Spontaneous breaking of translational invariance in non-commutative lambda phi^4 theory in two dimensions

The spontaneous breaking of of translational invariance in non-commutative self-interacting scalar field theory in two dimensions is investigated by effective action techniques. The analysis confirms the existence of the stripe phase, already observed in lattice simulations, due to the non-local nature of the non-commutative dynamics.Comment: 7 pages, 2 figure

Comment on "Feynman Effective Classical Potential in the Schrodinger Formulation"

We comment on the paper "Feynman Effective Classical Potential in the Schrodinger Formulation"[Phys. Rev. Lett. 81, 3303 (1998)]. We show that the results in this paper about the time evolution of a wave packet in a double well potential can be properly explained by resorting to a variational principle for the effective action. A way to improve on these results is also discussed.Comment: 1 page, 2eps figures, Revte

Astrophysical constraints on the confining models : the Field Correlator Method

We explore the relevance of confinement in quark matter models for the possible quark core of neutron stars. For the quark phase, we adopt the equation of state (EoS) derived with the Field Correlator Method, extended to the zero temperature limit. For the hadronic phase, we use the microscopic Brueckner-Hartree-Fock many-body theory. We find that the currently adopted value of the gluon condensate $G_2 \simeq 0.006-0.007 \rm {GeV^4}$, which gives a critical temperature $T_c \simeq 170 \rm MeV$, produces maximum masses which are only marginally consistent with the observational limit, while larger masses are possible if the gluon condensate is increased.Comment: 7 pages, 5 figure

The puzzle of the synthesis of the rare nuclide 138La

The calculations of the p-process in the O/Ne layers of Type II supernovae are quite successful in reproducung the solar system content of p-nuclides. They predict, however, a significant underproduction of the rare odd-odd nuclide 138La. A model for the explosion of a 25 Mo star with solar metallicity is used to suggest that electron neutrino captures on 138Ba may well be its most efficient production mechanism. The responsibility of an inadequate prediction of the 138La and 139La photodisintegration rates in the too low production of 138La is also examined quantitatively. A detailed discussion of the theoretical uncertainties in these rates suggest that the required rate changes are probably too high to be fully plausible. Their measurement would be most welcome. They would help disentangling the relative contributions of thermonuclear and neutrino processes to the 138La production.Comment: 4 pages to be published by A&A Letter

Synthesis of 5-substituted 7,9-dihydro-8H-[1,3]dioxolo[4,5-h][2,3]benzodiazepin-8-ones as anticonvulsant agents

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Inhomogeneities on the surface of 21 Lutetia, the asteroid target of the Rosetta mission

CONTEXT: In July 2010 the ESA spacecraft Rosetta will fly-by the main belt asteroid 21 Lutetia. Several observations of this asteroid have been so far performed, but its surface composition and nature are still a matter of debate. For long time Lutetia was supposed to have a metallic nature due to its high IRAS albedo. Later on it has been suggested to have a surface composition similar to primitive carbonaceous chondrite meteorites, while further observations proposed a possible genetic link with more evolved enstatite chondrite meteorites. AIMS: In order to give an important contribution in solving the conundrum of the nature of Lutetia, in November 2008 we performed visible spectroscopic observations of this asteroid at the Telescopio Nazionale Galileo (TNG, La Palma, Spain). METHODS: Thirteen visible spectra have been acquired at different rotational phases. RESULTS: We confirm the presence of a narrow spectral feature at about 0.47-0.48 micron already found by Lazzarin et al. (2009) on the spectra of Lutetia. We also find a spectral feature at about 0.6 micron, detected by Lazzarin et al. (2004) on one of their Lutetia's spectra. More importantly, our spectra exhibit different spectral slopes between 0.6 and 0.75 micron and, in particular, we found that up to 20% of the Lutetia surface could have flatter spectra. CONCLUSIONS: We detected a variation of the spectral slopes at different rotational phases that could be interpreted as possibly due to differences in the chemical/mineralogical composition, as well as to inhomogeneities of the structure of the Lutetia's surface (e.g., the presence of craters or albedo spots) in the southern hemisphere.Comment: 3 pages, 2 figures. Accepted for publication in Astronomy and Astrophysics. Updated on 25 March 2010

L’emorroidectomia secondo Milligan-Morgan e la mucoprolassectomia con stapler. Valutazione clinica comparativa dei risultati

The aim of this retrospective study was to assess the results of treatment for hemorrhoids by Milligan-Morgan hemorrhoidectomy and by stapled mucoprolapsectomy in terms of operative time, postoperative pain, lenght of hospital stay, incidence of early and late complications, time to return to work and to normal social activities and patient satisfaction. Between January 2002 and December 2003, a total of 65 patients with hemorrhoids (35 men and 30 women with a mean age of 46.9 years) underwent surgical treatment: 41 patients underwent conventional hemorrhoidectomy and 24 patients stapled mucoprolapsectomy. All patients were contacted by phone or were reviewed in the outpatient clinic with a mean follow-up of 2 months (range 8-31). The Authors emphasize that it is difficult to make an objective comparison between hemorrhoidectomy and stapled mucoprolapsectomy because the two procedures are completely different in terms of rationale and technique; however, stapled circumferential mucosectomy in their experience causes less postoperative pain and bleeding and can be considered a valid therapeutic option for third- and fourth-degree disease

Noncommutative electrodynamics and ultra high energy gamma rays

Plane waves in noncommutative classical electrodynamics (NCED) have a peculiar dispersion relation. We investigate the kinematical conditions on this deformed "mass shell" which come from ultra high energy gamma rays and discuss noncommutative dynamical effects on the gamma absorption by the infrared background and on the intrinsic spectrum. Finally we note that in NCED there is a strong correlation between the modified dispersion relation and the presence of dynamical effects in electromagnetic phenomena such as in the case of the synchrotron radiation. From this point of view, the limits on the typical energy scale of the violation of Lorentz invariance obtained by deformed dispersion relations and by assuming undeformed dynamical effects should be taken with some caution.Comment: Latex file, 7 pages, to be published in Europhysics Letter

Breakdown mechanisms in electrostatic deflector

The Electrostatic Beam Deflectors for the K800 Superconducting Cyclotron are the most critical elements of the beam extraction system. It has been carried out an accurate investigation from the microscopic point of view, leading to a better comprehension of the complex phenomena taking part in the breakdown process. The environmental conditions are high electric field (up to 130 kV/cm), high magnetic field (up to 5 T) in addition with high energy (70 MeV/u) and high power ion beam. It has been found that all the materials constituent the electrostatic deflector, and not only the electrodes, give an important contribute to the mechanism of breakdown that occurs in two main ways: insulator metalization and enhanced electrodes electron emission. These two effects are involved in a positive feedback process which amplifies the effects leading to a fast breakdown. These phenomena are here shown and some possible solutions are at the moment under test using several bulk (Mo, Ti, Cu) and coating materials (TiN, Diamond Like Carbon)