Showing papers by "Clemson University published in 1992"
TL;DR: Substantial progress has been made in the understanding of how biomineralization occurs, and the first steps are now being taken to exploit the basic principles involved.
Abstract: Many organisms construct structural ceramic (biomineral) composites from seemingly mundane materials; cell-mediated processes control both the nucleation and growth of mineral and the development of composite microarchitecture. Living systems fabricate biocomposites by: (i) confining biomineralization within specific subunit compartments; (ii) producing a specific mineral with defined crystal size and orientation; and (iii) packaging many incremental units together in a moving front process to form fully densified, macroscopic structures. By adapting biological principles, materials scientists are attempting to produce novel materials. To date, neither the elegance of the biomineral assembly mechanisms nor the intricate composite microarchitectures have been duplicated by nonbiological processing. However, substantial progress has been made in the understanding of how biomineralization occurs, and the first steps are now being taken to exploit the basic principles involved.
515 citations
TL;DR: In this article, the authors present the results of a two-part study exploring consumers' perceptions about situations they face as consumers, and which have potential ethical content, and identify three factors that affect consumers' perception regarding the ethical content of these situations: the locus of the fault, the presence of deception on the part of the consumer, and the degree of harm.
511 citations
TL;DR: In this paper, the authors collected quality deviation data from nine fast-track industrial construction projects and identified the direct costs associated with rework (including redesign, repair, and replacement).
Abstract: Quality deviation data are collected from nine fast‐track industrial construction projects. The data are collected after the construction phase of the projects and identify the direct costs associated with rework (including redesign), repair, and replacement. Analyses of the data indicate that deviations on the projects accounted for an average of 12.4% of the total project costs. Furthermore, design deviations average 78% of the total number of deviations, 79% of the total deviation costs, and 9.5% of the total project cost. Construction deviations average 16% of the total number of deviations, 17% of the total deviation costs, and 2.5% of the total project cost. These values are conservative because they consider only direct costs, but they are indications of the areas that cause the greatest impact on total project costs. By applying the procedures presented in this paper to its historical records, a company can identify not only its deviation costs, but also the most likely areas on which to focus to ...
429 citations
TL;DR: The major conclusion from this investigation is the fact that by explicitly testing for simple faults, the authors are also implicitly testing for more complicated faults, giving us confidence that fault-based testing is an effective way to test software.
Abstract: Fault-based testing strategies test software by focusing on specific, common types of faults. The coupling effect hypothesizes that test data sets that detect simple types of faults are sensitive enough to detect more complex types of faults. This paper describes empirical investigations into the coupling effect over a specific class of software faults. All of the results from this investigation support the validity of the coupling effect. The major conclusion from this investigation is the fact that by explicitly testing for simple faults, we are also implicitly testing for more complicated faults, giving us confidence that fault-based testing is an effective way to test software.
394 citations
TL;DR: In this article, a method for the computation of fault location in two and three-terminal high voltage lines is presented based on digital computation of the three-phase current and voltage 60/50 Hz phasors at the line terminals.
Abstract: A method for the computation of fault location in two- and three-terminal high voltage lines is presented. It is based on digital computation of the three-phase current and voltage 60/50 Hz phasors at the line terminals. The method is independent of fault type and insensitive to source impedance variation or fault resistance. Furthermore, it considers the synchronization errors in sampling the current and voltage waveforms at the different line terminals. The method can be used online following the operation of digital relays or offline using data transferred to a central processor from digital transient recording apparatus. The authors start with a two-terminal line to explain the principles and then present the technique for a three-terminal line. The technique was first tested using data obtained from a steady-state fault analysis program to evaluate the convergence, observability, and uniqueness of the solution. The technique was then tested using EMPT-generated transient data. The test results show the high accuracy of the technique. >
366 citations
TL;DR: In this article, four combinations of season and frequency of burning were applied in Coastal Plain loblolly pine stands over a 43-year period, and the results emphasize that frequent burning over a long period is needed to create and maintain the pine-grassland community observed by the first European settlers of the southeast.
298 citations
TL;DR: In this paper, it was shown that the high-temperature, high-entropy evacuated region outside the recent neutron star in a core-collapse supernova may be an ideal r-process site.
