本文探討我國金控公司在不同子公司組合以及考量雙引擎策略下，對各種績效指標以及風險指標影響。資料取樣我國2002年至2013年間15家金控公司之季度資料，在考量過去關於金融機構及金控公司多角化經營與子公司組合有關文獻後，選取適當控制變數搭配「以銀行搭配壽險為主」之虛擬變數進行分析，並以虛擬變數及三種集中率進行穩健度測試及並觀察不同面向影響；接著於雙引擎分析當中，試圖發展用於測量雙引擎策略程度之兩種平衡率變數，並且考量交叉項的效果，分別加入模型中進行分析分析。研究結果分為複迴歸、追蹤資料模型，以及關於落後一期自變數對當期應變數之延伸分析。 　　在複迴歸及追蹤資料模型進行橫斷面及縱斷面之實證研究結果指出，金控投入的資源越分散(資產多角化程度越高)或是越集中(集中率越高)皆未能顯著提昇金控績效或降低風險；然而若考慮雙引擎策略時，則能顯著提昇EPS、P/B Ratio或RBC，同時，不論資產面或營收面建立的平衡率變數，皆可觀察出金控旗下兩大子公司在收益傾向越相等的情況下，具顯著改善金控整體獲利能力、投資人評價或是降低破產風險的情況。 　　本研究對於各個金控公司前一期的自變數對當期應變數進行延伸分析，實證結果支持了本研究對於投入到產出存在時間落差的假設，亦即以資產平衡率而言，較屬於以資源「投入」概念觀察雙引擎策略程度，因此需要隔一段時間才能展現對於績效與風險的影響；而收益平衡率則偏向以當期「產出」的概念觀察雙引擎變數，此時用於衡量下一期之績效指標將會傾向不顯著，但對於風險方面則傾向能夠顯著降低破產風險。 / This study investigates the relationship of different subsidiary combination and dual-engine strategies on financial holding companies’ performance and risk. Using quarterly data for 15financial holding companies（FHCs）in the R.O.C for the period 2002Q1–2013Q4 and controlling for the size, size growth, equity ratio and diversification. In order to analysis the issue, we choose “the top-two subsidiaries are bank and life insurance” as a dummy variables, asset and revenue balance ratio as dual-engine variables. Also, the paper introduces several relevant variables to implement the robust tests. These relevant variables are “the FHC has subsidiary of life insurance”, three concentration ratios and two interaction variables. Our empirical finding can be divided into three parts: multiple regression, panel data and one-period lagged data analysis. 　　In multiple regression and panel data, we find evidence that both higher diversification and concentration in subsidiary resource have an ambiguities relation for the performance and risk of financial holding companies. However, considering dual-engine strategies can significantly improve the EPS, P/B Ratio and RBC in empirical results. Also, both asset and revenue balance ratios have significant effect to improve the earning power, the valuation of investors and the insolvency risk. 　　This paper also use the one time lagged data to conduct the extension study. The findings support the assumption of ours that FHCs exist time-lag between input and output. The asset balance ratio is more like the input concept and the revenue balance ratio is rather more like the output concept when we discuss the dual-engine strategies. In other words, there need more time to show the impact of performance and risk indicators when we use the asset balance ratio. However, output variable has insignificant relation to the performance indicators and significant effect to the risk indicator when we use the revenue balance ratio.

