DSpace Community:
http://hdl.handle.net/2117/127
20140418T13:32:13Z

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

An efficacious method to assemble a modern multimodal robotic team: dilemmas, challenges, possibilities and solutions
http://hdl.handle.net/2117/22603
Title: An efficacious method to assemble a modern multimodal robotic team: dilemmas, challenges, possibilities and solutions
Authors: Abdollahi Hosnijeh, Amir; Samani, Hooman Aghaebrahimi
Abstract: A modern multiagent robotic platform consists of a cooperative team of humans which develop a collaborative team of robots.
The multimodal nature of both the system and the team causes a complex problem which needs to be solved for optimum performance. Both the management and the technical aspect of a modern robotic team are explored in this
Chapter in the platform of the RoboCup Competition.
RoboCup is an example of such an environment where researchers from different disciplines join to develop a robotic team for completion as an evaluation challenge
(Robocup, 2011). RoboCup competitions were first proposed by Mackworth in 1993. The main goal of this scientific competition
is to exploit, improve and integrate the methods and techniques from robotics, machine vision and artificial intelligence disciplines to create an autonomous team of soccer playing robots(Kitano, 1997a; Kitano, 1997b; Kitano et al., 1997). Such experiment
includes several challenges, from inviting an expert of specific field to the team to choosing bolts and nuts for each part of the robots. Usually each challenge has several possible solutions and choosing the best one is often challenging.
We have participated in several world wide RoboCup competitions (Abdollahi, Samani et
al. 2002, 2003 & 2004) and share our
experience as an extensive instruction for setting up a modern robotic team including management and technical issues.
20140410T12:04:15Z

Some theoretical thoughts when using a composite endpoint to prove the efficacy of a treatment
http://hdl.handle.net/2117/22571
Title: Some theoretical thoughts when using a composite endpoint to prove the efficacy of a treatment
Authors: Gómez Melis, Guadalupe
Abstract: This paper discusses, following G_omez and Lagakos (2011) methodology, to what extent is there a gain in e_ciency from adding a component event to a relevant endpoint when the treatment e_ect on this component is not as strong as on the original relevant endpoint under ideal (independence) circumstances. It presents the bivariate copula model used to overcome the independence assumption and presents the relationship between the components of the asymptotic relative e_ciency and a set of interpretable parameters.
20140408T16:25:26Z

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

Review of multivariate survival data
http://hdl.handle.net/2117/22543
Title: Review of multivariate survival data
Authors: Gómez Melis, Guadalupe; Calle Rosingana, M. Luz; Serrat Piè, Carles; Espinal Berenguer, Anna
Abstract: This paper reviews some of the main contributions in the area of multivariate survival data and proposes some possible extensions. In particular, we have concentrated our search and study on those papers that are relevant to the situation where two (or more) consecutive variables are followed until a common day of analysis and subject to informative censoring.
The paper reviews bivariate nonparametric approaches and extend some of them to the case of two nonconsecutive times. We introduce the notation and construct the likelihood for the general problem of more than two consecutive survival times. We formulate the time dependencies and trends via a Bayesian approach. Finally, three regression models for multivariate survival times are discussed together with the differences among them which will be useful when the main interest is on the effect of covariates on the risk of failure.
Description: Document de recerca publicat per la UPC. Departament d'Estadística i Investigació operativa
20140407T14:05:21Z

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

Geometric HamiltonJacobi theory for higherorder autonomous systems
http://hdl.handle.net/2117/22509
Title: Geometric HamiltonJacobi theory for higherorder autonomous systems
Authors: Colombo, Leonardo; de León, Manuel; Prieto Martínez, Pedro Daniel; Román Roy, Narciso
Abstract: The geometric framework for the HamiltonJacobi theory is used to study this theory in the ambient of higherorder mechanical systems, both in the Lagrangian and Hamiltonian formalisms. Thus, we state the corresponding HamiltonJacobi equations in these formalisms and apply our results to analyze some particular physical examples.
20140403T17:26:58Z

