Science is Cool....

[Fish]

This is a repository for all cool scientific discussion and fascination. Scientific facts, theories, and overall cool scientific stuff that you'd like to share with others. Stuff that makes you smile and wonder at the amazing shit going on around us, that most people don't notice.

Post pictures, vidoes, stories, or links. Ask questions. Share science.

Why should I care?:

[Fish]

On rare occasions, colonoscopy patients sometimes have their large intestines explode, which I have to imagine would be quite messy.

Follow your doctor's advice guys, else your butthole could violently explode...

When people explode during colonoscopies

Few people, if any, look forward to colonoscopies. They're annoying to prepare for. (Liquid diet? No thank you.) They're invasive. (It's a camera. In your butt.) They're scary. (Even if it's just a routine screening, there's always a chance your doctor will find something up there that requires medical attention.) They may even be over-prescribed. And, as we learned at last week's Ig Nobel Awards Ceremony, sometimes colonoscopy patients go boom. Because we know you're curious, here's how that happens.

"Colonic gas explosions," as their name implies, occur inside a patient's colon. This stretch of guts is commonly known as the large intestine and makes up the last five feet or so of your intestinal canal, beginning at the bottom end of your small intestine and ending at your anus. Unlike your small intestine, which is largely responsible for digesting food and absorbing nutrients, one of the large intestine's most important roles is storing and eliminating fecal matter. It's also where farts are born. (And if the Internet has taught us anything, it's that farts can be flammable. Also, this.)

Housed in your large intestine are hundreds of species of beneficial bacteria that help digest those bits of food your small intestine misses. In the process, these bacteria generate a variety of gases, including carbon dioxide, oxygen, nitrogen, hydrogen and methane, to name a few. Some of these gasses are odorless. Others, (particularly ones containing sulfur), are not. Two of them — hydrogen and methane — also happen to be combustable. Given that the average person's bacteria produce between 1 and 4 pints of gas per day, a five-foot stretch of colon can pack some formidable explosive potential.

Fortunately, it takes a pretty special set of conditions to detonate an intestinal bomb, so only rarely does this potential actually get unleashed. According to a team of researchers led by Emmanuel Ben-Soussan (who last week was awarded an Ig Nobel prize in medicine for advising doctors on how to avoid gut-combustion), an explosion of colonic gasses requires three things:

1. The presence of combustible gases (hydrogen and/or methane)
2. The presence of combustive gas (oxygen)
3. Application of a heat source

Your bacteria provide the first two; electrocautery — a technique that uses heat to remove potentially cancerous intestinal growths known as polyps — provides the third. The perfect colonic storm would comprise a high concentration of hydrogen and/or methane (greater than 4% or 5%, respectively), plenty of oxygen and a piping-hot electrocautery tool.

Concentrations of hydrogen and methane in the colon can vary considerably (0.06%—47% and 0%—26%, respectively, according to this study). Taking these thresholds into consideration, it is estimated that almost half of colonoscopy patients with unprepared large intestines harbor potentially explosive concentrations of hydrogen and methane in their bowels.

And yet, a survey of the medical literature conducted by Ben-Soussan's team turned up just 20 cases of colonic gas explosion between 1952 and October 2006, only one of which was fatal. Why such a small number? Because if you read the last paragraph closely, you'll notice that the cited hydrogen and methane concentrations are high in unprepared (i.e. uncleaned) large intestines; and adequate bowel cleansing, as you might expect, is pretty common practice in colonoscopies. (Still, not all colon-cleansing solutions are created equal. Mannitol, once widely employed in the preparation of the large intestine for colonoscopies, has been shown to increase hydrogen and methane excretion. Its use, unsurprisingly, has been largely discontinued.)

As Ben-Boussan and colleagues point out: "following bowel preparation with a combination of clear liquids, cathartics, and enema, mean concentration of hydrogen... and methane" generally fall well below their minimal explosive concentrations:

An accumulation of colonic gas to potentially explosive concentrations due to poor colon preparation is considered an initiating factor in the complication of colonic gas explosion. Therefore, quality of bowel preparation as well as type of preparation and dietary restrictions are all essential for an uneventful therapeutic colonoscopy.

