Showing papers by "Michigan State University published in 2001"

Global distribution of perfluorooctane sulfonate in wildlife.

Abstract: Here we report, for the first time, on the global distribution of perfluorooctanesulfonate (PFOS), a fluorinated organic contaminant. PFOS was measured in the tissues of wildlife, including, fish, birds, and marine mammals. Some of the species studied include bald eagles, polar bears, albatrosses, and various species of seals. Samples were collected from urbanized areas in North America, especially the Great Lakes region and coastal marine areas and rivers, and Europe. Samples were also collected from a number of more remote, less urbanized locations such as the Arctic and the North Pacific Oceans. The results demonstrated that PFOS is widespread in the environment. Concentrations of PFOS in animals from relatively more populated and industrialized regions, such as the North American Great Lakes, Baltic Sea, and Mediterranean Sea, were greater than those in animals from remote marine locations. Fisheating, predatory animals such as mink and bald eagles contained concentrations of PFOS that were greater than the concentrations in their diets. This suggests that PFOS can bioaccumulate to higher trophic levels of the food chain. Currently available data indicate that the concentrations of PFOS in wildlife are less than those required to cause adverse effects in laboratory animals.

Personality and Performance at the Beginning of the New Millennium: What Do We Know and Where Do We Go Next?

Abstract: As we begin the new millennium, it is an appropriate time to examine what we have learned about personality-performance relationships over the past century and to embark on new directions for research. In this study we quantitatively summarize the results of 15 prior meta-analytic studies that have investigated the relationship between the Five Factor Model (FFM) personality traits and job performance. Results support the previous findings that conscientiousness is a valid predictor across performance measures in all occupations studied. Emotional stability was also found to be a generalizable predictor when overall work performance was the criterion, but its relationship to specific performance criteria and occupations was less consistent than was conscientiousness. Though the other three Big Five traits (extraversion, openness and agreeableness) did not predict overall work performance, they did predict success in specific occupations or relate to specific criteria. The studies upon which these results are based comprise most of the research that has been conducted on this topic in the past century. Consequently, we call for a moratorium on meta-analytic studies of the type reviewed in our study and recommend that researchers embark on a new research agenda designed to further our understanding of personalityperformance linkages.

Hyperthermophilic Enzymes: Sources, Uses, and Molecular Mechanisms for Thermostability

Abstract: Enzymes synthesized by hyperthermophiles (bacteria and archaea with optimal growth temperatures of >80°C), also called hyperthermophilic enzymes, are typically thermostable (i.e., resistant to irreversible inactivation at high temperatures) and are optimally active at high temperatures. These enzymes share the same catalytic mechanisms with their mesophilic counterparts. When cloned and expressed in mesophilic hosts, hyperthermophilic enzymes usually retain their thermal properties, indicating that these properties are genetically encoded. Sequence alignments, amino acid content comparisons, crystal structure comparisons, and mutagenesis experiments indicate that hyperthermophilic enzymes are, indeed, very similar to their mesophilic homologues. No single mechanism is responsible for the remarkable stability of hyperthermophilic enzymes. Increased thermostability must be found, instead, in a small number of highly specific alterations that often do not obey any obvious traffic rules. After briefly discussing the diversity of hyperthermophilic organisms, this review concentrates on the remarkable thermostability of their enzymes. The biochemical and molecular properties of hyperthermophilic enzymes are described. Mechanisms responsible for protein inactivation are reviewed. The molecular mechanisms involved in protein thermostabilization are discussed, including ion pairs, hydrogen bonds, hydrophobic interactions, disulfide bridges, packing, decrease of the entropy of unfolding, and intersubunit interactions. Finally, current uses and potential applications of thermophilic and hyperthermophilic enzymes as research reagents and as catalysts for industrial processes are described.

