Cloud computing setups are a huge investment of resources and personnel to maintain. As<br />the workload on a system is a major contributing factor to both the performance of the<br />system and a representation of the needs of system users, a clear understanding of the<br />workload is critical to organizations that support supercomputing systems. In this paper,<br />we analyze traces from two production level supercomputers to infer the characteristics of<br />their workloads, and make observations as to the needs of supercomputer users based on<br />them. We particularly focus on the usage of graphical processing units by domain<br />scientists. Based on this analysis, we generate a synthetic workload that can be used for<br />testing future systems, and make observations as to e"cient resource provisioning. / Master of Science

Over the past decades, since the discovery of a single–site silica-supported catalyst for the alkane metathesis reaction by our group, we have been extensively working on the development of supported catalytic systems for the improved alkane metathesis reaction. During these developments, we understand the reaction mechanism and reached a new perspective for the synthesis of various supported bimetallic systems via the surface organometallic chemistry (SOMC) approach. Recently, with this bi-metallic system, we got a very high TON (10000) in propane metathesis reaction. As these catalysts are very efficient for linear alkanes we thought to apply it for cyclo-alkanes specifically, for cyclo-octane metathesis expecting better activity. Besides, the value of the ring alkanes are higher than the linear alkanes. The current work demonstrates a combination of [(ΞSi−O−)W(Me)5] and [(ΞSi− O−)Ti(Np)3 pre-catalyst with several supports (SiO2-700, SBA-15 and MCM-41) for metathesis of cyclooctane. The catalysts have been synthesized and fully characterized by elemental analysis (EA), FT-IR and NMR spectroscopies. After fully characterization the bi-metallic catalyst was tested for metathesis of cyclooctane with highest ever TON 2500 as compared to that of mono-metallic catalyst where we got 430 TON. Which again corroborates our prediction that bimetallic catalysts are better catalysts than monometallic catalysts.

This is the first comprehensive systematic review of the definitions used for retention measures in HIV care. This review provides a compilation of existing definitions of retention in HIV care in randomized controlled trials. In summary, we report very little consensus regarding definitions of retention in HIV care in the research literature. We report and compare definitions of retention so researchers can weigh their definitions with the body of definitions, with the ultimate aim of motivating the research community to establish a clear and unambiguous definition. This work will provide resources for researchers to recommend a definition of retention. Future research is needed to seek practitioners’ views on the most unambiguous, explicit definition of retention. This is only a first step in research toward a standard definition of retention. / Introduction Retention in HIV care is critical for PLHIV. However, retention in HIV care is not measured uniformly across studies. The aim of this study within a review (SWAR) is to describe the diversity in definitions used for retention in HIV care in randomized controlled trials. Methods We conducted a SWAR, drawing data from an overview of systematic reviews on interventions to improve the HIV care cascade. A comprehensive and exhaustive search was conducted of the following databases: PubMed, Excerpta Medica data BASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycINFO, Web of Science, and the Cochrane Library. We identified randomized controlled trials (RCTs) of interventions to improve retention in care for people living with HIV (PLHIV). First, from the included studies in systematic reviews and second using targeted searches for RCTs. Only English language systematic reviews were included, but RCTs in any language were eligible. Data were screened and extracted in duplicate using pre-set criteria, with arbitration as needed. We identified distinct components from the definitions used to measure retention. The components were further categorized based on the similarities between them. We described the components narratively and presented the definitions in tables. Results We identified 8001 records, after a duplication check, 4147 unique titles and abstracts were examined for relevancy, leaving 744 articles. Full-text screening of the articles resulted in 50 articles that measured retention and provided 59 definitions for retention in care. Of the included studies, 11(22%) were conducted in low-income countries, 12(24%) were conducted in lower-middle-income and upper-middle-income countries, and 13(26%) were conducted in high-income countries. We identified ten different components used to define retention. These components are follow-up times (83%), administrative records (8%), clinical visits (61%), gap scores (8%), group-level measures (17%), lab records (15%), pharmacy-based measures (29%), scheduled visits (27%) and visit counts (17%). The most frequently used components are follow-up times (n=49), and the easiest to measure are retention data derived from administrative records (n=5). We put the components into categories based on the similarities between them. Conclusion We identified existing definitions of retention in HIV care and the commonly used components in the definitions. This compilation of the definitions and identification of the components may provide a framework for developing the standard globally agreed-upon definition of retention in HIV care. / Thesis / Master of Health Sciences (MSc) / Globally, there are more than 37.7 million people living with HIV (PLHIV). Retention in human immunodeficiency virus (HIV) care is a common and modifiable determinant of increased adherence to antiretroviral therapy (ART), better health outcomes, and a better quality of life. There is no consensus in the literature on measures of retention in HIV care. This makes it very difficult to compare different studies and jurisdictions. This thesis review summarizes the definitions of retention used in randomized controlled trials (RCTs) and identifies the various components used to measure retention, which can be used as a reference for researchers to identify the gaps in the current definitions for HIV retention measures and identify preferred measures with the goal of reaching a standard consensus definition of retention in HIV care.

