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Design of Efficient TLB-based Data Classification Mechanisms in Chip MultiprocessorsEsteve García, Albert 01 September 2017 (has links)
Most of the data referenced by sequential and parallel applications running in current chip multiprocessors are referenced by a single thread, i.e., private. Recent proposals leverage this observation to improve many aspects of chip multiprocessors, such as reducing coherence overhead or the access latency to distributed caches. The effectiveness of those proposals depends to a large extent on the amount of detected private data. However, the mechanisms proposed so far either do not consider either thread migration or the private use of data within different application phases, or do entail high overhead. As a result, a considerable amount of private data is not detected. In order to increase the detection of private data, this thesis proposes a TLB-based
mechanism that is able to account for both thread migration and private application phases with low overhead. Classification status in the proposed TLB-based classification mechanisms is determined by the presence of the page translation stored in other
core's TLBs. The classification schemes are analyzed in multilevel TLB hierarchies, for systems with both private and distributed shared last-level TLBs.
This thesis introduces a page classification approach based on inspecting other core's TLBs upon every TLB miss. In particular, the proposed classification approach is based on exchange and count of tokens. Token counting on TLBs is a natural and efficient way for classifying memory pages. It does not require the use of complex and undesirable persistent requests or arbitration, since when two ormore TLBs race for accessing a page, tokens are appropriately distributed classifying the page as shared.
However, TLB-based ability to classify private pages is strongly dependent on TLB size, as it relies on the presence of a page translation in the system TLBs. To overcome that, different TLB usage predictors (UP) have been proposed, which allow a page classification unaffected by TLB size. Specifically, this thesis introduces a predictor that obtains system-wide page usage information by either employing a shared last-level TLB structure (SUP) or cooperative TLBs working together (CUP). / La mayor parte de los datos referenciados por aplicaciones paralelas y secuenciales que se ejecutan enCMPs actuales son referenciadas por un único hilo, es decir, son privados. Recientemente, algunas propuestas aprovechan esta observación para mejorar muchos aspectos de los CMPs, como por ejemplo reducir el sobrecoste de la coherencia o la latencia de los accesos a cachés distribuidas. La efectividad de estas propuestas depende en gran medida de la cantidad de datos que son considerados privados. Sin embargo, los mecanismos propuestos hasta la fecha no consideran la migración de hilos de ejecución ni las fases de una aplicación. Por tanto, una cantidad considerable de datos privados no se detecta apropiadamente. Con el fin de aumentar la detección de datos privados, proponemos un mecanismo basado en las TLBs, capaz de reclasificar los datos a privado, y que detecta la migración de los hilos de ejecución sin añadir complejidad al sistema. Los mecanismos de clasificación en las TLBs se han analizado en estructuras de varios niveles, incluyendo TLBs privadas y con un último nivel de TLB compartido y distribuido.
Esta tesis también presenta un mecanismo de clasificación de páginas basado en la inspección de las TLBs de otros núcleos tras cada fallo de TLB. De forma particular, el mecanismo propuesto se basa en el intercambio y el cuenteo de tokens (testigos).
Contar tokens en las TLBs supone una forma natural y eficiente para la clasificación de páginas de memoria. Además, evita el uso de solicitudes persistentes o arbitraje alguno, ya que si dos o más TLBs compiten para acceder a una página, los tokens se
distribuyen apropiadamente y la clasifican como compartida.
