The Discovery of a Second Field Methane Brown Dwarf from Sloan Digital Sky Survey Commissioning Data     

Tsvetanov ZI  Golimowski DA  Zheng W  Geballe TR  Leggett SK  Ford HC  Davidsen AF  Uomoto A  Fan X  Knapp GR  Strauss MA  Brinkmann J  Lamb DQ  Newberg HJ  Rechenmacher R  Schneider DP  York DG  Lupton RH  Pier JR  Annis J  Csabai I  Hindsley RB  Ivesic Z  Munn JA  Thakar AR  Waddell P 《The Astrophysical journal》2000,531(1):L61-L65

We report the discovery of a second field methane brown dwarf from the commissioning data of the Sloan Digital Sky Survey (SDSS). The object, SDSS J134646.45-003150.4 (hereafter SDSS 1346-00), was selected because of its very red color and stellar appearance. Its spectrum between 0.8 and 2.5 μm is dominated by strong absorption bands of H2O and CH4 and closely mimics those of Gliese 229B and SDSS 162414.37+002915.6 (hereafter SDSS 1624+00), two other known methane brown dwarfs. SDSS 1346-00 is approximately 1.5 mag fainter than Gliese 229B, suggesting that it lies about 11 pc from the Sun. The ratio of flux at 2.1 μm to that at 1.27 μm is larger for SDSS 1346-00 than for Gliese 229B and SDSS 1624+00, which suggests that SDSS 1346-00 has a slightly higher effective temperature than the others. Based on a search area of 130 deg2 and a detection limit of z*=19.8, we estimate a space density of 0.05 pc-3 for methane brown dwarfs with Teff approximately 1000 K in the 40 pc3 volume of our search. This estimate is based on small-sample statistics and should be treated with appropriate caution.  相似文献   

Towards a spatio-temporal multicriteria evaluation method: A suitability analysis of residential units in a 3D urban environment     

Kendra Munn  Suzana Dragićević 《Transactions in GIS》2023,27(7):1830-1845

Spatial multi-criteria evaluation (MCE) techniques aid urban planning management by analyzing decision problem alternatives for solutions to help inform decision-making. However, there is a lack of such methods that incorporate the temporal dimension, an important factor when analyzing the dynamic urban landscape and decisions surrounding its changes. A novel spatio-temporal MCE approach is proposed that operates in three-dimensional (3D) space and time to identify changing suitability values of decision alternatives. This space–time method is implemented to evaluate the suitability of residential units over a 15-year period in part of downtown City of Vancouver, Canada. The results indicate that the majority of units exhibit a decrease in suitability with time due to depreciation and reduction of assets like view and privacy from the construction of new buildings. The proposed method can be used by urban planners and developers to assist in long-term assessments of proposed development scenarios and their impact on existing urban infrastructure.  相似文献   

Two warm frontal passages at Ottawa,Canada     

R.E. Munn 《大气与海洋》2013,51(4):125-157

The numerical simulations of Baumhefner (1971, 1972) and Miyakoda and Umscheid (1973) have shown that a “wall” placed at or near the equator has a serious effect on Northern Hemisphere forecasts after 10–14 days.

In practice, however, numerical models have available some information from the Southern Hemisphere. The question is posed, “How much information from the Southern Hemisphere is necessary to yield a forecast for the Northern Hemisphere which is more accurate than that obtained by integrating over the Northern Hemisphere alone?”

A simple numerical experiment demonstrates that a global model in which only the largest scales of the Southern Hemisphere are known at initial time yields a more accurate forecast for the Northern Hemisphere than a hemispheric model.  相似文献   

Obituary Prof. Helmut Landsberg     

R. E. Munn 《Theoretical and Applied Climatology》1986,36(3-4):381-382

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Book reviews     

G. T. Csanady  R. E. Munn 《Boundary-Layer Meteorology》1975,9(4):501-502

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Editor's preface     

R. E. Munn 《Boundary-Layer Meteorology》1970,1(1):3-4

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Spatial characterisation of the Benguela ecosystem for ecosystem-based management     