N2O chemisorption technique for copper dispersion determination was developed and optimized for accurate and reproducible results. With this technique, the bulk oxidation of pre-reduced catalyst can be prevented by N2O decomposition at low temperature (30oC). Only surface copper atoms are oxidized. The amount of freshly oxidized surface coppers is determined from H2-back-titration of fixed oxygen.The impact of temperature and time of exposure during oxidation was studied. Measurements made at higher temperature (60oC) resulted in overestimation of copper dispersion due to oxygen diffusion into the bulk and sub-layers. Much longer exposure time may also have an impact on copper dispersion estimation.For accurate results and good precision, it is recommended to work under mild conditions (isothermal oxidation at 30oC for 45 min.The developed method was successfully applied to fresh and spent catalyst. As expected, the copper dispersion for fresh catalyst was significantly higher than copper dispersion for spent catalyst.

Emerging technologies enable a set of distributed resources across a network to be linked together and used in a coordinated fashion to solve a particular parallel application at the same time. Such applications are often abstracted as directed acyclic graphs (DAGs), in which vertices represent application tasks and edges represent data dependencies between tasks. Effective scheduling mechanisms for DAG applications are essential to exploit the tremendous potential of computational resources. The core issues are that the availability and performance of resources, which are already by their nature heterogeneous, can be expected to vary dynamically, even during the course of an execution. In this thesis, we first consider the problem of scheduling DAG task graphs onto heterogeneous resources with changeable capabilities. We propose a list-scheduling heuristic approach, the Global Task Positioning (GTP) scheduling method, which addresses the problem by allowing rescheduling and migration of tasks in response to significant variations in resource characteristics. We observed from experiments with GTP that in an execution with relatively frequent migration, it may be that, over time, the results of some task have been copied to several other sites, and so a subsequent migrated task may have several possible sources for each of its inputs. Some of these copies may now be more quickly accessible than the original, due to dynamic variations in communication capabilities. To exploit this observation, we extended our model with a Copying Management(CM) function, resulting in a new version, the Global Task Positioning with copying facilities (GTP/c) system. The idea is to reuse such copies, in subsequent migration of placed tasks, in order to reduce the impact of migration cost on makespan. Finally, we believe that fault tolerance is an important issue in heterogeneous and dynamic computational environments as the availability of resources cannot be guaranteed. To address the problem of processor failure, we propose a rewinding mechanism which rewinds the progress of the application to a previous state, thereby preserving the execution in spite of the failed processor(s). We evaluate our mechanisms through simulation, since this allow us to generate repeatable patterns of resource performance variation. We use a standard benchmark set of DAGs, comparing performance against that of competing algorithms from the scheduling literature.

