Showing papers by "Southern Illinois University Carbondale published in 2001"

Anaerobic benzene oxidation coupled to nitrate reduction in pure culture by two strains of Dechloromonas

Abstract: Benzene contamination is a significant problem It is used in a wide range of manufacturing processes and is a primary component of petroleum-based fuels Benzene is a hydrocarbon that is soluble, mobile, toxic and stable, especially in ground and surface waters It is poorly biodegraded in the absence of oxygen However, anaerobic benzene biodegradation has been documented under various conditions Although benzene biomineralization has been demonstrated with nitrate1, Fe(III)2,3,4,5, sulphate6,7 or CO28,9 as alternative electron acceptors, these studies were based on sediments or microbial enrichments Until now there were no organisms in pure culture that degraded benzene anaerobically Here we report two Dechloromonas strains, RCB and JJ, that can completely mineralize various mono-aromatic compounds including benzene to CO2 in the absence of O2 with nitrate as the electron acceptor This is the first example, to our knowledge, of an organism of any type that can oxidize benzene anaerobically, and we demonstrate the potential applicability of these organisms to the treatment of contaminated environments

Contributing to success in an introductory computer science course: a study of twelve factors

Abstract: This study was conducted to determine factors that promote success in an introductory college computer science course. The model included twelve possible predictive factors including math background, attribution for success/failure (luck, effort, difficulty of task, and ability), domain specific self-efficacy, encouragement, comfort level in the course, work style preference, previous programming experience, previous non-programming computer experience, and gender. Subjects included 105 students enrolled in a CS1 introductory computer science course at a midwestern university. The study revealed three predictive factors in the following order of importance: comfort level, math, and attribution to luck for success/failure. Comfort level and math background were found to have a positive influence on success, whereas attribution to luck had a negative influence. The study also revealed by considering the different types of previous computer experiences (including formal programming class, self-initiated programming, internet use, game playing, and productivity software use) that both a formal class in programming and game playing were predictive of success. Formal training had a positive influence and games a negative influence on class grade.

Extending the lifespan of long-lived mice.

Abstract: Ames dwarf mice are mutant mice that live about 50% longer than their normal siblings1,2,3 because they carry a 'longevity' gene, Prop1df, and in some phenotypic respects they resemble normal mice whose lifespan has been extended by restricted food intake2,4,5. Here we investigate whether these factors influence lifespan by similar or independent mechanisms, by deliberately reducing the number of calories consumed by Ames dwarf mice. We show that calorie restriction confers a further lifespan increase in the dwarfs, indicating that the two factors may act through different pathways.

Population Declines and Priorities for Amphibian Conservation in Latin America

Abstract: Although dramatic amphibian population declines have been reported worldwide, our understanding of the extent of the declines in Latin America, where amphibian diversity is high, is limited to a few well-documented studies. To better understand the geographic extent of declines, their possible causes, and the measures needed to improve Latin American scientists' ability to research the phenomenon and make effective management recommendations, we convened three regional workshops with 88 Latin American herpetologists and conservationists. Population declines are widespread in Latin America. At least 13 countries have experienced declines, and in 40 cases species are now thought to be extinct or extirpated in a country where they once occurred. Declines or extinctions have affected 30 genera and nine families of amphibians. Most declines have occurred in remote highlands, above 500 m in elevation in Central America and above 1000 m in the Andes. Most documented declines occurred in the 1980s. Of the possible causes studied to date, climate change appears to be important at one site and chytrid fungal disease has been identified at sites in three countries. Although many monitoring studies are currently underway in a variety of habitats, most studies are recent and of short duration. In a signed resolution, workshop participants called for greater collaboration and communication among scientists working in Latin America to understand the geographic extent of population declines and the distribution of possible causal factors. In situ conservation is important to protect habitats, but captive-rearing programs for species subject to imminent extinction are also needed. Better understanding of the taxonomy and natural history of amphibians and more funding for research and monitoring are critical to developing a scientific basis for management action to arrest and reverse population declines.

