Showing papers by "Brigham Young University published in 1995"

The comet assay: a comprehensive review

Abstract: The comet assay is a sensitive and rapid method for DNA strand break detection in individual cells. Its use has increased significantly in the past few years. This paper is a review of the studies published to date that have made use of the comet assay. The principles of strand break detection using both the alkaline and neutral versions of the technique are discussed, and a basic methodology with currently used variations is presented. Applications in different fields are reviewed and possible future directions of the technique are briefly explored.

Authoritative, authoritarian, and permissive parenting practices: development of a new measure

Abstract: A 133-item parenting questionnaire was completed by 1251 parents of preschool and school-age children. Items in this measure were reduced using principal axes factor analyses followed by varimax ro...

Intelligent scissors for image composition

Abstract: We present a new, interactive tool called Intelligent Scissors which we use for image segmentation and composition. Fully automated segmentation is an unsolved problem, while manual tracing is inaccurate and laboriously unacceptable. However, Intelligent Scissors allow objects within digital images to be extracted quickly and accurately using simple gesture motions with a mouse. When the gestured mouse position comes in proximity to an object edge, a live-wire boundary “snaps” to, and wraps around the object of interest. Live-wire boundary detection formulates discrete dynamic programming (DP) as a two-dimensional graph searching problem. DP provides mathematically optimal boundaries while greatly reducing sensitivity to local noise or other intervening structures. Robustness is further enhanced with on-the-fly training which causes the boundary to adhere to the specific type of edge currently being followed, rather than simply the strongest edge in the neighborhood. Boundary cooling automatically freezes unchanging segments and automates input of additional seed points. Cooling also allows the user to be much more free with the gesture path, thereby increasing the efficiency and finesse with which boundaries can be extracted. Extracted objects can be scaled, rotated, and composited using live-wire masks and spatial frequency equivalencing. Frequency equivalencing is performed by applying a Butterworth filter which matches the lowest frequency spectra to all other image components. Intelligent Scissors allow creation of convincing compositions from existing images while dramatically increasing the speed and precision with which objects can be extracted.

Review of epidemiological evidence of health effects of particulate air pollution

Abstract: This article summarizes epidemiological evidence of health effects of particulate air pollution. Acute exposure to elevated levels of particulate air pollution has been associated with increased cardiopulmonary mortality, increased hospitalization for respiratory disease, exacerbation of asthma, increased incidence and duration of respiratory symptoms, declines in lung function, and restricted activity. Small deficits in lung function, higher risk of chronic respiratory disease and symptoms, and increased mortality have also been associated with chronic exposure to respirable particulate air pollution. Health effects have been observed at levels common to many U.S. cites and at levels below current US. National Ambient Air Quality Standards. Although the biological mechanisms involved are poorly understood, recent epidemiological evidence supports the hypothesis that respirable particulate air pollution is an important risk factor for respiratory disease and cardiopulmonary mortality.

A revision of the dyadic adjustment scale for use with distressed and nondistressed couples: construct hierarchy and multidimensional scales

Abstract: The existing research on the Dyadic Adjustment Scale (DAS) indicated that there were problems with some of the subscales and individual items. This study was designed to improve the instrument by following the standards of construct hierarchy. Through previous research and the analyses in this study, the subscales were found to contain some items that were homogeneous and others that were more heterogeneous. This problem was corrected by selecting out items that were homogeneous; 7jirst-order scales were created which were combined to create the 3 second-order concepts of consensus, satisfaction, and cohesion. With a sample of distressed and nondistressed couples, a series of confirmatory factor analyses was conducted. The factor analyses provided evidence for the construct validity of the new structure of the Revised DAS (RDAS) with the distressed, nondistressed, and total samples of this study, as well as with the sample from Spanier and ThompsonS (I 982) study. Additional analyses correlating the RDAS with another popular

The problem of unobservables in strategic management research

Abstract: In this paper we argue that unobservable constructs lie at the core of a number of influential theories used in the strategic marmgement literature—including agency theory, transaction cost theory, and the resource-based view of the firm. The debate over how best to deal with the problem of unobservables has raged in the philosophy of science literature for the best part of the current century. On the one hand, there are the positivists, who believe that theories containing unobservable constructs are only useful as tools for making predictions. According to positivists, such theories do not inform us about the deep structure of reality. On the other hand, there are the realists, who believe that our theories can give us knowledge about unobservables. Herein we review this debate, we argue for adopting a realist position, and we draw out the implications for strategic management research.

