Structural optimum design of bistable cylindrical shell for broadband energy harvesting application

AbstractThe shallow cylindrical structure is suitable to develop broadband vibration energy harvesters due to the property of the inherent mechanical bistability. In this letter, the optimum design of the bistable cylindrical shell for broadband energy harvesting application is investigated from the structural point of view. The output power is evaluated by the concept of the harvestable power, which balances the frequency of snap through and the referred output energy associated with each snap through. The non-dimensional harvestable power is analytically expressed as the function of the non-dimensional curvature parameter and one constructed parameter. The universal dependence of the optimal curvature parameter and the associated optimal harvestable power on the constructed parameter is derived, which can be well approximated by the linear relation in double logarithmic coordinate

Mid-infrared variability of changing-look AGN

It is known that some active galactic nuclei (AGNs) transited from type 1 to type 2 or vice versa. There are two explanations for the so-called changing look AGNs: one is the dramatic change of the obscuration along the line-of-sight, the other is the variation of accretion rate. In this paper, we report the detection of large amplitude variations in the mid-infrared luminosity during the transitions in 10 changing look AGNs using WISE and newly released NEOWISE-R data. The mid-infrared light curves of 10 objects echoes the variability in the optical band with a time lag expected for dust reprocessing. The large variability amplitude is inconsistent with the scenario of varying obscuration, rather supports the scheme of dramatic change in the accretion rate.Comment: Published by ApjL, 7 pages, 3 figures, 2 table

On the concentration properties of Interacting particle processes

These lecture notes present some new concentration inequalities for Feynman-Kac particle processes. We analyze different types of stochastic particle models, including particle profile occupation measures, genealogical tree based evolution models, particle free energies, as well as backward Markov chain particle models. We illustrate these results with a series of topics related to computational physics and biology, stochastic optimization, signal processing and bayesian statistics, and many other probabilistic machine learning algorithms. Special emphasis is given to the stochastic modeling and the quantitative performance analysis of a series of advanced Monte Carlo methods, including particle filters, genetic type island models, Markov bridge models, interacting particle Markov chain Monte Carlo methodologies

Discovery of a Mid-infrared Echo from the TDE candidate in the nucleus of ULIRG F01004-2237

We present the mid-infrared (MIR) light curves (LCs) of a tidal disruption event (TDE) candidate in the center of a nearby ultraluminous infrared galaxy (ULIRG) F01004-2237 using archival {\it WISE} and {\it NEOWISE} data from 2010 to 2016. At the peak of the optical flare, F01004-2237 was IR quiescent. About three years later, its MIR fluxes have shown a steady increase, rising by 1.34 and 1.04 mag in $3.4$ and $4.6\mu$m up to the end of 2016. The host-subtracted MIR peak luminosity is $2-3\times10^{44}$\,erg\,s$^{-1}$. We interpret the MIR LCs as an infrared echo, i.e. dust reprocessed emission of the optical flare. Fitting the MIR LCs using our dust model, we infer a dust torus of the size of a few parsecs at some inclined angle. The derived dust temperatures range from $590-850$\,K, and the warm dust mass is $\sim7\,M_{\odot}$. Such a large mass implies that the dust cannot be newly formed. We also derive the UV luminosity of $4-11\times10^{44}$\,erg\,s$^{-1}$. The inferred total IR energy is $1-2\times10^{52}$\,erg, suggesting a large dust covering factor. Finally, our dust model suggests that the long tail of the optical flare could be due to dust scattering

Stability of five-dimensional Myers-Perry black holes under massive scalar perturbation: bound states and quasinormal modes

