Post-transient relaxation in graphene after an intense laser pulse

High intensity laser pulses were recently shown to induce a population inverted transient state in graphene [T. Li et al. Phys. Rev. Lett. 108, 167401 (2012)]. Using a combination of hydrodynamic arguments and a kinetic theory we determine the post-transient state relaxation of hot, dense, population inverted electrons towards equilibrium. The cooling rate and charge-imbalance relaxation rate are determined from the Boltzmann-equation including electron-phonon scattering. We show that the relaxation of the population inversion, driven by inter-band scattering processes, is much slower than the relaxation of the electron temperature, which is determined by intra-band scattering processes. This insight may be of relevance for the application of graphene as an optical gain medium.Comment: 10 pages, 4 figures, submitted as contribution of the IMPACT Special Topics series of the EP

Teaching unit on pets for English language learners

Master of ArtsModern LanguagesMary T. CoppleDue to the fact that some English as a foreign language students lack motivation to learn English, this report will discuss how to promote their motivation by structuring appropriate lesson plans; giving students authentic L2 input; designing meaningful and communicative activities; choosing the right type of question to create learning opportunities; and using the guided inductive instructional approach for grammar teaching. Also, it will discuss how to prepare to be a 21st century teacher. The second part of this report contains detailed lesson plans for a unit on pets in which pedagogical theory is put into practice. This unit is mainly designed for low intermediate level English learners. The objectives of this lesson plan not only aim for improving students’ English language skills but also developing their animal and environmental protection awareness

The Method of Establishing Analogy Reservoir for Low Permeability Sandstone Reservoir

Analogy reservoir is accurate or not, related to the reliability of the SEC reserves evaluation. According to the characteristics of Jilin Oilfield low permeability sandstone reservoir, in accordance with SEC new rules and the principle of analogy reservoir establishment, we establish analogy reservoir of low permeability sandstone reservoir by taking the steps of selecting analogy reservoir, calculating geological reserves, evaluating recoverable reserves, and defining analogy recovery. With this method, we set up analogy reservoir sequence of low permeability sandstone reservoir and the sequence provides a reliable basis for SEC reserves evaluation. Key words: SEC rules; Geological reserves; Recoverable reserves; Analogy reservoir; Recovery efficienc