901 resultados para Nontrivial critical point of a polynomial


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Using a phenomenological asymmetric nuclear equation of state, we obtained pressure-density isotherms of the finite nucleus Sn-112 simulated in r-space and in p-space and constructed the nuclear fragments by using the coalescence model. After correlatively analysing the fragments, the signal of critical behavior has been found and critical exponents were also extracted.

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This paper deals with determining points of zero charge of natural and Na+-saturated mineral kaolinites using two methods: (1) acid-base potentiometric titration was employed to obtain the adsorption of H+ and OH- on amphoteric surfaces in solutions of varying ionic strengths in order to determinate graphically the point of zero net proton charge (PZNPC) defined equally as point of zero salt effect (PZSE); (2) mass titration curve at different electrolyte concentrations in order to estimate PZNPCs by interpolation and to compare with those determined by potentiometric titrations. The two methods involved points of zero charge approximately similar for the two kaolinites between 6.5-7.8, comparable to those reported previously and were in the range expected for these clay minerals. The comparison of potentiometric surface titration curves obtained at 25 °C and those published in the literature reveals significant discrepancies both in the shape and in the pH of PZNPCs values.

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zero point of charge of freshly precipitated cu(oh)2 has been determined to lie at pH 7.7 by means of microclectrophoresis technique. Day aged hydroxide shows an acid zpc shift to pH 7.3. these experimental values approximate the equivalence points of cu+ and oh_ ,which can be estimated from the solubility diagram constructed fo gu(oh)2 and cuo.

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the salt ritration metod was evaluated as a method to determine zpc in comparison with the potentiometric titration method for 26 soil with variable charge clays,i.e.,Oxisols and Ultisols from Thailand and Andisols from Japan. In addition to the determination of ST-pH0 as the zero point of charge, a calculation procedure was adopted here in order to acquire more information from the titration curve . fuithermore, for the purpose of cross-checking of zpc determined by the pt method, the st procedure was successively applied to the samples analyzed by the pt method.

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We report that the brittle-ductile transition of polymers induced by temperature exhibits critical behavior. When t close to 0, the critical surface to surface interparticle distance (IDc) follows the scaling law: IDc proportional to t(-v) where t = 1 - T/T-BD(m) (T and T-BD(m) are the test temperature and brittle-ductile transition temperature of matrix polymer, respectively) and v = 2/D. It is clear that the scaling exponent v only depends on dimension (D). For 2, 3, and 4 dimension, v = 1, 2/3, and 1/2 respectively. The result indicates that the ID, follows the same scaling law as that of the correlation length (xi), when t approach to zero.

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The unique surface-sensitive properties make quantum dots (QDs) great potential in the development of sensors for various analytes. However, quantum dots are not only sensitive to a certain analyte, but also to the surrounding conditions. The controlled response to analyte may be the first step in the designing of functional quantum dots sensors. In this study, taking the quenching effect of benzoquinone (BQ) on CdTe QDs as model, several critical parameters of buffer solution conditions with potential effect on the sensors were investigated. The pH value and the concentration of sodium citrate in the buffer solution critically influenced the quenching effects of BQ.

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Kohl, U. (2004). Who has the right to govern online activity? A criminal and civil point of view. International Review of Law, Computers & Technology 18 (3), 387-410 RAE2008

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Griffiths, L.; and O'Malley, T. (2007). Media Literacy in Wales: a Critical Review of Industry and Education Policies. Cyfrwng. 4, pp.7-23. RAE2008

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It has been suggested that the less than optimal levels of students’ immersion language “persist in part because immersion teachers lack systematic approaches for integrating language into their content instruction” (Tedick, Christian and Fortune, 2011, p.7). I argue that our current lack of knowledge regarding what immersion teachers think, know and believe and what immersion teachers’ actual ‘lived’ experiences are in relation to form-focused instruction (FFI) prevents us from fully understanding the key issues at the core of experiential immersion pedagogy and form-focused integration. FFI refers to “any planned or incidental instructional activity that is intended to induce language learners to pay attention to linguistic form” (Ellis, 2001b, p.1). The central aim of this research study is to critically examine the perspectives and practices of Irish-medium immersion (IMI) teachers in relation to FFI. The study ‘taps’ into the lived experiences of three IMI teachers in three different IMI school contexts and explores FFI from a classroom-based, teacher-informed perspective. Philosophical underpinnings of the interpretive paradigm and critical hermeneutical principles inform and guide the study. A multi-case study approach was adopted and data was gathered through classroom observation, video-stimulated recall and semistructured interviews. Findings revealed that the journey of ‘becoming’ an IMI teacher is shaped by a vast array of intricate variables. IMI teacher identity, implicit theories, stated beliefs, educational biographies and experiences, IMI school cultures and contexts as well as teacher knowledge and competence impacted on IMI teachers’ FFI perspectives and practices. An IMI content teacher identity reflected the teachers’ priorities as shaped by pedagogical challenges and their educational backgrounds. While research participants had clearly defined instructional beliefs and goals, their roadmap of how to actually accomplish these goals was far from clear. IMI teachers described the multitude of choices and pedagogical dilemmas they faced in integrating FFI into experiential pedagogy. Significant gaps in IMI teachers’ declarative knowledge about and competence in the immersion language were also reported. This research study increases our understanding of the complexity of the processes underlying and shaping FFI pedagogy in IMI education. Innovative FFI opportunities for professional development across the continuum of teacher education are outlined, a comprehensive evaluation of IMI is called for and areas for further research are delineated.

