Showing papers by "Pennsylvania State University published in 1987"

Adaptive histogram equalization and its variations

Abstract: Adaptive histogram equalization (ahe) is a contrast enhancement method designed to be broadly applicable and having demonstrated effectiveness. However, slow speed and the overenhancement of noise it produces in relatively homogeneous regions are two problems. We report algorithms designed to overcome these and other concerns. These algorithms include interpolated ahe, to speed up the method on general purpose computers; a version of interpolated ahe designed to run in a few seconds on feedback processors; a version of full ahe designed to run in under one second on custom VLSI hardware; weighted ahe, designed to improve the quality of the result by emphasizing pixels' contribution to the histogram in relation to their nearness to the result pixel; and clipped ahe, designed to overcome the problem of overenhancement of noise contrast. We conclude that clipped ahe should become a method of choice in medical imaging and probably also in other areas of digital imaging, and that clipped ahe can be made adequately fast to be routinely applied in the normal display sequence.

Message equivocality, media selection and manager performance: implications for information systems

Abstract: A field study of middle- and upper-level managers was undertaken to explain managers' selection of communication media. The findings indicate that media vary in their capacity to convey information cues. Managers prefer rich media for ambiguous communications and less rich media for unequivocal communications. The data suggest that high performing managers are more sensitive to the relationship between message ambiguity and media richness than low performing managers. Implications for managers' use of information systems and electronic media are discussed.

Why are children in the same family so different from one another

Abstract: One of the most important findings that has emerged from human behavioral genetics involves the environment rather than heredity, providing the best available evidence for the importance of environmental influences on personality, psychopathology, and cognition. The research also converges on the remarkable conclusion that these environmental influences make two children in the same family as different from one another as are pairs of children selected randomly from the population.The theme of the target article is that environmental differences between children in the same family (called “nonshared environment”) represent the major source of environmental variance for personality, psychopathology, and cognitive abilities. One example of the evidence that supports this conclusion involves correlations for pairs of adopted children reared in the same family from early in life. Because these children share family environment but not heredity, their correlation directly estimates the importance of shared family environment. For most psychological characteristics, correlations for adoptive “siblings” hover near zero, which implies that the relevant environmental influences are not shared by children in the same family. Although it has been thought that cognitive abilities represent an exception to this rule, recent data suggest that environmental variance that affects IQ is also of the nonshared variety after adolescence.The article has three goals: (1) To describe quantitative genetic methods and research that lead to the conclusion that nonshared environment is responsible for most environmental variation relevant to psychological development, (2) to discuss specific nonshared environmental influences that have been studied to date, and (3) to consider relationships between nonshared environmental influences and behavioral differences between children in the same family. The reason for presenting this article in BBS is to draw attention to the far-reaching implications of finding that psychologically relevant environmental influences make children in a family different from, not similar to, one another.

Earth's early atmosphere

Abstract: Ideas about atmospheric composition and climate on the early Earth have evolved considerably over the last 30 years, but many uncertainties still remain. It is generally agreed that the atmosphere contained little or no free oxygen initially and that oxygen concentrations increased markedly near 2.0 billion years ago, but the precise timing of and reasons for its rise remain unexplained. Likewise, it is usually conceded that the atmospheric greenhouse effect must have been higher in the past to offset reduced solar luminosity, but the levels of atmospheric carbon dioxide and other greenhouse gases required remain speculative. A better understanding of past atmospheric evolution is important to understanding the evolution of life and to predicting whether Earth-like planets might exist elsewhere in the galaxy.

The Continuing Problem of False Positives in Repeated Measures ANOVA in Psychophysiology: A Multivariate Solution

Abstract: Violation of the validity assumptions of repeated measures analysis of variance continues to be a problem in psychophysiology. Such violation results in positive bias for those tests involving the repeated measures factor(s), Recently it has been shown that the tests of simple interactions and multiple comparisons are even more vulnerable to bias (Boik. 1981; Mitzel & Games, 1981). The present paper offers a discussion of the validity assumptions for both overall and sub-effect tests and describes a multivariate approach which allows exact analysis of such designs. A modification of the univariate approach is also described. Validity concerns for both approaches are much less problematic than those of the traditional approach.

