1,550 research outputs found

    Squamous cell carcinoma of the ampulla of vater – A case report

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    Introduction: Ampullary carcinoma comprises up to 2% of all gastrointestinal malignancies. Primary squamous cell carcinoma of the ampulla is a very rare neoplasm, with only three reported cases in literature. Due to its rarity, the biological behavior is largely unknown. We highlight such a case, and its diagnostic workup.Case Report: A 61 year old woman presented with painless obstructive jaundice of 2 months duration. MRI scan showed a stricture in the distal common bile duct suggestive of a neoplasm. Biopsy at ERCP showed a poorly differentiated ampullary carcinoma. The specimen received at Whipple’s surgery showed a white tumour surrounding the ampulla, 25 mm in maximum dimension. Histology and immunohistochemistry (CK 7+/20 -, CA 19-9+, CK5/6 focally+) pointed towards a poorly differentiated squamous cell carcinoma. A primary squamous carcinoma elsewhere was excluded. The patient is alive nine months after surgery.Discussion: Ampullary squamous cell carcinoma is most often metastatic from sites such as the larynx, esophagus, lung and uterus. A squamous carcinoma therefore requires ruing out of a primary site elsewhere or a glandular component (adenosquamous carcinoma). These were excluded in this patient. Immunohistochemistry differed from that of primary adenocarcinoma of the ampulla

    Effect of guar gum on the physicochemical, thermal, rheological and textural properties of green edam cheese

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    In attempts to produce a low-fat cheese with a rheology and texture similar to that of a full-fat cheese, guar gum (within 0.0025–0.01%; w/v, final concentration) was added to low-fat milk. The obtained cheeses were characterised regarding their physicochemical, thermal, rheological and textural properties. Control cheeses were also produced with low and full-fat milk. The physicochemical properties of the guar gum modified cheeses were similar to those of the low-fat control. No significant differences were detected in the thermal properties (concerning the enthalpy and profile of water desorption) among all types of cheeses. The rheological behaviour of the 0.0025% modified cheese was very similar to the full-fat control. Overall, no trend was observed in the texture profile (hardness, cohesiveness, gumminess and elasticity) of the modified cheeses versus guar gum concentration, as well as in comparison with the control groups, suggesting that none of the studied polysaccharide concentrations simulated the textural functions of fat in Edam cheese

    Impact of magnetic field on the stability of the CMS GE1/1 GEM detector operation

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    The Gas Electron Multiplier (GEM) detectors of the GE1/1 station of the CMS experiment have been operated in the CMS magnetic field for the first time on the 7th^{th} of October 2021. During the magnetic field ramps, several discharge phenomena were observed, leading to instability in the GEM High Voltage (HV) power system. In order to reproduce the behavior, it was decided to conduct a dedicated test at the CERN North Area with the Goliath magnet, using four GE1/1 spare chambers. The test consisted in studying the characteristics of discharge events that occurred in different detector configurations and external conditions. Multiple magnetic field ramps were performed in sequence: patterns in the evolution of the discharge rates were observed with these data. The goal of this test is the understanding of the experimental conditions inducing discharges and short circuits in a GEM foil. The results of this test lead to the development of procedure for the optimal operation and performance of GEM detectors in the CMS experiment during the magnet ramps. Another important result is the estimation of the probability of short circuit generation, at 68 % confidence level, pshort_{short}HV^{HV} OFF^{OFF} = 0.420.35+0.94^{-0.35+0.94}% with detector HV OFF and pshort_{short}HV^{HV} OFF^{OFF} < 0.49% with the HV ON. These numbers are specific for the detectors used during this test, but they provide a first quantitative indication on the phenomenon, and a point of comparison for future studies adopting the same procedure

    Benchmarking LHC background particle simulation with the CMS triple-GEM detector

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    In 2018, a system of large-size triple-GEM demonstrator chambers was installed in the CMS experiment at CERN\u27s Large Hadron Collider (LHC). The demonstrator\u27s design mimicks that of the final detector, installed for Run-3. A successful Monte Carlo (MC) simulation of the collision-induced background hit rate in this system in proton-proton collisions at 13 TeV is presented. The MC predictions are compared to CMS measurements recorded at an instantaneous luminosity of 1.5 ×1034^{34} cm2^{-2} s1^{-1}. The simulation framework uses a combination of the FLUKA and GEANT4 packages. FLUKA simulates the radiation environment around the GE1/1 chambers. The particle flux by FLUKA covers energy spectra ranging from 1011^{-11} to 104^{4} MeV for neutrons, 103^{-3} to 104^{4} MeV for γ\u27s, 102^{-2} to 104^{4} MeV for e±^{±}, and 101^{-1} to 104^{4} MeV for charged hadrons. GEANT4 provides an estimate of the detector response (sensitivity) based on an accurate description of the detector geometry, the material composition, and the interaction of particles with the detector layers. The detector hit rate, as obtained from the simulation using FLUKA and GEANT4, is estimated as a function of the perpendicular distance from the beam line and agrees with data within the assigned uncertainties in the range 13.7-14.5%. This simulation framework can be used to obtain a reliable estimate of the background rates expected at the High Luminosity LHC

