Showing papers by "Mississippi State University published in 1997"

Soybean transformation and regeneration methods

Abstract: A method of transforming and regenerating soybean plants relies on selection of hypocotyl explants as the target material. Hypocotyl explants can be transformed either by microparticle bombardment with DNA-coated microparticles of inert metals, or by co-culturing with an Agrobacterium strain. The transformed explants can be successfully regenerated, using a protocol including culturing on a shoot induction medium, followed by transfer to a shoot elongation medium to form rooted plantlets, which are transplanted to soil.

Advancing the Theory of Adaptive Structuration: The Development of a Scale to Measure Faithfulness of Appropriation

Abstract: Adaptive Structuration Theory AST is rapidly becoming an influential theoretical perspective in research on advanced information technologies. However, there still exists a paucity of methods to capture critical AST constructs. This paper describes the development of an instrument to capture the extent to which users of an advanced information technology believe they have appropriated its structures faithfully. The development of such instruments is considered critical if the theoretical base provided by AST is to be fully exploited in understanding the use of advanced information technologies. The development procedure, which occurred in the context of the use of an electronic meeting system, was carried out in three phases that began with initial item development and proceeded through an exploratory to a confirmatory phase. Three experiments, two in the exploratory phase and one in the confirmatory phase, were performed. In the final phase, structural equation modeling techniques were used to confirm the convergent, discriminant, and nomological validity of the resulting five-item scale.

The social consequences of self-control: testing the general theory of crime*

Abstract: Gottfredson and Hirschi's recently introduced general theory of crime has received considerable empirical support. Researchers have found that low self-control, the general theory's core concept, is related to lawbreaking and to deviant behaviors considered by Gottfredson and Hirschi to be “analogous” to crime. In this article, we extend this research by assessing the effects of low self-control on crime and analogous behaviors and by using two distinct measures of self-control, an attitudinal measure and the analogous/behavior scale. Thus, following Gottfredson and Hirschi, we use analogous imprudent behaviors as outcomes of low self-control and as indicators of low self-control's effects on crime. We also examine an important but thus far neglected part of the theory: the claim that low self-control has effects not only on crime but also on life chances, life quality, and other social consequences. Consistent with the general theory, we found that both measures of self-control, attitudinal and behavioral, have effects on crime, even when controlling for a range of social factors. Further, the analysis revealed general support for the theory's prediction of negative relationships between low self-control and social consequences other than crime—life outcomes and quality of life.

Bovine Tuberculosis in Free-Ranging White-Tailed Deer From Michigan

Abstract: A 4.5 yr-old male white-tailed deer (Odocoileus virginianus) killed by a hunter during the 1994 firearm hunting season in northeastern Michigan (USA) had lesions suggestive of tuberculosis and was positive on culture for Mycobacterium bovis the causative agent for bovine tuberculosis. Subsequently, a survey of 354 hunter-harvested white-tailed deer for tuberculosis was conducted in this area from 15 November 1995 through 5 January 1996. Heads and/or lungs from deer were examined grossly and microscopically for lesions suggestive of bovine tuberculosis. Gross lesions suggestive of tuberculosis were seen in 15 deer. Tissues from 16 deer had acid-fast bacilli on histological examination and in 12 cases mycobacterial isolates from lymph nodes and/or lungs were identified as M. bovis. In addition, lymph nodes from 12 deer (11 females and 1 male) without gross or microscopic lesions were pooled into 1 sample from which M. bovis was cultured. Although more male (9) than female (3) deer had bovine tuberculosis in...

Designing and Rating an Area Yield Crop Insurance Contract

Abstract: This article documents the design and rate-making procedures used in the development of the Group Risk Plan (GRP)—the new federal crop insurance product that insures based on area yield. The authors of this article worked closely with personnel in the Federal Crop Insurance Corporation and others in developing methodological and practical constraints needed in implementing a workable area yield contract. GRP indemnity payments are made based on percentage shortfalls in actual county yields relative to a forecasted yield. Historical county yield data are used to develop forecasted yields and premium rates.