What Trust Means in E-Commerce Customer Relationships: An Interdisciplinary Conceptual Typology

Abstract: Trust is a vital relationship concept that needs clarification because researchers across disciplines have defined it in so many different ways. A typology of trust types would make it easier to compare and communicate results, and would be especially valuable if the types of trust related to one other. The typology should be interdisciplinary because many disciplines research e-commerce. This paper justifies a parsimonious interdisciplinary typology and relates trust constructs to e-commerce consumer actions, defining both conceptual-level and operational-level trust constructs. Conceptual-level constructs consist of disposition to trust (primarily from psychology), institution-based trust (from sociology), and trusting beliefs and trusting intentions (primarily from social psychology). Each construct is decomposed into measurable subconstructs, and the typology shows how trust constructs relate to already existing Internet relationship constructs. The effects of Web vendor interventions on consumer behaviors are posited to be partially mediated by consumer trusting beliefs and trusting intentions in the e-vendor.

What is the observed relationship between species richness and productivity

Abstract: Understanding the relationship between species richness and productivity is fundamental to the management and preservation of biodiversity. Yet despite years of study and intense theoretical interest, this relationship remains controversial. Here, we present the results of a literature survey in which we examined the relationship between species richness and productivity in 171 published studies. We extracted the raw data from published tables and graphs and subjected these data to a standardized analysis, using ordinary least-squares (OLS) regression and generalized linear-model (GLIM) regression to test for significant positive, negative, or curvilinear relationships between productivity and species diversity. If the relationship was curvilinear, we tested whether the maximum (or minimum) of the curve occurred within the range of productivity values observed (i.e., was there evidence of a hump?). A meta-analysis conducted on the distribution of standardized quadratic regression coefficients showed that ...

Control of nitrogen export from watersheds by headwater streams

Abstract: A comparative 15 N-tracer study of nitrogen dynamics in headwater streams from biomes throughout North America demonstrates that streams exert control over nutrient exports to rivers, lakes, and estuaries. The most rapid uptake and transformation of inorganic nitrogen occurred in the smallest streams. Ammonium entering these streams was removed from the water within a few tens to hundreds of meters. Nitrate was also removed from stream water but traveled a distance 5 to 10 times as long, on average, as ammonium. Despite low ammonium concentration in stream water, nitrification rates were high, indicating that small streams are potentially important sources of atmospheric nitrous oxide. During seasons of high biological activity, the reaches of headwater streams typically export downstream less than half of the input of dissolved inorganic nitrogen from their watersheds.

Psychiatric Disorders and Drug Use Among Human Immunodeficiency Virus–Infected Adults in the United States

Abstract: Background: There have been no previous nationally representative estimates of the prevalence of mental disorders and drug use among adults receiving care for human immunodeficiency virus (HIV) disease in the United States. It is also not known which clinical and sociodemographic factors are associated with these disorders. Subjects and Methods: We enrolled a nationally representative probability sample of 2864 adults receiving care for HIV in the United States in 1996. Participants were administered a brief structured psychiatric instrument that screened for psychiatric disorders (major depression, dysthymia, generalized anxiety disorders, and panic attacks) and drug use during the previous 12 months. Sociodemographic and clinical factors associated with screening positive for any psychiatric disorder and drug dependence were examined in multivariate logistic regression analyses. Results: Nearly half of the sample screened positive for a psychiatric disorder, nearly 40% reported using an illicit drug other than marijuana, and more than 12% screened positive for drug dependence during the previous 12 months. Factors independently associated with screening positive for a psychiatric disorder included number of HIV-related symptoms, illicit drug use, drug dependence, heavy alcohol use, and being unemployed or disabled. Factors independently associated with screening positive for drug dependence included having many HIV-related symptoms, being younger, being heterosexual, having frequent heavy alcohol use, and screening positive for a psychiatric disorder. Conclusions: Many people infected with HIV may also have psychiatric and/or drug dependence disorders. Clinicians may need to actively identify those at risk and work with policymakers to ensure the availability of appropriate care for these treatable disorders.

The home environments of children in the United States part I: variations by age, ethnicity, and poverty status.

Abstract: Although measures of the home environment have gained wide acceptance in the child development literature, what constitutes the “average” or “typical” home environment in the United States, and how this differs across ethnic groups and poverty status is not known. Item-level data from the National Longitudinal Survey of Youth on four age-related versions of the Home Observation for Measurement of the Environment–Short Form (HOME-SF) from five biennial assessments (1986–1994) were analyzed for the total sample and for four major ethnic groups: European Americans, Asian Americans, African Americans, and Hispanic Americans. The percentages of homes receiving credit on each item of all four versions of the HOME-SF are described. For the majority of items at all four age levels differences between poor and nonpoor families were noted. Differences were also obtained among African American, European American, and Hispanic American families, but the magnitude of the effect for poverty status was greater than for ethnicity, and usually absorbed most of the ethnic group effects on HOME-SF items. For every item at every age, the effects of poverty were proportional across European American, African American, and Hispanic American groups.

