Submerged early Holocene coastal and terrestrial landforms on the inner shelves of Atlantic Canada     

John Shaw  Gordon B. Fader  Robert B. Taylor 《Quaternary International》2009,206(1-2):24

Coastal and terrestrial landforms that formed with lowered relative sea levels during the early postglacial period in Atlantic Canada were submerged during the Holocene transgression. However, these landforms are seldom seen on sea floor imagery. Factors that contribute to their destruction include the brevity of sea level lowstands and high wave energy on shallow modern shelves. We identify one situation within which preservation has been relatively good: large coastal lakes that existed for many thousands of years before being connected to the ocean by rising sea level in the mid-Holocene. We describe Bedford Basin, near Halifax, Nova Scotia, and deal more exhaustively with the Bras d'Or Lakes, an inland sea in Cape Breton, Nova Scotia. The preservation of shore platforms, barrier beaches and spits, and fluvial systems, was due to the rapid onset of the transgression and the relatively low wave energy in the subsequent marine phases. The well-preserved early Holocene coastlines are highly favourable targets in the search for evidence of human occupation in the early- to mid-Holocene.  相似文献   

Clustering of temporal event processes   总被引：1，自引：0，他引：1  

Tao Pei  Xi Gong  Shih-Lung Shaw  Ting Ma 《International journal of geographical information science》2013,27(3):484-510

A temporal point process is a sequence of points, each representing the occurrence time of an event. Each temporal point process is related to the behavior of an entity. As a result, clustering of temporal point processes can help differentiate between entities, thereby revealing patterns of behaviors. This study proposes a hierarchical cluster method for clustering temporal point processes based on the discrete Fréchet (DF) distance. The DF cluster method is divided into four steps: (1) constructing a DF similarity matrix between temporal point processes; (2) constructing a complete linkage hierarchical tree based on the DF similarity matrix; (3) clustering the point processes with a threshold determined by locating the local maxima on the curve of the pseudo-F statistic (an index which measures the separability between clusters and the compactness in clusters); and (4) identifying inner patterns for each cluster formed by a series of dense intervals, each of which contains at least one event of all processes of the cluster. The contributions of the article are: (1) the proposed DF cluster method can cluster temporal point processes into different groups and (2) more importantly, it can identify the inner pattern of each cluster. Two synthetic data sets were created to illustrate the DF distance between temporal point process clusters (the first data set) and validate the proposed DF cluster method (the second data set), respectively. An experiment and a comparison with a method based on dynamic time warping show that DF cluster successfully identifies the preconfigured patterns in the second synthetic data set. The cluster method was then applied to a population migration history data set for the Northern Plains of the United States, revealing some interesting population migration patterns.  相似文献   

A Voronoi neighborhood-based search heuristic for distance/capacity constrained very large vehicle routing problems     

Zhixiang Fang  Shih-Lung Shaw  Shunqing Chen  Bi Yu Chen 《International journal of geographical information science》2013,27(4):741-764

Local search heuristics for very large-scale vehicle routing problems (VRPs) have made remarkable advances in recent years. However, few local search heuristics have focused on the use of the spatial neighborhood in Voronoi diagrams to improve local searches. Based on the concept of a k-ring shaped Voronoi neighbor, we propose a Voronoi spatial neighborhood-based search heuristic and algorithm to solve very large-scale VRPs. In this algorithm, k-ring Voronoi neighbors of a customer are limited to building and updating local routings, and rearranging local routings with improper links. This algorithm was evaluated using four sets of benchmark tests for 200–8683 customers. Solutions were compared with specific examples in the literature, such as the one-depot VRP. This algorithm produced better solutions than some of the best-known benchmark VRP solutions and requires less computational time. The algorithm outperformed previous methods used to solve very large-scale, real-world distance constrained capacitated VRP.  相似文献   

Assessment of drought over the past two millennia using near-shore sediment cores from a Canadian boreal lake     

Heather A. Haig  Melanie V. Kingsbury  Kathleen R. Laird  Peter R. Leavitt  Robyn Laing  Brian F. Cumming 《Journal of Paleolimnology》2013,50(2):175-190

Lack of long-term studies on drought in the boreal region of northwest Ontario limits our ability to assess the vulnerability of this region to climate change. We investigated changes in diatoms, scaled chrysophytes, and sedimentary pigments in two near-shore cores from Gall Lake to infer limnological and water-level changes over the last two millennia. The two coring locations, at modern water depths of 7.5 and 11.5 m, were selected to contrast inferences for past lake level based on distance from the modern water-depth boundary between predominantly benthic and planktonic diatom assemblages in surface sediments (6.0 m). Diatom-inferred depth inferences were more variable in the core from 7.5-m water depth, consistent with the hypothesis that the greatest changes occurred at water depths closest to the benthic:planktonic boundary. Both sites revealed a pronounced drought from ~AD 950 to 1300, synchronous with the medieval climate anomaly (MCA). This finding suggests a northeast expansion of the arid MCA into northwest Ontario, extending the known spatial extent of this megadrought. Scaled chrysophytes and sedimentary pigments suggest a recent increase in thermal stratification. Our findings indicate this region is more susceptible to changes in moisture than was previously suspected based on the instrumental record for the past century.  相似文献   

What about people in pedestrian navigation?     

