Showing papers by "Mississippi State University published in 1993"

The Habitat Concept in Ornithology

Abstract: Ornithologists have played a key role in the development of the habitat concept. The conspicuous nature of birds has allowed ornithologists to assemble a vast amount of information relating the distribution and abundance of birds to aspects of the environment (Brown, 1984; Mayr, 1988; Konishi et al., 1989; Morrison et al., 1992). The application of the term “habitat” has been used as a unifying, theoretical concept to explain the diversity of avian life-history patterns (Rotenberry, 1981). However, specific definitions of the term “habitat” are often vague. Definitions have ranged from, for example, how species are associated with broad, landscape-scaled vegetation types, to very detailed descriptions of immediate physical environments used by species (Karr, 1980; Verner et al., 1986; Harris and Kangas, 1988).

The structure of aniline by ab initio studies

Abstract: The structure of aniline has been studied by ab initio calculations. Complete geometry optimization of (1) the energy minimum structure and the transition states for (2) internal rotation and (3) inversion of the amino group were carried out at the SCF level using several different basis sets. For these three stationary geometries vibrational frequencies were calculated at the SCF/6-31G∗∗ level. The effect of electron correlation was estimated by single point MP4(SDQ) calculations using the 6-311G∗∗ basis set. To satisfactorily describe the conformation and orientation of the amino group a fully polarized (6-31G∗∗) basis set is required. It is predicted that the aniline molecule has a pyramidal amino group with an angle between the C-N bond and the NH2 plane of 42.3°. The angle between the C-N bond and the plane of the benzene ring is 2.0°. The barriers to inversion and internal rotation of the amino group are estimated to be 1.7 and 3,7 kcal mol− respectively.

Curvature approximation for triangulated surfaces

Abstract: Given a set of points and normals on a surface and a triangulation associated with them a simple scheme for approximating the principal curvatures at these points is developed. The approximation is based on the fact that a surface can locally be represented as the graph of a bivariate function. Quadratic polynomials are used for this local approximation. The principal curvatures at a point on the graph of such a quadratic polynomial is used as the approximation of the principal curvatures at an original surface point.

Physician's Guide to Arthropods of Medical Importance

Abstract: Part I: Pathological Conditions Caused by Arthropods. Principles of Treatment of Arthropod Bites, Stings, etc. Allergy to Arthropods and Their Venoms. Stings. Bites. Dermatitis, Urticaria, Blistering. Myiasis. Delusions of Parasitosis. Part II: Identification of Arthropods and the Diseases They Cause. Identification of Medically Important Arthropods. Signs and Symptoms of Arthropod-borne Diseases. Part III: Arthropods of Medical Importance. Ants. Bees. Blister Beetles. Bugs (The True Bugs). Caterpillars (Urticating). Centipedes. Cockroaches. Earwigs. Fleas. Flies (Biting). Flies (Non-Biting). Flies (Which Cause Myiasis). Lice. Millipedes. Mites. Mosquitoes. Moths (Whose Scales Cause Irritation). Scorpions. Spiders. Ticks. Wasps. Part IV: Personal Protection Measures Against Arthropods. Pros and Cons of Repellents. Arthropod-Specific Personal Protection Techniques. Part V: Glossary and Index.

Decriminalization of marijuana and the demand for alcohol, marijuana and cocaine

Abstract: This study examines whether the decriminalization of marijuana in eleven states has affected self-reported usage of drugs. Generally, decriminalization is not found to significantly impact drug use. An implication is that the demand for drugs is highly inelastic with respect to incremental changes in the legal sanctions for possession of small amounts of marijuana.

Nutritional management of replacement beef heifers: a review.

Abstract: Systems to produce replacement heifers to calve initially at 2 yr of age and at 12-mo intervals thereafter require integrated forage-animal management plans. The process of developing heifers as replacements must begin during the cow-calf production phase. Age and weight at puberty are affected by several factors, including breed of livestock. Generally, breeds of a larger size at maturity are older and heavier when reaching puberty. Heifers that are kept as replacements must be weaned at relatively heavy weights in comparison to their expected mature body size without becoming obese. Excessive adipose tissue in heifers during the preweaning phase may result in reduced subsequent performance of these animals. Several management techniques were reviewed that can be used both pre- and postweaning, including using anthelmintics, anabolic growth implants, and ionophores. Anabolic growth implants can increase heifer rates of gain and increase pelvic size. In addition, there are indications that these implants may alter mammary gland development, which may subsequently increase milk production. Ionophores were shown to increase growth rates, particularly in grazing heifers but more importantly to decrease age at puberty. Age and weight at puberty have been shown to be affected by level of nutrition. It is preferable for heifers to reach puberty one or two estrous cycles before the breeding season, and the breeding season for heifers should begin > or = 21 d before the breeding season of the mature cow herd. This time difference allows for the generally longer postpartum interval for primiparous cows than for multiparous cows. Because of the limited opportunities (every 12 mo) for cows to calve, optimum efficiency must be pursued.