Health effects of particulate air pollution: time for reassessment?

Abstract: Numerous studies have observed health effects of particulate air pollution. Compared to early studies that focused on severe air pollution episodes, recent studies are more relevant to understandin...

Toward a theory of entrepreneurial careers

Abstract: Parallel streams of theory and research regarding entrepreneurship and careers has led to a dearth of comprehensive theories regarding the careers of entrepreneurs. This article describes four core...

Single-Phase Liquid Jet Impingement Heat Transfer

Abstract: Publisher Summary Impinging liquid jets have been demonstrated to be an effective means of providing high heat or mass transfer rates in industrial transport processes. This chapter summarizes the available analytical and experimental work in the area with the objective of correlating the research findings. Significant progress has been made in understanding the fundamentals of heat, mass, and momentum transport in these systems. This chapter suggests that, there is considerable need for further research in liquid jet array applications, both in submerged and free-surface jet configurations. Cross-flow effects in these systems, which have been quite well characterized for submerged jets, have received only superficial treatment for free-surface jets. The physical phenomena are highly complex, requiring careful experimental investigation.

A dynamic instruction set computer

Abstract: A dynamic instruction set computer (DISC) has been developed that supports demand-driven modification of its instruction set. Implemented with partially reconfigurable FPGAs, DISC treats instructions as removable modules paged in and out through partial reconfiguration as demanded by the executing program. Instructions occupy FPGA resources only when needed and FPGA resources can be reused to implement an arbitrary number of performance-enhancing application-specific instructions. DISC further enhances the functional density of FPGAs by physically relocating instruction modules to available FPGA space.

Acculturative Stress The Experience of the Hispanic Immigrant

Abstract: Acculturative stress is the psychological impact of adaptation to a new culture. For Hispanics who come to the United States, there are a number of significant stressors that are likely to be pervasive, intense, and lifelong. Counselors need to learn the reality of the Hispanic immigrants and help them adapt to these stressors. This article defines and describes these aspects of acculturative stress.

A Survey of Capstone Engineering Courses in North America

Abstract: Senior project or Capstone-type courses have existed at engineering schools for many years. Capstone courses provide student engineers the opportunity to solve real-world engineering projects, and have been highly regarded as important learning activities. A survey of Capstone courses in engineering departments throughout North America was conducted in order to understand current practices in Capstone education. This study was conducted for presentation at the 1994 Advances in Capstone Education Conference, held at Brigham Young University, which brought together engineering educators interested in improving Capstone experiences. This conference was sponsored by ASEE, ASME, SME, and NSF. Response to the study was very high, with 360 departments from 173 schools responding to the survey. Survey results were categorized into five major areas of interest: Profile of the Respondents, Course Description Information, Faculty Involvement in Capstone Education, Project Information, and Industrial Involvement in Capstone Education. Graphs provide the results of responses to survey questions.

Rate of temperature increase in human muscle during 1 MHz and 3 MHz continuous ultrasound.

Abstract: To achieve the thermal effects of ultrasound, the tissue temperature must be raised from 1 to ≥4°C, depending on the desired outcome of the treatment. In the past 25 years, there have been no in vivo studies that have measured rate of change in temperature during 1-MHz ultrasound treatments, and none have ever been performed with the 3-MHz frequency. Thus, we are left to pure speculation regarding how long to administer an ultrasound treatment. We performed this study to plot the rate of temperature increase during ultrasound treatments delivered at various intensities and frequencies. We inserted two 23-gauge thermistors into each subjects' medial triceps surae at the following depths: 1 MHz at depths of 2.5 and 5.0 cm (12 subjects) and 3 MHz at depths of .8 and 1.6 cm (12 subjects). Each subject received a total of four 10-minute treatments, one each at .5, 1.0, 1.5, and 2.0 W/cn2, and temperature was measured every 30 seconds. No significant difference was found in the rate of heating at the two depths...

Foreign Policy Analysis Yesterday, Today, and Tomorrow

Abstract: The catalytic shock of the end of the Cold War and the apparent inability of international relations (IR) theory to predict this profound change have raised questions about how we should go about understanding the world of today. Our inherited tools and ways of describing the international arena seem not to work as well as they once did. To explain and predict the behavior of the human collectivities comprising nation-states, IR theory requires a theory of human political choice. Within the study of IR, foreign policy analysis (FPA) has begun to develop such a theoretical perspective. From its inception, FPA has involved the examination of how foreign policy decisions are made and has assumed that human beings, acting individually or in collectivities, are the source of much behavior and most change in international politics. This article reviews the field of foreign policy analysis, examining its research core and its evolution to date. The overview also looks forward, pointing to the future, not only of FPA itself, but to the implications that future developments in FPA may have for the study of international relations.

