949 resultados para and Multivariate Stochastic Control


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Nanotechnology is currently one of the fastest growing scientific fields. The products of this science have become part of our everyday lives. However, to date, regulatory agencies have not yet established a single definition for nanomaterials and nanotechnology. Therefore, each country has its own definitions and legislation to control products containing nanomaterials. Being relatively new materials, there are no long-term studies showing their impact on human health and the environment. Consequently, countries control the amount of nanomaterials present in cosmetics, allowing the end consumer to choose which cosmetic to use, by choosing products with or without nanomaterials. Therefore, the primary objective of this study was to identify the most used nanomaterials in cosmetics and verify whether these formulations are in accordance with the laws in force in the United States, the European Union and Brazil, thereby determining if the cosmetics on the market are in line with the existing laws in these three economic powers. This study is unique and will contribute to furthering the discussion on existing laws pertinent to the use of nanotechnology in cosmetics.

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Although social capital and health have been extensively studied during the last decade, there are still open issues in current empirical research. These concern for instance the measurement of the concept in different contexts, as well as the association between different types of social capital and different dimensions of health. The present thesis addressed these questions. The general aim was to promote the understanding of social capital and health by investigating the oldest old and the two major language groups in Finland, Swedish- and Finnish-speakers. Another aim was to contribute to the discussion on methodological issues in social capital and health research. The present thesis investigated two empirical data sets, Umeå 85+ and Health 2000. The Umeå 85+ study was a cross-sectional study of 163 individuals aged 85, 90, and 95 or older, living in the municipality of Umeå, Sweden, in the year of 2000. The Health 2000 survey was a national study of 8,028 persons aged 30 or above carried out in Finland in 2000-2001. Different indicators of structural (e.g. social contacts) and cognitive (e.g. trust) social capital, as well as health indicators were used as variables in the analyses. The Umeå 85+ data set was analyzed with factor analysis, as well as univariate and multivariate analysis of variance. The Health 2000 data was analyzed with logistic regression techniques. The results showed that the Swedish-speakers in the Finnish data set Health 2000 had consistently higher prevalence of social capital compared to the Finnish-speakers even after controlling for central sociodemographic variables. The results further showed that even if the language group differences in health were small, the Swedishspeakers experienced in general better self-reported health compared with the Finnish-speakers. Common sociodemographic variables could not explain these observed differences in health. The results imply that social capital is often, but not always, associated with health. This was clearly seen in the Umeå 85+ data set where only one health indicator (depressive symptoms) was associated with structural social capital among the oldest old. The results based on the analysis of the Health 2000 survey demonstrated that the cognitive component of social capital was associated with self-rated health and psychological health rather than with participation in social activities and social contacts. In addition, social capital statistically reduced the health advantage especially for Swedish-speaking men, indicating that high prevalence of social capital may promote health. Finally, the present thesis also discussed the issue of methodological challenges faced with when analyzing social capital and health. It was suggested that certain components of social capital such as bonding and bridging social capital may be more relevant than structural and cognitive components when investigating social capital among the two language groups in Finland. The results concerning the oldest old indicated that the structural aspects of social capital probably reflect current living conditions, whereas cognitive social capital reflects attitudes and traits often acquired decades earlier. This is interpreted as an indication of the fact that structural and cognitive social capital are closely related yet empirically two distinctive concepts. Taken together, some components of social capital may be more relevant to study than others depending on which population group and age group is under study. The results also implied that the choice of cut-off point of dichotomization of selfrated health has an impact on the estimated effects of the explanatory variables. When the whole age interval, 35-64 years, was analyzed with logistic regression techniques the choice of cut-off point did not matter for the estimated effects of marital status and educational level. The results changed, however, when the age interval was divided into three shorter intervals. If self-rated health is explored using wide age intervals that do not account for age-dependent covariates there is a risk of drawing misleading conclusions. In conclusion, the results presented in the thesis suggest that the uneven distribution of social capital observed between the two language groups in Finland are of importance when trying to further understand health inequalities that exist between Swedish- and Finnish-speakers in Finland. Although social capital seemed to be relevant to the understanding of health among the oldest old, the meaning of social capital is probably different compared to a less vulnerable age group. This should be noticed in future empirical research. In the present thesis, it was shown that the relationship between social capital and health is complex and multidimensional. Different aspects of social capital seem to be important for different aspects of health. This reduces the possibility to generalize the results and to recommend general policy implementations in this area. An increased methodological awareness regarding social capital as well as health are called for in order to further understand the cfomplex association between them. However, based on the present data and findings social capital is associated with health. To understand individual health one must also consider social aspects of the individuals’ environment such as social capital.

