The test material (solid or liquid) is applied uniformly and topically to a three-dimensional human skin model, comprising at least a reconstructed epidermis with a functional stratum corneum. Two tissue replicates are used for each treatment (exposure time), and for controls. Corrosive materials are identified by their ability to produce a decrease in cell viability below defined threshold levels at specified exposure periods. The principle of the human skin model assay is based on the hypothesis that corrosive chemicals are able to penetrate the stratum corneum by diffusion or erosion, and are cytotoxic to the underlying cell layers.
The test method utilizes an artificial membrane designed to respond to corrosive substances in a manner similar to animal skin in situ. The in vitro membrane barrier test method may be used to test solids, liquids (aqueous substances with a pH in the range of 4.5 to 8.5 often do not qualify for testing) and emulsions. The test described in this Test Guideline allows the identification of corrosive chemical substances and mixtures and allows the subcategorisation of corrosive substances as permitted in the GHS. This classification is based on the substance penetration time through the membrane barrier. The test system is composed of two components, a synthetic macromolecular bio-barrier and a Chemical Detection System (which one detect the test substance). An appropriate number of replicates is prepared for each test substance and its corresponding controls. The times of applying the test substance to the membrane barrier are recorded and staggered. The time (in minutes) elapsed between application of the test substance to the membrane barrier and barrier penetration is used to predict the corrosivity of the test substance.
The test material (solid or liquid) is applied uniformly and topically to a three-dimensional human skin model, comprising at least a reconstructed epidermis with a functional stratum corneum. Two tissue replicates are used for each treatment (exposure time), and for controls. Corrosive materials are identified by their ability to produce a decrease in cell viability below defined threshold levels at specified exposure periods. Coloured chemicals can also be tested by used of an HPLC procedure. The principle of the human skin model assay is based on the hypothesis that corrosive chemicals are able to penetrate the stratum corneum by diffusion or erosion, and are cytotoxic to the underlying cell layers.
Groups of animals, of a single sex, are exposed via the dermal route to the test chemical in a stepwise procedure using the appropriate fixed doses. The initial dose level is selected at the concentration expected to produce clear signs of toxicity without causing severe toxic effects or mortality. Further groups of animals may be tested at higher or lower fixed doses, depending on the presence or absence of signs of toxicity or mortality. This procedure continues until the dose causing toxicity or no more than one death is identified, or when no effects are seen at the highest dose or when deaths occur at the lowest dose. Subsequently, observations of effects and deaths are made. Animals which die during the test are necropsied, and at the conclusion of the test the surviving animals are sacrificed and necropsied.
The method provides information on the hazardous properties and allows the substance to be classified for acute toxicity according to the Globally Harmonised System of classification and labelling of chemicals.
Groups of at least 5 male and 5 female rodents are exposed 6 hours per day for 28 days to a) the test chemical at three or more concentration levels, b) filtered air (negative control), and/or c) the vehicle (vehicle control). Animals are generally exposed 5 days per week but exposure for 7 days per week is also allowed. Males and females are always tested, but they may be exposed at different concentration levels if it is known that one sex is more susceptible to a given test article. This guideline allows the study director the flexibility to include satellite (reversibility) groups, bronchoalveolar lavage (BAL), lung burden (LB) for particles, neurologic tests, and additional clinical pathology and histopathological evaluations in order to better characterize the toxicity of a test chemical.
Suspensions of bacterial cells are exposed to the test substance (liquid or solid) in the presence and in the absence of an exogenous metabolic activation system. At least five different analysable concentrations of the test substance should be used. The recommended maximum test concentration for soluble non-cytotoxic substances is 5 mg/plate or 5 ml/plate. There are two methods: the plate incorporation method and the preincubation method. For both techniques, after two or three days of incubation at 37°C, revertant colonies are counted and compared to the number of spontaneous revertant colonies on solvent control plates.
The test substance is administered daily, generally orally, to mated females (rats are preferred) from the time of implantation (GD 6) throughout lactation (PND 21). At least three dose levels and a concurrent control should be used and a total of 20 litters are recommended at each dose level. Dams are tested to assess effects in pregnant and lactating females and may also provide comparative information. Offspring are randomly selected from within litters for neurotoxicity evaluation. All dams and all offspring should be carefully observed at least once daily with respect to their health condition, including morbidity and mortality. The evaluation consists of observations to detect gross neurologic and behavioural abnormalities, and the evaluation of brain weights and neuropathology during postnatal development and adulthood. The report should include the body weight, the food/water consumption; the detailed clinical observations, the necropsy findings, a detailed description of all behavioural, the number of animals at the start and at the end of the study and the toxic response data by sex and dose level.
