Showing papers by "University of California, Davis published in 1990"
TL;DR: In this article, regression-based tests for mean-variance equality were proposed in a very general setting, which requires specification of only the mean variance relationship under the alternative, rather than the complete distribution whose choice is usually arbitrary.
1,044 citations
TL;DR: In this paper, a principal-agent model of financial contracting is examined in which a risk-neutral entrepreneur makes an unobservable ex-ante effort choice while employing the investment funds of a risk neutral investor (principal).
959 citations
TL;DR: This work has taken advantage of the capacity of mammalian steroid receptors to function in yeast and constructed a strain of Saccharomyces cerevisiae in which hsp90 expression was regulatable and could be reduced more than 20-fold relative to wild type, providing the first biological evidence that hSp90 acts in the signal transduction pathway for steroid receptors.
Abstract: Signalling by steroid hormones is mediated by receptor proteins that bind hormonal ligands and regulate the transcription of specific genes. The heat-shock protein hsp90 seems to associate selectively with unliganded receptors (aporeceptors), but it has not been determined whether this interaction affects receptor function in vivo. To address the role of hsp90, we have taken advantage of the capacity of mammalian steroid receptors to function in yeast. We constructed a strain of Saccharomyces cerevisiae in which hsp90 expression was regulatable and could be reduced more than 20-fold relative to wild type. At low levels of hsp90, aporeceptors seem to be mostly hsp90-free, yet fail to enhance transcription; on hormone addition, the receptors are activated but with markedly reduced efficiency. Thus hsp90 does not inhibit receptor function solely by steric interference; rather, hsp90 seems to facilitate the subsequent response of the aporeceptor to the hormonal signal. This is the first biological evidence that hsp90 acts in the signal transduction pathway for steroid receptors.
788 citations
TL;DR: In this article, a method was tested in the semiarid Owens Valley, California for measuring sparse vegetation cover using Landsat Thematic Mapper (TM) multispectral images, where fractions of vegetation, soils, and shading and shadow within the smallest resolution elements (30 × 30 m pixels) were computed by applying a mixing model based on laboratory and field reference spectra.
753 citations
TL;DR: It was found that combined N + P enrichment enhanced algal growth much more frequently and more substantially than did addition of N or P singly, and on average, the frequency and degree of algal response did not differ for P vs. N enrichment.
Abstract: While phosphorus is generally considered to be the primary nutrient limiting algal growth in lakes, limitation of algal growth by nitrogen has been observed in freshwater. It is also commonly obser...
650 citations
TL;DR: To consider a behavioral pattern as having evolved to serve a parasite control function the parasite or causative agent should be shown to adversely impact the animal's fitness and the behavior in question must be show to help animals, or their offspring or group mates, in combating their exposure, or reducing their vulnerability, to the parasite.
636 citations
TL;DR: The result indicates that, contrary to previous proposals, pyrroloquinoline quinone is not the active site cofactor in mammalian copper amine oxidases, and suggests that this compound has a functional role at an enzyme active site.
Abstract: An active site, cofactor-containing peptide has been obtained in high yield from bovine serum amine oxidase. Sequencing of this pentapeptide indicates: Leu-Asn-X-Asp-Tyr. Analysis of the peptide by mass spectrometry, ultraviolet-visible spectroscopy, and proton nuclear magnetic resonance leads to the identification of X as 6-hydroxydopa. This result indicates that, contrary to previous proposals, pyrroloquinoline quinone is not the active site cofactor in mammalian copper amine oxidases. Although 6-hydroxydopa has been implicated in neurotoxicity, the data presented suggest that this compound has a functional role at an enzyme active site.
607 citations
TL;DR: In the literature, a variety of approaches have been used to calculate demand elasticities in almost ideal demand system (AIDS) models of demand as mentioned in this paper, and some of these approaches may lead to significant errors.
Abstract: In the literature, a variety of approaches have been used to calculate demand elasticities in almost ideal demand system (AIDS) models of demand. It is common to estimate the linear approximate almost ideal demand system (LA/AIDS) instead of the AIDS. When the LA/AIDS is estimated, all of the previously reported approaches to compute elasticities are theoretically incorrect. This paper presents correct formulas for LA/ AIDS elasticities and illustrates the potential errors from using incorrect computing The almost ideal demand system (AIDS) of Deaton and Muellbauer (1980a,b) has become popular in recent years (Anderson and Blundell; Blanciforti and Green 1983a,b; Blanciforti, Green, and King; Chalfant; Eales and Unnevehr; Fujii, Khaled, and Mak; Fulponi, Heien and Willett; Murray; Parsons; Ray). A variety of approaches to computing elasticities has been used, and some of the approaches may lead to significant errors. This paper clarifies the differences between alternative approaches to estimating demand elasticities in AIDS models.
