This dissertation is devoted to groups generated by bounded automata and geometric objects related to these groups (limit spaces, Schreier graphs, etc.). It is shown that groups generated by bounded automata are contracting. We introduce the notion of a post-critical set of a finite automaton and prove that the limit space of a contracting self-similar group generated by a finite automaton is post-critically finite (finitely-ramified) if and only if the automaton is bounded. We show that the Schreier graphs on levels of automaton groups can be constructed by an iterative procedure of inflation of graphs. This was used to associate a piecewise linear map of the form fK(v) = minA∈KAv, where K is a finite set of nonnegative matrices, with every bounded automaton. We give an effective criterium for the existence of a strictly positive eigenvector of fK. The existence of nonnegative generalized eigenvectors of fK is proved and used to give an algorithmic way for finding the exponents λmax and λmin of the maximal and minimal growth of the components of f(n) K (v). We prove that the growth exponent of diameters of the Schreier graphs is equal to λmax and the orbital contracting coefficient of the group is equal to 1/λmin . We prove that the simple random walks on orbital Schreier graphs are recurrent. A number of examples are presented to illustrate the developed methods with special attention to iterated monodromy groups of quadratic polynomials. We present the first example of a group whose coefficients λmin and λmax have different values.

This dissertation is devoted to groups generated by bounded automata and geometric objects related to these groups (limit spaces, Schreier graphs, etc.). It is shown that groups generated by bounded automata are contracting. We introduce the notion of a post-critical set of a finite automaton and prove that the limit space of a contracting self-similar group generated by a finite automaton is post-critically finite (finitely-ramified) if and only if the automaton is bounded. We show that the Schreier graphs on levels of automaton groups can be constructed by an iterative procedure of inflation of graphs. This was used to associate a piecewise linear map of the form fK(v) = minA[set]KAv, where K is a finite set of nonnegative matrices, with every bounded automaton. We give an effective criterium for the existence of a strictly positive eigenvector of fK. The existence of nonnegative generalized eigenvectors of fK is proved and used to give an algorithmic way for finding the exponents λmax and λmin of the maximal and minimal growth of the components of fK(n)(v). We prove that the growth exponent of diameters of the Schreier graphs is equal to λmax and the orbital contracting coefficient of the group is equal to 1/λmin . We prove that the simple random walks on orbital Schreier graphs are recurrent. A number of examples are presented to illustrate the developed methods with special attention to iterated monodromy groups of quadratic polynomials. We present the first example of a group whose coefficients λmin and λmax have different values.

El presente estudio tuvo por objetivo inmunolocalizar la distribución de las células enteroendocrinas L, productoras del péptido similar al glucagón (GLP-1), en el intestino de alpacas. Una incretina de gran importancia debido a su función reguladora de la glucemia. Se utilizaron 36 crías de alpaca de 0-45 días de edad y adultos, distribuidos en 7 grupos etáreos. 0 días= <24h, 1-7 días, 8-15 días, 16-21 días, 27-34 días, 35-45 días y adultos. Las muestras intestinales fueron procesadas por inmunohistoquímica usando el anticuerpo monoclonal antiGLP-1. Las células positivas fueron contadas en 15 ejes cripta-vellosidad de cada porción intestinal en cada animal. Los resultados evidencian, respecto de los grupos etáreos, que en el dia 0, el yeyuno es la porción que contiene mayor número de células L (productoras de GLP-1); mientras que, en los otros grupos son yeyuno e íleon. Respecto a la ubicación, se determina en duodeno un aumento significativo (p<0.05) de células L desde los 8 días en adelante; en yeyuno el mayor número de células se encuentra a los 0 días; en íleon el mayor número celular se encuentra desde los 8 a 45 días; y en el colon el mayor número lo encontramos en los adultos. Se concluye que las células L en alpacas se encuentran presentes desde el nacimiento mayoritariamente en yeyuno e íleon.

