The performance of peristaltic pumps is mainly governed by their tubing or hose materials. Research and development in this area is therefore very important for peristaltic pump manufacturers to keep in front of the competition and to open up new applications to enable further market penetration. Another aspect of this is of course price; performance and cost have to be in balance. As an approach to fabricate a new tube material, the field of negative Poisson's ratio (or: auxetic) materials is explored. The combined deformations of tensile, compression and shear in a peristaltic pump tube may well benefit from the specific characteristics of auxetic materials. Materials can be designed to keep their dimensions constant in directions perpendicular to an applied load. This is referred to as “auxetic balancing”. Finite element modelling shows that lowering the Poisson's ratio will rapidly decrease the maximum stresses in the cross-section of an occluded tube. Optimum values for the Poisson's ratio are found to be between −0.1 and +0.1, preferentially being 0. The re-entrant honeycomb structure is selected for initial trials, but manufacturing of this structure at the desired dimension proved to be too difficult at this time. Instead, electrospun nanofibre membranes are selected as the reinforcement structure. A liquid silicone elastomer is used as the matrix material. Key characteristics for the new material are derived from baseline test results on existing tubing. Laminates are manufactured from electrospun nylon6 nanofibre membranes coated with a liquid silicone rubber. Compression moulding is used to cure the nylon6-silicone rubber laminate, to give two effects: it ensures impregnation of the membrane and the compression deforms the nanofibre structure in such a way that it will become auxetic through-the-thickness. Flat sheet laminates of 2 mm thickness are manufactured with 14 layers of reinforcement. A reinforcing effect and substantial lowering of the through-the-thickness Poisson's ratio is observed for the laminates at low strains. At higher strains (>50%) the effect of the reinforcement diminishes and the Poisson's ratio of the laminate and pure silicone rubber equalises. Finally, tubular laminates are manufactured and the resulting tubes are tested in a peristaltic pump with some promising results (>1 million occlusions before failure). Tube performance is not yet at the required level, but with further optimisation of the laminating process, mould design and (post-)curing large steps forward can be made.

"The information ratio is a very controversial topic in the business world. Some portfolio managers put a lot of weight behind this risk-analysis measurement while others believe that this financial statistic can be easily manipulated and thus shouldn't be trusted. In this paper, an attempt will be made to show both sides of this issue by defining the information ratio, applying this definition to real world situations, explaining some of the negative impacts on the information ratio, comparing this ratio to other statistical measures, and showing some ways to improve a portfolio manager's information ratio. "

O presente trabalho irá abordar dois temas matemáticos de diferentes contextos históricos mas que apresentam uma relação intrínseca com o número Φ, mais conhecido como número de ouro. Partiremos de uma breve descrição dos conjuntos numéricos N, Z, Q e algumas propriedades dos números racionais para, em seguida, deduzirmos os números irracionais Π e, enfim, os números reais R. Na sequência vamos trabalhar com dois problemas muito antigos: o primeiro aparece na coletânea de livros Os Elementos do matemático grego Euclides, 300 anos a.C., e diz respeito à divisão de um segmento em média e extrema razão e, o segundo, foi publicado no livro Liber Abaci do matemático italiano Leonardo Fibonacci, século XIII, e trata da reprodução de coelhos e a sequência a qual ela origina. Veremos que o número de ouro aparece em ambos os problemas e vem ao longo dos séculos desencadeando muitas teorias que tratam de padrões e beleza. Abordaremos situações do passado e do presente que fazem uso desses padrões, além de fenômenos da natureza. Também apresentaremos um conjunto de atividades para orientar professores do ensino médio de como trabalhar, numa perspectiva interdisciplinar com vários conteúdos da matemática, e o número Φ. / This work addresses two mathematical topics from different historical contexts but that have an intrinsic relationship with the number Φ, better known as the golden number. We start with a brief description of the numerical sets N, Z, Q and some properties of rational numbers, and then deduct the set of irrational numbers π and, finally, the set of real numbers R. In the sequence we work with two very old problems: the first appears in the collection of books The elements of the Greek mathematician Euclid, 300 years BC, and concerns the division of a segment in extreme and mean ratio, and the second, published in the book Liber Abaci of the Italian mathematician Leonardo Fibonacci, in the thirteenth century, and deals with the breeding of rabbits and the sequence which it originates. We will see that the golden number appears on both problems and has over the centuries triggering many theories dealing with standards and beauty. We discuss situations of past and present that makes use of these standards, as well as natural phenomena. We also present a set of activities to guide middle school teachers on how to work in an interdisciplinary perspective with various mathematical content, and the number Φ.