The upshot? While colonic explosion may be, as the researchers call it, "one of the most frightening [medical complications] of colonoscopy with electrocautery," it's also pretty damn rare. Here's to uneventful colonoscopies.

[Stewie]

Originally Posted by Fish

No offense to BEP, our resident homeopath nut...

After decades of studies of many hundreds of thousands of participants, evidence is quite clear that Vitamin and Mineral Supplements are nothing but a waste of money. And in some cases they can actually pose health risks.

Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements

Three articles in this issue address the role of vitamin and mineral supplements for preventing the occurrence or progression of chronic diseases. First, Fortmann and colleagues (1) systematically reviewed trial evidence to update the U.S. Preventive Services Task Force recommendation on the efficacy of vitamin supplements for primary prevention in community-dwelling adults with no nutritional deficiencies. After reviewing 3 trials of multivitamin supplements and 24 trials of single or paired vitamins that randomly assigned more than 400 000 participants, the authors concluded that there was no clear evidence of a beneficial effect of supplements on all-cause mortality, cardiovascular disease, or cancer.

Second, Grodstein and coworkers (2) evaluated the efficacy of a daily multivitamin to prevent cognitive decline among 5947 men aged 65 years or older participating in the Physicians’ Health Study II. After 12 years of follow-up, there were no differences between the multivitamin and placebo groups in overall cognitive performance or verbal memory. Adherence to the intervention was high, and the large sample size resulted in precise estimates showing that use of a multivitamin supplement in a well-nourished elderly population did not prevent cognitive decline. Grodstein and coworkers’ findings are compatible with a recent review (3) of 12 fair- to good-quality trials that evaluated dietary supplements, including multivitamins, B vitamins, vitamins E and C, and omega-3 fatty acids, in persons with mild cognitive impairment or mild to moderate dementia. None of the supplements improved cognitive function.

Third, Lamas and associates (4) assessed the potential benefits of a high-dose, 28-component multivitamin supplement in 1708 men and women with a previous myocardial infarction participating in TACT (Trial to Assess Chelation Therapy). After a median follow-up of 4.6 years, there was no significant difference in recurrent cardiovascular events with multivitamins compared with placebo (hazard ratio, 0.89 [95% CI, 0.75 to 1.07]). The trial was limited by high rates of nonadherence and dropouts.

Other reviews and guidelines that have appraised the role of vitamin and mineral supplements in primary or secondary prevention of chronic disease have consistently found null results or possible harms (5–6). Evidence involving tens of thousands of people randomly assigned in many clinical trials shows that β-carotene, vitamin E, and possibly high doses of vitamin A supplements increase mortality (6–7) and that other antioxidants (6), folic acid and B vitamins (8), and multivitamin supplements (1, 5) have no clear benefit.

Despite sobering evidence of no benefit or possible harm, use of multivitamin supplements increased among U.S. adults from 30% between 1988 to 1994 to 39% between 2003 to 2006, while overall use of dietary supplements increased from 42% to 53% (9). Longitudinal and secular trends show a steady increase in multivitamin supplement use and a decline in use of some individual supplements, such as β-carotene and vitamin E. The decline in use of β-carotene and vitamin E supplements followed reports of adverse outcomes in lung cancer and all-cause mortality, respectively. In contrast, sales of multivitamins and other supplements have not been affected by major studies with null results, and the U.S. supplement industry continues to grow, reaching $28 billion in annual sales in 2010. Similar trends have been observed in the United Kingdom and in other European countries.

The large body of accumulated evidence has important public health and clinical implications. Evidence is sufficient to advise against routine supplementation, and we should translate null and negative findings into action. The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided. This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States and in other countries (9).

