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Showing papers by "University of Massachusetts Amherst published in 1991"


Journal ArticleDOI
TL;DR: Ajzen, 1985, 1987, this article reviewed the theory of planned behavior and some unresolved issues and concluded that the theory is well supported by empirical evidence and that intention to perform behaviors of different kinds can be predicted with high accuracy from attitudes toward the behavior, subjective norms, and perceived behavioral control; and these intentions, together with perceptions of behavioral control, account for considerable variance in actual behavior.

65,095 citations


Book
25 Jan 1991
TL;DR: This book discusses Detection and Discrimination of Compound Stimuli: Tools for Multidimensional Detection Theory and Multi-Interval Discrimination Designs and Adaptive Methods for Estimating Empirical Thresholds.
Abstract: Both a user's guide and a theoretical exposition of modern detection theory, incorporating recent developments and covering the two major alternative versions of detection theory.

6,408 citations


Journal ArticleDOI
TL;DR: Extrapolation of the data from this population-based study suggests that there are approximately 170,000 new cases of clinically recognized venous thromboembolism in patients treated in short-stay hospitals in the United States each year, and 99,000 hospitalizations for recurrent disease.
Abstract: A community-wide study was conducted in 16 short-stay hospitals in metropolitan Worcester, Mass, to examine the incidence and case-fatality rates of deep vein thrombosis and pulmonary embolism in patients hospitalized between July 1, 1985, and December 31, 1986. The average annual incidence of deep vein thrombosis alone was 48 per 100,000, while the incidence of pulmonary embolism with or without deep vein thrombosis was 23 per 100,000. The incidence rates of deep vein thrombosis and pulmonary embolism increased exponentially with age. The in-hospital case-fatality rate of venous thromboembolism was 12%. Among patients discharged from the hospital, the long-term case-fatality rates were 19%, 25%, and 30% at 1, 2, and 3 years after hospital discharge. Extrapolation of the data from this population-based study suggests that there are approximately 170,000 new cases of clinically recognized venous thromboembolism in patients treated in short-stay hospitals in the United States each year, and 99,000 hospitalizations for recurrent disease. Because of the silent nature of this disease and the low rate of autopsy in the United States, the total incidence, prevalence, and mortality rates of venous thromboembolism remain elusive.

2,198 citations


Journal ArticleDOI
TL;DR: In this paper, a weak solution of the nonlinear PDE is proposed, which asserts each level set evolves in time according to its mean curvature, existing for all time.
Abstract: We construct a unique weak solution of the nonlinear PDE which asserts each level set evolves in time according to its mean curvature. This weak solution allows us then to define for any compact set ⌈0 a unique generalized motion by mean curvature, existing for all time. We investigate the various geometric properties and pathologies of this evolution.

1,415 citations


Journal ArticleDOI
TL;DR: In this article, the prediction of dishonest actions was studied in the context of the theory of planned behavior, where participants completed a questionnaire that assessed attitudes, subjective norms, perceptions of behavioral control, intentions, and perceptions of moral obligations, as well as self-reports of behavior with respect to cheating on a test, shoplifting, and lying to get out of assignments.

1,205 citations


Journal ArticleDOI
TL;DR: The theory of planned behavior (Ajzen 1985, 1987) is offered as a comprehensive framework for understanding of leisure participation by as mentioned in this paper, who found that participants' participation in leisure activities was influenced by affective and instrumental beliefs, as well as by normative beliefs about the expectations of important others and by control beliefs about required resources and other f...
Abstract: The theory of planned behavior (Ajzen 1985, 1987) is offered as a comprehensive framework for understanding of leisure participation. Salient behavioral, normative, and control beliefs, theoretically the basic determinants of behavior, were assessed with respect to five leisure activities: spending time at the beach, jogging or running, mountain climbing, boating, and biking. College students completed a questionnaire containing measures of these beliefs and of global expressions of attitude, subjective norm, and perceived behavioral control. One year later the participants reported how often they had performed each behavior in the preceding 12 months. Behavioral beliefs were found to partition into beliefs about affective reactions and beliefs about costs and benefits. Participation in leisure activities was influenced by these affective and instrumental beliefs, as well as by normative beliefs about the expectations of important others and by control beliefs about required resources and other f...