Reconceptualizing barriers to family leisure

Abstract: While research indicates that leisure is an important source of both family cohesion and conflict, comparatively little attention has been given to the development of conceptual models which define the nature and operation of leisure barriers. Traditionally, barriers have been assumed to constitute intervening variables in the leisure preference‐participation relationship. This paper suggests that the prevailing conceptualization of leisure barriers addresses only one of the ways in which barriers may be associated with preferences and participation. The model proposed in this paper considers barriers to be of three types: (1) intrapersonal barriers, wherein the primary relationship of importance is between preferences and barriers; (2) interpersonal barriers, which result from either the non‐correspondence of individuals’ intrapersonal barriers or from the behavioral patterning of interpersonal relations, thus indicating a relationship with both preferences and participation; and (3) structural ...

Behind the Mask: The Politics of Employee Appraisal

Abstract: is really no getting around the fact that whenever I evaluate one of my people, I stop and think about the impact—the ramifications of my decisions on my relationship with the guy and his future here. I'd be stupid not to. Call it being politically minded, or using managerial discretion, or fine tuning the guy's ratings, but in the end I've got to live with him, and I'm not going to rate a guy without thinking about the fallout. There are a lot of games played in the rating process and whether we [managers] admit it or not we are all guilty of playing them at our discretion.

Preparation of lead-based ferroelectric relaxors for capacitors

Abstract: On passe en revue des travaux recents sur la preparation de ceramiques dielectriques pour condensateurs. On analyse la stabilite de la structure perovskites et les conditions de formation des phases pyrochlore

Constrained Global Optimization: Algorithms and Applications

Abstract: Convex sets and functions.- Optimality conditions in nonlinear programming.- Combinatorial optimization problems that can be formulated as nonconvex quadratic problems.- Enumerative methods in nonconvex programming.- Cutting plane methods.- Branch and bound methods.- Bilinear programming methods for nonconvex quadratic problems.- Large scale problems.- Global minimization of indefinite quadratic problems.- Test problems for global nonconvex quadratic programming algorithms.

Construction and evaluation of the kinetic scheme associated with dihydrofolate reductase from Escherichia coli.

Abstract: A kinetic scheme is presented for Escherichia coli dihydrofolate reductase that predicts steady-state kinetic parameters and full time course kinetics under a variety of substrate concentrations and pHs. This scheme was derived from measuring association and dissociation rate constants and pre-steady-state transients by using stopped-flow fluorescence and absorbance spectroscopy. The binding kinetics suggest that during steady-state turnover product dissociation follows a specific, preferred pathway in which tetrahydrofolate (H4F) dissociation occurs after NADPH replaces NADP+ in the ternary complex. This step, H4F dissociation from the E X NADPH X H4F ternary complex, is proposed to be the rate-limiting step for steady-state turnover at low pH because koff = VM. The rate constant for hydride transfer from NADPH to dihydrofolate (H2F), measured by pre-steady-state transients, has a deuterium isotope effect of 3 and is rapid, khyd = 950 s-1, essentially irreversible, Keq = 1700, and pH dependent, pKa = 6.5, reflecting ionization of a single group in the active site. This scheme accounts for the apparent pKa = 8.4 observed in the steady state as due to a change in the rate-determining step from product release at low pH to hydride transfer above pH 8.4. This kinetic scheme is a necessary background to analyze the effects of single amino acid substitutions on individual rate constants.

Stability and Instability of Solitary Waves of Korteweg-de Vries Type

Abstract: Considered herein are the stability and instability properties of solitary-wave solutions of a general class of equations that arise as mathematical models for the unidirectional propagation of weakly nonlinear, dispersive long waves. Special cases for which our analysis is decisive include equations of the Korteweg-de Vries and Benjamin-Ono type. Necessary and sufficient conditions are formulated in terms of the linearized dispersion relation and the nonlinearity for the solitary waves to be stable.

