Showing papers by "Michigan State University published in 1993"

What Is Coefficient Alpha? An Examination of Theory and Applications

Abstract: Coefficient alpha (Cronbach, 1951) is certainly one of the most important and pervasive statistics in research involving test construction and use. A review of the Social Sciences Citations Index for the literature from 1966 to 1990 revealed that Cronbach's (1951) article had been cited approximately 60 times per year and in a total of 278 different journals. In addition to the areas of psychology in which one may expect to see alpha used, such as educational, industrial, social, clinical, child, community, and abnormal psychology, this list of journals included representatives from experimental psychology, sociology, statistics, medicine, counseling, nursing, economics, political science, criminology, gerontology, broadcasting, anthropology, and accounting. In spite of its widespread use, however, there is some confusion as to the true meaning and proper interpretation of the statistic. In this article I address this confusion in two ways. First, a theoretical discussion of alpha is presented. This includes some of the many statements that have been made about alpha and an attempt to integrate these statements. Second, I take a more practical approach in which the interpretation of alpha is examined by observing the changes in alpha as the number of items and interitem correlations are manipulated.

Econometric Methods for Fractional Response Variables with an Application to 401(K) Plan Participation Rates

Abstract: We offer simple quasi-likelihood methods for estimating regression models with a fractional dependent variable and for performing asymptotically valid inference. Compared with log-odds type procedures, there is no difficulty in recovering the regression function for the fractional variable, and there is no need to use ad hoc transformations to handle data at the extreme values of zero and one. We also offer some new, simple specification tests by nesting the logit or probit function in a more general functional form. We apply these methods to a data set of employee participation rates in 401(k) pension plans.

Age and Gender Differences in Children's Self‐ and Task Perceptions during Elementary School

Abstract: We examined the development of children's self- and task perceptions during the elementary school years. 865 first-, second,- and fourth-grade children (ages 7-10) completed questionnaires assessing their perceptions of competence in, and valuing of, activities in several activity domains (math, reading, sports, and instrumental music). Factor analyses showed that even the first graders had differentiated self-beliefs for the various activities. These analyses also indicated that children's competence beliefs and subjective task values formed distinct factors. Analyses assessing age and gender differences in children's beliefs showed that for all the activities except sports, younger children's (particularly the first graders) perceptions of competence and subjective task values were more positive than the beliefs of the older children. Boys had more positive competence beliefs and values than did girls for sport activities, and more positive competence beliefs for mathematics. Girls had more positive competence beliefs and values than did boys for reading and music activities.

