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141.
The study analyses the numbers of days with strong winds in Krakow during the period 2000?C2007 using anemometric records and fire department data. Patterns are identified in the seasonal and annual variation of strong winds. Particular attention is devoted to extreme events. Based on measurements, the study finds that strong winds mostly occurred in winter. Fire department call-out data show that repair of damage caused by strong winds and gusts of wind was needed equally as frequently in summertime. Strong winds accompanying summer storms are often of a local nature and are not always recorded by weather stations. Wind damage was mapped using requests for fire department assistance. 相似文献
142.
In St. Louis, as in many other cities, decline and displacement occurred when key policies, prejudices, and plans interacted with broad economic restructuring to devastate poor and minority communities, while leaving White and middle-class communities largely intact. Amidst overall population loss and neighborhood decline are pockets of prosperity and gentrification within the central city. In this article, we analyze three significant planning interventions in St. Louis, Missouri, that spurred displacement of populations—urban renewal, triage, and the foreclosure crisis. We argue that the differential experiences of Black and White during each of these periods represent two faces of development: one in the north of the city that is largely Black, experiencing vacant land, high crime, and crumbling infrastructure; another in the south of the city that is largely White, enjoying pockets of vibrant commercial development, larger homes, and stable real estate markets. We analyze each period through a framework of uneven and unequal development and displacement, which we call the Divergent City Theory. Based on this theory, planners face an ethical obligation to plan for the future of their cities in a way that seeks to reconcile the structured race and class inequalities of the divergent city. 相似文献
143.
Natural Hazards - Extreme risks associated with natural and man-made disasters involve disruptions to the production of goods or provision of services in interdependent systems. The reduced supply... 相似文献
144.
Dipanjan Mitra Joanna M. Rankin Yashwant Gupta 《Monthly notices of the Royal Astronomical Society》2007,379(3):932-944
In this paper we report multifrequency single-pulse polarization observations of the PSR B0329+54 normal mode using the Giant Metre-wave Radio Telescope at 325 and 610 MHz and the Effelsberg Observatory at 2695 MHz. Our observations show that towards the central part of the polarization position angle traverse there is an unusual 'arc'-like structure, which comprises a broad-band 'kink' and a frequency-dependent 'spot'. The features are intimately connected with the intensity dependence of the core component: the stronger emission arrives earlier and its linear polarization is displaced farther along the 'kink'. Moreover, at high intensities, the circular polarization is −/+ antisymmetric; the nearly complete positive circular is characteristic of the weaker, later core subpulses. We find that the 'kink' emission is associated with the extraordinary (X) propagation mode, and hence propagation effects do not appear to be capable of producing the core component's broad-band, intensity-dependent emission. Rather, the overall evidence points to a largely geometric interpretation in which the 'kink' provides a rare glimpse of the accelerating cascade or height-dependent amplifier responsible for the core radiation. 相似文献
145.
The periodicity of a river expressed in cycles of various lengths (monthly,seasonal,multiannual) is a result of climatic factors and overiapping environmental c... 相似文献
146.
Genetic differentiation of the soft shore barnacle Fistulobalanus albicostatus (Cirripedia: Thoracica: Balanomorpha) in the West Pacific 下载免费PDF全文
Yen Wei Chang Joanna S. M. Chan Ryota Hayashi Takuho Shuto Ling Ming Tsang Ka Hou Chu Benny K. K. Chan 《Marine Ecology》2017,38(2)
This study examined the phylogeography of the barnacle Fistulobalanus albicostatus, which inhabits mangroves and estuarine shores in the West Pacific. Differentiation in the mitochondrial cytochrome c oxidase subunit I (COI) and 12S ribosomal RNA (12S) genes of 401 specimens of F. albicostatus was examined in samples from 16 locations in the West Pacific, ranging from Honshu to Southern China. Our results revealed that F. albicostatus comprises two major clades exhibiting a COI divergence ranging from 1.25% to 2.8%. Clade A demonstrated the widest distribution, ranging from Japan to China, and was divided into three subclades occurring in the South China Sea (A1), Okinawa (A2), and Honshu, Korea and Qingdao (A3). Clade B was determined to be endemic to Okinawa; i.e. two endemic lineages occur in this island. Thus, F. albicostatus resembles several inter‐tidal species in having clades that are endemic to Okinawan waters. Nevertheless, in contrast to the rocky inter‐tidal barnacles Tetraclita spp. and Chthamalus malayensis, F. albicostatus was not found to be separated into continental and oceanic populations, but instead is divided into northern and southern clades, probably because of the Yangtze River discharge, which limits gene flow between the northern and southern populations. 相似文献
147.
