Showing papers by "Mississippi State University published in 2006"

Toward a Theory of Community-Based Enterprise

Abstract: In this article we develop the concept of community-based enterprise (CBE) and argue that it provides a potential strategy for sustainable local development in poor populations. We maintain that in this emerging form of entrepreneurship, typically rooted in community culture, natural and social capital are integral and inseparable from economic considerations, transforming the community into an entrepreneur and an enterprise. Drawing on interdisciplinary and multilevel approaches, we propose a theoretical model of the determinants, characteristics, and consequences of CBEs.

Kinematics for multisection continuum robots

Abstract: We introduce a new method for synthesizing kinematic relationships for a general class of continuous backbone, or continuum , robots. The resulting kinematics enable real-time task and shape control by relating workspace (Cartesian) coordinates to actuator inputs, such as tendon lengths or pneumatic pressures, via robot shape coordinates. This novel approach, which carefully considers physical manipulator constraints, avoids artifacts of simplifying assumptions associated with previous approaches, such as the need to fit the resulting solutions to the physical robot. It is applicable to a wide class of existing continuum robots and models extension, as well as bending, of individual sections. In addition, this approach produces correct results for orientation, in contrast to some previously published approaches. Results of real-time implementations on two types of spatial multisection continuum manipulators are reported.

Plant defense syndromes.

Abstract: Given that a plant's defensive strategy against herbivory is never likely to be a single trait, we develop the concept of plant defense syndromes, where association with specific ecological interactions can result in convergence on suites of covarying defensive traits. Defense syndromes can be studied within communities of diverse plant species as well as within clades of closely related species. In either case, theory predicts that plant defense traits can consistently covary across species, due to shared evolutionary ancestry or due to adaptive convergence. We examined potential defense syndromes in 24 species of milkweeds (Asclepias spp.) in a field experiment. Employing phylogenetically independent contrasts, we found few correlations between seven defensive traits, no bivariate trade-offs, and notable positive correlations between trichome density and latex production, and between C:N ratio and leaf toughness. We then used a hierarchical cluster analysis to produce a phenogram of defense trait similarity among the 24 species. This analysis revealed three distinct clusters of species. The defense syndromes of these species clusters are associated with either low nutritional quality or a balance of higher nutritional quality coupled with physical or chemical defenses. The phenogram based on defense traits was not congruent, however, with a molecular phylogeny of the group, suggesting convergence on defense syndromes. Finally, we examined the performance of monarch butterfly caterpillars on the 24 milkweed species in the field; monarch growth and survival did not differ on plants in the three syndromes, although multiple regression revealed that leaf trichomes and toughness significantly reduced caterpillar growth. The discovery of convergent plant defense syndromes can be used as a framework to ask questions about how abiotic environments, communities of herbivores, and biogeography are associated with particular defense strategies of plants.

Biorefineries: Current Status, Challenges, and Future Direction

Abstract: Conventional resources mainly fossil fuels are becoming limited because of the rapid increase in energy demand. This imbalance in energy demand and supply has placed immense pressure not only on consumer prices but also on the environment, prompting mankind to look for sustainable energy resources. Biomass is one such environmentally friendly renewable resource from which various useful chemicals and fuels can be produced. A system similar to a petroleum refinery is required to produce fuels and useful chemicals from biomass and is known as a biorefinery. Biorefineries have been categorized in three phases based on the flexibility of input, processing capabilities, and product generation. Phase I has less or no flexibility in any of the three aforementioned categories. Phase II, while having fixed input and processing capabilities, allows flexibility in product generation. Phase III allows flexibility in all the three processes and is based on the concept of high-value low-volume (HVLV) and low-value high...

