Fluent sentence comprehension requires the automatic application of grammatical principles, in combination with other kinds of information, to a linear input string. The latter can vary greatly in complexity, and it has been observed that structures that involve non-adjacent relationships (non-local dependencies) cause particular processing difficulties, for even fluent readers. This thesis focuses on the potential role that L1 transfer plays in processing non-local dependencies in the L2. Although L1 transfer has been demonstrated in a variety of L2 domains (Juffs, 2005), the degree to which L1 syntactic properties influence the L2 in real-time processing remains an open question (Clahsen & Felser, 2006b). A better understanding of L1 influence on L2 processing has important implications for emerging models of L2 sentence processing and SLA theory in general. This thesis examines L1 effects on the processing of L2 English relative clauses. It builds on established models of L1 relative clause processing (e.g., Gibson, 1998) and focuses on the asymmetry observed in the processing of subject versus object relative clauses. Research has shown that L1 individuals find object relative clauses more difficult to process than their subject counterparts (King & Just, 1991), and off-line L2 research suggests that this asymmetry might hold for L2 processing as well (Izumi, 2003; Kanno, 2007). This thesis will examine the asymmetry on-line and investigate the role that L1 background plays in on-line performance, both alone and in combination with other processing factors. The main data are on-line performance by three groups of advanced-level learners of L2 English from Japan, China, and Vietnam. The three L1s differ from English to varying degrees in relative clause formation, as reflected in head direction, branching direction and the presence of an overt relative marker. Vietnamese shares all three properties with English and Japanese none, leading to the prediction that the Japanese learners will have the greatest difficulty, as evident in the largest subject/object asymmetry in processing times. Evidence for the effect of L1 syntactic properties on L2 processing will be sought in a set of studies that compare processing outcomes for these learners across key individual difference factors in L2 processing, working memory capacity, lexical processing efficiency, and proficiency. The effect of non-structural information, in the form of animacy contrasts and frequency effects, on L2 syntactic processing across the L1 groups will also be examined. By systematically examining group differences across these key factors, the degree and nature of potential L1 influence on the processing of these non-local dependencies can be better assessed. Three groups of advanced-level L2 English learners from China, Japan, and Vietnam, a group of intermediate-level learners in Japan, and native English controls participated in the data collection. Participants were first tested on a battery of individual difference measures that established language proficiency and general processing skill for individual participants and groups. On-line reading data of relative clause structures were then collected and reported in a set of five studies. Study 1 examined reading when the target structures contained high frequency content words, which minimized word recognition demands. Advanced L2 learners took longer to read object relative clauses, and the difference was the greatest for the Japanese group. Study 2 revealed that the subject/object asymmetry and L1 influence evident in Study 1 disappeared when word recognition was effortful, as in sentences with low frequency words, suggesting that L1 syntactic influence may only be evident when lexical processing is relatively automatic. Study 3 examined the effect of proficiency differences on processing outcomes by comparing performance by Intermediate and Advanced Japanese learners. The Intermediate learners showed no subject/object asymmetry in sentences with high frequency words, providing further evidence that processing efficiency is a key factor when considering possible L1 effects in L2 processing. Study 4 demonstrated that advanced L2 learners benefited from animacy cues in on-line processing, with the difficulty associated with object relative sentences and the L1 effect evident in sentences with animate head nouns neutralized in sentences with inanimate head nouns. The findings indicate that L2 learners may rely on lexical information as an alternative to syntactic knowledge in some cases. Finally, Study 5 compared processing performance on full or reduced relative clauses to examine both the influence of L1 syntactic properties and L1 structural frequency biases on L2 processing outcomes. Although the influence of frequency information was not evident, the results suggested that the availability of an overt relative marker in the L1 affected L2 processing outcomes. Overall, the results provide some support for the view that L1 background influences the processing of complex syntactic structures in the L2, a finding consistent with Juffs (2005) but contrary to Clahsen et al. (Clahsen & Felser, 2006b). However, the effect is sensitive to a range of factors, which appears to support the claim by the latter that L2 learners may rely more on lexical-semantic information than L1 individuals.

