1,572 research outputs found
Search For New Physics With Taus at the LHC
No full textThis report reviews the ways in which taus can be used for discovering new physics at the LHC. Emphasis is given to the techniques currently proposed to include the tau in an efficient trigger scheme
Supplemental material for An omnibus test for the global null hypothesis
No full textSupplemental material for An omnibus test for the global null hypothesis by Andreas Futschik, Thomas Taus and Sonja Zehetmayer: R Core Team in Statistical Methods in Medical Research</p
Identification des leptons taus dans l'expérience DØ auprès du tevatron et recherche de particules supersymétriques se désintégrant avec R-parité violée (couplage 133)
No full textCette thèse a pour sujet la recherche de particules supersymétriques dans l expérience D0 Run II auprès de l accélérateur du Tevatron où se produisent des collisions protons-antiprotons à une énergie s=1.96 TeV dans le centre de masse. L analyse a porté sur un échantillon de données correspondant à une luminosité intégrée de 352 pb-1 (2001-2004). Le modèle supersymétrique retenu est celui où la R-parité est non-conservée par couplage 133. L état final peut être caractérisé par la présence de deux électrons, d énergie transverse manquante et d au moins un tau se désintégrant de façon hadronique. Aucun excès d événéments avec une telle signature n ayant été identifié, de nouvelles limites inférieures sur les masses du neutralino et du chargino les plus légers ont été obtenues. Afin de pouvoir mener cette analyse à bien nous avons au préalable développé une méthode d identification des leptons taus dans leurs modes hadroniques. Cette méthode s appuie sur des réseaux de neurones et utilise les informations du calorimètre et du trajectographe ayant trait à l isolation et aux dépôts énergétiques longitudinaux et transverses des taus. L efficacité et la validité de cette méthode ont été estimées dans les données à l aide du processus Z-> -> hadr. Cette méthode d identification permet de rejeter l important bruit de fond des jets QCD d un facteur 100 pour environ 50% d efficacité de reconnaissance des taus hadroniques.This thesis concerns the search for supersymmetric particles in data collected by the D0 experiment in Run II at Fermilab Tevatron proton-antiproton collider. Data corresponding to an integrated luminosity of 352 pb-1 (2001-2004) at a center-of-mass energy of s=1.96 TeV have been used to search for two electrons plus hadronic taus final states accompanied by missing transverse energy. These topologies are expected to arise if R-parity is violated and the lightest neutralino is allowed to decay through a 133 coupling. The data seen is consistent with Standard Model and instrumental background expectations which suggests no evidence for supersymmetry with 133 coupling. Thus lower limits on the masses of the lightest chargino and neutralino have been set. A significant part of the work has been dedicated to identify hadronically decaying taus. The developed method uses neural networks and exploits the narrowness and low particle multiplicty of tau jets by means of the calorimeter and tracker informations. The efficiency and capability of this method have been measured and demonstrated in data using the Z-> -> hadr process. This algorithm allows one to reduce the important QCD background by a factor 100 for 50% tau identification efficiency.STRASBOURG-Sc. et Techniques (674822102) / SudocCLUNY-Arts et Métiers (711372301) / SudocSudocFranceF
Identification des leptons taus dans l'expérience DØ auprès du tevatron et recherche de particules supersymétriques se désintégrant avec R-parité violée (couplage λ133)
No full textCette thèse a pour sujet la recherche de particules supersymétriques dans l’expérience D0 Run II auprès de l’accélérateur du Tevatron où se produisent des collisions protons-antiprotons à une énergie √s=1.96 TeV dans le centre de masse. L’analyse a porté sur un échantillon de données correspondant à une luminosité intégrée de 352 pb-1 (2001-2004). Le modèle supersymétrique retenu est celui où la R-parité est non-conservée par couplage λ133. L’état final peut être caractérisé par la présence de deux électrons, d’énergie transverse manquante et d’au moins un tau se désintégrant de façon hadronique. Aucun excès d’événéments avec une telle signature n’ayant été identifié, de nouvelles limites inférieures sur les masses du neutralino et du chargino les plus légers ont été obtenues. Afin de pouvoir mener cette analyse à bien nous avons au préalable développé une méthode d’identification des leptons taus dans leurs modes hadroniques. Cette méthode s’appuie sur des réseaux de neurones et utilise les informations du calorimètre et du trajectographe ayant trait à l’isolation et aux dépôts énergétiques longitudinaux et transverses des taus. L’efficacité et la validité de cette méthode ont été estimées dans les données à l’aide du processus Z→ττ→μτhadr. Cette méthode d’identification permet de rejeter l’important bruit de fond des jets QCD d’un facteur 100 pour environ 50% d’efficacité de reconnaissance des taus hadroniques.