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ABSTRACT Losses due to soybean anthracnose, caused by Colletotrichum truncatum, have not been systematically quantified in the field, and the efficacy of chemical control of this disease is not known. This study shows an estimate of losses associated with the disease in soybean crops in the north of the country. Two trials with cv. M9144 RR were carried out in commercial fields in Tocantins State in the 2010/2011 and 2011/2012 growing seasons, in randomized blocks, with four replicates. Foliar applications were performed on plants at R1/R2 and R5.2 stages, employing CO2-pressurized equipment and application volume of 200 L ha-1. Nine fungicides and one untreated control were compared, and the disease gradients in the two seasons were obtained. The percentage of infected pods was calculated at the R6 stage. Grain yield ranged from 3,288 to 3,708 kg/ha in the untreated plots in 2010/2011 and 2011/2012, respectively, and from 3,282 to 4,110 kg/ha in the treated plots. In the 2010/2011 season, only azoxystrobin + cyproconazole significantly reduced the disease incidence, compared to untreated control plots, not differing from the remaining treatments. In the 2011/2012 season, there were no significant differences between treated and untreated plots. Highly significant correlations (p < 0.01) were found between yield and soybean anthracnose incidence on pods in both years (r = -0.85). For each 1% increment in the disease incidence, c. 90 kg/ha of soybean grain were lost. The current study determined that significant losses due to anthracnose occur in commercial crops in the north of the country and highlighted the limitation of chemical control as anthracnose management method.

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The objective of this study was to model mathematically and to simulate the dynamic behavior of an auger-type fertilizer applicator (AFA) in order to use the variable-rate application (VRA) and reduce the coefficient of variation (CV) of the application, proposing an angular speed controller θ' for the motor drive shaft. The input model was θ' and the response was the fertilizer mass flow, due to the construction, density of fertilizer, fill factor and the end position of the auger. The model was used to simulate a control system in open loop, with an electric drive for AFA using an armature voltage (V A) controller. By introducing a sinusoidal excitation signal in V A with amplitude and delay phase optimized and varying θ' during an operation cycle, it is obtained a reduction of 29.8% in the CV (constant V A) to 11.4%. The development of the mathematical model was a first step towards the introduction of electric drive systems and closed loop control for the implementation of AFA with low CV in VRA.

