Alberto orellana - Academia.edu (original) (raw)
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Papers by Alberto orellana
El Palacio Municipal de Congresos de Madrid acogio, el pasado sabado 13 de julio, el solemne acto... more El Palacio Municipal de Congresos de Madrid acogio, el pasado sabado 13 de julio, el solemne acto de graduacion del Grupo Educativo CEF.- UDIMA, correspondiente al curso academico 2018-2019 del CEF.- Centro de Estudios Financieros y de la Universidad a Distancia de Madrid, UDIMA. En el se hizo entrega de las becas a los alumnos egresados de grado y master.
Small, 2021
Double‐stranded DNA (dsDNA) fragments exhibit noncovalent attractive interactions between their t... more Double‐stranded DNA (dsDNA) fragments exhibit noncovalent attractive interactions between their tips. It is still unclear how DNA liquid crystal self‐assembly is affected by such blunt‐end attractions. It is demonstrated that stiff dsDNA fragments with moderate aspect ratio can specifically self‐assemble in concentrated aqueous solutions into different types of smectic mesophases on the basis of selectively screening of blunt‐end DNA stacking interactions. To this end, this type of attractions are engineered at the molecular level by constructing DNA duplexes where the attractions between one or both ends are screened by short hairpin caps. All‐DNA bilayer and monolayer smectic‐A type of phases, as well as a columnar phase, can be stabilized by controlling attractions strength. The results imply that the so far elusive smectic‐A in DNA rod‐like liquid crystals is a thermodynamically stable phase. The existence of the bilayer smectic phase is confirmed by Monte‐Carlo simulations of h...
El Centro de Estudios Financieros (CEF.-) celebro el martes 17 de septiembre la ceremonia de entr... more El Centro de Estudios Financieros (CEF.-) celebro el martes 17 de septiembre la ceremonia de entrega de la XXIX edicion del Premio «Estudios Financieros» en el madrileno Club Financiero Genova. Al evento acudieron, ademas de los autores de los trabajos premiados en sus ocho modalidades y sus respectivos jurados, numerosas personalidades de los ambitos academico, juridico, empresarial y de las Administraciones publicas. En representacion del jurado asistio tambien el presidente del Instituto de Contabilidad y Auditoria de Cuentas (ICAC), D. Enrique Rubio. A la edicion de este ano se han presentado un total de 155 trabajos. La gran mayoria proceden de departamentos de investigacion de distintas universidades espanolas, tanto publicas como privadas. El 74 % de los premios han sido otorgados a catedraticos y profesores universitarios, mientras que el resto ha recaido en profesionales tanto de la Administracion publica como de la empresa privada. Estos premios tienen una dotacion total d...
ACM Transactions on Mathematical Software, 2020
Aiming to provide a very accurate, efficient, and robust quartic equation solver for physical app... more Aiming to provide a very accurate, efficient, and robust quartic equation solver for physical applications, we have proposed an algorithm that builds on the previous works of P. Strobach and S. L. Shmakov. It is based on the decomposition of the quartic polynomial into two quadratics, whose coefficients are first accurately estimated by handling carefully numerical errors and afterward refined through the use of the Newton-Raphson method. Our algorithm is very accurate in comparison with other state-of-the-art solvers that can be found in the literature, but (most importantly) it turns out to be very efficient according to our timing tests. A crucial issue for us is the robustness of the algorithm, i.e., its ability to cope with the detrimental effect of round-off errors, no matter what set of quartic coefficients is provided in a practical application. In this respect, we extensively tested our algorithm in comparison to other quartic equation solvers both by considering specific e...
The European Physical Journal E, 2019
Liquid-crystalline phases in all-DNA systems have been extensively studied in the past and althou... more Liquid-crystalline phases in all-DNA systems have been extensively studied in the past and although nematic, cholesteric and columnar mesophases have been observed, the smectic phase remained elusive. Recently, it has been found evidence of a smectic-A ordering in an all-DNA system, where the constituent particles, which are gapped DNA duplexes, resemble chain-sticks. It has been argued that in the smectic-A phase these DNA chain-sticks should be folded as a means to suppress aggregate polydispersity and excluded volume. Nevertheless, if initial crystalline configurations are prepared in silico with gapped DNA duplexes either fully unfolded or fully folded by carrying out computer simulations one can end up with two different phases having at the same concentration and temperature the majority of gapped DNA duplexes either folded or unfolded. This result suggests that these two phases have a small free energy difference, since no transition is observed from one to the other within the simulation time span. In the present manuscript, we assess which of these two phases is thermodynamically stable through a suitable protocol based on thermodynamic integration. Our method is rather general and it can be used to discriminate stable states from metastable ones of comparable free energy.
The European Physical Journal E, 2018
The hard cylinder model decorated with attractive patches proved to be very useful recently in st... more The hard cylinder model decorated with attractive patches proved to be very useful recently in studying physical properties of several colloidal systems. Phase diagram, elastic constants and cholesteric properties obtained from computer simulations based on a simple hard cylinder model have been all successfully and quantitatively compared to experimental results. Key to these simulations is an efficient algorithm to check the overlap between hard cylinders. Here, we propose two algorithms to check the hard cylinder overlap and we assess their efficiency through a comparison with an existing method available in the literature and with the well-established algorithm for simulating hard spherocylinders. In addition, we discuss a couple of optimizations for performing computer simulations of patchy anisotropic particles and we estimate the speed-up which they can provide in the case of patchy hard cylinders.
