This dissertation deals with the issue of smoking. Its practical part specifies several objectives, one of them being finding out whether the prevalence of smoking within the population is dependant upon the attained qualifications. Establishing the respondents{\crq} views on the harm of smoking is another goal. The approach of the respondents towards a smoking ban in restaurants is demonstrated in this dissertation, so is their awareness of quitting-smoking methods. The decision to give up is also affected by the knowledge and understanding of all the risks bred by smoking, therefore determining the level of the respondents{\crq} awareness of these health risks is another aim of this dissertation. A quantitative research was used in my dissertation to obtain results. A questionnaire of 18 questions was answered by 211 addressed respondents being in the age group of 45-60 years of age. Analysing the outcome it can be said that the prevalence of smoking within the population is not dependant upon the attained qualifications. Nicotine dependence is referred to as a disease therefore the risk of developing an addiction is the same for everyone irrespective of the qualifications accomplished. Nonetheless, the outcome manifests the fact that smokers with lower qualifications smoke a higher amount of cigarettes a day as opposed to smokers with higher qualifications. Considering the results it can be, furthermore, assumed that smokers with lower qualifications are more tolerant towards the nicotine addiction and they feel less unpleasant in a smoky environment. Moreover, their favour for a smoking ban in restaurants and at working places is lower. At the same time, their awareness of possibilities to treat their nicotine addiction as well as of the negative health effects of smoking proved to be lower. Most smokers would like to quit their nicotine addiction (app. 50% lower- qualified individuals and 72% university and college graduates). However, only a very small percentage would seek any professional help when giving up smoking. The unwillingness to treat the nicotine addiction with the help of an expert reflects the unawareness of the severity of such addiction by the smokers themselves. Therefore, the prevention aimed at non-smokers is as important as effecting smokers so that they become more aware of the seriousness and vast consequences of their addiction.

Nesta pesquisa, composta por três ensaios, buscamos resultados que contribuam com informações sobre três temas relevantes na área de finanças: o impacto de normas internacionais na qualidade da informação contábil; quantidades e estrutura de dependência entre commodities alimentares e o petróleo; e o estudo da relação entre o retorno e a volatilidade implícita de um fundo do mercado do petróleo. Em particular, trabalhamos para sugerir novas estratégias, com formas alternativas para a solução de problemas relacionados a esses temas. No primeiro ensaio, adotamos uma estratégia empírica, em duas etapas, para avaliar o impacto das normas internacionais de contabilidade (IFRS) na qualidade da informação contábil. Na primeira, construímos grupos de controle, por meio de um pareamento por escore de propensão, com a intenção de selecionar um contrafactual para avaliar o impacto das IFRS no Brasil. A busca e o uso de contrafactuais para a avaliação de normas contábeis ainda não foi explorado de forma adequada nos estudos específicos para o país. Na segunda etapa, estimamos modelos de painel para medidas de qualidade da informação. Os resultados apontaram para o efeito positivo da adoção de normas sobre a qualidade da informação contábil para as empresas avaliadas. No ensaio número dois, calculamos medidas de dependência entre as principais commodities alimentares e o petróleo, e testamos a existência de neutralidade entre esses mercados. Além disso, investigamos mudanças na estrutura de dependência ao passar de um período de estabilidade para um de crises. Para tanto, adotamos um procedimento que envolveu a estimação de valores para as marginais com modelos ARMA-GARCH, estimação de cópulas não paramétricas, via kernel, e cálculos aproximados de medidas de dependência. Também construímos intervalos de confi-ança para essas medidas de dependência utilizando técnicas de block bootstrap. De posse dos resultados dos intervalos refutarmos, de maneira geral, a hipótese de neutralidade entre esses mercados. Outro ponto a se destacar foi a mudança da estrutura de dependência observada ao passar de um período de estabilidade para um período de crises. Finalmente, no terceiro ensaio, realizamos a avaliação da relação entre o retorno e a volatilidade de um fundo representativo do mercado de petróleo e seu respectivo índice de volatilidade esperada. Neste ensaio, em particular, nos dedicamos na análise da não linearidade e assimetria entre os diferentes quantis de volatilidade. Com base nos resultados de regressões quantílicas e na análise não paramétrica do método B-splines, encontramos resultados que apontam para respostas de retornos negativos mais