Developments and prospects in synoptic climatology

Abstract: Developments in synoptic climatology in the 1990s included advances in traditional synoptic climatology, empirical downscaling, and dynamical downscaling (i.e. regional climate modelling). The research emphasis in traditional, empirical–statistical approaches to synoptic climatology shifted from methodological development to applications of widely accepted classification techniques, including manual, correlation-based, eigenvector-based, compositing and indexing schemes. In contrast, most efforts in empirical downscaling, which became a well-established field of synoptic climatology during the 1990s, were directed to model development; applications were of secondary concern. Similarly, regional climate models (RCMs) burst onto the scene during the decade and focused on model development, although important progress was made in linking or coupling RCMs to regional or local surface climate systems. This paper discusses prospects for the future of traditional synoptic climatology, empirical downscaling and regional climate modelling. It concludes by looking at the present role of geographic information system (GIS) concepts in synoptic climatology and the potential future role of GIS to the field. Copyright © 2001 Royal Meteorological Society

Degradation of mangrove tissues and implications for peat formation in Belizean island forests

Abstract: Summary 1 Macrofaunal leaf consumption and degradation of leaves, woody twigs and roots were studied in mangrove island forests on a Belizean island. Factors influencing accumulation of organic matter deposited both above and below ground in this oligotrophic, autochothonous system were assessed. 2 Leaf degradation rates of Rhizophora mangle (red mangrove), Avicennia germinans (black mangrove) and Laguncularia racemosa (white mangrove) measured in mesh bags, were much faster in the lower than the upper intertidal zone. Mass loss was most rapid in A. germinans but zonal effects were much larger than species differences. 3 Exposure to invertebrates such as crabs and amphipods tripled overall rates of leaf litter breakdown. In the lower intertidal, crabs completely consumed some unbagged leaves within 23 days. Crabs also had an effect on some upper intertidal sites, where degradation of leaves placed in artificial burrows was 2.4 times faster than when placed on the soil surface. 4 In contrast to leaves (27 ∠ 5% remaining after 230 days), roots and woody twigs were highly refractory (40 ∠ 2% and 51 ∠ 6% remaining after 584 and 540 days, respectively). Root degradation did not vary by soil depth, zone or species. Twigs of R. mangle and A. germinans degraded faster on the ground than in the canopy, whereas those of L. racemosa were highly resistant to decay regardless of position. 5 Peat formation at Twin Cays has occurred primarily through deposition and slow turnover of mangrove roots, rather than above-ground tissues that are either less abundant (woody twigs) or more readily removed (leaves).

Freshwater fish distribution

Abstract: With more than 29,000 species, fishes are the most diverse group of vertebrates on the planet. Of that number, more than 12,000 species are found in freshwater ecosystems, which occupy less than 1 percent of the Earth's surface and contain only 2.4 percent of plant and animal species. But, on a hectare-for-hectare basis, freshwater ecosystems are richer in species than more extensive terrestrial and marine habitats. Examination of the distribution patterns of fishes in these fresh waters reveals much about continental movements and climate changes and has long been critical to biogeographical studies and research in ecology and evolution. Tim M. Berra's seminal resource, "Freshwater Fish Distribution", maps the 169 fish families that swim in fresh water around the world. Each family account includes the class, subclass, and order; a pronunciation guide to the family name; life cycle information; and interesting natural history facts. Each account is illustrated, many with historical nineteenth-century woodcuts. Now available in paperback, this heavily cited work in ichthyology and biogeography will serve as a reference for students, a research support for professors, and a helpful guide for tropical fish hobbyists and anglers.

Strategic groups and competitive enactment: a study of dynamic relationships between mental models and performance

Abstract: This study used computer-assisted content analysis of more than four hundred presidents' letters to shareholders to examine empirical linkages between cognitive strategic groups clustered by themes in the reports and strategic groups clustered by performance. We found these groups converged as predicted by the literature, and that mental models and performance are involved in a recursive process of competitive enactment which contributes to strategic group stability. Our research used inductively derived themes from the letters to structure a mental model widely shared in the pharmaceutical industry, and then employed thematic variations to find stable clusters of companies. These thematic clusters were triangulated with the strategic groups from a published study of the same industry, in the same period, and were shown to converge. Additionally, longitudinal linkages between earlier mental models of strategic goals and later reports of performance were found. The findings of our large-scale empirical study support strategic group theory, demonstrate a novel approach to data mining, and pose questions for future research. Copyright © 2001 John Wiley & Sons, Ltd.