818 citations


Journal ArticleDOI
01 Jul 1991
TL;DR: Network representations show promise as mechanisms for inferring probable relationships between documents and queries and have been used in information retrieval since at least the early 1960s.
Abstract: Network representations have been used in information retrieval since at least the early 1960’s. Networks have been used to support diverse retrieval functions, including browsing [38], document clustering [7], spreading activation search [4], support for multiple search strategies [11], and representation of user knowledge [27] or document content [40]. Recent work suggests that significant improvements in retrieval performance will require techniques that, in some sense “understand” the content of documents and queries [9, 43] and can be used to infer probable relationships between documents and queries. In this view, information retrieval is an inference or evidential reasoning process in which we estimate the probability that a user’s information need, expressed as one or more queries, is met given a document as “evidence.” Network representations show promise as mechanisms for inferring these kinds of relationships [4, 12].

653 citations


Journal ArticleDOI
TL;DR: The fundamentals of microbial kinetics and continuous culture models are presented and the effect of temperature and inhibitors on the intrinsic kinetic rates is discussed, and Stoichiometric and bioenergetic considerations are reviewed.
Abstract: The fundamentals of microbial kinetics and continuous culture models are presented. The kinetics of the anaerobic treatment processes are reviewed recognizing that anaerobic degradation of complex, polymeric organic materials is a combination of series and parallel reactions. Such reactions include hydrolysis, fermentation, anaerobic oxidation of fatty acids, and methanogenesis. The intrinsic rates of each step are reviewed and literature data summarized. Whenever possible, available kinetic information is summarized on the basis of substrate composition (such as carbohydrates, proteins, and lipids). The effect of temperature and inhibitors on the intrinsic kinetic rates is discussed. Stoichiometric and bioenergetic considerations are reviewed. Mass transfer limitations (both external and internal) associated with biofilms and microbial agglomerates, in general, and their effect on the intrinsic kinetic rates are presented. Areas requiring further research are identified.

638 citations


Journal ArticleDOI
TL;DR: INTRODUCTION 560 SPLICING PATHWAy 560 The PARADIGM: AUTOCATALYTIC SPLICing of Group II InTRONS 560 SPLICEOSOME ASSEMBLY PATHWAY 561 The Vi snRNP-Binding Reaction 563 Entry of U4/U5/U6 snRNPs 565 Destabilization of V4 snRNA 565
Abstract: INTRODUCTION 560 SPLICING PATHWAy 560 THE PARADIGM: AUTOCATALYTIC SPLICING OF GROUP II INTRONS 560 SPLICEOSOME ASSEMBLY PATHWAY 561 The Vi snRNP-Binding Reaction ...... . ... . 563 The U2 snRNP-Binding Reaction 563 Entry of U4/U5/U6 snRNPs 565 Destabilization of V4 snRNA 565 THE SPLICING PROCESS 566 First Step and Catalysis 566 Second Step 566 mRNA Release, Spliceosome Disassembly, and Intron Degradation 567 U snRNPs 568 Sm-Binding Site , . . . . . . . . . . . . 568 Cap Structure , . . . . . . . . . . . . 569 snRN P Assembly 569 Structure-Function Analysis of Spliceosomal sRNAs 569 Higher Order snRNP-snRNP Interactions 574 NON-snRNP SPLICING FACTORS 574 Mammalian Factors , . . . . . . . . . . . . 574 Yeast Factors .. .... .. . .. .. 578 Protein Motifs in Splicing Factors 579 SELECTION OF SPLICE SITES 580 Splice Site Selection: A Hierarchy of Competition 581 Other Models 581

624 citations


Journal ArticleDOI
TL;DR: A synthetic review of studies confirms a primary correlation between REE and FFM in adults over a broad range of body weights and suggests that FFM predicts total daily energy expenditure (TDEE) equally well.