Abstract: We show that the high-temperature, high-entropy evacuated region outside the recent neutron star in a core-collapse supernova may be an ideal r-process site. In this high-entropy environment it is possible that most nucleons are in the form of free neutrons or bound into alpha particles. Thus, there can be many neutrons per seed nucleus even though the material is not particularly neutron rich. The predicted amount of r-process material ejected per event from this environment agrees well with that required by simple galactic evolution arguments. When averaged over regions of different neutron excess in the supernova ejecta, the calculated r-process abundance curve can give a good representation of the solar-system r-process abundances as long as the entropy per baryon is sufficiently high. Neutrino irradiation may aid in smoothing the final abundance distribution.
264 citations
TL;DR: In this paper, the authors show that there is no general equivalence between the existence of arbitrage opportunities and cointegration or, for that matter, a lack of co-integration, and that whether asset prices are cointegrated is a function of the relevant model.
247 citations
TL;DR: This article investigated whether the characterization of the liquidity effect is sensitive to changes in sample period, conditioning the correlations on past information, assuming money growth is exogenous, and treating monetary changes as anticipated or unanticipated.
241 citations
TL;DR: Viviparity first makes its evolutionary appearance within the craniate-vertebrate line among fishes and is estimated to have independently evolved at least 42 times in five of the nine major groups of fishes.
Abstract: Viviparity first makes its evolutionary appearance within the craniate-vertebrate line among fishes. We estimate that it has independently evolved at least 42 times in five of the nine major groups of fishes. Viviparity is the dominant mode of reproduction among the cartilaginous sharks and rays, i.e. , 55% of approximately 900 living species. It is less prevalent among the five major groups of bony fishes, i.e. , 2–3% of an estimated 20,000 or more species. The evolution of viviparity from oviparity involves: 1) a shift from external to internal fertilization; 2) retention of embryos in the female reproductive system; 3) utilization of the ovaryor oviduct as sites of gestation; 4) structural and functional modification of the embryo and the female reproductive system and; 5) modification of extant endocrine mechanisms controlling reproduction. Viviparity offers selective advantages to parents and offspring, such as: 1) enhanced survival of offspring; 2) compensation for low fecundity; 3) amplification of reproductive niches to reduce competition; 4) exploitation of pelagic niches; 5) colonization of new habitats; and 6) increased energetic efficiency in viviparous matrotrophes. Its principal disadvantages include: 1) reduced fecundity; 2) cost to the female; and 3) risk of brood loss through maternal death. Acquisition of viviparityestablishes new maternal-embryonic relationships, namely: 1) trophic; 2) osmoregulatory and excretory; 3) respiratory; 4) endocrinological; and 5) immunological. In sharks, rays, and the coelacanth, gestation takes place in the oviduct, but in teleosts gestation occurs either in the ovarian follicle or ovarian lumen. The cystovarian teleostean ovary is hypothesized to function both as ovary and oviduct. Oviductal, ovarian lumenal, andfollicular epithelial cells are the maternal sites of metabolic exchange. Metabolic exchange inembryos takes place across the epithelia of the general body surface and its derivatives or across the gut epithelium and its derivatives. Four patterns of piscine placentation have evolved,namely: 1) yolk sac; 2) follicular; 3) branchial; and 4) trophotaenial placentae. The pericardial amniochorion, the embryonic portion of the follicular placenta, occurs in poeciliids and several other teleostean groups. Developmental, it is nearly identical to the anterior aminochorionic fold of tetrapod vertebrates. Trophotaeniae are external rosette or ribbon-like structuresthat have evolved in four orders of teleosts by heterochrony, i.e. , accelerated outgrowth and differentiation of the embryonic hind gut. With the possible exception of the coelacanth, theyolk sac placenta occurs only in sharks. We estimate that it has independently evolved between 11 and 20 times. It displays considerable diversity. Evolution of the yolk sac placenta entails retention of the yolk sac and secondary differentiation of its distal portion for implantation and maternal tissue-embryonic tissue metabolic exchange and its proximal portion for oviductal fluid-embryonic tissue exchange. The yolk stalk lengthens, is modified into an umbilical stalk, and establishes a site of autotomy at the embryo-umbilical stalk junction. The lumenal wall of the oviduct becomes competent to function as a site of implantation.
