. The strongest association was with 5-d moving average PM10 levels, including the concurrent day and the preceding 4 d. An increase in 5-d moving average PM10 levels, equal to 100 micrograms/m3, was associated with an estimated increase in deaths per day equal to 16%. The association with mortality and PM10 was largest for respiratory disease deaths, next largest for cardiovascular deaths, and smallest for all other deaths. Mean PM10 concentrations during the study period equaled 47 micrograms/m3. The maximum 24-h and 5-d moving average PM10 levels equaled 365 and 297 micrograms/m3, respectively. Relatively low levels of sulfur dioxide, aerosol acidity, and ozone suggested an independent association between mortality and PM10. The relative risk of death increased monotonically with PM10, and the relationship was observed at PM10 levels that were well below the current National Ambient Air Quality Standard of 150 micrograms/m3.
663 citations
TL;DR: It is indicated that both symptomatic and asymptomatic children may suffer acute health effects of respirable particulate pollution, with symptomatic children suffering the most.
Abstract: This study assessed the association between daily changes in respiratory health and respirable particulate pollution (PM10) in Utah Valley during the winter of 1990-1991. During the study period, 24-h PM10 concentrations ranged from 7 to 251 micrograms/m3. Participants included symptomatic and asymptomatic samples of fifth- and sixth-grade students. Relatively small but statistically significant (p less than 0.01) negative associations between peak expiratory flow (PEF) and PM10 were observed for both the symptomatic and asymptomatic samples. The association was strongest for the symptomatic children. Large associations between the incidence of respiratory symptoms, especially cough, and PM10 pollution were also observed for both samples. Again the association was strongest for the symptomatic sample. Immediate and delayed PM10 effects were observed. Respiratory symptoms and PEF changes were more closely associated with 5-day moving-average PM10 levels than with concurrent-day levels. These associations were also observed at PM10 levels below the 24-h standard of 150 micrograms/m3. This study indicates that both symptomatic and asymptomatic children may suffer acute health effects of respirable particulate pollution, with symptomatic children suffering the most.
474 citations
TL;DR: Theoretical expressions for the error in the MUSIC DOA estimates are derived and compared with simulations performed for several representative cases, and an optimally weighted version of MUSIC is proposed for a particular class of array errors.
Abstract: Application of subspace-based algorithms to narrowband direction-of-arrival (DOA) estimation requires that both the array response in all directions of interest and the spatial covariance of the noise must be known. In practice, however, neither of these quantities is known precisely. Depending on the degree to which they deviate from their nominal values, serious performance degradation can result. The performance of the MUSIC algorithm is examined for situations in which the noise covariance and array response are perturbed from their assumed values. Theoretical expressions for the error in the MUSIC DOA estimates are derived and compared with simulations performed for several representative cases, and with the appropriate Cramer-Rao bound. An optimally weighted version of MUSIC is proposed for a particular class of array errors. >
460 citations
TL;DR: The authors argue that repatriation adjustment is sufficiently different from other forms of work adjustment (e.g., domestic relocation and expatriate assignments) to warrant separate theoretical and empirical investigation and propose an initial theoretical framework and set of derived propositions to guide and spark future research on this topic.
Abstract: Although the increased internationalization of business has brought greater scholarly attention to the issue of adjustment to overseas assignments, comparatively little research activity has been paid to the topic of adjustment back to the home country and home office—repatriation adjustment. In this article we argue that repatriation adjustment is sufficiently different from other forms of work adjustment (e.g., domestic relocation and expatriate assignments) to warrant separate theoretical and empirical investigation. To facilitate this, we propose an initial theoretical framework and set of derived propositions to guide and spark future research on this topic.
389 citations
01 Jul 1992
TL;DR: This paper presents a new af algorithm for smoothly blending between two 2-D polygonal shapes based on a physical model wherein one of the shapes is considered to be constructed of wire, and a solution is found whereby the first shape can be bent and/or stretched into the second shape with a minimum amount of work.
Abstract: This paper presents a new afgorithm for smoothly blending between two 2-D polygonal shapes. The algorithm is based on a physical model wherein one of the shapes is considered to be constructed of wire, and a solution is found whereby the first shape can be bent and/or stretched into the second shape with a minimum amount of work. The resulting solution tends to associate regions on the two shapes which look alike. If the two polYgons have m and n vertices respectively, the afgorithm is O(mn). The algorithm avoids local shape inversions in whkh intermediate polygons self-intersect, if such a solution exists.
