3.3 The projective plane We now consider one of the most important non-orientable surfaces – the projective plane (sometimes called the real projective plane). In Section 2 we introduced it as the surface obtained from a rectangle by identifying each pair of opposite edges in opposite directions, as shown in
3.2.1 Remarks By ‘contains’, we mean that we can find part of the surface that is homeomorphic to a Möbius band. The edge of the Möbius band does not need to correspond to an edge at the surface, so that a surface without boundary can be non-orientable (as we shall shortly see). When seeking Möbius bands in a surface, it can be helpful to look at all possible closed curves on the surface and thicken these into bands. Remember, fro
3.2 Orientability The idea of orientability is another fundamental concept that we need for the study of surfaces. To illustrate the underlying idea, we consider two familiar surfaces – a cylinder and a Möbius band. We can distinguish between a cylinder and a Möbius band by noticing that every cylinder has an ‘inside’ and an ‘outside’, as shown in Author(s):
3.1.1 Inserting half-twists We can insert half-twists into a paper surface whenever a piece of the surface is homeomorphic to a rectangle ABCD with the following properties: the edges AB and CD of the rectangle map to distinct parts of the boundary of the surface, and the edges BC and DA of the rectangle map to non-boundary points of the surface. As illustrated in Author(s):
3.1 Surfaces with twists In Section 3 we study the orientability of surfaces from an informal point of view. In particular, we take a detailed look at the projective plane and its properties. We start by examining some surfaces that resemble a Möbius band. A cylinder or a Möbius band can be formed by gluing together the ends of a rectangular strip or band of paper either with or without twisting the paper before gluing. Does adding further twists to the band before gluing provide any more examples of surfaces
Animals at the extremes: The desert environment
Animal life has adapted to survive in the most unlikely and inhospitable habitats. This unit looks at the surprisingly diverse desert climates throughout the world and mammals, birds, lizards and amphibians that survive there. It splits these animals into three groups according to their strategy for survival: evaders, evaporators and endurers, then discusses how these strategies work on a biochemical and physiological level.Author(s):
Understanding the environment: Flows and feedback
There is increasing recognition that the reductionist mindset that is currently dominating society, rooted in unlimited economic growth unperceptive to its social and environmental impact, cannot resolve the converging environmental, social and economic crises we now face. The primary aim of this unit is to encourage the shift away from reductionist and human centred thinking towards a holistic and ecological worldview.Author(s):
Design
This unit looks at the process of design – from assessing the complexity of design as an activity, to exposing the difficulty in making general conclusions about how designers work. You will be able to identify innovation in a wide variety of designed objects and evaluate the impact of this innovation. First published on Wed, 27
Potable water treatment
Without it we are dead! Water is essential, but what processes must it go through to become fit for human consumption? This unit will guide you through the continuous cycling of water between land, open water surfaces and the sea before moving on to an overview of the water treatment and supply process. First published on Fri, 29 Ju
Testing
Kyle Xu
In this module, we show the testing results and compare those of different algorithm.
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Darwin Now Awards
Janice Ansine is a recipient of a Darwin Now Award. She is currently working on a variety of projects in Jamaica, looking at contemporary responses to Darwin and Into the historic role of Jamaica in providing material for his research.
"DMC Upside": GIS Day
Del Mar College, Texas A&M University-Corpus Christi, Texas A&M University-Kingsville and the National Geospatial Technology Center of Excellence at Del Mar College hosted "Discovering the World Through GIS" on Nov. 15, 2012. The local event is part of the National Geographic Society's Geography Awareness Week (Nov. 12-18), which includes GIS Day.
This segment of the "DMC Upside" television program was featured in the December 2012 edition, which airs on cable channel 19 in Corpus Christi. The
"DMC Upside:" Military Friendly School designation
Del Mar College was named a "Friendly Military School" for the "2013 Guide To Military Friendly Schools" by G.I. Jobs magazine. The honor puts Del Mar in the top 20 percent of all schools nationwide in serving U.S. military veterans through higher education.
This segment of the "DMC Upside" television program was featured in the December 2012 edition, which airs on cable channel 19 in Corpus Christi. The "DMC Upside" is produced by DMC TV.
"DMC Upside:" Project Del Mar Fall 2012
Fifteen Del Mar College students in the Drama program's make-up class put into practice the skills and techniques they've learned during the fall 2012 semester and presented their best work as part of Project Del Mar's "The Phenomenal Land of Fantastical Fantasies."
This segment of the "DMC Upside" television program was featured in the December 2012 edition, which airs on cable channel 19 in Corpus Christi. The "DMC Upside" is produced by DMC TV.
Why Are Scientists Most Like Children?
Children are naturally curious about the world around them. They
experiment, explore, and discover without even thinking about it. Nobel
Prize winning physicist William Phillips reaches out to the children of
today as the scientists of tomorrow. (01:12)
UMMC Physician Profile: Anna B. Fishbein, M.D.
This short video introduces viewers to Anna B. Fishbein, M.D., assistant professor of pediatrics at the University of Maryland School of Medicine, and an allergy and immunology attending at the University of Maryland Medical Center.
Dr. Fishbein's special interests include, food allergy, asthma research, and allergic rhinitis. Watch this video to learn more about her practice at UMMC.
Related Links:
University of Maryland Children's Hospital
http://www.umm.edu/pediatrics/
Division of Pediatr
Visualizing Political Struggle in the Middle East [Audio]
Speaker(s): Lina Khatib | Marking the publication of Lina Khatib's latest book Image Politics in the Middle East: The Role of the Visual in Political Struggle, this lecture focuses on the evolution of political expression and activism in the Middle East over the past decade, highlighting the visual dimension of power struggles between citizens and leaders in Arab countries undergoing transition.Lina Khatib is the co-founding head of the Program on Arab Reform and Democracy at Stanford University
Deterioration of Structural Connectivity in the Aging Brain David Salat, recorded 12/5/12
NASA | The Evaporative Stress Index
The Evaporative Stress Index (ESI) provides objective, high-resolution information about the evaporation of water from land surface. The ESI model combines satellite data with other meteorological factors to determine how much water is used by crops and vegetation. The resulting data helps to detect drought. The kind of early-warning detection system ESI provides will enhance the US arsenal of drought monitoring tools and help farmers adapt to drought before it evolves.
Great cybersafety site from the FBI for Teachers & Students
With school back in session, one topic that’s on many class curriculums around the nation is cyber safety. After all, it’s a hyper-connected world—with texting, social networking, e-mail, online gaming, chat, music downloading, web surfing, and other forms of wired