541 citations


Journal ArticleDOI
TL;DR: To determine whether the increasing use of percutaneous fine-needle biopsy of abdominal lesions is associated with an increase in serious complications, the author updated a literature search and evaluated a questionnaire.
Abstract: To determine whether the increasing use of percutaneous fine-needle biopsy of abdominal lesions is associated with an increase in serious complications, the author updated a literature search and evaluated a questionnaire (distributed among selected hospitals in the United States in 1986 and 1987) that followed up a questionnaire distributed in 1983. The updated literature review revealed a total of 24 deaths and 20 needle tract seedings. The updated questionnaire revealed five deaths after 16,381 biopsies (0.031%), whereas the previous questionnaire had shown four deaths after 63,108 biopsies (0.006%). Two similar European questionnaires revealed mortality rates of 0.008% and 0.018%, respectively. Of the total of 33 deaths, 21 involved biopsies of liver lesions; six involved pancreatic biopsies. Seventeen of the 21 deaths after liver biopsies were secondary to hemorrhage; five of the six deaths after pancreatic biopsies were due to pancreatitis. Of the 23 instances of needle tract seeding, 10 occurred af...

Journal ArticleDOI
TL;DR: A novel modular connectionist architecture is presented in which the networks composing the architecture compete to learn the training patterns, and an outcome of the competition is that different networks learn different training patterns and, thus, learn to compute different functions.

Journal ArticleDOI
TL;DR: It is concluded that with but few exceptions, the evidence for the significance of mass transfer effects in the different reactor configurations is circumstantial and, in some cases, contradictory.

Journal ArticleDOI
TL;DR: Recommendations are made for the use of methods for assessing model adequacy and for future editorial policy in regard to the review of articles using logistic regression in the American Journal of Public Health.
Abstract: BACKGROUND. The logistic regression model is being used with increasing frequency in all areas of public health research. In the calendar year 1989, over 30% of the articles published in the American Journal of Public Health employed some form of logistic regression modeling. In spite of this increase, there has been no commensurate increase in the use of commonly available methods for assessing model adequacy. METHODS. We review the current status of the use of logistic regression modeling in the American Journal of Public Health. We present a brief overview of currently available and easily used methods for assessing the adequacy of a fitted logistic regression model. RESULTS. An example is used to demonstrate the methods as well as a few of the adverse consequences of failing to assess the fit of the model. One important adverse consequence illustrated in the example is the inclusion of variables in the model as a result of the influence of one subject. CONCLUSIONS. Failure to address model adequacy ma...

Journal ArticleDOI
TL;DR: Using feminist deconstructive strategies, the authors exposes some of the rhetorical and cultural conditions that have sustained the organizational leadership literature as a seductive game and argues against the closure imposed by organizational research and theory on what can be said to be organizational knowledge.
Abstract: Using feminist deconstructive strategies, this paper exposes some of the rhetorical and cultural conditions that have sustained the organizational leadership literature as a seductive game. The juxtaposition of 'leadership' and 'seduction' functions as the focus of analysis for understanding the cultural limits of know ledge at times when innovations in theory and research are expected, but do not seem to be happening. Through various analytical approaches, the paper creates 'reading effects' that may be unsettling for the community of organizational scholars. This opens different spaces for reflecting upon and arguing against the closure imposed by organizational research and theory on what can be said to be organizational knowledge.

Journal ArticleDOI
TL;DR: It is concluded that future advances in ecological validity are likely to come from a greater reliance on assessments of the target behaviors in natural settings and combining several of the more promising tasks and analogue methods into a battery that is taken over longer time intervals than has been customary and averaged across repeated administrations.
Abstract: An important question in the attempt to generalize laboratory findings on attention deficit-hyperactivity disorder (ADHD) children to clinical issues concerning their assessment, diagnosis, outcome, and treatment response is the ecological validity of the commonly used tasks and analogue behavioral observation procedures. This paper examines the concept of ecological validity and issues inherent in its evaluation. The evidence from a variety of sources is then reviewed on the relationship between laboratory methods of assessing inattention, impulsivity, and overactivity and measures of these same constructs in natural settings. Additional findings pertaining to this issue from a recent study of 140 ADHD and normal children and 159 ADHD and normal adolescents using a multimethod battery of tests are also reported. In general, the ecological validity of most methods is of a low to moderate degree, with some traditional laboratory tasks proving unsatisfactory. A few tasks demonstrated acceptable degrees of ecological validity but even these require improvement. It is concluded that future advances in ecological validity are likely to come from: (a) a greater reliance on assessments of the target behaviors in natural settings and (b) combining several of the more promising tasks and analogue methods into a battery that is taken over longer time intervals than has been customary and averaged across repeated administrations.

