Deadly Effects of Certain Kinds of Household Air Pollution

Almost four million people die each year from household air pollution (HAP) caused by exposure to the combustion of biomass fuels (wood, charcoal, crop residues, and dung), kerosene, or coal. These individuals are among the tens of millions who rely on such products to cook their meals, heat their rooms, and light their homes. Those in lower and middle income countries are among the hardest hit by the effects of HAP exposure, which also causes childhood respiratory infection, chronic lung disease, and cardiovascular disease. Exposure to biomass fuel is associated with low birth weight, asthma, and tuberculosis.

Given these effects, the large populations at risk, and a growing global interest in lower-cost energy sources, researchers from three continents have published a comprehensive overview of the current approaches to HAP assessments, the aims of biomarker development, and the state of development of tests which have the potential for rapid transition from the lab bench to field use. The effort is being led by William J. Martin II, MD, Associate Director for Disease Prevention and Health Promotion, and health institutions, their findings are addressed in the article, "Household air pollution: a call for studies into biomarkers of exposure and predictors of respiratory disease," which is published online by the American Journal of Physiology-Lung Cellular and Molecular Physiology.

Current approaches to HAP assessment, challenges

The researchers found that current HAP assessment tools include direct quantitative measurement of products of incomplete combustion, as well as qualitative methods (including use of questionnaires or the categorization of HAP exposure by type). However, direct exposure assessments via personal monitoring are problematic due to the size, portability and recording capacity of equipment, and acceptability to the user.

Despite the new devices currently being field tested and scaled up for commercial use to address these concerns, specific particulate measurement alone cannot differentiate between the multiple sources of pollution such as mixtures of HAP, tobacco smoke, and outdoor pollution. "The grand challenge to the research community is to produce simple and validated tests that better identify populations that are at risk from HAP, and individual responses to exposure reduction strategies," according to Dr. Martin.

The researchers also found that current HAP exposure measurement methods are expensive, technically challenging, difficult to use with large population studies, and have substantial limitations, making an urgent case for the development of biomarkers of both exposure and health effects. These findings have led to their call for studies into biomarkers of exposure and predictors of respiratory disease.

Martin and his colleagues note that further development of biomarkers of susceptibility and effect could facilitate large scale studies examining the impact of HAP on health and disease in human populations. In the end, new biomarkers would: (a) improve epidemiological accuracy in association studies with health effect; (b) reduce the cost and complexity of monitoring intervention studies; (c) provide data for educating the public and policymakers about risk; and (d) inform clinicians and the public health community about human environmental exposures that are not well characterized.

Source: sciencedaily

B.N

How much gold is there in the world?

Imagine if you were a super-villain who had taken control of all the world's gold, and had decided to melt it down to make a cube. How big would it be? Hundreds of metres cubed, thousands even?

Actually, it's unlikely to be anything like that size.

Warren Buffet, one of the world's richest investors, says the total amount of gold in the world - the gold above ground, that is - could fit into a cube with sides of just 20m (67ft).

But is that all there is? And if so, how do we know?

A figure that is widely used by investors comes from Thompson Reuters GFMS, which produces an annual gold survey.

Their latest figure for all the gold in the world is 171,300 tonnes - which is almost exactly the same as the amount in our super-villain's imaginary cube.

A cube made of 171,300 tonnes would be about 20.7m (68ft) on each side. Or to put it another way, it would reach to 9.8m above ground level if exactly covering Wimbledon Centre Court.

But not everyone agrees with the GFMS figures.

Estimates range from 155,244 tonnes, marginally less than the GFMS figure, to about 16 times that amount - 2.5 million tonnes.

That bigger figure would make a cube of sides 50m (166ft) long, or a column of gold towering 143m above Wimbledon centre court.

Part of the reason is that gold has been mined for a very long time - more than 6,000 years, according to gold historian Timothy Green.

Continue reading the main story          

 All the gold that has been mined throughout history is still in existence ”

The first gold coins were minted in about 550 BC under King Croesus of Lydia - a province in modern-day Turkey - and quickly became accepted payment for merchants and mercenary soldiers around the Mediterranean.

