Urban theory: A critical introduction to power,cities and urbanism in the 21st century by A. Harding and T. Blokland,Sage, London, 2014. 294 pp. ISBN 978‐1‐4462‐9452‐9.          下载免费PDF全文

Francis L. Collins 《New Zealand geographer》2015,71(1):64-65

  相似文献   

Benchmarks for multicomponent reactive transport across a cement/clay interface     

Nicolas C. M. Marty  Olivier Bildstein  Philippe Blanc  Francis Claret  Benoit Cochepin  Eric C. Gaucher  Diederik Jacques  Jean-Eric Lartigue  Sanheng Liu  K. Ulrich Mayer  Johannes C. L. Meeussen  Isabelle Munier  Ingmar Pointeau  Danyang Su  Carl I. Steefel 《Computational Geosciences》2015,19(3):635-653

  相似文献   

Seasonal predictions based on two dynamical models     

Jacques Derome  Gilbert Brunet  André Plante  Normand Gagnon  George J. Boer  Francis W. Zwiers 《大气与海洋》2013,51(4):485-501

Abstract

Two dynamical models are used to perform a series of seasonal predictions. One model, referred to as GCM2, was designed as a general circulation model for climate studies, while the second one, SEF, was designed for numerical weather prediction. The seasonal predictions cover the 26‐year period 1969–1994. For each of the four seasons, ensembles of six forecasts are produced with each model, the six runs starting from initial conditions six hours apart. The sea surface temperature (SST) anomaly for the month prior to the start of the forecast is persisted through the three‐month prediction period, and added to a monthly‐varying climatological SST field.

The ensemble‐mean predictions for each of the models are verified independently, and the two ensembles are blended together in two different ways: as a simple average of the two models, denoted GCMSEF, and with weights statistically determined to minimize the mean‐square error (the Best Linear Unbiased Estimate (BLUE) method).

The GCMSEF winter and spring predictions show a Pacific/North American (PNA) response to a warm tropical SST anomaly. The temporal anomaly correlation between the zero‐lead GCMSEF mean‐seasonal predictions and observations of the 500‐hPa height field (Z₅₀₀) shows statistically significant forecast skill over parts of the PNA area for all seasons, but there is a notable seasonal variability in the distribution of the skill. The GCMSEF predictions are more skilful than those of either model in winter, and about as skilful as the better of the two models in the other seasons.

The zero‐lead surface air temperature GCMSEF forecasts over Canada are found to be skilful (a) over the west coast in all seasons except fall, (b) over most of Canada in summer, and (c) over Manitoba, Ontario and Quebec in the fall. In winter the skill of the BLUE forecasts is substantially better than that of the GCMSEF predictions, while for the other seasons the difference in skill is not statistically significant.

When the Z₅₀₀ forecasts are averaged over months two and three of the seasons (one‐month lead predictions), they show skill in winter over the north‐eastern Pacific, western Canada and eastern North America, a skill that comes from those years with strong SST anomalies of the El Niño/La Niña type. For the other seasons, predictions averaged over months two and three show little skill in Z₅₀₀ in the mid‐latitudes. In the tropics, predictive skill is found in Z₅₀₀ in all seasons when a strong SST anomaly of the El Niño/La Niña type is observed. In the absence of SST anomalies of this type, tropical forecast skill is still found over much of the tropics in months two and three of the northern hemisphere spring and summer, but not in winter and fall.  相似文献   

The Ebro Deep-Sea Fan system     

C. Hans Nelson  Andres Maldonado  Francis Coumes  Henri Got  Andre Manaco 《Geo-Marine Letters》1984,3(2-4):125-131

The Ebro Fan System consists of en echelon channel-levee complexes, 50×20 km in area and 200-m thick. A few strong reflectors in a generally transparent seismic facies identify the sand-rich channel floors and levee crests. Numerous continuous acoustic reflectors characterize overbank turbidites and hemipelagites that blanket abandoned channel-levee complexes. The interlobe areas between channel complexes fill with homogeneous mud and sand from mass flow and overbank deposition; these exhibit a transparent seismic character. The steep continental rise and sediment “drainage” of Valencia Trough at the end of the channel-levee complexes prevent the development of distributary channels and midfan lobe deposits. Margin setting represents fan and/or source area  相似文献   