Second Language Acquisition: An Introductory Course

Abstract: Part One: Preliminaries Chapter One: Introduction 1.1 THE STUDY OF SECOND LANGUAGE ACQUISITION 1.2 DEFINITIONS 1.3 THE NATURE OF LANGUAGE 1.3.1 Semantics 1.3.2 Pragmatics 1.3.3 Syntax 1.3.4 Morphology and the Lexicon 1.3.5 Sound Systems 1.4 THE NATURE OF NONNATIVE SPEAKER KNOWLEDGE 1.5 CONCLUSION Chapter Two: Where Do Data Come From? 2.1 DATA TYPES 2.2 LEARNER CORPORA 2.3 DATA ELICITATION 2.3.1 Measuring General Proficiency 2.3.2 Measuring Nonlinguistic Information 2.3.3 Verbal Report Data 2.3.3.1 Think-Alouds 2.3.3.2 Stimulated Recall 2.3.3.3 Post-Production Interviews 2.3.4 Narrative Inquiry 2.3.5 Language-Elicitation Measures 2.3.5.1 Elicited Imitation 2.3.5.2 Judgments 2.3.5.3 Language Games 2.3.5.4 Discourse Completion 2.3.6 PROCESSING DATA 2.3.6.1 Reaction Time 2.3.6.2 Self-paced Reading 2.3.6.3 Eye-Tracking 2.3.6.4 Neurolinguistic Data 2.4 REPLICATION 2.5 META-ANALYSES 2.6 ISSUES IN DATA ANALYSIS 2.7 WHAT IS ACQUISITION? 2.8 CONCLUSION Part Two: Historical Underpinnings of SLA Research Chapter Three: The Role of the Native Language - A Historical Overview 3.1 INTRODUCTION 3.2 BEHAVIORISM 3.2.1 Linguistic Background 3.2.2 Psychological Background 3.3 CONTRASTIVE ANALYSIS HYPOTHESIS 3.4 ERROR ANALYSIS 3.5 CONCLUSION Chapter Four: The Transition Period 4.1 INTRODUCTION 4.2 FIRST LANGUAGE ACQUISITION 4.2.1 Words 4.2.2 Sounds and Pronunciation 4.2.3 Syntax 4.2.4 Morphology 4.3 CHILD L2 ACQUISITION 4.4 CHILD L2 MORPHEME ORDER STUDIES 4.5 ADULT L2 MORPHEME ORDER STUDIES 4.6 THE MONITOR MODEL 4.6.1 The Acquisition-Learning Hypothesis 4.6.2 The Natural Order Hypothesis 4.6.3 The Monitor Hypothesis 4.6.4 The Input Hypothesis 4.6.5 The Affective Filter Hypothesis 4.6.6 Limitations 4.7 CONCLUSION Chapter Five: Alternative Approaches to the Role of Previously Known Languages 5.1 REVISED PERSPECTIVES ON THE ROLE OF THE NATIVE LANGUAGE 5.1.1 Avoidance 5.1.2 Differential Learning Rates 5.1.3 Different Paths 5.1.4 Overproduction 5.1.5 Predictability/Selectivity 5.1.6 L1 Influences in L2 Processing 5.1.7 Morpheme Order 5.2 CONCLUSION Part Three: A Focus on Form - Language Universals Chapter Six: Formal Approaches to SLA 6.1 INTRODUCTION 6.2 UNIVERSAL GRAMMAR 6.2.1 Initial State 6.2.1.1 Fundamental Difference Hypothesis 6.2.1.2 Access to UG Hypothesis 6.2.2 UG Principles 6.2.3 UG Parameters 6.2.4 Minimalist Program 6.2.5 Falsification 6.3 TRANSFER: THE GENERATIVE/UG PERSPECTIVE 6.3.1 Levels of Representation 6.3.2 Clustering 6.3.3 Learnability 6.4 THE FUNDAMENTAL DIFFERENCE HYPOTHESIS REVISED 6.5 SEMANTICS AND THE SYNTAX-SEMANTICS INTERFACE HYPOTHESIS 6.5.1 Semantics 6.5.2 Syntax and Semantics: The Interface Hypothesis 6.6 PHONOLOGY 6.6.1 Markedness Differential Hypothesis 6.6.2 Similarity/Dissimilarity: Speech Learning Model 6.6.3 Optimality Theory 6.6.4 Ontogeny Phylogeny Model 6.7 CONCLUSION Chapter Seven: Typological Approaches 7.1 TYPOLOGICAL UNIVERSALS 7.1.1 Test Case I: The Accessibility Hierarchy 7.1.2 Test Case II: The Acquisition of Questions 7.1.3 Test Case III: Voiced/Voiceless Consonants 7.2 FALSIFIABILITY 7.3 TYPOLOGICAL UNIVERSALS: CONCLUSION 7.4 TYPOLOGICAL PRIMACY MODEL 7.5 THE ROLE OF THE L1: THREE APPROACHES 7.6 CONCLUSION: GENERAL COMMENTS ABOUT UNIVERSALS Part Four: A Focus on Meaning Chapter Eight: Meaning-based Approaches 8.1 INTRODUCTION 8.2 FUNCTIONAL APPROACHES 8.2.1 The Relationship between Form and Function: Form-to-Function 8.2.2 Concept-oriented Approach 8.3 TENSE AND ASPECT: THE ASPECT HYPOTHESIS 8.4 THE DISCOURSE HYPOTHESIS 8.5 CONCLUSION Chapter Nine: The Lexicon 9.1 THE SIGNIFICANCE OF THE LEXICON 9.2 LEXICAL KNOWLEDGE: WHAT DOES IT MEAN TO KNOW A WORD? 9.2.1 Production and Reception 9.2.2 Knowledge and Control 9.2.3 Breadth and Depth 9.2.4 Subcategorization 9.2.5 Word Associations and Networks 9.2.6 Word Formation 9.2.7 Formulaic Language, Collocations, and Chunking 9.2.7.1 Use of Multiword Units 9.2.7.2 Learning of Multiword Units 9.2.7.3 Processing of Multiword Units 9.3 INFLUENCES ON L2 VOCABULARY AND DEVELOPMENT 9.3.1 The Role of the L1 9.3.2 Incidental Vocabulary Learning 9.3.2.1 Input Type 9.3.2.2 What Helps Learning? 