Made available in DSpace on 2014-06-12T15:49:18Z (GMT). No. of bitstreams: 2 arquivo127_1.pdf: 5135920 bytes, checksum: 7ce3b83de0b3c66828d195aba8d141ea (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2007 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A família Araceae pertence às monocotiledôneas estimando-se que inclua cerca de 3.500 espécies e 105 gêneros, com ampla distribuição mundial, exceto na Antártida. O gênero Anthurium Schott concentra o maior número de espécies (ca. de 800), seguido de Philodendron Schott que inclui cerca de 400 espécies, no qual concentra-se a maioria das análises deste trabalho. A presente avaliação inclui análises citogenéticas de 40 espécies da família Araceae, enquanto 19 espécies foram amostradas pela primeira vez através de marcadores moleculares (DNA Amplification Fingerprinting DAF). Coletas incluíram áreas de floresta amazônica (estados de Manaus e Pará) e de Mata Atlântica incluindo quatro estados brasileiros (Alagoas, Bahia, Minas Gerais e Pernambuco). Para 32 espécies tratam-se das primeiras informações citológicas. O número cromossômico 2n=32 foi observado em 21 espécies, seguido por 2n=34 em oito espécies. O número 2n=30 foi observado apenas em quatro espécies, porém, o mais incomum foi o número 2n=46, observado numa única espécie. Quanto à morfologia cromossômica, observou-se uma conservação entre as populações da maioria das espécies estudadas, com predominância de pares submetacêntricos e metacêntricos, com poucos acrocêntricos. Com base nas atuais análises e em dados da literatura, a disploidia parece ser o principal mecanismo citoevolutivo, sobretudo em Philodendron, o qual pode ser considerado como um gênero paleopoliplóide. Em 13 espécies, a coloração com fluorocromos, antes ou após o tratamento para bandeamento C, evidenciou variações qualitativas (CMA3/DAPI e CB-CMA3 Palavras-chave: Araceae, Cromossomos, Disploidia, Hibridização, Fluorocromos, DNA Amplification Fingerprinting, UPGMA. /DAPI, respectivamente), quantitativas e de posição da heterocromatina constitutiva, revelando tratar-se de um importante marcador carioevolutivo. A impregnação argêntica revelou a variação da quantidade de nucléolos em quatro espécies, que apresentaram no máximo quatro, seis ou oito nucléolos. O presente trabalho apresenta também os primeiro dados com técnicas de bandeamento para Philodendron e Anthurium (e para a família Araceae), assim como hibridização in situ fluorescente (FISH) com sonda de DNAr 45S para A. gracile. Polimorfismos revelados pelo marcador DAF e analisados pelo método de UPGMA permitiram uma distinção entre os 16 taxa analisados, com níveis significativos de polimorfismo. Dendrogramas gerados por esta metodologia foram consistentes com informações taxonômicas e dados populacionais. As relações intra, interespecíficas e intergenéricas (Philodendron e Dieffenbachia) são discutidas, revelando possíveis tendências evolutivas

Made available in DSpace on 2014-06-12T18:03:22Z (GMT). No. of bitstreams: 2 arquivo3701_1.pdf: 924546 bytes, checksum: 6684872417d2bf8760fc0c94e37a5e14 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2008 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O gênero Philodendron (Araceae) apresenta destacada importância não apenas devido a seu contingente populacional, mas também pela ampla utilização ornamental, devido à beleza e diversidade de formas e cores de suas folhagens. Conta com aproximadamente 600 espécies já registradas, distribuindo-se endemicamente nas Américas e apresentando grande diversidade na região Amazônica na Mata Atlântica, onde os exemplares do presente estudo foram coletados. Marcadores DAF (DNA Amplification Fingerprinting) são úteis na geração de polimorfismos especialmente em nível intra e interespecífico, sendo informativos em análises de diversidade genética. No presente trabalhos 37 primers foram avaliados em uma amostragem inicial incluindo seis espécies de Philodendron (dois acessos de P. megalophyllum, e um acesso de cada espécie: P. imbe, P. ornatum, P. pedatum e P. sphalerum), bem como em dois táxons testados como grupo externo: Dieffenbachia elegans e Monstera dubia. A partir desta seleção, 12 iniciadores decâmeros foram selecionados como mais informativos. Em uma avaliação mais abrangente usando-se os primers selecionados, foram avaliados membros de 26 acessos de 18 espécies de Philodendron, comparados a representantes de Dieffenbachia (2 spp.) Monstera (3 spp.) e Scaphispatha (1 spp.). Todas as espécies de Philodendron estudadas pertencem ao subgênero Philodendron, com exceção de P. goeldi e P. solimoesense do sbg. Meconostigma. No total 1108 bandas polimórficas foram incluídas na matriz de dados para a geração do dendrograma usando o método de Neighbour-Joining (bootstrap de 1000 replicações, programa MEGA 4). O dendrograma foi associado a números cromossômicos das espécies analisadas, permitindo uma avaliação comparativa de tendências cariotípicas à luz dos grupamentos gerados pelos marcadores DAF. Espécies com 2n=32 agruparam-se no dendrograma, enquanto espécies com 2n=30 e 34 uniram-se em um clado separado. Considerações adicionais sobre as relações reveladas no presente trabalho com relação ao sbg. Philodendron são também discutidas