Tesis presentada a la Universidad de Chile para optar al grado de Doctor en Farmacología / La hipertrofia cardíaca es una respuesta adaptativa desencadenada por una mayor demanda de trabajo contráctil por parte del cardiomiocito, su desarrollo es el resultado de múltiples factores, existiendo una hipertrofia cardíaca de tipo fisiológica, reversible, sin signos histológicos de fibrosis, generada por factores de crecimiento como el factor de crecimiento análogo a insulina tipo 1 (IGF-1) y otra de tipo patológico, irreversible, cuya progresión genera insuficiencia cardíaca y cardiomiopatía dilatada, asociada a la acción de agonistas de receptores acoplados a proteína G como norepinefrina (NE), entre otros. Un aspecto importante a considerar es el metabolismo energético del corazón y su participación en el proceso hipertrófico, puesto que es uno de los órganos con mayor tasa de consumo de ATP y una disminución en la disponibilidad energética se traduce en alteraciones de la actividad contráctil y en el desarrollo de distintas patologías cardíacas. La mitocondria es el organelo responsable de la generación de energía en la célula, en el cardiomiocito se encuentran ubicadas entre las miofibrillas y ocupan sobre el 50% del volumen citoplasmático en el músculo cardíaco. Actualmente se reconoce la existencia de un retículo mitocondrial, donde estos organelos forman verdaderos “cables energéticos” cuya morfología y función dependen del equilibrio entre los procesos de fisión y fusión mitocondrial. Diversas proteínas, entre ellas OPA-1 y Mfn1/2 se relacionan con fusión mitocondrial mientras que Drp-1 y Fis-1 se asocian al proceso inverso. Tomando en cuenta la relación entre metabolismo e hipertrofia cardíaca, resulta evidente la importancia que adquieren los procesos de dinámica mitocondrial al regular la función de este organelo. Hasta la fecha se desconoce qué tipo de proceso de dinámica mitocondrial predomina en hipertrofia cardíaca, ni en qué forma la fusión/fisión de la mitocondria afecta el desarrollo del proceso hipertrófico en el cardiomiocito. Por esta razón, el objetivo principal del presente trabajo consistió en determinar si los estímulos prohipertróficos IGF-1 o NE, alteran la morfología y actividad mitocondrial. Para este fin, cultivos primarios de cardiomiocitos de ratas neonatas se trataron con IGF-1 (10 nM) o NE (10 M) entre 0 - 48 h. La red mitocondrial se visualizó mediante microscopía confocal y tinción con mitotracker Green. Los resultados muestran que desde las 24 h, NE produjo fisión de la red mitocondrial, identificada por un incremento en el porcentaje de células con fragmentación mitocondrial (+26 %, p<0,05 y +39 %, p<0,001), en el número relativo de mitocondrias por célula (+42 %, p<0,005 y +65 %, p<0,001) y disminución en el volumen mitocondrial promedio (-24 %, p<0,005 y -47 %, p<0,001, para las 24 y 48 h, respectivamente. Además, luego de los cambios morfológicos se observó una disminución del potencial de membrana mitocondrial (-23 %, p<0,05), del contenido intracelular de ATP (-27 %, p<0,05) y de la velocidad de consumo de oxígeno (-24 %, p<0,05), después de 48 h de exposición a NE. No se observaron cambios morfológicos ni metabólicos en la red mitocondrial de cardiomiocitos tratados con IGF-1. Igualmente se observó que la fisión mitocondrial inducida por NE se asoció con un incremento en la migración de Drp-1 a mitocondria, evaluado a través de un incremento en los niveles de Drp-1 en fracción mitocondrial y aumento en la colocalización entre Drp-1 y Fis-1. Calcineurina es una de las proteínas transduccionales de mayor relevancia en la respuesta hipertrófica inducida por NE, describiéndose que participa en la modulación de la dinámica mitocondrial mediante desfosforilación de Drp-1, incrementando su actividad. Para evaluar su participación, cultivos primarios de cardiomiocitos de ratas neonatas se transducieron con un adenovirus que expresa la subunidad catalítica de calcineurina constitutivamente activa (AdCN) o con uno que codifica un péptido inhibitorio para calcineurina (CAIN), observándose que su inhibición redujo significativamente los cambios morfológicos en la red mitocondrial inducidos por NE y que su sobreexpresión es suficiente para producir fisión mitocondrial. Además, el uso de herramientas adenovirales, también permitió determinar que una disminución en los niveles de Mfn2 produce fisión mitocondrial e induce la respuesta hipertrófica en el cardiomiocito, determinada como un incremento en el área celular, la sarcomerización y la reexpresión de biomarcadores asociados al proceso, mientras que la disminución en la actividad