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Steel tubular structures are becoming more widely used in recent years because of their excellent structural performance as well as appearance. For structures with steel hollow section (SHS) columns and concrete filled tubular (CFT) columns, several types of joint may be used to connect to wide flange beams. The topic of this research is a relatively new type of joint, the 'reverse channel' connection, in which the legs of a channel are welded to the tube thus converting the closed tubular column into an open section for connection purpose. However, since tubular columns have only recently become more popular in frames, there is a lack of research to quantify the moment-rotation characteristics of connections between I beams and tubular columns. A total of eight tests on loaded steel beam to RHS column connections using reverse channel and endplate, up to collapse, were carried out. The objectives of these tests were to investigate the effects of different connection details on connection performance and to provide experimental data for validation of numerical simulations. Validation of numerical modelling was carried out to check accuracy of the numerical simulation model developed using the general finite element package ABAQUS. The validated ABAQUS model was then used to perform various parametric studies to provide insight into structural behaviour. A systematic approach to quantify the load carrying capacity of the reverse channel web and the column face were adopted based on yield line theory. This thesis presents the derivation and validation of the analytical approach. The moment resistance of the whole connection can be obtained by assembling all the components together. A procedure for calculation was proposed to provide feasibility for designer and the analytical results were compared with the test results.

Redfield's theory and the theory of master equations have been reviewed and their applications to muonium spin dynamics discussed. It was found that both theories are equivalent in the Markov limit. In some cases, analytical expressions for relaxation rates are found. In addition, Redfield's theory was applied to describe spin relaxation of muonium-substituted free radicals near level-crossing resonances. Theoretical predictions were compared with experimental data for the C₆F₆-Mu radical and the results suggest there are several relaxation mechanisms involved. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

In the first essay, I document sample-specific and time period-specific style returns in two distinct sets of U.S. equities: Fama and French style portfolios and the S&P 1500 style indexes. The value and size effects are apparent in the Fama and French portfolios. Only the size effect is evident in the S&P data. In general, the Fama and French style returns are greater than those of the S&P 1500 styles. Style returns tend to be time-varying and exhibit momentum over a variety of formation period-holding period horizons. In the second essay, I utilize a bootstrap procedure to test for the presence of styleswitchers - as defined in Barberis and Shleifer (2003). I document style winner and loser continuations. There are some periods when no matter which particular style won (lost) in the past, it is more likely to continue winning (losing) in the future. I also test some Barberis and Shleifer (2003) propositions regarding style momentum. One proposition holds that Sharpe ratios from style-level momentum strategies should be at least as large as asset-level momentum Sharpe ratios. While many style momentum strategies generate significant returns, the implied Sharpe ratios are lower than those reported for asset-level momentum strategies. The Barberis and Shleifer (2003) model also suggests that style momentum could be time-varying. I condition style momentum returns on January, lagged market state, lagged monetary policy changes and lagged changes in relative dispersion and find significant conditional style-level momentum. In the third essay, I identify and test explanatory factors that potentially predict style momentum returns. Several macroeconomic, relative dispersion, market related and volatility related factors are associated with future short-term style momentum returns. Interactions of many of these variables with market and monetary state indicator variables are significant in the regressions as well.

No information is available on the role of allelopathy in crop rotation systems of the Western Cape Province of South Africa, where more than 100 000 ha are under threat from herbicide-resistant rye grass. A study which investigated the use of allelopathic properties for the suppression of rye grass hybrid type (Lolium multiflorum x perenne) was undertaken. These objectives were accomplished by: a) exploring the use of allelopathic properties of crop residues for rye grass suppression; b) evaluation of the role of allelopathy from seeds, seedlings, roots and above-ground plant material of rotational crops; c) assessing the distribution of genetic and morphological variability of rye grass and d) determining the interactions among micro-organisms and allelopathic root leachates from rotational crops and rye grass. In the field trials, growth inhibitory or stimulatory effects were observed on crops exposed to the residues of others. Medic suppressed the weed type rye grass. The radicle length of rye grass was inhibited by seed leachates from wheat and lupine. Growth inhibition from lupine seed and seedling leachates was evident in rye grass radicle length and cumulative germination percentage. Morphologically, 50% of the total number of specimens was classified as rigid rye grass, 48% as the hybrid, namely L. multiflorum x perenne and 2% as perennial rye grass. The wide genetic and morphological variation detected in rye grass may be due to high genotypic plasticity and hybridisation for producing the weed type L. multiflorum x perenne. The faster growth rate of rye grass on Langgewens soil treated with barley root leachates was revealed by Principal Component Analysis (PCA) as a probable association with growth-promoting soil micro-organisms. Crop cultivars and weeds may modify the soil micro-organism populations to their advantage and to the disadvantage of other species by the release of root exudates that apparently differ in composition between plant species. The effect on microbial communities varied with source of exudates and between soils. / Thesis (PhD)--University of Pretoria, 2011. / Plant Production and Soil Science / unrestricted

