Monday, March 31, 2008

Build your own Rebreather for $100 ...

... using a hot water bottle: A HOT WATER BOTTLE PENDULUM
Warning Warning Warning


You can die from too much oxygen by using pure oxygen below 20 feet of seawater. You can die from too little oxygen. You can drown. Screw up and you are likely to die. When you enter the water, you are on your own, even if a buddy is nearby. You alone must make the decision that you are capable of using a rebreather, you are up to the dive, and that your equipment is up to the dive. Even extensive open circuit experience will not prepare you for the details inherent with staying alive underwater on a rebreather. If you have any concerns about your abilities, take a course or do not dive. If you are foolish enough to dive rebreathers, be aware that it is a case of Evolution in Action. It is an effective sorting out process that has created many unhappy widows, mothers, and children. I recommend against it. This project is described for your amusement only. It is not the intent of the author that you build one of these and go out and kill yourself. As I have shown it, if you take the mouthpiece out of your mouth, water will flow in filling the scrubber, and your next breath is a caustic cocktail. If you don't know what you are doing, don't try this one at home. If you know what you are doing, I am sure you have a rig that makes this one look childish.

Information Storage in the Brain

Compartmentalized dendritic plasticity and input feature storage in neurons in Nature.
Although information storage in the central nervous system is thought to be primarily mediated by various forms of synaptic plasticity, other mechanisms, such as modifications in membrane excitability, are available. Local dendritic spikes are nonlinear voltage events that are initiated within dendritic branches by spatially clustered and temporally synchronous synaptic input. That local spikes selectively respond only to appropriately correlated input allows them to function as input feature detectors and potentially as powerful information storage mechanisms. However, it is currently unknown whether any effective form of local dendritic spike plasticity exists. Here we show that the coupling between local dendritic spikes and the soma of rat hippocampal CA1 pyramidal neurons can be modified in a branch-specific manner through an N-methyl-d-aspartate receptor (NMDAR)-dependent regulation of dendritic Kv4.2 potassium channels. These data suggest that compartmentalized changes in branch excitability could store multiple complex features of synaptic input, such as their spatio-temporal correlation. We propose that this 'branch strength potentiation' represents a previously unknown form of information storage that is distinct from that produced by changes in synaptic efficacy both at the mechanistic level and in the type of information stored.

Traffic Jams Just Happen

Traffic Jams Happen, Get Used to It in Science Magazine.

Too many cars equals a traffic jam, even without an external cause.
Credit: Mathematical Society of Traffic Flow

Precision Clocks

A Milestone in Time Keeping in Science Magazine.
Researchers have made atomic clocks so precise that effects of general relativity are on the verge of complicating the concept of keeping time.

So much for "junk DNA"

Only 1-2% of the DNA in humans and other higher organisms appears to code for proteins. But the remaining so-called "junk DNA" may be transribed into RNA with numerous functions.
The Eukaryotic Genome as an RNA Machine in Science Magazine.
The past few years have revealed that the genomes of all studied eukaryotes are almost entirely transcribed, generating an enormous number of non–protein-coding RNAs (ncRNAs). In parallel, it is increasingly evident that many of these RNAs have regulatory functions. Here, we highlight recent advances that illustrate the diversity of ncRNA control of genome dynamics, cell biology, and developmental programming.

Sunday, March 30, 2008

Cliche Mashups

Growing Pangs: growing pains / birth pangs --- attributed to Condi Rice

No Shit Jose: No Shit Sherlock / No Way Jose

Don't Bite the F---ing Horse: Don't Bite the Hand That Feeds You / Don't Look a Gift Horse in the Mouth

Green Behind the Ears: green / wet behind the ears --- Barack Obama in 2008 Presidential Debate

"They create a desolation and call it peace"

From Tacitus, Agricola, a rebel's comment about Rome.

Saturday, March 29, 2008

Science as Art Competition

Image: Fanny Beron, École Polytechnique de Montréal, Montréal, Canada)
Science as Art competition held at the 2007 Materials Research Society (MRS) Fall Meeting

Speed Camera Irony

Cities that have installed speed cameras are discovering motorists are driving slower, which is decreasing revenues from fines. So they're turning the cameras off.

Schneier on Security

You First

Tuesday, March 25, 2008

Galaxy Rotation

Disk galaxy rotation curves and dark matter distribution
After explaining the motivation for this article, we briefly recapitulate the methods used to determine somewhat coarsely the rotation curves of our Milky Way Galaxy and other spiral galaxies, especially in their outer parts, and the results of applying these methods. Recent observations and models of the very inner central parts of galaxian rotation curves are only briefly described. We then present the essential Newtonian theory of (disk) galaxy rotation curves. The next two sections present two numerical simulation schemes and brief results. Application of modified Newtonian dynamics to the outer parts of disk galaxies is then described. Finally, attempts to apply Einsteinian general relativity to the dynamics are summarized. The article ends with a summary and prospects for further work in this area

Galaxy Zoo

Galaxy Zoo: The large-scale spin statistics of spiral galaxies in the Sloan Digital Sky Survey
We re-examine the evidence for a violation of large-scale statistical isotropy in the distribution of projected spin vectors of spiral galaxies. We have a sample of $\sim 37,000$ spiral galaxies from the Sloan Digital Sky Survey, with their line of sight spin direction confidently classified by members of the public through the online project Galaxy Zoo. After establishing and correcting for a certain level of bias in our handedness results we find the winding sense of the galaxies to be consistent with statistical isotropy. In particular we find no significant dipole signal, and thus no evidence for overall preferred handedness of the Universe. We compare this result to those of other authors and conclude that these may also be affected and explained by a bias effect.

