Monogenetic volcanoes fed by interconnected dikes and sills in the Hopi Buttes volcanic field,Navajo Nation,USA     

James D. Muirhead  Alexa R. Van Eaton  Giuseppe Re  James D. L. White  Michael H. Ort 《Bulletin of Volcanology》2016,78(2):11

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Does geographic location impact the survival differential between screen- and interval-detected breast cancers?     

Jeff Ching-Fu Hsieh  Susanna M. Cramb  James M. McGree  Nathan A. M. Dunn  Peter D. Baade  Kerrie L. Mengersen 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(1):155-165

Although mammography screening programs aim to diagnose breast cancer at an early stage, not all tumours are detected during the regular screening examination. This study examines the influence of various characteristics, including geographical residence, on the survival between screen- and interval-detected breast cancers among participants of a public population-based breast screening program in Queensland, Australia. The investigation was performed using the linked population-based datasets from BreastScreen Queensland and the Queensland Cancer Registry for the period of 1997–2008 for women aged 40–89 years at diagnosis. A Bayesian spatial relative survival modelling approach that accommodates rare outcomes in small geographic regions was adopted, with the use of Markov chain Monte Carlo computation, to evaluate the relative excess risk of breast cancer. In the multivariate Bayesian spatial model, higher relative excess risk of mortality was observed in interval-detected cancer (RER = 1.59, 95 % credible interval = [1.33, 1.89]) compared to screen-detected cancer. Higher cancer survival among the study cohort was also observed among younger women (40–59 years), those of non-Indigenous ethnicity, with localised (stage I) tumour stage as well as those not in the work force. There was no independent association with marital status. Moreover, there was no substantive evidence of either measured geographical or latent random spatial inequalities in survival among screening participants across Queensland, meaning the higher survival for screen-detected breast cancer patients compared to interval-detected women was consistent across the state. These results provide suggestive evidence supporting the effectiveness of the BreastScreen Queensland screening program in reaching socio-economically disadvantaged women as well as those living in rural and remote areas of the state, but also highlights the need for any interval cancer awareness programs to be geographically widespread.  相似文献   

Temporal and Spatial Dynamics of Diel-Cycling Hypoxia in Estuarine Tributaries     

Robin M. Tyler  Damian C. Brady  Timothy E. Targett 《Estuaries and Coasts》2009,32(1):123-145

The distribution and intensity of hypoxia (low dissolved oxygen) in estuaries is increasing worldwide due to cultural eutrophication. This study quantifies the strength of associations between the duration of diel-cycling severe hypoxia (≤2 mg O₂ l⁻¹) in bottom water (∼15 cm above bottom) of a shallow (<2 m) coastal lagoon estuary (Delaware, USA) and abiotic environmental variables (water temperature, insolation, tide, streamflow, and wind) and predicts the duration of severe hypoxia given different combinations of these variables. The intensity and spatial extent and dynamics of diel-cycling severe hypoxia events were defined. Vertical variability in dissolved oxygen (DO) concentration during the daytime was also determined. During the summers of 2001–2005, bottom DO data were collected for periods of weeks to months at multiple sites using automated sondes. Multiple linear regression (MLR) and regression tree analysis (RTA) were used to determine the relative importance of the environmental variables in predicting the number of hours of severe hypoxia per day. Key findings of the study were that severe hypoxia events of minutes to hours in duration occurred frequently in all four tributaries sampled, primarily between 0200 and 1000 hours. Severe hypoxia duration and diel-cycling amplitudes of DO concentration increased in the up-tributary direction. Hierarchically, the duration of severe hypoxia was influenced mostly by the mean daily water temperature, then by preceding days’ total insolation, percentage of morning hours (02:00 to 10:00 a.m.) ebb tide, and daily streamflow. Collectively, the variables examined by the MLR and the RTA approaches accounted for 62% and 65% of the variability in the duration of severe hypoxia, respectively. RTA demonstrated that daily mean water temperature above 26.3°C and previous day’s total insolation below 13.6 kW m⁻² were associated with the longest lasting severe hypoxic events (9.56 h). The environmental variables and combinations of conditions that modulate or augment diel-cycling hypoxia presented in this paper enhance understanding of this widespread and growing phenomenon and provide additional insight regarding the extent to which it can impact food webs in very shallow estuarine waters that often serve as nursery habitat.  相似文献   

Comparison of the Salinity Structure of the Chesapeake Bay,the Delaware Bay and Long Island Sound Using a Linearly Tapered Advection-Dispersion Model   总被引：1，自引：0，他引：1  

