Influence of Water Depth on the Rate of Expansion of Giant Cutgrass Populations and Management Implications

Giant cutgrass ( Zizaniopsis miliacea (Michx.) Doell. & Asch.), a tall emergent grass native to the southeastern United States, was studied in Lake Seminole where it formed large expanding stands, and Lake Alice where it was confined to a stable narrow fringe.

A Semi-Empirical Equation of Penetration Depth on Concrete Target Impacted by Ogive-Nose Projectiles

In this paper, the penetration process of ogive-nose projectiles into the semi-infinite concrete target is investigated by the dimensional analysis method and FEM simulation. With the dimensional analysis, main non-dimensional parameters which control the penetration depth are obtained with some reasonable hypothesis. Then, a new semi-empirical equation is present based on the original work of Forrestal et al., has only two non-dimensional combined variables with definite physical meanings. To verify this equation, prediction results are compared with experiments in a wide variation region of velocity. Then, a commercial FEM code, LS-DYNA, is used to simulate the complex penetration process, that also show the novel semi-empirical equation is reasonable for determining the penetration depth in a concrete target.

Relationships between Initial Unloading Slope, Contact Depth, and Mechanical Properties for Spherical Indentation in Linear Viscoelastic Solids

Using analytical and finite element modeling, we examine the relationships between initial unloading slope, contact depth, and mechanical properties for spherical indentation in viscoelastic solids with either displacement or load as the independent variable. We then investigate whether the Oliver-Pharr method for determining the contact depth and contact radius, originally proposed for indentation in elastic and elastic-plastic solids, is applicable to spherical indentation in viscoelastic solids. Finally, the analytical and numerical results are used to answer questions raised in recent literature about measuring viscoelastic properties from instrumented spherical indentation experiments.

Determination of source finiteness and depth of large earthquakes

In this thesis, a method to retrieve the source finiteness, depth of faulting, and the mechanisms of large earthquakes from long-period surface waves is developed and applied to several recent large events.

In Chapter 1, source finiteness parameters of eleven large earthquakes were determined from long-period Rayleigh waves recorded at IDA and GDSN stations. The basic data set is the seismic spectra of periods from 150 to 300 sec. Two simple models of source finiteness are studied. The first model is a point source with finite duration. In the determination of the duration or source-process times, we used Furumoto's phase method and a linear inversion method, in which we simultaneously inverted the spectra and determined the source-process time that minimizes the error in the inversion. These two methods yielded consistent results. The second model is the finite fault model. Source finiteness of large shallow earthquakes with rupture on a fault plane with a large aspect ratio was modeled with the source-finiteness function introduced by Ben-Menahem. The spectra were inverted to find the extent and direction of the rupture of the earthquake that minimize the error in the inversion. This method is applied to the 1977 Sumbawa, Indonesia, 1979 Colombia-Ecuador, 1983 Akita-Oki, Japan, 1985 Valparaiso, Chile, and 1985 Michoacan, Mexico earthquakes. The method yielded results consistent with the rupture extent inferred from the aftershock area of these earthquakes.

In Chapter 2, the depths and source mechanisms of nine large shallow earthquakes were determined. We inverted the data set of complex source spectra for a moment tensor (linear) or a double couple (nonlinear). By solving a least-squares problem, we obtained the centroid depth or the extent of the distributed source for each earthquake. The depths and source mechanisms of large shallow earthquakes determined from long-period Rayleigh waves depend on the models of source finiteness, wave propagation, and the excitation. We tested various models of the source finiteness, Q, the group velocity, and the excitation in the determination of earthquake depths.

The depth estimates obtained using the Q model of Dziewonski and Steim (1982) and the excitation functions computed for the average ocean model of Regan and Anderson (1984) are considered most reasonable. Dziewonski and Steim's Q model represents a good global average of Q determined over a period range of the Rayleigh waves used in this study. Since most of the earthquakes studied here occurred in subduction zones Regan and Anderson's average ocean model is considered most appropriate.

