Showing papers by "Iowa State University published in 1999"

Longman Grammar of Spoken and Written English

Abstract: * Over 350 tables and graphs show the frequency of constructions in different contexts, from conversation to fiction to academic prose * Entirely corpus-based with 6000 authentic examples from the 40 million-word Longman Spoken and Written English Corpus * Suggests the reasons why we choose a particular structure in a particular context * Compares British and American spoken and written English Areas covered include basic grammar: description and distribution, key word classes and their phrases and complex structures. Each area is subdivided into more detailed content.

Randomized kinodynamic planning

Abstract: The paper presents a state-space perspective on the kinodynamic planning problem, and introduces a randomized path planning technique that computes collision-free kinodynamic trajectories for high degree-of-freedom problems. By using a state space formulation, the kinodynamic planning problem is treated as a 2n-dimensional nonholonomic planning problem, derived from an n-dimensional configuration space. The state space serves the same role as the configuration space for basic path planning. The bases for the approach is the construction of a tree that attempts to rapidly and uniformly explore the state space, offering benefits that are similar to those obtained by successful randomized planning methods, but applies to a much broader class of problems. Some preliminary results are discussed for an implementation that determines the kinodynamic trajectories for hovercrafts and satellites in cluttered environments resulting in state spaces of up to twelve dimensions.

Effects of Amylopectin Branch Chain Length and Amylose Content on the Gelatinization and Pasting Properties of Starch

Abstract: Structures and properties of starches isolated from different botanical sources were investigated. Apparent and absolute amylose contents of starches were determined by measuring the iodine affinity of defatted whole starch and of fractionated and purified amylopectin. Branch chain-length distributions of amylopectins were analyzed quantitatively using a high-performance anion-exchange chromatography system equipped with a postcolumn enzyme reactor and a pulsed amperometric detector. Thermal and pasting properties were measured using differential scanning calorimetry and a rapid viscoanalyzer, respectively. Absolute amylose contents of most of the starches studied were lower than their apparent amylose contents. This difference correlated with the number of very long branch chains of amylopectin. Studies of amylopectin structures showed that each starch had a distinct branch chain-length distribution profile. Average degrees of polymerization (dp) of amylopectin branch chain length ranged from 18...

Sonochemistry: Science and Engineering

Abstract: Sonochemistry is the use of ultrasound to enhance or alter chemical reactions. Sonochemistry in the true sense of the term occurs when ultrasound induces “true” chemical effects on the reaction system, such as forming free radicals which accelerate the reaction. However, ultrasound may have other mechanical effects on the reaction, such as increasing the surface area between the reactants, accelerating dissolution, and/or renewing the surface of a solid reactant or catalyst. This comprehensive review summarizes several topics of study in the sonochemical literature, including bubble dynamics, factors affecting cavitation, the effects of ultrasound on a variety of chemical systems, modeling of kinetic and mass-transfer effects, the methods used to produce ultrasound, proposed cavitation reactors, and the problems of scaleup. The objective of this paper is to present a critical review of information available in the literature so as to facilitate and inspire future research in the field of sonochemistry.

Adoption of new information technologies in rural small businesses

Abstract: The media discussion on `information superhighway', `Internet' and `national information infrastructure (NII)' has highlighted the potential of information technology in modern society. The changes in information and communication technologies provide both opportunities and threats to small businesses located in rural communities. The objective of this study is to identify the state of use of various communications technologies and the factors that influence the adoption of these technologies in small businesses located in rural communities in the US. A research model is postulated that contains 10 independent variables under three broad categories — innovation, organizational and environmental characteristics. The dependent variable, adoption of information and communication technologies, is measured as the degree of adoption of four modern communication technologies by the organization. Data from 78 organizations were collected using a structured interview process. The results of data analysis using discriminant analysis indicate that relative advantage, top management support, organizational size, external pressure and competitive pressure are important determinants of adoption.

Individual differences in social comparison: Development of a scale of social comparison orientation

Abstract: Development and validation of a measure of individual differences in social comparison orientation (the Iowa-Netherlands Comparison Orientation Measure [INCOM]) are described. Assuming that the tendency toward social comparison is universal, the scale was constructed so as to be appropriate to and comparable in 2 cultures: American and Dutch. It was then administered to several thousand people in each country. Analyses of these data are presented indicating that the scale has good psychometric properties. In addition, a laboratory study and several field studies are described that demonstrated the INCOM's ability to predict comparison behavior effectively. Possible uses of the scale in basic and applied settings are discussed.

