Showing papers by "Clemson University published in 2001"

Does the Internet Increase, Decrease, or Supplement Social Capital? : Social Networks, Participation, and Community Commitment

Abstract: How does the Internet affect social capital? Do the communication possibilities of the Internet increase, decrease, or supplement interpersonal contact, participation, and community commitment? This evidence comes from a 1998 survey of 39,211 visitors to the National Geographic Society Web site, one of the first large-scale Web surveys. The authors find that people's interaction online supplements their face-to-face and telephone communication without increasing or decreasing it. However, heavy Internet use is associated with increased participation in voluntary organizations and politics. Further support for this effect is the positive association between offline and online participation in voluntary organizations and politics. However, the effects of the Internet are not only positive: The heaviest users of the Internet are the least committed to online community. Taken together, this evidence suggests that the Internet is becoming normalized as it is incorporated into the routine practices of everyday ...

A physical map of the human genome.

Abstract: The human genome is by far the largest genome to be sequenced, and its size and complexity present many challenges for sequence assembly. The International Human Genome Sequencing Consortium constructed a map of the whole genome to enable the selection of clones for sequencing and for the accurate assembly of the genome sequence. Here we report the construction of the whole-genome bacterial artificial chromosome (BAC) map and its integration with previous landmark maps and information from mapping efforts focused on specific chromosomal regions. We also describe the integration of sequence data with the map.

Risk propensity differences between entrepreneurs and managers: A meta-analytic review.

Abstract: Research examining the relative risk-taking propensities of entrepreneurs and managers has produced conflicting findings and no consensus, posing an impediment to theory development To overcome the limitations of narrative reviews, the authors used psychometric meta-analysis to mathematically cumulate the literature concerning risk propensity differences between entrepreneurs and managers Results indicate that the risk propensity of entrepreneurs is greater than that of managers Moreover, there are larger differences between entrepreneurs whose primary goal is venture growth versus those whose focus is on producing family income Results also underscore the importance of precise construct definitions and rigorous measurement

Total Quality Management Implementation and Competitive Advantage: The Role of Structural Control and Exploration

Abstract: The authors explored the relationship between the degree to which total quality management (TQM) practices were adopted within organizations and the corresponding competitive advantages achieved. T...

Identification of electron donor states in N-doped carbon nanotubes

Abstract: Nitrogen-doped carbon nanotubes have been synthesized using pyrolysis and characterized by scanning tunneling spectroscopy and transmission electron microscopy. The doped nanotubes are all metallic and exhibit strong electron donor states near the Fermi level. Using tight-binding and ab initio calculations, we observe that pyridine-like N structures are responsible for the metallic behavior and the prominent features near the Fermi level. These electron rich structures are the first example of n-type nanotubes, which could pave the way to real molecular heterojunction devices.

Leadership in complex organizations

Abstract: This paper asks how complexity theory informs the role of leadership in organizations. Complexity theory is a science of complexly interacting systems; it explores the nature of interaction and adaptation in such systems and how they influence such things as emergence, innovation, and fitness. We argue that complexity theory focuses leadership efforts on behaviors that enable organizational effectiveness, as opposed to determining or guiding effectiveness. Complexity science broadens conceptualizations of leadership from perspectives that are heavily invested in psychology and social psychology (e.g., human relations models) to include processes for managing dynamic systems and interconnectivity. We develop a definition of organizational complexity and apply it to leadership science, discuss strategies for enabling complexity and effectiveness, and delve into the relationship between complexity theory and other currently important leadership theories. The paper concludes with a discussion of possible implications for research strategies in the social sciences.

Does Corporate Diversification Destroy Value

Abstract: We analyze several hundred firms that expand via acquisition and/or increase their reported number of business segments. The average combined market reaction to acquisition announcements is positive but, according to the Berger and Ofek (1995) method for valuing conglomerates, the excess values of the acquiring firms decline after the diversifying event. For our sample, half or more of the reduction in excess value occurs because the firms acquire already-discounted business units, and not because combining firms destroys value. We also show that firms that increase their number of business segments due to pure reporting changes do not exhibit reductions in excess value. Our results suggest that the standard assumption that conglomerate divisions can be benchmarked to typical stand-alone firms should be carefully reconsidered.