9.3.3 Depth of Processing 9.3.4 Incremental Vocabulary Learning 9.4 USING LEXICAL SKILLS 9.4.1 Production 9.4.2 Perception 9.5 CONCLUSION Part Five: Cognitive and Processing Approaches to SLA Chapter Ten: Psycholinguistic Approaches to Learning 10.1 INTRODUCTION 10.2 MODELS OF LANGUAGE PRODUCTION 10.3 PROCESSABILITY THEORY 10.4 PROCESSING OF INPUT 10.4.1 Input Processing 10.4.2 Processing Determinism 10.4.3 Autonomous Induction Theory 10.4.4 Shallow Structure Hypothesis 10.5 EMERGENTIST MODELS 10.5.1 Competition Model 10.5.2 Frequency-based Accounts 10.6 COMPLEX DYNAMIC SYSTEMS 10.7 SKILL ACQUISITION THEORY 10.8 CONCLUSION Chapter Eleven: Psycholinguistic Constructs and Knowledge Types 11.1 INTRODUCTION 11.2 INFORMATION PROCESSING 11.2.1 Automaticity 11.2.2 Restructuring 11.2.3 U-shaped Learning 11.2.4 Attention 11.2.5 Working Memory 11.2.6. Salience 11.2.7 Priming 11.3 KNOWLEDGE TYPES 11.3.1 Acquisition/Learning 11.3.2 Declarative/Procedural 11.3.3 Implicit/Explicit 11.3.4 Representation/Control 11.4 INTERFACE OF KNOWLEDGE TYPES 11.4.1 No Interface 11.4.2 Weak Interface 11.4.3 Strong Interface 11.5 CONCLUSION Part Six: The Social Environment of Learning Chapter Twelve: Interlanguage in Context 12.1 INTRODUCTION 12.2 SOCIOCULTURAL APPROACHES 12.2.1 Mediation 12.2.2 Internalization 12.2.3 Zone of Proximal Development 12.2.4 Private Speech 12.2.5 Learning in a Sociocultural Framework 12.2.6 Gesture and SLA 12.3 SOCIOLINGUISTIC VARIATION 12.4 SYSTEMATIC VARIATION 12.4.1 Linguistic Context 12.4.2 Social Context Relating to the Native Language 12.4.3 Social Context Relating to Interlocutor, Task Type, and Conversational Topic 12.4.4 Sociolinguistic Norms 12.5 CONVERSATION ANALYSIS 12.6 COMMUNICATION STRATEGIES 12.7 L2 PRAGMATICS 12.8 CONCLUSION: SLA AND OTHER DISCIPLINES Chapter Thirteen: Input, Interaction, and Output 13.1 INTRODUCTION 13.2 INPUT 13.3 COMPREHENSION 13.4 INTERACTION 13.5 OUTPUT 13.5.1 Hypothesis Testing 13.5.2 Automaticity 13.5.3 Meaning-based to Grammar-Based Processing 13.6. Feedback 13.6.1 Negotiation 13.6.2 Corrective Feedback 13.6.2.1 Recasts 13.6.2.2 Elicitation 13.6.2.3 Metalinguistic Feedback 13.7 THE ROLE OF INPUT AND INTERACTION IN LANGUAGE LEARNING 13.7.1 The Functions of Input and Interaction 13.7.2 Effectiveness of Feedback 13.7.2.1 Attention 13.7.2.2 Contrast Theory 13.7.2.3 Metalinguistic Awareness 13.7.3 Who Benefits From Interaction: When and Why? 13.8 LIMITATIONS OF INPUT 13.9 CONCLUSION Chapter Fourteen: Contexts of Language Learning - Classrooms, Study Abroad, and Technology 14.1 INTRODUCTION 14.2 CLASSROOM-BASED INSTRUCTION 14.2.1 Classroom Language 14.2.2 Teachability/Learnability 14.2.3 Focus on Form and Task-based Language Teaching 14.2.3.1 Timing 14.2.3.2 Forms to Focus On 14.2.3.3 Task Design 14.2.3.4 Input Manipulation and Input Enhancement 14.3 COMPLEXITY, ACCURACY, FLUENCY, AND PLANNING 14.4 PROCESSING INSTRUCTION 14.5 UNIQUENESS OF INSTRUCTION 14.6 EFFECTIVENESS OF INSTRUCTION 14.7 SLA AND CLASSROOM PRACTICES 14.8 ADDITIONAL CONTEXTS 14.8.1 Study Abroad 14.8.2 Technology-enhanced Language Learning 14.9 CONCLUSION Part Seven: The Individual Language Learner Chapter Fifteen: Learner-internal Influences 15.1 INTRODUCTION 15.2 THE INFLUENCE OF PSYCHOLOGY IN SLA 15.3 METHODOLOGICAL CONSIDERATIONS 15.4 AGE DIFFERENCES 15.5 APTITUDE 15.6 MOTIVATION 15.6.1 Motivation as a Function of Time and Success 15.6.2 Changes over Time 15.6.3 The L2 Motivational Self System 15.6.4 Influence of Success on Motivation and Demotivation 15.7 AFFECT 15.7.1 Anxiety 15.7.2 Other Emotional Variables 15.8 PERSONALITY 15.8.1 Extroversion and Introversion 15.8.2 Grit 15.9 LEARNING STRATEGIES 15.10 CONCLUSION Chapter Sixteen: Related Disciplines - A Focus on the Multilingual and Multimodal Learner 16.1 INTRODUCTION 16.2 BILINGUAL ACQUISITION 16.3 THIRD LANGUAGE ACQUISITION/MULTILINGUALISM 16.4 HERITAGE LANGUAGE ACQUISITION 16.5 SLA BY THE DEAF/HARD OF HEARING 16.6 CONCLUSION Part Eight: Conclusion Chapter Seventeen: An Integrated View of Second Language Acquisition 17.1 AN INTEGRATION OF SUB-AREAS 17.1.1 Apperceived Input 17.1.2 Comprehended Input 17.1.3 Intake 17.1.4 Integration 17.1.5 Output 17.2 CONCLUSION

