Showing papers by "Purdue University published in 1998"

The Investment Model Scale: Measuring commitment level, satisfaction level, quality of alternatives, and investment size

Abstract: Three studies evaluated the reliability and validity of the Investment Model Scale, an instrument designed to measure four constructs, including commitment level and three bases of dependence-satisfaction level, quality of alternatives, and investment size. In all three studies, reliability analyses revealed good internal consistency among items designed to measure each construct. Also, principal components analyses performed on scale items revealed evidence of four factors, with items designed to measure each construct loading on independent factors. Studies 2 and 3 examined associations of model variables with instruments measuring diverse qualities of relationships and assorted personal dispositions. As anticipated, Investment Model variables were moderately associated with other measures reflecting superior couple functioning (e.g., dyadic adjustment, trust level, inclusion of other in the self), and were essentially unrelated to measures assessing personal dispositions (e.g., need for cognition, self-esteem). In addition, Study 3 demonstrated that earlier measures of Investment Model variables predicted later levels of dyadic adjustment and later relationship status (persisted vs ended). It is hoped that the existence of a reliable and valid Investment Model Scale will promote further research regarding commitment and interdependence in ongoing close relationships.

The interaction of race, gender, and age in criminal sentencing: The punishment cost of being young, black, and male

Abstract: Prior theory and research on sentencing oversimplify the role of race, gender and age in judicial decision making. In this article we present a “focal concerns” theory of judicial decision making to frame hypotheses regarding the effects on sentencing of these social statuses, both singly and in combination. Analyzing statewide sentencing outcomes in Pennsylvania for 1989–1992, we find that, net of controls: (1) young black males are sentenced more harshly than any other group, (2) race is most influential in the sentencing of younger rather than older males, (3) the influence of offender's age on sentencing is greater among males than females, and (4) the main effects of race, gender, and age are more modest compared to the very large differences in sentencing outcomes across certain age-race-gender combinations. These findings demonstrate the importance of considering the joint effects of race, gender, and age on sentencing, and of using interactive rather than additive models.

The paleontology of intergene retrotransposons of maize

Abstract: Retrotransposons, transposable elements related to animal retroviruses, are found in all eukaryotes investigated and make up the majority of many plant genomes Their ubiquity points to their importance, especially in their contribution to the large-scale structure of complex genomes The nature and frequency of retro-element appearance, activation and amplification are poorly understood in all higher eukaryotes Here we employ a novel approach to determine the insertion dates for 17 of 23 retrotransposons found near the maize adh1 gene, and two others from unlinked sites in the maize genome, by comparison of long terminal repeat (LTR) divergences with the sequence divergence between adh1 in maize and sorghum All retrotransposons examined have inserted within the last six million years, most in the last three million years The structure of the adh1 region appears to be standard relative to the other gene-containing regions of the maize genome, thus suggesting that retrotransposon insertions have increased the size of the maize genome from approximately 1200 Mb to 2400 Mb in the last three million years Furthermore, the results indicate an increased mutation rate in retrotransposons compared with genes

Inclusion Chemistry in Periodic Mesoporous Hosts

Abstract: This review provides an overview of different aspects of inclusion chemistry in ordered mesoporous host materials such as MCM-41 or MCM-48 (Mobil codes). A rich field of inclusion chemistry has been explored in this context, including sorption, ion exchange, imbibition followed by reduction, grafting of reactive metal alkoxides, halides etc., grafting of silane coupling agents (sometimes followed by subsequent reactions), grafting of reactive metal complexes, and polymerization in the channels. Finally, co-condensation of reactive species during the mesopore synthesis is a method to incorporate functionality into the walls of the channel system. Important applications of these modified and functionalized systems are heterogeneous catalysis and photocatalysis involving bulky grafted catalysts and/or the conversion of large substrates. Other potential applications include ion exchange and separations, removal of heavy metals, chromatography, stabilization of quantum wires, stabilization of dyes, and polymer...

