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Dissertations / Theses on the topic 'Pain detection'
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Mahon, Mary L. "Pain perception in chronic pain patients : a signal detection analysis." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/31127.
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The purpose of this investigation was to examine the supposition that chronic pain patients (CPPs) have altered pain perception. Two models were examined that led to opposing predictions as to how CPPs would respond to painful stimuli (i.e., the hypervigilance and adaptation-level models). Both predictions have been supported by past research but because of methodological variation and the type of pain disorder studied, it has remained unclear under what circumstances the predictions of these two models may be met.
The responses of pain patients to painful stimuli have been found to vary for patients-with different clinical presentations (i.e. those with and without medically incongruent signs and symptoms). Therefore, the present investigation sought to compare the responses to radiant heat stimuli of sixty CPPs (thirty with and thirty without a medically incongruent pain presentation) to thirty age and sex matched normal control subjects (i.e., pain-tree individuals). Signal detection theory methodology was used in order to separately evaluate sensory sensitivity and the response bias to report sensations as painful. In addition, cognitive and affective factors were assessed in order to identity potential psychological correlates of altered pain perception.
The results of this study indicated that the presence of a medically incongruent pain presentation distinguished patients on their subjective report of disability and to a lesser extent cognitive appraisal and affective distress regarding their pain condition. They did not differ in their responses to painful stimuli. In a post hoc analysis where CPPs were classified into 'organic' and 'functional’ diagnostic groups, significant differences in pain threshold and the response bias to report pain were found. Patients classified as 'organic' had significantly higher pain thresholds compared to normal control subjects and patients classified as 'functional'. Differences in pain threshold were primarily represented by the response' bias to report sensations as painful rather than sensory sensitivity to the stimuli. The 'functional' group had a slightly lower pain threshold than the normal control group but this difference was not significant. The results are discussed in light of the two models of pain perception. The two methods used to classify pain patients are discussed according to their orthogonal characteristics on sensory, cognitive, and affective components.Arts, Faculty of
Psychology, Department of
Graduate
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Lloyd, Emily Paige. "Race Deficits in Pain Authenticity Detection." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1531912112953475.
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Mettam, Jessica Jane. "The Detection and Alleviation of Pain in Fish." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526925.
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Miller, Amy Louise. "Detection and alleviation of pain and distress in laboratory rodents." Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519633.
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Tan, Chee-Wee. "Signal detection theory in the study of nociceptive and pain perception processes." Thesis, Queen Margaret University, 2008. https://eresearch.qmu.ac.uk/handle/20.500.12289/7409.
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Signal detection theory (SDT) measures (discriminability and response bias) have been proposed to be valid for determining pain perception changes. The construct validity of SDT measures applied to pain perception studies has been questioned on three grounds: interpretation, methodology and theory. Multiple interpretations are possible for the combinations of discriminability and response bias change when the magnitude-rating scale is used for pain perception studies. This is resolved by utilising the confidence-rating scale. The problem of comparability of results between the two scales is bridged by Irwin & Whitehead’s (1991) common analytical framework. The results of this thesis supported the framework’s prediction that both scales are comparable. Therefore, the confidencerating scale was used for all studies within this thesis for interpretational clarity. Response bias data were not analysed in this thesis due to data artefacts created by correction methods for zero proportions in response categories. Methodologically, the construct validity of discriminability is influenced by the research design and procedures. Therefore, the following procedures were adopted to address weaknesses in previous studies. The one-interval confidence-rating task was used with a six-category confidence-rating scale and post-trial feedback. Based on a methodological study conducted within this thesis, the trial number was pragmatically reduced from 40 trials to 17 trials per stimulus intensity. This trial number reduction would not alter the mean and variance of the data sufficiently to influence the outcome of inferential statistical testing performed. Due to the novel use of the Quantitative Sensory Testing machine for the signal detection study procedures, accuracy and precision study on the machine was performed. This thesis found that the accuracy, repeatability and reproducibility of the machine in generating noxious thermal stimuli is excellent for the purposes of this thesis. Machine error is eliminated as a major source of variance for the thesis results. Theoretically, critics have challenged the construct validity of discriminability as an indicator of pain perception alteration. This thesis examined this issue in two separate contexts: 1) discriminability change as a correlate of local anaesthesia and, 2) discriminability as a correlate of psychological factors (depression and anxiety) in chronic low back pain (CLBP) sufferers. The results failed to establish the construct validity of discriminability for both contexts. However, the higher discriminability in CLBP sufferers compared to healthy individuals is in contrast to past research and warrant further investigation. This thesis addressed the construct validity issues through theoretical, methodological and interpretational modifications. A more robust analysis of the construct validity issue was facilitated. Caution is recommended on the use of discriminability as a pain perception measure until the construct validity issue has been satisfactorily resolved.
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Goldsby, Tamara L. "Intuition, openness to experience, and other personality correlates of pain-faking detection ability." Thesis, University of Surrey, 2008. http://epubs.surrey.ac.uk/844380/.
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This study seeks to examine the relationship between personality variables and pain perception ability. Specifically this thesis hypothesises that the Intuitive psychological type (rooted in Jung's theories of psychological type) will be effective at detecting faking of physical pain. Additionally, this thesis hypothesises that those scoring highly on Openness to Experience, as well as those rating as extraverts and those who rate high in emotional intelligence, will be more accurate at pain-faking detection than individuals who do not demonstrate these personality traits. It is also hypothesised that participants rating high in Machiavellianism will be accurate in detecting pain deception. In addition, it is speculated that a gender factor will exist in the ability to detect pain deception. In the first study, the Myers-Briggs Type Indicator (MBTI; Myers & McCaulley, 1985) and the NEO Five Factor Inventory (NEO-FFI; Costa & McCrae, 1992b) are used to measure participants' intuition level and openness to experience (as well as extraversion), respectively. In the second study, the Mayer Salovey Caruso Emotional Intelligence Test (MSCEIT; Mayer, Salovey & Caruso, 2002) and the Psychopathic Personality Inventory (PPI; Lilienfeld & Widows, 2005) are used to measure emotional intelligence and various psychopathy-related traits (including Machiavellianism), respectively. The stimuli presented are videotapes of facial expressions of pain, in which individuals display either genuine or faked physical pain. The first study's findings support the hypotheses that Intuitive and Open individuals are accurate at pain judgment, with Intuitive and Open females in particular displaying relationships with accuracy. Additionally, males categorised as 'Thinker' types, as well as those low in neuroticism predicted accuracy in pain judgment. However, the hypothesis that extraverted individuals would be more accurate at detection was largely unsupported. In the second study, the hypotheses that overall emotional intelligence and overall psychopathy would predict accuracy were generally unsupported. It was discovered, however, that particular subscales of the emotional intelligence measure such as the 'Changes' task were predictors of accuracy in pain judgment. The Machiavellianism subscale of the psychopathy measure was indeed a predictor of accuracy for male participants. In addition, other subscales of the psychopathy measure that predicted accuracy included Blame Externalisation, which had an inverse relationship with accuracy, as well as 'Fearlessness' in female participants. The significance of the study findings are discussed in terms of application to the realm of deception detection, as well as its relevance to the medical field in particular.
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Ogawa, Nozomi. "Detection of cellular redox status by transient receptor potential channels." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215577.
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Sinha, Manas Kumar. "Ischemia modified albumin for the detection of myocardial ischaemia in acute coronary syndromes and chest pain syndromes." Thesis, St George's, University of London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406680.
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Doyle, Jason Emory. "Automatic Dynamic Tracking of Horse Head Facial Features in Video Using Image Processing Techniques." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/87582.
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The wellbeing of horses is very important to their care takers, trainers, veterinarians, and owners. This thesis describes the development of a non-invasive image processing technique that allows for automatic detection and tracking of horse head and ear motion, respectively, in videos or camera feed, both of which may provide indications of horse pain, stress, or well-being. The algorithm developed here can automatically detect and track head motion and ear motion, respectively, in videos of a standing horse. Results demonstrating the technique for nine different horses are presented, where the data from the algorithm is utilized to plot absolute motion vs. time, velocity vs. time, and acceleration vs. time for the head and ear motion, respectively, of a variety of horses and ponies. Two-dimensional plotting of x and y motion over time is also presented. Additionally, results of pilot work in eye detection in light colored horses is also presented. Detection of pain in horses is particularly difficult because they are prey animals and have mechanisms to disguise their pain, and these instincts may be particularly strong in the presence of an unknown human, such as a veterinarian. Current state-of-the art for detecting pain in horses primarily involves invasive methods, such as heart rate monitors around the body, drawing blood for cortisol levels, and pressing on painful areas to elicit a response, although some work has been done for humans to sort and score photographs subjectively in terms of a "horse grimace scale." The algorithms developed in this thesis are the first that the author is aware for exploiting proven image processing approaches from other applications for development of an automatic tool for detection and tracking of horse facial indicators. The algorithms were done in common open source programs Python and OpenCV, and standard image processing approaches including Canny Edge detection Hue, Saturation, Value color filtering, and contour tracking were utilized in algorithm development. The work in this thesis provides the foundational development of a non -invasive and automatic detection and tracking program for horse head and ear motion, including demonstration of the viability of this approach using videos of standing horses. This approach lays the groundwork for robust tool development for monitoring horses non-invasively and without the required presence of humans in such applications as post-operative monitoring, foaling, evaluation of performance horses in competition and/or training, as well as for providing data for research on animal welfare, among other scenarios.MS
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Chew, Sien Wei. "Recognising facial expressions with noisy data." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/63523/1/Sien_Wei_Chew_Thesis.pdf.
