Background : Old fields are abandoned agricultural areas that are undergoing secondary succession. A variety of factors influence the assembly, invasibility, and species turnover during secondary succession in old fields. Old fields are important ecological research locations as an increasing amount of agricultural land is abandoned worldwide. Objectives : 1) To determine if exotic and native "invaders" display differences in invasion success in an old field, and 2) To observe how native and exotic species abundances change over the course of secondary succession under predictable disturbance regimes and resource levels with regards to the Core-Satellite Species (CSS) hypothesis. Methods : An old field located in southern Illinois subject to three levels of fertilization (control, annually fertilized, and fertilized every 5 years) crossed with three levels of mowing treatments (control, spring mowed, and spring/fall mowed) established in 1996 was used to test objectives Seedlings of C3 grasses (native and exotic) were planted within one fertilizer treatment to compare invasion success. Species composition data (species occurrence and abundance at three heights) in all blocks were previously collected from 1996 to 2002 and the sample plots were resampled in 2013. Species sampled in 2013 were assigned to core or satellite categories per the CSS hypothesis. Results : Invading exotic seedlings had higher survivorship than invading native seedlings from the same functional group within the same fertilizer level, and added fertilizer increased seedling survivorship. The number of core and satellite species varied early after experiment establishment in 1996 but has since leveled off, and the ratio of exotic to native species cover at heights <1m ratio was affected by an interaction between mowing treatment and time. The species occupancy distribution of all species in 2013 was not bimodally distributed, but the occupancy distribution of exotic species in 2013 was bimodally distributed.The community composition of the plots varied among blocks, but was affected by an interaction between fertilizer treatment and mowing. Conclusions : Exotic invading grass seedlings in a successional community were relatively more successful than native invading grass seedlings. However, overall survivorship of all invading grass seedlings was low, a typical finding in grasslands. The identity of core and satellite species continued to fluctuate through time following 17 years of secondary succession. Resource availability and disturbance regime affects on community composition throughout secondary succession, and may result in many alternative stable states. This research supports the `CSS' and `parallel dynamics' hypotheses and indicates that presence of exotic species within a community does not necessarily facilitate invasion by new exotic species.

The thesis deals with the hypothetical concessive clauses and hypothetical comparative clauses in the present-day French and its subsequent comparison with Czech. The aim of this comparative work is to find the expressive means of the hypothetical concessive and hypothetical comparative clauses in the present-day French and compare them with their expressive equivalents Czech by using the InterCorp corpus. The thesis is divided into two main parts: theoretical and practical. The first one, theoretical part defines and describes basic concepts and divisions by using specialized literature. It proceeds from the general description from the clause to the hypothetical concessive and hypothetical comparative clauses. The second, practical part consists of the analysis of the French expression means of the hypothetical concessive and hypothetical comparative clauses in the InterCorp corpus, and subsequent by qualitatively and quantitatively processing of their Czech equivalents.

Neste estudo foram analisados 40 países para o período mais longo disponível no IFS, através do teste de cointegração de Johansen (1995) e Vetores de Correção de Erro (VEC) para explorar as evidências sobre a capacidade de hedge dos ativos acionários com relação à inflação. Além disso, incluiu-se um teste de cointegração com quebra estrutural a fim de testar a relação entre as séries que não cointegraram através do teste principal de Johansen (1995). Cabe ressaltar que, ao contrário dos artigos que analisam as variáveis em diferença, ao considerarmos as variáveis em nível, um equilibrio de longo prazo entre estas foi encontrado, e mesmo que o retorno ao equilíbrio seja lento, ele existe e, após um periodo suficientemente longo, ambas as variáveis retornarão ao equilíbrio de longo prazo. Além disso, o equilíbrio de longo prazo encontrado para a maioria dos países decorreu do teste sem a inclusão de quebra estrutural. Assim, a relação de longo prazo entre as variáveis permanece estável para 29 países, indicando que choques reais ou monetários, mesmo permanentes, não são capazes de afetar a dinâmica entre estas variáveis. / This study analyses 40 countries for the longest sample available at IFS, through the cointegration test of Johansen (1995) and Vector Error Correction Models (VECM), in order to explore the evidences concerning the stock assets capability of hedging inflation. Besides, this paper includes a cointegration test with structural break in order to test the long run relationship between the series of countries that did not cointegrate using the Johansen (1995) test. We can’t stress enough that, contrary to the other studies that use variables in difference, when we consider them in level a long run relationship arrises, and even though the return to equilibrium is slow, it exists and after a sufficiently long period, both variables will reach a long run equilibrium. Beyond that, a long run relationship was found for most countries before considering the existance of a structural break. Hence, the long run relationship remains stable for 29 countries, indicating that any real or monetary shocks, even those permanent, did not affect the long run dinamic between stock prices and goods prices.

