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Bogota, Colombia

Lafontaine D.L.J.,Free University of Colombia
Nature Structural and Molecular Biology | Year: 2015

The ribosome, central to protein synthesis in all cells, is a complex multicomponent assembly with rRNA at its functional core. During the process of ribosome biogenesis, diverse noncoding RNAs participate in controlling the quantity and quality of this rRNA. In this Review, I discuss the multiple roles assumed by noncoding RNAs during the different steps of ribosome biogenesis and how they contribute to the generation of ribosome heterogeneity, which affects normal and pathophysiological processes. © 2015 Nature America, Inc. All rights reserved. Source

Beck B.,Free University of Colombia | Blanpain C.,Walloon Excellence in Lifesciences and Biotechnology WELBIO
Nature Reviews Cancer | Year: 2013

The maintenance and repair of many adult tissues are ensured by stem cells (SCs), which reside at the top of the cellular hierarchy of these tissues. Functional assays, such as in vitro clonogenic assays, transplantation and in vivo lineage tracing, have been used to assess the renewing and differentiation potential of normal SCs. Similar strategies have suggested that solid tumours may also be hierarchically organized and contain cancer SCs (CSCs) that sustain tumour growth and relapse after therapy. In this Opinion article, we discuss the different parallels that can be drawn between adult SCs and CSCs in solid tumours. © 2013 Macmillan Publishers Limited. All rights reserved. Source

Blanpain C.,Free University of Colombia
Nature Cell Biology | Year: 2013

Although many genes that lead to different types of cancer when mutated have been identified, the cells that initiate tumour formation following accumulation of these mutations have, until recently, remained elusive. This review explores how mouse genetic lineage-tracing experiments that allow the expression of oncogenes and/or the deletion of tumour suppressor genes in defined cell lineages have been instrumental in defining the cellular origin of different solid tumours in mouse models for various human cancers. © 2013 Macmillan Publishers Limited. All rights reserved. Source

Chamel N.,Free University of Colombia
Physical Review Letters | Year: 2013

Large pulsar frequency glitches are generally interpreted as sudden transfers of angular momentum between the neutron superfluid permeating the inner crust and the rest of the star. Despite the absence of viscous drag, the neutron superfluid is strongly coupled to the crust due to nondissipative entrainment effects. These effects are shown to severely limit the maximum amount of angular momentum that can possibly be transferred during glitches. In particular, it is found that the glitches observed in the Vela pulsar require an additional reservoir of angular momentum. © 2013 American Physical Society. Source

Baye D.,Free University of Colombia
Physics Reports | Year: 2015

The Lagrange-mesh method is an approximate variational method taking the form of equations on a grid thanks to the use of a Gauss-quadrature approximation. The variational basis related to this Gauss quadrature is composed of Lagrange functions which are infinitely differentiable functions vanishing at all mesh points but one. This method is quite simple to use and, more importantly, can be very accurate with small number of mesh points for a number of problems. The accuracy may however be destroyed by singularities of the potential term. This difficulty can often be overcome by a regularization of the Lagrange functions which does not affect the simplicity and accuracy of the method.The principles of the Lagrange-mesh method are described, as well as various generalizations of the Lagrange functions and their regularization. The main existing meshes are reviewed and extensive formulas are provided which make the numerical calculations simple. They are in general based on classical orthogonal polynomials. The extensions to non-classical orthogonal polynomials and periodic functions are also presented.Applications start with the calculations of energies, wave functions and some observables for bound states in simple solvable models which can rather easily be used as exercises by the reader. The Dirac equation is also considered. Various problems in the continuum can also simply and accurately be solved with the Lagrange-mesh technique including multichannel scattering or scattering by non-local potentials. The method can be applied to three-body systems in appropriate systems of coordinates. Simple atomic, molecular and nuclear systems are taken as examples. The applications to the time-dependent Schrödingerequation, to the Gross-Pitaevskii equation and to Hartree-Fock calculations are also discussed as well as translations and rotations on a Lagrange mesh. © 2014 Elsevier B.V. Source

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