Binding Energies and Optical Properties of Power-Exponential and Modified Gaussian Quantum Dots.

We examine the optical and electronic properties of a GaAs spherical quantum dot with a hydrogenic impurity in its center. We study two different confining potentials: (1) a modified Gaussian potential and (2) a power-exponential potential. Using the finite difference method, we solve the radial Schrodinger equation for the 1s and 1p energy levels and their probability densities and subsequently compute the optical absorption coefficient (OAC) for each confining potential using Fermi's golden rule. We discuss the role of different physical quantities influencing the behavior of the OAC, such as the structural parameters of each potential, the dipole matrix elements, and their energy separation. Our results show that modification of the structural physical parameters of each potential can enable new optoelectronic devices that can leverage inter-sub-band optical transitions.

Harnessing a Dielectric/Plasma Photonic Crystal as an Optical Microwave Filter: Role of Defect Layers and External Magnetic Fields.

We investigate the transmittance spectrum of a multichannel filter composed of dielectric (A) and plasma (P) materials in the microwave region within the transfer matrix formalism. Two configurations of the proposed filter are studied under the influence of an applied magnetic field: (1) a periodic structure containing (A/P)N unit cells surrounded by air and (2) the introduction of a second dielectric material (D) acting as a defect layer to produce an (AP)N/2/D/(AP)N/2 structure. Our findings reveal that in the periodic case, the number of resonant states of the transmittance increases with number N; however, the observed blue and red shifts depend on the intensity and orientation of the applied magnetic field. We present contour plots of the transmission coefficients that show the effect of the incident angle on the shifts of the photonic band gaps. Furthermore, we find that the introduction of a defect layer generates additional resonant states and merges the central resonant peak into a miniband of resonances. Moreover, we show that the number of resonant peaks and their locations can be modulated by increasing the unit cell number, N, as well as increasing the width of the inserted defect layer. Our proposed structures enable the design of novel photonic filters using magnetized plasma materials operating in the microwave region.

[Early treatment of Class III malocclusion by maxillary protraction facial mask: effects on craniofacial structures and upper airway dimensions]. / Le traitement interceptif des malocclusions de classe III par masque facial : quelle incidence sur les voies aérifères supérieures ?

The aim of our study was to evaluate the effect of treatment with a maxillary protraction appliance on the development of the craniofacial structures and to describe the correlation between the skeletal changes and the sagittal airway dimension associated with tongue, soft palate, and hyoid bone position in skeletal Class III children. A total of 40 patients with Class III malocclusions were evaluated by the use of lateral cephalograms. Pretreatment and posttreatment cephalometric radiographs were analyzed; linear and angular measurements were performed by the same orthodontist. The effect of treatment with a maxillary protraction appliance on the development of the craniofacial structures were evaluated by Student's T test and the correlation between treatment changes in craniofacial morphology and those in upper airway, tongue, soft palate, and hyoid position was evaluated by Pearson's correlation test. A significant increase in maxillary forward growth, inhibition of mandibular forward growth, and clockwise rotation of the mandible were observed. The statistical analysis revealed that maxillary growth had a significant positive effect on the superior upper airway sagittal dimension. The nasopharyngeal airway dimensions can be improved in the short term with maxillary protraction in skeletal Class III children.