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Category Archives: science

Ice and "complex organic materials" on Mercury’s poles

This is one of those perplexing astronomical news that make history and I can’t but mention. US scientists have found, with the help of scout satellite MESSENGER,  that not just suspected Mercury’s polar water ice (in shadowed craters) is indeed that but also that confusing dark regions around it are complex organic materials, possibly darkened by the intense solar radiation that bathes the small inner planet. 

The team found that the probe’s reflectance measurements, taken via laser altimetry, matched up well with previously mapped radar-bright regions in Mercury’s high northern latitudes. Two craters in particular were bright, both in radar and at laser wavelengths, indicating the possible presence of reflective ice. However, just south of these craters, others appeared dark with laser altimetry, but bright in radar.

This confused scientists for a while but eventually they realized that the puzzling regions actually hold water ice at a meter’s depth into the soil, where the heat of the sun can’t reach so easily. 
Radar-reflectant regions (ice) show in yellow
The most interesting part however is that the astronomers are almost certain now that the dark material must be complex organic matter, darkened by the extreme solar radiation.
Is there life in Mercury? 
Source: Science Daily.
Ref studies: 
  1. David A. Paige, Matthew A. Siegler, John K. Harmon, Gregory A. Neumann, Erwan M. Mazarico, David E. Smith, Maria T. Zuber, Ellen Harju, Mona L. Delitsky, and Sean C. Solomon. Thermal Stability of Volatiles in the North Polar Region of Mercury. Science, 29 November 2012 DOI: 10.1126/science.1231106
  2. Gregory A. Neumann, John F. Cavanaugh, Xiaoli Sun, Erwan M. Mazarico, David E. Smith, Maria T. Zuber, Dandan Mao, David A. Paige, Sean C. Solomon, Carolyn M. Ernst, and Olivier S. Barnouin. Bright and Dark Polar Deposits on Mercury: Evidence for Surface Volatiles. Science, 29 November 2012 DOI: 10.1126/science.1229764
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Posted by on November 30, 2012 in astronomy, biology, chemistry, science, Solar System

 

Quantum uncertainty goes uncertain

Heisenberg’s uncertainty principle is the stuff out of which some of the best modern legends are made, such as the ill-fated Schrödinger’s cat, which is neither dead nor alive but exactly the opposite, or the fantastic stories about quantum improbability drives, which made the infinite monkey theorem to be real for a fraction of eternity only to vanish again (among many other infinitely improbable effects).
However everything has an end and that seems to be the case with the uncertainty principle as well. Canadian researchers have managed to prove it false in some circumstances, circumstances theorized already in 2003 by Masanao Ozawa but not experimentally confirmed until now.

Lee A. Rozema et al., Violation of Heisenberg’s Measurement-Disturbance Relationship by Weak Measurements. Physical Review Letter, 2012. Pay per view ··> LINK [doi:10.1103/PhysRevLett.109.100404]

Abstract

While there is a rigorously proven relationship about uncertainties intrinsic to any quantum system, often referred to as “Heisenberg’s uncertainty principle,” Heisenberg originally formulated his ideas in terms of a relationship between the precision of a measurement and the disturbance it must create. Although this latter relationship is not rigorously proven, it is commonly believed (and taught) as an aspect of the broader uncertainty principle. Here, we experimentally observe a violation of Heisenberg’s “measurement-disturbance relationship”, using weak measurements to characterize a quantum system before and after it interacts with a measurement apparatus. Our experiment implements a 2010 proposal of Lund and Wiseman to confirm a revised measurement-disturbance relationship derived by Ozawa in 2003. Its results have broad implications for the foundations of quantum mechanics and for practical issues in quantum measurement.

In other words, the researchers managed to measure a photon with a very weak interaction first and then measure the photon regularly again, producing the same result. This means that the photon was not altered by the first measure, what surely opens many possibilities for both theoretical and applied physics. 
Source: Science Daily.
 
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Posted by on September 8, 2012 in physics, science

 

Higgs boson discovered?