Fluent sentence comprehension requires the automatic application of grammatical principles, in combination with other kinds of information, to a linear input string. The latter can vary greatly in complexity, and it has been observed that structures that involve non-adjacent relationships (non-local dependencies) cause particular processing difficulties, for even fluent readers. This thesis focuses on the potential role that L1 transfer plays in processing non-local dependencies in the L2. Although L1 transfer has been demonstrated in a variety of L2 domains (Juffs, 2005), the degree to which L1 syntactic properties influence the L2 in real-time processing remains an open question (Clahsen & Felser, 2006b). A better understanding of L1 influence on L2 processing has important implications for emerging models of L2 sentence processing and SLA theory in general. This thesis examines L1 effects on the processing of L2 English relative clauses. It builds on established models of L1 relative clause processing (e.g., Gibson, 1998) and focuses on the asymmetry observed in the processing of subject versus object relative clauses. Research has shown that L1 individuals find object relative clauses more difficult to process than their subject counterparts (King & Just, 1991), and off-line L2 research suggests that this asymmetry might hold for L2 processing as well (Izumi, 2003; Kanno, 2007). This thesis will examine the asymmetry on-line and investigate the role that L1 background plays in on-line performance, both alone and in combination with other processing factors. The main data are on-line performance by three groups of advanced-level learners of L2 English from Japan, China, and Vietnam. The three L1s differ from English to varying degrees in relative clause formation, as reflected in head direction, branching direction and the presence of an overt relative marker. Vietnamese shares all three properties with English and Japanese none, leading to the prediction that the Japanese learners will have the greatest difficulty, as evident in the largest subject/object asymmetry in processing times. Evidence for the effect of L1 syntactic properties on L2 processing will be sought in a set of studies that compare processing outcomes for these learners across key individual difference factors in L2 processing, working memory capacity, lexical processing efficiency, and proficiency. The effect of non-structural information, in the form of animacy contrasts and frequency effects, on L2 syntactic processing across the L1 groups will also be examined. By systematically examining group differences across these key factors, the degree and nature of potential L1 influence on the processing of these non-local dependencies can be better assessed. Three groups of advanced-level L2 English learners from China, Japan, and Vietnam, a group of intermediate-level learners in Japan, and native English controls participated in the data collection. Participants were first tested on a battery of individual difference measures that established language proficiency and general processing skill for individual participants and groups. On-line reading data of relative clause structures were then collected and reported in a set of five studies. Study 1 examined reading when the target structures contained high frequency content words, which minimized word recognition demands. Advanced L2 learners took longer to read object relative clauses, and the difference was the greatest for the Japanese group. Study 2 revealed that the subject/object asymmetry and L1 influence evident in Study 1 disappeared when word recognition was effortful, as in sentences with low frequency words, suggesting that L1 syntactic influence may only be evident when lexical processing is relatively automatic. Study 3 examined the effect of proficiency differences on processing outcomes by comparing performance by Intermediate and Advanced Japanese learners. The Intermediate learners showed no subject/object asymmetry in sentences with high frequency words, providing further evidence that processing efficiency is a key factor when considering possible L1 effects in L2 processing. Study 4 demonstrated that advanced L2 learners benefited from animacy cues in on-line processing, with the difficulty associated with object relative sentences and the L1 effect evident in sentences with animate head nouns neutralized in sentences with inanimate head nouns. The findings indicate that L2 learners may rely on lexical information as an alternative to syntactic knowledge in some cases. Finally, Study 5 compared processing performance on full or reduced relative clauses to examine both the influence of L1 syntactic properties and L1 structural frequency biases on L2 processing outcomes. Although the influence of frequency information was not evident, the results suggested that the availability of an overt relative marker in the L1 affected L2 processing outcomes. Overall, the results provide some support for the view that L1 background influences the processing of complex syntactic structures in the L2, a finding consistent with Juffs (2005) but contrary to Clahsen et al. (Clahsen & Felser, 2006b). However, the effect is sensitive to a range of factors, which appears to support the claim by the latter that L2 learners may rely more on lexical-semantic information than L1 individuals.

