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排序方式: 共有353条查询结果,搜索用时 312 毫秒
51.
Camila Soares Henrique Fontenele Garcia Maria do Rosário Maurício Ribeiro Macário Ezequiel Dantas de Araújo Girão Menezes Carlos Felipe Grangeiro Loureiro 《Networks and Spatial Economics》2018,18(2):415-439
Accessibility planning with reference to sustainability and equity principles has been advocated as the best approach to deal with the urban mobility complexity. It has enabled the development of more sustainable and fair policies in relation to access provision. However, despite this paradigm shift, many planning initiatives in practice are still focused on assessing alternatives and proposing solutions, instead of centering on the understanding and assessment of problems as the primary activity of planning. Therefore, in order to contribute for the problem-oriented paradigm in the accessibility planning, this work proposes a strategic assessment methodology for unequal and inequitable distribution problems of accessibility and mobility. This methodology relies on spatial analysis techniques and allows the characterization of accessibility and mobility conditions, as well as the diagnosis of accessibility and mobility problems and their causal relationships. It was applied for the case of Lisbon and the results of the performed assessment allowed an intelligent reading of the problems considered. Specifically, it was found that Lisbon presents an unequal and inequitable distribution of job accessibility and mobility by private car and public transport, and also that job accessibility, along with other transportation, land-use and socioeconomic variables, impact the mobility levels of its citizens. 相似文献
52.
Jorge E. Macías-Díaz 《Journal of scientific computing》2018,74(1):1-22
The partition of unity (PU) method, performed with local radial basis function (RBF) approximants, has been proved to be an effective tool for solving large scattered data interpolation problems. However, in order to achieve a good accuracy, the question about how many points we have to consider on each local subdomain, i.e. how large can be the local data sets, needs to be answered. Moreover, it is well-known that also the shape parameter affects the accuracy of the local RBF approximants and, as a consequence, of the PU interpolant. Thus here, both the shape parameter used to fit the local problems and the size of the associated linear systems are supposed to vary among the subdomains. They are selected by minimizing an a priori error estimate. As evident from extensive numerical experiments and applications provided in the paper, the proposed method turns out to be extremely accurate also when data with non-homogeneous density are considered. 相似文献
53.
The benzoxazolinones, specifically benzoxazolin-2(3H)-one (BOA), are important transformation products of the benzoxazinones that can serve as allelochemicals providing resistance
to maize from pathogenic bacteria, fungi, and insects. However, maize pathogens such as Fusarium verticillioides are capable of detoxifying the benzoxazolinones to 2-aminophenol (AP), which is converted to the less toxic N-(2-hydroxyphenyl) malonamic acid (HPMA) and 2-acetamidophenol (HPAA). As biocontrol strategies that utilize a species of
endophytic bacterium, Bacillus mojavensis, are considered efficacious as a control of this Fusarium species, the in vitro transformation and effects of BOA on growth of this bacterium was examined relative to its interaction with strains of F. verticillioides. The results showed that a red pigment was produced and accumulated only on BOA-amended media when wild type and the progeny
of genetic crosses of F. verticillioides are cultured in the presence of the bacterium. The pigment was identified as 2-amino-3H-phenoxazin-3-one (APO), which is a stable product. The results indicate that the bacterium interacts with the fungus preventing
the usual transformation of AP to the nontoxic HPMA, resulting in the accumulation of higher amounts of APO than when the
fungus is cultured alone. APO is highly toxic to F. verticillioides and other organisms. Thus, an enhanced biocontrol is suggested by this in vitro study. 相似文献
54.
Prats E Galindo JC Bazzalo ME León A Macías FA Rubiales D Jorrín JV 《Journal of chemical ecology》2007,33(12):2245-2253
In a previous study, we observed that bract and corolla extracts from a Sclerotinia sclerotiorum-resistant sunflower contained high amounts of the known coumarins scopoletin, scopolin, and ayapin. There was a correlation
between coumarin concentration and disease resistance. Thin layer chromatography showed higher concentrations of three other
compounds in the resistant genotype when compared to the susceptible. A bioassay-directed purification that used column chromatography
and HPLC allowed the isolation of a new compound, 3-acetyl-4-acetoxyacetophenone, and known compounds, demethoxyencecalin
and 3-acetyl-4-hydroxyacetophenone. Structures were assigned from spectral data, and bioactivities were characterized by in vitro bioassays against S. sclerotiorum. The new compound, 3-acetyl-4-acetoxyacetophenone, had an antifungal activity similar to the coumarin ayapin, previously
described as a potent Sclerotinia inhibitor. The speed and simplicity by which these compounds can be detected make them suitable for use in screening procedures
that may identify genotypes with valuable levels of resistance. A screening of seven sunflower genotypes in a field experiment
showed a correlation between these compounds and resistance to Sclerotinia. 相似文献
55.