Wintermyer M Skaidas A Roy A Yang YC Georgapoulos P Burger J Cooper K 《Marine environmental research》2005,60(2):133-152
A physiologically-based pharmacokinetic model (PBPK) was developed to describe the kinetics of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the eastern oyster (Crassostrea virginica). The estimated t(1/2) of elimination for a bolus dose of TCDD in C. virginica is approximately 14-24 days based on both the experimental data and the PBPK model. The highest dioxin concentration reached during 28-days was in the digestive gland followed by the mantle, gonad, hemolymph, gill, adductor muscle, and the kidney/heart. A binding protein for 2,3,7,8-TCDD had been reported in the literature for both the digestive gland and gonad. Incorporating a binding component in the model resulted in a better fit for the data. The PBPK model predicted the distribution and the elimination concentrations for 2,3,7,8-TCDD within each of the tissue compartments. This model will serve as a useful tool for predicting the kinetics of other persistent organic pollutants as well as, allow for a more refined ecological risk assessment by estimating dioxin concentrations in sensitive tissues such as the gonad. 相似文献
148.
Fast and reliable Markov chain Monte Carlo technique for cosmological parameter estimation 总被引:1,自引:0,他引:1
Joanna Dunkley Martin Bucher Pedro G. Ferreira Kavilan Moodley Constantinos Skordis 《Monthly notices of the Royal Astronomical Society》2005,356(3):925-936
Markov chain Monte Carlo (MCMC) techniques are now widely used for cosmological parameter estimation. Chains are generated to sample the posterior probability distribution obtained following the Bayesian approach. An important issue is how to optimize the efficiency of such sampling and how to diagnose whether a finite-length chain has adequately sampled the underlying posterior probability distribution. We show how the power spectrum of a single such finite chain may be used as a convergence diagnostic by means of a fitting function, and discuss strategies for optimizing the distribution for the proposed steps. The methods developed are applied to current cosmic microwave background and large-scale structure data interpreted using both a pure adiabatic cosmological model and a mixed adiabatic/isocurvature cosmological model including possible correlations between modes. For the latter application, because of the increased dimensionality and the presence of degeneracies, the need for tuning MCMC methods for maximum efficiency becomes particularly acute. 相似文献
149.
150.
Nicholas J. G. Pearce Joanna S. Denton William T. Perkins John A. Westgate Brent V. Alloway 《第四纪科学杂志》2007,22(7):721-736
Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) is a high spatial resolution analytical method which has been applied to the analysis of silicic tephras. With current instrumentation, around 30 trace elements can be determined from single glass shards as small as ~ 40 µm, separated from tephra deposits. As a result of element fractionation during the ablation process using a 266 nm laser, a relatively complex calibration strategy is required. Nonetheless, such a strategy gives analyses which are accurate (typically within ±5%) and have an analytical precision which varies from ~ ±2% at 100 ppm, to ~ ±15% at 1 ppm. Detection limits for elements used in correlation and discrimination studies are well below 1 ppm. Examples of the application of trace element analysis by LA‐ICP‐MS in tephra studies are presented from the USA, New Zealand and the Mediterranean. Improvements in instrumental sensitivity in recent years have the potential to lower detection limits and improve analytical precision, thus allowing the analysis of smaller glass shards from more distal tephras. Laser systems operating at shorter wavelengths (e.g. 193 nm) are now more widely available, and produce a much more controllable ablation in glasses than 266 nm lasers. Crater sizes of <10 µm are easily achieved, and at 193 nm many of the elemental fractionation issues which mar longer wavelengths are overcome. By coupling a short wavelength laser to a modern ICP‐MS it should be possible to determine the trace element composition of glass shards as small as 20 µm and, providing sample preparation issues can be overcome, the determination of the more abundant trace elements in glass shards as small as 10 µm is within instrumental capabilities. This will make it possible to chemically fingerprint tephra deposits which are far from their sources, and will greatly extend the range over which geochemical correlation of tephras can be undertaken. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献