Effects of Functional Electrical Stimulation on Denervated Laryngeal Muscle in a Large Animal Model

Bilateral vocal fold paralysis (BVCP) is a life-threatening condition that follows injury to the Recurrent Laryngeal nerve (RLn) and denervation of the intrinsic laryngeal musculature. Functional electrical stimulation (FES) enables restoration and control of a wide variety of motor functions impaired by lower motor neuron lesions. Here we evaluate the effects of FES on the sole arytenoid abductor, the posterior cricoarytenoid (PCA) muscle in a large animal model of RLn injury. Ten horses were instrumented with two quadripolar intramuscular electrodes in the left PCA muscle. Following a 12-week denervation period, the PCA was stimulated using a once-daily training session for 8 weeks in seven animals. Three animals were used as unstimulated controls. Denervation produced a significant increase in rheobase (P<0.001). Electrical stimulation produced a 30% increase in fiber diameter in comparison with the unstimulated control group (33.9±2.6μm FES+, 23.6±4.2μm FES-, P=0.04). A trend toward a decrease in the proportion of type 1 (slow) fibers and an increase in type 2a (fast) fibers was also observed. Despite these changes, improvement in PCA function at rest was not observed. These data suggest that electrical stimulation using a relatively conservative set of stimulation parameters can reverse the muscle fiber atrophy produced by complete denervation while avoiding a shift to a slow (type 1) fiber type

Restoration of diaphragmatic function after diaphragm reinnervation by inferior laryngeal nerve; experimental study in rabbits

OBJECTIVES: To assess the possibilities of reinnervation in a paralyzed hemidiaphragm via an anastomosis between phrenic nerve and inferior laryngeal nerve in rabbits. Reinnervation of a paralyzed diaphragm could be an alternative to treat patients with ventilatory insufficiency due to upper cervical spine injuries. MATERIAL AND METHOD: Rabbits were divided into five groups of seven rabbits each. Groups I and II were respectively the healthy and the denervated control groups. The 3 other groups were all reinnervated using three different surgical procedures. In groups III and IV, phrenic nerve was respectively anastomosed with the abductor branch of the inferior laryngeal nerve and with the trunk of the inferior laryngeal nerve. In group V, the fifth and fourth cervical roots were respectively anastomosed with the abductor branch of the inferior laryngeal nerve and with the nerve of the sternothyroid muscle (originating from the hypoglossal nerve). Animals were evaluated 4 months later using electromyography, transdiaphragmatic pressure measurements, sonomicrometry and histological examination. RESULTS: A poor inspiratory activity was found in quiet breathing in the reinnervated groups, with an increasing pattern of activity during effort. In the reinnervated groups, transdiaphragmatic pressure measurements and sonomicrometry were higher in group III with no significant differencewith groups IV and V. CONCLUSION: Inspiratory contractility of an hemidiaphragm could be restored with immediate anastomosis after phrenic nerve section between phrenic nerve and inferior laryngeal nerve

Functional Electrical Stimulation of Intrinsic Laryngeal Muscles under Varying Loads in Exercising Horses

Bilateral vocal fold paralysis (BVCP) is a life threatening condition and appears to be a good candidate for therapy using functional electrical stimulation (FES). Developing a working FES system has been technically difficult due to the inaccessible location and small size of the sole arytenoid abductor, the posterior cricoarytenoid (PCA) muscle. A naturally-occurring disease in horses shares many functional and etiological features with BVCP. In this study, the feasibility of FES for equine vocal fold paralysis was explored by testing arytenoid abduction evoked by electrical stimulation of the PCA muscle. Rheobase and chronaxie were determined for innervated PCA muscle. We then tested the hypothesis that direct muscle stimulation can maintain airway patency during strenuous exercise in horses with induced transient conduction block of the laryngeal motor nerve. Six adult horses were instrumented with a single bipolar intra-muscular electrode in the left PCA muscle. Rheobase and chronaxie were within the normal range for innervated muscle at 0.55±0.38 v and 0.38±0.19 ms respectively. Intramuscular stimulation of the PCA muscle significantly improved arytenoid abduction at all levels of exercise intensity and there was no significant difference between the level of abduction achieved with stimulation and control values under moderate loads. The equine larynx may provide a useful model for the study of bilateral fold paralysis

