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Bistability of persistent currents in mesoscopic rings
E. Anda,V. Ferrari,G. Chiappe
Physics , 1996, DOI: 10.1088/0953-8984/9/5/014
Abstract: We study the persistent currents flowing in a mesoscopic ring threaded by a magnetic flux and connected to a stub of finite length. Multistability processes and Coulomb blockade are demonstrated to be present in this system. These properties are functions of the magnetic flux crossing the ring which plays the role that the external applied potential fulfills in the multistability behaviour of the standard mesoscopic heterostructures.
Dynamic instabilities in resonant tunneling induced by a magnetic field
P. Orellana,E. Anda,F. Claro
Physics , 1997, DOI: 10.1103/PhysRevLett.79.1118
Abstract: We show that the addition of a magnetic field parallel to the current induces self sustained intrinsic current oscillations in an asymmetric double barrier structure. The oscillations are attributed to the nonlinear dynamic coupling of the current to the charge trapped in the well, and the effect of the external field over the local density of states across the system. Our results show that the system bifurcates as the field is increased, and may transit to chaos at large enough fields.
Investigation of DNA Sequences Related to Latency-Associated Transcripts in the Genome of Canine Herpesvirus Type 1 (CHV-1) by Means of Bioinformatics Tools  [PDF]
Ortiz M. A. Hernández, Verde C. Cuenca, Lara E. G. Valdivia, Anda G. Valdivia
Open Journal of Veterinary Medicine (OJVM) , 2019, DOI: 10.4236/ojvm.2019.910013
Abstract: A characteristic common to herpesviruses is the ability to establish a latent infection in the hosts, a transcriptionally active region has detected during latency as well as a set of RNA that are known as Latency Associated Transcripts (LATs), their functions have been clarified in recent work. The present work was carried using different bioinformatics method in order to determine if Herpesvirus Canine 1 (CHV-1) has a region associated with latency. Our result was the selection of nine sequences candidate of micro RNA (miRNA) (MIREval 2.0 software), and 26 miRNA (miRNAFold v.1.0 software), of them, were selected 14 with real precursors of miRNA, two were found between the RL2 and RS1 genes, one in the RL2 gene and 11 in the RS1 gene. The results showed that the similarities of these regions are very low among the herpesviruses analyzed, so it was not possible to deduce the presence of the LAT gene in canine herpesvirus type 1 with bioinformatics. On the other hand, the comparison showed that the miRNA predicted: chv1-mir-mirnafold-8 has similarity with the ebv-mir-BART7-3p of Epstein-Barr Virus (EBV), in this way, the microRNAs predicted by means of bioinformatic programs met the theoretical requirements of these molecules, however at not having a degree of preservation in other herpesviruses, the expression by CHV-1 in latency cannot be confirmed and it is necessary to identify through experimental tests.
Cenote Xbis: The House of Rain  [PDF]
James E. Brady, Guillermo de Anda
Archaeological Discovery (AD) , 2024, DOI: 10.4236/ad.2024.122005
Abstract: This article reports on a sacbe discovered by the Gran Aquífero Maya in the cave/cenote of Xbis, Hoctún, Yucatán, Mexico. The sacbe is the first reported example of a ritual roadway constructed in a Maya cave. The current study details how the construction incorporated elements of the natural cavescape to create Xbis as a significant sacred landmark. The sacbe led to a large pool of water and was constructed into the pool, allowing passage to a large speleothem column without entering the water. Ethnographic data suggests that such cave formations may have been the physical representation of a deity and were the focus of ritual. In addition, water droplets falling from thousands of active stalactites created the effect that it is always raining in the cave. It is proposed that the cave was appropriated and elaborated by elites for ritual because it proclaimed their control over the forces of nature.