On the fragility of skilled performance: what governs choking under pressure?

Abstract: Experiments 1-2 examined generic knowledge and episodic memories of putting in novice and expert golfers. Impoverished episodic recollection of specific putts among experts indicated that skilled putting is encoded in a procedural form that supports performance without the need for step-by-step attentional control. According to explicit monitoring theories of choking, such proceduralization makes putting vulnerable to decrements under pressure. Experiments 3-4 examined choking and the ability of training conditions to ameliorate it in putting and a nonproceduralized alphabet arithmetic skill analogous to mental arithmetic. Choking occurred in putting but not alphabet arithmetic. In putting, choking was unchanged by dual-task training but eliminated by self-consciousness training. These findings support explicit monitoring theories of choking and the popular but infrequently tested belief that attending to proceduralized skills hurts performance.

rrndb: the Ribosomal RNA Operon Copy Number Database

Abstract: The Ribosomal RNA Operon Copy Number Database (rrndb) is an Internet-accessible database containing annotated information on rRNA operon copy number among prokaryotes. Gene redundancy is uncommon in prokaryotic genomes, yet the rRNA genes can vary from one to as many as 15 copies. Despite the widespread use of 16S rRNA gene sequences for identification of prokaryotes, information on the number and sequence of individual rRNA genes in a genome is not readily accessible. In an attempt to understand the evolutionary implications of rRNA operon redundancy, we have created a phylogenetically arranged report on rRNA gene copy number for a diverse collection of prokaryotic microorganisms. Each entry (organism) in the rrndb contains detailed information linked directly to external websites including the Ribosomal Database Project, GenBank, PubMed and several culture collections. Data contained in the rrndb will be valuable to researchers investigating microbial ecology and evolution using 16S rRNA gene sequences. The rrndb web site is directly accessible on the WWW at http://rrndb.cme.msu.edu.

Supply chain collaboration and logistical service performance

Abstract: Collaboration with external supply chain entities influences increased internal collaboration, which in turn improves service performance. This relationship may be the key to helping managers understand how best to facilitate behavioral change. The implication is that collaborating with customers and suppliers is a first step toward effective collaboration within the firm.

Surface modifications of natural fibers and performance of the resulting biocomposites: An overview

Abstract: A review of biocomposites highlighting recent studies and developments in natural fibers, bio-polymers, and various surface modifications of natural fibers to improve fiber-matrix adhesion is presented. One of the most important factors which determine the final performance of the composite materials is the quality of the fiber-matrix interface. A sufficient degree of adhesion between the surface of hydrophilic ligno-cellulosic natural fibers and the polymer matrix resin is usually desired to achieve optimum performance of the biocomposite. Dewaxing, alkali treatment, isocyanate treatment, peroxide treatment, vinyl grafting, bleaching, acetylation, and treatment with coupling agents are useful ways to improve fiber-matrix adhesion in natural fiber composites. Two major areas of biocomposites will be discussed in this article. One is the most predominant biocomposite currently being commercialized for semi-structural use in the durable goods industries, e.g. auto-industries, i.e. natural fiber-polypropylen...

Is ADHD a Disinhibitory Disorder

Abstract: Attention deficit hyperactivity disorder (ADHD) is widely theorized to stem from dysfunctional inhibitory processes. However, the definition of inhibition is imprecisely distinguished across theories. To clarify the evidence for this conception, the author relies on a heuristic distinction between inhibition that is under executive control and inhibition that is under motivational control (anxiety or fear), It is argued that ADHD is unlikely to be due to a motivational inhibitory control deficit, although suggestions are made for additional studies that could overturn that conclusion. Evidence for a deficit in an executive motor inhibition process for the ADHD combined type is more compelling but is not equally strong for all forms of executive inhibitory control. Remaining issues include specificity to ADHD, whether inhibitory problems are primary or secondary in causing ADHD, role of comorbid anxiety and conduct disorder, and functional deficits in the inattentive ADHD subtype.