    Modeling the triple-GEM detector response to background particles for the CMS Experiment

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    An estimate of environmental background hit rate on triple-GEM chambers is performed using Monte Carlo (MC) simulation and compared to data taken by test chambers installed in the CMS experiment (GE1/1) during Run-2 at the Large Hadron Collider (LHC). The hit rate is measured using data collected with proton-proton collisions at 13 TeV and a luminosity of 1.5×1034\times10^{34} cm2^{-2} s1^{-1}. The simulation framework uses a combination of the FLUKA and Geant4 packages to obtain the hit rate. FLUKA provides the radiation environment around the GE1/1 chambers, which is comprised of the particle flux with momentum direction and energy spectra ranging from 101110^{-11} to 10410^{4} MeV for neutrons, 10310^{-3} to 10410^{4} MeV for γ\gamma's, 10210^{-2} to 10410^{4} MeV for e±e^{\pm}, and 10110^{-1} to 10410^{4} MeV for charged hadrons. Geant4 provides an estimate of detector response (sensitivity) based on an accurate description of detector geometry, material composition and interaction of particles with the various detector layers. The MC simulated hit rate is estimated as a function of the perpendicular distance from the beam line and agrees with data within the assigned uncertainties of 10-14.5%. This simulation framework can be used to obtain a reliable estimate of background rates expected at the High Luminosity LHC.Comment: 16 pages, 9 figures, 6 table

    Triple-GEM discharge probability studies at CHARM: Simulations and experimental results

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    The CMS muon system in the region with 2.03<|η|<2.82 is characterized by a very harsh radiation environment which can generate hit rates up to 144 kHz/cm2^{2} and an integrated charge of 8 C/cm2^{2} over ten years of operation. In order to increase the detector performance and acceptance for physics events including muons, a new muon station (ME0) has been proposed for installation in that region. The technology proposed is Triple—Gas Electron Multiplier (Triple-GEM), which has already been qualified for the operation in the CMS muon system. However, an additional set of studies focused on the discharge probability is necessary for the ME0 station, because of the large radiation environment mentioned above. A test was carried out in 2017 at the Cern High energy AcceleRator Mixed (CHARM) facility, with the aim of giving an estimation of the discharge probability of Triple-GEM detectors in a very intense radiation field environment, similar to the one of the CMS muon system. A dedicated standalone Geant4 simulation was performed simultaneously, to evaluate the behavior expected in the detector exposed to the CHARM field. The geometry of the detector has been carefully reproduced, as well as the background field present in the facility. This paper presents the results obtained from the Geant4 simulation, in terms of sensitivity of the detector to the CHARM environment, together with the analysis of the energy deposited in the gaps and of the processes developed inside the detector. The discharge probability test performed at CHARM will be presented, with a complete discussion of the results obtained, which turn out to be consistent with measurements performed by other groups

    CAD-based computer vision: the automatic generation of recognition stragtegies

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    Journal ArticleThree-dimensional model-based computer vision uses geometric models of objects and sensed data to recognize objects in a scene. Likewise, Computer Aided Design (CAD) systems are used to interactively generate three-dimensional models during these fields. Recently, the unification of CAD and vision systems has become the focus of research in the context of manufacturing automation. This paper explores the connection between CAD and computer vision. A method for the automatic generation of recognition strategies based on the geometric properties of shape has been devised and implemented. This uses a novel technique developed for quantifying the following properties of features which compose models used in computer vision: robustness, completeness, consistency, cost, and uniqueness. By utilizing this information, the automatic synthesis of a specialized recognition scheme, called a Strategy Tree, is accomplished. Strategy Trees describe, in a systematic and robust manner. the search process used for recognition and localization of particular objects in the given scene. They consist of selected features which satisfy system constraints and Corroborating Evidence Subtrees which are used in the formation of hypotheses. Verification techniques, used to substantiate or refute these hypotheses, are explored. Experiments utilizing 3-D data are presented

    MUSiC: a model-unspecific search for new physics in proton–proton collisions at √s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton–proton collision data recorded at the LHC at a centre-of-mass energy of 13TeV, corresponding to an integrated luminosity of 35.9fb-1, are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches
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