Sin embargo, la habilidad de los mecanismos basados en TLB para clasificar páginas privadas depende del tamaño de las TLBs. La clasificación basada en las TLBs se basa en la presencia de una traducción en las TLBs del sistema. Para evitarlo, se han propuesto diversos predictores de uso en las TLBs (UP), los cuales permiten una clasificación independiente del tamaño de las TLBs. En concreto, esta tesis presenta un sistema mediante el que se obtiene información de uso de página a nivel de sistema con la ayuda de un nivel de TLB compartida (SUP) o mediante TLBs cooperando juntas (CUP). / La major part de les dades referenciades per aplicacions paral·leles i seqüencials que s'executen en CMPs actuals són referenciades per un sol fil, és a dir, són privades. Recentment, algunes propostes aprofiten aquesta observació per a millorar molts aspectes dels CMPs, com és reduir el sobrecost de la coherència o la latència d'accés a memòries cau distribuïdes. L'efectivitat d'aquestes propostes depen en gran mesura de la quantitat de dades detectades com a privades. No obstant això, els mecanismes proposats fins a la data no consideren la migració de fils d'execució ni les fases d'una aplicació. Per tant, una quantitat considerable de dades privades no es detecta apropiadament. A fi d'augmentar la detecció de dades privades, aquesta tesi proposa un mecanisme basat en les TLBs, capaç de reclassificar les dades com a privades, i que detecta la migració dels fils d'execució sense afegir complexitat al sistema. Els mecanismes de classificació en les TLBs s'han analitzat en estructures de diversos nivells, incloent-hi sistemes amb TLBs d'últimnivell compartides i distribuïdes.
Aquesta tesi presenta un mecanisme de classificació de pàgines basat en inspeccionar les TLBs d'altres nuclis després de cada fallada de TLB. Concretament, el mecanisme proposat es basa en l'intercanvi i el compte de tokens. Comptar tokens en les TLBs suposa una forma natural i eficient per a la classificació de pàgines de memòria. A més, evita l'ús de sol·licituds persistents o arbitratge, ja que si dues o més TLBs competeixen per a accedir a una pàgina, els tokens es distribueixen apropiadament i la classifiquen com a compartida.
No obstant això, l'habilitat dels mecanismes basats en TLB per a classificar pàgines privades depenen de la grandària de les TLBs. La classificació basada en les TLBs resta en la presència d'una traducció en les TLBs del sistema. Per a evitar-ho, s'han proposat diversos predictors d'ús en les TLBs (UP), els quals permeten una classificació independent de la grandària de les TLBs. Específicament, aquesta tesi introdueix un predictor que obté informació d'ús de la pàgina a escala de sistema mitjançant un nivell de TLB compartida (SUP) or mitjançant TLBs cooperant juntes (CUP). / Esteve García, A. (2017). Design of Efficient TLB-based Data Classification Mechanisms in Chip Multiprocessors [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86136
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Evaluation of Foveal Cone and M?ller Cells in Epiretinal Membrane using Adaptive Optics OCT / 補償光学適用光干渉断層計を用いた黄斑上膜における錐体細胞とミュラー細胞の形態評価Ishikura, Masaharu 25 March 2024 (has links)
京都大学 / 新制・課程博士 / 博士(医学) / 甲第25171号 / 医博第5057号 / 新制||医||1071(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 花川 隆, 教授 林 康紀, 教授 高橋 淳 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
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Benefits and accessibility of OCTA imaging for diabetic retinopathy and macular edemaRhee, Jae 08 November 2024 (has links)
Diabetic retinopathy (DR) and diabetic macular edema (DME) are among the leading causes of vision loss worldwide. Early detection and timely intervention are crucial in decreasing the risk of vision impairment worldwide. Optical Coherence Tomography Angiography (OCTA) is an emerging imaging modality that has advantages to the current standard for assessing retinal microvascular changes in diabetic eye diseases. This study aims to evaluate the cost-effectiveness of different screening strategies incorporating OCTA for the detection and management of DR and DME.
A decision tree model (Figure 2) was created to estimate the cost consequences of different screening strategies for clinically significant macular edema (CSME) and severe DR in the United States. The model can be used to compare two screening arms: A) standard fluorescein angiography (FA) and optical coherence tomography (OCT) scans with standard of care follow-up.; and B) Universal OCTA imaging with FA and OCT scans with standard of care follow-up. In both strategies, screening will start with the most sensitive imaging (OCTA > OCT > FA) that is available.
Strategy A will serve as the control with the current standard image screening protocol for DME and DR diagnosis, which is based on the National Institute of Clinical Excellence (NICE) guidelines used in both the U.S. and U.K. These guidelines include FA imaging and a visual acuity test within 3 months of diagnosis of diabetes. In accordance with the guidelines, if DR or CSME is identified the participant will subsequently be referred to an ophthalmologist at which point OCT will also be obtained at this visit. If no DR or CSME is identified during imaging, the guidelines state that follow-up imaging should be conducted every 6 months.
