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Showing papers by "University of Arizona published in 1990"


Journal ArticleDOI
TL;DR: A new approach to rapid sequence comparison, basic local alignment search tool (BLAST), directly approximates alignments that optimize a measure of local similarity, the maximal segment pair (MSP) score.

88,255 citations


Journal ArticleDOI
27 Sep 1990-Nature
TL;DR: In this article, a new form of pure, solid carbon has been synthesized consisting of a somewhat disordered hexagonal close packing of soccer-ball-shaped C60 molecules.
Abstract: A new form of pure, solid carbon has been synthesized consisting of a somewhat disordered hexagonal close packing of soccer-ball-shaped C60 molecules. Infrared spectra and X-ray diffraction studies of the molecular packing confirm that the molecules have the anticipated 'fullerene' structure. Mass spectroscopy shows that the C70 molecule is present at levels of a few per cent. The solid-state and molecular properties of C60 and its possible role in interstellar space can now be studied in detail.

6,650 citations


Journal ArticleDOI
TL;DR: There is every reason to believe that a specialization for grammar evolved by a conventional neo-Darwinian process, as well as other arguments and data.
Abstract: Many people have argued that the evolution of the human language faculty cannot be explained by Darwinian natural selection. Chomsky and Gould have suggested that language may have evolved as the by-product of selection for other abilities or as a consequence of as-yet unknown laws of growth and form. Others have argued that a biological specialization for grammar is incompatible with every tenet of Darwinian theory – that it shows no genetic variation, could not exist in any intermediate forms, confers no selective advantage, and would require more evolutionary time and genomic space than is available. We examine these arguments and show that they depend on inaccurate assumptions about biology or language or both. Evolutionary theory offers clear criteria for when a trait should be attributed to natural selection: complex design for some function, and the absence of alternative processes capable of explaining such complexity. Human language meets these criteria: Grammar is a complex mechanism tailored to the transmission of propositional structures through a serial interface. Autonomous and arbitrary grammatical phenomena have been offered as counterexamples to the position that language is an adaptation, but this reasoning is unsound: Communication protocols depend on arbitrary conventions that are adaptive as long as they are shared. Consequently, language acquisition in the child should systematically differ from language evolution in the species, and attempts to analogize them are misleading. Reviewing other arguments and data, we conclude that there is every reason to believe that a specialization for grammar evolved by a conventional neo-Darwinian process.

2,002 citations


Journal ArticleDOI
01 Oct 1990
TL;DR: It is suggested that systems development and empirical research methodologies are complementary to each other and an integrated multidimensional and multimethodological approach will generate fruitful research results in IS research.
Abstract: The authors critically review systems development in information systems (IS) research. Several classification schemes of research are described and systems development is identified as a developmental, engineering, and formulative type of research. A framework of research is proposed to explain the dual nature of systems development as a research methodology and a research domain in IS research. Progress in several disciplinary areas is reviewed to provide a basis to argue that systems development is a valid research methodology. A systems development research process is presented from a methodological perspective. Software engineering, the basic method is applying the systems development research methodology, is then discussed. A framework to classify IS research domain and various research methodologies in studying systems development is presented. It is suggested that systems development and empirical research methodologies are complementary to each other. It is further proposed that an integrated multidimensional and multimethodological approach will generate fruitful research results in IS research. >

1,387 citations


Journal ArticleDOI
TL;DR: The authors found that mortality saliency led to positive reactions to someone who directly praised subjects' cultural worldviews and especially negative reactions to those who criticized them, but only among subjects high in authoritarianism.
Abstract: Three experiments were conducted to test the hypothesis, derived from terror management theory, that reminding people of their mortality increases attraction to those who consensually validate their beliefs and decreases attraction to those who threaten their beliefs. In Study 1, subjects with a Christian religious background were asked to form impressions of Christian and Jewish target persons. Before doing so, mortality was made salient to half of the subjects. In support of predictions, mortality salience led to more positive evaluations of the in-group member (the Christian) and more negative evaluations of the out-group member (the Jew). In Study 2, mortality salience led to especially negative evaluations of an attitudinally dissimilar other, but only among subjects high in authoritarianism. In Study 3, mortality salience led to especially positive reactions to someone who directly praised subjects' cultural worldviews and especially negative reactions to someone who criticized them. The implications of these findings for understanding in-group favoritism, prejudice, and intolerance of deviance are discussed.