The Assimilation of Knowledge Platforms in Organizations: An Empirical Investigation

Abstract: The ability to integrate dispersed pockets of expertise and institute an organizational repository of knowledge is considered to be vital for sustained effectiveness in contemporary business environments. Information technologies provide cost-effective functionalities for building knowledge platforms through systematic acquisition, storage, and dissemination of organizational knowledge. However, in order to gain the value-adding potential of organizational knowledge, it is not sufficient to simply adopt and deploy IT-enabled knowledge platforms. These platforms must be assimilated into the ongoing work processes in organizations. Yet, theories of technology innovation and use suggest that a variety of institutional, social, and political factors blend together in influencing the extent to which complex information technologies are actually assimilated into organizational practice. Therefore, this research addresses a significant question: What forces influence the assimilation of knowledge platforms in organization? Given the significant gap between the adoption and actual assimilation of complex technologies into organizations, this is an important question. Empirical evidence is generated by examining the forces influencing the assimilation of CASE technologies in systems development projects in organizations. CASE is considered to be one of the most mature knowledge platforms in contemporary organizations. The empirical evidence sheds light on the role of institutional forces that influence the rate of assimilation of the technology. The findings have significant implications for further research and practice.

The Personal Discount Rate: Evidence from Military Downsizing Programs

Abstract: The military drawdown program of the early 1990s provides an opportunity to obtain estimates of personal discount rates based on large numbers of people making real choices involving large sums. The program offered over 65,000 separatees the choice between an annuity and a lump-sum payment. Despite break-even discount rates exceeding 17 percent, most of the separatees selected the lump sum--saving taxpayers $1.7 billion in separation costs. Estimates of discount rates range from 0 to over 30 percent and vary with education, age, race, sex, number of dependents, ability test score, and the size of payment.

Identification of a gene associated with Bt resistance in Heliothis virescens.

Abstract: Transgenic crops producing insecticidal toxins from Bacillus thuringiensis (Bt) are widely used for pest control. Bt-resistant insect strains have been studied, but the molecular basis of resistance has remained elusive. Here, we show that disruption of a cadherin-superfamily gene by retrotransposon-mediated insertion was linked to high levels of resistance to the Bt toxin Cry1Ac in the cotton pest Heliothis virescens. Monitoring the early phases of Bt resistance evolution in the field has been viewed as crucial but extremely difficult, especially when resistance is recessive. Our findings enable efficient DNA-based screening for resistant heterozygotes by directly detecting the recessive allele.

Product platform design: method and application

Abstract: In this paper we focus on scale-based product families derived from scalable product platforms that can be exploited from both a functional and a manufacturing standpoint to increase the potential benefits of having a common platform. While many companies have been successful with scalable product platforms, few, if any, have instituted a systematic approach to design (i) the product platform and (ii) the corresponding family of products which are scaled around the product platform. Accordingly, in this paper we address the following question: How can a scalable product platform and its resulting product family be efficiently and effectively modeled, analyzed, and designed?

An examination of the determinants of entertainment vacationers' intentions to revisit.

Abstract: This study investigated the relationship of entertainment travelers’ past vacation behavior, vacation satisfaction, perceived vacation value, and intentions to revisit and repurchase. Subjects were inquirers for the purchase of an entertainment package that visited the destination and were systematically selected over a 12-month period. Results suggest that past behavior, satisfaction, and perceived value are good predictors of entertainment vacationers’ intentions to revisit the destination. It was further found that the variables of past behavior, satisfaction, and perceived value are poor predictors of intentions to visit and attend live theater entertainment or book an entertainment package during a visit. Given the relationships between past behavior, satisfaction, perceived value, and intentions to revisit, results of the present study provide important theoretical implications and direction for entertainment destination management.

Effect of distributed generation on protective device coordination in distribution system

Abstract: Protection of a power system is an extremely important aspect as the duality and scheme of protection decides system reliability, controllability and stability. This paper concentrates on the protection of a distribution system in the light of developments in distributed generation (DG). The conventional distribution system is radial in nature, characterized by a single source feeding a network of down-stream feeders. The protection system has traditionally been designed assuming the system to be radial. After connecting DG, part of the system may no longer be radial, which means the coordination might not hold. The effect of DG on coordination will depend on size, type and placement of DG. This paper explores the effect of DG on protective device coordination such as fuse-fuse, fuse-recloser and relay-relay. In each case, depending on size and placement of DG, there are some margins in which the coordination may hold and certain cases, where no margin is available. These conditions are identified for each case through coordination graphs.

