|Lunar crater Daedalus on the Moon's far side|
Wednesday, 25 May 2016
In 1961, the formal announcement of an American lunar landing was made by President John F. Kennedy speaking to the Congress: “I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space program in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish.”
Since, a total of twelve men have landed on the Moon. This was accomplished with two US pilot-astronauts flying a Lunar Module on each of six NASA missions across a 41-month time span starting on 20 July 1969 UTC, with Neil Armstrong and Buzz Aldrin on Apollo 11, and ending on 14 December 1972 UTC with Gene Cernan and Jack Schmitt on Apollo 17. Cernan was the last to step off the lunar surface.
All Apollo lunar missions had a third crew member who remained on board the Command Module. The last three missions had a rover for increased mobility.
The atmosphere of the moon
The Moon has an atmosphere so tenuous as to be nearly vacuum, with a total mass of less than 10 metric tons (9.8 long tons; 11 short tons). The surface pressure of this small mass is around 3 × 10−15 atm (0.3 nPa); it varies with the lunar day. Its sources include outgassing and sputtering, the release of atoms from the bombardment of lunar soil by solar wind ions. Elements that have been detected include sodium and potassium, produced by sputtering, which are also found in the atmospheres of Mercury and Io; helium-4 and neon from the solar wind; and argon-40, radon-222, and polonium-210, outgassed after their creation by radioactive decay within the crust and mantle.
The absence of such neutral species (atoms or molecules) as oxygen, nitrogen, carbon, hydrogen and magnesium, which are present in the regolith, is not understood. Water vapour has been detected by Chandrayaan-1 and found to vary with latitude, with a maximum at ~60–70 degrees; it is possibly generated from the sublimation of water ice in the regolith. These gases can either return into the regolith due to the Moon's gravity or be lost to space, either through solar radiation pressure or, if they are ionized, by being swept away by the solar wind's magnetic field.
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Wednesday, 18 May 2016
Higher intakes of boiled, baked, or mashed potatoes, and French fries is associated with an increased risk of developing high blood pressure (hypertension) in adult women and men, according to a study published by The BMJ today.
The US-based researchers suggest that replacing one serving a day of boiled, baked, or mashed potatoes with one serving of a non-starchy vegetable is associated with a lower risk of developing hypertension.
But a linked editorial argues that studying overall dietary patterns and risk of disease is more useful than a focus on individual foods or nutrients.
|Various potato dishes by Scott Bauer (United States Department of Agriculture (link)) [Public domain], via Wikimedia Commons|
Potatoes are one of the world's most commonly consumed foods - and have recently been included as vegetables in US government healthy meals programs, due to their high potassium content. But the association of potato intake with hypertension has not been studied.
So researchers based at Brigham and Women's Hospital and Harvard Medical School set out to determine whether higher long term intake of baked, boiled, or mashed potatoes, French fries, and potato chips (crisps) was associated with incident hypertension.
They followed over 187,000 men and women from three large US studies for more than 20 years. Dietary intake, including frequency of potato consumption, was assessed using a questionnaire. Hypertension was reported by participants based on diagnosis by a health professional.
After taking account of several other risk factors for hypertension, the researchers found that four or more servings a week of baked, boiled, or mashed potatoes was associated with an increased risk of hypertension compared with less than one serving a month in women, but not in men.
Higher consumption of French fries was also associated with an increased risk of hypertension in both women and men. However, consumption of potato chips (crisps) was associated with no increased risk.
After further analyses, the researchers suggest that replacing one serving a day of boiled, baked, or mashed potatoes with one serving of a non-starchy vegetable is associated with a decreased risk of hypertension.
The authors point out that potatoes have a high glycaemic index compared with other vegetables, so can trigger a sharp rise in blood sugar levels, and this could be one explanation for the findings.
They also acknowledge some study limitations and say that, as with any observational study, no firm conclusions can be drawn about cause and effect.
Nevertheless, they say their findings "have potentially important public health ramifications, as they do not support a potential benefit from the inclusion of potatoes as vegetables in government food programs but instead support a harmful effect that is consistent with adverse effects of high carbohydrate intakes seen in controlled feeding studies."
In a linked editorial, researchers at the University of New South Wales argue that, although diet has an important part to play in prevention and early management of hypertension, dietary behaviour and patterns of consumption are complex and difficult to measure.
"We will continue to rely on prospective cohort studies, but those that examine associations between various dietary patterns and risk of disease provide more useful insights for both policy makers and practitioners than does a focus on individual foods or nutrients," they conclude.
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Tuesday, 10 May 2016
Skywatchers across the globe are observing Mercury transit the Sun, the little planet's third such pass of 14 it will make this century.
