On the Use of Video Clips in College English Teaching

The use of video clips in college English teaching is of great significance and necessity and it has its own utilizing principle, yet not every college English teacher knows it, nor can they use them well. Combining the experience of my utilizing it and the students’ feedback., this paper studies its advantages and using principles. Key Words: the use of video clips, college English teaching, utilizing principle Résumé: L’utilisation du vidéoclip dans l’enseignement de l’anglais à l’université est d’une grande signification et nécessité. D’ailleurs, elle a son propre principe d’utilisation. Mais tous les enseignants d’anglais ne le savent pas, ni l’emploient bien. En combinant ma propre expérience et le feedbaclk des étudiants, l’auteur étudie les avantages de l’utilisation du vidéoclip et son principes d’emploi. Mots-Clés: utilisation du vidéoclip, enseignement de l’anglai

Multi-particle and High-dimension Controlled Order Rearrangement Encryption Protocols

Based on the controlled order rearrange encryption (CORE) for quantum key distribution using EPR pairs[Fu.G.Deng and G.L.Long Phys.Rev.A68 (2003) 042315], we propose the generalized controlled order rearrangement encryption (GCORE) protocols of $N$ qubits and $N$ qutrits, concretely display them in the cases using 3-qubit, 2-qutrit maximally entangled basis states. We further indicate that our protocols will become safer with the increase of number of particles and dimensions. Moreover, we carry out the security analysis using quantum covariant cloning machine for the protocol using qutrits. Although the applications of the generalized scheme need to be further studied, the GCORE has many distinct features such as great capacity and high efficiency

Mid-infrared flare of TDE candidate PS16dtm: dust echo and implications for the spectral evolution

PS16dtm was classified as a candidate tidal disruption event (TDE) in a dwarf Seyfert 1 galaxy with low-mass black hole ($\sim10^6M\odot$) and has presented various intriguing photometric and spectra characteristics. Using the archival WISE and the newly released NEOWISE data, we found PS16dtm is experiencing a mid-infrared (MIR) flare which started $\sim11$ days before the first optical detection. Interpreting the MIR flare as a dust echo requires close pre-existing dust with a high covering factor, and suggests the optical flare may have brightened slowly for some time before it became bright detectable from the ground. More evidence is given at the later epochs. At the peak of the optical light curve, the new inner radius of the dust torus has grown to much larger size, a factor of 7 of the initial radius due to strong radiation field. At $\sim150$ days after the first optical detection, the dust temperature has dropped well below the sublimation temperature. Other peculiar spectral features shown by PS16dtm are the transient, prominent FeII emission lines and outflows indicated by broad absorption lines detected during the optical flare. Our model explains the enhanced FeII emission from iron newly released from the evaporated dust. The observed broad absorption line outflow could be explained by accelerated gas in the dust torus due to the radiation pressure.Comment: Accepted by ApJ, 5 figure