11 results on '"Ramón Torres"'
Search Results
2. On the quantum corrected gravitational collapse
- Author
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Ramón Torres and Francesc Fayos
- Subjects
Gravitational collapse ,Black holes ,Singularities ,Quantum gravity ,Information paradox ,Physics ,QC1-999 - Abstract
Based on a previously found general class of quantum improved exact solutions composed of non-interacting (dust) particles, we model the gravitational collapse of stars. As the modeled star collapses a closed apparent 3-horizon is generated due to the consideration of quantum effects. The effect of the subsequent emission of Hawking radiation related to this horizon is taken into consideration. Our computations lead us to argue that a total evaporation could be reached. The inferred global picture of the spacetime corresponding to gravitational collapse is devoid of both event horizons and shell-focusing singularities. As a consequence, there is no information paradox and no need of firewalls. more...
- Published
- 2015
- Full Text
- View/download PDF
Catalog
3. Secondary chemical equilibria in reversed-phase liquid chromatography
- Author
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María Celia García-Alvarez-Coque, José Ramón Torres-Lapasió, M.J. Ruiz-Angel, and José Antonio Navarro-Huerta
- Published
- 2023
- Full Text
- View/download PDF
4. Contributors
- Author
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Adham Ahmed, Jeanethe A. Anguizola, Katia Arena, Sanka N. Atapattu, Juan José Baeza-Baeza, Kimber L. Barnett, Bogusław Buszewski, Francesco Cacciola, Andrea Carotti, Martina Catani, Alberto Cavazzini, Bezhan Chankvetadze, G. D’Orazio, John W. Dolan, Paola Dugo, Filip Duša, C. Fanali, Salvatore Fanali, Tivadar Farkas, Attila Felinger, František Foret, T. Fornstedt, P. Forssén, María Celia García-Alvarez-Coque, Timothy W. Graul, Paul R. Haddad, David S. Hage, Brent Harrington, Srishti Joshi, Malte Kaspereit, Julia Kuligowski, Margaret E. LaCourse, William R. LaCourse, Fernando Mauro Lanças, Bernhard Lendl, Rong Li, Edvaldo Vasconcelos Soares Maciel, Ryan Matsuda, Sven W. Meckelmann, Laura Mercolini, Luigi Mondello, José Antonio Navarro-Huerta, P.N. Nesterenko, Efthimia Papastavros, P. Peluso, Erika Pfaunmiller, Colin F. Poole, S. Della Posta, Jan Přikryl, Michele Protti, Guillermo Quintás, M. Asensio Ramon, Anurag S. Rathore, Marja-Liisa Riekkola, M.J. Ruiz-Angel, Antonio Salgado, J. Samuelsson, Roccaldo Sardella, Deepika Sarin, Oliver J. Schmitz, Andreas Seidel-Morgenstern, Jozef Šesták, Kevin Skinley, Lloyd R. Snyder, Matthew Sobansky, André M. Striegel, José Ramón Torres-Lapasió, Anna Týčová, Deyber Arley Vargas Medina, Justyna Walczak-Skierska, Susanne K. Wiedmer, Haifei Zhang, and Xiwei Zheng more...
- Published
- 2023
- Full Text
- View/download PDF
5. Mobile phase selection in liquid chromatography
- Author
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María Celia García-Alvarez-Coque, José Ramón Torres-Lapasió, Juan José Baeza-Baeza, and José Antonio Navarro-Huerta
- Published
- 2023
- Full Text
- View/download PDF
6. Mechanical properties of hydraulic concretes with partial replacement of Portland cement by pozzolans obtained from agro-industrial residues: A review
- Author
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Ramon Torres-Ortega, Diego Torres-Sanchez, and Teresa Lopez-Lara
- Subjects
Natural pozzolans ,Agro-industrial by-products in concrete ,Pozzolanic concrete ,Science (General) ,Q1-390 ,Social sciences (General) ,H1-99 - Abstract
The search for alternative material sources to conventional ones has had a significant impact on the construction sector today, driven by the implementation of sustainable development policies on a global scale. Alternative cementitious materials, such as agricultural industry by-products, have been introduced to ensure the efficient use of renewable natural resources while promoting a balance between the technical and economic aspects of infrastructure projects. This article provides an overview of research conducted on the use of pozzolans derived from agro-industrial by-products, such as rice husk ash (RHA), palm oil fuel ash (POFA), and sugarcane bagasse ash (SCBA), which have a high content of amorphous silica. This silica reacts with calcium hydroxide during the hydration process of Portland cement, leading to the production of calcium silicate hydrate (C-S-H) gel with cementitious properties. Investigations have explored the improvements these pozzolans provide in terms of compressive, flexural, and tensile strength in concretes where conventional Portland cement has been partially replaced by these materials. The influence of temperature and grinding processes used in their preparation was also determined, with optimal temperatures for obtaining amorphous silica ranging between 600 °C and 700 °C. Additionally, the optimal replacement levels for enhancing the mechanical properties of concrete were found to range between 10 % and 20 %. more...
