Showing papers by "University of Florida published in 1992"

Remembering pictures: pleasure and arousal in memory

Abstract: Incidental memory performance for pictures that varied along the affective dimensions of pleasantness and arousal was assessed. For both an immediate and delayed (1 year later) free-recall task, only the arousal dimension had a stable effect on memory performance: Pictures rated as highly arousing were remembered better than low-arousal stimuli. This effect was corroborated in a speeded recognition test, in which high-arousal materials encoded earlier in the experiment produced faster reaction times than their low-arousal counterparts. Pleasantness affected reaction time decisions only for pictures not encoded earlier. These results suggest that whereas both the dimensions of pleasantness and arousal are processed at initial encoding, long-term memory performance is mainly affected by arousal.

The SCS/ARS/CES pesticide properties database for environmental decision-making.

Abstract: A principal goal of pesticide science is to be able to predict the environmental impact of a pesticide before it is released into the environment. To save expense and time, we would like to be able to make such a prediction for each pesticide with as few laboratory experiments on the pesticide as possible, and even fewer field experiments. Environmental processes, however, are enormously complex and sometimes (apparently) random. The sites of most interest—agricultural fields, forests, lakes, streams, etc.—are subtle living ecosystems which are incompletely understood and subject to great variability in space and time. The very diversity and intricacy which are indicators of the health of such ecosystems makes even the definition of what constitutes a significant impact on such systems a difficult task.

Texture Classification by Wavelet Packet Signatures.

Abstract: This correspondence introduces a new approach to characterize textures at multiple scales The performance of wavelet packet spaces are measured in terms of sensitivity and selectivity for the classification of twenty-five natural textures Both energy and entropy metrics were computed for each wavelet packet and incorporated into distinct scale space representations, where each wavelet packet (channel) reflected a specific scale and orientation sensitivity Wavelet packet representations for twenty-five natural textures were classified without error by a simple two-layer network classifier An analyzing function of large regularity (D/sub 20/) was shown to be slightly more efficient in representation and discrimination than a similar function with fewer vanishing moments (D/sub 6/) In addition, energy representations computed from the standard wavelet decomposition alone (17 features) provided classification without error for the twenty-five textures included in our study The reliability exhibited by texture signatures based on wavelet packets analysis suggest that the multiresolution properties of such transforms are beneficial for accomplishing segmentation, classification and subtle discrimination of texture >

Herbicide resistant fertile transgenic wheat plants obtained by microprojectile bombardment of regenerable embryogenic callus

Abstract: Herbicide Resistant Fertile Transgenic Wheat Plants Obtained by Microprojectile Bombardment of Regenerable Embryogenic Callus

S-parameter-based IC interconnect transmission line characterization

Abstract: A methodology for extracting high-frequency IC interconnect transmission parameters directly from S-parameter measurements has been demonstrated using on-chip test structures. The methodology consists of: (1) building on-chip interconnect structures for microwave test, (2) characterizing and subtracting measurement system parasitics, (3) extracting the transmission line impedance and propagation constant (attenuation constant and phase constant) from the calibrated data, and (4) extracting the Telegrapher's Equation transmission parameters (R, L, C, and G). Additional on-chip calibration permits subtraction of pad parasitic effects. This methodology is demonstrated over a 45-MHz to 20-GHz frequency range using an example 1-cm-long, 4- mu m-wide IC interconnect built in an advanced BiCMOS technology. Variations in interconnect impedance and capacitance indicate two signal propagation modes. Significant substrate-based loss is measured at microwave frequencies. >

A review of production planning and scheduling models in the semiconductor industry part i: system characteristics, performance evaluation and production planning

Abstract: Although the national importance of the semiconductor industry is widely acknowledged, it is only recently that the production planning and scheduling problems encountered in this environment have begun to be addressed using industrial engineering and operations research.techniques. These problems have several features that make them difficult and challenging: random yields and rework, complex product flows, and rapidly changing products and technologies. Hence their solution will contribute considerably to die theory and practice of production planning and control. In a two-part project we present a review of research in this area to date, discuss the applicability of the various approaches and suggest directions for future research. In this paper, Part I, we describe the characteristics of the semiconductor manufacturing environment and review models related to performance evaluation and production planning. Part II will review research on shop-floor control in this industry to date.