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BACKGROUND & AIMS: Eosinophils are observed in several liver diseases, but their contribution in the pathogenesis of these disorders remains poorly investigated. Concanavalin A (Con A)-induced hepatitis is an experimental model of immune-mediated liver injury in which natural killer T (NKT) cells play a critical role through the production of interleukin (IL)-4 and the expression of Fas ligand (FasL). Because activated NKT cells also produce IL-5, a critical cytokine for eosinophil maturation and function, the role of IL-5 was investigated in this model. METHODS: IL-5-deficient mice, eosinophil depletion in wild-type (WT) mice, and NKT cell transfer from WT- or IL-5-deficient mice into NKT cell-deficient mice were used to assess the role of IL-5 and eosinophils. RESULTS: Liver eosinophil infiltrate and IL-5 production were observed after Con A challenge. Liver injury was dramatically reduced in IL-5-deficient or eosinophil-depleted mice. In addition, residual hepatitis observed in Fas-deficient mice was abolished after IL-5 neutralization. Finally, we showed that NKT cells constituted a critical source of IL-5. Indeed, transfer of WT NKT cells to mice lacking NKT cells restored liver injury, whereas transfer of IL-5-deficient NKT cells did not. CONCLUSIONS: These observations highlight the pathologic role of IL-5 and eosinophils in experimental immune-mediated hepatitis.

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BACKGROUND: Physical activity self-report instruments in the US have largely been developed for and validated in White samples. Despite calls to validate existing instruments in more diverse samples, relatively few instruments have been validated in US Blacks. Emerging evidence suggests that these instruments may have differential validity in Black populations. PURPOSE: This report reviews and evaluates the validity and reliability of self-reported measures of physical activity in Blacks and makes recommendations for future directions. METHODS: A systematic literature review was conducted to identify published reports with construct or criterion validity evaluated in samples that included Blacks. Studies that reported results separately for Blacks were examined. RESULTS: The review identified 10 instruments validated in nine manuscripts. Criterion validity correlations tended to be low to moderate. No study has compared the validity of multiple instruments in a single sample of Blacks. CONCLUSION: There is a need for efforts validating self-report physical activity instruments in Blacks, particularly those evaluating the relative validity of instruments in a single sample.

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Background: Acute febrile respiratory illnesses, including influenza, account for a large proportion of ambulatory care visits worldwide. In the developed world, these encounters commonly result in unwarranted antibiotic prescriptions; data from more resource-limited settings are lacking. The purpose of this study was to describe the epidemiology of influenza among outpatients in southern Sri Lanka and to determine if access to rapid influenza test results was associated with decreased antibiotic prescriptions.

Methods: In this pretest- posttest study, consecutive patients presenting from March 2013- April 2014 to the Outpatient Department of the largest tertiary care hospital in southern Sri Lanka were surveyed for influenza-like illness (ILI). Patients meeting World Health Organization criteria for ILI-- acute onset of fever ≥38.0°C and cough in the prior 7 days--were enrolled. Consenting patients were administered a structured questionnaire, physical examination, and nasal/nasopharyngeal sampling. Rapid influenza A/B testing (Veritor System, Becton Dickinson) was performed on all patients, but test results were only released to patients and clinicians during the second phase of the study (December 2013- April 2014).

Results: We enrolled 397 patients with ILI, with 217 (54.7%) adults ≥12 years and 188 (47.4%) females. A total of 179 (45.8%) tested positive for influenza by rapid testing, with April- July 2013 and September- November 2013 being the periods with the highest proportion of ILI due to influenza. A total of 310 (78.1%) patients with ILI received a prescription for an antibiotic from their outpatient provider. The proportion of patients prescribed antibiotics decreased from 81.4% in the first phase to 66.3% in the second phase (p=.005); among rapid influenza-positive patients, antibiotic prescriptions decreased from 83.7% in the first phase to 56.3% in the second phase (p=.001). On multivariable analysis, having a positive rapid influenza test available to clinicians was associated with decreased antibiotic use (OR 0.20, 95% CI 0.05- 0.82).

Conclusions: Influenza virus accounted for almost 50% of acute febrile respiratory illness in this study, but most patients were prescribed antibiotics. Providing rapid influenza test results to clinicians was associated with fewer antibiotic prescriptions, but overall prescription of antibiotics remained high. In this developing country setting, a multi-faceted approach that includes improved access to rapid diagnostic tests may help decrease antibiotic use and combat antimicrobial resistance.