Symmetries and degrees of freedom in 2-dimensional dual models

The 2-dimensional version of the Schwarz and Sen duality model (Tseytlin model) is analyzed at the classical and quantum levels. The solutions are obtained after removing the gauge dependent sector using the Dirac method. The Poincar\`e invariance is verified at both levels. An extension with global supersymmetry is also proposed.Comment: 3 pages, revtex, minor correction

I Quaderni di Careggi- Fifth issue- Landscape Observatories

Having regard to Recommendation CM/Rec (2008)3 on the Guidelines for the implementation of the European Landscape Convention, “landscape observatories, centers and institutes” are one of the main instruments for the implementation of landscape policies (II.3.3). They facilitate the collection and exchange of information and study protocols between states and local communities. This issue of the Quaderni di Careggi presents an international overview of the activities of landscape observatories, a reflection on their mission and effectiveness with regard to the ELC objectives, and a reflection on the relationships between the different subjects, thanks to the participation of institutional bodies, public officials as well as researchers and representatives of civil society. It reflects part of the scientific contributions which will be presented during the V Careggi Seminar (Florence, 27-28th June 2013)

Non-linear terms in 2D cosmology

In this work we investigate the behavior of two-dimensional (2D) cosmological models, starting with the Jackiw-Teitelboim (JT) theory of gravitation. A geometrical term, non-linear in the scalar curvature $R$, is added to the JT dynamics to test if it could play the role of dark energy in a 2D expanding universe. This formulation makes possible, first, the description of an early (inflationary) 2D universe, when the van der Waals (vdW) equation of state is used to construct the energy-momentum tensor of the gravitational sources. Second, it is found that for later times the non-linear term in $R$ can generate an old 2D universe in accelerated expansion, where an ordinary matter dominated era evolves into a decelerated/accelerated transition, giving to the dark energy effects a geometrical origin. The results emerge through numerical analysis, following the evolution in time of the scale factor, its acceleration, and the energy densities of constituents.Comment: tex file plus figures in two zipped files. To appear in Europhys. Let

Transition from accelerated to decelerated regimes in JT and CGHS cosmologies

In this work we discuss the possibility of positive-acceleration regimes, and their transition to decelerated regimes, in two-dimensional (2D) cosmological models. We use general relativity and the thermodynamics in a 2D space-time, where the gas is seen as the sources of the gravitational field. An early-Universe model is analyzed where the state equation of van der Waals is used, replacing the usual barotropic equation. We show that this substitution permits the simulation of a period of inflation, followed by a negative-acceleration era. The dynamical behavior of the system follows from the solution of the Jackiw-Teitelboim equations (JT equations) and the energy-momentum conservation laws. In a second stage we focus the Callan-Giddings-Harvey-Strominger model (CGHS model); here the transition from the inflationary period to the decelerated period is also present between the solutions, although this result depend strongly on the initial conditions used for the dilaton field. The temporal evolution of the cosmic scale function, its acceleration, the energy density and the hydrostatic pressure are the physical quantities obtained in through the analysis.Comment: To appear in Europhysics Letter

Landscape Observatories in Europe from the ELC Recommendations to Local Initiatives. Rationale and Issues of the Seminar

Having regard to Recommendation CM/Rec (2008)3 on the Guidelines for the implementation of the European Landscape Convention, “landscape observatories, centers and institutes” are one of the main instruments for the implementation of landscape policies (II.3.3). They facilitate the collection and exchange of information and study protocols between states and local communities. This issue of the Quaderni di Careggi presents an international overview of the activities of landscape observatories, a reflection on their mission and effectiveness with regard to the ELC objectives, and a reflection on the relationships between the different subjects, thanks to the participation of institutional bodies, public officials as well as researchers and representatives of civil society. It reflects part of the scientific contributions which will be presented during the V Careggi Seminar (Florence, 27-28th June 2013

Inflationary and dark energy regimes in 2+1 dimensions

In this work we investigate the behavior of three-dimensional (3D) cosmological models. The simulation of inflationary and dark-energy-dominated eras are among the possible results in these 3D formulations; taking as starting point the results obtained by Cornish and Frankel. Motivated by those results, we investigate, first, the inflationary case where we consider a two-constituent cosmological fluid: the scalar field represents the hypothetical inflaton which is in gravitational interaction with a matter/radiation contribution. For the description of an old universe, it is possible to simulate its evolution starting with a matter dominated universe that faces a decelerated/accelerated transition due to the presence of the additional constituent (simulated by the scalar field or ruled by an exotic equation of state) that plays the role of dark energy. We obtain, through numerical analysis, the evolution in time of the scale factor, the acceleration, the energy densities, and the hydrostatic pressure of the constituents. The alternative scalar cosmology proposed by Cornish and Frankel is also under investigation in this work. In this case an inflationary model can be constructed when another non-polytropic equation of state (the van der Waals equation) is used to simulate the behavior of an early 3D universe.Comment: Latex file, plus 9 figures. To appear in General Relativity and Gravitatio

Thermodynamics and Kinetic Theory of Relativistic Gases in 2-D Cosmological Models