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Techniques to improve the automated analysis of natural and spontaneous facial expressions have been developed. The outcome of the research has applications in several fields including national security (eg: expression invariant face recognition); education (eg: affect aware interfaces); mental and physical health (eg: depression and pain recognition).
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Morabit, Safaa El. "New Artificial Intelligence techniques for Computer vision based medical diagnosis." Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2023. http://www.theses.fr/2023UPHF0013.
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La capacité à ressentir la douleur est cruciale pour la vie, car elle sert de système d’alerteprécoce en cas de dommages potentiels pour le corps. La majorité des évaluations dela douleur reposent sur les rapports des patients. En revanche, les patients incapablesd’exprimer leur douleur doivent plutôt se fier aux rapports de tierces personnes sur leursouffrance. En raison des biais potentiel de l’observateur, les rapports sur la douleurpeuvent contenir des inexactitudes. En outre, il serait impossible de surveiller les patients 24 heures sur 24. Afin de mieux gérer la douleur, notamment chez les patients avec des difficultés de communication, des techniques de détection automatique de la douleur pourraient être mises en œuvre pour aider les soignants et compléter leur service. Les expressions faciales sont utilisées par la plupart des systèmes d’évaluation de la douleur basés sur l’observation, car elles constituent un indicateur fiable de la douleur et peuvent être interprétées à distance.En considérant que la douleur génère généralement un comportement facial spontané, les expressions faciales pourraient être utilisées pour détecter la présence de la douleur. Dans cette thèse, nous analysons les expressions faciales de la douleur afin d’aborder l’estimation de la douleur. Tout d’abord, nous présentons une analyse approfondie du problème en comparant de nombreuses architectures CNN (réseau de neurones convolutifs) courantes, telles que MobileNet, GoogleNet, ResNeXt-50, ResNet18et DenseNet-161. Nous utilisons ces réseaux dans deux modes uniques : autonome et extraction de caractéristiques. En mode autonome, les modèles (c’est-à-dire les réseaux)sont utilisés pour estimer directement la douleur. En mode extracteur de caractéristiques, les "valeurs" de la couche intermédiaire sont extraites et introduites dans desclassificateurs tels que la régression à vecteur de support (SVR) et la régression à forêtsd’arbres décisionnels (RFR).Les CNN ont obtenu des résultats significatifs dans la classification d’images et ontconnu un grand succès. Plus récemment, l’efficacité des Transformers en vision par ordinateur a été démontrée par plusieurs études. Des architectures basées sur les Transformers ont été proposées dans la deuxième section de cette thèse. Ces deux architectures distinctes ont été présentées pour répondre à deux problèmes distincts liés àla douleur : la détection de la douleur (douleur vs absence de douleur) et la distinction entre la douleur authentique et la douleur simulée. L’architecture innovante pourl’identification binaire de la douleur faciale est basée sur des transformateurs d’imagesefficaces en termes de données (Deit). Deux bases de données, UNBC-McMaster shoulder pain et BioVid heat pain, ont été utilisées pour affiner et évaluer le modèle formé. Ladeuxième architecture proposée, repose sur des transformateurs de vision pour la détection de douleurs authentiques et simulées à partir des expressions faciales (ViT). Pour distinguer la douleur authentique de la douleur simulée, le modèle doit accorder uneattention particulière aux changements subtils des expressions faciales dans le temps.L’approche employée prend en compte l’aspect séquentiel et capture les variations des expressions faciales. Les expériences ont été menées sur la base de données BioVid HeatPain démontrent l’efficacité de notre stratégieThe ability to feel pain is crucial for life, since it serves as an early warning system forpotential harm to the body. The majority of pain evaluations rely on patient reports. Patients who are unable to express their own pain must instead rely on third-party reportsof their suffering. Due to potential observer bias, pain reports may contain inaccuracies. In addition, it would be impossible for people to keep watch around the clock. Inorder to better manage pain, especially in noncommunicative patients, automatic paindetection technologies might be implemented to aid human caregivers and complementtheir service. Facial expressions are used by all observer-based pain assessment systemsbecause they are a reliable indicator of pain and can be interpreted from a distance.Taking into consideration that pain generally generates spontaneous facial behavior,these facial expressions could be used to detect the presence of pain. In this thesis, weanalyze facial expressions of pain in order to address pain estimation. First, we presenta thorough analysis of the problem by comparing numerous common CNN (Convolutional Neural Network) architectures, such as MobileNet, GoogleNet, ResNeXt-50, ResNet18, and DenseNet-161. We employ these networks in two unique modes: standalone and feature extraction. In standalone mode, models (i.e., networks) are utilized to directly estimate pain. In feature extractor mode, "values" from the middle layer are extracted and fed into classifiers like Support Vector Regression (SVR) and Random Forest Regression (RFR).CNNs have achieved significant results in image classification and have achievedgreat success. The effectiveness of Transformers in computer vision has been demonstrated through recent studies. Transformer-based architectures were proposed in the second section of this thesis. Two distinct Transformer-based frameworks were presented to address two distinct pain issues: pain detection (pain vs no pain) and thedistinction between genuine and posed pain. The innovative architecture for binaryidentification of facial pain is based on data-efficient image transformers (Deit). Twodatasets, UNBC-McMaster shoulder pain and BioVid heat pain, were used to fine-tuneand assess the trained model. The suggested architecture is built on Vision Transformers for the detection of genuine and simulated pain from facial expressions (ViT). Todistinguish between Genuine and Posed Pain, the model must pay particular attentionto the subtle changes in facial expressions over time. The employed approach takes intoaccount the sequential aspect and captures the variations in facial expressions. Experiments on the publicly accessible BioVid Heat Pain Database demonstrate the efficacy of our strategy
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Ghasemi, Ghaleh Bahmani Afsaneh. "Machine perception of human emotions using motion patterns." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/104297/1/Afsaneh_Ghasemi%20Ghaleh%20Bahmani_Thesis.pdf.
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We propose novel, intelligent facial expression recognition systems as well as unique encoding of the dynamics of facial actions, enabling machines to have the ability to sense and understand human visual interaction signals. Various methodologies have been proposed to address the existing limitations in performance as well as the computing resource constraints, to advance the field of automatic human emotion recognition.
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Curnow, David. "Validation of the Barkemeyer-Callon-Jones malingering detection scale: The ability of a scale differentiate simulating malingers from controls and prior litigants from those with No litigation experience within a sample of men who have all suffered chronic low back pain." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 1998. https://ro.ecu.edu.au/theses/1446.
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Chronic low back pain costs the community, and several authors have suggested that individuals often attempt to exaggerate chronic low back pain. Currently no reliable and valid scale for assessing malingering in chronic pain populations exists, and there is a large difference in opinion on the ability of experts using clinical judgment to detect malingering. The current study seeks to provide a validation for the BarkemeyerCallon-Jones Malingering Detection Scale (MDS) which has purported to be able to identify individuals attempting to malinger neurological conditions and pain. A simulation design was used, as in previous research, because it is difficult to identify actual malingerers in a known groups design. Thirty-two men with chronic low back pain were divided into two groups of sixteen. One group was asked to simulate malingering for the purposes of gaining an increased compensation while the other group is asked to be as honest as possible. The hypotheses tested were whether the responses to the MDS can: discriminate between simulating malingerers and controls, show an increased focus on severity rather than description of pain by simulating malingerers, show a relationship between malingering scores and reported pain levels, show that prior litigation contributes to either MDS scores or reported pain levels. Significance was assessed using chi square, t-test, bivariate correlation and two ANOVAs. While the MDS was able to discriminate to a significant level between participants asked to malinger and those being honest, methodological issues suggest that levels of pre-assessment injury contribute to malingering scores and that conscious intent is what separates malingering from psychological disorders (abnormal illness behaviour) is context bound. Litigation has no effect on reported pain level or MDS scores.
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Moore, Jay Gershon. "Temperature measurement and transition detection using temperature-sensitive paint." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10988.
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Balla, Joseph V. "Pressure-Sensitive Paint for Detection of Boundary Layer Transition." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345552359.
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Grewe, Jennifer R. "Detecting Malingering in Compensated Low Back Pain Patients: An Analog Study." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/552.