An Integrated Genetic Linkage Map of the Soybean Genome

Abstract: A number of molecular genetic maps of the soybean [Glycine max (L.) Merr.] have been developed over the past 10 yr. These maps are primarily based on restriction fragment length polymorphism (RFLP) markers. Parental surveys have shown that most RFLP loci have only two known alleles. However, because the soybean is an ancient polyploid, RFLP probes typically hybridize and map to more than one position in the genome. Thus, the polymorphic potential of an RFLP probe is primarily a function of the frequency of the two alleles at each locus the probe detects. In contrast, simple sequence repeat (SSR) markers are single locus markers with multiple alleles. The polymorphic potential of an SSR marker is dependent on the number of alleles and their frequencies. Single locus markers provide an unambiguous means of defining linkage group homology across mapping populations. The objective of the work reported here was to develop and map a large set of SSR markers. A total of 606 SSR loci were mapped in one or more of three populations: the USDA/Iowa State G. max × G. soja F 2 population, the Univ. of Utah Minsoy × Noir 1 recombinant inbred population, and the Univ. of Nebraska Clark × Harosoy F 2 population. Each SSR mapped to a single locus in the genome, with a map order that was essentially identical in all three populations. Many SSR loci were segregating in two or all three populations. Thus, it was relatively simple to align the 20+ linkage groups derived from each of the three populations into a consensus set of 20 homologous linkage groups presumed to correspond to the 20 pairs of soybean chromosomes. On the basis of in situ segregation or linkage reports in the literature all but one of the classical linkage groups can now be assigned to a corresponding molecular linkage group.

Tailored Porous Materials

Abstract: Tailoring of porous materials involves not only chemical synthetic techniques for tailoring microscopic properties such as pore size, pore shape, pore connectivity, and pore surface reactivity, but also materials processing techniques for tailoring the meso- and the macroscopic properties of bulk materials in the form of fibers, thin films, and monoliths. These issues are addressed in the context of five specific classes of porous materials: oxide molecular sieves, porous coordination solids, porous carbons, sol−gel-derived oxides, and porous heteropolyanion salts. Reviews of these specific areas are preceded by a presentation of background material and review of current theoretical approaches to adsorption phenomena. A concluding section outlines current research needs and opportunities.

Repression of lignin biosynthesis promotes cellulose accumulation and growth in transgenic trees

Abstract: Because lignin limits the use of wood for fiber, chemical, and energy production, strategies for its downregulation are of considerable interest. We have produced transgenic aspen (Populus tremuloides Michx.) trees in which expression of a lignin biosynthetic pathway gene Pt4CL1 encoding 4-coumarate:coenzyme A ligase (4CL) has been downregulated by antisense inhibition. Trees with suppressed Pt4CL1 expression exhibited up to a 45% reduction of lignin, but this was compensated for by a 15% increase in cellulose. As a result, the total lignin-cellulose mass remained essentially unchanged. Leaf, root, and stem growth were substantially enhanced, and structural integrity was maintained both at the cellular and whole-plant levels in the transgenic lines. Our results indicate that lignin and cellulose deposition could be regulated in a compensatory fashion, which may contribute to metabolic flexibility and a growth advantage to sustain the long-term structural integrity of woody perennials.

Information-theoretic determination of minimax rates of convergence

Abstract: We present some general results determining minimax bounds on statistical risk for density estimation based on certain information-theoretic considerations. These bounds depend only on metric entropy conditions and are used to identify the minimax rates of convergence.

Genetic Reassortment of Avian, Swine, and Human Influenza A Viruses in American Pigs

Abstract: In late summer through early winter of 1998, there were several outbreaks of respiratory disease in the swine herds of North Carolina, Texas, Minnesota, and Iowa. Four viral isolates from outbreaks in different states were analyzed genetically. Genotyping and phylogenetic analyses demonstrated that the four swine viruses had emerged through two different pathways. The North Carolina isolate is the product of genetic reassortment between H3N2 human and classic swine H1N1 influenza viruses, while the others arose from reassortment of human H3N2, classic swine H1N1, and avian viral genes. The hemagglutinin genes of the four isolates were all derived from the human H3N2 virus circulating in 1995. It remains to be determined if either of these recently emerged viruses will become established in the pigs in North America and whether they will become an economic burden.

