Advancing the Understanding of Sociospatial Dependencies in Terrorist Networks     

Richard M. Medina  George F. Hepner 《Transactions in GIS》2011,15(5):577-597

Terrorist networks operate in hybrid space where activities in social and geographic spaces are necessary for logistics and security. The Islamist terrorist network is analyzed as a sociospatial system using social network analysis, Geographic Information Science (GISc), and novel techniques designed for hybrid space analyses. This research focuses on identifying distance and sociospatial dependencies within the terrorist network. A methodology for analyzing sociospatial systems is developed and results lead to a greater understanding of terrorist network structures and activities. Distance and sociospatial dependencies are shown to exist for the Islamist terrorist network structure. These findings are discordant with recent literature that focuses on terrorist network tendencies toward decentralization in the information age. In this research, the Islamist terrorist network is theorized to use multiple structures of hierarchical and decentralized organization for effectiveness, efficiency, and resilience. Implications for counterterrorism policy and strategies are given.  相似文献   

Updating the Phase 1 habitat map of Wales, UK, using satellite sensor data     

Richard Lucas  Katie MedcalfAlan Brown  Peter BuntingJohanna Breyer  Dan Clewley  Steve KeyworthPhilippa Blackmore 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(1):81-102

The Phase 1 Survey is the most comprehensive and widely used national level map of semi-natural habitats in Wales. However, the survey was based largely on field survey and was conducted over several decades, before being completed in 1997. Given that resources for a repeat survey were limited, this study has used an object-orientated rule-based classification implemented within eCognition of multi-temporal satellite sensor data acquired between 2003 and 2006 to map semi-natural habitats and agricultural land across Wales, thereby allowing a progressive update of the Phase 1 Survey. The classification of objects to Phase 1 habitat classes was undertaken in two steps; firstly the landscape of Wales was divided into objects using orthorectified SPOT-5 High Resolution Geometric (HRG) reflectance data (10 m spatial resolution) and Land Parcel Information System (LPIS) boundaries. A rule-base was then developed to progressively discriminate and map the distribution of 105 sub-habitats across Wales based on time-series of SPOT HRG, Terra-1 Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Indian Remote Sensing Satellite (IRS) LISS-3 data, derived datasets (e.g., vegetation indices, fractional images) and ancillary information (e.g., topography). The rules coupled knowledge of ecology and the information content of these remote sensing data using a combination of thresholds, Boolean operations and fuzzy membership functions. A second rule-base was then developed to translate the more detailed sub-habitat classification to Phase 1 habitat classes. Indicative accuracies of the revised Phase 1 mapping, based on comparisons with the later Phase 2 survey (for selected habitats), were >80% overall and typically between 70% and 90% for many classes. Through this exercise, Wales has become the first country in Europe to produce a national map of habitats (as opposed to land cover) through object-orientated classification of satellite sensor data. Furthermore, the approach can be adapted to allow continual monitoring of the extent and condition of habitats and agricultural land.  相似文献   

Climate change links fate of glaciers and an endemic alpine invertebrate     

Clint C. Muhlfeld  J. Joseph Giersch  F. Richard Hauer  Gregory T. Pederson  Gordon Luikart  Douglas P. Peterson  Christopher C. Downs  Daniel B. Fagre 《Climatic change》2011,106(2):337-345

Climate warming in the mid- to high-latitudes and high-elevation mountainous regions is occurring more rapidly than anywhere else on Earth, causing extensive loss of glaciers and snowpack. However, little is known about the effects of climate change on alpine stream biota, especially invertebrates. Here, we show a strong linkage between regional climate change and the fundamental niche of a rare aquatic invertebrate—the meltwater stonefly Lednia tumana—endemic to Waterton-Glacier International Peace Park, Canada and USA. L. tumana has been petitioned for listing under the U.S. Endangered Species Act due to climate-change-induced glacier loss, yet little is known on specifically how climate impacts may threaten this rare species and many other enigmatic alpine aquatic species worldwide. During 14 years of research, we documented that L. tumana inhabits a narrow distribution, restricted to short sections (~500 m) of cold, alpine streams directly below glaciers, permanent snowfields, and springs. Our simulation models suggest that climate change threatens the potential future distribution of these sensitive habitats and the persistence of L. tumana through the loss of glaciers and snowfields. Mountaintop aquatic invertebrates are ideal early warning indicators of climate warming in mountain ecosystems. Research on alpine invertebrates is urgently needed to avoid extinctions and ecosystem change.  相似文献   