Phonon-assisted tunneling regimes in diatomic molecules
E. Vernek,E. V. Anda,S. E. Ulloa,N. Sandler
Physics , 2007, DOI: 10.1103/PhysRevB.76.075320
Abstract: Electronic transport in diatomic molecules (two-level systems) connected to metallic contacts is analyzed in the presence of competing electron-electron and electron-phonon interactions. We show that phonon emission and absorption processes are strongly modified when a Coulomb energy $U$ is included, as the phonons open channels that can result in destructive or constructive interference effects. Resonance conditions for these processes produce dramatic effects both in the density of states at the molecular sites, as well as in the conductance through the system. We find in particular an enhanced {\it Rabi-assisted tunneling} due to phonons, as the resonance conditions are met, which is made more evident for increasing temperatures. These effects are controllable by voltage gating of the molecular sites, and should be accessible in current experiments.
Kondo Regime of a Quantum Dot Molecule: A Finite-U Slave-Boson Approach
E. Vernek,N. Sandler,S. E. Ulloa,E. V. Anda
Physics , 2005, DOI: 10.1016/j.physe.2006.03.099
Abstract: We study the electronic transport in a double quantum dot structure connected to leads in the Kondo regime for both series and parallel arrangements. By applying a finite-U slave boson technique in the mean field approximation we explore the effect of level degeneracy in the conductance through the system. Our results show that for the series connection, as the energy difference of the localized dot levels increases, the tunneling via the Kondo state is destroyed. For the parallel configuration, we find an interesting interplay of state symmetry and conductance. Our results are in good agrement with those obtained with other methods, and provide additional insights into the physics of the Kondo state in the double dot system.
Phonon Rabi-assisted tunneling in diatomic molecules
E. Vernek,E. V. Anda,S. E. Ulloa,N. Sandler
Physics , 2005, DOI: 10.1103/PhysRevB.72.121405
Abstract: We study electronic transport in diatomic molecules connected to metallic contacts in the regime where both electron-electron and electron-phonon interactions are important. We find that the competition between these interactions results in unique resonant conditions for interlevel transitions and polaron formation: the Coulomb repulsion requires additional energy when electrons attempt phonon-assisted interlevel jumps between fully or partially occupied levels. We apply the equations of motion approach to calculate the electronic Green's functions. The density of states and conductance through the system are shown to exhibit interesting Rabi-like splitting of Coulomb blockade peaks and strong temperature dependence under the it interacting resonant conditions.
Alergia al látex: Manifestaciones clínicas en la población general y reactividad cruzada con alimentos Latex allergy: Clinical manifestations in the general population and reactivity crossed with foodstuffs
M. Anda,B. Gómez,E. Lasa,E. Arroabarren
Anales del Sistema Sanitario de Navarra , 2003,
Abstract: La alergia al látex en los últimos a os ha adquirido una gran importancia médica, no sólo para el personal sanitario sino también, aunque en menor medida, para la población general, debido a su ubicuidad. Son múltiples los objetos que manejamos en nuestra vida cotidiana que están fabricados con látex, y que por tanto pueden suponer un riesgo para los pacientes alérgicos a este material. Además del personal sanitario, existe otro subgrupo de pacientes en los que la alergia al látex tiene una mayor incidencia que en la población general; se trata de los pacientes multintervenidos, y especialmente los ni os con espina bífida y mielomeningocele. Las manifestaciones clínicas de alergia al látex, abarcan un amplio abanico: dermatitis de contacto, urticaria, angioedema, rinoconjuntivitis, asma y en ocasiones anafilaxia, dependiendo la presencia de una u otra clínica de la vía de contacto con el látex y también del tiempo de exposición al mismo. Además como ocurre con otros aeroalergenos, existen múltiples reactividades cruzadas con alimentos, por lo que los pacientes alérgicos al látex en muchas ocasiones asocian alergias alimentarias que se deben diagnosticar, ya que su desconocimiento puede suponer un riesgo a adido para el paciente. Because of widespread latex manufacturing in the last decades, latex allergy has become an important clinical problem, not only in high-risk groups (health-workers) but also among the general population. Latex is used to produce a large variety of natural rubber products (medical equipment, household gloves, condoms, balls and balloons,footwear, baby pacifiers…) employed in the ordinary life, with high risk for patients allergic to latex. Among general population, children affected by myelomeningocele or spina bifida, have a higher risk to develop latex allergy. Clinical manifestations range from local reactions(contact dermatitis, urticaria), rhino-conjunctivitis, asthma, pharyngeal edema to severe systemic reactions such anaphylactic shock. Furthermore, latex can crossreact with some plant foods, and patients suffering from latex allergy often associate food allergy.