Tight Junction-Related Barrier Contributes to the Electrophysiological Asymmetry across Vocal Fold Epithelium

Electrophysiological homeostasis is indispensable to vocal fold hydration. We investigate tight junction (TJ)-associated components, occludin and ZO-1, and permeability with or without the challenge of a permeability-augmenting agent, histamine. Freshly excised ovine larynges are obtained from a local abattoir. TJ markers are explored via reverse transcriptase polymerase chain reaction (RT-PCR). Paracellular permeabilities are measured in an Ussing system. The gene expression of both TJ markers is detected in native ovine vocal fold epithelium. Luminal histamine treatment significantly decreases transepithelial resistance (TER) (N = 72, p<0.01) and increases penetration of protein tracer (N = 35, p<0.001), respectively, in a time-, and dose-dependent fashion. The present study demonstrates that histamine compromises TJ-related paracellular barrier across vocal fold epithelium. The detection of TJ markers indicates the existence of typical TJ components in non-keratinized, stratified vocal fold epithelium. The responsiveness of paracellular permeabilities to histamine would highlight the functional significance of this TJ-equivalent system to the electrophysiological homeostasis, which, in turn, regulates the vocal fold superficial hydration

Volatility Smile expansions in Lévy models

Litraturverz. S. 54 - 55This thesis is about investigating tail expansions for the call price and implied volatility at large strikes in exponential Levy jump-diffusion models. Furthermore, the asymptotics of the density function and the tail probability are studied. To get these expansions, we use the saddle-point method (method of deepest descent) on the Mellin transform of the call price, respectively density function and tail probability. Expansions for the implied volatility skew are derived by using transfer theorems, sharpening previous results of Benaim and Friz. We consider the double exponential Kou and the Merton Jump Diffusion model in this work.5

Heat transfer modeling of a thin film evaporator in ionic liquid purification

Abweichender Titel nach Übersetzung der Verfasserin/des VerfassersIn dieser Arbeit wurde der Wärmeübergang eines Dünnschichtverdampfers im Zuge eines Wiederaufbereitungschrittes ionischer Flüssigkeit innerhalb eines Zellulosefaserprozesses modelliert. Eine Literaturrecherche über Dünnschicht- und Freifallverdampfer wurde durchgeführt, um den aktuellen Stand der Technik zusammenzufassen. Als eine kurze Einleitung in die Modellierung dieser Verfahren wurde ein kurzer Überlick über die numerische Strömungssimulation, CFD, gegeben. Weiters wurden einige repräsentative Anwendungsfälle aufgelistet. Im Zuge der Arbeit wurden experimentelle Versuchreihen an einem Labor Dünnfilmverdampfer durchgeführt. In einem ersten Schritt wurde ein Parameter-Screening und eine Korelationsanalyse durchgeführt. In einem zweiten Schritt wurde ein angepasstes Set an Parametern herangezogen, um eine Versuchsreihe als Grundlage zur Modellvalidierung zu erhalten. Der Modelierungsteil besteht aus drei verschiedenen Modellen. Das erste Modell wurde in Openfoam mit einem Zweiphasensolver erstellt. Die Ergebnisse gaben Auskunft über die Gültigkeit angenommener Randbedingungen vorangegangener Arbeiten. Zwei weitere Modelle wurden in COMSOL programmiert. Als limitierender Faktor für die auftretende Verdampfung wurde die konstant angenommene spezifische Verdampfungsenthalpie bestimmt. Mithilfe Energiebilanzen wurden Wärmeübergangskoeffizienten sowohl über die Modelle geschätzt als auch experimentell bestimmt. Der so ermittelte Wärmeübergangskoeffizient wurde für das dritte Modell festgelegt. Im dritten Modell wurde der gesamte Verdampfer als eine Kolonne idealer Trennstufen abgebildet. Für jede dieser Trennstufen wurde in einer definierten Modellgeometrie der resultierende Wärmestrom und verdampfende Massenstrom berechnet. Die Modellergebnisse wurden experimentellen Resultaten gegenübergestellt. In drei von vier Fällen stimmten die experimentellen Ergebnisse mit den Modellprognosen nicht überein. Mögliche Ursachen der Abweichung wurden diskutiert und zusammengefasst.In this work the heat transfer of a thin-film evaporator in ionic liquid purification, as a recycling step in a cellulose fiber production process, was modeled. A literature survey over the field of falling film and agitated thin film evaporation was undertaken to summarize the existing knowledge on the process. To provide a basic understanding of the model dynamics, a short introduction over the area of computational fluid dynamics was given also. A brief enumeration of exemplary research CFD applications of evaporation processes rounded off the theoretical part. Experiments with the thin-film evaporation were conducted to evaluate the process parameters and to create an empirical basis for the model evaluation. In a first stage, a correlation analysis of the different process variables was completed with the results of the thin-film evaporation of water. Then, in the second stage the process parameters were adjusted for a conclusive set of experiments for ionic-liquid purification that represented the actual experimental basis for the model evaluation. The modeling part consists of three different models. In the first one, a two-phase CFD Openfoam model was used to set up a case for falling-film flow. Although it was not possible to build up a fully working model, it provided some information on the validity of previous assumptions of thin film evaporation. Two other models were designed in Comsol to predict the heat transfer of the process in terms of required vaporization energy for evaporation. Both were liquid single-phase models.Instead of a continuous flow a series of ideal stages was assumed. Each single stage was simulated in the model and the results were interpolated to attain a result over the whole evaporator column. The models were opposed to the experimental values. In three out of four cases the model did not match with the empirical result. The possible reasons for the divergence were discussed and summarized.10

