Showing papers by "University of California, Davis published in 1988"

Fundamentals of digital image processing

Abstract: Introduction. 1. Two Dimensional Systems and Mathematical Preliminaries. 2. Image Perception. 3. Image Sampling and Quantization. 4. Image Transforms. 5. Image Representation by Stochastic Models. 6. Image Enhancement. 7. Image Filtering and Restoration. 8. Image Analysis and Computer Vision. 9. Image Reconstruction From Projections. 10. Image Data Compression.

An advocacy coalition framework of policy change and the role of policy-oriented learning therein

Abstract: There has been a great deal of research in recent years concerning the use of substantive policy analysis in public policy-making. This paper seeks to integrate those findings - e.g., the ‘enlightenment function’ of policy research - into a more general model of policy-making over periods of a decade or more. The conceptual framework focuses on the belief systems of advocacy coalitions within policy subsystems as the critical vehicle for understanding the role of policy analysis in policy-oriented learning and the effect, in turn, of such learning on changes in governmental programs.

Resolution of quantitative traits into Mendelian factors by using a complete linkage map of restriction fragment length polymorphisms

Abstract: The conflict between the Mendelian theory of particulate inheritance and the observation of continuous variation for most traits in nature was resolved in the early 1900s by the concept that quantitative traits can result from segregation of multiple genes, modified by environmental effects. Although pioneering experiments showed that linkage could occasionally be detected to such quantitative trait loci (QTLs), accurate and systematic mapping of QTLs has not been possible because the inheritance of an entire genome could not be studied with genetic markers. The use of restriction fragment length polymorphisms (RFLPs) has made such investigations possible, at least in principle. Here, we report the first use of a complete RFLP linkage map to resolve quantitative traits into discrete Mendelian factors, in an interspecific back-cross of tomato. Applying new analytical methods, we mapped at least six QTLs controlling fruit mass, four QTLs for the concentration of soluble solids and five QTLs for fruit pH. This approach is broadly applicable to the genetic dissection of quantitative inheritance of physiological, morphological and behavioural traits in any higher plant or animal.

Can there be a feminist ethnography

Abstract: Many feminist scholars have identified ethnographic methods as ideally suited to feminist research because its contextual, experiential approach to knowledge eschews the false dualisms of positivism and, drawing upon such traditionally female strengths as empathy and human concern, allows for an egalitarian, reciprocal relationship between knower and known. This paper discusses the irony that ethnographic methods also subject research subjects to greater risk of exploitation, betrayal, and abandonment by the researcher than does much positivist research. Fieldwork and its textual products represent an intervention into a system of relationships that the researcher is far freer than the researched to leave. The paper calls for greater dialogue between feminism and the new ethnography which addresses similar methodological concerns and suggests certain constraints on that dialogue.

Characterization of ribosomal frameshifting in HIV-1 gag-pol expression

Abstract: Based on precedents from other retroviruses, the precursor of the human immunodeficiency virus (HIV-1) reverse transcriptase is predicted to be a polyprotein with a relative molecular mass (Mr) of 160,000 (160K) encoded by both the viral pol gene and the upstream gag gene. These two genes lie in different translational reading frames, with the 3' end of gag overlapping the 5' end of pol by 205 or 241 nucleotides. Thus, production of the gag-pol fusion protein would require either messenger RNA processing or translational frameshifting. The latter mechanism has been shown in the synthesis of the gag-pol proteins of two other retroviruses, Rous sarcoma virus (RSV) and mouse mammary tumour virus (MMTV). Here we report that translation of HIV-1 RNA synthesized in vitro by SP6 RNA polymerase yields significant amounts of a gag-pol fusion protein, indicating that efficient ribosomal frameshifting also occurs within the HIV-1 gag-pol overlap region. Site-directed mutagenesis and amino-acid sequencing localized the site of frameshifting to a UUA leucine codon near the 5' end of the overlap.