Nonlinear wavelet image processing: variational problems, compression, and noise removal through wavelet shrinkage

Abstract: This paper examines the relationship between wavelet-based image processing algorithms and variational problems. Algorithms are derived as exact or approximate minimizers of variational problems; in particular, we show that wavelet shrinkage can be considered the exact minimizer of the following problem. Given an image F defined on a square I, minimize over all g in the Besov space B11(L1(I)) the functional |F-g|L2(I)2+λ|g|(B11(L1(I))). We use the theory of nonlinear wavelet image compression in L2(I) to derive accurate error bounds for noise removal through wavelet shrinkage applied to images corrupted with i.i.d., mean zero, Gaussian noise. A new signal-to-noise ratio (SNR), which we claim more accurately reflects the visual perception of noise in images, arises in this derivation. We present extensive computations that support the hypothesis that near-optimal shrinkage parameters can be derived if one knows (or can estimate) only two parameters about an image F: the largest α for which F∈Bqα(Lq(I)),1/q=α/2+1/2, and the norm |F|Bqα(Lq(I)). Both theoretical and experimental results indicate that our choice of shrinkage parameters yields uniformly better results than Donoho and Johnstone's VisuShrink procedure; an example suggests, however, that Donoho and Johnstone's (1994, 1995, 1996) SureShrink method, which uses a different shrinkage parameter for each dyadic level, achieves a lower error than our procedure.

The biology of leptin: a review.

Abstract: Leptin, a 16-kDa protein secreted from white adipocytes, has been implicated in the regulation of food intake, energy expenditure, and whole-body energy balance in rodents and humans. The gene encoding leptin was identified by positional cloning and is the mutation leading to the profound obese phenotype of the ob/ob mouse. Exogenous administration of leptin to ob/ob mice leads to a significant improvement in reproductive and endocrine status as well as reduced food intake and weight loss. The expression and secretion of leptin is highly correlated with body fat mass and adipocyte size. Cortisol and insulin are potent stimulators of leptin expression, and expression is attenuated by beta-adrenergic agonists, cAMP, and thiazolidinediones. The role of other hormones and growth factors in the regulation of leptin expression and secretion is emerging. Leptin circulates specifically bound to proteins in serum, which may regulate its half-life and biological activity. Isoforms of the leptin receptor, members of the interleukin-6 cytokine family of receptors, are found in multiple tissues, including the brain. Many of leptin's effects on food intake and energy expenditure are thought to be mediated centrally via neurotransmitters such as neuropeptide Y. Multiple peripheral effects of leptin have also been recently described, including the regulation of insulin secretion by pancreatic beta cells and regulation of insulin action and energy metabolism in adipocytes and skeletal muscle. Leptin is thought to be a metabolic signal that regulates nutritional status effects on reproductive function. Leptin also plays a major role in hematopoeisis and in the anorexia accompanying an acute cytokine challenge. The profound effects of leptin on regulating body energy balance make it a prime candidate for drug therapies for humans and animals.

The Use of Biological Assays to Evaluate Botanicals

Abstract: The Department of Medicinal Chemistry and Molecular Pharmacology’s laboratory has adopted four “bench top” bioassays which do not require higher animals to screen and direct the fractionation of botanical extracts in drug discovery efforts. These are: 1. The brine shrimp lethality test (BST) (a general bioassay), 2. The inhibition of crown gall tumors on discs of potato tubers (an antitumor bioassay), 3. The inhibition of frond proliferation in duckweed (a bioassay for herbicides and plant growth stimulants), and 4. The yellow fever mosquito larvae lethality test (a bioassay for pesticides). The materials and procedures for those bioassays will be briefly described. The authors’ results in applying these simple methods in the discovery of Annonaceous acetogenins will be presented to illustrate their successful use. The BST is especially suggested as an inexpensive, simple, and rapid means of standardization of bioactivity in heterogeneous botanical products.

