Regional climate model projections of the South Pacific Convergence Zone     

J. P. Evans  K. Bormann  J. Katzfey  S. Dean  R. Arritt 《Climate Dynamics》2016,47(3-4):817-829

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Optimal Routefinding Across Landscapes Featuring High‐cost Linear Obstacles          下载免费PDF全文

Denis J. Dean  Vaishnavi Thakar  Neeraj Sirdeshmukh 《Transactions in GIS》2016,20(4):613-625

Existing GIS‐based least‐cost routefinding approaches can in some cases be confounded by linear features in the landscape whose crossing costs are high relative to other traversing costs found throughout the landscape. Unfortunately, such high‐cost linear features are not uncommon; they frequently occur in the form of hydrologic features whose crossing costs are high relative to costs of traversing the surrounding dry land. This study (1) enumerates the situations where existing approaches can fail, (2) proposes a simple method for overcoming the limitations of the existing approaches, and (3) conducts an experiment to assess the impact of the weaknesses of existing approaches and the magnitude of the differences between the results produced by existing and revised approaches. Our results show that in mountainous terrain, linear hydrologic features with high crossing costs can have a profound impact on least‐cost routes, and the choice of solution method has equally profound impacts on the optimal route produced by the analysis.  相似文献   

Mapping local regression for spatial object-pairs     

Jie Lin  Robert G. Cromley  Dean M. Hanink 《制图学和地理信息科学》2016,43(4):328-337

Local regression methods such as geographically weighted regression (GWR) can provide specific information about individual locations (or places) in spatial analysis that is useful for mapping nonstationary covariate relationships. However, the distance-based weighting schemes used in GWR are only adaptable for spatial objects that are point or area features. In particular, spatial object-pairs pose a challenge for local analysis because they have a linear dimensionality rather than a point dimensionality. This paper proposes using an alternative local regression model – quantile regression (QR) – for investigating the stationarity of regression parameters with respect to these linear features as well as facilitating the visualization of the results. An empirical example of a gravity model analysis of trade patterns within Europe is used to illustrate the utility of the proposed method.  相似文献   

Seasonal and regional patterns in egg production of Calanus glacialis/marshallae in the Chukchi and Beaufort Seas during spring and summer, 2002     

Stphane Plourde  Robert G. Campbell  Carin J. Ashjian  Dean A. Stockwell 《Deep Sea Research Part II: Topical Studies in Oceanography》2005,52(24-26):3411

Understanding the physical and biogeochemical processes that control the exchange of biogenic carbon within and between the arctic shelves, slopes, and deep basins is a key objective of the Western Arctic Shelf-Basin Interaction program (SBI). Here, egg production (EP) of the dominant copepod Calanus glacialis/marshallae was used as an indicator of food limitation for the mesozooplankton community in the Chukchi and Beaufort Seas in spring and summer, 2002. Both C. glacialis and C. marshallae may occur in this region but the two cannot easily be differentiated visually. Four oceanographic regions were objectively identified that roughly corresponded to the different pathways in circulation of nutrient-rich Pacific water. A ‘transition’ region characterized by ‘older’ Pacific water was located at the shelfbreak and separated the nutrient-rich shelf water and the low-nutrient waters of the deep basin. The observed spatial pattern in EP in C. glacialis/marshallae in spring and summer resulted both from the different water mass environments and from the reproductive cycle of the species. EP was greater on the shelf than in the basin, corresponding to differences in body size and nitrogen condition factor (NCF) in females, while the egg viability was generally high throughout the study area. EP showed no relationship with low-chlorophyll a biomass under heavy ice-cover in spring, while a significant relationship was observed in the more open water in summer. Adult female carbon condition factor (CCF) was much higher in summer, reflecting the accumulation of lipids during the growth season. Small animals with a markedly greater NCF dominated on the shelf. The shelfbreak region contained a mixture of females from the shelf and the basin with intermediate sizes, conditions, and EP rates. The occurrence of water typical of the ‘transition’ shelfbreak region and elevated EP in C. glacialis/marshallae offshore on the Barrow Canyon and East Barrow sections indicated offshore transport of productive shelf water and the associated plankton community. The input of nutrient-rich Pacific water and accompanying elevated production to the northern Chukchi Sea and the Chukchi-Beaufort shelfbreak region may contribute to the reproductive success of C. glacialis/marshallae in this region.  相似文献   

The role of oxyradicals in intracellular proteolysis and toxicity in mussels     

Miles A. Kirchin  Michael N. Moore  Roger T. Dean  Gary W. Winston 《Marine environmental research》1992,34(1-4)

Studies were performed on the common mussel, M. edulis L., to determine whether copper (Cu) exposure can affect the extent to which digestive cell proteins are oxidised and whether such oxidative damage is mediated by free radicals. Three age groups of mussels were exposed for 6 ^-days to environmentally realistic concentrations of Cu and then digestive gland homogenates were examined for evidence of protein carbonyl formation. Significant increases in carbonyls relative to untreated control mussels were seen for the youngest (2–4 year-old) and oldest (≥ 10 year-old) mussels only after exposure for 6 days, followed by recovery from exposure for a further 6 days. Untreated mussels also showed an age-related difference in protein oxidation, with a significantly lower concentration in the youngest animals (2–4 year olds). Copper did not affect the levels of modified tryptophan or tyrosine residues or the extent of total lipid peroxidation in digestive gland homogenate. Significant depletion of total vitamin E (a-tocopherol) was seen only in young and medium-aged mussels following exposure for 6 days. The levels of protein carbonyl groups were increased in digestive cell cytosol and lighter lysosomes but not in heavier lysosomes or digestive gland microsomes following 5 days exposure to Cu. Dihydrohodamine-123 was converted to fluorescent rhodamine-123 following sequestration into digestive cell lysosomes. The results suggest a link between the lysosomal sequestration of copper, a concomitant increase in the production of oxyradicals and the potential for intracellular oxidative damage, as well as an increased capacity for oxidative damage in older animals.  相似文献   

