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Development of Frequency and Phase Modulated Thermal-wave Methodologies for Materials Non-destructive Evaluation and Thermophotonic Imaging of Turbid MediaTabatabaei, Nima 31 August 2012 (has links)
In frequency-domain photothermal radiometry (FD-PTR) a low-power intensity-modulated optical excitation generates thermal-wave field inside the sample and the subsequent infrared radiation from the sample is analyzed to detect material’s inhomogeneities. The non-contact nature of FD-PTR makes it very suitable for non-destructive evaluation of broad range of materials. Moreover, the methodology is based on intrinsic contrast of light absorption which can be used as a diagnostic tool for inspection of malignancy in biological tissues. Nevertheless, the bottom line is that the physics of heat diffusion allows for a highly damped and dispersive propagation of thermal-waves. As a result, the current FD-PTR modalities suffer from limited inspection depth and poor axial/depth resolution. The main objective of this thesis is to show that using alternative types of modulation schemes (such as linear frequency modulation and binary phase coding) and radar matched filter signal processing, one can obtain localized responses from inherently diffuse thermal wave fields. In this thesis, the photothermal responses of turbid, transparent, and opaque media to linear frequency modulated and binary phase coded excitations are analytically derived. Theoretical simulations suggest that matched-filtering in diffusion-wave field acts as constructive interferometry, localizing the energy of the long-duty excitation under a narrow peak and allowing one to construct depth resolved images. The developed technique is the diffusion equivalent of optical coherence tomography and is named thermal coherence tomography. It was found that the narrow-band binary phase coded matched filtering yields optimal depth resolution, while the broad-band linear frequency modulation can be used to quantify material properties through the multi-parameter fitting of the experimental data to the developed theory. Thermophotonic detection of early dental caries is discussed in detail as a potential diagnostic application of the proposed methodologies. The performance of the diagnostic system is verified through a controlled demineralization protocol as well as in teeth with natural caries.
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Diagnostic Imaging and Assessment Using Angle Resolved Low Coherence InterferometryGiacomelli, Michael Gene January 2012 (has links)
<p>The redistribution of incident light into scattered fields ultimately limits the ability to image into biological media. However, these scattered fields also contain information about the structure and distribution of protein complexes, organelles, cells and whole tissues that can be used to assess the health of tissue or to enhance imaging contrast by excluding confounding signals. The interpretation of scattered fields depends on a detailed understanding of the scattering process as well as sophisticated measurement systems. In this work, the development of new instruments based on low coherence interferometry (LCI) is presented in order to perform precise, depth-resolved measurements of scattered fields. Combined with LCI, the application of new light scattering models based on both analytic and numerical methods is presented in order to interpret scattered field measurements in terms of scatterer geometry and tissue health. </p><p>The first portion of this work discusses the application of a new light scattering model to the measurement recorded with an existing technique, Angle Resolved Low Coherence Interferometry (a/LCI). In the a/LCI technique, biological samples are interrogated with collimated light and the energy per scattering angle at each depth in the volume is recorded interferometrically. A light scattering model is then used to invert the scattering measurements and measure the geometry of cell nuclei. A new light scattering model is presented that can recover information about the size, refractive index, and for the first time, shape of cell nuclei. This model is validated and then applied to the study of cell biology in a series of experiments measuring cell swelling, cell deformation, and finally detecting the onset of apoptosis.</p><p>The second portion of this work introduces an improved version of a/LCI based on two dimension angle resolved measurement (2D a/LCI) and Fourier domain low coherence interferometry (FD-LCI). Several systems are presenting for high speed and polarization-resolved measurements of scattered fields. An improved light scattering model based on fully polarization and solid angle resolved measurements is presented, and then efficiently implemented using distributed computing techniques. The combined system is validated with phantoms and is shown to be able to uniquely determine the size and shape of scattering particles using a single measurement.</p><p>The third portion of this work develops the use of angle-resolved interferometry for imaging through highly scattering media by exploiting the tendency of scatterers to forward scatter light. A new interferometers is developed that can image through very large numbers of scattering events with acceptable resolution. A computational model capable of reproducing experimental measurements is developed and used to understand the performance of the technique.</p><p>The final portion of the work develops a method for processing 2D angle resolved measurements using optical autocorrelation. In this method, measurements over a range of angles are fused into a single depth scan that incorporates the component of scattered light only from certain spatial scales. The utility of the technique is demonstrated using a gene knockout model of retinal degeneration in mice. Optical autocorrelation is shown to be a potentially useful biomarker of tissue disease.</p> / Dissertation
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A statistical framework for the analysis of neural control of movement with aging and other clinical applicationsJohnson, Ashley Nzinga 08 March 2012 (has links)
The majority of daily living tasks necessitate the use of bimanual movements or concurrent cognitive processing, which are often more difficult for elderly adults. With the number of Americans age 65 and older expected to double in the next 25 years, in-depth research and sophisticated technologies are necessary to understand the mechanisms involved in normal neuromuscular aging. The objective of the research is to understand the effects of aging on biological signals for motor control and to develop a methodology to classify aging and stroke populations. The methodological approach investigated the influence on correlated activity (coherence) between electroencephalogram (EEG) and electromyogram (EMG) signals into senior age. In support of classifying aging and stroke populations, the methodology selected optimal features from the time, frequency, and information theory domains. Additionally, the use of cepstral analysis was modified toward this application to analyze EEG and EMG signals. The inclusion and optimization of cepstral features significantly improved classification accuracy. Additionally, classification of young and elderly adults using Gaussian Mixture Models with Minimum Classification Error improved overall accuracy values.