Mutation of the ptsG gene results in increased production of succinate in fermentation of glucose by Escherichia coli.

Abstract: Escherichia coli NZN111 is blocked in the ability to grow fermentatively on glucose but gave rise spontaneously to a mutant that had this ability. The mutant carries out a balanced fermentation of glucose to give approximately 1 mol of succinate, 0. 5 mol of acetate, and 0.5 mol of ethanol per mol of glucose. The causative mutation was mapped to the ptsG gene, which encodes the membrane-bound, glucose-specific permease of the phosphotransferase system, protein EIICB(glc). Replacement of the chromosomal ptsG gene with an insertionally inactivated form also restored growth on glucose and resulted in the same distribution of fermentation products. The physiological characteristics of the spontaneous and null mutants were consistent with loss of function of the ptsG gene product; the mutants possessed greatly reduced glucose phosphotransferase activity and lacked normal glucose repression. Introduction of the null mutant into strains not blocked in the ability to ferment glucose also increased succinate production in those strains. This phenomenon was widespread, occurring in different lineages of E. coli, including E. coli B.

Biogenic Magnetite Formation through Anaerobic Biooxidation of Fe(II)

Abstract: The presence of isotopically light carbonates in association with fine-grained magnetite is considered to be primarily due to the reduction of Fe(III) by Fe(III)-reducing bacteria in the environment. Here, we report on magnetite formation by biooxidation of Fe(II) coupled to denitrification. This metabolism offers an alternative environmental source of biogenic magnetite.

Earnings Management and Corporate Governance: The Roles of the Board and the Audit Committee

Abstract: We examine the role of the board of directors, the audit committee, and the executive committee in preventing earnings management. Supporting an SEC Panel Report's conclusion that audit committee members need financial sophistication, we show that the composition of a board in general and of an audit committee more specifically, is related to the likelihood that a firm will engage in earnings management. Board and audit committee members with corporate or financial backgrounds are associated with firms that have smaller discretionary current accruals. Board and audit committee meeting frequency is also associated with reduced levels of discretionary current accruals. We conclude that board and audit committee activity and their members' financial sophistication may be important factors in constraining the propensity of managers to engage in earnings management.

A Psychometric Investigation of the Academic Motivation Scale Using a United States Sample.

Abstract: The authors examine the factor structure of the Academic Motivation Scale (AMS; R. J. Vallerand, L. G. Pelletier, M. R. Blais, N. M. Briere, C. Senecal, & E. F. Vallieres, 1992) with a United State...

Alkanethiolate-Protected Copper Nanoparticles: Spectroscopy, Electrochemistry, and Solid-State Morphological Evolution†

Abstract: Copper nanoparticles protected by alkanethiolate monolayers were prepared in a one-phase system using superhydride as the reducing reagent. The as-produced nanoparticles were typically found within the size range of 1−2 nm in diameter and of spherical shape. UV−vis and FTIR spectroscopies were carried out to investigate the particle optoelectronic properties and the molecular conformations of the protecting monolayers. Electrochemistry was used to study their quantized charging properties in solutions where the nanoparticle molecular capacitance was evaluated. When the particles were subject to mild-temperature thermal annealing in solid state, large (>10 nm) nanocrystals emerged with well-define facets and distinct surface morphologies. While the majority of the nanocrystals were spherical, other crystal shapes such as hexagons, pentagons, diamonds, triangles, and even rods were very visible. Discussion of the molecular mechanism for the shape evolution is presented.

Post-tonsillectomy bleeding: a meta-analysis.