Fluent sentence comprehension requires the automatic application of grammatical principles, in combination with other kinds of information, to a linear input string. The latter can vary greatly in complexity, and it has been observed that structures that involve non-adjacent relationships (non-local dependencies) cause particular processing difficulties, for even fluent readers. This thesis focuses on the potential role that L1 transfer plays in processing non-local dependencies in the L2. Although L1 transfer has been demonstrated in a variety of L2 domains (Juffs, 2005), the degree to which L1 syntactic properties influence the L2 in real-time processing remains an open question (Clahsen & Felser, 2006b). A better understanding of L1 influence on L2 processing has important implications for emerging models of L2 sentence processing and SLA theory in general. This thesis examines L1 effects on the processing of L2 English relative clauses. It builds on established models of L1 relative clause processing (e.g., Gibson, 1998) and focuses on the asymmetry observed in the processing of subject versus object relative clauses. Research has shown that L1 individuals find object relative clauses more difficult to process than their subject counterparts (King & Just, 1991), and off-line L2 research suggests that this asymmetry might hold for L2 processing as well (Izumi, 2003; Kanno, 2007). This thesis will examine the asymmetry on-line and investigate the role that L1 background plays in on-line performance, both alone and in combination with other processing factors. The main data are on-line performance by three groups of advanced-level learners of L2 English from Japan, China, and Vietnam. The three L1s differ from English to varying degrees in relative clause formation, as reflected in head direction, branching direction and the presence of an overt relative marker. Vietnamese shares all three properties with English and Japanese none, leading to the prediction that the Japanese learners will have the greatest difficulty, as evident in the largest subject/object asymmetry in processing times. Evidence for the effect of L1 syntactic properties on L2 processing will be sought in a set of studies that compare processing outcomes for these learners across key individual difference factors in L2 processing, working memory capacity, lexical processing efficiency, and proficiency. The effect of non-structural information, in the form of animacy contrasts and frequency effects, on L2 syntactic processing across the L1 groups will also be examined. By systematically examining group differences across these key factors, the degree and nature of potential L1 influence on the processing of these non-local dependencies can be better assessed. Three groups of advanced-level L2 English learners from China, Japan, and Vietnam, a group of intermediate-level learners in Japan, and native English controls participated in the data collection. Participants were first tested on a battery of individual difference measures that established language proficiency and general processing skill for individual participants and groups. On-line reading data of relative clause structures were then collected and reported in a set of five studies. Study 1 examined reading when the target structures contained high frequency content words, which minimized word recognition demands. Advanced L2 learners took longer to read object relative clauses, and the difference was the greatest for the Japanese group. Study 2 revealed that the subject/object asymmetry and L1 influence evident in Study 1 disappeared when word recognition was effortful, as in sentences with low frequency words, suggesting that L1 syntactic influence may only be evident when lexical processing is relatively automatic. Study 3 examined the effect of proficiency differences on processing outcomes by comparing performance by Intermediate and Advanced Japanese learners. The Intermediate learners showed no subject/object asymmetry in sentences with high frequency words, providing further evidence that processing efficiency is a key factor when considering possible L1 effects in L2 processing. Study 4 demonstrated that advanced L2 learners benefited from animacy cues in on-line processing, with the difficulty associated with object relative sentences and the L1 effect evident in sentences with animate head nouns neutralized in sentences with inanimate head nouns. The findings indicate that L2 learners may rely on lexical information as an alternative to syntactic knowledge in some cases. Finally, Study 5 compared processing performance on full or reduced relative clauses to examine both the influence of L1 syntactic properties and L1 structural frequency biases on L2 processing outcomes. Although the influence of frequency information was not evident, the results suggested that the availability of an overt relative marker in the L1 affected L2 processing outcomes. Overall, the results provide some support for the view that L1 background influences the processing of complex syntactic structures in the L2, a finding consistent with Juffs (2005) but contrary to Clahsen et al. (Clahsen & Felser, 2006b). However, the effect is sensitive to a range of factors, which appears to support the claim by the latter that L2 learners may rely more on lexical-semantic information than L1 individuals.

