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Showing papers by "University of Minnesota published in 1994"


Book
14 Feb 1994
TL;DR: In this article, the authors present a survey of the focus group research, focusing on the following topics: planning the group study, developing a questioning route, participants in a focus group, moderating skills, and conducting interviews with young people.
Abstract: PREFACE ACKNOWLEDGEMENTS 1. Overview of Focus Groups 2. Planning the Focus Group Study 3. Developing a Questioning Route 4. Participants in a Focus Group 5. Moderating Skills 6. Analyzing Focus Group Results 7. Reporting 8. Styles of Focus Group Research 9. Focus Group Interviews With Young People 10. International and Cross-Cultural Focus Groups Interviewing 11. Telephone and Internet Focus Group Interviewing 12. Focus Group Interviews Within the Organization 13. Modifications of Focus Groups 14. Answering Questions About the Quality of Focus Group Research

12,356 citations


Proceedings ArticleDOI
22 Oct 1994
TL;DR: GroupLens is a system for collaborative filtering of netnews, to help people find articles they will like in the huge stream of available articles, and protect their privacy by entering ratings under pseudonyms, without reducing the effectiveness of the score prediction.
Abstract: Collaborative filters help people make choices based on the opinions of other people. GroupLens is a system for collaborative filtering of netnews, to help people find articles they will like in the huge stream of available articles. News reader clients display predicted scores and make it easy for users to rate articles after they read them. Rating servers, called Better Bit Bureaus, gather and disseminate the ratings. The rating servers predict scores based on the heuristic that people who agreed in the past will probably agree again. Users can protect their privacy by entering ratings under pseudonyms, without reducing the effectiveness of the score prediction. The entire architecture is open: alternative software for news clients and Better Bit Bureaus can be developed independently and can interoperate with the components we have developed.