Peter Gay  James O’Donnell 《Estuaries and Coasts》2009,32(1):68-87

Long records of monthly salinity observations along the axis of Chesapeake Bay, Delaware Bay, and Long Island Sound are used to test a simple advection–dispersion model of the salt distribution in linearly tapered estuaries developed in a previous paper. We subdivide each estuary into three to five segments, each with linear taper allowing a distributed input of fresh water, and evaluate the dispersion in each segment. While Delaware Bay has weak dispersion and a classical sigmoidal salinity structure, Long Island Sound and Chesapeake Bay are more dispersive and have relatively small gradients in the central stretches. Long Island Sound is distinguished by having a net volume and salt flux out of its low-salinity end resulting in a smaller range of salinity and increasing axial gradients at its head rather than the usual asymptotic approach to zero salinity. Estimates of residence times based on model transport coefficients show that Long Island Sound has the most rapid response to fresh-water flux variations. It also has the largest amplitude cycle in river discharge fluctuation. In combination, these cause the large seasonal variation in the salinity structure relative to interannual variability in Long Island Sound as compared with Chesapeake Bay and Delaware Bay.  相似文献   

Stable Isotopes Reveal Complex Changes in Trophic Relationships Following Nutrient Addition in a Coastal Marine Ecosystem   总被引：1，自引：0，他引：1  

Anna R. Armitage  James W. Fourqurean 《Estuaries and Coasts》2009,32(6):1152-1164

Complex links between the top-down and bottom-up forces that structure communities can be disrupted by anthropogenic alterations of natural habitats. We used relative abundance and stable isotopes to examine changes in epifaunal food webs in seagrass (Thalassia testudinum) beds following 6 months of experimental nutrient addition at two sites in Florida Bay (USA) with different ambient fertility. At a eutrophic site, nutrient addition did not strongly affect food web structure, but at a nutrient-poor site, enrichment increased the abundances of crustacean epiphyte grazers, and the diets of these grazers became more varied. Benthic grazers did not change in abundance but shifted their diet away from green macroalgae + associated epiphytes and towards an opportunistic seagrass (Halodule wrightii) that occurred only in nutrient addition treatments. Benthic predators did not change in abundance, but their diets were more varied in enriched plots. Food chain length was short and unaffected by site or nutrient treatment, but increased food web complexity in enriched plots was suggested by increasingly mixed diets. Strong bottom-up modifications of food web structure in the nutrient-limited site and the limited top-down influences of grazers on seagrass epiphyte biomass suggest that, in this system, the bottom-up role of nutrient enrichment can have substantial impacts on community structure, trophic relationships, and, ultimately, the productivity values of the ecosystem.  相似文献   

Conodont biostratigraphy across the Permian–Triassic boundary at the Dawen section, Great Bank of Guizhou, Guizhou Province, South China: Implications for the Late Permian extinction and correlation with Meishan     

Jun Chen  Tyler W. Beatty  Charles M. Henderson  Harry Rowe   《Journal of Asian Earth Sciences》2009,36(6):442

Several continuous Permian–Triassic boundary (PTB) sections are well exposed in the interior of the Great Bank of Guizhou (GBG) on the east limb of the Bianyang syncline, Luodian County, Guizhou Province, South China. Fourteen conodont taxa are identified, including Clarkina kazi, Clarkina lehrmanni n. sp., Clarkina taylorae, Clarkina zhejiangensis, Hindeodus eurypyge, Hindeodus inflatus, Hindeodus sxlatidentatus, Hindeodus parvus erectus, Hindeodus parvus parvus, Hindeodus postparvus, Hindeodus praeparvus, Hindeodus typicalis, Isarcicella staeschei, and Merrillina ultima based on a detailed study of the Permian-Triassic interval at the Dawen section. The first occurrence (FO) of H. parvus parvus in the lower Daye Formation, at about 7.45 m above the contact surface between the Upper Permian skeletal packstone and a calcimicrobial framestone unit, is correlated with the Permian–Triassic boundary; the occurrence of H. eurypyge, H. praeparvus and M. ultima immediately below and H. postparvus above the interval supports this interpretation. A morphometric analysis of 31 Hindeodus specimens helped distinguish H. parvus erectus from H. parvus parvus and H. postparvus. Correlation with the Meishan section (PTB GSSP) using both conodont biostratigraphy and carbon isotopes, indicates that the major extinction at the two localities is simultaneous and coincides with the top of the skeletal packstone at Dawen. The contact between the skeletal packstone and the calcimicrobialite is very irregular and has previously been interpreted as a dissolution surface and correlated with a surface in the lower part of bed 27 at Meishan. Our results confirm this interpretation and reveal that the dissolution event postdated the extinction.  相似文献   

Detecting groundwater contamination of a river in Georgia, USA using baseflow sampling     

James S. Reichard  Chandra M. Brown 《Hydrogeology Journal》2009,17(3):735-747

Algal blooms and fish kills were reported on a river in coastal Georgia (USA) downstream of a poultry-processing plant, prompting officials to conclude the problems resulted from overland flow associated with over-application of wastewater at the plant’s land application system (LAS). An investigation was undertaken to test the hypothesis that contaminated groundwater was also playing a significant role. Weekly samples were collected over a 12-month period along an 18 km reach of the river and key tributaries. Results showed elevated nitrogen concentrations in tributaries draining the plant and a tenfold increase in nitrate in the river between the tributary inputs. Because ammonia concentrations were low in this reach, it was concluded that nitrate was entering via groundwater discharge. Data from detailed river sampling and direct groundwater samples from springs and boreholes were used to isolate the entry point of the contaminant plume. Analysis showed two separate plumes, one associated with the plant’s unlined wastewater lagoon and another with its LAS spray fields. The continuous discharge of contaminated groundwater during summer low-flow conditions was found to have a more profound impact on river-water quality than periodic inputs by overland flow and tributary runoff.  相似文献   