Fluent sentence comprehension requires the automatic application of grammatical principles, in combination with other kinds of information, to a linear input string. The latter can vary greatly in complexity, and it has been observed that structures that involve non-adjacent relationships (non-local dependencies) cause particular processing difficulties, for even fluent readers. This thesis focuses on the potential role that L1 transfer plays in processing non-local dependencies in the L2. Although L1 transfer has been demonstrated in a variety of L2 domains (Juffs, 2005), the degree to which L1 syntactic properties influence the L2 in real-time processing remains an open question (Clahsen & Felser, 2006b). A better understanding of L1 influence on L2 processing has important implications for emerging models of L2 sentence processing and SLA theory in general. This thesis examines L1 effects on the processing of L2 English relative clauses. It builds on established models of L1 relative clause processing (e.g., Gibson, 1998) and focuses on the asymmetry observed in the processing of subject versus object relative clauses. Research has shown that L1 individuals find object relative clauses more difficult to process than their subject counterparts (King & Just, 1991), and off-line L2 research suggests that this asymmetry might hold for L2 processing as well (Izumi, 2003; Kanno, 2007). This thesis will examine the asymmetry on-line and investigate the role that L1 background plays in on-line performance, both alone and in combination with other processing factors. The main data are on-line performance by three groups of advanced-level learners of L2 English from Japan, China, and Vietnam. The three L1s differ from English to varying degrees in relative clause formation, as reflected in head direction, branching direction and the presence of an overt relative marker. Vietnamese shares all three properties with English and Japanese none, leading to the prediction that the Japanese learners will have the greatest difficulty, as evident in the largest subject/object asymmetry in processing times. Evidence for the effect of L1 syntactic properties on L2 processing will be sought in a set of studies that compare processing outcomes for these learners across key individual difference factors in L2 processing, working memory capacity, lexical processing efficiency, and proficiency. The effect of non-structural information, in the form of animacy contrasts and frequency effects, on L2 syntactic processing across the L1 groups will also be examined. By systematically examining group differences across these key factors, the degree and nature of potential L1 influence on the processing of these non-local dependencies can be better assessed. Three groups of advanced-level L2 English learners from China, Japan, and Vietnam, a group of intermediate-level learners in Japan, and native English controls participated in the data collection. Participants were first tested on a battery of individual difference measures that established language proficiency and general processing skill for individual participants and groups. On-line reading data of relative clause structures were then collected and reported in a set of five studies. Study 1 examined reading when the target structures contained high frequency content words, which minimized word recognition demands. Advanced L2 learners took longer to read object relative clauses, and the difference was the greatest for the Japanese group. Study 2 revealed that the subject/object asymmetry and L1 influence evident in Study 1 disappeared when word recognition was effortful, as in sentences with low frequency words, suggesting that L1 syntactic influence may only be evident when lexical processing is relatively automatic. Study 3 examined the effect of proficiency differences on processing outcomes by comparing performance by Intermediate and Advanced Japanese learners. The Intermediate learners showed no subject/object asymmetry in sentences with high frequency words, providing further evidence that processing efficiency is a key factor when considering possible L1 effects in L2 processing. Study 4 demonstrated that advanced L2 learners benefited from animacy cues in on-line processing, with the difficulty associated with object relative sentences and the L1 effect evident in sentences with animate head nouns neutralized in sentences with inanimate head nouns. The findings indicate that L2 learners may rely on lexical information as an alternative to syntactic knowledge in some cases. Finally, Study 5 compared processing performance on full or reduced relative clauses to examine both the influence of L1 syntactic properties and L1 structural frequency biases on L2 processing outcomes. Although the influence of frequency information was not evident, the results suggested that the availability of an overt relative marker in the L1 affected L2 processing outcomes. Overall, the results provide some support for the view that L1 background influences the processing of complex syntactic structures in the L2, a finding consistent with Juffs (2005) but contrary to Clahsen et al. (Clahsen & Felser, 2006b). However, the effect is sensitive to a range of factors, which appears to support the claim by the latter that L2 learners may rely more on lexical-semantic information than L1 individuals.

