Strong field approximation (SFA) is the most important approximation in the analytical theory of intense laser matter interaction. Based on SFA many analytical theories have been developed such that a broad spectrum of strong field physics phenomena can be described. The central idea of SFA-based theories is to approximate the electron propagation in the continuum by the Gordon-Volkov wavefunction - a well studied analytical solution to the time-dependent Schr\"{o}dinger equation where the electron is driven by the laser field only. This approximation captures some of the essential features of strong-field physics, but at the same time causes several problems in the theory. In this thesis a comprehensive study of the SFA has been presented. We introduce the SFA in both the length gauge and the velocity gauge. The adequacy of SFA has been discussed by comparing the theory to the numerical solution to the time-dependent Schr\"{o}dinger equation (TDSE). The numerical method of solving TDSE is presented as a separate chapter. In order to obtain a better understanding of the applicability of SFA-based theory, we tested the major approximations in the theory by using three different models: the zero-range potential, the hydrogen atom and the hydrogen molecular ion. The accuracy of the method of steepest descent (MSD) and other major approximations in the analytical theory have also been examined. Targeting at the generalization of the SFA-based theories, several extensions and improvements of SFA have been proposed. We will review them in detail and bring them into unity. One of the most successful aspect of the SFA-based theories is to describe and decompose electron dynamics into components such that identification of different physical processes becomes possible. For instance, the direct ionization and non-sequential double ionization bear clear definitions only within the SFA-based framework. The physical interpretation becomes more straight forward due to the fact that there is a close connection between the quantum orbital and classical trajectory. The MSD is a mathematical tool to bridge the quantum orbital and the classical trajectory in an SFA-based theory. We will discuss MSD within a systematic framework so that the higher order asymptotic expansion terms can be obtained in a straight forward way. After gaining substantial understanding of the SFA and the MSD we developed a graphic user interface (GUI) software that is capable of calculating strong field ionization rates, photo-electron spectra and high harmonic generation spectra. The software interface and algorithms have been presented in the thesis. Sample calculations were done and compared with the previously obtained results. In the last chapter of the thesis, we further developed the theory to describe a two-laser ionization scheme where one laser is chosen to be resonantly coupled two real states and the other is a strong few-cycle laser pulse. We demonstrate the periodic dependence of the total ionization on the appearance time of the strong few-cycle laser pulse. In the case of few-cycle pulses with lower intensity, we observed side-bands in the photoelectron spectrum, whose intensity vary periodically with the appearance time of the pulse. We show that our extended theory is able to explain these phenomena adequately.

No description available.

Strong field approximation (SFA) is the most important approximation in the analytical theory of intense laser matter interaction. Based on SFA many analytical theories have been developed such that a broad spectrum of strong field physics phenomena can be described. The central idea of SFA-based theories is to approximate the electron propagation in the continuum by the Gordon-Volkov wavefunction - a well studied analytical solution to the time-dependent Schr\"{o}dinger equation where the electron is driven by the laser field only. This approximation captures some of the essential features of strong-field physics, but at the same time causes several problems in the theory. In this thesis a comprehensive study of the SFA has been presented. We introduce the SFA in both the length gauge and the velocity gauge. The adequacy of SFA has been discussed by comparing the theory to the numerical solution to the time-dependent Schr\"{o}dinger equation (TDSE). The numerical method of solving TDSE is presented as a separate chapter. In order to obtain a better understanding of the applicability of SFA-based theory, we tested the major approximations in the theory by using three different models: the zero-range potential, the hydrogen atom and the hydrogen molecular ion. The accuracy of the method of steepest descent (MSD) and other major approximations in the analytical theory have also been examined. Targeting at the generalization of the SFA-based theories, several extensions and improvements of SFA have been proposed. We will review them in detail and bring them into unity. One of the most successful aspect of the SFA-based theories is to describe and decompose electron dynamics into components such that identification of different physical processes becomes possible. For instance, the direct ionization and non-sequential double ionization bear clear definitions only within the SFA-based framework. The physical interpretation becomes more straight forward due to the fact that there is a close connection between the quantum orbital and classical trajectory. The MSD is a mathematical tool to bridge the quantum orbital and the classical trajectory in an SFA-based theory. We will discuss MSD within a systematic framework so that the higher order asymptotic expansion terms can be obtained in a straight forward way. After gaining substantial understanding of the SFA and the MSD we developed a graphic user interface (GUI) software that is capable of calculating strong field ionization rates, photo-electron spectra and high harmonic generation spectra. The software interface and algorithms have been presented in the thesis. Sample calculations were done and compared with the previously obtained results. In the last chapter of the thesis, we further developed the theory to describe a two-laser ionization scheme where one laser is chosen to be resonantly coupled two real states and the other is a strong few-cycle laser pulse. We demonstrate the periodic dependence of the total ionization on the appearance time of the strong few-cycle laser pulse. In the case of few-cycle pulses with lower intensity, we observed side-bands in the photoelectron spectrum, whose intensity vary periodically with the appearance time of the pulse. We show that our extended theory is able to explain these phenomena adequately.