Deriving benefits from stressful events: the role of engagement in meaningful work and hardiness.

Abstract: This research explored the relationship between the meaningfulness of work, personality hardiness, and deriving long-term benefits from a stressful event. U.S. soldiers participating in a peacekeeping mission to Bosnia completed measures assessing the meaning of their work and personality hardiness midway through a 1-year deployment (mid-deployment) and completed a measure of deriving benefits from the deployment 4-5 months after it was over (postdeployment). Structural equation modeling revealed that personality hardiness was associated with being engaged in meaningful work during the deployment, which was strongly associated with deriving benefits from the deployment months after it was over. Enriching experiences were also associated with deriving benefits from the deployment. Discussion focuses on the linkages between personality processes, meaningful work, and deriving benefits from a stressful experience.

Soluble Dendron-Functionalized Carbon Nanotubes: Preparation, Characterization, and Properties§,‖

Abstract: Lipophilic and hydrophilic dendra which are terminated with long alkyl chains and oligomeric poly(ethylene glycol) moieties, respectively, were synthesized, and these dendron species were used to functionalize single-wall (SWNT) and multiple-wall (MWNT) carbon nanotubes via amidation and esterification reactions. The functionalized carbon nanotube samples are, depending on the functionalities, soluble in common organic solvents, such as hexane and chloroform, and water to form colored homogeneous solutions. Characterizations using NMR, electron microscopy, and optical spectroscopic techniques show that the homogeneous solutions contain carbon nanotubes. A preliminary understanding of the structural features and properties of these soluble dendron-functionalized SWNTs and MWNTs is discussed in terms of results from the characterizations, the defunctionalization reactions, and the trapping of metal nanoparticles by the functionalized nanotubes in solution.

Complete Nucleotide Sequence and Organization of the Atrazine Catabolic Plasmid pADP-1 from Pseudomonas sp. Strain ADP

Abstract: The complete 108,845-nucleotide sequence of catabolic plasmid pADP-1 from Pseudomonas sp. strain ADP was determined. Plasmid pADP-1 was previously shown to encode AtzA, AtzB, and AtzC, which catalyze the sequential hydrolytic removal of s-triazine ring substituents from the herbicide atrazine to yield cyanuric acid. Computational analyses indicated that pADP-1 encodes 104 putative open reading frames (ORFs), which are predicted to function in catabolism, transposition, and plasmid maintenance, transfer, and replication. Regions encoding transfer and replication functions of pADP-1 had 80 to 100% amino acid sequence identity to pR751, an IncPβ plasmid previously isolated from Enterobacter aerogenes. pADP-1 was shown to contain a functional mercury resistance operon with 99% identity to Tn5053. Complete copies of transposases with 99% amino acid sequence identity to TnpA from IS1071 and TnpA from Pseudomonas pseudoalcaligenes were identified and flank each of the atzA, atzB, and atzC genes, forming structures resembling nested catabolic transposons. Functional analyses identified three new catabolic genes, atzD, atzE, and atzF, which participate in atrazine catabolism. Crude extracts from Escherichia coli expressing AtzD hydrolyzed cyanuric acid to biuret. AtzD showed 58% amino acid sequence identity to TrzD, a cyanuric acid amidohydrolase, from Pseudomonas sp. strain NRRLB-12227. Two other genes encoding the further catabolism of cyanuric acid, atzE and atzF, reside in a contiguous cluster adjacent to a potential LysR-type transcriptional regulator. E. coli strains bearing atzE and atzF were shown to encode a biuret hydrolase and allophanate hydrolase, respectively. atzDEF are cotranscribed. AtzE and AtzF are members of a common amidase protein family. These data reveal the complete structure of a catabolic plasmid and show that the atrazine catabolic genes are dispersed on three disparate regions of the plasmid. These results begin to provide insight into how plasmids are structured, and thus evolve, to encode the catabolism of compounds recently added to the biosphere.