5,644 citations


Journal ArticleDOI
K. Hagiwara, Ken Ichi Hikasa1, Koji Nakamura, Masaharu Tanabashi1, M. Aguilar-Benitez, Claude Amsler2, R. M. Barnett3, Patricia R. Burchat4, C. D. Carone5, C. Caso, G. Conforto6, Olav Dahl3, Michael Doser7, Semen Eidelman8, Jonathan L. Feng9, L. K. Gibbons10, Maury Goodman11, Christoph Grab12, D. E. Groom3, Atul Gurtu7, Atul Gurtu13, K. G. Hayes14, J. J. Herna`ndez-Rey15, K. Honscheid16, Christopher Kolda17, Michelangelo L. Mangano7, David Manley18, Aneesh V. Manohar19, John March-Russell7, Alberto Masoni, Ramon Miquel3, Klaus Mönig, Hitoshi Murayama20, Hitoshi Murayama3, S. Sánchez Navas12, Keith A. Olive21, Luc Pape7, C. Patrignani, A. Piepke22, Matts Roos23, John Terning24, Nils A. Tornqvist23, T. G. Trippe3, Petr Vogel25, C. G. Wohl3, Ron L. Workman26, W-M. Yao3, B. Armstrong3, P. S. Gee3, K. S. Lugovsky, S. B. Lugovsky, V. S. Lugovsky, Marina Artuso27, D. Asner28, K. S. Babu29, E. L. Barberio7, Marco Battaglia7, H. Bichsel30, O. Biebel31, Philippe Bloch7, Robert N. Cahn3, Ariella Cattai7, R. S. Chivukula32, R. Cousins33, G. A. Cowan34, Thibault Damour35, K. Desler, R. J. Donahue3, D. A. Edwards, Victor Daniel Elvira, Jens Erler36, V. V. Ezhela, A Fassò7, W. Fetscher12, Brian D. Fields37, B. Foster38, Daniel Froidevaux7, Masataka Fukugita39, Thomas K. Gaisser40, L. Garren, H.-J. Gerber12, Frederick J. Gilman41, Howard E. Haber42, C. A. Hagmann28, J.L. Hewett4, Ian Hinchliffe3, Craig J. Hogan30, G. Höhler43, P. Igo-Kemenes44, John David Jackson3, Kurtis F Johnson45, D. Karlen, B. Kayser, S. R. Klein3, Konrad Kleinknecht46, I.G. Knowles47, P. Kreitz4, Yu V. Kuyanov, R. Landua7, Paul Langacker36, L. S. Littenberg48, Alan D. Martin49, Tatsuya Nakada50, Tatsuya Nakada7, Meenakshi Narain32, Paolo Nason, John A. Peacock47, Helen R. Quinn4, Stuart Raby16, Georg G. Raffelt31, E. A. Razuvaev, B. Renk46, L. Rolandi7, Michael T Ronan3, L.J. Rosenberg51, Christopher T. Sachrajda52, A. I. Sanda53, Subir Sarkar54, Michael Schmitt55, O. Schneider50, Douglas Scott56, W. G. Seligman57, Michael H. Shaevitz57, Torbjörn Sjöstrand58, George F. Smoot3, Stefan M Spanier4, H. Spieler3, N. J. C. Spooner59, Mark Srednicki60, A. Stahl, Todor Stanev40, M. Suzuki3, N. P. Tkachenko, German Valencia61, K. van Bibber28, Manuella Vincter62, D. R. Ward63, Bryan R. Webber63, M R Whalley49, Lincoln Wolfenstein41, J. Womersley, C. L. Woody48, O. V. Zenin 
Tohoku University1, University of Zurich2, Lawrence Berkeley National Laboratory3, Stanford University4, College of William & Mary5, University of Urbino6, CERN7, Budker Institute of Nuclear Physics8, University of California, Irvine9, Cornell University10, Argonne National Laboratory11, ETH Zurich12, Tata Institute of Fundamental Research13, Hillsdale College14, Spanish National Research Council15, Ohio State University16, University of Notre Dame17, Kent State University18, University of California, San Diego19, University of California, Berkeley20, University of Minnesota21, University of Alabama22, University of Helsinki23, Los Alamos National Laboratory24, California Institute of Technology25, George Washington University26, Syracuse University27, Lawrence Livermore National Laboratory28, Oklahoma State University–Stillwater29, University of Washington30, Max Planck Society31, Boston University32, University of California, Los Angeles33, Royal Holloway, University of London34, Université Paris-Saclay35, University of Pennsylvania36, University of Illinois at Urbana–Champaign37, University of Bristol38, University of Tokyo39, University of Delaware40, Carnegie Mellon University41, University of California, Santa Cruz42, Karlsruhe Institute of Technology43, Heidelberg University44, Florida State University45, University of Mainz46, University of Edinburgh47, Brookhaven National Laboratory48, Durham University49, University of Lausanne50, Massachusetts Institute of Technology51, University of Southampton52, Nagoya University53, University of Oxford54, Northwestern University55, University of British Columbia56, Columbia University57, Lund University58, University of Sheffield59, University of California, Santa Barbara60, Iowa State University61, University of Alberta62, University of Cambridge63
TL;DR: This biennial Review summarizes much of Particle Physics using data from previous editions, plus 2205 new measurements from 667 papers, and features expanded coverage of CP violation in B mesons and of neutrino oscillations.
Abstract: This biennial Review summarizes much of Particle Physics. Using data from previous editions, plus 2205 new measurements from 667 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. This edition features expanded coverage of CP violation in B mesons and of neutrino oscillations. For the first time we cover searches for evidence of extra dimensions (both in the particle listings and in a new review). Another new review is on Grand Unified Theories. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.

5,143 citations


Journal ArticleDOI
TL;DR: In this article, the authors examine the developmental process of cooperative interorganizational relationships (IORs) that entail transaction-specific investments in deals that cannot be fully specified or controlled by the parties in advance of their execution.
Abstract: This article examines the developmental process of cooperative interorganizational relationships (IORs) that entail transaction-specific investments in deals that cannot be fully specified or controlled by the parties in advance of their execution. A process framework is introduced that focuses on formal, legal, and informal social-psychological processes by which organizational parties jointly negotiate, commit to. and execute their relationship in ways that achieve efficient and equitable outcomes and internal solutions to conflicts when they arise. The framework is elaborated with a set of propositions that explain how and why cooperative IORs emerge, evolve, and dissolve. The propositions have academic implications for enriching interorganizational relationships, transaction cost economics, agency theories, and practical implications for managing the relationship journey.

