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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
411

Three-dimensional Holographic Lithography and Manipulation Using a Spatial Light Modulator

Jenness, Nathan J. January 2009 (has links)
<p>This research presents the development of a phase-based lithographic system for three-dimensional micropatterning and manipulation. The system uses a spatial light modulator (SLM) to display specially designed phase holograms. The use of holograms with the SLM provides a novel approach to photolithography that offers the unique ability to operate in both serial and single-shot modes. In addition to the lithographic applications, the optical system also possesses the capability to optically trap microparticles. New advances include the ability to rapidly modify pattern templates for both serial and single-shot lithography, individually control three-dimensional structural properties, and manipulate Janus particles with five degrees of freedom.</p><p>A number of separate research investigations were required to develop the optical system and patterning method. The processes for designing a custom optical system, integrating a computer aided design/computer aided manufacturing (CAD/CAM) platform, and constructing series of phase holograms are presented. The resulting instrument was used primarily for the photonic excitation of both photopolymers and proteins and, in addition, for the manipulation of Janus particles. Defining research focused on the automated fabrication of complex three-dimensional microscale structures based on the virtual designs provided by a custom CAD/CAM interface. Parametric studies were conducted to access the patterning transfer rate and resolution of the system.</p><p>The research presented here documents the creation of an optical system that is capable of the accurate reproduction of pre-designed microstructures and optical paths, applicable to many current and future research applications, and useable by anyone interested in researching on the microscale.</p> / Dissertation
412

Camera Trapping Large Mammals In Yenice Forest Habitats: A Feasibility Study For Camera Trapping Large Mammals In Yenice Forests, Turkey

Can, Ozgun Emre 01 September 2008 (has links) (PDF)
Widely applicable, quantitative field methods are needed to gather wildlife data for conservation and management initiatives in Turkey. In order to evaluate the use of camera traps in forest habitats of Turkey, we conducted a 5 phase camera trap survey by using 16 passive infrared-triggered cameras with a total sampling effort of 1200 camera trap days in Yaylacik Research Forest, a 50 km2 forest patch of Yenice Forest in Karab&uuml / k during January-May 2006. The camera trap survey confirmed the presence of grey wolf (Canis lupus), brown bear (Ursus arctos), wildcat (Felis silvestris), red fox (Vulpes vulpes), badger (Meles meles), pine marten (Martes martes), roe deer (Capreolus capreolus) and wild boar (Sus scrofa) in the study area. The camera trap survey also revealed the presence of jackal (Canis aureus) and brown hare (Lepus europaeus), whose presence were not known by people living and working in the area. Contrary to the local belief, neither camera trapping survey nor ground survey confirmed the presence of lynx (Lynx lynx) in Yaylacik Research Forest. The wolf was observed to be crepuscular and the wildcat showed a diurnal activity pattern. Wildcat seemed to avoid other carnivores spatially and temporally. Simulation studies suggested that camera trap surveys should last 14 days for wolf, 13 days for wildcat, 10 days for pine marten, and 11 days for roe deer, while it is advisable to conduct longer surveys, probably 15-20 days, for wild boar, red fox and brown bears. The estimated population size for wildcat was 9 (SE=2.28227) with 95% confidence interval of 9 to 25 in the study area. A minimum of 6 brown bears were present in the study area. Our study indicated that the local knowledge about the presence of wildlife should be considered by researchers, but it cannot replace scientific surveys conducted by field biologists. This study was the first attempt to assess the presence, relative abundance, activity patterns and diversity of multiple mammal species by the use of camera trapping methodology in Turkey. The results suggest that camera trap surveys have the potential for gathering wildlife data at larger scales in Turkey, where information gap on large mammals is an obstacle for effective management and conservation of mammals.
413

An Inventory Of Medium And Large Mammal Fauna In Pine Forests Of Beypazari Through Camera Trapping

