83 research outputs found
The Torelli theorem for ALH∗ gravitational instantons
No full textWe give a short proof of the Torelli theorem for ALH∗ gravitational instantons, using the authors' previous construction of mirror special Lagrangian fibrations in del Pezzo surfaces and rational elliptic surfaces together with recent work of Sun-Zhang. In particular, this includes an identification of 10 diffeomorphism types of ALH∗b gravitational instantons.First author draf
Giovanni da Roma e una fortunata Madonna del Latte. Indagine su una scultura in terracotta a stampo nella Lombardia del Quattrocento
No full textGiovanni da Roma was a 15th century terracotta sculptor, active between Parma and Cremona, known through a small number of documents and no certain works. The author traces an updated portrait of the coroplast, both with the contribution of unpublished information and by re-reading the data already emerged from the archive research, in the light of the early studies (19th century), passing through the subsequent investigations by Puerari and Mendogni, and finally the more recent ones by Aldo Galli and Marco Tanzi. It is also proposed the attribution to Giovanni da Roma of a Saint Benedict of Nursia, which remained unknown until very recent times and preserved in Parma. The second part of the contribution focuses on a large series of 15th century tiles replicated in a cast depicting the Nursing Madonna: today there are 17 examples, scattered throughout Italy, Germany, France, Russia and Hungary. The author also tries to identify the prototype of the series in an example of the successful composition, known only in photography. Finally, the hypothesis is advanced that also the original composition of the Nursing Madonna is attributable to Giovanni da Roma
Stability of numerical methods for delay differential equations
No full textAbstractConsider the following delay differential equation (DDE) y′=ƒ(t,y(t),y(t−τ(t))), t⩾t0,with the initial condition y(t)=Φ for t⩽t0,where ƒ and Φ are such that (0.1), (0.2) has a unique solution y(t). The author gives sufficient conditions for the asymptotic stability of the equation (0.1) for which he introduces new definitions of numerical stability. The approach is reminiscent of that from the nonlinear, stiff ordinary differential equation (ODE) field. He investigates stability properties of the class of one-point collocation rules. In particular, the backward Euler method turns out to be stable with respect to all the given definitions
Le ultime frontiere del recupero e della valorizzazione del patrimonio urbano: gli usi temporanei
No full textNowadays, the city is a laboratory of architectural, social, economic and urban transformation processes, based on a dynamic society, whose effectiveness de- pends on the definition of an adequate legal framework. Such legal framework is aimed at directing the urban planning function towards the environmental and territorial sustainability.
Among the processes that make the city more liveable, the paper analyses the most recent regulation for the recycling and valorisation of the unused urban heritage, in order to identify a change of use. Particularly, the research is focus on a specific rule that has been adopted by some regional laws and, more recently, by the National Parliament: the temporary use of unused buildings.
In addition to some considerations on the applicative potential and executive limits of the temporary use, the Author explains the reasons why it is necessary to legislatively define how much time the temporary use should last, considering also that the current legislation does not always regulate this aspect
On the rank of the flat unitary summand of the Hodge bundle
No full textLet be a non-isotrivial fibred surface. We prove that the
genus , the rank of the unitary summand of the Hodge bundle
and the Clifford index satisfy the inequality . Moreover, we prove that if the general fibre is a plane curve of degree
then the stronger bound holds. In particular,
this provides a strengthening of the bounds of \cite{BGN} and of \cite{FNP}.