Contributions from the dissertation include demonstration of the change in correlated activity between EMG and EEG with fine motor simple and complex dual tasks; a quantitative feature library for characterizing the neural control of movement with aging under three task conditions; and a methodology for the selection and classification of features to characterize the neural control of movement. Additionally, the dissertation provides functional insight for the association of features with tasks, aging, and clinical conditions. The results of the work are significant because classification of the neural control of movement with aging is not well established. From these contributions, future potential contributions are: a methodology for physiologists to analyze and interpret data; and a computational tool to provide early detection of neuromuscular disorders.
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Epilepsy in young adulthood : medical, psychosocial and functional aspectsGauffin, Helena January 2012 (has links)
The aim of this thesis was to describe the medical, cognitive and psychosocial consequences of epilepsy in young adulthood. Four studies were carried out with this patient group. The first two papers were based on a follow-up study regarding young adults with epilepsy that investigated medical and psychosocial aspects and compared the present results with those five years earlier. We then conducted focus group interviews with young adults with epilepsy and subjective cognitive decline to assess the deeper meaning of living with epilepsy accompanied by cognitive difficulties. In the fourth study we studied cognitive dysfunction further, choosing the language function in young adults with epilepsy. We firstly examined whether language impairments were associated to functional brain alterations and secondly related the language performance to demographics, clinical data, Quality of Life (QoL) and self-esteem. The five-year follow up of 97 young adults with uncomplicated epilepsy revealed no improvement regarding seizure frequency or side effects from anti-epileptic drugs (AEDs) over time, even though many new-generation AEDs had been established during this period. During the study period 21% had recovered from epilepsy, Seizure frequency among those who still had epilepsy had not improved, and 42% had experienced seizures during the past year. New-generation anti-epileptic drugs (AEDs) had been introduced to PWE, especially to women. There is still need for new and more effective treatment options for this group in the future. It is essential to find alternative approaches to develop better treatment options for this group in the future. However QoL was normal compared to the general population, indicating that new options regarding treatment can have made an impact. Lower QoL was correlated to high seizure frequency and to cognitive side effects. Self-esteem and Sence of Coherence were impaired compared to the situation at adolescence. Self-esteem was correlated to seizure frequency and to side-effects of antiepileptic drugs. Sence of Coherence was not correlated to epilepsy-related factors in the same way as QoL, but mirrored the phenomenon of epilepsy. The qualitative study showed that the consequences of epilepsy are not only restricted to the consequences of seizures, but also concerns many other aspects of life. The interviews revealed four themes: “affecting the whole person“, “influencing daily life”, ”affecting relations” and ”meeting ignorance in society”. Another important factor was language function; when one loses some language ability, this gives a feeling of losing one’s capability. The fourth study examined language by neuropsychological methods and correlated this function to brain activation measured by fMRI. Language functions measured in verbal fluency and abstract language comprehension were impaired in participants with both generalized epilepsy and epilepsy of focal onset. Age at onset of epilepsy and education are the most important factors correlating to language function. An additional factor that impacts abstract language comprehension is the frequency of convulsive seizures, while use of topiramate /zonisamide affect verbal fluency negatively. QoL was not correlated to language impairments, but for patients with focal onset seizures there was a correlation between self-esteem and abstract language comprehension. The fMRI investigation revealed altered activity during language tasks in participants with epilepsy compared to controls. In epilepsy with focal seizures originating in the left hemisphere, we found increased bilateral activation of supporting areas, in the anterior mid-cingulate cortex and the anterior ventral insulae, indicating a compensational functional reorganization. In generalized epilepsy, the functional language network showed an imbalance, as this group expressed an inadequate suppression of activation in the anterior temporal lobe during semantic processing. Subtle language impairment can, even if it does not occur in everyday dialogue, be of importance and have consequences for the person affected. The negative consequences of language decline must be addressed in people with epilepsy of different etiology. Young adults with epilepsy are still substantially affected by the condition. The consequences are not only restricted to the seizures, but concern many aspects of life and there is a great need for new treatment options for this group in the future.