Toward Development of the End User Computing Construct in a University Setting

Abstract: The authors identify and define the end user computing (EUC) construct and operationalize the construct through development of a valid, reliable measure called the EUC activities scale. This scale is designed to distinguish specific, discrete computer activities performed on the job. The research analyzes the validity and reliability of the instrument based on data obtained from 776 university employees who participated in the initial, exploratory application. Exploratory factor analysis of the scale resulted in five factors. In order of increasing complexity of job-related computer activities, these factors are: beginning EUC activities, intermediate EUC activities, advanced EUC activities, EUC facilitation activities, and EUC infrastructure activities. The factor analysis, reliabilities, and known-groups analysis provide support for the construct validity of the instrument when used in a university setting. Suggestions are provided for further use of the scale in business environments to increase generalizability, refine the instrument, and help establish a coherent theoretical basis for further research in EUC.

Use of previous experience to estimate precision uncertainty of small sample experiments

Abstract: The determination of precision uncertainty is described for experiments where the test measurements are obtained from single readings or from a limited number of independent readings. For these cases, the limits of precision uncertainty are best determined from previous experience based on larger sample sizes over the full range of variations that occur for a specific test. We describe the appropriate procedures to determine the limits of precision uncertainty based on previous experience for small sample experiments. A Monte Carlo simulation technique is used to model the experiments to demonstrate the effectiveness of using the precision uncertainty to determine the range that covers the true test result

Postnatal changes in selected bacterial groups of the pig colonic microflora

Abstract: The importance of the colonic microflora in health and nutrition is well known, but how they colonize and become established in the colon is not well understood. We therefore characterized the quantitative and qualitative changes of the colonic microflora during the first 120 days of postnatal development. Unlike previous studies, changes were defined for individual pigs using in situ samples collected anaerobically and aseptically from the distal colon. Although the colons were sterile at birth, they were rapidly colonized, and within 12 h bacterial densities had stabilized at 10(-9)-10(10) bacteria/g colonic content. Facultative anaerobes, notably coliforms, initially dominated the microflora, but were supplanted within 48 h after birth by obligate anaerobes, which constituted greater than 90% of the microflora thereafter. Bacteroides spp., the predominant anaerobes in the adult colon, did not markedly increase in abundance until after weaning and were still increasing by postnatal day 120. Shifts in the relative abundances of different bacterial populations throughout the first 120 days after birth confirm previous reports that the establishment of the adult colonic microflora is a gradual, sequential process, and highlight the need to focus research on anaerobic groups.

Structure and evolution of opossum, guinea pig, and porcupine cytochrome b genes.

Abstract: We have sequenced the mitochondrial cytochrome b gene from the guinea pig, the African porcupine, and a South American opossum. A phylogenetic analysis, which includes 22 eutherian and four other vertebrate cytochrome b sequences, indicates that the guinea pig and the porcupine constitute a natural clade (Hystricomorpha) that is not a sister group to the clade of mice and rats (Myomorpha). Therefore, the hypothesis that the Rodentia is paraphyletic receives additional support. The artiodactyls, the perissodactyls, and the cetaceans form a group that is separated from the primates and the rodents. The 26 sequences are used to study the structure/function relationships in cytochrome b, whose function is electron transport. Most of the amino acid residues involved in the two reaction centers are well conserved in evolution. The four histidines that are believed to ligate the two hemes are invariant among the 26 sequences, but their nearby residues are not well conserved in evolution. The eight transmembrane domains represent some of the most divergent regions in the cytochrome b sequence. The rate of nonsynonymous substitution is considerably faster in the human and elephant lineages than in other eutherian lineages; the faster rate might be due to coevolution between cytochrome b and cytochrome c.