Mesoscale Convective Complexes in the Americas

Abstract: Enhanced infrared satellite imagery and conventional surface and sounding data are used to document the existence and climatological characteristics of mesoscale convective complexes (MCCs) over midlatitude South America (south of 20°S) and in the tropical region (20°N to 20°S) between North and South America. The implications of the results, with regard to the structure and dynamics of MCCs, are discussed. It is found that MCCs occur with approximately the same frequency in mid-latitude South America as they do in mid-latitude North America. For the most part the characteristics of mid-latitude South American MCCs are similar to those of MCCs in the United States. The most notable difference between North and South American MCCs is that the South American systems are, on the average, about 60% larger than MCCs in the United States. In addition to the large population of mid-latitude South American MCCs, an even larger number of low-latitude (tropical) systems were found. In general, both the mid-latitude and tropical populations of MCCs are nocturnal and continental; i.e., the great majority of systems occur at night over land. Of the systems that do occur over water, a significant fraction develop into tropical storms. Large populations of MCCs occur in each of the physiographically similar mid-latitude areas of North and South America where low-level nocturnal jets frequently develop. Very few MCCs occur over the Amazon River Basin or over the southeastern United States, even though both of these areas exhibit large amounts of deep convective activity. All of the various MCC population centers occur in latitudinal zones of westerlies or easterlies and are concentrated immediately downwind of major mountain ranges. One of the 2 years of data that was investigated was an El Nino year. During the El Nino period the number of mid-latitude South American systems was more than double the number in the non-El Nino year. Moreover, several MCCs formed over the anomalously warm water that appeared along the Peruvian coast. Thus on the basis of this very small sample, there may be a direct connection between MCC activity and El Nino.

Capillary zone electrophoresis with electrochemical detection.

Abstract: Ce systeme a permis d'obtenir une efficacite de separation (pour la separation du pyrocatechol et de catecholamines) de l'ordre de 180000 plateaux theoriques

Detailed Modeling of PAH Profiles in a Sooting Low-Pressure Acetylene Flame

Abstract: A detailed modeling study of the formation of polycyclic aromatic hydrocarbons in a burner-stabilized low-pressure sooting 23.6 % C2 H2-21.4% 02-Ar flame of Bockhorn and co-workers is reported. The model predicts the correct orders of magnitude and relative appearances of the concentration peaks, but overstates the decline of the species concentrations in the post-flame zone. Imprecise knowledge of the thermochemical data and unknown details of the oxidation of hydrocarbon radicals are the reasons identifed for the latter. The main reaction pathways for cyclization and growth of polycyclic aromatics and the results of the sensitivity tests are in close agreement with those of the previous modeling study of acetylene oxidation under shock-tube conditions. An additional factor that is important in the. flame environment is the diffusion of hydrogen atoms from the main reaction zone into a cooler preflame region

Modeling stabilization and control of serially connected beams

Abstract: Many flexible structures consist of a large number of components coupled end to end in the form of a chain. In this paper, we consider the simplest type of such structures which is formed by N seri...

Pressure Distribution under Symptom-Free Feet during Barefoot Standing

Abstract: The plantar pressure distributions for a large heterogeneous sample of feet (N = 107) were collected during barefoot standing using a capacitance mat. From these data, the function of the foot during standing was characterized. Peak pressures under the heel (139 kPa) were, on average, 2.6 times greater than forefoot pressures (53 kPa). Forefoot peak pressures were usually located under the second or third metatarsal heads. No significant relationship was found between body weight and the magnitude of peak pressure. The concepts of a transverse arch at the level of the metatarsal heads and a "tripod" theory of load distribution were not substantiated by this study. Load distribution analysis showed that the heel carried 60%, the midfoot 8%, and the forefoot 28% of the weightbearing load. The toes were only minimally involved in the weightbearing process. Examples of unusual distributions are shown; finally, a checklist is provided to aid the clinician in evaluating plantar pressure findings.

