Low magnification SEM image of open cell polyurethane foam
If a gas is injected into a liquid it forms a cellular foam structure. When a thermoset prepolymer of low viscosity is foamed, the polymer can drain from the cell walls (driven by surface tension) before it sets at the cell edges, leaving an open-celled foam. The cell edges have three concave sides, giving rise to the tri-cuspid cross section visible at the bottom of this image. The average co-ordination number for the nodes (where struts meet) is four, giving tetrahedral junctions.
Author(s): DoITPoMS, University of Cambridge,Dr J A Elliott,

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3.6 Different paradigms and different methods

These different methods alert us to the fact that psychology is not just one enterprise, but a series of interlocking enterprises in which psychologists have different views about the best ways to try to understand or explain people and their behaviour and experience. These are arguments about epistemology; that is, what questions to ask, what sort of evidence to look for, what sort of criteria to use to evaluate explanations, and what sort of methods to use.

All knowledge and al
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References

Institute of Fundraising (2006) The Good Fundraising Guide: Where to start… London [online], Institute of Fundraising, http://www.institute-of-fundraising.org.uk/documents/good_fundraising_guide.pdf (Accessed 20 April 2007).
Lloyd, T. (2006) Cultural Giving, London, Directory of Social Change.
Mellor, P. (1983) ‘Advertising for legacy income’ in Norton, M.
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7.8 Summary of Section 7

This section has sought to illustrate the formation of connections between neurons and their targets by exploring a few examples. The picture that emerges is one of cells at different stages of development subjected to a vast array of signals. These signals are the medium through which environmental factors exert their effects. To some of these signals, some cells respond; to other signals, other cells respond. What a cell, a neuroblast, a growth cone actually does is dependent on the combina
Author(s): The Open University

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Veterans History Project Congressional Staff Briefing
Staff of the Veterans History Project make their annual briefing to Congressional staff. Speakers included Betsy Peterson, Bob Patrick, Patrick Burns, Florence Champagne, Lloyd Lenhart and Lisa Taylor. For transcript, captions, and more information, visit http://www.loc.gov/today/cyberlc/feature_wdesc.php?rec=6324
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Introduction

Both vitamins and minerals are essential in the diet in small quantities.The term ‘vitamin’ was not coined until early in the 20th century, to describe those chemicals in food without which a pattern of deficiency symptoms (often called a deficiency syndrome) occurs. Minerals, also called mineral elements, are those elements other than carbon, hydrogen, oxygen and nitrogen that are found in the body.

This free course, Nutrition: Vitamins and minerals, looks at the two main gr
Author(s): The Open University

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1.6 Summary

You may find it useful to go over the main points of the first section again.

  1. We in the West generally recognise two different concepts of musical creation, namely composition and improvisation. Composition is widely characterised as a relatively lengthy process involving the use of notation; improvisation involves the spontaneous generation of music without notation. The distinction can be useful when applied to our own art music tradition.


  2. Author(s): The Open University

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Introduction

This course looks at three different uses of genetic testing: pre-natal diagnosis, childhood testing and adult testing. Such tests provide genetic information in the form of a predictive diagnosis, and as such are described as predictive tests. Pre-natal diagnosis uses techniques such as amniocentesis to test fetuses in the womb. For example, it is commonly offered to women over 35 to test for Down's syndrome. Childhood testing involves testing children for genetic diseases that may no
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RVC 27 - Pathogen Evasion of The Immune System and Animal Disease
In the latest RVC podcast, Professor Dirk Werling describes the importance of the Innate Immune System in combating infection by micro-organisms and the tactics that some of these bugs use to evade these defences, with particular reference to his work on immune cell receptors in cattle.
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7.340 Avoiding Genomic Instability: DNA Replication, the Cell Cycle, and Cancer (MIT)
In this class we will learn about how the process of DNA replication is regulated throughout the cell cycle and what happens when DNA replication goes awry. How does the cell know when and where to begin replicating its DNA? How does a cell prevent its DNA from being replicated more than once? How does damaged DNA cause the cell to arrest DNA replication until that damage has been repaired? And how is the duplication of the genome coordinated with other essential processes? We will examine both
Author(s): Randell, John,Tanny, Robyn

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9.913-A Intensive Neuroanatomy (MIT)
The course will start with an overview of the central and peripheral nervous systems (CNS and PNS), the development of their structure and major divisions. The major functional components of the CNS will then be reviewed individually. Topography, functional distribution of nerve cell bodies, ascending and descending tracts in the spinal cord. Brainstem organization and functional components, including cranial nerve nuclei, ascending / descending pathways, amine-containing cells, structure and in
Author(s): Nedivi, Elly

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20.462J Molecular Principles of Biomaterials (MIT)
This course covers the analysis and design at a molecular scale of materials used in contact with biological systems, including biotechnology and biomedical engineering. Topics include molecular interactions between bio- and synthetic molecules and surfaces; design, synthesis, and processing approaches for materials that control cell functions; and application of state-of-the-art materials science to problems in tissue engineering, drug delivery, vaccines, and cell-guiding surfaces.
Author(s): Irvine, Darrell

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22.55J Principles of Radiation Interactions (MIT)
The central theme of this course is the interaction of radiation with biological material. The course is intended to provide a broad understanding of how different types of radiation deposit energy, including the creation and behavior of secondary radiations; of how radiation affects cells and why the different types of radiation have very different biological effects. Topics will include: the effects of radiation on biological systems including DNA damage; in vitro cell survival models; and in
Author(s): Coderre, Jeffrey

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Introduction

Motion is vital to life, and to science. In many ways it was the investigation of motion, initiated by Galileo Galilei in the late sixteenth century, and brought to a head by Isaac Newton in the seventeenth, that inaugurated the modern era of physics. Progress since that time has been so great that describing motion is now regarded as a fundamental part of science rather than one of its frontiers. Nonetheless, the description of motion played a central role in Einstein's formulation of the sp
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9.011 The Brain and Cognitive Sciences I (MIT)
Survey of principles underlying the structure and function of the nervous system, integrating molecular, cellular, and systems approaches. Topics: development of the nervous system and its connections, cell biology or neurons, neurotransmitters and synaptic transmission, sensory systems of the brain, the neuro-endocrine system, the motor system, higher cortical functions, behavioral and cellular analyses of learning and memory. First half of an intensive two-term survey of brain and behavioral s
Author(s): Miller, Earl,Brown, M. Christian,Wilson, Matt,Schi

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8 Water and its impurities

Water must be of a certain quality to be suitable for human consumption. No natural water found on Earth is pure; any sample of water contains more than just water molecules. Some materials, such as sodium nitrate, are very soluble and dissolve in water in large quantities, whereas other materials are much less soluble. This is just as well, otherwise rain would dissolve all the rocks and they would end up in the oceans!

Drinking water must not contain harmful materials, which means bot
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Cory Doctorow on Why it's a Bad Idea to Regulate Computers
Big Ideas presents Cory Doctorow on Why it's a Bad Idea to Regulate Computers the Way We Regulate Radios, Guns, Uranium and Other Special-Purpose Tools
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Male Giant Panda Bear Dust Bathing
This short video gives excellent real life footage of a male Giant Panda dust bathing. This is a great resource to help build background knowledge and to help make real world connections between nature and the classroom. (Less Than 2 Minutes)
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πού είναι ο άρης (2)π,ι,πι σελ.11

http://taksiasterati.blogspot.gr/

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SteveSongs 5 Smiles Song
This song from SteveSongs uses changing a frown into a smile to practice counting, basic addition, and subtraction skills.  Scenes are shot in a playground.  (1:41)
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