Identifying and hiring the highest performers is essential for organizations to remain competitive. Research has provided effective guidelines for this but important aspects of these evidence-based processes have yet to gain acceptance among practitioners. The general aim of this thesis was to help narrowing the gap between research and practice concerning personnel selection decisions. The first study compared the validity estimates of general mental ability (GMA) and the five factor model of personality traits as predictors of job performance, finding that, when the recently developed indirect correction for range restriction was applied, GMA was an even stronger predictor of job performance than previously found, while the predictive validity of the personality traits remained at similar levels. The approach used for data collection and combination is crucial to forming an overall assessment of applicants for selection decisions and has a great impact on the validity of the decision. The second study compared the financial outcomes of applying a mechanical or clinical approach to combining predictor scores. The results showed that the mechanical approach can result in a substantial increase in overall utility. The third study examined the potential influences that practitioners’ cognitive decision-making style, accountability for the assessment process, and responsibility for the selection decision had on their hiring approach preferences. The results showed that practitioners scoring high on intuitive decision-making style preferred a clinical hiring approach, while the contextual aspects did not impact practitioners’ preferences. While more research may be needed on practitioner preferences for a particular approach, the overall results of this thesis support and strengthen the predictive validity of GMA and personality traits, and indicate that the mechanical approach to data combination provides increased utility for organizations. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript.</p>

The thesis describes development and application of coupled resonant coil sensors, which is of growing interest for remote monitoring applications. An interrogation technique, which improves the accuracy and interrogation range of coupled resonant coil sensors, is introduced. The method uses time-domain gating to produce measurements that are dominated by the response of the sensor coil and are immune to surrounding object interference. For application in structural health monitoring a low cost embeddable coupled coil sensor, which is able to monitor the corrosion potential of reinforcement steel is presented. Results of an accelerated corrosion test using the sensor indicate that corrosion potential can be monitored with a resolution less than 10 mV and a sensitivity of 0.76 kHz/mV. The last part describes a coupled-coil pH sensor based on pH electrode potential measurement. A linear response over a 4 to 10 pH dynamic range and 50 kHz/pH sensitivity are achieved with a 0.1 pH resolution and 30 s response time.

In 1972, professor Grigore Moisil, the most famous Romanian academician for Mathematics, said about Combinatorics, that it is “an opportunity of a renewed gladness”, because “each problem in the domain asks for its solving, an expenditure without any economy of the human intelligence”. More, the research methods, used in Combinatorics, are different from a problem to the other! This is the explanation for the existence of my actual paper, in which I propose to teach Combinatorics, using selected problems. MS classification: 05A05, 97D50.

Das Harnblasenkarzinom (BCa) stellt in Deutschland die vierthäufigste Tumorneuerkrankung und die zehnthäufigste krebsbedingte Todesursache bei Männern dar. Nichtmuskelinvasive BCa werden organerhaltend aus der Blasenwand entfernt und zur Rezidiv- und Progressionsprophylaxe mittels intravesikaler Chemo- oder Immuntherapien behandelt. Trotz dieser adjuvanten Therapien, die mit starken Nebenwirkungen verbunden sein können, ist nur eine bedingte Minimierung des Rezidivrisikos möglich. Besonders im fortgeschrittenen Stadium weisen Harnblasenkarzinome eine schlechte Prognose auf. Obwohl das BCa eine chemosensitive Erkrankung darstellt, wird das Ansprechen auf lokale oder systemische Chemotherapien häufig durch auftretende Resistenzmechanismen limitiert. Daher stehen sowohl die Verbesserung konventioneller Chemotherapien als auch die Suche nach neuartigen Behandlungsstrategien im Fokus der experimentellen BCa-Forschung. Die Apoptose, eine Form des programmierten Zelltodes, ist ein essenzieller, streng regulierter biologischer Prozess, welcher der Aufrechterhaltung der Gewebshomöostase und der gezielten, entzündungsfreien Eliminierung geschädigter Zellen dient. Fehlregulationen in den Apoptosesignalwegen stellen ein zentrales Ereignis in der Tumorgenese dar und tragen außerdem zur Entstehung von Chemo- und Radiotherapieresistenzen bei. Eine wichtige Rolle in der Apoptoseregulation spielen die Mitglieder der BCL2- und der Inhibitor of Apoptosis Protein (IAP)-Familien, deren wichtigste antiapoptotische Vertreter BCL2, BCL-XL, XIAP und Survivin häufig in Tumoren, einschließlich des BCa, überexprimiert sind. Unter Verwendung von small interfering RNAs (siRNAs), synthetischen Nukleinsäurekonstrukten zur selektiven Geninhibition, wurde im Rahmen der Arbeit in vitro und in vivo untersucht, ob die Hemmung der Apoptoseinhibitoren BCL2, BCL-XL, XIAP und Survivin – allein und in Kombination mit Chemotherapie – eine Therapieoption zur Behandlung des BCa darstellen könnte. Da zur Tumorentstehung und -progression eine Vielzahl von genetischen Veränderungen beitragen, erscheint der Angriff eines einzelnen Zielgens