DSpace Collection:
http://hdl.handle.net/2117/3918
20140419T00:19:31Z

J2 effect and elliptic inclined periodic orbits in the collision threebody problem
http://hdl.handle.net/2117/21117
Title: J2 effect and elliptic inclined periodic orbits in the collision threebody problem
Authors: Barrabes, Esther; Cors Iglesias, Josep Maria; Pinyol, Conxita; Soler Villanueva, Jaume
Abstract: The existence of a new class of inclined periodic orbits of the collision restricted
three{body problem is shown. The symmetric periodic solutions found are perturbations of elliptic
kepler orbits and they exist only for special values of the inclination and are related to the motion
of a satellite around an oblate planet.

Automatic classification of atypical lymphoid B cells using digital blood image processing
http://hdl.handle.net/2117/22609
Title: Automatic classification of atypical lymphoid B cells using digital blood image processing
Authors: Alférez Baquero, Edwin Santiago; Merino, Ana; Mujica Delgado, Luis Eduardo; Ruiz Ordóñez, Magda; Bigorra, Laura; Rodellar Benedé, José
Abstract: Introduction: There are automated systems for digital peripheral blood (PB) cell analysis, but they operate most effectively in nonpathological blood samples. The objective of this work was to design a methodology to improve the automatic classification of abnormal lymphoid cells.
Methods: We analyzed 340 digital images of individual lymphoid cells from PB films obtained in the CellaVision DM96:150 chronic
lymphocytic leukemia (CLL) cells, 100 hairy cell leukemia (HCL) cells, and 90 normal lymphocytes (N). We implemented the
Watershed Transformation to segment the nucleus, the cytoplasm, and the peripheral cell region. We extracted 44 features and then the clustering Fuzzy CMeans (FCM) was applied in two steps for the lymphocyte classification.
Results: The images were automatically clustered in three groups, one of them with 98% of the HCL cells. The set of the remaining cells was clustered again using FCM and texture features. The two new groups contained 83.3% of the N cells and 71.3% of the CLL cells, respectively.
Conclusion: The approach has been able to automatically classify with high precision three types of lymphoid cells. The addition of more descriptors and other classification techniques will allow extending the classification to other classes of atypical lymphoid cells.
20140410T13:39:48Z

On lefttruncating and mixing poisson distributions
http://hdl.handle.net/2117/22548
Title: On lefttruncating and mixing poisson distributions
Authors: Valero Baya, Jordi; Pérez Casany, Marta; Ginebra Molins, Josep
Abstract: The distributions obtained by lefttruncating at k a mixed Poisson distribution, kTMP, and those obtained by mixing previously lefttruncated Poisson distributions, MkTP, are characterized by means of their probability generating function. The main consequence is that every kTMP distribution is a MkTP distribution, but not the other way around.
20140407T17:26:00Z

Higherorder mechanics: variational principles and other topics
http://hdl.handle.net/2117/22510
Title: Higherorder mechanics: variational principles and other topics
Authors: Prieto Martínez, Pedro Daniel; Román Roy, Narciso
Abstract: After reviewing the LagrangianHamiltonian unified formalism (i.e, the SkinnerRusk formalism) for higherorder (nonautonomous) dynamical systems, we state a unified geometrical version of the Variational Principles which allows us to derive the Lagrangian and Hamiltonian equations for these kinds of systems. Then, the standard Lagrangian and Hamiltonian formulations of these principles and the corresponding dynamical equations are recovered from this unified framework.. © American Institute of Mathematical Sciences.
20140403T17:35:10Z

Centers of quasihomogeneous polynomial differential equations of degree three
http://hdl.handle.net/2117/22462
Title: Centers of quasihomogeneous polynomial differential equations of degree three
Authors: Aziz, Waleed; Llibre Saló, Jaume; Pantazi, Chara
Abstract: We characterize the centers of the quasihomogeneous planar polynomial differential systems of degree three. Such systems do not admit isochronous centers. At most one limit cycle can bifurcate from the periodic orbits of a center of a cubic homogeneous polynomial system using the averaging theory of first order
20140331T16:38:52Z