Thesis (M.A.)--Indiana University, 2008. / Title from screen (viewed on June 3, 2009). Department of English, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Ulla Connor, William V. Rozycki, Thomas A. Upton. Includes vita. Includes bibliographical references (leaves 95-99).

This study investigates how seven Chinese sentence-final particles (SFP le, ne1, ma, ne2, ba1, ba2 and a; hereafter SFP) and their features are represented in English speakers’ L2 Chinese. In this research, SFPs are analysed as heads instantiating different positions in the CP domain (Paul 2009, 2014, 2015), which are head-final, and in particular, they are considered to carry semantic, syntactic and discourse features. As there is no SFP in English, the features on Chinese SFPs are realised by a variety of syntactic means. Through a proficiency test and six experimental tasks, data from 76 participants (including 18 Chinese native speakers, 20 low-intermediate learners, 20 high-intermediate learners and 18 advanced learners) were collected. Results show that English-speaking L2 learners can easily establish the basic syntactic structure of Chinese SFPs and successfully acquire the features attached to SFPs ma, ba1 and a. However, they have significant difficulty in acquiring the features attached to SFPs le, ne1, ne2 and ba2. In general, syntactic features on Chinese SFPs are intact in L2 grammars, whereas semantic features (i.e. syntax-semantics interfaces) are very vulnerable. In addition, it is found that not all discourse features (syntax-discourse interfaces) are problematic. Findings indicate that both L1 grammar (i.e. L1 transfer) and L2 input (frequency, saliency and complexity) play important roles in affecting learners’ acquisition of the features attached to Chinese SFPs. In particular, learners seem to transfer all feature sets from their L1 English. Semantic features that have been transferred from their L1 English but that are neither confirmed nor disconfirmed by the Chinese input have become dormant in the L2 Chinese, which complements the Dormant Feature Hypothesis (Yuan 2014). Furthermore, the homomorphous SFPs which exhibit a ‘one-to-many’ form-meaning connection are believed to complicate learners’ recognition and acquisition of relevant features on SFPs. It is also demonstrated that the mapping of a feature across CP domains (i.e. from a two-CP structure to a one-CP structure) can be problematic and difficult. The discourse feature needs to be reassembled in L2 grammars, which advances the arguments of the Feature Reassembly Hypothesis (Lardiere 2008, 2009a,b).

abstract: Osteosarcoma is the most common bone cancer in children and adolescents. Patients with metastatic osteosarcoma are typically refractory to treatment. Numerous lines of evidence suggest that cytotoxic T-lymphocytes (CTL) limit the development of metastatic osteosarcoma. I have investigated the role of Programmed Death Receptor-1 (PD-1) in limiting the efficacy of immune mediated control of metastatic osteosarcoma. I show that human metastatic, but not primary, osteosarcoma tumors express the ligand for PD-1 (PD-L1) and that tumor infiltrating CTL express PD-1, suggesting this pathway may limit CTL control of metastatic osteosarcoma in patients. PD-L1 is also expressed on the K7M2 osteosarcoma tumor cell line that establishes metastases in mice, and PD-1 is expressed on tumor infiltrating CTL during disease progression. Blockade of PD-1/PD-L1 interactions dramatically improves the function of osteosarcoma-reactive CTL in vitro and in vivo, and results in decreased tumor burden and increased survival in the K7M2 mouse model of metastatic osteosarcoma. My results suggest that blockade of PD-1/PD-L1 interactions in patients with metastatic osteosarcoma should be pursued as a therapeutic strategy. However, PD-1/PD-L1 blockade treated mice still succumb to disease due to selection of PD-L1 mAb resistant tumor cells via up-regulation of other co-inhibitory T cell receptors. Combinational α-CTLA-4 and α-PD-L1 blockade treated mice were able to completely eradicate metastatic osteosarcoma, and generate immunity to disease. These results suggest that blockade of PD-1/PD-L1 interactions in patients with metastatic osteosarcoma, although improves survival, may lead to tumor resistance, requiring combinational immunotherapies to combat and eradicate disease. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2015

