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101.
102.
Gianluca DAddese Laura Sani Luca La Rocca Roberto Serra Marco Villani 《Entropy (Basel, Switzerland)》2021,23(4)
The identification of emergent structures in complex dynamical systems is a formidable challenge. We propose a computationally efficient methodology to address such a challenge, based on modeling the state of the system as a set of random variables. Specifically, we present a sieving algorithm to navigate the huge space of all subsets of variables and compare them in terms of a simple index that can be computed without resorting to simulations. We obtain such a simple index by studying the asymptotic distribution of an information-theoretic measure of coordination among variables, when there is no coordination at all, which allows us to fairly compare subsets of variables having different cardinalities. We show that increasing the number of observations allows the identification of larger and larger subsets. As an example of relevant application, we make use of a paradigmatic case regarding the identification of groups in autocatalytic sets of reactions, a chemical situation related to the origin of life problem. 相似文献
103.
A. Bellosi J. Vicens V. Medri S. Guicciardi 《Applied Physics A: Materials Science & Processing》2005,81(5):1045-1052
The paper reports on both the characteristics of ultrafine silicon nitride powder produced by plasma synthesis and the microstructure and properties of the relative sintered material. The powder, already containing yttria and alumina as sintering aids, has a bimodal particle size distribution and it is partly amorphous. The chemical composition and morphology of the particles are shown. Yttria and alumina were not found in separate particles but the elements constituting them (i.e., Y, Al, O) are either in solid solutions in the crystalline particles or dispersed within the amorphous portion of the powder. Dense materials were obtained by pressureless sintering at 1750 °C. Microstructure and composition of silicon nitride grains and of grain boundary phases are analyzed and discussed. When compared to a micro-sized Si3N4, nanoindentation tests clearly revealed the inverse Hall Petch relation. The nanosize Si3N4 shows a Young’s modulus which is almost independent on the peak load. PACS 81.05.J,M; 81.40; 81.05.Y; 81.05.J; 46.30.P 相似文献
104.
Gianluca Occhetta 《manuscripta mathematica》2005,117(1):43-49
We rule out a doubtful case in the classification of Fano manifolds of middle indexMathematics Subject Classification (2000): 14J40, 14J45 相似文献
105.
Andrea Cappelli Maurizio Anzini Salvatore Vomero Alessandro Donati Lucia Zetta Raniero Mendichi Mario Casolaro Pietro Lupetti Paolo Salvatici Gianluca Giorgi 《Journal of polymer science. Part A, Polymer chemistry》2005,43(15):3289-3304
The macromolecular and aggregate structures of poly[ethyl 1‐methylene‐3‐(4‐methylphenyl)‐1H‐indene‐2‐carboxylate] (poly‐ BF1 ; a new polymer based on a functionalized benzofulvene moiety showing interesting properties, i.e., thermoreversible polymerization/depolymerization behavior, high solubility in the most common organic solvents, and susceptibility to molecular manipulation) have been investigated with NMR spectroscopy, absorption and emission spectrophotometry, and transmission electron microscopy (TEM). Moreover, the polymerization mechanism has been studied to obtain further information on the polymer structure. The collected evidence is consistent in indicating for poly‐ BF1 a vinyl (1,2) polymer structure stabilized by means of aromatic stacking interactions. Furthermore, TEM studies performed on metal replicas have shown that the polymer is liable to give nanostructured aggregates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3289–3304, 2005 相似文献
106.
In the field of the Jacobian conjecture it is well-known after Dru?kowski that from a polynomial ‘cubic-homogeneous’ mapping we can build a higher-dimensional ‘cubic-linear’ mapping and the other way round, so that one of them is invertible if and only if the other one is. We make this point clearer through the concept of ‘pairing’ and apply it to the related conjugability problem: one of the two maps is conjugable if and only if the other one is; moreover, we find simple formulas expressing the inverse or the conjugations of one in terms of the inverse or conjugations of the other. Two nontrivial examples of conjugable cubic-linear mappings are provided as an application. 相似文献
107.
Gianluca Cassese 《Journal of Theoretical Probability》2008,21(3):586-603
The concept of finitely additive supermartingales, originally due to Bochner, is revived and developed. We exploit it to study
measure decompositions over filtered probability spaces and the properties of the associated Doléans-Dade measure. We obtain
versions of the Doob–Meyer decomposition and, as an application, we establish a version of the Bichteler and Dellacherie theorem
with no exogenous probability measure.
I am indebted to an anonymous referee for several helping suggestions. 相似文献
108.
The dye-sensitized photooxygenation of furanosyl furans easily affords C- or O-glycosides with cis-alpha,beta-unsaturated 1,4-dioxo aglycones. The reaction, performed on a ribofuranosyl furan, provides a useful new entry to a novel pyridazine C-nucleoside that can be achieved through a simple one-pot procedure. 相似文献
109.
Gianluca Nasini Lucio Merlini Giovanni Dario Andreetti Gabriele Bocelli Paolo Sgarabotto 《Tetrahedron》1982,38(18):2787-2796
The absolute configuration of the asymmetric carbons and the axial chirality of the natural mold metabolite cercosporin (from .) have been established on the basis of X-ray analysis and chemical reactions. The results confirm the inherent dissymmetry of the perylenequinone ring, the twisting of which gives rise to the diastereoisomer isocercosporin. The energy barrier for the conversion of cercosporin into isocercosporin has been evaluated. 相似文献
110.