4,473 research outputs found
Obstructive sleep apnea syndrome in the pediatric age: the role of the dentist
Sleep disordered breathing in children designates a wide spectrum of respiratory disorders characterized by partial or complete obstruction of the upper airways. It ranges from primary snoring, its mildest clinical manifestation, to obstructive sleep apnea syndrome (OSAS): complete obstruction of the upper airways with cessation of airflow. The aim of this paper is to highlight the roles of the pediatric dentist and the orthodontist in the therapeutic approach to pediatric OSAS as a "sentinel" who can detect early signs of the disease for immediate referral to the otolaryngologist and as an active participant in therapy
Statistical Mesoscopic Hydro-Thermodynamics: The Description of Kinetics and Hydrodynamics of Nonequilibrium Processes in Single Liquids
Hydrodynamics, a term apparently introduced by Daniel Bernoulli (1700-1783)
to comprise hydrostatic and hydraulics, has a long history with several
theoretical approaches. Here, after a descriptive introduction, we present
so-called mesoscopic hydro-thermodynamics, which is also referred to as
higher-order generalized hydrodynamics, built within the framework of a
mechanical-statistical formalism. It consists of a description of the material
and heat motion of fluids in terms of the corresponding densities and their
associated fluxes of all orders. In this way, movements are characterized in
terms of intermediate to short wavelengths and intermediate to high
frequencies. The fluxes have associated Maxwell-like times, which play an
important role in determining the appropriate contraction of the description
(of the enormous set of fluxes of all orders) necessary to address the
characterization of the motion in each experimental setup. This study is an
extension of a preliminary article: Physical Review E \textbf{91}, 063011
(2015)
Non-extensive entropy from incomplete knowledge of Shannon entropy?
In this paper we give an interpretation of Tsallis' nonextensive statistical
mechanics based upon the information-theoretic point of view of Luzzi et al.
[cond-mat/0306217; cond-mat/0306247; cond-mat/0307325], suggesting Tsallis'
entropy to be not a fundamental concept but rather a derived one, stemming from
an incomplete knowledge of the system, not taking properly into account its
interaction with the environment. This interpretation seems to avoid some
problems occurring with the original interpretation of Tsallis statistics.Comment: v.4. 11 pages. Title changed. Content substantially changed: added
discussion of several points raised by various referees and readers; Also
reference made to work by Luzzi, Vasconcellos, Galvao Ramos. Physica Scripta,
to appea
The SCIANTIX code for fission gas behaviour: Status, upgrades, separate-effect validation, and future developments
SCIANTIX is a 0D, open-source code designed to model inert gas behaviour within nuclear fuel at the scale of the grain. The code predominantly employs mechanistic approaches based on kinetic rate-theory models to calculate engineering quantities, such as fission gas release and gaseous fuel swelling. Since its release, SCIANTIX has undergone significant improvements, including the incorporation of new modelling and numerical capabilities. The code architecture has been revamped, embracing an object-orientated structure improving the overall efficiency
and usability. This work provides a concise overview of the current state of the SCIANTIX code, highlighting recent updates and advancements. Each SCIANTIX model is presented along with the corresponding separate-effect validation database, which is used to assess its accuracy and predictions
Constraining the evolution of the CMB temperature with SZ measurements from Planck data
The CMB temperature-redshift relation, T_CMB(z)=T_0(1+z), is a key prediction
of the standard cosmology, but is violated in many non standard models.
Constraining possible deviations to this law is an effective way to test the
LambdaCDM paradigm and to search for hints of new physics. We have determined
T_CMB(z), with a precision up to 3%, for a subsample (104 clusters) of the
Planck SZ cluster catalog, at redshift in the range 0.01-- 0.94, using
measurements of the spectrum of the Sunyaev Zel'dovich effect obtained from
Planck temperature maps at frequencies from 70 to 353 GHz. The method adopted
to provide individual determinations of T_CMB(z) at cluster redshift relies on
the use of SZ intensity change, Delta I_SZ(nu), at different frequencies, and
on a Monte-Carlo Markov Chain approach. By applying this method to the sample
of 104 clusters, we limit possible deviations of the form
T_CMB(z)=T_0(1+z)^(1-beta) to be beta= 0.022 +/- 0.018, at 1 sigma uncertainty,
consistent with the prediction of the standard model. Combining these
measurements with previously published results we get beta=0.016+/-0.012.Comment: submitted to JCAP, 21 pages, 8 figure
Method of comparison equations for cosmological perturbations
We apply the method of comparison equations to study cosmological
perturbations during inflation, obtaining the full power spectra of scalar and
tensor perturbations to first and to second order in the slow-roll parameters.
We compare our results with those derived by means of other methods, in
particular the Green's function method and the improved WKB approximation, and
find agreement for the slow-roll structure. The method of comparison equations,
just as the improved WKB approximation, can however be applied to more general
situations where the slow-roll approximation fails.Comment: 20 pages, 10 figure
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