4,904 citations


Journal ArticleDOI
TL;DR: In this article, Chen et al. showed that a treatment effect that decreases with time can be directly visualized by smoothing an appropriate residual plot, which can be expressed as a weighted least-squares line fitted to the residual plot.
Abstract: SUMMARY Nonproportional hazards can often be expressed by extending the Cox model to include time varying coefficients; e.g., for a single covariate, the hazard function for subject i is modelled as exp { fl(t)Zi(t)}. A common example is a treatment effect that decreases with time. We show that the function /3(t) can be directly visualized by smoothing an appropriate residual plot. Also, many tests of proportional hazards, including those of Cox (1972), Gill & Schumacher (1987), Harrell (1986), Lin (1991), Moreau, O'Quigley & Mesbah (1985), Nagelkerke, Oosting & Hart (1984), O'Quigley & Pessione (1989), Schoenfeld (1980) and Wei (1984) are related to time-weighted score tests of the proportional hazards hypothesis, and can be visualized as a weighted least-squares line fitted to the residual plot.

4,770 citations


Journal ArticleDOI
TL;DR: Adaptive structuration theory (AST) as mentioned in this paper examines the change process from two vantage points: (1) the types of structures that are provided by advanced technologies, and (2) the structures that actually emerge in human action as people interact with these technologies.
Abstract: The past decade has brought advanced information technologies, which include electronic messaging systems, executive information systems, collaborative systems, group decision support systems, and other technologies that use sophisticated information management to enable multiparty participation in organization activities. Developers and users of these systems hold high hopes for their potential to change organizations for the better, but actual changes often do not occur, or occur inconsistently. We propose adaptive structuration theory (AST) as a viable approach for studying the role of advanced information technologies in organization change. AST examines the change process from two vantage points: (1) the types of structures that are provided by advanced technologies, and (2) the structures that actually emerge in human action as people interact with these technologies. To illustrate the principles of AST, we consider the small group meeting and the use of a group decision support system (GDSS). A GDS...

3,756 citations


Journal ArticleDOI
01 Sep 1994-Nature
TL;DR: A model is described that explains multispecies coexistence in patchy habitats and which predicts that their abundance may be fleeting, a future ecological cost of current habitat destruction.
Abstract: HABITAT destruction is the major cause of species extinctions1–3. Dominant species often are considered to be free of this threat because they are abundant in the undisturbed fragments that remain after destruction. Here we describe a model that explains multispecies coexistence in patchy habitats4 and which predicts that their abundance may be fleeting. Even moderate habitat destruction is predicted to cause time-delayed but deterministic extinction of the dominant competitor in remnant patches. Further species are predicted to become extinct, in order from the best to the poorest competitors, as habitat destruction increases. More-over, the more fragmented a habitat already is, the greater is the number of extinctions caused by added destruction. Because such extinctions occur generations after fragmentation, they represent a debt—a future ecological cost of current habitat destruction.

2,507 citations


Journal ArticleDOI
TL;DR: Examination of the postreatment factor scores showed that the Y-BOCS resistance items did not assess OCD symptom change as sensitively as the rest of the Y, Brown Obsessive-Compulsive Scale items did.
Abstract: We examined the construction of the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) and performance of subscale items based on data from 204 patients with obsessive-compulsive disorder (OCD) who participated in a multicenter drug treatment study. Factor analysis was used to examine the relationship among the 10 items that make up the Y-BOCS instrument. Models were computed in which both two- and three-factor solutions were estimated. Within the two-factor solution analyses, the factor distribution was not so consistent as in the three-factor solution analyses, and a shift in the factor distribution was noted after treatment. In the three-factor solution analyses, an independent resistance construct emerged in addition to the obsessive and compulsive constructs. Examination of the postreatment factor scores showed that the Y-BOCS resistance items did not assess OCD symptom change as sensitively as the rest of the Y-BOCS items did.

2,460 citations


Journal ArticleDOI
TL;DR: An emergent theory of quality management is proposed and links it to the literature, and a set of reliable and valid scales was developed that may be used by other researchers for hypothesis testing and by practitioners for assessing quality management practices in their plants and for internal and external benchmarking.