The evaluation of financial situation and financial health of the company SAND TEAM, spol. s r. o. with using the financial analysis' methods and its instruments (the chosen indexes of profit ratio, activity, liquidity and indebtedness). The position determination at the market, due to comparison of the financial analysis' data. The formulation of suggestions and recommendation regarding to the suitable managing of the company, which lead to the improvement of the situation, e.g. keeping the financial health and the powerful position at the market.

A análise de dados composicionais está sendo amplamente utilizada nas diversas áreas do conhecimento como por exemplo na análise de sedimentos rochosos, na comparação de diferentes células e até na análise criminalística na comparação de evidências de crimes. Durante a história da análise deste tipo de dados existiram muitos tipos de ajustes utilizados para contornar o problema da soma constante das variáveis e ainda hoje não temos um consenso de qual a melhor solução a ser utilizada. Neste trabalho, temos como objetivo a enunciação das 7 transformações que mais foram utilizadas ao longo do tempo e suas vantagens e desvantagens. A análise de componentes principais foi escolhida para o comparativo destas transformações. Fizemos a aplicação destas transformações em três bancos de dados reais com características diferentes entre si, comparamos os resultados e analisamos qual das transformações apresentou o melhor desempenho em cada base de dados. Os critérios de comparação foram o percentual da variância explicada, as variáveis que foram mais importantes para a primeira componente principal, cargas das variáveis nas componentes principais mais importantes assim como suas correlações com as variáveis. Também, simulamos quatro estruturas de bases de dados composicionais para avaliar o desempenho das transformações. Para essas comparações e simulações, foram desenvolvidas algumas funções, utilizando o \\textit estatístico R, que visam facilitar a comparação entre as sete transformações, assim auxiliando na escolha de qual das transformações melhor se adapta aos dados. Pelos resultados obtidos notamos que: nas bases de dados reais, os resultados das explicações da variância das transformações são similares e as transformações Ref e Alr mostram melhores desempenhos que as demais; nas quatro estruturas simuladas as transformações Ref e Alr também possuem os melhores resultados na explicação da variância e a interpretação de suas componentes principais são parecidas, assim como as transformações Trad, Log e Clr. Com isso notamos que independentemente da aplicação do logaritmo nas transformações Alr e Log elas apresentaram resultados muitos similares às transformações Ref e Trad, respectivamente, tanto na explicação da variância como na interpretação das componentes principais. / The compositional data analysis is being widely used in several areas of knowledge such as the analysis of rocky sediments, to compare different biological cells and even in forensic analysis to compare crimes evidences. During the history of the analysis of such data, to circumvent the problem of variable\'s constant sum were used many types of adjustments. Until now, we do not have a consensus in which is the best solution to be used in this cases. In this paper, we aim to enunciate seven transformations that most were used over time and their advantages and disadvantages. The principal component analysis was chosen for the comparison of these transformations. We applied this transformations in three real databases with different characteristics, we hope to compare the results and analyze which transformation have the best performance in each database. The comparison criteria were the percentage of explained variance, the variables that were most important to the first principal component,variable\'s loads in the most important principal components as well their correlation with the variables. We also simulated four compositional data bases structures to evaluate the performance of the transformations. For these comparisons and simulations were developed some functions, using the statistical software R, to facilitate comparison between the seven transformations, thus assisting in choosing which of the best transformation fits to the data. From the results we note that: for the real databases, the results of the variance explanation of all transformations are similar, thus Ref and Alr transformations show better performances than the others; in the four simulated structures the Ref and Alr transformations also have the best results in the variance explanation and interpretation of its main components are similar, as well as the transformations Trad, Log and Clr. Thus we note that independently of applying logarithm in and Log and Alr transformations they present very similar results as Ref and Trad transformations, respectively, both in variance explanation and in the interpretation of the principal components.

