The network of scientific journals

At the beginning of 2012, Science published a briefly paper about the coercitive action of the editors in most of the scientific journals in world:
We find that coercion is uncomfortably common and appears to be practiced opportunistically(1)
One of the most coercitive practice is to say to the authors to cite in their paper more source from the journal where the work is submitted (the practice of coercive self-citation is common in the business disciplines, for example). Now a new research try to describe the interaction between scientific journals with a really particular network:
In the network, an arrow from journal A to journal B represents a “resubmission link,” that is, an article that was submitted to and published by journal B after submission to journal A. This network can be used to learn more about publication strategies and perceived journal importance than is available in citation networks alone(2)
The idea is: you submit to a journal with an high impact factor, your paper was rejected for example because is too specialistic, and you resubmit to another journal, and in this case your paper is accepted. And, incredible:
Resubmissions were significantly more cited than first-intents published the same year in the same journal(2)
Keith Bowers, commenting the results of the paper, write on the same issue of Science:
Journal editors could increase the quality of papers published in their own journals by exacting more rigorous standards for revision without rejecting them. Providing authors more opportunities to revise and resubmit manuscripts following peer review, while being clear to authors that substantial improvement must be made before a final decision is reached, would increase the citation impact of an editor's own journal.(3)
As is he right?
(1) Wilhite A.W. & Fong E.A. (2012). Coercive Citation in Academic Publishing, Science, 335 (6068) 542-543. DOI:
(2) Calcagno V., Demoinet E., Gollner K., Guidi L., Ruths D. & de Mazancourt C. (2012). Flows of Research Manuscripts Among Scientific Journals Reveal Hidden Submission Patterns, Science, 338 (6110) 1065-1069. DOI:
(3) Bowers E.K. (2012). Journals: Increase Revisions, Not Rejections, Science, 338 (6110) 1029-1029. DOI:

Proofs without words: Ptolemy's theorem and cosine's law

Derrick W. & Hirstein J. (2012). Proof Without Words: Ptolemy’s Theorem, The College Mathematics Journal, 43 (5) 386-386. DOI: (via Cut the Knot)
Kung S.H. (1990). Proof without Words: The Law of Cosines, Mathematics Magazine, 63 (5) 342. DOI: (pdf)
Law of cosines via Ptolemy's theorem
Kung S.H. (1992). Proof without Words: The Law of Cosines via Ptolemy's Theorem, Mathematics Magazine, 65 (2) 103. DOI: (pdf)

A is for atom

#video posted by @ulaulaman about #nuclearenergy

via boingboing

Looking through an opaque material

posted by @ulaulaman about #JacopoBertolotti #physics #optics #opaque #matter
I am proud to publish a feature article about the research word of a Wikipedia's friend like Jacopo Bertolotti. The work was finally published on "Nature", that decided also to honor the paper with the cover.
I admit to have received the paper a couple of weeks ago, so I hope to have made ​​a good service to Jacopo and all of his colleagues.

Recently one of my students asked me why glass is transparent while other materials are not. Its transparency is substantially due to the interaction between the electrons of the glass and the incident light, and so from the interaction between the photons (or electromagnetic radiation) and matter. A photon, when it interacts with matter, can be absorbed, reflected or continue on its way without change. These different behaviors are due to the energy levels occupied by the electrons of the atoms that constitute matter, in particular by the energy difference between these levels. We know, thanks to the photoelectric effect and the explanation given to it by Einstein, that the electrons are excited by the incident photons only if the energy of these photons is equal to (or greater than) the energy required to jump to another level. This means that if the light does not excite the electrons of the material, this is transparent to its passage, just as occurs in the glass: the visible light, in fact, has not enough energy to excite the electrons of the glass, which is therefore transparent to its passage, despite the rays of light are reflected.
Now, if we take a sheet of glass and do hit by light from one of its ends, a part of the rays will be reflected and then detected by a device (such as our eyes) placed for example at the opposite end. Not all reflected rays, however, follow an equal path and therefore not all the rays reach the eyes at the same time.
Something similar also occurs when light passes through the glass of our windows: the light rays don't travel all at the same speed.
In order to enable to all the rays of light to reach the detection point at the same time one can construct a structure which gradually tapering as it approaches the ends, i.e. it builds a lens.
One of the ways to use a lens is for example for the magnification of objects, but not all magnifications can be made using the lenses that take advantage of the visible light. If, for example, we have some objects that are at a scale of less than 200 nm, the usual optical lenses are not able to resolve their details. Unless you build a HIRES(1) (High Resolution Enhancement by Scattering Index) lens.
This lens, developed by the group of van Putten and Bertolotti (our Jacopo!) consists of:
(...) of a homogeneous slab of high-index material on top of a strongly disordered scattering layer. The disordered layer breaks the translational invariance of the interface, which enables incident light to be coupled to all propagating angles inside the highrefractive-index material as shown in figure.
Yet multiple scattering also scrambles the wavefront creating a speckle-like pattern on the object plane that itself cannot be used for imaging. Therefore we manipulate the incident wavefront in order to force constructive interference of the scattered light at a position in the object plane of our HIRES-lens.(1)