The intestines of carnivorous fish: structure and functions and the relations with diet

Abstract: The intestine is a complex multifunctional organ. In addition to digesting and absorbing feedstuffs, the intestine is critical for water and electrolyte balance, endocrine regulation of digestion and metabolism, and immunity. The intestines of carnivorous fish have evolved for processing a highly digestible, nutrient dense diet that is high in protein and low in carbohydrate. Correspondingly, abilities to digest protein are well developed, but carbohydrate digestion is low compared to omnivorous and herbivorous fish. Furthermore, the evolutionary stable diet is associated with a lack or reduced abilities to adaptively modulate digestive functions to match changes in diet composition. Despite similar selective pressures, intestinal structure is highly variable among carnivorous fish, reflecting phylogenetic diversity. Due to economic considerations, diets for cultured species often have varying proportions of plant-based ingredients. Although such feeds are effective for raising omnivorous and herbivorous species, they have provided limited success for carnivores, and this has been attributed to digestive limitations. Recent evidence of inflammatory responses to as yet unidentified components of some plants suggest involvement of the enteric immune system. Changes in temperature and salinity alter intestinal structure and functions, and therefore processing of dietary inputs. A relatively unknown component of the intestine involves the resident microbiota and its role in the health and disease of carnivoraus fish.

Out-of-the-Loop Performance Problems and the Use of Intermediate Levels of Automation for Improved Control System Functioning and Safety

Abstract: Human supervisory control and monitoring of automated systems, as well as, passive system(s) information processing can all be classified as forms of out-of-the-loop (OOTL) performance. Whether the operator's task is to decide if process control intervention is necessary, detect a critical system event, or accept or reject the actions of a computer controller, he or she is removed from direct, real-time control of the system. OOTL performance is a critical issue in overall automated systems functioning because it is associated with numerous negative consequences including: (a) operator failure to observe system parameter changes and intervene when necessary (vigilance decrements); (b) human over-trust in computer controllers (complacency); (c) operator loss of system or situation awareness; and (d) operator direct/manual control skill decay. These consequences have been found to impact human performance under both normal operating conditions and system failure modes, with a greater effect on the latter [15] leading to serious problems in operator ability to perform their assigned tasks when working with automated systems. Level of automation (LOA) has been put forth as an approach to ameliorating OOTL performance problems. It is intended to determine the optimal assignment of control between a human operator and computer in order to keep both involved in system operations. LOA considers the capabilities and capacities of both the human and computer controller in determining their optimal coupling. It constitutes a systems approach to resolving OOTL performance problems by minimizing the negative consequences associated with the removal of the operator from active system control, and allows for the strengths of both human decision making and computer processing to be realized. When compared to a technological approach that assesses only the capabilities of the computer in allocating as much responsibility to the machine as possible, and assigning the remaining tasks to the human operator, the advantages can be considerable. A LOA taxonomy will be presented along with research examining its utility in a dynamic control task. Using LOA to identify optimal combinations of human and computer control was found to produce improvements in system performance under intermediate levels. These levels involve joint human and computer control of various system functions, such as monitoring, planning, and option selection and implementation. Results indicated decreases in the number of system processes/tasks overlooked by operators. These improvements may translate into cost reductions due to improved operational safety and are anticipated to be applicable to process control operations.

Sudden Death Syndrome of Soybean

Abstract:  Sudden death syndrome (SDS) is one of the most important diseases of soybean in North and South America.  Soybeans are at greater risk for SDS when planted into cool, wet soils, when soybean cyst nematode (SCN) is present, and when summer rains cause saturated soils.  Managing SDS can involve several practices such as relieving soil compaction, delaying planting, and selecting soybean products with a good disease tolerance package.

