Radar detection of the nucleus and coma of comet hyakutake     

JK Harmon  SJ Ostro  LAM Benner  KD Rosema  RF Jurgens  R Winkler  DK Yeomans  D Choate  R Cormier  JD Giorgini  DL Mitchell  PW Chodas  R Rose  D Kelley  MA Slade  ML Thomas 《Science (New York, N.Y.)》1997,278(5345):1921-1924

Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from the nucleus and from large grains in the inner coma. The nucleus of this bright comet was estimated to be only 2 to 3 kilometers in diameter. Models of the coma echo indicate backscatter from porous, centimeter-size grains ejected anisotropically at velocities of tens of meters per second. The radar observations suggest that a comet's activity may be a poor indicator of its size and provide evidence that large grains constitute an important component of the mass loss from a typical active comet.  相似文献   

A Comparison of SIR-B Directional Ocean Wave Spectra with Aircraft Scanning Radar Spectra     

Beal RC  Monaldo FM  Tilley DG  Irvine DE  Walsh EJ  Jackson FC  Hancock DW  Hines DE  Swift RN  Gonzalez FL  Lyzenga DR  Zambresky LF 《Science (New York, N.Y.)》1986,232(4757):1531-1535

Directional ocean wave spectra derived from Shuttle Imaging Radar-B (SIR-B) L-band imagery collected off the coast of southern Chile on 11 and 12 October 1984 were compared with independent spectral estimates from two airborne scanning radars. In sea states with significant wave heights ranging from 3 to 5 meters, the SIR-B-derived spectra at 18 degrees and 25 degrees off nadir yielded reasonable estimates of wavelengths, directions, and spectral shapes for all wave systems encountered, including a purely azimuth-traveling system. A SIR-B image intensity variance spectrum containing predominantly range-traveling waves closely resembles an independent aircraft estimate of the slope variance spectrum. The prediction of a U.S. Navy global spectral ocean wave model on 11 October 1984 exhibited no significant bias in dominant wave number but contained a directional bias of about 30 degrees espect to the mean of the aircraft and spacecraft estimates.  相似文献   

The use of littoral mesohabitats and their macroinvertebrate assemblages in the ecological assessment of lakes     

J. White  K. Irvine 《水产资源保护:海洋与淡水生态系统》2003,13(4):331-351

• 1. Historically, ecological assessment of lakes has depended on open‐water chemical and phytoplankton analysis, with trophic status determined by chlorophyll a and total phosphorus following the general protocol of the OECD lake classification scheme. This has been accompanied by a prevailing opinion that the littoral zone of lakes is too heterogeneous to allow meaningful inter‐lake comparisons.
• 2. Council of the European Communities Directive 2000/60/EC establishing a framework in the field of water policy (the Water Framework Directive) requires a broader approach to ecological assessment, including the need to incorporate a range of biotic variables. This paper describes the results of a monitoring programme designed to determine within‐ and among‐lake variation of macroinvertebrate communities found in defined mesohabitats of 22 lakes incorporating a range of lake types. Three sampling approaches were applied to the study.
• 3. Triplicate macroinvertebrate samples from a cobble/pebble mesohabitat of 11 lakes showed that community composition from a standard habitat was robust.
• 4. Twinned samples from contrasting habitats of pebble/cobble and macrophyte dominated mesohabitats of 21 lakes had greater similarity within than among lakes. This showed that even across contrasting habitat structure, macroinvertebrate assemblages can provide a reliable lake‐specific indicator.
• 5. Multivariate analysis of replicate samples from 15 visually distinct mesohabitats in one lake showed that within‐lake variation could, nevertheless, be identified as distinct clusters of invertebrate assemblages.
• 6. Conclusions from the work are that variations within lakes were nested in among‐lake variation across a range of lake types, and that macroinvertebrate assemblages can provide meaningful assessment of ecological differences across lakes. Monitoring can, however, produce a substantial amount of ‘noise’ from the data that reflects the complexity of macroinvertebrate community structure in littoral zones. It is recommended that incorporation of macroinvertebrates in ecological assessment is most useful when confined to well defined mesohabitats rather than attempt to incorporate a complete range of mesohabitats within a single lake.

Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

Spinal aspergillosis in pheasants     

Barnett J  Booth P  Arrow M  Garcia-Rueda C  Irvine RM 《The Veterinary record》2011,169(17):449-450

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Outbreak of highly pathogenic avian influenza caused by Asian lineage H5N1 virus in turkeys in Great Britain in January 2007     

Irvine RM  Banks J  Londt BZ  Lister SA  Manvell RJ  Outtrim L  Russell C  Cox WJ  Ceeraz V  Shell W  Landeg FJ  Wilesmith JW  Alexander DJ  Brown IH 《The Veterinary record》2007,161(3):100-101

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Reposition of prolapsed uterus in the cow     

