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space elevator cable 60-day test

“LiftPort has finished a 60-day test with a 100-metre-long tether held aloft by four helium balloons. The test was designed to see what kinds of problems would crop up if such a platform were used to transmit Wi-Fi signals. The lofty platforms would be especially useful for providing Wi-Fi coverage to rural areas, [...]”
—
“Overall, he says, the test went well, but there were several unexpected encounters with wildlife. More than a dozen insect colonies had laid eggs on the tether [. I]n the first few days of the test, curious bats flew around the balloons, apparently attracted by the sound made by the tether's vibrations. Late in the test, swallows were also seen swooping down on the balloons, possibly to sip the morning dew on their surfaces.”
—
“The team learned that if the tether is pulled hard by wind, it starts to buckle and deform slightly, creating crinkles. The robot climber hit these crinkles and could not proceed because they made the tether too thick for it to handle.

“[...] Future designs will have to incorporate sensors to tell the robot when it is about to encounter varying thicknesses.”

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wanted - long, strong string

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‘bioavailability’: using your intestines as a chemistry set for improved health - the auroran sunset

This Beeb [BBC] article is seriously sloppy, but has a few interesting examples. The article describes an area of nutritional science called ‘bioavailability’. Bioavailability is the study of the absorption of minerals and vitamins into the body under different circumstances. (The term ‘bioavailability’ is also used in pharmacology with regard to the relative absorption of drugs, medicines and poisons to their activity sites.)

The nutritional data on your packet of food from the supermarket will tell you there is such an amount of Vitamin C per 100g, such an amount of iron per 100g, and so on; but this does not mean all of that amount is absorbed or that the same amount gets absorbed every time you eat that food.

Depending on what you eat with the food in question, and on how the food has been prepared, it is possible to change the absorption characteristics of a particular nutrient - making it absorb faster or slower. (Food tends to stay in the stomach and intestines for a fairly standard amount of time, so faster absorption leads fairly directly to greater absorption; conversely slower absorption leads fairly directly to lower absorption).

Here is an example from the Beeb article:

“While red meat contains the type of iron - haem-iron - that is most readily absorbed by the body, vegetarians are pointed towards iron-rich foods such as spinach. However, this vegetable contains the mineral in a form that is not so readily absorbed - non-haem iron.

“But, explains Mr Faulks, a glass of orange juice alongside your plate of spinach can make all the difference.

"Vitamin C in orange juice changes the iron to its non-oxidised state (haem iron) - which is much more readily absorbed than the oxidised iron (non-haem iron).”
—
“ Conversely, explains Dr Steer, tea and coffee contain compounds called phenols that inhibit iron absorption - so they shouldn't be consumed alongside iron-rich foods.”

The article also gives examples contrasting cooked and uncooked food: surprisingly cooked vegetables can sometimes be nutritionally more effective than raw vegetables - although this can at the same time mean a different nutrient is absorbed less. There are also examples of nutrients that absorb more efficiently if you eat them with a little bit of fat.

People have been studying nutritional bioavailability since the 1980s. However, it is a seriously complex study as this fascinating ten page article from 1989 attempts to explain. The article assumes a fair degree of background knowledge of chemistry, but a layman can gain a lot from reading it carefully, and with judicious references to a search engine or a dictionary.

The writer discusses the practicalities of increasing the bioavailability of various important minerals, with particular reference to industrial food processing. It seems a lot can be done by fixing pH at particular points in the processing process. The article also discusses how some methods of increasing bioavailability can cause negative taste effects, yet another complication in this very complicated science. Bioavailability science appears to still be fairly primitive, largely because there are too many variables and substances to take into account.

[Beeb article lead from the empathogen]

keeping up: step forward doctor frank n stein - ok sam, plug him in!

“Scientists working at a British laboratory have achieved one of the most controversial breakthroughs ever made in the field of stem cell science by taking cells from dead embryos and turning them into living tissue.”
—
“The team then waited 24 hours to check that the embryos were no longer dividing before beginning their experiments. 'These were all deemed to be arrested embryos,' said Stojkovic. 'In other words, they were dead. [But] they had the capacity to develop any different type of cell you could think of, including kidney cells, liver cells, and skin cells.' ”

teaching computers to perceive in 3 dimensions

Top left - original; other three images - 3D-rendered images
Image credit: Carnegie Mellon University

“We live in a three-dimensional world but, for the most part, we see it in two dimensions. Discerning how objects and surfaces are juxtaposed in an image is second nature for people, but it's something that has long flummoxed computer vision systems.

“Now, however, researchers in Carnegie Mellon University's School of Computer Science have found a way to help computers understand the geometric context of outdoor scenes and thus better comprehend what they see. The discovery promises to revive an area of computer vision research all but abandoned two decades ago because it seemed insoluble. It may ultimately find application in vision systems used to guide robotic vehicles, monitor security cameras and archive photos.