Our depth estimates are in general consistent with the Harvard CMT solutions. The centroid depths and their 90 % confidence intervals (numbers in the parentheses) determined by the Student's t test are: Colombia-Ecuador earthquake (12 December 1979), d = 11 km, (9, 24) km; Santa Cruz Is. earthquake (17 July 1980), d = 36 km, (18, 46) km; Samoa earthquake (1 September 1981), d = 15 km, (9, 26) km; Playa Azul, Mexico earthquake (25 October 1981), d = 41 km, (28, 49) km; El Salvador earthquake (19 June 1982), d = 49 km, (41, 55) km; New Ireland earthquake (18 March 1983), d = 75 km, (72, 79) km; Chagos Bank earthquake (30 November 1983), d = 31 km, (16, 41) km; Valparaiso, Chile earthquake (3 March 1985), d = 44 km, (15, 54) km; Michoacan, Mexico earthquake (19 September 1985), d = 24 km, (12, 34) km.

In Chapter 3, the vertical extent of faulting of the 1983 Akita-Oki, and 1977 Sumbawa, Indonesia earthquakes are determined from fundamental and overtone Rayleigh waves. Using fundamental Rayleigh waves, the depths are determined from the moment tensor inversion and fault inversion. The observed overtone Rayleigh waves are compared to the synthetic overtone seismograms to estimate the depth of faulting of these earthquakes. The depths obtained from overtone Rayleigh waves are consistent with the depths determined from fundamental Rayleigh waves for the two earthquakes. Appendix B gives the observed seismograms of fundamental and overtone Rayleigh waves for eleven large earthquakes.

Continuous radial superresolution filters with large focal depth

A new set of continuous superresolution filters is proposed which exhibits a radial superresolution performance with an extended depth of focus in an optical system by properly choosing the design parameters. Numerical simulation results of the performance parameters of the superresolution gain, the radial central core size, the Strehl ratio, the side-lobe factor and the depth of focus with different design parameters for the optimized patterns are displayed. We also give a design example for this kind of filter characterized by a birefringent element inserted between two parallel polarizers. This kind of filter would be useful in fields such as optical data storage systems.

Influência do sistema de cimentação e do modo de ativação na resistência ao push-out de pinos de fibra de vidro

O objetivo deste estudo foi avaliar a influência do tipo de sistema de cimentação (condicionamento ácido total ou autoadesivo), do modo de ativação (autoativado ou dual), do terço do conduto radicular (cervical, médio ou apical) e da espessura do filme de cimento sobre a resistência de união de pinos de fibra de vidro cimentados em dentes humanos. Quarenta raízes foram incluídas em resina epóxi, submetidas a tratamento endodôntico e obturadas com guta percha e cimento endodôntico sem eugenol. Decorridos sete dias, os condutos foram preparados a uma profundidade de 10mm com brocas padronizadas do sistema dos pinos de fibra (WhitePost DC #2) e aleatoriamente divididos em 4 grupos, conforme o sistema de cimentação e o modo de ativação: (G1) RelyX ARC/Adper Scotchbond Multi-Purpose Plus (condicionamento ácido total), ativação dual, (G2) RelyX ARC/Adper Scotchbond Multi-Purpose Plus, autoativado, (G3) RelyX U100 (autoadesivo), dual e (G4) RelyX U100, autoativado. Após uma semana, cada raiz foi seccionada em máquina de corte, originando 6 fatias de 1 mm de espessura (n=60). Antes do ensaio de push-out cada fatia foi fotografada em ambas as faces, para determinação do raio dos pinos e da espessura do filme de cimento. Após o ensaio mecânico, novas imagens foram capturadas para determinação do modo de falha. Para automatizar a determinação da espessura de cimento, foi desenvolvida uma macro no software KS 400. Os dados foram estatisticamente analisados com ANOVA 3 fatores (resistência de união) e teste de Kruskall-Wallis (espessura do cimento). Comparações múltiplas foram realizadas com o teste Student-Newman-Keuls. Análise de regressão, modelo linear, foi empregada para verificar a correlação entre espessura do cimento e resistência de união. Todos os testes foram aplicados com α = 0,05. O fator cimento exerceu influência significativa para a resistência de união (p = 0,0402): o RelyX U100 apresentou a maior média. A ativação dual elevou os valores de resistência de união em comparação ao modo quimicamente ativado (p < 0,0001). Houve diferenças significantes entre os grupos, sendo G1 (22,4 4,0 MPa) > G3 (20,4 3,6 MPa) > G4 (17,8 5,2 MPa) > G2 (13,5 4,3 MPa). O terço do conduto não exerceu influência significativa sobre a resistência adesiva (p = 0,4749). As espessuras dos filmes de cimento foram estatisticamente diferentes nos diferentes terços: cervical (102 45 m) > médio (75 29 m) > apical (52 28m). Não foi observada forte correlação entre os valores de espessura e os de resistência ao push-out (r = - 0,2016, p = 0,0033). O tipo de falha predominante foi a mista, exceto para o G2, que apresentou 74% das falhas na interface cimento-pino. Dessa forma, o cimento autoadesivo apresentou melhor desempenho que o convencional, e ambos os sistemas duais, sobretudo o RelyX ARC, apresentaram dependência da fotoativação para atingirem maiores valores de resistência de união.