Hearing aid device incorporating signal processing techniques

Abstract: A hearing compensation system for the hearing impaired comprises a plurality of bandpass filters having an input connected to an input transducer and each bandpass filter having an output connected to the input of one of a plurality of multiplicative AGC circuits whose outputs are summed together and connected to the input of an output transducer. The multiplicative AGC circuits attenuate acoustic signals having a constant background level without the loss of speech intelligibility. The identification of the background noise portion of the acoustic signal is made by the constancy of the envelope of the input signal in each of the several frequency bands. The background noise that will be suppressed includes multi-talker speech babble, fan noise, feedback whistle, fluorescent light hum, and white noise.

Implicitization using moving curves and surfaces

Abstract: This paper presents a radically new approach to the century old problem of computing the implicit equation of a parametric surface. For surfaces without base points, the new method expresses the implicit equation in a determinant which is one fourth the size of the conventional expression based on Dixon’s resultant. If base points do exist, previous implicitization methods either fail or become much more complicated, while the new method actually simplifies.

The Spectral Line-Based Weighted-Sum-of-Gray-Gases Model in Nonisothermal Nonhomogeneous Media

Abstract: An approach is developed to extend the previously developed spectral-line weighted-sum-of-gray-gases (SLW) model to nonisothermal, nonhomogeneous media. The distinguishing feature of the SLW gas property model is that it has been developed for use in arbitrary solution methods of the radiative transfer equation (RTE). A spatial dependence of the gray gas absorption cross sections on local temperature, pressure, and mole fraction is introduced through the absorption-line blackbody distribution function. Incorporating this spatial dependence results in significant improvement over the use of spatially uniform gray gas absorption cross sections in comparisons with line-by-line benchmarks. 16 refs., 7 figs.

Dynamics of aluminum combustion

Abstract: A study has been performed modeling both steady and unsteady combustion of aluminum. Law's steadystate aluminum combustion model has been expanded to include the effects of multiple oxidizers and their products, oxide accumulation on the surface of the burning aluminum particle, and convection. Both transport and thermodynamic properties are calculated internally for varying temperatures, relaxing the normal assumption of unity Lewis number. The aluminum combustion model has been compared to experimental data from burners, laser-ignited particles, and propellant under a variety of conditions, showing a reasonable degree of agreement. Calculations with the model show that O2 is a stronger oxidizer than H2O, which in turn is stronger than CO2. The aluminum combustion model was incorporated into a computer model for predicting acoustic effects in a Rijke burner. Calculations have shown that a significant part of the increase in acousticgrowth due to the addition of aluminum is due strictly to the change in the gas temperature profile. The change in temperature profile apparently causes the location of the velocity antinode to shift relative to the Rijke burner flame and thereby cause an increase in the flame response. The acoustic model agrees reasonably well with available acoustic growth rates for data where aluminum particles have been added to a propane Rijke burner. Nomenclature ak = sum of the mole fractions of the oxidizers in Eq. (1) Cp = heat capacity, J/kg D = diffusivity, irr/s d = particle diameter, m F = ratio of total mass flux to mass flux aluminum H = total flux of energy in aluminum combustion model, W/m2; heat of reaction, J/mol j = mass flux due to diffusion, kg/m2/s k =. arbitrary constant in Eq. (1) M = nondimensional mass flux used in Law's aluminum combustion model /?2 = mass flux, kg/m2/s Nu = Nusselt number p = pressure, N/m2 Qr = heat production due to a reaction, W/m3; heat caused by radiation, W/m2 <92 = enthalpy in the region from the flame to infinity q = heat flux, W/m2 Re = Reynolds number r = radial distance, m; reaction rate, kg/mVs T = temperature, K t = time, s v — velocity, m/s; volume, m3 \v = transport property weighting factor A- = mole fraction 77 = fraction of vaporized oxide that moves toward the particle surface 0 = fraction of metal oxide that vaporizes at the flame A = fraction of metal that reacts with the particular oxidizing species v = stoichiometric mass ratio of oxide or oxidizer to metal f = fraction of condensed products with move inward or outward p = density, kg/m3 T = characteristic time lag, s