Exploring the relationships among liminal transitions, symbolic consumption, and the extended self

Abstract: Integrating Belk's (1988) notion of the “extended self” with van Gennep's (1960) framework of “liminal transitions,” a model of symbolic consumption activities and psychological phenomena that occur during major life transitions is developed. In an initial investigation, the transition from high school to college is used to explore the nature of the liminal experience, the role that symbolic consumption assumes in the process, and the effects of both on consumers' psychological states. The results suggest that certain negative psychological consequences are indicative of existence in a liminal state. Further, consumers in transition appear to rely on possessions that symbolize the past, as well as those that represent the new role, to help facilitate a major life transition. Directions for future research are offered. © 1997 John Wiley & Sons, Inc.

Relationships among root branch order, carbon, and nitrogen in four temperate species.

Abstract: The objective of this study was to examine how root length, diameter, specific root length, and root carbon and nitrogen concentrations were related to root branching patterns. The branching root systems of two temperate tree species, Acer saccharum Marsh. and Fraxinus americana L., and two perennial herbs from horizontal rhizomes, Hydrophyllum canadense L. and Viola pubescens Ait., were quantified by dissecting entire root systems collected from the understory of an A. saccharum-Fagus grandifolia Ehrh. forest. The root systems of each species grew according to a simple branching process, with laterals emerging from the main roots some distance behind the tip. Root systems normally consisted of only 4–6 branches (orders). Root diameter, length, and number of branches declined with increasing order and there were significant differences among species. Specific root length increased with order in all species. Nitrogen concentration increased with order in the trees, but remained constant in the perennial herbs. More than 75% of the cumulative root length of tree seedling root systems was accounted for by short (2–10 mm) lateral roots almost always <0.3 mm in diameter. Simple assumptions suggest that many tree roots normally considered part of the dynamic fine-root pool (e.g., all roots <2.0 mm in diameter) are too large to exhibit rapid rates of production and mortality. The smallest tree roots may be the least expensive to construct but the most expensive to maintain based on an increase in N concentration with order.

Testing the Self-Efficacy—Performance Linkage of Social—Cognitive Theory

Abstract: Past empirical research examining the relationship of self-efficacy perceptions and performance has had several limitations. Most studies were performed in the laboratory with tasks not directly related to individual work performance. As a consequence, many findings are not generalizable to individual work performance. This study tested the self-efficacy-performance model found in Bandura's social-cognitive theory in a work setting, with a sample of 776 American university employees, and with discriminant function analyses. Respondents indicated that performance with computers significantly predicted perceptions of high and low self-efficacy. Results provide additional support for social-cognitive theory as outlined by Bandura.

Racial and gender meanings of why people participate in recreational fishing

Abstract: This article explores the meanings associated with why people fish as a leisure pursuit. Comparisons are drawn across gender and racial groups. Exploratory factor analyses reveal a mosaic of race‐ and gender‐based meanings assigned to fishing. The most marked differences are present between racial groups, although gender contributed conceptually to meaning structures. More similarities than differences in meanings are present among anglers. The results underscore the importance of going beyond an examination of leisure participation rates and issues of choice among minority groups to broader concerns of the meanings of such activities. A discussion of the theoretical significance of place and subculture highlights the role of race and gender in creating meanings of leisure. Natural resource managers are encouraged to consider the meanings placed on leisure and recreation activities by racial and gender groups.

Fish species richness and incidence patterns in isolated and connected stream pools: effects of pool volume and spatial position.