207 citations
TL;DR: In this article, a semi-empirical kinetic equation, − d [ AN ] dt = k 1 [ AN ][ APS ] + k 2 ′[ AN ][ P ], where [P] = equivalent concentration of polymer, is proposed for this autoaccelerated reaction.
TL;DR: Recreation specialization proposes that participation in an activity progresses along a continuum from general to specific modes of perception and behavior as discussed by the authors, and typically measures an individual's individua...
Abstract: Recreation specialization proposes that participation in an activity progresses along a continuum from general to specific modes of perception and behavior. Research typically measures an individua...
TL;DR: In this article, a low-cost, qualitative evaluation scheme using a fuzzy set analysis for mapping slope failure potential (SFP) was proposed, where four categories of factors affecting stability of natural slopes, i.e., geology, topography, meteorology, and environment, are considered.
Abstract: This paper documents a low-cost, qualitative evaluation scheme using a fuzzy set analysis for mapping slope failure potential (SFP). Four categories of factors affecting stability of natural slopes, i.e., geology, topography, meteorology, and environment, are considered. Each category involves two to five factors, and a total of 13 factors is used in the proposed evaluation scheme. A set of evaluation criteria was established for each adopted factor. In the proposed evaluation scheme, slope failure potential is assessed and recorded in linguistic terms based on the established criteria. The linguistic data or information obtained from the assessments is represented and processed using fuzzy sets. In this study, the analysis or computation involving fuzzy sets was performed using the Monte Carlo simulation technique. An SFP index to measure the slope failure potential is defined. Based on the computed SFP values for a large number of subareas or cells selected for an area studied, an SFP map can be developed. An example application is presented to demonstrate the method. The SFP map developed in the case study seems to be able to correctly predict the slope failure potential of the area studied.
TL;DR: In this article, a tracking controller for rigid-link electrically-driven (RLED) robot manipulators is proposed, which is robust with regard to parametric uncertainties and additive bounded disturbances while correcting for the typically ignored electrical actuator dynamics.
Abstract: This paper illustrates a simple, hand-crafted approach which can be used to design tracking controllers for rigid-link electrically-driven (RLED) robot manipulators. The control methodology is intuitively simple since it is based on concepts readily identified by most control engineers. To illustrate the approach, we develop a corrective tracking controller for the RLED robot dynamics which yields global exponential stability for the link tracking error under the assumption of exact model knowledge. To compensate for the uncertainties in the rigid-link electrically-driven robot model, we then design a corrective robust tracking controller which yields global uniform ultimate bounded stability of the link tracking error. The proposed controller is robust with regard to parametric uncertainties and additive bounded disturbances while correcting for the typically ignored electrical actuator dynamics.
TL;DR: For the period starting with the floating of the US dollar, the authors found evidence that long-run stationarity of the demand function for M2 (but not M1) requires inclusion of the effective exchange rate.
TL;DR: In this paper, three key dimensions that distinguish the various forms of observational methods are presented and general applications of observational research to services marketing phenomena are posited, as well as specific application of observational data collection methods to services quality are suggested.
Abstract: Applications of observational data collection methods to services marketing research are explored. Three key dimensions that distinguish the various forms of observational methods are presented. General applications of observational research to services marketing phenomena are posited. Specific applications of observational research to services quality are suggested. Issues concerning the implementation of direct human observation are considered.
TL;DR: In this paper, the congener-specific aqueous solubilities (S) and Henry's Law constants (HLCs) of polychlorinated biphenyls (PCBs) were generated based on molecular models which were sensitive to slight changes in chemical structure.
Abstract: Quantitative structure-property relationship (QSPR) models have been developed which accurately calculate the congener-specific aqueous solubilities (S) and Henry's Law constants (HLCs) of polychlorinated biphenyls (PCBs). QSPRs were generated based on molecular models which were sensitive to slight changes in chemical structure. PCB aqueous solubilities were found to be a function of total surface area, melting point, and third shadow area. Observed HLCs were a function of the second moment of inertia, path-four connectivity index, path-three K index, and the second and third principal polarizabilities.
