DSpace Collection:
http://hdl.handle.net/2117/3919
2014-04-20T19:14:32ZReview 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 operativa2014-04-07T14:05:21ZGeometric Hamilton-Jacobi theory for higher-order autonomous systems
http://hdl.handle.net/2117/22509
Title: Geometric Hamilton-Jacobi theory for higher-order autonomous systems
Authors: Colombo, Leonardo; de León, Manuel; Prieto Martínez, Pedro Daniel; Román Roy, Narciso
Abstract: The geometric framework for the Hamilton-Jacobi theory is used to study this theory in the ambient of higher-order mechanical systems, both in the Lagrangian and Hamiltonian formalisms. Thus, we state the corresponding Hamilton-Jacobi equations in these formalisms and apply our results to analyze some particular physical examples.2014-04-03T17:26:58ZGeneralized Clifford-Severi inequality and the volume of irregular varieties
http://hdl.handle.net/2117/22384
Title: Generalized Clifford-Severi inequality and the volume of irregular varieties
Authors: Barja Yáñez, Miguel Ángel
Abstract: We give a sharp lower bound for the selfintersection of a nef li
ne bundle L on an irregular variety X in terms of its continuous global sections and the Albanese dim
ension of X, which we call the Generalized Clifford-Severi inequality. We also extend the result to nef
vector bundles and give a slope inequality for fibred irregular varieties. As a byproduct we obtain a lower b
ound for the volume of irregular varieties; when X is of maximal Albanese dimension the bound is vol(X)=2n!¿¿X
and it is sharp.
Description: Preprint. Acceptat per publicar a Duke Math. J.2014-03-25T20:15:26ZLocal description of phylogenetic group-based models
http://hdl.handle.net/2117/22383
Title: Local description of phylogenetic group-based models
Authors: Casanellas Rius, Marta; Fernández Sánchez, Jesús; Michalek, Mateusz
Abstract: Motivated by phylogenetics, our aim is to obtain a system of equations that
de ne a phylogenetic variety on an open set containing the biologically meaningful points. In
this paper we consider phylogenetic varieties de ned via group-based models. For any nite
abelian group G, we provide an explicit construction of codimX phylogenetic invariants
(polynomial equations) of degree at most jGj that de ne the variety X on a Zariski open set
U. The set U contains all biologically meaningful points when G is the group of the Kimura
3-parameter model. In particular, our main result con rms [Mic12, Conjecture 7.9] and, on
the set U, Conjectures 29 and 30 of [SS05].2014-03-25T19:26:25ZTesting of the three multiplicatively closed (Lie Markov) model heirarchies which respect purine/pyrimidine, Watson-Crick, and amino/keto nucleotide groupings
http://hdl.handle.net/2117/22382
Title: Testing of the three multiplicatively closed (Lie Markov) model heirarchies which respect purine/pyrimidine, Watson-Crick, and amino/keto nucleotide groupings
Authors: Woodhams, Michael D.; Fernández Sánchez, Jesús; Sumner, Jeremy
Abstract: We present three hierarchies of Lie Markov models of DNA sequence evolution. These models are
(locally) “multiplicatively closed,” meaning that the composition of two Markov matrices in the
model results, with some (rare) exceptions, in a third Markov matrix that is still in the model.
Additionally, the models in each hierarchy respectively distinguish between (i) purines and pyrimadines
(RY), (ii) Watson-Crick pairs (WS), and (iii) amino/keto pairs (MK), but otherwise treat
the four nucleotides without distinction. The multiplicative closure property allows mathematically
consistent modeling of time-inhomogeneous scenarios, unlike models that are not closed, such
as the general time-reversible model (GTR) and many of its submodels. We derive the nesting
relationships of the three model hierarchies and present software implementing the models. For a
diverse range of biological data sets, we perform Bayesian information criterion model comparision
analogous to that of the ModelTest framework. We find that our models outperform the GTR
model in some (but not all) cases.2014-03-25T17:59:41ZLie Markov models with purine/pyrimidine symmetry
http://hdl.handle.net/2117/22381
Title: Lie Markov models with purine/pyrimidine symmetry
Authors: Fernández Sánchez, Jesús; Sumner, Jeremy; Jarvis, Peter; Woodhams, Michael D.