The thesis is focused on backup documents in the public administration information systems. First chapters of thesis are devoted to general theories of backup files and databases. Next is described storage media what is used for backups, their advantages and disadvantages. Afterwards are described the most common backup strategies and rotation scheme. Thesis is devoted after that to analysis of a representative information system that is used to publish documents to the public. Based on information obtained from analysis is selected optimal backup strategy and this strategy is implemented and tested in designed application.

Alguna vez y por diferentes motivos la palabra “millennials” ha sido escuchada y leída en distintos ámbitos, ya sean personales, profesionales o académicos. Los miembros de esta generación destacan por su adaptación al cambio, su alta autoestima, su familiaridad con la tecnología y su aporte con nuevas ideas sobre una determinada actividad. Esta generación representa actualmente la cuarta parte de la población peruana, lo que equivale a ocho millones de habitantes, los cuales tienen intereses muy particulares en relación al trabajo, a la calidad de vida y a su desarrollo personal. Su capacidad de relacionamiento es distinta a la de otras generaciones, están pendientes de las últimas tendencias de comunicación; la conectividad es parte de su ser, es la generación de la rapidez, del aquí y ahora. Sin embargo, el estar siempre conociendo nuevas tecnologías y nuevos procesos hace que los millennials no se sientan cómodos en una organización que no los rete, sobre todo cuando ya llevan laborando más de dos o tres años. Ante ello, la rotación laboral es un problema que todas las organizaciones a nivel mundial deben enfrentar, más aún, las empresas nacionales, donde la mayoría de sus colaboradores son representados por esta generación. Estas empresas deben preguntarse cuál o cuáles son los motivos por el que este personal rota de trabajo en trabajo, no sin antes reconocer en su organización al verdadero millennial para saber el tipo de liderazgo que deben aplicar los jefes para tenerlos y retenerlos dentro de sus equipos. El tiempo para la generación millennial vale mucho, en gran medida porque han crecido viendo a sus padres y abuelos dedicándole la mayor parte de su vida al trabajo, sus familias han vivido para trabajar y esta generación busca cambiar este concepto, en base al equilibrio entre el trabajo y su calidad de vida. El presente trabajo de investigación buscará mediante investigaciones, encuestas, entrevistas, tablas, teorías y cuadros estadísticos conocer cuáles son las razones principales por las que este grupo tiende a cambiar de empresa en el corto plazo y qué acciones deben tomar las organizaciones para retenerlos. / Abstrac: Once and for different reasons the word millennials have been heard and read in different fields, whether personal, professional or academic. The members of this generation stand out for their adaptation to change, their high self-esteem, their familiarity with technology and their contribution with new ideas about a particular activity. This generation currently represents a quarter of the Peruvian population, which is equivalent to eight million inhabitants, who have very particular interests in relation to work, quality of life and personal development. Their relationship capacity is different from that of other generations, they are pending the latest communication trends; Connectivity is part of your being, it is the generation of speed, from the here and now. However, being always aware of new technologies and new processes mean that millennials do not feel comfortable in an organization that does not challenge them especially when they have been working for more than two or three years. Given this, labor turnover is a problem that all organizations worldwide must face, even more, large companies, where most of their employees are represented by this generation. These companies must ask themselves what or what are the reasons why this staff rotates from work to work, but not before recognizing in their organization the true millennial to know the type of leadership that the bosses must apply to have them and retain them within their team. The time for the millennial generation is worth a lot, largely because they have grown up watching their parents and grandparents dedicating most of their lives to work, their families have lived to work and this generation seeks to change this concept, based on the balance between Work and its quality of life. This research work will search through research, surveys, interviews, tables, theories and statistical tables to know what are the main reasons why this group tends to change companies in the short term and what actions organizations should take to retain them. / Trabajo de investigación