A description of autofixed subgroups in a free group
http://hdl.handle.net/2117/22454
Title: A description of autofixed subgroups in a free group
Authors: Martino, Armando; Ventura Capell, Enric
Abstract: Let F be a finitely generated free group. By using BestvinaHandel theory, as well
as some further improvements, the eigengroups of a given automorphism of F (and
its fixed subgroup among them) are globally analyzed and described. In particular,
an explicit description of all subgroups of F which occur as the fixed subgroup of
some automorphism is given.
20140331T14:23:38Z

Corrigendum to "Algebraic characterizations of regularity properties in bipartite graphs" Eur. J. Combin. 34 (2013) 12231231
http://hdl.handle.net/2117/22446
Title: Corrigendum to "Algebraic characterizations of regularity properties in bipartite graphs" Eur. J. Combin. 34 (2013) 12231231
Authors: Abiad, Aida; Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel
Description: Corrigendum d'un article anteriorment publicat
20140331T10:03:52Z

Water, sanitation, hygiene and rural poverty: Issues of sector monitoring and the role of aggregated indicators
http://hdl.handle.net/2117/22423
Title: Water, sanitation, hygiene and rural poverty: Issues of sector monitoring and the role of aggregated indicators
Authors: Giné Garriga, Ricard; Pérez Foguet, Agustí
Abstract: Water and sanitation improvements together with hygiene (WASH) are central to health. However, progress in ensuring access to these basic services remains inadequate, particularly in the rural developingworld. To remedy this appalling situation, decisionmakers need reliable data on which to base planning, targeting and prioritization. However, the challenges of collecting such data and producing consistent evidence are diverse. To influence policy, data have to be easily and meaningfully interpreted. In addition, the evaluation framework needs to capture the complexity inherent in the delivery of rural services. And with limited resources, the neediest must be prioritized. In this paper we compare three different monitoring and evaluation approaches: health impact indicators, standard indicators of the World Health Organization (WHO)/United Nations Children's Fund (UNICEF) Joint Monitoring Programme (JMP), and one multidimensional, WASHfocused indicator. From a policymaking perspective, the likely utility of the outcomes produced by each approach is discussed. The epidemiological study producesmisleading results,which do not help draw relevant conclusions. JMPindicators provide reasonable quality basic estimates of coverage across different contexts, but are inappropriate to build up a complete picture of such context. The index approach takes into account a broader view of service level, and proves useful as a policy tool to guide action towards improved service delivery
20140328T10:52:16Z

Mathematical Methods Applied to the Celestial Mechanics of Artificial Satellites 2013
http://hdl.handle.net/2117/22393
Title: Mathematical Methods Applied to the Celestial Mechanics of Artificial Satellites 2013
Authors: Prado, Antonio F. Bertachini A.; Masdemont Soler, Josep; Zanardi, Maria Cecilia; Winter, Silvia Maria Giuliatti; Yokoyama, Tadashi; Gomes, Vivian Martins
20140326T15:17:42Z

Computation of limit cycles and their isochrons: Fast algorithms and their convergence
http://hdl.handle.net/2117/22392
Title: Computation of limit cycles and their isochrons: Fast algorithms and their convergence
Authors: Huguet Casades, Gemma; de la Llave Canosa, Rafael
Abstract: We present efficient algorithms to compute limit cycles and their isochrons (i.e., the sets of points with the same asymptotic phase) for planar vector fields. We formulate a functional equation for the parameterization of the invariant cycle and its isochrons, and we show that it can be solved by means of a Newton method. Using the right transformations, we can solve the equation of the Newton step efficiently. The algorithms are efficient in the sense that if we discretize the functions using N points, a Newton step requires O(N) storage and O(N log N) operations in Fourier discretization or O(N) operations in other discretizations. We prove convergence of the algorithms and present a validation theorem in an a posteriori format. That is, we show that if there is an approximate solution of the invariance equation that satisfies some some mild nondegeneracy conditions, then there is a true solution nearby. Thus, our main theorem can be used to validate numerically computed solutions. The theorem also shows that the isochrons are analytic and depend analytically on the base point. Moreover, it establishes smooth dependence of the solutions on parameters and provides efficient algorithms to compute perturbative expansions with respect to external parameters. We include a discussion on the numerical implementation of the algorithms as well as numerical results for representative examples.
20140326T15:06:49Z