- Published
- 2025
- Full Text
- View/download PDF
7. On the quantum corrected gravitational collapse
- Author
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Francesc Fayos, Ramón Torres, Universitat Politècnica de Catalunya. Departament de Física, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
High Energy Physics - Theory ,Nuclear and High Energy Physics ,Gravitació ,Event horizon ,General relativity ,White hole ,Black hole information paradox ,FOS: Physical sciences ,Primordial black hole ,General Relativity and Quantum Cosmology (gr-qc) ,General Relativity and Quantum Cosmology ,Gravitational collapse ,Exotic star ,Astrophysics::Galaxy Astrophysics ,Physics ,Black holes ,Estels -- Evolució ,Quantum gravity ,lcsh:QC1-999 ,Black hole ,Information paradox ,Classical mechanics ,High Energy Physics - Theory (hep-th) ,Física::Astronomia i astrofísica [Àrees temàtiques de la UPC] ,Stars -- Evolution ,Singularities ,lcsh:Physics ,Gravitation - Abstract
Based on a previously found general class of quantum improved exact solutions composed of non-interacting (dust) particles, we model the gravitational collapse of stars. As the modeled star collapses a closed apparent 3-horizon is generated due to the consideration of quantum effects. The effect of the subsequent emission of Hawking radiation related to this horizon is taken into consideration. Our computations lead us to argue that a total evaporation could be reached. The inferred global picture of the spacetime corresponding to gravitational collapse is devoid of both event horizons and shell-focusing singularities. As a consequence, there is no information paradox and no need of firewalls., 14 pages, 5 figures; Corrected sentence on the physical content. Added new reference and acknowledgements more...
- Published
- 2015
8. Singularity free gravitational collapse in an effective dynamical quantum spacetime
- Author
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Ramón Torres, Francesc Fayos, Universitat Politècnica de Catalunya. Departament de Física Aplicada, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
High Energy Physics - Theory ,Physics ,Nuclear and High Energy Physics ,Quantum field theory in curved spacetime ,Física [Àrees temàtiques de la UPC] ,General relativity ,Gravitational collapse ,Black holes ,Quantum gravity ,FOS: Physical sciences ,Hawking radiation ,General Relativity and Quantum Cosmology (gr-qc) ,General Relativity and Quantum Cosmology ,Black hole ,Micro black hole ,Forats negres (Astronomia) ,Classical mechanics ,High Energy Physics - Theory (hep-th) ,Semiclassical gravity ,Black holes (Astronomy) - Abstract
We model the gravitational collapse of heavy massive shells including its main quantum corrections. Among these corrections, quantum improvements coming from Quantum Einstein Gravity are taken into account, which provides us with an effective quantum spacetime. Likewise, we consider dynamical Hawking radiation by modeling its back-reaction once the horizons have been generated. Our results point towards a picture of gravitational collapse in which the collapsing shell reaches a minimum non-zero radius (whose value depends on the shell initial conditions) with its mass only slightly reduced. Then, there is always a rebound after which most (or all) of the mass evaporates in the form of Hawking radiation. Since the mass never concentrates in a single point, no singularity appears., 19 pages, 5 figures more...
- Published
- 2014
9. Singularity-free gravitational collapse and asymptotic safety
- Author
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Ramón Torres, Universitat Politècnica de Catalunya. Departament de Física Aplicada, and Universitat Politècnica de Catalunya. DF - Dinàmica No Lineal de Fluids
- Subjects
High Energy Physics - Theory ,Black-holes ,Nuclear and High Energy Physics ,Gravitació ,General relativity ,Asymptotic safety in quantum gravity ,FOS: Physical sciences ,General Relativity and Quantum Cosmology (gr-qc) ,Astrophysics::Cosmology and Extragalactic Astrophysics ,General Relativity and Quantum Cosmology ,Time ,symbols.namesake ,Singularity ,Gravitational collapse ,Astrophysics::Solar and Stellar Astrophysics ,Einstein ,Astrophysics::Galaxy Astrophysics ,Physics ,Black holes ,Quantum gravity ,Naked singularity ,Spacetimes ,Asymptotic safety ,Forats negres (Astronomia) ,Classical mechanics ,High Energy Physics - Theory (hep-th) ,symbols ,Gravitational singularity ,Física::Relativitat [Àrees temàtiques de la UPC] ,Astrophysics::Earth and Planetary Astrophysics ,Black holes (Astronomy) ,Singularities ,Naked singularities - Abstract
A general class of quantum improved stellar models with interiors composed of non-interacting ('dust') particles is obtained and analyzed in a framework compatible with asymptotic safety. First, the effective exterior, based on the Quantum Einstein Gravity approach to asymptotic safety is presented and, second, its effective compatible dust interiors are deduced. The resulting stellar models appear to be devoid of shell-focusing singularities., Comment: 11 pages, 1 figure. Added a comment for the energy-momentum tensor with respect to version 2 on the arXiv more...