Summarizing Single-Subject Research Issues and Applications

Abstract: In this article, literature concerning the quantitative synthesis (meta-analysis) of single subject research literature is reviewed. First, the general rationale for such an approach is discussed. Next, procedures for synthesizing single-subject literature are described, followed by comments and critiques of those procedures. Finally, a review is presented of the results of applications of those procedures. The authors suggest that procedures based on percentage of nonoverlapping data (PND) between baseline and treatment are justifiable, meaningful, and--across nine applications--have produced results that are highly meaningful and faithful to the original research reports.

Cognitive Interdependence: Commitment and the Mental Representation of Close Relationships

Abstract: On the basis of an interdependence analysis, it is proposed that commitment to a close relationship is associated with cognitive interdependence—a mental state characterized by a pluralistic, collective representation of the self-in-relationship. A cross-sectiona l survey study and a 2-wave longitudinal study revealed that strong commitment to a romantic relationship is associated with greater spontaneous plural pronoun usage, greater perceived unity of self and partner, and greater reported relationship centrality. Commitment and cognitive interdependence operate in a cycle of mutual influence, such that earlier commitment predicts change over time in cognitive interdependence, and earlier cognitive interdependence predicts change over time in commitment. Links between commitment and cognitive interdependence were weak or nonsignifican t for relationships among best friends, suggesting that this phenomenon may be unique to romantic relationships. Involvement in a close relationship can change individuals in fundamental ways. For example, close involvement can produce changes in everyday activity preferences, arising from attempts to coordinate activities with those of a significant other (cf. Berscheid, Snyder, & Omoto, 1989; Van Lange et al., 1997). Close involvement can also change the ways in which we communicate; for instance, increasing commitment is associated with enhanced tendencies to accommodate, or to diminish negative reciprocity during the course of interaction (cf. Gottman, 1979; Rusbult, Verette, Whitney, Slovik, & Lipkus, 1991). Does close involvement modify mental representations of the self or change the manner in which we think about ourselves in relation to our partners? The present work asserts that increasing relationship commitment is accompanied by a restructuring of selfin-relationship mental representations, including tendencies to perceive ourselves less as individuals and more as part of a

Governance and uncertainty: the trade-off between administrative control and commitment

Abstract: This study elaborates upon the motives for initiating equity-based collaborations vs. acquisition of another firm already having a desired technology. We characterize both minority direct investments and joint ventures as options to defer either internal development or acquisition of a target firm. In domains where learning about growth opportunities dominates investment activity, this incremental mode of governance economizes on the cost of committing resources to a technology with an uncertain value. Using a sample of 402 transactions in the biotechnology industry, we find strong support for the theoretical model. The findings suggest that the cost of commitment in the face of technological uncertainty may offset the administrative benefits of hierarchical governance. ? 1998 John Wiley & Sons, Ltd.

An architecture for intrusion detection using autonomous agents

Abstract: The intrusion detection system architectures commonly used in commercial and research systems have a number of problems that limit their configurability, scalability or efficiency. The most common shortcoming in the existing architectures is that they are built around a single monolithic entity that does most of the data collection and processing. In this paper, we review our architecture for a distributed intrusion detection system based on multiple independent entities working collectively. We call these entities autonomous agents. This approach solves some of the problems previously mentioned. We present the motivation and description of the approach, partial results obtained from an early prototype, a discussion of design and implementation issues, and directions for future work.

Genetically Engineered Saccharomyces Yeast Capable of Effective Cofermentation of Glucose and Xylose

