Showing papers by "University of California, Davis published in 1989"
TL;DR: In this paper, a chart for body condition scoring of freely moving Holstein dairy cows was developed using an iterative process consisting of literature review, interviews with experts, field testing, statistical analysis, and comments from chart users.
2,572 citations
TL;DR: A review of the medical records of 239 patients with 243 autogenous bone grafts was undertaken to document the morbidity at the donor sites, finding that there was a much higher complication rate if the incision used for the surgery was also the sameincision used to harvest the bone graft.
Abstract: SummaryA review of the medical records of 239 patients with 243 autogenous bone grafts was undertaken to document the morbidity at the donor sites. The overall major complication rate was 8.6%. Major complications included infection (2.5%), prolonged wound drainage (0.8%), large hematomas (3.3%), re
1,875 citations
TL;DR: Modified atmospheres (MA), i.e., elevated concentrations of carbon dioxide and reduced levels of oxygen and ethylene, can be useful supplements to provide optimum temperature and relative humidity in maintaining the quality of fresh fruits and vegetables after harvest.
Abstract: Modified atmospheres (MA), i.e., elevated concentrations of carbon dioxide and reduced levels of oxygen and ethylene, can be useful supplements to provide optimum temperature and relative humidity in maintaining the quality of fresh fruits and vegetables after harvest. MA benefits include reduced respiration, ethylene production, and sensitivity to ethylene; retarded softening and compositional changes; alleviation of certain physiological disorders; and reduced decay. Subjecting fresh produce to too low an oxygen concentration and/or to too high a carbon dioxide level can result in MA stress, which is manifested by accelerated deterioration. Packaging fresh produce in polymeric films can result in a commodity-generated MA. Atmosphere modification within such packages depends on film permeability, commodity respiration rate and gas diffusion characteristics, and initial free volume and atmospheric composition within the package. Temperature, relative humidity, and air movement around the package can influence the permeability of the film. Temperature also affects the metabolic activity of the commodity and consequently the rate of attaining the desired MA. All these factors must be considered in developing a mathematical model for selecting the most suitable film for each commodity.
1,114 citations
Book•
01 Jun 1989TL;DR: In this paper, the authors illustrate how different patterns of speciation and differentiation have occurred among diverse taxa among different taxa and how they represent both the formation of units of evolution and the connection between microevolution and macroevolution.
Abstract: Speciation is a subject of great interest because it represents both the formation of units of evolution and the connection between microevolution and macroevolution. The purpose of this book is to illustrate how different patterns of speciation and differentiation have occurred among diverse taxa.
1,018 citations
TL;DR: A review of the self-propagating high-temperature synthesis (SHS) method is presented in this article, which emphasizes the mechanisms of the rapid, non-isothermal reactions associated with this method.
1,002 citations
TL;DR: A simple mathematical model of the evolution of indirect reciprocity is described and analysis suggests that indirect reciprocities is unlikely to be important unless interacting groups are fairly small.
967 citations
TL;DR: The developmental courses of high-risk and resilient children were analyzed in a follow-up study of members of a 1955 birth cohort on the island of Kauai, Hawaii, with males displaying greater vulnerability than females in their first decade and less during their second; another shift appears at the beginning of their fourth decade.
Abstract: The developmental courses of high-risk and resilient children were analyzed in a follow-up study of members of a 1955 birth cohort on the island of Kauai, Hawaii. Relative impact of risk and protective factors changed at various life phases, with males displaying greater vulnerability than females in their first decade and less during their second; another shift appears under way at the beginning of their fourth decade. Certain protective factors seem to have a more general effect on adaptation than do specific risk factors.
948 citations
TL;DR: Analysis of conserved tracts of amino acid sequence among LEA proteins from several species suggests that it exists as an amphiphilic α helix which may serve as the basis for higher order structure.
Abstract: LEA proteins are late embryogenesis abundant in the seeds of many higher plants and are probably universal in occurrence in plant seeds. LEA mRNAs and proteins can be induced to appear at other stages in the plant's life by desiccation stress and/or treatment with the plant hormone abscisic acid (ABA). A role in protecting plant structures during water loss is likely for these proteins, with ABA functioning in the stress transduction process. Presented here are conserved tracts of amino acid sequence among LEA proteins from several species that may represent domains functionally important in desiccation protection. Curiously, an 11 amino acid sequence motif is found tandemly repeated in a group of LEA proteins of vastly different sizes. Analysis of this motif suggests that it exists as an amphiphilic α helix which may serve as the basis for higher order structure.