1,982 citations


Journal ArticleDOI
27 Jan 1994-Nature
TL;DR: This article showed that primary productivity in more diverse plant communities is more resistant to, and recovers more fully from, a major drought and that each additional species lost from our grasslands had a progressively greater impact on drought resistance.
Abstract: One of the ecological tenets justifying conservation of biodiversity is that diversity begets stability. Impacts of biodiversity on population dynamics and ecosystem functioning have long been debated1–7, however, with many theoretical explorations2–6,8–11 but few field studies12–15. Here we describe a long-term study of grasslands16,17 which shows that primary productivity in more diverse plant communities is more resistant to, and recovers more fully from, a major drought. The curvilinear relationship we observe suggests that each additional species lost from our grasslands had a progressively greater impact on drought resistance. Our results support the diversity—stability hypothesis5,6,18,19, but not the alternative hypothesis that most species are functionally redundant19–21. This study implies that the preservation of biodiversity is essential for the maintenance of stable productivity in ecosystems.

1,941 citations


Journal ArticleDOI
TL;DR: It is argued that the distribution functions for quarks and gluons are computable at small {ital x} for sufficiently large nuclei, perhaps larger than can be physically realized, and that weak coupling methods may be used.
Abstract: We argue that the distribution functions for quarks and gluons are computable at small $x$ for sufficiently large nuclei, perhaps larger than can be physically realized. For such nuclei, we argue that weak coupling methods may be used. We show that the computation of the distribution functions can be recast as a many-body problem with a modified propagator, a coupling constant which depends on the multiplicity of particles per unit rapidity per unit area, and for non-Abelian gauge theories, some extra media-dependent vertices. We explicitly compute the distribution function for gluons to lowest order, and argue how they may be computed in higher order.

Journal ArticleDOI
TL;DR: In this article, a typology of different image formation agents is presented, and a theoretical basis for the touristic image formation process is developed for selecting the appropriate image formation mix.
Abstract: The image formation process has been an area of inquiry for more than 20 years. The process of image formation is intricately entwined with the destination selection process. Understanding the different techniques unitized to form destination images is necessary to developing an image consistent with what a destination has to offer. This paper present a typology of the different image formation agents, describes the process of touristic image formation and provides recommendations for selecting the appropriate image formation mix. It is an attempt to develop a theoretical basis for the touristic image formation process.

Journal ArticleDOI
TL;DR: The authors challenge a prevailing belief within the culture of medicine that while it may be possible to teach information about ethics, course material or even an entire curriculum can in no way decisively influence a student's personality or ensure ethical conduct.
Abstract: The authors raise questions regarding the wide-spread calls emanating from lay and medical audiences alike to intensify the formal teaching of ethics within the medical school curriculum. In particular, they challenge a prevailing belief within the culture of medicine that while it may be possible to teach information about ethics (e.g., skills in recognizing the presence of common ethical problems, skills in ethical reasoning, or improved understanding of the language and concepts of ethics), course material or even an entire curriculum can in no way decisively influence a student's personality or ensure ethical conduct. To this end, several issues are explored, including whether medical ethics is best framed as a body of knowledge and skills or as part of one's professional identity. The authors argue that most of the critical determinants of physician identity operate not within the formal curriculum but in a more subtle, less officially recognized "hidden curriculum." The overall process of medical education is presented as a form of moral training of which formal instruction in ethics constitutes only one small piece. Finally, the authors maintain that any attempt to develop a comprehensive ethics curriculum must acknowledge the broader cultural milieu within which that curriculum must function. In conclusion, they offer recommendations on how an ethics curriculum might be more fruitfully structured to become a seamless part of the training process.

Journal ArticleDOI
TL;DR: This work addresses the problem of global asymptotic stabilization via partial-state feedback for linear systems with nonlinear, stable dynamic perturbations and for systems which have a particular disturbed recurrent structure.
Abstract: We introduce a concept of input-to-output practical stability (IOpS) which is a natural generalization of input-to-state stability proposed by Sontag. It allows us to establish two important results. The first one states that the general interconnection of two IOpS systems is again an IOpS system if an appropriate composition of the gain functions is smaller than the identity function. The second one shows an example of gain function assignment by feedback. As an illustration of the interest of these results, we address the problem of global asymptotic stabilization via partial-state feedback for linear systems with nonlinear, stable dynamic perturbations and for systems which have a particular disturbed recurrent structure.