intensos do que positivos, em especial nos extremos da distribuição. E ainda, que existe uma relação no formato de "S" inclinado entre as variáveis, em forma de “U” para retornos ne-gativos e “U” invertido para retornos positivos, nos quantis (0.05, 0.90 e 0.95) de volatilidade. / In this research, composed of three essays, we seek results that contribute to information on three relevant topics in the finance: the impact of international standards on the accounting information quality; Quantities and structure of dependence between grain commodities and oil; and the study of the relationship between return-volatility of an oil investment fund. In particular, we work to suggest new strategies, with alternative ways to solve problems related to these themes. In the first essay, we adopted a two-stage empirical strategy to assess the impact of international accounting standards (IFRS) on the accounting information quality. In the first stage, we constructed control groups, through a pairing by propensity score macthing, with the intention of selecting a counterfactual to evaluate the impact of IFRS in Brazil. The search and use of counterfactuals for the evaluation of accounting standards has not yet been adequately explored in the specific s tudies f or B razil. In the second s tep, we e stimate panel models for the main measures of information quality. The results pointed to the positive effect of adopting standards on the quality of accounting information for the companies evaluated. In essay number two, we calculated measures of dependence between the main grain commodities and oil, and we tested the existence of neutrality between these markets. In addition, we investigate changes in the dependency structure when moving from a period of stability to one of crisis. For that, we adopted a procedure that involved the estimation of values for the marginal ones with ARMA-GARCH models, estimation of non-parametric copulas, via kernel, and approximate calculations of dependence measures. We also constructed confidence intervals for these dependency measures using blockbootstrap techniques. With the results of the intervals, we refute the hypothesis of neutrality between these markets, in general. Another point to highlight was the change in the structure of dependence observed when changing from one period of stability to another of crises. Finally, in the third essay, we evaluated the relationship between the return and the volatility of a fund representative of the oil market and its expected volatility index. In this essay, in particular, we focus on the analysis of nonlinearity and asymmetry between the different quantile of volatility. Based on the results of quantile regressions and the non-parametric analysis of the B-splines method, we find results that point to responses of negative returns that are more intense than positive, especially at the extremes of the distribution. Also, there is an "S"-shaped relationship between the variables, in the form of "U"-shaped for negative returns and "U"-shaped inverted for positive returns, for the quantis (0.05, 0.90 and 0.95) of volatility.

C-Kit est généralement considéré comme un récepteur à tyrosine kinase et comme un proto-oncogène, dont la surexpression et la mutation conduisent à une progression tumorale médiée par son activité kinase. En clinique, les traitements ciblant l’activité kinase de c-Kit, comme l’Imatinib (Gleevec), ont été largement utilisés pour traiter les patients atteints de maladies liées à c-Kit. Alors que le rôle de c-Kit comme proto-oncogène ne fait aucun doute, certaines études et analyses de bases de données diffèrent avec l’idée d’un rôle pro-tumoral de c-Kit, laissant penser à un rôle différent de c-Kit dans le cancer. Ici, nous montrons que c-Kit appartient à la famille des récepteurs à dépendance, de la même façon que d’autres récepteurs de la famille des tyrosine kinases tel que MET, RET et TrkC. En absence de son ligand Stem Cell Factor (SCF), au lieu de rester inactif, c-Kit déclenche l’apoptose, qui peut être renforcée par l’invalidation de son activité kinase. En parallèle, nous montrons que c-Kit est capable de se lier à la caspase-9 et de l’activer. De plus, à la manière d’autres récepteurs à dépendance, c-Kit est aussi clivé par des protéases de type caspase sur son résidu acide aspartique D816, qui est nécessaire à son activité pro-apoptotique. La mutation du site D816 inhibe l’interaction entre c-kit et la caspase-9 et invalide l’activité pro-apoptotique de c-Kit. De façon intéressante, la mutation D816 est l’une des mutations les plus communes de ce récepteur dans la plupart des cancers liés à c-Kit, et cette mutation favorise la résistance au traitement Gleevec. Nous montrons aussi que la surexpression de c-Kit invalidé pour son activité kinase est capable d’inhiber la croissance tumorale dans des modèles animaux, alors que la mutation du site D816 empêche son effet suppresseur de tumeur. En outre, nous avons développé un outil permettant de bloquer l’interaction entre SCF et c-Kit, déclenchant l’activité