We generalize bistellar operations (often called flips) on simplicial manifolds to a notion of general flips on PL-spheres. We provide methods for computing the cd-index of these general flips, which is the change in the cd-index of any sphere to which the flip is applied. We provide formulas and relations among flips in certain classes, paying special attention to the classic case of bistellar flips. We also consider questions of "flip-connecticity", that is, we show that any two polytopes in certain classes can be connected via a sequence of flips in an appropriate class.

Doctor of Philosophy / Department of Statistics / Juan Du / It is common to assume the spatial or spatio-temporal data are realizations of underlying random elds or stochastic processes. E ective approaches to modelling of the underlying autocorrelation structure of the same random eld and the association among multiple processes are of great demand in many areas including atmospheric sciences, meteorology and agriculture. To this end, this dissertation studies methods and application of the spatial modeling of large-scale dependence structure and spatio-temporal regression modelling. First, variogram and variogram matrix functions play important roles in modeling dependence structure among processes at di erent locations in spatial statistics. With more and more data collected on a global scale in environmental science, geophysics, and related elds, we focus on the characterizations of the variogram models on spheres of all dimensions for both stationary and intrinsic stationary, univariate and multivariate random elds. Some e cient approaches are proposed to construct a variety of variograms including simple polynomial structures. In particular, the series representation and spherical behavior of intrinsic stationary random elds are explored in both theoretical and simulation study. The applications of the proposed model and related theoretical results are demonstrated using simulation and real data analysis. Second, knowledge of the influential factors on the number of days suitable for fieldwork (DSFW) has important implications on timing of agricultural eld operations, machinery decision, and risk management. To assess how some global climate phenomena such as El Nino Southern Oscillation (ENSO) a ects DSFW and capture their complex associations in space and time, we propose various spatio-temporal dynamic models under hierarchical Bayesian framework. The Integrated Nested Laplace Approximation (INLA) is used and adapted to reduce the computational burden experienced when a large number of geo-locations and time points is considered in the data set. A comparison study between dynamics models with INLA viewing spatial domain as discrete and continuous is conducted and their pros and cons are evaluated based on multiple criteria. Finally a model with time- varying coefficients is shown to reflect the dynamic nature of the impact and lagged effect of ENSO on DSFW in US with spatio-temporal correlations accounted.

Orientador: Carlos Eduardo Duran Fernandez / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-14T00:21:52Z (GMT). No. of bitstreams: 1 Speranca_LlohamDallagnol_M.pdf: 1442574 bytes, checksum: eec573204734790dd464f4ba0a79d6c5 (MD5) Previous issue date: 2009 / Resumo: Apresentaremos neste trabalho alguns dos modelos clássicos em geometria e topologia diferencial para algumas variedades diferenciáveis com o mesmo tipo homotópico de uma esfera. Em seguida apresentaremos construções mais recentes dos mesmos e algumas de suas propriedades. / Abstract: We show in this work some of the classical models in geometry and diferential topology for some diferentiable manifolds with the same homotopy type of the sphere. We follow with an exposition of recent work and some of its properties. / Mestrado / Topologia / Mestre em Matemática