Neste estudo foram analisados 40 países para o período mais longo disponível no IFS, através do teste de cointegração de Johansen (1995) e Vetores de Correção de Erro (VEC) para explorar as evidências sobre a capacidade de hedge dos ativos acionários com relação à inflação. Além disso, incluiu-se um teste de cointegração com quebra estrutural a fim de testar a relação entre as séries que não cointegraram através do teste principal de Johansen (1995). Cabe ressaltar que, ao contrário dos artigos que analisam as variáveis em diferença, ao considerarmos as variáveis em nível, um equilibrio de longo prazo entre estas foi encontrado, e mesmo que o retorno ao equilíbrio seja lento, ele existe e, após um periodo suficientemente longo, ambas as variáveis retornarão ao equilíbrio de longo prazo. Além disso, o equilíbrio de longo prazo encontrado para a maioria dos países decorreu do teste sem a inclusão de quebra estrutural. Assim, a relação de longo prazo entre as variáveis permanece estável para 29 países, indicando que choques reais ou monetários, mesmo permanentes, não são capazes de afetar a dinâmica entre estas variáveis. / This study analyses 40 countries for the longest sample available at IFS, through the cointegration test of Johansen (1995) and Vector Error Correction Models (VECM), in order to explore the evidences concerning the stock assets capability of hedging inflation. Besides, this paper includes a cointegration test with structural break in order to test the long run relationship between the series of countries that did not cointegrate using the Johansen (1995) test. We can’t stress enough that, contrary to the other studies that use variables in difference, when we consider them in level a long run relationship arrises, and even though the return to equilibrium is slow, it exists and after a sufficiently long period, both variables will reach a long run equilibrium. Beyond that, a long run relationship was found for most countries before considering the existance of a structural break. Hence, the long run relationship remains stable for 29 countries, indicating that any real or monetary shocks, even those permanent, did not affect the long run dinamic between stock prices and goods prices.

Orientador: Dimitar Kolev Dimitrov / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-16T01:35:19Z (GMT). No. of bitstreams: 1 Lucas_FabioRodrigues_D.pdf: 837192 bytes, checksum: 1cec40a06f620203e95cbca6134fd41a (MD5) Previous issue date: 2010 / Resumo: Nesta tese abordamos alguns problemas relacionados com zeros de polinômios e de funções inteiras. Estabelecemos fórmulas explícitas para os polinômios da sequência de Sturm, gerada por um polinômio e pela sua derivada. Como consequência, obtemos condições necessárias e suficientes para que um polinômio sem zeros múltiplos tenha somente zeros reais. Provamos também a veracidade de algumas condições necessárias para a hipótese de Riemann, estendendo desta forma um resultado anterior de Csordas, Norfolk e Varga que estabelecem uma conjectura de Pólya / Abstract: In this thesis we approach problems concerning zeros of polynomials and entire functions. We establish explicit formula for the polynomial in the Sturm sequence, generated by a polynomial and its derivative. As a consequence, we obtain necessary and sufficient conditions for a polynomial without multiple zeros to possess only real zeros. We prove also the truth of certain necessary conditions for the Riemann Hypothesis, thus extending a previous result of Csordas, Norfolk and Varga who established a conjecture of Pôlya / Doutorado / Analise Aplicada / Doutor em Matemática Aplicada

This work focus on situation prediction in data fusion systems. A hypothesis evaluation algorithm based on artificial neural networks is introduced. It is evaluated and compared to an algorithm based on Bayesian networks which is commonly used. It is also compared to a simple "dummy" algorithm. For the tests, a computer based model of the environment, including protected objects and enemy objects, is implemented. The model handles the navigation of the enemy objects and situational data is extracted from the environment and provided for the hypothesis evaluation algorithms. It was the belief of the author that ANNs would be suitable for hypothesis evaluation if a suitable data representation of the environment were used. The representation requirements include pre processing of the situational data to eliminate the need for variable input size to the algorithm. This because ANNs poorly handles this; the whole network have to be retrained each time the amount of input data changes. The results show that ANNs performed best of the three and hence seems to be suitable for hypothesis evaluation.

No description available.

