Papers by silvio mercadante
Current HIV Research, 2014
Switch to unboosted atazanavir (ATV) is an attractive option due to convenience and tolerability ... more Switch to unboosted atazanavir (ATV) is an attractive option due to convenience and tolerability in HIV-positive patients. With limited available data we investigated the determinants of long-term efficacy and the consequences of virological failure of unboosted atazanavir-based regimens. Retrospective analysis in two Italian large outpatient clinics including demographic, immunovirological, resistance and pharmacokinetic data. 249 patients receiving atazanavir (400 mg once-daily) plus 2 NRTIs were included; 163 were males (65.5%) and median age was 47 years (42-51.5). Median CD4+ T-cell count was 396/uL (261-583); 146 (58.6%) presented a viral load < 50 copies/mL. Over a median follow up of 157 weeks (106-203) 193 patients (77.5%) were still on treatment with 10 (4%) and 2 (0.8%) stopping for virological failure or toxicity, respectively. Ten patients with virological failure presented newly selected resistance associated mutations (RAMs) for NRTIs (2/10) or ATV (4/10, one I50L). Total cholesterol and triglycerides showed significant decreases at 48 [-4 mg/dL and -41 mg/dL] and 96 weeks [-14 mg/dL and -54 mg/dL] as compared to baseline. At multivariate analysis a genotypic sensitivity score ≤ 1, atazanavir RAMs > 1 and suboptimal adherence were independently associated with virological failure; in lamivudine/emtricitabine-treated patients the presence of M184V (without other NRTI RAMs) was not associated with virological failure. Unboosted-atazanavir containing regimens were efficacious (with uncommon virological failures) and well-tolerated (with improvements in lipid profile over time) treatments in HIV-positive patients. Isolated M184V in lamivudine/emtricitabine recipients was not associated with higher failure rates supporting the use of functional ATV-based dual therapies as maintenance strategies.
We review the Lagrangian formulation of (generalised) Noether symmetries in the framework of Calc... more We review the Lagrangian formulation of (generalised) Noether symmetries in the framework of Calculus of Variations in Jet Bundles, with a special attention to so-called "Natural Theories" and "Gauge-Natural Theories" that include all relevant Field Theories and physical applications (from Mechanics to General Relativity, to Gauge Theories, Supersymmetric Theories, Spinors, etc.). It is discussed how the use of Poincaré-Cartan forms and decompositions of natural (or gauge-natural) variational operators give rise to notions such as "generators of Noether symmetries", energy and reduced energy flow, Bianchi identities, weak and strong conservation laws, covariant conservation laws, Hamiltonian-like conservation laws (such as, e.g., so-called ADM laws in General Relativity) with emphasis on the physical interpretation of the quantities calculated in specific cases (energy, angular momentum, entropy, etc.). A few substantially new and very recent applications/examples are presented to better show the power of the methods introduced: one in Classical Mechanics (definition of strong conservation laws in a frame-independent setting and a discussion on the way in which conserved quantities depend on the choice of an observer); one in Classical Field Theories (energy and entropy in General Relativity, in its standard formulation, in its spin-frame formulation, in its first order formulation "à la Palatini" and in its extensions to Non-Linear Gravity Theories); one in Quantum Field Theories (applications to conservation laws in Loop Quantum Gravity via spin connections and Barbero-Immirzi connections).
Abstract: General Relativity isn’t the definitive theory of Gravitation. The attempts to recover ... more Abstract: General Relativity isn’t the definitive theory of Gravitation. The attempts to recover it, with respect to the latest observative data, leads to very strange physical entites as the Dark Energy & Dark Matter. On the other hand, the attempts to produce generalized theories gives rise to mathematical difficulties that need workarounds that
Abstract: We shall review different approaches to the entropy of self-gravitating systems in Gene... more Abstract: We shall review different approaches to the entropy of self-gravitating systems in General Relativity. Then we shall discuss in detail the macroscopic approach based on à la Clausius point of view. Recent developments will be reviewed discussing the aims as well as the assumptions which the framework is based on.
