Showing papers by "University of California, Davis published in 1981"

Image data compression: A review

Abstract: With the continuing growth of modern communications technology, demand for image transmission and storage is increasing rapidly. Advances in computer technology for mass storage and digital processing have paved the way for implementing advanced data compression techniques to improve the efficiency of transmission and storage of images. In this paper a large variety of algorithms for image data compression are considered. Starting with simple techniques of sampling and pulse code modulation (PCM), state of the art algorithms for two-dimensional data transmission are reviewed. Topics covered include differential PCM (DPCM) and predictive coding, transform coding, hybrid coding, interframe coding, adaptive techniques, and applications. Effects of channel errors and other miscellaneous related topics are also considered. While most of the examples and image models have been specialized for visual images, the techniques discussed here could be easily adapted more generally for multidimensional data compression. Our emphasis here is on fundamentals of the various techniques. A comprehensive bibliography with comments is included for a reader interested in further details of the theoretical and experimental results discussed here.

A model for the estimation of outcrossing rate and gene frequencies using n independent loci

Abstract: A mixed mating model for many unlinked loci is described. A procedure for estimation of the model parameters (outcrossing rate and gene frequencies), based on a multilocus maximum likelihood equation, is discussed and analyzed for bias, variance, and robustness. Genotypic data from families of known or unknown maternal parentage, or data from progenies of known maternal parentage, are used for estimation. The procedure is applicable to dominant or co-dominant Mendelian genes with two or three alleles per locus, and should be particularly useful in studies where the effort in scoring more loci is less than the effort in scoring more progeny. Variances of the multilocus estimates of outcrossing rate and pollen pool gene frequencies decrease when more loci are included in the estimation. Monte Carlo simulations showed the estimates to be unbiased when model assumptions are not violated, but the bias introduced by various violations is reduced when more loci are included in the estimate. Often the variance of a three or four locus estimate closely approaches the minimum variance possible (the variance of an estimate using infinitely many loci), setting a practical limit to the number of loci needed for a nearly minimum variance estimate. An example from some work on Limnanthes is presented to illustrate the use of multilocus model and its fit to data from natural populations.

Nonlinear decoupling via feedback: A differential geometric approach

Abstract: The paper deals with the nonlinear decoupling and noninteracting control problems. A complete solution to those problems is made possible via a suitable nonlinear generalization of several powerful geometric concepts already introduced in studying linear multivariable control systems. The paper also includes algorithms concerned with the actual construction of the appropriate control laws.

DDT-induced feminization of gull embryos

Abstract: Injection of DDT [1, 1, 1-trichloro-2,2-bis(p-chlorophenyl)ethane] into gull eggs at concentrations comparable to those found in contaminated seabird eggs in 1970 induces abnormal development of ovarian tissue and oviducts in male embryos. Developmental feminization of males is associated with inability to breed as adults and may explain the highly skewed sex ratio and reduced number of male gulls breeding on Santa Barbara Island in southern California.

Advances in mathematical models for image processing

Abstract: Several state-of-the-art mathematical models useful in image processing are considered. These models include the traditional fast unitary transforms, autoregessive and state variable models as well as two-dimensional linear prediction models. These models introduced earlier [51], [52] as low-order finite difference approximations of partial differential equations are generalized and extended to higher order in the framework of linear prediction theory. Applications in several image Processing problems, including image restoration, smoothing, enhancement, data compression, spectral estimation, and filter design, are discussed and examples given.

Defect in cyclic AMP phosphodiesterase due to the dunce mutation of learning in Drosophila melanogaster.

Abstract: Cyclic AMP is an intracellular mediator ('second messenger') in the nervous and endocrine control of cellular function, regulating different processes in different cell types. Although evidence is incomplete, it seems that cyclic AMP enhances the calcium-mediated release of neurotransmitter in some neurones. A simple form of memory in the mollusc Aplysia is probably encoded as a cyclic AMP-induced enhancement of neurotransmission at certain synapses of the central nervous system. The possibility that cyclic AMP participates in learning mechanisms may be explored using genetic mutants. For this purpose the fruitfly Drosophila is suitable as it is genetically well characterized and can learn through olfaction, vision or taste. We show here that independent searches for mutations of olfactory learning and of cyclic AMP metabolism, and for mutations causing female infertility have each led to the same gene--the dunce gene. Our evidence indicates that the normal dunce gene may specify a cyclic AMP phosphodiesterase.