363 citations
TL;DR: The mitogen-inducible prostaglandin GIH synthase (miPGHS) as mentioned in this paper was identified as a new target of nonsteroidal antiinflammatory drugs (NSAlDs).
Abstract: Prostaglandins have been shown to be involved in many different biological processes, under both normal and pathological conditions. As the key enzyme in the production of prostaglandins and thromboxanes, prostaglandin GIH synthase (PGHS) has been well characterized, including extensive studies as a pharmacological target of the nonsteroidal antiinflammatory drugs (NSAIDs). The gene for this enzyme has been cloned, sequenced, and characterized from sheep, mouse, and human sources. Recently, a new form of this enzyme, a mitogen-inducible PGHS (miPGHS), was identified. Comparisons between these two genes and their protein products have identified significant differences, including structural differences in the proteins and their mRNAs. The genes encoding these two isoenzymes are not coordinately regulated in cultured cells or in tissues. The discovery of this second form of PGHS may change our understanding of how NSAlDs exert their effects. miPGHS is believed to be a new, unique target of NSAIDs which could have a different sensitivity to many of these drugs, compared to the previously identified PGHS. © 1992 Wiley-Liss, Inc.
309 citations
TL;DR: Results indicate that virucidal activity and cytotoxicity may have depended upon the viral envelope and cell membrane, respectively.
Abstract: Garlic (Allium sativum) has been shown to have antiviral activity, but the compounds responsible have not been identified. Using direct pre-infection incubation assays, we determined the in vitro virucidal effects of fresh garlic extract, its polar fraction, and the following garlic associated compounds: diallyl thiosulfinate (allicin), allyl methyl thiosulfinate, methyl allyl thiosulfinate, ajoene, alliin, deoxyalliin, diallyl disulfide, and diallyl trisulfide. Activity was determined against selected viruses including, herpes simplex virus type 1, herpes simplex virus type 2, parainfluenza virus type 3, vaccinia virus, vesicular stomatitis virus, and human rhinovirus type 2. The order for virucidal activity generally was: ajoene > allicin > allyl methyl thiosulfinate > methyl allyl thiosulfinate. Ajoene was found in oil-macerates of garlic but not in fresh garlic extracts. No activity was found for the garlic polar fraction, alliin, deoxyalliin, diallyl disulfide, or diallyl trisulfide. Fresh garlic extract, in which thiosulfinates appeared to be the active components, was virucidal to each virus tested. The predominant thiosulfinate in fresh garlic extract was allicin. Lack of reduction in yields of infectious virus indicated undetectable levels of intracellular antiviral activity for either allicin or fresh garlic extract. Furthermore, concentrations that were virucidal were also toxic to HeLa and Vero cells. Virucidal assay results were not influenced by cytotoxicity since the compounds were diluted below toxic levels prior to assaying for infectious virus. These results indicate that virucidal activity and cytotoxicity may have depended upon the viral envelope and cell membrane, respectively. However, activity against non-enveloped virus may have been due to inhibition of viral adsorption or penetration.(ABSTRACT TRUNCATED AT 250 WORDS)
307 citations
TL;DR: The authors found that international wars can, under specified conditions, have domestically instigated consequences for violent regime change in the political systems of the participants, and that domestic politics play a larger role in national security policy than is generally believed by realist or neorealist theorists.
Abstract: Governments are likely to be held accountable for the success or failure of their foreign policies. Consequently, we claim that international wars can, under specified conditions, have domestically instigated consequences for violent regime change in the political systems of the participants. Drawing upon all international war participation between 1816 and 1975, we seek to answer the question, Do wars lead to violent changes of regime and if so, under what conditions? Three hypotheses set out the expected associations of a nation's initiator or target role in a war, the war outcome, and the costs of the war with domestically instigated violent changes of regime. Direct relationships are found for all three and hold even against possible threats to their validity and robustness. The results suggest that domestic politics play a larger role in national security policy than is generally believed by realist or neorealist theorists.
265 citations
TL;DR: A subspace-fitting formulation of the ESPRIT problem is presented that provides a framework for extending the algorithm to exploit arrays with multiple invariances and the asymptotic distribution of the estimates is obtained.
