La Medusa by Caravaggio: characterisation of the painting technique and evaluation of the state of conservation     

Monica Favaro  Pietro A. Vigato  Alessia Andreotti  Maria Perla Colombini 《Journal of Cultural Heritage》2005,6(4):295-305

The oil painting “La Medusa” executed by Caravaggio at the end of the XVI century on a wooden shield, was investigated by integrated physical–chemical and analytical methodologies in order to obtain scientific data capable of elucidating the state of conservation and the painting technique. Optical (OM) and electronic (SEM-EDS) microscopy, micro-FT-IR spectroscopy, gas chromatography–mass spectrometry (GC–MS) and pyrolysis GC–MS were applied on two microfragments and some organic samples obtained by solvent extraction using the swab cleaning technique. The obtained results indicated that Caravaggio probably reused an old shield as a previous gypsum preparation layer has been detected under the original painting layers. He used white lead, natural earths, verdigris and lead–tin yellow type I mixed with drying oils to paint. The considerable amount of amorphous particles of copper chlorides found in the green pigment verdigris suggests that it could have been produced according to the ancient recipe of verde salsum described by Theophilus. Mordant gilding has been identified on the upper part of the shield that can be related to an abandoned experiment to give the painting a mirror-like reflecting effect. Three different varnishes layers have been detected above the painted surface. The original and restoration varnishes have been identified and they contain a mixture of drying oil, mastic and turpentine and some beeswax. Cleaning tests, performed with different organic solvents, suggest the use of isopropyl alcohol as cleaning agent because it is less efficient in comparison to others solvents; thus it ensures a careful and controlled removal of the varnishes.  相似文献   

Just when you thought it was safe: synthetic phonics and syncretic literacy practices     

Andrey Rosowsky 《English in Education》2005,39(3):32-46

Until just recently one might have been forgiven for considering the ‘Reading’ debate to have been amicably resolved, with, at the end of the twentieth century, a negotiated consensus reached comprised of all sides in the debate agreeing on a balanced approach to the teaching of initial reading. However, the recent intervention of the House of Commons Education and Skills Committee with its report, Teaching Children to Read, and its advocacy of synthetic phonics, has once again brought the teaching of reading in UK schools to public attention. This paper seeks to provide an interesting comparative example of a UK literacy context where synthetic phonics is employed regularly and systematically. Thousands of British schoolchildren attend mosque schools on a daily basis where they learn how to read the Classical Arabic of the Qur'an. They are taught how to decode the text accurately and fluently using synthetic phonics methods. This literacy practice is described and suggestions are made about what it might have to contribute to the discussion around the adoption of synthetic phonics in mainstream schools  相似文献   

探究式教学法在《有机化学》教学中的应用   总被引：1，自引：0，他引：1  

陈甡  刘平 《中国科技信息》2012,(11):221-222

阐述了有机化学的教学现状及探究式教学的实质,强调了在有机化学教学中应用探究式教学的必要性,并列举实施探究式教学的程序及实施实例。  相似文献   

高校教师考评的模糊综合评判     

赵力 《温州职业技术学院学报》2010,10(3):79-81

为使教学管理者对教师能够进行客观公正的评价,构建基于模糊综合评判的高校教师评价体系,使教学管理者对教师进行客观公正评价的同时,还能分析教师教学中存在的不足,为今后的工作改进指明方向。  相似文献   

黄色七彩菊花色素的提取及其稳定性研究     

管春平  杨平 《楚雄师专学报》2013,(9):53-57

以黄色七彩菊花作材料,对其花色素提取条件及理化性质进行研究。以蒸馏水作为提取剂,在单因素实验基础上,通过正交实验优化了色素提取温度、料液比、提取时间,优化提取条件为：温度80℃,料液比1：11．1（g／mL）,提取时间30min。理化性质表明：不同温度、pH值对色素颜色有较大影响,色素的光稳定性及抗氧化性能力较差,色素具有一定的热稳定性和抗还原性能力;Na^＋、K^＋、Ca^2＋、Al^3＋四种离子对色素稳定性影响较小,Cu^2＋、Fe^3＋对色素影响较大。  相似文献   

Social Learning among Organic Farmers and the Application of the Communities of Practice Framework     

Selyf Lloyd Morgan 《The Journal of Agricultural Education and Extension》2013,19(1):99-112