Influence of ashing techniques on the analysis of trace elements in animal tissue : I. Wet ashing.

Abstract: A multitude of methods exists at present for the solubilization of biological tissues for atomic absorption analysis. We have examined several common methods of wet ashing using NBS bovine liver in order to determine which acids, acid combinations, or bases should be used as digesting agents for accurate and precise measurement of iron, copper, zinc, and manganese. Nitric acid proved to be the most effective wet ashing agent. With nitric acid, mean concentrations for iron, copper, and zinc differed from NBS certified values by less than 1.5% while those for manganese differed by 4%.

Naturally Occurring Food Toxicants: Phenolic Substances of Plant Origin Common in Foods

Abstract: Publisher Summary The risks to humans of serious poisonous effects caused by natural phenols present in normal foods consumed under usual circumstances seem vanishingly small, as determined by experiment, as well as common sense and long-term observation. Conclusions involving evolution obviously are speculative, but some putative relationships appear worthy of discussion to clarify the durability of animal life and the threat of plant toxins generally or of phenols particularly. Phenols are probably the most important group of substances, useful in chemotaxonomic differentiation among plant species. Plants have evolved toxins to combat herbivores, but herbivores have also evolved to tolerate or avoid plant toxins. Phenol itself, and other small phenols, such as catechol, the cresols, guaiacol, orcinols, and pyrogallol, are commonly considered to be industrial chemicals. Gallic acid is widely distributed in plants, but the concentration is usually very low. The flavonoids contribute color, flavor, and processing characteristics important in food. The most often cited effect of phenols that is discussed in this chapter is the inhibition of catechol-O-methyltransferse (COMT) and competition for methyl groups by phenols that serve as a substrate for this enzyme. The chapter discusses that many plants contain secondary metabolites toxic or deterrent to members of the animal kingdom attempting to feed on them. Plant phenols that are highly toxic to animals are rarely found. The phenols that occur widely in plants or in large amounts in common food plants have very low acute oral toxicity and most are also of low toxicity when given parenterally.

Evidence for Extensive Overlap of Sporophytic and Gametophytic Gene Expression in Lycopersicon esculentum.

Abstract: Male gametophyte (pollen) isozyme profiles were compared with those of the sporophyte for nine enzyme systems. Sixty percent of the structural genes coding for these enzymes in the sporophyte were also found to be expressed by the gametophyte. All the genes tested were found to be expressed after meiosis, apparently transcribed and translated in the haploid gametophytes.

Extrapolation algorithms for discrete signals with application in spectral estimation

Abstract: In this paper we present some new algorithms useful for extrapolation and spectral estimation of band-limited sequences in one and two dimensions. First we show that many of the existing extrapolation algorithms for noiseless observations are unified under the criterion of minimum norm least squares (MNLS) extrapolation. For example, the iterative algorithms proposed in [2] and [8]-[10] are shown to be special cases of a one-step gradient algorithm which has linear convergence. Convergence and other numerical properties are improved by going to a conjugate gradient algorithm. For noisy observations, these algorithms could be extended by considering a mean-square extrapolation criterion which gives rise to a mean-square extrapolation filter and also to a recursive extrapolation filter. Examples and application of these methods are given. Extension of these algorithms is made for problems where the signal is known to be periodic. A new set of functions called the periodic-discrete prolate spheroidal sequences (P-DPSS), analogous to DPSS [21], [22], are introduced and their properties are studied. Finally, several of these algorithms are generalized to two dimensions and the relevant equations are given.

