We report a measurement of the single-top-quark production cross section in 2.2 fb;{-1} of pp collision data collected by the Collider Detector at Fermilab at sqrts=1.96 TeV. Candidate events are ...classified as signal-like by three parallel analyses which use likelihood, matrix element, and neural network discriminants. These results are combined in order to improve the sensitivity. We observe a signal consistent with the standard model prediction, but inconsistent with the background-only model by 3.7 standard deviations with a median expected sensitivity of 4.9 standard deviations. We measure a cross section of 2.2(-0.6)(+0.7)(stat+syst) pb, extract the Cabibbo-Kobayashi-Maskawa matrix-element value |V(tb)|=0.88(-0.12)(+0.13)(stat+syst)+/-0.07(theory), and set the limit |V(tb)|>0.66 at the 95% C.L.
A search for new dielectron-mass resonances using data recorded by the CDF II detector and corresponding to an integrated luminosity of 5.7 fb(-1) is presented. No significant excess over the ...expected standard model prediction is observed. In this data set, an event with the highest dielectron mass ever observed (960 GeV/c(2)) was recorded. The results are interpreted in the Randall-Sundrum (RS) model. Combined with the 5.4 fb(-1) diphoton analysis, the RS-graviton lower-mass limit for the coupling k/M¯(Pl)=0.1 is 1058 GeV/c(2), making it the strongest limit to date.
The muon detector of the HERA-B experiment at DESY (Hamburg, Germany) is a gaseous detector that provides muon identification in a high-rate environment. Pairs of muons with an invariant mass in the ...region of the J//spl psi/, meson ensure the first-level trigger for the experiment. Three different types of gas proportional chambers are employed: tube, pad, and pixel. The muon detector is fully installed and has been continuously running since November 1999. A clear signal for J//spl psi//spl rarr//spl mu//spl mu/, is reconstructed from data taken during the commissioning run. Design of the muon system as well as experience gained with detector commissioning are presented in this paper. The severe radiation environment of the HERA-B experiment leads to a maximum charge deposit on a wire, within the muon detector, of 200 mC/cm per year. We report recent results of aging studies performed by irradiating proportional wire chambers filled with Ar/CF/sub 4/,/CK and Ar/CF/sub 4//CO/sub 2/ mixtures under various conditions. These results show that aging rates obtained by irradiating a small region of the wire with a radioactive source cannot be extrapolated to the irradiation of large areas in an environment of hadronic interactions. Our experience shows that the aging rate depends not only on the total collected charge but also on the mode of operation and area of irradiation.
Pancreatic cysts are common and often pose a management dilemma, because some cysts are precancerous, whereas others have little risk of developing into invasive cancers. We used supervised machine ...learning techniques to develop a comprehensive test, CompCyst, to guide the management of patients with pancreatic cysts. The test is based on selected clinical features, imaging characteristics, and cyst fluid genetic and biochemical markers. Using data from 436 patients with pancreatic cysts, we trained CompCyst to classify patients as those who required surgery, those who should be routinely monitored, and those who did not require further surveillance. We then tested CompCyst in an independent cohort of 426 patients, with histopathology used as the gold standard. We found that clinical management informed by the CompCyst test was more accurate than the management dictated by conventional clinical and imaging criteria alone. Application of the CompCyst test would have spared surgery in more than half of the patients who underwent unnecessary resection of their cysts. CompCyst therefore has the potential to reduce the patient morbidity and economic costs associated with current standard-of-care pancreatic cyst management practices.
Background & Aims The management of pancreatic cysts poses challenges to both patients and their physicians. We investigated whether a combination of molecular markers and clinical information could ...improve the classification of pancreatic cysts and management of patients. Methods We performed a multi-center, retrospective study of 130 patients with resected pancreatic cystic neoplasms (12 serous cystadenomas, 10 solid pseudopapillary neoplasms, 12 mucinous cystic neoplasms, and 96 intraductal papillary mucinous neoplasms). Cyst fluid was analyzed to identify subtle mutations in genes known to be mutated in pancreatic cysts ( BRAF , CDKN2A , CTNNB1 , GNAS , KRAS , NRAS , PIK3CA , RNF43 , SMAD4 , TP53 , and VHL ); to identify loss of heterozygozity at CDKN2A , RNF43 , SMAD4 , TP53 , and VHL tumor suppressor loci; and to identify aneuploidy. The analyses were performed using specialized technologies for implementing and interpreting massively parallel sequencing data acquisition. An algorithm was used to select markers that could classify cyst type and grade. The accuracy of the molecular markers was compared with that of clinical markers and a combination of molecular and clinical markers. Results We identified molecular markers and clinical features that classified cyst type with 90%−100% sensitivity and 92%−98% specificity. The molecular marker panel correctly identified 67 of the 74 patients who did not require surgery and could, therefore, reduce the number of unnecessary operations by 91%. Conclusions We identified a panel of molecular markers and clinical features that show promise for the accurate classification of cystic neoplasms of the pancreas and identification of cysts that require surgery.
There are currently few therapeutic options for patients with pancreatic cancer, and new insights into the pathogenesis of this lethal disease are urgently needed. Toward this end, we performed a ...comprehensive genetic analysis of 24 pancreatic cancers. We first determined the sequences of 23,219 transcripts, representing 20,661 protein-coding genes, in these samples. Then, we searched for homozygous deletions and amplifications in the tumor DNA by using microarrays containing probes for ~10⁶ single-nucleotide polymorphisms. We found that pancreatic cancers contain an average of 63 genetic alterations, the majority of which are point mutations. These alterations defined a core set of 12 cellular signaling pathways and processes that were each genetically altered in 67 to 100% of the tumors. Analysis of these tumors' transcriptomes with next-generation sequencing-by-synthesis technologies provided independent evidence for the importance of these pathways and processes. Our data indicate that genetically altered core pathways and regulatory processes only become evident once the coding regions of the genome are analyzed in depth. Dysregulation of these core pathways and processes through mutation can explain the major features of pancreatic tumorigenesis.
The status of the GEM project for CMS high- eta eta muon system Abbaneo, D; Abbrescia, M; Armagnaud, C ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2013, Letnik:
732
Journal Article
Recenzirano
The dedicated CMS R&D program was intended to study the feasibility of using micropattern detectors for the instrumentation of the vacant | eta |>1.6| eta |>1.6 region in the present Resistive Plate ...Chambers (RPCs) endcap system. The proposed detector for CMS is a Triple-Gas Electron Multiplier (GEM) trapezoidal chamber, equipped with 1D readout. While during 2010-2011 the Collaboration worked on the prototyping of the detector, during the first part of 2012 a newly developed assembly technique to be used for the mass production was adopted. GEMs can provide precision tracking and fast trigger information, contributing on one hand to the improvement of the CMS muon Trigger and on the other hand to provide the missing redundancy in the high eta eta region. In the view of the next LHC long shutdown (LS1) the CMS GEM Collaboration designed and built four full-size Triple GEM-based muon detectors.
We report a measurement of the differential cross section dσ/d(cosθ(t)) for top-quark pair production as a function of the top-quark production angle in proton-antiproton collisions at sqrts = 1.96 ...TeV. This measurement is performed using data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.4 fb(-1). We employ the Legendre polynomials to characterize the shape of the differential cross section at the parton level. The observed Legendre coefficients are in good agreement with the prediction of the next-to-leading-order standard-model calculation, with the exception of an excess linear-term coefficient a(1) = 0.40 ± 0.12, compared to the standard-model prediction of a(1)=0.15(-0.03)(+0.07).
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