Effect of mandibular and tongue protrusion on upper airway size during wakefulness

Oral appliances for the treatment of obstructive sleep apnea (OSA) produce either mandibular or tongue protrusion, and are thought to enlarge the upper airway (UA). We used videoendoscopy to measure UA cross-sectional area (CSA) and shape in the hypopharynx, oropharynx, and velopharynx during various stages of active mandibular and tongue protrusion during wakefulness in 10 patients with OSA and nine control subjects. Measurements were made in the supine position at end-tidal expiration, and were normalized to the CSA in the normal bite position. Airway shape was expressed as the anteroposterior/lateral (AP/L) diameter ratio. There were no differences between OSA patients and controls in the effects of mandibular and tongue protrusion on UA caliber. Both mandibular and tongue protrusion increased CSA in the hypopharynx and oropharynx (p < 0.001), whereas only tongue protrusion increased CSA in the velopharynx (p < 0.001). Tongue protrusion caused a greater increase in oropharyngeal and velopharyngeal CSA than did mandibular protrusion (p < 0.05). Mandibular protrusion caused a greater increase in CSA in the hypopharynx than in the oropharynx or velopharynx (p < 0.05). Obese patients had a larger relative increase in oropharyngeal CSA with mandibular and tongue protrusion than did subjects of normal weight. Tongue protrusion increased the AP/L diameter ratio in the oropharynx and velopharynx (p < 0.001), and mandibular protrusion did so to a lesser extent in the oropharynx (p < 0.01), resulting in a more circular airway shape. We conclude that mandibular and tongue protrusion increase the CSA and alter the shape of the UA during wakefulness.     

Disruption of syntaxin-mediated protein interactions blocks neurotransmitter secretion

The membrane protein syntaxin participates in several protein-protein interactions that have been implicated in neurotransmitter release. To probe the physiological importance of these interactions, we microinjected into the squid giant presynaptic terminal botulinum toxin C1, which cleaves syntaxin, and the H3 domain of syntaxin, which mediates binding to other proteins. Both reagents inhibited synaptic transmission yet did not affect the number or distribution of synaptic vesicles at the presynaptic active zone. Recombinant H3 domain inhibited the interactions between syntaxin and SNAP-25 that underlie the formation of stable SNARE complexes in vitro. These data support the notion that syntaxin-mediated SNARE complexes are necessary for docked synaptic vesicles to fuse.     

Inhomogeneity of rolling texture in fcc metals

The cold rolling of metal sheets and strips results in the formation of an inhomogeneous texture. The type and sharpness of texture in layers and the degree of inhomogeneity depend on the friction between rolls and the material and the geometry of the rolling gap. Contrary to the opinion of several authors, it is shown that the inhomogeneity of texture appears not only in the case of small values of thel/h ratio (l/h characterizes the geometry of the rolling gap) but also in the case of large values whenl/h > 5. In the first case shear texture forms in the intermediate layers of the rolled sheet while in the second, in its outer layers. The results of experiments carried out on aluminum, silver and 70/30 brass clearly show that the sensitivity of metals and alloys to the formation of an inhomogeneous texture is caused by their flow characteristics: yield strength (Y) and the work hardening exponent (m). High values ofY andm will tend to hinder the shear deformation, and consequently they will hinder the occurrence of inhomogeneity.     

High performance AlyGa1−yAs-GaAs-lrxGa1−xAs quantum well lasers defined by silicon-oxygen impurity-induced layer disordering

In these experiments impurity-induced layer disordering (IILD) utilizing chemical reduction of SiO₂ by Al (from Al_0.8Ga_0.2As) is employed to generate Si and O to effect layer disordering. The SiO₂-Al_0.8Ga_0.2As reaction is studied with respect to annealing ambient. By controlling the extent of disordering via As₄ overpressure, closely spaced (∼1μm) Si-O IILD buried heterostructure lasers can be optically coupled or uncoupled. Direct observation of O incorporation into the buried layers is shown using secondary ion mass spectroscopy (SIMS). The thermal stability of separate-confinement Al_yGa_1−yAs-GaAs-In_xGa_1−xAs quantum well heterostructure (QWH) laser crystals is investigated using SIMS, transmission electron microscopy (TEM), and photoluminescence (PL) measurements. The data show that the thermal stability of a strained-layer In_0.1Ga_0.9As quantum well (QW) is strongly dependent upon: (1) the layer thickness and heterointerfaces of the Al_yGa_1−yAs-GaAs waveguide layers located directly above and below the QW, (2) the type of surface encapsulant employed, and (3) the annealing ambient. Narrow single-stripe (<2μm) lasers fabricated via Si-O diffusion and layer disordering exhibit low threshold currents (I_th ∼ 4 mA) and differential quantum efficiencies,η, of 22% per facet under continuous (cw) room-temperature operation.     

THE EFFECT OF DIFFERENT BODIES ON SOME WETTING AND FLOW CHARACTERISTICS OF GLAZES *

Variations in the fluid properties of glazes produced by different bodies were studied, and several methods for testing the wetting ability of the glazes were compared. An angle-of-contact method was found best for measuring the ability of glazes to wet bodies. It was found that different bodies had varying effects on the fluid properties of a glaze. The maturing temperatures of a glaze are not fixed for a given glaze but may vary as much as four cones on different bodies, if wetting ability is considered in determining this temperature.