Journal ArticleDOI
01 Nov 1991-Cell
TL;DR: It is proposed that the G:G base pair distorts the sugar-phosphate backbone of viral RNA and that this distortion is a critical determinant of recognition by Rev.

Journal ArticleDOI
TL;DR: Results suggest that the development and maintenance of ODD into adolescence in hyperactive children is strongly associated with aggression and negative parent-child interactions in childhood.
Abstract: The present study reports the results of a prospective, 8-year follow-up study of 100 hyperactive and 60 normal children followed from childhood into adolescence. Ratings of child behavior problems and family conflicts as well as direct observations of mother-child interactions were taken in childhood and again at adolescent follow-up. At outcome, hyperactives continued to have more conduct and learning problems and to be more hyperactive, inattentive, and impulsive than controls. Hyperactives were also rated by their mothers as having more numerous and intense family conflicts than the normal controls, although the adolescents in both groups did not differ in their own ratings of these conflicts. Observations of mother-adolescent interactions at outcome found the hyperactive dyads displaying more negative and controlling behaviors and less positive and facilitating behaviors towards each other than in the normal dyads. These interaction patterns were significantly related to similar patterns in mother-child interactions observed 8 years earlier. Mothers of hyperactives also reported more personal psychological distress than normal mothers at outcome. Further analyses of subgroups of hyperactives at outcome, formed on the presence or absence of ADHD and oppositional defiant disorder (ODD), indicated that the presence of ODD accounted for most of the differences between hyperactives and normals on the interaction measures, ratings of home conflicts, and ratings of maternal psychological distress. Results suggest that the development and maintenance of ODD into adolescence in hyperactive children is strongly associated with aggression and negative parent-child interactions in childhood.

Journal ArticleDOI
10 Oct 1991-Nature
TL;DR: TFIIB expressed in and purified from Escherichia coli (recombinant TFIIB) binds directly to the potent acidic activating region of the herpes simplex virus-1 VP16 protein.
Abstract: A CENTRAL issue in eukaryotic transcriptional regulation is the mechanism by which promoter-specific transcription factors (activators) stimulate transcription. Two lines of evidence indicate that the general transcription factor TFIIB is a pivotal component in the mechanism by which an acidic activator functions. First, during assembly of the preinitiation complex TFIIB binding is a rate-limiting step enhanced by an acidic activator1. Second, the TFIIB activity in a HeLa cell nuclear extract is specifically retained on a column containing an acidic activating region1. But because our previous study monitored only TFIIB activity, it remains possible that the interaction between TFIIB and the acidic activating region is mediated through additional proteins, for example, those designated as adaptors2, coactivators3 or mediators4,5. A complementary clone encoding TFIIB has recently been isolated and shown to encode a polypeptide of relative molecular mass 35,000 (ref. 6). Here we report that TFIIB expressed in and purified from Escherichia coli (recombinant TFIIB) binds directly to the potent acidic activating region of the herpes simplex virus-1 VP16 protein.