An enteric coronavirus infection of cats and its relationship to feline infectious peritonitis

Abstract: An enteric coronavirus that is antigenically closely related to feline infectious peritonitis virus (FIPV) is ubiquitous in the cat population. This virus has been designated feline enteric coronavirus to differentiate it from FIPV. The virus is shed in the feces by many seropositive cats; in catteries it is a cause of inapparent to mildly severe enteritis in kittens 6 to 12 weeks of age. The virus may produce a more severe enteritis in young specific-pathogen-free kittens. Feline enteric coronavirus selectively infects the apical columnar epithelium of the intestinal villi, from the caudal part of the duodenum to the cecum. In severe infections, there are sloughing of the tips of the villi and villous atrophy. Many cats recovering from the disease remain carriers of the virus. Recovered cats, observed for 3 to 24 months, remained healthy and did not develop peritonitis, pleuritis, or granulomatous disease. The relationship of feline enteric coronavirus and FIPV was studied. Although the viruses were antigenically similar, they were distinctly different in their pathogenicities. The enteric coronavirus did not cause feline infectious peritonitis in coronavirus antibody-negative cats inoculated orally or intraperitoneally nor in coronavirus antibody-positive cats inoculated intraperitoneally or intratracheally. Serologic tests, using FIPV, canine coronavirus, and transmissible gastroenteritis virus of swine as substrate antigens in fluorescent antibody procedures may not accurately identify FIPV infection. These tests do not appear to distinguish between FIPV and this feline enteric coronavirus.

Biosynthesis of stress ethylene induced by water deficit.

Abstract: Wheat leaves normally produced very little ethylene, but following a water deficit stress which caused a loss of 9% initial fresh weight, ethylene production increased more than 30-fold within 4 hours and declined rapidly thereafter. The changes in ethylene production were paralleled by an increase and subsequent decrease in 1-aminocyclopropanecarboxylic acid (ACC) content. The level of S-adenosylmethionine was unaffected, suggesting that the conversion of S-adenosylmethionine to ACC is a key reaction in the production of water stress-induced ethylene. This view was further supported by the observation that application of ACC to nonstressed leaf tissue caused a 70-fold increase in ethylene production, while aminoethoxyvinylglycine, a known inhibitor of the conversion of S-adenosylmethionine to ACC, inhibited ACC accumulation as well as the surge in ethylene production if the inhibitor was applied prior to the stress treatment. Cycloheximide, an inhibitor of protein synthesis, effectively blocked both ethylene production and ACC formation, suggesting that water stress induces de novo synthesis of ACC synthase, which is the rate-controlling enzyme in the pathway of ethylene biosynthesis.

Proline over-production results in enhanced osmotolerance in Salmonella typhimurium.

Abstract: Mutants of S. typhimurium with enhanced osmotolerance were isolated. These mutants were obtained as strains which over-produced proline due to regulatory mutations affecting proline biosynthesis. The mutations are located on F′proBA and upon transfer to other S. typhimurium strains, they confer enhanced osmotolerance on the recipients. The osmotolerant mutants not only have higher intracellular proline levels than the osmosensitive parental strain, but the proline levels in the osmotolerant mutants are regulated such that they increase in response to osmotic stress. Possible reasons why elevated proline levels lead to enhanced osmotolerance are discussed.

Is a New Evolutionary Synthesis Necessary

Abstract: The current (synthetic) theory of evolution has been criticized on the grounds that it implies that macroevolutionary processes (speciation and morphological diversification) are gradual. The extent to which macroevolution is gradual or punctuational remains to be ascertained. Macroevolutionary processes are underlain by microevolutionary phenomena and are compatible with the synthetic theory of evolution. But microevolutionary principles are compatible with both gradualism and punctualism; therefore, logically they entail neither. Thus, macroevolution and microevolution are decoupled in the important sense that macroevolutionary patterns cannot be deduced from microevolutionary principles.

A multilocus estimator of mating system parameters in plant populations

Abstract: A multilocus method of estimating mating system parameters in populations is presented that recovers information from classification over multiple loci that single-locus estimators do not detect. It is shown that the multilocus estimator provides a standard of reference (null hypothesis) that can be useful in analyzing the effects of factors such as population heterogeneity and post-mating zygotic selection on the transmission of genetic information at the population level.