This thesis concerns the search for supersymmetric particles in data collected by the D0 experiment in Run II at Fermilab Tevatron proton-antiproton collider. Data corresponding to an integrated luminosity of 352 pb-1 (2001-2004) at a center-of-mass energy of √s=1.96 TeV have been used to search for two electrons plus hadronic taus final states accompanied by missing transverse energy. These topologies are expected to arise if R-parity is violated and the lightest neutralino is allowed to decay through a λ133 coupling. The data seen is consistent with Standard Model and instrumental background expectations which suggests no evidence for supersymmetry with λ133 coupling. Thus lower limits on the masses of the lightest chargino and neutralino have been set.
A significant part of the work has been dedicated to identify hadronically decaying taus. The developed method uses neural networks and exploits the narrowness and low particle multiplicty of tau jets by means of the calorimeter and tracker informations. The efficiency and capability of this method have been measured and demonstrated in data using the Z→ττ→μτhadr process. This algorithm allows one to reduce the important QCD background by a factor 100 for 50% tau identification efficiency
Correlation between neutrino oscillations and collider signals of supersymmetry in an R-parity violating model
No full textMotivated by the recent Super-Kamiokande results on atmospheric neutrinos, we incorporate massive neutrinos, with large angle oscillation between the second and third generations, in a scenario with R-parity violating supersymmetry. We emphasize the testability of such models through the observation of comparable numbers of muons and taus, produced together with the W-boson, in decays of the lightest neutralino. A distinctly measurable decay gap is another remarkable feature of such a scenario. (orig.)21 refs.Available from TIB Hannover: RA 2999(98-134) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Automatic Prostate Volume estimation on Transabdominal Ultrasound using Deep Neural Networks
No full textProstate cancer is the most commonly diagnosed cancer in the Netherlands. Accurate assessment of the prostate volume (PV) is a crucial step in prostate cancer (PCa) screening and risk-stratification. In standard clinical care, the PV is obtained by measuring the prostate dimensions with the aid of transrectal ultrasound (TRUS). However, rectal examination is characterised with patient discomfort, for which the feasibility of transabdominal ultrasound (TAUS) is explored, as a more accessible and patient-friendly alternative. However, manual PV measurements are prone to inter-observer variability and require operator training. This study aims to improve the accessibility, complexity, and robustness of PV measurements by developing a framework to automatically estimate the PV based on TAUS acquisitions. The primary components of the framework comprise two deep neural networks, developed for prostate segmentation on axial and sagittal TAUS images, and an algorithm that extracts the prostate's diameters on which the PV is calculated.During this study, a new prostate dataset is developed, comprising sagittal and transverse TAUS image acquisitions of 100 participants, and reference PV measurements based on TRUS and MRI are collected. First, the feasibility of TAUS for manual PV estimation is explored, and the inter-method agreement between TAUS, TRUS and MRI is analysed in Bland Altman diagrams. Additionally, all TAUS acquisitions are assessed on image quality. Secondly, three deep neural networks (using the nnU-Net framework) are developed to segment the prostate on sagittal and/or axial TAUS images. All models, are trained and validated on TAUS image data of 52 participants. Additionally, an algorithm is designed to predict the prostate diameters when prostate segmentations serve as input. To this extend, the PV is estimated according to the widely used Ellipsoid formula. The proposed algorithm is evaluated on input ground-truth segmentations of 42 participants. Essentially, the segmentation models combined with the proposed algorithm result in a framework to automatically estimate the PV on TAUS. Finally, it is tested on unseen TAUS acquisitions of 17 participants, whereby the predicted PV is compared to reference PV measurements on MRI. Our results show an average volume difference of 3.0 ± 17.6 ml when manual PV estimation on TAUS is compared to MRI. When manual PV estimation on TRUS is compared to MRI, an average volume difference of 12.3 ± 18.8 ml is obtained. The developed segmentations models segment the middle region of the prostate on TAUS with an average DSC = 0.91 ± 0.06 and DSC = 0.83 ± 0.09 for axial and sagittal TAUS images