Journal ArticleDOI
TL;DR: Results indicate (a) T lymphocytes are activated and produce IL-2 and IFN gamma in vivo during DHF and DF, (b) CD4+ T lymphocyte are activated inDHF andDF, and the level of activation is higher in DHF than in DF, and (c) activation of CD8+T lymphocytes is evident in DH, but not in DF.
Abstract: It has been reported that the severe complication of dengue virus infection, dengue hemorrhagic fever (DHF) is much more commonly observed during secondary dengue virus infections than primary infections. In order to elucidate the role of T lymphocytes in the pathogenesis of DHF, we attempted to determine whether T lymphocytes are activated in vivo during dengue virus infections, by examining the levels of soluble IL-2 receptor (sIL-2R), soluble CD4 (sCD4), soluble CD8 (sCD8), interleukin-2 (IL-2) and interferon-gamma (IFN gamma) in the sera of 59 patients with DHF and 41 patients with dengue fever (DF). The levels of sIL-2R, sCD4, sCD8, IL-2, and IFN gamma were significantly higher in the acute sera of patients with DHF than in the sera of healthy children (P less than 0.001 for all markers). The acute sera of patients with DF contained higher levels of sIL-2R, sCD4, IL-2, and IFN gamma than the sera of healthy children (P less than 0.001 for sIL-2R, IL-2, and IFN gamma; P less than 0.05 for sCD4), but did not have elevated levels of sCD8. The levels of sIL-2R (P less than 0.05), sCD4 (P less than 0.001), and sCD8 (P less than 0.001) were higher in DHF than in DF on days 3-4 after the onset of fever. The levels of IL-2 and IFN gamma in patients with DHF were highest 1 d before defervescence. There were no significant differences in the levels of sIL-2R, sCD4, sCD8, IL-2, and IFN gamma among grades 1, 2, and 3 of DHF. These results indicate (a) T lymphocytes are activated and produce IL-2 and IFN gamma in vivo during DHF and DF, (b) CD4+ T lymphocytes are activated in DHF and DF, and the level of activation is higher in DHF than in DF, and (c) activation of CD8+ T lymphocytes is evident in DHF, but not in DF.

Journal ArticleDOI
TL;DR: In this paper, the effects of both short term and chronic treatment with 1,25- dihydroxyvitamin D3 were examined during osteoblast growth and differentiation in rat osteoblasts.
Abstract: Normal rat osteoblasts in culture undergo a developmental sequence consisting of a proliferation period in which high levels of the histone and collagen type I genes are expressed, followed by periods of matrix maturation [high levels of alkaline phosphatase (AP)] and mineralization that signal a high level of production of osteopontin (OP) and osteocalcin (OC). Since these parameters are regulated by vitamin D, the effects of both short term and chronic treatment with 1,25- dihydroxyvitamin D3 were examined during osteoblast growth and differentiation. In acute studies, during the proliferation period, histone mRNA (reflecting DNA synthesis) was inhibited (20–60%). Matrix Gla protein (MGP) and OP mRNA were significantly elevated during proliferation (30- and 15-fold), in contrast to OC which is not expressed and was not induced by hormone treatment. OP and MGP remained stimulated throughout the developmental sequence, but to a lesser degree (from 6- to 10-fold). Collagen and AP mRNA were inhibited by hor...

Proceedings ArticleDOI
01 Sep 1991
TL;DR: The results show that using phrases in this way can improve performance, and that phrases that are automatically extracted from a natural language query perform nearly as well as manually selected phrases.
Abstract: Both phrases and Boolean queries have a long history in information retrieval, particularly in commercial systems. In previous work, Boolean queries have been used as a source of phrases for a statistical retrieval model, This work, like the majority of research on phrases, resulted in little improvement in retrieval effectiveness, In this paper, we describe an approach where phrases identified in natural language queries are used to build structured queries for a probabilistic retrieval model. Our results show that using phrases in this way can improve performance, and that phrases that are automatically extracted from a natural language query perform nearly as well as manually selected phrases.