TL;DR: Evidence that organic material exists within diatom biosilica and can be extracted using HF/NH4F solutions from frustules isolated from Cyclotella meneghiniana Kütz and diatomaceous earth is presented and indirect evidence is presented that suggests the soluble proteins may contain regions of primary structure enriched in anionic amino acids.
Abstract: Most biominerals appear to be composites of organic material and mineral. Whether biosilica is such a composite is unresolved because of a lack of evidence for such organic components. We present evidence that organic material exists within diatom biosilica and can be extracted using HF/NH4F solutions from frustules isolated from Cyclotella meneghiniana Kutz and diatomaceous earth. To eliminate organic casing on the silicified frustules as a source of organic materials, the casing was removed by oxidation of frustules with NaOCl before extraction. The removal of the casing was confirmed in that oxidized frustules no longer displayed the ability to be stained with ruthenium red and fluorescamine. Frustules examined with EDXA showed an emission peak from sulfur before treatment but no peak following treatment, indicating that oxidation removed organic sulfur. The organic material obtained from extracts of fresh frustules contained both soluble and insoluble components. Only soluble material was evident in extracts from diatomaceous earth. The soluble material appears to contain glycoproteins with relatively high levels of serine and glycine. The soluble proteins from fresh frustules also appear to be phosphorylated. Indirect evidence is presented that suggests the soluble proteins may contain regions of primary structure enriched in anionic amino acids. The soluble extracts differ from general cell contents when the two fractions are compared, suggesting that frustules contain specialized organic material. The identification of silica-specific organic material suggests that mineralization in diatoms may be in part matrix-mediated.
TL;DR: In this article, the problems of state observation and state trajectory control by output feedback for the class of non-linear systems in [3,11] were examined and specific time-varying bounds on the observation error and the state trajectory were also developed; revealing how the corresponding observer or control parameters can be adjusted to improve the system performance.
TL;DR: This paper conducted a survey of 1,353 high school students from abusive and non-abusive households in a rural area of North Dakota and found that less than one in five of them reported dating violence, providing little support for the cycle of violence hypothesis.
Abstract: Social scientists have theorized about the cycle of domestic violence in family abuse. Little research has addressed dating violence as a consequence to the experience of domestic violence by children. This article deals with the self-reported experience of dating violence by high school students from abusive and nonabusive households. A survey was conducted of 1,353 students in a rural area of North Dakota. Results indicated that students from abusive households showed significantly higher incidence of dating violence than those from homes where no abuse was evident. However, less than one in five of the students from abusive home reported dating violence, providing little support for the cycle of violence hypothesis. Students from abusive homes viewed violence as negatively as students from nonabusive homes. Thus, while there are significant differences between the two groups, there are also important similarities. Although there is apparently a greater risk of dating violence among students who have experienced violence at home, these data do not support the idea of an inescapable pattern of violence among adolescents who have experienced violence themselves.
TL;DR: For instance, this article found that mothers who are restrictive and warm in relationships with children are also more likely to use communication messages that promote monitoring and control of children's consumption activities, while mothers who generally respect and solicit children's opinions also tend to utilize messages that foster the development of consumption decision-making abilities in children.
TL;DR: Seven different silicone surface textures were tested for effect on macrophage spreading and metabolic activity in vitro and a hypothesis is introduced that includes a possible mechanism of how a micrometre-sized surface texture could modify cell function.
TL;DR: In this paper, it was shown that Co-57 radioactivity does not account for most of the current luminosity of the supernova remnant in low optical depth models and suggested alternatives, including a large optical depth model that is able to provide the SN 1987A luminosity.
