156 research outputs found

    The Mandelstam--Leibbrandt Prescription and the Discretized Light Front Quantization

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    It is shown that the quantization of the unphysical degrees of freedom, which leads to the Mandelstam--Leibbrandt prescription for the infrared spurious singularities in the continuum light cone gauge, does indeed suggest some quite natural recipe to treat the zero modes in the Discretized Light Front Quantization of gauge theories.Comment: 5 pages, LaTeX, Talk given at the Fourth International Workshop on Light Cone Quantization and Non--Perturbative Dynamics, Polana Zgorzelisk

    The Unruh effect revisited

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    A new and exact derivation of the Bogoliubov coefficients is obtained for the simplest case of a spinless, neutral, massive field in a uniformly accelerated frame with a constant acceleration. The method can be suitably generalized in a straightforward manner to any field with spin and charges.Comment: 5 page

    Neutral Massive Spin 1/2 Particles Emission in a Rindler Spacetime

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    The Unruh effect for the rate of emission and absorption of neutral massive Majorana spinor particles -- the most plausible consituents of Dark Matter -- in a Rindler spacetime is thoroughly investigated. The corresponding Bogolyubov coefficients are explicitly calculated and the consistency with Fermi-Dirac statistics and the Pauli principle is actually verified.Comment: v2: clarifications added to Introduction and Conclusions, added appendices; v3 removed review part, published versio

    teoria dei campi 1.

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    teoria dei campi 2.

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    On the mystery of the missing pie in graphene

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    We investigate in some detail the structure of the electromagnetic current density for the pseudo-relativistic massless spinor effective model for graphene. It is shown that the pseudo-relativistic massless Dirac field theory in {\em 2+1} space-time dimensions and in the presence of a constant homogeneous electric field actually leads to the measured current density and to the minimum quantum conductivity.Comment: 10 pages, no figures, substantial changes and added reference

    Synthesis of new bioactive ╬▓-lactam compounds

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    New biologically active ╬▓-lactams were designed and synthesized, developing novel antibiotics and enzymatic inhibitors directed toward specific targets. Within a work directed to the synthesis of mimetics for RGD (Arg-Gly-Asp) sequence able to interact with ╬▒v╬▓3 and ╬▒5╬▓1-type integrins, new activators were developed and their Structure-Activity Relationships (SAR) analysis deepened, enhancing their activity range towards the ╬▒4╬▓1 isoform. Moreover, to synthesize novel compounds active both against bacterial infections and pulmonary conditions of cystic fibrosis patients, new ╬▓-lactam candidates were studied. Among the abundant library of ╬▓-lactams prepared, mainly with antioxidant and antibacterial double activities, it was identified a single lead to be pharmacologically tested in vivo. Its synthesis was optimized up to the gram-scale, and pretreatment method and HPLC-MS/MS analytical protocol for sub-nanomolar quantifications were developed. Furthermore, replacement of acetoxy group in 4-acetoxy-azetidinone derivatives was studied with different nucleophiles and in aqueous media. A phosphate group was introduced and the reactivity exploited using different hydroxyapatites, obtaining biomaterials with multiple biological activities. Following the same kind of reactivity, a small series of molecules with a ╬▓-lactam and retinoic hybrid structure was synthesized as epigenetic regulators. Interacting with HDACs, two compounds were respectively identified as an inhibitor of cell proliferation and a differentiating agent on steam cells. Additionally, in collaboration with Professor L. De Cola at ISIS, University of Strasbourg, some new photochemically active ╬▓-lactam Pt (II) complexes were designed and synthesized to be used as bioprobes or theranostics. Finally, it was set up and optimized the preparation of new chiral proline-derived ╬▒-aminonitriles through an enantioselective Strecker reaction, and it was developed a chemo-enzymatic oxidative method for converting alcohols to aldehydes or acid in a selective manner, and amines to relative aldehydes, amides or imines. Moreover, enzymes and other green chemistry methodologies were used to prepare Active Pharmaceutical Ingredients (APIs)
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