- Published
- 2014
10. Refining geomagnetic field intensity changes in Europe between 200 CE and 1800 CE. New data from the Mediterranean region
- Author
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Rivero Montero, M., Gómez Paccard, M., Pavón Carrasco, Francisco Javier, Cau Ontiveros, M.A., Fantuzzi, L., Martín Hernández, Fátima, Palencia Ortas, Alicia, Aidona, E., Tema, E., Kondopoulou, D., Mas Florit, C., Ramón Torres, J., Rivero Montero, M., Gómez Paccard, M., Pavón Carrasco, Francisco Javier, Cau Ontiveros, M.A., Fantuzzi, L., Martín Hernández, Fátima, Palencia Ortas, Alicia, Aidona, E., Tema, E., Kondopoulou, D., Mas Florit, C., and Ramón Torres, J. more...
- Abstract
Absolute past geomagnetic intensity values can mainly be recovered by fired archaeological materials and volcanic rocks. Here, we present 10 new archeointensities from the Mediterranean region that help to better constrain geomagnetic field intensity changes in Europe over the last two millennia. The new archeointensity results were obtained from the Thellier classical method including thermoremanent magnetization (pTRM) checks and both the TRM anisotropy and cooling rate corrections and were derived from at least three specimens. The new data presented, together with a selection of previous archeointensities satisfying a set of quality criteria, confirm the presence of several intensity maxima in Europe over the last 2000 years. In particular, the new archeointensities allow to better define the starting point of the double-oscillation feature that occurred in Europe during the second half of the first millennium CE, and reinforce the existence of a relative maximum at the end of the 14th century - beginning of the 15th century in Western Europe. From selected European archeointensities two new paleosecular variation curves are constructed for Western and Eastern Europe using temporal cubic b-splines in a bootstrap approach. The obtained curves suggest that the occurrence of the intensity maxima is characterized by a period of about 300 ± 50 years. In addition, our results suggest that the maxima do not occur simultaneously in Western and Eastern Europe, pointing out an intensity eastward drift with a mean lag-time of about 100 years., Ministerio de Ciencia, Innovación y Universidades (España), Fondo Europeo de Desarrollo Regional, Generalitat de Catalunya, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub more...
11. Refining geomagnetic field intensity changes in Europe between 200 CE and 1800 CE. New data from the Mediterranean region
- Author
-
Rivero Montero, M., Gómez Paccard, M., Pavón Carrasco, Francisco Javier, Cau Ontiveros, M.A., Fantuzzi, L., Martín Hernández, Fátima, Palencia Ortas, Alicia, Aidona, E., Tema, E., Kondopoulou, D., Mas Florit, C., Ramón Torres, J., Rivero Montero, M., Gómez Paccard, M., Pavón Carrasco, Francisco Javier, Cau Ontiveros, M.A., Fantuzzi, L., Martín Hernández, Fátima, Palencia Ortas, Alicia, Aidona, E., Tema, E., Kondopoulou, D., Mas Florit, C., and Ramón Torres, J. more...
- Abstract
Absolute past geomagnetic intensity values can mainly be recovered by fired archaeological materials and volcanic rocks. Here, we present 10 new archeointensities from the Mediterranean region that help to better constrain geomagnetic field intensity changes in Europe over the last two millennia. The new archeointensity results were obtained from the Thellier classical method including thermoremanent magnetization (pTRM) checks and both the TRM anisotropy and cooling rate corrections and were derived from at least three specimens. The new data presented, together with a selection of previous archeointensities satisfying a set of quality criteria, confirm the presence of several intensity maxima in Europe over the last 2000 years. In particular, the new archeointensities allow to better define the starting point of the double-oscillation feature that occurred in Europe during the second half of the first millennium CE, and reinforce the existence of a relative maximum at the end of the 14th century - beginning of the 15th century in Western Europe. From selected European archeointensities two new paleosecular variation curves are constructed for Western and Eastern Europe using temporal cubic b-splines in a bootstrap approach. The obtained curves suggest that the occurrence of the intensity maxima is characterized by a period of about 300 ± 50 years. In addition, our results suggest that the maxima do not occur simultaneously in Western and Eastern Europe, pointing out an intensity eastward drift with a mean lag-time of about 100 years., Ministerio de Ciencia, Innovación y Universidades (España), Fondo Europeo de Desarrollo Regional, Generalitat de Catalunya, Depto. de Física de la Tierra y Astrofísica, Fac. de Ciencias Físicas, TRUE, pub more...
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