Learn++: an incremental learning algorithm for supervised neural networks

Abstract: We introduce Learn++, an algorithm for incremental training of neural network (NN) pattern classifiers. The proposed algorithm enables supervised NN paradigms, such as the multilayer perceptron (MLP), to accommodate new data, including examples that correspond to previously unseen classes. Furthermore, the algorithm does not require access to previously used data during subsequent incremental learning sessions, yet at the same time, it does not forget previously acquired knowledge. Learn++ utilizes ensemble of classifiers by generating multiple hypotheses using training data sampled according to carefully tailored distributions. The outputs of the resulting classifiers are combined using a weighted majority voting procedure. We present simulation results on several benchmark datasets as well as a real-world classification task. Initial results indicate that the proposed algorithm works rather well in practice. A theoretical upper bound on the error of the classifiers constructed by Learn++ is also provided.

The Revised Almost Perfect Scale

Abstract: This article describes the development of the Almost Perfect Scale—Revised (APS—R). Exploratory and confirmatory factor analyses and data exploring the reliability and construct validity of the sub...

Image classification for content-based indexing

Abstract: Grouping images into (semantically) meaningful categories using low-level visual features is a challenging and important problem in content-based image retrieval. Using binary Bayesian classifiers, we attempt to capture high-level concepts from low-level image features under the constraint that the test image does belong to one of the classes. Specifically, we consider the hierarchical classification of vacation images; at the highest level, images are classified as indoor or outdoor; outdoor images are further classified as city or landscape; finally, a subset of landscape images is classified into sunset, forest, and mountain classes. We demonstrate that a small vector quantizer (whose optimal size is selected using a modified MDL criterion) can be used to model the class-conditional densities of the features, required by the Bayesian methodology. The classifiers have been designed and evaluated on a database of 6931 vacation photographs. Our system achieved a classification accuracy of 90.5% for indoor/outdoor, 95.3% for city/landscape, 96.6% for sunset/forest and mountain, and 96% for forest/mountain classification problems. We further develop a learning method to incrementally train the classifiers as additional data become available. We also show preliminary results for feature reduction using clustering techniques. Our goal is to combine multiple two-class classifiers into a single hierarchical classifier.

Logistics Service Quality as a Segment-Customized Process

Abstract: Logistics excellence has become a powerful source of competitive differentiation within diverse marketing offerings of world-class firms. Although researchers have suggested that logistics competencies complement marketing efforts, empirical evidence is lacking on what logistics service quality means to customers and whether it has different meanings for separate customer segments. The authors present empirical support for nine related logistics service quality constructs; demonstrate their unidimensionality, validity, and reliability across four customer segments of a large logistics organization; and provide empirical support for a logistics service quality process. Although structural equation modeling offers support for the logistics service quality process across customer segments, the authors find that the relative parameter estimates differ for each segment, which suggests that firms ought to customize their logistics services by customer segments.

The Future of the Brazilian Amazon

Abstract: The Brazilian Amazon is currently experiencing the world9s highest absolute rate of forest destruction and is likely to suffer even greater degradation in the future because of government plans to invest $40 billion from 2000 to 2007 in dozens of major new highways and infrastructure projects. We developed two computer models that integrate spatial data on deforestation, logging, mining, highways and roads, navigable rivers, vulnerability to wildfires, protected areas, and existing and planned infrastructure projects, in an effort to predict the condition of Brazilian Amazonian forests by the year 2020. Both models suggest that the region9s forests will be drastically altered by current development schemes and land-use trends over the next 20 years.

Information Fusion in Biometrics

Abstract: User verification systems that use a single biometric indicator often have to contend with noisy sensor data, restricted degrees of freedom and unacceptable error rates. Attempting to improve the performance of individual matchers in such situations may not prove to be effective because of these inherent problems. Multimodal biometric systems seek to alleviate some of these drawbacks by providing multiple evidences of the same identity. These systems also help achieve an increase in performance that may not be possible by using a single biometric indicator. This paper addresses the problem of information fusion in verification systems. Experimental results on combining three biometric modalities (face, fingerprint and hand geometry) are also presented.