The elusive subatomic particle, dubbed “the God particle”, or at least something that looks a lot like it, has been finally found, according to an announcement by the European Organization for Nuclear Research (CERN), whose particle accelerator, the Large Hadron Collider (LHC), spans many kilometers underground the French-Swiss border near Geneva.
“We observe in our data clear signs of a new particle, at the level of 5 sigma, in the mass region around 126 GeV. The outstanding performance of the LHC and ATLAS and the huge efforts of many people have brought us to this exciting stage”, said ATLAS experiment spokesperson Fabiola Gianotti, “but a little more time is needed to prepare these results for publication”.
“The results are preliminary but the 5 sigma signal at around 125 GeV we’re seeing is dramatic. This is indeed a new particle. We know it must be a boson and it’s the heaviest boson ever found”, said CMS experiment spokesperson Joe Incandela. “The implications are very significant and it is precisely for this reason that we must be extremely diligent in all of our studies and cross-checks”.
While the implications of this discovery are yet to be refined there is almost no doubt that it will strongly affect our understanding of nature confirming the theoretical set of the so-called Standard Model of particle physics.
The unification theory or Theory of Everything (ToE), which would fuse particle physics and space-time (and gravity) physics described in Einstein’s General Relativity is still out of our immediate reach, however consolidating the Standard Model should provide more solid basis for such efforts.
The Higgs Boson is involved in the Higgs mechanism: the why behind particle mass.

 
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Posted by on July 5, 2012 in Europe, physics, science

 

Problems demonstrating positive selection

This is a very interesting paper not because it offers any new striking discovery but because it brings to doubt previous ones and highlights the difficulties in demonstrating beyond reasonable doubt the functional selection in genes allegedly involved in pigmentation, which is one of the most clear differential adaptions among humans.
Importantly most of the discoveries challenged were made by the same team, what is a outstanding example of scientific commitment and self-criticism. Casting doubts and reducing certainty may not be what makes a Nobel Prize but it is how Science advances in fact.

Abstract (provisional)

Background

Numerous genome-wide scans conducted by genotyping previously-ascertained single nucleotide polymorphisms (SNPs) have provided candidate signatures of positive selection in various regions of the human genome, including in genes involved in pigmentation traits. However, it is unclear how well the signatures discovered by such haplotype-based test statistics can be reproduced in tests based on full resequence data. Four genes, OCA2, TYRP1, DCT and KITLG, implicated in human skin color variation, have shown evidence for positive selection in Europeans and East Asians in previous SNP-scan data. In the current study, we resequenced 4.7-6.7 kb of DNA from each of these genes in Africans, Europeans, East Asians and South Asians.

Results

Applying all commonly-used allele frequency distribution neutrality test statistics to the newly generated sequence data provided conflicting results in respect of evidence for positive selection. Previous haplotype-based findings could not be clearly confirmed. The application of Markov Chain Monte Carlo Approximate Bayesian Computation to these sequence data using a simple forward simulator revealed broad posterior distributions of the selective parameters for all four genes providing no support for positive selection. However, when we applied this approach to published sequence data on SLC45A2, another human pigmentation candidate gene, we could readily confirm evidence for positive selection as previously detected with sequence-based and some haplotype-based tests.

Conclusions

Overall, our data indicate that even genes that are strong biological candidates for positive selection and show reproducible signatures of positive selection in SNP scans do not always show the same replicability of selection signals in other tests, which should be considered in future studies on detecting positive selection in genetic data. 

 

Echoes from the Past (Nov 1)

Happy calaca day to all Mexicans. I have a bunch of interesting news items stored in the “to do” folder and it’s time to release them in bulk and, in a sense, get rid of them that way. Hope you find them interesting.
Prehistory and proto-history:

Abalone ochre container from Blombos
I already commented in the previous ‘Echoes’ edition but the 100,000 years-old paint containers made-out-of-shells found in Blombos (South Africa) have been echoing through various media, each with a  slightly different twist ··> The Heritage Journal, MSNBC, SD.
Nail in the coffin for ‘Clovis first’ theory: mammoth bone spear point in mammoth leg bone dated precisely to pre-Clovis times: 13,800 years ago (there are older dates out there anyhow) ··> BBC.
Jaw bone found near Kennewick Man’s site (and controversy on native insistence on reburial) ··> KPLU.

Cishan-Peligang pottery
Chinese Neolithic may be almost as old as West Asian one. Evidence of millet cultivation in Hebei (North China) dates to c. 10,000-8,700 years ago, within the Cishan culture (notice that Pengtoushan culture in South China overlaps with these dates and could be even quite older) ··> Xinhua
Bronze Age take-out windows found in Iran (Godin Tepe) ··> Unreported Heritage News, Live Science.
A new report on Iruña-Veleia Roman era graffiti supports their authenticity ··> Ostraka euskalduna[eu], where you can download the PDF in Spanish language by M. Thomson.
Also mentioned recently but still hitting the news, controversy on the reopening of Altamira cave, dubbed the Magdalenian Sistine Chapel, to the public ··> SD.