The evidence also has implications for research. Antioxidants, folic acid, and B vitamins are harmful or ineffective for chronic disease prevention, and further large prevention trials are no longer justified. Vitamin D supplementation, however, is an open area of investigation, particularly in deficient persons. Clinical trials have been equivocal and sometimes contradictory. For example, supplemental vitamin D, which might prevent falls in older persons, reduced the risk for falls in a few trials, had no effect in most trials, and increased falls in 1 trial. Although future studies are needed to clarify the appropriate use of vitamin D supplementation, current widespread use is not based on solid evidence that benefits outweigh harms (10).

With respect to multivitamins, the studies published in this issue and previous trials indicate no substantial health benefit. This evidence, combined with biological considerations, suggests that any effect, either beneficial or harmful, is probably small. As we learned from voluminous trial data on vitamin E, however, clinical trials are not well-suited to identify very small effects, and future trials of multivitamins for chronic disease prevention in well-nourished populations are likely to be futile.

In conclusion, β-carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful. Other antioxidants, folic acid and B vitamins, and multivitamin and mineral supplements are ineffective for preventing mortality or morbidity due to major chronic diseases. Although available evidence does not rule out small benefits or harms or large benefits or harms in a small subgroup of the population, we believe that the case is closed— supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful. These vitamins should not be used for chronic disease prevention. Enough is enough.

I read this about a week ago. The next day they wrote an article about the link between Vitamin E deficiency and Alzheimer's.

Whether taking a multi-vitamin is necessary or not for healthy people is debatable, but there are known problems with a lack of certain vitamins. It's especially notable in the elderly and the young due to diets and food intake. We know the consequences of Vitamins A, C, D and E deficiencies. A normal multi-vitamin (sans ridiculous doses) costs about four cents per day. That's not unreasonable for someone that eats very little (elderly) or has a poor diet.

[Stewie]

Originally Posted by Dave Lane

I've read all his stuff, it's interesting really he's relying on massive eruptions in the Siberian area and possibly India caused a massive reduction in the dinosaur population and possibly they were already dead. I doubt this is the case but reduction is likely.

And as for not finding bones at the KT boundary it's pretty apparent to anyone that studied the impact that the entire surface of the earth was incinerated in ways you have to study to understand. Surface of the earth was probably around 25000 degrees for a period of time. Only underground and deep ocean animals survived.

Bakker was on a recent episode on Discovery Channel... I think it was Discovery. He stated the 20 million year extinction was mainly due to disease spread by parasites and insects.

[Fish]

Originally Posted by Stewie

I read this about a week ago. The next day they wrote an article about the link between Vitamin E deficiency and Alzheimer's.

Whether taking a multi-vitamin is necessary or not for healthy people is debatable, but there are known problems with a lack of certain vitamins. It's especially notable in the elderly and the young due to diets and food intake. We know the consequences of Vitamins A, C, D and E deficiencies. A normal multi-vitamin (sans ridiculous doses) costs about four cents per day. That's not unreasonable for someone that eats very little (elderly) or has a poor diet.

Well.. the the article makes a pretty strong case that those vitamin and supplement pills were ineffective for primary prevention in community-dwelling adults with no nutritional deficiencies. The cost wasn't the issue, it was the fact that there were no benefits for the majority of people.

I've read the Vitamin E/Alzheimers link as well, and it's not as simple as what you allude to. In that study, the link they found was from very high doses of VitE. Much more than what you'd find in a retail supplement. It was borderline dangerous intakes of VitE, which medicine has already shown, can have damaging effects. The scientists doing the VitE/Alzheimers experiment even cautioned against the interpretation of the results:

No one should rush out and buy vitamin E, several doctors warned. It failed to prevent healthy people from developing dementia or to help those with mild impairment ("pre-Alzheimer's") in other studies, and one suggested it might even be harmful.

In addition, they noted that taking VitE wouldn't prevent Alzheimers, it simply slowed it a bit. And if they took any other Alzheimers medication as well, they got no benefit from the VitE.

Vitamin deficiencies should be addressed using food. Not pills. That was an important point of the supplement article. Pills are a terrible intake method, and it's proven not to work in the overwhelming majority of cases. That doesn't mean they're completely worthless. Just that they're worthless for the majority of people that take them.

