Background/aim: Currently, the liver is cold-preserved at 0-4 ℃ for experimental and clinical purposes. Here, we investigated whether milder hypothermia during the initial phase of the preservation period was beneficial for liver viability upon reperfusion. Methods: In the first set of experiments, rat livers were preserved either conventionally in clinically used histidine-trypthopan-ketoglutarate (HTK) solution (Group A: 45 min and Group B: 24 h) or by slow cooling HTK solution (from 13 ℃ to 3 ℃) during the initial 45 min of preservation (Group C: 24 h). In the second set of experiments, additional groups of livers were evaluated: Group BB-preservation according to Group B and Group CC-preservation according to Group C. Further, some livers were preserved at 13 ℃ for 24 h. Livers were then reperfused using a blood-free perfusion model. Results: Bile production was approximately 2-fold greater in Group C compared to Group B. Alanine transaminase (ALT) and aspartate transaminase (AST) release into perfusate were 2-3-fold higher in Group B compared to Group C. No significant differences were found in ALT and AST release between Group C and Group A. Livers in Group CC compared to Group BB exhibited significantly lower portal resistance, greater oxygen consumption and bromosulfophthalein excretion into bile and lower lactate dehydrogenase (LDH) release into perfusate. Histological evaluation of tissue sections in Group BB showed parenchymal dystrophy of hepatocytes, while dystrophy ofhepatocytes was absent in Group CC. Livers preserved at 13 ℃ for 24 h exhibited severe ischemic injury Conclusion: These results suggest that the conventional way of liver preservation is not suitable at least for rat livers and that slow cooling of HTK solution during the initial phase of cold storage can improve liver viability during reperfusion. 相似文献
In the article, we present the construction of an index of economic and social condition of culture using datasets of Eurostat’s Cultural Statistics Pocketbooks from 2007 and 2011 and Eurostat’s COFOG data. The datasets allow us a broad perspective over a set of more than 200 variables in 12 domains for the EU-27 member states. Using high-dimensionally adjusted factor analysis (Metropolis–Hastings Robbins–Monro algorithm), we construct an index and determine a set of its several dimensions (as seen from the cultural statistics viewpoint). Using cluster analysis, we determine the general similarities and differences among the analysed countries and show several broadly different groupings that roughly, but not exclusively follow the divide speculated in some previous studies. The analysis therefore brings a novel and statistically developed tool to empirically follow the changes in the economic and social condition of culture from the viewpoint of cultural statistics, while the clustering of models has important consequences for empirical cultural policy and has to be verified in future studies. 相似文献
Mathematics teachers play a unique role as experts who provide opportunities for students to engage in the practices of the mathematics community. Proof is a tool essential to the practice of mathematics, and therefore, if teachers are to provide adequate opportunities for students to engage with this tool, they must be able to validate student arguments and provide feedback to students based on those validations. Prior research has demonstrated several weaknesses teachers have with respect to proof validation, but little research has investigated instructional sequences aimed to improve this skill. In this article, we present the results from the implementation of such an instructional sequence. A sample of 34 prospective secondary mathematics teachers (PSMTs) validated twelve mathematical arguments written by high school students. They provided a numeric score as well as a short paragraph of written feedback, indicating the strengths and weaknesses of each argument. The results provide insight into the errors to which PSMTs attend when validating mathematical arguments. In particular, PSMTs’ written feedback indicated that they were aware of the limitations of inductive argumentation. However, PSMTs had a superficial understanding of the “proof by contradiction” mode of argumentation, and their attendance to particular errors seemed to be mediated by the mode of argument representation (e.g., symbolic, verbal). We discuss implications of these findings for mathematics teacher education. 相似文献
Mobile banking (mBanking) enables customers to carry out their banking tasks via mobile devices. We advance the extant body of knowledge about mBanking adoption by proposing a model for understanding the importance and relationship between the user perception of mBanking, initial trust in mBanking services, and the fit between the technology and mBanking task characteristics. We synergistically combine the strengths of three IS theories – task technology fit (TTF) model, unified theory of acceptance and usage of technology (UTAUT), and initial trust model (ITM). The model was tested in a study conducted in Portugal, one of the European Union (EU) countries with the highest mobile phone adoption. Based on the sample of 194 individuals we applied partial least squares (PLS) to test the conceptual model propose. The path significance levels were estimated using the bootstrapping method (500 resamples). The study found that facilitating conditions and behavioral intentions directly influence mBanking adoption. Initial trust, performance expectancy, technology characteristics, and task technology fit have total effect on behavioral intention. The paper offers valuable insights to decision-makers involved in the implementation and deployment of mBanking services. For researchers, the paper highlights the usefulness of integrating TTF, UTAUT and ITM in the development of a decision support framework to study the adoption of new technologies. 相似文献
International Journal for Educational and Vocational Guidance - The study examines the effectiveness of a career intervention in middle schools. The intervention was organized in eight... 相似文献
For the present development of teacher training system in Slovenia (Yugoslavia) two trends are characteristic: the prolongation of studies for elementary school teachers (grades 1‐8) from two to four years and an institutional shift of responsibility for subject teacher training from ‘mono‐technical’ (pedagogical academies) to ‘polytechnical’ institutions (different faculties or departments of the universities).
These trends are having important implications for the scope of practical training and its relationship to other parts of the studies. Traditional forms of practical training that had developed at pedagogical academies are being discontinued but the new ones are not yet firmly established.
The existing forms of practical training of student teachers are briefly described (exercises in general professional courses, exercises in classroom observation, teaching attempts and block practice). In addition, the role of teachers of special didactics and the role of practice teachers is analysed.
The pragmatic character of practical training has to be overcome on the basis of systematic attempts to confront students’ subjective theories on teaching and learning, based on experience, with scientific theories throughout the process of their training.
An important prerequisite for the necessary integration of different components of study and especially of theory and practice is cooperation between university teachers of academic, general professional subjects and special didactics. How do we achieve such a cooperation and overcome the negative attitude of teachers of academic subjects toward professional and practical training of students? This remains one of the open problems in the reform of teacher training in Slovenia. 相似文献