Abstract: Objective/Hypothesis: To reconcile conflicting reports and opinions of the value of preoperative coagulation studies for patients undergoing tonsillectomy. Study Design: Meta-analysis: Articles were identified by MEDLINE search, references from review articles, textbook chapter, and retrieved reports. Independent observers selected prospective trials of patients undergoing tonsillectomy or adenoidectomy and tonsillectomy. Retrospective studies meeting other inclusion and exclusion criteria were included for sensitivity analyses of results. Methods: Data were abstracted from studies for an end point of bleeding with normal and abnormal coagulation tests. Four prospective studies met all inclusion and exclusion criteria. These four studies were used in the data synthesis. An additional eight retrospective studies met all other criteria and were used in the sensitivity analysis. Results: Pooled analysis of 3384 patients revealed a rate of 3.3% (95% confidence interval [CI], 2.5%-4.1%) for post-tonsillectomy bleeding in patients with normal coagulation studies. A rate of 8.7% (95% CI, 1.5%-15.9%) was obtained for bleeding in patients with abnormal coagulation studies. No significant rate difference in post-tonsillectomy bleeding was demonstrated. Conclusion: There is no difference in the rate of post-tonsillectomy bleeding in patients with abnormal coagulation studies as compared with patients with normal coagulation studies obtained preoperatively.

Academic Characteristics of Incarcerated Youth and Correctional Educational Programs: A Literature Review.

Abstract: A literature review of the academic characteristics of incarcerated youth and the academic correctional education programs serving them was conducted.The outcomes of the review indicated incarcerated adolescents function in the low-average to below-average range of intelligence, perform academically between fifth- and ninth-grade levels, and have histories of high rates of academic failure and grade retention.The predominant feature of correctional education academic programs serving these youth is a broad continuum of curricular offerings, ranging from elementary school to postsecondary school levels. However, the availability of special education services for youth with disabilities varies from state to state. Effective instructional strategies for incarcerated youth appear to be direct instruction and tutoring-based approaches. Implications of the findings for program development are discussed.

Tracking the Restructuring of American Religion: Religious Affiliation and Patterns of Religious Mobility, 1973–1998

Abstract: Trends and patterns of religious mobility have played a central role in theoretical controversies in the sociology of religion. Early examinations focused on how social status might motivate religious switching, and recently scholars have claimed that diminishing status differences between denominations have opened denominational boundaries and led to higher rates of religious mobility. Scholars working from rational actor perspectives have generated several hypotheses. First, human capital and adaptive preference theories suggest that switching will remain infrequent, and will tend to occur between similar denominations. Second, "strict church" perspectives argue that demanding sectarian denominations will have higher retention, and be more attractive destinations. Third, market niche perspectives argue that niche overlap will foster high rates of religious mobility. Finally, theories emphasizing normative constraints on religious choices suggest that quasi-ethnic religious groups will have a greater hold on members. This article examines trends and patterns of religious mobility in the U.S. between 1973 and 1998 using data from the General Social Surveys. Retention rates, distributions of original and destination affiliations, and mobility tables are compared across three periods, and four broad cohorts using log-multiplicative association models. I find some support for hypotheses generated by status theories, and for several propositions from rational actor theories, however the decline of denominationalism perspective is unsupported.

‘Forrest’ Resistance to the Soybean Cyst Nematode Is Bigenic: Saturation Mapping of the Rhg1 and Rhg4 Loci

Abstract: Field resistance to cyst nematode (SCN) race 3 (Heterodera glycines I.) in soybean [Glycine max (L.) Merr.] cv ’Forrest’ is conditioned by two QTLs: the underlying genes are presumed to include Rhg1 on linkage group G and Rhg4 on linkage group A2. A population of recombinant inbred lines (RILs) and two populations of near-isogenic lines (NILs) derived from a cross of Forrest×Essex were used to map the loci affecting resistance to SCN. Bulked segregant analysis, with 512 AFLP primer combinations and microsatellite markers, produced a high-density genetic map for the intervals carrying Rhg1 and Rhg4. The two QTLs involved in resistance to SCN were strongly associated with the AFLP marker EATGMCGA87 (P=0.0001, R2=24.5%) on linkage group G, and the AFLP marker ECCGMAAC405 (P=0.0001, R2 =26.2%) on linkage group A2. Two- way analysis of variance showed epistasic interaction (P=0.0001, R2 =16%) between the two loci controlling SCN resistance in Essex×Forrest recombinant inbred lines. Considering the two loci as qualitative genes and the resistance as female index FI <5%, jointly the two loci explained over 98% of the resistance. The locations of the two QTLs were confirmed in the NILs populations. Therefore SCN resistance in Forrest×Essex is bigenic. High-efficiency marker-assisted selection can be performed using the markers to develop cultivars with stable resistance to SCN.