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Matrizes inorgÃnicas tÃm sido utilizadas como materiais adsorventes para remoÃÃo de poluentes quÃmicos em sistemas aquÃticos, dada Ãs suas boas capacidades de adsorÃÃo e estabilidades fÃsicas e quÃmicas Neste trabalho, foi sintetizado esferas de sÃlica funcionalizadas com EDTA com a finalidade de remover Ãons metÃlicos em soluÃÃo aquosa. A cinÃtica de adsorÃÃo dos Ãons em estudo (Cu2+, Cd2+ e Zn2+) foi feita em pH 5,5 numa concentraÃÃo de 60 mg L-1, onde se observou que o equilÃbrio à atingido extremamente rÃpido, cerca de 10 minutos, o que indica que a etapa limitante do processo de adsorÃÃo pode ser a quimissorÃÃo, evidenciado pelos melhores ajustes para o modelo de pseudo-segunda ordem. As isotermas de adsorÃÃo foram submetidas ao modelo linear e nÃo linear para efeito de comparaÃÃo, utilizando o R2 e funÃÃo erro SSE como referencia. O estudo com sistema simples e multielementar dos Ãons foi realizado em pH 5,5, concentraÃÃes variando de 10-300 mg L-1, onde os dados foram submetidos aos modelos de Langmuir, Freundlich, Temkin e Redlich-Peterson. Os resultados evidenciaram um melhor ajuste para o modelo de Langmuir, o qual defende que os sÃtios de adsorÃÃo sÃo homogÃneos e adsorÃÃo à em monocamada. As capacidades mÃximas de adsorÃÃo observadas nos estudos de equilÃbrio para o sistema mono e multielementar seguem a ordem Cu2+> Zn2+> Cd2+. Para efeito de comparaÃÃo de modelos foi utilizado o mÃtodo de AKAIKEÂS onde comprovou que os resultados se ajustam melhor ao modelo de Langmuir. Com respeito ao estudo de adsorÃÃo em coluna, as curvas de ruptura indicaram que a saturaÃÃo da mesma ocorre num volume de 35 mL. O uso do eluente HCl 0,1 M, permitiu recuperar 100% dos Ãons adsorvidos. A coluna foi utilizada por trÃs ciclos para verificar seu potencial de uso, e foi comprovado que nos trÃs ciclos consegue-se recuperar 100% dos metais, o que significa uma Ãtima eficiÃncia das esferas de sÃlica-APTS-EDTA. / Inorganic matrices have been used as adsorbent mate rial for removal of chemical pollutants in aquatic systems, due to its good adsorption capacity for physical and chemical stabilities and this work was synthesized silica spheres functionalized with EDTA in order to remove metal i ons in aqueous solution . The kinetics of adsorption of the ions under study (Cu 2 + , Cd 2 + and Zn 2 + ) was performed at pH 5.5 at a concentration of 60 mg L -1 , where it was observed that equilibrium is reached very fast, about 10 minutes, indicating tha t limiting step of the adsorption process may be the chemisorption, as evidenced by t he best fitting model for the pseudo-second order. The adsorption isotherms were subjected to linear and nonlinear model for comparison, using the error fun ction SSE and R 2 as a reference. The study of simple and multielement ions was carri ed out at pH 5.5, concentrations ranging from 10-300 mg L -1 , where the data were submitted to the models of Langmuir, Freundlich, Temkin and Redlich-Peterson. The results showed a better fit to the Langmuir model, which argues that the adsorp tion sites are homogeneous and monolayer adsorption. The maximum sorption capaciti es observed in studies of equilibrium for the system mono and multielement fo llow the order Cu 2 + > Zn 2 + > Cd 2+. For comparison model method was used Akaike's whe re proved that the Langmuir model is the best. With respect to the stu dy of adsorption column, the breakthrough curves indicate that saturation occurs in the same volume of 35 mL. The use of the eluent 0.1 M HCl, allowed to recover 100% of the adsorbed ions. The column was used for three cycles to verify their po tential use, and it was proved that in the three-cycles can recover 100% of the metals, which means an optimum efficiency of the spheres of silica-APTS-EDTA.

Foi estudada a cristalização de suspensões aquosas de esferas de poliestireno (850&#197, 910&#197 e 1090&#197 de diâmetro) no limite de baixas concentrações -1011 a 1013 esferas / cm3. A dependência do parâmetro de rede com a concentração original (n) da suspensão aquosa apresenta uma transição de fase da fase bcc para fcc, conforme já foi observada por outros autores. Observamos também que durante a cristalização a concentração de esferas no cristal Ra sistematicamente maior do que na solução original, portanto a água estaria sendo expelida para a solução durante a cristalização. Baseado nestas observações nós propomos um modelo de cristalização onde os cristalites (concentração n1) estão em equilíbrio termodinâmico com uma solução com concentração n2 (n1&#62 n &#62 n2), dando para cada concentração inicial um diferente parâmetro de rede determinado por este equilíbrio. Nossos resultados mostraram que o coeficiente de expulsão da água durante a cristalização é dependente do raio da esfera. Para realizar as medidas de parâmetro de rede nós adaptamos para as nossas condições particulares o método de Debye-Scherrer usado em difração de raios-X por cristais. O equivalente à fonte de raios-X era um laser de Argônio com comprimentos de onda variáveis. Diversas experiências novas são sugeridas. / The crystallization of aqueous suspensions of polystyrene spheres 850&#197, 910&#197 and 1090&#197 of diameter) was studied in the limit of low concentration -1011 to 1013 spheres / cm3. The dependence of the lattice parameter with the original concentration (n) of the aqueous suspension shows a phase transition from bcc to fcc phase as it was already been observed by others authors. We also observed that during crystallization the concentration of spheres in the crystal was systematically higher than in the original solution, showing that water should be expelled toward the solution during crystallization where the crystallites (concentration n1) are in thermodynamic equilibrium with a solution with concentration n2 (n1&#62 n &#62 n2) giving for each initial concentration a different lattice parameter determined by this equilibrium. Our results showed that coefficient of water rejection during crystallization is dependent on the sphere radius. In order to make the measurements of the lattice parameter we adapted to our particular conditions the Debye-Scherrer method used in X-ray diffraction of crystals. The equivalent to the X-ray source was a tunable Argon laser. Several new experiments are suggested.