Hydrogen Membrane Separation Techniques

Abstract: About 80% of the present world energy demand comes from fossil fuels. Unlike using fossil fuels, using hydrogen as an energy source produces water as the only byproduct. Use of hydrogen as an energy source could help to address issues related to energy security including global climate change and local air pollution. Moreover, hydrogen is abundantly available in the universe and possesses the highest energy content per unit of weight compared to any of the known fuels. Consequently, demand for hydrogen energy and production has been growing in the recent years. Membrane separation process is an attractive alternative compared to mature technologies such as pressure swing adsorption and cryogenic distillation. This paper reports different types of membranes used for hydrogen separation from hydrogen-rich mixtures. The study has found that much of the current research has been focused on nonpolymeric materials such as metal, molecular sieving carbon, zeolites, and ceramics. High purity of hydrogen is obtain...

Corporate Entrepreneurship in Family Firms: A Family Perspective

Abstract: Entrepreneurship has been recognized as an important factor contributing to firm success. Despite the potential benefit of corporate entrepreneurship to sustain the family firm across generations, corporate entrepreneurship has been underresearched in the family firm literature. We investigate how generational involvement, willingness to change, and the ability to recognize technological opportunities impact corporate entrepreneurship in family firms. We also examine strategic planning in family firms as a facilitating process. Our findings suggest that willingness to change and technological opportunity recognition are positively related to corporate entrepreneurship in family firms. We further found strategic planning to significantly moderate the relationships between (1) generational involvement and (2) technological opportunity recognition and corporate entrepreneurship. These findings and implications for management and research are discussed.

An alternative bactericidal mechanism of action for lantibiotic peptides that target lipid II

Abstract: Lantibiotics are polycyclic peptides containing unusual amino acids, which have binding specificity for bacterial cells, targeting the bacterial cell wall component lipid II to form pores and thereby lyse the cells. Yet several members of these lipid II-targeted lantibiotics are too short to be able to span the lipid bilayer and cannot form pores, but somehow they maintain their antibacterial efficacy. We describe an alternative mechanism by which members of the lantibiotic family kill Gram-positive bacteria by removing lipid II from the cell division site (or septum) and thus block cell wall synthesis.

Field trials and testing of the OctArm continuum manipulator

Abstract: This paper describes the results of field trials and associated testing of the OctArm series of multi-section continuous backbone "continuum" robots. This novel series of manipulators has recently (Spring 2005) undergone a series of trials including open-air and in-water field tests. Outcomes of the trials, in which the manipulators demonstrated the ability for adaptive and novel manipulation in challenging environments, are described. Implications for the deployment of continuum robots in a variety of applications are discussed

Identification, subtyping and virulence determination of Listeria monocytogenes, an important foodborne pathogen

Abstract: Listeria monocytogenes is an opportunistic intracellular pathogen that has become an important cause of human foodborne infections worldwide. Given its close relationship to other Listeria species and its tendency to produce non-specific clinical symptoms, the availability of rapid, sensitive and specific diagnostic tests for the differentiation of L. monocytogenes from other Listeria species is helpful for selecting appropriate treatment regimens. In addition, with L. monocytogenes comprising a diversity of strains of varying pathogenicity, the ability to precisely track the strains involved in listeriosis outbreaks and speedily determine their pathogenic potential is critical for the control and prevention of further occurrences of this deadly disease. Extensive research in recent decades has revealed significant insights regarding the molecular mechanisms of L. monocytogenes infection. This in turn has facilitated the development of laboratory procedures for enhanced detection and identification of L. monocytogenes, and has also contributed to the implementation of improved control and prevention strategies against listeriosis. The purpose of this review is to summarize recent progress in the species-specific identification, subtyping and virulence determination of L. monocytogenes strains, and to discuss future research needs pertaining to these important areas of listeriosis.