Up until 1492, the year Columbus sailed to America, GFMS estimates that 12,780 tonnes had been extracted.

But one investor who looked at the research done in this area, James Turk, the founder of Gold Money, discovered what he regarded as a series of over-estimates.

 

He believes that the primitive mining techniques used up to the Middle Ages mean that this figure is much too high, and that a more realistic total is just 297 tonnes.

His figure for the overall amount of gold in the world is 155,244 tonnes - 16,056 tonnes, or 10% less, than the assessment by Thompson Reuters GFMS. A relatively small disparity, perhaps, but one that at today's prices comes to more than $950bn.

His conclusions are accepted by some investors but such is the feeling between rival analysts that one competitor described Turk's figures as an alternative to the GFMS's "in the same way that Jedi is an alternative to Christianity".

But there are others who think both sets of figures are too low.

One of Tutenkhamen's sarcophagi

"In Tutankhamen's tomb alone they found that his coffin was made from 1.5 tonnes of gold, so imagine the gold that was found in the other tombs that were ransacked before records were taken of them," says Jan Skoyles of gold investment firm The Real Asset Company.

While James Turk makes only minor adjustments to the GFMS figure for the amount of gold mined after 1492, Skoyles points out that even today China is "not particularly open" about how much gold it is mining.

And in some countries, such as Colombia, "there's a lot of illegal mining going on", she says.

She doesn't have an exact figure to offer, but one organisation that has tried to do some maths is the Gold Standard Institute.

Gold mine in Bunia There is much gold still in the ground, like here in Democratic Republic of Congo

Its experts believe that if we emptied our bank vaults and jewellery boxes, we'd find no less than 2.5 million tonnes of gold - though they admit that the evidence is somewhat sparse and the figure is a bit speculative.

In the end, all these numbers are made up of estimates added to estimates added to yet more estimates. Maybe they're all way off.

The good news is that we are not likely to run out of gold any time soon. The US Geological Survey estimates there are 52,000 tonnes of minable gold still in the ground and more is likely to be discovered.

"All the gold that has been mined throughout history is still in existence in the above-ground stock. That means that if you have a gold watch, some of the gold in that watch could have been mined by the Romans 2,000 years ago," says James Turk.

The way gold is being used in the technology industry, however, is different.

 

The British Geological Survey states that about 12% of current world gold production finds its way to this sector, where it is often used in such small quantities, in each individual product, that it may no longer be economical to recycle it.

In short, gold may be being "consumed" for the first time.

Source:BBC

R.Sawas

First Migration from Africa Less Than 95,000 Years Ago

Recent measurements of the rate at which children show DNA changes not seen in their parents -- the "mutation rate" -- have challenged views about major dates in human evolution.

In particular these measurements have made geneticists think again about key dates in human evolution, like when modern non-Africans split from modern Africans. The recent measurements push back the best estimates of these dates by up to a factor of two. Now, however an international team led by researchers at the University of Tübingen and the Max Planck Institute for Evolutionary Anthropology in Leipzig, present results that point again to the more recent dates. The new study is published in Current Biology.

The team, led by Johannes Krause from Tübingen University, was able to reconstruct more than ten mitochondrial genomes (mtDNAs) from modern humans from Eurasia that span 40,000 years of prehistory. The samples include some of the oldest modern human fossils from Europe such as the triple burial from Dolni Vestonice in the Czech Republic, as well as the oldest modern human skeletons found in Germany from the site of Oberkassel close to Bonn.

The researchers show that pre-ice age hunter-gatherers from Europe carry mtDNA that is related to that seen in post-ice age modern humans such as the Oberkassel fossils. This suggests that there was population continuity throughout the last major glaciation event in Europe around 20,000 years ago. Two of the Dolni Vestonice hunter-gatherers also carry identical mtDNAs, suggesting a close maternal relationship among these individuals who were buried together.

The researchers also used the radiocarbon age of the fossils to estimate human mutation rates over tens of thousands of year back in time. This was done by calculating the number of mutations in modern groups that are absent in the ancient groups, since they had not yet existed in the ancient population. The mutation rate was estimated by counting the number of mutations accumulated along descendent lineages since the radiocarbon dated fossils.