de Drp-1 fusiona la red mitocondrial y previene la hipertrofia cardíaca en los cardiomiocitos tratados con ambos estímulos. En base a estos resultados, se puede concluir que durante el desarrollo del proceso hipertrófico patológico del cardiomiocito se produce fragmentación de la red mitocondrial, a través de un mecanismo que involucra el incremento en la migración de Drp-1 amembrana mitocondrial y la participación de la fosfatasa calcineurina, todo esto asociado a una disminución en diversos parámetros metabólicos. Por otro lado, la modulación en los niveles o actividad de proteínas asociadas a los procesos de fusión y fisión mitocondrial, modificó significativamente el desarrollo del proceso hipertrófico, por lo que colectivamente, estos resultados revelan la importancia de los procesos de dinámica mitocondrial en el desarrollo de hipertrofia cardíaca. / Cardiac hypertrophy is an adaptive response induced by an increased contractile work. Physiological cardiac hypertrophy is reversible, without histological signs of fibrosis, generated by growth factors such as insulin like growth factor 1 (IGF-1). In contrast, pathological cardiac hypertrophy is irreversible, progress to heart failure and dilated cardiomyopathy and it has been associated with the action of G protein-coupled receptors agonists such as norepinephrine. An important aspect to consider is the heart’s energy metabolism and its role in the hypertrophic process, since myocardial tissue is one of the organs with the highest rate of ATP consumption. A decrease in energy availability results in detrimental changes in contractile activity and the development of distinct cardiac diseases. Mitochondria have a key role in energy generation in the cardiomyocyte are located between the myofibrils and occupy over 50% of cytoplasmic volume. The existence of a mitochondrial reticulum is recognized now and these organelles are true "power-transmitting cables" whose morphology and function depend on the balance between mitochondrial fission and fusion. Several proteins like OPA-1 and Mfn1/2 have been linked to mitochondrial fusion while Drp-1 and Fis-1 are associated with mitochondrial fission. Taking into account the relationship between metabolism and cardiac hypertrophy, the role of mitochondrial dynamics in the developrment of hypertrophyc growth must be relevant. However, the mitochondrial morphology in the hypertrophic cardiomyocyte, or how the mitochondrial fusion/fission events affect the development of the cardiomyocyte hypertrophic process is unknown. For this reason, our main objective was to investigate whether IGF-1 or NE stimulation produces changes in morphology and mitochondrial activity. For this goal, primary cultures of neonatal rat cardiomyocytes were treated with IGF-1 (10 nM) or NE (10 M) for 0 - 48 h. The mitochondrial network was visualized by confocal microscopy and Mitotracker Green staining. The results show that NE triggered mitochondrial fission after 24 hours of exposure, identified by an increase in the percentage of cells with mitochondrial fragmentation (+26 %, p <0.05 and +39 %, p <0.001), increase in the relative number of mitochondria per cell (+42 %, p <0.005 and +65 %, p <0.001) and decrease in the average mitochondrial volume (-24 %, p <0.005 and -47 %, p < 0.001, for the 24 and 48 h respectively). In addition to these, morphological changes, decreases in mitochondrial membrane potential (-23 %, p <0.05), intracellular ATP content (-27 %, p <0.05) and oxygen consumption rate (-24 %, p <0.05) were also observed after 48 h of exposure to NE. No morphological or metabolic changes in the mitochondrial network were detected in cardiomyocytes treated with IGF-1. NEinduced mitochondrial fission was associated with an increase in the migration of Drp-1 to mitochondria, evaluated by increase in levels of Drp-1 in mitochondrial fraction and by Drp-1 and Fis-1 colocalization. Calcineurin is one of the most important signaling molecules in the hypertrophic response induced by NE. This phosphatase is also involved in the modulation of mitochondrial dynamics by dephosphorylation of Drp-1, increasing its activity. To evaluate its role, culture neonatal rat cardiomyocytes were transduced with an adenovirus expressesing the calcineurin catalytic subunit constitutively active (AdCN) an inhibitory peptide (CAIN). Inhibition of calcineurin significantly decreased morphological changes in the mitochondrial network triggered by NE and AdCN overexpression being sufficient to cause mitochondrial fission. Using other adenoviral tools, we show that a decrease in Mfn2 levels causes mitochondrial