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In Finland, maternity and child health clinics play a key role in promoting health in young families. Currently, obesity causes the greatest challenges to clinics. In obese pregnant women, an increased risk for metabolic diseases exist which can affect both the mother and child. The purpose of this thesis was to explore the role of dietary counselling: in Finnish health clinics; in the regulation of dietary intake; and in affecting the body weight of women. The main aim was to test the effect of dietary counselling and probiotic intervention on dietary intake and maternal body weight during and after pregnancy. In addition to dietary counselling, the effect of other factors, such as eating behaviour on dietary intake and body weight control after pregnancy was assessed. Another aim was also to evaluate dietary counselling practices by nurses (n = 327) in Finnish health clinics assessed by a questionnaire. At the beginning of the pregnancy, women (n = 256) enrolled in a dietary intervention study, were randomised into three groups. One group received dietary counselling with probiotics, one had counselling with placebo and the third group was the control group. The control group consisted of women whom did not receive counselling and took placebo. Probiotics and placebo supplements were used until the end of exclusive breastfeeding or six months after pregnancy. Women were followed from early pregnancy up to four years after pregnancy. Follow-up visits took place three times during pregnancy, at one and six months, and one, two and four years after pregnancy. Dietary counselling, provided by a nutritionist, aimed to influence the quality of dietary fat intake. Dietary counselling is important to provide in clinics, as determined by the nurses, and these nurses expressed a want to improve their own nutritional knowledge through education. The nurses had varying knowledge of current dietary recommendations. Dietary counselling for women during and after pregnancy resulted in beneficial changes in dietary intake up to one year after pregnancy and body weight and waist circumference up to four years after pregnancy. Probiotics had a beneficial effect together with dietary counselling on waist circumference until one year after pregnancy, but not throughout the long term, four years after pregnancy. Other factors, such as eating behaviour, associated with dietary intake and body weight control after pregnancy. Specifically, dietary recommendations are reached amongst women whom had high cognitive restraint in their eating behaviour and did not demonstrate uncontrolled eating. Overweight women more frequently emotionally ate compared to normal weight women and women with central adiposity related more frequently to having an uncontrolled eating behaviour than women with normal waist circumference. In addition, being overweight prior to pregnancy and excessive weight gain during pregnancy associated with increased body weight retention after pregnancy. This study showed that individual dietary counselling is useful in influencing dietary intake which adheres to dietary recommendations and this counselling influences, favourably, body weight after pregnancy. Especially, women with the risk for weight retention, such as women who have emotional and uncontrolled eating behaviours, who were overweight prior to pregnancy or those who had excessive weight gain during pregnancy, may benefit from individual dietary counselling. This study underscores the need to develop dietary counselling practices for pregnant women and their follow-up after pregnancy in Finnish health clinics. These practices include increasing the efficacy of the counselling such as collaboration with families, having knowledgable health professionals and having sufficient resources.

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Control of an industrial robot is mainly a problem of dynamics. It includes non-linearities, uncertainties and external perturbations that should be considered in the design of control laws. In this work, two control strategies based on variable structure controllers (VSC) and a PD control algorithm are compared in relation to the tracking errors considering friction. The controller's performances are evaluated by adding an static friction model. Simulations and experimental results show it is possible to diminish tracking errors by using a model based friction compensation scheme. A SCARA robot is used to illustrate the conclusions of this paper.

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The objective of this study was to understand how organizational knowledge governance mechanisms affect individual motivation, opportunity, and the ability to share knowledge (MOA framework), and further, how individual knowledge-sharing conditions affect actual knowledge sharing behaviour. The study followed the knowledge governance approach and a micro-foundations perspective to develop a theoretical model and hypotheses, which could explain the casual relationships between knowledge governance mechanisms, individual knowledge sharing conditions, and individual knowledge sharing behaviour. The quantitative research strategy and multivariate data analysis techniques (SEM) were used in the hypotheses testing with a survey dataset of 256 employees from eleven military schools of Finnish Defence Forces (FDF). The results showed that “performance-based feedback and rewards” affects employee’s “intrinsic motivation towards knowledge sharing”, that “lateral coordination” affects employee’s “knowledge self-efficacy”, and that ”training and development” is positively related to “time availability” for knowledge sharing but affects negatively employee’s knowledge self-efficacy. Individual motivation and knowledge self-efficacy towards knowledge sharing affected knowledge sharing behaviour when work-related knowledge was shared 1) between employees in a department and 2) between employees in different departments, however these factors did not play a crucial role in subordinate–superior knowledge sharing. The findings suggest that individual motivation, opportunity, and the ability towards knowledge sharing affects individual knowledge sharing behaviour differently in different knowledge sharing situations. Furthermore, knowledge governance mechanisms can be used to manage individual-level knowledge sharing conditions and individual knowledge sharing behaviour but their affect also vary in different knowledge sharing situations.

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Understanding how weed seed germination and emergence respond to environmental factors is critical to determining their adaptive capabilities and potential for infestations, and could also aid in the development of effective control practices. Germination of Ipomoea asarifolia (Desr.) Roem. & Schultz and Stachytarpheta cayennensis (Rich) Vahl. decreased linearly with decreasing osmotic potentials. Also, increasing osmotic stress delayed germination of Ipomoea more than that of Stachytarpheta. Ipomoea germination was insensitive to light, while Stachytarpheta showed a positive photoblastic behavior. Nitrate had a negative effect on germination of Ipomoea seed under both light and dark conditions but stimulated dark germination of Stachytarpheta. Ipomoea emergence was not significantly affected by planting depth. However, for Stachytarpheta emergence was restrited to seeds planted at the soil surface. Emergence of Ipomoea seedlings from greater than 6cm significantly decreased the amount of biomass allocated to roots, while biomass allocated to leaves was decreased for seedlings that emerged from depths greater than 2cm. These germination and emergence responses are discussed in relation to their ecological implications and to weed control strategies.