Estimation of the economic impact of temperature changes induced by a shutdown of the thermohaline circulation: an application of <Emphasis Type="Italic">FUND</Emphasis>     

P. Michael Link  Richard S. J. Tol

《Climatic change》2011,104(2):287-304

The integrated assessment model FUND 2.8n is applied in an assessment to estimate the magnitude of the general market and non-market impacts of temperature changes caused by a possible shutdown of the thermohaline circulation (THC). The monetized impacts of this change in environmental conditions are determined for 207 individual countries for two scenarios: one warming scenario in which the THC weakens but remains intact, and another in which the THC breaks down. Eight different response patterns are identified. The dominant pattern is that a THC shutdown has an offsetting effect on the underlying warming trend. Depending on whether the impacts of warming are initially beneficial or detrimental, the economic effects of a THC shutdown show distinct regional variability. Key economic sectors affected are water resources and energy consumption, as well as cardiovascular and respiratory diseases among health impacts. The maximum national impact of a shutdown of the THC turns out to be of the magnitude of a few per cent of GDP, but the average global impact is much smaller. The results indicate that the temperature effect of a THC shutdown does not create an insurmountable economic threat on a global scale, but may cause severe damages to individual countries. However, a consideration of other climatic impacts such as precipitation and sea level changes is likely to alter the identified trends in economic development.  相似文献   

Turbulent Transfer Between Street Canyons and the Overlying Atmospheric Boundary Layer   总被引：1，自引：1，他引：0  

Pietro Salizzoni  Massimo Marro  Lionel Soulhac  Nathalie Grosjean  Richard J. Perkins 《Boundary-Layer Meteorology》2011,141(3):393-414

The turbulent exchange of momentum between a two-dimensional cavity and the overlying boundary layer has been studied experimentally, using hot-wire anemometry and particle image velocimetry (PIV). Conditions within the boundary layer were varied by changing the width of the canyons upstream of the test canyon, whilst maintaining the square geometry of the test canyon. The results show that turbulent transfer is due to the coupling between the instabilities generated in the shear layer above the canyons and the turbulent structures in the oncoming boundary layer. As a result, there is no single, unique velocity scale that correctly characterizes all the processes involved in the turbulent exchange of momentum across the boundary layer. Similarly, there is no single velocity scale that can characterize the different properties of the turbulent flow within the canyon, which depends strongly on the way in which turbulence from the outer flow is entrained into the cavity and carried round by the mean flow. The results from this study will be useful in developing simple parametrizations for momentum exchange in the urban canopy, in situations where the street geometry consists principally of relatively long, uniform streets arranged in grid-like patterns; they are unlikely to be applicable to sparse geometries composed of isolated three-dimensional obstacles.  相似文献   

How much should the public know about climate science?     

Richard C. J. Somerville 《Climatic change》2011,104(3-4):509-514

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Identifying extreme hottest days from large scale upper air data: a pilot scheme to find California Central Valley summertime maximum surface temperatures   总被引：1，自引：0，他引：1  

Richard Grotjahn 《Climate Dynamics》2011,37(3-4):587-604

A pilot scheme uses upper air data from a few extreme hottest days to identify those and other extreme hottest days measured by 3 stations sampling the California Central Valley (CV). Prior work showed that CV extreme heat wave onsets have characteristic large scale patterns in many upper-air variables; those patterns also occur for the hottest days. A pilot scheme uses areas of two upper-air variables with high significance and consistency to forecast extreme surface temperatures. The scheme projects key parts of composite patterns for one or more variables onto daily weather maps of the corresponding variables resulting in a ??circulation index?? for each day. The circulation index measures how similar the pattern on that day is to the composite patterns in areas dynamically relevant to a CV extremely hot day, with a larger value for a stronger match and larger amplitude. The scheme is tested on the development period (1979?C1988) and on the subsequent 18?year ??independent?? period (1989?C2006). The pilot scheme captures about half of the rare events in the development period, with similar skill for the independent period. Based only on 16?days of extreme heat in the first 10?years, the scheme is not intended to represent the general distribution; however the circulation index has similar kurtosis, variance, and skewness as the observed maximum temperatures. Properties of the high end tail of the distribution are notably improved by adding the second predictor. The scheme outperforms simply using 850?hPa temperature above the CV.  相似文献   