Evidence for Independent Genetic Control of the Multiple Forms of Maize Endosperm Branching Enzymes and Starch Synthases

Abstract: Soluble starch synthase and starch-branching enzymes in extracts from kernels of four maize genotypes were compared. Extracts from normal (nonmutant) maize were found to contain two starch synthases and three branching enzyme fractions. The different fractions could be distinguished by chromatographic properties and kinetic properties under various assay conditions. Kernels homozygous for the recessive amylose-extender (ae) allele were missing branching enzyme IIb. In addition, the citrate-stimulated activity of starch synthase I was reduced. This activity could be regenerated by the addition of branching enzyme to this fraction. No other starch synthase fractions were different from normal enzymes. Extracts from kernels homozygous for the recessive dull (du) allele were found to contain lower branching enzyme IIa and starch synthase II activities. Other fractions were not different from the normal enzymes. Analysis of extracts from kernels of the double mutant ae du indicated that the two mutants act independently. Branching enzyme IIb was absent and the citrate-stimulated reaction of starch synthase I was reduced but could be regenerated by the addition of branching enzyme (ae properties) and both branching enzyme IIa and starch synthase II were greatly reduced (du properties). Starch from ae and du endosperms contains higher amylose (66 and 42%, respectively) than normal endosperm (26%). In addition, the amylopectin fraction of ae starch is less highly branched than amylopectin from normal or du starch. The above observations suggest that the alterations of the starch may be accounted for by changes in the soluble synthase and branching enzyme fractions.

Changes in Diet and Body Composition of Canada Geese before Spring Migration

Abstract: Changes in diet and body composition of Giant Canada Geese (Branta canadensis maxima) were studied before geese initiated spring migration in early April. During the period of hyperphagia in March, body weight of female and male geese increased 36% and 26%, respec- tively, above average winter weights. Body weights of paired geese averaged 0.34 kg (females) and 0.27 kg (males) more than those of geese without mates before the weight gain period. Some unmated geese did not gain weight, and others gained less weight than paired geese. Geese shifted from a winter diet of corn (Zea mays) to a diversity of food items in spring. Corn remained the primary source of carbohydrate, and bluegrass (Poa pratensis) provided protein for geese. Weight gain of females was composed of 61% lipid, 10% protein, and 21% water, whereas weight gained by males was 47% lipid, 13% protein, and 35% water. Initial weight gains were predominantly protein (and accompanying water), probably required for gut enlargement. Most of the later body weight gain was due to lipid storage. Increase in size of breast and leg muscles at the end of March was largely due to lipid storage and a shift of protein from other body tissues. Lipid and protein storage was adequate to explain energy and nutrient requirements for body maintenance after arrival on the breeding grounds, egg laying, and territorial defense. Females may have to obtain minerals (and possibly additional protein) for egg formation from food sources on the breeding grounds. Lipid reserves of male Giant Canada Geese indicate an ability to sustain energetic costs during nesting equal to those of the female (apart from egg laying) and are greater than reserves of other species of geese and subspecies of Canada Geese investigated to date. Received 22 April 1980, accepted 21 August 1980. THE importance of lipid and protein reserves for reproduction by geese has been the subject of much recent discussion (Ankney 1977; Raveling and Lumsden 1977; Ankney and Macinnes 1978; Raveling 1978a, 1979a, b). Increases in body weight of females in spring of 41-53% of winter weight have been documented for Todd's Canada Goose (Branta canadensis interior, Hanson 1962a), Ross' Goose (Chen rossii, Ryder 1967), Lesser Snow Goose (Chen caerulescens caerulescens; Ankney 1977, Ankney and Macinnes 1978), and the Cackling Goose (B.c. minima, Raveling 1979a). These reserves provide the necessary energy for migration and reproduction and are critical in affecting clutch size. The evolutionary and functional significance of these weight gains was discussed in the papers cited above (see also Barry 1962, Ryder 1970). Few data exist on the process of acquisition of maximum body weights by geese during spring, however, and most previous studies used qualitative mea- sures or indirect indices of body composition of free-living geese (Hanson 1962a, Ryder 1970, Ankney 1977, Ankney and Macinnes 1978, Wypkema and Ankney 1979). Recently, body components were quantified and energetic strategies discussed for Common Eiders (Somateria mollissima, Korschgen 1977) and Cackling Geese (Raveling 1979a, b). The purpose of this study was to use similar methods to measure quantitatively the changes in body constituents and skeletal muscles undergone by adult Giant Canada Geese (B.c. maxima, Hanson 1965). We related these changes to food habits, social status, and timing of spring migration in order to understand better the behavior attendant to and the factors controlling the attainment of the annual reproductive state.