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The aim of this thesis was to examine congruencies between university identity and university images of prospective and current students. Therefore, factors essentially influencing on expected and experienced university images were identified. Providing an understanding on the differences in the formation of both concepts allowed the analysis of potential incongruities between a university’s identity and the perceptions its students hold. The study was conducted in July and August 2013 at Lappeenranta University of Technology by means of a web-based research survey. The sample consisted of 160 international Master’s degree students who were admitted in 2011, 2012 and 2013. Descriptive and multivariate statistical analysis methods were used to process the data. The results of the study indicated statistically significant incongruities between the case university’s identity and its students’ images. Further, the expected and experienced university images showed incongruities to each other. Deviations were additionally detected to be dependent on the students’ home regions. All in all, there is potential for an improvement of the students’ experiences resulting from a low perception of the student’s preparation for future job life.

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Two field experiments were conducted in two successive seasons, 2005/2006 and 2006/2007, to determine whether management can improve faba bean competitiveness with weeds, thus helping to achieve its yield potential. The experiment included five treatments, composed of organic and mineral fertilizers, alone and mixed at different rates, along with a control and six weed control treatments, including oxadiargyl, prometryn, hand hoeing treatments alone or mixed with the herbicides, and a nonweeded treatment (control).The herbicide treatments were not superior to the two hand-hoeing treatments. Using compost favored growth and yield of faba bean more than of weeds. Adding fertilizer also improved most yield parameters. Application of compost alone or combined with 50 or 100% of the recommended NPK rate improved faba bean growth in terms of net assimilation rate, specific leaf area, and leaf weight ratio as components of relative growth rate. This improvement in growth resulted in increase of seed yield, yield components and protein of faba bean. Faba bean yield performance improved under interactive fertilizer effects and weed control treatments as growth improved, as a result of nutrient release from fertilizers and weed control.

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The interference imposed the by weeds on corn decreases practically all vegetative characteristics. As consequence, the green ear and grain yield are also reduced. Losses due to the fall armyworm (Spodoptera frugiperda) attack can reduce corn grain yield up to 34%. In general, weed and insect control issues are addressed separately in research papers. Nevertheless, interaction between weeds and insects may exist. This study aimed to evaluate green ear and corn grain yield response to weed and fall armyworm control. A completely randomized block design with split-plots and five replicates was adopted. Corn cultivar AG 1051 was grown under weedy conditions or with control by hand hoeings performed at 20 and 40 days after planting. Fall armyworm control (applied to subplots) was performed with sprays of water (control), deltamethrin (5g active ingredient ha-1); neem oil, at 0.5% (diluted in water), and neem leaf extract at 5%. Each product was sprayed three times, at seven-day intervals, starting at the 7th day after planting, using 150 L ha-1 of the tank solution. Dry mass of the above-ground part, internode diameter, leaf length, leaf width, leaf area, green ear yield and grain yield of corn were reduced due to the lack of weed control. Fall armyworm control in the weeded plots did not influence green ear yield and grain yield, except green mass of marketable, husked ears, which was reduced when the caterpillar was not controlled. Without weed control, neem extracts and deltamethrin sprays provided highest yields of number and total weight of green ears with husks, number and weight of marketable ears with husks and number of marketable ears without husks. The best results for husked ear mass and for grain yield were obtained with neem extract and deltamethrin, respectively.