Made available in DSpace on 2014-06-12T18:06:46Z (GMT). No. of bitstreams: 2 arquivo6319_1.pdf: 813959 bytes, checksum: ac0fdfeef1e3a6adeb19be879b540aad (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2004 / O Brasil ocupa mundialmente a terceira posição na produção de mamona (Ricinus communis L.). Embora existam muitos estudos moleculares voltados às proteínas expressas nas sementes, não existem até o momento análises com marcadores moleculares avaliando a diversidade genética dessa espécie. O presente trabalho estudou a variabilidade genética de 16 genótipos de populações subespontâneas de mamona adquiridas através de coletas em quatro diferentes localidades de Pernambuco e em duas outras regiões do Brasil, comparando-as a acessos cultivados de quatro outros países. Para isso a metodologia de DAF (DNA amplification Fingerprinting) foi utilizada, permitindo a geração de em média 14 bandas por primer, sendo 10,72 polimórficas, a partir de 11 primers. Para a construção da matriz de dados 143 bandas foram analisadas, perfazendo 2.288 caracteres. A análise filogenética de máxima parsimônia revelou uma diversidade genética significativa, entre genótipos da mesma população, considerando os diferentes pontos de coleta no Brasil, bem como comparativamente com acessos cultivados no exterior. O estudo confirma a variabilidade sugerida pelos melhoristas para as populações subespontâneas de mamona e demonstra a eficiência deste tipo de marcador para estudos de caracterização de germoplasma desta importante cultura vegetal.

We allow for heterogeneity in investors' ability to borrow from collateral in a Kiyotaki-Moore style macro model. We calibrate the model to match the quintiles of the distribution of leverage ratios of US non-financial firms. We show that financial amplification of the model with heterogeneous investors can be orders of magnitude higher, because of more pronounced asset price reactions. / Series: Department of Economics Working Paper Series

