1,367,938 research outputs found
Annotazioni linguistiche alla Cronica de' Matematici di Bernardino Baldi
No full textIl saggio riguarda uno dei più caratteristici lavori del Baldi, risalente agli inizi del Seicento. Poiché ancora il manoscritto non è stato pubblicato (data la sua difficile consultazione presso i Rosminiani), sono state prese in esame le edizioni del 1707 e quella del 1859 (che si basa su quella del 1707). Questo saggio esamina la lingua del Baldi, gli influssi dell’urbinate (Urbino è patria del Baldi) sulla stesura della Cronica, alcuni aspetti di retorica, e mette in luce alcune retrodatazioni di ambito scientifico legate all’argomento del trattato
Sobolev-Gaffney type inequalities for differential forms on sub-Riemannian contact manifolds with bounded geometry
Full text linkIn this paper we establish a Gaffney type inequality, in -Sobolev
spaces, for differential forms on sub-Riemannian contact manifolds without
boundary, having bounded geometry (hence, in particular, we have in mind
non-compact manifolds). Here and depending on the
order of the differential form we are considering. The proof relies on the
structure of the Rumin's complex of differential forms in contact manifolds, on
a Sobolev-Gaffney inequality proved by Baldi-Franchi in the setting of the
Heisenberg groups and on some geometric properties that can be proved for
sub-Riemannian contact manifolds with bounded geometry.Comment: 36 page
Cell-cycle molecules in mesothelioma
No full textThe cell cycle is the cascade of events that allows a growing cell to duplicate all its component and split into two daughter cells. Several studies report the importance of cell cycle proteins in the pathogenesis and the prognosis of mesothelioma. Cell cycle progression is mediated by the activation of a highly conserved family of protein kinases, the cyclin-dependent kinases (CDKs). CDKs are also regulated by related proteins called cdk inhibitors grouped into two families: the INK4 inhibitors (p16, p15, p19 and p18) and the Cip/Kip inhibitors (p21, p27 and p53). This article will review the most recent data from the literature about the expression and the diagnostic and prognostic significance of cell cycle molecules in mesothelioma
Gadda in Adelphi. Una conversazione
No full textIntervista a Paola Italia, Giorgio Pinotti e Claudio Vela sulle nuove edizioni Adelphi di Gadda. A cura di Valentino Baldi e Cristina Savettier
Extensions of Ehrenfest's urn designs for comparing two treatments
No full textIn this paper we discuss sequential urn designs for comparing two treatments. The Ehrenfest urn design suggested by Chen is shown to be a special case of the Adjustable Biased Coin Design proposed by Baldi Antognini and Giovagnoli. Some generalizations of Chen's design are proposed that converge to a general target proportion of allocations. A further extension is suggested, the Ehrenfest-Brillouin design, that converges to the target faster
A dose-finding sequential method for targeting a given mean response: Up&Down experiments
No full textTradizionalmente, gli studi dose-risposta sono esperimenti di tipo binario volti a stimare un determinato “quantile” di interesse di una curva di risposta. In questo lavoro si considera il caso in cui la risposta osservata sia una generica variabile aleatoria reale, non necessariamente dicotomica, e lo scopo dell’esperimento consiste nello stimare la dose target associata ad una preassegnata risposta media. Ripercorrendo i risultati di Giovagnoli e Pintacuda (1998) e Baldi Antognini et al (2006), viene proposta ed analizzata un’estensione randomizzata dell’algoritmo up-and-down, fornendo inoltre una
procedura di stima della risposta media basata sul metodo di massima verosimiglianza
Clarifying the effects of interacting dark energy on linear and non-linear structure formation processes
No full textWe present a
detailed numerical study of the impact that cosmological
models featuring a direct interaction between the dark energy component
that drives the accelerated expansion of the Universe and cold dark
matter can have on the linear and non-linear stages of structure
formation. By means of a series of collisionless N-body simulations, we
study the influence that each of the different effects characterizing
these cosmological models - which include among others a fifth force, a
time variation of particle masses and a velocity-dependent acceleration
- separately have on the growth of density perturbations and on a series
of observable quantities related to linear and non-linear cosmic
