101,739 research outputs found
Trend extraction in functional data of amplitudes of R and T waves in exercise electrocardiogram
No full textThe amplitudes of R and T waves of the electrocardiogram recorded during the
exercise test show both large inter- and intra-individual variability in response to
stress. We analyze a dataset of 65 normal subjects undergoing ambulatory test. We
model the dataset of R and T series in the framework of functional data, assuming
that the individual series are realizations of a non stationary process, centered at the
population trend. We test the time variability of this trend computing a simultaneous
confidence band and the zero crossing of its derivative. The analysis
shows that the amplitudes of the R and T waves have opposite responses to stress,
consisting respectively in a bump and a dip at the early recovery stage.
Our findings support the existence of a relationship between R and T wave
amplitudes and respectively diastolic and systolic ventricular volumes
A general approach to systems with randomly pinned particles: Unfolding and clarifying the Random Pinning Glass Transition
No full textPinning a fraction of particles from an equilibrium configuration in supercooled liquids has been recently proposed as a way to induce a new kind of glass transition, the Random Pinning Glass Transition (RPGT). The RPGT has been predicted to share some features of standard thermodynamic glass transitions and usual first-order ones. Thanks to its special nature, the approach and the study of the RPGT appears to be a fairly reachable task compared to the daunting problem of inspecting standard glass transitions. In this letter we generalize the pinning particle procedure. We study a mean-field system where the pinned configuration is extracted from the equilibrium distribution at temperature T′ and the thermodynamics of the non-pinned particles is observed at a lower temperature T. A more complicated physics emerges from this generalization eventually clarifying the origin and the peculiar characteristics of the RPGT
Joint distribution of the process and its sojourn time on the positive half-line for pseudo-processes governed by high-order heat equation.
No full textConsider the high-order heat-type equation ∂u/∂t = ±∂Nu/∂xN for an integer N > 2 and introduce the related Markov pseudo-process (X(t))t≥0. In this paper, we study the sojourn time T(t) in the interval [0, +∞) up to a fixed time t for this pseudo-process. We provide explicit expressions for the joint distribution of the couple (T(t),X(t))
Imaging diagnostico delle polmoniti nell'anziano
No full textEsposizione delle metodiche di imaging nelle polmoniti infettive e non infettive nei pazienti geriatric
Nodal area distribution for arithmetic random waves
No full textWe obtain the limiting distribution of the nodal area of random Gaussian Laplace eigenfunctions on (three-dimensional ``arithmetic random waves"). We prove that, as the multiplicity of the eigenspace goes to infinity, the nodal area converges to a universal, non-Gaussian distribution. Universality follows from the equidistribution of lattice points on the sphere. Our arguments rely on the Wiener chaos expansion of the nodal area: we show that, analogous to the two-dimensional case addressed by Marinucci et al., [Geom. Funct. Anal. 26 (2016), pp. 926-960] the fluctuations are dominated by the fourth-order chaotic component. The proof builds upon recent results from Benatar and Maffiucci [Int. Math. Res. Not. IMRN (to appear)] that establish an upper bound for the number of nondegenerate correlations of lattice points on the sphere. We finally discuss higher-dimensional extensions of our result
Cascades of particles moving at finite velocity in hyperbolic spaces
No full textA branching process of particles moving at finite velocity over the geodesic lines of the hyperbolic space (Poincaré half-plane and Poincaré disk) is examined. Each particle can split into two particles only once at Poisson spaced times and deviates orthogonally when splitted. At time t , after N (t ) Poisson events, there are N (t ) + 1 particles moving along different geodesic lines. We are able to obtain the exact expression of the mean hyperbolic distance of the center of mass of the cloud of particles. We derive such mean hyperbolic distance from two different and independent ways and we study the behavior of the relevant expression as t increases and for different values of the parameters c (hyperbolic velocity of motion) and λ (rate of reproduction). The mean hyperbolic distance of each moving particle is also examined and a useful representation, as the distance of a randomly stopped particle moving over the main geodesic line, is presented
Cellular mediators of inflammation: tregs and t(h)17 cells in gastrointestinal diseases.
No full textHuman lymphocyte subpopulations were originally classified as T- and B-cells in the 70s. Later, with the development of monoclonal antibodies, it became possible to recognize, within the T-cells, functional populations: CD4(+) and CD8(+). These populations were usually referred to as "helper" and "suppressor" cells, respectively. However several investigations within the CD8 cells failed to detect a true suppressor activity. Therefore the term suppressor was neglected because it generated confusion. Much later, true suppressor activity was recognized in a subpopulation of CD4 cells characterized by high levels of CD25. The novel population is usually referred to as T regulatory cells (Tregs) and it is characterized by the expression of FoxP3. The heterogeneity of CD4 cells was further expanded by the recent description of a novel subpopulation characterized by production of IL-17. These cells are generally referred to as T(H)17. They contribute to regulate the overall immune response together with other cytokine-producing populations. Treg and T(H)17 cells are related because they could derive from a common progenitor, depending on the presence of certain cytokines. The purpose of this review is to summarize recent findings of the role of these novel populations in the field of human gastroenterological disease
The mixed p-spin model: selecting, following and losing states
No full textDifferently to crystals, amorphous materials can preserve the memory of their past and their thermodynamic properties are directly connected to the protocol used to prepare them (think of ordinary glasses). In this thesis, I present an abstract model of glass for which many analytical results are already known: the p-spin spherical model (introduced 30 years ago). In particular, I focus the attention on a particular preparation protocol: the system is equilibrated at one temperature T’ and instantaneously cooled to a second temperature T. If choosing an opportunely tuned "mixed" p-spin model, the aforementioned protocol shows a phenomenology analogous to that of real glass. The system presents final properties that strictly depend on the first temperature T’, thus preserving the memory of the initial condition. This is the first analytically solvable model which presents such a dependence, and it is expected to bring new insights into the theoretical understanding of amorphous material
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