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Search Results: 1 - 10 of 116504 matches for " O. Casta?os "
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Steady-state quantum correlations of two driven qubits collectively interacting with a vacuum reservoir
L. O. Castaos
Mathematics , 2011,
Abstract: We consider two two-level atoms fixed at different positions, driven by a monochromatic laser field, and interacting collectively with the vacuum electromagnetic field. A Born-Markov-secular master equation is used to describe the dynamics of the two atoms and their steady-state is obtained analytically for two configurations, one in which the atoms are in equivalent positions and another in which they are not. The steady-state populations of the energy levels of the free atoms, entanglement, quantum discord and degree of mixed-ness are calculated analytically as a function of the laser field intensity and the distance between the two atoms. It is found that driving both atoms with the laser field is inefficient for the generation of steady-state correlations when they are in equivalent positions. On the contrary, inequivalent positions lead to the possibility of considerable steady-state entanglement and left/right quantum discord. It is shown that an X-state can be obtained for high laser field intensities for both configurations. This allows the comparison of two measures of quantum discord. The behaviour and relationships between correlations are studied and several limiting cases are investigated.
Transporte y consumo de otras durante la romanización en el norte de la Península Ibérica
Castaos, P.,Escribano, O.
Munibe Antropologia-Arkeologia , 2010,
Abstract: En este trabajo se estudia la presencia de ostras en yacimientos alejados de la costa durante la Romanización en el Norte de la Península Ibérica. Se establece una metodología para la estimación del número mínimo de individuos y la osteometría de esta especie. Se comprueba la importancia cuantitativa del consumo de este molusco en la dieta. Se aborda experimentalmente el problema del transporte de las ostras desde la costa hasta asentamientos de interior. Se establecen las ventajas de las distintas formas de colocación y del grado supervivencia de los animales durante el tiempo de transporte.
Características clínicas e histopatológicas del síndrome nefrótico primario
Bola?os,Laercio; Castao,Iris de;
Colombia Médica , 2005,
Abstract: introduction: the presentation of nephrotic syndrome with severe proteinuria, hypoalbuminemia, generalized edema and his treatment with high-dose of steroides, force the clinicial to recognize and treat opportunely. also must have the ability to predict the outcome and prognosis of the disease after the initial treatment. objectives: to know the behavior of primary nephrotic syndrome in children in cali and peripheral areas, the demographic profiles, the clinical presentation, the response to treatment the histopathology classification and recommendation for renal biopsy. design and methods: from january 1986 to july 2002, 264 medical records of children with primary nephrotic syndrome between 1 to 15 years old were reviewed. results: the mean age for the diagnosis was 4 years, 60% of the patients were males and 40% females. all the patients presented with edema and massive proteinuria, 97% hypoalbuminemia, 94% hypercholesterolemia and 54% oliguria. the response to therapy with corticosteroids was 89% and 11% were corticoresistent: this percentage is lower than other series which report up to 30% corticosteroid resistence. in 65 patients with frequent relapsing we observed good response to cyclophosfamide in 40%. renal biopsy was performed in 73 patients; the indication for the biopsy was no response to steroid therapy in 29%, frequent relapses and steroid dependence in 71%. the diagnosis in these 73 biopsies was minimal changes 36%, mesangial proliferation 46%, focal segmental glomeruloesclerosis 11%, and other pathologies 7%. conclusions: we observed low frequency of corticosteroid resistence patients and focal segmental glomeruloesclerosis than other series. we recommend the use of cyclophosfamide in frequent relapsing patients before doing a renal biopsy. renal biopsy is recommended in corticoid resistent patients. only 40% of the patients had complete follow up in nephrology outpatient clinic. it is important to improve follow up of nephrotic patients.
Primary nephrotic syndrome: clinical and histopathologic characteristics
Laercio Bola?os,Iris de Castao
Colombia Médica , 2005,
Abstract: Introduction: The presentation of nephrotic syndrome with severe proteinuria, hypoalbuminemia, generalized edema and his treatment with high-dose of steroides, force the clinicial to recognize and treat opportunely. Also must have the ability to predict the outcome and prognosis of the disease after initial treatment. Objectives: To review the behavior of primary nephrotic syndrome in children in Cali and peripheral areas, the demographic profiles, the clinical presentation, the response to treatment the histopathology classification and recommendation for renal biopsy. Design and methods: From January 1986 to July 2002, 264 medical records of children with primary nephrotic syndrome between 1 to 15 years old were reviewed. Results: The mean age for the diagnosis was 4 years, 60% of the patients were males and 40% females. All the patients had edema and massive proteinuria, 97% hypoalbuminemia, 94% hypercholesterolemia and 54% oliguria. The response to therapy with corticosteroids was 89% and 11% were corticoresistent: this percentage is lower than other series which report up to 30% corticosteroid resistence. In 65 patients with frequent relapsing we observed good response to cyclophosfamide in 40%. Renal biopsy was performed in 73 patients; the indication for the biopsy was no response to steroid therapy in 29%, frequent relapses and steroid dependence in 71%. The diagnosis in these 73 biopsies was minimal changes 36%, mesangial proliferation 46%, focal segmental glomeruloesclerosis 11%, and other pathologies 7%. Conclusions: We observed low frequency of corticosteroid resistence patients and focal segmental glomeruloesclerosis than other series. We recommend the use of cyclophosfamide in frequent relapsing patients before doing a renal biopsy. Renal biopsy is recommended in corticoid resistent patients. Only 40% of the patients had complete follow up in nephrology outpatient clinic. It is important to improve follow up of nephrotic patients.