pro-apoptotique de c-Kit dans les cancers positifs pour ce récepteur. En utilisant l’activité pro-apoptotique de c-Kit, en combinaison avec des inhibiteurs de kinases comme le Gleevec, nous proposons une nouvelle stratégie thérapeutique. En conclusion, nous démontrons que c-Kit est un membre de la famille des récepteurs à dépendance, présentant une activité pro-apoptotique, et pouvant être utilisé comme un outil alternatif dans le cadre d’un traitement contre le cancer / C-Kit has been generally considered as a receptor tyrosine kinase and a proto-oncogene, whose upregulation and mutation lead to tumor progression through its kinase activity. Clinically, drugs targeting the kinase activity of c-Kit, such as Imatinib (Gleevec), have been wildly used to treat patients with c-Kit related diseases. While the role of c-Kit as a proto-oncogene is of no doubt, some research reports and database analysis do not fit well the tumor promoting role of c-Kit, indicating a possible different role of c-Kit in cancer. Here, we show that c-Kit belongs to the dependence receptor family, similarly to other receptor tyrosine kinases such as MET, RET and TrkC. In the absent of its ligand SCF (stem cell factor), instead of staying inactive, c-Kit triggers apoptosis, which can be enhanced by silencing its kinase activity. Besides, we have shown that c-Kit is able to bind and activate caspase-9. Moreover, similarly to other dependence receptors, c-Kit is also cleaved by caspases-like protease at aspartic acid residue D816, which is crucial for its pro-apoptotic activity. The mutation of D816 site inhibits the c-Kit/caspase-9 binding and silences the pro-apoptotic activity of c-Kit. Of interest, c-Kit D816 mutation is one of the most common mutation of this receptor in many c-Kit related cancers and it promotes resistance against Gleevec treatment. We also show that overexpression of kinase mutated c-Kit is able to inhibit tumor growth in animal models, while the mutation of D816 site impairs the tumor suppressing activity. Furthermore, we develop a tool to block the SCF/c-Kit interaction, which unleashes the pro-apoptotic activity of c-Kit in cancers expressing this receptor. By using the pro-apoptotic activity of c-Kit, in combination with kinase inhibitors like Gleevec, we propose a novel therapeutic strategy. In conclusion, we demonstrate that c-Kit is a member of dependence receptor family, harboring intrinsic pro-apoptotic activity, which can be used as an alternative tool in cancer treatment

Cette thèse présente des contributions à la modélisation multivariée des queues de distribution. Nous introduisons une nouvelle modélisation des probabilités de queue jointes d'une distribution multivariée avec des marges Pareto. Ce modèle est inspiré de celui de Wadsworth et Tawn (2013). Une nouvelle variation régulière multivariée non-standard de coefficient une fonction à deux variables est introduite, permettant de généraliser deux approches de modélisation respectivement proposées par Ramos et Ledford (2009)et Wadsworth et Tawn (2013). En nous appuyant sur cette modélisation nous proposons une nouvelle classe de modèles semi-paramétriques pour l'extrapolation multivariée selon des trajectoires couvrant tout le premier quadrant positif. Nous considérons aussi des modèles paramétriques construits grâce à une mesure non-négative satisfaisant une contrainte qui généralise celle de Ramos et Ledford (2009). Ces nouveaux modèles sont flexibles et conviennent tant pour les situations de dépendance que d'indépendance asymptotique. / This PhD thesis presents contributions to the modelling of multivariate extremevalues. We introduce a new tail model for multivariate distribution with Pareto margins. This model is inspired from the Wadsworth and Tawn (2013) one. A new non-standard multivariate regular variation with index equals to a function of two variables is thus introduced to generalize both modeling approaches proposedby Ramos and Ledford (2009) and Wadsworth and Tawn (2013), respectively. Building on this new approach we propose a new class of non-parametric models allowing multivariate extrapolation along trajectories covering the entire first positive quadrant. Similarly we consider parametric models built with a non-negative measure satisfying a constraint that generalizes the Ramos and Ledford (2009) one. These new models are flexible and valid in both situations of dependence or asymptotic independence.

The main subject of this thesis is a change point detection in stationary vector autoregressions. Various test statistics are proposed for the retrospective break point detection in the parameters of such models, in particular, the derivation of their asymptotic distribution under the null hypothesis of no change. Testing procedures are based on the maximum like- lihood principle and are derived under normality, nevertheless the asymptotic results are valid for broader class of distributions and involve also the models with certain form of dependence. Simulation studies document the quality of the results.

