Archive for the 'Body' Category

Cold but Safe

The gloves don’t work

Scaling laws, related to why kids may be better off with mittens, and why cold fingers on a child also tells us we won’t be attacked by giant ants.

Now, my daughter is significantly smaller than me, so overall she gets colder more quickly anyway. And, given that “Gloves that work” features on her Christmas list, an equally valid answer to her question could have been “Because you need better gloves, and I’m a bad dad.” But the physics happens too.

How Many Metabols Does that Cost, Anyway?

Arm swinging reduces the metabolic cost of running

Swinging the arms clearly saves energy for runners, and helps to minimise the amount that we rotate the body while swinging our legs, which led Arellano and Kram to wonder whether the metabolic benefits of arm swinging outweigh the cost of carrying the limbs.


Choprafication: The act of adding of “quantum” to a description to make it sound all science-y and stuff

- Me (no relation)

Quantum and Consciousness Often Mean Nonsense

I hold degrees in physics and have spent a lot of time learning and teaching quantum mechanics. Nonphysicists seem to have the impression that quantum physics is really esoteric, with those who study it spending their time debating the nature of reality. In truth, most of a quantum mechanics class is lots and lots of math, in the service of using a particle’s quantum state—the bundle of physical properties such as position, energy, spin, and the like—to describe the outcomes of experiments. Sure, there’s some weird stuff and it’s fun to talk about, but quantum mechanics is aimed at being practical (ideally, at least).

Yet the mysterious aspects of quantum physics and consciousness have inspired many people to speculate freely. The worst offenders will even say that because we don’t fully understand either field, they must be related problems. It sounds good at first: We don’t know exactly how some things in quantum physics work, we don’t know exactly how to go from the brain to consciousness, so maybe consciousness is quantum.

The problem with this idea? It’s almost certainly wrong.

Even a Tie is a Win

Could This 3-D Printed Cast Really Heal Bones Faster?

Having endured plaster and fiberglass casts in my youth (when my ego, overestimating my limited athletic ability, was writing checks my body couldn’t cash), I can say that even if the ultrasound part of this is not effective, having a cast where the limb can “breathe” would be a huge win, in terms of bathing and accessing itchy areas.

Orange You Glad I Didn’t Say Banana?

How Radioactive (In Bananas) is the Room You’re Sitting in Right Now?

They only mention building materials in the paper’s abstract, so this ignores C-14 decay, which is important because people are radioactive, too — any accounting of the radioactivity of a room should be compared with what you can’t avoid because it’s an internal dose.

License to Killjoy

Did James Bond Want His Martinis ‘Shaken, Not Stirred’ Because Of An Alcohol-Induced Tremor?

James Bond’s famous catchphrase “shaken, not stirred” may have stemmed from his inability to stir his drinks due to an alcohol-induced tremor affecting his hands, researchers reveal in a new, tongue-in-cheek medical report.

Such a tremor would be likely in a spy who drank more than four times the recommended limit of alcohol throughout his missions, they said, writing in a special Christmas issue of the BMJ — a lighthearted edition of the medical journal that includes real research.

As the HuffPo notes, this is not serious (though this has gotten a lot of play and not all articles make this observation), but I’m going to be a killjoy anyway and apply Betteridge’s Law: the answer is no.

It’s not because of the silliness of applying medical analysis to a frikkin’ fictional character, or that the fictional data is anecdotal in nature, or even that the fictional empirical evidence says no, because Bond was a crack shot with his pistol. It’s because Bond was ordering the drinks, not mixing them himself. A tremor is moot.

But there’s more to this. One version I read (and unfortunately I can’t find the link to the specific article, but several versions are out there) included a description that a properly mixed martini would be stirred, and with a thin wooden spoon, rather than a metal one which would raise the temperature of the drink. This is baloney, but probably a case of right answer, wrong reason. The reasoning is wrong, because the drink is mixed with ice, so the final temperature is going to be the same — probably the temperature of the ice cubes.

I say probably because this is most likely not the case like where you have a pure water/ice mixture, which stays at 0 ºC because of the phase change going on. In the drink you will have a mixture or alcohol and water, and the freezing point will be lower. For a 50/50 mix, the freezing point will be -32 ºC, and the ice is probably warmer than that — freezers don’t generally get that cold. (dissolving things in water lowers the freezing point, and this is a colligative property, meaning it depends on how much stuff you have dissolved. It’s why putting salt on ice tends to melt it if you’re near 0 ºC: there’s always a little water, and when the salt dissolves the solution freezes at a lower temperature, which allows the ice to melt)

If the final temperature is independent of the spoon type, then what’s right about this? The metal spoon will absorb more energy from the solution, so while the final temperature is unaffected, this will tend to melt more of the ice, and that will water down the drink. From a thermodynamic standpoint that is more likely why you want to use a wooden spoon. Some years ago there was an episode of the West Wing where the president was complaining about “shaken, not stirred” in the context that shaking makes the ice chip, and small chips won’t get strained out when you pour the drink, which also has the effect of watering the drink down.