Abstract: I tested the effects of pool size and spatial position (upstream or downstream) on fish assemblage attributes in isolated and connected pools in an upland Oklahoma stream, United States. I hypothesized that there would be fundamental differences between assemblages in these two pool types due to the presence or absence of colonization opportunities. Analyses were carried out at three ecological scales: (1) the species richness of pool assemblages, (2) the species composition of pool assemblages, and (3) the responses of individual species. There were significant species-volume relationships for isolated and connected pools. However, the relationship was weaker and there were fewer species, on average, in isolated pools. For both pool types, species incidences were significantly nested such that species-poor pools tended to be subsets of species-rich pools, a common pattern that ultimately results from species-specific differences in colonization ability and/or extinction susceptibility. To examine the potential importance of these two processes in nestedness patterns in both pool types, I made the following two assumptions: (1) probability of extinction should decline with increasing pool size, and (2) probability of immigration should decline in an upstream direction (increasing isolation). When ordered by pool volume, only isolated pools were significantly nested suggesting that these assemblages were extinction-driven. When ordered by spatial position, only connected pools were significantly nested (more species downstream) suggesting that differences in species-specific dispersal abilities were important in structuring these assemblages. At the individual-species level, volume was a significant predictor of occurrence for three species in isolated pools. In connected pools, two species showed significant position effects, one species showed a pool volume effect, and one species showed pool volume and position effects. These results demonstrate that pool size and position within a watershed are important determinants of fish species assemblage structure, but their importance varies with the colonization potential of the pools. Isolated pool assemblages are similar to the presumed relaxed faunas of montane forest fragments and land bridge islands, but at much smaller space and time scales.

Cover, Copy, and Compare: A Self-Managed Academic Intervention Effective Across Skills, Students, and Settings

Abstract: Cover, Copy, and Compare (CCC) is a simple, efficient, self-managed academic intervention that can be used to improve accuracy, fluency, and maintenance across students, curricula objectives, academic skill domains, and settings In it's simplest form CCC requires students to look at an academic stimulus (eg, for spelling the stimulus would be a written a word) cover the stimulus, respond by copying the stimulus (eg, writing the word), and evaluate the responses by comparing it to the original stimulus The CCC procedure and research that supports the generalizability and ecological validity of this procedure is described and analyzed Following this analysis, recommendations for implementing Cover, Copy, and Compare in educational settings are provided

Dynamics of juvenile hormone-mediated gonadotropism in the Lepidoptera

Abstract: Reproduction in moths and butterflies is a dynamic process that is influenced by various endogenous physiological processes and exogenous factors. The Lepidoptera may be divided into four distinct groups based on their gonadotropic hormones and other reproductive and biological characteristics, regardless of phylogenetic relationships. Some species have integrated their reproduction tightly with the endocrine events of metamorphosis, the waxing or waning ecdysteroid levels. Other species rely instead on juvenile hormone (JH), in part or solely. Species of Lepidoptera that rely on JH as the gonadotropic signal also exhibit polyandry. Several mechanisms have been suggested for the occurrence of polyandry, including availability of male-transferred nutrients (gonadotrophic effect), need for additional sperm, and increased genetic variability. We propose an additional reason for polyandry observed in some lepidopterans. If a female remains a virgin, her endogenous gonadotropic signal diminishes, and eggs that have been produced already may be resorbed to increase longevity. During copulation, the male may trigger a neural/humoral response in the female, thus stimulating release of her endogenous gonadotropic signal, JH, and/or inhibiting degradation of the same, whence she matures new eggs. The mating effect appears to act humorally on the cephalic structures in several species. Whether this change in JH titer is due to an effect on synthesis and release by corpora allata only or occurs in conjunction with inhibition of JH degradation is unknown. Arch. Insect Biochem. Physiol. 35:539–558, 1997. © 1997 Wiley-Liss, Inc.

Microbial Phytase Can Replace Inorganic Phosphorus Supplements in Channel Catfish Ictalurus punctatus Diets