A Surface Forces Apparatus (SFA) was used in this study to investigate the fundamental surface forces in oil sand processing research. Asphaltene coated surfaces were chosen as the research topic due to the critical role of asphaltenes in oil sands processing, from bitumen extraction, froth treatment to tailings treatment. To mimic the real surface state in industry processing, dip-coated asphaltene surfaces were prepared for surface force experiments. In this study, a SFA 2000 was used to determine intermolecular and surface forces of asphaltene in organic solvents (toluene and heptane). The force vs. distance curves, or so-called force profiles obtained provide valuable information on local material properties such as interaction energies, molecular conformation changes of the interacting asphaltene surfaces or films. Atomic force microscopy (AFM) was used to provide complementary information on the surface morphology of the prepared asphaltene surfaces. / Chemical Engineering

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Local land administration office is to execute registering of lands and buildings. Its objective is to implement local land policy. In the mean time, its functions are about citizen¡¦s property rights. Because the social, economy and political environment have been changed rapidly, demands for land administration and service quality have been growing as well. Therefore, the first priority work for government is to improve whole administrative efficiency and effectiveness, by using modern technology. It thus needed to electronic-wise land office, to set up a computerization system of land information management so as to provide complete land information, to execute modern administration, to promote competition, and to provide convenient and efficient services. Therefore, the purpose of this study is to research these first-line local offices so as (i) to promote its efficiency after being computerized (ii) to compare the implementing result before and after the computerization in Kaohsiung county and city, and (iii) to study the influences of the computerized process, finally (iv) to suggest local offices decision makers the future direction of improvement. This study uses DEA and SFA to compute their efficiency after computerization of the local land offices in Kaohsiung county and city. To do this, we collect annually statistics and use DEA-Solver software and Frontier 4.1 computer program to evaluate their productivities, and to make an efficiency analysis. The results revealed that the annual average technology efficiency descended before computerization and ascended after computerization for all land offices. CCR model revealed that annual averages of technology efficiency are stable before computerization and it ascended after computerization for all land offices. SFA analysis revealed that annual averageefficiency score slightly ascends before computerization and ascends after computerization except for year 2001. For technology changes, their productivities slightly descends for all land offices in Kaohsiung county but ascends for all land offices in Kaohsiung city. For efficiency slack analysis, all five land offices must reduce their inputs in Kaohsiung county. For output slack, only Chi-Shang land office must expand its output 13.01% so as to reach a relatively inefficient DMU. Between the Kaohsiung county and city, information difference between city and country has influences on efficiency. Land offices in Kaohsiung city have general higher average technology efficiency than those in Kaohsiung county. This study uses DEA and SFA to analyze land offices in Kaohsiung county and city, and it was found that whole efficiency scores increased after computerization. And it is suggested several important problems and the possible directions of productivity improvement in the future for all land offices.

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The Master's thesis deals with the effect of feed enrichment with various types of oils on the deposition of fatty acids in selected tissues. Forty male Wistar Albino rats were divided into four groups and fed for 10 weeks daily ad libitum with a basic feed mixture enriched with 8 % palm, 8 % safflower, 8 % fish oil or 8 % microalgae Schizochytrium sp. oil. Rats had also free access to the drinking water. Fat from the tissue samples (liver, muscle, visceral fat) was extracted, converted to methyl esters and analyzed with usage of gas chromatography. The results of the experiment show that the addition of various types of oils to the feed of model organism can influence the deposition of fatty acids in its tissues. The addition of fish oil and microalgae Schizochytrium sp. oil caused statistically significant decrease (p < 0,05) in the ratio of PUFA n-6/n-3 in all observed tissues to a value of 1 or less compared to the addition of palm and safflower oil. Low ratio of n-6/n-3 polyunsaturated fatty acids is considered to be more desirable in reducing the risk of cardiovascular diseases.

Bacterial adhesion is the first step of biofilm formation that plays various roles in the environment and the human body. Examples of undesirable roles of biofilm formation include metal rust, sewage sludge and bacteria-related diseases. Desirable roles are biofiltration and bioremediation.For a decade, Atomic Force Microscopy (AFM) has been the primary tool used to study the adhesion and elastic properties of individual bacteria. In this work we show it is possible to use a Surface Forces Apparatus (SFA) to measure elastic and adhesive properties of small collections of surface bound bacteria. The measurements are conducted with incomplete, patterned bacterial films and we have developed a protocol to image the contact area with AFM after the experiment. Using the SFA, we measured the force profile between a P. Aeruginosa PAO1 film and a bare mica surface. We repeated the measurement in the same contact position for up to ten days to determine the effect of desiccation on the film material properties, and then moved to the new contact area to measure the film thickness and elastic properties. A large shrinkage of the bacterial film thickness was measured during the first few days due to the bacterial film desiccation and rearrangement. The proportion of shrinkage depends on factors such as the bacterial film coverage, roughness, temperature and relative humidity. Thickness compressibility was estimated from the force curves. As a force approximation, the stress at the center of the contact (&amp;#963;) and the area of the contact were estimated by applying the Hertz model. Since the film is incomplete the calculated area in contact was reduced by a factor estimated from the optical image of the contact zone. Adhesiveness was measured in receding force profiles. Maximum adhesive force was detected in the first day, due to the high capillary force, decreased by the bacterial film desiccation and increased again due to the conditioning film.