Battaglino D.,University of Siena |
Fedou J.M.,UNS |
Rinaldi S.,University of Siena |
Socci S.,University of Siena
Discrete Mathematics and Theoretical Computer Science | Year: 2013
A convex polyomino is k-convex if every pair of its cells can be connected by means of a monotone path, internal to the polyomino, and having at most k changes of direction. The number k-convex polyominoes of given semi-perimeter has been determined only for small values of k, precisely k = 1; 2. In this paper we consider the problem of enumerating a subclass of k-convex polyominoes, precisely the k-convex parallelogram polyominoes (briefly, k-parallelogram polyominoes). For each k ≥ 1, we give a recursive decomposition for the class of k- parallelogram polyominoes, and then use it to obtain the generating function of the class, which turns out to be a rational function. We are then able to express such a generating function in terms of the Fibonacci polynomials. © 2013 Discrete Mathematics and Theoretical Computer Science (DMTCS).
Theoretical Computer Science | Year: 2013
In this paper, we consider the class of 4-stack polyominoes, i.e. polyominoes which can be decomposed into a central rectangle supporting four stack polyominoes, one on each side of the rectangle. This class of objects-recently introduced by Marc Noy-extends the class of centered convex polyominoes, and is included into the class of Z-convex polyominoes. Using an inclusion/exclusion approach, we obtain the enumeration of 4-stack polyominoes according to the number of rows and columns. Moreover, we solve some problems posed by Marc Noy, proving that the generating function of 4-stack polyominoes according to the semi-perimeter is algebraic, and that their asymptotic behavior is n4n, which is immediately smaller than the asymptotic behavior of Z-convex polyominoes, which is n4n. As a corollary of our result, we find the generating function of bi-centered polyominoes, i.e. convex polyominoes which are both horizontally and vertically centered. © 2011 Elsevier B.V. All rights reserved.
Battaglino D.,University of Siena |
Fedou J.M.,UNS |
Frosini A.,University of Florence |
Rinaldi S.,University of Siena
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2011
In  the authors proposed a classification of convex polyominoes based on the number of changes of direction in the paths connecting any two cells of a polyomino. More precisely, a convex polyomino is k-convex if every pair of its cells can be connected by a monotone path with at most k changes of direction. In 1-convex (also called L-convex) polyominoes, any two cells can be connected by a path with at most one change of direction. © 2011 Springer-Verlag.
Diaz S.L.,CONICET |
Paoloni J.D.,CONICET |
Nicolli H.B.,CONICET |
Nicolli H.B.,Institute Geoguimica |
And 6 more authors.
One Century of the Discovery of Arsenicosis in Latin America (1914-2014): As 2014 - Proceedings of the 5th International Congress on Arsenic in the Environment | Year: 2014
In the Southern Pampa, excess levels of As are due to its geoavailability within loess sediments-soils sequences hosting the phreatic aquifers. We analyzed total contents of As and associated trace elements in the loess solid phase, including spatial distribution of As, F, B and V in hydric resources. The interrelationships between solid and aqueous As contents were studied in El Divisorio Creek Basin applying statistics (Principal Components Analysis, PCA). Total As in soils ranges 5.1-20.7 mg kg-1, being lower in the valley slopes and appeared irregularly distributed in the alluvial plain. Alluvial activity determines intrabasin distribution of As-bearing minerals as reflected in As contents in the solid phase. Variability of As in waters is explained by the local factors controlling water residence time in the aquifers, by processes of silicate hydrolysis, oxidation-reduction, sorption-desorption and formation of complex ions in the fine fraction (<2 μm). © 2014 Taylor & Francis Group.
Locati F.,CONICET |
Marfil S.,National University of San Juan |
Baldo E.,CONICET |
Cement and Concrete Research | Year: 2010
The potential release of elements from potassic and calcic-sodic feldspars into the concrete pore solution was evaluated by ICP-MS using 1 N NaOH and KOH solutions at 80 °C in accordance with the conditions set in the chemical test method. Materials were characterized by petrography, XRD and by XRF analysis. The influence of textural and microstructural characteristics on the leaching process was also analyzed by immersing polished plates of each mineral in 1 N NaOH at 80 °C for 7 days. Optical microscope and SEM observations indicate that microstructural characteristics, such as cleavage zones, twins, grain-grain contact and the finer and less abundant phases in perthites, play a key role in the leaching process under alkaline conditions. Na2O, K2O, SiO2 and Al2O3 are supplied by hydrolysis, although the participation of other processes cannot be ruled out. © 2010 Elsevier Ltd. All rights reserved.