Highbrow/Lowbrow: The Emergence of Cultural Hierarchy in America

Abstract: Acknowledgments Prologue 1. William Shakespeare in America 2. The Sacralization of Culture 3. Order, Hierarchy, and Culture Epilogue Notes Index

Signal interception: a unifying theoretical framework for feature detection

Abstract: The unifying framework of the spectral-correlation theory of cyclostationary signals is used to present a broad treatment of weak, random signal detection for interception purposes. The relationships among a variety of previously proposed ad hoc detectors, optimum detectors, and newly proposed detectors are established. The spectral-correlation-plane approach to the interception problem is put forth as especially promising for detection, classification, and estimation in particularly difficult environments involving unknown and changing noise levels and interference activity. A fundamental drawback of the popular radiometric methods in such environments is explained. >

Seropositivity for HIV and the development of AIDS or AIDS related condition: three year follow up of the San Francisco General Hospital cohort.

Abstract: The three year actuarial progression rate to the acquired immune deficiency syndrome (AIDS) in a cohort of men in San Francisco who were seropositive for the human immuno-deficiency virus (HIV) was 22%. An additional 26 (19%) developed AIDS related conditions. β 2 Microglobulin concentration, packed cell volume, HIV p24 antigenaemia, and the proportion and number of T4 lymphocytes each independently predicted progression to AIDS. β 2 Microglobulin was the most powerful predictor. The 111 subjects tested who were normal by all predictors (40%) had a three year progression rate of 7%, and the 68 subjects who were abnormal by two or more predictors (24%) had a progression rate of 57%. Two thirds of all men who progressed to AIDS were in the last group. The median T4 lymphocyte count in subjects who did not progress to AIDS fell from 626 × 10 6 to 327 × 10 6 /1. HIV p24 antigenaemia developed in 7% of the subjects per year. The proportion who were abnormal by two or more predictive variables rose to 41%. At three years an estimated two thirds of the seropositive subjects showed clinical AIDS, an AIDS related condition, or laboratory results that were highly predictive of AIDS. It is concluded from the observed rates and the distribution of predictive variables at three years that half of the men who were seropositive for HIV will develop AIDS by six years after the start of the study, and three quarters will develop AIDS or an AIDS related condition.

The HIV tat gene induces dermal lesions resembling Kaposi's sarcoma in transgenic mice.

Abstract: When the human immunodeficiency virus transactivating gene under the control of the viral regulatory region is introduced into the germline of mice, skin lesions are induced that resemble Kaposi's sarcoma seen in AIDS. Our findings indicate that HIV could play a direct part in causing cancer.

Effects of lesions of temporal-parietal junction on perceptual and attentional processing in humans

Abstract: When stimuli with larger forms (global) containing smaller forms (local) are presented to subjects with large lesions in the right hemisphere, they are more likely to miss the global form than the local form, whereas subjects with large lesions in the left are more likely to miss the local than the global form. The present study tested whether the global/local impairment in subjects with posterior lesions was due to deficits in controlled attentional processes, passive perceptual processes, or both. Attentional control was examined by measuring reaction time changes when the probability of a target appearing at either the global or local level was varied. Patients with unilateral right or left lesions centered in temporal-parietal regions and age-matched controls served as subjects. Because neurophysiological and neuropsychological evidence have implicated temporal regions in visual discrimination and inferior parietal regions in the allocation of attention to locations in the visual field, patients with left hemisphere lesions were further subdivided into those with lesions centered in the superior temporal gyrus (LSTG) or rostral inferior parietal lobule (LIPL). Patients with right hemisphere injury could not be analogously subdivided. The results revealed that the LSTG group was able to control the allocation of attention to global and local levels normally, while the LIPL group was not. In contrast, the LSTG group showed a strong baseline reaction time advantage toward global targets, while normals and the LIPL group showed no advantage toward one level or the other. Finally, the perceptual component was affected differentially by lesions in the right hemisphere and LSTG, with lesions in the left favoring global targets and lesions in the right favoring local targets. These findings indicate that the hemispheric global/local asymmetry is due to a perceptual mechanism with a critical anatomical locus centered in the STG.

Pathogenesis of experimentally induced feline immunodeficiency virus infection in cats.