Mengulluoglu, Deniz 01 October 2010 (has links) (PDF)
Information about large mammals in Turkey usually does not go further than species lists or annual counts of particular species such as the wild goat. Camera trapping is a very useful technique to overcome this deficiency by gathering information about species presence, numbers, habitat use and behavior. Hence, a one year long camera trap study was conducted to demonstrate the diversity, activity, distribution patterns, habitat preferences and interspecific interactions of medium and large mammals in a 148 km2 large pine woodland near Ankara. Brown bear (Ursus arctos), wolf (Canis lupus), Eurasian lynx (Lynx lynx), golden jackal (Canis aureus), jungle cat (Felis chaus), red fox (Vulpes vulpes), Eurasian badger (Meles meles), stone marten (Martes foina), red deer (Cervus elaphus), wild boar (Sus scrofa), brown hare (Lepus europaeus), Caucasian squirrel (Sciurus anomalus) and southern white-breasted hedgehog (Erinaceus concolor) were the 13 mammal species captured during the study. Spatial segregation was observed among canid species indicating intraguild competition and competitive exclusion. Prey-predator interactions were documented at both spatial and temporal scales between wolves, deer and wild boars. Red deer showed seasonal and sex differences in activity patterns that appeared to be influenced by wolf predation risk. The presence of two felids unknown to the local people were revealed by camera trapping, showing the utility of this technique for such secretive and rare species. However, the low encounter rates for particular species such as lynx, brown bear and jungle cat indicated the importance of the length of study. Based on various evidence, resident adult population sizes were estimated for wolf (2-5), Eurasian lynx (2-4), brown bear (0-2) and jungle cat (2-3). The study showed that lynx can exist in high densities in a relatively small area when prey species are abundant. This study area hosted a rich mammal fauna in spite of human activities such as livestock grazing, logging and hunting. A relatively intact ecosystem, high altitudinal and habitat diversity, and a positive attitude of local people are believed to be the reasons of this observed high diversity.
414

Development Of Novel Analytical Methods For Selenium, Gold, Silver And Indium Determination Using Volatile Compound Generation, Atom Trapping And Atomic Absorption Spectrometry

Arslan, Yasin 01 May 2011 (has links) (PDF)
A novel analytical technique was developed where gaseous hydrogen selenide formed by sodium tetrahydroborate reduction is transported to and trapped on a resistively heated gold-coated W-coil atom trap for in situ preconcentration. The atom trap is held at 165 &ordm / C during the collection stage and is heated up to 675 &ordm / C for revolatilization / analyte species formed are transported to an externally heated quartz T-tube where the atomization takes place and the transient signal is obtained. For gold, a high volume gas liquid separator (HVGLS) was designed to improve the detection limit of Au down to the ng mL-1 levels. In this apparatus, analyte and reductant solutions are collected in a limited volume and volatile analyte species are formed. After separation of the volatile analyte species from liquid phase, the entire analyte vapor is sent to an atomizer. A W-coil trap was used to further decrease the detection limit. The enhancement factor for the characteristic concentration was found to be 10.7 when compared to HG-AAS performance without W-coil trap by using peak height values. Furthermore, the generation of analytically useful volatile form of Au has been studied. The flow injection generation was performed in a dedicated generator consisting of a special mixing apparatus and gas-liquid separator design. The on-line atomization in the quartz tube multiatomizer for atomic absorption (AAS) detection has been employed as the convenient atomization/detection mean. 198Au, 199Au radioactive indicator of high specific activity together with AAS measurements was used to track quantitatively the transfer of analyte in the course of generation and transport to the atomizer. In-situ trapping in GF for AAS was explored as an alternative to the on-line atomization. Transmission electron microscopy measurements proved the presence of Au nanoparticles of diameter of approximately 10 nm and smaller transported from the generator by the flow of carrier Ar. For silver, three types of GLS which are U-shaped, cylindrical and high volume gas liquid separators (HVGLS) were used to compare the sensitivities of these GLSs during Ag determination. The DL (3s) values were found as 29 ng mL-1, 0.4 ng mL-1 and 0.05 ng mL-1 for U-shaped GLS, cylindrical GLS with W-coil trap and HVGLS with W-coil trap, respectively. For indium, two types of GLS which are cylindrical and HVGLS with W-coil trap were used. The LOD and characteristic concentration were found as 148 and 317 ng mL-1 with cylindrical shape GLS. HVGLS with W-coil trap was used to improve sensitivity. In this case, LOD and characteristic concentration were found to be 0.46 and 0.98 ng mL-1, respectively. Moreover, to increase the reactivity between indium and reductant solutions, Ru(acac)3 catalyst was used. In this case, LOD and characteristic concentration were found to be 0.13 and 0.23 ng mL-1, respectively. In the case of using this catalyst, sensitivity was enhanced around 1378 fold with respect to cylindrical GLS.
415