Abstract: The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory has observed SN 1987A for two 2 week periods during the first 9 months of the mission. Evidence for gamma-ray line and continuum emission from Co-57 is observed with an intensity of about 10 exp -4 gamma/sq cm/s. This photon flux between 50 and 136 keV is demonstrated by Monte Carlo calculations to be independent of the radial distribution of Co-57 for models of low optical depth, viz., models having photoelectric absorption losses of 122 keV photons no greater than several percent. For such models the observed Co-57 flux indicates that the ratio Ni-57/Ni-56 produced in the explosion was about 1.5 times the solar system ratio of Fe-57/Fe-56. When compared with nearly contemporaneous bolometric estimates of the luminosity for SN 1987A, our observations imply that Co-57 radioactivity does not account for most of the current luminosity of the supernova remnant in low optical depth models. We suggest alternatives, including a large optical depth model that is able to provide the SN 1987A luminosity and is consistent with the OSSE flux. It requires a 57/56 production ratio about twice solar.
TL;DR: This work investigated the inhibitor(s) produced by P. jensenii P126 (ATCC 4872) and classification of the inhibitor as a bacteriocin is supported by its proteinaceous nature and its bactericidal activity against L. delbrueckii subsp.
Abstract: The genus Propionibacterium includes cutaneous species typically found on human skin and the dairy or classical species (Propionibacterium freudenreichii, P. jensenii, P. thoenii, and P. acidipropionici) used industrially for the production of Swiss cheese and propionic acid. Grinstead (1989, M.S. thesis, Iowa State University, Ames) has previously observed that some dairy propionibacteria inhibit other species in the classical grouping. We further investigated the inhibitor(s) produced by P. jensenii P126 (ATCC 4872). An antagonist(s) from anaerobic agar cultures of P126 strongly inhibited two closely related strains of propionibacteria, P. acidipropionici P5 and P. jensenii P54, and Lactobacillus bulgaricus NCDO 1489, Lactobacillus delbrueckii subsp. lactis ATCC 4797, Lactococcus cremoris NCDO 799, and Lactococcus lactis subsp. lactis C2. The inhibitor, designated jenseniin G, was active at pH 7.0; inactivated by treatment with pronase E, proteinase K, and type 14 protease; insensitive to catalase; and stable to freezing, cold storage (4 degrees C, 3 days), and heat (100 degrees C, 15 min). Classification of the inhibitor as a bacteriocin is supported by its proteinaceous nature and its bactericidal activity against L. delbrueckii subsp. lactis ATCC 4797. The lack of detectable plasmids suggests a chromosomal location for the determinant(s) of jenseniin G.
TL;DR: It is demonstrated how insight provided by participation in life as woman and also as a feminist suggests testable hypotheses about the evolution of social behavior—hypotheses that are applicable to the authors' investigations of the evolutionof social behavior in nonhuman animals.
Abstract: Evolutionary biology and feminism share a variety of philosophical and practical concerns. I have tried to describe how a perspective from both evolutionary biology and feminism can accelerate the achievement of goals for both feminists and evolutionary biologists. In an early section of this paper I discuss the importance of variation to the disciplines of evolutionary biology and feminism. In the section entitled “Control of Female Reproduction” I demonstrate how insight provided by participation in life as woman and also as a feminist suggests testable hypotheses about the evolution of social behavior—hypotheses that are applicable to our investigations of the evolution of social behavior in nonhuman animals. In the section on “Deceit, Self-deception, and Patriarchal Reversals” I have overtly conceded that evolutionary biology, a scientific discipline, also represents a human cultural practice that, like other human cultural practices, may in parts and at times be characterized by deceit and self-deception. In the section on “Femininity” I have indicated how questions cast and answered and hypotheses tested from an evolutionary perspective can serve women and men struggling with sexist oppression.
TL;DR: In this paper, the social information presented in outfits selected by others to be representative of their personalities, and these perceptions were significantly correlated with the individuals' views of themselves, were found to be related to the identities of individuals who would wear them but only if the clothes are specifically selected by the individuals to represent themselves.
Abstract: Individuals are believed to use clothing to define and communicate their social identities to others. If this is the case, observers should be able to read and show consensus about the social information present in clothing cues, and there should be substantial agreement between the perceived meaning of the cues to observers and the actual social identities of the individuals but only if the clothes are specifically selected by the individuals to represent themselves. In Study 1 observers were able to perceive the social information presented in outfits selected by others to be representative of their personalities, and these perceptions were significantly correlated with the individuals' views of themselves. In Study 2 observers were similarly able to read social information present in jeans brand labels. However, these perceptions were not found to be related to the identities of individuals who would wear them. These findings suggest that clothing may have meaning, but the relationship between clothing...
