Notizie da 5 fonti
Quantum mechanics permits particles to follow bizarre, looping and curving trajectories, usually with very low probability. But a calculation shows that in some cases, these paths can have significant and possibly measurable effects. Published Fri Sep 19, 2014
A particle detector onboard the International Space Station has revealed differences between the spectrum of cosmic-ray positrons and electrons, which might be a hint of dark matter annihilation processes. Published Thu Sep 18, 2014
The experimental observation of spin-orbital exchange interactions in ultracold atoms opens a window for the exploration of poorly understood magnetic behaviors. Published Mon Sep 15, 2014
Experiments show that beams of left- or right-handed electrons are not equal-opportunity destroyers of molecules having two mirror-image forms, which supports the idea that primordial cosmic rays generated the asymmetry in biological molecules. Published Fri Sep 12, 2014
The magnetic phase transition and magnetocaloric effect are studied in a series of Mn 1− x Zn x CoGe ( x = 0.01, 0.02, 0.04, and 0.08) alloys. By introducing a small quantity of Zn element, the structural transformation temperature of the MnCoGe alloy is greatly reduced and a first-order magnetostructural transition is observed. Further increasing the Zn concentration results in a second-order ferromagnetic transition. Large room-temperature magnetocaloric effects with small magnetic hysteresis are obtained in alloys with x = 0.01 and 0.02, which suggests their potential application in magnetic refrigeration.
Using the trial equation method, a Broer—Kau—Kupershmidt (BKK) mechanism physical model is obtained, and the exact and approximate solitary traveling wave solutions are found. As an example, it is pointed out that the solitary traveling wave approximate solutions have better accurate degree by using the homotopic mapping theory.
The second-order and fourth-order statistical moments of the speckle field from a diffuse target in atmospheric turbulence are studied which have great influence on the performance of lidar systems. By expanding a general rotationally symmetric beam as a sum of Gaussian—Schell model (GSM) beams, the mean intensity of the general beam propagating over a distance in an atmospheric turbulence is formulated. Expressions for the degree of coherence (DOC) and the normalized intensity variance of the scattered field of a general beam from a rough surface in turbulence are derived based on the extended Huygens—Fresnel principle. The general expressions reduce to the well-known forms for a GSM beam. Another example for the general beam used in this paper is the collimated flat-topped beam. The results of both kinds of beams show that the intensity profile on the target plane is a key factor affecting the statistical characteristics of the speckle field. A larger beam spot on the target p...
We point out an error in Eq. (19) in our original paper [ Chin. Phys. B 23 040402 (2014)] and present the correct equation.