A papaína no tratamento da periodontite crônica

A raspagem subgengival e o alisamento radicular constituem o "padrão ouro" e o tratamento de eleição para a periodontite; porém, é um procedimento difícil de ser executado, que requer um intenso treinamento e que pode expor a dentina, causando hipersensibilidade dentinária pela remoção excessiva de cemento, ou produzir defeitos, como sulcos e ranhuras, além de deixar cálculo residual e não conseguir atingir toda as superfície radicular. Recentemente, um gel a base de papaína e cloramina foi introduzido no mercado (Papacárie), utilizado no tratamento da remoção de dentina cariada. Este gel poderia auxiliar na remoção do cálculo subgengival com menor desgaste do cemento. O objetivo deste trabalho foi comparar a eficácia e analisar a superfície radicular na utilização de um gel à base de papaína e cloramina, associado ao alisamento radicular, na região subgengival. Após receberem instruções de higiene oral, raspagem supragengival e polimento coronário, 18 pacientes com periodontite crônica, 6 mulheres e 12 homens, com idade média de 51 anos (8) foram tratados num modelo de boca dividida. O tratamento-teste foi constituído pela aplicação do gel na área subgengival por 1 min., seguida pelo alisamento radicular; o tratamento-controle foi constituído pela raspagem subgengival e alisamento radiculares. A terapia foi executada por 3 operadoras e os exames inicial, de 28 dias e 3 meses, foram realizados por um único examinador. Quatro dentes nunca tratados de dois outros pacientes (2 incisivos centrais inferiores e 2 premolares), com indicação para extração, foram submetidos ao tratamento teste e controle e, após a exodontia, analisados em microscopia eletrônica de varredura (MEV). Ao longo dos 3 meses, os resultados demonstraram significativa melhora nos parâmetros clínicos: sangramento à sondagem, profundidade de bolsa e ganho de inserção, tanto no lado-teste, como no lado-controle, principalmente aos 28 dias; mas não foi observada significância estatística quando ambas as formas de terapia foram comparadas. O índice de placa médio permaneceu alto ao longo do estudo. A análise do MEV demonstrou que o tratamento-teste deixou uma maior quantidade de cálculo residual sobre a superfície radicular; porém, áreas livres de cálculo também foram observadas. No tratamento-controle, verificaram-se regiões mais profundas não atingidas pelas curetas, áreas livres de cálculo e um sulco produzido pela cureta. Concluiu-se que tanto o tratamento-teste, como o controle, foram eficazes no tratamento da periodontite crônica nos 3 meses observados.

Enlarging the depth of focus by filtering in the phase-space domain

The ambiguity function was employed as a merit function to design an optical system with a high depth of focus. The ambiguity function with the desired enlarged-depth-of-focus characteristics was obtained by using a properly designed joint filter to modify the ambiguity function of the original pupil in the phase-space domain. From the viewpoint of the filter theory, we roughly propose that the constraints of the spatial filters that are used to enlarge the focal depth must be satisfied. These constraints coincide with those that appeared in the previous literature on this topic. Following our design procedure, several sets of apodizers were synthesized, and their performances in the defocused imagery were compared with each other and with other previous designs. (c) 2005 Optical Society of America.

Analysis of optical systems with extended depth of field using the Wigner distribution function

We describe the use of a Wigner distribution function approach for exploring the problem of extending the depth of field in a hybrid imaging system. The Wigner distribution function, in connection with the phase-space curve that formulates a joint phase-space description of an optical field, is employed as a tool to display and characterize the evolving behavior of the amplitude point spread function as a wave propagating along the optical axis. It provides a comprehensive exhibition of the characteristics for the hybrid imaging system in extending the depth of field from both wave optics and geometrical optics. We use it to analyze several well-known optical designs in extending the depth of field from a new viewpoint. The relationships between this approach and the earlier ambiguity function approach are also briefly investigated. (c) 2006 Optical Society of America.