A survey of wormhole routing techniques in direct networks

Abstract: Several research contributions and commercial ventures related to wormhole routing, a switching technique used in direct networks, are discussed. The properties of direct networks are reviewed, and the operation and characteristics of wormhole routing are discussed in detail. By its nature, wormhole routing is particularly susceptible to deadlock situations, in which two or more packets may block one another indefinitely. Several approaches to deadlock-free. routing, along with a technique that allows multiple virtual channels to share the same physical channel, are described. In addition, several open issues related to wormhole routing are discussed. >

The Supreme Court and the Attitudinal Model Revisited

Abstract: This book, authored by two leading scholars of the Supreme Court and its policy making, systematically presents and validates the use of the attitudinal model to explain and predict Supreme Court decision making. In the process, it critiques the two major alternative models of Supreme Court decision making and their major variants: the legal and rational choice. Using the US Supreme Court Data Base, the justices' private papers, and other sources of information, the book analyzes the appointment process, certiorari, the decision on the merits, opinion assignments, and the formation of opinion coalitions. The book will be the definitive presentation of the attitudinal model as well as an authoritative critique of the legal and rational choice models. The book thoroughly reflects research done since the 1993 publication of its predecessor, as well as decisions and developments in the Supreme Court, including the momentous decision of Bush v. Gore.