817 citations
TL;DR: The ability of a given concentration of a carbohydrate to shift this band back toward the position noted with the hydrated protein coincided, at least in the extreme cases, with the capacity of that same level of carbohydrate to preserve the activity of rabbit skeletal muscle phosphofructokinase during freeze-drying.
Abstract: Fourier-transform infrared spectroscopy was used to characterize the interaction of stabilizing carbohydrates with dried proteins. Freeze-drying of trehalose, lactose, and myo-inositol with lysozyme resulted in substantial alterations of the infrared spectra of the dried carbohydrates. In the fingerprint region (900-1500 cm-1), there were large shifts in the frequencies of bands, a decrease in absorbance, and a loss of band splitting. These effects mimic those of water on hydrated trehalose. Bands assigned to hydroxyl stretching modes (around 3350 cm-1) were decreased in intensity and shifted to higher frequencies in the presence of the protein. In complementary experiments, it was found that dehydration-induced shifts in the positions of amide I and amide II bands for lysozyme could be partially and fully reversed, respectively, when the protein was freeze-dried in the presence of either trehalose or lactose. In addition, the carboxylate band, which was not detectable in the protein dried without the sugar, was apparent when these sugars were present. myo-Inositol was less effective at shifting the amide bands, and the carboxylate band was not detected in the presence of this carbohydrate. Also tested was the concentration dependency of the carbohydrates' influence on the position of the amide II band for dried lysozyme. The results showed that the ability of a given concentration of a carbohydrate to shift this band back toward the position noted with the hydrated protein coincided, at least in the extreme cases, with the capacity of that same level of carbohydrate to preserve the activity of rabbit skeletal muscle phosphofructokinase during freeze-drying.(ABSTRACT TRUNCATED AT 250 WORDS)
699 citations
664 citations
TL;DR: The tobacco mosaic virus movement protein has a direct effect on a plasmodesmatal function and no evidence of F-dextran metabolism in the leaves of the transgenic plants was found.
Abstract: The function of the 30-kilodalton movement protein (MP) of tobacco mosaic virus is to facilitate cell-to-cell movement of viral progeny in an infected plant. A novel method for delivering non-plasmalemma-permeable fluorescent probes to the cytosol of spongy mesophyll cells of tobacco leaves was used to study plasmodesmatal size exclusion limits in transgenic plants that express the MP gene. Movement of fluorescein isothiocyanate-labeled dextran (F-dextran) with an average molecular mass of 9400 daltons and an approximate Stokes radius of 2.4 nanometers was detected between cells of the transgenic plants, whereas the size exclusion limit for the control plants was 700 to 800 daltons. No evidence of F-dextran metabolism in the leaves of the transgenic plants was found. Thus, the tobacco mosaic virus movement protein has a direct effect on a plasmodesmatal function.
TL;DR: An important implication of the model is that the variation maintained by genotype-environment interactions is difficult to study with the restricted range of environments represented in typical experiments, and efforts to estimate genetic parameters in a single environment may be of limited value.
Abstract: Genotype-environment interactions may be a potent force maintaining genetic variation in quantitative traits in natural populations. This is shown by a simple model of additive polygenic inheritance in which the additive contributions of alleles vary with the environment. Under simplifying symmetry assumptions, the model implies that the variance of the phenotypes produced across environments by a multilocus genotype decreases as the number of heterozygous loci increases. In the region of an optimal phenotype, the mapping from the quantitative trait into fitness is concave, and the mean fitness of a genotype will increase with the number of heterozygous loci. This leads to balancing selection, polymorphism, and potentially high levels of additive genetic variance, even though all allelic effects remain additive within each specific environment. An important implication of the model is that the variation maintained by genotype-environment interactions is difficult to study with the restricted range of environments represented in typical experiments. In particular, if fluctuations in allelic effects are pervasive, as suggested by the extensive literature on genotype-environment interactions, efforts to estimate genetic parameters in a single environment may be of limited value.
TL;DR: An extension of the minimal model to include a singlet Higgs field whose vacuum expectation value determines the mixing is explored, and the possible production mechanisms and phenomenological signatures of the different Higgs bosons at these machines are analyzed.
