oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 79 )

2018 ( 635 )

2017 ( 650 )

2016 ( 723 )

Custom range...

Search Results: 1 - 10 of 362968 matches for " L. de Guevara "
All listed articles are free for downloading (OA Articles)
Page 1 /362968
Display every page Item
Principales comas metabólicos en pediatría: Elementos de diagnostico y tratamiento
FERNANDO MARTINEZ L. DE GUEVARA
Revista chilena de pediatría , 1953,
Abstract:
Quantum transport of electrons through a parallel-coupled triple quantum-dot molecule
Guevara, M. L. Ladrón de;Orellana, P. A.;
Brazilian Journal of Physics , 2006, DOI: 10.1590/S0103-97332006000600031
Abstract: in this article we study the electronic transport through a triple quantum-dot molecule parallel-coupled to leads under a magnetic field. analytical expressions are obtained for both the conductance and total density of states for the molecule in equilibrium at zero temperature. as a result of quantum interference of resonances belonging to different channels, this configuration exhibits bound states in the continuum (bics). we examine the broadenings of the molecular states around the conditions under which bics occur, finding long-lived states extremely robust under variations of the magnetic flux.
PET/CT en cáncer pulmonar
LADRóN DE GUEVARA H,DAVID; PEFAUR D,RAúL;
Revista médica de Chile , 2010, DOI: 10.4067/S0034-98872010001200015
Abstract: metabolic imaging studies are an integral part of oncology practice, particularly with 18 fuorodeoxyglucose pet scanning. lung cancer is one of the primary indications of a pet/ct study. it is helpful in staging, evaluating treatment response and follow-up of these patients. the recent development of pet/ct, which incorporates a multislice ct scanner to the pet detector, improves results, combining metabolic information from the pet with anatomic data obtained with ct. it reduces false positive results from pet in cases of inflammatory disease such as pneumonia or drug reactions, which are frequent in this group of patients. these conditions are easily recognized by ct. it also improves the detection of primary tumors, when they are adjacent to atelectasis or desmoplastic reactions. pet-ct studies are able to characterize the metabolism of mediastinal and hilar lymph nodes, thus obviating the need for further related imaging studies or invasive procedures. in the assessment of metastatic disease, it allows a whole body analysis in only one study, with high predictive value and optimal cost-benefit relation. the detection of a second primary tumor is not infrequent in these patients. pet-ct is useful in the evaluation of treatment response after chemotherapy, and for the long term follow-up.
PET/CT en cáncer pulmonar PET/CT in lung cancer
DAVID LADRóN DE GUEVARA H,RAúL PEFAUR D
Revista médica de Chile , 2010,
Abstract: Metabolic imaging studies are an integral part of oncology practice, particularly with 18 fuorodeoxyglucose PET scanning. Lung cancer is one of the primary indications of a PET/CT study. It is helpful in staging, evaluating treatment response and follow-up of these patients. The recent development of PET/CT, which incorporates a multislice CT scanner to the PET detector, improves results, combining metabolic information from the PET with anatomic data obtained with CT. It reduces false positive results from PET in cases of inflammatory disease such as pneumonia or Drug reactions, which are frequent in this group of patients. These conditions are easily recognized by CT. It also improves the detection of primary tumors, when they are adjacent to atelectasis or desmoplastic reactions. PET-CT studies are able to characterize the metabolism of mediastinal and hilar lymph nodes, thus obviating the need for further related imaging studies or invasive procedures. In the assessment of metastatic disease, it allows a whole body analysis in only one study, with high predictive value and optimal cost-benefit relation. The detection of a second primary tumor is not infrequent in these patients. PET-CT is useful in the evaluation of treatment response after chemotherapy, and for the long term follow-up.
A propósito del reconocimiento de Colciencias a grupos de investigación en administración
Carlos Dávila L. de Guevara,Florentino Malaver Rodríguez
Cuadernos de Administración , 2004,
Abstract:
Conclusive inner product modification
Luis Roa,A. Delgado,M. L. Ladron de Guevara
Physics , 2009,
Abstract: The task of changing the overlap between two quantum states can not be performed by making use of a unitary evolution only. However, by means of a unitary-reduction process it can be probabilistically modified. Here we study in detail the problem of mapping two known pure states onto other two states in such a way that the final inner product between the outcome states is different from the inner product of the initial states. In this way we design an optimal non-orthogonal quantum state preparation scheme by starting from an orthonormal basis. In this scheme the absolute value of the inner product can be reduced only probabilistically whereas it can be increased deterministically. Our analysis shows that the phases of the involved inner products play an important role in the increase of the success probability of the desired process.
Ghost Fano resonance in a double quantum dot molecule attached to leads
M. L. Ladron de Guevara,F. Claro,Pedro A. Orellana
Physics , 2003,
Abstract: We study the electronic transport through a double quantum dot molecule attached to leads, and examine the transition from a configuration in series to a symmetrical parallel geometry. We find that a progressive reduction of the tunneling through the antibonding state takes place as a result of the destructive quantum interference between the different pathways through the molecule. The Fano resonance narrows down, disappearing entirely when the configuration is totally symmetric, so that only the bonding state participates of the transmission. In this limit the antibonding state becomes completely localized.
Friedel phase discontinuity and bound states in the continuum in quantum dot systems
B. Solis,M. L. Ladron de Guevara,P. A. Orellana
Physics , 2008, DOI: 10.1016/j.physleta.2008.05.014
Abstract: n this article we study the Friedel phase of the electron transport in two different systems of quantum dots which exhibit bound states in the continuum (BIC). The Friedel phase jumps abruptly in the energies of the BICs, which is associated to the vanishing width of these states, as shown by Friedrich and Wintgen in Phys. Rev. A \textbf{31}, 3964 (1985). This odd behavior of the Friedel phase has consequences in the charge through the Friedel sum rule. Namely, if the energy of the BIC drops under the Fermi energy the charge changes abruptly in a unity. We show that this behavior closely relates with discontinuities in the conductance predicted for interacting quantum dot systems.
Electronic transport through a parallel--coupled triple quantum dot molecule: Fano resonances and bound states in the continuum
M. L. Ladrón de Guevara,P. A. Orellana
Physics , 2005, DOI: 10.1103/PhysRevB.73.205303
Abstract: The electronic transport through a triple quantum dot molecule attached in parallel to leads in presence of a magnetic flux is studied. Analytical expressions of the linear conductance and density of states for the molecule in equilibrium at zero temperature are obtained. As a consequence of quantum interference, the conductance exhibits in general a Breit--Wigner and two Fano resonances, the positions and widths of which are controlled by the magnetic field. Every two flux quanta, there is an inversion of roles of the bonding and antibonding states. For particular values of the magnetic flux and dot-lead couplings, one or even both Fano resonances collapse and bound states in the continuum (BIC's) are formed. The line broadenings of the molecular states are examined as a function of the Aharonov--Bohm phase around the condition for the formation of BIC's, finding resonances extremely narrow and robust against variations of the magnetic field.
Controlling Fano and Dicke effects via a magnetic flux in a double quantum-dot molecule
P. A. Orellana,M. L. Ladron de Guevara,F. Claro
Physics , 2004, DOI: 10.1103/PhysRevB.70.233315
Abstract: The electronic transport through a parallel double quantum-dot molecule attached asymmetrically to leads is studied under a magnetic field. We model the system by means of a non interacting two-impurity Anderson Hamiltonian. We find that the conductance shows Fano and Dicke effects that can be controlled by the magnetic flux.
Page 1 /362968
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.