Journal ArticleDOI
TL;DR: Results indicated that the children with ADD+H were rated as having more pervasive behavioral problems at home and more pervasive and severe conduct problems at school than theChildren with ADD-H.
Abstract: The response of 23 children with attention deficit disorder (ADD) with hyperactivity (+H) and 17 children with ADD without hyperactivity (-H) to three doses of methylphenidate (5, 10, and 15 mg twice a day) was evaluated in a triple-blind, placebo-controlled crossover design using parent and teacher ratings of behavior, laboratory tests of ADD symptoms, and behavioral observations during academic performance. Results indicated that the children with ADD+H were rated as having more pervasive behavioral problems at home and more pervasive and severe conduct problems at school than the children with ADD-H. Laboratory tests found the children with ADD+H to be impaired in behavioral inhibition and vigilance whereas children with ADD-H were more impaired in the consistent retrieval of verbally learned material Drug effects were noted on the parent and teacher ratings and on most laboratory measures, with all three doses typically producing significant changes but rarely differing among themselves in effectiveness. The groups were not found to differ significantly on any measures in their response to methylphenidate. However, more children with ADD-H were clinically judged as having either no clinical response (24%) or responding best to the low dose (35%) of medication. In contrast, most ADD+H (95%) children were judged to be positive responders and most were recommended to receive the moderate to high dose (71%).

Journal ArticleDOI
TL;DR: Results indicate that transcript domains do not result directly from a simple clustering of chromatin corresponding to metaphase chromosomes bands, and observations on the reassembly of these domains after mitosis suggest that the clusters of snRNP antigens may be dependent on the reappearance of pol II transcription.
Abstract: The functional organization of the nucleus was studied using a fluorescence microscopy approach which allowed integration of positional information for RNA, DNA, and proteins. In cells from sea urchin to human, nuclear poly(A) RNA was found concentrated primarily within several discrete "transcript domains" which often surrounded nucleoli. Concentrations of poly(A) RNA were coincident with snRNP antigen clusters, providing evidence for the localization of pre-mRNA splicing at these sites. The spatial relationship of transcript domains with respect to various classes of DNA was established, in that the poly(A) RNA-rich regions coincided with discrete regions of low DNA density and were non-randomly distributed with respect to specific DNA sequences. Centromeric DNA and late-replicating DNA did not overlap transcript domains, whereas a subset of early-replicating DNA may. Results indicate that transcript domains do not result directly from a simple clustering of chromatin corresponding to metaphase chromosomes bands. Finally, observations on the reassembly of these domains after mitosis suggest that the clustering of snRNP antigens may be dependent on the reappearance of pol II transcription. Implications of these findings for overall nuclear structure and function are considered, including a discussion of whether transcript domains may be sites of polymerase II transcription reflecting a clustering of active genes.

Journal ArticleDOI
TL;DR: Current evidence suggests that mucosal damage in shock, trauma, and sepsis is likely due to various combinations of intracellular hypoxia due to ischemia, tissue injury caused by reactive oxygen metabolites, the deleterious effects of various lipid mediators, and deficient utilization or supply of key nutritional substrates.
Abstract: Background and MethodsThe mucosa of the GI tract serves as an important barrier limiting the systemic absorption of luminal microbes and microbial products. Two methods commonly used to assess the integrity of the GI mucosal barrier are assessment of the extent of microbial translocation and measure

Journal ArticleDOI
TL;DR: This submaximal walking test based on a single stage of a treadmill protocol provides a valid and time-efficient method for estimating VO2max.
Abstract: An equation was developed to estimate maximal oxygen uptake (VO2max, ml.kg-1.min-1) based on a single submaximal stage of a treadmill walking test. Subjects (67 males, 72 females) aged 20-59 yr completed 4-min stages at 0, 5, and 10% grades walking at a constant speed (2.0-4.5 mph) and then performed a VO2max test. Heart rate and respiratory gas exchange variables were measured during the test. Multiple regression analysis (N = 117) to estimate VO2max from the 4-min stage at 5% grade yielded the following model (R2 = 0.86; SEE = 4.85 ml.kg-1.min-1): VO2max = 15.1 + 21.8*SPEED (mph) -0.327*HEART RATE (bpm) -0.263*SPEED*AGE (yr) + 0.00504*HEART RATE*AGE + 5.98*GENDER (0 = Female; 1 = Male). The constant and all coefficients were highly significant (P less than 0.01). To assess the accuracy of the model in a cross-validation group (N = 22), an estimated VO2max value was obtained using the above model. Estimated VO2max then was regressed on observed VO2max yielding the following equation (R2 = 0.92): ESTIMATED VO2max = 0.15 + 1.03*OBSERVED VO2max. The intercept and slope of this equation were not significantly different from 0 and 1, respectively. For 90.9% of the subjects in the cross-validation group, residual scores were within the range of +/- 5 ml.kg-1.min-1. In conclusion, this submaximal walking test based on a single stage of a treadmill protocol provides a valid and time-efficient method for estimating VO2max.