SP Kirkman  L Blamey  T Lamont  G Bianchi  JA Huggett 《African Journal of Marine Science》2016,38(1):7-22

The three countries of the Benguela Current Large Marine Ecosystem (BCLME), namely Angola, Namibia and South Africa, have committed to implementing ecosystem-based management (EBM) including an ecosystem approach to fisheries (EAF) in the region, to put in practice the principles of sustainable development in ocean-related matters. There is also recognition of the need for marine spatial planning (MSP) as a process for informing EBM with regard to the allocation and siting of ocean uses so that ecosystem health is ensured and trade-offs between ecosystem services are appropriately dealt with. Marine spatial planning is both an integrated and an area-based process, and this paper produces a spatial characterisation of the BCLME for achieving a common basis for MSP in the region, focusing on the oceanography, biology and fisheries. Recognising spatial variation in physical driving forces, primary and secondary production, trophic structures and species richness, four different subsystems are characterised: (1) north of the Angola–Benguela Front, (2) from the Angola–Benguela Front to Lüderitz, (3) from Lüderitz to Cape Agulhas, and (4) from Cape Agulhas to Port Alfred on the south-east coast of South Africa. Research and monitoring requirements of relevance for MSP and EBM in the region are identified, focusing on understanding variability and change, including with regard to the boundary areas identified for the system. To this end, 14 cross-shelf monitoring transects are proposed (including seven that are already being monitored) to estimate fluxes of biota, energy and materials within and between the subsystems. The usefulness of models for understanding ecosystem variability and changes is recognised and the need for fine-scale resolution of both sampling and modelling for adequate MSP as input to EBM for the often-conflicting interests of conserving biodiversity, and managing fisheries, recreation, offshore oil and gas exploration and exploitation, offshore mining and shipping routes, is emphasised.  相似文献   

Book review     

R. E. Munn 《Boundary-Layer Meteorology》1975,9(3):371-371

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Secular increases in summer haziness in the Atlantic provinces     

R.E. Munn 《大气与海洋》2013,51(4):156-161

Since 1953, there has been a significant increase in the number of hours (May to October) of reported haze, smoke and/or dust at synoptic observing stations in the Atlantic Provinces and Eastern Quebec. Because the increase is associated mainly with south to southwest winds, and because there has in fact been a decrease in particulate emissions in eastern North America during this period, the suggestion is made that the increase in haziness is due to increasing photochemical activity, resulting from greater emissions of gases such as SO₂ and NO_x from sources along the United States eastern seaboard.  相似文献   

Use of probiotic bacteria to improve growth and survivability of farmed New Zealand abalone (Haliotis iris)     

JA Hadi  AC Alfaro  RD Roberts 《新西兰海洋与淡水研究杂志》2014,48(3):405-415

The effects of two probiotic feeds containing two and three bacterial isolates were evaluated on the growth performance of New Zealand abalone (Haliotis iris). Probiotic bacteria were isolated from the guts of healthy adult abalone. The isolates were screened qualitatively and quantitatively according to their ability to hydrolyse nutrients (i.e. proteins, starch and alginate), produce acid and resist bile salts. Based on the screening results, we developed a multi-strain conglomerate of 2- and 3- probiotic bacterial strains that were supplemented into a commercial abalone feed to use in our experiments. The 2-probiotic conglomerate consisted of Exiguobacterium JHEb1 and Vibrio JH1, and the 3-probiotic conglomerate consisted of Exiguobacterium JHEb1, Vibrio JH1 and Enterococcus JHLDc. The probiotic feeding trial involved abalone juveniles (20–30 mm in maximum shell length). Both probiotic feeds significantly improved abalone growth compared to that of the unsupplemented feed. The 3-probiotic supplemented feed produced a significant shell length increase of 20.9%, a wet weight gain of 19.8% and a five-fold reduction in mortality compared to the controls. The 2-probiotic supplemented feed resulted in significant increases in shell length (15.4%) and reduced mortality (five-fold), but not in weight gain, compared to controls.  相似文献