Abstract: .– Juvenile channel catfish Ictalurus punctatus (initial weight: 6.8 g/fish) were fed four practical diets containing 0, 250, 500, and 750 units of microbial phytase/kg and a diet containing 1% feed grade dicalcium phosphate (but no microbial phytase) under laboratory conditions for 12 wk. Fish fed the diets containing 250 units of microbial phytase/kg and above consumed more feed, gained more weight, and had a lower feed conversion ratio (FCR) in comparison to fish fed the basal diet containing no microbial phytase. Fish fed the diet containing dicalcium phosphate had intermediate weight gain and feed conversion ratio as compared to fish fed the basal diet and diets containing microbial phytase. Bone ash and phosphorus concentrations were lower for fish fed the basal diet than for fish fed other diets. No differences in weight gain, feed consumption, FCR, bone ash and bone phosphorus were observed among fish fed the diets containing various levels of microbial phytase. Fish fed the diet containing dicalcium phosphate had a lower bone phosphorus concentration than fish fed diets containing microbial phytase. Fecal phosphorus concentrations were lower for fish fed the diets containing microbial phytase than for fish fed the basal diet and the diet containing dicalcium phosphate. Results from the present study indicated that addition of 250 units of microbial phytase/kg to practical diets can effectively improve bioavailability of phytate phosphorus to channel catfish and may possibly eliminate the use of an inorganic phosphorus supplement in channel catfish diets. However, these data must be verified in trials conducted in ponds, prior to recommending removal of supplemental phosphorus from channel catfish diets.

Fusarium solani on soybean roots : Nomenclature of the causal agent of sudden death syndrome and identity and relevance of F. solani form B

Abstract: Two morphological forms of Fusarium solani pathogenic on soybean, forms A and B, were further characterized and distinguished from other fungi Questions regarding their identity were addressed Soybean plants grown in the field and in a growth chamber were inoculated with Fusarium solani form A and F solani f sp phaseoli F solani form A incited leaf symptoms typical of sudden death syndrome; F solani f sp phaseoli did not It was concluded that the two fungi are different and distinguishable on the basis of host specialization and the types of symptoms they incite on soybean F solani form A, the causal agent of sudden death syndrome, was designated F solani (Mart) Sacc f sp glycines form nov Cultural and morphological characteristics of F solani form B, the cause of seedling disease and root rot of soybean, and Plectosphaerella cucumerina were compared to determine the validity of a report indicating that they were conspecific Results demonstrated that F solani form B and P cucumerina are distinctly different and not conspecific The relevance of identifying and recognizing the two F solani forms as separate and distinct members of the F solani pathogen complex on soybean is discussed

Suckling Induces Rapid Intestinal Growth and Changes in Brush Border Digestive Functions of Newborn Pigs

Abstract: The interplay between suckling, intestinal growth and brush-border membrane functions is critical during the perinatal period. The present study investigates changes in intestinal dimensions, activities of four brush border membrane hydrolases (lactase, sucrase, maltase and aminooligopeptidase) and rates of sugar and amino acid uptake by intact tissues and brush border membrane vesicles during the first 24 h of suckling. Total intestinal weight, mucosal weight and protein content increased 58%, 80% and 126% (P < 0.05) during the first 6 h of suckling; length and surface area did not increase. Total mucosal DNA content was 4.6-fold higher at 24 h after birth, with the rate of increase differing among intestinal regions. Hydrolytic capacities of the entire small intestine increased, more so for homogenates than for brush border membrane vesicles, and more for lactase relative to the other hydrolases studied. Rates of nutrient transport declined, especially for brush border membrane vesicles, for proximal and mid-intestine relative to distal intestine, and for glucose relative to galactose and amino acids. We conclude that 1) changes in brush border membrane digestive functions coincide with rapid intestinal growth, with postnatal patterns varying among hydrolases, transporters and regions; 2) insertion into the brush border membrane, not synthesis, limits the postnatal increase of hydrolase activity; and 3) despite declines in specific activity, hydrolytic and glucose transport capacities of the entire intestine remained stable or increased, and exceeded estimated dietary loads because of intestinal growth.