Nonsteroidal antiinflammatory drugs cause apoptosis and induce cyclooxygenases in chicken embryo fibroblasts

Abstract: Programmed cell death (apoptosis) is an intrinsic part of organismal development and aging. Here we report that many nonsteroidal antiinflammatory drugs (NSAIDs) cause apoptosis when applied to v-src-transformed chicken embryo fibroblasts (CEFs). Cell death was characterized by morphological changes, the induction of tissue transglutaminase, and autodigestion of DNA. Dexamethasone, a repressor of cyclooxygenase (COX) 2, neither induced apoptosis nor altered the NSAID effect. Prostaglandin E2, the primary eicosanoid made by CEFs, also failed to inhibit apoptosis. Expression of the protooncogene bcl-2 is very low in CEFs and is not altered by NSAID treatment. In contrast, p20, a protein that may protect against apoptosis when fibroblasts enter G0 phase, was strongly repressed. The NSAID concentrations used here transiently inhibit COXs. Nevertheless, COX-1 and COX-2 mRNAs and COX-2 protein were induced. In some cell types, then, chronic NSAID treatment may lead to increased, rather than decreased, COX activity and, thus, exacerbate prostaglandin-mediated inflammatory effects. The COX-2 transcript is a partially spliced and nonfunctional form previously described. Thus, these findings suggest that COXs and their products play key roles in preventing apoptosis in CEFs and perhaps other cell types.

Geometric Approach to Factor Analysis for the Estimation of Orthogonality and Practical Peak Capacity in Comprehensive Two-Dimensional Separations

Abstract: Procedures were developed for the estimation of orthogonality in two-dimensional (2D) separations. The parameters evaluated include peak spreading angle, retention correlation, and practical peak capacity. Solute retention parameters, such as retention times and capacity factors on both dimensions, were used to establish a correlation matrix, from which a peak spreading angle matrix was calculated using a geometric approach to factor analysis. The orthogonality is defined by the correlation matrix with correlation coefficients that vary from 0 (orthogonal) to 1 (perfect correlation). Equations were derived for the calculation of practical peak capacity in 2D separations. The calculations are based on the peak capacities obtained on each dimension and the peak spreading angle in an orthogonal, 2D retention space. The equations and the procedures can be used to evaluate the performance of a comprehensive 2D separation. Using experimental data from a 2D GC separation, it is demonstrated that the equations are very useful for the comparison, evaluation, and optimization of 2D separations.

Nonspecific white matter degeneration following traumatic brain injury

Abstract: Morphometric analysis of magnetic resonance (MR) scans in 88 traumatic brain injury (TBI) patients demonstrated significantly larger ventricle-to-brain ratios (VBR) and temporal horn volumes, and significantly smaller fornix-to-brain ratios (FBR) and corpus callosum (CC) area measurements, compared to 73 controls. Additionally, TBI patients were grouped according to Glasgow Coma Scale (GCS) for a within-TBI sample comparison so that severity of injury on brain morphology could be examined. The severe TBI group (GCS = 3–6) differed from the mild and moderate injury groups on measures of the internal capsule, VBR, temporal horn volume, and CC. In a separate analysis wherein the TBI subjects were grouped by degree of fornix atrophy, the group with the smallest fornix size demonstrated the lowest memory performance. Furthermore, anatomic measures correlated with severity of injury, and tests of memory and motor function. Results demonstrate the diffuse nature of degeneration in TBI with more severe injury, and that quantified MR identified morphologic changes relate to neuropsychological outcome. (JINS, 1995, 1, 17–28.)

Family, educational and peer influences on the alcohol use of female and male adolescents.

Abstract: Objective: This research provides estimates of how strongly family bonds, family drug use, age, educational commitment and peer drug use are associated with the frequency and amount of alcohol consumption among adolescents, and compares females and males. Method: Using questionnaire data from a random sample of 27,000 adolescents, structural equation modeling is used to evaluate the strength of several risk factors. Results: The influence of family bonds is moderately strong but operates primarily through peers; adolescents with higher family bonds are less likely to have close friends who are involved with drugs. Family bonds have a relatively strong, positive association with educational commitment, and adolescents with a higher educational commitment tend to drink less frequently; and when they drink, they tend to consume smaller amounts. Living in a family where other family members have a problem with alcohol or other drugs increases the chance that an adolescent has friends who drink or use other dr...