Abstract: Xylose is one of the major fermentable sugars present in cellulosic biomass, second only to glucose. However, Saccharomyces spp., the best sugar-fermenting microorganisms, are not able to metabolize xylose. We developed recombinant plasmids that can transform Saccharomyces spp. into xylose-fermenting yeasts. These plasmids, designated pLNH31, -32, -33, and -34, are 2μm-based high-copy-number yeast-E. coli shuttle plasmids. In addition to the geneticin resistance and ampicillin resistance genes that serve as dominant selectable markers, these plasmids also contain three xylose-metabolizing genes, a xylose reductase gene, a xylitol dehydrogenase gene (both from Pichia stipitis), and a xylulokinase gene (from Saccharomyces cerevisiae). These xylose-metabolizing genes were also fused to signals controlling gene expression from S. cerevisiae glycolytic genes. Transformation of Saccharomyces sp. strain 1400 with each of these plasmids resulted in the conversion of strain 1400 from a non-xylose-metabolizing yeast to a xylose-metabolizing yeast that can effectively ferment xylose to ethanol and also effectively utilizes xylose for aerobic growth. Furthermore, the resulting recombinant yeasts also have additional extraordinary properties. For example, the synthesis of the xylose-metabolizing enzymes directed by the cloned genes in these recombinant yeasts does not require the presence of xylose for induction, nor is the synthesis repressed by the presence of glucose in the medium. These properties make the recombinant yeasts able to efficiently ferment xylose to ethanol and also able to efficiently coferment glucose and xylose present in the same medium to ethanol simultaneously.

The Effect of Institutional Investors on the Level and Mix of Ceo Compensation

Abstract: This study investigated the influence of institutional investors on CEO compensation policy. Results suggest that institutional owners that have only an investment relationship with a firm influenc...

Supervised classification in high-dimensional space: geometrical, statistical, and asymptotical properties of multivariate data

Abstract: The recent development of more sophisticated remote-sensing systems enables the measurement of radiation in many more spectral intervals than was previously possible. An example of this technology is the AVIRIS system, which collects image data in 220 bands. The increased dimensionality of such hyperspectral data greatly enhances the data's information content, but provides a challenge to the current techniques for analyzing such data. Human experience in 3D space tends to mislead our intuition of geometrical and statistical properties in high-dimensional space, properties which must guide our choices in the data analysis process. Using Euclidean and Cartesian geometry, high-dimensional space properties are investigated in this paper, and their implication for high-dimensional data and its analysis is studied in order to illuminate the differences between conventional spaces and hyperdimensional space.

Vertical Specialization and the Changing Nature of World Trade

Abstract: A major feature of globalization has been the enormous increase in international flows of goods and services: countries are now trading much more with each other. In this article, the authors demonstrate the greater role vertical specialization is playing in these increased flows. Vertical specialization occurs when a country uses imported intermediate parts to create a good it later exports - that is, the country links sequentially with other countries to produce a final good. Deriving evidence from four case studies as well as OECD input-output tables, the authors reveal that vertical specialization has accounted for a large and increasing share of international trade over the last several decades. They also note that because the trends encouraging vertical specialization - lower trade barriers and improvements in transportation and communications technologies - are likely to continue, this type of international trade should become even more prevalent in the next century.

Prevention of Protein Adsorption by Tethered Poly(ethylene oxide) Layers: Experiments and Single-Chain Mean-Field Analysis

Abstract: Prevention of protein adsorption by the surface-grafted poly(ethylene oxide) (PEO) chains has been well-known. We have examined the mechanisms of how the grafted PEO prevents protein adsorption. PEO−poly(propylene oxide)−PEO (PEO−PPO−PEO) triblock copolymers were used to graft PEO to the trichlorovinylsilane (TCVS)-modified glass by γ-irradiation. The surface density of the PEO chains was varied up to 60 pmol/cm2 and the number of the ethylene oxide (EO) units of the PEO segment was varied from 75 to 128. The adsorption of lysozyme and fibrinogen to the PEO-grafted glass was examined using radiolabeled proteins. The surface protein concentration decreased as the surface density of the grafted PEO increased, but surface protein concentration never reached zero. The experimental data were compared with the predictions by the single-chain mean-field theory. There was very good agreement between the predictions of the theory and the experimental observations. It was found that the mechanism for prevention of ...