TL;DR: In this article, the dynamic process of voltage collapse is analyzed based on three mechanisms: on-load tap-changing, load dynamics, and generator excitation limiting, and the interaction among these mechanisms and how the voltage collapse takes place are thoroughly investigated in a general interconnected network model under the assumption that system frequency remains unchanged.
Abstract: The dynamic process of voltage collapse is analyzed based on three mechanisms: on-load tap-changing, load dynamics, and generator excitation limiting. The interaction among these mechanisms and how the voltage collapse takes place are thoroughly investigated in a general interconnected network model under the assumption that system frequency remains unchanged. It is found that, so long as an equilibrium exists, there is a maximal equilibrium. It is also established that there is a region in the state space corresponding to a monotonic fall of system voltages. When the reactive capability of generator(s) is reached, this region expands, whereas the voltage stability region shrinks. The system trajectory may eventually exit the stability region, whereupon the voltage begins to drop monotonically. It is shown that locking the tap-changers at an appropriate time helps the system voltage to reach a steady state, and therefore avoid the collapse. Numerical examples for a realistic power system are given to illustrate the theory. >
TL;DR: Data indicate that cows exposed to biostimulation from either bulls or TTC immediately after calving return to estrus earlier than do cows isolated from biostIMulation.
Abstract: Three experiments were conducted to evaluate the effects of biostimulation (exposure to bulls or androgenized females) on various reproductive variables in suckled beef cows. Bulls or testosterone-treated cows (TTC) were introduced to cows, randomly allotted to one of four groups, within 72 h postpartum. In Exp. 1, Groups 1 and 3 were exposed to bulls and Groups 2 and 4 were exposed to TTC. In Exp. 2, Groups 1 and 3 were exposed to bulls and Groups 2 and 4 served as controls (isolated from biostimulation). In Exp. 3, Groups 1 and 3 were exposed to TTC and Groups 2 and 4 served as controls. Mean postpartum intervals to estrus were not different between cows exposed to either bulls or TTC in Exp. 1 (P greater than .10). However, in Exp. 2 and 3, cows exposed to either bulls or TTC had reduced postpartum intervals to estrus (44 and 41 d, respectively) compared with control cows (52 d; P less than .05). Fewer control cows were in estrus at either 40 d (P less than .05; Exp. 2 and 3) or 60 d (P less than .05; Exp. 3) postpartum than were cows exposed to bulls or TTC. No differences were observed between groups in any experiment for postpartum intervals to pregnancy (P greater than .10). These data indicate that cows exposed to biostimulation from either bulls or TTC immediately after calving return to estrus earlier than do cows isolated from biostimulation.
TL;DR: In this article, a shear deformable (three-dimensional) shell element is used to analyze two panels without boles and one with a bole, and the resulting responses and failure modes comelated well with the experimental results.
Abstract: A shear deformable (three-dimensional) shell element is used to analyze the panels. Two panels without boles and one with a bole are studied, and the resulting responses and failure modes comelated well with the experimental results.
TL;DR: Experimental results using specifications for NASA's planetary lander control software suggest that mutation-based testing could hold greater potential for enhancing reliability than the desirable but perhaps unachievable goal of independence among N versions.
Abstract: A simulation-based method for obtaining numerical estimates of the reliability of N-version, real-time software is proposed. An extended stochastic Petri net is used to represent the synchronization structure of N versions of the software, where dependencies among versions are modeled through correlated sampling of module execution times. The distributions of execution times are derived from automatically generated test cases that are based on mutation testing. Since these test cases are designed to reveal software faults, the associated execution times and reliability estimates are likely to be conservative. Experimental results using specifications for NASA's planetary lander control software suggest that mutation-based testing could hold greater potential for enhancing reliability than the desirable but perhaps unachievable goal of independence among N versions. Nevertheless, some support for N-version enhancement of high-quality, mutation-tested code is also offered. Mutation analysis could also be valuable in the design of fault-tolerant software systems. >