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-09-04T20:38:58Z No. of bitstreams: 1 DanieleDeSouzaMarinhoDoNascimento_DISSERT.pdf: 2192295 bytes, checksum: 73b11671b4d2ac4a205f4fba79f5180a (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-09-06T19:07:23Z (GMT) No. of bitstreams: 1 DanieleDeSouzaMarinhoDoNascimento_DISSERT.pdf: 2192295 bytes, checksum: 73b11671b4d2ac4a205f4fba79f5180a (MD5) / Made available in DSpace on 2017-09-06T19:07:23Z (GMT). No. of bitstreams: 1 DanieleDeSouzaMarinhoDoNascimento_DISSERT.pdf: 2192295 bytes, checksum: 73b11671b4d2ac4a205f4fba79f5180a (MD5) Previous issue date: 2017-06-22 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A obesidade ? considerada um importante problema de sa?de p?blica, sendo um fator de risco para v?rias doen?as cr?nicas como doen?as cardiovasculares, hipertens?o, diabetes e outras. A Baccharis trimera (Less.) DC, conhecida popularmente como carqueja, ? uma planta medicinal utilizada na medicina tradicional em v?rias partes do Brasil. Para tal, infus?es, decoc??es e tinturas de suas folhas s?o produzidas e utilizadas para o tratamento da obesidade, diabetes, assim como diur?ticos, agentes digestivos, antiinflamat?rios, dentre outros. Neste trabalho, com intuito de respaldar o potencial medicinal da carqueja, extratos de folhas de Baccharis trimera foram obtidos, caracterizados qu?mica e fitoquimicamente e avaliados com rela??o ? sua atividade antioxidante e antiadipog?nica. Foram obtidos tr?s extratos: aquoso (AE), decoco (AE-D) e metan?lico (ME); a partir destes, foram realizados seis diferentes ensaios antioxidantes in vitro: ensaio do radical super?xido e hidroxila, poder redutor, capacidade antioxidante total e quela??o dos ?ons ferro e cobre. Bem como, foi avaliada sua poss?vel atividade antiadipog?nica com os testes de oil red O, glicerol livre e mensura??o de fatores de transcri??o adipog?nicos C/EBP?, C/EBP? e PPAR?. Na caracteriza??o fitoqu?mica, revelou-se a presen?a de flavonoides (?cido clorog?nico e apigenina) e compostos fen?licos nos extratos AE e AE-D. Quanto a atividade antioxidante, verificou-se uma atividade dose-dependente. Em rela??o ? atividade antiadipog?nica, a Baccharis trimera inibiu significantemente tanto a diferencia??o e ac?mulo de gordura nos adip?citos pelo MDA, quanto a express?o dos fatores de transcri??o C/EBP?, C/EBP? e PPAR?, durante a adipog?nese todas em rela??o dose-dependente. Este trabalho sugere que Baccharis trimera possui ?tima atividade antioxidante, prevenindo o estresse oxidativo, podendo contribuir para a diminui??o da adipog?nese, al?m de possuir ?tima atividade antiadipog?nica. Este foi o primeiro trabalho que demonstrou o potencial efeito de extratos de Baccharis trimera na diferencia??o de adip?citos 3T3-L1 em adip?citos. / Obesity is considered an important public health problem, being a risk factor for several chronic diseases such as cardiovascular diseases, hypertension, diabetes and other. Baccharis trimera (Less.) DC (carqueja) is a medicinal plant used in traditional medicine in various parts of Brazil. Infusions, decoctions and tinctures of its leaves are produced and used for the treatment of obesity and diabetes, and also as diuretics, digestive agents, anti-inflammatory drugs, among others. In this work, in order to support the medicinal potential of carqueja, extracts of Baccharis trimera leaves were obtained, characterized chemically and phytochemically and evaluated in relation to their antioxidant and antiadipogenic activities. Three extracts were obtained: aqueous (AE), decoco (AE-D) and methanolic (ME); From these, six different in vitro antioxidant assays were performed: superoxide and hydroxyl radical assay, reducing power, total antioxidant capacity and chelation of iron and copper ions. As well, its possible antiadipogenic activity was evaluated with oil red O, free glycerol and measurement of adipogenic transcription factors C / EBP?, C / EBP? and PPAR?. Phytochemical characterization revealed the presence of flavonoids (chlorogenic acid and apigenin) and phenolic compounds in extracts AE and AE-D. As for the antioxidant activity, a dose-dependent activity was observed. Regarding antiadipogenic activity, Baccharis trimera significantly inhibited the differentiation and accumulation of fat in adipocytes by MDA in a dose-dependent relationship and significantly reduced the expression of the transcription factors C / EBP?, C / EBP? and PPAR?, during adipogenesis in a relation dose-dependent too. This work suggests that Baccharis trimera has an excellent antioxidant activity, preventing oxidative stress, and may contribute to the decrease of adipogenesis, besides having an excellent antiadipogenic activity. This was the first work that demonstrated the potential effect of Baccharis trimera extracts on the differentiation of 3T3-L1 adipocytes into adipocytes.