Reproductive Development in Grain Crops during Drought

Abstract: Reproductive development of plants is highly vulnerable to water deficit. Stress early during this phase can delay or completely inhibit flowering, both through an inhibition of floral induction and development. The stage of meiosis is perhaps the most stress-sensitive period of reproduction in all species studied. A meiotic-stage water deficit causes pollen sterility, but usually affects female fertility only under extreme stress. Sterility occurs even though the reproductive structures of stressed plants maintain a high water status, indicating that the response is probably mediated by a sporocidal signal from elsewhere in the plant. Rice and maize plants are also highly vulnerable during flowering (anthesis) and early grain initiation. Stress during this period can cause loss of pollen fertility, failure of pollination, spikelet death, or zygotic abortion. Changes in carbohydrate availability and metabolism appear to be involved in the effects of stress during meiosis and anthesis. Stress during early grain development curtails the kernel sink potential by reducing the number of endosperm cells and amyloplasts formed. Controls underlying these effects are poorly understood, although hormones may be involved. A water deficit during any stage of grain development causes the premature cessation of grain filling. Kernel moisture content and its direct impact on metabolism appear to be key regulatory factors in shortening the duration of grain filling.

Stimulus Sampling and Social Psychological Experimentation

Abstract: The authors discuss the problem with failing to sample stimuli in social psychological experimentation. Although commonly construed as an issue for external validity, the authors emphasize how failure to sample stimuli also can threaten construct validity. They note some circumstances where the need for stimulus sampling is less obvious and more obvious, and they discuss some well-known cognitive biases that can contribute to the failure of researchers to see the need for stimulus sampling. Data are presented from undergraduate students (N = 106), graduate students (N = 72), and psychology faculty (N = 48) showing insensitivity to the need for stimulus sampling except when the problem is made rather obvious. Finally, some of the statistical implications of stimulus sampling with particular concern for power, effect size estimates, and data analysis strategies are noted.

Couple resilience to economic pressure.

Abstract: Over 400 married couples participated in a 3-year prospective study of economic pressure and marital relations. The research (a) empirically evaluated the family stress model of economic stress influences on marital distress and (b) extended the model to include specific interactional characteristics of spouses hypothesized to protect against economic pressure. Findings provided support for the basic mediational model, which proposes that economic pressure increases risk for emotional distress, which, in turn, increases risk for marital conflict and subsequent marital distress. Regarding resilience to economic stress, high marital support reduced the association between economic pressure and emotional distress. In addition, effective couple problem solving reduced the adverse influence of marital conflict on marital distress. Overall, the findings provided substantial support for the extended family stress model.

JML: A Notation for Detailed Design

Abstract: JML is a behavioral interface specification language tailored to Java. It is designed to be written and read by working software engineers, and should require only modest mathematical training. It uses Eiffel-style syntax combined with model-based semantics, as in VDM and Larch. JML supports quantifiers, specification-only variables, and other enhancements that make it more expressive for specification than Eiffel and easier to use than VDM and Larch.

Immunoassay readout method using extrinsic Raman labels adsorbed on immunogold colloids

Abstract: An immunoassay readout method based on surface-enhanced Raman scattering (SERS) is described. The method exploits the SERS-derived signal from reporter molecules that are coimmobilized with biospecific species on gold colloids. This concept is demonstrated in a dualanalyte sandwich assay, in which two different antibodies covalently bound to a solid substrate specifically capture two different antigens from an aqueous sample. The captured antigens in turn bind selectively to their corresponding detection antibodies. The detection antibodies are conjugated with gold colloids that are labeled with different Raman reporter molecules, which serve as extrinsic labels for each type of antibody. The presence of a specific antigen is established by the characteristic SERS spectrum of the reporter molecule. A near-infrared diode laser was used to excite efficiently the SERS signal while minimizing fluorescence interference. We show that, by using different labels with little spectral overlap, two different antigenic species can be detected simultaneously. The potential of this concept to function as a readout strategy for multiple analytes is briefly discussed.

A mini binary vector series for plant transformation.

Abstract: A streamlined mini binary vector was constructed that is less than 1/2 the size of the pBIN19 backbone (3.5 kb). This was accomplished by eliminating over 5 kb of non-T-DNA sequences from the pBIN19 vector. The vector still retains all the essential elements required for a binary vector. These include a RK2 replication origin, the nptIII gene conferring kanamycin resistance in bacteria, both the right and left T-DNA borders, and a multiple cloning site (MCS) in between the T-DNA borders to facilitate cloning. Due to the reduced size, more unique restriction sites are available in the MCS, thus allowing more versatile cloning. Since the traF region was not included, it is not possible to mobilize this binary vector into Agrobacterium by triparental mating. This problem can be easily resolved by direct transformation. The mini binary vector has been demonstrated to successfully transform Arabidopsis plants. Based on this mini binary vector, a series of binary vectors were constructed for plant transformation.

