Electronic transport through a parallel--coupled triple quantum dot molecule: Fano resonances and bound states in the continuum

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.Comment: 15 pages, 7 figure

Transport through a quantum wire with a side quantum-dot array

A noninteracting quantum-dot array side-coupled to a quantum wire is studied. Transport through the quantum wire is investigated by using a noninteracting Anderson tunneling Hamiltonian. The conductance at zero temperature develops an oscillating band with resonances and antiresonances due to constructive and destructive interference in the ballistic channel, respectively. Moreover, we have found an odd-even parity in the system, whose conductance vanishes for an odd number of quantum dots while becomes $2e^2/h$ for an even number. We established an explicit relation between this odd-even parity, and the positions of the resonances and antiresonances of the conductivity with the spectrum of the isolated QD arrayComment: 5 pages, 4 figures, submitted to PR

Conductance and persistent current of a quantum ring coupled to a quantum wire under external fields

The electronic transport of a noninteracting quantum ring side-coupled to a quantum wire is studied via a single-band tunneling tight-binding Hamiltonian. We found that the system develops an oscillating band with antiresonances and resonances arising from the hybridization of the quasibound levels of the ring and the coupling to the quantum wire. The positions of the antiresonances correspond exactly to the electronic spectrum of the isolated ring. Moreover, for a uniform quantum ring the conductance and the persistent current density were found to exhibit a particular odd-even parity related with the ring-order. The effects of an in-plane electric field was also studied. This field shifts the electronic spectrum and damps the amplitude of the persistent current density. These features may be used to control externally the energy spectra and the amplitude of the persistent current.Comment: Revised version, 7 pages and 9 figures. To appear in Phys. Rev.

Ibuprofen-loaded calcium phosphate granules : combination of innovative characterization methods to relate mechanical strength to drug location

This paper studies the impact of the location of a drug substance on the physicochemical and mechanical properties of two types of calcium phosphate granules loaded with seven different contents of ibuprofen, ranging from 1.75% to 46%. These implantable agglomerates were produced by either low or high shear granulation. Unloaded Mi-Pro pellets presented higher sphericity and mechanical properties, but were slightly less porous than Kenwood granules (57.7% vs 61.2%). Nevertheless, the whole expected quantity of ibuprofen could be integrated into both types of granules. A combination of surface analysis, using near-infrared (NIR) spectroscopy coupling chemical imaging, and pellet porosity, by mercury intrusion measurements, allowed ibuprofen to be located. It was shown that, from 0% to 22% drug content, ibuprofen deposited simultaneously on the granule surface, as evidenced by the increase in surface NIR signal, and inside the pores, as highlighted by the decrease in pore volume. From 22%, porosity was almost filled, and additional drug substance coated the granule surfaces, leading to a large increase in the surface NIR signal. This coating was more regular for Mi-Pro pellets owing to their higher sphericity and greater surface deposition of drug substance. Unit crush tests using a microindenter revealed that ibuprofen loading enhanced the mechanical strength of granules, especially above 22% drug content, which was favorable to further application of the granules as a bone defect filler

Actividades educativas para preparar a la familia en la prevención de las alteraciones del ritmo y la fluidez del habla

The stimulation of the language in the preschool childhood has a markedly preventive nuance and it focuses particularly on the training of families, being these the first form of social education, with which the boy and the girl interact from the moment of their birth. It constitute a stable sphere of influence, which acts directly on them, in two important periods in the development of the personality, on childhood and adolescence. The education to the family consists of a pedagogically directed system of influences, aimed at raising the preparation of adult relatives's and stimulating their conscious participation in the formation of descendants in coordination with the school. This education provides knowledge, helps to argue opinions, develops attitudes and convictions, stimulates interests and consolidates motivations, contributing to integrate in parents a humanist and scientist conception of the family and the education of the children. The work will use different educational investigation methods at the theoretical, empirical, and mathematical -statistical levels. The application of educational activities will favor the preparation of the family to prevent the alterations in the rhythm and fluency of speech in the preschool childhood.La estimulación del lenguaje en la infancia preescolar tiene un matiz marcadamente preventivo y se centra de manera particular en la capacitación de las familias, siendo esta la primera forma de educación social, con la que interactúa el niño y la niña desde el momento de su nacimiento. Constituye una esfera de influencia estable que actúa directamente sobre ellos, en dos períodos importantes en el desarrollo de la personalidad, infancia y adolescencia. La educación a la familia consiste en un sistema de influencias pedagógicamente dirigido, encaminado a elevar la preparación de los familiares adultos y estimular su participación consciente en la formación de descendencia en coordinación con la escuela. Esta educación suministra conocimientos, ayuda a argumentar opiniones, desarrolla actitudes y convicciones, estimula intereses y consolida motivaciones, contribuyendo a integrar en los padres una concepción humanista y científica de la familia y la educación de los hijos. En el trabajo se utilizarán diferentes métodos de investigación educativa de los niveles teórico, empírico y matemático-estadístico. La aplicación de actividades educativas en la práctica favorecerá a la preparación de la familia para prevenir las alteraciones del ritmo y la fluidez del habla en la infancia preescola

Study of Spin and Decay-Plane Correlations of W Bosons in the e+e- -> W+W- Process at LEP

Data collected at LEP at centre-of-mass energies \sqrt(s) = 189 - 209 GeV are used to study correlations of the spin of W bosons using e+e- -> W+W- -> lnqq~ events. Spin correlations are favoured by data, and found to agree with the Standard Model predictions. In addition, correlations between the W-boson decay planes are studied in e+e- -> W+W- -> lnqq~ and e+e- -> W+W- -> qq~qq~ events. Decay-plane correlations, consistent with zero and with the Standard Model predictions, are measured

Ultrarelativistic sources in nonlinear electrodynamics

The fields of rapidly moving sources are studied within nonlinear electrodynamics by boosting the fields of sources at rest. As a consequence of the ultrarelativistic limit the delta-like electromagnetic shock waves are found. The character of the field within the shock depends on the theory of nonlinear electrodynamics considered. In particular, we obtain the field of an ultrarelativistic charge in the Born-Infeld theory.Comment: 10 pages, 3 figure

Measurement of the Cross Section for Open-Beauty Production in Photon-Photon Collisions at LEP

The cross section for open-beauty production in photon-photon collisions is measured using the whole high-energy and high-luminosity data sample collected by the L3 detector at LEP. This corresponds to 627/pb of integrated luminosity for electron-positron centre-of-mass energies from 189GeV to 209GeV. Events containing b quarks are identified through their semi-leptonic decay into electrons or muons. The e+e- -> e+e-b b~X cross section is measured within our fiducial volume and then extrapolated to the full phase space. These results are found to be in significant excess with respect to Monte Carlo predictions and next-to-leading order QCD calculations