A Esteban I Alía MJ Tobin A Gil F Gordo I Vallverdú L Blanch A Bonet A Vázquez R de Pablo A Torres MA de La Cal S Macías 《Canadian Metallurgical Quarterly》1999,159(2):512-518
The duration of spontaneous breathing trials before extubation has been set at 2 h in research studies, but the optimal duration is not known. We conducted a prospective, multicenter study involving 526 ventilator-supported patients considered ready for weaning, to compare clinical outcomes for trials of spontaneous breathing with target durations of 30 and 120 min. Of the 270 and 256 patients in the 30- and 120-min trial groups, respectively, 237 (87.8%) and 216 (84.8%), respectively, completed the trial without distress and were extubated (p = 0.32); 32 (13.5%) and 29 (13.4%), respectively, of these patients required reintubation within 48 h. The percentage of patients who remained extubated for 48 h after a spontaneous breathing trial did not differ in the 30- and 120-min trial groups (75.9% versus 73.0%, respectively, p = 0.43). The 30- and 120-min trial groups had similar within-unit mortality rates (13 and 9%, respectively) and in-hospital mortality rates (19 and 18%, respectively). Reintubation was required in 61 (13.5%) patients, and these patients had a higher mortality (20 of 61, 32.8%) than did patients who tolerated extubation (18 of 392, 4.6%) (p < 0.001). Neither measurements of respiratory frequency, heart rate, systolic blood pressure, and oxygen saturation during the trial, nor other functional measurements before the trial discriminated between patients who required reintubation from those who tolerated extubation. In conclusion, after a first trial of spontaneous breathing, successful extubation was achieved equally effectively with trials targeted to last 30 and 120 min. 相似文献
56.
This paper examines the spatial and temporal variability and trends of agricultural productivity in the Lower Mekong River
Basin. We also show the future productivity requirements for both food security and the maintenance of the basin’s export
potential at the current level for the projected increase in population by 2030. We considered both rice and upland crops
grown in the basin and estimated physical and economic productivity in terms of land and population. Both physical and economic
productivity of rice in terms of land area and population is highest in Vietnam, moderate in Laos and lowest in Thailand and
Cambodia. However, the physical productivity of upland crops such as sugarcane and maize is highest in Thailand. Economic
productivity of upland crops is highest in Laos followed by Vietnam, Cambodia and Thailand, respectively and is much higher
than that of rice. Total economic productivity is dominated by rice in all countries except Laos. In general, productivity
has increased in all four riparian countries between 1993 and 2004 and there appears to be considerable scope for further
increases, which will allow maintenance of the current level of rice export in the future, despite population growth.
相似文献
Mohammed MainuddinEmail: |
57.
Sizing and control of trailing edge flaps on a smart rotor for maximum power generation in low fatigue wind regimes 下载免费PDF全文
Jeroen Smit Lars O. Bernhammer Sachin T. Navalkar Leonardo Bergami Mac Gaunaa 《风能》2016,19(4):607-624
An extension of the spectrum of applicability of rotors with active aerodynamic devices is presented in this paper. Besides the classical purpose of load alleviation, a secondary objective is established: optimization of power capture. As a first step, wind speed regions that contribute little to fatigue damage have been identified. In these regions, the turbine energy output can be increased by deflecting the trailing edge (TE) flap in order to track the maximum power coefficient as a function of local, instantaneous speed ratios. For this purpose, the TE flap configuration for maximum power generation has been using blade element momentum theory. As a first step, the operation in non‐uniform wind field conditions was analysed. Firstly, the deterministic fluctuation in local tip speed ratio due to wind shear was evaluated. The second effect is associated with time delays in adapting the rotor speed to inflow fluctuations caused by atmospheric turbulence. The increase in power generation obtained by accounting for wind shear has been demonstrated with an increase in energy production of 1%. Finally, a control logic based on inflow wind speeds has been devised, and the potential of enhanced power generation has been shown by time‐domain simulations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
58.
Supermartensitic stainless steels (SMSSs) allow high mechanical strength with better corrosion resistance and toughness than conventional martensitic stainless steels. The SMSS steels with 12–13%Cr have been studied and applied in the oil and gas offshore production. The increase of Cr content, and the addition of Mo and W is now being investigated to increase mechanical and pitting corrosion resistance. In this work, a new 17%Cr steel, with Mo and W additions was studied. Depending on the final tempering treatment, the steel has a complex microstructure of austenite, ferrite, martensite and precipitates. The pitting corrosion resistance also depends on the microstructure produced by tempering. It was found that the pitting potential slightly decreases with the increase of tempering temperature and is further decreased by the double-tempering treatment. The pits initiate and grow preferentially in the martensite or tempered martensite islands, due to the lower Cr, Mo and W contents of these areas. 相似文献
59.
60.
Macé S Cornet J Chevalier F Cardinal M Pilet MF Dousset X Joffraud JJ 《Food microbiology》2012,30(1):164-172
In order to characterise the spoilage related to microbiota of raw salmon, a combination of culture-dependent and -independent methods, including PCR–TTGE, was used to analyse 3 raw salmon batches stored for 3 days at chilled temperature in modified atmosphere packaging (MAP) (50% CO2/50% N2) or under vacuum. Sensory evaluation, microbiological enumeration and chemical analysis were performed after 3, 7 and 10 days of storage. At the onset of spoilage, 65 bacterial isolates were picked from the plates. Thus, 13 different genera or species were identified by phenotypic and molecular tests: Serratia spp., Photobacterium phosphoreum, Yersinia intermedia, Hafnia alvei, Buttiauxella gaviniae, Pseudomonas sp., Carnobacterium maltaromaticum, Carnobacterium divergens, Lactococcus piscium, Lactobacillus fuchuensis, Vagococcus carniphilus, Leuconostoc gasicomitatum and Brochothrix thermosphacta. The PCR–TTGE profiles and band identification enabled a shift of the dominant populations during the storage to be visualised for all the batches, probably due to the temperature change and the packaging. At the beginning of storage, Pseudomonas sp. dominated the raw salmon microbiota while in the following days (7 and 10), P. phosphoreum and L. piscium were identified as the main bacterial groups. This study enhances the knowledge of MAP and vacuum-packed raw salmon spoilage microbiota. 相似文献