Recommendations for standards in transthoracic two-dimensional echocardiography in the dog and cat

Abstract: Recommendations are presented for standardized imaging planes and display conventions for two-dimensional echocardiography in the dog and cat. Three transducer locations ("windows") provide access to consistent imaging planes: the right parasternal location, the left caudal (apical) parasternal location, and the left cranial parasternal location. Recommendations for image display orientations are very similar to those for comparable human cardiac images, with the heart base or cranial aspect of the heart displayed to the examiner's right on the video display. From the right parasternal location, standard views include a long-axis four-chamber view and a long-axis left ventricular outflow view, and short-axis views at the levels of the left ventricular apex, papillary muscles, chordae tendineae, mitral valve, aortic valve, and pulmonary arteries. From the left caudal (apical) location, standard views include long-axis two-chamber and four-chamber views. From the left cranial parasternal location, standard views include a long-axis view of the left ventricular outflow tract and ascending aorta (with variations to image the right atrium and tricuspid valve, and the pulmonary valve and pulmonary artery), and a short-axis view of the aortic root encircled by the right heart. These images are presented by means of idealized line drawings. Adoption of these standards should facilitate consistent performance, recording, teaching, and communicating results of studies obtained by two-dimensional echocardiography.

Beauty and the Labor Market

Abstract: We develop a theory of sorting across occupations based on looks and derive its implications for testing for the source of earnings differentials related to looks. These differentials are examined using the 1977 Quality of Employment, the 1971 Quality of American Life, and the 1981 Canadian Quality of Life surveys, all of which contain interviewers' ratings of the respondents' physical appearance. Holding constant demographic and labor-market characteristics, plain people earn less than people of average looks, who earn less than the good-looking. The penalty for plainness is 5 to 10 percent, slightly larger than the premium for beauty. The effects are slightly larger for men than women; but unattractive women are less likely than others to participate in the labor force and are more likely to be married to men with unexpectedly low human capital. Better-looking people sort into occupations where beauty is likely to be more productive; but the impact of individuals' looks on their earnings is mostly independent of occupation.

Literature review of the usefulness of nerve conduction studies and electromyography for the evaluation of patients with carpal tunnel syndrome. AAEM Quality Assurance Committee

Abstract: The sensitivity and specificity of nerve conduction studies (NCS's) and electromyography (EMG) for the diagnosis of carpal tunnel syndrome (CTS) were evaluated by a critical review of the literature. With a search of the medical literature in English through May 1991, 165 articles were identified and reviewed on the basis of six criteria of scientific methodology. The findings of 11 articles that met all six criteria and the results of 48 additional studies that met four or five criteria are presented. We concluded that median sensory and motor NCS's are valid and reproducible clinical laboratory studies that confirm a clinical diagnosis of CTS with a high degree of sensitivity and specificity. Clinical practice recommendations are made based on a comparison of the sensitivities of the several different median nerve conduction study (NCS) techniques.

Elevated atmospheric CO2 and feedback between carbon and nitrogen cycles

Abstract: We tested a conceptual model describing the influence of elevated atmospheric CO2 on plant production, soil microorganisms, and the cycling of C and N in the plant-soil system. Our model is based on the observation that in nutrient-poor soils, plants (C3) grown in an elevated CO2 atmosphere often increase production and allocation to belowground structures. We predicted that greater belowground C inputs at elevated CO2 should elicit an increase in soil microbial biomass and increased rates of organic matter turnover and nitrogen availability. We measured photosynthesis, biomass production, and C allocation of Populus grandidentata Michx. grown in nutrient-poor soil for one field season at ambient and twice-ambient (i.e., elevated) atmospheric CO2 concentrations. Plants were grown in a sandy subsurface soil i) at ambient CO2 with no open top chamber, ii) at ambient CO2 in an open top chamber, and iii) at twice-ambient CO2 in an open top chamber. Plants were fertilized with 4.5 g N m−2 over a 47 d period midway through the growing season. Following 152 d of growth, we quantified microbial biomass and the availabilities of C and N in rhizosphere and bulk soil. We tested for a significant CO2 effect on plant growth and soil C and N dynamics by comparing the means of the chambered ambient and chambered elevated CO2 treatments.

