yesterday's full moon
https://mail.google.com/mail/?zx=akjq19ih146w&shva=1#inbox/11e2a03f376ba7eb
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Εμφάνιση αναρτήσεων με ετικέτα SCIENCE. Εμφάνιση όλων των αναρτήσεων
Εμφάνιση αναρτήσεων με ετικέτα SCIENCE. Εμφάνιση όλων των αναρτήσεων
13/12/08
https://mail.google.com/mail/?zx=akjq19ih146w&shva=1#inbox/11e2a03f376ba7eb
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16/11/08
23/11/06
We're only human? It's more complex than that
Wed Nov 22, 1:07 PM ET
PARIS (AFP)
New investigations into the code for life suggest the assumption that humans are genetically almost identical is wide of the mark, and the implications could be resounding.
Current thinking, inspired by the results five years ago from the Human Genome Project, is that the six billion humans alive today are 99.9 percent similar when it comes to genetic content and identity.
But major research work, published on Thursday, suggests we are genetically more diverse -- and the repercussions could be far-reaching for medical diagnosis, new drugs and the tale of human evolution itself.
Until now, analysis of the genome has focussed overwhelmingly on comparing flaws, or polymorphisms, in single "letters" in the chemical code for making and sustaining human life.
An international consortium of scientists has taken a different tack and believe they have uncovered a complex, higher-order variation in the code.
This better explains why some individuals are vulnerable to certain diseases and respond well to specific drugs, while counterparts swiftly fall sick or never respond to treatment, the authors believe.
Their focus has been to dig out deletions or duplications of code among relatively long sequences of individual DNA and then compare these so-called copy number variations (CNVs) across a range of volunteers of different ancestry.
The researchers were astonished to locate 1,447 CNVs in nearly 2,900 genes, or around one eighth of the human genetic code.
"Each one of us has a unique pattern of gains and losses of complete sections of DNA," said Matthew Hurles of Britain's Wellcome Trust Sanger Institute, one of the project's partners.
"One of the real surprises of these results was just how much of our DNA varies in copy number. We estimate this to be at least 12 percent of the genome."
"The copy number variation that researchers had seen before was simply the tip of the iceberg, while the bulk lay submerged, undetected. We now appreciate the immense contribution of this phenomenon to genetic differences between individuals."
Some of the missing or duplicated stretches are very long, suggesting that, like backroom switches in a protein factory, CNVs must have a big impact on gene expression.
Nearly 16 percent of genes that are known to be related to disease have CNVs, the group found.
These include genes involved in rare genetic disorders such as DiGeorge, Williams-Beuren and Prader-Willi syndromes and those linked with schizophrenia, cataracts, spinal muscular atrophy and atherosclerosis.
But kidney disease, Parkinson's, Alzheimer's and vulnerability to malaria and the human immunodeficiency virus (HIV), which recent research has blamed on single-letter variations in the gene code, may also well be rooted in CNVs, the doctors believe.
"The stage is set for global studies to explore anew... the clinical significance of human variation," said Huntington Willard and Kevin Shianna of the Institute for Genome and Science Policy at Duke University in North Carolina, in a review of the research.
Evolution is another area that will come under new scrutiny.
The "Out of Africa" scenario, by which Homo sapiens emerged from east Africa and spread around the globe, will not be challenged, though.
Our origins are so recent that the vast majority of CNVs, around 89 percent, was found to be shared among the 269 people who volunteered blood as samples for the study.
These individuals included Japanese from Tokyo, Han Chinese from Beijing, Yoruba from Nigeria and Americans of Northern and Western European ancestry.
All the same, there are widespread differences in CNVs according to the three geographical origins of the samples.
This implies that, over the last 200,000 years or so, subtle variants have arisen in the genome to allow different populations of humans adapt to their different environments, Wellcome Trust Sanger said in a press release.
The research, which appears in the British journal Nature, is based on two technical breakthroughs, one in faster, accurate sequencing of DNA and the other in a powerful software programme to spot the CNVs.
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13/11/06
28/10/06
WILLIAM PYE THE WATER SCULPTOR
THIS ONE CALLED "CHARYBDIS"
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19/10/06
Halloween Special
Myth-diagnosis:
Vampirism or Porphyria?
What creature has very pale skin, has teeth of an unusual colour, sports long fingernails and only comes out at night? Everyone knows it’s a vampire.
Or is it?
The vampire legend probably arose from the appearance and behaviour of people suffering from porphyria, a disease that is actually a group of related disorders.
All variants of the disease are caused by overproduction of porphyrins—chemicals that do not normally accumulate in the body. Although symptoms are many, most notable is extreme sensitivity to sunlight.
Porphyria is rare, especially outside Eastern Europe, and difficult to diagnose. Symptoms of the disease mimic those of many other ailments: They include insomnia, anxiety, skin lesions, nausea and muscle weakness; some types of porphyria also cause excessive nail growth and receding gums. Exposure to sunlight causes the skin to become so fragile it breaks easily, and people with porphyria avoid being outside at any time during the day—hence the idea that vampires fear sun and roam the earth only at night.