An impulse-timing theory for reciprocal control of muscular activity in rapid, discrete movements.

Abstract: Much remains to be learned about how agonist and antagonist muscles are controlled during the production of rapid, voluntary movements. In an effort to summarize a wide body of existing knowledge and stimulate future research on this subject, an impulse-timing theory is presented which attempts to predict the activity of reciprocal muscles based on certain characteristics of a movement. The basic tenet of the theory is that variables of movement time, movement distance and inertial load have fairly predictable effects on the underlying muscular activity of the agonist and antagonist muscles during the production of rapid and discrete, voluntary movements. The theory is derived from the kinematic work of Schmidt, Zelaznik, Hawkins, Frank and Quinn (1979) and supporting evidence from studies which have used electromyographic (EMG) recordings of agonist and antagonist muscles during rapid movements. Issues related to synergistic muscle control, central and peripheral control of reciprocal muscle activity, muscle control, and neurological disorder and the relationship between impulse-timing and mass-spring control are discussed in the final section.

Developmental changes in composition of cats milk: trace elements, minerals, protein, carbohydrate and fat.

Abstract: The concentrations of iron, copper, zinc, manganese, calcium and magnesium, as well as protein, carbohydrate and fat, were analyzed in rat milk during the course of lactation in rats fed a purified diet. As serial milking has been demonstrated to affect milk composition (1), lactating rats were milked only once at various times from days 0 to 28 after parturition. Concentration of iron decreased rapidly from 9 to 5 micrograms/ml during the 1st week of lactation and changed little thereafter. Similarly, copper concentration decreased considerably in early lactation, from 9 to 2 micrograms/ml, but then remained constant. Zinc concentration did not decrease during the 1st week of lactation, but dropped from 14 micrograms/ml in the 2nd week of lactation to 8-10 micrograms/ml in mature milk. Manganese was unique as its concentration decreased during the early days of lactation, from 0.3 to 0.1 microgram/ml, with a subsequent rise in late lactation back to 0.3 microgram/ml. Calcium and magnesium concentrations increased somewhat in early lactation and decreased slightly in later lactation, but the changes were fairly small as compared to the trace elements. Developmental patterns for protein, carbohydrate and fat were not very pronounced, although protein and carbohydrate increased somewhat in early lactation and later decreased. These data demonstrate that the nutrient intake of the suckling changes markedly during the early neonatal period. These changes should be taken into account in evaluating data on the trace element composition of tissues of suckling rats.

Isolation and culture of adult hepatocytes from liver biopsies

Abstract: Hepatocytes were isolated from liver biopsies of rats, guinea pigs, rabbits, dogs, and humans. The procedure is based on cannulation of large veins in the cut face of the biopsy, followed by collagenase perfusion. Yields averaged 19 x 10(6) viable hepatocytes/g liver. Viability averaged 84%, as determined by trypan blue dye exclusion. Cultures were prepared from the isolated hepatocytes and were found to be comparable in morphology and N-demethylase activity to hepatocyte cultures prepared by the in situ perfusion of the liver. The development of this method should facilitate comparative studies of the cytotoxicity, genotoxicity, and metabolism of foreign chemicals in primary hepatocyte cultures.