1,362 citations


Book
26 Jan 1990
TL;DR: In this paper, the authors present an analytical framework for contracts for property rights, mineral rights, and changes in federal land policies in the United States, as well as contracts for the utilization of oil fields.
Abstract: Series editors' preface 1. Contracting for property rights 2. Analytical framework 3. Contracting for mineral rights 4. Contracting for changes in federal land policies 5. Contracting in fisheries 6. Contracting for the utilization of oil fields 7. Concluding remarks References Index.

1,023 citations


Book
01 Jan 1990
TL;DR: The primary ethical framework: patient-centered principles and application: Advance directives, personhood, and personal identity provide a framework for distributing justice and the incompetent.
Abstract: Preface Introduction Part I. Theory: 1. Competence and incompetence 2. The primary ethical framework: patient-centered principles 3. Advance directives, personhood, and personal identity 4. Distributive justice and the incompetent Part II. Application: 5. Minors 6. The elderly 7. The mentally ill Looking forward Appendix 1: living trust and nomination of conservatorship Appendix 2: durable power of attorney for health care Notes Index.

1,001 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of time and communication channel (computer conferencing versus face-to-face meetings) on impression development, message personalization, and relational communication in groups were investigated.
Abstract: This study involved an experiment of the effects of time and communication channel--computer conferencing versus face-to-face meetings--on impression development, message personalization, and relational communication in groups. Prior research on the relational aspects of computer-mediated communication has suggested strong depersonalizing effects of the medium due to the absence of nonverbal cues. Past research is criticized for failing to incorporate temporal and developmental perspectives on information processing and relational development. In this study data were collected from, and observations made of 96 subjects assigned to computer conferencing or traditional zero-history groups of three, who completed three tasks over several weeks' time. Results showed that computer-mediated groups increased in several relational dimensions to more positive levels, and that these subsequent levels approximated those of face-to-face groups. Boundaries on the predominant theories of computer-mediated communication are recommended, and future research is suggested.

1,000 citations


Journal ArticleDOI
Karen Wynn1
TL;DR: Children learn the meanings of smaller number words before larger ones within their counting range, up to the number three or four, indicating that children learn the cardinal word principle at roughly 3 1/2 years of age.

926 citations


Journal ArticleDOI
TL;DR: In this article, a continuous contact force model for the impact analysis of a two-particle collision is presented, where a hysteresis damping function is incorporated in the model which represents the dissipated energy in impact.
Abstract: A continuous contact force model for the impact analysis of a two-particle collision is presented. The model uses the general trend of the Hertz contact law. A hysteresis damping function is incorporated in the model which represents the dissipated energy in impact. The parameters in the model are determined, and the validity of the model is established. The model is then generalized to the impact analysis between two bodies of a multibody system. A continuous analysis is performed using the equations of motion of either the multibody system or an equivalent two-particle model of the colliding bodies. For the latter, the concept of effective mass is presented in order to compensate for the effects of joint forces in the system. For illustration, the impact situation between a slider-crank mechanism and another sliding block is considered.

807 citations


Journal ArticleDOI
TL;DR: In carbon smoke samples prepared from vaporized graphite at elevated quenching gas pressures (e.g. > 100 Torr He) new absorption features have been observed in the infrared (the strongest at 1429, 1183, 577, and 528 cm −1 ).

Journal ArticleDOI
TL;DR: Hepatitis B e antigen and hepatitis B viral DNA disappeared from serum significantly more often in the patients given prednisone plus interferon or 5 million units of interferons alone than in the untreated controls.
Abstract: Background and Methods. Chronic hepatitis B is a common and often progressive liver disorder for which there is no accepted therapy. To assess the efficacy of treatment with interferon, we randomly assigned patients with chronic hepatitis B to one of the following regimens: prednisone for 6 weeks followed by 5 million units of recombinant interferon alfa-2b daily for 16 weeks; placebo followed by 5 million units of interferon daily for 16 weeks; placebo followed by 1 million units of interferon daily for 16 weeks; or observation with no treatment. Results. Hepatitis B e antigen and hepatitis B viral DNA disappeared from serum significantly more often in the patients given prednisone plus interferon (16 of 44 patients, or 36 percent) or 5 million units of interferon alone (15 of 41; 37 percent) than in the untreated controls (3 of 43; 7 percent; P<0.001); the difference between those given 1 million units of interferon (7 of 41; 17 percent) and the controls was not significant. The strongest indep...