Research in the Psychological Laboratory Truth or Triviality

Abstract: This article examines the truism that studies from psychological laboratories are low in external validity. Past rational and empirical explorations of this truism found little support for it. A broader empirical approach was taken for the study reported here; correspondence between lab and field was compared across a broad range of domains, including aggression, helping, leadership style, social loafing, self-efficacy, depression, and memory, among others. Correspondence between lab- and field-based effect sizes of conceptually similar independent and dependent variables was considerable. In brief, the psychological laboratory has generally produced psychological truths, rather than trivialities. These same data suggest that a companion truism about field studies in psychology—that they are generally low on internal validity—is also false.

Statistical methods for testing functional divergence after gene duplication.

Abstract: Functional innovations after gene duplication may result in altered functional constraints between member gene clusters of a gene family. This type (type I) of functional divergence is measured by the coefficient of functional divergence (theta lambda), which can be interpreted as the decrease in rate correlation between gene clusters, or the probability that the evolutionary rate at a site is statistically independent between two gene clusters. A simple stochastic model has been developed for estimating theta lambda and testing its statistical significance. The current model includes the model of rate variation among sites as a special case when theta lambda = 0. Moreover, we have developed a site-specific profile based on the hidden Markov model to identify critical amino acid residues that are responsible for these functional differences between two gene clusters, which may have great potential in functional genomics.

Haddad, Lawrence, John Hoddinott, and Harold Alderman, eds. Intrahousehold Resource Allocation in Developing Countries: Models, Methods, and Policy. Baltimore MD: Johns Hopkins University Press, 1997, 384 pp., $55.00

Abstract: In this volume economists, demographers, sociologists and anthropologists collaborate in the study of how resources are allocated within households in developing countries and why it matters from a policy perspective. Surveying a broad range of theory and evidence, the contributors examine the many social and cultural factors that influence decisions about the family and household level about the allocation of time, income, assets and other resources. Ths contributors show that a more complete understanding of intrahousehold behaviour can increase the likelihood that policies will reach the people they are intended to affect.

Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages.

Abstract: The effects of different polyphenol-containing beverages on Fe absorption from a bread meal were estimated in adult human subjects from the erythrocyte incorporation of radio-Fe. The test beverages contained different polyphenol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.), vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), pennyroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages were potent inhibitors of Fe absorption and reduced absorption in a dose-dependent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/serving reduced Fe absorption from the bread meal by 50-70%, whereas beverages containing 100-400 mg total polyphenols/serving reduced Fe absorption by 60-90%. Inhibition by black tea was 79-94%, peppermint tea 84%, pennyroyal 73%, cocoa 71%, vervain 59%, lime flower 52% and camomile 47%. At an identical concentration of total polyphenols, black tea was more inhibitory than cocoa, and more inhibitory than herb teas camomile, vervain, lime flower and pennyroyal, but was of equal inhibition to peppermint tea. Adding milk to coffee and tea had little or no influence on their inhibitory nature. Our findings demonstrate that herb teas, as well as black tea, coffee and coca can be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.

A Research Model of Sustainable Family Businesses

Abstract: This paper proposes a research model that outlines the determinants of functional families and profitable businesses—requisites for family business sustainability. Two features distinguish the model from previous models: inclusion of the family in the same detail as the business and emphasis on the key features of family and business. Delineation of the interface between the family and the business permits the use of research methods that allow for variable degrees of overlap of family and business rather than assuming that family businesses constitute either a single system or two separate systems. The research model is also compatible with a variety of theoretical perspectives.

Comparison of Fumonisin Concentrations in Kernels of Transgenic Bt Maize Hybrids and Nontransgenic Hybrids.