Perceived external prestige and internal respect: New insights into the organizational identification process

Abstract: The group engagement model (Tyler & Blader, 2003) suggests that identification with one's organization is based not only on the individual's evaluation of the status of the organization (i.e. perceived external prestige), but also the individual's evaluation of their own status within the organization (i.e. perceived internal respect). Using data drawn from three different sources (subordinates, supervisors, and company records), results from a sample of healthcare employees (n = 205) provide support for the core relationships proposed in the group engagement model and extend the model by showing that prestige and respect have different antecedents. The perceived status of the organization's employees, the organization's perceived success in achieving its goals, the visibility of the organization, and the status level of the individual employee were all associated with perceived external prestige. The results also indicate that visibility within the organization, perceived opportunities for growth, and pa...

Are We Family and Are We Treated as Family? Nonfamily Employees’ Perceptions of Justice in the Family Firm:

Abstract: The importance of justice perceptions in fostering positive job attitudes and value–creating behaviors in organizations is well established in the literature. Despite this, only a handful of studie...

NOx Reduction from Biodiesel Fuels

Abstract: The demand for energy around the world is increasing, specifically the demand for petroleum-based energy. Appeasing this growing energy demand without irreparably damaging the environment is of primary concern. With rising fuel prices and environmental concerns, alternative fuels could satisfy the need for renewable energy with low environmental impact. Some of the more popular alternative fuels for new vehicles are ethanol, hydrogen, and biodiesel. Although gasoline engines are expected to be replaced by hydrogen-powered fuel cells, compression-ignition engines, the diesel engines, are expected to remain in use for high-power applications because of limitations of hydrogen-storage densities. The viable environmental friendly alternative fuel for compression-ignition engines is methyl esters (commonly known as biodiesel), which is derived from vegetable oils or animal fats. Using biodiesel instead of conventional diesel fuel reduces emissions such as the overall life cycle of carbon dioxide (CO2), particu...

The effect of word frequency, word predictability, and font difficulty on the eye movements of young and older readers.

Abstract: Young adult and older readers' eye movements were recorded as they read sentences containing target words that varied in frequency or predictability. In addition, half of the sentences were printed in a font that was easy to read (Times New Roman) and the other half were printed in a font that was more difficult to read (Old English). Word frequency, word predictability, and font difficulty effects were apparent in the eye movement data of both groups of readers. In the fixation time data, the pattern of results was the same, but the older readers had larger frequency and predictability effects than the younger readers. The older readers skipped words more often than the younger readers (as indicated by their skipping rate on selected target words), but they made more regressions back to the target words and more regressions overall. The E-Z Reader model was used as a platform to evaluate the results, and simulations using the model suggest that lexical processing is slowed in older readers and that, possibly as a result of this, they adopt a more risky reading strategy.

Poplar FT2 Shortens the Juvenile Phase and Promotes Seasonal Flowering

Abstract: Many woody perennials, such as poplar (Populus deltoides), are not able to form flower buds during the first several years of their life cycle. They must undergo a transition from the juvenile phase to the reproductive phase to be competent to produce flower buds. After this transition, trees begin to form flower buds in the spring of each growing season. The genetic factors that control flower initiation, ending the juvenile phase, are unknown in poplar. The factors that regulate seasonal flower bud formation are also unknown. Here, we report that poplar FLOWERING LOCUS T2 (FT2), a relative of the Arabidopsis thaliana flowering-time gene FT, controls first-time and seasonal flowering in poplar. The FT2 transcript is rare during the juvenile phase of poplar. When juvenile poplar is transformed with FT2 and transcript levels are increased, flowering is induced within 1 year. During the transition between vegetative and reproductive growth in mature trees, FT2 transcripts are abundant during reproductive growth under long days. Subsequently, floral meristems emerge on flanks of the axillary inflorescence shoots. These findings suggest that FT2 is part of the flower initiation pathway in poplar and plays an additional role in regulating seasonal flower initiation that is integrated with the poplar perennial growth habit.