Hummocky cross-stratification, tropical hurricanes, and intense winter storms

Abstract: Most previous workers have inferred a storm origin for hummocky cross-stratification, which typically occurs in shallow-marine deposits. On the modern Earth, the only storms capable of profoundly affecting shallow-marine depositional environments are severe tropical cyclones (hurricanes) and mid-latitude winter wave cyclones (intense winter storms). This paper examines the palaeogeographic distribution (including palaeolatitude and palaeogeographic setting) of 107 occurrences of hummocky cross-stratification, ranging in age from the Proterozoic to Recent. In each of these stratigraphic units, both palaeolatitude and palaeogeography are consistent with a direct storm influence (associated with the passage of hurricanes or winter storms directly over the site of deposition). This palaeogeographic evidence lends support to the inferred storm origin for hummocky cross-stratification; further, the distribution of the structure suggests that most occurrences (73%) were generated by tropical hurricanes, the remaining 27% being generated by intense mid-latitude winter storms. The preferential generation of hummocky cross-stratification by hurricanes is consistent with: (1) the known differences in the nature of the bottom flows generated by the two major storm types, and (2) the inferred nature of the flows which form hummocky cross-stratification. Hurricanes couple less effectively with the water column than do intense winter storms. Due to this ineffective coupling, hurricane-generated bottom flows tend to be oscillatory-or multidirectional-dominant, with only minor unidirectional components of motion. In contrast, intense winter storms generally do couple effectively with the water column, generating bottom flows which possess a dominant or significant unidirectional component. Most previous workers have suggested that hummocky cross-stratification forms under oscillatory- or multidirectional-dominant flow; thus, it is conceptually reasonable that the vast majority of ancient occurrences of hummocky cross-stratification were probably hurricane-generated, as suggested by the aforementioned palaeogeographic distribution. The Proterozoic, Palaeozoic, Neogene, and Quaternary were times when global climate was similar to that of today. The distribution of hummocky cross-stratification deposited during these times suggests that both hurricanes and intense winter storms occupied latitudinal belts during these times which were essentially identical to those occupied by their modern counterparts. The Mesozoic and Palaeogene were non-glacial times when global climate was much warmer than that of today. The distribution of hummocky cross-stratification deposited during this interval suggests that hurricanes occurred more frequently at higher latitudes during non-glacial times than they do at present. The possibility of a broadened hurricane belt during the Mesozoic and Palaeogene is consistent with climatic considerations. A limited number of Mesozoic and Palaeogene rock units containing hummocky cross-stratification were deposited in palaeogeographic settings that preclude a direct hurricane influence; these examples were deposited in the middle latitudes, suggesting that intense winter storms continued to form hummocky cross-stratification in the middle latitudes during these much warmer times. Some previous workers have suggested that tsunamis may be capable of generating hummocky cross-stratification. The palaeogeographic distribution of the structure does not support an origin due to tsunamis. Lacustrine examples of hummocky cross-stratification reported herein are the first known non-marine occurrences; they suggest that storm effects strongly influence the sedimentary record of some lakes.

Kinetic Mechanism of DNA Polymerase I (Klenow)

Abstract: The minimal kinetic scheme for DNA polymerization catalyzed by the Klenow fragment of DNA polymerase I (KF) from Escherichia coli has been determined with short DNA oligomers of defined sequence, labeled with (/sup 32/P)-nucleotides. A key feature of this scheme is a minimal two-step sequence that interconverts the ternary KF-DNA/sub n/-dNTP and KF-DNA/sub n+1/-PP/sub i/ complexes. The rate is not limited by the actual polymerization but by a separate step, possibly important in ensuring fidelity. Evidence for this sequence is supplied by the observation of biphasic kinetics in single-turnover pyrophosphorolysis experiments (the microscopic reverse of polymerization). Data analysis then provides an estimate of the internal equilibrium constant. The dissociations of DNA, dNTP, and PP/sub i/ from the various binary and ternary complexes were measured by partitioning (isotope-trapping) experiments. The rate constant for DNA dissociation from KF is sequence dependent and is rate limiting during nonprocessive DNA synthesis. The combination of single-turnover (both directions) and isotope-trapping experiments provides sufficient information to permit a quantitative evaluation of the kinetic scheme for specific DNA sequences.

