Tuesday, December 13, 2011

She chills me out - thanks to my oxytocin receptor gene

Can your girlfriend help chill you out before some stressful activity? It probably depends on whether you have the G allele of the rs53576 single nucleotide polymorphism of the oxytocin receptor gene, according to this study in PNAS: Common oxytocin receptor gene (OXTR) polymorphism and social support interact to reduce stress in humans . See a previous blog post You're Nice, He's a Jerk - is it because of your Oxycotin receptor genes? for more fascinating research about the behavioral differences attributed to different variants of this gene.

Monday, December 12, 2011

Step up to the bar - the Milky Way bar

Apparently there's a bar/box shaped concentration of stars in the center of our Milky Way galaxy.

This central bar is oriented about 20 degrees from our line of sight to the center of the galaxy - so the diagram above doesn't look quite right to me. The bar seems to rotate like a cylinder - rigidly. This type of structure is typical of many galaxies, not just ours. There's evidence that our bar is a fairly uniform population, there's no real evidence of recent mergers. That's inconsistent with a model of galaxy formation by merger, which seemed to work well for elliptical galaxies. Our Milky Way is a barred spiral - different from ellipticals - but it was thought for a while that the central bulge of spirals might have formed a similar manner. Now that no longer appears to be true.
For some scientific details see The Bulge Radial Velocity Assay (BRAVA): II. Complete Sample and Data Release and OUR MILKY WAY AS A PURE-DISK GALAXY—A CHALLENGE FOR GALAXY FORMATION.

Saturday, December 10, 2011

Magma

Magma is melted rock, when it reaches the surface it's called lava. Magma comes from deep underground where it's much hotter, so the rock down there is melted, isn't it? Well not really. Beneath the earth's crust is the mantle and it's by and large solid too. The difference between the crust and the mantle is mainly chemical, they are both solid.
So then, where does magma come from, how does all that rock melt and create such appalling displays at volcanic eruptions?

As it turns out, magma forms by decompression melting. Not only is the temperature higher deep underground in the mantle, the pressure is also terrifically greater. We usually think of solids melting when the temperature rises, but they can also melt when the pressure decreases. Peridotite the mantle rock, is solid at the high pressures and temperatures found down in the mantle, but it will melt when the pressure is released by an opening to the surface - a volcano.

The Mid-Pleistocene Transition

Before 1.2 million years ago, glacial cycles had a 40,000 year periodicity. But in the past 700,000 years the ice-age cycle has been around 100,000 years. There was a transitional period in between. See Atmospheric Carbon Dioxide Concentration Across the Mid-Pleistocene Transition from 2009 in Science magazine. There is a 41,000 year periodicity in the earth's orbit which could explain the earlier periodicity (see Milankovitch cycles), but the the transition to the more recent 100,000 year cycle is currently rather mysterious.

Tuesday, December 06, 2011

Type Ia Supernovae and the discovery of Cosmic Acceleration

It's not so easy to figure out the distance to far away objects in the sky - see an older post on the cosmic distance ladder. However, it's possible for even beginning astronomy students to climb the First Three Rungs of the Cosmological Distance Ladder. The top of the ladder isn't so easy though. The 2011 Nobel Prize in Physics was awarded for "for the discovery of the accelerating expansion of the Universe through observations of distant supernovae". A key element of that discovery was the use of Type Ia supernova to determine distances. Type Ia supernova are supposed to the explosion of a white dwarf star, conveniently it seems to be possible to determine the absolute luminosity of those explosions, which indicates the actual distance.

The preprint Type Ia Supernovae and the discovery of the Cosmic Acceleration is a nice explanation of the history of this discovery by Alejandro Clocchiatti a member of one of the groups which made the discovery - the High-z Supernova Search Team.

Kepler's supernova

Monday, December 05, 2011

Hank Paulson: Facts and Figures - or Fiction?

Henry Paulson has had a distinguished career as CEO of Goldman Sachs and U.S. Secretary of the Treasury under President George W. Bush. As Treasury Secretary he was a key figure in the 2007-2009 financial crisis.
He's also known as an avid nature lover. In the article Birds and Bankers in the New Yorker he's quoted as saying, "The Amazon dumps enough fresh water in the ocean every hour to fill one Lake Superior.”
However, according to Wikipedia:
the water volume of Lake Superior is 12,000 cubic kilometers;
the average discharge of the Amazon River is approximately 209,000 cubic meters per second.
Based on those figures, according to my calculations it would actually take approximately 15,948 hours (1.82 years) for the Amazon River to discharge enough fresh water to fill Lake Superior.
I hope Secretary Paulson had superior sources of information while discharging his duties during the financial crisis.