fission, and induces the cardiomyocyte hypertrophic response, determined by increases in cell area, sarcomerización and biomarkers associated with hypertrophic response. The decrease in Drp-1 activity, stimulated mitochondrial fusion and prevented cardiac hypertrophy induced by NE and IGF-1. Collectively our results suggest, that mitochondrial network is fragmented during the development of pathological cardiomyocyte hypertrophy, through a mechanism involving the migration of Drp1 to the mitochondria and the phosphatase calcineurin activation, associated with decreases in several metabolic parameters. In addition, the modulation in the activity of proteins associated with mitochondrial fusion/fission, produced significant changes in the development of hypertrophy. Collectively these results demonstrate the importance of mitochondrial dynamics in the development of cardiac hypertrophy. / CONICYT; FONDAP; FONDECYT; MECESUP

Tesis presentada a la Universidad de Chile para optar al grado de Doctora en Ciencias Farmacéuticas / No autorizada por el autor para ser publicada a texto completo en el Portal de Tesis Electrónicas / Para probar este concepto, se sintetizaron en fase sólida tres nuevos análogos del GLP-1, los cuales fueron caracterizados por cromatografía líquida y espectrometría de masas. Adicionalmente, a los péptidos se les evaluó su estructura secundaria por dicroísmo circular y su actividad insulinotrópica in vitro en la línea celular de páncreas Beta-TC-6. Posteriormente se prepararon y caracterizaron fisicoquímicamente los conjugados obtenidos; para ello se utilizaron técnicas de espectrofotometría UV-visible, microscopía electrónica de transmisión, potencial zeta y dispersión dinámica de la luz. Finalmente se evaluó la estabilidad de los conjugados, se estudió su permeabilidad intestinal, utilizando un sistema in vitro basado en un cocultivo de células de adenocarcinoma de colon humano y mucosecretoras (Caco-2/goblet), y además se determinó la actividad hipoglicemiante in vivo de uno de los péptidos y su respectivo conjugado a AuNP, después de una administración intraperitoneal en ratas. Los resultados obtenidos revelaron que los tres péptidos sintetizados: GLP-1(7- 37)-Lys(Acet), GLP-1(7-37)-Lys(Cys) y GLP-1(7-37)-Lys(PegCys), tienen una conformación de tipo α hélice en disolución acuosa y presentan una actividad insulinotrópica similar a la de la incretina endógena GLP-1. Sin embargo, generan conjugados que difieren en estabilidad y capacidad de penetrar el epitelio intestinal, probablemente debido al tipo de interacción que generan con las AuNP. De esta forma, los conjugados de los péptidos que contienen cisteína (péptidos tiolados) resultaron ser más estables que el del péptido sin cisteína, frente al pH gástrico e intestinal, pues generan una interacción de tipo Au-S que le otorga una mayor estabilidad estérica al sistema coloidal. Por otra parte, el conjugado de AuNP al péptido GLP-1(7-37)-Lys(PegCys) fue el que penetró en mayor medida la monocapa de células, encontrándose aproximadamente un 0.016 % de oro después de 4 h de incubación, mientras que con los otros conjugados el nivel de oro no superó el 0.008 %. Además los péptidos y sus conjugados a AuNP no presentaron toxicidad en los sistemas celulares empleados (Beta-TC-6 y Caco-2/goblet, respectivamente). Finalmente, de la evaluación de la actividad hipoglicemiante in vivo se obtuvo que la eficacia hipoglicémica para el análogo GLP-1(7-37)-Lys(PegCys) y su conjugado a AuNP fue similar a la de la incretina endógena (18.7 ± 6.67 %, 27.6 ± 6.33 % y 22.1 ± 8.26 %, respectivamente), revelando que tanto la modificación realizada en el extremo C- terminal de GLP-1, como la presencia de la AuNP, no afectan su bioactividad. De esta forma, el sistema de entrega desarrollado en esta Tesis demostró penetrar las células intestinales en diferentes grados, y disminuir los niveles de glicemia in vivo de una manera similar al péptido endógeno después de su administración intraperitoenal, revelando que este tipo de sistemas es capaz de atravesar barreras biológicas y que la conjugación al nanomaterial no afecta la actividad de la biomolécula, por lo que podría convertirse en una estrategia para la entrega de biomacromoléculas con aplicación en diabetes / Generally, the therapeutic potential of peptides and proteins is hampered by their physicochemical characteristics, which prevent their successful delivery. In this regard, GLP-1 is a peptide incretin that has great therapeutic usefulness due to their interesting action on glucose metabolism, so it is currently an excellent candidate option for the