En la presente tesis doctoral, se ha llevado a cabo un estudio mediante la teoría del funcional de la densidad (DFT) sobre los mecanismos que gobiernan cuatro importantes procesos industriales relacionados con el amoníaco: el proceso Ostwald de producción de ácido nítrico, los procesos Degussa y Andrussow de producción de ácido cianhídrico y por último, el proceso MacArthurForrest de extracción de oro de sus minerales mediante sales de cianuro.Proceso Ostwald: Se han estudiado las barreras de activación y la termodinámica de las reacciones en el proceso de formación de NO sobre Au, Cu, Ir, Pd, Pt y Rh en las superficies (111) y (211). Asímismo, se ha estudiado el proceso sobre una aleación de PtRh como la utilizada industrialmente. Finalmente, la estabilidad termodinámica de los óxidos de platino y rodio en función de la presión de oxígeno y de la temperatura ha sido analizada.Se ha encontrado una alta selectividad a producción de NO para las superficies de Pt. Aunque Rh(211) y Pd(111) muestran una gran preferencia por la recombinación N+O respecto a la N+N, la desorción de NO está fuertemente impedida. Esto provoca que pueda disociarse de nuevo. No se ha encontrado que la adición de impurezas de Rh a la superficie de Pt favorezca la selectividad del proceso, aunque si mejora la estabilidad del material, ya que el Rh forma óxidos de mayor estabilidad que el Pt y presenta menor volatilidad.Procesos Degussa y Andrussow:Se ha realizado un estudio en el que se han determinado las barreras para las reacciones más relevantes en los procesos Degussa y Andrussow sobre la superficie Pt(111). Este estudio ha sido extendido a Au, Cu, Ir, Pd y Rh en condiciones no oxidativas.En Pt, se ha observado diferente mecanismo en función de la presencia (Andrussow) o no (Degussa) de oxígeno. En condiciones no oxidativas la recombinación de especies parcialmente hidrogenadas (CHx y NHy) y su posterior deshidrogenación es el camino de reacción más importante. En condiciones oxidativas las deshidrogenaciones están asistidas por oxígeno e hidroxilos y la población de especies cambia. De este modo, la reacción entre fragmentos poco (HC+N) o nada (C+N) hidrogenadas se convierte en el mecanismo de producción del enlace CN.Au y Cu muestran en general barreras pequeñas y reacciones exotérmicas para los procesos de recombinación. Se han determinado relaciones lineales entre las barreras de reacción para las disociaciones y la energía de adsorción del N atómico. Asímismo, se han encontrado relaciones lineales entre la energía de adsorción de las diferentes especies (CN, CNH y HCN) respecto a las energía de adsorción del átomo de C.Proceso MacArthurForrest: Para estudiar la interacción del grupo cianuro con las superficies Au(111) y (211) se ha realizado una comparación con el monóxido de carbono.Electrónicamente, la adsorción de CN en las superficies de oro es cualitativamente diferente de la de CO. La covalencia del enlace AuCN está apoyada por el análisis de cargas de Bader, las distancias de enlace y el análisis ELF. La adsorción de CN se incrementa ante la presencia de carga negativa o de compuestos electropositivos. El estudio apoya los mecanismos propuestos anteriormente, en los que la adsorción del primer grupo CN provoca la donación de un electrón a la superficie. La adsorción de un segundo grupo CN es termodinámicamente favorable y forma un precursor adecuado de la molécula soluble [Au(CN)2]. / In this dissertation, the mechanisms that govern four essential industrial processes have been studied by means of Density Functional Theory (DFT). The processes are the following: Ostwald (HNO3 production), Degussa and Andrussow (HCN production) and MacArthurForrest (gold recovery). In these processes, ammonia is the main raw material or a precursor of it.The KohnSham equations that describe the model systems have been solved by means of VASP and GPAW using the RPBE functional. These packages make use of periodic boundary conditions to simulate an infinite solid as model of the real metal surface.Ostwald Process: The first step of this process, NO formation, has been studied on the (111) and (211) surfaces of Au, Cu, Ir, Pd, Pt and Rh metals. The reactions involved have been analyzed as well in the PtRh alloy (the one used in industry). The thermodynamic stability of Pt and Rh oxides as a function of the temperature and the pressure of oxygen has been described. Finally, the volatility of these oxides has been calculated to determine catalyst loses in form of PtO2 and RhO2 gases.Good selectivity towards NO formation has been found for Pt metal. The desorption of NO has been found determinant for several metals that produce NO on the surface but hardly leaves it. The addition of Rh impurities to Pt does not increase its reactivity, but Rh oxides are more stable than Pt ones and Rh is less prone to form volatile oxides.Degussa and Andrussow Processes: The formation of CN bonds from individual atoms and hydrogenated moieties on a series of transition and noble metals has been studied there.A comprehensive study on all the possible couplings between partially hydrogenated species, CHx and NHy, on Pt(111) surface is shown. The differences between the mechanism under the distinct conditions (oxygen presence or absence) have been stressed. Under nonoxidative conditions, the coupling of partially hydrogenated species is found as the most effective way to form the CN bond on Pt. Under oxygen presence conditions, dehydrogenations are eased and C, CH and N are the most stable species.Thus, C+N and HC+N appear as the favoured paths for HCN formation.For the remainder metals, the basic steps under anaerobic conditions have been analysed. Correlations between the adsorption energy of the different species with the adsorption energy of nitrogen atom has been found. The dissociation energy for the most important reactions correlates as well with the adsorption energy of carbon atom.MacArthurForrest Process: In this Chapter, the interactions of cyanides with gold (111) and (211) surfaces have been analysed. A comparison with carbon monoxide interaction has been stated. Cyanides are the responsible of the solution of gold from its minerals by the formation of the watersoluble [Au(CN)2]molecule.On the other hand, CO affinity for metallic gold is very weak.A Bader analysis on the atomic charges and Localized Density Of States (LDOS) and Electronic Localization Function (ELF) studies are shown.Almost no interaction between CO and gold have been observed. CN bonding with gold have been described as covalent according to atomic charges, bond length and electronic analysis. The mechanism proposed by experimental works: CNadsorption, etransfer, second CNadsorption and elimination of the soluble compound, is supported by our theoretical approach.