Inactivation of the mitogen-activated protein kinase Mps1 from the rice blast fungus prevents penetration of host cells but allows activation of plant defense responses

Abstract: The rice blast fungus, Magnaporthe grisea, generates enormous turgor pressure within a specialized cell called the appressorium to breach the surface of host plant cells. Here, we show that a mitogen-activated protein kinase, Mps1, is essential for appressorium penetration. Mps1 is 85% similar to yeast Slt2 mitogen-activated protein kinase and can rescue the thermosensitive growth of slt2 null mutants. The mps1-1Delta mutants of M. grisea have some phenotypes in common with slt2 mutants of yeast, including sensitivity to cell-wall-digesting enzymes, but display additional phenotypes, including reduced sporulation and fertility. Interestingly, mps1-1Delta mutants are completely nonpathogenic because of the inability of appressoria to penetrate plant cell surfaces, suggesting that penetration requires remodeling of the appressorium wall through an Mps1-dependent signaling pathway. Although mps1-1Delta mutants are unable to cause disease, they are able to trigger early plant-cell defense responses, including the accumulation of autofluorescent compounds and the rearrangement of the actin cytoskeleton. We conclude that MPS1 is essential for pathogen penetration; however, penetration is not required for induction of some plant defense responses.

Fabrication of Nanocolumns for Liquid Chromatography

Abstract: This paper shows that in situ micromachining can be used to simultaneously position and define (i) support particles, (ii) convective transport channels, (iii) an inlet distribution network of channels, and (iv) outlet channels in multiple chromatography columns on a single quartz wafer to the level of a few tenths of a micrometer. Stationary phases were bonded to 5 × 5 × 10 μm collocated monolith support structures separated by rectangular channels 1.5 μm wide and 10 μm deep with a low degree of deviation of channel width between the top and bottom of channels. High aspect ratio microfabrication can only be achieved with deep reactive ion etching. The volume of a 150 μm × 4.5 cm column was 18 nL. Column efficiency was evaluated in the capillary electrochromatography (CEC) mode using rhodamine 123 and a hydrocarbon stationary phase. Plate heights in these columns were typically 0.6 μm in the nonretained and 1.3 μm in the retained modes of operation. Columns were designed to have identical mobile-phase vel...

Molecular-genetic analysis of plant cytochrome p450-dependent monooxygenases.

Abstract: Cytochrome P450-dependent monooxygenases are a large group of heme-containing enzymes, most of which catalyze NADPH- and O2-dependent hydroxylation reactions. The cloning of plant P450s has been hampered because these membrane-localized proteins are typically present in low abundance and are often unstable to purification. Since the cloning of the first plant P450 gene in 1990, there has been an explosion in the rate at which genes encoding plant P450s have been identified. These successes have largely been the result of advances in purification techniques, as well as the application of alternative methods such as mutant- and PCR-based cloning strategies. The availability of these cloned genes has made possible the analysis of P450 gene regulation and may soon reveal aspects of the evolution of P450s in plants. This new knowledge will significantly improve our understanding of many metabolic pathways and may permit their manipulation in the near future.

Measurements of the meson-photon transition form factors of light pseudoscalar mesons at large momentum transfer

Abstract: Using the CLEO II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons {pi}{sup 0}, {eta}, and {eta}{prime}. From our measurements we have obtained the form factors associated with the electromagnetic transitions {gamma}*{gamma} {yields} meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV2 for {pi}{sup 0}, {eta}, and {eta}{prime}, respectively, and have made comparisons to various theoretical predictions.

The Sovereign Limits of Global Civil Society: A Comparison of NGO Participation in UN World Conferences on the Environment, Human Rights, and Women

Abstract: The increased visibility of nongovernmental organizations (NGOs) and social movements at the international level invites continuing evaluation of the extent and significance of the role they now play in world politics. While the presence of such new actors is easily demonstrated, international relations scholars have debated their significance. The authors argue that the concept of global civil society sets a more demanding standard for the evaluation of transnational political processes than has been applied in prior accounts of transnational activity. Further, most empirical studies of this activity have focused on a limited number of NGOs within a single issue-area. Using three recent UN world conferences as examples of mutual encounters between state-dominated international politics and global civic politics, the authors develop the concept of global civil society to provide a theoretical foundation for a systematic empirical assessment of transnational relations concerning the environment, human rights, and women at the global level.