Showing papers by "Louisiana State University published in 1983"

Negative Word-of-Mouth by Dissatisfied Consumers: A Pilot Study:

Abstract: While marketing scholars have emphasized the importance of customer satisfaction, few studies have examined in detail consumers’ responses to dissatisfaction. This study examines correlates of one ...

Markov Random Field Texture Models

Abstract: We consider a texture to be a stochastic, possibly periodic, two-dimensional image field. A texture model is a mathematical procedure capable of producing and describing a textured image. We explore the use of Markov random fields as texture models. The binomial model, where each point in the texture has a binomial distribution with parameter controlled by its neighbors and ``number of tries'' equal to the number of gray levels, was taken to be the basic model for the analysis. A method of generating samples from the binomial model is given, followed by a theoretical and practical analysis of the method's convergence. Examples show how the parameters of the Markov random field control the strength and direction of the clustering in the image. The power of the binomial model to produce blurry, sharp, line-like, and blob-like textures is demonstrated. Natural texture samples were digitized and their parameters were estimated under the Markov random field model. A hypothesis test was used for an objective assessment of goodness-of-fit under the Markov random field model. Overall, microtextures fit the model well. The estimated parameters of the natural textures were used as input to the generation procedure. The synthetic microtextures closely resembled their real counterparts, while the regular and inhomogeneous textures did not.

A Theoretical Model for the Study of Product Importance Perceptions

Abstract: Product importance and related constructs have been inadequately defined and understood in the consumer behavior literature. This paper reviews and integrates these constructs and presents a framew...

Cortical dopaminergic involvement in cocaine reinforcement

Abstract: Neuronal systems involved in the initiation of cocaine reinforcement were investigated by identifying brain sites where direct application of the drug was reinforcing. This was accomplished by allowing rats to self-administer picomolar concentrations of cocaine into discrete brain regions. The medial prefrontal cortex supported self-administration, while the nucleus accumbens and ventral tegmental area did not. Self-administration could be attenuated by including equimolar concentrations of the dopaminergic D2-receptor antagonist sulpiride in the microinjection system. These results imply that cocaine reinforcement is mediated in part through a direct action on mesocortical dopaminergic receptors.

Sedimentation, accretion, and subsidence in marshes of Barataria Basin, Louisiana1

Abstract: Vertical accretion and sediment accumulation rates were determined from the distribution of 137Cs in cores collected from freshwater, intermediate, brackish, and salt marshes in the Barataria Basin, Louisiana. Vertical accretion rates vary from about 1.3 cm*yr-l in levee areas to 0.7 in backmarshes. Mineral sediment content of the marsh soil profile decreased with distance from the coast. However, vertical accretion rates were about equivalent in areas of the same type. Autochthonous organic matter appears to be an important factor defining the process and rate of vertical accretion, especially in the freshwater marshes. Except in natural levee areas, marsh accretion rates are less than subsidence measured by water level data, however this alone cannot account for observed land-loss patterns in the basin area.

The Radicals in Cigarette Tar: Their Nature and Suggested Physiological Implications

Abstract: The paramagnetism of cigarette tar is found to be associated with at least four different types of species. One of the types is responsible for over 80 percent of the total paramagnetism and has a signal intensity that is independent of temperature from 60 to 250 K. This non-Curie-Weiss temperature dependence indicates that the principal paramagnetic species in tar is not an organic monoradical (doublet) species but instead is a donor-acceptor excimer with a paramagnetic excited state and a diamagnetic ground state. Modeling experiments suggest that the excimer consists of quinone (Q) and hydroquinone (QH2) molecules held in a tar matrix. Since such Q-QH2 species are catalysts for the oxidation of hydrocarbons and are very active redox systems, this paramagnetic species may be implicated in the cocarcinogenic properties of tar. Alternatively, since semiquinone radicals are known to bind to DNA, the tar paramagnetic species may be directly involved in the carcinogenic properties of tar.

Identifying and Locating Surface Defects in Wood: Part of an Automated Lumber Processing System

Abstract: Continued increases in the cost of materials and labor make it imperative for furniture manufacturers to control costs by improved yield and increased productivity This paper describes an Automated Lumber Processing System (ALPS) that employs computer tomography, optical scanning technology, the calculation of an optimum cutting strategy, and a computer-driven laser cutting device While certain major hardware components of ALPS are already commercially available, a major missing element is the automatic inspection system needed to locate and identify surface defects on boards This paper reports research aimed at developing such an inspection system The basic strategy is to divide the digital image of a board into a number of disjoint rectangular regions and classify each independently This simple procedure has the advantage of allowing an obvious parallel processing implementation The study shows that measures of tonal and pattern related qualities are needed The tonal measures are the mean, variance, skewness, and kurtosis of the gray levels The pattern related measures are those based on cooccurrence matrices In this initial feasibility study, these combined measures yielded an overall 883 percent correct classification on the eight defects most commonly found in lumber To minimize the number of calculations needed to make the required classifications a sequential classifier is proposed

Age-related and seasonal variation in the Sertoli cell population, daily sperm production and serum concentrations of follicle-stimulating hormone, luteinizing hormone and testosterone in stallions.