Journal ArticleDOI
TL;DR: It is shown that the gluon distribution function for very large nuclei may be computed for small transverse momentum as correlation functions of an ultraviolet finite two-dimensional Euclidean field theory.
Abstract: We show that the gluon distribution function for very large nuclei may be computed for small transverse momentum as correlation functions of an ultraviolet finite two-dimensional Euclidean field theory. This computation is valid to all orders in the density of partons per unit area, but to lowest order in ${\ensuremath{\alpha}}_{s}$. The gluon distribution function is proportional to $\frac{1}{x}$, and the effect of the finite density of partons is to modify the dependence on the transverse momentum for small transverse momenta.

Journal ArticleDOI
TL;DR: The Deming management method contains a set of 14 points that serve as guidelines for appropriate organizational behavior and practice regarding quality management as discussed by the authors. But despite the apparent effect of these 14 points on both the industrial world and the practice of management theory around the world, there is little evidence of the role of the Deming Management Method in the formalization and advancement of management theories.
Abstract: In its current form, the Deming management method contains a prescriptive set of 14 points that serve as guidelines for appropriate organizational behavior and practice regarding quality management. Despite the apparent effect of these 14 points on both the industrial world and the practice of management theory around the world, there is little evidence of the role of the Deming management method in the formalization and advancement of management theory. Although its impact on management practice is clear, neither its theoretical contribution nor its theoretical base has yet to be articulated. Yes, there is a theory of quality management underlying the Deming management method, but at present, this theory is presented in the prescriptive form of these 14 points. We propose and articulate a theory of quality management to describe and explain the effects of adopting the Deming management method. This theory is based on the conceptual synthesis of Deming's writings, literature on the Deming management metho...

Journal ArticleDOI
TL;DR: Body mass index (BMI) should be used routinely to screen for overweight adolescents and youths with BMIs > or = 95th percentile for age and sex, or > 30 should be considered overweight and referred for medical follow-up to determine underlying diagnoses.

Journal ArticleDOI
24 Jun 1994-Science
TL;DR: Several examples of enzymatic reactions that appear to use this principle are presented, and a weak hydrogen bond in the enzyme-substrate complex in which the pKa's do not match can become a strong, low-barrier one if the p Ka's become matched in the transition state or enzyme-intermediate complex.
Abstract: Formation of a short (less than 2.5 angstroms), very strong, low-barrier hydrogen bond in the transition state, or in an enzyme-intermediate complex, can be an important contribution to enzymic catalysis. Formation of such a bond can supply 10 to 20 kilocalories per mole and thus facilitate difficult reactions such as enolization of carboxylate groups. Because low-barrier hydrogen bonds form only when the pKa's (negative logarithm of the acid constant) of the oxygens or nitrogens sharing the hydrogen are similar, a weak hydrogen bond in the enzyme-substrate complex in which the pKa's do not match can become a strong, low-barrier one if the pKa's become matched in the transition state or enzyme-intermediate complex. Several examples of enzymatic reactions that appear to use this principle are presented.

Journal ArticleDOI
01 Jul 1994-Immunity
TL;DR: An adoptive transfer system was used to monitor physically the behavior of a trace population of TCR transgenic T cells in vivo, providing a physical basis for the classical finding that antigen-specific memory and tolerance can be influenced by the form of antigen administration.

Journal ArticleDOI
TL;DR: In this article, a broader, more theory-driven perspective on TQM is proposed to clearly distinguish control from learning goals and, thus, to begin to address limitations in the way total quality management has been conceptualized and applied in the past.
Abstract: The singular emphasis on control that has characterized traditional approaches to total quality management (TQM) implementation are not well suited to conditions of high task uncertainty, a limitation that has not been recognized in the popular TQM movement. Although the fundamental precepts advocated by founders of the quality movement can accommodate conditions of high uncertainty, the way that these basic TQM precepts have been articulated, extended, and applied has not reflected the distinct, learning-oriented requirements associated with higher levels of uncertainty. A broader, more theory-driven perspective on TQM is proposed to clearly distinguish control from learning goals and, thus, to begin to address limitations in the way TQM has been conceptualized and applied in the past.