A Comparative Examination of Attitudes Toward Software Piracy Among Business Professors and Executives

Abstract: This study investigates attitudes toward unauthorized copying of microcomputer software, a practice which is costing the industry an estimated $800 million to $2 billion a year in lost revenue. Specifically, the copying activities of business executives are compared with those of business faculty members. Executives are found to report less unauthorized copying activities both personally and by colleagues; they also reject rationalizations for such copying. Academicians, on the other hand, tend to view unauthorized copying as being less unethical. Possible explanations for the differences between the two groups include the degree and type of job-related supervision, identification with the organization vs. the profession, and social-desirability bias. Implications of these findings and future research needs are discussed.

Ethics in accounting education: What is really being done

Abstract: Recent developments in the business world have caused the academic community to address the coverage of ethics in the accounting curriculum. This study surveyed accounting faculty to: (1) examine perceptions about ethics coverage in the undergraduate accounting courses; (2) identify teaching methods used to include ethics in the undergraduate accounting courses, the perceived effectiveness of those methods and the amount of time spent on ethics coverage; and (3) to identify problems encountered in including ethics in accounting courses. The study found that although a large majority of the professors surveyed (77%) said they include ethics, 69% felt that there was a need for more ethics coverage. Also, the study revealed that while the lecture method was the most commonly used method, the written case was deemed the most effective method. The average time spent covering ethics was a little over 3 hours per course. The most significant problems encountered by faculty who include ethics in their undergraduate accounting courses was not enough time and lack of appropriate ethics materials.

Chemical and physical characteristics of four soil types under conventional and no-tillage systems

Abstract: This study was conducted to determine how soils of different origin respond to no-till practices, with emphasis on organic C accumulation and its subsequent effect on soil properties. Tillage experiments which had been running for between 5 and 15 years on four southeastern USA soils with textures of sandy loam, loam, silt, and sandy clay loam were utilized. Soil samples were collected from conventional and no-tillage treatments at depths of 0–2.5, 2.5–7.6, and 7.6–15.2 cm. No-tillage plots had higher bulk density, aggregate stability, organic C, exchangeable cations and acidity, cation exchange capacity, and extractable P, K, and Mn, but most of these properties were not significantly different (P < 0.05) from those of conventional plots. Modulus of rupture and extractable Fe decreased in the no-till plots. Most of these changes, other than bulk density, occurred as a result of increases in organic C content, and the lack of more significant differences is attributed to inadequate residue production and/or its rapid decomposition in this relatively hot, moist climate.

The Relationship between "Traditional" Leadership, "Super" Leadership, and Organizational Citizenship Behavior:

Abstract: In a field study of a small manufacturing plant, relationships between five dimensions of organizational citizenship and two sets of predictors, "traditional" leadership (initiating structure and consideration) and "super" leadership (self-goal-setting, self-observation, and self-expectation) were examined. Results suggest that traditional leadership contributes incremental explained variance beyond super leadership on all five dimensions of organizational citizenship. Both consideration and initiating structure contributed approximately equally to four citizenship dimensions, whereas consideration contributed most predictive power to the sportsmanship dimension. Super leadership explained no incremental variance in organizational citizenship behavior beyond traditional leadership.

Seasonal Changes in Water Quality in Commercial Channel Catfish Ponds in Mississippi

Abstract: Selected water quality variables were measured at monthly intervals for 1 yr in 10 commercial channel catfish ponds in northwest Mississippi. Temporal changes in most variables appeared to be related to seasonal periodicity of phytoplankton abundance. Phytoplankton standing crops and total organic matter were highest in summer months when primary production was favored by warm water temperatures, high solar irradiance, and large inputs of nutrients resulting from high summer fish feed allowances. As day length, water temperature, and feed inputs decreased in autumn and winter, phytoplankton abundance and organic matter concentrations decreased. Seasonal changes in total nitrogen and total phosphorus concentrations were similar to phytoplankton abundance because much of the total nitrogen and phosphorus was contained within phytoplankton cells. Contrasting to the seasonal trend for total nitrogen, concentrations of dissolved inorganic nitrogen were lowest in the summer and highest in the cooler months. Rapid assimilation by phytoplankton served to maintain relatively low concentrations of dissolved inorganic nitrogen during the summer despite highest nitrogen loading rates during that period. Low water temperatures and generally less favorable conditions for phytoplankton growth decreased rates of nitrogen assimilation in the winter and ammonia, nitrite, and nitrate accumulated. Soluble reactive phosphorus concentrations were low throughout the year because physico-chemical processes, such as precipitation and adsorption to bottom muds acted to continually remove inorganic phosphorus from the water column.