The thesis is made up of a number of studies involving long-range dependence (LRD), that is, a slow power-law decay in the temporal correlation of stochastic models. Such a phenomenon has been frequently observed in practice. The models with LRD often yield non-standard probabilistic and statistical results. The thesis includes in particular the following topics: Multivariate limit theorems. We consider a vector made of stationary sequences, some components of which have LRD, while the others do not. We show that the joint scaling limits of the vector exhibit an asymptotic independence property. Non-central limit theorems. We introduce new classes of stationary models with LRD through Volterra-type nonlinear filters of white noise. The scaling limits of the sum lead to a rich class of non-Gaussian stochastic processes defined by multiple stochastic integrals. Limit theorems for quadratic forms. We consider continuous-time quadratic forms involving continuous-time linear processes with LRD. We show that the scaling limit of such quadratic forms depends on both the strength of LRD and the decaying rate of the quadratic coefficient. Behavior of the generalized Rosenblatt process. The generalized Rosenblatt process arises from scaling limits under LRD. We study the behavior of this process as its two critical parameters approach the boundaries of the defining region. Inference using self-normalization and resampling. We introduce a procedure called "self-normalized block sampling" for the inference of the mean of stationary time series. It provides a unified approach to time series with or without LRD, as well as with or without heavy tails. The asymptotic validity of the procedure is established.

Adaptation has increasingly come to be recognised as an urgent and necessary response to climate change. The ability of a system to carryout adaptation is dependent on its adaptive capacity. To date, the majority of research relating to adaptation has focused on the objective and material determinants of a system's capacity to adapt to severe and extreme weather impacts. Whereas the role that subjective factors, such as people's perceptions, beliefs and values play in that same process, has received comparatively less attention. Despite being a global phenomenon, climate change is being experienced and responded to in local places. More than just physical locations, places are often imbued with meaning by the people associated with them. This thesis argues that these meanings have implications for the ways in which people adapt, or fail to adapt, to climate change impacts. It uses the concept 'sense of place', as a means of capturing this place meaning and as a lens for exploring adaptive behaviours in three low-income urban communities in the Dominican Republic. In particular it examines the specific roles of residents' place attachment, dependence and identity in motivating and constraining adaptive behaviours. Based on qualitative research with ethnographic underpinnings, the thesis shows that the urban poor sense of place is shaped by interconnected relationships between residents and; their homes, the physical and social aspects of their communities and a range of non-community actors. These relationships are shaped by physical and social interactions with and within places, but also through the discursive construction of the locations and the inhabitants of them in public opinion. Residents continuously seek out ways to enhance their sense of place, at times as an improvement in the built environment as a means of preventing or ameliorating environmental threats and events. However, often it is enhancement, in an aesthetic sense, which is envisaged as being of equal and sometimes greater importance. Although aesthetic improvements sometimes have the resultant impact of enabling adaptation, this tends to be incidental, rather than purposeful. Despite the importance placed by the urban poor on their sense of place, these subjective determinants and adaptation in the urban environment, remain unrecognised as well as absent from local institutional and policy radars. Overall the research suggests the need for a more comprehensive approach to understanding adaptive capacities. It requires an approach which continues to measure the objective determinants but which also recognises the role of people's relationships to places in converting or failing to convert objective capacity into climate change action and in dictating the type activities that are valued and prioritised by urban poor residents themselves.