Abstract: Testes and blood samples were obtained from 201 stallions aged 6 months to 20 years in either December-January (nonbreeding season) or June-July (breeding season) to study the effect of age and season on reproductive parameters. Seasonal differences in the Sertoli cell population of adult (4-20 years old) horses were characterized by a 36% larger number of Sertoli cells in the breeding season than in the nonbreeding season. Seasonal elevation in the Sertoli cell population was associated with an increase in testicular weight and daily sperm production per testis (DSP/testis). Concentrations of luteinizing hormone (LH) and testosterone in serum varied with season. Although follicle-stimulating hormone (FSH) concentrations also tended to be higher in the breeding season, this trend was not statistically significant (P less than 0.08). Sertoli cell numbers averaged over both seasons, like testicular weights, increased with age until 4-5 years of age, but were stabilized thereafter. This age-related difference was also associated with increased concentrations of FSH, LH and testosterone, and with increased DSP/testis. The Sertoli cell population was capable of increasing in the adult horse by fluctuating its size with season. The number of elongated spermatids per Sertoli cell over both seasons increased with age up to 4-5 years of age and was stabilized thereafter. Thus, seasonal and/or age-related differences in DSP/testis were associated with significant elevations in serum concentrations of FSH, LH and testosterone, testicular weights, numbers of elongated spermatids per Sertoli cell and elevation of the Sertoli cell population.

Alligator Metabolism Studies on Chemical Reactions in Vivo

Abstract: Bring home now the book enPDFd alligator metabolism studies on chemical reactions in vivo thomas hernandez to be your sources when going to read. It can be your new collection to not only display in your racks but also be the one that can help you fining the best sources. As in common, book is the window to get in the world and you can open the world easily. These wise words are really familiar with you, isn't it?

The sex-linked recessive lethal test for mutagenesis in Drosophila melanogaster: A report of the U.S. environmental protection agency Gene-Tox program

Abstract: The test for sex-linked recessive lethals (SLRL) in Drosophila melanogaster has been used to detect induced mutations since 1927. The advantage of the test for both screening and hazard evaluation is its objectivity in testing for transmissible mutations in the germ cells of a eukaryote. Statistical criteria for both positive and negative mutagenicity at the highest concentration tested under a particular exposure condition were developed by the Work Group, and a recommended protocol for future testing was agreed upon. For 421 compounds there were sufficient data available in the literature for analysis; 198 compounds were found to be positive and 46 negative at the highest concentration tested. Most experiments had been done for objectives of pure research rather than for deliberately screening for mutagenicity, although many of the 421 chemicals were selected for testing because of suspected mutagenicity. Therefore, the statement of 198 positive and 46 negative should not be taken as an example of the proportion of mutagens in the environment. In three sets of experiments with D. melanogaster that were done specifically for screening, one involving 40 compounds for the Environmental Protection Agency (EPA), the others involving 13 for the Food and Drug Administration (FDA), only 6 mutagens were discovered. After completion of the classification of compounds according to their response in the SLRL test, the compounds were classified as to their carcinogenic response according to the list of Griesemer and Cueto (1980). There were 62 compounds that could be classified as positive or negative for both carcinogenesis and mutagenesis. Of the 62 compounds, there was agreement between the carcinogenesis and mutagenesis classification in 56 (50 positive and 6 negative), or 90% would have been correctly classified as to carcinogenesis from only the SLRL test. Because of inadequate sample size, 177 compounds could not be classified as positive or negative according to the statistical criteria established by the Work Group. This large number of inadequately tested compounds reflects the fact that many of the experiments were not done for screening. Further work is needed on the compounds with inadequate sample size.(ABSTRACT TRUNCATED AT 400 WORDS)

Methane release from Gulf coast wetlands

Abstract: A seasonal study of methane release from adjoining salt, brackish and fresh marsh sediment andthe adjacent open water areas in Louisiana’s Barataria Basin indicates that methane emission isa significant process in the carbon and energy flow of the ecosystem. Methane emission wasinversely related to salinity and sulfate concentration, with methane increasing and salinity andsulfate decreasing with increasing distance from the coast. The annual amounts of methaneevolved were 4.3, 73 and 160 g C m -2 for the salt, brackish and fresh marshes, respectively. Invitro experiments show that methane production is sensitive to the addition of sulfate, highconcentrations (10 mM SO,) inhibiting methane evolution. DOI: 10.1111/j.1600-0889.1983.tb00002.x