When an intense laser beam interacts with matter, the Kerr nonlinearity results in self-focusing. Above the critical intensity, self-focusing dominates pulse spreading through diffraction leading to continuous pulse narrowing and thus an increase of the laser peak intensity. Collapse is prevented through the fact that peak intensities ultimately reach a level where ionization occurs. The profile of ionized electrons represents a negative lens which balances Kerr nonlinear self-focusing and causes the formation of stable filaments. From filaments radiation is emitted in a cone around the filament which has been termed conical emission. Filament formation happens at non-perturbative intensities where the formalism of perturbative nonlinear optics loses its validity. This opens the question of how the Kerr nonlinearity behaves in the non-perturbative limit and how large the Kerr nonlinear coefficient is. The expression for the Kerr nonlinearity is derived by perturbation theory; the validity of this expression in the non-perturbative limit is questionable. Further, experimentally the Kerr nonlinear index is extracted from measurements of the self-focusing distance as a function of beam intensity which is called the Z-scan method. This method fails at non-perturbative intensities due to the presence of the negative lens coming from the ionized electrons. The effects of the positive focusing and negative self-defocusing lens cannot be separated by the Z-scan method. As a result, not much is known about the Kerr nonlinearity in the regime of non-perturbative nonlinear optics. The purpose of this thesis is twofold. First, recently it has been discovered that conical emission can be utilized as a broadband and very efficient amplification mechanism in the far infrared. The process has been dubbed Kerr instability amplification. The difference between conical emission and Kerr instability amplification is that they take place in two different regimes of the nonlinear interaction. Whereas conical emission grows out of noise and therewith only takes place once the pump pulse has been substantially restructured due to filamentation, Kerr instability amplification is seeded with a second pulse and therewith occurs long before filamentation happens. The theory developed for Kerr instability amplification has been developed based on a stability analysis of the scalar wave equation. This analysis has shown that with pump lasers in the 1-2 μm range amplification of infrared radiation up to the 10’s of μm can be achieved. For amplification over such a wide range it is not adhoc clear to which exent vectorial wave effects can be neglected. The first part of the thesis closes this gap by developing the vectorial theory of vector instability amplification. The second part uses the results derived for Kerr instability amplification to answer the question of how to measure the Kerr nonlinear index in the nonperturbative laser intensity limit. The idea rests on the fact that Kerr instability amplification is maximum for a specific angle between pump and seed beam which varies as a function of laser pump intensity. A relation is derived that connects this angle with the Kerr nonlinear refractive index. As a result, from the maximum angle measured as a function of pump intensity, both magnitude and functional form of the Kerr nonlinear index as a function of laser intensity can be determined.

For many animals, rapid movements place high power demands on underlying muscles. Storage of muscle energy in elastic structures and the subsequent rapid release of that energy can effectively amplify muscle power. Elastic recoil can also confer thermal robustness to performance in behaviors occurring at variable temperatures. Muscle contractile performance tends to decrease at lower temperatures, but elastic recoil is less affected by temperature. Here I examine the impacts of temperature and scale in systems using elastic recoil and I explore possible interactive effects on movement performance. I explored the role that muscle contractile properties play in the differences in performance and thermal robustness between elastic and non-elastic systems by examining muscles from two species of plethodontid salamanders with elastically powered tongue projection and one with non-elastic tongue projection. These salamanders use tongue projection to capture prey and in species with elastic mechanisms, tongue projection is characterized by higher mechanical power output and thermal robustness compared to tongue projection of closely-related genera with non-elastic mechanisms. In vitro and in situ muscle experiments reveal that species differ in their muscle contractile properties, but these patterns do not predict the performance differences between elastic and non-elastic tongue projection. Overall, salamander tongue muscles are like other vertebrate muscles in contractile performance and thermal sensitivity. I conclude that changes in the tongue-projection mechanism, specifically the elaboration of elastic structures, are responsible for high performance and thermal robustness in species with elastic tongue projection. This suggests that the evolution of high-performance and thermally robust elastic-recoil mechanisms can occur via relatively simple changes to morphology, while muscle contractile properties remain relatively unchanged. The efficacy of elastic recoil in the face of changing temperature depends on the mechanical work done by muscle contraction being unaffected by temperature. In vitro stimulation of Cuban tree frog (Osteopilus septentrionalis) plantaris muscles reveals that interactions between force and temperature affect the mechanical work of muscle. At low temperatures (9 – 17°C), muscle work depends on temperature when shortening at any force, and temperature effects are greater at higher forces. At warmer temperatures (13 – 21°C), muscle work depends on temperature when shortening with intermediate and high forces (≥ 30% peak isometric tetanic force). Shortening velocity is most strongly affected by temperature at low temperatures and high forces. Power is also most strongly affected at low temperature intervals but this effect is minimized at intermediate forces. Effects of temperature on muscle force explain these interactions; force production decreases at lower temperatures, increasing the challenge of moving a constant force relative to the muscle’s capacity. These results suggest that animal performance that requires muscles to do work with low forces relative to a muscle’s maximum force production will be robust to temperature changes, and this effect should be true whether muscle acts directly or through elastic-recoil mechanisms and whether force is prescribed (i.e. internal) or variable (i.e. external). Conversely, performance requiring muscles to shorten with relatively large forces is expected to be more sensitive to temperature changes. How muscle work and power scale determines, in part, the scaling of movement performance. Muscle-mass-specific work is predicted to remain constant across a range of scales, assuming geometric similarity, while muscle-mass-specific power is expected to decrease with increasing scale. I tested these predictions by examining muscle morphology and contractile properties of plantaris muscles from frogs ranging in mass from 1.28 to 20.60 g. Scaling of muscle work and power was examined using both linear regression on log10-transformed data (LR) and non-linear regressions on untransformed data (NLR). In LR, muscle-mass-specific work decreased with increasing scale, but this is counteracted by a positive allometry of muscle mass to predict constant movement performance at all scales. These relationships were non-significant in NLR, though scaling with geometric similarity also predicts constant jump performance across scales. Both intrinsic shortening velocity and muscle-mass-specific power were positively allometric in both types of analysis. However, these differences between methods are caused not by large changes in scaling slopes, but by changing levels of statistical significance using corrections for multiple tests. The dependence of these conclusions on the method of regression, largely because of the setting and adjusting of an arbitrary alpha, demonstrates the importance of careful consideration of statistical methods when analyzing patterns of scaling. Nonetheless, scale accounts for little variation in contractile properties over the range of scales examined, indicating that other sources of intraspecific variation may be more important in determining muscle performance and its effects on movement. Elastic recoil used for power amplification is most often found in smaller animals, suggesting that performance in larger animals using less elastic recoil would be affected more by changing temperatures. To examine the interaction between scale and temperature on performance, I recorded jumps from 1-34 g Cuban tree frogs (Osteopilus septentrionalis) at 10, 20, and 30°C and compared jump performance to predictions based on the effects of temperature and scaling on muscle properties. High muscle-mass-specific power requirements from measured jumps indicate that frogs use elastic recoil at all scales to achieve performance that would be impossible using only muscle, and elastic recoil allows small frogs to achieve the same level of performance as large frogs. Performance that is greater at all temperatures than predictions from models using only muscle power could result from some combination of elastic recoil and power directly from muscle. The relative contributions of muscle power and elastic recoil cannot be discerned by examining temperature effects on performance because these effects are predicted to be so similar. Predicted performance from models of elastic recoil is significantly affected by changing temperature at all scales with temperature coefficient (Q10) values similar to predictions for muscle-powered jumping. Measured Q10 values are similar to those from both predictive models and there is no interaction between temperature and scale. Therefore, elastic recoil allows for jump performance that could not be achieved by muscle power alone at all temperatures and scales, but performance predictions from elastic recoil are not more thermally robust than predictions for muscle-powered jumping.