Quantifying internal variability in a regional climate model: a case study for Southern Africa     

Julien Cr��tat  Cl��mence Macron  Benjamin Pohl  Yves Richard 《Climate Dynamics》2011,37(7-8):1335-1356

This study aims at presenting various methodologies to separate the reproducible and irreproducible components of seasonal and intraseasonal climate variability simulated by a regional climate model over Southern Africa (south of 15°S), during an austral summer rainy season representative of the climatology. To that end, a 30-member ensemble simulation is performed using WRF laterally forced by the ERA40 reanalyses. Retained metrics include the analysis of weather regimes, signal-to-noise ratio, inter-member standard deviation and coefficient of variation. At the seasonal timescale, simulated rainfall amounts generally show a strong reproducibility, except in the subtropics and over the southern part of the Mozambique Channel. There, the number of rainy days is roughly similar in all members, while their average intensity varies extensively. At the intraseasonal timescale, the chronology of weather regimes, derived from the 500?hPa geopotential height, is highly reproducible. Rainfall variability is much less reproducible, especially in the central parts of the domain and near its outflow boundaries. Analysis of a South African regional index nonetheless indicates that both wet and dry spells tend to be accurately simulated and occur in phase in most members, demonstrating that they are embedded in large-scale variability patterns. Internal variability is lastly related to the lateral forcings along the domain boundaries. An objective classification of inflow/outflow mass fluxes allows identification of the recurrent synoptic configurations that favor strong or weak regional reproducibility. The main uncertainties concern the basic morphological features of rain-bearing systems (i.e., their spatial extension, location and propagation speed). Consequences for tropical-temperate interactions are then discussed.  相似文献   

Assessing the effectiveness of non-structural flood management measures in the Thames Estuary under conditions of socio-economic and environmental change   总被引：1，自引：0，他引：1  

Richard J. Dawson  Tom Ball 《Global Environmental Change》2011,21(2):628-646

Risk analysis and appraisal of the benefits of structural flood risk management measures such as embankments is well established. Here, a method to quantify, over extended timescales, the effectiveness of non-structural measures such as land use spatial planning, insurance and flood resilient construction is presented. The integrated approach couples socio-economic and climate change scenarios with long term land use modelling and flood risk analysis to generate maps and time series of expected annual damages. The analysis has been applied on a case study in the Thames Estuary in the UK. Stakeholders helped develop a number of scenarios that might lead to substantial changes in existing planning and insurance policies in the UK. The effectiveness of these changes was analysed and showed the substantial benefits in terms of reduction of future flood risks that are achievable with changes in planning policy, financial incentives and resilient property construction in the floodplain. Moreover, the reward can be increased through earlier action. Subsequently, the benefits of a range of policies are explored under the UK Foresight socio-economic scenarios. Different structural and non structural flood management interventions are tested and the results demonstrate that despite the potential for large increases in flood risk in the Thames Estuary, in all scenarios substantial flood risk reductions are possible. The effectiveness of non-structural measures is however sensitive to socio-economic changes and governance arrangements. The analysis described here will help to identify portfolios of non-structural and structural options that are robust to uncertainties.  相似文献   

Major human Hepatitis A virus genotype in Hong Kong marine waters and detection by real-time PCR     

Yang N  Chu DL  Wong MM  Qi H  Wu RS  Kong RY 《Marine pollution bulletin》2011,62(12):2654-2658

Marine waters from seven sites around Hong Kong with varying levels of sewage pollution were analyzed for Hepatitis A virus (HAV) by PCR cloning and DNA sequencing of the highly variable VP1/2A junction of the HAV genome. Phylogenetic analysis of 10 PCR clones from each of the HAV-positive marine sites indicated that human HAV genotype IB is the most widely distributed type in Hong Kong waters. A sensitive and quantitative TaqMan-based PCR method targeting the 5′-noncoding region (5′-NCR) of HAV was used to quantify HAV particles in marine water samples along with the total Escherichiacoli counts being enumerated on TBX medium for comparison. Our results showed that no correlation of any significance between HAV and E. coli counts was observed which underscores the inadequacy in using E. coli as a sanitary standard to predict the levels of HAV in marine waters.  相似文献