structures, as the matter power spectrum, the gravitational bias between
baryons and cold dark matter, the halo mass function and the halo
density profiles. We perform our analysis applying and comparing
different numerical approaches previously adopted in the literature, and
we address the partial discrepancies recently claimed in a similar study
by Li & Barrow with respect to the first outcomes of Baldi et al.,
which are found to be related to the specific numerical approach adopted
in the former work. Our results fully confirm the conclusions of Baldi
et al. and show that when linear and non-linear effects of the
interaction between dark energy and cold dark matter are properly
disentangled, the velocity-dependent acceleration is the leading effect
acting at non-linear scales and in particular is the most important
mechanism in lowering the concentration of cold dark matter haloes
On the speed of convergence of some urn designs for the balanced allocation of two treatments
No full textThe present paper deals with sequential urn designs for the balanced allocation of two treatments. Wei (1977, 1978b) was among the first authors to suggest an algorithm based on the probabilistic properties of the generalized Friedman urn and recently Chen (2000) has suggested the Ehrenfest design, namely a sequential procedure based on the Ehrenfest urn process. Some extensions of these algorithms are discussed: in particular we focus on a generalization of Chen's procedure, called the Ehrenfest-type urn designs, recently introduced by Baldi Antognini (2004). By analyzing some convergence properties of the Ehrenfest process, we show that for an Ehrenfest-type urn it is possible to evaluate the variance of the design at each step and analyze the
convergence to balance. Furthermore, the generalized Friedman urn and the Ehrenfest-type procedures are compared in terms of
speed of convergence. The Ehrenfest design proposed by Chen converges to balance faster than the other urn procedures
'Optimal' Randomized Designs for Sequential Experiments with Two Treatments
No full textThis paper starts with a discussion of the ``optimality'' of sequential
randomized designs for comparing two treatments and introduces the concept\
of ``desirable'' proportion of allocations to one of the treatments. The
problem is finding a randomized design which converges to the desirable one
almost certainly and also forces the procedure towards the desirable
proportion even for small samples. When balance is optimal we show that
Efron's Biased Coin Design (1971) and the class of Wei's designs (1978) are
asymptotically desirable and propose extensions of the above mentioned
algorithms that converge almost surely to any desired proportion, when the value is known. The Adjustable Biased Coin Design of Baldi Antognini and Giovagnoli (2003) also converges to balance and the convergence is faster
than the other procedures
Comparing three possible hypoelliptic Laplacians on the 5-dimensional Cartan group via div-curl type estimates
Full text linkOn general Carnot groups, the definition of a possible hypoelliptic Hodge-Laplacian on forms using
the Rumin complex has been considered in (M. Rumin, “Differential geometry on C-C spaces and application
to the Novikov-Shubin numbers of nilpotent Lie groups,” C. R. Acad. Sci., Paris Sér. I Math., vol. 329, no. 11, pp.
985–990, 1999, M. Rumin, “Sub-Riemannian limit of the differential form spectrum of contactmanifolds,” Geom.
Funct. Anal., vol. 10, no. 2, pp. 407–452, 2000), where the author introduced a 0-order pseudodifferential operator
on forms. However, for questions regarding regularity for example, where one needs sharp estimates, this
0-order operator is not suitable. Up to now, there have only been very few attempts to define hypoelliptic Hodge-
Laplacians on forms that would allow for such sharp estimates. Indeed, this question is rather difficult to address
in full generality, the main issue being that the Rumin exterior differential dc is not homogeneous on arbitrary
Carnot groups. In this note, we consider the specific example of the free Carnot group of step 3 with 2 generators,
and we introduce three possible definitions of hypoelliptic Hodge-Laplacians.We compare how these three possible
Laplacians can be used to obtain sharp div-curl type inequalities akin to those considered by Bourgain &
Brezis and Lanzani & Stein for the de Rham complex, or their subelliptic counterparts obtained by Baldi, Franchi
& Pansu for the Rumin complex on Heisenberg groups
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