Journal ArticleDOI
TL;DR: The data indicate that C. parvum oocysts are 30 times moreresistant to ozone and 14 times more resistant to chlorine dioxide than Giardia cysts exposed to these disinfectants under the same conditions.
Abstract: Purified Cryptosporidium parvum oocysts were exposed to ozone, chlorine dioxide, chlorine, and monochloramine. Excystation and mouse infectivity were comparatively evaluated to assess oocyst viability. Ozone and chlorine dioxide more effectively inactivated oocysts than chlorine and monochloramine did. Greater than 90% inactivation as measured by infectivity was achieved by treating oocysts with 1 ppm of ozone (1 mg/liter) for 5 min. Exposure to 1.3 ppm of chlorine dioxide yielded 90% inactivation after 1 h, while 80 ppm of chlorine and 80 ppm of monochloramine required approximately 90 min for 90% inactivation. The data indicate that C. parvum oocysts are 30 times more resistant to ozone and 14 times more resistant to chlorine dioxide than Giardia cysts exposed to these disinfectants under the same conditions. With the possible exception of ozone, the use of disinfectants alone should not be expected to inactivate C. parvum oocysts in drinking water.

Book
01 May 1990
TL;DR: This book discusses the development of working relationships in Scientific Research Collaborations, the role of technology in this work, and experiences with technology for Cooperative Work.
Abstract: Contents: J. Galegher, R.E. Kraut, Technology for Intellectual Teamwork: Perspectives on Research and Design. Part I:Basic Social Processes. J.E. McGrath, Time Matters in Groups. B.A. Gutek, Work Group Structure and Information Technology: A Structural Contingency Approach. J.J. Gabarro, The Development of Working Relationships. R.M. Krauss, S.R. Fussell, Mutual Knowledge and Communicative Effectiveness. Part II:Field Studies of Collaborative Work. R.E. Kraut, C. Egido, J. Galegher, Patterns of Contact and Communication in Scientific Research Collaborations. D.G. Ancona, D.F. Caldwell, Information Technology and Work Groups: The Case of New Product Teams. E. Hutchins, The Technology of Team Navigation. A.V. Cicourel, The Integration of Distributed Knowledge in Collaborative Medical Diagnosis. Part III:Experiences With Technology for Cooperative Work. T.K. Bikson, J.D. Eveland, The Interplay of Work Group Structures and Computer Support. T. Finholt, L. Sproull, S. Kiesler, Communication and Performance in ad hoc Task Groups. R.E. Rice, D.E. Shook, Voice Messaging, Coordination, and Communication. C. Egido, Teleconferencing as a Technology to Support Cooperative Work: Its Possibilities and Limitations. K.L. Kraemer, A. Pinsonneault, Technology and Groups: Assessments of the Empirical Research. Part IV:Technology for Cooperative Work. G.P. Landow, Hypertext and Collaborative Work: The Example of Intermedia. G.M. Olson, D.E. Atkins, Supporting Collaboration With Advanced Multimedia Electronic Mail: The NSF EXPRES Project. F. Lakin, Visual Languages for Cooperation: A Performing Medium Approach to Systems for Cooperative Work. M. Abel, Experiences in an Exploratory Distributed Organization. D.R. Vogel, J.F. Nunamaker, Design and Assessment of a Group Decision Support System.

Journal ArticleDOI
TL;DR: In this paper, the physical and chemical characterization of two new molecular forms of carbon, C{sub 60} and C {sub 70} were reported. But the results demonstrate a high yield of production (14%) under optimized conditions and reveal only C{ sub 60 and Csub 70 in measurable quantity, in an 85:15 ratio.
Abstract: The authors report on the further physical and chemical characterization of the new forms of molecular carbon, C{sub 60} and C{sub 70}. Results demonstrate a high yield of production (14%) under optimized conditions and reveal only C{sub 60} and C{sub 70} in measurable quantity, in an 85:15 ratio. These two new molecular forms of carbon can be completely separated in analytical amounts by column chromatography on alumina. Comparison among mass spectra obtained by the electron impact, laser desorption, and fast atom bombardment (FAB) methods allows a clear assessment of the composition of the mixed and pure samples, and of the fragmentation and double ionization patterns of the molecules. In addition, spectroscopic analyses are reported for the crude mixture by {sup 13}C NMR and by IR spectroscopy in KBr pellet, and for pure C{sub 60} and C{sub 70} in solution by UV-vis spectroscopy.

Journal ArticleDOI
31 Aug 1990-Science
TL;DR: Synchrony of fire-free and severe fire years across diverse southwestern forests implies that climate forces fire regimes on a subcontinental scale; it also underscores the importance of exogenous factors in ecosystem dynamics.
Abstract: Fire scar and tree growth chronologies (1700 to 1905) and fire statistics (since 1905) from Arizona and New Mexico show that small areas burn after wet springs associated with the low phase of the Southern Oscillation (SO), whereas large areas burn after dry springs associated with the high phase of the SO. Through its synergistic influence on spring weather and fuel conditions, climatic variability in the tropical Pacific significantly influences vegetation dynamics in the southwestern United States. Synchrony of fire-free and severe fire years across diverse southwestern forests implies that climate forces fire regimes on a subcontinental scale; it also underscores the importance of exogenous factors in ecosystem dynamics.