A Simplified Dynamic Model of Grid-Connected Fuel-Cell Generators

Abstract: This paper describes a reduced-order dynamic model for a grid-connected fuel-cell power plant that is suitable for preliminary stability assessment. Generic voltage and power control loops are included. The model is applied to a distributed utility that uses fuel cells and gas turbines to investigate the nature and magnitude of their interaction. The studies presented in the paper show the effect of the mix between the fuel cell and gas turbine generation on the system stability. The developed model, being simple, could provide a useful tool for the planning of distributed generation.

New procedures to assess executive functions in preschool children.

Abstract: Executive functions are difficult to assess in preschool children, yet the preschool period is particularly important, both in the development of behavioral control and of the brain, particularly the prefrontal cortex. Several tasks were adapted from developmental and neuroscience literature and then administered to 98 preschool children (30-, 36-, 42-, 48- and 60-month age groups). Executive function task performance was related largely to age group, but not to sex or intelligence. These tasks, then, were sensitive in this age range and may be useful to delineate distinct cognitive profiles among preschool children with various neurological and developmental disorders.

Photosynthetic and phylogenetic primers for detection of anoxygenic phototrophs in natural environments

Abstract: Primer sets were designed to target specific 16S ribosomal DNA (rDNA) sequences of photosynthetic bacteria, including the green sulfur bacteria, the green nonsulfur bacteria, and the members of the Heliobacteriaceae (a gram-positive phylum). Due to the phylogenetic diversity of purple sulfur and purple nonsulfur phototrophs, the 16S rDNA gene was not an appropriate target for phylogenetic rDNA primers. Thus, a primer set was designed that targets the pufM gene, encoding the M subunit of the photosynthetic reaction center, which is universally distributed among purple phototrophic bacteria. The pufM primer set amplified DNAs not only from purple sulfur and purple nonsulfur phototrophs but also from Chloroflexus species, which also produce a reaction center like that of the purple bacteria. Although the purple bacterial reaction center structurally resembles green plant photosystem II, the pufM primers did not amplify cyanobacterial DNA, further indicating their specificity for purple anoxyphototrophs. This combination of phylogenetic- and photosynthesis-specific primers covers all groups of known anoxygenic phototrophs and as such shows promise as a molecular tool for the rapid assessment of natural samples in ecological studies of these organisms.

Interplay of structure and transport properties of sodium-doped lanthanum manganite

Abstract: The crystal structure, magnetic and electrical transport properties of the sodium-doped lanthanum manganites La1-xNaxMnO3 (0.07≤x≤0.40) have been studied in detail using x-ray powder diffraction, atomic absorption spectroscopy, a SQUID (superconducting quantum interference device) magnetometer and the four-probe resistivity measurement technique. A rhombohedrally distorted perovskite structure has been observed in the range 0.07≤x≤0.20. Both the lattice parameter and unit-cell volume decrease with increase in the Na content. A ferromagnetic-to-paramagnetic phase transition associated with a metal-insulator transition is observed for all the La1-xNaxMnO3 compounds. There is a systematic change in both the Mn-O-Mn bond angle and the tolerance factor with Na content. The compositional variation of the magnetic and metal-insulator transition temperatures is explained as due to the distortion of the MnO6 octahedron and increase in the tolerance factor that controls the hopping interaction. In the metallic region a ρ~AT2 behaviour is observed due to the magnon excitation effect. The resistivity shows a field-dependent minimum at low temperature that has been explained as due to the intergrain transport phenomenon.

Murine germ cells do not require functional androgen receptors to complete spermatogenesis following spermatogonial stem cell transplantation.