Strategy B will involve universal OCTA Imaging, FA imaging, OCT scans and a visual acuity test. Screening with OCTA imaging should be conducted before proceeding to screen the FA images taken. If criteria for CSME or severe DR is met, then the participant will be referred to an ophthalmologist. If criteria for CSME or severe DR is not met, then the participant will receive follow up imaging every 6 months.
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Micro-injection moulded microneedles for drug delivery.Nair, Karthik Jayan January 2014 (has links)
The emergence of microneedle (MN) technologies offers a route for a pain free, straightforward and efficient way of transdermal drug delivery, but technological barriers still exist which pose significant challenges for manufacture of MN systems with high volume outputs at low cost. The main aim of this research was to develop new ways for MN manufacture primarily using micro-injection moulding processes with high performance engineering thermoplastics.
During the moulding process these polymeric melts will be subjected to extreme stress and temperature gradients and detailed material characterisation combined with in-line monitoring is desirable to optimise the moulding parameters and will help in achieving sharp microneedles with acceptable quality. Hence high shear rheology of these selected materials was performed at wall shear rates carried out in excess of 107 s-1 over a range of temperatures to predict the flow behaviour of polymer melts at such high shear strain rates. This information was fed into injection moulding simulation software tools (Moldflow) to assist the MN production process design. The optimal design was then used to produce a full 3D solid model of the injection mould and mould insert.
Furthermore various design of experiments were conducted considering input parameters such as injection pressure, injection speed, melt temperature, filling time and mould cavity temperature. Response variables including product quality and data acquired from the cavity pressure and temperature transducers were used to optimise the manufacturing process. The moulded MNs were geometrically assessed using a range of characterisation techniques such as atomic force microscopy, confocal microscopy and scanning electron microscopy. An attempt to make hollow MNs was performed and encountered many challenges like partial cavity filling and part ejection during processing. Studies were carried out to understand the problem and identified the major problem was in tool design and improvements to the moulding tool design were recommended.
Plasma treatment and mechanical abrasion were employed to increase the surface energy of the moulded polymer surfaces with the aim of enhancing protein adsorption. Sample surface structures before and after treatment were studied using AFM and surface energies have been obtained using contact angle measurement and calculated using Owens-Wendt theory. Adsorption performance of bovine serum albumin and release kinetics for each sample set was assessed using a Franz diffusion cell. Results indicate that plasma treatment significantly increases the surface energy and roughness resulting in better adsorption and release of BSA.
To assist design-optimisation and to assess performance, a greater understanding of MN penetration behaviour is required. Contact stiffness, failure strength and creep behaviour were measured during compression tests of MN against a steel surface, and in-vitro penetration of MNs into porcine skin. The MN penetration process into porcine skin was imaged using optical coherence tomography. Finally, a finite element model of skin was established to understand the effect of tip geometry on penetration.
The output of findings from this research will provide proof of concept level development and understanding of mechanisms of MN penetration and failure, facilitating design improvements for micro-injection moulded polymeric MNs.
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Studie- och yrkesvägledares upplevelse av autonomi i arbetet / Career guidance counselors experience of autonomy at workNälsén, Amanda, Salovaara, Carolina January 2024 (has links)
This study looks at how career guidance counselors in high school experience the degree of autonomy in their work. We have interviewed eight career guidance counselors in high school and use semi-structured interviews designed based on the concept of autonomy and the three dimensions of the Sense of coherence-theory: comprehensibility, manageability and meaningfulness. The interviews have then been analyzed through a thematic analysis based on SOC and the concept of autonomy. The empirical evidence shows that all respondents experience that they have a high degree of autonomy. We also see that the respondents experience and manage autonomy in the career guidance role in three different ways and have thus been able to distinguish three different SOC types among our respondents. Six of them are type 1, which have high values on all three dimensions of SOC. One is type 4, which means low comprehensibility, low manageability and high meaningfulness. One is type 7 with low comprehensibility, high manageability and low meaningfulness. We show that the professional role is an example of flexible work, which in today's society is something that is sought after. / Denna studie tittar på hur studie- och yrkesvägledare inom gymnasieskolan upplever graden av autonomi i arbetet. Vi har intervjuat åtta studie- och yrkesvägledare inom gymnasieskolan och använder oss av semistrukturerade intervjuer utformade utifrån autonomibegreppet och KASAM-teorins tre dimensioner: begriplighet, hanterbarhet och meningsfullhet. Intervjuerna har sedan analyserats genom en tematisk analys utifrån KASAM och begreppet autonomi. Empirin visar att alla respondenter upplever att de har en hög grad av autonomi. Vi ser även att respondenterna upplever och hanterar autonomi i studie- och yrkesvägledarrollen på tre olika sätt och har därmed kunnat urskilja tre olika KASAM-typer bland våra respondenter. Sex av dem är typ 1, vilka har höga värden på KASAM:s alla tre dimensioner. En är typ 4 vilket innebär en låg begriplighet, låg hanterbarhet och hög meningsfullhet. En är typ 7 med låg begriplighet, hög hanterbarhet och låg meningsfullhet. Vi visar att yrkesrollen är ett exempel på flexibelt arbete, vilket i dagens samhälle är något som eftertraktas.
