Variational approach to gravitational theories with two independent connections

A new variational approach for general relativity and modified theories of gravity is presented. In addition to the metric tensor, two independent affine connections enter the action as dynamical variables. In the matter action the dependence upon one of the connections is left completely unspecified. When the variation is applied to the Einstein-Hilbert action the Einstein field equations are recovered. However when applied to $f(R)$ and Scalar-Tensor theories, it yields gravitational field equations which differ from their equivalents obtained with a metric or Palatini variation and reduce to the former ones only when no connections appear in the matter action.Comment: 11 pages, no figure

Towards a Formal Verification Methodology for Collective Robotic Systems

We introduce a UML-based notation for graphically modeling systems’ security aspects in a simple and intuitive way and a model-driven process that transforms graphical specifications of access control policies in XACML. These XACML policies are then translated in FACPL, a policy language with a formal semantics, and the resulting policies are evaluated by means of a Java-based software tool

Metabolic and functional consequences of cytosolic 5′-nucleotidase-IA overexpression in neonatal rat cardiomyocytes

Adenosine exerts a spectrum of energy-preserving actions on the heart negative chronotropic effects. The pathways leading to adenosine formation have remained controversial. In particular, although cytosolic 5′-nucleotidases can catalyze adenosine formation in cardiomyocytes, their contribution to the actions of adenosine has not been documented previously. We recently cloned two closely related AMP-preferring cytosolic 5′-nucleotidases (cN-IA and -IB); the A form predominates in the heart. In this study, we overexpressed pigeon cN-IA in neonatal rat cardiomyocytes using an adenovirus. cN-IA overexpression increased adenosine formation and release into the medium caused by simulated hypoxia and by isoproterenol in the absence and presence of inhibitors of adenosine metabolism. Adenosine release was not affected by an ecto-5′-nucleotidase inhibitor, α,β-methylene-ADP, but was affected by a nucleoside transporter, dipyridamole. The positive chronotropic effect of isoproterenol (130 ±3 vs. 100 ±4 beats/min) was inhibited (107 ±3 vs. 94 ±3 beats/min) in cells overexpressing cN-IA, and this was reversed by the addition of the adenosine receptor antagonist 8-(p-sulfophenyl)theophilline (120 ± 3 vs. 90 ± 4 beats/min). Our results demonstrate that overexpressed cN-IA can be sufficiently active in cardiomyocytes to generate physiologically effective concentrations of adenosine at its receptors.Fil: Sala-Newby, Graciela B.. University of Bristol; Reino UnidoFil: Freeman, Nicola V. E.. University of Bristol; Reino UnidoFil: Curto, Maria de Los Angeles. University of Bristol; Reino Unido. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Newby, Andrew C.. University of Bristol; Reino Unid

Entropic uncertainty relations for electromagnetic beams

The symplectic tomograms of 2D Hermite--Gauss beams are found and expressed in terms of the Hermite polynomials squared. It is shown that measurements of optical-field intensities may be used to determine the tomograms of electromagnetic-radiation modes. Furthermore, entropic uncertainty relations associated with these tomograms are found and applied to establish the compatibility conditions of the the field profile properties with Hermite--Gauss beam description. Numerical evaluations for some Hermite--Gauss modes illustrating the corresponding entropic uncertainty relations are finally given.Comment: Invited talk at the XV Central European Workshop on Quantum Optics (Belgrade, Serbia, 30 May -- 3 June 2008), to appear in Physica Scripta

Crisi e rimobilitazione: gli italiani, la politica, i partiti nelle indagini campionarie del CISE (2011-2012)

Nella primavera 2012, pochi mesi dopo l\u2019insediamento del governo Monti, i partiti italiani toccavano il punto pi\uf9 basso della loro presa sull\u2019opinione pubblica italiana: altissime percentuali di astenuti e indecisi, con un elettorato demotivato da un\u2019offerta politica ancora incerta (anche a causa della difficile convivenza con un governo tecnico) e quindi incapace di strategie innovative. Tuttavia, \ue8 forse vero che la politica ha orrore del vuoto: l\u2019imminenza delle elezioni amministrative (del maggio 2012) e soprattutto l\u2019ingresso nell\u2019ultimo anno prima delle elezioni politiche segnano una ripresa dell\u2019iniziativa politica, sia da parte dei partiti esistenti che da parte di nuovi attori politici. Il primo a muoversi \ue8 il Movimento 5 Stelle, con un\u2019aggressiva strategia per le elezioni amministrative, in cui registrer\ue0 un grande successo. Ma in secondo luogo \ue8 il centrosinistra a gettarsi in una impegnativa e rischiosa strategia politica basata sulle primarie, che otterr\ue0 tuttavia il grande risultato di una significativa rimobilitazione del proprio elettorato. Tutte queste tendenze sono state puntualmente registrate dalla serie di indagini demoscopiche Osservatorio Politico CISE, condotte ogni sei mesi a partire dalla primavera 2011. I risultati di queste indagini, gi\ue0 pubblicati sul sito web Cise nel corso del 2012, sono raccolti oggi in questo secondo Dossier CISE. Una riflessione sul clima di opinione pubblica che conduce alle elezioni politiche del 2013, che vuole fornire dati utili per interpretare le ultime fasi della campagna elettorale e per inquadrare l\u2019ormai imminente risultato delle elezioni

In vitro selection of resistance in Streptococcus pneumoniae at in vivo fluoroquinolone concentrations

Methods: Twenty strains of S. pneumoniae susceptible to fluoroquinolones were used. The frequencies of spontaneous single-step mutations at plasma and epithelial lining fluid (ELF) peak and trough antibiotic concentrations were calculated. Multi-step selection of resistance was evaluated by performing 10 serial subcultures on agar plates containing a linear gradient from peak to trough antimicrobial concentrations, followed by 10 subcultures on antibiotic-free agar. Resistant strains selected after multi-step selection were characterized for DNA mutations by sequencing gyrA, gyrB, parC and parE genes. Results: Levofloxacin and moxifloxacin showed the lowest frequencies of mutations (median <10 211 ) at plasma peak and at ELF concentrations, while medians ranging from 10 28 to 10 26 were observed for ciprofloxacin and prulifloxacin. In a multi-step selection assay, ciprofloxacin and prulifloxacin selected for the highest number of resistant strains (19 and 31, respectively). No selection of resistance was observed for levofloxacin at ELF concentrations and for moxifloxacin at plasma and ELF concentrations. Mutations in parC, parE and gyrA genes were found in ciprofloxacin- and prulifloxacinresistant strains, while only parC mutations were found for levofloxacin. Conclusions: Levofloxacin and moxifloxacin are characterized by a lower propensity to select in vitro for resistance in S. pneumoniae than ciprofloxacin and prulifloxacin, when tested at plasma and lung concentrations