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Given the prevalence and cost of low back pain, particularly among workers' compensation patients, it is advantageous to understand how various psychological constructs may be related to prolonged disability and failure to return to work. Malingering is a psychological construct that is clearly relevant for worker compensation populations and is a construct that is well suited for experimental control within an analog study. Malingering is the intentional exaggeration of physical or psychological symptoms that are motivated by external incentives such as time away from work. The ability to detect malingering in such a population with psychological assessments is unclear. An analog study was conducted in which we instructed college students to portray themselves as injured workers who received a back injury that required them to be off work while they recovered. Students were then told that they would be seeing a psychologist who would attempt to ascertain their abilities to return to work via the MMPI-2. Students were then randomly instructed to respond to the MMPI-2 in three different ways: a control condition was instructed to respond as if they suffered a workplace back injury that resulted in significant pain; a subtle fake-bad condition who received the control instruction plus were informed they did not enjoy their work and their back injury allowed them to enjoy personal and family time more; and a fake-bad condition that received the control instruction plus were asked to deliberately portray themselves as experiencing physical symptoms severe enough to keep them off work longer. Currently, no assessment of malingering exists within a compensated low back pain population. The purpose of this study was to determine if the MMPI-2 can be used to differentially identify "patients" who are instructed to report symptoms veridically versus "patients" instructed to consciously feign and magnify symptoms in an effort to avoid returning to work. Malingering and non-malingering patients' scores on the MMPI-2 validity and clinical scales were subjected to a cluster analysis to determine if a malingering profile could be accurately identified. A 5-cluster validity solution and 4-cluster clinical (both with K correction) solution were accepted. Substantially lower scores on L and K, elevated scores on F on the 5-cluster validity solutions, distinguished the "malingering" profile. The 4-cluster clinical solution was characterized by elevated scores on the clinical scales of hypochondriasis, depression, paranoia, and schizophrenia, which distinguished the "malingering" profile. The results indicate that the MMPI-2 could be useful in detecting malingering in compensated back pain patients. Results are discussed in the context of pain studies.
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Tothill, I. E. "The detection and characterisation of cellulolytic activity in emulsion paint." Thesis, Cranfield University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234507.
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Sverchkov, Yuriy. "Detection and explanation of statistical differences across a pair of groups." Thesis, University of Pittsburgh, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3647988.
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The task of explaining differences across groups is a task that people encounter often, not only in the research environment, but also in less formal settings. Existing statistical tools designed specifically for discovering and understanding differences are limited. The methods developed in this dissertation provide such tools and help understand what properties such tools should have to be successful and to motivate further development of new approaches to discovering and understanding differences.
This dissertation presents a novel approach to comparing groups of data points. The process of comparing groups of data is divided into multiple stages: The learning of maximum a posteriori models for the data in each group, the identification of statistical differences between model parameters, the construction of a single model that captures those differences, and finally, the explanation of inferences of differences in marginal distributions in the form of an account of clinically significant contributions of elemental model differences to the marginal difference. A general framework for the process, applicable to a broad range of model types, is presented. This dissertation focuses on applying this framework to Bayesian networks over multinomial variables.
To evaluate model learning and the detection of parameter differences an empirical evaluation of methods for identifying statistically significant differences and clinically significant differences is performed. To evaluate the generated explanations of how differences in the models account for the differences in probabilities computed from those models, case studies with real clinical data are presented, and the findings generated by explanations are discussed. An interactive prototype that allows a user to navigate through such an explanation is presented, and ideas are discussed for further development of data analysis tools for comparing groups of data.
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Augustian, Midhumol. "Neural network based fault detection on painted surface." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-141070.
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Machine vision systems combined with classification algorithms are being increasingly used for different applications in the age of automation. One such application would be the quality control of the painted automobile parts. The fundamental elements of the machine vision system include camera, illumination, image acquisition software and computer vision algorithms. Traditional way of thinking puts too much importance on camera systems and ignores other elements while designing a machine vision system. In this thesis work, it is shown that selecting an appropriate illumination for illuminating the surface being examined is equally important in case of machine vision system for examining specular surface. Knowledge about the nature of the surface, type and properties of the defect to be detected and classified are important factors while choosing the illumination system for the machine vision system. The main illumination system tested were bright field, dark field and structured illumination and out of the three, dark field and structured illumination gave best results. This thesis work proposes a dark field illumination based machine vision system for fault detection on specular painted surface. A single layer Artificial Neural Network model is employed for the classification of defects in intensity images of painted surface acquired with this machine vision system. The results of this research work proved that the quality of the images and size of data set used for training the Neural Network model play a vital role in the performance of the classifier algorithm.
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Alamin, Mohammed. "Passive low frequencey RFID for detection and monitoring of corrosion under paint and insulation." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2347.
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Despite decades of research, corrosion under insulation (CUI) still presents significant challenges for non-destructive testing and evaluation (NDT&E). One of the biggest challenges posed by CUI is the inaccessibility due to the large standoff distance intro-duced by thick insulation. The hidden nature of CUI may result in it going unnoticed for long periods of time leading to potentially catastrophic failures. Electromagnetic NDT&E techniques, which are widely employed in the pipeline industries in various forms, have large decrease in sensitivity primarily due to the insulation layer. Methods to overcome this typically involve either the removal of insulation or the use of high powered and expensive equipment. Limitations of existing NDT&E techniques create opportunities for novel approaches to tackle the challenges posed by CUI. This research project, funded by the Engineering and Physical Sciences Research Coun-cil (EPSRC) CASE studentship in collaboration with International Paint®, proposes the use of passive low frequency (LF) RFID hardware for the detection and monitoring of corrosion on insulated pipes. The battery-free, low cost nature of RFID makes it attrac-tive for long term condition monitoring. Experimental studies have been conducted us-ing carefully designed samples to demonstrate the detection capabilities of the proposed system. The contribution of the research can be summarised as follows: (1) experimen-tal feasibility study demonstrating the detection capabilities at large standoff distances; (2) demonstration of the increased sensitivity of the proposed system compared to tradi-tion eddy current (EC) method; (3) use of multivariate statistical analysis to identify the most dominant features and relate them to time-domain features of the RFID waveform; (4) application of principal component analysis (PCA) to overcome the dependence of the aforementioned features on the position of the reader coil; and (5) performed accel-erated CUI testing to demonstrate the potential of the RFID system in a realistic test scenario. This work concludes that passive LF RFID hardware can be used to detect corrosion on steel under thick insulation. In comparison to traditional EC method, the RFID based method shows greater sensitivity at large standoff distances. However, significant chal-lenges, particularly the high temperature survivability of RFID tags, limit the real-world applicability.
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Kamat, Ashish V. "AN INVESTIGATION OF IMAGE PROCESSING TECHNIQUES FOR PAINT DEFECT DETECTION USING A MACHINE VISION SYSTEM." UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_theses/332.
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Detection and inspection of metal surface corrosion in the ballast tanks of U.S. Navy ships has been a long time problem. The adverse climatic conditions to which the ballast tanks are exposed and the uneven geometry of ballast tanks makes the visual inspection process of surface coatings a difficult job. Thousands of tanks are inspected yearly, with the average cost of an individual tank inspection at approximately $8-15 thousand/each. To aid the visual inspection process, this research is conducted to develop a new technique to automate the visual task of metal surface inspection by image acquisition and post processing. The best results of image processing are achieved by the enhanced contrast between the paint defect and the background using a newly developed optically active additive (OAA) used in paints. Thorough investigation of image processing algorithms has been carried out and a background of imaging theory and experiments is illustrated in this work.
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Ke, Song-Hua. "Determination of non-watson-crick base pair stability and development of a new method for mutation detection." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/25198.
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Zgallai, Walid A. "Advanced robust non-invasive foetal heart detection techniques during active labour using one pair of transabdominal electrodes." Thesis, City University London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440694.
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Chatziplis, Dimitrios. "The use of selective genotyping in the detection of quantitative trait loci (QTL) by sib pair analysis." Thesis, University of Edinburgh, 1998. http://hdl.handle.net/1842/14410.
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This study covered two main areas in the methodology of Quantitative Trait Locus (QTL) detection with the use of genetic markers: i) the use of sib pair analysis for QTL detection in animal populations of large family size and ii) the use of selective genotyping in sib pair analysis for the reduction of genotyping costs. The regression of the squared phenotypic differences of sib pairs on the proportion of alleles they share Identical By Descent (IBD) at a marker locus can provide a test of linkage between a marker and a QTL. The t-values of the regression coefficient can provide a way to detect linkage. The regression coefficient can provide estimates of the QTL position and variance. The power of detection and parameter estimates (position and QTL variance) obtained from the analysis of progeny originating from populations with different family size, were compared using simulated data. Families of large size provide large numbers of sib pairs, since the number of sib pairs is related to the family size. The correlation of phenotypic differences between sib pairs of the same family has little effect on the test statistic and consequently on the power of detection. In order to decrease the amount of genotyping without any negative effects on the power of detection, a different approach to sib pair analysis was used. Instead of using the associations between phenotypic differences and proportion of alleles shared IBD at a marker locus for the detection of linkage, any changes in the proportion of alleles shared IBD at a marker locus in a selected sample of phenotypically discordant sib pairs could be used to identify linkage between the marker and a QTL. The t-values of the regression constant were used to test any deviations of the mean proportion of alleles shared IBD at a marker locus from the expected mean (0.5). It was found that this is the most powerful test statistic in samples of sib-pairs selected for high phenotypic differences.