Nature's Brightest Explostion

Observations of the Naked-Eye GRB 080319B: Implications of Nature's Brightest Explosion
The first gamma-ray burst (GRB) confirmed to be bright enough to be seen with the naked eye, GRB 080319B, allowed for exquisite follow-up across the electromagnetic spectrum. We present our detailed optical and infrared observations of the afterglow, consisting of over 5000 images starting 122 s after the GRB trigger, in concert with our own analysis of the Swift UVOT, BAT, and XRT data. The event is extreme not only in observed properties but intrinsically: it was the most luminous ever recorded at optical wavelengths and had an exceedingly high isotropic-equivalent energy release in gamma-rays

The French

There's a charming article about the French in the New York Times A Guide to the French. Handle With Care
“Every man has two countries, his own and France,” says a character in a play by the 19th- century poet and playwright Henri de Bornier.
“The most beautiful makeup for a woman is passion,” Yves Saint Laurent once said. “But cosmetics are easier to buy.”

Saturday, March 22, 2008

Giant Undersea Robot

The UT-1 ‘Ultra Trencher’ is the world’s most powerful jetting
trencher: pdf technical specification.

New Form of Vision Discovered

Mantis Shrimps can detect polarized light, an ability previously unknown: Science Magazine.

They are also really cute.

Thursday, March 20, 2008

Crayon Physics

Cute video demonstration of the Crayon Physics program. You will smile.

Tuesday, March 18, 2008

Cocteau Twins

Recently I've been listening to the dreamy 80/90's Scottish band Cocteau Twins - a lot. I wondered about the "lyrics" which seem like they're in some unknown language.

Here's a wonderful collection of comments on the lyrics by singer Liz Fraser.

Monday, March 17, 2008

Droll Retort in "Not Even Wrong Blog"

In the comments of Peter Woit's blog:

Eric Says:
March 9th, 2008 at 10:25 pm
At least 99% of the 10^500 possible vacua are complete garbage and can be ruled out easily. Thus, the regions of the landscape for which realistic vacua may arise is limited. If string theory is the right theory, then at least one of these vacua is our universe and it can be found with a focused effort.

Peter Woit Says:

March 9th, 2008 at 10:30 pm

Once you rule out the 99% garbage, you’re left with 10^498 vacua to study….

Fundamental Constants

Fundamental Constants a preprint by Frank Wilczek, has a nice discussion of the fundamental constants of physics as well as systems of units.
There's a nice quote attributed to Einstein:
I would like to state a theorem which at present can not be based upon anything more than upon a faith in the simplicity, i.e., intelligibility, of nature: there are no arbitrary constants ... that is to say, nature is so constituted that it is possible logically to lay down such strongly determined laws that within these laws only rationally completely determined constants occur (not constants, therefore, whose numerical value could be changed without destroying the theory).

Gravity poses some problems:
Straightforward estimation suggests that empty space should weigh several orders of magnitude of orders of magnitude (no misprint here!) more than it does. It “should” be much denser than a neutron star, for example. The expected energy of empty space acts like dark energy, with negative pressure, but far more is expected than is observed.

And there are other less than pretty parts as well:
The flavor/Higgs sector of the standard model is, by a wide margin, its least satisfactory part. Whether judged by the large number of independent parameters or by the small number of powerful ideas it contains, our theory of this sector does not attain the same level as we’ve reached in the other sectors. This part truly deserves to be called a “model” rather than a “theory”.

Sunday, March 16, 2008

Cell Phone Scams

I'm forced to admire the scams described in The Anatomy of a Vishing Scam.
Ah, the irony. Here we have the very accounts these entities use to respond to complaints about fraudulent activity being used to perpetrate fraudulent activity.

Friday, March 14, 2008

Blind Chance

Blind Chance: a brilliant 1981 Polish film by Krzysztof Kieślowski.

Bacterial Snowmakers

Ubiquity of Biological Ice Nucleators in Snowfall: is ice nucleation, essential to snow and rain, mainly catalyzed by bacteria?

Stretching and Flexibility

To Stretch or Not to Stretch? The Answer Is Elastic in the New York Times on March 13, 2008.

But distance runners do not benefit from being flexible, he found. The most efficient runners, those who exerted the least effort to maintain a pace, were the stiffest.