Abstract: The spermatogonial stem cell transplantation technique was employed to determine if murine germ cells require functional androgen receptors to complete qualitatively normal spermatogenesis. Testicular cells from testicular feminized mice were injected into the seminiferous tubules of azoospermic mice expressing functional androgen receptors. Recipient testes were analyzed between 110 and 200 days following transplantation. Multiple colonies of complete and qualitatively normal donor-derived spermatogenesis were seen within the seminiferous tubules of each recipient testis, demonstrating that murine germ cells do not require functional androgen receptors to complete spermatogenesis.

A Review on Consumer External Search: Amount and Determinants

Abstract: Consumer external search continues to be a fruitful research area. The bivariate relationships between a number of variables and the central construct, amount of information search, have been proposed, theorized, and empirically tested in the literature. This paper extensively examines the current status and importance of consumer information search with close attention on empirical findings on the subject. While some research findings converge on the bivariate relationship between some variables and amount of information search, e.g., a positive relationship between perceived risk and search effort, some studies found conflicting results on the relationship between other variables and the central construct. There are also some non-linear relationships found between a few variables such as experience and the degree of search. Some hypotheses are also proposed and discussed.

Vagus nerve stimulation: analysis of device parameters in 154 patients during the long-term XE5 study.

Abstract: Summary: Purpose: To determine the effect of changes in device settings and duty cycle (on and off times) on the efficacy of vagus nerve stimulation (VNS) for refractory epilepsy. In the long-term XE5 study of VNS for intractable epilepsy, the median reduction in seizure frequency improved significantly after 1 year of follow-up. A central question is whether device changes improve efficacy. We analyzed the effects of device parameter changes on seizure frequency in 154 subjects who completed the study and who had complete data for analysis. Methods: Retrospective analysis of device changes during the XE5 long-term study of VNS. During the XE5 long-term follow-up study, the subject's device settings were modified within a Food and Drug Administration (FDA)-approved range of output current, pulse duration, frequency, on time, and off time. Significant changes in device settings occurred after 3 months. We investigated the relationship between percentage reduction in seizures and changes in device parameters between the 3- and 12-month visits. Within-group comparisons were performed for those who continued on standard on/off cycle of 30 s on and 5 min off, and those with the most common off times of 3, 1.8, and <1.1 min. Results: Output current, pulse duration, frequency, and off time changed significantly between the 3- and 12-month long-term follow-ups. For the group as a whole, changes in device settings were not correlated with an improvement in efficacy. However, a significant improvement in efficacy occurred in a subgroup whose off time was reduced to ≤1.1 min. In this group, the median reduction in seizures improved from 21% before the change in off time, to 39% after the change in off time (Wilcoxon Signed-Rank, p = 0.011). The responder rate (>50% reduction in seizures) also significantly improved from 19 to 35% (McNemar's test, p = 0.046). Conclusions: The data from this retrospective analysis indicate that device changes were not the primary determinant of increased efficacy at 12 months of long-term follow-up. In general, patients who remained on the original settings of 30 s on and 5 min off continued to respond or improve in their response over the 1-year period. However, some patients may benefit from reductions in off time (increases in duty cycle). In a subgroup initially resistant to VNS, a change in off time to ≤1.1 min off did result in significant improvements in efficacy.

Motile Gametes of Land Plants: Diversity, Development, and Evolution

Abstract: Referee: Professor Jeffrey Duckett, School of Biological Sciences, Queen Mary and Westfield College, University of London, Mile End Road, London, E1 4NS, UK Spermatogenesis is a morphogenetic system in plants that is unparalled in its potential to yield diverse and informative structural and developmental data. The unquestionable homology of terrestrial plant spermatozoids to each other and to gametes of related lineages allows an examination of cellular evolution and provides sound data for phylogenetic analyses. In this review we examine the architecture and ontogeny of motile male gametes among major groups of land plants. We begin with a historical perspective that emphasizes the utility of spermatogenesis in understanding cellular evolution and in determining phylogenetic relationships. A cladistic analysis of data based solely on spermatogenesis and a conceptual phylogeny based on combined morphological and molecular data serve as the basis for the comprehensive discussion of architectural and devel...