Direct observation of the structural component of the metal-insulator phase transition and growth habits of epitaxially grown VO2 nanowires.

We have grown epitaxially orientation-controlled monoclinic VO2 nanowires without employing catalysts by a vapor-phase transport process. Electron microscopy results reveal that single crystalline VO2 nanowires having a [100] growth direction grow laterally on the basal c plane and out of the basal r and a planes of sapphire, exhibiting triangular and rectangular cross sections, respectively. In addition, we have directly observed the structural phase transition of single crystalline VO2 nanowires between the monoclinic and tetragonal phases which exhibit insulating and metallic properties, respectively, and clearly analyzed their corresponding relationships using in situ transmission electron microscopy.

Interactions between climatic variables controlling subalpine tree growth: implications for climatic history of the Sierra Nevada, California

EXTRACT (SEE PDF FOR FULL ABSTRACT): Tree-ring records from foxtail pine (Pinus balfouriana) and western juniper (Juniperus occidentalis) growing near tree line in the eastern Sierra Nevada, California, show strong correlations with summer temperature and winter precipitation. Response surfaces portraying tree growth as a function of summer temperature and winter precipitation indicate a strong interaction between these variables in controlling growth. ... Above average growth for both foxtail pine and western juniper from AD 1480 to 1570 can be interpreted as indicating an extended period of warm, moist conditions unequalled during the 20th century.

Axial compressor response to inlet flow distortions by a CFD analysis

The usual approach to compressor design considers uniform inlet flow characteristics. Especially in aircraft applications, the inlet flow is quite often non uniform, and this can result in severe performance degradation. The magnitude of this phenomenon is amplified in military engines due to the complexity of inlet duct configurations and the extreme flight conditions. CFD simulation is an innovative and powerful tool for studying inlet distortions and can bring this inside the very early phases of the design process. This project attempts to study the effects of inlet flow distortions in an axial flow compressor trying to minimize the use computer resources and computational time. The first stage of a low bypass ratio compressor has been analyzed and its clean and distorted performance compared outlining the principal changes due to uneven flow distribution: drop in mass flow, increase in pressure and temperature ratios, decrease in surge margin. Three different studies have then been conducted to better understand the effects of the level, the type and the frequency of the distortion.

湖南产五步蛇蛇毒磷脂酶A_2的热稳定性

本文测定了湖南产五步蛇蛇毒磷脂酶Ａ２在不同温度保温后的酶活性，结果表明此酶具有一定的热稳定性。

高黎贡山地区公众保护意识教育

云南西部高黎贡山地区生物多样性既丰富又受威胁。当地公众不珍惜自然、无保护常识。为拯救该地区生物资源，笔者深入基层山区村户、不拘形式或小型非正式座谈讨论方式，对１０００余人进行了公众保护意识教育，使他们懂得了生物资源的保护与持续利用益在自身和长久，控制狩猎和择猎以确保野生动物种群稳定，改变“刀耕火种”、以计划限量采伐维护森林环境等。文中对未来公众保护教育提出了建议

Differential Dynamic Microscopy: a High-Throughput Method for Characterizing the Motility of Microorganism

We present a fast, high-throughput method for characterizing the motility of microorganisms in 3D based on standard imaging microscopy. Instead of tracking individual cells, we analyse the spatio-temporal fluctuations of the intensity in the sample from time-lapse images and obtain the intermediate scattering function (ISF) of the system. We demonstrate our method on two different types of microorganisms: bacteria, both smooth swimming (run only) and wild type (run and tumble) Escherichia coli, and the bi-flagellate alga Chlamydomonas reinhardtii. We validate the methodology using computer simulations and particle tracking. From the ISF, we are able to extract (i) for E. coli: the swimming speed distribution, the fraction of motile cells and the diffusivity, and (ii) for C. reinhardtii: the swimming speed distribution, the amplitude and frequency of the oscillatory dynamics. In both cases, the motility parameters are averaged over \approx 10^4 cells and obtained in a few minutes.