Protein flexibility predictions using graph theory

Abstract: Techniques from graph theory are applied to analyze the bond networks in proteins and identify the flexible and rigid regions. The bond network consists of distance constraints defined by the covalent and hydrogen bonds and salt bridges in the protein, identified by geometric and energetic criteria. We use an algorithm that counts the degrees of freedom within this constraint network and that identifies all the rigid and flexible substructures in the protein, including overconstrained regions (with more crosslinking bonds than are needed to rigidify the region) and underconstrained or flexible regions, in which dihedral bond rotations can occur. The number of extra constraints or remaining degrees of bond-rotational freedom within a substructure quantifies its relative rigidity/flexibility and provides a flexibility index for each bond in the structure. This novel computational procedure, first used in the analysis of glassy materials, is approximately a million times faster than molecular dynamics simulations and captures the essential conformational flexibility of the protein main and side-chains from analysis of a single, static three-dimensional structure. This approach is demonstrated by comparison with experimental measures of flexibility for three proteins in which hinge and loop motion are essential for biological function: HIV protease, adenylate kinase, and dihydrofolate reductase.

Gender and the Internet: Women Communicating and Men Searching

Abstract: This research examined gender differences in Internet use and factors responsible for these differences. A sample of 630 Anglo American undergraduates completed the Student Computer and Internet Survey that contained questions about e-mail and Web use, and about potential affective and cognitive mediators of use. Based on a general model of Internet use, we predicted and found that females used e-mail more than did males, males used the Web more than did females, and females reported more computer anxiety, less computer self-efficacy, and less favorable and less stereotypic computer attitudes. Path analysis to identify mediators of gender differences in Internet use revealed that computer self-efficacy, loneliness, and depression accounted in part for gender differences, but that gender continued to have a direct effect on use after these factors were considered. Implications for realizing the democratizing potential and benefits of Internet use are discussed.

Complete genomic sequence of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120

Abstract: The nucleotide sequence of the entire genome of a filamentous cyanobacterium, Anabaena sp. strain PCC 7120, was determined. The genome of Anabaena consisted of a single chromosome (6,413,771 bp) and six plasmids, designated pCC7120α (408,101 bp), pCC7120β (186,614 bp), pCC7120γ (101,965 bp), pCC7120δ (55,414 bp), pCC7120e (40,340 bp), and pCC7120ζ (5,584 bp). The chromosome bears 5368 potential protein-encoding genes, four sets of rRNA genes, 48 tRNA genes representing 42 tRNA species, and 4 genes for small structural RNAs. The predicted products of 45% of the potential protein-encoding genes showed sequence similarity to known and predicted proteins of known function, and 27% to translated products of hypothetical genes. The remaining 28% lacked significant similarity to genes for known and predicted proteins in the public DNA databases. More than 60 genes involved in various processes of heterocyst formation and nitrogen fixation were assigned to the chromosome based on their similarity to the reported genes. One hundred and ninety-five genes coding for components of two-component signal transduction systems, nearly 2.5 times as many as those in Synechocystis sp. PCC 6803, were identified on the chromosome. Only 37% of the Anabaena genes showed significant sequence similarity to those of Synechocystis, indicating a high degree of divergence of the gene information between the two cyanobacterial strains.

Evolution of digital organisms at high mutation rates leads to survival of the flattest

Abstract: Darwinian evolution favours genotypes with high replication rates, a process called 'survival of the fittest'. However, knowing the replication rate of each individual genotype may not suffice to predict the eventual survivor, even in an asexual population. According to quasi-species theory, selection favours the cloud of genotypes, interconnected by mutation, whose average replication rate is highest. Here we confirm this prediction using digital organisms that self-replicate, mutate and evolve. Forty pairs of populations were derived from 40 different ancestors in identical selective environments, except that one of each pair experienced a 4-fold higher mutation rate. In 12 cases, the dominant genotype that evolved at the lower mutation rate achieved a replication rate >1.5-fold faster than its counterpart. We allowed each of these disparate pairs to compete across a range of mutation rates. In each case, as mutation rate was increased, the outcome of competition switched to favour the genotype with the lower replication rate. These genotypes, although they occupied lower fitness peaks, were located in flatter regions of the fitness surface and were therefore more robust with respect to mutations.