Two mechanisms for inversionless amplification in four-level atoms with Raman pumping

Abstract: We analyze the physical origin of the inversionless amplification in four-level atoms driven by a Raman field and identify the existence of two different mechanisms for the predicted gain. The first mechanism is connected with the appearance of a population inversion between the atomic states dressed by the coherent pump, while the second is linked to the buildup of coherence among these states. Proper selection of the relaxation parameters can make either the first or the second mechanism dominant over the other although usually both coexist.

Cognitive and affective components of stimuli presented in three modes

Abstract: This study was conducted to compare responses to stimuli presented in three different modalities: olfactory, visual, and lexical (the written name of the object). Cognitive aspects of these responses as well as affective components were examined. The subjects were placed at random into one of three experimental groups and were tested individually. Each subject was asked to smell, to view, or to see the name of six common items and to write whatever immediately came to mind after each stimulus presentation. The results indicate that the olfactory mode produced the shortest answers, with the largest amount of affect. The results are discussed in terms of their implications about the structure and nature of concepts and how such concepts interrelate with different sensory modalities.

Biochemical genetics of Heliothis and Helicoverpa (Lepidoptera: Noctuidae) and evidence for a founder event in Helicoverpa zea

Abstract: Natural populations of Heliothis virescens (F.) and Helicoverpa zea (Boddie) were studied using starch gel electrophoresis as part of a program to understand gene flow, insecticide resistance, and evolutionary relationships in the group. This paper treats the electrophoretic techniques developed and used in our laboratories, compares our results with those of other workers on Heliothis and Helicoverpa , suggests enzyme loci that might be used in chemical tests for species identification, and proposes a new model for evolution in Helicoverpa . Several new or little-known enzyme staining recipes are included. Of the 23 interpretable loci revealed, 14 (61%) were polymorphic in H. virescens and 12 (52%) were polymorphic in H. zea . We find considerably less enzyme polymorphism in both species that did T. P. Sluss and co-workers in either species, but we suggest that some of the polymorphisms found by the latter were artifactual. Based on the 23 loci run here, average expected heterozygosity in H. virescens (17.2%) was significantly greater than in H. zea (5.5%). Eleven loci were diagnostic between the two species. However, our results on diagnostic loci also differ from those of T. P. Sluss et al., again suggesting scoring problems in their laboratory. Our results with H. zea were compared with those for the Old World species Helicoverpa armigera (Hubner) and Helicoverpa punctigera (Wallengren) from Australia. At polymorphic loci, H. zea has a 61% reduction in heterozygosity compared with its probable closest Old World relative, H. armigera and a similar reduction compared with H. punctigera . If caused by genetic drift, this reduction in heterozygosity would have required a severe bottleneck, equivalent to ≈10 generations with an effective population size of only six individuals, in the population ancestral to the entire species of H. zea . Our results are consistent with a founder effect leading to the evolution of the species H. zea during colonization of the Americas by stray individuals of H. armigera or a close relative.

Navier-Stokes calculations for the unsteady flowfield of turbomachinery

Abstract: The Multistage Unsteady Turbomachinery Code is presently used to numerically simulate the flowfield generated by rotating machinery. The code, which simplifies the Reynolds-averaged Navier-Stokes equations via the thin-layer approximation, is an implicit finite-volume scheme with flux Jacobians that are evaluated by flux-vector splitting, while residual fluxes are evaluated by flux-difference splitting. Attention is given to the computational results this obtained for three engineering problems, involving propfan, rotating blade, and both rotating and static blade flows.

F2 Hybrids of Host Plant Germplasm and Cotton Cultivars: I. Heterosis and Combining Ability for Lint Yield and Yield Components

Abstract: Although pest-resistant cotton (Gossypuim hirsutum L.) germplasm is available, it is generally not equal to adapted cultivars and other elite germplasm in yield. Cotton F 2 hybrids could provide a means to combine beneficial traits of high-yielding adapted cultivar (elite) germplasm with those of pest-resistant germplasms. In the F 2 heterosis and combining ability were studied for lint yield and the primary yield component boll number as well as for the secondary yield components of lint percentage and boll weight (.)