This analysis has been carried out in an effort to link PISA results to curricular programmes and structures in participating countries and economies. Results from the student assessment reflect differences in country performance in terms of the test questions. These findings are important for curriculum planners, policy makers and in particular teachers – especially mathematics teachers of intermediate and lower secondary school classes.
The report offers a comprehensive overview of the rapidly changing phenomenon of Open Educational Resources and the challenges it poses for higher education. It examines reasons for individuals and institutions to share resources for free, and looks at copyright issues, sustainability and business models as well as policy implications. It will be of particular interest to those involved in e-learning or strategic decision making within higher education, to researchers and to students of new technologies.
PISA Computer-Based Assessment of Student Skills in Science describes how the 2006 survey was administered, presents 15-year-olds’ achievement scores in science and explains the impact of information communication technologies on both males’ and females’ science skills. While males outperformed females on the computer-based test in all three countries, females in Iceland and males in Denmark performed better than their counterparts on the paper-and-pencil test. The evidence shows that, overall, males are more confident and use computers more frequently. While females tend to use the Internet more for social networking activities, males tend to browse the Internet, play games and download software.
Readers will also learn how students reacted to the electronic questionnaire and how it compared with pencil-and-paper tests. In general, there were no group differences across test methods buts students enjoyed the computer-based test more than the paper-and-pencil test.
Data are provided for all OECD member countries (including area totals), and for Brazil, China, India, Indonesia, the Russian Federation and South Africa. For each indicator, there is a two-page spread: a text page includes a short introduction followed by a detailed definition of the indicator, comments on comparability of the data, an assessment of long-term trends related to the indicator and a list of references for further information on the indicator; the second page contains a table and a graph providing, at a glance, the key message conveyed by the data. Each indicator includes "StatLinks" which allow readers to download the corresponding data.
OECD Countries covered include Australia, Austria, Belgium, Canada, Chile,Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Israel, Italy, Japan, Korea, Luxembourg, Mexico, Netherlands, New Zealand, Poland, Portugal, Slovak Republic, Slovenia, Spain, Sweden, Switzerland, Turkey, the United Kingdom, and the United States. Non-OECD countries covered include Brazil, China, India, Indonesia, Russia, and South Africa.
Topics covered include population and migration; production and productivity; household income, wealth and debt; globalisation, trade and foreign direct investment (FDI); prices, interest rates and exchange rates; energy and transportation; labour, employment and unemployment; science and technology including research and development (R&D) and the Information and Communications Technology (ICT) sector; environment including natural resoures, water,and air and climate; education resources and outcomes; government expenditures, debt, revenues, taxes, agricultural support and foreign aid; and health status, risk and resources.
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This new publication is a product of the OECD-Eurostat Entrepreneurship Indicators Programme, which is a long-term programme of internationally-comparable policy-relevant entrepreneurship statistics. The work involves developing standard definitions and concepts and engaging countries and international Agencies in the collection of data. An international group of statisticians and analysts provides guidance to the Programme that benefits from sponsorship by the Ewing Marion Kauffman Foundation in the United States.
This study shows that success requires not some silver bullet, but a range of complementary factors that support the innovation-intensive growth exemplified by new information and communication technologies such as the Internet and Internet applications like electronic commerce. Supportive policies include those favourable to innovative start-ups and to financial systems able to support them, those that facilitate the reorganisation required to reap the full benefits of ICT, regulatory and institutional frameworks that facilitate links between science and industry, and efforts to train and obtain the necessary human capital, as well as public support for basic scientific research. While this study is far from exhaustive, it represents an important step in understanding the conditions under which economies flourish.
This report offers policy insights and stimulates new research to complement and further develop the recent OECD Teaching and Learning International Survey (TALIS) and the upcoming PISA 2012 assessment, which will again focus on mathematics. In addition, this report may be of interest to teachers, educators and officials within national and local educational authorities responsible for the professional development of teachers or for programme development, as well as members of school boards and parent advisory bodies.
The OECD’s 2nd World Forum on Statistics, Knowledge and Policy 'Measuring and Fostering the Progress of Societies' held in Istanbul in June 2007 brought together a diverse group of leaders from more than 130 countries to debate these issues. These proceedings contain 40 papers presented at the Forum.