Previous research regarding the utility of non-linear frequency compression in hearing aids has revealed conflicting results for speech recognition, marked by high individual variability. The aims of the study were to determine the effect of non-linear frequency compression on aided speech recognition in noise and listening effort using a dual-task test paradigm and to determine if listener variables of hearing loss slope, working memory capacity, and age predicted performance with non-linear frequency compression. 17 older adults with symmetrical sensorineural hearing loss were tested in the sound field using hearing aids. Speech recognition in noise and listening effort were measured by adapting the Revised Speech in Noise Test into recognition/recall dual-task paradigm. On average, speech recognition in noise performance significantly improved with the use of non-linear frequency compression. Individuals with steeply sloping hearing loss received more recognition benefit. Recall performance also significantly improved at the group level with non-linear frequency compression revealing reduced listening effort. Older participants within the study cohort received less recall benefit than the younger participants. Evidence supports individualized selection of non-linear frequency compression, with results suggesting benefits in speech recognition for individuals with steeply sloping hearing losses and in listening effort for younger individuals.

Real-time or quantitative PCR (qPCR) is an innovative method used to determine the amount of amplifiable DNA in a biological sample. Typically, a fluorescent dye is introduced during thermal cycling, causing a change in fluorescent output as the double-stranded DNA (dsDNA) product accumulates. Both TaqMan® and Plexor HY System methods detect PCR inhibition through the monitoring of internal control sequences. Alternatively, SYBR®Green and Plexor detect inhibition through melt curve effects. Previous work using SYBR®Green intercalation has demonstrated that inhibitors can affect melt curves differently depending on their structure and mode of action. Inhibitors that bind DNA can cause melt curve shifts while those primarily affecting Taq polymerase do not. Unlike SYBR®Green, Plexor dyes are fluorescently linked to a modified base, 5'-methylisocytosine (iso-dC), adjacent to the 5' end of the dsDNA. This produces minimal interference in dsDNA structure making it an ideal procedure for measuring these effects. In this study, inhibition of qPCR was evaluated by observing the effects of various inhibitor concentrations and amplicon lengths on DNA amplification.

