Rebel Cities: From the Right to the City to the Urban Revolution by David Harvey. Verso,London and New York, 2013, 206 pages (ISBN‐13: 978‐1‐78168‐074‐2) (pbk).     

Rita Padawangi 《Singapore journal of tropical geography》2014,35(2):285-286

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The Growth of the Planetary Boundary Layer at a Coastal Site: a Case Study   总被引：2，自引：1，他引：1  

Ferdinando De Tomasi  M. Marcello Miglietta  M. Rita Perrone 《Boundary-Layer Meteorology》2011,139(3):521-541

A lidar system is used to determine the diurnal evolution of the planetary boundary layer (PBL) height on a summer day characterized by anticyclonic conditions. The site is located some 15 km distant from the sea, on a peninsula in south-east Italy. Contrary to expectations, the PBL height, after an initial growth consequent to sunrise, ceases to increase about 2 h before noon and then decreases and stabilizes in the afternoon. An interpretation of such anomalous behaviour is provided in terms of trajectories of air parcels towards the lidar site, which are influenced by the sea breeze, leading to a transition from a continental boundary layer to a coastal internal boundary layer. The results are analyzed using mesoscale numerical model simulations and a simple model that allows for a more direct interpretation of experimental results.  相似文献   

Intraurban variability of PM10 and PM2.5 in an Eastern Mediterranean city     

Rawad Massoud  Alan.L Shihadeh  Mohamed Roumié  Myriam Youness  Jocelyne Gerard  Nada Saliba  Rita Zaarour  Maher Abboud  Wehbeh Farah  Najat Aoun Saliba 《Atmospheric Research》2011,101(4):893-901

The results of the first large scale chemical characterization of PM10 and PM2.5 at three different sites in the urban city of Beirut, Lebanon, are presented. Between May 2009 and April 2010 a total of 304 PM10 and PM2.5 samples were collected by sampling every sixth day at three different sites in Beirut. Observed mass concentrations varied between 19.7 and 521.2 μg m^? 3 for PM10 and between 8.4 and 72.2 μg m^? 3 for PM2.5, respectively. Inorganic concentrations accounted for 29.7–35.6 μg m^? 3 and 46.0–53.5 μg m^? 3 of the total mass of PM10 and PM2.5, respectively. Intra-city temporal and spatial variations were assessed based on the study of three factors: correlation coefficients (R) for PM and chemical components, coefficient of divergence (CODs), and source apportionment using positive matrix factorization (PMF). Based on R and COD of PM concentrations, the three sites appear homogeneous. However, when individual elements were compared, heterogeneity among sites was found. This latter was attributed to the variability in the percent contribution of biogenic and local anthropogenic source factors such as traffic related sources and dust resuspension. Other factors included the proximity to the Mediterranean sea, the population density and the topographical structure of the city. Hence, despite its small size (20.8 km²), one PM monitoring site does not reflect an accurate PM level in Beirut.  相似文献   

Electromagnetic fields generated by finite‐length wire sources: comparison with point dipole solutions     

Rita Streich  Michael Becken 《Geophysical Prospecting》2011,59(2):361-374

In present‐day land and marine controlled‐source electromagnetic (CSEM) surveys, electromagnetic fields are commonly generated using wires that are hundreds of metres long. Nevertheless, simulations of CSEM data often approximate these sources as point dipoles. Although this is justified for sufficiently large source‐receiver distances, many real surveys include frequencies and distances at which the dipole approximation is inaccurate. For 1D layered media, electromagnetic (EM) fields for point dipole sources can be computed using well‐known quasi‐analytical solutions and fields for sources of finite length can be synthesized by superposing point dipole fields. However, the calculation of numerous point dipole fields is computationally expensive, requiring a large number of numerical integral evaluations. We combine a more efficient representation of finite‐length sources in terms of components related to the wire and its end points with very general expressions for EM fields in 1D layered media. We thus obtain a formulation that requires fewer numerical integrations than the superposition of dipole fields, permits source and receiver placement at any depth within the layer stack and can also easily be integrated into 3D modelling algorithms. Complex source geometries, such as wires bent due to surface obstructions, can be simulated by segmenting the wire and computing the responses for each segment separately. We first describe our finite‐length wire expressions and then present 1D and 3D examples of EM fields due to finite‐length sources for typical land and marine survey geometries and discuss differences to point dipole fields.  相似文献   

Ammonium,nitrate and phytoplankton interactions in a freshwater tidal estuarine zone: potential effects of cultural eutrophication   总被引：2，自引：0，他引：2  

Rita B. Domingues  Ana B. Barbosa  Ulrich Sommer  Helena M. Galvão 《Aquatic Sciences - Research Across Boundaries》2011,73(3):331-343