unzureichend für eine effektive Tumortherapie. Aufgrund dessen wurde untersucht, ob durch simultane Reduktion der ausgewählten Apoptoseinhibitoren in BCa-Zellen stärkere wachstumsinhibitorische Effekte erzielt werden können. In der vorliegenden Arbeit wurde gezeigt, dass insbesondere die siRNA-vermittelte Hemmung von BCL-XL und Survivin in den BCa-Zelllinien EJ28 und J82 antiproliferative Effekte hervorruft und diese Tumorzellen gegenüber einer nachgeschalteten Chemotherapie mit Mitomycin C oder Cisplatin sensitiviert. Hingegen bewirkte sowohl die transiente als auch die stabile RNAi-induzierte Hemmung von BCL2 und XIAP in den untersuchten BCa-Monolayerzellkulturen, möglicherweise infolge kontinuierlicher Versorgung der Tumorzellen mit Sauerstoff und Nährstoffen, keine Reduktion des Tumorwachstums. Eine gegenüber den Einzelbehandlungen deutliche Verstärkung der antitumoralen und insbesondere der chemosensitivierenden Effekte in den BCa-Zelllinien wurde durch simultane Hemmung von BCL-XL und Survivin erzielt. Beispielsweise stieg der Anteil apoptotischer Zellen von 64 % nach Survivin-siRNA+Cisplatin-Behandlung auf 94 % nach gleichzeitiger BCL-XL+Survivin-Inhibition in Kombination mit Cisplatin. Folglich stellt die simultane Inhibition von BCL-XL und Survivin in Kombination mit Chemotherapeutika eine äußert viel versprechende BCa-Therapieoption dar. Tierexperimentelle Studien belegen die wachstumsinhibitorische Wirkung der Survivin-Reduktion und der kombinierten BCL-XL-siRNA+Chemotherapie-Behandlung, so wurde das Tumorendvolumen im Vergleich zur Kontrollbehandlung um 43 % bzw. um 48 % reduziert.

This thesis, which consists of four chapters, focuses on forecasting in a data-rich environment and related computational issues. Chapter 1, “An embarrassment of riches: Forecasting using large panels” explores the idea of combining forecasts from various indicator models by using Bayesian model averaging (BMA) and compares the predictive performance of BMA with predictive performance of factor models. The combination of these two methods is also implemented, together with a benchmark, a simple autoregressive model. The forecast comparison is conducted in a pseudo out-of-sample framework for three distinct datasets measured at different frequencies. These include monthly and quarterly US datasets consisting of more than 140 predictors, and a quarterly Swedish dataset with 77 possible predictors. The results show that none of the considered methods is uniformly superior and that no method consistently outperforms or underperforms a simple autoregressive process. Chapter 2. “Forecast combination using predictive measures” proposes using out-of-sample predictive likelihood as the basis for BMA and forecast combination. In addition to its intuitive appeal, the use of the predictive likelihood relaxes the need to specify proper priors for the parameters of each model. We show that the forecast weights based on the predictive likelihood have desirable asymptotic properties. And that these weights will have better small sample properties than the traditional in-sample marginal likelihood when uninformative priors are used. In order to calculate the weights for the combined forecast, a number of observations, a hold-out sample, is needed. There is a trade off involved in the size of the hold-out sample. The number of observations available for estimation is reduced, which might have a detrimental effect. On the other hand, as the hold-out sample size increases, the predictive measure becomes more stable and this should improve performance. When there is a true model in the model set, the predictive likelihood will select the true model asymptotically, but the convergence to the true model is slower than for the marginal likelihood. It is this slower convergence, coupled with protection against overfitting, which is the reason the predictive likelihood performs better when the true model is not in the model set. In Chapter 3. “Forecasting GDP with factor models and Bayesian forecast combination” the predictive likelihood approach developed in the previous chapter is applied to forecasting GDP growth. The analysis is performed on quarterly economic dataset from six countries: Canada, Germany, Great Britain, Italy, Japan and United States. The forecast combination technique based on both in-sample and out-of-sample weights is compared to forecasts based on factor models. The traditional point forecast analysis is extended by considering confidence intervals. The results indicate that forecast combinations based on the predictive likelihood weights have better forecasting performance compared with the factor models and forecast combinations based on the traditional in-sample weights. In contrast to common findings, the predictive likelihood does improve upon an autoregressive process for longer horizons. The largest improvement over the in-sample weights is for small values of hold-out sample sizes, which provides protection against structural breaks at the end of the sample period. The potential benefits of model averaging as a tool for extracting the relevant information from a large set of predictor variables come at the cost of considerable computational complexity. To avoid evaluating all the models, several approaches have been developed to simulate from the posterior distributions. Markov chain Monte Carlo methods can be used to directly draw from the model posterior distributions. It is desirable that the chain moves well through the model space and takes draws from regions with high probabilities. Several computationally efficient sampling schemes, either one at a time or in blocks, have been proposed for speeding up convergence. There is a trade-off