Zhixiang Fang  Qingquan Li  Shih-Lung Shaw 《地球空间信息科学学报》2013,16(4):135-150

Pedestrian navigation has become an important theoretical and practical research topic in many disciplines such as cartography, geographical information science, global and indoor positioning, spatial behavior, psychology, sociology, and neuroscience. Many research studies view pedestrian navigation using process-oriented and goal-directed approaches. However, this paper revisits people’s needs in pedestrian navigation and classifies their needs as three layers: physical sense layer, physiological safety layer, and mental satisfaction layer according to Maslow’s theory. This paper introduces a people-centric framework for pedestrian navigation theory based on these three layers and discusses theoretical challenges for meeting each layer of people’s needs. These challenging theories may represent promising and valuable research and promote usage of pedestrian navigation systems or devices in the future.  相似文献   

Lake ecosystem dynamics and links to climate change inferred from a stable isotope and organic palaeorecord from a mountain lake in southwestern China (ca. 22.6–10.5 cal ka BP)     

Charlotte G. Cook  Melanie J. Leng  Richard T. Jones  Peter G. Langdon  Enlou Zhang 《Quaternary Research》2012,77(1):132-137

A detailed understanding of long-term climatic and environmental change in southwestern China is hampered by a lack of long-term regional palaeorecords. Organic analysis (%TOC, %TN, C/N ratios and δ¹³C values) of a sediment sequence from Lake Shudu, Yunnan Province (ca. 22.6–10.5 cal ka BP) indicates generally low aquatic palaeoproductivity rates over millennial timescales in response to cold, dry climatic conditions. However, the record is punctuated by two marked phases of increased aquatic productivity from ca. 17.7 to 17.1 cal ka BP and from ca. 11.9 to 10.5 cal ka BP. We hypothesise that these shifts reflect a marked, stepwise lacustrine response to Asian summer monsoon strengthening during the last deglaciation.  相似文献   

Climate disaster resilience of the education sector in Thua Thien Hue Province, Central Vietnam   总被引：2，自引：2，他引：0  

Thi My Thi Tong  Rajib Shaw  Yukiko Takeuchi 《Natural Hazards》2012,63(2):685-709

Recognizing the importance of building disaster resilience for education sector, this study aims to develop a methodology to measure the level of educational resilience to cope with natural disasters and is then applied in Central Vietnam. The assessment tool in this paper is developed through a combination of climate disaster resilience indexes and the 16 tasks of Hyogo framework for action designed for education sector. It looks at five dimensions namely physical conditions, human resources, institutional issues, external relationships, and natural conditions, with each dimension characterized by three parameters and five variables. Findings from this study provide important insights into enhancing resilience of the education system in Thua Thien Hue at the provincial, local, and school levels. By giving the overall resilience situation, it can help policy-makers and practitioners in developing an effective plan to increase the level of educational resilience. In addition, it provides the School Management Board with a means to assess the school??s resilience level and set out priorities that need to be focused on with regard to the improvement of school safety and disaster risk reduction education.  相似文献   

Distribution, characterization, and geochemical controls of elements of concern in uranium mine tailings, Key Lake, Saskatchewan, Canada     

Sean A. Shaw  M. Jim Hendry  Joseph Essilfie-Dughan  Tom Kotzer  Dirk Wallschläger 《Applied Geochemistry》2011,26(12):2044-2056