Nitrate and ammonium are the most important nitrogen sources for phytoplankton growth. Differential utilization of inorganic nitrogenous compounds by phytoplankton has been observed and may have significant impacts on primary productivity at local scales. We used enrichment experiments with natural phytoplankton populations from the freshwater tidal zone of the Guadiana estuary, a coastal ecosystem increasingly subjected to anthropogenic influences, to study the effects of nitrate and ammonium on N-consumption and phytoplankton growth. In addition, we used combined additions of nitrate and ammonium to understand the inhibitory effect of ammonium over nitrate uptake. Ammonium concentrations in the freshwater tidal reaches of the Guadiana estuary throughout the sampling period were too low to exert an inhibitory effect on nitrate uptake or a toxic effect on phytoplankton growth. Nitrate was clearly the main nitrogen source for phytoplankton at the study site. Overall, nitrate seemed to become limiting at concentrations lower than 20 μM and N-limitation was particularly significant during summer. A trend of decreasing nitrate uptake with increasing ammonium concentrations and uptake suggested an overall preference for ammonium. However, preference for ammonium was group-specific, and it was observed mainly in green algae and cyanobacteria. In fact, cyanobacteria relied only on ammonium as their N-source. On the contrary, diatoms preferred nitrate, and did not respond to ammonium additions. The increasing eutrophication in the Guadiana estuary and particularly increased inputs of nitrogen as ammonium due to urban waste effluents may result in a shift in phytoplankton community composition, towards a dominance of cyanobacteria and green algae.  相似文献   

GSD‐1G and MPI‐DING Reference Glasses for In Situ and Bulk Isotopic Determination     

Klaus Peter Jochum  Steven A. Wilson  Wafa Abouchami  Marghaleray Amini  Jérome Chmeleff  Anton Eisenhauer  Ernst Hegner  Linda M. Iaccheri  Bruno Kieffer  Joachim Krause  William F. McDonough  Regina Mertz‐Kraus  Ingrid Raczek  Roberta L. Rudnick  Denis Scholz  Grit Steinhoefel  Brigitte Stoll  Andreas Stracke  Sonia Tonarini  Dominique Weis  Ulrike Weis  Jon D. Woodhead 《Geostandards and Geoanalytical Research》2011,35(2):193-226

This paper contains the results of an extensive isotopic study of United States Geological Survey GSD‐1G and MPI‐DING reference glasses. Thirteen different laboratories were involved using high‐precision bulk (TIMS, MC‐ICP‐MS) and microanalytical (LA‐MC‐ICP‐MS, LA‐ICP‐MS) techniques. Detailed studies were performed to demonstrate the large‐scale and small‐scale homogeneity of the reference glasses. Together with previously published isotopic data from ten other laboratories, preliminary reference and information values as well as their uncertainties at the 95% confidence level were determined for H, O, Li, B, Si, Ca, Sr, Nd, Hf, Pb, Th and U isotopes using the recommendations of the International Association of Geoanalysts for certification of reference materials. Our results indicate that GSD‐1G and the MPI‐DING glasses are suitable reference materials for microanalytical and bulk analytical purposes.  相似文献   

Assessing food web dynamics and relative importance of organic matter sources for fish species in two Portuguese estuaries: a stable isotope approach     

França S  Vasconcelos RP  Tanner S  Máguas C  Costa MJ  Cabral HN 《Marine environmental research》2011,72(4):204-215

Stable carbon and nitrogen isotopes (δ13C, δ1?N) were used to analyse food web dynamics of two of the main estuaries of the Portuguese coast: Tejo and Mira. The ultimate sources of organic matter supporting production of some of the most abundant and commercially important fish species were determined; and seasonal, inter- and intra- estuarine differences in the trophic relations among producers and consumers were identified. Stable isotope analysis was performed in different producers, primary consumers (main prey items for fish) and fish species (Solea solea, Solea senegalensis, Pomatoschistus microps, Dicentrarchus labrax, Liza ramada, Diplodus vulgaris and Atherina presbyter) of two areas in each estuary, in July and October 2009. Model calculations showed that the main prey for the fish species in the Tejo estuary used mostly salt marsh-derived organic matter as nutritional sources, with no marked differences between the sampled months. Trophic levels of fish species from the same estuary differed at multiple scales: inter-species, seasonally and spatially (both between and within estuaries). Significant differences in isotopic composition of fish species were more pronounced spatially (between the two sampled areas in the estuary) than seasonally (between sampled months). Trophic relationships in both estuaries demonstrated that organic matter is transferred to higher trophic positions mainly through benthic pathways. This shows the flexibility of these species to share resources and to exploit temporary peaks in prey populations. The present results showed that extensive disturbance in intertidal habitats from both estuaries may potentially change the balance of organic matter in the base of these complex food webs.  相似文献   

Light as a driver of phytoplankton growth and production in the freshwater tidal zone of a turbid estuary   总被引：2，自引：0，他引：2  

Rita B. Domingues  Tnia P. Anselmo  Ana B. Barbosa  Ulrich Sommer  Helena M. Galvo 《Estuarine, Coastal and Shelf Science》2011,91(4):282

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Synthetic Spectra for Carbon Stars from Dynamica Model Atmospheres     

Rita Loidl  Josef Hron  Bernhard Aringer  Susanne Höfner  Uffe G. Jφrgensen 《Astrophysics and Space Science》1997,255(1-2):289-290

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Dust Features of Visually Bright AGB Variables as Seen by ISO and IRAS     

Josef Hron  Rita Loidl  Franz Kerschbaum 《Astrophysics and Space Science》1997,251(1-2):211-214

ISO-SWS spectra of two Mira variables (R Cas and T Dra), taken at two different pulsational phases, are presented. We describe the reduction of the data and the encountered problems. The dust features observed by ISO at different phases and with the Low Resolution Spectrometer of IRAS are compared. We briefly discuss the results in terms of current models for the circumstellar dust shells of AGB variables. This revised version was published online in September 2006 with corrections to the Cover Date.  相似文献