Shedding Light on the Vampire Legend
The most notorious alleged vampire lived in 15th-century Romania. Vlad the Impaler was indeed a ghoulish ruler, whose bloodthirsty habits were known far and wide even before Bram Stoker’s day, but he was not the earliest vampire legend. Records of vampire stories exist from 12th-century England. The Impaler’s sadistic punishments for minor offences certainly fuelled legends, and by all accounts he did actually indulge in the blood of his victims.
By the 17th century, vampires were linked to evil and witchcraft. The 18th century saw vampire hysteria in Eastern Europe into which even government officials were drawn. And in the 19th century, of course, Bram Stoker’s Dracula cemented into popular cultures the myths that had developed over centuries.
The early beliefs—that vampires drank blood, were creatures of darkness, and were fascinated with counting—were enriched by the newer aspects of the myth. Only within the last 200 years were we introduced to vampires who are dressed in capes and who turn into bats. But with the migration of cultures and their legends, some of the interesting traditions were lost—such as leaving a pile of seeds outside the door so a vampire would be distracted by counting them, thus losing interest in drinking the inhabitants’ blood.
Even with some of the finer details lost, and with evidence that porphyria was the likely cause of an odd appearance and behaviour, the vampire has captured the imagination of the public like no other legend.
Werewolves or hypertrichosis
The myth of the werewolf or "shape-shifter" dates back to the cavemen. The condition on which the myth was based is almost surely older than that.
A condition that probably contributed to the werewolf myth is hypertrichosis or hirsutism, which causes excessive hair growth over the entire body. The condition is linked to endocrine malfunction, which can be genetic and present at birth. The gene that causes the disease was recently isolated by geneticists and is thought to be an atavism, a once common genetic trait that became less common as humans evolved. The trait is sex-linked and dominant; males who inherit the disease from their mothers develop the condition, while females who inherit only one of the trait-bearing chromosomes exhibit the thick hair growth in random patches.
The condition can also develop over the course of a lifetime. Often, acquired hypertrichosis is the result of hormonal irregularities.
Hypertrichosis, especially from birth, is rare, but well-documented. In the past and even today, people with the condition have appeared in circuses as "wolf-men" or "dog-boys." No doubt these public exhibitions have contributed to the werewolf fascination.
The Werewolf Evolves
Every culture has its werewolf. The mythology has had a stronger hold on some cultures than others. Germany is famous for its werewolves, popularized by the Brothers Grimm. In early legends, people who became werewolves were cursed with the condition, and simply acted as wolves after they were transformed. In later legends, the werewolf was better able to control the transformation, usually using a salve or special article of clothing, and used the ability only to attack livestock in enemy farmers’ fields. In these stories, people are accidental victims of the werewolf, if victims at all.
Over time, werewolf folklore evolved from simple shape-shifting and animal worship to the 19th century and present-day conceptions, which are closely, linked to both witch and vampire legends. The Western werewolf, epitomized in Stephen King’s The Silver Bullet, transforms according to lunar changes which are linked to witchcraft, and can only be killed by a silver bullet formed from a molten crucifix, reminiscent of vampire lore.
Copyright © Demetrios the Traveler
(Brexians lair)
12/10/06
11/10/06
Yahoo to digitally encapsulate 2006
If there's any intelligent life out there with the right technology, they can expect to receive a laser-guided load of multimedia messages from our little blue-green planet, thanks to Yahoo.
The search company announced today the launch of an Internet time capsule, intended to document life in 2006. People from around the globe are invited to submit digital photos, text, movies, and audio files on topics such as love, sorrow, beauty, the past, and the present.
At the end of the project (about 29 days from now), the time capsule will be saved onto a digital archive and sealed at the Yahoo HQ to be opened in 2020. Another copy will go to the Smithsonian Folkways Recordings archive in Washington D.C.
Finally, in a move that has PR stunt written all over it, Yahoo on Oct. 25 through 27 will project the capsule contents onto one of the world's oldest time capsules, the Pyramid of the Sun in Teotihuacán, Mexico, and beam it into space from the pyramid. This event will be viewable live via Webcast.
"Wherever people use Yahoo -- from Mexico, Germany or China to the U.S. -- we want them to represent their culture and show us what's impor-tant to them by participating in this historic Internet time capsule event," said Jerry Yang, co-founder and "chief Yahoo." "It will be fascinating to see what people submit as their part of this 2006 snapshot, which will be shared with generations to come."
The time capsule, accessible at timecapsule.yahoo.com, was designed by artist Jonathan Harris, and it shows. Aesthetically speaking, I think Harris has done an impressive job of designing an application that's not only aesthetically pleasing but also intuitive for making contributions and sifting through them.
There is, for example, a neat Facts page, where you can view all sorts of data about what kind of contributions have been made to the capsule.
(I did observe that some contributors didn't quite grasp the proper technique of tagging contributions, though.)
Also nice: Yahoo will be donating $100,000, divided among eight charities. When you add to the time capsule, you may select which charity of the eight you support.
My only hope is that no one contributes a clip from the show "ALF." I think that could serve to antagonize otherwise peaceful aliens out there who don't take kindly to being portrayed so demeaningly.
Copyright © Demetrios the Traveler
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