Genetic search strategies in multicriterion optimal design

Abstract: The present paper describes an implementation of genetic search methods in multicriterion optimal designs of structural systems with a mix of continuous, integer and discrete design variables. Two distinct strategies to simultaneously generate a family of Pareto optimal designs are presented in the paper. These strategies stem from a consideration of the natural analogue, wherein distinct species of life forms share the available resources of an environment for sustenance. The efficacy of these solution strategies are examined in the context of representative structural optimization problems with multiple objective criteria and with varying dimensionality as determined by the number of design variables and constraints.

Nitric oxide synthase in macula densa regulates glomerular capillary pressure

Abstract: Tubular-fluid reabsorption by specialized cells of the nephron at the junction of the ascending limb of the loop of Henle and the distal convoluted tubule, termed the macula densa, releases compounds causing vasoconstriction of the adjacent afferent arteriole. Activation of this tubuloglomerular feedback response reduces glomerular capillary pressure of the nephron and, hence, the glomerular filtration rate. The tubuloglomerular feedback response functions in a negative-feedback mode to relate glomerular capillary pressure to tubular-fluid delivery and reabsorption. This system has been implicated in renal autoregulation, renin release, and longterm body fluid and blood-pressure homeostasis. Here we report that arginine-derived nitric oxide, generated in the macula densa, is an additional intercellular signaling molecule that is released during tubular-fluid reabsorption and counters the vasoconstriction of the afferent arteriole. Antibody to rat cerebellar constitutive nitric oxide synthase stained rat macula densa cells specifically. Microperfusion of the macula densa segment of single nephrons with N omega-methyl-L-arginine (an inhibitor of nitric oxide synthase) or with pyocyanin (a lipid-soluble inhibitor of endothelium-derived relaxation factor) showed that generation of nitric oxide can vasodilate the afferent arteriole and increase glomerular capillary pressure; this effect was blocked by drugs that prevent tubular-fluid reabsorption. We conclude that nitric oxide synthase in macula densa cells is activated by tubular-fluid reabsorption and mediates a vasodilating component to the tubuloglomerular feedback response. These findings imply a role for arginine-derived nitric oxide in body fluid-volume and blood-pressure homeostasis, in addition to its established roles in modulation of vascular tone by the endothelium and in neurotransmission.

Inhibition of enzymatic browning in foods and beverages

Abstract: Enzymatic browning is a major factor contributing to quality loss in foods and beverages. Sulfiting agents are used commonly to control browning; however, several negative attributes associated with sulfites have created the need for functional alternatives. Recent advances in the development of nonsulfite inhibitors of enzymatic browning are reviewed. The review fouses on compositions that are of practical relevance to food use.

Efficient algorithms for scheduling semiconductor burn-in operations

Abstract: In this paper, we study the problem of scheduling semiconductor burn-in operations, where burn-in ovens are modeled as batch processing machines. A batch processing machine is one that can process up to B jobs simultaneously. The processing time of a batch is equal to the largest processing time among all jobs in the batch. We present efficient dynamic programming-based algorithms for minimizing a number of different performance measures on a single batch processing machine. We also present heuristics for a number of problems concerning parallel identical batch processing machines and we provide worst case error bounds.

Factors that affect ovarian follicular dynamics in cattle.

Abstract: Studies of ovarian follicular dynamics in cattle may lead to methods for improving fertility, for synchronizing estrus with more precision, and for enhancing superovulatory responses. Within an estrous cycle, two or three large (> 10 mm) follicles develop during consecutive waves of follicular growth. The last wave provides the ovulatory follicle, whereas preceding wave(s) provide follicles that undergo atresia. The life span of large follicles seems to depend on the pulsatile secretion of LH; decreased frequency of LH pulses results in atresia of large follicles. Aromatase activity in the walls of the largest follicles is greatest during the first 8 d of the estrous cycle and decreases by d 12. Steroidogenesis of the largest and second-largest ovarian follicles differs on d 5, 8, and 12 of the estrous cycle. Follicular dynamics are altered by negative energy balance and lactation. The number of large follicles and concentration of estradiol during the preovulatory period differs between postpartum lactating and nonlactating cows. Dietary fats stimulate follicular growth when they are fed to increase energy balance. Administration of bovine somatotropin decreases energy balance and has a differential effect on ovarian follicular responses; growth of the largest follicle does not change, but growth of the second-largest follicle is stimulated by somatotropin. Studies of follicular dynamics in lactating cows demonstrate changes in ovarian function associated with energy balance that may be related to inefficient reproductive performance of cows producing high yields of milk.

