Evaluation of upper airways depth among patients with skeletal Class I and III

Background: The aim of this study was to determine the value of upper andlower pharyngeal depth among patients with skeletal Class III malocclusion on lateral cephalograms, as well as to examine the relationship between SNA, SNB, and ANB angles, along with Wits appraisal and the cross-sectional value of upper airway space at the level of the soft palate and tongue base among patients withskeletal Class I and III.Materials and methods: The material consisted of lateral cephalograms taken from 80 patients living in the Lubelskie voivodeship. The study group consistedof cephalograms of 50 patients with skeletal Class III malocclusion (17 maleand 33 female), whereas the control group consisted of 30 roentgenograms of patients with Class I malocclusion with proper jaw to mandible relation (14 maleand 16 female). The study and the control group shared no statistically significant differences considering basic sociographic data such as gender (chi = 1.267, p = 0.26)and age (U = 727.5, p = 0.82). The upper and lower pharyngeal depths wereassessed with the use of McNamara’s method. Spearman’s rho test, Mann--Whitney’s U test, and chi test were used for statistical analysis.Results: Among both males and females the pharyngeal depths were greaterconsidering patients with skeletal Class III in comparison to patients with Class Imalocclusion (p < 0.001). Furthermore, it was determined that the lower as wellas the upper pharyngeal width is statistically significantly dependent on ANB and SNB angles and Wits appraisal (p < 0.001).Conclusions: Pharyngeal width at the level of the soft palate and tongue base depends on skeletal class, namely ANB angle and Wits appraisal; it increases with the increase of SNB angle (forward movement of the mandible). The SNA angle (position of the maxilla) does not influence the anterior-posterior nasopharyngeal dimension

Craniofacial structure in patients with obstructive sleep apnoea

Background: Obstructive sleep apnoea (OSA) is characterised by at least five 10-s episodes of apnoea or markedly shallow breathing per 1 h of sleep, which can lead to severe, sometimes life-threatening complications. It is essential to determine the specific features of the affected patients’ craniofacial structure, thus enabling their allocation to risk groups. The aim of the study was to assess the craniofacial structure in OSA patients, comparing the findings with Hasund’s and Segner’s cephalometric normal values. In addition, the sagittal dimensions of the upper airways, measured at two levels, were compared to McNamara’s normal values. Materials and methods: The study covered 41 patients diagnosed polysomno­graphically with OSA. Lateral cephalograms with cephalometric analysis and the measurements of the upper and lower sagittal dimensions of the upper airways were taken for each patient. Results: The only feature of the patents’ facial skeleton that significantly diverged from the normal range was the SNB angle (p = 0.004). Other angles, i.e. SNA, ANB, NL/NSL, NL/ML and NSL/ML, were not significantly different from normal. The average upper cross-sectional area of the upper airways was 10.4 mm; in 97.6% patients, this measurement was below McNamara’s normal values. In the majority of patients (75.6%), the average lower sagittal dimension of the upper airways (10.4 mm) was also below the normal. Conclusions: Mandibular retrognathia, manifested by the reduced SNB angle, and the narrowed upper and lower sagittal dimensions of the upper airways can be considered one of OSA prognostic factors

Spin Dynamics and Spin Transport

Spin-orbit (SO) interaction critically influences electron spin dynamics and spin transport in bulk semiconductors and semiconductor microstructures. This interaction couples electron spin to dc and ac electric fields. Spin coupling to ac electric fields allows efficient spin manipulating by the electric component of electromagnetic field through the electric dipole spin resonance (EDSR) mechanism. Usually, it is much more efficient than the magnetic manipulation due to a larger coupling constant and the easier access to spins at a nanometer scale. The dependence of the EDSR intensity on the magnetic field direction allows measuring the relative strengths of the competing SO coupling mechanisms in quantum wells. Spin coupling to an in-plane electric field is much stronger than to a perpendicular field. Because electron bands in microstructures are spin split by SO interaction, electron spin is not conserved and spin transport in them is controlled by a number of competing parameters, hence, it is rather nontrivial. The relation between spin transport, spin currents, and spin populations is critically discussed. Importance of transients and sharp gradients for generating spin magnetization by electric fields and for ballistic spin transport is clarified.Comment: Invited talk at the 3rd Intern. Conf. on Physics and Applications of Spin-Related Phenomena in Semiconductors, Santa Barbara (CA), July 21 - 23. To be published in the Journal of Superconductivity. 7 pages, 2 figure

Observation of oscillatory relaxation in the Sn-terminated surface of epitaxial rock-salt SnSe {111}\{111\} topological crystalline insulator