Sunday, December 04, 2011

You're Nice, He's a Jerk - is it because of your Oxycotin receptor genes?

A study published in PNAS: Thin-slicing study of the oxytocin receptor (OXTR) gene and the evaluation and expression of the prosocial disposition indicates that individual differences in social behavior are correlated with variants of their Oxycotin receptor genes. Previously, another study in PNAS: Oxytocin receptor gene (OXTR) is related to psychological resources indicated that variation in this gene was also related to other personality traits. Forget about horoscopes, find out whether your potential mate has the A or G allele of the oxytocin receptor (OXTR) SNP rs53576!
Oxytocin is the "love hormone" associated with maternal and sexual behavior.

Monday, November 28, 2011

Gliding Along the Alps for Eleven Hours


Did You Wonder How a Plane Stayed Up for 11 Hours With No Engine? an article by James Fallows about the flight in The Atlantic.

Hedy Lamarr - Screen Siren and Inventor

"Any girl can be glamorous. All you have to do is stand still and look stupid."
Hedy Lamarr was a glamorous Hollywood actress and the inventor of frequency hopping, the basic technique used in wireless communication. Hedy’s Folly: The Life and Breakthrough Inventions of Hedy Lamarr, the Most Beautiful Woman in the World is a new book by Richard Rhodes the Pulitzer Prize winning author of The Making of the Atomic Bomb. The new book is reviewed in Slate: The Inventor in Hollywood; in Nature: Technology: Inventing beauty.

Saturday, November 26, 2011

Allergies

There's a special section on Allergies in Nature magazine this week. That holds special interest for me personally since I'm allergy prone. I've been violently allergic to eggs since I was an infant - for example, I can't have vaccinations cultured with eggs including flu vaccines. When I was 19, before I knew that some vaccinations were cultured in eggs, I received one and then spent a week in the MIT infirmary - I needed two shots every 15 minutes for the first 36 hours just to keep me alive - ouch!
I had asthma as a child, but grew out of it. I developed an allergy to cats and many other furry animals (but not dogs) while in college - I would walk into a room with a cat and in seconds start sneezing and rubbing my eyes. But that's been much less severe since my early forties. I developed hay fever in my mid-thirties which persists but it seems to be getting somewhat less severe. I also seem to have developed allergies to kiwis and avocados, both of which I loved growing up, both of which I unknowingly ate mixed with eggs (kiwi sherbert and guacamole) during my thirties and ever since have experienced strong reactions.

Atophy: Marching with allergies in Nature is written by an individual tormented by a wide array of allergies. The author also suffered from chronic eczema, one annoyance I've been mercifully spared.


Food: Picky eaters discusses food allergies, including the possibility of creating tolerance by ingesting tiny amounts of the allergen and gradually increasing the dosage.

Wednesday, November 23, 2011

How do porcupines make love?

This riddle appears in the 1987 film Black Widow starring Debra Winger and Theresa Russell.
The two main characters are: women; formidable adversaries; and they are stronger and more clever then the men in the story. They use men to further their goals - kindly in one instance, cruelly in another - but they control their own destinies.
Any other good examples of stories - filmed or written - along those lines?




The article How do porcupines make love? from Annals of Improbable Research, reveals the punch line to the joke and then goes on to detail the actual mating behavior of these mammals - your previous ignorance of you may come to cherish.




When I was a little kid, nine or so, I had heard the f-word, realized of course, it was probably something naughty, but didn't yet know the actual definition. I finally asked another kid, who disdainfully outlined the concept. "Oh," I responded, "you mean copulation?"

Wednesday, November 16, 2011

Leonardo's Rule

Leonardo da Vinci observed that
all the branches of a tree at every stage of its height when
put together are equal in thickness to the trunk

There have been various attempts to explain that, involving the tree's vascular system for example. The preprint Leonardo's rule, self-similarity and wind-induced stresses in trees votes for wind resistance. See also Leonardo's Formula Explains Why Trees Don't Splinter at Science Now.