Lattice-parameter dependence of ferromagnetism in bcc and fcc iron

Abstract: A series of self-consistent-band calculations have been performed for a ferromagnetic state of iron in both the bcc and fcc structures. The dependence of the magnetic moment per atom on the lattice parameter was obtained. The linear combination of Gaussian orbitals method was employed in conjunction with a local-density exchange-correlation potential. An explanation is given for the abrupt increase in the magnetic moment in the fcc case near ${r}_{s}=2.7$ in terms of behavior of the band structure.

Bacterial translocation from the gastrointestinal tracts of mice receiving immunosuppressive chemotherapeutic agents

Abstract: Specific pathogen-free (SPF) mice were treated with certain classes of immunosuppressive chemotherapeutic agents to determine if they would promote bacterial translocation from the gastrointestinal tract to the mesenteric lymph node, spleen, or liver. The antimetabolites methotrexate, 5-fluorouracil, and cytosine arabinoside were injected once intraperitoneally into SPF mice, and the mice were tested for bacterial translocation from the gastrointestinal tract. When total organs from the treated mice were compared with the total organs from the control mice, the alkylating agent cyclophosphamide promoted bacterial translocation when injected once intraperitoneally at doses of 100–400 mg/kg. Increasing the number of injections of cyclophosphamide did not increase the incidence of bacterial translocation. The steroid prednisone also promoted bacterial translocation after one intraperitoneal injection of 10–150 mg/kg. Prednisone and cyclophosphamide at various doses appeared to be more effective in promoting bacterial translocation from the gastrointestinal tract than the antimetabolites. The aerobic and facultatively anaerobic bacteria translocating to the various organs were identified asLactobacillus acidophilus, Escherichia coli, Klebsiella pneumoniae, Streptococcus faecalis, Staphylococcus aureus, andProteus mirabilis. Groups of SPF mice also were injected once intraperitoneally with the minimal dose of each chemotherapeutic drug that induced bacterial translocation, and then tested for immune responsiveness toE. coli vaccination. Each of the chemotherapeutic agents at the minimal doses promoting bacterial translocation also suppressed the serum antibody responses to antigens of indigenousE. coli. However, other toxic manifestations of these chemotherapeutic agents also may be involved in promoting bacterial translocation. The promotion of bacterial translocation from the gastrointestinal tract by these chemotherapeutic agents has important implications for the pathogenesis of infectious disease in patients receiving these drugs.

The effect of malonyldialdehyde, a product of lipid peroxidation, on the deformability, dehydration and 51Cr-survival of erythrocytes.

Abstract: Summary. Erythrocyte membrane lipid peroxidation has been reported to occur in various haemolytic anaemias. In the present study, treatment of human erythrocytes with malonyldialdehyde (MDA). a product of fatty acid peroxidation, induced membrane rigidity, cellular dehydration and reduced whole cell deformability. These effects of MDA were blocked by histamine and fluorescamine, which can act as alternate substrates for MDA. Additionally, reduced deformability of MDA-treated rabbit cells was associated with shortened 51Cr survival in vivo. These findings suggest a biochemical basis for decreased survival of erythrocytes undergoing peroxidative damage of the membrane.

Biomechanics of Cranial Cruciate Ligament Reconstruction in the Dog II. Mechanical Properties

Abstract: A biomechanical analysis of the results of an over-the-top procedure for replacement of the cranial cruciate ligament (CCL) in the dog is presented. Using 15 adult mongrel dogs, the CCL in one stifle joint was reconstructed using fascia lata and the lateral one-third of the patellar ligament. The opposite CCL served as the control. Animals were sacrificed at 0, 4, 12 and 26 weeks postoperation and axial failure tests were performed. Stiffness, maximum load, and elastic modulus of the replacement increased over time, while elongation to maximum load continually decreased as compared to controls. Other parameters showed less consistent trends. The results are encouraging given the reduction in joint laxity and the increases in tissue stiffness and strength. However, the ligament substitute was still unable to replicate the mechanical properties of the normal cruciate ligament. Longer studies therefore are required to determine if this replacement is capable of completely restoring joint stability and normal function.

