SEMCIÊNCIA

The Death of Nemesis: The Sun's Distant, Dark Companion Posted:  11 Jul 2010 09:10 PM PDT The data that once suggested the Sun is orbited by a distant dark companion now raises even more questions Over the last 500 million years or so, life on Earth has been threatened on many occasions; the fossil record is littered with extinction events. What's curious about these events is that they seem to occur with alarming regularity. The periodicity is a matter of some controversy among paleobiologists but there is a growing consensus that something of enormous destructive power happens every 26 or 27 million years. The question is what? In this blog, we've looked at various ideas such as the Sun's passage through the various spiral arms of the Milky Way galaxy (it turns out that this can't explain the extinctions because the motion doesn't have had the right periodicity). But another idea first put forward in the 1980s is that the Sun has a distant dark companion calle

Estudo: vagalumes sincronizam luzes para conquistar fêmeas 08 de julho de 2010 • 16h50 comentários 1 Notícia Cientistas afirmam que vagalumes sincronizam suas piscadas para que fêmea não confunda as espécies Foto: Getty Images Reduzir Normal Aumentar Imprimir Um novo estudo da universidade de Connecticut, nos Estados Unidos, indica que os vagalumes machos sincronizam suas luzes para atrair as fêmeas. Segundo os cientistas, a sincronia das piscadas ajuda as fêmeas a encontrar os machos da sua própria espécie, e não cruzar com um vagalume de outra. As informações são do Discovery News . Os pesquisadores afirmam que quando a fêmea vê os machos piscando no mesmo padrão, ela pode responder com outro flash para chamar o parceiro. "O que as fêmeas estão fazendo é procurar pelo número e o tempo dos flashes", diz o pesquisador Andrew Moiseff. Os cientistas, para testar a teoria, utilizaram pequenas luzes LED que imitavam os padrões de diferentes espécies. Contudo, os pesquisadores nã

Error bars in experimental biology. Geoff Cumming, Fiona Fidler, David L Vaux Add to My Library ShareThis The Journal of Cell Biology (2007) Volume: 177, Issue: 1, Publisher: Rockefeller Univ Press, Pages: 7-11 PubMed ID: 17420288 Available from http://www.ncbi.nlm.nih.gov/ Tags basics error bars graphing methods standard deviation standard error statistics Abstract Error bars commonly appear in figures in publications, but experimental biologists are often unsure how they should be used and interpreted. In this article we illustrate some basic features of error bars and explain how they can help communicate data and assist correct interpretation. Error bars may show confidence intervals, standard errors, standard deviations, or other quantities. Different types of error bars give quite different information, and so figure legends must make clear what error bars represent. We suggest eight simple rules to assist with effective use and interpretation of error bars. Cuidado! O autor di

Quantum Entanglement Holds DNA Together, Say Physicists Posted: 27 Jun 2010 09:10 PM PDT A new theoretical model suggests that quantum entanglement helps prevent the molecules of life from breaking apart There was a time, not so long ago, when biologists swore black and blue that quantum mechanics could play no role in the hot, wet systems of life. Since then, the discipline of quantum biology has emerged as one of the most exciting new fields in science. It's beginning to look as if quantum effects are crucial in a number of biological processes, such as photosynthesis and avian navigation which we've looked at here and here . Now a group of physicists say that the weird laws of quantum mechanics may be more important for life than biologists could ever have imagined. Their new idea is that DNA is held together by quantum entanglement. That's worth picking apart in more detail. Entanglement is the weird quantum process in which a single wavefunction describes two separat

Mammalian Sleep Dynamics: How Diverse Features Arise from a Common Physiological Framework Article Metrics Related Content Comments: 0 To add a note , highlight some text. Hide notes Make a general comment Jump to Abstract Author Summary Introduction Results Discussion Methods Author Contributions References Andrew J. K. Phillips 1 , 2 , 3 * , Peter A. Robinson 1 , 2 , 4 , David J. Kedziora 1 , 2 , Romesh G. Abeysuriya 1 , 2 1 School of Physics, University of Sydney, Sydney, Australia, 2 Brain Dynamics Center, Westmead Millennium Institute, Sydney Medical School - Western, University of Sydney, Westmead Hospital, Sydney, Australia, 3 Division of Sleep Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, Massachussetts, United States of America, 4 Center for Integrated Research and Understanding of Sleep, Camperdown, Australia Abstract Top Mammalian sleep varies widely, ranging from frequent napping in rodents to consolidated blocks in primates and unihemisph

Vou violar a regra de não alimentar trolls. É que aparentemente o leitor César Reis exemplifica um novo tipo de criacionismo, que não tem origem no fundamentalismo cristão, judeu ou muçulmano, mas sim em um fundamentalismo Nova Era. Assim, vou tentar responder parágrafo por parágrafo. Prezado Osame: Não sei de onde você tirou este fantástico e massificador placar de 98% para teólogos cristãos favoráveis ao evolucionismo darwinista. Poderia indicar-me a fonte da pesquisa? E quantos seriam esses teólogos: 10, 15, 23? E de onde seriam os teólogos: do Brasil, da Tanzânia? É tudo muito simples Osame, os céticos de modo geral fazem de tudo para provar suas teorias materialistas, inclusive mentir. Se você se der ao trabalho de num dia desses prestar atenção aos pastores evangélicos na TV – a grande maioria, senão todos, são teólogos – verá que são pelo criacionismo. César, estou considerando os teólogos profissionais, ou seja, o pessoal com pós-graduação em teologia, e não os pastores de TV q