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Search Results: 1 - 10 of 6694 matches for " Fernanda Cristofori "
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Generalized regular genus for manifolds with boundary
Paola Cristofori
Le Matematiche , 2003,
Abstract: We introduce a generalization of the regular genus, a combinatorial invariant of PL manifolds ([10]), which is proved to be strictly related, in dimension three, to generalized Heegaard splittings defined in [12].
Celiac Disease and Overweight in Children: An Update
Antonella Diamanti,Teresa Capriati,Maria Sole Basso,Fabio Panetta,Vincenzo Maria Di Ciommo Laurora,Francesca Bellucci,Fernanda Cristofori,Ruggiero Francavilla
Nutrients , 2014, DOI: 10.3390/nu6010207
Abstract: The clinical presentation of celiac disease in children is very variable and differs with age. The prevalence of atypical presentations of celiac disease has increased over the past 2 decades. Several studies in adults and children with celiac disease indicate that obesity/overweight at disease onset is not unusual. In addition, there is a trend towards the development of overweight/obesity in celiac patients who strictly comply with a gluten-free diet. However, the pathogenesis and clinical implications of the coexistence of classic malabsorption (e.g., celiac disease) and overweight/obesity remain unclear. This review investigated the causes and main clinical factors associated with overweight/obesity at the diagnosis of celiac disease and clarified whether gluten withdrawal affects the current trends of the nutritional status of celiac disease patients.
Compact 3-manifolds via 4-colored graphs
Paola Cristofori,Michele Mulazzani
Mathematics , 2013, DOI: 10.1007/s13398-015-0240-8
Abstract: We introduce a representation of compact 3-manifolds without spherical boundary components via (regular) 4-colored graphs, which turns out to be very convenient for computer aided study and tabulation. Our construction is a direct generalization of the one given in the eighties by S. Lins for closed 3-manifolds, which is in turn dual to the earlier construction introduced by Pezzana's school in Modena. In this context we establish some results concerning fundamental groups, connected sums, moves between graphs representing the same manifold, Heegaard genus and complexity, as well as an enumeration and classification of compact 3-manifolds representable by graphs with few vertices ($\le 6$ in the non-orientable case and $\le 8$ in the orientable one).
Fecal Microbiota and Metabolome of Children with Autism and Pervasive Developmental Disorder Not Otherwise Specified
Maria De Angelis, Maria Piccolo, Lucia Vannini, Sonya Siragusa, Andrea De Giacomo, Diana Isabella Serrazzanetti, Fernanda Cristofori, Maria Elisabetta Guerzoni, Marco Gobbetti, Ruggiero Francavilla
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0076993
Abstract: This study aimed at investigating the fecal microbiota and metabolome of children with Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS) and autism (AD) in comparison to healthy children (HC). Bacterial tag-encoded FLX-titanium amplicon pyrosequencing (bTEFAP) of the 16S rDNA and 16S rRNA analyses were carried out to determine total bacteria (16S rDNA) and metabolically active bacteria (16S rRNA), respectively. The main bacterial phyla (Firmicutes, Bacteroidetes, Fusobacteria and Verrucomicrobia) significantly (P<0.05) changed among the three groups of children. As estimated by rarefaction, Chao and Shannon diversity index, the highest microbial diversity was found in AD children. Based on 16S-rRNA and culture-dependent data, Faecalibacterium and Ruminococcus were present at the highest level in fecal samples of PDD-NOS and HC children. Caloramator, Sarcina and Clostridium genera were the highest in AD children. Compared to HC, the composition of Lachnospiraceae family also differed in PDD-NOS and, especially, AD children. Except for Eubacterium siraeum, the lowest level of Eubacteriaceae was found on fecal samples of AD children. The level of Bacteroidetes genera and some Alistipes and Akkermansia species were almost the highest in PDD-NOS or AD children as well as almost all the identified Sutterellaceae and Enterobacteriaceae were the highest in AD. Compared to HC children, Bifidobacterium species decreased in AD. As shown by Canonical Discriminant Analysis of Principal Coordinates, the levels of free amino acids and volatile organic compounds of fecal samples were markedly affected in PDD-NOS and, especially, AD children. If the gut microbiota differences among AD and PDD-NOS and HC children are one of the concomitant causes or the consequence of autism, they may have implications regarding specific diagnostic test, and/or for treatment and prevention.
Computing Matveev's complexity via crystallization theory: the boundary case
Maria Rita Casali,Paola Cristofori
Mathematics , 2012, DOI: 10.1142/S0218216513500387
Abstract: The notion of Gem-Matveev complexity has been introduced within crystallization theory, as a combinatorial method to estimate Matveev's complexity of closed 3-manifolds; it yielded upper bounds for interesting classes of such manifolds. In this paper we extend the definition to the case of non-empty boundary and prove that for each compact irreducible and boundary-irreducible 3-manifold it coincides with the modified Heegaard complexity introduced by Cattabriga, Mulazzani and Vesnin. Moreover, via Gem-Matveev complexity, we obtain an estimation of Matveev's complexity for all Seifert 3-manifolds with base $\mathbb D^2$ and two exceptional fibers and, therefore, for all torus knot complements.
