Novel physical phenomena can emerge in low-dimensional nanomaterials. Bulk MoS(2), a prototypical metal dichalcogenide, is an indirect bandgap semiconductor with negligible photoluminescence. When the MoS(2) crystal is thinned to monolayer, however, a strong photoluminescence emerges, indicating an indirect to direct bandgap transition in this d-electron system. This observation shows that quantum confinement in layered d-electron materials like MoS(2) provides new opportunities for engineering the electronic structure of matter at the nanoscale.

To determine whether cmAssist™, an artificial intelligence-based computer-aided detection (AI-CAD) algorithm, can be used to improve radiologists’ sensitivity in breast cancer screening and detection. A blinded retrospective study was performed with a panel of seven radiologists using a cancer-enriched data set from 122 patients that included 90 false-negative mammograms obtained up to 5.8 years prior to diagnosis and 32 BIRADS 1 and 2 patients with a 2-year follow-up of negative diagnosis. The mammograms were performed between February 7, 2008 (earliest) and January 8, 2016 (latest), and were all originally interpreted as negative in conjunction with R2 ImageChecker CAD, version 10.0. In this study, the readers analyzed the 122 studies before and after review of cmAssist™, an AI-CAD software for mammography. The statistical significance of our findings was evaluated using Student’s t test and bootstrap statistical analysis. There was a substantial and significant improvement in radiologist accuracy with use of cmAssist, as demonstrated in the 7.2% increase in the area-under-the-curve (AUC) of the receiver operating characteristic (ROC) curve with two-sided p value < 0.01 for the reader group. All radiologists showed a significant improvement in their cancer detection rate (CDR) with the use of cmAssist (two-sided p value = 0.030, confidence interval = 95%). The readers detected between 25 and 71% (mean 51%) of the early cancers without assistance. With cmAssist, the overall reader CDR was 41 to 76% (mean 62%). The percentage increase in CDR for the reader panel was significant, ranging from 6 to 64% (mean 27%) with the use of cmAssist. There was less than 1% increase in the readers’ false-positive recalls with use of cmAssist. With the use of cmAssist TM, there was a substantial and statistically significant improvement in radiologists’ accuracy and sensitivity for detection of cancers that were originally missed. The percentage increase in CDR for the radiologists in the reader panel ranged from 6 to 64% (mean 27%) with the use of cmAssist, with negligible increase in false-positive recalls. Electronic supplementary material The online version of this article (10.1007/s10278-019-00192-5) contains supplementary material, which is available to authorized users.

Recent experiments with pure electron plasmas in a Malmberg-Penning trap have observed the algebraic damping of m ¼ 1 diocotron modes. Transport due to small field asymmetries produces a low density halo of electrons moving radially outward from the plasma core, and the mode damping begins when the halo reaches the resonant radius r ¼ R w at the wall of the trap. The damping rate is proportional to the flux of halo particles through the resonant layer. The damping is related to, but distinct from, spatial Landau damping, in which a linear wave-particle resonance produces exponential damping. This paper explains with analytic theory the new algebraic damping due to particle transport by both mobility and diffusion. As electrons are swept around the "cat's eye" orbits of the resonant wave-particle interaction, they form a dipole (m ¼ 1) density distribution. From this distribution, the electric field component perpendicular to the core displacement produces E Â B-drift of the core back to the axis, that is, damps the m ¼ 1 mode. The parallel component produces drift in the azimuthal direction, that is, causes a shift in the mode frequency.

Experiments with pure electron plasmas in a Malmberg–Penning trap have observed linear in time, algebraic damping of m = 2 diocotron modes. Transport due to small field asymmetries produces a low-density halo of electrons moving radially outward from the plasma core, and the mode damping begins when the halo reaches the resonant radius of the mode. The damping rate is proportional to the flux of halo particles through the resonant layer. The damping is related to, but distinct from spatial Landau damping in which a linear wave–particle resonance produces exponential damping. This paper reports an analytic theory that captures the main signatures reported for this novel damping, namely, that the damping begins when the halo particles reach the resonant radius and that the damping is algebraic in time with nearly constant damping rate. The model also predicts a nonlinear frequency shift. The model provides two ways to think about the damping. It results from a transfer of canonical angular momentum from the mode to halo particles being swept by the mode field through the nonlinear cat's eye orbits of the resonant region. More mechanistically, the electric field produced by the perturbed charge density of the resonant particles acts back on the plasma core causing E×B drift that gives rise to the damping and nonlinear frequency shift.

This paper provides a simple mechanistic interpretation of the resonant wave-particle interaction of Landau. For the simple case of a Langmuir wave in a Vlasov plasma, the non-resonant electrons satisfy an oscillator equation that is driven resonantly by the bare electric field from the resonant electrons, and in the case of wave damping, this complex driver field is of a phase to reduce the oscillation amplitude. The wave-particle resonant interaction also occurs in waves governed by 2D E × B drift dynamics, such as a diocotron wave. In this case, the bare electric field from the resonant electrons causes E × B drift motion back in the core plasma, reducing the amplitude of the wave. This paper provides a simple mechanistic interpretation of t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f t f the he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he re re re re re re re re re re re re re re re re re re re re re re re re re reso so so so so so so so so so so so so so so so so so so so so so sona na na na na na nant interaction of Landau. For the simple case of a Langm gm gm gm gm gm gm gm gm gm gm gm gmui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui ui uir w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r w r wav av av av av av av av av av av av av av av av av av av av av av av av av av av av av ave in a Vl the non-resonant electrons satisfy an oscillator equat at at at at at at at at at at at at at at at at at at at atio io io io io io io io io io io io io io io io io io io ion t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n tha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha ha hat i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t i t is ds d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d s d sn t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n t n the he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he case of wa this complex driver field is of a phase to red ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed ed educe t e t e t e t e t e t e t e t e t e t e t e t e t e t e the he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he he os os os os os os os os os os os os os os os os os os os os os os os os oscillation amp wave-particle resonant interaction also occu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu cu curs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs rs in in in in in in in in in in in in in in in in in in in in in in in in wa wa wa wa wa wa wa wa wa wa wa wa wa wa wa wa wa wa...