The strongholds of our arguments are the deformation techniques developed by
the first author in \cite{Rigid} and by the third author and Pirola in
\cite{PT}, which display here naturally their power and depht.Comment: 19 pages, revised versio
Feasibility of a directional solar neutrino measurement with the CYGNO/INITIUM experiment
No full textOver the past five decades, solar neutrino research has been pivotal in driving significant scientific advancements, enriching our comprehension of both neutrino characteristics and solar processes. Despite numerous experiments dedicated to solar neutrino detection, a segment of the lower pp spectrum remains unexplored, while the precision of measurements from the CNO cycle remains insufficient to resolve the solar abundance problem determined by the discrepancy between the data gathered from helioseismology and the forecasts generated by stellar interior models for the Sun. The CYGNO/INITIUM experiment aims to deploy a large 30 m3 directional detector for rare event searches focusing on Dark Matter. Recently, in the CYGNUS collaboration, there has been consideration for employing these time projection chamber technology in solar neutrino directional detection trough neutrino-electron elastic scattering. This is due to their potential to conduct low-threshold, high-precision measurements with spectroscopic neutrino energy reconstruction on an event-by-event basis driven by the kinematic. However, so far, no experiments have been investigated on the feasibility of this measurement using actual detector performances and background levels. Such a detector already with a volume of O(10) m3 could perform an observation of solar neutrino from the pp chain with an unprecedented low threshold, while with larger volumes it could measure the CNO cycle eventually solving the solar metallicity problem
Human Cytomegalovirus, Human Herpesvirus 8 and Other Herpesviruses (Part III, Section 2, Chapter 75)
No full textWritten by a young, innovative author group, this exciting new book gives you the clinically relevant aspects of hematology in an innovative, unique format. The book is structured to comprehensively cover the complete scope of hematology, but allows fast access to key information you need in everyday practice. A section on consultative hematology includes chapters on special populations (pregnancy, pediatrics, geriatrics), infections of marrow and blood, and hematologic problems of medical practice and surgery. You'll also find a section on tools for the hematologist, covering clinical aspects of transfusion, transplantation, and the latest innovative laboratory procedures
Numerical reconstruction of curves from their Jacobians
No full textConference Name:18th International Conference on Arithmetic, Geometry, Cryptography, and Coding Theory, AGC2T 2021Date of Conference: May 31– June 4, 2021We approach the Torelli problem of recostructing a curve from its Jacobian from a
computational point of view. Following Dubrovin, we design a machinery to solve this
problem effectively, which builds on methods in numerical algebraic geometry. We
verify this methods via numerical experiments with curves up to genus 7
Role of Metal Dopants in Hydrogen Dissociation on Cu:CeO2 and Fe:CeO2 Surfaces Studied by Ambient-Pressure X-ray Absorption Spectroscopy
No full textThe doping of metal oxides is an interesting route to increase catalyst activity and lower activation temperatures in H-2 dissociation to replace Pt in catalysts for electrochemical devices. In this process, the roles of both the matrix and dopant cations are fundamental to understanding and designing more efficient catalysts. In this work, we have investigated the reduction process in pure and doped CeO2 films. We followed the oxidation states of Ce and dopants (Cu and Fe) during H-2 exposure at ambient pressure by combining X-ray absorption spectroscopy and gas chromatography on 5 nm films in the temperature range of 300-620 K. We have observed that Cu doping (at concentrations of 5 and 14 at. %) promotes the ceria reduction, while the addition of Fe seems to have a limited impact on the oxide chemical reactivity only at low temperatures. Moreover, thanks to the chemical sensitivity of operando X-ray absorption spectroscopy, we were able to follow simultaneously the evolution of Ce and Cu oxidation states during the reaction, which has permitted to identify two distinct reduction processes taking place above and below 500 K. These measurements show that at low temperatures, the H-2 dissociation takes place at the Cu1+ sites, thus explaining the higher reactivity of the Cu-doped samples. The described mechanism can help in the design of Pt-free catalysts with enhanced performances
A motivic global Torelli theorem for isogenous K3 surfaces
No full textFu L, Vial C. A motivic global Torelli theorem for isogenous K3 surfaces. Advances in Mathematics. 2021;383: 107674.We prove that the Chow motives of twisted derived equivalent K3 surfaces are isomorphic, not only as Chow motives (due to Huybrechts), but also as Frobenius algebra objects. Combined with a recent result of Huybrechts, we conclude that two complex projective K3 surfaces are isogenous (i.e. their second rational cohomology groups are Hodge isometric) if and only if their Chow motives are isomorphic as Frobenius algebra objects; this can be regarded as a motivic Torellitype theorem. We ask whether, more generally, twisted derived equivalent hyper-K & auml;hler varieties have isomorphic Chow motives as (Frobenius) algebra objects and in particular isomorphic graded rational cohomology algebras. In the appendix, we justify introducing the notion of & ldquo;Frobenius algebra object & rdquo; by showing the existence of an infinite family of K3 surfaces whose Chow motives are pairwise non isomorphic as Frobenius algebra objects but isomorphic as algebra objects. In particular, K3 surfaces in that family are pairwise non-isogenous but have isomorphic rational Hodge algebras. (c) 2021 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
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