To predict the T stage of nonrectal colon cancer using contrast-enhanced computed tomography colonography.
Sixty-one patients with 67 nonrectal colon cancers consecutively underwent contrast-enhanced ...computed tomography colonography after an incomplete colonoscopy. Two readers evaluated wall deformity and perilesional fat abnormality on three-dimensional double contrast enema-like views and multiplanar reconstructions. Pathology was used as the standard of reference. McNemar, Fisher, and Cohen κ statistics were used.
At pathologic examination, we found the following stages: T1 (n = 5), T2 (n = 10), T3 (n = 41), T4a (n = 6), and T4b (n = 5). Intraobserver and interobserver reproducibilities were almost perfect for wall deformity (κ = 1.00 and κ = 0.88, respectively), substantial for perilesional fat abnormality (κ = 0.79 and κ = 0.74, respectively). Using the results of the more experienced reader, accuracy of wall deformity ≥50% (apple-core) alone for T ≥ 3 was 62 of 67 (0.93, 95% confidence interval CI 0.83-0.97) and that of perilesional fat abnormality alone was 37 of 67 (0.55, 95% CI 0.43-0.67) (P < .001). Predictive value for ≥ T3 of the association wall deformity ≥50% with perilesional fat abnormality was 22 of 22 (1.00, 95% CI 0.85-1.00), higher, but not significantly, than that of wall deformity ≥50% with normal perilesional fat 29 of 33 (0.88, 95% CI 0.72-0.97) (P = .148, Fisher exact test).
The presence of apple-core wall deformity, regardless of perilesional fat abnormality, is highly predictive of stage T3 or higher.
A new FPGA-based low-level trigger processor has been installed at the NA62 experiment. It is intended to extend the features of its predecessor due to a faster interconnection technology and ...additional logic resources available on the new platform. With the aim of improving trigger selectivity and exploring new architectures for complex trigger computation, a GPU system has been developed and a neural network on FPGA is in progress. They both process data streams from the Ring Imaging Cherenkov detector of the experiment to extract in real time high level features for the trigger logic. Description of the systems, latest developments and design flows are reported in this paper.
We have observed a significant enhancement in the energy deposition by \(25\)--\(100~\mathrm{GeV}\) photons in a \(1~\mathrm{cm}\) thick tungsten crystal oriented along its \(\langle 111 \rangle\) ...lattice axes. At \(100~\mathrm{GeV}\), this enhancement, with respect to the value observed without axial alignment, is more than twofold. This effect, together with the measured huge increase in secondary particle generation is ascribed to the acceleration of the electromagnetic shower development by the strong axial electric field. The experimental results have been critically compared with a newly developed Monte Carlo adapted for use with crystals of multi-\(X_0\) thickness. The results presented in this paper may prove to be of significant interest for the development of high-performance photon absorbers and highly compact electromagnetic calorimeters and beam dumps for use at the energy and intensity frontiers.
The integrated low-level trigger and data acquisition (TDAQ) system of the NA62 experiment at CERN is described. The requirements of a large and fast data reduction in a high-rate environment for a ...medium-scale, distributed ensemble of many different sub-detectors led to the concept of a fully digital integrated system with good scaling capabilities. The NA62 TDAQ system is rather unique in allowing full flexibility on this scale, allowing in principle any information available from the detector to be used for triggering. The design concept, implementation and performances from the first years of running are illustrated.
