12,776 research outputs found
S-estimation of hidden Markov models
A method for robust estimation of dynamic mixtures of multivariate distributions is proposed. The EM algorithm is modified by replacing the classical M-step
with high breakdown S-estimation of location and scatter, performed by using the
bisquare multivariate S-estimator. Estimates are obtained by solving a system of estimating equations that are characterized by component specific sets of weights, based on
robust Mahalanobis-type distances. Convergence of the resulting algorithm is proved
and its finite sample behavior is investigated by means of a brief simulation study and
n application to a multivariate time series of daily returns for seven stock markets
Halphen conditions and postulation of nodes
We give sharp lower bounds for the postulation of the nodes of a general
plane projection of a smooth connected curve C in P^r and we study the
relationships with the geometry of the embedding. Strict connections with
Castelnuovo's theory and Halphen's theory are shown.Comment: LaTeX, 26 page
Energy density fluctuations in Early Universe
The primordial nucleosinthesys of the element can be influenced by the
transitions of phase that take place after the Big Bang, such as the QCD
transition. In order to study the effect of this phase transition, in this work
we compute the time evolution of thermodynamical quantities of the early
universe, focusing on temperature and energy density fluctuations, by solving
the relevant equations of motion using as input the lattice QCD equation of
state to describe the strongly interacting matter in the early universe plasma.
We also study the effect of a primordial strong magnetic field by means of a
phenomenological equation of state. Our results show that small inhomogeneities
of strongly interacting matter in the early Universe are moderately damped
during the crossover.Comment: 4 pages, 2 figures. Talk given at Sventh European Summer School on
Experimental Nuclear Astrophysics, 15-27 September 2013, Santa Tecla (CT) -
Ital
Digging deep the oil world: corporate liability and environmental justice strategies
The impacts provoked by the expanding oil industry encompass environmental destruction, health impacts and violations of human rights. The increasing contamination jeopardizes safe conditions of life and destroys means of livelihood of vulnerable communities and of those relying on healthy ecosystems. Local communities, feeling that they are simply sacrificed to the oil industry, see themselves involved in social conflict. They are experiencing forms of environmental discrimination and might even face criminalisation of the protest when they stand up to defend their rights promoting the chilly effect on others who need and want to defend themselves and the environment. In fact, the number of lawsuits demanding justice for environmental, social, economical and cultural damages provoked by oil companies are increasing as well as their media visibility. Yet most outcomes are not satisfactory in tackling impacted communities claims for justice. This paper describes the most recent trends regarding oil corporations’ responsibilities and use of procedural justice by civil society through the review of emblematic legal cases
Policy Rules, Regime Switches, and Trend Inflation: An Empirical Investigation for the U.S.
This paper estimates Taylor rules featuring instabilities in policy parameters, switches in policy shocks' volatility, and time-varying trend inflation using post-WWII U.S. data. The model embedding the stochastic target performs better in terms of data-fit and identification of the changes in the FOMC's chairmanships. Policy breaks are found not to be synchronized with variations in policy shocks' volatilities. Finally, we detect a negative correlation between systematic monetary policy aggressiveness and inflation gap persistence.
Zero-gravity cloud physics laboratory: Experiment program definition and preliminary laboratory concept studies
The experiment program definition and preliminary laboratory concept studies on the zero G cloud physics laboratory are reported. This program involves the definition and development of an atmospheric cloud physics laboratory and the selection and delineations of a set of candidate experiments that must utilize the unique environment of zero gravity or near zero gravity
Ivabradine: a preliminary observation for a new terapeutic role in patients with multiple organ dysfunction syndrome
[No abstract available
Critical Endpoint and Inverse Magnetic Catalysis for Finite Temperature and Density Quark Matter in a Magnetic Background
In this article we study chiral symmetry breaking for quark matter in a
magnetic background, , at finite temperature and quark chemical
potential, , making use of the Ginzburg-Landau effective action formalism.
As a microscopic model to compute the effective action we use the renormalized
quark-meson model. Our main goal is to study the evolution of the critical
endpoint, , as a function of the magnetic field strength, and
investigate on the realization of inverse magnetic catalysis at finite chemical
potential. We find that the phase transition at zero chemical potential is
always of the second order; for small and intermediate values of ,
moves towards small , while for larger it moves
towards moderately larger values of . Our results are in agreement with
the inverse magnetic catalysis scenario at finite chemical potential and not
too large values of the magnetic field, while at larger direct magnetic
catalysis sets in.Comment: 6 pages, 2 figure
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