respectively. When the entire prostate region was evaluated, a lower model performance was observed, whereby the prostate was segmented with a DSC of 0.76 ± 0.09 in the axial imaging-plane and DSC of 0.68 ± 0.21 in the sagittal imaging-plane. The algorithm for automatic diameter extraction showed good correspondence with manually assigned prostate diameters on TAUS. When the segmentation models and the algorithm are utilised for automatic PV estimation, an average volume difference of 2.5 ± 10.2 ml was observed, compared to MRI reference volumes. Ultimately the PV was predicted with a volume difference < 25 compared to MRI in 14 out of 17 test cases. The results of this study show that it is possible to obtain PV measurements using TAUS that are comparable to those obtained with MRI. Moreover, the variability related to PV measurements using TAUS seem unrelated to TAUS image quality, indicating that manual PV measurements can be performed, even when unfavorable patient characteristics limit the image quality. Still, it is important to note that proper operator training for TAUS examination is essential. The proposed framework for automatic PV estimation on TAUS acquisitions shows good correspondence with MRI reference volumes. Thus expanding the possibilities of PCa risk-stratification, whereby robust, and straightforward PV estimations are desired. In order to adopt the framework for standard clinical care, further research is required on a larger cohort to investigate the generalizability of the framework and ensure reliable results on all future patients.TM30004; 35 ECTSTechnical Medicine | Imaging and Interventio
Circadian melatonin and temperature taus in delayed sleep-wake phase disorder and non-24-hour sleep-wake rhythm disorder patients: An ultradian constant routine study
No full textFerguson, SA ORCiD: 0000-0002-9682-7971Our objectives were to investigate the period lengths (i.e., taus) of the endogenous core body temperature rhythm and melatonin rhythm in delayed sleep-wake phase disorder patients (DSWPD) and non-24-h sleep-wake rhythm disorder patients (N24SWD) compared with normally entrained individuals. Circadian rhythms were measured during an 80-h ultradian modified constant routine consisting of 80 ultrashort 1-h "days" in which participants had 20-min sleep opportunities alternating with 40 min of enforced wakefulness. We recruited a community-based sample of 26 DSWPD patients who met diagnostic criteria (17 males, 9 females; age, 21.85 ± 4.97 years) and 18 healthy controls (10 males, 8 females; age, 23.72 ± 5.10 years). Additionally, 4 full-sighted patients (3 males, 1 female; age, 25.75 ± 4.99 years) were diagnosed with N24SWD and included as a discrete study group. Ingestible core temperature capsules were used to record minute temperatures that were averaged to obtain 80 hourly data points. Salivary melatonin concentration was assessed every half-hour to determine time of dim light melatonin onset at the beginning and end of the 80-h protocol. DSWPD patients had significantly longer melatonin rhythm taus (24 h 34 min ± 17 min) than controls (24 h 22 min ± 15 min, p = 0.03, d = 0.70). These results were further supported by longer temperature rhythm taus in DSWPD patients (24 h 34 min ± 26 min) relative to controls (24 h 13 min ± 15 min, p = 0.01, d = 0.80). N24SWD patients had even longer melatonin (25 h ± 19 min) and temperature (24 h 52 min ± 17 min) taus than both DSWPD (p = 0.007, p = 0.06) and control participants (p < 0.001, p = 0.02, respectively). Between 12% and 19% of the variance in DSWPD patients' sleep timing could be explained by longer taus. This indicates that longer taus of circadian rhythms may contribute to the DSWPD patients' persistent tendency to delay, their frequent failure to respond to treatment, and their relapse following treatment. Additionally, other factors can contribute to misalignments in DSWPD and N24SWD disorders. © 2016 The Author(s).Associated Grant:Australian Research Council Discovery ProjectAssociated Grant Code:DP12010140
Search for spontaneous R-parity violation at s**(1/2) = 183-GeV and 189-GeV
No full textSearches for spontaneous R-parity-violating signals at roots = 183 GeV and roots = 189 GeV have been performed using the 1997 and 1998 DELPHI data, under the assumption of R-parity breaking in the third lepton family. The expected topology for the decay of a pair of charginos into two acoplanar taus plus missing energy was investigated and no evidence for a signal was found. The results were used to derive a limit on the chargino mass and to constrain the allowed domains of the MSSM parameter space
Modifications of functional and physico-chemical properties of rat ileal plasma membranes.
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