AgBase: a functional genomics resource for agriculture

Abstract: Background: Many agricultural species and their pathogens have sequenced genomes and more are in progress. Agricultural species provide food, fiber, xenotransplant tissues, biopharmaceuticals and biomedical models. Moreover, many agricultural microorganisms are human zoonoses. However, systems biology from functional genomics data is hindered in agricultural species because agricultural genome sequences have relatively poor structural and functional annotation and agricultural research communities are smaller with limited funding compared to many model organism communities. Description: To facilitate systems biology in these traditionally agricultural species we have established "AgBase", a curated, web-accessible, public resource http://www.agbase.msstate.edu for structural and functional annotation of agricultural genomes. The AgBase database includes a suite of computational tools to use GO annotations. We use standardized nomenclature following the Human Genome Organization Gene Nomenclature guidelines and are currently functionally annotating chicken, cow and sheep gene products using the Gene Ontology (GO). The computational tools we have developed accept and batch process data derived from different public databases (with different accession codes), return all existing GO annotations, provide a list of products without GO annotation, identify potential orthologs, model functional genomics data using GO and assist proteomics analysis of ESTs and EST assemblies. Our journal database helps prevent redundant manual GO curation. We encourage and publicly acknowledge GO annotations from researchers and provide a service for researchers interested in GO and analysis of functional genomics data. Conclusion: The AgBase database is the first database dedicated to functional genomics and systems biology analysis for agriculturally important species and their pathogens. We use experimental data to improve structural annotation of genomes and to functionally characterize gene products. AgBase is also directly relevant for researchers in fields as diverse as agricultural production, cancer biology, biopharmaceuticals, human health and evolutionary biology. Moreover, the experimental methods and bioinformatics tools we provide are widely applicable to many other species including model organisms.

Estimation of the Number of Decomposition Levels for a Wavelet-Based Multiresolution Multisensor Image Fusion

Abstract: The wavelet-based scheme for the fusion of multispectral (MS) and panchromatic (PAN) imagery has become quite popular due to its ability to preserve the spectral fidelity of the MS imagery while improving its spatial quality. This is important if the resultant imagery is used for automatic classification. Wavelet-based fusion results depend on the number of decomposition levels applied in the wavelet transform. Too few decomposition levels result in poor spatial quality fused images. On the other hand, too many levels reduce the spectral similarity between the original MS and the pan-sharpened images. If the shift-invariant wavelet transform is applied, each excessive decomposition level results in a large computational penalty. Thus, the choice of the number of decomposition levels is significant. In this paper, PAN and MS image pairs with different resolution ratios were fused using the shift-invariant wavelet transform, and the optimal decomposition levels were determined for each resolution ratio. In general, it can be said that the fusion of images with larger resolution ratios requires a higher number of decomposition levels. This paper provides the practitioner an understanding of the tradeoffs associated with the computational demand and the spatial and spectral quality of the wavelet-based fusion algorithm as a function of the number of decomposition levels

Laboratory persistence and fate of fluoxetine in aquatic environments.

Abstract: The persistence and fate of fluoxetine, a selective serotonin reuptake inhibitor, has been investigated in laboratory-scale experiments, including studies with various aqueous solutions, water/sediment systems, and activated sludge-amended medium The samples were placed in the dark and/or in a growth chamber fitted with fluorescent lamps simulating the ultraviolet output of sunlight Over a period of 30 d, fluoxetine was hydrolytically and photolytically stable in all aqueous solutions except synthetic humic water (pH 7), in which the degradation rate was increased by approximately 13-fold in comparison with buffered solutions at the same pH Fluoxetine rapidly dissipated from the aqueous phase in water/sediment systems, primarily because of distribution to sediments The dissipation rate from the aqueous phase was similar between light and dark systems, indicating a low contribution of photodegradation to the dissipation of fluoxetine in this system The potential impact of fluoxetine in aquatic environments would be decreased because of adsorption to sediments Based on results of ready-biodegradability investigations, fluoxetine would not be expected to rapidly biodegrade in wastewater treatment plants A photoproduct was detected only in a sample of synthetic humic water and was identified as norfluoxetine formed by demethylation Results indicate that fluoxetine is relatively recalcitrant to hydrolysis, photolysis, and microbial degradation and that it is rapidly removed from surface waters by adsorption to sediment, where it appears to be persistent