582 citations
TL;DR: An infectious molecular clone of simian immunodeficiency virus (SIV) was identified that induces AIDS in common rhesus monkeys in a time frame suitable for laboratory investigation and defines a system for molecular dissection of the determinants of AIDS pathogenesis.
Abstract: Better understanding of the pathogenesis of acquired immunodeficiency syndrome (AIDS) would be greatly facilitated by a relevant animal model that uses molecularly cloned virus of defined sequence to induce the disease. Such a system would also be of great value for AIDS vaccine research. An infectious molecular clone of simian immunodeficiency virus (SIV) was identified that induces AIDS in common rhesus monkeys in a time frame suitable for laboratory investigation. These results provide another strong link in the chain of evidence for the viral etiology of AIDS. More importantly, they define a system for molecular dissection of the determinants of AIDS pathogenesis.
558 citations
TL;DR: In this article, a censored regression approach was used for household-level microdata to measure the effects of demographic variables, which is computationally simple, consistent, and asymptotically efficient.
Abstract: Demand systems estimation increasingly makes use of household-level microdata, mainly to measure the effects of demographic variables. Data based on these household-expenditure surveys present a major estimation problem. For any given household, many of the goods have zero consumption, implying a censored dependent variable. Techniques which do not take this censored dependent variable into account will yield biased results. We utilize a censored regression approach that is computationally simple, consistent, and asymptotically efficient. The results are then presented and compared with those obtained using an uncensored technique.
504 citations
TL;DR: Evidence is reviewed that freezing and dehydration are fundamentally different stress vectors and that while many solutes will preserve liposomes during freezing, only a few (of which trehalose is the most effective) will preserve them during drying.
TL;DR: In this article, the authors focus on the nexus between cultural heterosexism and individual prejudice against lesbians and gay men, and identify the key components of the ideologies of sex and gender from which heter-sexism derives: personal-public dichotomy, stigmatization of particular forms of sexuality, and the linkage of heterosexuality to gender-role conformity.
Abstract: Hate crimes against lesbians and gay men occur within a broader cultural context that is permeated by heterosexism. Heterosexism is defined here as an ideological system that denies, denigrates, and stigmatizes any nonheterosexual form of behavior, identity, relationship, or community. It operates principally by rendering homosexuality invisible and, when this fails, by trivializing, repressing, or stigmatizing it. This article focuses upon the nexus between cultural heterosexism and individual prejudice against lesbians and gay men. Key components of the ideologies of sex and gender from which heterosexism derives are identified: (a) the personal-public dichotomy, (b) the stigmatization of particular forms of sexuality, and (c) the linkage of heterosexuality to gender-role conformity. Supported by these ideological underpinnings, cultural heterosexism fosters individual anti-gay attitudes by providing a ready-made system of values and stereotypical beliefs that justify such prejudice as “natural.” By imb...
TL;DR: The data suggest that older patients may experience a burden of new and worsened functional impairment during hospitalization that improves at a much slower rate than the acute illness.
Abstract: This study provides data on changes in the functional status of older patients that are associated with acute hospitalization. Seventy-one patients over the age of 74 admitted to the medical service of Stanford University Hospital between February and May 1987 received functional assessments covering seven domains: mobility, transfer, toileting, incontinence, feeding, grooming, and mental status. Assessments were obtained by report from the patient's caregiver (or the patient when he or she lived alone) for 2 weeks before admission; from the patient's nurse on day 2 of hospitalization and on the day before discharge; and again from the caregiver (or patient) 1 week after discharge. The sample had a mean age of 84, covered 37 Diagnostic Related Groups, and had a median length of stay of 8 days. Between baseline and day 2, statistically significant deteriorations occurred for the overall functional score and for the individual scores for mobility, transfer, toileting, feeding, and grooming. None of these scores improved significantly by discharge. In the case of mobility, 65% of the patients experienced a decline in score between baseline and day 2. Between day 2 and discharge, 67% showed no improvement, and another 10% deteriorated further. These data suggest that older patients may experience a burden of new and worsened functional impairment during hospitalization that improves at a much slower rate than the acute illness. An awareness of delayed functional recovery should influence discharge planning for older patients. Greater efforts to prevent functional decline in the hospitalized older patient may be warranted.