The development of a sensitive method to study volatile organic compounds in gaseous emissions of lung cancer cell lines

Maroly, Anupam 29 August 2005 (has links)
The ultimate objective of this research was to develop a low cost, reliable system that would lead to early detection of lung cancer. Tests involved the quantitation of gaseous metabolic emissions from immortalized lung cancer cell lines in order to correlate the chemical markers to be of cancerous origin. The specific aims of the project were the study of gas emissions in selected cancer cell lines and identification of volatile organic compounds (VOCs) in them. Disadvantages of earlier studies were that the measurements were not real time or state specific so that molecular identification was often inconclusive. Furthermore the methods of study used in the past were not quantitative, which limited their practicality for medical applications. We felt the need to prove or disprove these earlier results using a new technique. The method we proposed is different and unique when compared to previous methods because cell lines have not been studied extensively for cancer markers. We have studied cancer cell lines which are adherent, immortalized cultures originating from primary tumors obtained from patients with no prior treatment for lung cancer. We have used an alternative method for the spectrometric analysis and quantitation of the selected chemical markers. The pre-concentration method involved a Purge and Trap unit with a thermal desorber where the vapor concentration was enhanced. The concentrated head space gases were analyzed using a Gas Chromatograph ?? Mass Spectrometer setup. This setup eliminated the bulky apparatus used in earlier studies. It is simpler in design and more comprehensive so that external factors such as patient??s diet, habitat and lifestyle do not contribute to our study of recognition of cancer markers. Based on the results obtained in the above experiments, a more comprehensive, inexpensive study of lung cancer related markers could be made. The first section, after giving an introduction to lung cancer, goes on to explain the background work done by other researchers on cancer. The third section gives a detailed explanation of the experimental setup. This is followed by all the tests conducted with corresponding results. The final section deals with the conclusions drawn from all experiments.
416

Sympathetic heating and cooling of trapped atomic and molecular ions

Clark, Craig R. 06 January 2012 (has links)
Laser-cooled atomic ions have led to an unprecedented amount of control over the quantum states of matter. The Coulombic interaction allows for information to be transferred between neighboring ions, and this interaction can be used to entangle qubits for logic operations in quantum information processors. The same procedure for logic operations can be used for high resolution atomic spectroscopy, and is the basis for the most accurate atomic optical clocks to date. This thesis describes how laser-cooled atomic ions can impact physical chemistry through the development of molecular ion spectroscopy techniques and the simulation of magnetic systems by ion trap quantum computers. A new technique developed for spectroscopy, Sympathetic Heating Spectroscopy (SHS), takes advantage of the Coulombic interaction between two trapped ions: the control ion and a spectroscopy ion. SHS uses the back action of the interrogating laser to map spectroscopy ion information onto the Doppler shift of the control ion for measurement. SHS only requires Doppler cooling of the ions and fluorescence measurement and represents a simplification of quantum logic spectroscopy. This technique is demonstrated on two individual isotopes of calcium: Ca-40(+) for cooling and Ca-44(+) as the spectroscopy ion. Having demonstrated SHS with atomic ions, the next step was to extend the technique by loading and characterizing molecular ions. The identification of an unknown molecular ion is necessary and can be achieved by monitoring the change in motion of the two ion crystal, which is dependent on the molecular ion mass. The motion of two trapped ions is described by their normal modes, which can be accurately measured by performing resolved sideband spectroscopy of the S(1/2)-D(5/2) transition of calcium. The resolved sidebands can be used to identify unknown ions (atomic and molecular) by calculating the mass based on the observed value in axial normal mode frequencies. Again, the trapped molecular ion is sympathetically cooled via the Coulombic interaction between the Ca-40(+) and the unknown molecular ion. The sensitivity of SHS could be improved by implementing sympathetic sideband cooling and determining the heating by measuring single quanta of motion. The ultimate limit of control would be the development of an ion trap quantum computer. Many theoretical quantum computing researchers have made bold claims of the exponential improvement a quantum computer would have over a classical computer for the simulation of physical systems such as molecules. These claims are true in principle for ideal systems, but given non-ideal components it is necessary to consider the scaling due to error correction. An estimate of the resource requirements, the total number of physical qubits and computational time, required to compute the ground state energy of a 1-D quantum Transverse Ising Model (TIM) of N spin-1/2 particles, as a function of the system size and the numerical precision, is presented. This estimate is based on analyzing the impact of fault-tolerant quantum error correction in the context of the quantum logic array architecture. The results show that a significant amount of error correction is required to implement the TIM problem due to the exponential scaling of the computational time with the desired precision of the energy. Comparison of this result to the resource requirements for a fault-tolerant implementation of Shor's quantum factoring algorithm reveals that the required logical qubit reliability is similar for both the TIM problem and the factoring problem.
417