The effects of variety in food choices on dietary quality.

Abstract: The purpose of this study was to examine the effects of overall dietary variety, variety among major food groups, and variety within major food groups on dietary quality. Nutritional adequacy, one aspect of dietary quality, was measured by a Mean Adequacy Ratio (MAR)--an index of the percent of recommended intake for 11 nutrients. Other dietary quality measures included the percent of calories from fat and sugar and total intakes of energy, cholesterol, and sodium. A study sample of 3,701 individuals was selected from USDA's 1977-78 Nationwide Food Consumption Survey, excluding pregnant and lactating women and children under 1 year of age. Multiple regression analyses were performed to examine the relationships between each type of variety and each diet quality measure, controlling for age, sex, the number of foods, and all of their two-way interactions with variety. The variety terms added a significant increment to the variation in MAR that was explained by each of the models. Variety among five major food groups explained as much of the variation in MAR as did variety within those groups. Thus, dietary variety might best be defined as simply including foods from each of the major groups. Increases in this type of variety were associated with greater increases in MARs for females than for males and for persons with lower vs. higher numbers of foods. None of the types of variety could account for a sizeable proportion of the variation in the intakes of energy, fat, sugar, sodium, or cholesterol. That is, those measures were not related in any appreciable way to variety per se--either to the expansion or to the restriction of food choices. The key to limiting the intake of those constituents may be to selectively alter the scope of food choices to include more of some foods and less of others.

Natural History of Human Immunodeficiency Virus Infections in Hemophiliacs: Effects of T-Cell Subsets, Platelet Counts, and Age

Abstract: Serial T-cell subsets and platelet counts were determined in a cohort of 84 hemophiliacs in whom time of seroconversion for human immunodeficiency virus (HIV) antibody could be ascertained. An abrupt decrease in the number of T-helper (T4) cells was seen in 9 patients 12 to 24 months before the acquired immunodeficiency syndrome (AIDS) was diagnosed (p = 0.0007 compared with those who did not develop AIDS). Thrombocytopenia also was associated with an increased risk for AIDS (p = 0.02), as was older age at the time of seroconversion (p = 0.03). Ten patients developed AIDS at 24 to 95 months after seroconversion, for a cumulative incidence (+/- SE) of 18.0% +/- 7.1% at 6 years. Hemophiliacs who had T4 cell counts of less than 200 cells/microL had a 50% +/- 16% cumulative incidence of AIDS within 2 years, indicating that decreasing or very low T4 cell counts have predictive value for the development of AIDS. Furthermore, the data suggest that thrombocytopenia and older age may be markers for a cofactor that increases the risk for AIDS in hemophiliacs.

Functional properties of parietal visual neurons: Radial organization of directionalities within the visual field

Abstract: Parietal visual neurons (PVNs) were studied in waking monkeys as they executed a simple fixation-detection task. Test visual stimuli of varied direction, speed, and extent were presented during the fixation period; these stimuli did not control behavior. Most PVNs subtend large, bilateral receptive fields and are exquisitely sensitive to stimulus motion and direction but insensitive to stimulus speed. The directional preferences of PVNs along meridians are opponently organized, with the preferred directions pointing either inward toward or outward away from the fixation point. Evidence presented in the preceding paper (Motter et al., 1987) indicates that opponent directionality along a single meridian is produced by a feed-forward inhibition of 20 degrees-30 degrees spatial extent. The observations fit a double-Gaussian model of superimposed but unequal excitatory and inhibitory receptive fields: When the former is larger, inward directionality results; when smaller, outward directionality results. We examine here the distribution of the meridional directional preferences in the visual field. Tests showed that opponent organization is not produced by differences in local directional properties in different parts of the receptive field. The distribution of response intensities from one meridian to another is adequately described by a sine wave function. These data indicate a best radial direction for each neuron with a broad distribution of response intensities over successive meridians. Thus, any single PVN, with rare exceptions, cannot signal radial stimulus direction precisely. We then determined how accurately the population response predicted radial stimulus direction by the application of a linear vector summation model. The resulting population vector varied from stimulus direction by an average of 9 degrees. Whether or not the perception of the direction of motion depends upon a population vector remains uncertain. PVNs are especially sensitive to object movement in the visual surround, particularly in the periphery of the visual field. This, combined with their large receptive fields and their wide but flat sensitivity to stimulus speed, makes them especially sensitive to optic flow. This is discussed in relation to the role of the parietal visual system in the visual guidance of projected movements of the arm and hand, in the guidance of locomotion, and in evoking the illusion of vection.