treatment of the type 2 Diabetes Mellitus. However, as a peptidic macromolecule, GLP- 1 has a poor permeability across the intestinal epithelium and is very susceptible to the enzymatic degradation. To overcome these drawbacks some efforts have been made to improve its therapeutic efficacy, such as development of metabolically stable analogs, but very few studies have been focused on the study of the delivery systems to prolong their action and improve its bioavailability. In this Thesis the study of a potential delivery system based on the use of gold nanoparticles (AuNP) for biomacromolecules, such as GLP-1, is presented. This system searches for to increase the permeability of peptides across the intestinal epithelium and enhance its bioavailability while retaining the biological activity of the biomolecules. Thus, a nanoscale delivery system was developed, wherein GLP-1 analogues were conjugated to the surface of AuNP. To probe this concept, three new analogs of GLP-1 on solid phase were synthesized; the peptides were characterized by liquid chromatography and mass spectrometry and additionally their secondary structure and in vitro insulinotropic activity, using Beta-TC-6 pancreatic cells, were evaluated. Subsequently, the conjugates were physicochemically characterized by UVvisible spectrophotometry, transmission electron microscopy, zeta potential and dynamic light scattering. Finally, the stability of the conjugates and their intestinal permeability, using a mucosecretory in vitro system based on human colon adenocarcinoma cells (Caco-2) and goblet cells were studied. Additionally, the in vivo hypoglycemic activity after intraperitoneal administration en rats of one of the peptides and its conjugate was also determinate. The results revealed that all three peptides synthesized: GLP-1(7-37)-Lys(Acet), GLP-1(7-37)-Lys(Cys) and GLP-1(7-37)-Lys(PegCys), have an α helix conformation in solution, and equal insulinotropic activity than the endogenous incretin GLP-1. However, their conjugates differ in stability and ability to penetrate the intestinal epithelium, probably due to the difference in the interaction with the AuNP. In this way, the conjugates of the peptides containing cysteine (thiolated peptides) were more stable, to the gastric and intestinal pH, than the peptide without cysteine because generate an interaction of Au-S that gives a greater steric stability to the colloidal system. Moreover, the conjugate of GLP-1(7-37)-Lys (PegCys) to AuNP penetrated the cell monolayer in a greater extent than the others, being found about 0.016 % gold after 4 h of incubation, while with the other conjugated the gold level did not exceed 0.008 %. In addition, peptides and their conjugates to AuNP did not show toxicity at cell systems used (Beta-TC-6 and Caco-2/goblet, respectively). Finally, the evaluation of the in vivo hypoglycemic activity showed that the hypoglycemic efficacy for the GLP-1(7-37)-Lys (PegCys) analogue and its AuNP conjugate were similar to the endogenous incretin (18.7 ± 6.67 %, 27.6 ± 6.33 % and 22.1 ± 8.26 %, respectively), revealing that the modification in the C-terminal of the GLP-1 molecule and the presence of the AuNP, do not affect its bioactivity. Thereby, the delivery system developed in this Thesis showed penetrate the intestinal cells in different degrees, and decrease blood glucose levels in vivo in a similar way to the endogenous peptide after intraperitoenal administration, revealing that this type of system is capable of cross biological barriers and that the conjugation to the nanomaterial does not affect the activity of the biomolecule, so it could become a strategy for the delivery of biomacromolecules with application in diabetes

The purpose of this paper is to construct sets, measures and energy forms of certain mixed nested fractals which are spatially homogeneous but not strictly self-similar. We start with the constructions of regular nested fractals, such as Sierpinski gaskets and Koch curves, by employing the iterated map system. Then we show that under the open set condition, the unique invariant (self-similar) measure consists with the normalized Hausdorff measure ristricted on the invariant set. The energy forms construced on regular Sierpinski gaskets and Koch curves is also proved to be a closed form. Next, we use the similar idea, by extending the iterated maps system into a general case, to construct the mixture sets, as well as measures and energy forms. It can be seen that the elements so constructed will not have any strict self-similarity, but them indeed satisfy some weak self-similar properties.