El Palacio Municipal de Congresos de Madrid acogio, el pasado sabado 13 de julio, el solemne acto... more El Palacio Municipal de Congresos de Madrid acogio, el pasado sabado 13 de julio, el solemne acto de graduacion del Grupo Educativo CEF.- UDIMA, correspondiente al curso academico 2018-2019 del CEF.- Centro de Estudios Financieros y de la Universidad a Distancia de Madrid, UDIMA. En el se hizo entrega de las becas a los alumnos egresados de grado y master.
Small, 2021
Double‐stranded DNA (dsDNA) fragments exhibit noncovalent attractive interactions between their t... more Double‐stranded DNA (dsDNA) fragments exhibit noncovalent attractive interactions between their tips. It is still unclear how DNA liquid crystal self‐assembly is affected by such blunt‐end attractions. It is demonstrated that stiff dsDNA fragments with moderate aspect ratio can specifically self‐assemble in concentrated aqueous solutions into different types of smectic mesophases on the basis of selectively screening of blunt‐end DNA stacking interactions. To this end, this type of attractions are engineered at the molecular level by constructing DNA duplexes where the attractions between one or both ends are screened by short hairpin caps. All‐DNA bilayer and monolayer smectic‐A type of phases, as well as a columnar phase, can be stabilized by controlling attractions strength. The results imply that the so far elusive smectic‐A in DNA rod‐like liquid crystals is a thermodynamically stable phase. The existence of the bilayer smectic phase is confirmed by Monte‐Carlo simulations of h...
El Centro de Estudios Financieros (CEF.-) celebro el martes 17 de septiembre la ceremonia de entr... more El Centro de Estudios Financieros (CEF.-) celebro el martes 17 de septiembre la ceremonia de entrega de la XXIX edicion del Premio «Estudios Financieros» en el madrileno Club Financiero Genova. Al evento acudieron, ademas de los autores de los trabajos premiados en sus ocho modalidades y sus respectivos jurados, numerosas personalidades de los ambitos academico, juridico, empresarial y de las Administraciones publicas. En representacion del jurado asistio tambien el presidente del Instituto de Contabilidad y Auditoria de Cuentas (ICAC), D. Enrique Rubio. A la edicion de este ano se han presentado un total de 155 trabajos. La gran mayoria proceden de departamentos de investigacion de distintas universidades espanolas, tanto publicas como privadas. El 74 % de los premios han sido otorgados a catedraticos y profesores universitarios, mientras que el resto ha recaido en profesionales tanto de la Administracion publica como de la empresa privada. Estos premios tienen una dotacion total d...
ACM Transactions on Mathematical Software, 2020
Aiming to provide a very accurate, efficient, and robust quartic equation solver for physical app... more Aiming to provide a very accurate, efficient, and robust quartic equation solver for physical applications, we have proposed an algorithm that builds on the previous works of P. Strobach and S. L. Shmakov. It is based on the decomposition of the quartic polynomial into two quadratics, whose coefficients are first accurately estimated by handling carefully numerical errors and afterward refined through the use of the Newton-Raphson method. Our algorithm is very accurate in comparison with other state-of-the-art solvers that can be found in the literature, but (most importantly) it turns out to be very efficient according to our timing tests. A crucial issue for us is the robustness of the algorithm, i.e., its ability to cope with the detrimental effect of round-off errors, no matter what set of quartic coefficients is provided in a practical application. In this respect, we extensively tested our algorithm in comparison to other quartic equation solvers both by considering specific e...
The European Physical Journal E, 2019
Liquid-crystalline phases in all-DNA systems have been extensively studied in the past and althou... more Liquid-crystalline phases in all-DNA systems have been extensively studied in the past and although nematic, cholesteric and columnar mesophases have been observed, the smectic phase remained elusive. Recently, it has been found evidence of a smectic-A ordering in an all-DNA system, where the constituent particles, which are gapped DNA duplexes, resemble chain-sticks. It has been argued that in the smectic-A phase these DNA chain-sticks should be folded as a means to suppress aggregate polydispersity and excluded volume. Nevertheless, if initial crystalline configurations are prepared in silico with gapped DNA duplexes either fully unfolded or fully folded by carrying out computer simulations one can end up with two different phases having at the same concentration and temperature the majority of gapped DNA duplexes either folded or unfolded. This result suggests that these two phases have a small free energy difference, since no transition is observed from one to the other within the simulation time span. In the present manuscript, we assess which of these two phases is thermodynamically stable through a suitable protocol based on thermodynamic integration. Our method is rather general and it can be used to discriminate stable states from metastable ones of comparable free energy.
The European Physical Journal E, 2018
The hard cylinder model decorated with attractive patches proved to be very useful recently in st... more The hard cylinder model decorated with attractive patches proved to be very useful recently in studying physical properties of several colloidal systems. Phase diagram, elastic constants and cholesteric properties obtained from computer simulations based on a simple hard cylinder model have been all successfully and quantitatively compared to experimental results. Key to these simulations is an efficient algorithm to check the overlap between hard cylinders. Here, we propose two algorithms to check the hard cylinder overlap and we assess their efficiency through a comparison with an existing method available in the literature and with the well-established algorithm for simulating hard spherocylinders. In addition, we discuss a couple of optimizations for performing computer simulations of patchy anisotropic particles and we estimate the speed-up which they can provide in the case of patchy hard cylinders.