A correct statistical model of soil pore structure can be critical for understanding flow and transport processes in soils, and creating synthetic soil pore spaces for hypothetical and model testing, ...and evaluating similarity of pore spaces of different soils. Advanced visualization techniques such as X-ray computed tomography (CT) offer new opportunities of exploring heterogeneity of soil properties at horizon or aggregate scales. Simple fractal models such as fractional Brownian motion that have been proposed to capture the complex behavior of soil spatial variation at field scale rarely simulate irregularity patterns displayed by spatial series of soil properties. The objective of this work was to use CT data to test the hypothesis that soil pore structure at the horizon scale may be represented by multifractal models. X-ray CT scans of twelve, water-saturated, 20-cm long soil columns with diameters of 7.5
cm were analyzed. A reconstruction algorithm was applied to convert the X-ray CT data into a stack of 1480 grayscale digital images with a voxel resolution of 110
microns and a cross-sectional size of 690
×
690
pixels. The images were binarized and the spatial series of the percentage of void space vs. depth was analyzed to evaluate the applicability of the multifractal model. The series of depth-dependent macroporosity values exhibited a well-defined multifractal structure that was revealed by singularity and Rényi spectra. The long-range dependencies in these series were parameterized by the Hurst exponent. Values of the Hurst exponent close to one were observed indicating the strong persistence in variations of porosity with depth. The multifractal modeling of soil macropore structure can be an efficient method for parameterizing and simulating the vertical spatial heterogeneity of soil pore space.
To investigate the performance of low-dose, dual-source computed tomography (DSCT) coronary angiography in the step-and-shoot (SAS) mode for the diagnosis of significant coronary artery stenoses in ...comparison with conventional coronary angiography (CCA).
Prospective, single-centre study conducted in a referral centre enrolling 120 patients (71 men, mean (SD) age 68 (9) years, mean (SD) body mass index 26.2 (3.2) kg/m2). All study participants underwent DSCT in the SAS mode and CCA within 14 days. Twenty-seven patients were given intravenous beta blockers for heart rate reduction before CT. Patients were excluded if a target heart rate <or=70 bpm could not be achieved by beta blockers or when the patients were in non-sinus rhythm. Two blinded readers independently evaluated coronary artery segments for assessability and for the presence of significant (>50%) stenoses. Sensitivity, specificity, negative (NPV) and positive predictive values (PPV) were determined, with CCA being the standard of reference. Radiation dose values were calculated.
DSCT coronary angiography in the SAS mode was successfully performed in all 120 patients. Mean (SD) heart rate during scanning was 59 (6) bpm (range 44-69). 1773/1803 coronary segments (98%) were depicted with a diagnostic image quality in 109/120 patients (91%). The overall patient-based sensitivity, specificity, PPV and NPV for the diagnosis of significant stenoses were 100%, 93%, 94% and 100%, respectively. The mean (SD) effective dose of the CT protocol was 2.5 (0.8) mSv (range 1.2-4.4).
DSCT coronary angiography in the SAS mode allows, in selected patients with a regular heart rate, the accurate diagnosis of significant coronary stenoses at a low radiation dose.
We describe the new ENDF/B-VIII.0 evaluated nuclear reaction data library. ENDF/B-VIII.0 fully incorporates the new IAEA standards, includes improved thermal neutron scattering data and uses new ...evaluated data from the CIELO project for neutron reactions on 1H, 16O, 56Fe, 235U, 238U and 239Pu described in companion papers in the present issue of Nuclear Data Sheets. The evaluations benefit from recent experimental data obtained in the U.S. and Europe, and improvements in theory and simulation. Notable advances include updated evaluated data for light nuclei, structural materials, actinides, fission energy release, prompt fission neutron and γ-ray spectra, thermal neutron scattering data, and charged-particle reactions. Integral validation testing is shown for a wide range of criticality, reaction rate, and neutron transmission benchmarks. In general, integral validation performance of the library is improved relative to the previous ENDF/B-VII.1 library.
We present a multi-sensor chip comprising an array of whispering-gallery mode (WGM) micro-goblet lasers integrated into a digital microfluidic (DMF) system. In contrast to earlier demonstrations, the ...lasers are fabricated from dye-doped poly-methyl methacrylate (PMMA) at low cost using spin-coating, mask-based optical lithography, wet chemical etching, and thermal reflow techniques. Pumping and read-out of the devices is accomplished via simple free-space optics, thereby allowing large-scale sensor arrays to be addressed. We demonstrate the viability of the system by bulk refractive index-sensing and by measuring the specific binding of streptavidin to a biotinylated sensor surface. This is the first time that optical cavities are used for label-free detection of biomolecules in a DMF system. This approach can be extended to a versatile detector platform that targets a wide range of clinically relevant biomolecules.