The two-dimensional problem of tile drainage on sloping heterogeneous lands was considered. The land surface and the impermeable boundaries of the problem were of a general shape. The flow in both the saturated and unsaturated zones was considered and the system was treated as one composite system. The problem was solved by a finite difference numerical method using the successive over-relaxation iterative (SOR) method for the steady state case with no local recharge, and a combined Newton inner iteration and successive over-relaxation outer iteration for the transient state case with local recharge. Both the rising water table and the falling water table cases were simulated. A computer program was written in Fortrain IV language for this purpose, and a UNIVAC 1108 computer system was used. The results of two runs for a hypothetical problem and one run for a field testing problem are presented. The results were compared with some approximate mathematical solutions for the falling water table.

The removal of trace amounts of acetylene in ethylene streams is a high-volume industrial process that must possess high selectivity of alkyne hydrogenation over hydrogenation of alkenes. Current technology uses metallic nanoparticles, typically palladium or platinum, for acetylene removal. However, problems arise due to the deactivation of the catalysts at high temperatures as well as low selectivities at high conversions. Pore expanded MCM-41 is synthesized via a two-step strategy in which MCM-41 was prepared via cetyltrimethylammonium bromide (CTMABr) followed by the hydrothermal treatment with N,N-dimethyldecylamine (DMDA). This material was washed with ethanol to remove DMDA, or calcined to remove both surfactants. PE-MCM-41 based materials were impregnated with palladium, gold, and palladium-gold nanoparticles. The removal of DMDA had an effect on both the conversion and selectivity, in which they were found to drop significantly. However, by using the bimetallic PdAu catalysts, higher selectivity could be achieved due to increased electron density.

Orientador: Rodnei Bertazzoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-16T07:51:42Z (GMT). No. of bitstreams: 1 Oliveira_HenriqueVitorde_M.pdf: 4560558 bytes, checksum: 0df61e42792db8c18f8157701dd2a067 (MD5) Previous issue date: 2010 / Resumo: Por meio da técnica "core shell" foram produzidas micropartículas ocas e porosas de óxido de titânio IV (TiO2) para a utilização em processos de fotocatálise heterogênea. Inicialmente foram sintetizadas as matrizes de carbonato de cálcio (CaCO3) por meio da técnica de precipitação reativa, a qual baseia-se na interação do reagente aquoso hidróxido de cálcio com o gás dióxido de carbono em um meio poroso rotativo, em uma montagem do tipo da Máquina de Higee. Em seguida, as matrizes de carbonato de cálcio foram imersas em uma solução de um precursor polimérico de isopropóxido de titânio, prosseguindo com as etapas de secagem do solvente e calcinação. A seguir, o conjunto matriz-revestimento foi imerso em solução de ácido clorídrico para a dissolução do carbonato, dando origem às partículas ocas e porosas de TiO2. O pó resultante foi caracterizado por difração de R-X e microscopia eletrônica de varredura. Na seqüência, foi usado em um processo de fotocatálise heterogênea para a degradação do 17 ?- estradiol. A eficiência da degradação foi acompanhada por cromatografia líquida de alto desempenho / Abstract: In this investigation, hollow and porous microparticules of titanium dioxide IV (TiO2) were produced using a "core shell" system in which calcium carbobate microparticules were used as templates. Initially, templates of calcium carbonate (CaCO3) were synthesized using the technique of reactive precipitation, which is based in the interaction between the calcium hidroxide aqueous reagent and the carbon dioxide. Reaction took place in a Higee Machine type with a rotative porous element. In a sequence, the templates was immersed in a polimeric precursor solution of titanium isopropoxide, following the steps of solvent drying and calcination. Then, calcium carbonate matrix were remove by immersion in a hydrochloric acid solution. Final product was hollow and porous microparticules of TiO2. The powder was used in a heterogeneous fotocatalysis process for degradation 17 ?-estradiol. The efficiency of degradation was accompanied by high perfomance liquid chromatography / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

Ph.D. (Chemistry) / Please refer to full text to view abstract