C.H.G. Irvine B.V.Sc. 《New Zealand veterinary journal》2013,61(3):63-64

Extract

The dismay which is evoked by the sight of a totally prolapsed and swollen uterus is familiar to all large-animal practitioners. The prolapsed horn (simultaneous individual prolapse of both horns is not possible because of the intercornuate ligament) is frequently 8 to 10 in. in diameter and its reposition requires Herculean efforts. If, as often happens, the animal is unable to rise, owing to concurrent hypocalcaemia or other causes, the difficulties and discomforts associated with reposition are greatly increased. Facilities for raising the cow's hindquarters are commonly not available and, even where they are, this manoeuvre can be very time-consuming.  相似文献   

A national scale inventory of resource provision for biodiversity within domestic gardens     

Zoe G. Davies  Alison Loram  Katherine N. Irvine  Kevin J. Gaston 《Biological conservation》2009,142(4):761-766

The human population is increasingly disconnected from nature due to urbanisation. To counteract this phenomenon, the UK government has been actively promoting wildlife gardening. However, the extent to which such activities are conducted and the level of resource provision for biodiversity (e.g., food and nesting sites) within domestic gardens remains poorly documented. Here we generate estimates for a selection of key resources provided within gardens at a national scale, using 12 survey datasets gathered across the UK. We estimate that 22.7 million households (87% of homes) have access to a garden. Average garden size is 190 m², extrapolating to a total area of 432,924 ha. Although substantial, this coverage is still an order of magnitude less than that of statutory protected areas. Approximately 12.6 million (48%) households provide supplementary food for birds, 7.4 million of which specifically use bird feeders. Similarly, there are a minimum of 4.7 million nest boxes within gardens. These figures equate to one bird feeder for every nine potentially feeder-using birds in the UK, and at least one nest box for every six breeding pairs of cavity nesting birds. Gardens also contain 2.5-3.5 million ponds and 28.7 million trees, which is just under a quarter of all trees occurring outside woodlands. Ongoing urbanisation, characterised by increased housing densities, is inevitable throughout the UK and elsewhere. The important contribution domestic gardens make to the green space infrastructure in residential areas must be acknowledged, as their reduction will impact biodiversity conservation, ecosystem services, and the well-being of the human population.  相似文献   

Semiochemicals to enhance herbivory by Diorhabda carinulata aggregations in saltcedar (Tamarix spp.) infestations          下载免费PDF全文

Alexander M Gaffke  Sharlene E Sing  Tom L Dudley  Daniel W Bean  Justin A Russak  Agenor Mafra‐Neto  Paul A Grieco  Robert KD Peterson  David K Weaver 《Pest management science》2018,74(6):1494-1503

BACKGROUND

Semiochemicals for monitoring, attracting or repelling pest and beneficial organisms are increasingly deployed in agricultural and forest systems for pest management. However, the use of aggregation pheromones and host‐plant attractants for the express purpose of increasing the efficacy of classical biological control agents of weeds has not been widely reported. Therefore, we conducted field‐based assays to determine if a specialized wax‐based matrix impregnated with an aggregation pheromone of the northern tamarisk beetle Diorhabda carinulata (Desbrochers) or host‐plant volatiles could increase the efficacy of D. carinulata.

RESULTS

The aggregation pheromone and host‐plant volatiles were formulated for field application using a wax‐based matrix. Reported release rates suggest that this matrix is a viable formulation for enhancing D. carinulata aggregations under field conditions. Pheromone‐treated saltcedar plants (Tamarix spp.) not only had higher densities of adult and larval D. carinulata, but also sustained greater levels of foliar damage than control plants. Increased damage from the focused feeding of D. carinulata caused an increase in foliar dieback and decrease in live canopy volume of semiochemical‐treated plants.

CONCLUSION

Field deployment of these semiochemical formulations could be useful in directing populations of D. carinulata for increased impact on Tamarix spp. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

Spin Hall effect transistor     

Wunderlich J  Park BG  Irvine AC  Zârbo LP  Rozkotová E  Nemec P  Novák V  Sinova J  Jungwirth T 《Science (New York, N.Y.)》2010,330(6012):1801-1804

The field of semiconductor spintronics explores spin-related quantum relativistic phenomena in solid-state systems. Spin transistors and spin Hall effects have been two separate leading directions of research in this field. We have combined the two directions by realizing an all-semiconductor spin Hall effect transistor. The device uses diffusive transport and operates without electrical current in the active part of the transistor. We demonstrate a spin AND logic function in a semiconductor channel with two gates. Our study shows the utility of the spin Hall effect in a microelectronic device geometry, realizes the spin transistor with electrical detection directly along the gated semiconductor channel, and provides an experimental tool for exploring spin Hall and spin precession phenomena in an electrically tunable semiconductor layer.  相似文献   

Pesticide fate in tropical soils     

KD Racke  M Skidmore  DJ Hamilton  JB Unsworth  J Miyamoto  SZ Cohen 《Pest management science》1999,55(2):219-220

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