Various
290. Last two weeks of February on NEQNET
February (and long cold winter!) has finally come to the end, and, if by a chance, you were unable to visit us for the last two weeks, here is what the buzz was about at NEQNET:
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286. Nambu-Goldstone dark matter
This is a guest post by Yu Nakayama from the University of California, Berkeley. Dmitry.
First of all, I’d like thank Dmitry for giving me this opportunity to post a guest blog on our hottest paper about Nambu-Goldstone Dark Matter (arXiv:0902.2914). This is based on the collaboration with M. Ibe, H. Murayama, and T.T Yanagida. You know, last year Nambu got his Nobel prize for his discovery of the spontaneous breaking of the global symmetry and associated massless scalar fields (Nambu-Goldstone boson). The main idea of our paper is to use this Nambu-Goldstone boson as a candidate for dark matter, in the context of the supersymmetric extension of the standard model.
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282. Communication among communities
This is a guest blog post by Massimo Ostilli from the Center of Statistical Mechanics and Complexity (INFM, Roma). Dmitry.
In recent times, in the network science, the problem of detecting the community structure of a given network (a random graph), has attracted more attention. The general idea behind the concept of community structure comes from the observation that, in many situations, real data show an intrinsic partition of the vertices of the graph into 
groups, called communities, such that between any two communities there is a number of bonds that is relatively small if compared with the number of bonds present in each community. The partition(s) can be used to build a higher-level meta-network where the meta-nodes are now the communities (cells, proteins, groups of people, tec…) and play important roles in unveiling the functional organization inside the network. Given an hypothetical community structure, one of the most important issue is to understand whether or not the communities exchange information and to what extent, and, more in general, what are their correlations. In a recent work, we have emphasized that such a problem cannot be faced through an analysis that takes into account only the network topology (that is, the detailed description of nodes and bonds) that, by its definition, neglects any kind of correlation among the nodes. Nodes, in fact, are the sites where some physical or abstract status manifests as a result of the status of the other nodes. The most elementary example is the case in which at any node there is a dichotomy variable taking values ON and OFF. This happens – for example – in an network in which individuals, in somehow equivalent, are asked to say YES or NO to some politic proposal. The fact that the individuals know, in part, the opinion of the others, makes the answer of each individual partly conditioned by the others, especially, but not only, by those that are near (neighbors) in the social space. Physicists immediately understand that – within the equilibrium statistical mechanics – such a system can be cast by defining a suitable disordered Ising model. In this approach, the temperature 
can be seen as a parameter describing the freedom of the vertices to assume a state independently of the state of the other vertices, while the Ising couplings 
between two vertices 
and 
belonging to the 
-th and 
-th community, respectively, as a tendency of the vertices to be positively or negatively correlated, according to the amplitude and to the sign of . At least in principle, if a Gibbs-Boltzmann 
distribution with some Hamiltonian 
has been assumed, one can obtain 
from the data of the given graph by isolating the two vertices 
from all vertices of the graph other then them, and by measuring the correlation function of the obtained isolated dimer.
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281. Twitter updates for 2009-02-21
- Importance of stupidity in scientific #research: http://jcs.biologists.org/cgi/…..21/11/1771 I feel stupid all the time…
- … but writing a paper about it seems bizarre idea
- Terence Tao on Hardy uncertainty principle: http://tinyurl.com/adbzjl
Read more on 281. Twitter updates for 2009-02-21…
280. An effect – could you explain the origin?
While watching “Iron man”, I’ve got interested by the following episode: while Mr. Stark flies to Afghanistan to destroy Al Qaeda hideouts, he apparently develops supersonic speed at some point – at list, I’ve clearly heard a shock wave. At the very moment the shock wave comes, a cone of mist is developed around him.
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278. Twitter updates for 2009-02-20
- Chad Orzel on #gravity probe B: http://tinyurl.com/b6cazj
- Ballistic acceleration of supercurrent in #superconductor: http://link.aps.org/doi/10.110…..102.077001
- Kinks in electronic specific heat: http://link.aps.org/doi/10.110…..102.076402
- #Gauge coupling unification in F-theory #GUTs: http://link.aps.org/doi/10.110…..102.071601
- http://tinyurl.com/df9a9k – how applied #science will look like in 2020.
Read more on 278. Twitter updates for 2009-02-20…
277. Video of the day: In search of giants
A nice video about history of particle physics (featuring Brian Cox).
275. Twitter updates for 2009-02-19
- UFO? http://tinyurl.com/dfa4ld
- Helping underprepared students in introductory physics: http://jijr.com/ypb
- Sean Carroll discusses search for #Higgs boson: http://tinyurl.com/b6oqre
- So, it is practically certain that #Higgs with mass around 165 GeV will be found at Fermilab before 2011
Read more on 275. Twitter updates for 2009-02-19…
274. Video of the day: Quark-gluon plasma at RHIC
Beautiful promo video of RHIC. Not sure what she means by “they expected to find a gas…”
272. Twitter updates for 2009-02-18
- Lubos Motl on Ernst Mach: http://tinyurl.com/b2gx96
- Stanleyfest at #KITP: http://online.kitp.ucsb.edu/online/stanleyfest/ . Fascinating, Joe Polchinski’s talk is definitely worth watching.
- http://arxivblog.com/?p=1220 – the CORONA coronograph proved to be unable to function in Antarctica and was sent back to France.
Read more on 272. Twitter updates for 2009-02-18…
268. Video of the day: Sean Carroll at Google
is talking about dark energy and dark matter:
Wow, not bad, I am glad to see that Googlers get more interest in science (so that the way PageRank treats science papers will be finally improved to the point where googling a research paper becomes useful )
Read more on 268. Video of the day: Sean Carroll at Google…
267. Twitter updates for 2009-02-17
- Jester on CDF multi-muon anomaly: http://short.to/109b
- Black hole hair removal: http://arxiv.org/abs/0901.0359
- Deformed general relativity and torsion: http://arxiv.org/abs/0902.2001
- Quantum data buffering scale: http://www.physorg.com/news153681740.html
- First draft of Neanderthal genome was unveiled: http://jijr.com/oyo
- Artificial arm listens to brain: New York Times http://snipr.com/bxs2b
Read more on 267. Twitter updates for 2009-02-17…
266. First two weeks of February on NEQNET
It seems that I did not do summary of activities on NEQNET for quite a bit Let me first quickly go through some relevant and irrelevant statistics.
First of all, the number of subscribers to NEQNET has finally crossed the magic number of 200 (two-three days ago). Thank you so much, all of you, who decided to subsribe – you made me extremely happy, made my day! On the other hand – the number of daily visitors is currently more than 1000 and, as I see, at least half of them are not newcomers. If, by a chance, you are reading NEQNET on a constant basis but are not yet subscribed – could I ask you to become a subscriber? It is possible to either subscribe to NEQNET RSS feed or get sent new posts directly to your Inbox.
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265. Video of the day: CMS assembly animation
An old video (2003) by CERN explaining how CMS detector was assembled.
Update: If you want some relatively fresh info on CMS status, listen for Giovanni Franzoni’s talk at PI.
264. Twitter updates for 2009-02-15
- Evolution: unnatural selection http://dx.doi.org/10.1038/457803a
- Tunable delay in EPR entanglement: http://dx.doi.org/10.1038/nature07751
- Density of states and critical behavior of Coulomb gas: http://link.aps.org/doi/10.110…..102.067205
- How to measure a spinon Fermi surface: http://link.aps.org/doi/10.110…..102.067204
- Topological transition in a non-hermitean quantum walk: http://short.to/ysa
Read more on 264. Twitter updates for 2009-02-15…
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