Precise measurements of the branching ratios for the flavor-changing neutral current decays \(K\to\pi\nu\bar{\nu}\) can provide unique constraints on CKM unitarity and, potentially, evidence for new ...physics. It is important to measure both decay modes, \(K^+\to\pi^+\nu\bar{\nu}\) and \(K_L\to\pi^0\nu\bar{\nu}\), since different new physics models affect the rates for each channel differently. The goal of the NA62 experiment at the CERN SPS is to measure the BR for the charged channel to within 10%. For the neutral channel, the BR has never been measured. We are designing the KLEVER experiment to measure BR(\(K_L\to\pi^0\nu\bar{\nu}\)) to \(\sim\)20% using a high-energy neutral beam at the CERN SPS starting in LHC Run 4. The boost from the high-energy beam facilitates the rejection of background channels such as \(K_L\to\pi^0\pi^0\) by detection of the additional photons in the final state. On the other hand, the layout poses particular challenges for the design of the small-angle vetoes, which must reject photons from \(K_L\) decays escaping through the beam exit amidst an intense background from soft photons and neutrons in the beam. Background from \(\Lambda \to n\pi^0\) decays in the beam must also be kept under control. We present findings from our design studies for the beamline and experiment, with an emphasis on the challenges faced and the potential sensitivity for the measurement of BR(\(K_L\to\pi^0\nu\bar{\nu}\)).
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1995.
Includes bibliographical references (p. 274-283).
by James D. Soldi, Jr.
M.S.
The main goal of the NA62 experiment at CERN is to measure the branching ratio of the ultra-rare K + → π + vv̅ decay with 10% accuracy. NA62 will use a 750 MHz high-energy un-separated charged hadron ...beam, with kaons corresponding to ~ 6% of the beam, and a kaon decay-in-flight technique. The positive identification of kaons is performed with a differential Cherenkov detector (CEDAR), filled with Nitrogen gas and placed in the incoming beam. To stand the kaon rate (45 MHz average) and meet the performances required in NA62, the Cherenkov detector has been upgraded (KTAG) with new photon detectors, readout, mechanics and cooling systems. The KTAG provides a fast identification of kaons with an efficiency of at least 95% and precise time information with a resolution below 100 ps. A half-equipped KTAG detector has been commissioned during a technical run at CERN in 2012, while the fully equipped detector, its readout and front-end have been commissioned during a pilot run at CERN in October 2014. The measured time resolution and efficiency are within the required performances.
Hard X-ray (≥10 keV) observations of active galactic nuclei (AGNs) can shed light on some of the most obscured episodes of accretion onto supermassive black holes. The 70-month Swift/BAT all-sky ...survey, which probes the 14-195 keV energy range, has currently detected 838 AGNs. We report here on the broadband X-ray (0.3-150 keV) characteristics of these AGNs, obtained by combining XMM-Newton, Swift/XRT, ASCA, Chandra, and Suzaku observations in the soft X-ray band ( keV) with 70-month averaged Swift/BAT data. The nonblazar AGNs of our sample are almost equally divided into unobscured ( ) and obscured ( ) AGNs, and their Swift/BAT continuum is systematically steeper than the 0.3-10 keV emission, which suggests that the presence of a high-energy cutoff is almost ubiquitous. We discuss the main X-ray spectral parameters obtained, such as the photon index, the reflection parameter, the energy of the cutoff, neutral and ionized absorbers, and the soft excess for both obscured and unobscured AGNs.
SUMMARY
Dissolution and precipitation processes modify the structure of the porous media at microscale which significantly affects the macroscopic properties of the media. These variations in the ...pore geometry result in changes in the hydraulic properties that control the groundwater flow, and also modify the electrokinetic properties associated to the displacement of electrical charges carried by the flow which originates the streaming potential. Under the hypothesis of a uniform dissolution or precipitation of the pores and based on the effective excess charge density approach, we present a physically based theoretical model for estimating the effective excess charge density as a function of time. The model is based on the assumption that the pore structure can be represented by an ensemble of capillary tubes with a smooth periodic variation of their radius and a fractal pore size distribution. The analytical expressions obtained to describe the effective excess charge density depend on the chemical parameters of the fluid and the petrophysical properties of the medium. In addition, the periodic variations assumed in the pore geometry represent a more realistic description of a porous medium than considering the pores as constant radii capillaries. These irregularities allow us to include the hysteresis phenomenon in the electrokinetic properties. The expressions of the proposed model have been tested with experimental data consisting of sets of effective excess charge density-effective saturation, permeability-effective saturation, porosity-time and permeability-time values. In all cases, the model is able to satisfactorily reproduce the behaviour of the data.
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