Determinants of judgment performance in accounting settings: Ability, knowledge, motivation, and environment☆

Abstract: The goal of this paper is to trace the development of our conceptions of the roles of ability, knowledge, motivation, and environment as determinants of decision performance in accounting settings, and provide a synthesis of the basic constructs, conceptual relations, and methodological guidelines that can be inferred from this diverse literature. We first outline the key characteristics of accounting settings and research principles appropriate for examining the characteristics. The primary emphasis is on identifying interactions between determinants of performance, specifying underlying cognitive processes, and abstraction based on theory and task analysis. We then demonstrate how selected studies which follow these basic principles have greatly enhanced our understanding of accounting-related decisions. Finally, suggestions for future research are presented.

Product and Promotion Adaptation in Export Ventures: An Empirical Investigation

Abstract: While the desirability of marketing adaptation vs. standardization has long been debated within both academic and business circles, empirical studies investigating the conditions under which each strategy becomes appropriate have been rare. This article provides a formal investigation of the correlates of product and promotion adaptation in export ventures. A conceptual framework of product and promotion adaptation in export ventures is proposed to integrate the diverse perspectives on the issue of standardization versus adaptation. The conceptual framework is further specified in a testable form and tested via data collected by a series of in-depth personal interviews with export marketing managers. The results support the contingency perspective recently emerging in the standardization literature, and suggest that the degree of the various aspects of product adaptation (i.e., upon and after entry) and promotion adaptation (i.e., positioning, packaging/labeling, and promotional approach) are significantly influenced by company, product/industry, and export market characteristics. However, the profile of the correlates varies across the various aspects of product and promotion adaptation.

Emotions, Arousal, and Stereotypic Judgments: A Heuristic Model of Affect and Stereotyping

Abstract: Publisher Summary The heuristic view of stereotyping emphasizes that people use their oversimplified beliefs about social groups as a basis for responding to the members of those groups whenever they lack the desire or the ability to engage in more extensive thought about the individuals. The lack of such desire and/or ability may be common enough under most everyday life circumstances, and it appears that conditions of heightened emotional experience—in particular, anger, anxiety, and happiness—only serve to further reduce the motivation and/or processing capacity. This chapter presents the task of specifying the motivational and cognitive consequences of affective states for information processing. Drawing on the neurological, physiological, and cognitive literatures, Galen V. Bodenhausen develops the hypothesis that some affective states, but not others, produce simplified information processing. He draws out and tests the processing implications of a range of affective states for the use of stereotypic, rather than individuating, information in social perception tasks. The theoretical integration of affective and cognitive processes promises to yield important advances in social psychology generally, but no topic of study seems likely to profit from this reunification more than the study of stereotyping and discrimination.

Configurations of Organizational Effectiveness and Efficiency

Abstract: This study examined the relationship between various characteristics of organizations—including resource inputs, context, rules and regulations, goals, climate, and informal systems—and the effecti...

The dynamics of fine root length, biomass, and nitrogen content in two northern hardwood ecosystems

Abstract: The dynamics of fine (<2.0 mm) roots were measured in two sugar maple (Acersaccharum Marsh.) dominated ecosystems (northern and southern sites) during 1989 and 1990 using a combination of minirhizo...

Assessing diversity climate: A field study of reactions to employer efforts to promote diversity

Abstract: Based on intergroup theory, this study examined relationships among group characteristics (racioethnicity, gender, and level), contextual organizational unit characteristics (gender and racioethnic heterogeneity, resource support for women and racioethnic minorities) and perceptions of diversity climate by faculty at a large university. Compared to white men, white women and racioethnic minorities placed greater value on employer efforts to promote diversity, and held more favorable attitudes about the qualifications of women and racioethnic minorities. The study found that group rather than contextual organizational unit characteristics were more strongly related to diversity climate. However, the organizational unit characteristic, gender heterogeneity, was significantly related to valuing diversity. The greater the ratio of women in a unit, regardless of the respondents' gender, racioethnicity or level, the more favorable diversity activities were viewed. In addition, units whose allocation of resources to racioethnic minorities were perceived as insufficient by respondents were more likely to have members who valued diversity and held favorable perceptions toward the qualifications of racioethnic minorities. Implications for organizations and future research are offered.