Misperceptions of Friendly Behavior as Sexual Interest: A Survey of Naturally Occurring Incidents

Abstract: The studies described in this article examine retrospective reports of naturally occurring misperceptions of friendliness as sexual interest. Previous research has demonstrated that men perceive other people and situations more sexually than women do. The purpose of this research was to examine how this gender difference in perceptions of sexuality is exhibited in actual interactions between women and men. Two surveys of undergraduates were conducted. The results indicated that a large percentage of both women and men had experienced such misperceptions, although more women had than men. Most of these incidents were quickly resolved without problems; however, others involved some degree of forced sexual activity and left the individual feeling angry, humiliated, and depressed. Gender differences in the characteristics of these incidents and reactions to them are described. The implications of these findings for future research on gender differences in perceptions of sexual intent are discussed.

Interventions with care givers of dementia patients: comparison of two approaches.

Abstract: We compared the effect of two approaches, family counseling and support groups, for relieving the stress and burden experienced by care givers of dementia patients. Both treatments are designed to implement features of a stress-management model that have been identified in prior research with this population: providing information about the patient's disease and its effects on behavior, teaching behavioral problem solving for managing difficult behavior, and identifying potential support for care givers. Subjects were primary care givers of dementia patients living in the community; they included husbands, wives, daughters, and other relatives. Although subjects in the treatment groups made significant gains over time, they did not differ from wait-list subjects who showed similar improvements. One-year follow-up interviews indicated that gains made during the treatment period were maintained.

Ceramics by the solution-sol-gel route

Abstract: The use of solution mixing followed by gelation to make ultrahomogeneous glasses and ceramics of various oxide compositions for laboratory experimentation, with first organic and later principally colloidal inorganic, precursors was developed over 30 years ago. Major technologies that use the solution-sol-gel route have been developed to make nuclear fuel pellets, ceramic fibers, thin coatings, and abrasive grain. This article reviews the early history and summarizes present research in this field, particularly new processes aimed at achieving xerogel precursors of maximum heterogeneity with respect either to composition or to structure. Such nanocomposites provide major advantages in lowering sintering temperatures, refining microstructure, and controlling morphology and final phase composition.

Amino-acid sequence of glycoproteins encoded by three alleles of the S locus of Brassica oleracea

Abstract: The pollen–stigma interaction of self-incompatibility in the mustard family Brassicaceae is controlled by the S locus. Nearly fifty allelic variants at this locus control the specificity of this interaction. Identity of alleles in pollen and stigma results in an incompatible reaction and the arrest of pollen development. Genetic and developmental analyses of self-incompatibility in Brassica have identified a class of stigma glycoproteins exhibiting allele-specific isoforms as being among the products of the S-locus1–3. A cDNA clone encoding one of these S-locus specific glycoproteins has been isolated from B. oleracea4, and recently, N-terminal protein sequence analysis has shown extensive similarity between three S-locus specific glycoproteins from B. campestris5. Here, we describe cDNA clones encoding such glycoproteins from three different S-allele homozygous genotypes, and report the complete amino-acid sequence of the glycoproteins based on the nucleotide sequence of the cDNA clones. We identify allele-encoded differences in the protein sequences which may be relevant to the allelic specificity of the stigma component of the pollen–stigma interaction. The sequences from the sporophytically determined incompatibility system of Brassica show no similarity to the reported S-locus-associated cDNA sequence of the gametophytic Nicotiana self-incompatibility type6.