A kinetic theory of relativistic gases in a two-dimensional space is developed in order to obtain the equilibrium distribution function and the expressions for the fields of energy per particle, pressure, entropy per particle and heat capacities in equilibrium. Furthermore, by using the method of Chapman and Enskog for a kinetic model of the Boltzmann equation the non-equilibrium energy-momentum tensor and the entropy production rate are determined for a universe described by a two-dimensional Robertson-Walker metric. The solutions of the gravitational field equations that consider the non-equilibrium energy-momentum tensor - associated with the coefficient of bulk viscosity - show that opposed to the four-dimensional case, the cosmic scale factor attains a maximum value at a finite time decreasing to a "big crunch" and that there exists a solution of the gravitational field equations corresponding to a "false vacuum". The evolution of the fields of pressure, energy density and entropy production rate with the time is also discussed.Comment: 23 pages, accepted in PR

Could specific EKG markers identify a pharmacologically induced type 1 Brugada pattern? Insights from a large, single-centre cohort

Abstract Funding Acknowledgements Type of funding sources: None. Background. Pharmacological (Ajmaline) induction of a type 1 Brugada pattern is currently considered mandatory for the diagnosis of Brugada syndrome. However, performing the test requires time and healthcare resources. Some EKG markers have been proposed as predictors of positive result at Ajmaline test. Aim. To evaluate in a large population the predictive value of multiple EKG markers for Ajmaline test results. Methods. We retrospectively analysed consecutive patients (pts) referred to our Centre to perform Ajmaline test. All pts had type 2 Brugada pattern detected at a conventional EKG or were relatives of pts with positive Ajmaline test, with or without type 2 Brugada pattern at EKG. All pts performed the Ajmaline pharmacological test (1 mg/Kg iv) with EKG "superior" right precordial unipolar derivations monitoring. To determine whether clinical parameters (age, gender, cardiomyopathy, history of arrhythmias, symptoms, familiarity) and EKG markers (heart rate (HR), PR duration, R1V1 and SV6 duration and amplitude, QRSV1/QRSV6 duration, V1 and V2 ST amplitude (coved or saddle back pattern) were independently associated to positivity at Ajmaline test, a logistic regression model was applied. Results. From January 2010 to December 2019 we evaluated 442 consecutive pts: mean age 40.1 ± 14.5 years; 273 (65%) male; 352 (80%) pts were included because of type 2 Brugada pattern at EKG and 90 (20%) for familial screening. The Ajmaline test was positive in 150 (34%) pts. At multivariate logistic regression analysis adjusted for baseline confounders, age > 45 years (OR= 1.64, 95%CI: 1.03 to 2.54; p = 0.0385), female gender (OR = 1.79, 95%CI: 1.12 to 2.85; p = 0.0141), HR > 60 bpm (OR = 2.44, 95%CI: 1.48 to 4.03; p = 0.0005), QRSV1/QRSV6 duration (msec) >1 (OR = 5.34, 95%CI: 3.28 to 8.69; p < 0.0001) and non isoelectric pattern (coved/saddle back) in V2 (OR = 1.93, 95%CI: 1.03 to 3.63, p = 0.0416) remained associated with a positive Ajmaline test. The percentage of pts with positive Ajmaline test increased according to the presence of significant EKG markers in their risk profile: 11.3% (8 out 71, absence of both QRSV1/QRSV6 duration (msec) >1 and V2 non isoelectric pattern), 24.3% (50 out 206, presence of only V2 non isoelectric pattern), 48.5% (16 out 33, presence of only QRSV1/QRSV6 duration (msec) >1), 57.6% (76 out 132, presence of both factors). Conclusions. In our large population: 1) we confirmed the positive predictive power of QRSV1/QRSV6 duration (msec) >1 and of a non isoelectric pattern (coved/saddle back) in V2 for a pharmacologically induced type 1 Brugada pattern; 2) we observed a non-negligible percentage of pts who would not be correctly diagnosed for type 1 Brugada pattern, if selected according to an EKG parameters-based prescreening

Gravitational-wave memory revisited: memory from the merger and recoil of binary black holes

Gravitational-wave memory refers to the permanent displacement of the test masses in an idealized (freely-falling) gravitational-wave interferometer. Inspiraling binaries produce a particularly interesting form of memory--the Christodoulou memory. Although it originates from nonlinear interactions at 2.5 post-Newtonian order, the Christodoulou memory affects the gravitational-wave amplitude at leading (Newtonian) order. Previous calculations have computed this non-oscillatory amplitude correction during the inspiral phase of binary coalescence. Using an "effective-one-body" description calibrated with the results of numerical relativity simulations, the evolution of the memory during the inspiral, merger, and ringdown phases, as well as the memory's final saturation value, are calculated. Using this model for the memory, the prospects for its detection are examined, particularly for supermassive black hole binary coalescences that LISA will detect with high signal-to-noise ratios. Coalescing binary black holes also experience center-of-mass recoil due to the anisotropic emission of gravitational radiation. These recoils can manifest themselves in the gravitational-wave signal in the form of a "linear" memory and a Doppler shift of the quasi-normal-mode frequencies. The prospects for observing these effects are also discussed.Comment: 6 pages, 2 figures; accepted to the proceedings of the 7th International LISA Symposium; v2: updated figures and signal-to-noise ratios, several minor changes to the tex