On the experimental silicification of microorganisms. III. Implications of the preservation of the green prokaryotic alga prochloron and other coccoids for interpretation of the microbial fossil record     

Susan Francis  Elso S. Barghoorn  Lynn Margulis 《Precambrian Research》1978,7(4):377-383

Evidence for Precambrian fossil eukaryotic microorganisms has been based on: (1) the presence of internal ‘spots’ which have been variously interpreted to be remains of nuclei or pyrenoids of photosynthetic plastids or other organelles; (2) tetrahedral tetrad arrangement of cells; (3) trilete scars interpreted to be indicative of meiotic division: (4) large cell diameters; and (5) putative mitotic cell divisions. These features have been reported in fossils preserved in Precambrian cherts. We have studied modern microbial mats, thought to be analogues of Precambrian fossil communities, and found they may be silicified by laboratory procedures. In microbial mats from Baja California we have found many ‘spot cells’ that we could identify as remains of cyanophytes. We have silicified the newly discovered large prokaryotic coccoid green alga Prochloron and have found that it, like many cyanophytes previously silicified, preserves its structure and maintains its initial dimensions. In laboratory-silicified prokaryotic organisms we have found that all of the above criteria, supposedly characteristic of eukaryotes, can be observed. We conclude that there is no compelling morphological evidence for fossil eukaryotic microbes from Precambrian cherts.  相似文献   

Determination of volatile fatty acid turnover rates in organic-rich marine sediments     

Francis J. Sansone  Christopher S. Martens 《Marine Chemistry》1981,10(3):233-247

Volatile fatty acid (VFA) apparent turnover rates in organic-rich marine sediments were determined by measuring whole sediment VFA concentration and the corresponding first-order reaction rate constants. In order to measure VFA concentrations, bulk wet sediment samples were basified, freeze-dried, extracted with methanol, derivatized to form methyl esters of the VFAs, and analyzed by packed-column gas chromatography using hexanoic acid as an internal standard. The detection limits for acetate, propionate, iso-butyrate and butyrate were 1.0, 0.4, 0.2 and 0.2 μmol l^?1_s, respectively, for 600 ml samples. Rate constants for acetate and propionate were determined by anaerobically incubating samples at in-situ temperatures with tracer levels of ¹⁴C-labelled VFAs. Metabolized label was recovered as CO₂, CH₄, cellular material, water-soluble material, and VFA (ether-soluble) fractions. Apparent turnover rates measured during summer and winter in anoxic Cape Lookout Bight, North Carolina (U.S.A.) sediments were in the range of 19–330 μmol l^?1_s h^?1 for acetate and 0.7–7.0 μmol l^?1_s h^?1 for propionate.  相似文献   

Frozen stakes: B. Mitchell International Institute for Environment and Development,London, 1983,135 pp     

Francis Auburn 《Marine Policy》1984,8(3):285-286

  相似文献   

HD 115781 and HD 116204—two RS CVn binaries     

R. F. Griffin  Francis C. Fekel 《Journal of Astrophysics and Astronomy》1988,9(4):213-224

HD 115781 and HD 116204 (BL CVn and BM CVn) are shown to be RS CVn binaries with periods near 20 days. HD 115781 is double-lined; the primary type is about K1III, while the secondary is probably a late-type subgiant. The masses of the two components are equal within observational error. There is substantial photometric variability with a period half the orbital period; it is attributed to ellipsoidal variation. HD 116204 is also of type K1III. It shows exceptionally strong Ca II H and K emission, together with an emission-line spectrum typical of RS CVn stars in theIUE ultraviolet region, but Hα is an absorption line. The secondary star in the HD 116204 system has not been detected. The primary shows photometric variations, presumably due to starspots, with a period 5 per cent longer than the orbital period.  相似文献   

How Necessary are Large-Scale Seismic Refraction Experiments?     

T. J. G. Francis 《Geophysical Journal International》1969,18(2):223-226

  相似文献   

Prediction of heavy metal solubility in agricultural topsoils around two smelters by the physico-chemical parameters of the soils   总被引：1，自引：0，他引：1  

Matthieu?Fran?oisEmail author  Henri-Charles?Dubourguier  Dongyan?Li  Francis?Douay 《Aquatic Sciences - Research Across Boundaries》2004,66(1):78-85

  相似文献