07 May 1990
TL;DR: Initial results demonstrate that many network attacks are detectable with the authors' monitor, although it can be defeated.
Abstract: This study concentrates on the security-related issues in a single broadcast LAN (local area network) such as Ethernet. The authors formalize various possible network attacks. Their basic strategy is to develop profiles of usage of network resources and then compare current usage patterns with the historical profile to determine possible security violations. Thus, the work is similar to the host-based intrusion-detection systems. Different from such systems, however, is the use of a hierarchical model to refine the focus of the intrusion-detection mechanism. The authors also report on the development of an experimental LAN monitor currently under implementation. Several network attacks have been simulated, and results on how the monitor has been able to detect these attacks are analyzed. Initial results demonstrate that many network attacks are detectable with the authors' monitor, although it can be defeated. >
TL;DR: An alternative approach is presented, based upon the timing of radicle emergence, to characterize the relationship of seed germination rates to Psi, and finds that the rate of endosperm weakening is sensitive to PSI or turgor.
Abstract: Seed germination culminates in the initiation of embryo growth and the resumption of water uptake after imbibition. Previous applications of cell growth models to describe seed germination have focused on the inhibition of radicle growth rates at reduced water potential (Psi). An alternative approach is presented, based upon the timing of radicle emergence, to characterize the relationship of seed germination rates to Psi. Using only three parameters, a ;hydrotime constant' and the mean and standard deviation in minimum or base Psi among seeds in the population, germination time courses can be predicted at any Psi, or normalized to a common time scale equal to that of seeds germinating in water. The rate of germination of lettuce (Lactuca sativa L. cv Empire) seeds, either intact or with the endosperm envelope cut, increased linearly with embryo turgor. The endosperm presented little physical resistance to radicle growth at the time of radicle emergence, but its presence markedly delayed germination. The length of the lag period after imbibition before radicle emergence is related to the time required for weakening of the endosperm, and not to the generation of additional turgor in the embryo. The rate of endosperm weakening is sensitive to Psi or turgor.
TL;DR: In this article, a large sample (N = 2223) allowed random segmenting of the data into specification, estimation, and out-of-sample prediction portions, and the prediction results allowed comparison of the statistical models' robustness.
Abstract: Truncated Poisson and truncated negative binomial count data models, as well as standard count data models, OLS, nonlinear normal, and truncated nonlinear normal MLE were used to estimate demand for deer hunting in California. The truncated count data estimators and their properties are reviewed. A large sample (N = 2223) allowed random segmenting of the data into specification, estimation, and out-of-sample prediction portions. Statistics of interest are therefore unbiased by the specification search, and the prediction results allow comparison of the statistical models' robustness. The new estimators are found to be more appropriate for estimating and predicting demand and social benefits than the alternative estimators based on a variety of criteria.
TL;DR: In this article, trained judges rated intensities of astringency and bitterness of four phenolic substances in white wine by scalar and time-intensity methods, and found that the polymeric tannic acid and grape seed tannin were more astringent than bitter.
Abstract: Trained judges rated intensities of astringency and bitterness of four phenolic substances in white wine by scalar and time—intensity methods. According to scalar rating, astringency and bitterness increased as a linear function of concentration for catechin, gallic acid, grape seed tannin and tannic acid. The polymeric tannic acid and grape seed tannin were rated more astringent than bitter; the reverse was found for their respective monomers, gallic acid and catechin. Similar results were obtained for maximum intensity ratings by time—intensity methods. As maximum intensity of astringency or bitterness increased directly with concentration, the total duration of aftertaste increased; however, little or no changes in time to maximum were observed. A slightly longer time to maximum perception for bitterness was observed than for astringency.
TL;DR: In this paper, the authors describe some of the major psychosocial challenges faced by lesbian and gay male survivors of hate crimes, their significant others, and the gay community as a whole.
Abstract: This article describes some of the major psychosocial challenges faced by lesbian and gay male survivors of hate crimes, their significant others, and the gay community as a whole. When an individual is attacked because she or he is perceived to be gay, the negative mental health consequences of victimization converge with those resulting from societal heterosexism to create a unique set of problems. Such victimization represents a crisis for the individual, creating opportunities for growth as well as risks for impairment. The principal risk associated with anti-gay victimization is that the survivor's homosexuality becomes directly linked to her or his newly heightened sense of vulnerability. The problems faced by lesbian and gay male victims of sexual assault, and the psychological impact of verbal abuse also are discussed. Suggestions are offered to assist practitioners in helping the survivors of anti-gay hate crimes.