Journal ArticleDOI
TL;DR: In this paper, a framework to analyze implicit or explicit behavioral theories found in laws, regulations, and programs is presented, focusing on policy tools or instruments and the underly hidden theories.
Abstract: This paper provides a framework to analyze the implicit or explicit behavioral theories found in laws, regulations, and programs. The analysis focuses on policy tools or instruments and the underly...

Journal ArticleDOI
TL;DR: In this article, the authors explore two related literatures, teacher change and learning to teach, and develop a third perspective, which will be grounded in examples from a teacher change research project which is funded by the Office of Educational Research and Improvement (OERI), U.S. Department of Education.
Abstract: This paper addresses two questions: What is involved in bringing about significant and worthwhile change in teaching practices? How can or should research aid in this process? In order to do so, two related literatures will be explored—teacher change and learning to teach. These literatures will be used to develop a third perspective, which will be grounded in examples from a teacher change research project which is funded by the Office of Educational Research and Improvement (OERI), U.S. Department of Education. This perspective suggests that empirical premises derived from research (Fenstermacher, 1986) be considered as warranted practice, which, in combination with teachers's practical knowledge, become the content of reflective teacher change. It also suggests that practice should be viewed as activity embedded in theory. The paper concludes with suggestions for ways of approaching the introduction of research into teachers' ways of thinking.

Journal ArticleDOI
TL;DR: The authors adopt the notions of signal set expansion, set partitioning, and branch labeling of TCM, but modify the techniques to account for the source distribution, to design TCQ coders of low complexity with excellent mean-squared-error (MSE) performance.
Abstract: Trellis-coded quantization (TCQ) is developed and applied to the encoding of memoryless and Gauss-Markov sources. The theoretical justification for the approach is alphabet-constrained rate distortion theory, which is a dual to the channel capacity argument that motivates trellis-coded modulation (TCM). The authors adopt the notions of signal set expansion, set partitioning, and branch labeling of TCM, but modify the techniques to account for the source distribution, to design TCQ coders of low complexity with excellent mean-squared-error (MSE) performance. For a memoryless uniform source, TCQ provides an MSE within 0.21 dB of the distortion-rate bound at all positive (integral) rates. The performance is superior to that promised by the coefficient of quantization for all of the best lattices known in dimensions 24 or less. For a memoryless Gaussian source, the TCQ performance at rates of 0.5, 1, and 2 b/sample is superior to all previous results the authors found in the literature. The encoding complexity of TCQ is very modest. TCQ is incorporated into a predictive coding structure for the encoding of Gauss-Markov sources. Simulation results for first-, second-, and third-order Gauss-Markov sources are presented. >

Journal ArticleDOI
TL;DR: Possible relationships between the non-telomeric distribution of the (TTAGGG)n sequence and the process of karyotype evolution, during which these sites may provide potential new telomeres are discussed.
Abstract: The intrachromosomal distribution of non-telomeric sites of the (TTAGGG)n telomeric repeat was determined for 100 vertebrate species. The most common non-telomeric location of this sequence was in the pericentric regions of chromosomes. A variety of species showed relatively large amounts of this sequence present within regions of constitutive heterochromatin. We discuss possible relationships between the non-telomeric distribution of the (TTAGGG)n sequence and the process of karyotype evolution, during which these sites may provide potential new telomeres.

Journal ArticleDOI
TL;DR: Some of the more useful approaches to the design of peptide ligands with highly potent and specific biological and conformational properties are summarized, and the future development in this area is assessed.
Abstract: A central goal in peptide and protein research is the development of rational approaches to the design of peptide and protein ligands with specific physical, chemical, and biological properties. In the case of peptide ligands which generally act by interactions with receptors or acceptor molecules (hormones, neurotransmitters, growth promoters and inhibitors, immunomodulators, etc...), the problem is complicated by several inherent difficulties. Despite these difficulties, considerable progress has been made in the development of a rational approach to the design of peptide ligands with highly potent and specific biological and conformational properties. In this review, we summarize some of the more useful approaches which have emerged from these studies, and assess the future development in this area

Journal ArticleDOI
TL;DR: In this paper, determinants of political violence at the cross-national level are derived from rational action theory and tested across the entire population of independent states in the mid-1940s.
Abstract: Propositions about determinants of political violence at the cross-national level are derived from rational action theory and tested across the entire population of independent states in the mid-19...