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Kim, Dae Hwan. "The study of Z boson pair production with the OPAL detector at LEP /." view abstract or download file of text, 2000. http://wwwlib.umi.com/cr/uoregon/fullcit?p3003995.
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Thesis (Ph. D.)--University of Oregon, 2000.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 144-147). Also available for download via the World Wide Web; free to University of Oregon users.
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Cholez, Thibault. "Supervision des réseaux pair à pair structurés appliquée à la sécurité des contenus." Phd thesis, Université Henri Poincaré - Nancy I, 2011. http://tel.archives-ouvertes.fr/tel-00608907.
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L'objectif de cette thèse est de concevoir et d'appliquer de nouvelles méthodes de supervision capables d'appréhender les problèmes de sécurité affectant les données au sein des réseaux P2P structurés (DHT). Ceux-ci sont de deux types. D'une part les réseaux P2P sont utilisés pour diffuser des contenus illégaux dont l'activité est difficile à superviser. D'autre part, l'indexation des contenus légitimes peut être corrompue (attaque Sybil). Nous proposons tout d'abord une méthode de supervision des contenus basée sur l'insertion de sondes et le contrôle du mécanisme d'indexation du réseau. Celle-ci permet d'attirer l'ensemble des requêtes des pairs pour un contenu donné, puis de vérifier leur intention en générant des appâts très attractifs. Nous décrivons ainsi les faiblesses du réseau permettant la mise en œuvre de notre méthode en dépit des protections existantes. Nous présentons les fonctionnalités de notre architecture et en évaluons l'efficacité sur le réseau P2P KAD avant de présenter un déploiement réel ayant pour but l'étude des contenus pédophiles. Nous considérons ensuite la sécurité des données indexées dans une DHT. Nous supervisons le réseau KAD et montrons que celui-ci est victime d'une pollution particulièrement néfaste affectant 2/3 des fichiers mais aussi de nombreuses attaques ciblées affectant la sécurité des contenus stockés. Nous proposons un moyen de détecter efficacement cette dernière attaque en analysant la distribution des identifiants des pairs autour d'une référence ainsi qu'une contre-mesure permettant de protéger les pairs à un coût négligeable. Nous terminons par l'évaluation de la protection au sein de réseaux P2P réels.
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Mulligan, Padhraic Liam. "Fabrication and Characterization of Gallium Nitride Schottky Diode Devices for Determination of Electron-Hole Pair Creation Energy and Intrinsic Neutron Sensitivity." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448405475.
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Bielski, Rafal. "Top quark pair production measurements in the single lepton channel using the ATLAS detector." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/top-quark-pair-production-measurements-in-the-single-lepton-channel-using-the-atlas-detector(ff46d1b0-0102-47d5-a60c-3a9e4ae07c07).html.
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Three measurements of top-quark pair production cross sections in proton-proton collisions at sqrt(s) = 13 TeV using data collected by the ATLAS experiment are presented. The single-lepton final states are used, where one electron or muon, two b-jets and two other jets can be identified. The inclusive ttbar production cross section is measured to be sigma(ttbar) = 817 +/- 13 (stat.) +/- 103 (syst.) +/- 88 (lum.) pb, which is in good agreement with predictions and with other measurements. Absolute and relative differential cross sections of ttbar production are also measured, showing an overall good agreement with predictions, except for the top-quark transverse momentum distribution. As already reported in measurements at lower proton-proton collision energies, this distribution is shifted towards higher momenta in all predictions with respect to the observations. Total and differential fiducial cross sections of ttbar production in association with heavy-flavour jets are also presented. All tested models are found to agree with data within the uncertainties of these measurements.
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Makouski, Mikhail. "A measurement of top quark pair and photon production cross section with CMS detector." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19188.
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Doctor of PhilosophyPhysics
Andrew G. Ivanov
In this thesis the measurement of production cross section of top-quark pairs in association with a photon in proton-proton collisions at a center of mass energy of 8 TeV is presented. The data was recorded at the CMS experiment at the LHC in 2012. This measurement aims to extend our knowledge of top quark properties and help to test consistency of the Standard Model (SM) of particle physics. Data-driven methods are used to estimate the photon identification efficiency and purity. The measured cross-section agrees with the standard model expectation.
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Agaras, Merve Nazlim. "Searches for associated Higgs Boson production with top quark pair and Higgs pair production in multi lepton final states with the ATLAS detector." Thesis, Université Clermont Auvergne (2017-2020), 2020. http://www.theses.fr/2020CLFAC023.
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Depuis la découverte du boson de Higgs à une masse d'environ 125 GeV par les deux collaborations ATLAS et CMS en juillet 2012, il est devenu crucial de mesurer ses propriétés, telles que ses couplages avec d'autres particules, et de rechercher tout écart par rapport aux prévisions du Modèle Standard (SM). Le couplage Yukawa du quark top est proche de l'unité et est le plus fort dans le secteur fermionique. Par conséquent, ce couplage joue un rôle crucial dans la théorie. La détermination de la production de boson de Higgs avec une paire de quarks top (ttH) offre un accès a l'ordre dominant pour mesurer ce couplage. L'analyse de la production de ttH dans le cadre de l'expérience ATLAS exploite plusieurs canaux de désintégration du Higgs, ainsi que différents modes de désintégration des quarks top. Dans cette thèse, l'étude du processus ttH (H → Multi lepton) est présentée dans la topologie où le Higgs se désintègre en WW,ZZ ou tautau, en utilisant un ensemble de données correspondant à une luminosité intégrée de 79,8fb^-1 à √s = 13 TeV, recueillies avec le détecteur ATLAS entre 2015 et 2017. L'amélioration des connaissances sur la modélisation des bruits de fond et un modèle d'ajustement complexe est utilisée avec de nombreux degrés de liberté. Des ajustements particulièrement différents sont présentés afin de comprendre la modélisation du principal bruit de fond irréductible, ttW. En outre, une recherche sur la production de paires de bosons de Higgs dans les états finaux multi leptoniques est présentée. La recherche utilise 139fb^-1 de données issues de collisions proton-proton à une énergie de centre de masse de 13 TeV fournies par le Grand collisionneur de hadrons (LHC) et enregistrées par l'expérience ATLAS entre 2015 et 2018. Les premières études du canal 2 leptons de même signe sont réalisées afin d'optimiser le point de fonctionnement des leptons et d'estimer les contributions des bruits de fond. La méthode d'ajustement du modèle est appliquée pour estimer les bruits de fond réductibles et calculer la limite supérieure préliminaire prévueSince the discovery of the Higgs boson at a mass around 125 GeV by both ATLAS and CMS collaborations in July 2012, it became crucial to measure its properties, such as its couplings to other particles, and search for any deviations from the Standard Model (SM) predictions. The top quark Yukawa coupling is close to unity and the strongest in the fermionic sector. Therefore, this coupling plays a crucial role in the theory. Determination of the associated production of The Higgs boson production with a pair of top quarks (ttH) offers a tree-level access to measuring this coupling. The analysis of ttH production at ATLAS experiment exploits several Higgs decay channel, together with different top quark decay modes. In this thesis, the study of the ttH (H → Multi lepton) process is presented in the topology where the Higgs decays to WW,ZZ or tautau, using a dataset corresponding to an integrated luminosity of 79.8fb^-1 at √s = 13 TeV, collected with the ATLAS detector between 2015-2017. Improved knowledge on the background modelling and the complex fit model is used with many degrees of freedoms. Particularly different fit setups are presented in order to understand the modelling of the major irreducible background, ttW. Furthermore, a search for the SM Higgs boson pair production in the multi lepton final states is presented. The search uses 139fb^-1 of proton-proton collisions data at a centre-of-mass energy of 13 TeV provided by the Large Hadron Collider (LHC) and recorded by the ATLAS experiment in 2015 and 2018. The first studies in two lepton same-sign channel is performed for lepton working point optimisation and estimation of background contributions. Template fit method is applied to estimated the reducible backgrounds and preliminary expected upper limit is calculated
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Yee, Tze-Sung. "A hardware based optical digital code scanning system." Ohio University / OhioLINK, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1182536210.
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Thomas, Laurent. "Search for new heavy narrow resonances decaying into a dielectron pair with the CMS detector." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209221.
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Le sujet de la présente thèse porte sur la recherche de nouvelles particules très massives se désintégrant en une paire électron-positron avec le détecteur CMS.Le démarrage en 2010 du Large Hadron Collider au CERN marque le début d'une nouvelle ère en physique des particules. L'énergie et l'intensité de ses faisceaux de protons, inégalées à ce jour, offre en effet la possibilité d'étudier les lois décrivant les constituants ultimes de la matière et leurs interactions à des énergies jusqu'alors inaccessibles et d'étudier des processus rares.