Inmunoterapia local Local immunotherapy
E. Lasa,S. Garrido,E. Arroabarren,M. Anda
Anales del Sistema Sanitario de Navarra , 2003,
Abstract: La inmunoterapia específica, junto con la evitación del alergeno y el tratamiento sintomático, forma parte del tratamiento de la patología alérgica. La modalidad más antigua, más conocida y mejor estudiada es la inmunoterapia subcutánea (ITSC), cuya eficacia tanto a corto como a largo plazo, ha sido ampliamente demostrada en numerosos estudios. Sin embargo, a pesar de haberse demostrado segura, no está exenta de efectos adversos y precisa ser administrada bajo supervisión de personal médico. Esto ha animado a buscar nuevas vías de administración de eficacia similar, con un buen perfil de seguridad, y de buena cumplimentación por parte del paciente. De las distintas alternativas estudiadas la más relevante es la inmunoterapia sublingual (ITSL). En ésta, se administra el antígeno en forma de gotas debajo de la lengua. Existen diferentes pautas de administración en función del alergeno implicado. La dosis óptima de tratamiento está aún sin determinar, hallándose en este momento en un rango amplio de dosis respecto a la inmunoterapia subcutánea. Su mecanismo de acción es poco conocido aunque en diversos estudios se han observado cambios inmunológicos. La ITSL ha mostrado un buen perfil de seguridad con escasos efectos secundarios, habitualmente de carácter local. Asimismo se han realizado distintos ensayos clínicos en los que se ha demostrado su eficacia en el tratamiento de la alergia respiratoria tanto en ni os como en adultos. Por ello, aunque aún existen datos sin resolver respecto a esta vía de administración de inmunoterapia, ha sido propuesta por la OMS como una alternativa válida a la ITSC. Specific immunotherapy, together with avoidance of the allergen and symptomatic treatment, forms part of the treatment of allergic pathology. The oldest, best known and most studied form is subcutaneous immunotherapy (SCIT), whose efficacy, both in the short and the long term, has been widely demonstrated in numerous studies. However, in spite of having been shown to be safe, it is not free of adverse effects and must be administered under the supervision of medical personnel. This has encouraged the search for new ways of administration of similar efficacy, with a good safety profile and good adherence on the patient’s side. Sublingual immunotherapy (SLIT) is the most relevant of the different alternatives studied. In this alternative the antigen is administered in the form of drops under the tongue. There are different dosages of administration depending on the allergen involved. The optimum treatment dose has still to be determined, at present a wide range of
Switching the sign of photon induced exchange interactions in semiconductor microcavities with finite quality factors
G. Chiappe,E. Louis y E. V. Anda
Physics , 2006, DOI: 10.1103/PhysRevB.74.155320
Abstract: We investigate coupling of localized spins in a semiconductor quantum dot embedded in a microcavity with a finite quality factor. The lowest cavity mode and the quantum dot exciton are coupled forming a polariton, whereas excitons interact with localized spins via exchange. The finite quality of the cavity Q is incorporated in the model Hamiltonian by adding an imaginary part to the photon frequency. The Hamiltonian, which treats photons, spins and excitons quantum mechanically, is solved exactly. Results for a single polariton clearly demonstrate the existence of a resonance, sharper as the temperature decreases, that shows up as an abrupt change between ferromagnetic and antiferromagnetic indirect anisotropic exchange interaction between localized spins. The origin of this spin-switching finite-quality-factor effect is discussed in detail remarking on its dependence on model parameters, i.e., light-matter coupling, exchange interaction between impurities, detuning and quality factor. For parameters corresponding to the case of a (Cd,Mn)Te quantum dot, the resonance shows up for Q around 70 and detuning around 10 meV. In addition, we show that, for such a quantum dot, and the best cavities actually available (quality factors better than 200) the exchange interaction is scarcely affected.
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