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Magnetism and Structure of Thin 3d Transition Metal Films : XMCD and EXAFS using Polarized Soft X-RaysHahlin, Anders January 2003 (has links)
In this Thesis the magnetic and structural properties of thin epitaxial Fe, Co, and Ni films are discussed. Some of the in-situ prepared samples were used to characterize the degree of circular polarization of the newly installed beamline D1011 at MAX-lab. By means of x-ray magnetic circular dichroism (XMCD) and utilizing the associated magneto optic sum rules, the orbital (ml) and spin (ms) moments are determined directly in mB/atom with elemental specificity. The extended x-ray absorption fine structure (EXAFS) measurements yield site specific information on the local crystallographic structure. These measurements were performed using the circular x-rays of several beamlines. The influence of the degree of spatial source coherence lspat of the x-rays was characterized by means of Fresnel diffractometry. A correlation between enhanced XAS white line intensities and higher values of lspat was established for 20 ML Fe, Co, and Ni films on Cu(100). The degree of circularly polarized x-rays (Pc) at beamline D1011 at MAX-lab was characterized by studying Fe films on Cu(100) by means of XMCD. The maximum value of Pc is experimentally determined to Pc =0.85. The Au/Co/Au trilayer system was studied as a function of Co thickness, temperature, and Au cap thickness. A 10 mono-layer (ML) Co film, with an Au cap of 20 Å, shows a spin reorientation transition (SRT) from an in-plane to an out-of-plane easy direction as the temperature is lowered from 300 K to 200 K. The magnetic properities of these Co films are very different to what is found for bulk samples due to, in particular, the broken symmetry at the interfaces. The thickness dependent spin reorientation transition in the Fe/Ag(100) system was characterized by means of XMCD and EXAFS measurements. 3 ML Fe films show an out-of-plane easy direction with an 125% enhanced orbital moment as compared to the 25 ML Fe in-plane film. Simulations of the Fe L-edge EXAFS indicate the bulk Fe bcc structure for film thicknesses of 6-25 ML Fe. For 3 ML Fe strong deviations from this bcc phase is observed. Ultrathin Co films deposited on flat and vicinal Cu(111) in the thickness region 1-25 ML were studied by means of XMCD and scanning tunneling microscopy (STM). The vicinal Cu(111) Co deposition leads to the formation of elongated islands preferentially oriented along the step edges. In connection to this particular Co growth mode we observe an increase of both the orbital and the spin moment on the vicinal Cu(111) of about 25% relative to what was observed for Co on flat Cu(111).
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Fault-tolerant Cache Coherence Protocols for CMPsFernández Pascual, Ricardo 23 July 2007 (has links)
We propose a way to deal with transient faults in the interconnection network of many-core CMPs that is different from the classic approach of building a fault-tolerant interconnection network. In particular, we provide fault tolerance mechanisms at the level of the cache coherence protocol so that it guarantees the correct execution of programs even when the underlying interconnection network does not deliver all messages correctly. This way, we can take advantage of the different meaning of each message to achieve fault tolerance with lower overhead than at the level of the interconnection network, which has to treat all messages alike with respect to reliability.We design several fault-tolerant cache coherence protocols using these techniques and evaluate them. This evaluation shows that, in absence of faults, our techniques do not increase significantly the execution time of the applications and their major cost is an increase in network traffic due to acknowledgment messages that ensure the reliable transference of ownership between coherence nodes, which are sent out of the critical path of cache misses. In addition, a system using our protocols degrades gracefully when transient faults actually happen and can support fault rates much higher than those expected in the real world with only a small performance degradation. / Se proponen una forma de tratar con los fallos transitorios en la red de interconexión de un CMP con gran número de núcleos que es diferente del enfoque clásico basado en construir una red de interconexión tolerante a fallos. En particular se proporcionan mecanismos de tolerancia a fallos al nivel del protocolo de coherencia. De esta forma, se puede aprovechar el conocimiento que el protocolo tiene sobre el significado de cada mensaje para obtener tolerancia a fallos con menor sobrecarga que en el nivel de red, que tiene que tratar todos los mensajes idénticamente.En la tesis se diseñan y evalúan varios protocolos de coherencia utilizando estas técnicas. Los resultados muestran que, cuando no hay fallos, nuestras técnicas no incrementan significativamente el tiempo de ejecución de las aplicaciones y su mayor coste es un incremento en el tráfico de red. Además, un sistema que use nuestros protocolos soporta tasas de fallos mucho mayores que las esperadas en circunstancias realistas y su rendimiento se degrada gradualmente cuando ocurren los fallos.