Transgenic mice lacking class I major histocompatibility complex-restricted T cells have delayed viral clearance and increased mortality after influenza virus challenge.

Abstract: To investigate the role of CD8+ T lymphocytes in recovery from influenza pneumonia, we used transgenic mice either homozygous (-/-) or heterozygous (+/-) for beta 2-microglobulin (beta 2-M) gene disruption. These mice lack major histocompatibility complex-restricted class I (CD8+) T cells. We found that after challenge with a nonlethal influenza virus, the beta 2-M (-/-) mice had significantly delayed pulmonary viral clearance. Furthermore, after challenge with a more virulent influenza virus, the beta 2-M (-/-) mice had a significantly higher mortality rate than did control mice. Thus, CD8+ T cells are important in recovery from virulent influenza infections, but other host defense mechanisms can clear the respiratory tract of more benign infections.

The ACES II program system

Abstract: ACES II, a new program system for ab initio electronic structure calculations is described. The strengths of ACES II involve the use of many-body perturbation theory (MBPT) and coupled-cluster (CC) theory for calculating the energy, geometry, spectra, and properties of small- to medium-sized molecules. This paper gives a brief overview of the ACES II project, describes many features of the program system, and documents a number of benchmark calculations. © 1992 John Wiley & Sons, Inc.

Sucrose Phosphate Synthase and Sucrose Accumulation at Low Temperature

Abstract: The influence of growth temperature on the free sugar and sucrose phosphate synthase content and activity of spinach (Spinacia oleracea) leaf tissue was studied. When plants were grown at 25 degrees C for 3 weeks and then transferred to a constant 5 degrees C, sucrose, glucose, and fructose accumulated to high levels during a 14-d period. Predawn sugar levels increased from 14- to 20-fold over the levels present at the outset of the low-temperature treatment. Sucrose was the most abundant free sugar before, during, and after exposure to 5 degrees C. Leaf sucrose phosphate synthase activity was significantly increased by the low-temperature treatment, whereas sucrose synthase and invertases were not. Synthesis of the sucrose phosphate synthase subunit was increased during and after low-temperature exposure and paralleled an increase in the steady-state level of the subunit. The increases in sucrose and its primary biosynthetic enzyme, sucrose phosphate synthase, are discussed in relation to adjustment of metabolism to low nonfreezing temperature and freezing stress tolerance.

Rhodopsin and phototransduction: a model system for G protein-linked receptors.

Abstract: Rhodopsin is the photoreceptor protein in rod cells of the vertebrate retina and the first member of the class of G protein-coupled receptors for which the amino acid sequence was determined. Rhodopsin is available in greater quantities than any other receptor of its class and therefore has been studied biochemically and biophysically by methods difficult or impossible to apply to its fellow receptors. Such studies support a model in which rhodopsin consists of seven transmembrane helices that form a binding pocket for its ligand, 11-cis retinal. Insights into the structure and function of rhodopsin serve as a model for understanding the structure and function of other members of the receptor class. Rhodopsin undergoes a change in conformation upon photoexcitation and activates a G protein, transducin, and is phosphorylated by a receptor-specific kinase, rhodopsin kinase. The phosphorylated photoactivated rhodopsin is bound by arrestin, thereby terminating activity of the receptor in the signal transducti...

Renormalization-group study of the standard model and its extensions: The standard model.

Abstract: In this paper we present a comprehensive analysis of the running of all the couplings of the standard model to two loops, including threshold effects. Our purpose is twofold---to determine what the running of these parameters may indicate for the physics of the standard model and to provide a template for the study of its extensions up to the Planck mass.