La découverte récente par les expériences ATLAS et CMS du boson scalaire prédit par la théorie de la brisure de symétrie électro-faible constitue ainsi la première percée du programme de recherche du LHC et confirme la théorie actuelle décrivant la physique subatomique, le Modèle Standard.
Il est cependant largement admis que cette théorie, bien que hautement prédictive et jamais mise en défaut expérimentalement jusqu'à présent, ne constitue qu'une approximation à basse énergie d'une théorie plus fondamentale.
Cette thèse décrit la recherche de nouvelles particules, prédites par plusieurs modèles au delà du Modèle Standard, via leur désintégration en une paire électron-positron de haute énergie.
La reconstruction et la sélection des électrons de haute énergie par le détecteur CMS sont des éléments centraux de cette analyse et sont étudiées en détail. Divers critères sont développés afin de distinguer les électrons des autres types d'objets physiques produits lors de collisions de protons, tels que les jets. L'intensité des faisceaux du LHC est telle que plusieurs collisions ont lieu simultanément dans le détecteur et il est montré que l'efficacité de sélection des électrons dépend fortement du nombre de ces interactions. Une technique est donc mise au point pour corriger cet effet.
Une méthode pour mesurer l'efficacité de la sélection directement sur les données est également développée. Celle-ci permet de confirmer les mesures obtenues à partir de simulations, jusqu'à des impulsions transverses de plusieurs centaines de GeV.
Le spectre de masse des paires diélectron est établi pour les données enregistrées en 2012 à une énergie dans le centre de masse des protons de 8 TeV, et un excès localisé d'événements est recherché. Aucune déviation significative par rapport au bruit de fonds attendu n'est observée et des limites très contraignantes sont établies sur le rapport de la section efficace de production d'une nouvelle résonance diélectronique et de celle mesurée au pic du boson Z. Ces résultats sont utilisés pour fixer des limites inférieures sur la masse de nouvelles particules prédites par certains modèles.
Le redémarrage du LHC en 2015 avec une énergie de 6.5 TeV par faisceau de proton élargira fortement le potentiel de découverte de ces résonances. En cas de découverte d'un signal, ses propriétés (telles que le spin ou l'asymétrie avant-arrière) seront étudiées avec attention. Des projections sur la précision qui pourrait alors être atteinte pour ces mesures sont donc finalement présentées en fonction de la luminosité intégrée collectée.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Sahlin, Kristoffer. "Algorithms and statistical models for scaffolding contig assemblies and detecting structural variants using read pair data." Doctoral thesis, KTH, Beräkningsbiologi, CB, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173580.
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Advances in throughput from Next Generation Sequencing (NGS) methods has provided new ways to study molecular biology. The increased amount of data enables genome wide scale studies of structural variation, transcription, translation and genome composition. Not only is the scale of each experiment large; lowered cost and faster turn-around has also increased the frequency with which new experiments are conducted. With the data growth comes an increase in demand for efficient and robust algorithms — this is a great computational challenge. The design of computationally efficient algorithms are crucial to cope with the amount of data and it is relatively easy to verify an efficient algorithm by runtime and memory consumption. However, as NGS data comes with several artifacts together with the size the difficulty lies in verifying that the algorithm gives accurate results and are robust to different data sets. This thesis focuses on modeling assumptions of mate-pair and paired-end reads when scaffolding contig assemblies or detecting variants. Both genome assembly and structural variation are difficult problems, partly because of a computationally complex nature of the problems, but also due to various noise and artifacts in input data. Constructing methods that addresses all artifacts and parameters in data is difficult, if not impossible, and end-to-end pipelines often come with several simplifications. Instead of tackling these difficult problems all at once, a large part of this thesis concentrates on smaller problems around scaffolding and structural variation detection. By identifying and modeling parts of the problem where simplifications has been made in other algorithms, we obtain an improved solution to the corresponding full problem. The first paper shows an improved model to estimate gap sizes, hence contig placement, in the scaffolding problem. The second paper introduces a new scaffolder to scaffold large complex genomes and the third paper extends the scaffolding method to account for paired-end-contamination in mate-pair libraries. The fourth paper investigates detection of structural variants using fragment length information and corrects a commonly assumed null-hypothesis distribution used to detect structural variants.QC 20150915
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Haj, Ahmad Wael [Verfasser]. "Search for top quark pair resonances with the CMS detector at the LHC / Wael Haj Ahmad." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1037106644/34.
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Tapia, Páez Isabel. "Characterization of human chromosome 22 : cloning of breakpoints of the constitutional translocation t(11;22)(q23;q11) and detection of small constitutional deletions by microarray CGH /." Stockholm, 2003. http://diss.kib.ki.se/2003/91-7349-505-0.
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Rubbo, Francesco. "Measurements of the charge asymmetry in top quark pair production at the LHC with the ATLAS detector." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/284972.
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El quark top, descubierto en 1995 en los experimentos CDF y D0 en el colisionador protón-antiprotón Tevatron en Fermilab (Chicago, USA), es la partícula elemental más pesada conocida, con una masa comparable a la de un átomo de tungsteno. Esta propiedad, no explicada por el Modelo Estándar, confiere al quark top un papel especial en el contexto de modelos teóricos más allá del Modelo Estándar, muchos de los cuales predicen nuevas partículas que se acoplan preferentemente al quark top debido a su alta masa. Después de una década de estudios en el Tevatron (2001-2011), no se han descubierto indicios significativos de nueva física en las propiedades del quark top. La única excepción es la medida de la asimetría adelante-atrás en la producción de parejas top-antitop en colisiones protón-antiprotón en el Tevatron, donde se han encontrado un exceso de aproximadamente dos desviaciones estándar con respecto a la predicción del Modelo Estándar. Esta medida indica que en promedio los quarks top en sucesos top-antitop se producen en la dirección del haz de protones con mayor frecuencia que los quarks antitop. Aunque el Modelo Estándar predice una pequeña asimetría adelante-atrás debido a la interacción fuerte, la presencia de nuevas partículas pesadas contribuyendo a la producción de parejas top-antitop podría dar lugar a un exceso como el observado. Por desgracia, tras el cese de operaciones del Tevatron en Septiembre del 2011, el análisis de todos los datos de los experimentos CDF y D0 no han permitido alcanzar una conclusión definitiva con respecto a esta anomalía.
Esta tesis doctoral está centrada en la medida de precisión de la asimetría de carga en la producción de parejas top-antitop en colisiones protón-protón en el LHC usando las muestras completas de datos acumulados por el detector ATLAS a energías del centro de masas de 7 TeV y 8 TeV, correspondientes a luminosidades integradas de aproximadamente 5 fb-1 y 20 fb-1, respectivamente. La asimetría de carga AC en el LHC, relacionada con la asimetría adelante-atrás en el Tevatron, es sensible a los mismos efectos de nueva física que causarían una desviación en las medidas del Tevatron. En esta tesis doctoral se utiliza el canal semileptónico para hacer medidas inclusivas y diferenciales de la asimetría de carga en sucesos top-antitop. La cinemática de producción de la pareja top-antitop es reconstruida a partir del productos de la desintegración semileptónica y un metodo de unfolding bayesiano es utilizado para estimar AC al nivel partónico. Usando los datos a 7 TeV, se ha alcanzado una precisión 1% en la medida de la asimetría de carga a nivel inclusivo. También se han realizado medidas diferenciales en función de la masa invariante, ángulo de producción con respecto al eje del haz de protones y momento transverso de la pareja top-antitop. Usando los datos a 8 TeV, la precisión obtenida es de 0.5% en la medida de la asimetría de carga a nivel inclusivo, y también se ha realizado la medida diferencial en función de la masa invariante de la pareja top-antitop. La comparación de todas las medidas con las predicciones teóricas indican consistencia con el Modelo Estándar.The top quark, discovered in 1995 at the CDF and D0 experiments at Fermilab’s Tevatron proton-antiproton collider, is the heaviest known elementary particle, with a mass comparable to the atomic mass of tungsten. This property, not explained by the Standard Model (SM), gives a special role to the top quark in the context of theoretical models beyond the Standard Model. Many of the models predict that new particles would preferably couple with the top quark, due to its high mass. After a decade of studies at the Tevatron (2001-2011), no signs of new physics have been discovered in the properties of the top quark, with the exception of the forward-backward asymmetry in top quark pair production, where an excess of about two standard deviations from the SM prediction has been found. This measurement shows that, in average, the top quark in top-antitop events is produced in the proton direction more often than the antitop quark. Even though the SM predicts a small forward-backward asymmetry due to the strong interaction, the presence of new heavy particles contributing to the top-antitop pair production could cause the observed excess. Unfortunately the Tevatron operation terminated on September 2012, and the analysis of the full datasets collected by the CDF and D0 experiments did not provide a final answer with respect to this anomaly. This dissertation describes the precise measurement of the charge asymmetry AC in top-antitop pair production in proton-proton collisions at LHC, using the full dataset collected with the ATLAS detector at center-of-mass energies of 7 TeV and 8 TeV, corresponding to integrated luminosities of about 5 fb-1 and 20 fb-1, respectively. The LHC charge asymmetry, related to the Tevatron forward-backward asymmetry, is a complementary probe of the same new physics effects that could be responsible for the Tevatron excess. The lepton+jets channel is considered to perform inclusive and differential measurements of the charge asymmetry in top quark pair events. The kinematics of the top-antitop pair is reconstructed from the semileptonic decay products, and a Bayesian unfolding procedure is employed to estimate AC at the parton level. Using the dataset at 7 TeV, a 1% precision is achieved for the inclusive measurement. Differential AC measurements as a function of the invariant mass, the rapidity and the transverse momentum of the top-antitop pair are also presented. Using the dataset at 8 TeV, a 0.5% precision is achieved for the inclusive measurement, and the differential AC measurement as a function of the invariant mass of the top-antitop pair is performed as well. All measurements are found to be consistent with the SM predictions.