Nonlinear equations for fractional Laplacians, I: Regularity, maximum principles, and Hamiltonian estimates
http://hdl.handle.net/2117/22391
Title: Nonlinear equations for fractional Laplacians, I: Regularity, maximum principles, and Hamiltonian estimates
Authors: Cabré Vilagut, Xavier; Sire, Yannick
Abstract: This is the first of two articles dealing with the equation ()sv = f (v) in Rn, with s ¿ (0,1), where ()s stands for the fractional Laplacian — the in¿nitesimal generator of a Lévy process. This equation can be realized as a local linear degenerate elliptic equation in Rn+1+ together with a nonlinear Neumann boundary condition on ¿Rn+1 + =Rn.
In this ¿rst article, we establish necessary conditions on the nonlinearity f to admit certain type of solutions, with special interest in bounded increasing solutions in all of R. These necessary conditions (which will be proven in a followup paper to be also suficient for the existence of a bounded increasing solution) are derived from an equality and an estimate involving a Hamiltonian — in the spirit of a result of Modica for the Laplacian. Our proofs are uniform ass ¿1, establishing in the limit the corresponding known results for the Laplacian.
In addition, we study regularity issues, as well as maximum and Harnack principles associated to the equation.

A Perturbation argument for a Monge–Ampère type equation arising in optimal transportation
http://hdl.handle.net/2117/22385
Title: A Perturbation argument for a Monge–Ampère type equation arising in optimal transportation
Authors: Caffarelli, Luis; González Nogueras, María del Mar; Nguyen, Truyen
Abstract: We prove some interior regularity results for potential functions of optimal transportation problems with power costs. The main point is that our problem is equivalent to a new optimal transportation problem whose cost function is a sufficiently small perturbation of the quadratic cost, but it does not satisfy the well known condition (A.3) guaranteeing regularity. The proof consists in a perturbation argument from the standard Monge–Ampère equation in order to obtain, first, interior C1,1 estimates for the potential and, second, interior Hölder estimates for
second derivatives. In particular, we take a close look at the geometry of optimal
transportation when the cost function is close to quadratic in order to understand
how the equation degenerates near the boundary.
20140326T07:03:34Z

Basin of attraction of triangular maps with applications
http://hdl.handle.net/2117/22371
Title: Basin of attraction of triangular maps with applications
Authors: Cima Mollet, Anna; Gasull Embid, Armengol; Mañosa Fernández, Víctor
Abstract: We consider planar triangular maps that preserve certain fibration of the plane. We assume that there exists an invariant attracting fiber and we study the limit dynamics of those points in the basin of attraction of this invariant fiber, assuming that either it contains a global attractor, or it is filled by fixed or 2periodic points. We apply our results to several examples.
20140325T10:55:11Z

Algebraic Characterizations of Regularity Properties in Bipartite Graphs
http://hdl.handle.net/2117/22312
Title: Algebraic Characterizations of Regularity Properties in Bipartite Graphs
Authors: Abiad Monge, Aida; Dalfó Simó, Cristina; Fiol Mora, Miquel Àngel
Abstract: Regular and distanceregular characterizations of general graphs are wellknown. In particular, the spectral excess theorem states that a connected graph GG is distanceregular if and only if its spectral excess (a number that can be computed from the spectrum) equals the average excess (the mean of the numbers of vertices at extremal distance from every vertex). The aim of this paper is to derive new characterizations of regularity and distanceregularity for the more restricted family of bipartite graphs. In this case, some characterizations of (bi)regular bipartite graphs are given in terms of the mean degrees in every partite set and the Hoffman polynomial. Moreover, it is shown that the conditions for having distanceregularity in such graphs can be relaxed when compared with general graphs. Finally, a new version of the spectral excess theorem for bipartite graphs is presented.
20140320T12:40:12Z

Edgedistanceregular graphs are distanceregular
http://hdl.handle.net/2117/22307
Title: Edgedistanceregular graphs are distanceregular
Authors: Cámara Vallejo, Marc; Dalfó Simó, Cristina; Delorme, Charles; Fiol Mora, Miquel Àngel; Suzuki, Hiroshi
Abstract: A graph is edgedistanceregular when it is distanceregular around each of its edges and it has the same intersection numbers for any edge taken as a root. In this paper we give some (combinatorial and algebraic) proofs of the fact that every edgedistanceregular graph Γ is distanceregular and homogeneous. More precisely, Γ is edgedistanceregular if and only if it is bipartite distanceregular or a generalized odd graph. Also, we obtain the relationships between some of their corresponding parameters, mainly, the distance polynomials and the intersection numbers.
20140320T10:40:00Z