In identifying the importance of early identification of hearing loss in children, very little attention has been given to how advanced FM technology may improve outcomes. Distance, noise and reverberation remain considerable challenges for individuals using hearing aids, more so in really young children. The aim of this present research was to evaluate and explore the benefits of advanced integrated FM amplification technology with pre-school hearing aided children. The research was of a longitudinal prospective design, including both quantitative and qualitative analysis of FM technology use in pre-school hearing aided participants. All participants were provided with the latest hearing aid and integrated FM amplification technology suited to their hearing loss. An initial study was conducted to validate the 'AutoConnect' feature on the FM technology provided to participants. The manufacturers of the 'AutoConnect' purport the feature removes the need for verifying FM technology 'transparency'. The results indicated the feature did work with the hearing aid and FM combinations used in this study. Three further studies were conducted. The first of these evaluated FM device use via daily diaries, datalogging and questionnaires. Five of the seven families were able to establish regular FM use in a range of environments and settings. The environments where the FM was used most frequently were the home, car, nursery, shopping and outdoors. Listening evaluation measures with FM technology demonstrated the greatest improvements were in noise and at distance. Parents rated the FM technology highly, with all parents reporting 5 out of 5 for 'easy to operate'. Significant improvements in language development were noticed for the three children whose language development was identified as 'at risk' at the start of the study. The second of the three studies qualitatively explored the views and experiences of parents and carers on their use of FM technology. Eight weekly diaries, seven completed by parents and one completed by pre-school nursery staff of one of the participants, were collected throughout the study period. Seven semi structured interviews were conducted with parents at the end of study participation. Altogether eight cases were included for analysis with seven including both diaries and interviews and one case including diary only. Thematic content analysis sought to acknowledge parents and carers as the experts and place them in the centre of knowledge generation. Six main themes were identified: access to speech, listening, communication, wellbeing, engagement/ownership and practicalities of FM use. More detailed sub-themes were generated under the main six headings. Overall the analysis highlighted the potential benefits, barriers and challenges to pre-school use of FM technology. The final study used the language environment analysis (LENA) system to compare differences in language environment with and without FM use. The findings indicated the language environment of the children in this study was comparable to their hearing peers. The acoustic environment results suggested the largest portion of children's day was spent in environments where speech was at a distance or in background noise. The thesis concludes by discussing the findings and implications of this study and highlighting areas for future research. The current study provides a unique contribution to the existing literature and together with future research can be integral to the provision of FM technology as standard for pre-school hearing aided children.

The alkylation of pyrimidyl aldehyde by diisopropylzinc has received immense attention over the last decade. This is mainly because the reaction which was discovered by Soai and coworkers is capable of achieving a homochiral product from an essentially achiral precursor. The strong amplification of the enantiomeric excess occurs because of a transition state complex which is responsible for autocatalysis. Clarifying the structural nature of the organometallic species involved in the reaction is vital for understanding the mechanism of the chiral amplification process. Known mechanistic details are patchy and based on studies that address molecular level details by NMR, computational chemistry, calorimetric and kinetic studies. The studies reported in this thesis for the first time directly addressed the nature of the intermediate by structural analysis with X-ray Absorption Fine Structure (XAFS) Spectroscopy at the Zn K-edge. These measurements provide bond distances, local coordination numbers and the geometry of ligands in the local environment around the Zn centres. First, the molecular level origin of the solvent dependencies in the asymmetric amplification by the Soai process is elucidated. A rationale for the behaviour of dialkylzinc compounds in polar and non-polar solvents is reported. Structural causes for often observed chirality depletion in polar solvents are elucidated. Further studies then examined the nature of the products formed by the reaction of various chiral ligands and dialkylzinc compounds. Different chiral ligands are examined and the complex structure was determined.Finally, first results of in situ studies of the reaction progress in continuous flow channel cells are reported.