Doctor of Philosophy / Department of Statistics / Haiyan Wang / Advances in technology easily collect a large amount of data in scientific research such as agricultural screening and micro-array experiments. We are particularly interested in data from one-way and crossed two-way designs that have a large number of treatment combinations but small replications with heteroscedastic variances. In this framework, several test statistics have been proposed in the literature. Even though the form of these proposed test statistics may be different, they all use limiting normal or chi-square distribution to conduct their tests. Such approximation approaches the true distribution very slowly when the sample size ni is small while the number of levels of treatments a gets large. A strategy to obtain better accuracy in the classical large sample size setting is to use the bootstrap procedure with studentized statistic. Unfortunately, the available bootstrap method fails when the number of treatment level combinations is large while the number of replications is small. The Fisher and Hall (1990) asymptotic pivotal statistic under large sample size setting is no longer pivotal under small sample size setting with large number of treatment levels. In the first part of this dissertation, we start with describing suitable bootstrap statistics and procedures for hypothesis tests in one- and two-way ANOVA with a large number of levels and small sample sizes. We prove that the theoretical type I error-rate of Akritas and Papadatos (2004) and Wang and Akritas (2006) test statistics and their corresponding bootstrap versions have accuracy of order O(1/√a). We then modify their statistics to obtain asymptotically pivotal statistics in our current framework. We prove that the theoretical type I error-rate of the bootstrap version of the pivotal statistics is accurate up to order O(1/√a). In the second part of the dissertation, we propose a new test statistic in one-way ANOVA which is asymptotically pivotal in the current setting. We improve the accuracy of approximation of the distribution of the test statistic by deriving asymptotic expansion of the statistic under the current framework and define a new test rejection region through Cornish-Fisher expansion of quantiles. The type I error-rate of the new test has a faster convergence rate and is accurate up to order O(1/a). Simulation studies show that our tests performs better in terms of type I error-rate but comparable power with that of Akritas and Papadatos (2004) in the large a small ni setting. The connection between our asymptotic expansions and bootstrap distribution in the large a small ni setting is discussed. Our proposed test based on asymptotic expansion and Cornish-Fisher expansion of quantiles have both the advantage of higher accuracy and computational efficiency due to no resampling is needed.

The past decade has witnessed a proliferation of internet use for socialising with dedicated websites such as Facebook, and also for maintaining relationships using computer mediated communication. Individuals can extend the boundary associated with traditional forms of communication, and use technology to meet strangers online to share interests, or maintain existing relationships remotely. One of the most significant functions of computer-mediated communication (CMC) is its contribution to the evolution of social communication. CMC is “communication that takes place between human beings via the instrumentality of computers” (Thurlow, Lengel, & Tomic, 2004). As a consequence of the convenience and flexibility that this channel provides, CMC can be effectively used to orchestrate a variety of communication situations. Furthermore, social networks sites are becoming the choice in which individuals are maintaining relationships or meeting new people. The potential distinctions between these relationships and their offline counterparts remain contradictory. Online relationships may face different challenges, such as anonymity, restricted interaction (Walther, 1992), and the lack of physical presence. For example, sharing activities online such as playing games or visiting Web sites together differs from offline activities, such as going to the movies or dining together. These observations question whether CMC relationships have any parallels with real world relationships. Dunbar (1992) structured real world relationship by strength of ties and formulated the social brain hypothesis (SBH). This work uses the SBH as an interpretive lens in analyzing CMC relationship ties. Thus, a major focus of this work is to investigate implications of the SBH (Dunbar, 1992) within the context of CMC usage. It is recognised that CMC allows for the maintenance of a large number of friendships. Thus potentially, the use of CMC could alter the SBH ratios. Within the main findings consistency with SBH was found. Furthermore, CMC has many parallels with real world communication methods. Face-to-face communications were strongly preferred for maintenance of strong ties. Also phone usage was analysed and identified as an indicator of strong tie relationships, for both local and distant communications. The findings also address questions on displaced communities communication habits and their use of CMC. The phone was found to be most popular media and culture had a strong influence on communication content. The research used a mixed method approach, combining data collection via questionnaires, semi structured interviews and a diary study completed by participants. Based on the findings, a framework is proposed categorising groups on their level of real world socialising and CMC use. There are four essential contributions impacting on current theory. The findings offer new knowledge within the research of CMC and relationship maintenance theory. In our understanding these exploratory questions have not yet been addressed and therefore the findings of this research project are significant in their contributions.

Master of Science / Department of Statistics / John E. Boyer Jr / It has been shown that the most straightforward approach to testing for the difference of two independent population proportions, called the Wald procedure, tends to declare differences too often. Because of this poor performance, various researchers have proposed simple adjustments to the Wald approach that tend to provide significance levels closer to the nominal. Additionally, several tests that take advantage of different methodologies have been proposed. This paper extends the work of Tebbs and Roths (2008), who wrote an R program to compare confidence interval coverage for a variety of these procedures when used to estimate a contrast in two or more binomial parameters. Their program has been adapted to generate exact significance levels and power for the two parameter hypothesis testing situation. Several combinations of binomial parameters and sample sizes are considered. Recommendations for a choice of procedure are made for practical situations.