Singularities of nonredundant manipulators: a short account and a method for their computation in the planar case
http://hdl.handle.net/2117/22508
Title: Singularities of nonredundant manipulators: a short account and a method for their computation in the planar case
Authors: Bohigas Nadal, Oriol; Manubens Ferriol, Montserrat; Ros Giralt, Lluís
Abstract: The study of the singularity set is of utmost utility in understanding the local and global behavior of a manipulator. After reviewing the mathematical conditions that characterize this set, and their kinematic and geometric interpretation, this paper shows how these conditions can be formulated in an amenable manner in planar manipulators, allowing the definition of a conceptuallysimple method for isolating the set exhaustively, even in higherdimensional cases. As a result, the method delivers a collection of boxes bounding the location of all points of the set, whose accuracy can be adjusted through a threshold parameter. Such boxes can then be projected to the input or output coordinate spaces, obtaining informative diagrams, or portraits, on the global motion capabilities of the manipulator. Examples are included that show the application of the method to simple manipulators, and to a complex mechanism that would be difficult to analyze using commonpractice procedures.
20140403T17:06:36Z

Joint modelling analysis of prostate cancer incidence: frequentist and bayesian approaches
http://hdl.handle.net/2117/22507
Title: Joint modelling analysis of prostate cancer incidence: frequentist and bayesian approaches
Authors: Piulachs, Xavier; Serrat Piè, Carles; Rué, Montserrat; Armero, Carmen; Forte, Anabel; Perpiñán, Héctor; Luján, Marcos; Páez, Álvaro
Abstract: Prostate specific antigen (PSA) is a biomarker for prostate cancer (PCa) that is widely used for PCa screening. Using a database of 2415 men included in the Spanish screening arm of the ERSPC Study, we will use joint modelling strategies to analyze if longitudinal PSA profiles and time to PCa incidence allow to obtain a better estimate of the individual risk of PCa. Conclusions and limitations of the study will be discussed.
20140403T15:38:32Z

Estimation of survival functions subject to order restrictions
http://hdl.handle.net/2117/22506
Title: Estimation of survival functions subject to order restrictions
Authors: Serrat Piè, Carles; Moreno, Laura
Abstract: This contribution is framed in, and is part of, the Durabiltiy of Building Facades studies carried out in the last decade in the Institut d’Estadística i Matemàtica Aplicada a l’Edificació and Laboratori d’ Edificació at the Universitat Politècnica de Catalunya. The goal of this presentation is to incorporate in the analysis of the estimation of the durability of building facades respect the severity degrees (low, medium or high) the order of the events of interest. In other words, we will take into account preliminary estimates of the survival probabilities of previous events (e.g. initial severities) as order constraints for the estimation of survival probabilities for subsequent events of interest (e.g. more advanced severities).
Standard statistical analyses for this type of interval censored data are usually conducted by using the R statistical software, however it does not include libraries or packages neither for simultaneous estimation nor for the use of order constraints. For this reason, we will use AMPL and the solver SNOPT to implement the Turnbull's estimator with order restrictions, for the estimation of the survival function of each event of interest taking into account the information given by the survival function of some previous event of interest. The proposed methodology solves the inconsistency problem associated with a separate estimation of the respective survival probabilities. As a illustration the methodology will be applied to a simulated dataset. As a theoretical contribution, a conjecture on Turnbull's estimator Theorem under order restrictions will be proposed.
20140403T15:05:09Z

Longitudinal + reliability = joint modeling
http://hdl.handle.net/2117/22505
Title: Longitudinal + reliability = joint modeling
Authors: Serrat Piè, Carles
Abstract: The aim of this presentation is to introduce joint modelling techniques for the simultaneous analysis of longitudinal timevarying data and timetoevent data. This is an increasing area of interest for the analysis of complex systems. Among others, three main advantages of this approach are: a) it corrects the bias derived from a traditional separate analysis, b) the modelization allows to incorporate and model the between and within correlation among observations and, c) true longitudinal profiles for endogenous covariates can be included in the relative hazard survival submodel.
The relevant benefit of these models is being able to estimate the effect of each subjectspecific longitudinal profile in the hazard function for the event of interest, in an adaptive manner. In particular, subjectspecific dynamic predictions, like conditional survival functions given the available longitudinal information, can be derived. In order to implement joint models, existing open source libraries in R will be introduced and some illustrations will be given.
20140403T14:50:15Z

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