Journal ArticleDOI
TL;DR: The American Psychological Association (APA) submitted to the Supreme Court amicus curiae brief supporting the validity of the field of stereotyping and the general methods used by the expert.
Abstract: The American Psychological Association filed an amicus curiae brief supporting the validity of the field of stereotyping and the general methods used by the expert. Such legal application provides further lessons for psychological research on stereotyping. The American Psychological Association (APA) submitted to the Supreme Court amicus curiae brief. The relevant psychological literature was heavily cited in Judge Gesell's original decision, and the testimony about the psychology of stereotyping was cited at all levels of the appeal and review process, including the Supreme Court's decision and the subsequent remand. Social science evidence has played a significant role in race discrimination cases in the Supreme Court since Brown v. Board of Education, but such evidence had not before been used in sex discrimination cases. The psychological literature is strong in showing how per vasive stereotypes are, in demonstrating the myriad conditions that promote them, and in showing how resistant they can be to new information.

Journal ArticleDOI
18 Oct 1991-Science
TL;DR: Formation of the OJP may have led to a rise in sea level that induced global oceanic anoxia and carbon dioxide emissions likely contributed to the mid-Cretaceous greenhouse climate but did not provoke major biologic extinctions.
Abstract: The timing of flood basalt volcanism associated with formation of the Ontong Java Plateau (OJP) is estimated from paleomagnetic and paleontologic data. Much of OJP formed rapidly in less than 3 million years during the early Aptian, at the beginning of the Cretaceous Normal Polarity Superchron. Crustal emplacement rates are inferred to have been several times those of the Deccan Traps. These estimates are consistent with an origin of the OJP by impingement at the base of the oceanic lithosphere by the head of a large mantle plume. Formation of the OJP may have led to a rise in sea level that induced global oceanic anoxia. Carbon dioxide emissions likely contributed to the mid-Cretaceous greenhouse climate but did not provoke major biologic extinctions.

Journal ArticleDOI
TL;DR: More ADHD teenagers had oppositional defiant disorder and conduct disorder and were rated as more impaired in social competence, behavioral and emotional adjustment, and school performance by parents and teachers than control teens.
Abstract: Adolescents with attention deficit hyperactivity disorder (ADHD) were compared with a control group on a comprehensive assessment battery. More ADHD teenagers had oppositional defiant disorder (68%) and conduct disorder (39%) and were rated as more impaired in social competence, behavioral and emotional adjustment, and school performance by parents and teachers than control teens. The ADHD youths, however, rated themselves as better adjusted than did their parents and teachers, differing only from controls in depressive symptoms and antisocial acts. Poorer performances in verbal learning and vigilance and greater ADHD behaviors during a math task also distinguished the ADHD from control teenagers.

Journal ArticleDOI
TL;DR: Evidence that Rev is a stable oligomer both in vitro and in vivo is presented and analysis of Rev mutants indicates that oligomerization is essential for RNA binding and hence Rev function.
Abstract: The Rev protein of human immunodeficiency virus type 1 is a sequence-specific RNA binding protein that is essential for viral replication. Here we present evidence that Rev is a stable oligomer both in vitro and in vivo. Analysis of Rev mutants indicates that oligomerization is essential for RNA binding and hence Rev function. The oligomerization and RNA binding domains overlap over 47 amino acids. Within this region is a short arginine-rich motif found in a large class of RNA binding proteins. Substitution of multiple residues within the arginine-rich motif abolishes oligomerization, whereas several single-amino-acid substitution mutants oligomerize but do not bind RNA. Thus, Rev's arginine-rich motif participates in two distinct functions: oligomerization and RNA binding.