Journal ArticleDOI
TL;DR: There are a number of components present in soybeans that exert a negative impact on the nutritional quality of the protein and the allergenic response that may sometimes occur in humans, as well as calves and piglets, on dietary exposure to soybeans.
Abstract: There are a number of components present in soybeans that exert a negative impact on the nutritional quality of the protein. Among those factors that are destroyed by heat treatment are the protease inhibitors and lectins. Protease inhibitors exert their antinutritional effect by causing pancreatic hypertrophy/hyperplasia, which ultimately results in an inhibition of growth. The lectin, by virtue of its ability to bind to glycoprotein receptors on the epithelial cells lining the intestinal mucosa, inhibits growth by interfering with the absorption of nutrients. Of lesser significance are the antinutritional effects produced by relatively heat stable factors, such as goitrogens, tannins, phytoestrogens, flatus-producing oligosaccharides, phytate, and saponins. Other diverse but ill-defined factors appear to increase the requirements for vitamins A, B12, D, and E. The processing of soybeans under severe alkaline conditions leads to the formation of lysinoalanine, which has been shown to damage the kidneys of rats. This is not generally true, however, for edible soy protein that has been produced under milder alkaline conditions. Also meriting consideration is the allergenic response that may sometimes occur in humans, as well as calves and piglets, on dietary exposure to soybeans.

Journal ArticleDOI
TL;DR: It is shown how one can compute the sea quark distribution functions, and explictly compute them in the kinematic range of transverse momenta, α 2 � 2 << k 2 t << � 2 , where � 2 is the average color charge squared per unit area.
Abstract: We compute the Green's function for scalars, fermions, and vectors in the color field associated with the infinite momentum frame wave function of a large nucleus. Expectation values of this wave function can be computed by integrating over random orientations of the valence quark charge density. This relates the Green's functions to correlation functions of a two-dimensional, ultraviolet finite, field theory. We show how one can compute the sea quark distribution functions and explicitly compute them in the kinematic range of transverse momenta, ${\mathrm{\ensuremath{\alpha}}}_{\mathit{s}}^{2}$${\mathrm{\ensuremath{\mu}}}^{2}$\ensuremath{\ll}${\mathit{k}}_{\mathit{t}}^{2}$\ensuremath{\ll}${\mathrm{\ensuremath{\mu}}}^{2}$, where ${\mathrm{\ensuremath{\mu}}}^{2}$ is the average color charge squared per unit area. When ${\mathit{m}}_{\mathrm{quark}}^{2}$\ensuremath{\ll}${\mathrm{\ensuremath{\mu}}}^{2}$\ensuremath{\sim}${\mathit{A}}^{1/3}$, the sea quark contribution to the infinite momentum frame wave function saturates at a value that is the same as that for massless sea quarks.

Journal ArticleDOI
TL;DR: NO and cGMP relax vascular smooth muscle by a cG MP-dependent protein kinase-dependent activation of K channels, which suggests that the final common pathway shared by NO and the nitrovasodilators is cGmp-dependent K-channel activation.
Abstract: Nitric oxide (NO)-induced relaxation is associated with increased levels of cGMP in vascular smooth muscle cells. However, the mechanism by which cGMP causes relaxation is unknown. This study tested the hypothesis that activation of Ca-sensitive K (KCa) channels, mediated by a cGMP-dependent protein kinase, is responsible for the relaxation occurring in response to cGMP. In rat pulmonary artery rings, cGMP-dependent, but not cGMP-independent, relaxation was inhibited by tetraethylammonium, a classical K-channel blocker, and charybdotoxin, an inhibitor of KCa channels. Increasing extracellular K concentration also inhibited cGMP-dependent relaxation, without reducing vascular smooth muscle cGMP levels. In whole-cell patch-clamp experiments, NO and cGMP increased whole-cell K current by activating KCa channels. This effect was mimicked by intracellular administration of (Sp)-guanosine cyclic 3',5'-phosphorothioate, a preferential cGMP-dependent protein kinase activator. Okadaic acid, a phosphatase inhibitor, enhanced whole-cell K current, consistent with an important role for channel phosphorylation in the activation of NO-responsive KCa channels. Thus NO and cGMP relax vascular smooth muscle by a cGMP-dependent protein kinase-dependent activation of K channels. This suggests that the final common pathway shared by NO and the nitrovasodilators is cGMP-dependent K-channel activation.