Abstract: A subspace-fitting formulation of the ESPRIT problem is presented that provides a framework for extending the algorithm to exploit arrays with multiple invariances. In particular, a multiple invariance (MI) ESPRIT algorithm is developed and the asymptotic distribution of the estimates is obtained. Simulations are conducted to verify the analysis and to compare the performance of MI ESPRIT with that of several other approaches. The excellent quality of the MI ESPRIT estimates is explained by recent results which state that, under certain conditions, subspace-fitting methods of this type are asymptotically efficient. >
255 citations
TL;DR: It is suggested that dietary fat intake may play a role in obesity beyond dietary energy content and protein consumption and carbohydrate intake were not significant individual predictors of body-fat percentage when the potential confounding variables were controlled.
211 citations
TL;DR: In this article, the association between school absenteeism and respirable particulate pollution (PM10) in Utah Valley for the six school years of 1985 to 1990 was assessed, and the association was positive, statistically significant (P less than 0.01), and robust to different model specifications.
TL;DR: In this paper, the authors define canonical discriminant functions and canonical variates as linear combinations associated with canonical correlations between two sets of variables, which can be converted to correlations between the variables and the canonical function.
Abstract: Canonical discriminant functions are defined here as linear combinations that separate groups of observations, and canonical variates are defined as linear combinations associated with canonical correlations between two sets of variables. In standardized form, the coefficients in either type of canonical function provide information about the joint contribution of the variables to the canonical function. The standardized coefficients can be converted to correlations between the variables and the canonical function. These correlations generally alter the interpretation of the canonical functions. For canonical discriminant functions, the standardized coefficients are compared with the correlations, with partial t and F tests, and with rotated coefficients. For canonical variates, the discussion includes standardized coefficients, correlations between variables and the function, rotation, and redundancy analysis. Various approaches to interpretation of principal components are compared: the choice ...
TL;DR: The regular variation in the form of mammalian body size distributions among different‐sized islands and continents suggests that environmental conditions, operating through both macro‐ and microevolutionary processes, determine to a large extent the diversification of body sizes within faunas.
Abstract: The diversity of body sizes of organisms has traditionally been explained in terms of microevolutionary processes: natural selection owing to differential fitness of individual organisms, or to macroevolutionary processes: species selection owing to the differential proliferation of phy- logenetic lineages. Data for terrestrial mammals and birds indicate that even on a logarithmic scale frequency distributions of body mass among species are significantly skewed towards larger sizes. We used simulation models to evaluate the extent to which macro- and microevolutionary processes are sufficient to explain these distributions. Simulations of a purely cladogenetic process with no bias in extinction or speciation rates for different body sizes did not produce skewed log body mass distributions. Simulations that included size-biased extinction rates, especially those that incor- porated anagenetic size change within species between speciation and extinction events, regularly produced skewed distributions. We conclude that although cladogenetic processes probably play a significant role in body size evolution, there must also be a significant anagenetic component. The regular variation in the form of mammalian body size distributions among different-sized islands and continents suggests that environmental conditions, operating through both macro- and microevolutionary processes, determine to a large extent the diversification of body sizes within faunas. Macroevolution is not decoupled from microevolution.
TL;DR: The NH4F/MeOH is an economical alternative to TBAF/THF as discussed by the authors, and it can be used to remove silyl ethers from methanol at 60°C.
TL;DR: A new type of protein kinase involved in the early mitogenic response whose activity is transcriptionally and posttranscriptionally regulated is identified, which is highly inducible by serum and phorbol ester.
Abstract: Early-growth-response genes, also known as immediate-early genes, play important roles in regulating cell proliferation. We have identified a new type of early-growth-response gene product, a 77,811-Da putative serine/threonine kinase, which is highly inducible by serum and phorbol ester. mRNA encoding this putative kinase is markedly elevated within 1 h after treatment with mitogen, and this induction is synergistically increased by cycloheximide. Dexamethasone blocks serum induction of the kinase mRNA, as does transformation by v-Ki-ras. The kinase mRNA was detected in mouse brain, lung, and heart. This new putative kinase, which we term Snk, for serum-inducible kinase, showed similarity in its proposed catalytic domain to many other protein kinases; however, no other kinase showed enough sequence similarity with Snk to suggest the existence of a common function. Hence, Snk represents a new type of protein kinase involved in the early mitogenic response whose activity is transcriptionally and posttranscriptionally regulated.
TL;DR: This study determined normal, mean quadriceps angles for college-aged men and women, and to compare Q angles measured in the supine and the standing positions, and calculated the inci dence of an abnormally high Q angle.