Global response approximation with radial basis functions

Abstract: In this article, a study is performed on the accuracy of radial basis functions (RBFs) in creating global metamodels for both low- and high-order nonlinear responses. The response surface methodology (RSM), which typically uses linear or quadratic polynomials, is inappropriate for creating global models for highly nonlinear responses. The RBF, on the other hand, has been shown to be accurate for highly nonlinear responses when the sample size is large. However, for most complex engineering applications only limited numbers of samples can be afforded; it is desirable to know whether the RBF is appropriate in this situation, especially when the augmented RBF has to be used. Because the types of true responses are typically unknown a priori, it is essential for high-fidelity metamodeling to have an RBF or RBFs that are appropriate for linear, quadratic, and higher-order responses. To this end, this study compares a variety of existing basis functions in both non-augmented and augmented forms with various typ...

Accumulation of genome-specific transcripts, transcription factors and phytohormonal regulators during early stages of fiber cell development in allotetraploid cotton.

Abstract: Gene expression during the early stages of fiber cell development and in allopolyploid crops is poorly understood. Here we report computational and expression analyses of 32 789 high-quality ESTs derived from Gossypium hirsutum L. Texas Marker-1 (TM-1) immature ovules (GH_TMO). The ESTs were assembled into 8540 unique sequences including 4036 tentative consensus sequences (TCs) and 4504 singletons, representing approximately 15% of the unique sequences in the cotton EST collection. Compared with approximately 178 000 existing ESTs derived from elongating fibers and non-fiber tissues, GH_TMO ESTs showed a significant increase in the percentage of genes encoding putative transcription factors such as MYB and WRKY and genes encoding predicted proteins involved in auxin, brassinosteroid (BR), gibberellic acid (GA), abscisic acid (ABA) and ethylene signaling pathways. Cotton homologs related to MIXTA, MYB5, GL2 and eight genes in the auxin, BR, GA and ethylene pathways were induced during fiber cell initiation but repressed in the naked seed mutant (N1N1) that is impaired in fiber formation. The data agree with the known roles of MYB and WRKY transcription factors in Arabidopsis leaf trichome development and the well-documented phytohormonal effects on fiber cell development in immature cotton ovules cultured in vitro. Moreover, the phytohormonal pathway-related genes were induced prior to the activation of MYB-like genes, suggesting an important role of phytohormones in cell fate determination. Significantly, AA sub-genome ESTs of all functional classifications including cell-cycle control and transcription factor activity were selectively enriched in G. hirsutum L., an allotetraploid derived from polyploidization between AA and DD genome species, a result consistent with the production of long lint fibers in AA genome species. These results suggest general roles for genome-specific, phytohormonal and transcriptional gene regulation during the early stages of fiber cell development in cotton allopolyploids.

Relationships among Structural Diversity, Informal Peer Interactions and Perceptions of the Campus Environment

Abstract: Almost half of the U.S. population will be racial/ethnic minorities by the year 2030 (Cortes, 1991). Colleges and universities are also becoming increasingly diverse and students of color are expected to comprise nearly two fifths of total undergraduate enrollment by 2015 (Carnevale & Fry, 2000). In several states, minority students already make up at least one third of the student body. For example, fall 2002 minority enrollments in the four most populous states—California, Texas, Florida, and New York—were 51%, 41%, 37%, and 32%, respectively (Chronicle of Higher Education, 2005). Faced with this dramatic demographic shift, leaders in the public and private sectors have called on colleges and universities to prepare students to function effectively in a diverse society (Association of American Colleges and Universities, 1995; Bikson & Law, 1994). Similar calls have come from within the academy by leaders such as Bowen and Bok (1998) and