Thesis--New York University, 1959. / Xerographic copy of typescript. Vol. 2: music. Bibliography: v. 1, leaves 202-207.

Thesis-New York University, 1959. / Xerographic copy of typescript. Vol. 2: music. Bibliography: v. 1, leaves 202-207.

Heidelberg, University, Diss., 2001.

Seminario de Título entregado a la Universidad de Chile en cumplimiento parcial de los requisitos para optar al Título de Bióloga con mención Medio Ambiente. / La pérdida y degradación de los bosques templados de Sudamérica son perturbaciones que alteran la estructura del hábitat, lo que puede repercutir negativamente sobre las especies dependientes del bosque, como es el caso de Dromiciops gliroides, un marsupial arbóreo endémico de estos bosques. Se espera que la ocurrencia y actividad de D. gliroides sea mayor en hábitats con menor grado de perturbación, ya que presentan una estructura vegetal más compleja, a diferencia de hábitats con mayor grado de perturbación, en los cuales la estructura vegetal es más simple, limitando su dispersión y refugio. Se realizó un monitoreo con cámaras trampa y se caracterizó la estructura vegetal de doce sitios con diferentes niveles de perturbación (bosque nativo, bosque secundario, bosque sujeto a tala y plantaciones forestales abandonadas) en el sur de Chile, en un rango norte-sur de 450 km, durante el verano austral (diciembre, 2017 a marzo, 2018). Se utilizaron Modelos Aditivos Generalizados Mixtos para determinar los factores que explican su ocurrencia a nivel regional, junto a un análisis de actividad. Dromiciops gliroides estuvo presente en todos los sitios, sin embargo, la ocurrencia y la actividad disminuyó al aumentar el grado de perturbación, con una actividad significativamente diferente entre bosque nativo-secundario y plantación. El porcentaje de arbustos fue la variable que explicó una mayor ocurrencia, tanto a escala regional como en la condición de bosque nativo. La ocurrencia fue mayor al inicio del verano en los sitios más perturbados y al final del verano en los sitios más conservados, probablemente debido a la abundancia de frutos maduros. En conclusión, la perturbación de hábitat altera la dinámica temporal (estacional y diaria) de D. gliroides, disminuyendo su ocurrencia y actividad. / Habitat loss and degradation are threatening the temperate forests of South America, bein likely to alter habitat structure. These structure changes can have negative impacts on forest dependent species, such as Dromiciops gliroides, an arboreal marsupial endemic to these forests. It is expected that D. gliroides occurrence and activity of will be higher in habitats with a lower disturbance degree, undisturbed sites present a more complex vegetation structure compared to the disturbed sites, where a simpler structure will be limiting dispersion and refuge. We conducted a camera-trap monitoring and characterized vegetation structure from twelve sites with different disturbance levels (primary forest, secondary forest, logged forest, and abandoned forest plantations) in southern Chile, in a 450-km north-south range during the austral summer (December 2017 to March 2018). Mixed Generalized Additive Models were used to determine the factors that explain the occurrence at regional level, along with an activity analysis. Dromiciops gliroides was present in all sampling sites, however, its occurrence and activity decreased as disturbance increased, finding significant activity differences between the secondary forest and the plantation. Shrub percentage was the variable that explained most of the variation in occurrence, both on a regional scale as well as in the native forest condition. Occurrence was higher at the beginning of the summer in the most disturbed sites, and at the end of summer in the most conserved sites, probably due to the abundance of ripe fruits. In conclusion, habitat disturbance alters D. gliroides temporal dynamics (seasonal and daily), decreasing their occurrence and activity. / Proyecto N° 111601 de FONDECYT.

No description available.

No description available.

There are few reliable computational techniques applicable to the problem of structural phase behaviour. This is starkly emphasised by the fact that there are still a number of unanswered questions concerning the solid state of some of the simplest models of matter. To determine the phase behaviour of a given system we invoke the machinery of statistical physics, which identifies the equilibrium phase as that which minimises the free-energy. This type of problem can only be dealt with fully via numerical simulation, as any less direct approach will involve making some uncontrolled approximation. In particular, a numerical simulation can be used to evaluate the free-energy difference between two phases if the simulation is free to visit them both. However, it has proven very difficult to find an algorithm which is capable of efficiently exploring two different phases, particularly when one or both of them is a crystalline solid. This thesis builds on previous work (Physical Review Letters 79 p.3002), exploring a new Monte Carlo approach to this class of problem. This new simulation technique uses a global coordinate transformation to switch between two different crystalline structures. Generally, this `lattice switch' is found to be extremely unlikely to succeed in a normal Monte Carlo simulation. To overcome this, extended-sampling techniques are used to encourage the simulation to visit `gateway' microstates where the switch will be successful. After compensating for this bias in the sampling, the free-energy difference between the two structures can be evaluated directly from their relative probabilities. As concrete examples on which to base the research, the lattice-switch Monte Carlo method is used to determine the free-energy difference between the face-centred cubic (fcc) and hexagonal close-packed (hcp) phases of two generic model systems --- the hard-sphere and Lennard-Jones potentials. The structural phase behaviour of the hard-sphere solid is determined at densities near melting and in the close-packed limit. The factors controlling the efficiency of the lattice-switch approach are explored, as is the character of the `gateway' microstates. The face-centred cubic structure is identified as the thermodynamically stable phase, and the free-energy difference between the two structures is determined with high precision. These results are shown to be in complete agreement with the results of other authors in the field (published during the course of this work), some of whom adopted the lattice-switch method for their calculations. Also, the results are favourably compared against the experimentally observed structural phase behaviour of sterically-stabilised colloidal dispersions, which are believed to behave like systems of hard spheres. The logical extension of the hard sphere work is to generalise the lattice-switch technique to deal with `softer' systems, such as the Lennard-Jones solid. The results in the literature for the structural phase behaviour of this relatively simple system are found to be completely inconsistent. A number of different approaches to this problem are explored, leading to the conclusion that these inconsistencies arise from the way in which the potential is truncated. Using results for the ground-state energies and from the harmonic approximation, we develop a new truncation scheme which allows this system to be simulated accurately and efficiently. Lattice-switch Monte Carlo is then used to determine the fcc-hcp phase boundary of the Lennard-Jones solid in its entirety. These results are compared against the experimental results for the Lennard-Jones potential's closest physical analogue, the rare-gas solids. While some of the published rare-gas observations are in approximate agreement with the lattice-switch results, these findings contradict the widely held belief that fcc is the equilibrium structure of the heavier rare-gas solids for all pressures and temperatures. The possible reasons for this disagreement are discussed. Finally, we examine the pros and cons of the lattice-switch technique, and explore ways in which it can be extended to cover an even wider range of structures and interactions.

This paper aims to practice the use of Monte Carlo methods to simulate stock prices in order to price European call options using control variates. American put options are priced using the binomial model separately. Finally, we use the information to form a portfolio position using an Interactive Brokers paper trading account.

This report describes our work in pricing options using computational methods. First, I collected the historical asset prices for assets in four economic sectors to estimate model parameters, such as asset returns and covariances. Then I used these parameters to model asset prices using multiple geometric Brownian motion and simulate new asset prices. Using the generated prices, I used Monte Carlo methods and control variates to price call options. Next I used the binomial tree model to price put options, which I was introduced to in the course Math 571: Financial Mathematics I. Using the estimated put and call option prices together with some stocks, I formed a portfolio in an Interactive Brokers paper account . This project was done a part of the masters capstone course Math 573: Computational Methods of Financial Mathematics.

by Tang Hing Sing. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1989. / Bibliography: leaves 92-96.