Objective: This article describes the process of determining the need for a pass/fail grading system for APPE rotations and the development and implementation of a pass/fail grading process. Methods: Preceptors, faculty, and students were surveyed prior to the development and implementation of pass/fail grading and a new evaluation tool. Preceptors were surveyed after the new grading scheme had been in place for one year about their perceptions of student performance. Rates of APPE commendations under a pass/fail system and the number of students achieving a 4.0 under a point-based system are reported. Results: Surveys from preceptors indicate that pass/fail grading decreased preceptors concerns about distinguishing between student performances (56.6% had concerns prior to switching versus 30.6% having concerns after switching to pass/fail). Survey results also indicate that pass/fail grading did not affect preceptor's perception of student motivation (61.4% felt concerned under a graded system versus 12.2% were concerned after switching to pass/fail). A pass with honors commendation was given in 17.2% of rotation evaluations, contrasting with 83.1% of students achieving a 4.0 grade in a rotation prior to switching to pass/fail. Conclusions: The transition to a pass/fail grading system for APPE rotations is not associated with reductions in student motivation or performance, and is acceptable to preceptors. The implementation of a pass/fail system is complicated and takes a significant investment of time, but resulted in an APPE evaluation system which preserves student motivation, fosters robust feedback, decreases grade inflation, and allows preceptors to distinguish and reward student performance.

The existing literature determining the optimal rotation period of a forest stand under conditions of certainty, as well as under uncertainty, lacks the genera 1 scope to be useful. A forest provides timber of commercial value, a flow of recreational services, and other valuable environmental s ervices. Providing goods and services invo lves benefits as well as costs. Relevant management decisions depend on the net va 1 ues that can be obtai ned. The present work developes a more general model for determining an optimal rotation period incorporating various fixed and variable costs associated with timber production and recreational services in an environment of certainty and uncertainty. It is shown that under certainty, the optimal rotation period is likely to be finite and depending on the values of benefits and costs the rotation period indicated by the solution of this model may be identical to, shorter, or longer than that indicated by a model ignoring net values. In addition, a generalized Faustmann rule under certainty (when only recreational value i s added to the model ) using optimal control (maximum principle) as the analytical tool has been developed and the impact of two sources of uncertainties on the optimal rotation decision in the context of the more generalized model is analyzed. They are (1) uncertainty related to future stumpage price, and (2) uncertainty related to the future stock of trees due to unpredictable natural catastrophes. Under price uncertainty the optimal rotation period will be longer than that under conditions of certainty if the forest operator is risk averse. In addition, the period wi ll be lengthened with increasing risk and shortened with increasing expected stumpage price under noni ncreasing absolute risk aversion of the forest operator. The risk of catastrophic destruction of the biomass whether total or partial will lead to a rotation period dependent on the value of the average rate of occurrence of catastrophes.

The aim of the work was to analyze the erosion and runoff conditions in the cadastral area of Ketkovice in the district of Brno. The work focuses mainly on the outflow and erosion situation, the survey of terrain, the proposal of measures with a focus on alternation of crop belt rotation and the Spatial Plan of the municipality in terms of the runoff conditions. The first part of the diploma thesis is focused on the analyze the erosion and runoff conditions. The second part is focused on creating suitable shapes of alternation of crop belt rotation in combination with grass cover and creating a suitable grass line stripe, which will allow us to drain water and increase the amount of infiltration. My work is concentrated on how to apply these measures in the right way. Each of the methods was described and the individual results of the calculations were compared with each other, and subsequently the most suitable method for the given locality was developed. I´ve determined the erosion using the Wismeier-Smith equation in the ArcGIS As far as possible, it would be appropriate to use the most effective proposals for erosion protection using suitable erosion protective means. One of the possibilities is an area measure in combination with a line measure.