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Post-copulatory sexual selection and sexual c...
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Male pregnancy in seahorses, pipefishes and sea dragons (family Syngnathidae) represents a striking reproductive adaptation that has shaped the evolution of behaviour and morphology in this group of fishes1. In many syngnathid species, males brood their offspring in a specialized pouch, which presumably evolved to facilitate male parental care5, 6. However, an unexplored possibility is that brood pouch evolution was partly shaped by parent–offspring or sexual conflict, processes that would result in trade-offs between current and future pregnancies. Here we report a controlled breeding experiment using the sexually dimorphic Gulf pipefish, Syngnathus scovelli, to test for post-copulatory sexual selection within broods and for trade-offs between successive male pregnancies as functions of female attractiveness. Offspring survivorship within a pregnancy was affected by the size of a male’s mate, the number of eggs transferred and the male’s sexual responsiveness. Significantly, we also found that embryo survivorship in a current pregnancy was negatively related to survivorship in the prior pregnancy, clearly demonstrating fitness trade-offs between broods. Overall, our data indicate that post-copulatory sexual selection and sexual c... |
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Stem Cell Research Documentary
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Stem Cell Research Initiative: why it's needed and what it does.Embryonic stem cells (ES cells) are stem cells derived from the inner cell mass of an early stage embryo known as a blastocyst. Human embryos reach the blastocyst stage 4-5 days post fertilization, at which time they consist of 50-150 cells.
ES cells are pluripotent. This means they are able to differentiate into all derivatives of the three primary germ layers: ectoderm, endoderm, and mesoderm. These include each of the more than 220 cell types in the adult body. Pluripotency distinguishes ES cells from multipotent progenitor cells found in the adult; these only form a limited number of cell types. When given no stimuli for differentiation, (i.e. when grown in vitro), ES cells maintain pluripotency through multiple cell divisions. The presence of pluripotent adult stem cells remains a subject of scientific debate, however, research has demonstrated that pluripotent stem cells can be directly generated from adult fibroblast cultures.[1]
Because of their plasticity and potentially unlimited capacity for self-renewal, ES cell therapies have been proposed for regenerative medicine and tissue replacement after injury or disease. However, to date, no approved medical... |
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Gandhi - His Triumph changed the World Foreve...
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Mohandas Karamchand Gandhi[4] was born into the Hindu Modh family in Porbandar, in 1869. He was the son of Karamchand Gandhi, the diwan (Prime Minister) of Porbandar, and Putlibai, Karamchand's fourth wife, a Hindu of the Pranami Vaishnava order. Karamchand's first two wives, who each bore him a daughter, died from unknown reasons (rumored to be in childbirth). Living with a devout mother and surrounded by the Jain influences of Gujarat, Gandhi learned from an early age the tenets of non-injury to living beings, vegetarianism, fasting for self-purification, and mutual tolerance between members of various creeds and sects. He was born into the vaishya, or business, caste.
In May 1883, at the age of 13, Gandhi was married through his parents' arrangements to Kasturba Makhanji (also spelled "Kasturbai" or known as "Ba"). They had four sons: Harilal Gandhi, born in 1888; Manilal Gandhi, born in 1892; Ramdas Gandhi, born in 1897; and Devdas Gandhi, born in 1900. Gandhi was a mediocre student in his youth at Porbandar and later Rajkot. He barely passed the matriculation exam for Samaldas College at Bhavanagar, Gujarat. He was also unhappy at the college, because his family wanted him to become a barrister.
At the age of 18 on Sept... |
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IBM Research Computational Biology Center
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Computational biology is an interdisciplinary field that applies the techniques of computer science, applied mathematics and statistics to address biological problems. The main focus lies in the development of computational and statistical data analysis methods and in developing mathematical modeling and computational simulation techniques. By these means it addresses scientific research topics with their theoretical and experimental questions without a laboratory. It is connected to the following fields: (1) Computational biomodeling, a field concerned with building computer models of biological systems.(2) |
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Test of Rolls Royce Engine for Airbus 380
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A Discovery Channel footage of a destructive testing of a Rolls Royce jet engine. The idea is to see if the engine suffers a destructuve failure, all the fragments from the failure (blade parts, lethal shrapnels) are contained in the engine cover. This is an important part of the testing that ensures safety for passengers. Rolls-Royce plc (LSE: RR.) is a British aircraft engine maker; the second-largest in the world, behind General Electric Aviation. The company has related b... |
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rolex replica
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