Rural Iowa towns often lack flood mitigation because of a lack of resources and inability to compete for federal assistance funds. The Federal Emergency Management Agency relies on a benefit-cost analysis which produces benefit-cost ratios (BCRs) for proposed projects to determine which communities receive funding, with an emphasis on the economic BCR, which compares potential future benefits with estimated capital costs. The FEMA requirement for an economic BCR is at least 0.75. The economic BCRs for mitigation projects in rural towns are often lower compared to those in urban centers due lower potential future benefits from lower building count and potential exposure. Here we use a multijurisdictional approach which analyzes flood mitigation at a watershed scale to join upstream agricultural potential future benefits with downstream potential avoided benefits in rural towns. We predicted BCRs of simulated flood retention wetlands using HAZUS-MH to find the potential future benefits a range of estimated capital costs via a percent reduction approach and a targeted peak flow approach to calculating wetland effects on peak flow. The percent reduction approach generated BCRs of over 0.75 in the Mud Creek watershed for estimated capital costs per wetland up to $177,400. However, the simulated flood retention wetlands did not generate BCRs high enough to meet the minimum requirement in the Hinkle Creek watershed by itself. However, a multijurisdictional approach is not limited to each watershed individually. When the simulated flood retention wetland projects in each watershed were combined, the BCRs were high enough to meet the FEMA requirement. The combined BCRs were over 0.75 for estimated capital costs up to $143,300. The targeted peak flow approach included BCRs which account for dry and wet antecedent soil moisture conditions and minimum, maximum and average peak flow change scenarios. The scenarios with dry antecedent soil moisture conditions created BCRs higher than wet antecedent soil moisture conditions. Further, the maximum peak change scenarios generated BCRs higher than average peak change scenarios, which in turn generated higher BCRs than the minimum peak change scenarios. In the Mud Creek watershed, the only scenario to generate BCRs above 0.75 for any part of the range of estimated capital costs was the maximum peak change scenario under dry antecedent soil moisture conditions. However, the maximum and average peak change scenarios under dry antecedent soil moisture conditions and the maximum peak change scenario under wet soil moisture conditions generated BCRs over 0.75 in the Hinkle Creek watershed. When the simulated flood retention wetland projects for both watersheds were combined, only the maximum peak change scenario under dry antecedent soil moisture conditions generated BCRs above 0.75. We found that a multijurisdictional approach is a viable method for rural watersheds to analyze potential flood mitigation projects to help increase their BCRs.