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A novel approach to multiple reference frequency domain adaptive controlVaudrey, Michael A. 29 August 2008 (has links)
Adaptive feedforward control of any physical system, acoustical, vibrational or other, requires what is termed as an uncontrollable coherent reference signal. That is, a signal which is highly representative (coherent) of the disturbance to be controlled which is not affected by the control actuator itself. Creating the <i>coherent</i> portion of this requirement for a certain class of problems is the motivation of this work.
Most physical disturbances do not originate from a single source, but rather maintain contributions from a number of (possibly) correlated paths. For engineers who have access to only a single-input single-output (SISO) adaptive controller, the multi-source disturbance presents a difficult design issue. Simply adding the references in a linear combination can result in a signal which is not coherent at any frequency. Appropriately amplifying and suppressing coherent and incoherent signals prior to their linear combination can result in a signal which accurately represents the disturbance at all frequencies. This is precisely the task that the newly developed coherent output power (COP) filters perform.
By calculating the coherent (or partial coherent) output power of each of the candidate references before control occurs, frequency domain filters are designed to remove incoherent portions of each signal. The advantages of performing the COP filtering procedure are very apparent when compared to the simple linear combination of signals. Coherence, and thus control performance, can be drastically improved. The COP filtering technique offers a means for system identification and computational savings not apparent in the conventional adaptive array, which solves the same multi-source problem. / Master of Science
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Depth-resolved variations in visibility of retinal nerve fibre bundles across the retina in enface OCT images of healthy eyes.Cheloni, Riccardo, Denniss, Jonathan 06 November 2020 (has links)
Yes / Recent developments in optical coherence tomography (OCT) technology enable direct enface visualisation of retinal nerve fibre bundle (RNFB) loss in glaucoma. However, the optimum depth at which to visualise RNFBs across the retina is unknown. We aimed to evaluate the range of depths and optimum depth at which RNFBs can be visualised across the retina in healthy eyes.
The central ± 25° retina of 10 healthy eyes from 10 people aged 57–75 years (median 68.5 years) were imaged with spectral domain OCT. Slab images of maximum axial resolution (4 μm) containing depth‐resolved attenuation coefficients were extracted from 0 to 193.5 μm below the inner limiting membrane (ILM). Bundle visibility within 10 regions of a superimposed grid was assessed subjectively by trained optometrists (n = 8), according to written instructions. Anterior and posterior limits of RNFB visibility and depth of best visibility were identified for each grid sector. Effects of retinal location and individual eye on RNFB visibility were explored using linear mixed modelling with likelihood ratio tests. Intraclass correlation coefficient (ICC) was used to measure overall agreement and repeatability of grading. Spearman’s correlation was used to measure correlation between depth range of visible RNFBs and retinal nerve fibre layer thickness (RNFLT).