Mercury's sojourn between Earth and our star lasts from 11:12 until 18:42 GMT.
It will not make another transit until 2019 and then 2032.
The event is impossible - and dangerous - to view with the naked eye or binoculars, but astronomy groups worldwide are offering the chance view it through filtered telescopes.
Live views from space and ground telescopes are also available online.
They show Mercury as a tiny black circle, smaller but darker than many sunspots, slowly traversing the Sun's giant yellow disc.
Mercury spins around the Sun every 88 days, but its orbit is tilted relative to the Earth's. It is that discrepancy which makes it relatively rare for the three bodies to line up in space.
From western Europe, north-western Africa and much of the Americas, Mercury's seven-and-a-half-hour glide across the Sun will be visible in its entirety. A further swathe of the planet will catch part of the transit, depending on local sunrise and sunset times.
The only land masses to miss out completely are Australasia, far eastern Asia and Antarctica.
Because Mercury is so small - just one-third as big as Earth and, from our perspective, 1/150th of the Sun's diameter - its transit can only be glimpsed under serious magnification; the "eclipse glasses" used by thousands of people to view last year's solar eclipse will be useless.
And to avoid permanent eye damage, any telescope must be fitted with a solar filter before being trained on the Sun. The British Astronomical Association explains on its website how amateur stargazers can enjoy the spectacle safely.
Open University's Prof David Rothery said the celestial event would not present any novel scientific opportunities - but was special nonetheless.
"From this transit, we're unlikely to learn anything we don't already know," he told BBC Inside Science. "But what a wonderful event for showing people Mercury. It's a hard planet to see.
"Historically, transits were of immense importance."
In the 1700s, for example, it was observations of Mercury and Venus slipping across the Sun that allowed astronomers, led by Edmund Halley, to pin down the dimensions of the known Solar System.
Prof Rothery is a Mercury expert and a leading scientist on the European Space Agency's BepiColombo mission to the diminutive planet, which will launch in 2017 or 2018.
Mercury has already been visited by two Nasa probes: Mariner 10 flew past in 1974 and 1975 and Messenger spent four years in orbit until its planned crash landing in 2015.
Messenger spent four years in orbit taking images and measurements of Mercury
"[Messenger] told us an awful lot. It really told us we don't understand Mercury - because there's a lot of things which just don't stack up," Prof Rothery said.
"It's an airless body, with lots of craters... But there's been a long history of volcanic activity, fault activity - and the composition, that began to be revealed by Messenger, is weird.
"There's very little iron at the surface but it must have a ginormous iron core, because it generates a magnetic field - which Venus, Mars and the Moon don't."
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Tuesday, 3 May 2016
Livestock farming is responsible for 18 percent of the world's greenhouse gases, and ruminants such as cattle, sheep and goats generate 35 percent of one of these gases - methane, and according to experts they make a significant contribution to climate change.
Researchers at the Spanish National Research Council (CSIC) have taken part in a study of the effect of one molecule, 3-nitrooxypropanol, in inhibiting methane production in ruminants. The work has been published in the magazine, Proceedings of the National Academy of Sciences (PNAS).
|Stereo, skeletal formula of methane with some measurements added. By Jynto [Public domain], via Wikimedia Commons.|
Ruminants are animals which digest their food through fermentation carried out by microorganisms living in the rumen. This process produces organic acids: acetic acid, propionic acid, and butyric acid, all of which are absorbed and metabolized by the organism as a source of energy. But, in addition, it also produces methane, which escapes into the atmosphere in the form of gas.
How 3-nitrooxypropanol works
By 2014, scientists had demonstrated the effectiveness of this molecule in sheep, but were unaware of how it actually worked. Now, in vivo research, using incubated anaerobic microorganisms from ruminants' digestive systems have revealed how the compound 3-nitrooxypropanol only had an effect on methane producing microorganisms (arqueas methanogens) and not on those which contribute to digestion (bacterias). As David Yáñez, a CSIC researcher at the Zaidin Experimental Research Centre in Granada (southern Spain) explains, "Up until now, no-one had described the mode of action of a compound which can repeatedly reduce (by 30%) methane production in animals without any risks, either to the animal's health, or to their productivity."
The results of this work open up the possibility of reducing methane emissions and of contributing to a reduction in global temperatures which is caused by greenhouse gases. In addition, "We will see an increase in the efficiency of ruminant production systems as better use is made of the energy taken in in animal feed, given that methane production accounts for a loss of up to 12% of the energy an animal ingests" notes Yáñez.
Both the University of Auburn in the USA and the Max Planck Institute in Germany collaborated on this project as did the Swiss company, DSM Nutritional Products, which developed and owns the patent to 3-nitrooxypropanol.
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