Study of Subharmonic Oscillations In Resonance Excitation Experiments In Nonlinear Paul Traps

Srinivasan, S Deepak 09 1900 (has links)
This thesis presents the results of studies on the problem of subharmonic oscillations in nonlinear Paul trap mass spectrometry. The objective of this thesis is to determine whether the subharmonic oscillations of ions in the trap could in any way affect the quality of mass spectrum in resonance ejection experiments. This is accomplished by studying the existence and stability criteria of these oscillations. This study is done for two casesone in which the auxiliary excitation frequency is close to thrice the ion axial secular frequency and other in which it is close to twice the ion axial secular frequency. Initially, the equations describing the ion motion in the presence of auxiliary excitation are derived. The equations describing the ion motion are then brought into a form easily amenable to analysis by techniques of perturbation theory. The necessary background and definitions to understand the basis for the thesis, along with a survey of results obtained in relevant areas in mass spectrometry and nonlinear dynamics is then developed. The first problem is the study of subharmonic oscillations when the auxiliary excitation frequency is in the vicinity of thrice the ion axial secular frequencies taken up. The application of the multiple time scales technique to the equations describing ion motion gives the slow flow equations, that describe the evolution of amplitudes of axial and radial oscillations. The expression for the steady state amplitudes of these oscillations are then derived. From these expressions the conditions for the existence of the oscillations are obtained in terms of the auxiliary amplitude and the frequency detuning. This is then followed by a detailed stability analysis for the subharmonic oscillation with a given amplitude and phase. The study ends with the discussion of the results obtained, the pertinent numerical studies and the relevance of this study to mass spectrometry. The second study is regarding the problem of subharmonic oscillations when the auxiliary excitation frequency is close to twice the ion axial secular frequency is analyzed. When PoincareLindstedt’s method is applied to the ion motion equations, the amplitude frequency relationship that describes the relation between the steady state subharmonic oscillation amplitude and the frequency detuning is obtained. The variation of the oscillation amplitude with the frequency detuning is then studied. Then follows the analysis of stability. The stability of subharmonic oscillation is analyzed using the results from the standard analysis of Hill’s equation of fourth order. This study ends with the discussion of the results obtained in the context of mass spectrometry. Finally, a summary of the results obtained is discussed.
418