Nocturia: a risk factor for falls in the elderly

Abstract: OBJECTIVE: To determine if nocturia is a risk factor for reported falls and bone fractures in older persons. DESIGN: Cross-sectional study comparing falls in men and women with and without nocturia. SETTING: Longitudinal health screening program of ambulatory elderly participants. PARTICIPANTS: Participants included 988 (65.5%) women and 520 (34.5%) men who had completed their tenth annual visit to the program. MAIN OUTCOME MEASURES: Reported falls in the past year and reported bone fractures in the past 5 years. RESULTS: Participants who reported nocturia at least twice during the night were at significantly greater risk to report falls (Odds Ratio = 1.84; 95% CI = 1.05-3.22), and the risk increased in subjects reporting more than three nocturia events (Odds Ratio = 2.15; 95% CI = 1.04-4.44). The significant increase in falls reported by nocturia participants did not result in an increase in reported bone fractures in the past 5 years (P Language: en

Narrow‐band sound localization related to external ear acoustics

Abstract: Human subjects localized brief 1/6‐oct bandpassed noise bursts that were centered at 6, 8, 10, and 12 kHz. All testing was done under binaural conditions. The horizontal component of subjects’ responses was accurate, comparable to that for broadband localization, but the vertical and front/back components exhibited systematic errors. Specifically, responses tended to cluster within restricted ranges that were specific for each center frequency. The directional transfer functions of the subjects’ external ears were measured for 360 horizontal and vertical locations. The spectra of the sounds that were present in the subjects’ ear canals, the ‘‘proximal stimulus’’ spectra, were computed by combining the spectra of the narrow‐band sound sources with the directional transfer functions for particular stimulus locations. Subjects consistently localized sounds to regions within which the associated directional transfer function correlated most closely with the proximal stimulus spectrum. A quantitative model was constructed that successfully predicted subjects’ responses based on interaural level difference and spectral cues. A test of the model, using techniques adapted from signal detection theory, indicated that subjects tend to use interaural level difference and spectral shape cues independently, limited only by a slight spatial correlation of the two cues. A testing procedure is described that provides a quantitative comparison of various predictive models of sound localization.

Low conductances for CO2 diffusion from stomata to the sites of carboxylation in leaves of woody species

Abstract: Concurrent measurements of leaf gas exchange and on-line 13C discrimination were used to evaluate the CO2 conductance to diffusion from the stomatal cavity to the sites of carboxylation within the chloroplast (internal conductance; gi). When photon irradiance was varied it appeared that gi and/or the discrimination accompanying carboxylation also varied. Despite this problem, gi, was estimated for leaves of peach (Prunus persica), grapefruit (Citrus paradisi), lemon (C. limon) and macadamia (Macadamia integrifolia) at saturating photon irradiance. Estimates for leaves of C. paradisi, C. limon and M. integrifolia were considerably lower than those previously reported for well-nourished herbaceous plants and ranged from 1.1 to2.2μmol CO2 m−2 s−1 Pa−1, whilst P. persica had a mean value of 3.5 μmol CO2 m−2 s−1 Pa−1. At an ambient CO2 partial pressure of 33Pa, estimates of chloroplastic partial pressure of CO2 (Cc) using measurements of CO2 assimilation rate (A) and calculated values of gi, and of partial pressure of CO2 in the stomatal cavity (Cst) were as low as 11.2 Pa for C. limon and as high as 17.8Pa for peach. In vivo maximum rubisco activities (Vmax) were also determined from estimates of Cc. This calculation showed that for a given leaf nitrogen concentration (area basis) C. paradisi and C. limon leaves had a lower Vmax than P. persica, with C. paradisi and C. limon estimated to have only 10% of leaf nitrogen present as rubisco. Therefore, low CO2 assimilation rates despite high leaf nitrogen concentrations in leaves of the evergreen species examined were explained not only by a low Cc but also by a relatively low proportion of leaf nitrogen being used for photosynthesis. We also show that simple one-dimensional equations describing the relationship between leaf internal conductance from stomatal cavities to the sites of carboxylation and carbon isotope discrimination (Δ) can lead to errors in the estimate of gi. Potential effects of heterogeneity in stomatal aperture on carbon isotope discrimination may be particularly important and may lead to a dependence of gi upon CO2 assimilation rate. It is shown that for any concurrent measurement of A and Δ, the estimate of Cc is an overestimate of the correct photosynthetic capacity-weighted value, but this error is probably less than 1.0 Pa.

The CLEO-II detector

Abstract: The new detector for data recording by the CLEO collaboration at the Cornell Electron Storage Ring is described. This detector has been designed to optimize studying e+ e− annihilation into hadronic matter at a total energy of 10 GeV. It consists of high precesion charged particle tracking chambers and an electromagnetic calorimeter together with systems for particle identification. The design of the detector and its performance over the first year and a half of operation are presented.