abstract: Achieving high performance is a crucial issue in modern organizations including public, for-profit, and nonprofit even though there is no consensus about what performance means. How to obtain resources is important for boosting organizational performance. Furthermore, resource acquisition capacity is closely associated with the survival of modern nonprofit organizations. Resource Dependence Theory (RDT) notes that dependence on critical resources influences diverse actions and behavior of organizations. The study examines the relationship among Resource Dependence Patterns (RDPs), organizational behavior, and organizational performance in nonprofit organizations. This study introduces five dimensions of RDPs (the appearance of the resource inflow): resource dependency, resource diversity, resource uncertainty, resource abundance, and resource competitiveness. This research suggests that a nonprofit's RDPs affect its behavior, performance, and survival. A main research question can be phrased as: How are RDPs of nonprofit organizations related to organizational behavior and performance? Data are mainly gathered from financial officers, managers, and directors in the nonprofit sector. Multivariate data analytic techniques including factor analysis, multiple regression analysis, and path analysis are used for testing the proposed hypotheses and answering the research question. The empirical findings reveal that the Resource Dependence Patterns directly or indirectly affect organizational behavior and performance in nonprofit organizations. Resource dependency (where resources come from) has substantive and wide impacts on the overall nonprofits' behavior and structures. High dependency on government funding (high resource dependency) is positively associated with organizational hierarchy and frequent goal changes; on the other hand, it has a negative effect on participatory decision making. This study suggests that goal clarity has the strongest direct impact on nonprofits' performance. Clear organizational goals increase the likelihood that nonprofits show a higher level of performance. The paths of both resource diversity and resource competitiveness also have direct impacts on organizational performance and their impacts are statistically robust. Path analysis verifies the fact that the other three RDP variables account for organizational performance via organizational behavior variables (indirect causality on performance). This study of RDPs, behavior, and performance contributes practically to the effective management of nonprofit organizations and contributes to consolidating and expanding Resource Dependence Theory (RDT). In addition, the information about resource dependence patterns will help funders including governments, foundations, and individual donors to understand the fiscal environment that an organization faces. / Dissertation/Thesis / Ph.D. Public Administration 2011

Made available in DSpace on 2016-08-15T20:31:25Z (GMT). No. of bitstreams: 1 BrunaKGA_DISSERT.pdf: 10130604 bytes, checksum: 442a6ff2ea41c2bd6e2b8cd41175fcb4 (MD5) Previous issue date: 2015-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The collared peccary (Pecari tajacu) belongs to the family Tayassuidae, have four digits on the forelimb and three in the pelvic limb, presents elongated snout and a short tail; stands out for having an odoriferous gland on the back that continuously secretes a whitish liquid. This secretion can be considered a chemical signal. Chemical signals intra-specific action are called phero mones acting in physiology and development of individuals or directly in their behavior. In several mammalian species, the function of the scent gland development is regulated by gonadal hormones. This study s objective was to describe the morphology of scent gland and assess if its structure is influenced by testosterone. For this we used twelve collared peccary from the Centro de Multiplicação de Animais Silvestres of the Universidade Federal Rural do Semi -Árido, divided into groups: group I (newborns peccary), group II (adult collared peccaries), group III (adult castrated collared peccaries), group IV (castrated collared peccaries and treated with testosterone). All the procedures used were approved by the UFERSA s Ethics in Animals Use Commission (pr ocess number: 26/2013). The collared peccary were sacrificed, the scent glands were dissected and the length and width dimensions were measured. Posteriorly glands fragments were subjected to histological processing, histomorphometric analyzes were performed, the proliferative kinetics of glandular cells were also evaluated through the AgNORs count method. The peccaries had a scent gland with oval shape and showed in the center a central duct. Two regions were distinct and differentiated by the color. The cranial portion was clear (sebaceous glands) and the caudal portion was dark (sweat gland). The newborn animal scent gland showed histological differences when compared to adult animal s glands and after castration the gland underwent a process of involution which can be partially reversed with hormone replacement. The sebaceous portion of the scent gland was the most affected by castration. The results of histomorphometric data and AgNOR count showed that the sebaceous portion of the collared peccary scent gland is under strong influence of testosterone, since the decrease in testosterone levels in the blood resulting from castration, generated low proliferative activity and changes significant in their secretory units / O cateto (Pecari tajacu) pertence à família Tayassuidae, possuem quatro dígitos no membro torácico e três no membro pélvico, apresentam um focinho alongado e uma cauda curta; se destacam por possuir uma glândula odorífera no dorso, que secreta continuamente um líquido