Search results for "Quantum physic"
showing 10 items of 1596 documents
Theory of domain-wall magnetoresistance in metallic antiferromagnets
2020
We develop a theory to compute the domain-wall magnetoresistance (DWMR) in antiferromagnetic (AFM) metals with different spin structures. In the diffusive transport regime, the DWMR can be either {\it negative} or positive depending on the domain-wall orientation and spin structure. In contrast, when the transport is in the ballistic regime, the DWMR is always positive, and the magnitude depends on the width and orientation of the domain wall. Our results pave the way of using electrical measurements for probing the internal spin structure in antiferromagnetic metals.
Evaluation of prostate segmentation algorithms for MRI: The PROMISE12 challenge
2014
Contains fulltext : 137969.pdf (Publisher’s version ) (Open Access) Prostate MRI image segmentation has been an area of intense research due to the increased use of MRI as a modality for the clinical workup of prostate cancer. Segmentation is useful for various tasks, e.g. to accurately localize prostate boundaries for radiotherapy or to initialize multi-modal registration algorithms. In the past, it has been difficult for research groups to evaluate prostate segmentation algorithms on multi-center, multi-vendor and multi-protocol data. Especially because we are dealing with MR images, image appearance, resolution and the presence of artifacts are affected by differences in scanners and/or …
Effect of observer experience in the differentiation between benign and malignant liver tumors after ultrasound contrast agent injection.
2009
OBJECTIVE: The purpose of this study was to assess the impact of the observer level of experience on the diagnostic performance of contrast-enhanced ultrasound imaging (CEUS) for differentiation between benign and malignant liver tumors. METHODS: From a computerized search, we retrospectively identified 286 biopsy-proven liver tumors (105 hepatocellular carcinomas, 48 metastases, 7 intra-hepatic cholangiocarcinomas, 33 liver hemangiomas, and 93 nonhemangiomatous benign lesions) in 235 patients (140 male and 95 female; mean age +/- SD, 56 +/- 11 years) who underwent CEUS after sulfur hexafluoride-filled microbubble injection. The digital cine clips recorded during the arterial (10-35 seconds…
Is there contextuality in behavioural and social systems?
2015
Most behavioral and social experiments aimed at revealing contextuality are confined to cyclic systems with binary outcomes. In quantum physics, this broad class of systems includes as special cases Klyachko-Can-Binicioglu-Shumovsky-type, Einstein-Podolsky-Rosen-Bell-type, and Suppes-Zanotti-Leggett-Garg-type systems. The theory of contextuality known as Contextuality-by-Default allows one to define and measure contextuality in all such system, even if there are context-dependent errors in measurements, or if something in the contexts directly interacts with the measurements. This makes the theory especially suitable for behavioral and social systems, where direct interactions of "everythin…
Helium and Argon Line Broadening in the nu2 Band of CH4
2004
Abstract The spectra of the gaseous mixtures CH 4 –He and CH 4 –Ar were obtained in the spectral region 1400–1750 cm −1 with a resolution up to 0.003 cm −1 . Helium and argon pressure broadenings for the vibration–rotation lines of the ν 2 band of CH 4 have been estimated at room temperature for some lines in the P , Q , and R branches. These values were also calculated using the theoretical approach developed by Robert and Bonamy, extended to the case of tetrahedral molecules. The helium data have been found to be in a satisfactory agreement whereas a divergence of calculated and measured broadening coefficients has been evidenced in the case of argon. Simulations of the ν 2 band shapes of…
Estimation of line parameters under line mixing effect: the nu3 band of CH4 in helium
2001
International audience; Spectra of CH4-He mixtures were measured in the P and R branch regions of nu3 vibration-rotation band at lower pressures of 0.26-1.0 bar and for the whole band at higher pressures up to 90 bar. The line broadening coefficients were found from lower pressure data for the lines of the P branch. These coefficients were calculated in the framework of the Robert and Bonamy semi-classical approach. In general, they agree with the experimental ones, but a small J-dependent deviation was observed. Line mixing effects were observed at all pressures. At higher pressures they were interpreted in terms of the adjusted branch-coupling model. At lower pressures line mixing effects…
Infrared laser threshold magnetometry with a NV doped diamond intracavity etalon
2019
International audience; We propose a hybrid laser system consisting of a semiconductor external cavity laser associated to an intra-cavity diamond etalon doped with nitrogen-vacancy color centers. We consider laser emission tuned to the infrared absorption line that is enhanced under the magnetic field dependent nitrogen-vacancy electron spin resonance and show that this architecture leads to a compact solid-state magnetometer that can be operated at room-temperature. The sensitivity to the magnetic field limited by the photon shot-noise of the output laser beam is estimated to be less than 1 pT/ √ Hz. Unlike usual NV center infrared magnetometry, this method would not require an external f…
Essential features of optical processes in neon-buffered submicron-thin Rb vapor cell
2010
A new submicron thin cell (STC) filled with Rb and neon gas is developed and comparison of resonant absorption with STC containing pure Rb is provided. The effect of collapse and revival of Dicke-type narrowing is still observable for the thickness L = lambda /2 and L = lambda , where lambda is a resonant laser wavelength 794 nm (D(1) line). For an ordinary Rb cm-size cell with addition of buffer gas, the velocity selective optical pumping/saturation (VSOP) resonances in saturated absorption spectra are fully suppressed if neon pressure0.5 Torr. A spectacular difference is that for L = lambda , VSOP resonances are still observable even when neon pressure isor = 6 Torr. Narrow fluorescence s…
Micro lensing induced lineshapes in a single mode cold-atom hollow-core fiber interface
2018
We report on the observation of strong transmission line shape alterations in a cold-atom-hollow-core-fiber interface. We show that this can lead to a significant overestimation of the assigned resonant optical depth for high atom densities. By modeling light beam propagation in an inhomogeneous dispersive medium, we attribute the observations to micro lensing in the atomic ensemble in combination with the mode selection of the atom-fiber interface. The approach is confirmed by studies of Rydberg electromagnetically induced transparency line shapes.
A single-atom heat engine
2015
Making a teeny tiny engine Steam locomotives, cars, and the drinking bird toy all convert heat into useful work as it cycles between two reservoirs at different temperatures. Usually, the working substance where the heat-work conversion occurs is a liquid or a gas, consisting of many molecules. Roβnagel et al. have made a working substance of a single calcium ion in a tapered ion trap. A laser-cooling beam plays the part of a cold reservoir for the calcium ion, and in turn, electric field noise acts as a hot reservoir. Science , this issue p. 325