Application of rhizobacteria for induced resistance

Abstract: This article provides a review of experiments conducted over a six-year period to develop a biological control system for insect-transmitted diseases in vegetables based on induced systemic resistance (ISR) mediated by plant growth-promoting rhizobacteria (PGPR). Initial experiments investigated the factors involved in treatment with PGPR led to ISR to bacterial wilt disease in cucumber caused by Erwinia tracheiphila. Results demonstrated that PGPR-ISR against bacterial wilt and feeding by the cucumber beetle vectors of E. trachiphiela were associated with reduced concentrations of cucurbitacin, a secondary plant metabolite and powerful beetle feeding stimulant. In other experiments, PGPR induced resistance against bacterial wilt in the absence of the beetle vectors, suggesting that PGPR-ISR protects cucumber against bacterial wilt not only by reducing beetle feeding and transmission of the pathogen, but also through the induction of other plant defense mechanisms after the pathogen has been introduced into the plant. Additional greenhouse and field experiments are described in which PGPR strains were selected for ISR against cucumber mosaic virus (CMV) and tomato mottle virus (ToMoV). Although results varied from year to year, field-grown tomatoes treated with PGPR demonstrated a reduction in the development of disease symptoms, and often a reduction in the incidence of viral infection and an increase in tomato yield. Recent efforts on commercial development of PGPR are described in which biological preparations containing industrial formulated spores of PGPR plus chitosan were formulated and evaluated for use in a transplant soil mix system for developing plants that can withstand disease attack after transplanting in the field.

Effect of van der Waals Interactions on the Raman Modes in Single Walled Carbon Nanotubes

Abstract: We have measured the Raman spectrum of individual single walled carbon nanotubes in solution and compare it to that obtained from the same starting material where the tubes are present in ordered bundles or ropes. Interestingly, the radial mode frequencies for the tubes in solution are found to be approximately 10 cm (-1) higher than those observed for tubes in a rope, in apparent contradiction to lattice dynamics predictions. We suggest that there is no such contradiction, and propose that the upshift is due rather to a decreased energy spacing of the Van Hove singularities in isolated tubes over the spacings in a rope, thereby allowing the same laser excitation to excite different diameter tubes in these two samples.

Ethnic group differences in cognitive ability in employment and educational settings: a meta‐analysis

Abstract: The cognitive ability levels of different ethnic groups have interested psychologists for over a century. Many narrative reviews of the empirical literature in the area focus on the Black-White differences, and the reviews conclude that the mean difference in cognitive ability (9) is approximately 1 standard deviation; that is, the generally accepted effect size is about 1.0. We conduct a meta-analytic review that suggests that the one standard deviation effect size accurately summarizes Black-White differences for college application tests (e.g., SAT) and overall analyses of tests of g for job applicants in corporate settings. However, the 1 standard deviation summary of group differences fails to capture many of the complexities in estimating ethnic group differences in employment settings. For example, our results indicate that job complexity, the use of within job versus across job study design, focus on applicant versus incumbent samples, and the exact construct of interest are important moderators of standardized group differences. In many instances, standardized group differences are less than 1 standard deviation. We conduct similar analyses for Hispanics, when possible, and note that Hispanic-White differences are somewhat less than Black-White differences.

The Physics of Proto-Neutron Star Winds: Implications for r-Process Nucleosynthesis

Abstract: We solve the general-relativistic steady-state eigenvalue problem of neutrino-driven proto-neutron star winds, which immediately follow core-collapse supernova explosions. We provide velocity, density, temperature, and composition profiles and explore the systematics and structures generic to such a wind for a variety of proto-neutron star characteristics. Furthermore, we derive the entropy, dynamical timescale, and neutron-to-seed ratio in the general relativistic framework essential in assessing this site as a candidate for r-process nucleosynthesis. Generally, we find that for a given mass outflow rate (), the dynamical timescale of the wind is significantly shorter than previously thought. We argue against the existence or viability of a high entropy (300 per kB per baryon), long dynamical timescale r-process epoch. In support of this conclusion, we model the proto-neutron star cooling phase, calculate nucleosynthetic yields in our steady-state profiles, and estimate the integrated mass loss. We find that transonic winds enter a high-entropy phase only with very low (1 × 10-9 M☉ s-1) and extremely long dynamical timescale (τρ 0.5 s). Our results support the possible existence of an early r-process epoch at modest entropy (~150) and very short dynamical timescale, consistent in our calculations with a very massive or very compact proto-neutron star that contracts rapidly after the preceding supernova. We explore possible modifications to our models, which might yield significant r-process nucleosynthesis generically. Finally, we speculate on the effect of fallback and shocks on both the wind physics and nucleosynthesis. We find that a termination or reverse shock in the wind, but exterior to the wind sonic point, may have important nucleosynthetic consequences. The potential for the r-process in proto-neutron star winds remains an open question.