Thesis (M.Sc. (Agriculture)) --University of Limpopo, 2010 / Ten experiments were conducted to determine the effect of dietary energy to protein ratio level on growth and productivity of indigenous Venda chickens raised in closed confinement from day-old up to thirteen weeks of age. The ten experiments were based on five different energy levels of 12.2, 13, 13.2, 13.4 and 14 MJ ME/kg DM. Each dietary energy level had five different levels of protein concentrations of 220, 190, 180, 170 and 160 g/kg DM, thus ending up with twenty five different dietary energy to protein ratio levels. Experiments 1 to 5 examined the effect of dietary energy to protein ratio on productivity of unsexed Venda chickens aged one to six weeks. Experiments 1 to 5 each commenced with 160 unsexed day-old indigenous Venda chicks with an initial weight of 25 ± 2 g per bird and each lasted for a period of six weeks. In each experiment, the chicks were randomly assigned to five treatments with four replications, each having eight birds. Thus, 20 floor pens (1.5 m2 /pen) were used in total for each experiment. All the five experiments were carried out around the same time. A complete randomized design was used for each experiment. A quadratic regression model was used to determine the ratios for optimum feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy and nitrogen retention in each experiment while a linear model was used to determine the relationship between optimal responses in the above variables and dietary energy to protein ratio levels. Dietary energy to protein ratio level for optimal response for any variable was relative and depended on the energy to protein ratio values of the diet. Energy to protein ratios of 63, 67, 70, 74 and 78 MJ ME/kg protein promoted optimal live weights of 415, 408, 370, 365 and 344 g at six weeks of age for diet energy levels of 12.2, 13, 13.2, 13.4 and 14 MJ ME/kg DM, respectively. However, optimal response trends for different variables were also influenced by the dietary energy to crude protein ratio. Optimal feed intake increased linearly with increasing dietary energy to protein ratio levels. Similarly, optimal metabolisable energy level increased linearly with increasing dietary energy to protein ratio levels without any increase in live weight. On the other hand, increasing dietary energy to protein ratio level decreased growth rate with a linear deteriorating feed conversion ratio,thus, negatively affecting live weight of the chickens at six weeks of age. However, increasing dietary energy to protein ratio levels improved efficiency of protein utilization with a linear deteriorating metabolisable energy utilization. In experiments 1 to 5, correlation analysis indicated that optimal feed intake, feed conversion ratio and metabolisable energy level were positively and strongly correlated with dietary energy to protein ratio levels while optimal live weight, growth rate and nitrogen retention were negatively and strongly correlated with dietary energy to protein ratio levels. The study indicated that a diet containing a crude protein content level of 178 g/kg DM and an energy level of 14 MJ ME/kg DM allowed for optimal utilization of absorbed protein and energy for growth in unsexed indigenous Venda chickens aged between one and six weeks. Experiments 6 to 10 examined the effect of dietary energy to protein ratio level on productivity of male Indigenous Venda chickens raised in closed confinement from seven up to 13 weeks of age. Each experiment commenced with 100 seven-week old male Venda chickens with an initial weight of 320 ± 2 g per bird. In each experiment, the chickens were randomly assigned to five treatments with four replications, each having five birds. Thus, 20 floor pens (1.5 m2/pen) were used in total for each experiment. All the five experiments were carried out around the same time and for a period of seven weeks. A complete randomized design wasused for each experiment. A quadratic regression model was used to determine energy to protein ratios for optimum feed intake, growth rate, feed conversion ratio,live weight, metabolisable energy, nitrogen retention, carcass yield, breast meatyield and fat pad deposition in each experiment while a linear model was used to determine the relationship between optimal responses of the above variables and dietary energy to protein ratio levels. Energy to protein ratios of 60, 71, 66, 72 and 71 MJ ME/kg protein promoted optimal live weights of 1167, 950, 983, 1235 and 1172 g at thirteen weeks of age for diet energy levels of 12.2, 13, 13.2, 13.4 and 14 MJ ME/kg DM, respectively. Optimal response trends in feed intake, growth rate, feed conversion ratio, nitrogen retention, and metabolisable energy intakes in male Venda chickens tended to increase with increase in dietary energy to protein ratio level. In contrast, optimal carcass and breast meat yield tended to decrease with increasing dietary energy to protein ratio level. However, optimal live weight and fat pad remained unchanged with increase in dietary energy to protein ratio value. Additionally, increasing dietary energy to protein ratio level improved efficiency of protein utilization with deteriorating metabolisable energy utilization.On the other hand, experiments 6 to 10 showed that optimal feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy level, nitrogen retention and fat pad were positively and poorly correlated with dietary energy to protein ratio levels while optimal carcass weight and breast meat yield were negatively and poorly correlated with dietary energy to protein ratio levels This study indicated that a diet containing 193 g CP/kg DM and an energy level of 14 MJ ME/kg DM allowed for optimal utilization of absorbed protein and energy for growth in male indigenous Venda chickens aged between seven and thirteen weeks.It is, therefore, concluded that optimal response trends for different variables in growing unsexed Venda chickens offered diets differing in optimal dietary energy to protein ratio levels are influenced by the diet crude protein content rather than the feed energy level per se. Diets containing decreased dietary energy to protein ratio levels may promote improved growth rate and efficient feed conversion ratio while naturally restricting feed intake. Diets containing increased dietary energy to protein ratio levels favoured efficient utilization of consumed dietary protein. However, with such diets, protein became limiting and birds increased their feed intake attempting thereby to obtain more of the limiting protein in order to meet their protein requirement regardless of the energy value of the diet.It is, also, concluded that growing male Venda chickens increased their feed intake with increase in dietary energy to protein ratio. This is contrary to what has been observed in broiler chickens which decrease their intake with increase in diet energy value. It is suggested that this might reflect the differences between indigenous and broiler chickens in terms of their genetic and physiological abilities to regulate their feed intakes according to dietary energy levels. / National Research Foundation (NRF)