Cartographic Constructs: A Case Study of Nantucket Island Oral Histories     

James J. Biles 《The Professional geographer》2013,65(4):541-555

The widespread adoption of neoliberal reforms during the past quarter century has had profound implications for the livelihoods of those who live and work in cities throughout Latin America. This case study of Mérida, Mexico, builds directly on recent research about the changing nature of work and the role of informality as a livelihood strategy in Latin America and attempts to explain how place-specific patterns of informal work emerge from neoliberal reforms and concomitant urban economic restructuring. Drawing on field research and a large household survey, this article reveals that general patterns of informality coincide with previous findings from Latin America: high levels of informal work; increased heterogeneity of informality; and significant mobility, with a large share of workers “opting out” of the formal sector voluntarily. However, compared with previous research in Mexico, this study shows that informal work is significantly more pervasive, particularly among women; less likely to be voluntary; and pays considerably less. In light of gender considerations and significant discrepancies between local patterns of informality and national trends, this case study casts doubt on recent World Bank encyclicals affirming the resemblance between self-employment in Mexico and microentrepreneurship in more developed countries. Moreover, the article concludes that World Bank literature conveniently overlooks the gendered nature of informal work in Latin America and the profound divergence between the express purposes of neoliberalism and its actual implications. As a result, World Bank research on informality serves to justify the neoliberal model, rather than improve the livelihoods of those who live and work in cities throughout Latin America.  相似文献   

Boundaries Make a Difference: The Effects of Spatial and Temporal Parameters on Conservation Planning*     

Patrick R. Huber  Steven E. Greco  James H. Thorne 《The Professional geographer》2013,65(3):409-425

Conservation planning and resulting ecological target identification require selection of both a planning area boundary and temporal baseline or reference condition. We examined the effects that these selections can have on resulting amount and location of identified conservation targets. A gap analysis for California was conducted using five different sets of ecoregion boundaries to identify and compare existing conservation shortfalls in major land cover type representation in protected areas using a threshold of 30 percent per ecoregion per type as the minimum required for future ecological viability. Another gap analysis was run for a single ecoregion using two temporal baselines (current and pre-1900) for the land cover followed by a comparison of identified conservation needs. We found that the boundaries of different ecoregional schemes affected both the total area needed to meet the per ecoregion land cover conservation goals and the spatial location of underprotected land cover types. Choice of temporal baseline also had a significant effect on the establishment of conservation targets for the highly human-impacted Central Valley ecoregion. To meet the given conservation threshold using a historic rather than contemporary baseline, a substantial amount of restoration is required. The results can help identify areas of both conservation needs consensus and those that vary widely based on the chosen planning boundary, as well as aid in the selection of appropriate restoration targets in degraded ecosystems. Because all landscapes are continuous in nature and planning area boundaries are discrete, similar results are likely to be found in analyses conducted in other regions.  相似文献   

A Review of “Hurricanes of the Gulf of Mexico”     

James B. Elsner 《The Professional geographer》2013,65(4):559-560

Books reviewed:

Bassin, Mark, Imperial Visions: Nationalist Imagination and Geographical Expansion in the Russian Far East, 1840 – 1865

Shortridge, James R., Our Town on the Plains: J. J. Pennell's Photographs of Junction City, Kansas, 1893 – 1922

Jakle, John A. and Sculle, Keith A., Fast Food: Roadside Restaurants in the Automobile Age

Boeschenstein, Walter, Historic American Towns along the Atlantic Coast

McKee, Jesse O., Ethnicity in Contemporary America: A Geographical Appraisal

Luciuk, Lubomyr Y., Searching for Place: Ukrainian Displaced Persons, Ottawa, and the Migration of Memory

Hausladen, Gary, Places for Dead Bodies

Phillips, Richard, Watt, Diane and Shuttleton, David, De-Centering Sexualities: Politics and Representations beyond the Metropolis

Goldin, Liliana R., Identities on the Move, Transnational Processes in North America and the Caribbean Basin

McDonald, David A., On Borders: Perspectives on International Migration in Southern Africa

Fox, Roddy and Rowntree, Kate, The Geography of South Africa in a Changing World

Takeuchi, Keiichi, Modern Japanese Geography: An Intellectual History

Amery, Hussein A., and Wolf, Aaron T., Water in the Middle East: A Geography of Peace

Karl, Thomas R., Nicholls, Neville and Ghazi, Anver, Weather and Climate Extremes: Changes, Variations, and a Perspective from the Insurance Industry

Pittman, Blair, Texas Caves  相似文献