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Davids, Martina [Verfasser]. "Investigation of spin correlations in top-pair production with the CMS detector at the LHC / Martina Davids." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018218963/34.
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Veron, Maxime Pierre Andre. "Scalable services for massively multiplayer online games." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066212/document.
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Les jeux massivement multi-joueurs en ligne (jeux MMOGs) visent à rassembler un nombre infini de joueurs dans le même univers virtuel. Pourtant, tous les MMOG existants reposent sur des architectures client / serveur centralisé qui imposent une limite sur le nombre maximum de joueurs (avatars) et sur les ressources qui peuvent coexister dans un univers virtuel donné. Cette thèse vise à proposer des solutions pour améliorer l'évolutivité de MMOG. Cette thèse explore deux services qui sont essentiels à toutes les variantes de MMOG: jumelage et détection de triche. Ces deux services sont les goulots d'étranglement connus, et pourtant les implémentations actuelles restent centralisées. Cette thèse montre également qu'il est possible de concevoir un service d'arbitrage au-dessus d'un système de réputation. Le service résultant reste très efficace sur une grande échelle, à la fois en termes de performance et en termes de prévention de la fraude. Comme l'arbitrage est un problème similaire à la détection de fautes, cette thèse étend l'approche proposée pour surveiller les défaillancesMassively Multi-player Online Games (MMOGs) aim at gathering an infinite number of players within the same virtual universe. Yet all existing MMOGs rely on centralized client/server architectures which impose a limit on the maximum number of players (avatars) and resources that can coexist in any given virtual universe. This thesis aims at proposing solutions to improve the scalability of MMOGs. To address the wide variety of their concerns, MMOGs rely on independent services such as virtual world hosting, avatar storage, matchmaking, cheat detection, and game design. This thesis explores two services that are crucial to all MMOG variants: matchmaking and cheat detection. Both services are known bottlenecks, and yet current implementations remain centralized. This thesis also shows that it is possible to design a peer to peer refereeing service on top of a reputation system. The resulting service remains highly efficient on a large scale, both in terms of performance and in terms of cheat prevention. Since refereeing is somewhat similar to failure detection, this thesis extends the proposed approach to monitor failures. The resulting failure detection service scales with the number of monitored nodes and tolerates jitter
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Strandberg, Sara. "Measurements of the Top Quark Pair Production Cross Section and an Estimate of the DØ Silicon Detector Lifetime." Doctoral thesis, Stockholm : Physics Department, Stockholm University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6642.
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Roberts, Rhys. "Evidence for the associated production of the Higgs boson and a top quark pair with the ATLAS detector." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/evidence-for-the-associated-production-of-the-higgs-boson-and-a-top-quark-pair-with-the-atlas-detector(ae9de2a2-b533-41db-9eb7-b25ac77afcdf).html.
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This thesis presents analyses performed with proton-proton collision data collected with the ATLAS detector in 2015 and 2016 at √s=13 TeV. The measurement of so-called non-factorisation effects in the calibration of luminosity is presented. An estimate of the correction, and systematic uncertainty, due to non-factorisation on the calibration is calculated by measuring the proton bunch density profiles from the variation in the luminosity and distribution of reconstructed vertices during beam separation scans. The correction is applied to the calibrations of the total luminosity collected in both 2015 and 2016. A novel multivariate algorithm designed to reject non-prompt leptons (produced from the decays of b- and c-quarks) is presented, utilising information from nearby tracks to discriminate from prompt leptons (produced from W, Z and H boson decays). This algorithm is used to reject non-prompt backgrounds in the search for the associated production of a top quark pair and a Higgs boson (tt̄H) in multilepton final states with 36.1 fb⁻¹ of √s=13 TeV data. Multilepton states refer to the Higgs boson decaying into pairs of W bosons, Z bosons or τ leptons. The combination of the multilepton analysis with the other search analyses of tt̄H production in which the Higgs decays to pairs of photons, b-quarks and ZZ→4ℓ is also shown. The measured value of the signal strength of tt̄H production in data is μ(tt̄H) = 1.2 ± 0.3, corresponding to an observed (expected) discovery significance of 4.2σ (3.8σ) and constituting evidence for the tt̄H production mode.
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Watson, Ian. "Differential top pair production cross-section measurements at √(s) = 7 TeV with the ATLAS detector at the LHC." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/11929.
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The top quark is the most massive fundamental particle of the Standard Model of particle physics, and as the only quark to decay before hadronising gives a unique opportunity for studying QCD, the theory of the strong interaction. In this thesis, we study the \ttbar production cross-section as a function of several variables related to the produced top quarks. This thesis presents variables defined after the hadronisation of the top quark, and so are mostly independent of its theoretical description, unlike previous results which are corrected to the partonic variables. Using the ATLAS detector at the LHC, the measurements are performed for √(s) = 7 TeV proton-proton collisions. The measurements are sensitive to various parameters entering the description of top quark production, including the Parton Distribution Functions, and so have good potential to be used in furthering our understanding of proton collision physics and for future tunings of the models used in describing the physics.
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Cadamuro, Luca. "Search for Higgs boson pair production in the bbtautau decay channel with the CMS detector at the LHC." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX059/document.
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Cette thèse présente une recherche de la production de paires de bosons de Higgs en utilisant les données des collision proton-proton à sqrt(s) = 13 TeV enregistrées avec les détecteur CMS auprès du LHC du CERN. Les évènements avec les deux boson de Higgs se désintégrant en une paire de quark b et de leptons tau (HH -> bb tau+tau-) sont utilisés pour l’exploration des mécanismes de production résonante et non-résonante.La mesure de la production de HH est expérimentalement difficile à cause de la petite section efficace prévue par le modèle standard de la physique des particules. Sa recherche est néanmoins motivée par les informations qu’elle peut révéler sur la nature de la brisure de la symétrie électrofaible. La production de HH donne accès à l’auto-couplage trilineaire du boson de Higgs et, par conséquent, à la forme du potentiel scalaire. En plus, elle est sensible à la présence de physique au-délà du modèle standard. La présence de nouvelles résonances se désintégrant en HH et de couplages anormales du boson de Higgs sont étudiées dans ce travail.Les leptons tau ont un rôle de premier plan dans cette recherche et un effort important a été consacré à l’amélioration de leur efficacité de sélection par le système de déclenchement de l’expérience CMS. En particulier, le déclenchement de premier niveau (L1) a été amélioré pour faire face aux nouvelles conditions des collisions du Run II du LHC, marqué par une augmentation de l’énergie dans le centre de masse et de la luminosité instantanée. Ce nouveau système de déclenchement permet de développer un algorithme spécifique pour la reconstruction des leptons tau se désintégrant en hadrons (tauh) et un neutrino.Cet algorithme se fonde une technique avancée de regroupement dynamique de l’énergie et utilise des critères dédiés pour la réjection du bruit de fond. Le développement, l’implementation, et la vérification de son fonctionnement pour le redémarrage du LHC sont présentés ici. La performance de l’algorithme est initialement évaluée grâce à une simulation et puis mesurée avec les données de l’expérience CMS. Son excellente performance est un element essentiel dans la recherche de la production de HH.L’investigation du processus HH -> bb tau+tau- utilise les trois canaux de désintégration du système tau+tau- avec au moins un tauh dans l’état final. La sélections et categorisation des évènements sont conçues pour optimiser la sensibilité de la recherche, et des techniques d’analyse multivariés sont mises en place pour distinguer le signal du bruit de fond.Les résultats sont présentés en utilisant une luminosité intégrée de 35.9 fb-1. Ils sont compatibles, dans les incertitudes expérimentales, avec les prédictions du modèle standard pour les bruits de fond. Des limites supérieures à la production résonante de HH sont évaluées et interprétées dans le contexte du modèle standard supersymmétrique minimal. Les limites supérieures à la production non-résonante permettent de contraindre l’espace des paramètres des couplages anormales du boson de Higgs. Les limites supérieures observées et attendues correspondent respectivement à environ 30 et 25 fois la prédiction du modèle