Journal ArticleDOI
TL;DR: Experiments on root and rhizosphere response in plants grown in CO(2)-enriched atmospheres will be reviewed and, where possible, collectively integrated, to offer a series of hypotheses which are considered as priority targets for future research.

Journal ArticleDOI
TL;DR: The lack of efficacy of these vitamins argues against the use of supplemental beta carotene and vitamins C and E to prevent colorectal cancer.
Abstract: Background People who consume a diet high in vegetables and fruits have a lower risk of cancer of the large bowel. Antioxidant vitamins, which are present in vegetables and fruits, have been associated with a diminished risk of cancers at various anatomical sites. We conducted a randomized, controlled clinical trial to test the efficacy of beta carotene and vitamins C and E in preventing colorectal adenoma, a precursor of invasive cancer. Methods We randomly assigned 864 patients, using a two-by-two factorial design, to four treatment groups, which received placebo, beta carotene (25 mg daily), vitamin C (1 g daily) and vitamin E (400 mg daily), or beta carotene plus vitamins C and E. In order to identify new adenomas, we performed complete colonoscopic examinations in the patients one year and four years after they entered the study. The primary end points for analyses were new adenomas identified after the first of these two follow-up examinations. Results Patients adhered well to the prescribed regimen...

Journal ArticleDOI
TL;DR: In this article, a method for performing electronic structure calculations without the explicit use of a basis is presented. But this method requires the use of supercell geometries and no artifacts such as supercells need be introduced for localized systems.
Abstract: We present a method for performing electronic structure calculations without the explicit use of a basis. We combine a finite-difference approach with ab initio pseudopotentials. In contrast to methods which use a plane wave basis, our calculations are performed completely in ``real space.'' No artifacts such as supercell geometries need be introduced for localized systems. Although this approach is easier to implement than one with a plane wave basis, no loss of accuracy occurs. The electronic structure of several diatomic molecules, ${\mathrm{Si}}_{2}$, ${\mathrm{C}}_{2}$, ${\mathrm{O}}_{2}$, and CO, are calculated to illustrate the utility of this method.

Journal ArticleDOI
TL;DR: This ILUT factorization extends the usual ILU(O) factorization without using the concept of level of fill-in, and is a compromise between these two extremes.
Abstract: In this paper we describe an Incomplete LU factorization technique based on a strategy which combines two heuristics. This ILUT factorization extends the usual ILU(O) factorization without using the concept of level of fill-in. There are two traditional ways of developing incomplete factorization preconditioners. The first uses a symbolic factorization approach in which a level of fill is attributed to each fill-in element using only the graph of the matrix. Then each fill-in that is introduced is dropped whenever its level of fill exceeds a certain threshold. The second class of methods consists of techniques derived from modifications of a given direct solver by including a dropoff rule, based on the numerical size of the fill-ins introduced, traditionally referred to as threshold preconditioners. The first type of approach may not be reliable for indefinite problems, since it does not consider numerical values. The second is often far more expensive than the standard ILU(O). The strategy we propose is a compromise between these two extremes.

Journal ArticleDOI
02 Dec 1994-Cell
TL;DR: Results show that beta-catenin has an important role in dorsal mesoderm induction and directly demonstrate the activity of a maternal mRNA in axis specification.

Journal ArticleDOI
28 Jan 1994-Cell
TL;DR: It is suggested that the catalytic activity of the Fet3 protein is required for cellular iron accumulation, similar to that of the blue multicopper oxidoreductases.

Journal ArticleDOI
TL;DR: Evidence has been presented suggesting that NO participates in the mechanisms of cerebral ischemic damage and the evidence for and against a role of NO is critically examined.
Abstract: There is increasing evidence that nitric oxide (NO) is an important molecular messenger involved in a wide variety of biological processes. Recent data suggest that NO is also involved in the regulation of the cerebral circulation. Thus, NO participants in the maintenance of resting cerebrovascular tone and may play an important role in selected vasodilator responses of the cerebral circulation. Furthermore, evidence has been presented suggesting that NO participates in the mechanisms of cerebral ischemic damage. Despite the widespread attention that NO has captured in recent years and the large number of studies that have been published on the subject, there is considerable controversy regarding the role of this agent in cerebrovascular regulation and in ischemic damage. In this paper the results of investigations on NO and the cerebral circulation are reviewed and the evidence for and against a role of NO is critically examined.