Abstract: The minimal supersymmetric standard model contains two Higgs doublets which must mix via a mass parameter whose magnitude remains to be explained. We explore an extension of the minimal model to include a singlet Higgs field whose vacuum expectation value determines the mixing. We study the spectrum and couplings of Higgs bosons in this extended model and compare them with those in the minimal model. We examine a number of limiting cases analytically and also make numerical studies of the extended model both with and without constraints from the renormalization-group analysis of a parent superstring-inspired grand-unified-theory model. We establish the conditions for there to be a charged Higgs boson lighter than the ${W}^{\ifmmode\pm\else\textpm\fi{}}$ and the circumstances under which there is no light neutral Higgs boson. With a particularly simple set of boundary conditions at the unification scale, the renormalization-group equations imply that one or more Higgs bosons are light enough to be found at the CERN LEP or SLAC Linear Collider and that many supersymmetric particles should be accessible to these accelerators and the Fermilab Tevatron; relatively few would require the Superconducting Super Collider, Large Hadron Collider, or a TeV-scale ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$ collider for discovery. Finally, we analyze the possible production mechanisms and phenomenological signatures of the different Higgs bosons at these machines.
TL;DR: The results indicate that auditory association cortex in the human temporal-parietal junction is critical for auditory P3 generation.
TL;DR: In this article, the authors provide theoretical reasoning and empirical evidence that international migration decisions are influenced by relative as well as absolute income considerations, and they also suggest that this migration is an effective mechanism for achieving income gains in households that send migrants to the U.S.
Abstract: This article provides theoretical reasoning and empirical evidence that international migration decisions are influenced by relative as well as absolute income considerations. Potential gains in absolute income through migration are likely to play an important role in households’ migration decisions, but international migration by household members who hold promise for success as labor migrants can also be an effective strategy to improve a household’s income position relative to others in the household’s reference group. The findings reported in this article provide empirical support for the hypothesis that relative deprivation plays a significant role in Mexico-to-U. S. migration decisions. The findings also suggest that this migration is an effective mechanism for achieving income gains in households that send migrants to the U.S. and that households wisely choose as migrants those of their members who are most likely to provide net income gains.
TL;DR: In this article, second-harmonic generation and spectroscopic absorption measurements are used to study the nonlinear-optical thin-film properties of azo dye guest molecules oriented in a polymer host by corona-onset poling at elevated temperatures.
Abstract: Second-harmonic generation and spectroscopic absorption measurements are used to study the nonlinear-optical thin-film properties of azo dye guest molecules oriented in a polymer host by corona-onset poling at elevated temperatures (COPET). Parallel-wire electrode and needle electrode configurations are studied. The orientational order of the nonlinear molecules, the internal electric field, and the stability of the second-harmonic properties are measured. The nonlinear properties stabilize after 10 days and remain relatively constant over a period of at least 8 months, and the films tolerate power densities of at least 60MW/cm2. Compared with other poling methods, COPET produces a more efficient long-range and long-term orientational order in the guest–host system studied, resulting in large, stable second-harmonic properties.
TL;DR: Experimental and seroepidemiologic studies suggest that FIV is transmitted mainly by bites, and intimate, non-traumatic contact is inefficient in transmitting the infection.
TL;DR: In this paper, the authors analyze countervailing incentives in the agency problem and demonstate that the creation of countervailious incentives can enhance aggregate welfare and that the agent's performance is distorted both above and below efficient levels, and that an agent's rents generally increase with the realization of his private information over some ranges and decrease over other ranges.
TL;DR: In this paper, the case of a single circular turbulent air jet at the ambient air temperature impinging on a flat stationary surface was considered and some new experimental results were provided that attempt to overcome this difficulty by using a fully developed jet and a well-controlled thermal boundary condition.
Abstract: There are numerous studies, mostly experimental, on the characteristics and heat transfer associated with jet impingement on surfaces. These studies have considered both single jets and multiple jets (i.e., arrays) and many different aspects of impinging jets including the effects of crossflow, jet orientation (oblique jets), jet temperature, rotating surfaces, and different surface shapes. The present study is concerned with the case of a single circular turbulent air jet at the ambient air temperature impinging on a flat stationary surface. One of the difficulties in comparing recent numerical work with previous experimental results is the lack of data on the jet characteristics and in some cases the mixed thermal boundary conditions at the surface. The present work provides some new experimental results that attempt to overcome this difficulty by using a fully developed jet and a well-controlled thermal boundary condition (i.e., a uniform heat flux). No other similar measurements were found in the literature.
