No description available.

No description available.

No description available.

No description available.

Swabs are used as a collecting device for many biological samples and its complete elution is a desired step for clinical and forensic diagnostics. Swabs are made of cotton, rayon, polyurethane, foam or polyester and come in a spun or flocked-tipped format. They are used to extract biological samples from a patient, which includes saliva, mucous, blood, semen or other body fluids. These body fluids then undergo the process of elution where the collected samples are extracted from the swabs into an elution fluid. Apart from biological samples, the importance of swabbing and elution also becomes more evident in forensics, where the concentration of available cells is very low. One such example is rape kit analysis. Another field of application is the capture and release of bacterial spores from environmental contact surfaces and food surfaces, which also indicate the use of swabs in non-biological areas. The recovery of the biological material from the fibre matrix of the swab has a significant influence on diagnostic sensitivity of any assay. The recovery of micro-organisms from a matrix of swab fibres depends on the nature of the body fluid, the type of the swab fibres and the process of elution. Various methods are used to elute samples from swab, including the use of chemicals to digest the cotton fibres to remove intact cells (~20% recovery), centrifugation (~58% recovery), piezoelectric vibration or pressurized fluid-flow (~60% recovery). These methods are either passive (chemical elution) or provides a gentle tangential shear force through associated flow (centrifugation, piezoelectric and pressurized flow), resulting in a low recovery. The success of all the downstream processes of elution, like lysis, DNA amplification and detection, depends on the number of cells eluted from the swab fibre matrix. Hence, the recovery efficiency is an important parameter for determining the performance of elution, and higher value of the same is desired for most diagnostic assays. This thesis reports a magnetically-actuated physical impingement method for elution and recovery of artificial sputum samples from cotton fibres. A device has been fabricated to induce a rotating magnetic field on smaller magnetic particles in a vial for striking the swab within a confined gap. Elution of samples from the swab using this device was demonstrated using artificial sputum prepared by mixing 2% methyl cellulose in deionised water, loaded with fluorescent-tagged polystyrene beads and Escherichia coli bacteria at various concentrations. The recovery efficiency was found to increase with both rotational speed and elution time, but plateaus after 400 RPM and 120s respectively. At higher concentration of polystyrene beads, a maximum recovery of ~85% was achieved at 5x108 particles/ml sample. With lower concentration (106 particles/ml), the maximum efficiency (~93%) was found to be almost twice of the static condition (46.7%), while using only 620µL of elution volume. Similar trends were found in experiments with artificial sputum loaded with E. coli cells, and the maximum recovery was found to be ~90% at 105 CFU/ml concentration. The robust design and smaller size allows the device to be used in different clinical, forensic and laboratory settings. Also, due to cheaper means of manufacturing and assembly, the vials and smaller magnets can be discarded after every experiment, thereby preventing contamination. The device is most suitable for recovering cells from different body fluids like saliva, mucous, semen or blood, absorbed by the swab fibres. Apart from body fluids samples, swabs holding biological agents from environmental surfaces can also be eluted. A higher recovery at lower concentration facilitates the use of this device where the available analyte concentration is low. / Thesis / Master of Applied Science (MASc)

This dissertation proposes a miniaturized optical fiber based sensor system for the measurement of 3-dimensional vector magnetic fields. The operation of the sensor system is based on the detection of magnetostrictive dimensional changes in the sensor gage using a modified extrinsic Fabry-Perot Interferometer configuration. Because of the magnetostrictive reflector the gap length depends on the magnetic fields applied to the sensor. Since the diameter of the magnetostrictive sensor gage is 125 micrometer which is the same as that of the input/output fiber, the sensor is simply constructed by inserting the sensor gage and the input/output fiber into a small glass tube. The glass tube serves as both an aligner for the sensor gage and input/out fiber, and a passive temperature compensator. In addition, it also enhances the mechanical strength and compactness of the sensor. This sensor design shows 98 percent suppression of the thermally induced sensor output changes. The linear output of the sensor system is enhanced by transverse field annealing which increases magnetostrictive induction in the ferromagnetic sensor gage material and controls the sensor gage geometry. A 5-times increase in sensor sensitivity is obtained with the transverse field annealing and the use of a new magnetostrictive material. A modified sensor gage endface demonstrates 92 percent of fringe visibility, which further improves the performance of the interferometer. The signal fading in the interferometric sensors at the peak or bottom of a fringe is reduced by using a quadrature signal demodulation method. The system has been shown to have a resolution better than 100 nT over a measurement range from 100 to 40,000 nT. This research is supported financially by the Phillips Laboratory of the U.S. Air Force. / Ph. D.