Using those novel mutation rates -- capitalizing on information from ancient DNA -- the authors cal-culate the last common ancestor for human mitochondrial lineages to around 160,000 years ago. In other words, all present-day humans have as one of their ancestors a single woman who lived around that time.

The authors also estimate the time since the most recent common ancestor of Africans and non-Africans to between 62,000-95,000 years ago, providing a maximum date for the mass migration of modern humans out of Africa. Those results are in agreement with previous mitochondrial dates based on archaeological and anthropological work but are at the extreme low end of the dates sug-gested from de-novo studies that suggest a split of non-Africans from Africans about thirty thousand years earlier.

 

"The results from modern family studies and our ancient human DNA studies are in conflict" says Krause. "One possibility is that mutations were missed in the modern family studies, which could lead to underestimated mutation rates." The authors argue that nuclear genomes from ancient modern humans may help to explain the discrepancies.

Source: Science Daily

M.Wassouf

Distant Planetary System Is a Super-Sized Solar System

A team of astronomers, including Quinn Konopacky of the Dunlap Institute for Astronomy & Astrophysics, University of Toronto, has made the most detailed examination yet of the atmosphere of a Jupiter-like planet beyond our Solar System.

According to Konopacky, "We have been able to observe this planet in unprecedented detail because of the advanced instrumentation we are using on the Keck II telescope, our ground-breaking observing and data-processing techniques, and because of the nature of the planetary system."

Konopacky is lead author of the paper describing the team's findings, to be published March 14th in Science Express, and March 22nd in the journal Science.

The team, using a high-resolution imaging spectrograph called OSIRIS, uncovered the chemical fingerprints of specific molecules, revealing a cloudy atmosphere containing carbon monoxide and water vapour. "With this level of detail," says Travis Barman, a Lowell Observatory astronomer and co-author of the paper, "we can compare the amount of carbon to the amount of oxygen present in the planet's atmosphere, and this chemical mix provides clues as to how the entire planetary system formed."

There has been considerable uncertainty about how systems of planets form, with two leading models, called core accretion and gravitational instability. Planetary properties, such as the composition of a planet's atmosphere, are clues as to whether a system formed according to one model or the other.

"This is the sharpest spectrum ever obtained of an extrasolar planet," according to co-author Bruce Macintosh of the Lawrence Livermore National Laboratory. "This shows the power of directly imaging a planetary system. It is the exquisite resolution afforded by these new observations that has allowed us to really begin to probe planet formation."

The spectrum reveals that the carbon to oxygen ratio is consistent with the core accretion scenario, the model thought to explain the formation of our Solar System.

The planet, designated HR 8799c, is one of four gas giants known to orbit a star 130 light-years from Earth. The authors and their collaborators previously discovered HR 8799c and its three companions back in 2008 and 2010. All the planets are larger than any in our Solar System, with masses three to seven times that of Jupiter. Their orbits are similarly large when compared to our system. HR 8799c orbits 40 times farther from its parent star than Earth orbits from the Sun; in our Solar System, that would put it well beyond the realm of Neptune.

According to the core accretion model, the star HR 8799 was originally surrounded by nothing but a huge disk of gas and dust. As the gas cooled, ice formed; this process depleted the disk of oxygen atoms. Ice and dust collected into planetary cores which, once they were large enough, attracted surrounding gas to form large atmospheres. The gas was depleted of oxygen, and this is reflected in the planet's atmosphere today as an enhanced carbon to oxygen ratio.

The core accretion model also predicts that large gas giant planets form at great distances from the central star, and smaller rocky planets closer in, as in our Solar System. It is rocky planets, not too far, nor close to the star, that are prime candidates for supporting life.

"The results suggest the HR 8799 system is like a scaled-up Solar System," says Konopacky. "And so, in addition to the gas giants far from their parent star, it would not come as a surprise to find Earth-like planets closer in."

The observations of HR 8799c were made with the Keck II 10-metre telescope in Hawaii, one of the two largest optical telescopes in the world. The telescope's adaptive optics system corrects for distortion caused by Earth's atmosphere, making the view through Keck II sharper than through the Hubble Space Telescope.