It is nowadays clear that General Relativity cannot be the definitive theory of Gravitation. The ... more It is nowadays clear that General Relativity cannot be the definitive theory of Gravitation. The attempts to recover it, with respect to the latest observative data, lead in fact to very strange physical entities as the Dark Energy & Dark Matter. On the other hand, the attempts to produce generalized theories give rise to mathematical difficulties that need workarounds which, in turn, generate problems from the interpretative viewpoint. We present here a completely new approach to the mathematical objects in terms of which a theory of Gravitation may be written in a first-order (à la Palatini) formalism, and introduce the concept of Dark Metric.
It is shown that when in a higher order variational principle one fixes fields at the boundary le... more It is shown that when in a higher order variational principle one fixes fields at the boundary leaving the field derivatives unconstrained, then the variational principle (in particular the solution space) is not invariant with respect to the addition of boundary terms to the action, as it happens instead when the correct procedure is applied. Examples are considered to show how leaving derivatives of fields unconstrained affects the physical interpretation of the model. This is justified in particular by the need of clarifying the issue for the purpose of applications to relativistic gravitational theories, where a bit of confusion still exists. On the contrary, as it is well known for variational principles of order k, if one fixes variables together with their derivatives (up to order k − 1) on the boundary then boundary terms leave solution space invariant.
International Journal of Geometric Methods in Modern Physics, 2014
International Society for General Relativity and Gravitation and he served as a member of the Boa... more International Society for General Relativity and Gravitation and he served as a member of the Board of the ISGRG for nine years (1986-1995). He was an associate editor of the Journal of General Relativity and Gravitation, since 1999, and Managing Editor of the "International Journal of Geometrical Methods in Modern Physics". Italian relativists will definitely miss his scientific competence and enthusiasm.
International Journal of Geometric Methods in Modern Physics, 2010
We shall consider here extended theories of gravitation in the metric-affine formalism with matte... more We shall consider here extended theories of gravitation in the metric-affine formalism with matter coupled directly to the connection. A sufficiently general procedure will be exhibited to solve the resulting field equation associated to the connection. As special cases one has the no-coupling case (which is standard in f(R) literature) as well as the cases already analyzed in [1].
International Journal of Geometric Methods in Modern Physics, 2008
In the framework of augmented variational principles we recover here the conserved quantities pro... more In the framework of augmented variational principles we recover here the conserved quantities proposed by Gibbons et al. for Kerr–AdS solutions.
International Journal of Geometric Methods in Modern Physics, 2005
We shall review some results about the globality of Chern–Simons theory in any odd dimension. The... more We shall review some results about the globality of Chern–Simons theory in any odd dimension. The relation between Chern–Simons theories and some recent results about conservation laws are also considered in detail.
Emerging Infectious Diseases, 2013
Migration from low-and middle-income countries to high-income countries increasingly determines t... more Migration from low-and middle-income countries to high-income countries increasingly determines the severity of tuberculosis (TB) cases in the adopted country. Socially marginalized groups, about whom little is known, may account for a reservoir of TB among the immigrant populations. We investigated the rates of and risk factors for Mycobacterium tuberculosis transmission, infection, and disease in a cohort of 27,358 socially marginalized immigrants who were systematically screened (1991-2010) in an area of Italy with low TB incidence. Overall TB and latent TB infection prevalence and annual tuberculin skin testing conversion rates (i.e., incidence of new infection) were 2.7%, 34.6%, and 1.7%, respectively. Prevalence of both TB and latent TB infection and incidence of infection increased as a function of the estimated TB incidence in the immigrants' countries of origin. Annual infection incidence decreased with time elapsed since immigration. These findings have implications for control policy and immigrant screening in countries with a low prevalence of TB.