between local moves, which make use of the current parameter values to propose plausible values for model parameters, and more global transitions, which potentially allow faster exploration of the distribution of interest, but may be much harder to implement efficiently. Local model moves enable use of fast updating schemes, where it is unnecessary to completely reestimate the new, slightly modified, model to obtain an updated solution. The last fourth chapter “Computational efficiency in Bayesian model and variable selection” investigates the possibility of increasing computational efficiency by using alternative algorithms to obtain estimates of model parameters as well as keeping track of their numerical accuracy. Also, various samplers that explore the model space are presented and compared based on the output of the Markov chain. / Diss. Stockholm : Handelshögskolan, 2006

In this study, we have explored the combination of a novel Purine Nucleoside Phosphorylase mediated Gene-Directed Enzyme Prodrug Therapy (PNP-GDEPT) with chemotherapeutics, Taxotere and/or Carboplatin to target prostate and ovarian cancer (PC & OC). PNP converts the prodrug (Fludarabine-phosphate) to a toxic purine, 2-fluoroadenine (2FA) that inhibits RNA/DNA synthesis. Taxotere is active against late stage PC whilst carboplatin is first line therapy for OC. Neither modality is adequately effective. We expect that a combination will target heterogeneity via cytotoxicity to diverse cancer cell populations leading to effective synergies, which may improve efficacy and quality of life. For PC, Synergy between Ad-PNP-GDEPT and Taxotere were assessed in vitro and in vivo. Cell killing effects of combination led to significant synergistic killing of human PC-3 & murine RM1 PC cells accompanied by enhanced apoptosis. A lower individual dose (by up to 8 fold) led to enhanced efficacy. In vivo, the combination regimen given at the suboptimal doses led to reduction in local tumour (PC-3 & RM1) growth in nude and in C57BL/6 mice, respectively. A significant reduction in lung RM1 colony numbers indicated enhanced systemic efficacy. Combination treated mice also displayed significantly improved survival (25 days vs 15 days for control mice). Importantly, the condition of combination treated mice (e.g. weight loss) was better than those given individual treatments. The possible involvement of the immune system in this enhanced effect is under investigation. For OC, three-way synergy between Ad-PNP-GDEPT, Taxotere and carboplatin was effectively demonstrated in SKOV-3 and OVCAR-3 cells. This was significantly greater than bimodal or individual treatments. A 10-50 fold dose reduction of individual treatments was effective when combined, accompanied by enhanced apoptosis. Western-blotting analyses revealed a shift in the expression of anti-apoptotic and proapoptotic proteins upon treatment with various combinations. This is the first demonstration of synergy between these modalities.

[Truncated abstract] Failure to fully reconstitute the immune system is a common clinical problem in HIV patients who were severely immunodeficient before responding to combination antiretroviral therapy (CART). This can manifest as a deficiency in the number or function of CD4+ T-cells and occurs most often in patients who had a nadir CD4+ T-cell count below 100/μl when CART was commenced. Observational studies of large cohorts of HIV patients, such as the D:A:D study, have demonstrated that patients with low CD4+ T-cell counts have increased rates of death compared with patients who have normal CD4+ T-cell counts. Furthermore, individual case studies suggest that impaired recovery of pathogen-specific immune responses during CART is associated with opportunistic infections or disease progression. This thesis addresses possible causes of deficiencies in CD4+ T-cell number or function in HIV patients who were very immunodeficient prior to treatment and are responding (virologically) to CART. Firstly, the role of the thymus in producing naive CD4+ T-cells and the effects of persistent immune activation on the recovery of CD4+ T-cell numbers were assessed in patients with either low or high CD4+ T-cell counts after long-term CART. ... Proportions of antigen presenting cell (APC) subpopulations were examined in HIV patients with low or high CMV-specific CD4+ T-cell responses after long-term CART. HIV patients had significantly lower proportions of plasmacytoid dendritic cells (pDC) than HIV-negative controls. Furthermore, the proportions of pDC were positively correlated with CMV-specific CD4+ T-cell responses in HIV patients. Proportions of myeloid dendritic cells (mDC) were significantly higher in HIV patients than controls, and were also increased in patients with low CMV-specific CD4+ T-cell responses. Proportions of M-DC8+ dendritic cells or CD14+ monocytes did not differ between patients and controls, nor were they associated with CMV-specific CD4+ T-cell responses. Quantitation of cytokine (interferon-α, tumour necrosis factor-α, interleukin (IL) -12, IL-23, IL-15, IL-18 and IL-10) mRNA in unstimulated, purified populations of the APC described above revealed few significant differences between patients with low or high CD4+ T-cell IFN-γ responses to CMV. The only notable difference was the slight elevation of IL-15 mRNA levels in patients compared to controls. Since patients in the high responder group had the highest levels of IL-15 mRNA, this association may reflect the anti-apoptotic properties of IL-15. These studies provide valuable insights into the causes of persistent CD4+ T-cell deficiency and dysfunction in HIV patients on CART and may lead to better monitoring and treatments.