Topological crystalline insulators have been recently predicted and observed in rock-salt structure SnSe $\{111\}$ thin films. Previous studies have suggested that the Se-terminated surface of this thin film with hydrogen passivation, has a reduced surface energy and is thus a preferred configuration. In this paper, synchrotron-based angle-resolved photoemission spectroscopy, along with density functional theory calculations, are used to demonstrate conclusively that a rock-salt SnSe $\{111\}$ thin film epitaxially-grown on \ce{Bi2Se3} has a stable Sn-terminated surface. These observations are supported by low energy electron diffraction (LEED) intensity-voltage measurements and dynamical LEED calculations, which further show that the Sn-terminated SnSe $\{111\}$ thin film has undergone a surface structural relaxation of the interlayer spacing between the Sn and Se atomic planes. In sharp contrast to the Se-terminated counterpart, the observed Dirac surface state in the Sn-terminated SnSe $\{111\}$ thin film is shown to yield a high Fermi velocity, $0.50\times10^6$m/s, which suggests a potential mechanism of engineering the Dirac surface state of topological materials by tuning the surface configuration.Comment: 12 pages, 13 figures, supplementary materials include

Growth and properties of ferromagnetic In(1-x)Mn(x)Sb alloys

We discuss a new narrow-gap ferromagnetic (FM) semiconductor alloy, In(1-x)Mn(x)Sb, and its growth by low-temperature molecular-beam epitaxy. The magnetic properties were investigated by direct magnetization measurements, electrical transport, magnetic circular dichroism, and the magneto-optical Kerr effect. These data clearly indicate that In(1-x)Mn(x)Sb possesses all the attributes of a system with carrier-mediated FM interactions, including well-defined hysteresis loops, a cusp in the temperature dependence of the resistivity, strong negative magnetoresistance, and a large anomalous Hall effect. The Curie temperatures in samples investigated thus far range up to 8.5 K, which are consistent with a mean-field-theory simulation of the carrier-induced ferromagnetism based on the 8-band effective band-orbital method.Comment: Invited talk at 11th International Conference on Narrow Gap Semiconductors, Buffalo, New York, U.S.A., June 16 - 20, 200

Electron spin operation by electric fields: spin dynamics and spin injection

Spin-orbit interaction couples electron spins to electric fields and allows electrical monitoring of electron spins and electrical detection of spin dynamics. Competing mechanisms of spin-orbit interaction are compared, and optimal conditions for the electric operation of electrons spins in a quantum well by a gate voltage are established. Electric spin injection into semiconductors is discussed with a special emphasis on the injection into ballistic microstructures. Dramatic effect of a long range Coulomb interaction on transport phenomena in space-quantized low-dimensional conductors is discussed in conclusion.Comment: A plenary paper at the 11th Intern. Conf. on Narrow Gap Semiconductors (Buffalo, NY, June 2003). To be published in Physica

Two-step model versus one-step model of the inter-polarization conversion and statistics of CdSe/ZnSe quantum dot elongations

The magneto-optical inter-polarization conversions by a layer of quantum dots have been investigated. Various types of polarization response of the sample were observed as a function of external magnetic field and of the orientation of the sample. The full set of experimental dependences is analyzed in terms of a one-step and a two-step model of spin evolution. The angular distribution of the quantum dots over the directions of elongation in the plane of the sample is taken into account in terms of the two models, and the model predictions are compared with experimental observations

Ultrafast manipulation of topologically enhanced surface transport driven by mid-infrared and terahertz pulses in Bi2Se3

Topology-protected surface transport of ultimate thinness in three-dimensional topological insulators (TIs) is breaking new ground in quantum science and technology. Yet a challenge remains on how to disentangle and selectively control surface helical spin transport from the bulk contribution. Here we use the mid-infrared and terahertz (THz) photoexcitation of exclusive intraband transitions to enable ultrafast manipulation of surface THz conductivity in Bi2Se3. The unique, transient electronic state is characterized by frequency-dependent carrier relaxations that directly distinguish the faster surface channel than the bulk with no complication from interband excitations or need for reduced bulk doping. We determine the topological enhancement ratio between bulk and surface scattering rates, i.e., γBS/γSS ~3.80 in equilibrium. The ultra-broadband, wavelength-selective pumping may be applied to emerging topological semimetals for separation and control of the protected transport connected with the Weyl nodes from other bulk bands

External control of the direction of magnetization in ferromagnetic InMnAs/GaSb heterostructures

In this paper, we demonstrate external control over the magnetization direction in ferromagnetic (FM) In_{1-x}Mn_{x}As/GaSb heterostructures. FM ordering with T_C as high as 50 K is confirmed by SQUID magnetization, anomalous Hall effect (AHE), and magneto-optical Kerr effect (MOKE) measurements. Even though tensile strain is known to favor an easy axis normal to the layer plane, at low temperatures we observe that the magnetization direction in several samples is intermediate between the normal and in-plane axes. As the temperature increases, however, the easy axis rotates to the direction normal to the plane. We further demonstrate that the easy magnetization axis can be controlled by incident light through a bolometric effect, which induces a pronounced increase in the amplitude of the AHE. A mean-field-theory model for the carrier-mediated ferromagnetism reproduces the tendency for dramatic reorientations of the magnetization axis, but not the specific sensitivity to small temperature variations.Comment: 11 pages, 3 figures, submitted to NGS-1