Edge mode based graphene nanomechanical resonators for high-sensitivity mass sensor

We perform both molecular dynamics simulations and theoretical analysis to study the sensitivity of the graphene nanomechanical resonator based mass sensors, which are actuated following the global extended mode or the localized edge mode. We find that the mass detection sensitivity corresponding to the edge mode is about three times higher than that corresponding to the extended mode. Our analytic derivations reveal that the enhancement of the sensitivity originates in the reduction of the effective mass for the edge mode due to its localizing feature

A Partially Linear Framework for Massive Heterogeneous Data

We consider a partially linear framework for modelling massive heterogeneous data. The major goal is to extract common features across all sub-populations while exploring heterogeneity of each sub-population. In particular, we propose an aggregation type estimator for the commonality parameter that possesses the (non-asymptotic) minimax optimal bound and asymptotic distribution as if there were no heterogeneity. This oracular result holds when the number of sub-populations does not grow too fast. A plug-in estimator for the heterogeneity parameter is further constructed, and shown to possess the asymptotic distribution as if the commonality information were available. We also test the heterogeneity among a large number of sub-populations. All the above results require to regularize each sub-estimation as though it had the entire sample size. Our general theory applies to the divide-and-conquer approach that is often used to deal with massive homogeneous data. A technical by-product of this paper is the statistical inferences for the general kernel ridge regression. Thorough numerical results are also provided to back up our theory.Comment: 40 pages main text + 40 pages suppl, To appear in Annals of Statistic

Perceptions of secondary school agriculture teachers regarding biomass production education in Iowa

With the boom of biorenewable energy, biomass production has become an important segment in agriculture industry (Iowa Energy Center, 2013). A higher workforce will be needed for this burgeoning biomass energy industry (Iowa Workforce Development, n. d.). Instructional topics in agricultural education should take the form of problems and questions faced by the agriculture industry itself (Phipps, Osborne, Dyer, & Ball, 2008). This study sought to assess the perceptions of secondary agriculture teachers regarding biomass production education in Iowa. Results of this study indicated that teachers held strongly to moderately positive perceptions toward biomass production and moderately positive perceptions toward teaching about biomass. In addition, seven topics related to biomass production education were identified with higher needs for future inservice training. Past experience of teachers participating in workshops about bioenergy was found to have a positive impact on teachers\u27 perceptions regarding teaching about biomass production. In conclusion, teachers have a need for in-service training about biomass production education. It is recommended that institutes, extension organizations and corresponding professional organizations should hold more workshops about biomass production

Some Insights into the Genesis and Evolution of Dunefields Along the Lower Ganjiang River and Surrounding the Poyang Lake

AbstractBased on a body of relevant literature and field investigations, this paper presents some insights into the genesis and evolution of dunefields along the lower Ganjiang River and surrounding the Poyang Lake, Jiangxi Province, central China. After analyses and comparisons, it concluded that: 1) the dunefields in the Poyang Lake valley occurred at lest during late Quaternary, not Holocene, and there could be theoretically mid-Quaternary dunefields; 2) the essentials of genesis and evolution of dunefields exist during both Quaternary glaciations and dry seasons and periods in the Holocene, especially in specific sites such as Shaling of Xingzi County and Laoyemiao of Duchang County; 3) considering the distinct location and spatial characters of the Poyang Lake valley, as the existence of “Easten Asian Cold Trough” is possible and reasonable, glacial and aeolian processes as a coupled complex should be concurrent and synergic in a much larger spatial extent, the widespread dunefields of late Quaternary suggest more possibly the existence of corresponding glacial products in the region; 4) the future explorations in such vulnerable and distinct environments entail more original ideas and approaches as well as research and analysis techniques in order to obtain more valuable results

Temperature at Horizon in de Sitter Spacetime

It is found that there is no period in the imaginary Beltrami-time of the de Sitter spacetime with Beltrami metric and that the `surface-gravity' in view of inertial observers in de Sitter spacetime is zero! They show that the horizon might be at zero temperature in de Sitter spacetime and that the thermal property of the horizon in the de Sitter spacetime with a static metric should be analogous to that of the Rindler horizon in Minkowski spacetime.Comment: 7 pages, 1 figur