This PhD thesis is concerned with developing a methodology for early diagnosis of cancer by comparing the resonant frequencies in the amplitude spectra obtained during a vibration test using the AFM or, by comparing the stiffness properties of single cancerous and normal cells obtained using a resonant technique. As there is no reliable data in the literature to prove the existence of resonant frequencies of single cells, this work pioneers the search for resonant frequencies of related microspherical soft bodies using the AFM. Experiments to investigate the resonant behaviour of single cells depends on various parameters which are difficult to control; for example, the cell type, deciding at what stage the cell should be tested during the culturing process, determining the nucleus size, determining the cytoskeleton integrity and designing an appropriate vibration test setup among others. For this reason, agarose microspheres were selected to carry out preliminary work as these samples have similar properties to human cells and their resonances are affected by fewer variables. Although these micrometric spheres were tested under different conditions, no clear resonant behaviour was found at frequencies below 20 kHz and, only wide curves (interpreted as highly damped peaks of resonance) in the interval ranging from 20 kHz to 100 kHz were observed. By considering those curves as the quadrupole (Qp) vibration mode, approximate stiffness values for the agarose microspheres were found to be in between 37 kPa and 72 kPa. These values are similar to those obtained during an indentation test performed on the same samples whic¬¬h gave Young’s modulus values ranging from 10 kPa to 200 kPa. In order to gain a greater insight into the vibration test performed on microscopic samples, the research was extended to include agarose spheres of millimetric size. The characterization of these samples was carried out using an innovative purpose-built experimental setup. For the vibration test, a PZT based excitation device and a vibro-acoustic sensor were designed and constructed. The amplitude spectra of the vibration tests performed on millimetric samples consistently showed at least three peaks of resonance from which after the numerical simulation of the vibration test were interpreted as the quadrupole (Qp) and octupole (Op) vibration modes. Using this information, stiffness values for the samples ranging from 100 kPa to 700 kPa were calculated. In order to obtain the stiffness of the millimetric samples using a different technique, an experimental setup was constructed to perform a compression test. However, due to high viscoleasticity of the samples, it was not possible to obtain a standard compression curve necessary for their mechanical characterization. The results obtained from the tests on millimetric agarose samples demonstrate that spheres made of this material are able to provide measurable vibrational characteristics. Consequently, this methodology can be further implemented on micrometric samples and possibly on human cells to detect their resonant frequencies and equivalent stiffness values which can be used as a cancer marker. From the vibrational experiments on millimetric samples, it was noticed that the excitation mechanism plays an important role and for this reason future work is proposed to continue in this direction.

Detonation waves in gases are very complex, involving a highly transient cellular structure and a turbulent reaction zone coupled with transverse shocks. The role of out-of-equilibrium phenomena in these waves remains unclear despite extensive research on the underlying physics. On the small scales, translational non-equilibrium associated with shocks, as postulated by Zel’dovich, may significantly affect the chemistry, and these effects are not yet fully understood. Similarly, very fast chemical processes may involve out-of-equilibrium effects due to local energy release that has been postulated by Prigogine. On larger scales, detonation waves display a cellular structure and are supported by turbulent combustion. The present thesis aims to quantify the importance of these three out-of-equilibrium effects on ignition, wave amplification, and diffraction limits of detonations. First, the role of translational non-equilibrium in reactive dynamics in the thermal explosion problem is investigated using molecular dynamics (MD) simulations and continuum models. Ignition delays are calculated and compared with rates from kinetic theory. MD results show agreement with the Prigogine and Mahieu corrections to the reaction rate evaluated from kinetic theory assuming a Maxwell-Boltzmann distribution. Accounting for the departure from translational equilibrium was found to reduce the ignition delay by up to 30% specifically at high activation energies. However, at low activation energies, the standard equilibrium rate shows a longer delay by up to 60%. The molecular dynamics simulations reveal that translational non-equilibrium effects accelerate activated exothermic reactions, referred to as “molecular hotspots”. The second part of the study focuses on the impact of thermal non-equilibrium and its coupling with reactive kinetics in shock-to-detonation transitions in gases. Results suggest that shock-induced ignition and transition to detonation involve non-equilibrium reactions that overlap with the shock structure, showing strong translational non-equilibrium with reactive fingers. Comparison with continuum simulations using different approximations reveals that shock amplification rate and transition to detonation are approximately twice as fast as predicted by conventional Euler hydrodynamic models, despite evidence of non-equilibrium. A Navier-Stokes model with hard sphere transport properties effectively captures the acceleration process, indicating significant implications for modeling gaseous detonations with fast reactions and strongly coupled pressure wave dynamics and reactivity in the detonation structure. In the last part of the thesis, the 3D hydrodynamic structure of cellular detonations is modeled by a global 1D mean hydrodynamic average model. Transport properties are artificially increased to account for the high-speed behavior resulting from fast turbulent diffusion. The existence of steady state Navier-Stokes detonation structure, as studied by Wood, is critically reviewed for this purpose and compared with transient calculations. Observations reveal that in the hyper-diffuse model, the shock and reaction zone overlap, resulting in a thickened reaction zone. The 1D model is used to study diffraction dynamics, with critical diffraction occurring when the tube diameter approaches the hydrodynamic reaction zone thickness. After diffraction, the complex viscous detonation structure separates, resulting in a rapid flame transitioning into a weak detonation. The conclusion of the present survey on the role of out-of-equilibrium effects on detonation dynamics suggests that non-equilibrium ignition due to molecular hotspots may give rise to corrections on the reaction rates by at most a factor of two. The coupling of exothermic reactions with the non-equilibrium structure of shock waves also predicts rates of shock amplification different by a factor of two from the standard Euler model for ignition, but accounting for the diffusive effects brings the MD and continuum predictions into closer agreement. Similarities with the out-of-equilibrium hydrodynamic structure of detonations are discussed.