Abstract: Continuous-time Markov chains are a standard tool in phylogenetic inference. If homogeneity is assumed, the chain is formulated by specifying time-independent rates of substitutions between states in the chain. In applications, there are usually extra constraints on the rates, depending on the situation. If a model is formulated in this way, it is possible to generalise it and allow for an inhomogeneous process, with time-dependent rates satisfying the same constraints. It is then useful to require that there exists a homogeneous average of this inhomogeneous process within the same model. This leads to the definition of "Lie Markov models", which are precisely the class of models where such an average exists. These models form Lie algebras and hence concepts from Lie group theory are central to their derivation. In this paper, we concentrate on applications to phylogenetics and nucleotide evolution, and derive the complete hierarchy of Lie Markov models that respect the grouping of nucleotides into purines and pyrimidines -- that is, models with purine/pyrimidine symmetry. We also discuss how to handle the subtleties of applying Lie group methods, most naturally defined over the complex field, to the stochastic case of a Markov process, where parameter values are restricted to be real and positive. In particular, we explore the geometric embedding of the cone of stochastic rate matrices within the ambient space of the associated complex Lie algebra.2014-03-25T17:13:58ZICASES scenarios Final Report
http://hdl.handle.net/2117/22332
Title: ICASES scenarios Final Report
Authors: Juan Zornoza, José Miguel; Sanz Subirana, Jaume2014-03-21T14:17:23ZUnified formalism for the generalized kth-order Hamilton-Jacobi problem
http://hdl.handle.net/2117/21964
Title: Unified formalism for the generalized kth-order Hamilton-Jacobi problem
Authors: Colombo, Leonardo; León, Manuel de; Prieto Martínez, Pedro Daniel; Román Roy, Narciso
Abstract: The geometric formulation of the Hamilton-Jacobi theory enables u
s to generalize it to
systems of higher-order ordinary differential equations. In this w
ork we introduce the unified
Lagrangian-Hamiltonian formalism for the geometric Hamilton-Jacob
i theory on higher-order
autonomous dynamical systems described by regular Lagrangian f
unctions.2014-03-10T13:07:34ZPeriodic orbits of planar integrable birational maps
http://hdl.handle.net/2117/21748
Title: Periodic orbits of planar integrable birational maps
Authors: Gálvez Carrillo, Maria Immaculada; Mañosa Fernández, Víctor
Abstract: A birational planar map F possessing a rational ﬁrst integral preserves a
foliation of the plane given by algebraic curves which, if F is not globally periodic,
is given by a foliation of curves that have generically genus 0 or 1. In the genus 1
case, the group structure of the foliation characterizes the dynamics of any birational
map preserving it. We will see how to take advantage of this structure to ﬁnd periodic
orbits of such maps.2014-02-25T12:09:41ZSymplectic topology of b-symplectic manifolds
http://hdl.handle.net/2117/21516
Title: Symplectic topology of b-symplectic manifolds
Authors: Miranda Galcerán, Eva; Martinez Torres, David; Frejlich, Pedro
Abstract: A Poisson manifold (M2n; ) is b-symplectic if
Vn is transverse
to the zero section. In this paper we apply techniques of Symplectic Topology
to address global questions pertaining to b-symplectic manifolds. The main
results provide constructions of: b-symplectic submanifolds a la Donaldson,
b-symplectic structures on open manifolds by Gromov's h-principle, and of
b-symplectic manifolds with a prescribed singular locus, by means of surgeries.2014-02-11T13:34:06ZAn extension problem for the CR fractional Laplacian
http://hdl.handle.net/2117/21457
Title: An extension problem for the CR fractional Laplacian
Authors: Frank, Rupert L.; González Nogueras, María del Mar; Monticelli, Dario D.; Tan, Jinggang
Abstract: We show that the conformally invariant fractional powers of the sub-Laplacian
on the Heisenberg group are given in terms of the scattering operator for an extension
problem to the Siegel upper halfspace. Remarkably, this extension problem is di erent
from the one studied, among others, by Ca arelli and Silvestre2014-02-05T10:52:39ZDescription of the experiment set-up in Vietnam
http://hdl.handle.net/2117/20959
Title: Description of the experiment set-up in Vietnam
Authors: Quang, Phuong Xuan; Vinh, La The; Juan Zornoza, José Miguel; Sanz Subirana, Jaume; García Rigo, Alberto; Hai Tung, Ta2013-12-10T15:34:07ZIONI-R and IONA-R scenarios report
http://hdl.handle.net/2117/20958
Title: IONI-R and IONA-R scenarios report
Authors: Juan Zornoza, José Miguel; Sanz Subirana, Jaume2013-12-10T15:13:10ZFinal report on EGNOS default ionospheric conditions. Volume 2: selection of ionospheric conditions: indicator thresholds
http://hdl.handle.net/2117/20957
Title: Final report on EGNOS default ionospheric conditions. Volume 2: selection of ionospheric conditions: indicator thresholds
Authors: Juan Zornoza, José Miguel; Sanz Subirana, Jaume2013-12-10T15:06:34ZFinal report on EGNOS default ionospheric conditions. Volume 1: Selection and justification of indicators and analysis against past EGNOS performance
http://hdl.handle.net/2117/20955
Title: Final report on EGNOS default ionospheric conditions. Volume 1: Selection and justification of indicators and analysis against past EGNOS performance
Authors: Juan Zornoza, José Miguel; Sanz Subirana, Jaume2013-12-10T14:52:26Z