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Cell Size and Scale Some cells are visible to the unaided eye The smallest objects that the unaided human eye can see are about 0.1 mm long. That means that under the right conditions, you might be able to see an ameoba proteus, a human egg, and a paramecium without using magnification. spectre d'absorption INTRODUCTIONChaque année, en cette période et sous nos latitudes, certains arbres se parent de couleurs chatoyantes. Dans un premier temps, nous tâcherons de répondre à la question: Qu'est-ce qu'une feuille? Puis, nous nous intéresserons à la couleur de la feuille. Ensuite, on cherchera à expliquer son changement de couleur au fil des saisons. L'algorithme qui fait avancer la biologie L'algorithme qui fait avancer la biologie - 1 Photo Vous êtes biologiste et vous voulez savoir quel est le degré de parenté et l'histoire évolutive entre les différentes espèces de levures (ou de vers, ou d'insectes, ou d'oiseaux) que vous êtes en train d'étudier. La méthode la plus fiable, celle qui ne vous induira pas en erreur par des ressemblances morphologiques superficielles, c'est la phylogénie moléculaire : comparer le génome de vos bestioles. Pour ce faire, vous disposez désormais de banques de données regroupant des millions de séquences d'ADN correspondant à des dizaines de milliers d'espèces vivantes. Mais, sans outils adaptés pour les comparer, elles resteront une suite muette de A, T, C et G. C'est là qu'interviennent Olivier Gascuel et Stéphane Guindon, chercheurs au Laboratoire d'informatique, de robotique et de microélectronique de Montpellier (Lirmm).

Biomedical Beat: May 20, 2009 - National Institute of General Me IN THIS ISSUE . . . May 20, 2009 Check out the Biomedical Beat Cool Image Gallery. Got research news to share? E-mail us at - Old Time Radio Shows Learn Biology Online For Free with our Huge Collection of Open Courses If you’ve always been interested to learn more about nature and the diversity of life, you can now Learn Biology Online for Free! Free Biology courses are easy to find yet some of the ones you find may not be worth your time. We’ve put together a list of Biology courses from well-respected institutions such as John Hopkins, Yale, MIT, Stanford, and UCLA. Hopefully, this free resources will help you advance your knowledge of Biology towards a career in education, medicine, research, and agriculture. MOOCs are Massive Open Online Courses. They are university courses that have been put online, often with enhanced functionality such as Lecture Notes, mini-quizzes and other special features.

Phase photochimique et phase « obscure » - [la cordonnerie] Spectres d’absorption des pigments photosensibles. spectre des xanthophylles et du carotène spectre des 2 chlorophylles spectre du lycopène (pigment rouge de la tomate Ces figures viennent d’ici. Tree of Life Web Project The Tree of Life Web Project (ToL) is a collaborative effort of biologists and nature enthusiasts from around the world. On more than 10,000 World Wide Web pages, the project provides information about biodiversity, the characteristics of different groups of organisms, and their evolutionary history (phylogeny). Each page contains information about a particular group, e.g., salamanders, segmented worms, phlox flowers, tyrannosaurs, euglenids, Heliconius butterflies, club fungi, or the vampire squid. ToL pages are linked one to another hierarchically, in the form of the evolutionary tree of life. Starting with the root of all Life on Earth and moving out along diverging branches to individual species, the structure of the ToL project thus illustrates the genetic connections between all living things.

Fire and Water on a Hot, Turbulent Planet - Dot Earth Blog The Earth Observatory Web site of NASA is a vital portal, not only providing data that help scientists clarify global conditions and trends but also reminding people, once in awhile, of the special nature of this pale blue (and green) dot. Today’s images show the scope of two unfolding disasters — involving excessive fire and water — related to extreme climate conditions that are projected to become more frequent in a heating world. The fires sweeping parched, baked peat bogs and forests in western Russia have raised a vast smoke pall captured by NASA satellites. (See similar images of Canada’s smoke pall to get a sense of the severity of the Russian blazes.) At the same time, NASA has posted images of the Indus River valley in Pakistan vividly showing the scope of severe flooding, the worst in 70 years, that has displaced several million people.

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