分形分析的主題是研究分形上的Dirichlet形式和Laplacian. 壓縮的自相似群有一個與之關聯的極限空間,此空間通常具備分形結構，因而引發了分形分析和自相似群兩個分支的結合. / 我們回顧了自相似群和它們的極限空間極限空間可以用Schreier 圖來逼近,事實上其可以看成由Schreier圖構造出來的雙曲圖的雙曲邊界.我們探究了迭代單值群. 通過增加專門的條件我們可以得到迭代單值群的極限空間同胚於某個Julia集. / 通過運用[31] 中的想法和[47] 中自相似隨機游動的方法，我們闡明了極限空間上Laplacian和Dirichlet形式的構造步驟我們介紹了加法器， Basilica群以及Hanoi塔群的極限空間(在第三種情況下是Sierpiríski墊片)上的Laplacian 這裡得到的Dirichlet形式是局部且正則的. / 通過採用[53] 的設置, 我們描述了加法器的極限空間上的誘發型Dirichlet形式在構造了加法器的自相似圖上的嚴格可逆隨機游動後，我們可以得到一個非局部的Dirichlet形式. / The major theme of fractal analysis is studying Dirichlet forms and Laplacians on fractals. For a contracting self-similar group there is an associated limit space, which usually exhibits a fractal structure, thereby triggering the combination of fractal analysis and self-similar groups. / We give reviews of self-similar groups and their limit spaces. Limit space can be approximated by Schreier graphs, and it is in fact identied as a hyperbolic boundary of a hyperbolic graph constructed from Schreier graphs. We explore the iterated monodromy groups. By adding technical conditions, we have that the limit space of an iterated monodromy group is homeomorphic to a Julia set. / We show the construction process of Laplacians and Dirichlet forms on limit spaces using the idea of [31] and the method of self-similar random walks from [47]. We present examples of Laplacians of the limit spaces of adding machine, the Basilica group and the Hanoi Tower group (it is Sierpi´nski gasket in this case). In this context these forms are local and regular. / We describe the induced Dirichlet forms on limit space of the adding machine by adopting the settings of [53] . By constructing strictly reversible random walks on self-similarity graph of the adding machine, we can obtain a non-local Dirichlet form. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lin, Dateng. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 71-76). / Abstracts also in Chinese. / Chapter 1 --- Introduction --- p.6 / Chapter 1.1 --- Review of fractal analysis --- p.6 / Chapter 1.2 --- Applications to self-similar groups --- p.7 / Chapter 1.3 --- Boundary theory method --- p.8 / Chapter 1.4 --- Summary of the thesis --- p.9 / Chapter 2 --- Self-similar groups --- p.11 / Chapter 2.1 --- Basic definitions --- p.11 / Chapter 2.2 --- Limit spaces of self-similar groups --- p.18 / Chapter 2.3 --- Schreier graphs approximations --- p.24 / Chapter 2.4 --- Iterated monodromy groups --- p.28 / Chapter 3 --- Construction of Laplacians on limit spaces --- p.35 / Chapter 3.1 --- Dirichlet forms, Laplacians and resistance forms --- p.35 / Chapter 3.2 --- Representations of groups and functions --- p.42 / Chapter 3.3 --- Laplacians on limit spaces --- p.45 / Chapter 4 --- Induced Dirichlet form on limit space of the adding machine --- p.53 / Chapter 4.1 --- Martin boundary and hyperbolic boundary --- p.53 / Chapter 4.2 --- Graph energy and the induced form --- p.62 / Chapter 4.3 --- Induced Dirichlet form of the adding machine --- p.65 / Bibliography --- p.71

Marketers often extend product lines by introducing slight variations of existing products (e.g., there are 53 varieties of Crest toothpaste, 15 varieties of Cheerios). As a result, consumers select from assortments containing relatively similar options. Unfortunately, consumers sometimes fail to differentiate among options, and instead consider the different options as similar and choose. Consequently, prior research shows that selecting from choice sets containing relatively similar options can sometimes lead to negative consequences such as decreased satisfaction. In light of these negative consequences, and given the frequency with which consumers choose from sets of similar options, it becomes important to identify interventions that can be used to optimize option differentiation (i.e., to optimize the perceived difference between two similar options or the perceived variety in an assortment). This dissertation proposes that incidental muscular sensations that consumers encounter while performing regular marketplace activities can serve as one such sensory based intervention. Drawing on theories related to learned associations and classical conditioning, it is proposed that because individuals experience high intensity muscular contractions concurrently with threat/danger, these muscular contractions and the responses they facilitate (i.e., self-protective reflexes) become