EEFIT mission to Haiti following the 12th January 2010 earthquake

The Mw= 7.2 Haiti earthquake of 12th January 2010 caused extensive damage to buildings and other infrastructure in the epicentral region in and around Port-au-Prince. The Earthquake Engineering Field Investigation Team (EEFIT), which is based in the United Kingdom, organised a field mission to Haiti with the authors as the team members. The paper presents the geotechnical findings of the team including those relating to soil liquefaction and lateral spreading and discusses the performance of buildings, including historic buildings, and bridges. Unprecedented use was made of damage assessments made from remote images (i. e. images taken from satellites and aircraft) when planning the post-earthquake relief effort in Haiti and a principal objective of the team was to evaluate the accuracy of such assessments. Accordingly, 142 buildings in Port-au-Prince were inspected in the field by the EEFIT team; damage assessments had previously been made using remote images for all these buildings. On the basis of this survey, the tendency of remote assessments to underestimate damage was confirmed; it was found that the underestimate applied to assessments based on oblique images using the relatively new technique of Pictometry, as well as those based on vertical images, although to a lesser degree. The paper also discusses the distribution of damage in Port-au-Prince, which was found to be strongly clustered in ways that appear not to have been completely explained. © 2012 Springer Science+Business Media B.V.

土壤硒污染对土壤酶的生态毒理效应

通过室内培养和盆栽试验,研究了Se对黄棕壤过氧化氢酶、脱氢酶、脲酶、碱性磷酸酶、转化酶的生态毒理效应.结果表明,土壤Se对脱氢酶、碱性磷酸酶、转化酶有“抗性酶活性”现象.土壤Se对土壤过氧化氢酶和脲酶活性有抑制作用,脲酶受Se的抑制作用最强.土壤Se含量与脲酶抑制率之间具有显著相关性,脲酶抑制率可作为Se生态风险评价的一项生物指示物.

The rocking response of large flexible structures to earthquakes

The rocking response of structures subjected to strong ground motions is a problem of 'several scales'. While small structures are sensitive to acceleration pulses acting successively, large structures are more significantly affected by coherent low frequency components of ground motion. As a result, the rocking response of large structures is more stable and orderly, allowing effective isolation from the ground without imminent danger of overturning. This paper aims to characterize and predict the maximum rocking response of large and flexible structures to earthquakes using an idealized structural model. To achieve this, the maximum rocking demand caused by different earthquake records was evaluated using several ground motion intensity measures. Pulse-type records which typically have high peak ground velocity and lower frequency content caused large rocking amplitudes, whereas non-pulse type records caused random rocking motion confined to small rocking amplitudes. Coherent velocity pulses were therefore identified as the primary cause of significant rocking motion. Using a suite of pulse-type ground motions, it was observed that idealized wavelets fitted to velocity pulses can adequately describe the rocking response of large structures. Further, a parametric analysis demonstrates that pulse shape parameters affect the maximum rocking response significantly. Based on these two findings, a probabilistic analysis method is proposed for estimating the maximum rocking demand to pulse-type earthquakes. The dimensionless demand maps, produced using these methods, have predictive power in the near-field provided that pulse period and amplitude can be estimated a priori. Use of this method within a probabilistic seismic demand analysis framework is briefly discussed. © 2013 Springer Science+Business Media Dordrecht.

New type of multimode-interference-type thermo-optic variable optical attenuator

A thermo-optic variable optical attenuator (VOA) based on a Mach-Zehnder interferometer and multimode-interference coupler is fabricated. Not a single-mode but a multimode waveguide is used as the input and output structures of the optical field, which greatly reduces the coupling loss of the VOA with a normal single-mode fiber. The insertion loss of the fabricated VOA is 2.52 to 2.82 dB at the wavelength of 1520 to 1570 nm. The polarization dependent loss is 0.28 to 0.45 dB at the same wavelength range. Its maximum attenuation range is up to 26.3 dB when its power consumption is 369 mW. The response frequency of the fabricated VOA is about 10 kHz. (C) 2004 Society of Photo-Optical Instrumentation Engineers.

Lossless electroabsorption modulator monolithically rntegrated with a semiconductor optical amplifier and dual-wavegulde spot-size converters

Semiconductor optical amplifier and electroabsorption modulator monolithically integrated with dual-waveguide spot-size converters at the input and output ports is demonstrated by means of selective area growth, quantum-well intermixing, and asymmetric twin waveguide technologies. At the wavelength range of 1550 similar to 1600 nm, lossless operation with extinction ratios of 25-dB dc and 11.8-dB radio frequency and more than 10-GHz 3-dB modulation bandwidth is successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3 degrees x 10.6 degrees, respectively, resulting in 3.0-dB coupling loss with cleaved single-mode optical fiber.