ABSTRACT

The paper examines social learning processes among organic farmers and explores the application of the Community of Practice (CoP) model in this context. The analysis employed utilises an approach based on the CoP model, and considers how, or whether, this approach may be useful to understand social learning among farmers. The CoP model is applied to case studies of social learning fora among organic farmers. The case studies are compiled from in-depth semi-structured interviews and participant observation with farmers and other actors, and the data are analysed with reference to three dimensions of the CoP model, namely mutual engagement, joint enterprise and shared repertoires. Farmers associate and engage in social learning more readily with peers determined by similar attitudes to farm business, farming styles and understanding of what organic agriculture entails. Such associations support the hypothesis that CoPs are self-organising structures that generate their knowledge in sympathy with community definition and identity. A CoP framework applied within relatively unstructured and dispersed communities, such as described in this paper, emphasises the fluid nature of CoPs, and their essentially self-organising nature. Extension approaches may be facilitated by regarding farmers as de-facto members of CoPs and by understanding how CoPs may form and develop. The CoP model is applied as a heuristic to examine social learning processes in organic farming.  相似文献   

Open-ended Cases in Agroecology: Farming and Food Systems in the Nordic Region and the US Midwest     

Charles Francis  James King  Geir Lieblein  Tor Arvid Breland  Lennart Salomonsson  Nadarajah Sriskandarajah 《The Journal of Agricultural Education and Extension》2013,19(4):385-400

Abstract

Our aim is to describe open-ended case studies for learning real-life problem solving skills, and relate this approach to conventional, closed-ended decision case studies. Teaching methods are open-ended cases in agroecology, an alternative to traditional strategies that lead students through prepared materials and structured discussions to determine an outcome already known to the instructor. Our method promotes a culture of curiosity. Multiple evaluation criteria show how this learning strategy provides students with practice in researching, envisioning and designing potential scenarios for clients in the field. In agroecology case studies, students and instructors are co-learners in a discovery process that includes gathering information from key clients, interviewing major stakeholders, and building an understanding of the current context of the local farming and food systems. Two agroecology courses in Norway, a field course in the US Midwest, and an experimental course in Sweden and Vietnam illustrate this learning strategy. Student evaluations of learning have been highly positive, and skills and methods from courses have been applied in their thesis projects and professional careers.

Practical results reveal that students are well prepared for an uncertain, complex, multi-dimensional and dynamic future, have the capacity to develop alternative future scenarios, and have practiced methods to evaluate options based on production, economic, environmental and social criteria and impacts. This innovative strategy is offered as a complement or alternative to conventional decision case studies and evaluated as an approach to experiential learning, an important and effective method for adult learners.  相似文献   

以实验为主导的高职有机化学教学模式的探索与实践     

李云霞  张秋霞  盛贻林 《金华职业技术学院学报》2013,13(3):29-32

基于有机化学课程目前的教学现状。针对高职学生特点,提出了以“实验为主导”的教学模式替代传统教学模式的改革试验。即同样的知识内容通过实验、实训来开展,理论与实践教学基本同步,实现课堂教学“理实一体化”。教学实践证实,该种教学模式更符合高职教育的特点和规律,能充分调动学生学习积极性和主动性,在对照的几个班级教学中取得明显的效果。  相似文献   

汽车行业职业经理人胜任特征评价模型研究     

吴梦颖  莫良元 《重庆职业技术学院学报》2013,(5):27-30

根据胜任力理论,通过问卷调查及因子分析法建立了包括职业技能、行政技能、创新技能、道德素养和知识阅历5个一级指标及16个二级指标的评价体系,采用专家问卷法、层次分析法和模糊综合评判法计算出两级影响因子权重,构建了汽车行业职业经理人胜任特征评价模型,并通过案例说明该模型的可行性和实用性.  相似文献   

基于邻接矩阵存储结构的二元关系的合成运算     

达文姣  郭珍  任志国  石旺峰 《甘肃高师学报》2013,(5):10-11

关系的应用非常广泛.在数学领域对关系的研究主要集中在关系的性质上,很少有人研究关系的存储结构和算法.本文主要论述了二元关系的邻接矩阵存储结构和在此结构之上的关系的创建和合成运算.并利用C语言实现了该算法.最后分析了算法的复杂性.  相似文献