Effects of group bonding on conformity in antisocial behaviour

Ähnlichkeit ist ein sehr subtiles Mittel um soziales Bonding zu erzeugen. Soziale Bindungen sind ein essentieller Teil des menschlichen Funktionierens und können als Schlüsselmotivation gesehen werden weshalb Menschen Gruppen bilden. Gruppenbildungen führen immer zu einer Unterscheidung von in-group und out-group, sowie zu Bildung von Gruppennormen. Gruppennormen können Motivation für vorteilhaftes und prosoziales Verhalten in Gruppenmitgliedern auslösen, andererseits können sie aber genauso antisoziales und schädliches Verhalten hervorrufen. Die vorliegende Arbeit möchte untersuchen ob sich wahrgenommene Gruppenähnlichkeit auf den Grad an Beteiligung in antisozialem Verhalten auswirkt. In einem gemischten faktoriellen Design spielten 117 Teilnehmer ein Konformitäts-Computerspiel mit entweder destruktiven oder nicht-destruktiven Mitspielern, nachdem sie den Eindruck vermitteln bekamen entweder ähnliche oder unähnliche Mitspieler zu haben. Klickraten in destruktiven Durchgängen dienten als abhängige Variable, die das Verhalten widerspiegelten. Nur das Verhalten der Mitspieler (destruktiv oder nicht-destruktiv) beeinflusste die Konformität in antisozialem Verhalten, aber nicht die wahrgenommene Ähnlichkeit mit der Gruppe. Versuchspersonen mit destruktiven Mitspielern wiesen höhere Klickraten in Abzugsdurchgängen auf als Versuchspersonen mit non-destruktiven Mitspielern. Weitere theoretische und praktische Implikationen werden dargelegt.Similarity is a very subtle means to create social bonds. Social bonds are an essential part of human functioning and can be seen as a key motivation for people to form groups. The formation of groups always leads to the distinction of an in-group and out-group as well as the formation of group norms. Group norms can trigger motivation to beneficial and prosocial behaviour in the members of the group but contrarily the might just as likely unleash antisocial and harmful behaviour. This present research aimed at investigating whether perceived group similarity acts as a factor that moderates the degree of engagement in antisocial behaviour. In a mixed factorial design, 117 participants played a conformity computer game with either destructive or non-destructive co-players after having gotten the impression of having either similar or dissimilar co-players. Clicking rates in destructive trials served as a dependent variable reflecting behaviour. Only the behaviour by co-players (destructive or non-destructive) impacted the conformity in antisocial behaviour, but not the perceived similarity with one’s group. Participants with destructive co-players showed higher clicking rates in subtraction trials than participants with non-destructive co-players. Theoretical and practical implications are discussed