Misleading Inferences from Panel Unit‐Root Tests with an Illustration from Purchasing Power Parity

Abstract: Simulations demonstrate that when unit-root behavior is rejected in a Levin and Lin panel test, it is incorrect to infer that all series are stationary. Recent tests proposed by Im, Pesaran and Shin, and by Sarno and Taylor, are also incapable of determining the mix of I(0) and I(1) series in a panel setting. This paper introduces a new unit-root test that allows the researcher to discern which series are I(0) and which ones are I(1). The test has double to triple the power of single-equation augmented Dickey–Fuller tests.

Testing a Software Product Line

Abstract: The software product line approach to the development of software intensive systems has been used by organizations to improve quality, increase productivity and reduce cycle time. These gains require different approaches to a number of the practices in the development organization including testing. The planned variability that facilitates some of the benefits of the product line approach poses a challenge for test-related activities. This chapter provides a comprehensive view of testing at various points in the software development process and describes specific techniques for carrying out the various test-related tasks. These techniques are illustrated using a pedagogical product line developed by the Software Engineering Institute (SEI).

Microcompartments in prokaryotes: carboxysomes and related polyhedra.

Abstract: All cyanobacteria and many chemoautotrophs contain polyhedral inclusion bodies that are bound by a unilamellar protein shell (15, 63). Isolation and enzymatic analysis of the bodies from Halothiobacillus neapolitanus (previously Thiobacillus neapolitanus) revealed that they are filled with ribulose 1,5bisphosphate carboxylase/oxygenase (RuBisCO); therefore they were given the name “carboxysomes” (59). Subsequent studies of both cyanobacteria and chemoautotrophic bacteria have led to the well-accepted conclusion that the “organelles” or microcompartments function to enhance the catalytic properties of the RuBisCO they contain, although the mechanism of this catalytic enhancement is unclear (51, 65). Localization and characterization of the genes encoding carboxysome components has underscored the apparent common function of these bodies in carboxysome-containing autotrophic bacteria. More surprising is the finding that a number of heterotrophic prokaryotes harbor genes homologous to those for carboxysome shell proteins (9, 32, 62). Under proper growth conditions, these bacteria produce polyhedral inclusion bodies that are morphologically similar to carboxysomes, although the cells expressing these bodies contain no RuBisCO and do not fix CO 2 via the Calvin-Benson-Bassham cycle as a major part of their carbon metabolism. This review evaluates the evidence that relates carboxysome structure to function in the carbon metabolism of autotrophic prokaryotes and examines similarities to newly discovered particles found in heterotrophs. The possibility is explored that microcompartmentalization of key metabolic enzymes by carboxysomes and their relatives is a more widely utilized regulatory mechanism in prokaryotes than was previously envisioned.

A metabolic model for acetate uptake under anaerobic conditions by glycogen accumulating organisms: Stoichiometry, kinetics, and the effect of pH.

Abstract: A metabolic model for the stoichiometry of acetate uptake under anaerobic conditions by an enriched culture of glycogen accumulating organisms (GAOs) was developed and tested by experimental studies. Glycogen served as the source of both reducing power and energy to drive the process of acetate uptake. The amount of glycogen consumed and poly-β-hydroxyvalerate (PHV) accumulated in the cells increased with increasing pH, indicating that the energy requirements for acetate uptake increased with pH. The composition of the accumulated poly-β-hydroxyalkanoates (PHAs) was adequately predicted using the assumption that acetyl-CoA and propionyl-CoA condense randomly to produce PHA. In addition, the rate of acetate uptake was strongly affected by the pH. The rate decreased with increasing pH and this dependence could be described with a saturation type of expression. A comparison of the rate of acetate uptake at low pH with the rates observed in enriched cultures of phosphorus accumulating organisms (PAOs) indicated that GAOs are able to compete effectively with PAOs in nutrient removal systems under certain conditions. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 17–31, 2001.