linked. Through classical conditioning, high (vs. low) intensity incidental muscular sensations eventually activate self-protective reflexes in the absence of any threat or danger. Once activated, self-protective reflexes lead to increased perceptual sensitivity and discriminatory ability, and a sense of unconscious vigilance. Six studies show that the enhanced perceptual sensitivity and unconscious vigilance that result from high (vs. low) intensity muscular sensations optimize option differentiation, and can help to offset the decreased satisfaction that is sometimes associated with choosing from relatively similar options. Theoretical and managerial implications are discussed.

This study investigates the use of authentic subtitled similar task videos (ASSTVs) and their relationship to second language negotiation of meaning and language production among non-native speakers of English in an online task-based language learning (TBLL) environment. Over the course of two weeks, twenty intermediate nonnative speakers (NNSs) of English from the English Language Institute at Texas A&M University engaged in four communicative tasks in pairs using an online TBLL environment designed specifically for this study, and a chat tool in WebCT Vista, a course management system provided by the university. ASSTVs were videotaped and integrated into the online TBLL environment. Participants were divided into two groups, each of which consisted of five dyads, to test the effects of ASSTVs. Five dyads were provided with the ASSTVs and the remaining five dyads were not provided with them before the task completion process. The first section of this study examines the effects of ASSTVs on negotiation of meaning, and the second section examines the effects on language production. The amount of negotiation of meaning was calculated through the negotiation of meaning sequences model developed by Gass and Varonis and revised for online communication by Smith. Language production was investigated in terms of fluency and complexity with regard to lexical and syntactic complexity. A detailed analysis of the data from the chat-scripts showed that NNSs engage in more negotiation of meaning and produce more fluent and lexically diverse language when provided with the ASSTVs than NNSs who were not provided with them. Based on these findings, this study concludes that using ASSTVs in an online TBLL environment is a viable and effective tool for promoting negotiation of meaning and language production in terms of fluency and lexical complexity.

This study investigates the use of authentic subtitled similar task videos (ASSTVs) and their relationship to second language negotiation of meaning and language production among non-native speakers of English in an online task-based language learning (TBLL) environment. Over the course of two weeks, twenty intermediate nonnative speakers (NNSs) of English from the English Language Institute at Texas A&M University engaged in four communicative tasks in pairs using an online TBLL environment designed specifically for this study, and a chat tool in WebCT Vista, a course management system provided by the university. ASSTVs were videotaped and integrated into the online TBLL environment. Participants were divided into two groups, each of which consisted of five dyads, to test the effects of ASSTVs. Five dyads were provided with the ASSTVs and the remaining five dyads were not provided with them before the task completion process. The first section of this study examines the effects of ASSTVs on negotiation of meaning, and the second section examines the effects on language production. The amount of negotiation of meaning was calculated through the negotiation of meaning sequences model developed by Gass and Varonis and revised for online communication by Smith. Language production was investigated in terms of fluency and complexity with regard to lexical and syntactic complexity. A detailed analysis of the data from the chat-scripts showed that NNSs engage in more negotiation of meaning and produce more fluent and lexically diverse language when provided with the ASSTVs than NNSs who were not provided with them. Based on these findings, this study concludes that using ASSTVs in an online TBLL environment is a viable and effective tool for promoting negotiation of meaning and language production in terms of fluency and lexical complexity.