Given a set of potential explanatory variables, one model selection approach is to select the best model, according to some criterion, from among the collection of models defined by all possible subsets of the explanatory variables. A popular procedure that has been used in this setting is to select the model that results in the smallest value of the Akaike information criterion (AIC). One drawback in using the AIC is that it can lead to the frequent selection of overspecified models. This can be problematic if the researcher wishes to assert, with some level of certainty, the necessity of any given variable that has been selected. This thesis develops a model selection procedure that allows the researcher to nominate, a priori, the probability at which overspecified models will be selected from among all possible subsets. The procedure seeks to determine if the inclusion of each candidate variable results in a sufficiently improved fitting term, and hence is referred to as the SIFT procedure. In order to determine whether there is sufficient evidence to retain a candidate variable or not, a set of threshold values are computed. Two procedures are proposed: a naive method based on a set of restrictive assumptions; and an empirical permutation-based method. Graphical tools have also been developed to be used in conjunction with the SIFT procedure. The graphical representation of the SIFT procedure clarifies the process being undertaken. Using these tools can also assist researchers in developing a deeper understanding of the data they are analyzing. The naive and empirical SIFT methods are investigated by way of simulation under a range of conditions within the standard linear model framework. The performance of the SIFT methodology is compared with model selection by minimum AIC; minimum Bayesian Information Criterion (BIC); and backward elimination based on p-values. The SIFT procedure is found to behave as designed—asymptotically selecting those variables that characterize the underlying data generating mechanism, while limiting the selection of false or spurious variables to the desired level. The SIFT methodology offers researchers a promising new approach to model selection, whereby they are now able to control the probability of selecting an overspecified model to a level that best suits their needs.

The present study was designed to investigate the effects of a stimulus change inserted in the large component of a mixed fixed-ratio 10 fixed-ratio 100 schedule. In mixed fixed-ratio schedules, a run of responses which approximates the response requirement of the smaller fixed ratio occurs at the beginning of the larger fixed ratio. This run of responses and the pause it precedes is called a prime. In Experiment I, priming acquisition was compared in a mixed schedule in which a change in key-color followed completion of the first 10 responses of the fixed-ratio 100 component and a mixed schedule with no stimulus change. Primes were acquired more rapidly in the mixed schedule with the stimulus change and the number of responses in a priming run was less variable than occurred without the stimulus change. In Experiment II, the effect of the stimulus change on primes was further investigated by removal of the smaller fixed-ratio component or by varying the location of the stimulus change. Primes occurred only when the smaller fixed-ratio component was present. Varying the location of the stimulus change resulted in the transfer of control from the external stimulus to response-produced stimuli. Future investigation of this point of transfer should prove useful in the study of the proprioceptive stimulus control of homogeneous behavior sequences. In Experiments Ill through VI, the variables controlling the length of the post-prime and the post-reinforcement pauses were investigated using the mixed FR x chained FR x FR y schedule. In this series of experiments, FR x was varied with FR y held constant at both high and low values. In addition, FR y was varied with FR x held constant at both high and low values. The results indicate that the post-prime pause is primarily a function of FR y, the number of responses required after the priming run. On the other hand, both post-reinforcement pauses were shown to be a function of FR x, the size of the small fixed ratio. An interaction between FR x and FR y and both the post-reinforcement and the post-prime pauses suggested that pausing in mixed schedules is a closed system. Taken as a whole, these results indicate the importance of mixed chained schedules in the investigation of the priming phenomenon.

Four pigeons had discrimination training that required the choice of a left side-key following completion of a fixed-ratio 10 an the center key, and a right side-key response after fixed-ratio 20. Correct choices were reinforced on various fixed-interval, fixed-ratio, random-interval, and random-ratio schedules. When accuracy was examined across quarters of intervals (fixed-interval schedules) or quarters of median interreinforcerrent intervals (fixed-ratio schedules), accuracy was usually laver in the second quarter than in the first, third, or fourth quarters. When accuracy was examined across quarters of ratios (fixed-ratio schedules) or quarters of median number of correct interreinforcement trials (fixed-interval schedules), accuracy increased across quarters. These accuracy patterns did not occur m random-interval or random-ratio schedules. The results indicate that, when choice patterns differed on fixed-interval and fixed-ratio schedules, these differences were due to the methods of data analyses.