The Maize Invertase-Deficient miniature-1 Seed Mutation Is Associated with Aberrant Pedicel and Endosperm Development.

Abstract: Genetic evidence is presented to show that the developmental stability of maternal cells in the pedicel at the base of maize seeds is determined by the genotype of the developing endosperm. An early degeneration and withdrawal of maternal cells from the endosperm of homozygous miniature (mn mn) seed mutants were arrested if mn plants were pollinated by the wild-type Mn pollen. Similarly, the stability of the wild-type, Mn mn, maternal cells was also dependent on whether or not these cells were associated with the normal (Mn) or the mutant (mn) endosperm on the same ear. Biochemical and cellular analyses indicated that developing mn kernels have extremely low (<0.5% of the wild type) to undetectable levels of both soluble and wall-bound invertase activities. Extracts from endosperm with a single copy of the Mn gene showed a significant increase in both forms of invertases, and we suggest it is the causal basis of the wild-type seed phenotype. Collectively, these data provide evidence that invertase-mediated maintenance of a physiological gradient of photosynthate between pedicel and endosperm constitutes the rate-limiting step in structural stability of maternal cells as well as normal development of endosperm and seed.

A controlled clinical trial of dichloroacetate for treatment of lactic acidosis in adults. The Dichloroacetate-Lactic Acidosis Study Group.

Abstract: Background. Mortality is very high in lactic acidosis, and there is no satisfactory treatment other than treatment of the underlying cause. Uncontrolled studies have suggested that dichloroacetate, which stimulates the oxidation of lactate to acetyl-coenzyme A and carbon dioxide, might reduce morbidity and improve survival among patients with this condition. Methods. We conducted a placebo-controlled, randomized trial of intravenous sodium dichloroacetate therapy in 252 patients with lactic acidosis; 126 were assigned to receive dichloroacetate and 126 to receive placebo. The entry criteria included an arterial-blood lactate concentration of ≥5.0 mmol per liter and either an arterial-blood pH of ≤7.35 or a base deficit of ≥6 mmol per liter. The mean (±SD) arterial-blood lactate concentrations before treatment were 11.6±7.0 mmol per liter in the dichloroacetate-treated patients and 10.4±5.5 mmol per liter in the placebo group, and the mean initial arterial-blood pH values were 7.24±0.12 and 7.24±0...

Five-Minute Treatments With Fluorouracil, Floxuridine, and Mitomycin Have Long-term Effects on Human Tenon's Capsule Fibroblasts

Abstract: • Proliferating human Tenon's capsule fibroblasts were exposed for 5 minutes to a wide range of concentrations of fluorouracil, floxuridine, and mitomycin. High concentrations of all three agents had prolonged effects on cell proliferation and morphologic characteristics compared with untreated control cells up to 36 days. The highest concentrations of both floxuridine (15000 μg/mL) and mitomycin (1000 μ g mL) had an apparent cidal effect, reducing cell numbers below initial cell density. In contrast, although the highest concentration of fluorouracil (25000 μg/mL) inhibited cell proliferation by more than 50% relative to the untreated control cells at 36 days, the cell numbers still increased fourfold compared with the initial cell density. These results demonstrate that 5-minute treatments with high concentrations of these drugs have prolonged effects on the proliferation of human Tenon's capsule fibroblasts in vitro. Single-dose regimens using high concentrations of these drugs at the time of operation may achieve results similar to those of protocols that involve repeated applications.

The Viviparous-1 gene and abscisic acid activate the C1 regulatory gene for anthocyanin biosynthesis during seed maturation in maize.

Abstract: The Viviparous-1 (Vp1) gene is required for expression of the C1 regulatory gene of the anthocyanin pathway in the developing maize seed. We show that VP1 overexpression and the hormone, abscisic acid (ABA), activate a reporter gene driven by the C1 promoter in maize protoplasts. Cis-acting sequences essential for these responses were localized. Mutation of a conserved sequence in the C1 promoter abolishes both ABA regulation and VP1 trans-activation. An adjacent 5-bp deletion blocks ABA regulation but not VP1 trans-activation. The latter mutant reconstructs the promoter of c1-p, an allele that is expressed during seed germination but not during seed maturation. We suggest that VP1 activates C1 specifically during maturation by interacting with one or more ABA-regulated transcription factors.