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Automated Epileptic Seizure Onset DetectionDorai, Arvind 21 April 2009 (has links)
Epilepsy is a serious neurological disorder characterized by recurrent unprovoked seizures due to abnormal or excessive neuronal activity in the brain. An estimated 50 million people around the world suffer from this condition, and it is classified as the second most serious neurological disease known to humanity, after stroke. With early and accurate detection of seizures, doctors can gain valuable time to administer medications and other such anti-seizure countermeasures to help reduce the damaging effects of this crippling disorder.
The time-varying dynamics and high inter-individual variability make early prediction of a seizure state a challenging task. Many studies have shown that EEG signals do have valuable information that, if correctly analyzed, could help in the prediction of seizures in epileptic patients before their occurrence. Several mathematical transforms have been analyzed for its correlation with seizure onset prediction and a series of experiments were done to certify their strengths. New algorithms are presented to help clarify, monitor, and cross-validate the classification of EEG signals to predict the ictal (i.e. seizure) states, specifically the preictal, interictal, and postictal states in the brain. These new methods show promising results in detecting the presence of a preictal phase prior to the ictal state.
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Perspectives on Perspectivism: Nietzsche and His CommentatorsHudgens, Jennifer L 03 August 2007 (has links)
There is little consensus among scholars as to what Nietzsche’s “perspectivism” is or what it entails. I will focus on a limited number of Nietzsche’s commentators, describing and commenting upon the writings of Brian Leiter, R. Lanier Anderson, Maudemarie Clark, Christoph Cox, and John Wilcox. Each commentator provides insight into the problems generated by the interpretations previous commentators have given, while simultaneously generating different problems within these newer interpretations. I hope to draw together the salvageable elements of each of these five interpretations in order to alleviate some general interpretive problems. My own interpretation is as follows: perspectivism entails the two positions ‘knowledge coherentism’ and ‘truth constructivism.’ ‘Knowledge coherentism’ is the need for coherence within a system of knowledge. This position saves perspectivism from relativism. ‘Truth constructivism’ is the claim that we humans intersubjectively create truth; this entails a rejection of the dichotomy of the real and the apparent.
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Fingerprint SegmentationJomaa, Diala January 2009 (has links)
In this thesis, a new algorithm has been proposed to segment the foreground of the fingerprint from the image under consideration. The algorithm uses three features, mean, variance and coherence. Based on these features, a rule system is built to help the algorithm to efficiently segment the image. In addition, the proposed algorithm combine split and merge with modified Otsu. Both enhancements techniques such as Gaussian filter and histogram equalization are applied to enhance and improve the quality of the image. Finally, a post processing technique is implemented to counter the undesirable effect in the segmented image. Fingerprint recognition system is one of the oldest recognition systems in biometrics techniques. Everyone have a unique and unchangeable fingerprint. Based on this uniqueness and distinctness, fingerprint identification has been used in many applications for a long period. A fingerprint image is a pattern which consists of two regions, foreground and background. The foreground contains all important information needed in the automatic fingerprint recognition systems. However, the background is a noisy region that contributes to the extraction of false minutiae in the system. To avoid the extraction of false minutiae, there are many steps which should be followed such as preprocessing and enhancement. One of these steps is the transformation of the fingerprint image from gray-scale image to black and white image. This transformation is called segmentation or binarization. The aim for fingerprint segmentation is to separate the foreground from the background. Due to the nature of fingerprint image, the segmentation becomes an important and challenging task. The proposed algorithm is applied on FVC2000 database. Manual examinations from human experts show that the proposed algorithm provides an efficient segmentation results. These improved results are demonstrating in diverse experiments.
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Hälsosamt förhållningssätt mot stress: En kvalitativ studie om att vara enhetschef inom LSS i Kalmar kommunKrusell, Magnus, Ruuth, Patrik January 2011 (has links)
Stress is part of everyday life and in the working conditions of the social services in Sweden. Thus each and every person has resources and strategies to cope with those stressors that construct the assumption of stress. The aim of this study was to understand how persons in leading positions of the LSS of Social Services in Kalmar experience and cope with stressors in their leadership and organization and to investigate what factors during working and non-working hours promote health. Influenced by the theoretical approach of Aaron Antonovsky´s Sense of Coherence seven qualitative interviews were conducted with persons in leading positions. They were asked about stressors, coping strategies, resources and health promoting factors that help to cope with stressors. The interviewees stated that stressors like unclear role description and heavy workload are among others a major part of the role as leader. They also stated that the role as a leader was more desirable than being a chief. Coping strategies were found to help control the daily stressors. Factors during working and non-working hours which promote health were found to be important as a factor to gain energy, relaxation and meaningfulness.
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