TL;DR: The recent observation that Zn may be critical for the activity and binding of protein kinase C in lymphocyte membranes suggests that another fruitful area of research will involve examination of the influence of Zn deficiency on lymphocyte membrane structure and function.
Abstract: Zn deficiency can have marked effects on virtually all components of the immune system. That these effects can be functionally significant is demonstrated by the increased susceptibility of Zn-deficient animals to a number of bacterial, viral, and parasitic challenges. In addition, strong epidemiological data support the belief that Zn deficiency is a major factor underlying immune dysfunction in select human populations. Despite recognition of the importance of Zn in the ontogeny and functioning of the immune system, the biochemical lesions underlying the effects of Zn deficiency on immune responsivity have not been well characterized. Future efforts to delineate the effects of Zn on the production, release, and action of cytokines will likely produce significant advances in our understanding of the influence of this element on the immune system. The recent observation that Zn may be critical for the activity and binding of protein kinase C in lymphocyte membranes suggests that another fruitful area of research will involve examination of the influence of Zn deficiency on lymphocyte membrane structure and function. Finally, the recent recognition that Zn may be a critical factor in the activation/inactivation of immunoregulatory genes provides us with yet another avenue of research.
TL;DR: In this paper, the authors define the relationship between telecommunications and transportation, by expanding on linkages already identified in the literature, by identifying additional relationships, and by putting these relationships into a robust conceptual framework.
TL;DR: The results show that growth of the maize primary root at low water potentials involves a complex pattern of morphogenic and metabolic events and the contrasting behavior of hexose and potassium deposition indicates that the adjustment is a highly regulated process.
Abstract: Primary roots of maize (Zea mays L. cv WF9 × Mo17) seedlings growing in vermiculite at various water potentials exhibited substantial osmotic adjustment in the growing region. We have assessed quantitatively whether the osmotic adjustment was attributable to increased net solute deposition rates or to slower rates of water deposition associated with reduced volume expansion. Spatial distributions of total osmotica, soluble carbohydrates, potassium, and water were combined with published growth velocity distributions to calculate deposition rate profiles using the continuity equation. Low water potentials had no effect on the rate of total osmoticum deposition per unit length close to the apex, and caused decreased deposition rates in basal regions. However, rates of water deposition decreased more than osmoticum deposition. Consequently, osmoticum deposition rates per unit water volume were increased near the apex and osmotic potentials were lower throughout the growing region. Because the stressed roots were thinner, osmotic adjustment occurred without osmoticum accumulation per unit length. The effects of low water potential on hexose deposition were similar to those for total osmotica, and hexose made a major contribution to the osmotic adjustment in middle and basal regions. In contrast, potassium deposition decreased at low water potentials in close parallel with water deposition, and increases in potassium concentration were small. The results show that growth of the maize primary root at low water potentials involves a complex pattern of morphogenic and metabolic events. Although osmotic adjustment is largely the result of a greater inhibition of volume expansion and water deposition than solute deposition, the contrasting behavior of hexose and potassium deposition indicates that the adjustment is a highly regulated process.
TL;DR: In this paper, three fundamental contradictions were examined in the stages of development identified retrospectively by 106 romantic relationship parties: autonomy-connection, openness-closedness, and predictability-novelty.
Abstract: Three fundamental contradictions were examined in the stages of development identified retrospectively by 106 romantic relationship parties: autonomy-connection, openness-closedness, and predictability-novelty. The contradictions were reported to be present in approximately three-quarters of all identified stages. The openness closedness contradiction was more likely than the other two contradictions to be reported during the initial stage of development; autonomy connection and predictability-novelty contradictions were reported with increased frequency in subsequent developmental stages. Relationship parties reported that they managed the contradictions with six basic types of responses. These response forms were not reported with equal frequency across the contradictions and the stages of development. Current relationship satisfaction did not correlate significantly with the reported presence of the contradictions but did correlate with the ways in which the contradictions were managed.
01 Apr 1990
TL;DR: The class of spectral self-coherence restoral (SCORE) objective functions is introduced, and algorithms for adapting antenna arrays to optimize these objective functions are developed to maximize the signal-to-interference-and-noise ratio at the output of the narrowband antenna array.