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The objective of this work was to evaluate the selectivity of clomazone in two formulations and S-metolachlor applied on shoots of different sizes after pruning of 'Baianinha' cassava. The experiment was arranged in a randomized block design in a factorial 5 x 2 (5 treatments x 2 sizes of shoots after pruning - 10 and 33 cm) with four replications. The herbicides evaluated were: clomazone (encapsulated suspension - 900 g h-1), clomazone (encapsulated suspension - 1,080 g ha-1), clomazone (emulsifiable concentrate 900 g ha-1), S-metolachlor (1,920 g ha-1) and an untreated control. During the experiment, all plots were kept free of weed interference by hand weeding. It was concluded that both the formulations of clomazone and S-metolachlor were selective when applied on both the shoot sizes evaluated. However, the application of S-metolachlor on 33 cm shoots gave higher selectivity to 'Baianinha' cassava plants.

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Greenhouse studies were conducted in 2008-2009 with the objective of adjusting dose-response curves of the main soil-applied herbicides currently used in cotton for the control of Amaranthus viridis, A. hybridus, A. spinosus, A. lividus, as well as comparing susceptibility among different species, using the identity test models. Thirty six individual experiments were simultaneously carried out in greenhouse, in a sandy clay loam soil (21% clay, 2.36% OM) combining increasing doses of the herbicides alachlor, clomazone, diuron, oxyfluorfen, pendimethalin, prometryn, S-metolachlor, and trifluralin applied to each species. Dose-response curves were adjusted for visual weed control at 28 days after herbicide application and doses required for 80% (C80) and 95% (C95) control were calculated. All herbicides, except clomazone and trifluralin, provided efficient control of most Amaranthus species, but substantial differences in susceptibility to herbicides were found. In general, A. lividus was the least sensitive species, whereas A. spinosus demonstrated the highest sensitivity to herbicides. Alachlor, diuron, oxyfluorfen, pendimethalin, S-metolachlor, and prometryn are efficient alternatives to control Amaranthus spp. in a range of doses that are currently lower than those recommended to cotton.

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The use of herbicides, even in tolerant crops, can cause stress evidenced by increase phytotoxicity affecting growth and development. The objectives of this study were to evaluate herbicides effect from different mechanisms of action in photosynthetic and oxidative stress parameters, as well visual phytotoxicity and wild radish control in wheat crop, cultivar Quartzo. Two trials were conducted where the first one evaluated the photosynthetic parameters on wheat plants in two seasons collection, following the application of herbicides bentazon, clodinafop, iodosulfuron, metribuzin, metsulfuron and 2,4-D; and the second one evaluated wild radish (Raphanus sativus) control, wheat phytotoxicity and yield due to bentazon, iodosulfuron, metribuzin, metsulfuron and 2,4-D herbicides application. Photosynthetic rate, stomatal conductance and transpiration were negatively affected by metribuzin, metsulfuron and 2,4-D herbicides at 24 and 120 HAS (hours after spraying) compared to control. Oxidative stress was similar or lower to control, when herbicide was applied and, in general, there was no difference between application times. Lipid peroxidation, catalase activity and phenols were higher in the first collection time. The application of herbicides iodosulfuron and 2,4-D reduces chlorophylls and carotenoids in wheat. Herbicides bentazon, iodosulfuron, metribuzin, metsulfuron and 2,4-D are selective to wheat, cultivar Quartzo and do not affect wheat yield. 2,4-D, metribuzin and iodosulfuron are more efficient for wild radish control.

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In order to adapt to daily environmental changes, especially in relation to light availability, many organisms, such as plants, developed a vital mechanism that controls time-dependent biological events: the circadian clock. The circadian clock is responsible for predicting the changes that occur in the period of approximately 24 hours, preparing the plants for the following phases of the cycle. Some of these adaptations can influence the response of weeds to the herbicide application. Thus, the objectives of this review are to describe the physiological and genetic mechanisms of the circadian clock in plants, as well as to demonstrate the relationship of this phenomenon with the effectiveness of herbicides for weed control. Relationships are described between the circadian clock and the time of application of herbicides, leaf angle and herbicide interception, as well as photosynthetic activity in response to the circadian clock and herbicide efficiency. Further, it is discussed the role of phytochrome B (phyB) in the sensitivity of plants to glyphosate herbicide. The greater understanding of the circadian clock in plants is essential to achieve greater efficiency of herbicides and hence greater control of weeds and higher crop yields.