The NA61/SHINE experiment at the CERN SPS is undergoing a major upgrade during the CERN Long Shutdown 2 period (2019-2021). The upgrade is essential to fulfill the requirements of the new open charm ...and neutrino programs. In these programs the NA61/SHINE will operate with the data acquisition rate increased by a factor of 10, which requires an upgrade of current Beam Position Detectors (BPDs). New detectors should monitor beam particle positions with a frequency up to 10
5
Hz.
This paper presents an overview of the new BPD design, as well as discusses current state of development and prototype production of BPD, including: mechanical design, front-end electronics design and integration with experiment’s data aquisition system.
We present a new measurement of $J/\psi$ production in Pb-Pb collisions at 158 GeV/nucleon, from the data sample collected in year 2000 by the NA50 Collaboration, under improved experimental ...conditions with respect to previous years. With the target system placed in vacuum, the setup was better adapted to study, in particular, the most peripheral nuclear collisions with unprecedented accuracy. The analysis of this data sample shows that the ($J/\psi$)/Drell-Yan cross-sections ratio measured in the most peripheral Pb-Pb interactions is in good agreement with the nuclear absorption pattern extrapolated from the studies of proton-nucleus collisions. Furthermore, this new measurement confirms our previous observation that the ($J/\psi$)/Drell-Yan cross-sections ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb collisions and that this ratio persistently decreases up to the most central collisions.
—
A new compact time-of-flight neutron detector is being planned for the identification and energy measurement of neutrons produced in nucleus-nucleus interactions at energies up to 4 AGeV at the ...BM@N experiment, located at the Nuclotron (Joint Institute for Nuclear Research, Dubna, Russia). This detector will be used to measure neutron yields and azimuthal flows, which should be sensitive to the equation of state of dense nuclear matter, as shown in various theoretical models It is proposed to use plastic scintillators produced at JINR and IFTP and silicon photomultipliers with a sensitive area of 6 × 6 mm
2
for photon registration, one for each scintillation cell. To achieve the required neutron energy resolution (of the order of several percent) in the energy range up to 4 GeV, the time resolution of scintillation detectors should be 100−150 ps. The concept of a time-of-flight neutron detector is discussed. The results of measurements of the light yield and time resolution of several scintillation detector specimens of various sizes and two types of silicon photomultipliers are presented.
Forward Hadron Calorimeter is a part of MPD experiment setup at NICA beam facility. FHCal structure and purpose are presented in this proceedings. Methods of collision centrality and event plane ...reconstruction are discussed. Simulation, beam test results and production status are presented.
We report a new measurement of J/ψ, ψ′ and Drell–Yan cross-sections, in the kinematical domain -0.425<ycm<0.575 and -0.5<cosθCS<0.5, performed at the CERN-SPS using 400 GeV/c incident protons on Be, ...Al, Cu, Ag, W and Pb targets. The dependence of the charmonia production cross-sections on the size of the target nucleus allows to quantify the so-called normal nuclear absorption. In the framework of the Glauber model, this new measurement is combined with results previously obtained with the same apparatus, under different experimental conditions, and leads to a precise determination of the J/ψ and ψ′ absorption cross-sections in the surrounding nuclear matter.
The BM@N (Baryonic Matter at Nuclotron) is the fixed target experiment at NICA-Nuclotron (JINR, Dubna, Russia) accelerator complex. The main goal of the experiment is studying the properties of dense ...nuclear matter produced in ion-ion collisions at the energies of up to 4 AGeV. New Forward Hadron Calorimeter (FHCal) with modular structure and a beam hole in the center has been developed and constructed to measure the collision centrality after the BM@N upgrade. The transverse and longitudinal segmentation of the FHCal allows to perform calibration of the calorimeter with cosmic muons.
FHCal modules have lead/scintillator sampling structure with longitudinal segmentation. Light signals from the sections are collected with MPPCs, amplified and read-out by ADC boards. Fast analog signals are collected for trigger system.
The status of development and construction of the new FHCal calorimeter for the BM@N experiment is presented. Performance of FHCal front-end and readout systems is discussed.
PDF