Abstract: The purpose of this study was to determine normal, mean quadriceps angles (Q angles) for college-aged men and women, and to compare Q angles measured in the supine and the standing positions. The Q angles of 269 men and 257 women were measured in both positions by use of a specially modified goniometer. The mean Q angle for men was 12.7 degrees in the supine position and 13.6 degrees in the standing position; for women the mean Q angle was 15.8 degrees in the supine position and 17.0 degrees in the standing position. All of these differences were statistically significant. We calculated the incidence of an abnormally high Q angle, and will discuss the implications of our findings.
TL;DR: In this article, a one-dimensional model of countercurrent fixed-bed coal gasification is developed, and results are compared to experimental data from commercial-scale gasifiers, and the steady-state model considers separate gas and solid temperatures, axially variable solid and gas flow rates, variable bed void fraction, coal drying, devolatilization based on chemical functional group composition, oxidation and gasification of char, and partial equilibrium in the gas phase.
Abstract: In this paper, a one-dimensional model of countercurrent fixed-bed coal gasification is developed, and results are compared to experimental data from commercial-scale gasifiers. The steady-state model considers separate gas and solid temperatures, axially variable solid and gas flow rates, variable bed void fraction, coal drying, devolatilization based on chemical functional group composition, oxidation and gasification of char, and partial equilibrium in the gas phase. Generalized treatment of gas-phase chemistry and accounting for variable bed void fraction were necessary to predict realistic axial temperature and pressure profiles in an atmospheric fixed-bed gasifier. Model evaluation includes sensitivity of axial temperature profiles to model options, model parameters and operational parameters. Model predictions agree reasonably well with experimental temperature and pressure profile data for gasification of eight coal types ranging from lignite to bituminous. The relative importance of char oxidation resistances to bulk film diffusion, ash diffusion, and chemical reaction is identified.
11 Oct 1992
TL;DR: An adaptive boundary detection algorithm that uses two-dimensional dynamic programming (DP) is presented and accurately detects the boundaries of low contrast objects, which occur with intravenous injections, as well as those found in noisy, low SNR images.
Abstract: An adaptive boundary detection algorithm that uses two-dimensional dynamic programming (DP) is presented. The algorithm is less constrained than previous one-dimensional dynamic programming algorithms and allows the user to interactively determine the mathematically optimal boundary between a user-selected seed point and any other dynamically selected free point in the image. Interactive movement of the free point by the cursor causes the boundary to behave like a live wire as it adapts to the new minimum cost path between the seed point and the currently selected free point. The algorithm can also be adapted or customized to learn boundary-defining features for a particular class of images. Adaptive 2-D DP performs well on a variety of images. It accurately detects the boundaries of low contrast objects, which occur with intravenous injections, as well as those found in noisy, low SNR images. >
TL;DR: The interval Bezier curve, which, unlike other curve and surface approximation schemes, can transfer a complete description of approximation errors between diverse CAD/CAM systems that impose fundamentally incompatible constraints on their canonical representation schemes, is described.
Abstract: The interval Bezier curve, which, unlike other curve and surface approximation schemes, can transfer a complete description of approximation errors between diverse CAD/CAM systems that impose fundamentally incompatible constraints on their canonical representation schemes, is described. Interval arithmetic, which offers an essentially infallible way to monitor error propagation in numerical algorithms that use floating-point arithmetic is reviewed. Affine maps, the computations of which are key operations in the de Casteljau subdivision and degree-elevation algorithms for Bezier curves, the floating-point error propagation in such computations, approximation by interval polynomials, and approximation by interval Bezier curves are discussed. >
TL;DR: The results suggest that dietary Se exerts its effect on pretranslational Se-GPX gene expression at the level of cytosolic mRNA stabilization, and steady state levels of Se- GPX mRNA were markedly reduced by Se deficiency.
Abstract: The objective of these studies was to determine the step at which dietary selenium (Se) regulates the pre-translational expression of the gene for cytosolic Se-glutathione peroxidase (Se-GPX) in rat liver. Weanling male Sprague-Dawley rats were fed a Torula yeast-based Se-deficient diet, or the same diet supplemented with 0.5 mg/kg as Na2SeO3, for at least 40 d. Livers were excised and divided into three portions for isolation of nuclei, for purification of total RNA and for assay of Se-GPX activity. Nuclei were used in run-on transcription assays and for isolation of total nuclear RNA. Nuclear RNA and total liver RNA were probed with segments from a rat Se-GPX cDNA in Northern blot and slot blot assays. Despite marked differences in Se-GPX activity, there were no significant differences between dietary groups in the transcription rates of the Se-GPX gene. Species hybridizing to Se-GPX were not detected in nuclear RNA. However, steady state levels of Se-GPX mRNA were markedly reduced by Se deficiency. These results suggest that dietary Se exerts its effect on pretranslational Se-GPX gene expression at the level of cytosolic mRNA stabilization.