Fuzzy sets and generalized Boolean retrieval systems

Abstract: Substantial work has been done on the application of fuzzy subset theory to information retrieval. Boolean query processing has been generalized to allow for weights to be attached to individual terms, in either the document indexing or the query representation, or both. Problems with the generalized Boolean lattice structure have been noted, and an alternative approach using query thresholds and appropriate document evaluation functions has been suggested. Problems remain unsolved, however. Criteria generated for the query processing mechanism are inconsistent. The exact functional form and appropriate parameters for the query processing mechanism must be specified. Moreover, the generalized Boolean query model must be reconciled with the vector space approach, suggested new lattice structures for weighted retrieval, and probabilistic retrieval models. Finally, proper retrieval evaluation mechanisms reflecting the fuzzy nature of retrieval are needed.

Isolation of a Pseudomonas sp. Which Utilizes the Phosphonate Herbicide Glyphosate.

Abstract: A strain of bacteria has been isolated which rapidly and efficiently utilizes the herbicide glyphosate (N-phosphonomethylglycine) as its sole phosphorus source in a synthetic medium. The strain (PG2982) was isolated by subculturing Pseudomonas aeruginosa ATCC 9027 in a synthetic broth medium containing glyphosate as the sole phosphorus source. Strain PG2982 differs from the culture of P. aeruginosa in that it is nonflagellated, does not produce pyocyanin, and has an absolute requirement for thiamine. Strain PG2982 has been tentatively identified as a Pseudomonas sp. strain by its biochemical activities and moles percent guanine plus cytosine. Measurements of glyphosate with an amino acid analyzer show that glyphosate rapidly disappears from the medium during exponential growth of strain PG2982. In batch culture at 30 degrees C, this isolate completely utilized 1.0 mM glyphosate in 96 h and yielded a cell density equal to that obtained with 1.0 mM phosphate as the phosphorus source. However, a longer lag phase and greater generation time were noted in the glyphosate-containing medium. Strain PG2982 can efficiently utilize glyphosate as an alternate phosphorus source.

Displacements on late Cenozoic strike-slip faults of the central Mojave Desert, California

Abstract: Field studies demonstrate that displacements on northwest-striking wrench faults of the central Mojave Desert are too small to support hypotheses suggesting large interior translations and associated rotation of the province during late Cenozoic time. The margin of an early Miocene structural belt provides the marker with which to establish lateral displacement on individual faults. Displacement values for faults are as follows: Lenwood fault = 1.5–3 km, Camp Rock Fault = 1.6–4.0 km, Calico fault = 8.2 km, and Rodman-Pisgah faults = 6.4–14.4 km. Cumulative displacement on all the major northwest-striking faults of the Mojave Desert is about 26.7–38.4 km. Most, if not all, regionally distributed right shear (presumably related to Pacific–North American plate interaction) developed in the central Mojave Desert after 20 m.y. B.P. Right shear was preceded by significant amounts of kinematically unrelated northeast-southwest crustal extension.

The relationship of student characteristics and student performance in science as viewed by meta‐analysis research

Abstract: Relationships of student characteristics to student performance and attitudes were explored by meta-analysis for studies conducted in kindergarten through twelfth grade since 1960. Six student characteristics (general ability, language ability, mathematics ability, socio-economic status, gender, and race) were selected for inclusion in this investigation based on their frequency of use in the literature. Studies in which these student characteristics were associated with student science performance or science attitudes were included in this investigation. Associations of ability and socio-economic status with science performance and attitudes were summarized by correlational analysis. An effect size measure was used to summarize associations of gender and race with science performance and attitudes.

The chloride corrosion behaviour of four orthodontic wires.

Abstract: Potentiodynamic cyclic polarization of four orthodontic alloys (wires), namely Permachrome, Elgiloy, a beta-titanium alloy and Nitinol in a 1% NaCl solution within -500 mV and +300 mV (SCE) indicated the first three alloys to be passive whereas breakdown of passivity was observed on Nitinol. The SEM examination of the pre- and post-polarized alloy surfaces provided evidence which was consistent with the electrochemical measurements, in that the first three alloys exhibited no appreciable corrosion damage whereas pitting corrosion was observed on Nitinol. The results obtained from X-ray analysis of the pitted surface indicated that this pitting could be due to selective dissolution of nickel from Nitinol.

Biochemical and immunological systematics of the order crocodilia

Abstract: Attempts to assess the natural affinities and evolution of living crocodilians have been difficult and largely contradictory (Kalin, 1955; Steel, 1973; Dowling and Duellman, 1974). Morphological character analysis has been misleading due to the overall conservatism of these reptiles and to the tendencies toward parallelism and convergence of traits that has occurred during their evolution (Langston, 1973). These complications, together with the lack of critical fossils, have made paleontological interpretations extremely difficult (Sill, 1968; Hecht and Malone, 1972; Langston, 1973; Buffetaut, 1979). Because of such problems and the small number of living species, morphoclines are rare, further complicating the efforts of the comparative morphologist (Hecht and Malone, 1972).