[Stewie]

Originally Posted by Fish

Well.. the the article makes a pretty strong case that those vitamin and supplement pills were ineffective for primary prevention in community-dwelling adults with no nutritional deficiencies. The cost wasn't the issue, it was the fact that there were no benefits for the majority of people.

I've read the Vitamin E/Alzheimers link as well, and it's not as simple as what you allude to. In that study, the link they found was from very high doses of VitE. Much more than what you'd find in a retail supplement. It was borderline dangerous intakes of VitE, which medicine has already shown, can have damaging effects. The scientists doing the VitE/Alzheimers experiment even cautioned against the interpretation of the results:



In addition, they noted that taking VitE wouldn't prevent Alzheimers, it simply slowed it a bit. And if they took any other Alzheimers medication as well, they got no benefit from the VitE.

Vitamin deficiencies should be addressed using food. Not pills. That was an important point of the supplement article. Pills are a terrible intake method, and it's proven not to work in the overwhelming majority of cases. That doesn't mean they're completely worthless. Just that they're worthless for the majority of people that take them.

The point is many elderly don't get enough vitamins from food intake. Who cares if healthy people take a multi-vitamin?

Instead of focusing on a 4 cent vitamin, why don't these people focus on the multi-billion dollar statin business. They've never proven any benefit and they've been on the market for decades.

[Fish]

Originally Posted by Stewie

The point is many elderly don't get enough vitamins from food intake. Who cares if healthy people take a multi-vitamin?

Instead of focusing on a 4 cent vitamin, why don't these people focus on the multi-billion dollar statin business. They've never proven any benefit and they've been on the market for decades.

Well that is a dietary condition, and should probably be addressed that way whenever possible. The pill form is a really really poor way to get those nutrients into the body and isn't a sufficient replacement.

I completely agree with the statin business. Been going through that exact thing with my mom.

[Pants]

Originally Posted by Fish

****ing much too much.

[Discuss Thrower]

YouTube Doubler is a great tool for us to learn about science, folks...

[Shogun]

Not so much Science, but more Cool and Fascinating Biology

World's most beautiful beach glows like millions of stars at night



Flickr user hala065 brings us these otherworldly images of a beach in the Maldives that glows with millions of pinpoints of glowing blue. The light from these bioluminescent phytoplankton looks like a fantastic starry sky somewhere deep in the universe. It's mesmerizing.



First spotted by Colossal, these phenomenal photographs show how the glowing phytoplankton light the entire beach where the waves hit the sand and agitate the little creatures. They also light up under pressure, like when people walk across the sand.

[BigMeatballDave]

Uh, biology is science.

[Shogun]

Lol. Thats not quite how I meant to say it

[Fish]

Seriously?

How Far Can the Human Eye See?



The Earth's surface curves out of sight at a distance of 3.1 miles, or 5 kilometers. But our visual acuity extends far beyond the horizon. If Earth were flat, or if you were standing atop a mountain surveying a larger-than-usual patch of the planet, you could perceive bright lights hundreds of miles distant. On a dark night, you could even see a candle flame flickering up to 30 mi. (48 km) away.

How far the human eye can see depends on how many particles of light, or photons, a distant object emits. The farthest object visible with the naked eye is the Andromeda galaxy, located an astonishing 2.6 million light-years from Earth. The galaxy's 1 trillion stars collectively emit enough light for a few thousand photons to hit each square centimeter of Earth every second; on a dark night, that's plenty to excite our retinas.

Back in 1941, the vision scientist Selig Hecht and his colleagues at Columbia University made what is still considered a reliable measurement of the "absolute threshold" of vision — the minimum number of photons that must strike our retinas in order to elicit an awareness of visual perception. The experiment probed the threshold under ideal conditions: study participants' eyes were given time to adapt to total darkness, the flash of light acting as a stimulus had a (blue-green) wavelength of 510 nanometers, to which our eyes are most sensitive, and this light was aimed at the periphery of the retina, which is richest in light-detecting rod cells.