Journal ArticleDOI
TL;DR: Implicit memory effects need not and often do not involve any conscious or explicit recollection of a prior episode, and thus can be said to reflect implicit memory for previously studied information.
Abstract: Consider the following experimental situations. In the first, subjects are shown a list of familiar words and are instructed to carefully study each of them. After performing a variety of unrelated tasks for several minutes, they are told to think back to the study list and recall as many of the presented words as possible. Subjects are then shown a series of words-half were presented in the study list, half were not-and are instructed to say “yes” if they remember having studied the items, and “no” if they do not remember them. In the second situation, subjects also study a word list and then engage in unrelated activities for a few minutes. However, instead of then being asked to remember previously studied items, the subjects are asked to write down the first word that comes to mind in response to a series of 3-letter word stems; some can be completed with previously studied words, and some cannot. The first of these two hypothetical situations reflects the way in which cognitive psychologists have traditionally studied human memory: by assessing subjects’ intentional or explicit memoy for information acquired during a study episode with standard recall and recognition tests. In the second situation, memory is inferred from an enhanced tendency to complete 3-letter stems with previously studied words; this is often referred to as “repetition priming” or “direct priming” (cf., Cofer, 1967; Tulving & Schacter, 1990). Priming effects need not and often do not involve any conscious or explicit recollection of a prior episode, and thus can be said to reflect implicit memory for previously studied information (Graf & Schacter, 1985; Schacter, 1987). Priming has been assessed with a variety of implicit memory tasks that do not require explicit recollection of a specific prior episode. One common type of implicit test involves completing word stems or word fragments with the first word that comes to mind, as in the foregoing example (e.g., Graf & Mandler, 1984; Light, Singh & Capps, 1986; Roediger & Blaxton, 1987a, b; Schacter & Graf, 1986a, b; Tulving, Schacter & Stark, 1982). Another frequently used implicit task involves word identification: Subjects are required to try to identify a word from a brief (e.g., 50-msec) perceptual exposure, and priming is indicated by more accurate identification of a recently studied item than of a new, nonstudied item (e.g., Jacoby, 1983a, b;


Journal ArticleDOI
TL;DR: Fuzzy-trace theory is a gist-driven interpretation of cognitive development that has descended from, but is distinctly different than, the Piagetian and information-processing traditions.

Journal ArticleDOI
TL;DR: In this paper, modern fire records and fire-scarred remnant material collected from logs, snags, and stumps were used to reconstruct and analyze fire history in the mixed-conifer and pine forest above 2300m.
Abstract: Modern fire records and fire-scarred remnant material collected from logs, snags, and stumps were used to reconstruct and analyze fire history in the mixed-conifer and pine forest above 2300 m with...

Journal ArticleDOI
TL;DR: In this paper, chemical elements are used as tracers in a mass balance analysis that provides functional relationships among soil chemical composition, bulk density, and volume change in relation to parent material.

Journal ArticleDOI
TL;DR: A number of task-specific approaches to the assessment of image quality are treated, but only linear estimators or classifiers are permitted, and results are expressed as signal-to-noise ratios (SNR's).
Abstract: A number of task-specific approaches to the assessment of image quality are treated. Both estimation and classification tasks are considered, but only linear estimators or classifiers are permitted. Performance on these tasks is limited by both quantum noise and object variability, and the effects of postprocessing or image-reconstruction algorithms are explicitly included. The results are expressed as signal-to-noise ratios (SNR's). The interrelationships among these SNR's are considered, and an SNR for a classification task is expressed as the SNR for a related estimation task times four factors. These factors show the effects of signal size and contrast, conspicuity of the signal, bias in the estimation task, and noise correlation. Ways of choosing and calculating appropriate SNR's for system evaluation and optimization are also discussed.

Journal ArticleDOI
TL;DR: This study examines the influence of anonymity on group process in groups using a group decision support system (GDSS) with an idea-generating task and finds group members whose contributions were anonymous generated more comments, were more critical and probing, and were more likely to embellish ideas proposed by others.
Abstract: This study examines the influence of anonymity on group process in groups using a group decision support system (GDSS) with an idea-generating task. Group members whose contributions were anonymous generated more comments, were more critical and probing, and were more likely to embellish ideas proposed by others than were those whose contributions were identified by name. Implications for group support research are discussed.

Journal ArticleDOI
TL;DR: In this article, the degradability of starch from corn, milo, wheat, barley, and oats was determined in vitro using a 60-min incubation in a glucoamylase enzyme.