Biography:

One of their most recent publications is Genetic approach to the study of heterogeneity of affective disorders. Which was published in journal Journal of Affective Disorders.

More information about M. Gasperini research including statistics on their citations can be found on their Copernicus Academic profile page.

M. Gasperini's Articles: (9)

Genetic approach to the study of heterogeneity of affective disorders

AbstractIn the present paper we compared the results of the application of segregation analysis, under two different single major locus (SML) transmission hypotheses, a dominant one with sex effect and a recessive one, to the families of 202 probands with major depression, recurrent and bipolar disorder. In the first analysis we considered only secondary cases with major affective disorders (bipolar disorders and major depression, recurrent), in the second one we included as affected phenotypes also relatives with atypical depression, dysthymic and cyclothymic disorders. Results indicated that considering spectrum disorders greatly modified familial segregation patterns.

On the gravitational interactions of ultrarelativistic particles

AbstractIt is shown that an anomalous energy-dependent modification of Newton's law could be obtained not only in a broken supersymmetry model of gravity, but also in the case of broken local Lorentz symmetry; in particular, the explicit expression for the radial acceleration of a test particle, in the field of a static central source, is derived in the framework of a quasi-riemannian geometric theory with SO(3) gauge invariance. It is then suggested that a measurement of the gravitational properties of relativistic microscopic matter and antimatter (whose importance has been recently stressed for quantum-gravity and supersymmetric models) could be interpreted also as a test on the eventual Lorentz noninvariance of high-energy gravitational dynamics.

Short-range interactions in gravitational theories with torsion and quadratic lagrangian

AbstractConsidering a nine-parameter lagrangian quadratic in torsion and curvature, we derive the general condition which must be satisfied by the parameters in order to obtain, in the weak field limit, a Yukawa-type correction to the static Newton potential. This condition is shown to be in general not incompatible with a different set of restrictions needed to avoid the presence of ghosts and tachyons.

Adiabatic perturbations and minimal size of the de Sitter vacuum

AbstractWe consider transitions for a higher dimensional to a lower dimensional de Sitter phase. We show that, if the transitions are adiabatic, the evolution necessarily passes through a state of maximal curvature (minimal size). This minimal size depends only on the total entropy content, but the dependence is so weak that no fine tuning is needed in order to set the minimum at the Planck scale.

Kinematic interpretation of string instability in a background gravitational field

AbstractThe unstable regime in which the string oscillating modes develop imaginary frequencies is shown to be characterized, kinematically, by a positive relative acceleration among the different points of the string. Instability occurs when this acceleration, induced by the background curvature, is large enough to make the extension of the corresponding causally connected region smaller than the string maximal size. This kinematic characterization is applied, in particular, to discuss string instability in a static and spherically symmetric gravitational background.

Inflation in scalar-tensor gravity with quadratic Gauss-Bonnet self-interactions

AbstractWe present cosmological solutions for a graviton-plus-dilaton system coupled to a perfect fluid source, including quadratic curvature corrections. We show that, even in the absence of a dilaton self-interaction potential, isotropic superinflation (H>0) can be realized for a wide range of equations of state, which includes in particular the ordinary cases of dust matter and radiation. It is found that in this context inflation can be produced more efficiently than in previous superinflationary models based on the contraction of internal dimensions.

A problem with non-abelian duality?

AbstractWe investigate duality transformations in a class of backgrounds with non-Abelian isometries, i.e. Bianchi-type (homogeneous) cosmologies in arbitrary dimensions. Simple duality transformations for the metric and the antisymmetric tensor field, generalizing those known from the Abelian isometry (Bianchi I) case, are obtained using either a Lagrangian or a Hamiltonian approach. Applying these prescriptions to a specific conformally invariant σ-model, we show that no dilaton transformation leads to a new conformal background. Some possible ways out of the problem are suggested.

Singularity and exit problems in two-dimensional string cosmology☆

AbstractA broad class of two-dimensional loop-corrected dilaton gravity models exhibit cosmological solutions that interpolate between the string perturbative vacuum and a background with asymptotically flat metric and linearly growing dilaton. The curvature singularities of the corresponding tree-level solutions are smoothed out, but no branch-change occurs. Thus, even in the presence of a non-perturbative potential, the system is not attracted by physically interesting fixed points with constant dilaton, and the exit problem of string cosmology persists.

Perturbations in a non-singular bouncing Universe

AbstractWe complement the low-energy gravi-dilaton effective action of string theory with a non-local, general-covariant dilaton potential, and obtain homogeneous solutions describing a non-singular (bouncing-curvature) cosmology. We then compute, both analytically and numerically, the spectrum of amplified scalar and tensor perturbations, and draw some general lessons on how to extract observable consequences from pre-big bang and ekpyrotic scenarios.

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