Late Quaternary tectonics,northern end of Juan de Fuca Ridge (northeast Pacific)     

Dean A. McManus  Mark L. Holmes  Bobb Carson  Sandra M. Barr 《Marine Geology》1972

Seismic reflection profiles from the northern end of Juan de Fuca Ridge reveal three axial valleys having a basement relief of as much as 2 sec (two-way travel time). A thick sequence, presumably of turbidites, mainly less than 0.7 m.y. old, covers much of the area. The oldest turbidites form the upper part of the fill of a possible Tertiary trench between the ridge and North America. The second turbidite unit extends beyond the trench and once formed an abyssal plain over most of northern Juan de Fuca Ridge and the area west to Explorer Ridge. Following formation of the plain, vertical movements began that broadly uplifted the crest of Juan de Fuca Ridge, block-faulted its northern end, produced faulting along Sovanco Fracture Zone, and upwarped the basement north of the ridge. Younger turbidites have filled the lowlands created by the vertical movements. The present sea floor topography and seismic activity show evidence of continued movements.  相似文献   

Declining Union Contract Coverage and Increasing Income Inequality in U.S. Metropolitan Areas     

Qinglin Hu  Dean M. Hanink 《The Professional geographer》2018,70(3):453-462

We focus on the association between the institutional factor of union contract coverage rates among workers and the variation in income inequality across a set of sixty-four metropolitan areas of the United States for the years 1990, 2000, and 2010. We use market variables of relative skills and relative education and demographic variables of race and gender as controls in our regression models. We also specify a set of models that substitute right-to-work status for union contract coverage rates. Our primary finding is that union contract coverage rates are temporally consistent and significant negative covariates of income inequality, as measured by Gini coefficients, across the metropolitan areas. Further, metropolitan areas in right-to-work states have consistently and significantly higher levels of inequality than expected given the control variable effects. Our interpretation of the primary finding is that issues of labor power and class play a clearly important role in contributing to income inequality in the set of metropolitan areas used in the analysis.  相似文献   

An Early Prediction of the Amplitude of Solar Cycle 25     

W. Dean Pesnell  Kenneth H. Schatten 《Solar physics》2018,293(7):112

A “Solar Dynamo” (SODA) Index prediction of the amplitude of Solar Cycle 25 is described. The SODA Index combines values of the solar polar magnetic field and the solar spectral irradiance at 10.7 cm to create a precursor of future solar activity. The result is an envelope of solar activity that minimizes the 11-year period of the sunspot cycle. We show that the variation in time of the SODA Index is similar to several wavelet transforms of the solar spectral irradiance at 10.7 cm. Polar field predictions for Solar Cycles 21?–?24 are used to show the success of the polar field precursor in previous sunspot cycles. Using the present value of the SODA index, we estimate that the next cycle’s smoothed peak activity will be about \(140 \pm30\) solar flux units for the 10.7 cm radio flux and a Version 2 sunspot number of \(135 \pm25\). This suggests that Solar Cycle 25 will be comparable to Solar Cycle 24. The estimated peak is expected to occur near \(2025.2 \pm1.5\) year. Because the current approach uses data prior to solar minimum, these estimates may improve as the upcoming solar minimum draws closer.  相似文献   

The Fill–Spill Hydrology of Prairie Wetland Complexes during Drought and Deluge     

Dean A. Shaw  Garth Vanderkamp  F. Malcolm Conly  Al Pietroniro  Lawrence Martz 《水文研究》2012,26(20):3147-3156

The fill–spill of surface depressions (wetlands) results in intermittent surface water connectivity between wetlands in the prairie wetland region of North America. Dynamic connectivity between wetlands results in dynamic contributing areas for runoff. However, the effect of fill–spill and the resultant variable or dynamic basin contributing area has largely been disregarded in the hydrological community. Long‐term field observations recorded at the St. Denis National Wildlife Area, Saskatchewan, allow fill–spill in the basin to be identified and quantified. Along with historical water‐level observations dating back to 1968, recent data collected for the basin include snow surveys, surface water survey and production of a light detection and ranging–derived digital elevation model. Data collection for the basin includes both wet and dry antecedent basin conditions during spring runoff events. A surface water survey at St. Denis in 2006 reveals a disconnected channel network during the spring freshet runoff event. Rather than 100% of the basin contributing runoff to the outlet, which most hydrological models assume, only approximately 39% of the basin contributes to the outlet. Anthropogenic features, such as culverts and roads, were found to influence the extent and spatial distribution of contributing areas in the basin. Historical pond depth records illustrate the effect of antecedent basin conditions on fill–spill and basin contributing area. A large pond at the outlet of the St. Denis basin, which only receives local runoff during dry years when upstream surface storage has not been satisfied, has pond runoff volumes that increase by a factor of 20 or more during wet years when upstream antecedent basin surface storage is satisfied and basin‐wide runoff contributes to the pond. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Sorby on sedimentology: A collection of papers from 1851 to 1908 by Henry Clifton Sorby. Geological milestones, 1: C.H. Summerson (editor). University of Miami,Miami, Fla., 1976, 225 pp., U.S. $7.50     

Dean A. McManus 《Marine Geology》1976,22(3):207-208

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