All of this reminds me that my parents used to complain about “shaken, not stirred” when we’d see these movies on TV. My dad was a bartender at one point, and the complaint (from both) was that shaking would bruise the alcohol. I knew enough science to know that this could not be literally true, but I never got an explanation of what “bruising” really was; I assumed that it was a euphemism for something undesirable and left it at that. Now that the internet exists, I can find something calling itself the martini FAQ and see that this is a matter of aeration.

Another addendum to this is that the link I can’t find had in it a link to some martini information, in which it was claimed that a dry martini had a lot of dry vermouth in it, but claimed that recently this had changed to mean very little (or no) vermouth. Well, that doesn’t jibe with the bartender joke I know where someone asks for a dry martini and the bartender asks how dry they want it. To which the customer responds, “Just whisper ‘vermouth’ over the glass.” That joke is probably older than I am, so no vermouth = dry is not a recent trend.

Knock Me Down With a Feather*

*Knocking me down with a feather is not intended to diagnose, treat, cure or prevent disease.

Copper Bracelets, Magnetic Wrist Straps Fail to Help Rheumatoid Arthritis

I had noted a long time ago that based on the proposed mechanism, there was no basis to expect magnetic bracelets to work. No real surprise that they don’t.

The research published in PLOS ONE, show that both the standard magnetic wrist strap and the copper bracelet provided no meaningful therapeutic effects beyond those of a placebo, which was not magnetic and did not contain copper.

I like that they point this out about the placebos.

It’s No “Alan Parsons Project”

Physics Buzz and Uncertain Principles take on the plausibility of a purported x-ray death beam that was recently in the news.

Fermi Problem Friday: X-Ray Assassins

On “Death Rays”

Goldilocks and the Laser Pointer

Most Laser Pointers Are Too Strong

This seems a little … unfinished.

Neither the story nor the referenced study mention if the lasers are all supposed to be 5 mW and thus class IIIa (or 3R), or if, as one link claims, there are higher-power lasers that aren’t limited by this threshold because they aren’t marketed as laser pointers. Or if the violation isn’t that they are claiming 5 mW and exceeding it, but rather they are incorrectly (and presumably illegally) calling the more powerful devices laser pointers and listing them as class III/3R.

Then there was this claim.

Green lasers use a shorter wavelength of light than red ones, making them brighter and more dangerous.

This was lifted from the included link, but lacking the detail found in another link. Green lasers aren’t brighter simply because they have a shorter wavelength. If that were true, a blue laser would be brighter still, and they aren’t. In fact green lasers must fire fewer photons per second at you than red lasers do, if they all have the same power. What makes the green brighter is your eye. The eye’s response to light isn’t constant across the spectrum — it’s much better at absorbing (and thus detecting) green light then either red or blue, so the green light has a better chance at doing damage.

Seeing Red. Or the Opposite.

Why Do Doctors Wear Green Or Blue Scrubs?

Green could help physicians see better for two reasons. First, looking at blue or green can refresh a doctor’s vision of red things, including the bloody innards of a patient during surgery. The brain interprets colors relative to each other. If a surgeon stares at something that’s red and pink, he becomes desensitized to it. The red signal in the brain actually fades, which could make it harder to see the nuances of the human body. Looking at something green from time to time can keep someone’s eyes more sensitive to variations in red

I’ve noticed the opposite effect in the lab; when I work with lasers I wear laser safety glasses, which block the wavelength being used, and for quite a while this has been in the NIR. The glasses block everything above ~650 nm, so the glasses look bluish-green and deprives your eyes of any red light. After taking them off, everything has a pink hue to it.


Synaesthesia and savant syndrome: are we all superhuman?

“There are numerous different kinds of synaesthesia,” Professor Brogaard began. “One of the most common forms is grapheme-colour synaesthesia, which is where letters or numbers give rise to specific colours. There are people who have so-called mirror-touch synaesthesia who experience the feeling of being touched when they see other people being touched. There are others who see colours when they taste something and some people even see colours when they feel fear.”

I Know What You Did Last Summer, Based on Isotopic Ratios in Your Hair and Fingernails

Stable Isotopes in Forensics

[L]et’s follow a raindrop from the Pacific Ocean to Saltair Sally’s strand of hair. When water evaporates from the ocean, the heavier molecules containing deuterium and tritium and oxygen-18 do not evaporate as readily and are left behind in greater numbers. As droplets gather into clouds and eventually fall as rain, the heavier molecules fall first. This means rainwater in regions closer to oceans and large lakes is isotopically enriched compared with regions farther inland. Isotope levels are again fractionated in drinking water depending on whether it is drawn from wells or reservoirs (lighter isotopes more easily evaporate from the surface of reservoirs). Currently, scientists are busily creating maps of various isotopes’ distributions to assist investigators.
If Saltair Sally had been in Salt Lake City in the weeks preceding her death, the hair closest to her scalp would reflect the isotopic signature of Salt Lake City’s local water supply. If she had been in, say, Seattle instead, her hair’s isotopic composition would be different, giving investigators a valuable clue.

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