Ecological degradation in protected areas : The case of Wolong Nature Reserve for Giant Pandas

Abstract: It is generally perceived that biodiversity is better protected from human activities after an area is designated as a protected area. However, we found that this common perception was not true in Wolong Nature Reserve (southwestern China), which was established in 1975 as a “flagship” protected area for the world-renowned endangered giant pandas. Analyses of remote sensing data from pre- and post-establishment periods indicate that the reserve has become more fragmented and less suitable for giant panda habitation. The rate of loss of high-quality habitat after the reserve9s establishment was much higher than before the reserve was created, and the fragmentation of high-quality habitat became far more severe. After the creation of the reserve, rates of habitat loss and fragmentation inside the reserve unexpectedly increased to levels that were similar to or higher than those outside the reserve, in contrast to the situation before the reserve was created.

The home environments of children in the United States part II: relations with behavioral development through age thirteen.

Abstract: This study examined the frequency with which children were exposed to various parental actions, materials, events, and conditions as part of their home environments, and how those exposures related to their well-being. Part 1 focused on variations by age, ethnicity, and poverty status. In Part 2 of the study, relations between major aspects of the home environment (including maternal responsiveness, learning stimulation, and spanking) and developmental outcomes for children from birth through age 13 were investigated. The outcomes examined were early motor and social development, vocabulary development, achievement, and behavior problems. These relations were examined in both poor and nonpoor European American, African American, and Hispanic American families using hierarchical linear modeling. The most consistent relations found were those between learning stimulation and children's developmental status, with relations for parental responsiveness and spanking varying as a function of outcome, age, ethnicity, and poverty status. The evidence indicated slightly stronger relations for younger as compared with older children.

Transnational Networks and Policy Diffusion: The Case of Gender Mainstreaming

Abstract: How can we account for the global diffusion of remarkably similar policy innovations across widely differing nation-states? In an era characterized by heightened globalization and increasingly radical state restructuring, this question has become especially acute. Scholars of international relations offer a number of theoretical explanations for the cross-national convergence of ideas, institutions, and interests. We examine the proliferation of state bureaucracies for gender mainstreaming. These organizations seek to integrate a gender-equality perspective across all areas of government policy. Although they so far have received scant attention outside of feminist policy circles, these mainstreaming bureaucracies—now in place in over 100 countries—represent a powerful challenge to business-as-usual politics and policymaking. As a policy innovation, the speed with which these institutional mechanisms have been adopted by the majority of national governments is unprecedented. We argue that transnational networks composed largely of nonstate actors (notably women's international nongovernmental organizations and the United Nations) have been the primary forces driving the diffusion of gender mainstreaming. In an event history analysis of 157 nation-states from 1975 to 1998, we assess how various national and transnational factors have affected the timing and the type of the institutional changes these states have made. Our findings support the claim that the diffusion of gender-mainstreaming mechanisms has been facilitated by the role played by transnational networks, in particular by the transnational feminist movement. Further, they suggest a major shift in the nature and the locus of global politics and national policymaking.

The influence of complementarity, compatibility, and relationship capital on alliance performance

Abstract: Value creation through alliances requires the simultaneous pursuit of partners with similar characteristics on certain dimensions and different characteristics on other dimensions. Partnering firms need to have different resource and capability profiles yet share similarities in their social institutions. In this article, the authors empirically examine the impact of partner characteristics on the performance of alliances. In particular, they test hypotheses related to both direct impact of partner characteristics on alliance performance and indirect effects through relational capital aspects of the alliance. Empirical results based on a sample of alliances in the global construction contracting industry suggest that complementarity in partner resources and compatibility in cultural and operational norms have different direct and indirect effects on alliance performance. Accordingly, organizational routines aimed at partner selection need to be complemented by relationship management routines to maximize the potential benefits from an alliance.

Helping Novices Learn to Teach: Lessons from an Exemplary Support Teacher

Abstract: There is growing interest in the problem of teacher induction and widespread support for the idea of assigning experienced teachers to work with beginning teachers. Still, we know relatively little...