Astronomers refer to this as spatial resolution. Seeing exoplanets around stars is like trying to see a firefly next to a spotlight. Keck's adaptive optics and high spatial resolution, combined with advanced data-processing techniques, allow astronomers to more clearly see both the stellar "spotlight" and planetary "firefly."

"We can directly image the planets around HR 8799 because they are all large, young, and very far from their parent star. This makes the system an excellent laboratory for studying exoplanet atmospheres," says coauthor Christian Marois of the National Research Council of Canada. "Since its discovery, this system just keeps surprising us."

Konopacky and her team will continue to study the super-sized planets to learn more details about their nature and their atmospheres. Future observations will be made using the recently upgraded OSIRIS instrument which utilizes a new diffraction grating -- the key component of the spectrograph that separates light according to wavelength, just like a prism. The new grating was developed at the Dunlap Institute and installed in the spectrograph in December 2012.

"These future observations will tell us much more about the planets in this system," says Dunlap Fellow Konopacky. "And the more we learn about this distant planetary system, the more we learn about our own."

Source:Science Daily

M.wassouf

Astronomers Conduct First Remote Reconnaissance of Another Planetary System

Researchers have conducted a remote reconnaissance of a distant planetary system with a new telescope imaging system that sifts through the blinding light of stars. Using a suite of high-tech instrumentation and software called Project 1640, the scientists collected the first chemical fingerprints, or spectra, of this system's four red exoplanets, which orbit a star 128 light years away from Earth.

A detailed description of the planets -- showing how drastically different they are from the known worlds in the universe -- was accepted Friday for publication in The Astrophysical Journal.

"An image is worth a thousand words, but a spectrum is worth a million," said lead author Ben R. Oppenheimer, associate curator and chair of the Astrophysics Department at the American Museum of Natural History,according to Science Daily.

Oppenheimer is the principal investigator for Project 1640, which uses the Hale telescope at the Palomar Observatory in California. The project involves researchers from the California Institute of Technology, NASA's Jet Propulsion Laboratory, Cambridge University, New York University, and the Space Telescope Science Institute, in addition to Oppenheimer's team at the Museum.

The planets surrounding the star of this study, HR 8799, have been imaged in the past. But except for a partial measurement of the outermost planet in the system, the star's bright light overwhelmed previous attempts to study the planets with spectroscopy, a technique that splits the light from an object into its component colors -- as a prism spreads sunlight into a rainbow. Because every chemical, such as carbon dioxide, methane, or water, has a unique light signature in the spectrum, this technique is able to reveal the chemical composition of a planet's atmosphere.

"In the 19th century it was thought impossible to know the composition of stars, but the invention of astronomical spectroscopy has revealed detailed information about nearby stars and distant galaxies," said Charles Beichman, executive director of the NASA Exoplanet Science Institute at the California Institute of Technology. "Now, with Project 1640, we are beginning to turn this tool to the investigation of neighboring exoplanets to learn about the composition, temperature, and other characteristics of their atmospheres."

With this system, the researchers are the first to determine the spectra of all four planets surrounding HR 8799. "It's fantastic to nab the spectra of four planets in a single observation," said co-author Gautam Vasisht, an astronomer at the Jet Propulsion Laboratory.

 

The results are "quite strange," Oppenheimer said. "These warm, red planets are unlike any other known object in our universe. All four planets have different spectra, and all four are peculiar. The theorists have a lot of work to do now."

Researchers are already collecting more data on this system to look for changes in the planets over time, as well as surveying other young stars. During its three-year survey at Palomar, which started in June 2012, Project 1640 aims to survey 200 stars within about 150 light years of our solar system.

"The variation in the spectra of the four planets is really intriguing," said Didier Saumon, an astronomer at Los Alamos National Laboratory who was not involved in this study. "Perhaps this shouldn't be too surprising, given that the four gaseous planets of the solar system are all different. The hundreds of known exoplanets have forced us to broaden our thinking, and this new data keeps pushing that envelope."

M.W