<p> Polymers and block copolymers have been grafted from hard and soft polymer micro-spheres by atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). The hard and soft micro-spheres were prepared by precipitation polymerization of divinylbenzene-80 (DVB80), and of DVB80/hydroxyethylmethacrylate (HEMA), respectively, in neat acetonitrile.</p> <p> Residual vinyl groups in the hard, poly(DVB80) micro-spheres were hydrochlorinated to form benzyl chloride groups that subsequently served as ATRP initiators for poly(styrene) and poly(styrene-block-4-methylstyrene) grafts. Hydrophilic poly(HEMA) and poly(2-( dimethylamino)ethyl methacrylate) poly(DMAEMA) were also grafted from hard micro-spheres containing bromopropionates, using ATRP in the presence of CuBr/Me4Cyclam.</p> <p> Hydroxy groups in soft, poly(DVB80-co-HEMA) micro-spheres were used directly as initiators for ring opening polymerization of ε-caprolactone catalyzed by aluminum compounds. In the addition, they were reacted with α-bromopropionyl bromide to form ATRP initiators.</p> <p> Several combinations of ATRP-ATRP and ROP-ATRP with different monomers were carried out using these initiator micro-spheres. In particular, the soft micro-spheres grafted with poly(methacrylic acid), poly(methylmethacrylate), poly(methylmethacrylate-block-dimethylaminoethylmethacrylate), poly(methylmethacrylate-block-trimethylammoniumethylmethacrylate), poly(methylmethacrylate-block-HEMA), poly(methylmethacrylate-block-glycidylmethacrylate), poly(ε-caprolactone-block- methylmethacrylate), poly(ε-caprolactone-block-dimethylaminoethylmethacrylate).</p> <p> The internal morphology of these homo and block copolymer grafted microspheres was studied using electron microscopy and x-ray microspectroscopy.</p> / Thesis / Doctor of Philosophy (PhD)

<p> An investigation is reported of oxygen diffusion in monoclinic zirconia at elevated temperatures. </p> <p> A method was developed for production of solid zirconia spheres of a quality suitable for diffusion measurements. The spheres, 60μ and 90μ diameter were subsequently used for the determination of the coefficient of self-diffusion of oxygen in stoichiometric zirconia at 800°C, 850°C, 900°C, 950°C and 1000°C. Oxygen O18 isotope exchange using mass spectrometry for the gas analysis was employed for this investigation. </p> <p> The oxygen self-diffusion coefficent was found to conform to the Arrhenius equation (see online text for equation) Theoretical considerations indicate that this diffusivity represents virtually the lattice diffusion of oxygen in zirconia. </p> <p> Diffusivities of oxygen in zirconia scale calculated from zirconium oxidation studies are 104 times higher and are believed to be due to short-circuit diffusion through line defects. To substantiate this hypothesis, "slabs" of stoichiometric zirconia scale and irregular, but equiaxed particles of the same material were used for oxygen diffusion experiments employing the same method. The diffusivities for the slabs were 10^3 times higher than those for spheres, supporting the validity of the short-circuit diffusion theory for zirconia scale. </p> <p> Oxygen concentration drop across zirconia scale on metal, during its formation by parabolic kinetics was calculated for 600°C and 850°C, and was found to be 0.04 g/cm3 approximately, while the concentration drop across the interface between the oxide and the oxygen-saturated metal was about 1.07 g/cm3. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.