Thesis (MEd)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: This research explored the influence of the rural multi-grade context on the nature of the work of the principal of a rural multi-grade school. I specifically looked at the job description of the school principal as set out in the South African Schools Act (84 of 1996) and how the rural multi-grade context affects the nature of the work of four principals in the Western Cape. The relationship between the interpretation of policy and its implementation has always been complex because policies are open to different interpretations by the implementers thereof. This complex relationship can be observed with the implementation of the South African Schools Act of 1996, with specific reference to articles 16(1), 16A(2) and 16(3), in the South African school community. This disjunction between the policy as formulated by policy makers and the implementation thereof by implementers is often traced to the fact that policy makers do not consider the context of the implementers of the policy properly (Bell & Stevenson, 2006:14-15). In my attempt for a better understanding of this disjunction (and the factors that contribute to it), I found the interpretive qualitative investigation the most suited methodology for this study. In this case, I used the case study as a qualitative research method. According to Patton en Cochan (2002:2), qualitative research is characterised by the goals of the research question, which relates to the understanding of certain aspects of social life and methodologies; therefore, words are generated instead of numbers for data analysis. Merriam (1998:21) defines a qualitative case study in terms of the end product as an intensive, holistic description and analysis of a single case, phenomenon or social unit. By defining and conceptualising rural multi-grade schools, I found that these schools are characterised by (a) remote areas with a sparse population and (b) poverty. Joubert (2009:4) defines rural teaching (read rural multi-grade schools) as teaching in remote areas with a sparse population, such as on farms, far from towns and cities, where learners are not exposed to the luxuries of shopping malls or industries. These environments are characterised by inaccessibility, poor or inadequate infrastructure, poverty and a lack of skills, resources, knowledge and community involvement. I conducted interviews with four principals of rural multi-grade schools. Based on results of the research study, I found that the rural multi-grade context indeed has an effect on the nature of the work of the principal. To assist principals of rural multi-grade schools, I recommend that the national education department review the staff establishments of rural multi-grade schools with regard to teachers and non-teaching staff. Furthermore, the provincial department needs to increase the monetary allocation for rural multi-grade schools by the Western Cape Education Department (WCED). In order to address the lack of support to the principals of rural multi-grade schools, specialists on multi-grade teaching should be appointed to support these schools in terms of curriculum delivery and school management. / AFRIKAANSE OPSOMMING: Hierdie studie het die invloed van die landelike multigraad-agtergrond op die aard van die werk van die hoof van ’n landelike multigraadskool verken. Ek het spesifiek gekyk na die posbeskrywing van die skoolhoof soos verwoord in die Suid-Afrikaanse Skolewet (84 van 1996) en hoe die landelike multigraad-agtergrond die aard van die werk van vier skoolhoofde in die Wes-Kaap beïnvloed. Die verband tussen interpretasie van beleid en die toepassing daarvan was nog altyd ʼn komplekse verhouding omdat beleid oop is vir uiteenlopende interpretasies deur die toepassers daarvan. Hierdie komplekse verhouding kom aan die lig wanneer daar byvoorbeeld gekyk word na die toepassing van die Suid-Afrikaanse Skolewet van 1996 (met spesifieke verwysing na artikels 16(1), 16A(2) en 16(3)) op die Suid-Afrikaanse skoolgemeenskap. Die disjunksie tussen die beleid soos deur ‘beleidmakers’ geformuleer en die toepassing daarvan deur beleidstoepassers of implementeerders van beleid kan dikwels