Geomicrobiology of selenium: Life and death by selenite     

Nathan Yee 《Applied Geochemistry》2011

Selenite oxyanions are readily assimilated by microorganisms for the synthesis of selenoproteins. However, at elevated concentrations, selenite becomes highly toxic due to the intracellular formation of reactive oxygen species. Remarkably, some microorganisms have evolved the ability to not only survive toxic levels of selenite, but to flourish in its presence. The cultivation and genomic sequencing of dissimilatory selenite-respiring Bacteria and Archaea have begun to help elucidate the molecular mechanisms of selenite respiration.  相似文献   

Computer aided design of underground excavations in jointed rock     

C. F. Leung 《Rock Mechanics and Rock Engineering》1990,23(2):71-89

Summary Stability analysis of rock blocks that may be formed by excavating jointed rock masses is traditionally performed using the stereographic projection technique. However, such technique is prone to human errors, and existing alternative analytical methods are rather tedious and time consuming. In this paper, a computer aided approach is proposed with the prime objective that the entire analysis is automated on a microcomputer. Computer aided design features such as determination of discontinuity orientation based on borehole data, stability analysis of rock blocks involving multiple discontinuity sets, and determination of optimum excavation direction, optimum plunge of rock reinforcement and the most critical direction of earthquake force are provided.  相似文献   

The force-restore method revisited     

Samuel Y. K. Yee 《Boundary-Layer Meteorology》1988,43(1-2):85-90

The so-called ‘force-restore method’ has been used with considerable success in numerical weather prediction models to simulate diurnal variations of ground temperature. This note demonstrates that the force-restore equation is no more nor less than an approximation to the surface-energy-balance equation. The applicability of the method to the case of multi-component heating functions and to the case in which the soil is covered by a litter layer is discussed.  相似文献   

Development of seismic fragility curves for low-rise masonry infilled reinforced concrete buildings by a coefficient-based method     

Ray Kai Leung Su  Chien-Liang Lee 《地震工程与工程振动(英文版)》2013,12(2):319-332

This study presents a seismic fragility analysis and ultimate spectral displacement assessment of regular low-rise masonry infilled (MI) reinforced concrete (RC) buildings using a coefficient-based method. The coefficient-based method does not require a complicated finite element analysis; instead, it is a simplified procedure for assessing the spectral acceleration and displacement of buildings subjected to earthquakes. A regression analysis was first performed to obtain the best-fitting equations for the inter-story drift ratio (IDR) and period shift factor of low-rise MI RC buildings in response to the peak ground acceleration of earthquakes using published results obtained from shaking table tests. Both spectral acceleration-and spectral displacement-based fragility curves under various damage states (in terms of IDR) were then constructed using the coefficient-based method. Finally, the spectral displacements of low-rise MI RC buildings at the ultimate (or near-collapse) state obtained from this paper and the literature were compared. The simulation results indicate that the fragility curves obtained from this study and other previous work correspond well. Furthermore, most of the spectral displacements of low-rise MI RC buildings at the ultimate state from the literature fall within the bounded spectral displacements predicted by the coefficient-based method.  相似文献   

Leonid meteor spectrum from 110 to 860 nm     

J.F Carbary  J.-H Yee 《Icarus》2003,161(2):223-234

During the Leonid meteor shower on 18 November 1999, the five spectrographic imagers onboard the Midcourse Space Experiment (MSX) satellite recorded the first complete meteor spectra from 110 to 860 nm. The observation occurred at 00:23:36.2 UT, at which time the satellite was pointed at a tangent altitude of 100 km over 37.2°N and 78.2°E. The spectrograph slits were oriented approximately parallel to the horizon at a tangent altitude of 100 km, and the meteor passed approximately perpendicular through the slits’ fields of view. All five spectrographic imagers observed the passage of a bright object (m_v < −2.8 at 100 km) and each recorded several frames of data. In the visible, common meteor emissions were observed from iron, sodium, and oxygen. However, the ultraviolet spectrum displayed a wealth of more intense features, some of which actually caused saturation in the spectrographs. The most intense features appeared between 220 and 300 nm and are attributed to neutral and singly ionized iron and ionized magnesium. Some unknown emissions, possibly from an unidentified molecular species such as iron oxide, appear between 180 and 220 nm. In the far ultraviolet from 110 to 130 nm, oxygen and nitrogen features appear in the spectrum, with some features from ionized iron and magnesium. In particular, the FUV spectrum showed an intense emission from hydrogen Lyman alpha and a much weaker emission from what appeared to be neutral carbon. The atmospheric emissions can be associated with the heating within the meteor shock, while the metallic emissions originate from the fireball of the meteor proper. The ultraviolet emissions were much stronger than those in the visible and near-infrared parts of the spectrum. The energy of emissions in the ultraviolet (110 < λ < 337 nm) exceeded the energy of the visible (337 < λ < 650 nm) by a factor of at least 5.  相似文献   

North American extreme temperature events and related large scale meteorological patterns: a review of statistical methods,dynamics, modeling,and trends     

Richard Grotjahn  Robert Black  Ruby Leung  Michael F. Wehner  Mathew Barlow  Mike Bosilovich  Alexander Gershunov  William J. Gutowski  John R. Gyakum  Richard W. Katz  Yun-Young Lee  Young-Kwon Lim  Prabhat 《Climate Dynamics》2016,46(3-4):1151-1184

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Characterization of Non-Gaussian Geologic Facies Distribution Using Ensemble Kalman Filter with Probability Weighted Re-Sampling     

Siavash Nejadi  Juliana Leung  Japan Trivedi 《Mathematical Geosciences》2015,47(2):193-225

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Extended model of shear modulus reduction for cohesive soils     

Wong  John Kok Hee  Wong  Soon Yee  Wong  Kim Yuen 《Acta Geotechnica》2022,17(6):2347-2363

Acta Geotechnica - The shear modulus of a soil, G, shows a hyperbolic degradation curve relationship with increasing shear strain, γ. G is usually normalized against the small-strain modulus...  相似文献   

State‐led talent return migration programme and the doubly neglected ‘Malaysian diaspora’: Whose diaspora,what citizenship,whose development?          下载免费PDF全文

Sin Yee Koh 《Singapore journal of tropical geography》2015,36(2):183-200

This paper questions the assumptions of ‘diaspora’, ‘citizenship’ and ‘development’ underlying diaspora strategies targeting a specific pool of overseas Malaysian ‘talent’ migrants. I examine the Malaysian state's discursive attempts to construct a carefully contained economic ‘diaspora'—the ‘Malaysian diaspora'—through its talent return migration programme. In this process, there is a portion of the ‘Malaysian diaspora’, especially non‐bumiputeras (sons of soil), who are doubly neglected and excluded: first, from access to full and equal citizenship (which arguably contributed to their emigration in the first place); and second, from eligibility and recognition to participate in Malaysia's talent return migration programme. However, recent political activism calling for electoral reform and overseas voting rights challenges state‐constructed visions of the ‘diaspora’ and their expected roles in advancing ‘development’. This paper concludes by highlighting questions raised by the Malaysian case, linking these explicitly to how diaspora strategies—as they have been conceived, practised and contested—challenge the broader Migration and Development paradigm.  相似文献   

Vertical structure,physical properties,and energy exchange of the East Asian trough in boreal winter     

Leung  Marco Yu-Ting  Zhou  Wen 《Climate Dynamics》2015,45(5-6):1635-1656

Climate Dynamics - The relation between the intensity of the East Asian trough and the strength of the East Asian winter monsoon is documented. A prominent dipole of the available potential energy...  相似文献