Some pinching and classification theorems for minimal submanifolds

Abstract: By BANG-YEN CHEN 1. Introduction. Let x: M -* E" be an immersion from an n-dimensional (n > 0) mani- fold into a Euclidean re, space. Denote by A the Laplacian operator of M with respect to the induced metric. Then we have the following formula of Beltrami: (1.1)

Fibre-matrix adhesion and its relationship to composite mechanical properties

Abstract: Two major areas of enquiry exist in the field of fibre-matrix adhesion in composite materials. One is the fundamental role that fibre-matrix adhesion plays on composite mechanical properties. The other is what is the “best” method used to measure fibre-matrix adhesion in composite materials. Results of an attempt to provide an experimental foundation for both areas are reported here. A well-characterized experimental system consisting of an epoxy matrix and carbon fibres was selected in which only the fibre surface chemistry was altered to produce three different degrees of adhesion. Embedded single-fibre fragmentation tests were conducted to quantify the level of fibre-matrix adhesion. Observation of the events occurring at the fibre breaks led to the documentation of three distinct failure modes coincident with the three levels of adhesion. The lowest level produced a frictional debonding, the intermediate level produced interfacial crack growth and the highest level produced radial matrix fracture. High fibre volume fraction composites made from the same material were tested for on- and off-axis, as well as fracture, properties. Results indicate that composite results can be explained if both differences in adhesion and failure mode are considered. It will be further demonstrated that fibre-matrix adhesion is an “optimum” condition which has to be selected for the stress state that the interface will experience. The embedded single-fibre fragmentation test is both a valuable measurement tool for quantifying fibre-matrix adhesion as well as the one method which provides fundamental information about the failure mode necessary for understanding the role of adhesion on composite mechanical properties.

Spatial expression and autoregulation of hetR, a gene involved in the control of heterocyst development in Anabaena

Abstract: The spatially patterned differentiation of heterocysts in the filamentous cyanobacterium Anabaena requires a functional hetR gene. Transcriptional fusions to luxAB show that hetR is transcribed at a low level throughout the filament when Anabaena is grown with combined nitrogen, and that induction of the gene begins within 2 h following nitrogen deprivation. By 3.5 h, induction is localized to spaced foci. By 6 h, there is an overall induction of at least threefold in whole cultures, reflecting at least a 20-fold increase within spatially separated cells. The induction requires the presence of a functional hetR gene, indicating that hetR is autoregulatory. Full induction of a heterocyst structural gene, hepA, also requires a functional hetR locus.

The effects of nitrate, nitrite and N-nitroso compounds on human health: a review.

Abstract: The effects of nitrate, nitrite, and N-nitroso compounds on human health are reviewed. Special emphasis has been placed on the role of these compounds on infant methemoglobinemia and gastric cancer. The discussion on methemoglobinemia includes the source of nitrate or nitrite, diagnosis, treatment, prevention and the contributions of age, gastric pH, gastrointestinal illness, and ingestion of vitamin C to this illness. The maternal transfer of these compounds and the potential effect on fetal death and malformation are also described. The etiology and development of gastric cancer is reviewed as well as the roles of nitrate, nitrite, and N-nitroso compounds in this disease. Endogenous nitrosation and the experimental and epidemiologic evidence linking these compounds to gastric cancer is examined. Other sections include adult methemoglobinemia and acute toxicity, hypo- and hypertension, Balkan nephropathy, slowing of motor reflexes in children, nitrate esters dependence. Sources of nitrate, nitrite, and N-nitroso compounds are detailed. Future areas of research are given.

