B0850+054: a new gravitational lens system from CLASS     

A. D. Biggs  D. Rusin  I. W. A. Browne  A. G. de Bruyn  N. J. Jackson  L. V. E. Koopmans  J. P. McKean  S. T. Myers  R. D. Blandford  K.-H. Chae  C. D. Fassnacht  M. A. Norbury  T. J. Pearson  P. M. Phillips  A. C. S. Readhead  P. N. Wilkinson 《Monthly notices of the Royal Astronomical Society》2003,338(4):1084-1088

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Do Spur-Throated Grasshoppers, <Emphasis Type="Italic">Melanoplus</Emphasis> spp. (Orthoptera: Acrididae), Exert Top-Down Control on Smooth Cordgrass <Emphasis Type="Italic">Spartina alterniflora</Emphasis> in Northern New England?     

David Samuel Johnson  Brita Juliet Jessen 《Estuaries and Coasts》2008,31(5):912-919

Recently, strong top-down (consumer) control of cordgrass (Spartina alterniflora) has been demonstrated. Here, we manipulated the densities of cordgrass consumers, acridid grasshoppers (Melanoplus bivittatus and Melanoplus femurrubrum), to examine their impact on cordgrass in the Plum Island Estuary (PIE), MA, USA. After 1 month, there was no detectable effect of grasshopper density on S. alterniflora biomass and grasshoppers at the highest densities (34 individuals per square meter) consumed only ~14% of the standing stock biomass. However, significant impacts of grasshopper density on grazing damage were seen. For example, plant damage and scarring length increased by 160% and 6,156%, respectively, at the highest grasshopper densities relative to exclusion (zero grasshoppers) densities. Plant height was significantly reduced with increasing grasshopper densities, although this may be a function of leaf tip removal instead of reduced plant growth. No other strong consumers of cordgrass (e.g., Littoraria irrorata, Prokelisia marginata) were observed in PIE and we suggest that consumer regulation of cordgrass is weak in this system.  相似文献   

A 256×256 pixel InSb FPA for SIRTF and other astronomical applications     

J. D. Biggs  M. A. Blessinger  M. L. Louderback 《Experimental Astronomy》1994,3(1-4):117-118

As part of the NASA Space Infrared telescope Facility (SIRTF), a low noise multiplexer has been developed. The hybridization of this multiplexer to a high indium antimonide (InSb) photodiode array has resulted in a MWIR detector of outstanding performance. The multiplexer is made of a 256×256 array of source follower amplifiers on a 30 m square pitch. Random access binary decoders are used to access each pixel of the array, allowing any read-out scheme to be implemented. Dark current has been measured at temperatures ranging from 4K to 77K. Generation recombination currents dominate above 45K. With 100mV of reverse bias applied, less than 3×10^-17 A is typical below 50K with 8×10^-19 A (5 e^-/s) at 4K. Under the same conditions 0.25 pA was measured at 77K. Read noise has been measured as low as 186 e^- using non-correlated techniques. Detector QE is 50 to 80 % through the entire 1 to 5 m band.  相似文献   

The Dahuiyeh (Zarand) earthquake of 2005 February 22 in central Iran: reactivation of an intramountain reverse fault   总被引：3，自引：0，他引：3  

M. Talebian  J. Biggs  M. Bolourchi  A. Copley  A. Ghassemi  M. Ghorashi  J. Hollingsworth  J. Jackson  E. Nissen  B. Oveisi  B. Parsons  K. Priestley  A. Saiidi 《Geophysical Journal International》2006,164(1):137-148

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The impact of epistemic uncertainty on an earthquake loss model     

Helen Crowley  Julian J. Bommer  Rui Pinho  Juliet Bird 《地震工程与结构动力学》2005,34(14):1653-1685

Models capable of estimating losses in future earthquakes are of fundamental importance for emergency planners, for the insurance and reinsurance industries, and for code drafters. Constructing a loss model for a city, region or country involves compiling databases of earthquake activity, ground conditions, attenuation equations, building stock and infrastructure exposure, and vulnerability characteristics of the exposed inventory, all of which have large associated uncertainties. Many of these uncertainties can be classified as epistemic, implying—at least in theory—that they can be reduced by acquiring additional data or improved understanding of the physical processes. The effort and cost involved in refining the definition of each component of a loss model can be very large, for which reason it is useful to identify the relative impact on the calculated losses due to variations in these components. A mechanically sound displacement‐based approach to loss estimation is applied to a test case of buildings along the northern side of the Sea of Marmara in Turkey. Systematic variations of the parameters defining the demand (ground motion) and the capacity (vulnerability) are used to identify the relative impacts on the resulting losses, from which it is found that the influence of the epistemic uncertainty in the capacity is larger than that of the demand for a single earthquake scenario. Thus, the importance of earthquake loss models which allow the capacity parameters to be customized to the study area under consideration is highlighted. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Assessing infrequent large earthquakes using geomorphology and geodesy: the Malawi Rift     

Michael Hodge  Juliet Biggs  Katsuichiro Goda  Willy Aspinall 《Natural Hazards》2015,76(3):1781-1806

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Intrinsic intraday variability in the gravitational lens system B0218+357     

A. D. Biggs  I. W. A. Browne  P. N. Wilkinson 《Monthly notices of the Royal Astronomical Society》2001,323(4):995-998

Radio monitoring of the gravitational lens system B0218+357 reveals it to be a highly variable source with variations on time-scales of a few days correlated in both images. This shows that the variability is intrinsic to the background lensed source and suggests that similar variations in other intraday variable sources can also be intrinsic in origin.  相似文献   

Confirming a population of hot-dust dominated, star-forming, ultraluminous galaxies at high redshift     

C. M. Casey  S. C. Chapman  R. J. Beswick  A. D. Biggs  A. W. Blain  L. J. Hainline  R. J. Ivison  T. W. B. Muxlow  Ian Smail 《Monthly notices of the Royal Astronomical Society》2009,399(1):121-128

We identify eight   z > 1  radio sources undetected at 850 μm but robustly detected at 70 μm, confirming that they represent ultraluminous infrared galaxies (ULIRGs) with hotter dust temperatures  (〈 T _d〉= 52 ± 10 K)  than submillimetre galaxies (SMGs) at similar luminosities and redshifts. These galaxies share many properties with SMGs: ultraviolet spectra consistent with starbursts, high stellar masses and radio luminosities. We can attribute their radio emission to star formation since high-resolution Multi-Element Radio Linked Interferometer Network (MERLIN) radio maps show extended emission regions (with characteristic radii of 2–3 kpc), which are unlikely to be generated by active galactic nucleus (AGN) activity. These observations provide the first direct confirmation of hot, dusty ULIRGs which are missed by current submillimetre surveys. They have significant implications for future observations from the Herschel Space Observatory and Submillimetre Common-User Bolometer Array 2 (SCUBA2), which will select high-redshift luminous galaxies with less selection biases.  相似文献   

Analytic estimates and topological properties of the weak stability boundary     

Marta Ceccaroni  James Biggs  Luca Biasco 《Celestial Mechanics and Dynamical Astronomy》2012,114(1-2):1-24

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Exploring the infrared/radio correlation at high redshift     

Edo Ibar  Michele Cirasuolo  Rob Ivison  Philip Best  Ian Smail  y Biggs  Chris Simpson  Jim Dunlop  Omar Almaini  Ross McLure  Sebastien Foucaud  Steve Rawlings 《Monthly notices of the Royal Astronomical Society》2008,386(2):953-962

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