Replica of the Altamira ceiling (fragment)

Genetics:
Sardinian genetics point to pre-Neolithic origins according to new research (this I want to discuss in some greater detail but I’m sadly leaving for tomorrow again) ··> Daniela Contu et al. at PLoS ONE (open access). 
Researchers claim that mtDNA age estimates support pre-Neolithic dates for major East Asian population expansion ··> Hong-Xiang Zheng et al. at PLoS ONE (open access).
Fractal analysis of the human genome. You would think that putting together the words fractal and human genetics would appeal to my interest a lot. I must be getting old because it only does somewhat. A reason may be that while the methodology is intriguing and innovative no particular conclusion is proposed ··> Pedro A. Moreno et al. at BMC Genomics (open access).
Extra copies of SRGAP2 gene may be one reason behind human unique intelligence ··> Science News.
Human brains designed by the same fixated genes, regardless of race or individual differences. This is one of a list of novel findings on how the genome expresses in the brain along human life ··> SD.
Epigenetically modified nucleotide (“sixth letter” 5-hydroxymethylcytosine) in neuronal genomes is key to their behavior as such ··> SD.
Propensity for longer life inherited epi-genetically through generations. This so much coveted trait is inherited by lab roundworms even if the initial epigenetic modification has vanished ··> SD.
Other anthropology news:
Human children, but not chimpanzees, prefer to collaborate in order to solve tasks ··> Science Daily.
IQ is not totally fixed by genetics and can indeed change, specially in adolescence ··> BBC.
Other science news:
Comet storm detected in nearby stellar system (may increase chances of life by feeding planets like ours with water) ··> SD.
Nature laws may vary across the universe. At least electromagnetic constants seem to behave that way ··> PhysOrg.
Highly efficient (10x) hydrolysis catalyst found, helping to pave the way for easier production of hydrogen for fuel instead of dirty oil ··> SD.
Global warming is for real (in case you still had any doubt) ··> SD.

 

The Chaos paradigm

A must watch: a high quality BBC documentary on the great paradigm shift that happened through the second half of the 20th century from the Newtonian paradigm of a clockwork universe, not to Relativity or Quantum Uncertainty, but straight into Chaos.

It lasts exactly 1 hour.
Found at In Defense of Marxism, which has an article on it, with a few punctual criticisms and some of its politico-economical implications.
I understand that the film has an spiritual (emotional) and intellectual value and is worth watching even for those in the know, so to say, of Chaos science. Because it is not so easy to comprehend this new unavoidable paradigm and the film certainly aids to that in many ways. Understanding Chaos may be even more important than understanding Relativity, because Einstein’s theory only applies to some aspects of reality, while Chaos applies to everything.
It is this overwhelming influence of Chaos mathematics and physics what makes this understanding so crucial, whichever one’s field or fields of interest: it applies to evolution and human prehistory surely and it also is in the economy, in social organization and even in the intimacy of our souls (psyche).
Self organization, feedback, fractality (the part and the whole are usually similar), unpredictability of even very simple systems, orders as forms of chaos and not anymore its opponents and critically the real option for a small incident to precipitate a major reaction if the conditions are adequate albeit unpredictably so (the butterfly effect).
We have no choice but to embrace Chaos if we are to do something in it.
 
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Posted by on May 20, 2011 in Chaos, science

 

A one-dimensional universe at the Big Bang?

This is so weird and intriguing that I can’t but make a quick comment on it. Two US scientists, Jonas Mureika and Dejan Stojovic, are proposing a radical rethink of what we understand as the basic physics of our universe: they suggest that, at the Big Bang, the Universe had only one dimension (like a line), acquiring then two dimensions (plane) and then three (space), and probably soon a fourth (if not already). 
This radical rethink seems to have been pushed by the advances (and lack of them) in the fields of Physics and Astrophysics in the last decades, when questions have been piling up and convincing answers have been lacking instead. 
These problems include the fundamental incompatibility between gravito-centric General Relativity and particle-centric Quantum Mechanics, the mystery of the Universe’s accelerating expansion (which seems to demand extra dimensions) and serious issues with the elusive (and maybe non-existent) Higg’s Boson. 
By reflecting this new proposal I do not mean to adhere to it but I do like the principle they begin from: maybe something fundamental is wrong in the way we think Physics, so exploring radically new venues may be the way out of an otherwise unsolvable problem. 
They are thinking out of the box and that is something I really like and that often brings real solutions in all fields. 
The new theory has been published in the Physical Review Letter (pay per view) and is also discussed in its essentials at Science Daily.
 
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Posted by on April 21, 2011 in astronomy, physics, science