A note about complexity of lens spaces
Maria Rita Casali,Paola Cristofori
Mathematics , 2013, DOI: 10.1515/forum-2013-0185
Abstract: Within crystallization theory, (Matveev's) complexity of a 3-manifold can be estimated by means of the combinatorial notion of GM-complexity. In this paper, we prove that the GM-complexity of any lens space L(p,q), with p greater than 2, is bounded by S(p,q)-3, where S(p,q) denotes the sum of all partial quotients in the expansion of q/p as a regular continued fraction. The above upper bound had been already established with regard to complexity; its sharpness was conjectured by Matveev himself and has been recently proved for some infinite families of lens spaces by Jaco, Rubinstein and Tillmann. As a consequence, infinite classes of 3-manifolds turn out to exist, where complexity and GM-complexity coincide. Moreover, we present and briefly analyze results arising from crystallization catalogues up to order 32, which prompt us to conjecture, for any lens space L(p,q) with p greater than 2, the following relation: k(L(p,q)) = 5 + 2 c(L(p,q)), where c(M) denotes the complexity of a 3-manifold M and k(M)+1 is half the minimum order of a crystallization of M.
Cataloguing PL 4-manifolds by gem-complexity
M. R. Casali,P. Cristofori
Mathematics , 2014,
Abstract: We describe an algorithm to subdivide automatically a given set of PL n-manifolds (via coloured triangulations or, equivalently, via crystallizations) into classes whose elements are PL-homeomorphic. The algorithm, implemented in the case n=4, succeeds to solve completely the PL-homeomorphism problem among the catalogue of all closed connected PL 4-manifolds up to gem-complexity 8 (i.e., which admit a coloured triangulation with at most 18 4-simplices). Possible interactions with the (not completely known) relationship among different classification in TOP and DIFF=PL categories are also investigated. As a first consequence of the above PL classification, the non-existence of exotic PL 4-manifolds up to gem-complexity 8 is proved. Further applications of the tool are described, related to possible PL-recognition of different triangulations of the K3-surface.
Computing Matveev's complexity via crystallization theory: the orientable case
M. R. Casali,P. Cristofori
Mathematics , 2004,
Abstract: By means of a slight modification of the notion of GM-complexity, the present paper performs a graph-theoretical approach to the computation of (Matveev's) complexity for closed orientable 3-manifolds. In particular, the existing crystallization catalogue C^{28}, due to Lins, is used to obtain upper bounds for the complexity of closed orientable 3-manifolds triangulated by at most 28 tetrahedra. The experimental results actually coincide with the exact values of complexity, for all but three elements. Moreover, in the case of at most 26 tetrahedra, the exact value of the complexity is shown to be always directly computable via crystallization theory.
A catalogue of orientable 3-manifolds triangulated by 30 coloured tetrahedra
M. R. Casali,P. Cristofori
Mathematics , 2006,
Abstract: The present paper follows the computational approach to 3-manifold classification via edge-coloured graphs, already performed by several authors with respect to orientable 3-manifolds up to 28 coloured tetrahedra, non-orientable 3-manifolds up to 26 coloured tetrahedra, genus two 3-manifolds up to 34 coloured tetrahedra: in fact, by automatic generation and analysis of suitable edge-coloured graphs, called crystallizations, we obtain a catalogue of all orientable 3-manifolds admitting coloured triangulations with 30 tetrahedra. These manifolds are unambiguously identified via JSJ decompositions and fibering structures. It is worth noting that, in the present work, a suitable use of elementary combinatorial moves yields an automatic partition of the elements of the generated crystallization catalogue into equivalence classes, which are proved to be in one-to one correspondence with the homeomorphism classes of the represented manifolds.
Local order in aqueous solutions of rare gases and the role of the solute concentration: a computer simulation study with a polarizable potential
Paola Cristofori,Paola Gallo,Mauro Rovere
Physics , 2004, DOI: 10.1080/00268970512331316058
Abstract: Aqueous solutions of rare gases are studied by computer simulation employing a polarizable potential for both water and solutes. The use of a polarizable potential allows to study the systems from ambient to supercritical conditions for water. In particular the effects of increasing the concentration and the size of the apolar solutes are considered in an extended range of temperatures. By comparing the results at increasing temperature it appears clearly the change of behaviour from the tendency to demix at ambient conditions to a regime of complete solubility in the supercritical region. In this respect the role of the hydrogen bond network of water is evidenced.
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