TL;DR: The theory of invariant manifolds plays an important role in the study of dynamics of nonlinear systems in finite dimensional or infinite dimensional spaces as discussed by the authors, see Pliss [36], for example.
TL;DR: In this article, the second part of a two-part study on the flow structure and heat transfer characteristics of turbulent free-surface liquid jets is presented, where the effect of selected nozzle configurations on the local heat transfer in the stagnation zone is investigated.
Abstract: This is the second of a two-part study on the flow structure and heat transfer characteristics of turbulent, free-surface liquid jets. Part 2 deals with the effect of selected nozzle configurations on the local heat transfer in the stagnation zone. Infrared techniques have been used to characterize the local heat transfer for the four nozzle configurations whose mean and turbulent flow structure was detailed in Part 1. The results show that for identical jet Reynolds numbers, significant differences exist in the magnitudes of the local Nusselt number for the nozzle types studied. Differences of approximately 40 percent were observed. Local heat transfer results reveal that for already turbulent jets, the mean radial velocity gradient appears to be more influential in determining the heat transfer than incremental changes in the level of turbulence (as measured by the radial component of the fluctuations). An empirical correlation of the experimental data supports this conclusion, and reveals that the stagnation Nusselt number is affected independently by the jet Reynolds number and the dimensionless mean radial velocity gradient. 21 refs., 6 figs.
TL;DR: A frank and dramatic sex difference in the distribution of E-concentrating cells within sexually dimorphic regions of the MPOA is demonstrated, and an interaction between galanin and gonadal steroids may be an important means by which cells within theMPOA regulate reproductive function is suggested.
TL;DR: The theoretical structure of a generalized qualitative-response model is presented and its performance is compared to two seminal machine-learning models in two problem domains associated with audit decision making and the results suggest that the generalized quantitative- response model may be a useful alternative for certain problem domains.
Abstract: Machine learning methods are currently the object of considerable study by the artificial intelligence community. Research on machine learning carries implications for decision making in that it seeks computational methods that mimic input-output behaviors found in classes of decision-making examples. At the same time, research in statistics and econometrics has resulted in the development of qualitative-response models that can be applied to the same kind of problems addressed by machine-learning models—particularly those that involve a classification decision. This paper presents the theoretical structure of a generalized qualitative-response model and compares its performance to two seminal machine-learning models in two problem domains associated with audit decision making. The results suggest that the generalized qualitative-response model may be a useful alternative for certain problem domains.
TL;DR: In this paper, the authors used the BWRS equation of state to correlate the PVT and vapor pressure data, and predict enthalpy departures, and compared the measurement results with data from other sources.
TL;DR: In this article, eleven new chiral macrocycles of the pyridino-18-crown-6 type have been prepared, which contain two amides (1,R=benzyl; 5, R=phenyl, two N-methylthionoamide (8, R =phenyl), two amine (3, R-bezyl), or two Nmethylamine (9, R/phenyl) groups incorporated into the macroring.
Abstract: Eleven new chiral macrocycles (1-11, see Figure 1) of the pyridino-18-crown-6 type have been prepared. Nine diazapyridino-crown ligands contain two amide (1,R=benzyl; 5, R=phenyl, two N-methylthionoamide (8, R=phenyl), two amine (3, R=bezyl; 6, R=phenyl), or two N-methylamine (9, R=phenyl) groups incorporated into the macroring
Journal Article•
TL;DR: Students from intact two-parent families had fewer absences and tardies, higher grade point averages, and fewer negative and more positive teacher behavioral ratings than did those from reconstituted and single- parent families.
Abstract: Differences in school behavior and achievement between students from intact, reconstituted, and single-parent families were analyzed. Students from intact two-parent families had fewer absences and tardies, higher grade point averages, and fewer negative and more positive teacher behavioral ratings than did those from reconstituted and single-parent families.
TL;DR: The t-PA level in blood was directly proportional to the plasma epinephrine concentration during both exercise andEpinephrine infusion, suggesting that epine cortisol release during exercise stimulates t- PA secretion.