El presente estudio versa sobre el análisis de errores de un grupo de suecos aprendientes de español como segunda lengua. El análisis trata de explorar si el tiempo de estadía en el país de la lengua meta, juega un papel significativo en la frecuencia de errores lingüísticos. Para este efecto, se analizaron las transcripciones de un ejercicio narrativo hecho por los aprendientes, para luego determinar los errores gramaticales y léxicos más frecuentes. Además de los aprendientes también se constó de un grupo de nativos monolingües de español quienes también hicieron el mismo ejercicio narrativo. El método de análisis en este trabajo es de tipo cuantitativo y como herramienta de análisis se utilizaron el t-test y el test correlacional Pearson. El t-test ayuda a determinar si la diferencia entre los dos grupos es suficientemente grande y significativa. El test correlacional Pearson ayuda a determinar la correlación entre el total de errores y el tiempo de estadía. Las preguntas de investigación responden a dos preguntas: las diferencias entre nativos y aprendientes en lo que se refiere a los errores lingüísticos que comente y el papel que desempeña el tiempo de estadía en la frecuencia de errores cometidos. Seguido a estas preguntas se plantean dos hipótesis: los aprendientes cometen más errores que los nativos, y el tiempo de estadía juega un papel importante en este comportamiento en el sentido de que mientras más tiempo se lleva en el ámbito L2 menos errores lingüísticos se deben cometer. Los resultados del análisis indican que el tiempo de estadía no presenta mayor efecto en la frecuencia de errores que los aprendientes cometen.

Cette thèse est articulée autour de deux facettes de l’étude des équations auxdérivées partielles. Dans une première partie, on étudie la stabilité des solutionspériodiques pour des lois de conservation. On démontre d’abord la stabilité asymptotiquedans L1 des solutions périodiques de lois de conservation scalaires et inhomogènes.On montre ensuite un résultat de stabilité structurelle des roll-waves. Plusprécisément, on montre que les solutions périodiques d’un système hyperbolique sansviscosité sont limites des solutions du problème avec viscosité, quand le terme deviscosité tend vers 0. Dans une deuxième partie, on s’intéresse à un système d’équationsaux dérivées partielles issu de la biologie : le modèle de Patlak-Keller-Segelen dimension 2 ; il décrit les phénomènes de chimiotactisme. Pour ce modèle, onconstruit un schéma de type volume fini, ce qui permet d’approcher la solution touten gardant certaines propriétés du système : positivité, conservation de la masse,estimation d’énergie. / This thesis is organized around two aspects of the study of partial differentialequations. In a first part, we study the stability of periodic solutions for conservationlaws. First, we prove asymptotic L1-stability of periodic solutions of scalarinhomogeneous conservation laws. Then, we show a result on structural stability ofroll-waves. More precisely, we prove that periodic solutions of a hyperbolic systemwithout viscosity are the limits of the solutions of the problem with viscosity, as theviscous term tends to 0. In a second part, we study a system of partial differentialequations derived from biology: the model of Patlak-Keller-Segel in dimension 2, describingthe phenomena of chemotaxis. For this model, we construct a finite-volumescheme, which approaches the solution while keeping some properties of the system:positivity, conservation of mass, energy estimate.