Monday, November 14, 2011

Ultra High Energy Cosmic Rays

Ultra High Energy Cosmic Rays hit the earth's atmosphere with energies millions of times higher than the most powerful man-made particle accelerator (the LHC). When these cosmic rays slam into the atmosphere, they create an air shower of up to billions of secondary particles which can be detected on the ground. They also generate a streak of ultraviolet light bright enough (barely) to be detected on the ground in ideal conditions. There are two amazing detector arrays: the Pierre Auger Observatory in Argentina; and the Telescope Array Project in Utah, which are currently collecting data using vast arrays of detectors. The recent preprint Ultra High Energy Cosmic Rays reviews the latest data gathered by these two observatories. One of the main unresolved questions is the source of these fantastically energetic particles - which particles are produced within our own Milky Way galaxy and which are extragalactic.

Thursday, November 10, 2011

Nonlocal Correlations without Alignment or Calibration

Nonlocal correlations are one of the spookiest things about quantum mechanics. Einstein didn't much care for quantum mechanics, he tried to show that quantum mechanics was inconsistent with his special theory of relativity with the EPR paradox. While thought provoking, the EPR paradox did not end up being viewed as a fatal flaw for quantum mechanics.
Experimental schemes for actually testing quantum nonlocality have required quite a bit of alignment and calibration of different parts of the experiment which might make a skeptic wonder if such experiments really are an ironclad test of nonlocality. The preprint Guaranteed violation of a Bell inequality without aligned reference frames or calibrated devices is a clever test of quantum nonlocality which doesn't require a lot of the alignment and calibration steps used in other approaches.

Einstein and controversy in Weimar Germany

Einstein's theory of general relativity was astonishingly controversial around 1920, even at the level of the general public. Einstein was caught up in the politics and anti-semitism rampant in Germany at the time. See the preprint Reactionaries and Einstein's Fame: "German Scientists for the Preservation of Pure Science," Relativity, and the Bad Nauheim Meeting
Cut with a kitchen knife, Dada through the last Weimar beer belly culture of Germany, 1919/1920 - Hannah Höch

Tuesday, November 08, 2011

Spacecraft Navigation by Pulsar

Currently spacecraft find their position and velocity using radio signals sent back and forth from earth-based antennas. That's quite accurate for the components of position and velocity in the direction of earth, but in other directions the accuracy is not so good. The authors of the preprint Autonomous Spacecraft Navigation Based on Pulsar Timing Information propose using an x-ray telescope onboard the spacecraft to track the signals emitted by pulsars, which rival atomic clocks in accuracy. New models of x-ray telescopes are getting small and accurate enough to find the position and velocity of a spacecraft more accurately than an earth-based system, for interplanetary missions when the spacecraft is more than 1AU from earth.

Wednesday, July 20, 2011

Puzzling Star Formation Rates in Galaxies

The rate at which stars form in Galaxies is expected to decrease with time. The spectral lines in more distant galaxies are shifted to the red end of the spectrum. The light from very distant galaxies left in the distant past, so we would expect that the star formation rate in galaxies with high redshift should increase. That does not appear to be the case: On the puzzling plateau in the specific star formation rate at z=2-7

Saturday, April 30, 2011

The Local Leo Cold Cloud

I've been fascinated with the Local Bubble, a region nearly empty of stars containing hot but low-density gas within the Milky Way near our Sun. Especially since it appears that the mysterious object Geminga, a radio-quiet x-ray plusar, might be the cause of this bubble. The preprint The Local Leo Cold Cloud and New Limits on a Local Hot Bubble describes a very cold cloud of gas within the Local Bubble - Curiouser and Curiouser.

Saturday, March 12, 2011

Balance Sheet Recession

What is a balance sheet recession and is the US in one?
Richard Koo: How the West is Repeating Japan's Mistakes.

Friday, March 11, 2011

Argon on Venus

There is Too much argon 40 on the moon (a recent blog post) and argon in the atmosphere of Venus is hard to understand as well. In both lunar rocks and the atmosphere of Venus the Argon 40/argon 36 ratio is 1:1 while in the atmosphere of Earth argon 40 is 99.6%.

See also 40Ar retention in the terrestrial planets and Geochemistry: Earth holds its breath in Nature 2007.