The stability of five-dimensional singly rotating Myers-Perry Black Holes against massive scalar perturbations is studied. Both the quasibound states and quasinormal modes of the massive scalar field are considered. For the quasibound states, we use an analytical method to discuss the effective potential felt by the scalar field, and found that there is no potential well outside the event horizon. Thus, singly rotating Myers-Perry Black Holes are stable against the perturbation of quasibound states of massive scalar fields. Then, We use continued fraction method based on solving a seven-term recurrence relations to compute the spectra of the quasinormal modes. For different values of the black hole rotation parameter $a$, scalar mass parameter $\mu$ and angular quantum numbers, all found quasinormal modes are damped. So singly rotating Myers-Perry Black Holes are also stable against the perturbation of quasinormal modes of massive scalar fields. Besides, when the scalar mass $\mu$ becomes relatively large, the long-living quasiresonances are also found as in other rotating black hole models. Our results complement previous arguments on the stability of five-dimensional singly rotating Myers-Perry black holes against massive scalar perturbations.Comment: references adde

MetaBinG: Using GPUs to Accelerate Metagenomic Sequence Classification

Metagenomic sequence classification is a procedure to assign sequences to their source genomes. It is one of the important steps for metagenomic sequence data analysis. Although many methods exist, classification of high-throughput metagenomic sequence data in a limited time is still a challenge. We present here an ultra-fast metagenomic sequence classification system (MetaBinG) using graphic processing units (GPUs). The accuracy of MetaBinG is comparable to the best existing systems and it can classify a million of 454 reads within five minutes, which is more than 2 orders of magnitude faster than existing systems. MetaBinG is publicly available at http://cbb.sjtu.edu.cn/~ccwei/pub/software/MetaBinG/MetaBinG.php

Climate change impact on China food security in 2050

Climate change is now affecting global agriculture and food production worldwide. Nonetheless the direct link between climate change and food security at the national scale is poorly understood. Here we simulated the effect of climate change on food security in China using the CERES crop models and the IPCC SRES A2 and B2 scenarios including CO2 fertilization effect. Models took into account population size, urbanization rate, cropland area, cropping intensity and technology development. Our results predict that food crop yield will increase +3-11 % under A2 scenario and +4 % under B2 scenario during 2030-2050, despite disparities among individual crops. As a consequence China will be able to achieve a production of 572 and 615 MT in 2030, then 635 and 646 MT in 2050 under A2 and B2 scenarios, respectively. In 2030 the food security index (FSI) will drop from +24 % in 2009 to -4.5 % and +10.2 % under A2 and B2 scenarios, respectively. In 2050, however, the FSI is predicted to increase to +7.1 % and +20.0 % under A2 and B2 scenarios, respectively, but this increase will be achieved only with the projected decrease of Chinese population. We conclude that 1) the proposed food security index is a simple yet powerful tool for food security analysis; (2) yield growth rate is a much better indicator of food security than yield per se; and (3) climate change only has a moderate positive effect on food security as compared to other factors such as cropland area, population growth, socio-economic pathway and technology development. Relevant policy options and research topics are suggested accordingly

Genome-wide analysis of alternative splicing of pre-mRNA under salt stress in Arabidopsis

BACKGROUND: Alternative splicing (AS) of precursor mRNA (pre-mRNA) is an important gene regulation process that potentially regulates many physiological processes in plants, including the response to abiotic stresses such as salt stress. RESULTS: To analyze global changes in AS under salt stress, we obtained high-coverage (~200 times) RNA sequencing data from Arabidopsis thaliana seedlings that were treated with different concentrations of NaCl. We detected that ~49% of all intron-containing genes were alternatively spliced under salt stress, 10% of which experienced significant differential alternative splicing (DAS). Furthermore, AS increased significantly under salt stress compared with under unstressed conditions. We demonstrated that most DAS genes were not differentially regulated by salt stress, suggesting that AS may represent an independent layer of gene regulation in response to stress. Our analysis of functional categories suggested that DAS genes were associated with specific functional pathways, such as the pathways for the responses to stresses and RNA splicing. We revealed that serine/arginine-rich (SR) splicing factors were frequently and specifically regulated in AS under salt stresses, suggesting a complex loop in AS regulation for stress adaptation. We also showed that alternative splicing site selection (SS) occurred most frequently at 4 nucleotides upstream or downstream of the dominant sites and that exon skipping tended to link with alternative SS. CONCLUSIONS: Our study provided a comprehensive view of AS under salt stress and revealed novel insights into the potential roles of AS in plant response to salt stress. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2164-15-431) contains supplementary material, which is available to authorized users