The distribution of As, Mo, Ni and Se in the aqueous and solid phases of U mine tailings in the Deilmann Tailings Management Facility (DTMF), located at the Key Lake mine in northern Saskatchewan, Canada, was defined using as-discharged tailings samples collected monthly starting in 1996 and core samples collected from the DTMF from 3 locations on 3 occasions between 2004 and 2009. These data indicated that the DTMF can be divided into two geochemical zones; tailings generated from the Deilmann ore body between 1996 and 2000 and tailings from the McArthur River ore body, mined after July 2000. The Deilmann tailings solids are generally characterized by greater elemental concentrations than those in the McArthur River tailings, particularly for As, Co and Ni. These elevated concentrations are attributed to the abundance of Ni–Co–As–S minerals in this ore. The mean aqueous concentrations of As, Mo, Ni, and Se are 3.7, 23.2, 0.14, and 0.02 mg L⁻¹, respectively, in the Deilmann porewaters and 0.20, 4.16, 0.06, and 0.03 mg L⁻¹, respectively, in the McArthur River porewaters. Similarly, the mean As, Mo, Ni, and Se solid phase concentrations are 5.89 × 10³, 69.9, 3.20 × 10³, and 17.4 μg g⁻¹, respectively, for the Deilmann tailings and 440, 13.6, 551, and 3.03 μg g⁻¹ in the McArthur River tailings. Statistically, pH remained unchanged from the time of discharge while Eh values have remained oxic with no significant change between the two tailings types over 15 a of residence time. Results from sequential extractions, thermodynamic modeling, and results of complimentary research indicated that ferrihydrite solubility is the dominant control on aqueous As concentrations and also plays a role in controlling dissolved Mo, Ni and Se.  相似文献   

Integration of biochemical, histochemical and toxicogenomic indices for the assessment of health status of mussels from the Tamar Estuary, U.K     

Shaw JP  Dondero F  Moore MN  Negri A  Dagnino A  Readman JW  Lowe DR  Frickers PE  Beesley A  Thain JE  Viarengo A 《Marine environmental research》2011,72(1-2):13-24

The aim of this study was to examine whether a combination of biochemical, histopathological and toxicogenomic data could be used as a valuable tool for the assessment of biological risk associated with pollutants within the Tamar River and Estuary, S.W. England, U.K. Accordingly, biochemical and histopathological biomarkers (protein carbonyls, lipofuscin, neutral lipids, lysosomal stability [N-acetyl-β-hexosaminidase and neutral red], lysosomal volume, ferric reducing antioxidant power [FRAP] and malonaldehyde [MDA]) and gene expression profiles were assessed in 5 sites from the Tamar River and Estuary (Neal Point, Town Quay, Wilcove, Cremyll Ferry and Whitsand; and a reference site, Trebarwith Strand, N. Cornwall). PAHs were measured in mussel tissue and sediment and metals were measured in mussel tissue only. Data from the biomarkers was integrated into a Mussel Expert System (MES) model to produce a simple assessment of mussel stress. Clear gradients of mussel toxicity were identified by the biomarkers (with the exception of neutral lipids) with the highest impacted animals found furthest up the Tamar, whilst the MES was unable to identify a gradient of effect. Gene expression profiles also indicated a gradient of stress with the greatest number of significantly up- or down- regulated genes found at the uppermost 2 sites. The MES did, however, determine that mussels from all sites, except the reference site, were highly stressed; a conclusion that could not be inferred from the biomarker data alone. It is concluded that the MES is a valuable tool that permits integration and interpretation of complex sets of biomarker data by identifying the biological meaning of biomarker changes.  相似文献   

Role of women as risk communicators to enhance disaster resilience of Bandung,Indonesia     

Mulyasari  Farah  Shaw  Rajib 《Natural Hazards》2013,69(3):2137-2160

This study addresses the need for women risk communication and highlights the potential role of Women Welfare Associations (WWAs) of Bandung, Indonesia, as risk communicators. A risk communication framework is modeled for women’s risk communication process. A set of indicators in social, institutional, and economic resilience activities (SIERAs), with a scope of 45 activities covering three different disaster periods, were developed to characterize the delivery process of risk information by women in WWAs through their activities at sub-district and ward levels. The data were collected through a questionnaire survey method using the risk communication SIERA approach. Women’s leaders at wards were surveyed concerning their perceptions on these 45 scopes of SIERA, ongoing activities, and their risk information source and dissemination process. Correlation analysis was applied to determine the relationship between the variables such as periods of disaster, types of activities (social, institutional, economic), and attributing factors (location, population, and education institution) in finding variations in risk communication activity that functions for women and communities. Five risk communication processes of WWAs are identified and implemented that work for women in Bandung. When their perceptions and ongoing activities are compared, activities such as dissemination of disaster risk information, conveying early warnings to their peers, and involvement of the local government have been confirmed to match the risk communication plans and implementation of WWAs. These indicate that WWAs’ activities in Bandung implement a certain degree of risk communication that is embedded in their activities. The results confirm that women through their social networks can become active agents of change and thus act beyond their usual domestic roles and responsibilities in order to contribute to the overall enhancement of community resilience.

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