Abstract: Feline immunodeficiency virus (FIV; formerly, feline T-lymphotropic lentivirus) is a typical lentivirus resembling human and simian immunodeficiency viruses in morphologic features, protein structure, and reverse transcriptase enzyme. It is antigenically dissimilar, however. The virus is tropic for primary and permanent feline T-lymphoblastoid cells and Crandell feline kidney cells. The virus did not grow in other permanent feline non-lymphoblastoid cells that were tested, or in lymphoid and non-lymphoid cells from man, dogs, mice, and sheep. During short-term inoculation studies in cats, the feline immunodeficiency-like syndrome found in nature was not experimentally induced, but a distinct primary phase of infection was observed. Fever and neutropenia were observed 4 to 5 weeks after inoculation; fever lasted several days, and neutropenia persisted from 1 to 9 weeks. Generalized lymphadenopathy that persisted for 2 to 9 months appeared at the same time. Antibodies to FIV appeared 2 weeks after inoculation and then plateaued. Virus was reisolated from the blood of all infected cats within 4 to 5 weeks after inoculation and persisted indefinitely in the face of humoral antibody response. Virus was recovered from blood, plasma, CSF and saliva, but not from colostrum or milk. Contact transmission was achieved slowly in one colony of naturally infected cats, but not between experimentally infected and susceptible specific-pathogen-free cats kept together for periods as long as 4 to 14 months. The infection was transmitted readily, however, by parenteral inoculation with blood, plasma, or infective cell culture fluids. In utero and lactogenic transmission were not observed in kittens born to naturally or experimentally infected queens. Lymphadenopathy observed during the initial stage of FIV infection was ascribed to lymphoid hyperplasia and follicular dysplasia. A myeloproliferative disorder was observed in 1 cat with experimentally induced infection.

Growth of the Maize Primary Root at Low Water Potentials : I. Spatial Distribution of Expansive Growth

Abstract: Seedlings of maize (Zea mays L. cv WF9 × Mo 17) were grown in vermiculite at various water potentials. The primary root continued slow rates of elongation at water potentials which completely inhibited shoot growth. To gain an increased understanding of the root growth response, we examined the spatial distribution of growth at various water potentials. Time lapse photography of the growth of marked roots revealed that inhibition of root elongation at low water potentials was not explained by a proportional decrease in growth along the length of the growing zone. Instead, longitudinal growth was insensitive to water potentials as low as − 1.6 megapascal close to the root apex, but was inhibited increasingly in more basal locations such that the length of the growing zone decreased progressively as the water potential decreased. Cessation of longitudinal growth occurred in tissue of approximately the same age regardless of spatial location or water status, however. Roots growing at low water potentials were also thinner, and analysis revealed that radial growth rates were decreased throughout the elongation zone, resulting in greatly decreased rates of volume expansion.

Symbolic gesturing in normal infants.

Abstract: 2 studies are presented that document the spontaneous development by normal infants of nonverbal gestures to symbolically represent objects, needs, states, and qualities. These symbolic gestures are shown to be a typical rather than rare phenomenon of early development and to function in ways similar to early verbal symbols. Indeed, the case is made that these gestures and early words are both representative of common underlying mechanisms, in particular, the recognition that things have names. In the first study, mothers of 38 17-month-old infants were interviewed in regard to their infants' verbal and nonverbal development. The second study, designed to document with greater precision the findings of the interview study, is a longitudinal study of 16 infants who were followed from 11 to 24 months. Both studies provide evidence that symbolic gestures tend to develop in tandem with the child's early words, that girls tend to rely more heavily than boys on such gestures, that structured parent-child interactions are important to the development of these gestures, that the gestures tend to depict the function rather than the form of objects, and that the use of gestural labels is positively related to verbal vocabulary development. Implications of these findings for theories of language development and for speech pathology are discussed.

An evaluation of activity-based travel analysis

Abstract: This paper is a review and assessment of the contributions made by “activity-based approaches” to the understanding and forecasting of travel behavior. In their brief history of approximately a decade, activity-based analyses have received extensive interest. This work has led to an accumulation of empirical evidence and new insights and has made substantial contributions toward the better understanding of travel behavior. However, practical applications of the approach in transportation planning and policy development have been scarce. Based on an analysis of the inherent characteristics of the activity-based approach, a review of recent (after the 1981 Oxford conference) developments, and a synthesis of the findings from past empirical studies, this study attempts to evaluate the contribution made by activity-based analyses and determine the reasons for the limited practical application. Recommendations are made for the future development of activity-based analysis as a science of travel behavior and as a tool in the practice of transportation planning and policy development.