Journal Article•
TL;DR: The epidemiologic features of feline immunodeficiency virus (FIV) infection were evaluated in 2,765 cats from the United States and Canada and there was a pronounced linkage between FIV and feline syncytium-forming virus (FeSFV) infections.
Abstract: The epidemiologic features of feline immunodeficiency virus (FIV) infection were evaluated in 2,765 cats from the United States and Canada. Of these cats, 2,254 were considered by veterinarians to be at high risk for the infection, and 511 were healthy cats considered to be at low or unknown risk. Of the cats in the high-risk group, 318 (14%) were found to be infected with FIV. The infection rate among low- or unknown-risk cats was 6 of 511 (1.2%). Male cats in the high-risk group were 3 times more likely to be infected than were females, similarly as were cats greater than 6 years old, compared with younger cats; domestic cats, compared with purebred cats; and free-roaming cats, compared with confined cats. Feline immunodeficiency virus and FeLV infections did not appear to be linked with each other; 16% of FeLV-infected cats in the high- and low-risk groups were coinfected with FIV. In contrast, there was a pronounced linkage between FIV and feline syncytium-forming virus (FeSFV) infections. Seventy-four percent of FeSFV-infected cats in the high-risk study group were coinfected with FIV, compared with a 38% FIV infection rate among cats that were not infected with FeSFV. The major clinical manifestations associated with FIV infection in cats that were surveyed included chronic oral cavity infections (56%), chronic upper respiratory tract disease (34%), chronic enteritis (19%), and chronic conjunctivitis (11%). Bacterial infections of the urinary tract (cystitis), skin, and ears were seen in a small proportion of cats.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: In this article, the authors used a triaxial sonic anemometer/thermometer and three Lyman-alpha hygrometers at an experimental site in Ontario, Canada.
Abstract: Ramp patterns of temperature and humidity occur coherently at several levels within and above a deciduous forest as shown by data gathered with up to seven triaxial sonic anemometer/thermometers and three Lyman-alpha hygrometers at an experimental site in Ontario, Canada. The ramps appear most clearly in the middle and upper portion of the forest. Time/height cross-sections of scalar contours and velocity vectors, developed from both single events and ensemble averages of several events, portray details of the flow structures associated with the scalar ramps. Near the top of the forest they are composed of a weak ejecting motion transporting warm and/or moist air out of the forest followed by strong sweeps of cool and/or dry air penetrating into the canopy. The sweep is separated from the ejecting air by a sharp scalar microfront. At approximately twice the height of the forest, ejections and sweeps are of about equal strength.
TL;DR: It is argued that progesterone is present at the site of fertilization of placental mammals in concentrations sufficient for activity, and hence provides a mechanism of inducing the acrosome reaction, an exocytotic event, in vivo.
TL;DR: In this paper, the authors report experimental observations of high-pressure faulting of metastable Mg2GeO4 olivine as it undergoes incipient transformation to a spinel structure and present a model in which this faulting arises from the generation, propagation and linking up of spinel-filled anticracks.
Abstract: THE mechanism of deep-focus earthquakes has been a puzzle since their discovery almost 70 years ago1, 2, because brittle fracture and frictional sliding at depths in excess of 100–200 km would require unrealistic rock strengths3, 4. Rock strength does increase with pressure, but a few hundred MPa (equivalent to 10–20 km depth) suffices to inhibit most fracture, and elevated temperature activates ductile mechanisms that operate at stresses less than the fracture stength. A range of mechanisms has been proposed for deep earthquakes, including plastic instabilities5–7, shear-induced melting8–11 and instabilities accompanying recrystallization12, 13 or polymorphic phase transformation14–23. Each of these proposed mechanisms has exhibited certain inherent weaknesses (see Kirby22 for review and discussion). Here we report experimental observations of high-pressure faulting of metastable Mg2GeO4 olivine as it undergoes incipient transformation to a spinel 24, 25 structure. We present a model in which this faulting arises from the generation, propagation and linking-up of spinel-filled anticracks26. When applied to the olivine → spinel transformation in the Earth's mantle, the anticrack model27 satisfactorily accounts for the similarities and differences between shallow and deep earthquakes and removes the problems associated with frictional sliding.
TL;DR: The reduction in larval growth is proposed to result from the alkylation of amino acids/protein byo-quinones, and the subsequent reduction in the nutritive quality of foliage, which reduces the digestibility of dietary protein and the bioavailability of amino amino acids.