Thursday, March 10, 2011

Friday, March 04, 2011

Too much argon 40 on the moon

The decay of radioactive isotope potassium 40 to argon 40 is one of the main ways of finding the age of rocks: see Potassium-argon dating at Wikipedia.
But on the moon, the Apollo missions found much more argon 40 than could be explained by potassium decay. Other explanations don't look so great either, see: On the question of the 40Ar excess in lunar soils.

Globular clusters have little dark matter

Apparently globular clusters have little or no dark matter:
Evidence Against Dark Matter Halos Surrounding the Globular Clusters MGC1 and NGC 2419. This preprint also finds the motion of stars in these globular clusters is consistent with Newtonian gravity and not MOND, even though the clusters are in the low acceleration range in which MOND is supposed to make a difference. However previous see the blog post Velocities in Globular Clusters for a report that MOND does work in GCs!
Maybe globular clusters originated as the nuclear cluster of a galaxy: the preprint Nuclear Star Clusters mentions this as a possibility while discussing the star clusters at the center of galaxies.

In contrast Dwarf spheroidal galaxies are dark matter dominated.

Tuesday, March 01, 2011

The Missing Satellites Problem

The standard of model of the cosmology Lambda-CDM predicts that our Milky Way galaxy should have many more satellite galaxies than we actually see: Dwarf Galaxy Problem. It could be that some are actually missing or perhaps they are fainter than expected and hard to detect. See the preprints Notes on the Missing Satellites Problem for a review and also Too big to fail? The puzzling darkness of massive Milky Way subhalos.

Guarding the Germline

The great apes (humans, gorillas and chimps) are able to reproduce for many decades -longer than other primates. Researchers have discovered a genetic change which is active in human testis that helps guard the genome and ensure the quality of sperm. See the original report Endogenous retrovirus drives hitherto unknown proapoptotic p63 isoforms in the male germ line of humans and great apes in PNAS and Those retroviruses get everywhere at the MicrobiologyBytes blog.
It wasn't clear to me if this also occurs in Orangutans, the paper said the change occurred about 15 million years ago and the Orangutans diverged 12-16Mya Comparative and demographic analysis of orang-utan genomes. Female orangutans are fertile for 30 years, fairly similar to human females. What about the males?

Sunday, February 27, 2011

Modified Gravity works well for Gas Rich Galaxies

The motion of stars and gas in galaxies surprisingly is not so easily explained by the gravity they produce. They tend to follow flat rotation curves - after a certain distance the velocity tends to be the same whether a star is nearer or farther from the center of the galaxy. It had been expected that more distant stars and gas would be moving slower. The most popular explanation for this is dark matter , that 80% of the mass of galaxies like our Milky Way is some new unseen form that doesn't interact much, except by gravity. Another possible explanation is MOND, a theory that modifies gravity when it is very weak. A recent preprint shows that MOND works very well for gas-rich galaxies while dark matter is rather less natural and convincing: A Novel Test of the Modified Newtonian Dynamics with Gas Rich Galaxies.

Saturday, February 26, 2011

An Unusual Earlier Ice Age

There was an earlier ice age in the southern supercontinent Gondwana at the boundary between the Ordovician and Silurian periods around 445 million years ago. This ice age was unusual in that it occurred while CO2 levels were high and also coincided with a major extinction event. See The Magnitude and Duration of Late Ordovician–Early Silurian Glaciation in Science.

Thursday, February 03, 2011

The Downsizing Problem for Galaxies

It was commonly thought that galaxies form and grow larger by mergers of smaller masses. However, it has been observed that galaxies with high redshifts (which indicates that they are being observed at an early time) are on average larger than galaxies at low redshifts. This is the Downsizing Problem. The preprints Feedback in Galaxy Formation and The Many Manifestations of Downsizing: Hierarchical Galaxy Formation Models confront Observations discuss this and other problems in galaxy formation theory.

Saturday, January 29, 2011

Polar Ring Galaxies

Polar Ring Galaxies have a large ring of material perpendicular to the main galaxy. See also Polar Disk Galaxy found in Wall between Voids.
 Polar Ring  Galaxy NGC 4650A: A Disk of Red Stars Ringed By Dust, Gas, and More Stars
Source: Hubblesite.org

Another Void Model of Cosmic Acceleration

Supernovae observations published in 1998 surprisingly indicated that the expansion of the universe is accelerating - with the standard explanation being Dark Energy. A very different explanation for this acceleration is the possibility that we are near the center of a gigantic void in the distribution of galaxies. Many such Voids (smaller, but still mind-bogglingly large themselves) have been found. The preprint Reconciling the local void with the CMB elaborates on earlier proposals by relaxing the assumption that the Cosmic Microwave Background (CMB) is scale-invariant.
Here's an earlier blog post on this topic: Void Models of Cosmic Acceleration.