The scientists found that for study participants to perceive such a flash of light more than half the time, the subjects required between 54 and 148 photons to hit their eyeballs. Based on measurements of retinal absorption, the scientists calculated that a factor of 10 fewer photons were actually being absorbed by the participant's rod cells. Thus, the absorption of 5 to 14 photons, or, equivalently, the activation of just 5 to 14 rod cells, tells your brain you're seeing something. [Why Do We See in 3-D?]

"This is indeed a small number of chemical events," Hecht and his colleagues concluded in their seminal paper on the subject.

Considering the absolute threshold, the brightness of a candle flame, and the way a glowing object dims according to the square of the distance away from it, vision scientists conclude that one could make out the faint glimmer of a candle flame up to 30 miles away.

But how far away can we perceive that an object is more than just a twinkle of light? For something to appear spatially extended rather than point-like, light from it must stimulate at least two adjacent cone cells — the elements in our eyes that produce color vision. Under ideal conditions, an object must subtend an angle of at least 1 arcminute, or one sixtieth of a degree, in order to excite adjacent cones. (This angular measure stays the same regardless of whether an object is nearby or far away; distant objects must be much larger to subtend the same angle as near objects). The full moon is 30 arcminutes across, whereas Venus is barely resolvable as an extended object at around 1 arcminute across.

Human-scale objects are resolvable as extended objects from a distance of just under 2 miles (3 km). For example, at that distance, we would just be able to make out two distinct headlights on a car.

[Donger]

Nasa says Mars mystery rock that ‘appeared’ from nowhere is ‘like nothing we’ve seen before’

http://www.independent.co.uk/news/sc...e-9070323.html

A mysterious rock which appeared in front of the Opportunity rover is "like nothing we've ever seen before", according to Mars exploration scientists at Nasa.

Experts said they were "completely confused" by both the origins and makeup of the object, which is currently being investigated by Opportunity's various measuring instruments.

Astronomers noticed the new rock had "appeared" without any explanation on an outcrop which had been empty just days earlier. The rover has been stuck photographing the same region of Mars for more than a month due to bad weather, with scientists at the Jet Propulsion Laboratory (JPL) in California monitoring the images it sends.

Nasa issued a Mars status report entitled "encountering a surprise", and lead Mars Exploration rover scientist Steve Squyres told a JPL event it seems the planet literally "keeps throwing new things at us".

He said the images, from 12 Martian days apart, were from no more than a couple of weeks ago. "We saw this rock just sitting here. It looks white around the edge in the middle and there’s a low spot in the centre that's dark red - it looks like a jelly doughnut.

"And it appeared, just plain appeared at that spot - and we haven't ever driven over that spot."

[ChiefRocka]

Originally Posted by Donger

Nasa says Mars mystery rock that ‘appeared’ from nowhere is ‘like nothing we’ve seen before’

http://www.independent.co.uk/news/sc...e-9070323.html

A mysterious rock which appeared in front of the Opportunity rover is "like nothing we've ever seen before", according to Mars exploration scientists at Nasa.

Experts said they were "completely confused" by both the origins and makeup of the object, which is currently being investigated by Opportunity's various measuring instruments.

Astronomers noticed the new rock had "appeared" without any explanation on an outcrop which had been empty just days earlier. The rover has been stuck photographing the same region of Mars for more than a month due to bad weather, with scientists at the Jet Propulsion Laboratory (JPL) in California monitoring the images it sends.

Nasa issued a Mars status report entitled "encountering a surprise", and lead Mars Exploration rover scientist Steve Squyres told a JPL event it seems the planet literally "keeps throwing new things at us".

He said the images, from 12 Martian days apart, were from no more than a couple of weeks ago. "We saw this rock just sitting here. It looks white around the edge in the middle and there’s a low spot in the centre that's dark red - it looks like a jelly doughnut.

"And it appeared, just plain appeared at that spot - and we haven't ever driven over that spot."

Alien surveillance gone terribly wrong.

[Donger]

That's pretty neat. You can see the outline of it in the picture on the left, I think.