standard. Ils représentent l’un des résultats les plus sensibles à la production de HH atteint jusqu'à présent au LHC.Les perspectives pour l‘observation de la production de HH au LHC sont enfin discutées. Les résultats précédemment obtenus sont extrapolés à une luminosité intégrée de 3000 fb-1 sous des différentes assomptions pour la performance du détecteur et de l’analyseThis thesis describes a search for Higgs boson pair (HH) production using proton-proton collision data collected at sqrt(s) = 13 TeV with the CMS experiment at the CERN LHC. Events with one Higgs boson decaying into two bottom quarks and the other decaying into two tau leptons (HH -> bb tau+tau-) are explored to investigate both resonant and nonresonant production mechanisms. The measurement of HH production is experimentally challenging because of the tiny cross section predicted by the standard model of particle physics (SM). However, this process can reveal invaluable information on the nature of electroweak symmetry breaking by giving access to the Higgs boson trilinear self-coupling and, consequently, to the shape of the scalar potential itself. Moreover, HH production is sensitive to the presence of physics beyond the SM. Both the presence of new states decaying to HH and of anomalous Higgs boson couplings are investigated in this work.Tau leptons have a key role in this search and considerable effort has been devoted to ensure a high efficiency in their selection by the trigger system of the CMS experiment. In particular, the CMS Level-1 (L1) trigger was upgraded to face the increase in the centre-of-mass energy and instantaneous luminosity conditions expected for the LHC Run II operations. The upgrade opened up the possibility to develop an efficient and dedicated algorithm to reconstruct tau leptons decaying to hadrons (tauh) and a neutrino.The tau algorithm implements a sophisticated dynamic energy clustering technique and dedicated background rejection criteria. Its development, optimisation, implementation, and commissioning for the LHC restart are presented. The algorithm performance is initially demonstrated using a simulation and subsequently measured with the data collected with the CMS experiment. The excellent performance achieved is an essential element of the search for HH production.The investigation of the HH -> bb tau+tau- process explores the three decay modes of the tau+tau- system with at least one tauh object in the final state. A dedicated event selection and categorisation is developed and optimised to enhance the sensitivity, and multivariate techniques are applied for the first time to these final states to separate the signal from the background.Results are derived using an integrated luminosity of 35.9 fb-1. They are found to be consistent, within uncertainties, with the SM background predictions. Upper limits on resonant production are set and interpreted in the context of the minimal supersymmetric standard model. Upper limits on nonresonant production constrain the parameter space for anomalous Higgs boson couplings. The observed and expected upper limit are about 30 and 25 times the SM prediction, respectively, corresponding to one of the most stringent limits set so far at the LHC.Finally, prospects for future measurements of HH production at the LHC are evaluated by extrapolating the current results to an integrated luminosity of 3000 fb-1 under different detector and analysis performance scenarios
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Nechansky, Filip. "Search for the production of a Higgs boson decaying into a pair of bottom quarks in association with a pair of top quarks at 13 TeV with the ATLAS detector." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/23027.
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Die Entdeckung des Higgs-Bosons im Jahr 2012 bestätigt das Standardmodell als die erfolgreichste Theorie, die die grundlegenden Wechselwirkungen von Elementarteilchen beschreibt. Eine der wichtigen Eigenschaften des Higgs-Bosons ist seine Yukawa-Kopplung an das Top-Quark, die aufgrund der hohen Masse des Quarks im Standardmodell am stärksten ist.
Diese Arbeit berichtet über eine Messung der Top-Yukawa-Kopplung mit Daten, die vom ATLAS-Detektor von 2015 bis 2018 bei einem Massenschwerpunkt von 13 TeV aufgezeichnet wurden. Die Kopplung wird in ttH(bb)-Ereignissen untersucht, einem Endzustand, der die Zerfälls-produkte von zwei Top-Quarks enthält und in dem zusätzlich ein Higgs-Boson emittiert wird, welches in Bottom-Quark-Paar zerfällt. Dieser Zerfallskanal des Higgs-Bosons hat das größte Verzweigungsverhältnis, wird jedoch durch die Beschreibung des dominanten Untergrundprozesses ttbb, ein Top-Quark-Paar mit zwei zusätzlichen b-Quarks im Endzustand systematisch beschränkt.
Die Messung nutzt die Fähigkeit des ATLAS-Detektors, Jets von einem b-Quark zu identifizieren, um Analysebereiche mit verschiedenen Zusammensetzungen von Signal und Untergrund zu konstruieren. Um das Signal weiter zu separieren, wird eine Reihe von multivariaten Algorithmen verwendet und der ttH-Prozess wird unter Verwendung eines Profile-Likelihood-Fits extrahiert.
Die Ergebnisse werden für den Kanal mit einem einzelnen Lepton im Endzustand und für eine Kombination mit dem Dilepton-Kanal gezeigt. Die Untergrundgenauigkeit wird im Detail untersucht, wobei große Fehlmodellierungen festgestellt werden. Das gemessene Verhältnis der ttH-Produktion zur Standardmodell-Vorhersage beträgt mu(ttH) = 0,84+0,45- 0,39 (syst.) +-0,21 (stat.). Das Ergebnis stimmt mit der Vorhersage des Standardmodells überein und entspricht einer beobachteten (erwarteten) Signifikanz von 1,9 sigma (2,3 sigma), eine Verbesserung gegenüber der vorherigen ATLAS-Messung, bei der eine Signifikanz von 1,4sigma (1,6 sigma) ermittelt wurden.The discovery of the Higgs Boson in 2012 confirms the Standard Model as the most successful theory describing the fundamental interactions of elemental particles. One of the important properties of the Higgs boson is its Yukawa coupling to the top quark, which in the Standard Model is the strongest due to the high mass of the quark. This thesis reports on a measurement of the top-Yukawa coupling with data collected by the ATLAS detector from 2015 to 2018 at 13 TeV center of mass energy. The coupling is studied in ttH(bb) events, a final state containing decay products of two top quarks with additional emission of a Higgs boson, where the Higgs decays into a pair of bottom quarks. This decay channel of the Higgs Boson has the largest branching ratio, but is systematically limited by the description of the dominant background process ttbb, a tt with additional two b quarks in the final state. The measurement takes advantage of the ability of the ATLAS detector to identify jets coming from a b quarks to construct analysis regions with various compositions of the signal and the background. To further separate the signal, a series of multivariate algorithms is employed and the ttH process is then extracted using a profile likelihood fit. The results are shown for the channel with a single lepton in the final state and for a combination with the dilepton channel. The background performance is studied in detail, where large mis-modeling is found. The measured ratio of the ttH production compared to the Standard Model prediction is found to be mu(ttH) = 0.84 +0.45 -0.39 (syst.) +-0.21 (stat.). The result is in agreement with the Standard Model prediction and corresponds to an observed (expected) significance of 1.9 sigma (2.3 sigma), an improvement compared to the previous ATLAS measurement which reported 1.4 sigma (1.6 sigma).
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Shamim, Mansoora. "Search for pair production of scalar top quarks in jets and missing transverse energy channel with the D0 detector." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/707.
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Apyan, Aram. "Electroweak physics and evidence for a Higgs boson decaying to a pair of tau leptons with the CMS detector." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/112081.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 157-170).
.Studies of the electroweak interactions using final states with leptons in proton-proton collisions at the Large Hadron Collider at [square root of] s = 7 TeV, [square root of] s = 8 TeV, and [square root of] s = 13 TeV center-of-mass energies are described. Measurements of total inclusive and fiducial W and Z boson production cross sections and their ratios are performed. The W and Z bosons are observed via their decays to electrons and muons. An indirect determination of the total width of the W boson and the B(W --> lv) from the measured cross section ratios is described. The discovery of a new boson with a mass of 125 GeV at the Large Hadron Collider in 2012 sheds a new light on understanding the nature of electroweak symmetry breaking. A question of great significance is whether the new field couples to fermions through a Yukawa coupling interaction predicted in the standard model of particles. Evidence of the 125 GeV Higgs boson decay to a pair of tau leptons with an observed significance of 3.1 standard deviations is established. The nature of the Higgs sector is probed through searches for neutral resonances decaying to a pair of tau leptons in gluon-fusion and b-quark associated production modes with no observation of a significant excess. In addition, the feasibility of measuring the standard model Higgs boson self-coupling with an expected data sample corresponding to an integrated luminosity of 3000 fb-1 is studied.
by Aram Apyan.
Ph. D.
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Li, Changqiao. "b-tagging calibration and observation of Higgs boson decays to a pair of bottom quarks with the atlas detector." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS620.