Retinal location and individual eye affected anterior limit of visibility (χ2(9) = 58.6 and 60.5, both p < 0.0001), but none of the differences exceeded instrument resolution, making anterior limit consistent across the retina and different eyes. Greater differences were observed in the posterior limit of visibility across retinal areas (χ2(9) = 1671.1, p < 0.0001) and different eyes (χ2(9) = 88.7, p < 0.0001). Optimal depth for visualisation of RNFBs was around 20 µm below the ILM in most regions. It varied slightly with retinal location (χ2(9) = 58.8, p < 0.0001), but it was not affected by individual eye (χ2(9) = 10.7, p = 0.29). RNFB visibility showed good agreement between graders (ICC 0.89, 95%CI 0.87–0.91), and excellent repeatability (ICC 0.96–0.99). Depth range of visible RNFBs was highly correlated with RNFLT (ρ = 0.9, 95%CI: 0.86–0.95).
The range of depths with visible RNFBs varies markedly across the healthy retina, consistently with RNFLT. To extract all RNFB information consistently across the retina, slab properties should account for differences across retinal locations and between individual eyes. / This work was supported by a College of Optometrists Research Fellowship (JD).
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The relationship between work performance and sense of coherenceMoerane, Elias Mochabo 30 November 2005 (has links)
This dissertation investigates the relationship between work performance and the sense of coherence, using the salutogenesis approach and the influence of employees' biographical variables on work performance.
The sense of coherence construct is discussed and conceptualised in terms of its comprehensibility, manageability and meaningfulness. Similarly, work performance is discussed and conceptualised in terms of its dimensions and dynamics. The integration of the literature study characteristics such as the cognitive, affective, conative and interpersonal characteristics were discussed.
The research was conducted among 80 employees at a banking institution. The quality of life questionnaire and performance appraisal ratings were used. The relationship between biographical variables such as age, marital status, gender, qualifications, tenure, functional department and work performance were investigated. The results confirmed the empirical investigation that there was not a significant relationship between work performance and SOC. However, a significant relationship was found between job category and work performance, and between age and work performance.
Finally, recommendations made for future research included using a bigger sample size in order to improve the generalisation of the findings to other organisational environments, and to further determine the relationship between other aspects of work performance (not just the KPAs) such as the human attributes of work performance and SOC. / Industrial and Organisational Psychology / M.A. (Industrial and Organisational Psychology)
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An exploratory factor analysis on the measurement of psychological wellnessGropp, Liezl 30 June 2006 (has links)
This research investigated the psychometric characteristics of self-actualisation, locus of control, sense of coherence and emotional intelligence as constructs of psychological wellness. Details of the intercorrelatedness of the various constructs will assist in understanding the nature of psychological wellness and its measurement.
In the literature review a definition for psychological wellness was determined by studying various definitions and models of psychological wellness. During this investigation it was determined that the four constructs mentioned above were related to psychological wellness.
An explorative factor analysis was conducted to address the empirical research questions. Three factors (psychological adjustment, self-actualisation and stress management) were extracted from the analysis. The descriptive statistics were analysed in terms of management responsibility, gender and race.
The findings of the explorative factor analysis supported the theoretical definition of psychological wellness. It was found that self-actualisation played a key role in psychological wellness. Meaningfulness, although indicating a low loading on all three factors, must be present to provide meaning to day to day functioning. / Industrial and Organisational Psychology / MCOM (Industrial and Organisational Psychology)
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Salutogenic functioning amongst university administrative staffMtsweni, Sipho Herold 30 June 2007 (has links)
This study provides an orientation towards coping with stress management
through salutogenic functioning. Six constructs, namely, sense of
coherence, hardiness, self-efficacy, potency, learned resourcefulness and
locus of control, were studied as it manifest amongst random sampled
university administrative staff.
The literature review focused on salutogenic functioning, coping and stress,
integrated in the salutogenic personality profile.
The results from the research revealed positive correlations between
external locus of control and self-efficacy and meaningfulness, autonomy
and self control, internal locus of control and meaningfulness, internal locus
of control and meaningfulness, challenge and meaningfulness. Negative
correlations existed between autonomy and self-efficacy and
comprehensibility, potency and all locus of control dimensions, males and
females differed in their self control and external control, black africans had
the lowest score on external control, and there was no relationship between
age and the constructs.
Conclusions and recommendations were made regarding the optimisation of
salutogenic functioning among university administrative staff. / Industrial and Organisational Psychology / M.A. (Industrial and Organisational Psychology)
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