herlei word tot die feit dat beleidmakers nie die agtergrond van beleidstoepassers of implementeerders van die beleid na behore in ag neem nie (Bell & Stevenson, 2006:14-15). In my poging om dié disjunksie (en die faktore wat daartoe aanleiding gee) beter te verstaan, het ek bevind dat die interpretatiewe kwalitatiewe ondersoek die geskikste metodologie vir hierdie studie sou wees. In hierdie geval het ek gebruik gemaak van die gevallestudie as kwalitatiewe navorsingsmetode. Kwalitatiewe navorsing word gekenmerk deur die doelstellings van die navorsingsvraag, wat verband hou met die begrip van sekere aspekte van die maatskaplike lewe en die metodes, wat woorde in plaas van getalle genereer vir data-analise (Patton & Cochan, 2002:2). Merriam (1998:21) definieer ʼn kwalitatiewe gevallestudie met betrekking tot die eindproduk as ʼn intensiewe, holistiese beskrywing en analise van ʼn enkele geval, fenomeen of maatskaplike eenheid. Met die definiëring en konseptualisering van landelike multigraadskole het ek tot die gevolgtrekking gekom dat hierdie skole gekenmerk word deur twee pertinente kenmerke: (a) dit is afgeleë met ylbevolkte omgewings en (b) armoede. Joubert (2009:4) omskryf landelike onderrig (lees landelike multigraadskole) as onderrig wat meestal in afgeleë en ylbevolkte omgewings soos op plase, gewoonlik ver van hoofroetes, dorpe en stede plaasvind, waar leerders nie aan luukshede soos inkopiesentrums of nywerhede blootgestel word nie. Hierdie omgewings word gekenmerk deur ontoeganklikheid, swak infrastruktuur, armoede en gebrekkige vaardighede, bronne, kennis en gemeenskapsbetrokkenheid. Onderhoude is met hoofde van vier landelike multigraadskole gevoer. Op grond van die navorsingresultate het ek bevind dat die landelike multigraad-agtergrond wel die aard van die skoolhoof se werk beïnvloed. Ek beveel dus onder andere aan dat die provinsiale onderwysdepartement die diensstate van landelike multigraadskole hersien wat betref onderwysers en niedoserende personeel asook dat die monetêre toekenning van landelike multigraadskole deur die Wes-Kaapse Onderwysdepartement (WKOD) verhoog word. Verder bevel ek aan dat bekwame distriksamptenare aangestel word om die skoolhoof van ʼn landelike multigraadskool ten opsigte van die bestuur van die skool en die onderwysers ten opsigte van kurrikulumlewering te ondersteun.

Made available in DSpace on 2014-12-17T15:47:49Z (GMT). No. of bitstreams: 1 DiogoFO.pdf: 866073 bytes, checksum: bf59c2597aef9b7382b7e14bd4914265 (MD5) Previous issue date: 2008-09-01 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Multi-classifier systems, also known as ensembles, have been widely used to solve several problems, because they, often, present better performance than the individual classifiers that form these systems. But, in order to do so, it s necessary that the base classifiers to be as accurate as diverse among themselves this is also known as diversity/accuracy dilemma. Given its importance, some works have investigate the ensembles behavior in context of this dilemma. However, the majority of them address homogenous ensemble, i.e., ensembles composed only of the same type of classifiers. Thus, motivated by this limitation, this thesis, using genetic algorithms, performs a detailed study on the dilemma diversity/accuracy for heterogeneous ensembles / Sistemas Multiclassificadores, tamb?m conhecidos como comit?s de classificadores, t?m sido amplamente utilizados para resolver os mais variados problemas, pois em geral t?m melhores desempenhos que os classificadores base que formam esses sistemas. Para que isso ocorra, por?m, ? necess?rio que os classificadores base sejam t?o acurados quanto diversos entre si isso ? conhecido como dilema da diversidade-acur?cia. Dado a sua import?ncia, alguns trabalhos sobre o estudo do omportamento dos comit?s no contexto desse dilema foram propostos. Entretanto, a maioria dos trabalhos estudou tal problema para comit?s homog?neos, ou seja, comit?s formados apenas por classificadores do mesmo tipo. Sendo assim, motivado por esta limita??o, esta disserta??o, usando algoritmos gen?ticos, efetua um estudo mais detalhado sobre o dilema da diversidade-acur?cia em comit?s heterog?neos