Abstract: Munkvold, G. P., Hellmich, R. L., and Rice, L. G. 1999. Comparison of fumonisin concentrations in kernels of transgenic Bt maize hybrids and nontransgenic hybrids. Plant Dis. 83:130138. Maize hybrids genetically engineered with genes from the bacterium Bacillus thuringiensis (Bt maize) express CryIA(b) and other Cry proteins that are toxic to certain insects, particularly the European corn borer (Ostrinia nubilalis). Maize kernel feeding by O. nubilalis often leads to infection by fungi in the genus Fusarium, including the fumonisin-producing species F. verticillioides and F. proliferatum. In field experiments in 1995, 1996, and 1997, transgenic maize hybrids and near-isogenic, nontransgenic hybrids were manually infested with neonatal European corn borer larvae. Manual infestation increased Fusarium ear rot severity and fumonisin concentrations in kernels of nontransgenic hybrids. Transgenic hybrids with kernel expression of CryIA(b) consistently experienced less insect feeding on kernels and less Fusarium ear rot than their nontransgenic counterparts. In manually infested treatments, these hybrids also exhibited lower concentrations of fumonisins in kernels compared with their nontransgenic counterparts. In manually infested treatments in 1995, mean fumonisin B 1 concentrations were 8.8 µg/g in the nontransgenic hybrid and 6.7 or 3.0 µg/g in transgenic hybrids. In 1996, mean fumonisin B1 concentrations in manually infested treatments were 4.9 µg/g (range 2.3 to 8.8) for nontransgenic and 1.2 µg/g (range 1.0 to 1.3) for transgenic hybrids with kernel expression. Mean total fumonisin concentrations (fumonisin B 1 + B2 + B3) were 7.0 µg/g (range 3.0 to 12.2) for nontransgenic and 1.7 µg/g (range 1.5 to 1.9) for transgenic hybrids with kernel expression. In 1997, mean fumonisin B1 concentrations in manually infested treatments were 11.8 µg/g (range 7.6 to 17.3) for nontransgenic and 1.3 µg/g (range 0.8 to 2.2) for transgenic hybrids with kernel expression of CryIA(b) or Cry9C. Mean total fumonisin concentrations were 16.5 µg/g (range 10.7 to 24.0) for nontransgenic and 2.1 µg/g (range 1.5 to 3.1) for transgenic hybrids with kernel expression. Transgenic hybrids that do not express CryIA(b) or Cry9C in kernels did not consistently have fumonisin concentrations different from the nontransgenic hybrids. Higher fumonisin concentrations in nontransgenic hybrids were associated with high European corn borer populations during the early reproductive stages of the maize plants. These results indicate that under some conditions, genetic engineering of maize for insect resistance may enhance its safety for animal and human consumption.

Using the science writing heuristic as a tool for learning from laboratory investigations in secondary science

Abstract: This article presents and discusses preliminary research on a new heuristic tool for learning from laboratory activities in secondary science. The tool, called the science writing heuristic, can be used by teachers as a framework from which to design classroom activities. Theoretically, the science writing heuristic represents a bridge between traditional laboratory reports and types of writing that promote personal construction of meaning. Two eighth-grade classes participated in using the science writing heuristic during an 8-week stream study. The teacher and one of the researchers collaboratively developed activities based on the science writing heuristic that the teacher implemented. Nineteen target students were studied in depth. Characteristics of report writing and students' understanding of the nature of science were investigated, using interpretive techniques. There is evidence that use of the science writing heuristic facilitated students to generate meaning from data, make connections among procedures, data, evidence, and claims, and engage in metacognition. Students' vague understandings of the nature of science at the beginning of the study were modified to more complex, rich, and specific understandings. The implications of the study for writing in science classrooms is discussed. © 1999 John Wiley & Sons, Inc. J Res Sci Teach 36: 1065–1084, 1999

Attitude formation from product trial: Distinct roles of cognition and affect for hedonic and functional products

Abstract: Affective and cognitive responses to a product trial are examined in an experiment containing two cells representing two product types: hedonic and functional. The stimulus products were a computer game and grammar-checking software. Forty-two college students comprised the sample for the experiment. The specific affective responses studied are pleasure and arousal, and brand cognitions are represented as the expectancy value from brand attributes (the product of brand beliefs, belief confidence, and attribute evaluations, summed across the attributes (σ biciei)). The relative level and influence of affective and cognitive responses to a product trial were shown to differ significantly, depending on whether the product was hedonic or functional in nature. Specifically, for the hedonic product, felt arousal during the trial was higher than for the functional product, and emotional responses were significant antecedents of subjects' evaluations of the trial experience. Brand cognitions, however, were not significantly related to trial evaluations for the hedonic product. In contrast, for the functional product, brand cognitions and pleasure were significant antecedents of trial evaluations, but arousal was not. The findings of this study demonstrate the importance of considering both the cognitive structure created by a product trial and the consumer's emotional reactions to the trial. For hedonic products, especially, emotional responses to the trial were shown to be powerful antecedents to consumers' evaluations of a trial experience, and subsequently, brand attitude. Marketers and marketing researchers can use these results to predict which category of responses to product trial (affective or cognitive) will be most important for brand evaluation for the particular product in question. This knowledge may also enable marketers to manipulate aspects of a product trial that are most influential on the set of trial responses that this study has shown to significantly affect brand evaluation for that product type. © 1999 John Wiley & Sons, Inc.