Computational Mass Spectrometry

Chen, Evan Xuguang January 2015 (has links)
<p>Conventional mass spectrometry sensing has isomorphic nature, which means measure the input mass spectrum abundance function by a resemble of delta function to avoid ambiguity. However, the delta function nature of traditional mass spectrometry sensing approach imposes trade-offs between mass resolution and throughput/mass analysis time. This dissertation proposes a new field of mass spectrometry sensing which combines both computational signal processing and hardware modification to break the above trade-offs. We introduce the concept of generalized sensing matrix/discretized forward model in mass spectrometry filed. The presence of forward model can bridge the cap between sensing system hardware design and computational sensing algorithm including compressive sensing, feature/variable selection machine learning algorithms, and stat-of-art inversion algorithms. </p><p>Throughout this dissertation, the main theme is the sensing matrix/forward model design subject to the physical constraints of varies types of mass analyzers. For quadrupole ion trap systems, we develop a new compressive and multiplexed mass analysis approach mutli Resonant Frequency Excitation (mRFE) ejection which can reduce mass analysis time by a factor 3-6 without losing mass spectra specificity for chemical classification. A new information-theoretical adaptive sensing and classification framework has proposed on quadrupole mass filter systems, and it can significantly reduces the number of measurements needed and achieve a high level of classification accuracy. Furthermore, we present a coded aperture sector mass spectrometry which can yield a order-of-magnitude throughput gain without compromising mass resolution compare to conventional single slit sector mass spectrometer.</p> / Dissertation
419

The Labour Party and family income support policy, 1940-1979 : an examination of the party's interpretation of the relationship between family income support and the labour market

Pratt, Alan January 1988 (has links)
The first two chapters examine the party's policy towards the wage-stop and the poverty trap. Until 1963 the party ignored the wage-stop but from then until 1975 a section of the party campaigned against the regulation expressing moral revulsion and concern about its administration but only rarely opposition to the principle. A Labour government removed the stop when its operation affected only a tiny minority of families. The party was quickly involved in the development of the poverty trap debate being particularly drawn to its disincentive characteristics, but Labour governments, like their Conservative counterparts, soon came to regard the idea as a mere statistical abstraction. After confirming the party's historical ambivalence about Family Allowances the thesis demonstrated that whenever it advocated allowances it did so because it believed the programme would alleviate family poverty rather than augment work incentives. However Labour governments consistently upheld the principle of substitutability, thus conferring de facto support on that less-eligibility dimension of Family Allowances which Macnicol has established informed the coalition government's decision to legislate for the programme in 1945. Despite the party's opposition to Family Income Supplement it became an important element in the Labour government's anti-poverty strategy after the Child Benefits debate in 1976. F.I.S. was criticised because of its contribution to the poverty trap and its potential for assisting in the pauperisation of the low paid, while Child Benefit was supported because it appeared to be a more equitable technique of delivering support to families with dependent children although some in the party were sensitive to the scheme's potential link with improved work incentives. In general, the Labour Party is seen to have failed to develop any coherent and sustained alternative to the ideas and programmes of its political opponents in this critical area of social policy.
420

Trapped Positrons for High-Precision Magnetic Moment Measurements

Hoogerheide, Shannon Michelle Fogwell 28 August 2013 (has links)
A single electron in a quantum cyclotron provides the most precise measurement of the electron magnetic moment, given in units of the Bohr magneton by g/2 = 1.001 159 652 180 73 (28) [0.28 ppt]. The most precise determination of the fine structure constant comes from combining this measurement with Standard Model theory, yielding \(\alpha^{-1} = 137.035 999 173 (34)\) [0.25 ppb], limited by the experimental uncertainty of the electron g-value. The most stringent test of CPT symmetry in leptons comes from comparing the electron and positron magnetic moments, limited by the positron uncertainty at 4.2 ppt. A new high-stability apparatus has been built and commissioned for improved measurements of the electron and positron magnetic moments, a greatly improved test of lepton CPT symmetry, and an improved determination of the fine structure constant. These new measurements require robust positron loading from a retractable radioactive source that is small enough to avoid compromising the high-precision environment of our experiment. The design and implementation of such a scheme is a central focus of this work. Robust positron loading at a rate of \(1-2 e^+/min\) from a \(6.5 \mu Ci^{22}Na\) source has been demonstrated. / Physics

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