“Using machine learning techniques, Robotics Institute researchers Alexei Efros and Martial Hebert, along with graduate student Derek Hoiem, have taught computers how to spot the visual cues that differentiate between vertical surfaces and horizontal surfaces in photographs of outdoor scenes. They've even developed a program that allows the computer to automatically generate 3-D reconstructions of scenes based on a single image.”

Test versions of software (Linux and Windows versions) available for download from links at Software section.

the web address for the article above is
https://www.abelard.org/news/science0607.php#photo_to_3d_230806

£60k for a car that watches you and pedestrians

image credit: lexus.com

“What you won’t know is that, as you ponder its purpose, it’s looking right back at you. In that box are six infrared eyes logging the position of your features so it can build up a picture of your mug. It doesn’t matter how tall or short you are or from which ethnic group. It can see you in the pitch black even when you can’t see it and you won’t faze it by donning dark glasses.

“And while it’s watching you, so another set of eyes, in the form of radar and cameras, is watching the road. This way the car can not only spot danger approaching from the back or front of the car, it can also tell whether you’re looking out of the side window or are fast asleep at the wheel as you hurtle towards this life-threatening hazard. If it figures that your attention is not where it should be, it will flash lights, bleep at you and nudge the brakes until it decides you’re back in control. And if you don’t snap out of your stupor it won’t just nudge the brakes, it’ll slam them on to save you from yourself.”
—

image credit: lexus.com

“ And that’s not all this extraordinary car will do. While self-braking vehicles are not new, systems from Honda and Mercedes require the obstacle to be metallic, which is fine if it’s a car you’re about to wallop but entirely ineffective when a child runs out in front of you. The Lexus, by contrast, sees all, or so its maker claims. It will stiffen the suspension in antAicipation of you trying to swerve around the danger and it even has eyes in the back of its head, or the rear bumper to be more precise, permanently scanning for something about to come smashing into the back of you. If it reckons that’s on the cards, it will move your headrest forward and up to minimise whiplash.”

the web address for the article above is
https://www.abelard.org/news/science0607.php#big_brother_car_210806

man regrows brain

“We read about these widely publicised cases of miraculous recovery every few years, but none of them, not one, has ever been followed up scientifically until now," said Dr Nicholas Schiff, a neuroscientist at Weill Cornell Medical College in Manhattan and the senior author of the new study.”
—
“Nerve cells that have not died can form new connections; for example, nerves in the arms and legs can grow about 2.5 centimetres a month after they are severed or damaged. This happens far less often in the brain.

“The new research suggests that instead of the sudden recovery Mr Wallis seemed to make three years ago, he may have been slowly recovering all along, as nerves in his brain slowly formed new connections until enough were present to make a network.”

the web address for the article above is
https://www.abelard.org/news/science0607.php#brain_050706

our wobbling earth

Wobbles in the Earth’s rotation on its axis. Image credit: l'Observatoire de Paris

“Like a spinning top, Earth wobbles as it rotates on its axis. In fact, it displays many different wobbling motions, ranging in period from a few minutes to billions of years. Some of these are well studied, like the Chandler wobble of 433 days and the annual wobble, which together can tilt Earth's axis up to 10 meters [30 feet] from its nominal center.”
—
“[...] scientists in Belgium and France have taken advantage of a quirk in the pattern of large-scale motions and the advent of the Global Positioning System (GPS) to pin down short-term wobbles that occurred from November 2005 through February 2006.

“During this period, the Chandler wobble and the annual wobble essentially cancelled each other out, an event that occurs every 6.4 years, allowing the researchers to focus on the short-period wobbles. Over these three and a half months, the pole position traced small loops, ranging in size from that of a sheet of A4 [8-1/2x11 inch] paper down to that of a cell phone, and it remained within a one meter [yard] square during these four months. ” [Quoted from American Geophysical Union press release]

“[...] We compared the observed polar motion with the contribution of atmosphere and oceans predicted from global atmospheric and oceanic analyses and models. We clearly see that centimeter level polar motion displacements during the 2005–2006 winter season are almost fully explained by major pressure events on the continents and on the ocean, especially a depression over Northern Europe in-phase with similar events over North America.” [Quoted from abstract of originating article in Geophysical Research Letters; full article: $9 for non-subscribers]

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motorway aires - Tavel nord aire, A9 : giant sundials

the web address for the article above is
https://www.abelard.org/news/science0607.php#wobbly_earth_030706

email email_abelard [at] abelard.org

© abelard, 2006, 03 july


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the address for this document is https://www.abelard.org/news/science0607.php

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