Friday, January 14, 2011

Ghost Imaging

Quantum effects are sometimes very strange and occasionally even useful. Ghost imaging is a particularly bizarre example. It's possible to create an image using pairs of photons. One photon is sent to the subject and the other is sent to the camera. An image of the subject is created using the photon which is received by the camera - even though that photon was never anywhere near the subject! This is possible because of the (weird) quantum nature of photons. Here's a blog post that discusses recent research in which the photon source is classical instead of quantum - supposedly you can even use sunlight. Making ghost images by getting sunlight to act quantum

Wednesday, January 12, 2011

Neandertals Cooked

Neandertals have often been characterized as highly carnivorous but now it appears that they ate a variety of plant foods and even cooked them: Microfossils in calculus demonstrate consumption of plants and cooked foods in Neanderthal diets at PNAS and here's a link to the full paper.

Tuesday, January 11, 2011

Top Quark Asymmetry

There are six quarks in the standard model of physics, the heaviest is the top quark. The Tevatron at Fermilab in Batavia, Illinois had earlier detected an unexpected asymmetry in top quark/antiquark production, but it wasn't overwhelmingly significant statistically speaking. New results in 2011 are more significant - see this preprint: Evidence for a Mass Dependent Forward-Backward Asymmetry in Top Quark Pair Production . There's a discussion at the Résonaances blog.

Monday, January 10, 2011

Motion Blinds Change Awareness

Motion Silences Awareness of Visual Change

One Way Ticket to Mars

Getting to the planet Mars isn't so difficult, as it turns out - it's coming back that's hard. Are you you willing to permanently relocate? To Boldly Go: A One-Way Human Mission to Mars discusses the possibilities.

Extinctions and Ocean Anoxia

There were a series of massive extinctions during the Cambrian period around 500 million years ago, the period when the first modern animals are found. There is new evidence that the extinctions coincided with dramatic decreases in ocean oxygen levels: Biogeochemistry: Toxic Cambrian oceans in Nature.

Hubble pictures of Hanny

Hubble Zooms in on a Space Oddity has better images of Hanny's Voorwerp.

Sunday, January 02, 2011

The Flood Myth

There's a big flood in the book of Genesis as well as other cultures: Flood myth. One hypothesis is that those stories originated from the time when the Black Sea basin was mainly dry land: Black Sea deluge theory at Wikipedia and The Search for Noah's Flood at National Geographic. Here's another possibility: Lost Civilization May Have Existed Beneath the Persian Gulf. During the last Ice Age the Persian Gulf was dry land and may have been heavily settled. Maybe the flooding there as water levels rose at the end of the Ice Age was the origin of the stories?

Saturday, January 01, 2011

Renormalization

Quantum Field Theory (QFT)is the basic framework for both particle physics and condensed matter physics. However, disturbingly, QFT calculations are plagued by unwanted infinities. All too often, when we use the theory to calculate some observable property - for example, the mass of a particle - our calculation diverges, there is no finite solution. This can't be a good thing, especially when we find in our laboratories that the mass of that particle is indeed finite. Ordinarily, this would seem like a really good reason to throw up our hands and find ourselves a better theory. But theoretical physicists are made of sterner stuff. Whenever they stumble across one of these infinities they simply use the actual observed laboratory value instead. They then proceed with their calculations until they hit another observable infinity and do it again. For certain happy theories, clever people have proved that it's only necessary to resort to the process of kludging in laboratory values a finite number of times. The theory is then said to be renormalizable and the lucky physicist who creates such a theory may well get a Nobel Prize. Steven Weinberg got his Nobel Prize after the theory of electroweak interactions which he helped create was shown to be renormalizable. In the 2009 preprint Living with Infinities Weinberg discusses the problems with infinities in QFT.

Hanny's Voorwerp

Hanny's Voorwerp is mysterious green object found by an amateur during the Galaxy Zoo project, which enlists the public to help classify galaxies over the internet.
http://antwrp.gsfc.nasa.gov/apod/ap080625.html