Abstract: A new approach to blind adaptive signal extraction using narrowband antenna arrays is presented. The approach has the capability to extract communication signals from cochannel interference environments using only known spectral correlation properties of those signals, i.e. without using knowledge of the content or direction of arrival of the transmitted signal, or the array manifold or background noise covariance of the receiver, to train the antenna array. The class of spectral self-coherence restoral (SCORE) objective functions is introduced, and algorithms for adapting antenna arrays to optimize these objective functions are developed. Using the theory of spectral correlation, it is shown by analysis and simulation that these algorithms maximize the signal-to-interference-and-noise ratio at the output of the narrowband antenna array when a single communication signal with spectral self-coherence at a known value of frequency separation, along with an arbitrary number of interferers without spectral self-coherence at that frequency separation, are impinging on the array. >
TL;DR: Two very useful serologic tests are primarily to determine the two major antibody responses: the early immunoglobulin M (IgM) response is useful in the diagnosis of acute primary coccidioidomycosis and the exoantigen test for identification of putative cultures of C. immitis.
Abstract: Serologic tests have assisted in the diagnosis and prognosis of coccidioidomycosis for a half-century. The causative agent, Coccidioides immitis, is a dimorphic fungus existing in a hyphal form with arthroconidia in nature and in the usual culture. The arthroconidia represent the inhaled infective forms which in vivo and under special laboratory conditions form spherules which endosporulate. The culture filtrate/autolysate (coccidioidin) from the hyphal phase has provided antigens of suitable reliability for currently used serologic tests. These tests are primarily to determine the two major antibody responses: the early immunoglobulin M (IgM) response is useful in the diagnosis of acute primary coccidioidomycosis. Later, IgG is produced and usually outlasts the IgM, persisting in chronic coccidioidomycosis. The IgM is detectable by tube precipitin, a corresponding immunodiffusion, or latex particle agglutination tests. The pertinent antigen(s) is heat stable and pronase resistant and appears to be largely carbohydrate, mainly mannose with some 3-O-methyl mannose. The IgG detectable in the serum and other body fluids by complement fixation and a corresponding immuno-diffusion is useful in diagnosis, and its quantitation provides an indicator of progression of disease (increasing titer) or regression (decreasing titer). The pertinent antigen appears to be a heat-labile, pronase-sensitive protein which in an unreduced form has a molecular weight of 110,000. A third very useful serologic procedure is the exoantigen test for identification of putative cultures of C. immitis.
TL;DR: Use of NBD-labeled lipids as analogues of natural lipids is critically evaluated and synthetic routes for preparing the lipids, and spectroscopic and ionization properties of these probes are reviewed in this report.
TL;DR: Kupffer cells isolated from the rat liver with alcoholic fibrosis express and release transforming growth factor β is largely responsible for the Kupffer‐cell‐conditioned medium‐induced stimulation of collagen formation by hepatic lipocytes, and this may represent a possible molecular mechanism of lipocyte stimulation during alcoholic liver fibrogenesis.
TL;DR: In this paper, a method has been found for preparing uniform silicon tips with a radius of curvature less than 1 nm, formed by oxidation of 5μm-high silicon cones through exploitation of a known oxidation inhibition of silicon at regions of high curvature.
Abstract: Electron emitters in vacuum microelectronic devices need sharp tips in order to permit electron emission at moderate voltages A method has been found for preparing uniform silicon tips with a radius of curvature less than 1 nm These tips are formed by oxidation of 5‐μm‐high silicon cones through exploitation of a known oxidation inhibition of silicon at regions of high curvature
TL;DR: It is shown that selection among groups can cause the spread of the strategy that has the lowest extinction rate or highest probability of contributing to the colonization of empty habitats, and that this may occur even when groups are usually very large, migration rates are substantial, and "extinction" entails only the disruption of the group and the dispersal of its members.
TL;DR: In this paper, the authors used universal primers to amplify 447 or 445 bp fragments from male or female genomic DNA corresponding to the ZFY or ZFX genes and found specific banding patterns between the two sexes in these species.
Abstract: We describe a quick and efficient method of determining the sex of DNA samples from humans, cattle, sheep, and goats. Using universal primers we have amplified 447 or 445 bp fragments from male or female genomic DNA corresponding to the ZFY or ZFX genes. Restriction fragment length polymorphism (RFLP) analysis of the fragments yielded specific banding patterns between the two sexes in these species. Horse, pig and rainbow trout fragments did not show RFLPs with the group of enzymes chosen for the other species. Use of this method would allow animal breeders to determine the sex of preimplantation embryos before transfer to recipient females. Human embryos at risk for sex-linked disorders could be sexed soon after in vitro fertilization (IVF) and options considered before implantation.