Searching for pairing energies in phase space
M. Calixto,O. Castaos,E. Romera
Physics , 2014, DOI: 10.1209/0295-5075/108/47001
Abstract: We obtain a representation of pairing energies in phase space, for the Lipkin-Meshkov-Glick and general boson Bardeen-Cooper-Schrieffer pairing models. This is done by means of a probability distribution of the quantum state in phase space. In fact, we prove a correspondence between the points at which this probability distribution vanishes and the pairing energies. In principle, the vanishing of this probability distribution is experimentally accessible and additionally gives a method to visualize pairing energies across the model control parameter space. This result opens new ways to experimentally approach quantum pairing systems.
Velocity selector with a microwave magnetic dipole transition
L. O. Castaos,E. Gomez
Physics , 2014, DOI: 10.1103/PhysRevA.89.013406
Abstract: We proposed a method based on microwave magnetic dipole transitions to prepare samples of atoms with well defined position and velocity. Each microwave pulse corresponds to a position measurement for the atoms and two pulses separated by a given delay result in a velocity measurement. The method gives velocity sensitivity approaching that obtained with Raman transitions but it is easier to implement. Moreover, it has the advantages that it also selects in position and has less demanding experimental requirements. The method can be demonstrated in a magneto-optical trap.
Neutrinoless Double Beta Decay in Heavy Deformed Nuclei
Jorge G. Hirsch,O. Castaos,P. O. Hess
Physics , 1994, DOI: 10.1016/0375-9474(94)00464-X
Abstract: The zero neutrino mode of the double beta decay in heavy deformed nuclei is investigated in the framework of the pseudo SU(3) model, which has provided an accurate description of collective nuclear structure and predicted half-lives for the two neutrino mode in good agreement with experiments. In the case of $^{238}U$ the calculated zero neutrino half-life is at least three orders of magnitude greater than the two neutrino one, giving strong support of the identification of the radiochemically determined half-life as being the two neutrino double beta decay. For $^{150}Nd$ the zero neutrino matrix elements are of the order of magnitude of, but lesser than, those evaluated using the QRPA. This result confirms that different nuclear models produce similar zero neutrino matrix elements, contrary to the two neutrino case. Using these pseudo SU(3) results and the upper limit for the neutrino mass we estimate the $\beta\beta_{0\nu}$ half-lives for six nuclei. An upper limit for majoron coupling constant is extracted from the experimental data.
Pseudo SU(3) Model and Abnormal Parity States
Jorge G. Hirsch,Octavio Castaos,Peter O. Hess
Physics , 1994,
Abstract: The most important features of the pseudo SU(3) model are reviewed. This description of heavy deformed nuclei is based on pseudo spin symmetry, and is able to correctly predict the collective spectra and their transition amplitudes, using appropriate effective charges. It also gives a very good description of the exotic double beta decay, a hard test of any nuclear model. The simplest pseudo SU(3) assumptions describe nucleons in the abnormal parity states as having seniority zero. This idea is very useful as a mathematical simplification, and is also able to give a nice description of the backbending phenomena, but has been challenged in a recent study about effective charges and $BE2(0^+_1 \rightarrow 2^+_1)$ systematics. We carefully checked this statement and conclude that the seniority zero approach is a formal way of assign abnormal parity nucleons a passive role. The contribution of the abnormal parity nucleons to the nuclear quadrupole moments is finite but only a fraction of their asymptotic Nilsson values.
Double beta decay of $^{100}Mo$: the deformed limit
Jorge G. Hirsch,O. Castaos,P. O. Hess,Osvaldo Civitarese
Physics , 1994, DOI: 10.1103/PhysRevC.51.2252
Abstract: The double beta decay of $^{100}Mo$ to the ground state and excited states of $^{100}Ru$ is analysed in the context of the pseudo SU(3) scheme. The results of this deformed limit are compared with the vibrational one based on the QRPA formalism. Consistency between the deformed limit and the experimental information is found for various $\beta\beta$ transitions, although, in this approximation some energies and B(E2) intensities cannot reproduced.
New species of Tetramorium Mayr (Hymenoptera: Formicidae) from Puebla State, Mexico
Vásquez-Bola?os, M;Castao-Meneses, G;Guzmán-Mendoza, R;
Neotropical Entomology , 2011, DOI: 10.1590/S1519-566X2011000400007
Abstract: tetramorium notomelanum sp. n. is described from the tehuacán valley, state of puebla, méxico. its distribution and relation with other species of the tortuosum-group is discussed. the new species of tetramonium is described from workers, and distinguished from others of the group by several characters: i) black coloration of the body; ii) size: t. notomelanum sp. n. is smaller than t. hispidum (wheeler), t. mexicanum bolton and t.spinosum (pergande), but larger than t. bicolorum vásquez-bola?os and t. placidum bolton; iii) length of the hairs of the dorsal of the head are equal to the diameter of eye; iv) the length of the hairs on the scape and tibiae less than the width of the appendage where they are located. this is the second species of the tortuosum group of tetramorium found in the state of puebla, and the fourth recorded in mexico.
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