Abstract: The foliage and fruit of the tomato plantLycopersicon esculentum contains polyphenol oxidases (PPO) and peroxidases (POD) that are compartmentally separated from orthodihydroxyphenolic substrates in situ. However, when leaf tissue is damaged by insect feeding, the enzyme and phenolic substrates come in contact, resulting in the rapid oxidation of phenolics to orthoquinones. When the tomato fruitwormHeliothis zea or the beet army-wormSpodoptera exigua feed on tomato foliage, a substantial amount of the ingested chlorogenic acid is oxidized to chlorogenoquinone by PPO in the insect gut. Additionally, the digestive enzymes of the fruitworm have the potential to further activate foliar oxidase activity in the gut. Chlorogenoquinone is a highly reactive electrophilic molecule that readily binds cova-lently to nucleophilic groups of amino acids and proteins. In particular, the —SH and —NH2 groups of amino acids are susceptible to binding or alkylation. In experiments with tomato foliage, the relative growth rate of the fruitworm was negatively correlated with PPO activity. As the tomato plant matures, foliar PPO activity may increase nearly 10-fold while the growth rate of the fruitworm is severely depressed. In tomato fruit, the levels of PPO are highest in small immature fruit but are essentially negligible in mature fruit. The growth rate of larvae on fruit was also negatively correlated with PPO activity, with the fastest larval growth rate occurring when larvae fed on mature fruit. The reduction in larval growth is proposed to result from the alkylation of amino acids/protein byo-quinones, and the subsequent reduction in the nutritive quality of foliage. This alkylation reduces the digestibility of dietary protein and the bioavailability of amino acids. We believe that this mechanism of digestibility reduction may be extrapolatable to other plant-insect systems because of the ubiquitous cooccurrence of PPO and phenolic substrates among vascular plant species.
TL;DR: Results indicate that histone acetylation has the ability to release negative supercoils previously constrained by nucleosomes into a closed chromatin loop and in effect function as a eukaryotic gyrase.
TL;DR: In this article, the authors examined the effect of tariffs and exchange rates on U.S. prices of Japanese cars, trucks and motorcycles, and found that the long-run pass-through of the tariffs and the exchange rates are identical.
TL;DR: It is suggested it is feasible to develop better empirical formulae for the prediction of cortical bone strength than are currently available if a variety of variables is introduced.
TL;DR: It is reported here that both a Sephadex G-75 column fraction, derived from follicular fluid, and progesterone stimulate rapid hydrolysis of PtdIns(4,5)P2 and PTDIns4P in human sperm and that progester one stimulates a rapid influx of Ca2+ inhuman sperm.
Abstract: Hydrolysis of the phospholipid phosphatidylinositol 4,5-bisphosphate is thought to be intimately involved in agonist-induced changes in intracellular Ca2+ levels Recently we have shown that human preovulatory follicular fluid, which induces exocytosis in human sperm, can stimulate a rapid, transient increase in sperm cytosolic [Ca2+] [Thomas & Meizel (1988) Gamete Res 20, 397-411] We report here that both a Sephadex G-75 column fraction, derived from follicular fluid, and progesterone (a component of both the G-75 fraction and whole follicular fluid) stimulate rapid hydrolysis of PtdIns(4,5)P2 and PtdIns4P in human sperm We also report that progesterone stimulates a rapid influx of Ca2+ in human sperm Human spermatozoa were labelled for 24 h with myo-[3H]inositol and then treated with either the G-75 fraction or progesterone A 30-65% loss of label was detected in PtdIns(4,5)P2 and PtdIns4P within 15 s of stimulus addition; no changes were observed in PtdIns during 2 min of treatment The loss of label from both lipids was accompanied by an increase in water-soluble inositol phosphates Production of both InsP3 and InsP2 was seen within 10 s; however, InsP3 was rapidly removed and had reached control levels by 1 min Similarly, formation of InsP2 reached a peak by 30 s and then began a decline accompanied by a corresponding increase in InsP No increases in InsP4 were seen in sperm treated in this fashion Stimulated hydrolysis of the phosphoinositides and release of inositol phosphates were both blocked by the Ca2+ antagonist La3+ Likewise, the progesterone-induced increase in intracellular Ca2+ was inhibited by La3+, and phosphoinositide hydrolysis stimulated by this hormone was dependent upon the presence of extracellular Ca2+
01 Jan 1989
TL;DR: In this paper, a review of 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, is reviewed.
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.