esbranquiçado. Tal secreção pode ser considerada um sinal químico . Sinais químicos de ação intra-específicos são denominados feromônios, agindo na fisiologia e desenvolvimento dos indivíduos ou diretamente em seu comportamento. Em várias espécies de mamíferos, a função do desenvolvimento da glândula de cheiro é regulada por hormônios gonadais. O objetivo desse trabalho foi descrever a morfologia da glândula de cheiro e avaliar se sua estrutura é influenciada pela testosterona. Para isso foram utilizados doz e catetos machos provenientes do Centro de Multiplicação de Animais Silvestres da Universidade Federal Rural do Semi-Árido e dividido em quatro grupos de três animais: grupo I (catetos recém -nascidos), grupo II (catetos adultos intactos), grupo III (cateto s adultos castrados), grupo IV (catetos adultos castrados e tratados com testosterona). Todos os procedimentos foram realizados de acordo com o Comitê de Ética no Uso de Animais da Universidade Federal Rural do Semi-Árido (nº 26/2013). Os catetos foram sacrificados, as glândulas de cheiro foram dissecadas e as dimensões de comprimento e largura foram mensuradas. Posteriormente fragmentos das glândulas foram submetidos ao processa mento histológico, foram realizadas análises histomorfométricas, bem como se avaliou a atividade proliferativa das células glandulares através do método de contagem de regiões organizadoras de nucléolo argirofílicas. A glândula de cheiro era oval e exibia no centro um ducto principal. Duas regiões eram nítidas e diferenciavam-se pela coloração. A porção cranial era clara (glândula sebácea) e a porção caudal era escura (glândula sudorípara). A glândula de cheiro de animais recém -nascidos apresentou diferenças histológicas quando comparado à glândula de animais adultos e após a castração a glândula sofreu um processo de involução que pode ser parcialmente revertido com a reposição hormonal. A porção sebácea da glândula de cheiro foi a mais afetada pela castração. Os resultados dos dados histomorfométricos e da contagem de AgNORs mostraram que a porção sebácea da glândula de cheiro do cateto está sobre forte influência da testosterona, uma vez que a diminuição dos níveis de testosterona no sangue decorrentes da castração, geraram diminuição da atividade proliferativa e alterações significativas em suas unidades secretoras

The objectives of the research undertaken have been to investigate the properties of semiconductor lasers operating at around 1.3 mum. The aim of the investigation is to suggest modifications which give rise to improved operating characteristics especially in the high temperature (approaching 85 °C) range. The investigation can be divided into 2 sections: a theoretical approach and an experimental section. The theoretical study examined the performance of compressively strained InGaAsP/InP multiple quantum-well lasers emitting at 1.3 mum in order to investigate the important factors and trends in the threshold current density and differential gain with strain, well width and well number. Structures with a fixed compressive strain of 1% but variable well width, and also with a fixed well width but variable strain from 0% to 1.4% have been considered. It has been found that there is little benefit to having compressive strains greater than 1 %. For structures with a fixed 1% compressive strain and unstrained barriers, an optimum structure for lowest threshold current density and a high differential gain has been found to consist of six 35 A quantum-wells. In addition, compensated strain (CS) structures with compressive wells and tensile barriers have been examined. It is shown that the conduction band offset can be significantly increased and the valence band offset reduced in such structures, to give band-offset ratios comparable with aluminium based 1.3 mum devices. The gain calculations performed suggest that there is little degradation in the threshold carrier density or differential gain due to these alterations in the band offsets; and hence a better laser performance is expected due to a reduction in thermal leakage currents due to the improved electron confinement. The experimental study concentrates on looking at certain key design parameters to investigate their effect on the laser performance. These design parameters range from the number of quantum-wells to the device length. The experimental study confirms the conclusions drawn in the theoretical investigation that the optimum structure for a 1.3 mum InGaAsP laser for low threshold current, high efficiency and high characteristic temperature operation consists of six 1% compressively strained 50 A quantum-wells in a device of medium length (approx. 450 mum). The inclusion of a high reflection coating on one facet provides further improvement in the device performance, but increases the production cost dramatically. Also investigated in the experimental section is the effect of changing the device material from InGaAsP to InGaA1As. The results discussed do not offer firm evidence of any improvement in the device characteristics in switching from a P-based to an Al-based structure. This is mainly due to the added complication of switching to a RWG structure from a BH structure. Another explanation for the relatively poor performance of InGaAsP 1.3 mum lasers has been examined. That is leakage of the carriers out of the well region. Evidence of a leakage current has been seen primarily in devices with a low number of quantum-wells. A novel measurement technique has been demonstrated, which should prove useful for obtaining a numerical value for the leakage current in semiconductor lasers. The results presented suggest that leakage current is not significant for a 9 well device until operating at temperatures above around 373 K. This is supported by evidence supplied by the spontaneous emission spectra.