Encephalitozoon hellem in Budgerigars (Melopsittacus undulatus)

Abstract: Microsporidiosis with concurrent megabacteriosis in budgerigar (Melopsittacus undulatus) chicks contributed to significant economic loss in a commercial pet bird aviary in Mississippi. Three budgerigar chicks, 1-2 weeks old, from the aviary were necropsied. Microscopic lesions in the chicks consisted of heavy infection of enterocytes with microsporidia (2/3; autolysis precluded critical evaluation of the intestine of chick No. 2), multifocal hepatic necrosis and inflammation with intralesional microsporidia (1/3), spherical clusters of microsporidia in the hepatic sinusoids in the absence of inflammation (1/3), and gastric megabacteriosis (3/3). The ultrastructure of the microsporidian spores was consistent with an Encephalitozoon species. The polymerase chain reaction and Southern blot analysis were used to identify the microsporidian as Encephalitozoon hellem, an organism that has only been identified in humans. Encephalitozoon hellem causes keratoconjunctivitis and respiratory infections in humans with...

Debating Patriarchy: Discursive Disputes over Spousal Authority among Evangelical Family Commentators

Abstract: Theoretical paradigms that have called attention to the contemporary "war" over the family suggest that religious conservatives in general, and evangelical Protestants in particular, are among the most vociferous defenders of a "traditional" patriarchal family structure. However, a handful of recent inquiries on contemporary evangelical spousal roles has suggested that conservative Protestants are not unanimous in their support for a patriarchal family structure. Drawing on insights from poststructuralist theories of discourse and gender theory, this study augments such investigations by analyzing the rhetoric contained within a large sample of popular evangelical family manuals. I demonstrate that leading conservative Protestants are engaged in a rancorous debate about spousal authority relatione, with evangelical pur­ veyors of patriarchy attracting significant criticism from prominent biblical feminists and a growing coterie of egalitarian evangelical commentators. After delineating the most salient points of this internecine debate, I trace these antagonists' divergent recommendations for the allocation of spousal authority to their distinctive assumptions about (1) the nature of masculinity and femininity, and (2) Bible's instructions for familial decision making. I conclude by specifying several directions for future empirical research, and by explicating this study's challenge to prevailing assumptions concerning the religious contours of the war over the family.

Numerical Simulation of Internal Kelvin Waves and Coastal Upwelling Fronts

Abstract: Two three-dimensional primitive equation numerical ocean models are applied to the problem of internal Kelvin waves and coastal upwelling in the Great Lakes. One is the Princeton Ocean Model (POM) with a terrain-following (sigma) vertical coordinate, and the other is the Dietrich/Center for Air Sea Technology (DIECAST) model with constant z-level coordinates. The sigma coordinate system is particularly convenient for simulating coastal upwelling, while the z-level system might be better for representing abrupt topographic changes. The models are first tested with a stratified idealized circular lake 100 km in diameter and 100 m deep. Two bottom topographies are considered: a flat bottom and a parabolic depth profile. Three rectilinear horizontal grids are used: 5, 2.5, and 1.25 km. The POM was used with 13 vertical levels, while the DIECAST model was tested with both 13 and 29 vertical levels. The models are driven with an impulsive wind stress imitating the passage of a weather system. In the case of the flat-bottom basin, the dynamical response to light wind forcing is a small amplitude internal Kelvin wave. For both models, the speed of the Kelvin wave in the model is somewhat less than the inviscid analytic solution wave speed. In the case of strong wind forcing, the thermocline breaks the surface (full upwelling) and a strong surface thermal front appears. After the wind ceases, the edges of this thermal front propagate cyclonically around the lake, quite similar to an internal Kelvin wave. In the case of parabolic bathymetry, Kelvin wave and thermal front propagation is modified by interaction with a topographic wave and a geostrophic circulation. In both models, higher horizontal resolution gives higher wave and frontal speeds. Horizontal resolution is much more critical in the full upwelling case than in the Kelvin wave case. Vertical resolution is not as critical. The models are also applied to Lake Michigan to determine the response to strong northerly winds causing upwelling along the eastern shore. The results are more complex than for the circular basin, but clearly show the characteristics of cyclonically propagating thermal fronts. The resulting northward warm front propagation along the eastern shore compares favorably with observations of temperature fluctuations at municipal water intakes after a storm, although the model frontal speed was less than the observed speed.