A wide range of physical systems are modeled as axially moving strings; such examples are belts, tapes, wires and fibers with applied electromagnetic fields. In this study, we propose a model that describes the motion of a current-carrying conductive string in a lateral magnetic field, while it is being pulled axially. This model is a generalization of past studies that have neglected one or more properties featured in our system. It is assumed that the string is moving with a constant velocity between two rings that are a finite distance apart. Directions of the magnetic field and the motion of the string coincide. The problem is first considered in a static setting. Stability critical values of the magnetic field, pulling speed, and current are shown to exist when the uniform motion (along a string line) of the string buckles into spiral forms. In the dynamic setting, conditions for stability of certain solutions are presented and discussed. It is shown that there is a divergence between the critical values in the linear dynamic and static cases. Furthermore, traveling wave solutions are examined for certain cases of our general system. We develop an approximate solution for a nonlinear moving string when a periodic nonstationary current flows through the string. Domains of parameters are defined when the string falls into a pre-chaotic state, i.e., the frequency of vibrations is doubled. / MS / The modeling and analysis of elastic conductors has applications in areas ranging from manufacturing to particle physics. In this study, we model the motion of a conductive string being pulled (between two rings) while a magnetic field is applied in the lateral direction. This system’s stability is categorized through certain parameters such as the applied magnetic field, speed of pulling, and current flowing through the string. The equilibrium states are also analyzed. When the string has a periodic current, approximate solutions (string shape/orientation) are computed. In this case, we find domains of parameters that give rise to chaos. Wave speeds of traveling wave solutions are also found for certain cases.

A new neutron Electric Dipole Moment (nEDM) experiment was proposed to be commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source (SNS) of the Oak Ridge National Laboratory (ORNL). The underlying theme of this experiment (first conceived by Golub and Lamoreaux in 1994) is the search for new physics beyond the Standard Model of particle physics. The discovery of a non-zero nEDM would be of revolutionary importance to physics, with the discovery of such providing for evidence for new-beyond-the-Standard-Model physics required for a resolution to the unresolved puzzle of why the universe is dominated by matter, as opposed to anti-matter. A first demonstration of a new magnetic field monitoring system for a neutron electric dipole moment experiment is presented. The system is designed to reconstruct the vector components of the magnetic field in the interior measurement region solely from exterior measurements. The results highlight the potential for the implementation of an improved system in an upcoming neutron electric dipole moment experiment to be carried out at the Spallation Neutron Source at Oak Ridge National Laboratory.

In recent years, the nitrogen-vacancy (NV) center has emerged as a promising magnetic sensor capable of measuring magnetic fields with high sensitivity and spatial resolution under ambient conditions. This combination of characteristics allows NV magnetometers to probe magnetic structures and systems that were previously inaccessible with alternative magnetic sensing technologies. This dissertation presents and discusses a number of the initial efforts to demonstrate and improve NV magnetometry. In particular, a wide-field CCD based NV magnetic field imager capable of micron-scale spatial resolution is demonstrated; and magnetic field alignment, preferential NV orientation, and multipulse dynamical decoupling techniques are explored for enhancing magnetic sensitivity. The further application of dynamical decoupling control sequences as a spectral probe to extract information about the dynamics of the NV spin environment is also discussed; such information may be useful for determining optimal diamond sample parameters for different applications. Finally, several proposed and recently demonstrated applications which take advantage of NV magnetometers' sensitivity and spatial resolution at room temperature are presented, with particular focus on bio-magnetic field imaging. / Engineering and Applied Sciences

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24173号 / 理博第4864号 / 新制||理||1696(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 藤 浩明, 教授 吉川 裕, 教授 石岡 圭一 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM