Influence of cephalometric characteristics on the occlusal success rate of Class II malocclusions treated with 2-and 4-premolar extraction protocols

Introduction: The objectives of this investigation were to compare the initial cephalometric characteristics of complete Class II Division 1 malocclusions treated with 2 or 4 premolar extractions and to verify their influence on the occlusal success rate of these treatment protocols. Methods: A sample of 98 records from patients with complete Class II Division 1 malocclusion was divided into 2 groups with the following characteristics: group 1 consisted of 55 patients treated with 2 maxillary first premolar extractions at an initial mean age of 13.07 years; group 2 included 43 patients treated with 4 premolar extractions, with an initial mean age of 12.92 years. Initial and final occlusal statuses were evaluated on dental casts with Grainger`s treatment priority index (TPI), and the initial cephalometric characteristics were obtained from the pretreatment cephalograms. The initial cephalometric characteristics and the initial and final occlusal statuses of the groups were compared with the t test. A multiple regression analysis was used to evaluate the influence of all variables in the final TPI. Results: The 2-premolar extraction protocol provided a statistically smaller TPI and consequently a better occlusal success rate than the 4-premolar extraction protocol. The 4-premolar extraction group had statistically smaller apical base lengths, more vertical facial growth patterns, and greater hard- and soft-tissue convexities at pretreatment than the 2-premolar extraction group. However, the multiple regression analysis showed that only the extraction protocol was significantly associated with the final occlusal status. Conclusions: The initial cephalometric characteristics of the groups did not influence the occlusal success rate of these 2 treatment protocols.

Analysis of Piezoelectric sensor to detect flexural waves

The electromechanical transfer characteristics of adhesively bonded piezoelectric sensors are investigated. By the use of dynamic piezoelectricity theory, Mindlin plate theory for flexural wave propagation, and a multiple integral transform method, the frequency-response functions of piezoelectric sensors with and without backing materials are developed and the pressure-voltage transduction functions of the sensors calculated. The corresponding simulation results show that the sensitivity of the sensors is not only dependent on the sensors' inherent features, such as piezoelectric properties and geometry, but also on local characteristics of the tested structures and the admittance and impedance of the attached electrical circuit. It is also demonstrated that the simplified rigid mass sensor model can be used to analyze successfully the sensitivity of the sensor at low frequencies, but that the dynamic piezoelectric continuum model has to be used for higher frequencies, especially around the resonance frequency of the coupled sensor-structure vibration system.

Flexural waves transmitted by rectangular piezoceramic transducers

Rectangular piezoceramic transducers are widely used in ultrasonic evaluation and health monitoring techniques and structural vibration control applications. In this paper the flexural waves excited by rectangular transducers adhesively attached to isotropic plates are investigated. In view of the difficulties in developing accurate analytical models describing the transfer characteristics of the transducer due to the complex electromechanical transduction processes and transducer-structure interactions involved, a combined theoretical-experimental approach is developed. A multiple integral transform method is used to describe the propagation behaviour of the waves in the plates, while a heterodyne Doppler laser vibrometer is employed as a non-contact receiver device. This combined theoretical-experimental approach enables the efficient characterization of the electromechanical transfer properties of the piezoelectric transducer which is essential for the development of optimized non-destructive evaluation systems. The results show that the assumption of a uniform contact pressure distribution between the transducer and the plate can accurately predict the frequency spectrum and time domain response signals of the propagating waves along the main axes of the rectangular transmitter element.

Stable expression of noncytopathic Kunjin replicons simulates both ultrastructural and biochemical characteristics observed during replication of Kunjin virus

This report focuses mainly on the characterization of a Vero cell line stably expressing the flavivirus Kunjin (KUN) replicon C20SDrep (C20SDrepVero). We showed by immunofluorescence and cryoimmunoelectron microscopy that unique flavivirus-induced membrane structures, termed convoluted membranes/paracrystalline structures, were induced in the C20SDrepVero cells. These induced cytoplasmic foci were immunolabeled with KUN virus anti-NS3 antibodies and with antibodies to the cellular markers ERGIC53 (for the intermediate compartment) and protein disulfide isomerase (for the rough endoplasmic reticulum). However, in contrast to the large perinuclear inclusions observed by immunofluorescence with anti-double-stranded (ds)RNA antibodies in KUN virus-infected cells, the dsRNA in C20SDrepVero cells was localized to small isolated foci scattered throughout the cytoplasm, which were coincident with small foci dual-labeled with the trans-Golgi specific marker GaIT. importantly persistent expression of the KUN replicons in cells did not produce cytopathic effects, and the morphology of major host organelles (including Golgi, mitochondria, endoplasmic reticulum, and nucleus) was apparently unaffected. The amounts of plus- and minus-sense RNA synthesis in replicon cells were similar to those in KUN virus-infected cells until near the end of the latent period, but subsequently increases of about 10- and fourfold, respectively, occurred in infected cells. Virus-specified protein synthesis in C20SDrepVero cells was also about 10-fold greater than that in infected cells. When several KUN replicon cell lines were compared with respect to membrane induction, the relative efficiencies increased in parallel with increases in viral RNA and protein synthesis, consistent with the increases observed during the virus infectious cycle. Based on these observations, cell lines expressing less-efficient replicons may provide a useful tool to study early events in flavivirus RNA replication, which are difficult to assess in Virus infections. (C) 2001 Academic press.