Dynamics of Stretched Flames

Abstract: Recent advances in the understanding of the structure, propagation, and extinction of laminar flames under the influence of stretch, as manifested by the existence of flame curvature, flow nonuniformity, and flame motion, are reviewed. The emphasis is on premixed flames because of the richness and subtlety of the phenomena involved. The review distinguishes the influences of the tangential and normal velocity gradients on the flame response, both at the hydrodynamic scale and within the flame structure, and emphasizes the importance of the preferential diffusion nature of heat and mass transport, as well as the extent to which the flame can freely adjust its location in response to stretch in order to achieve complete reaction. It is then demonstrated that stretch has only minimal effect on an adiabatic, unrestrained, diffusionally-neutral flame with complete reaction in that the temperature, propagation rate, and thickness of the flame are invariant to stretch, and that stretch alone cannot extinguish such a flame. In the presence of preferential diffusion and/or when the flame movement is restrained, the response of the flame to stretch becomes more sensitive and extinction is also possible. The concept of flame stretch is applied to interpret such practical flame phenomena as flame stabilization and flame-front instability, determination of laminar flame speeds and flammability limits, concentration and temperature modifications in flame chemistry, and modeling of turbulent flames. The properties of stretched diffusion flames are then briefly discussed. The review closes with suggestions for further research.

Superconducting properties of La2-xBax

Abstract: We show that the superconducting transition temperature ${T}_{c}$ of ${\mathrm{La}}_{2\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Ba}}_{\mathrm{x}}$${\mathrm{CuO}}_{4}$ as a function of barium content (0\ensuremath{\le}x\ensuremath{\le}0.25, determined by mutual inductance measurements) has two maxima, both ${T}_{c}$\ensuremath{\approxeq}25 K, near compositions x=0.09 and x-0.15. Between these two maxima is a local minimum (${T}_{c}$ about 5 K) for x=0.12. dc magnetization data are also reported for six compositions. Anomalies in electrical resistance appear near T=50--60 K at compositions 0.10\ensuremath{\le}x\ensuremath{\le}0.125. Many samples clearly show a second resistive superconducting transition near 30 K in addition to the bulk transition most clearly observed magnetically. The variation of ${T}_{c}$ with composition is discussed in relation to the occurrence of resistance anomalies. The tetragonal lattice parameters at room temperature are consistent with previous work, and show no obvious anomalies. The sample preparation procedures are discussed in detail.

Quantitative NMR measurements of hippocampal atrophy in Alzheimer's disease.

Abstract: Nuclear magnetic resonance (NMR) imaging was employed to study 10 patients with Alzheimer's disease (AD) and seven healthy elderly control subjects. Coronal sections were used to make volumetric measurements of the hippocampus, ventricles, subarach-noid space, and brain parenchyma. The hippocampal volume (normalized relative to the size of the lenticular nucleus) was reduced by 40% in the AD group compared to the controls, with no overlap between the two groups. Overall measures of brain atrophy and ventricular and sulcal enlargement also showed significantly different group means, although with overlap between the two groups. Hippocampal atrophy did not correlate with either overall brain atrophy or dementia severity, although the degree of brain atro-phy was correlated with dementia severity. These results show that NMR is capable of providing in vivo quantification of diminished hippocampal size in AD which is not cor-related with overall brain atrophy and which may differentiate AD from normal aging. © 1988 Academic Press, Inc.

Dynamic models in behavioural and evolutionary ecology

Abstract: The maximization of fitness is often used to analyse the action of natural selection on the life history of animals but short periods of behaviour receive ad hoc treatment. This article describes a dynamic, stochastic model for analysing behaviour in terms of the maximization of fitness.

Phenotypic evolution, constant covariances, and the maintenance of additive variance

Abstract: Theoretical work in evolutionary quantitative genetics concentrates on two problems: phenotypic evolution (including speciation) and the maintenance of the heritable variation on which evolution depends. I will argue that these problems are decoupled in practice, because detailed genetic models do not make useful predictions concerning the dynamics of the critical variance and covariance parameters that enter the evolution equations for means