Foundations of Physics, 2009
It is nowadays clear that General Relativity cannot be the definitive theory of Gravitation due t... more It is nowadays clear that General Relativity cannot be the definitive theory of Gravitation due to several shortcomings that come out both from theoretical and experimental viewpoints. At large scales (astrophysical and cosmological) the attempts to match it with the latest observational data lead to invoke Dark Energy and Dark Matter as the bulk components of the cosmic fluid. Since no final evidence, at fundamental level, exists for such ingredients, it is clear that General Relativity presents shortcomings at infrared scales. On the other hand, the attempts to formulate more general theories than Einstein's one give rise to mathematical difficulties that need workarounds that, in turn, generate problems from the interpretative viewpoint. We present here a completely new approach to the mathematical objects in terms of which a theory of Gravitation may be written in a first-order (à la Palatini) formalism, and introduce the concept of Dark Metric which could completely bypass the introduction of disturbing concepts as Dark Energy and Dark Matter.
International Journal of Geometric Methods in Modern Physics, 2010
We shall here propose a class of relativistic theories of gravitation, based on a foundational pa... more We shall here propose a class of relativistic theories of gravitation, based on a foundational paper of Ehlers Pirani and Schild (EPS). All "extended theories of gravitation" (also known as f(R) theories) in Palatini formalism are shown to belong to this class. In a forthcoming paper, we shall show that this class of theories contains other more general examples. EPS framework helps in the interpretation and solution of these models that however have exotic behaviors even compared to f(R) theories.
International Journal of Geometric Methods in Modern Physics, 2008
In the framework of augmented variational principles we recover here the conserved quantities pro... more In the framework of augmented variational principles we recover here the conserved quantities proposed by Gibbons et al. for Kerr–AdS solutions.
International Journal of Geometric Methods in Modern Physics, 2014
We shall consider possible potentials emerging in (purely metric) f(R)-theories for the conformal... more We shall consider possible potentials emerging in (purely metric) f(R)-theories for the conformal scalar field. We shall discuss possible approaches to determine models with specific potentials and show that some potentials qualitatively similar to the typical Higgs potentials are allowed.
International Journal of Geometric Methods in Modern Physics, 2014
General Relativity is not the definitive theory of Gravitation due to several shortcomings which ... more General Relativity is not the definitive theory of Gravitation due to several shortcomings which are coming out both from theoretical and experimental viewpoints. At large scales (astrophysical and cosmological scales) the attempts to match it with the today observational data lead to invoke Dark Energy and Dark Matter as the bulk components of the cosmic fluid. Since no final evidence, at fundamental level, exists for such ingredients, it is clear that General Relativity presents shortcomings at infrared scales. On the other hand, the attempts to formulate theories more general than the Einstein one give rise to mathematical difficulties that need workarounds which, in turn, generate problems from the interpretative viewpoint. We present here a completely new approach to the mathematical objects in terms of which a theory of Gravitation may be written in a first-order (à la Palatini) formalism, and introduce the concept of Dark Metric which could completely bypass the introduction of disturbing concepts as Dark Energy and Dark Matter.
General Relativity is not the definitive theory of Gravitation due to several shortcomings which ... more General Relativity is not the definitive theory of Gravitation due to several shortcomings which are coming out both from theoretical and experimental viewpoints. At large scales (astrophysical and cosmological scales) the attempts to match it with the today observational data lead to invoke Dark Energy and Dark Matter as the bulk components of the cosmic fluid. Since no final evidence, at fundamental level, exists for such ingredients, it is clear that General Relativity presents shortcomings at infrared scales. On the other hand, the attempts to formulate theories more general than the Einstein one give rise to mathematical difficulties that need workarounds which, in turn, generate problems from the interpretative viewpoint. We present here a completely new approach to the mathematical objects in terms of which a theory of Gravitation may be written in a first-order (à la Palatini) formalism, and introduce the concept of Dark Metric which could completely bypass the introduction of disturbing concepts as Dark Energy and Dark Matter.
International Journal of Geometric Methods in Modern Physics, 2014
We shall consider possible potentials emerging in (purely metric) f(R)-theories for the conformal... more We shall consider possible potentials emerging in (purely metric) f(R)-theories for the conformal scalar field. We shall discuss possible approaches to determine models with specific potentials and show that some potentials qualitatively similar to the typical Higgs potentials are allowed.
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Papers by silvio mercadante