Predicting coal ash slag flow characteristics (viscosity model for the Al2O3-CaO-'FeO'-SiO2 system)

A model has been developed which enables the viscosities of coal ash slags to be predicted as a function of composition and temperature under reducing conditions. The model describes both completely liquid and heterogeneous, i.e. partly crystallised, slags in the Al2O3-CaO-'FeO'-SiO2 system in equilibrium with metallic iron. The Urbain formalism has been modified to describe the viscosities of the liquid slag phase over the complete range of compositions and a wide range of temperatures. The computer package F * A * C * T was used to predict the proportions of solids and the compositions of the remaining liquid phases. The Roscoe equation has been used to describe the effect of presence of solid suspension (slurry effect) on the viscosity of partly crystallised slag systems. The model provides a good description of the experimental data of fully liquid, and liquid + solids mixtures, over the complete range of compositions and a wide range of temperatures. This model can now be used for viscosity predictions in industrial slag systems. Examples of the application of the new model to coal ash fluxing and blending are given in the paper. (C) 2001 Elsevier Science Ltd. All rights reserved.

Olfaction in the Queensland fruit fly, Bactrocera tryoni. II: Response spectra and temporal encoding characteristics of the carbon dioxide receptors

Single-unit electrophysiology was used to record the nerve impulses from the carbon dioxide receptors of female Queensland fruit flies, Bactrocera tryoni. The receptors responded to stimulation in a phasic-tonic manner and also had a period of inhibition of the nerve impulses after the end of stimulation, at high stimulus intensities. The cell responding to carbon dioxide was presented with a range of environmental odorants and found to respond to methyl butyrate and 2-butanone. The coding characteristics of the carbon dioxide cell and the ability to detect other odorants are discussed, with particular reference to the known behavior of the fly.

Effect of aestivation on muscle characteristics and locomotor performance in the Green-striped burrowing frog, Cyclorana alboguttata

The Green-striped burrowing frog. Cyclorana alboguttata survives extended drought periods by burrowing underground and aestivating. These frogs remain immobile within cocoons of shed skin and Mucus during aestivation and emerge from their burrows upon heavy rains to feed and reproduce. Extended periods of immobilisation in mammals typically result in muscle atrophy and a decrease in muscle performance. We examined the effect of aestivation and hence prolonged immobilisation, on skeletal Muscle mass. in vitro muscle performance, and locomotor performance in C. alboguttata. Frogs were aestivated in soil for 3 months and were compared with control animals that remained active, were fed, and had a continual supply of water. Compared to the controls, the wet mass of the gastrocnemius. sartorius, gracilus major. semimembranosus. peroneus, extensor cruris, tibialis posticus and tibialis anticus longus of aestivators remained unchanged indicating no muscle atrophy. The in-vitro performance characteristics of the gastroenemius muscle were maintained and burst swimming speed Was Unaffected, requiring no recovery from the extended period of immobilisation associated with aestivation. This preservation of muscle size, contractile condition and locomotor performance through aestivation enables C. alboguttata to compress their life history into unpredictable windows of opportunity, whenever heavy rains occur.

Acute characteristics of pediatric dysphagia subsequent to traumatic brain injury: Videofluoroscopic assessment

Objective: To document the acute characteristics of swallowing impairment in a group of children post moderate/severe traumatic brain injury (TBI) by means of videofluoroscopy. Participants: Eighteen children with moderate/severe TBI. Main Outcome Measure: Videofluoroscopy at an average of 27.7 days post-injury. Results: Subjects demonstrated a range of dysphagia severity levels: mild-moderate (n = 8), moderate (n = 6), moderate-severe (n = 3), and severe (n = 1) and had a combination of oral and pharyngeal phase characteristics. More specifically; observable features or physiological impairments that were identified included reduced lingual control, hesitancy of tongue movement, repetitive tongue pumping, the presence of aspiration (including silent aspiration), delayed swallow reflex trigger, reduced laryngeal elevation and closure, and reduced peristalsis. Conclusions: These data highlight the diversity of swallowing deficits and dysphagia severity levels in children following TBI and suggest that the former are consistent with a pattern of oropharyngeal impairments.

Propagation of nonstationary curved and stretched premixed flames with multistep reaction mechanisms

The propagation speed of a thin premixed flame disturbed by an unsteady fluid flow of a larger scale is considered. The flame may also have a general shape but the reaction zone is assumed to be thin compared to the flame thickness. Unlike in preceding publications, the presented asymptotic analysis is performed for a general multistep reaction mechanism and, at the same time, the flame front is curved by the fluid flow. The resulting equations define the propagation speed of disturbed flames in terms of the properties of undisturbed planar flames and the flame stretch. Special attention is paid to the near-equidiffusion limit. In this case, the flame propagation speed is shown to depend on the effective Zeldovich number Z(f) , and the flame stretch. Unlike the conventional Zeldovich number, the effective Zeldovich number is not necessarily linked directly to the activation energies of the reactions. Several examples of determining the effective Zeldovich number for reduced combustion mechanisms are given while, for realistic reactions, the effective Zeldovich number is determined from experiments. Another feature of the present approach is represented by the relatively simple asymptotic technique based on the adaptive generalized curvilinear system of coordinates attached to the flame (i.e., intrinsic disturbed flame equations [IDFE]).