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Cette thèse décrit dans un premier temps la mesure d’efficacité d’identification des jets b grâce à la méthode tag-and-probe utilisant les données enregistrées par le détecteur ATLAS en 2015 et 2016. La méthode de mesure de l’efficacité, la sélection des objets, des événements et des jets sondes, l’évaluation des incertitudes systématiques et statistiques sont présentées. Les efficacités d’identification des jets b ont été mesurées en fonction du moment transverse des jets, de leurs pseudo-rapidités et du nombre moyen de collisions (pile-up). Les efficacités mesurées dans les données ont été comparées aux prédictions des simulations, et ainsi des facteurs d’échelles ont été extraits. Les valeurs obtenues sont proche de un, avec des incertitudes allant de 2% à 12%.Dans un deuxième temps, cette thèse décrit la recherche de la désintégration du boson de Higgs décrit par le modèle standard en une paire quark/anti-quark b dans le canal de production associée avec un boson vecteur. Deux résultats obtenus sont décrits: le premier avec les données collectées par ATLAS avec de collisions protons protons à 13 TeV lors du Run2 du LHC jusqu’en 2016 (36.1 fb-1), puis un second ajoutant les données obtenues dans les mêmes conditions en 2017 (44 fb-1).Le premier résultat est présenté avec une description de la technique de reconstruction des objets, de la sélection des événements et de leur classification, des techniques de discrimination entre le signal et le bruit de fond, de la modélisation des principaux bruits de fond, des propriétés du signal ainsi que de l’interprétation des résultats. Pour le deuxième étude, basée sur les 80 fb-1 données collectées, seules les différences d’avec la première étude sont mises en lumière.Les deux résultats apportent une forte évidence statistique de la production avec des significances respectives de 3.5 et 4.9 déviation standard. L’intensité du signal, définie comme le rapport entre la mesure et la prédiction théorique de la section efficace multipliée par le rapport d’embranchement , obtenue avec les données est , ce qui indique un bon accord entre les données et le modèle standard. La combinaison du résultat basé sur les données à 80 fb-1 obtenues à une énergie dans le centre de masse de 13 TeV avec les données obtenues avec une énergie inférieure (7 et 8 TeV) en 2011 et 2012, ainsi qu’avec les recherches de la désintégration dans les autres canaux de production (fusion de bosons vecteurs, production associée avec une paire de quark top) a permis l’observation de la désintégration avec une significance statistique de 5.4 déviation standard, et une mesure de l’intensité de signal . Une combinaison du résultat basée sur les données à 80 fb-1 obtenues à une énergie dans le centre de masse de 13 TeV avec les recherches dans le même canal de production et avec les mêmes données brutes dans les états finaux en deux photons et ZZ∗ → 4l, a permis l’observation de la production associée du boson de Higgs avec un boson vecteur avec une significance statistique de 5.3 deviation standard, et une mesure de l’intensité de signal , ce qui confirme le bon accord avec la théorie du modèle standardThis thesis firstly describes a measurement of the b-jet tagging efficiency with a tag-and-probe method using data recorded by the ATLAS detector in 2015 and 2016. The efficiency measurement method, the object selection, the event and probe jet selection, the evaluation of the statistical and systematic uncertainties, and the final results are discussed. The b-tagging efficiencies have been measured as a function of the jet transverse momentum, pseudorapidity and of the average number of pile-up collisions. The efficiencies measured in data have been compared to those predicted from simulation, and simulation-to-data efficiency scale factors have been determined. The efficiency scale factors are close to unity, with total uncertainty ranging between 2% and 12%. The second part of this thesis focuses on the search for the decays of the Standard Model (SM) Higgs boson to bottom quarks in the associated production mode with vector bosons. Two measurements have been performed and are described here: the first one is based on of 13 TeV pp collisions recorded by ATLAS during the LHC Run-2 until 2016; the second one includes the additional of 13 TeV pp collisions recorded in 2017. For the study based on of data, the object reconstruction, event selection and classification, the techniques to discriminate the signal from the background, the main background and their modelling, the signal properties and the interpretation of results are discussed. For the study based on data, the main difference from the previous study are highlighted. Both results provide a strong evidence of the process, with statistical significances of 3.5 and 4.9 standard deviations, respectively. The signal strength, defined as the ratio between the measured cross section times branching ratio and the SM prediction, is measured with the 2015–2017 dataset to be , indicating good agreement with the SM. The combination of the results based on of 13 TeV collisions with the results of the same analysis performed on data collected at lower (7 and 8 TeV) centre-of-mass energies in 2011 and 2012, and witht those of the searches of decays in other Higgs boson production modes (vector-boson fusion, associated production with a top-quark pair) have led to the observation of the decay with a significance of 5.4 standard deviations, and to a measurement of the signal strength . A combination of the results of the results based on of 13 TeV collisions with the results of searches for the same production mode on the same amount of data in the diphoton and ZZ∗ → 4l Higgs boson final states has led to the observation of VH production with a significance of 5.3 standard deviations, and to a measurement of the signal strength , in good agreement with the SM
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Ray, Matthew P. "Assembly and modification of a hyperthermal and low energy ion beamline for detecting electron-hole pair production in Schottky diodes." Connect to this title online, 2006. http://etd.lib.clemson.edu/documents/1175186115/.
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Mogg, Philipp [Verfasser], Christian [Akademischer Betreuer] Weiser, and Karl [Akademischer Betreuer] Jakobs. "The search for top-squark pair production with the ATLAS detector at √s = 13 TeV in the fully hadronic final state = The search for top-squark pair production with the ATLAS detector at [square root]s = 13 TeV in the fully hadronic final state." Freiburg : Universität, 2019. http://d-nb.info/1217193669/34.
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Le, Ngoc Khang. "Detecting and Coloring some Graph Classes." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN021/document.
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Les graphes sont des structures mathématiques utilisées pour modéliser les relations par paires entre objets. Malgré leur structure simple, les graphes ont des applications dans divers domaines tels que l'informatique, la physique, la biologie et la sociologie. L'objectif principal de ce travail est de continuer l'étude des problèmes de coloration et de détection dans le cadre de classes de graphes fermées par sous-graphes induits (que nous appelons classes de graphes héréditaires).La première classe que nous considérons est graphes sans ISK4 - les graphes qui ne contiennent aucune subdivision de en tant que sous-graphe induit. Nous montrons que le nombre chromatique de cette classe est limité à 24, une amélioration considérable par rapport à la borne existant précédemment. Nous donnons également une bien meilleure limite dans le cas sans triangle. De plus, nous prouvons qu'il existe un algorithme de complexité pour détecter cette classe, ce qui répond à une question de Chudnovsky et al. et Lévêque et al.La deuxième classe que nous étudions est celle des graphes sans trou pair et sans étoile d’articulation. Cela est motivé par l'utilisation de la technique de décomposition pour résoudre certains problèmes d'optimisation. Nous garantissons la fonction χ-bounding optimale pour cette classe. Nous montrons que la classe a rank-width bornée, ce qui implique l'existence d'un algorithme de coloration en temps polynomial. Enfin, la coloration gloutonne connexe dans les graphes sans griffes est considérée. Une façon naturelle de colorier un graphe est d'avoir un ordre de ses sommets et d'affecter pour chaque sommet la première couleur disponible. Beaucoup de recherches ont été faites pour des ordres généraux. Cependant, nous connaissons très peu de choses sur la caractérisation des bons graphes par rapport aux ordres connexes. Un graphe est bon si pour chaque sous-graphe induit connexe de , chaque ordre connexe donne à une coloration optimale. Nous donnons la caractérisation complète de bons graphes sans griffes en termes de sous-graphes induits minimaux interditsGraphs are mathematical structures used to model pairwise relations between objects. Despite their simple structures, graphs have applications in various areas like computer science, physics, biology and sociology. The main focus of this work is to continue the study of the coloring and detecting problems in the setting of graph classes closed under taking induced subgraphs (which we call hereditary graph classes). The first class we consider is ISK4-free graphs - the graphs that do not contain any subdivision of K4 as an induced subgraph. We prove that the chromatic number of this class is bounded by 24, a huge improvement compared to the best-known bound. We also give a much better bound in the triangle-free case. Furthermore, we prove that there exists an O(n 9) algorithm for detecting this class, which answers a question by Chudnovsky et al. and Lévêque et al. The second class we study is even-hole-free graphs with no star cutset. This was motivated by the use of decomposition technique in solving some optimization problems. We prove the optimal χ -bounding function for this class and show that it has bounded rank-width, which implies the existence of a polynomial-time coloring algorithm.Finally, the connected greedy coloring in claw-free graphs is considered. A natural way to color a graph is to have an order of its vertices and assign for each vertex the first available color. A lot of researches have been done for general orders. However, we know very little about the characterization of good graphs with respect to connected orders. A graph G is good if for every connected induced subgraph H of G, every connected order gives H an optimal coloring. We give the complete characterization of good claw-free graphs in terms of minimal forbidden induced subgraphs
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Nechansky, Filip [Verfasser]. "Search for the production of a Higgs boson decaying into a pair of bottom quarks in association with a pair of top quarks at 13 TeV with the ATLAS detector / Filip Nechansky." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1236896971/34.
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