Nutritional Aspects of Leukocytic Cytokines

Abstract: Immune responses result in a variety of metabolic adjustments that are mediated by cytokines of leukocytic origin. Of the dozens of cytokines released during an immune response, interleukin-1 (IL-1), tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) are the major mediators of intermediary metabolism. These three cytokines act in concert to decrease food intake, increase resting energy expenditure, gluconeogenesis, glucose oxidation, and hepatic synthesis of fatty acids and acute phase proteins, decrease fatty acid uptake by adipocytes and alter the distribution of zinc, iron and copper. Most of these activities result from direct interactions between the cytokine and the responding cells. IL-1, TNF alpha and IL-6 also affect changes in metabolism by changing levels of circulating insulin, glucagon and corticosterone. The nutritional impact of these metabolic changes is dependent upon age. In growing animals, increases in energy expenditure and oxidation of amino acids are balanced by lower needs associated with growth. In adult animals, energy and amino acid requirements are increased by an amount similar to the increased basal metabolic rate and amino acid oxidation. Nutrition also influences the release of cytokines and consequently affects regulation of the immune response. For example, protein deficiency results in decreased IL-1 release and impaired tissue responses to IL-1.

Regional Deposition of Inhaled Monodisperse Coarse and Fine Aerosol Particles in Small Laboratory Animals

Abstract: The regional deposition of inhaled monodisperse insoluble particles of about 1, 3, 5, and 10 micrometers in activity median aerodynamic diameter was measured in four small rodent species including CF1 mice, golden Syrian hamsters, Fischer 344 rats and Hartley guinea pigs and in New Zealand rabbits. Near monodisperse aerosols of about 0.05 micrometers activity median diffusive diameter were also studied. The five species are commonly utilized in inhalation toxicology research. Monodisperse aerosols of fused aluminosilicate particles labeled with radioactive /sup 169/Yb were generated utilizing a modified vibrating liquid stream generator, reduced to Boltzmann charge equilibrium with a /sup 85/Kr discharge device, concentrated with a centripeter stage, fused in a 1200C quartz tube furnace, and delivered to a specially designed nose-only exposure system suitable for use with coarse particles as large as 10 micrometers. Twenty unanaesthetized animals (eight rabbits) were exposed simultaneously for up to 45 minutes to each aerosol particle size.

Induction of acrosome reactions by the human zona pellucida.

Abstract: We have used two approaches to test the ability of the human zona pellucida to induce acrosome reactions in human sperm. First, nonviable human oocytes were incubated for 1 min in a suspension of capacitated sperm (of which fewer than 5% were acrosome-reacted) to allow binding of about 200 sperm per oocyte. Some of the oocytes were fixed immediately, and the remainder were fixed after a further 1-h incubation without free-swimming sperm. As determined by light microscopy, sperm on the zona were only 3 +/- 2% (avg. +/- SD) acrosome-reacted at 1 min, and the incidence increased to 46 +/- 15% during the next hour. Electron microscopy confirmed that most sperm on the zona at 1 min were acrosome-intact. A few sperm were in an early stage of the acrosome reaction. Acrosome reactions occurring on the zona during the subsequent hour appeared to be morphologically normal. Second, treatment of sperm in suspension with acid-disaggregated zonae (2 to 4 zonae/microliter) increased the incidence of acrosome-reacted sperm from 3 +/- 1% to 24 +/- 4%. We conclude that the human zona pellucida, or material intimately associated with it, can induce acrosome reactions in human sperm.

Isozyme variability in trypanosoma cruzi, the agent of chagas' disease: genetical, taxonomical, and epidemiological significance.

Abstract: A genetic interpretation of the zymograms of 524 Trypanosoma cruzi stocks from various hosts and representing a broad geographical range (United States to Southern Brazil) reveals high genetic variability (only one monomorphic locus out of 15) and suggests that this parasite has a diploid structure. The data do not give any indication of Mendelian sexuality, although many opportunities are present for genetic exchange between extremely different genotypes. The population structure of T. cruzi appears to be multiclonal and complex. The natural clones evidenced by isozyme analysis are numerous (43 different ones are recorded among 121 stocks assayed at 15 gene loci) and exhibit a large range of genotypes, in a nonhierarchical structure; it is not possible to cluster them into a few strictly delimited groups which could represent natural taxa. The available data suggest that the genetic variability of T. cruzi reflects the long separate evolution of multiple clones. It is suggested that long clonal evolution may explain the present biological and medical variability of the causative agent of Chagas' disease.