The demography of fine roots in response to patches of water and nitrogen

Abstract: SUMMARY Fine root demography was quantified in response to patches of increased water and nitrogen availability in a natural, second-growth, mixed hardwood forest in northern Michigan, USA. As expected, the addition of water and water plus nitrogen resulted in a significant overall increase in the production of new fine roots. New root production was much greater in response to water plus nitrogen when compared with water alone, and the duration of new root production was related to the length of resource addition in the water plus nitrogen treatments; the average difference in new root length between the 20 vs. 40 d additions of water plus nitrogen amounted to almost 600%. Roots produced in response to the additions of water and water plus nitrogen lived longer than roots in the control treatments. Thus, additions of water and water plus nitrogen influenced both the proliferation of new roots and their longevity, with both proliferation and longevity related to the type and duration of resource supply. Results suggest that root longevity and mortality may be plastic in response to changes in soil resource availability, as is well known for root proliferation.

Disordered eating attitudes and behaviors, psychological adjustment, and ethnic identity: A comparison of black and white female college students

Abstract: The low prevalence of restrictive eating disorders among black women has been attributed primarily to cultural differences in the definition of beauty. Utilizing self-report measures, this study examined differences in the nature of disordered eating behaviors for black and for white female college students. Analyses of covariance and correlational tests revealed that white females demonstrated significantly greater disordered eating attitudes and behaviors than black females. Additionally, the data indicated that although disordered eating behaviors and attitudes are related to actual weight problems for black females, this is not the case for white females. Furthermore, this study is the first to provide evidence that restrictive eating disorders among black women are related to the degree to which they assimilate to mainstream culture. Finally disordered eating behaviors and attitudes were related to depression, anxiety, and low self-esteem in both groups. © 1993 by John Wiley & Sons, Inc.

High school geometry students' justification for their views of empirical evidence and mathematical proof

Abstract: Concerns about the use of computer-aided empirical verification in geometry classes lead to an investigation of students' understandings of the similarities and differences between the measurement of examples and deductive proof. The study reports in-depth interviews with seventeen high school students from geometry classes which employed empirical evidence. The analysis focuses on students' reasons for viewing empirical evidence as proof and mathematical proof simply as evidence.

Attitude-Behavior Relations: A Meta-Analysis of Attitudinal Relevance and Topic

Abstract: The difficulty of finding a relationship between attitudes and behavior is one of the greatest controversies in recent social science research. The purpose of this study was to determine whether attitudinal relevance substantially affects the magnitude of the correlation between attitudes and behavior and whether the effects are content-free. Using meta- analysis the authors integrated findings from 138 attitude-behavior correlations with a total sample size of 90908. The behaviors they studied ranged over 19 different categories and a variety of miscellaneous topics. The results showed a strong overall attitude- behavior relationship (r = .79) when methodological artifacts were eliminated. As predicted the higher the attitudinal relevance the stronger the relationship between attitudes and behavior. This effect held true across diverse content domains. Implications for communication theory and practice are discussed. (authors)

Changing middle school students' conceptions of matter and molecules

Abstract: The purpose of this study was two-fold: (1) to understand the conceptual frameworks that sixth-grade students use to explain the nature of matter and molecules, and (2) to assess the effectiveness of two alternative curriculum units in promoting students' scientific understanding. The study involved 15 sixth-grade science classes taught by 12 teachers in each of two successive years. Data were collected through paper-and-pencil tests and clinical interviews. The results revealed that students' entering conceptions differed from scientific conceptions in various ways. These differences included molecular conceptions concerning the nature, arrangement, and motion of molecules as well as macroscopic conceptions concerning the nature of matter and its physical changes. The results also showed that the students taught by the revised unit in Year 2 performed significantly better than the students taught by the original commercial curriculum unit in Year 1 for 9 of the 10 conceptual categories. Implications for science teaching and curriculum development are discussed.

The influence of cancer patients' symptoms and functional states on patients' depression and family caregivers' reaction and depression.

Abstract: In this article the paths among cancer patients' physical and mental health and the reactions and mental health of their family caregivers were examined. Data for these analyses came from a cross-sectional sample of cancer patients who were recruited through ambulatory outpatient chemotherapy units, and their family caregivers. Patients' depression was explained largely by their symptomatology and, to a lesser extent, by loss of mobility. Patients' physical limitations impacted caregivers' daily schedules but not their physical health. Patients' levels of depression were related to those of their caregivers. However, caregivers' optimism proved to be a significant predictor of their mental health and reactions to caregiving.