116 research outputs found
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Increasing phenological asynchrony between spring green-up and arrival of migratory birds
Consistent with a warming climate, birds are shifting the timing of their migrations, but it remains unclear to what extent these shifts have kept pace with the changing environment. Because bird migration is primarily cued by annually consistent physiological responses to photoperiod, but conditions at their breeding grounds depend on annually variable climate, bird arrival and climate-driven spring events would diverge. We combined satellite and citizen science data to estimate rates of change in phenological interval between spring green-up and migratory arrival for 48 breeding passerine species across North America. Both arrival and green-up changed over time, usually in the same direction (earlier or later). Although birds adjusted their arrival dates, 9 of 48 species did not keep pace with rapidly changing green-up and across all species the interval between arrival and green-up increased by over half a day per year. As green-up became earlier in the east, arrival of eastern breeding species increasingly lagged behind green-up, whereas in the west—where green-up typically became later—birds arrived increasingly earlier relative to green-up. Our results highlight that phenologies of species and trophic levels can shift at different rates, potentially leading to phenological mismatches with negative fitness consequences
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A century of decoupling size and structure of urban spaces in the United States
Most cities in the United States of America are thought to have followed similar development trajectories to evolve into their present form. However, data on spatial development of cities are limited prior to 1970. Here we leverage a compilation of high-resolution spatial land use and building data to examine the evolving size and form (shape and structure) of US metropolitan areas since the early twentieth century. Our analysis of building patterns over 100 years reveals strong regularities in the development of the size and density of cities and their surroundings, regardless of timing or location of development. At the same time, we find that trajectories regarding shape and structure are harder to codify and more complex. We conclude that these discrepant developments of urban size- and form-related characteristics are driven, in part, by the long-term decoupling of these two sets of attributes over time.
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Fine-grained, spatiotemporal datasets measuring 200 years of land development in the United States
The collection, processing, and analysis of remote sensing data since the early 1970s has rapidly improved our understanding of change on the Earth’s surface. While satellite-based Earth observation has proven to be of vast scientific value, these data are typically confined to recent decades of observation and often lack important thematic detail. Here, we advance in this arena by constructing new spatially explicit settlement data for the United States that extend back to the early 19th century and are consistently enumerated at fine spatial and temporal granularity (i.e. 250m spatial and 5-year temporal resolution). We create these time series using a large, novel building-stock database to extract and map retrospective, fine-grained spatial distributions of built-up properties in the conterminous United States from 1810 to 2015. From our data extraction, we analyse and publish a series of gridded geospatial datasets that enable novel retrospective historical analysis of the built environment at an unprecedented spatial and temporal resolution. The datasets are part of the Historical Settlement Data Compilation for the United States (https://dataverse.harvard.edu/dataverse/hisdacus, last access: 25 January 2021) and are available at https://doi.org/10.7910/DVN/YSWMDR (Uhl and Leyk, 2020a), https://doi.org/10.7910/DVN/SJ213V (Uhl and Leyk, 2020b), and https://doi.org/10.7910/DVN/J6CYUJ (Uhl and Leyk, 2020c)
Relationship between age and elite marathon race time in world single age records from 5 to 93 years
Looking Back, Looking Forward: Progress and Prospect for Spatial Demography
In 2011 a specialist meeting on the “Future Directions in Spatial Demography” was
held in Santa Barbara, California (Matthews, Goodchild, & Janelle, 2012).1
This specialist meeting was the capstone to a multi-year National Institutes of Health training
grant that had supported workshops in advanced spatial analysis methods increasing used by population scientists.2
Early-career scholars who had participated in the
training workshops and senior demographers and geographers drawn from across
the United States participated in the specialist meeting.3
The application process to
attend the 2011 meeting, required that each of the forty-one attendees submit a statement that reviewed challenges and identifed new directions for spatial demography,
including gaps in current knowledge regarding innovations in geospatial data, spatial
statistical methods, and the integration of data and models to enhance the science of
spatial demography in population and health research. Reading again some of the ruminations of these scholars is an interesting exercise in its own right. The level
of optimism back in 2011 was high, and especially regarding anticipated changes
in computational capacity, leveraging big data (including volunteered geographic
information), developments in data systems (including new data high resolution data
products and online resources such as multi-scale map interfaces and dashboards),
and in methods such as time–space models, agent-based models, microsimulation,
and small-area estimation. There were also several challenges identifed including,
but not limited to, study designs, data integration, data validation, confdentiality,
non-representative data, historic data, defnitions of place, residential selection and
mobility as well as two overarching challenges related to the role and contribution of
spatial demographers in interdisciplinary population and health research, and many,
many comments on training issues. Substantively the attendees research focused
on all forms of interaction between people and place (and the reciprocal relations
between the people in social, built, and physical environment contexts) covering the
gamut of demographic processes from reproductive health to mortality, though with
perhaps an overrepresentation of researchers in areas related to population and environment research, racial and residential segregation, and migration.The R25 Training Grant was funded through the Eunice Kennedy Shriver National Institutes of Child
Health and Human Development (NICHD 5R-25 HD057002; Principal Investigator: Stephen A. Matthews).
Looking Back, Looking Forward: Progress and Prospect for Spatial Demography
In 2011 a specialist meeting on the “Future Directions in Spatial Demography” was
held in Santa Barbara, California (Matthews, Goodchild, & Janelle, 2012).1
This specialist meeting was the capstone to a multi-year National Institutes of Health training
grant that had supported workshops in advanced spatial analysis methods increasing used by population scientists.2
Early-career scholars who had participated in the
training workshops and senior demographers and geographers drawn from across
the United States participated in the specialist meeting.3
The application process to
attend the 2011 meeting, required that each of the forty-one attendees submit a statement that reviewed challenges and identifed new directions for spatial demography,
including gaps in current knowledge regarding innovations in geospatial data, spatial
statistical methods, and the integration of data and models to enhance the science of
spatial demography in population and health research. Reading again some of the ruminations of these scholars is an interesting exercise in its own right. The level
of optimism back in 2011 was high, and especially regarding anticipated changes
in computational capacity, leveraging big data (including volunteered geographic
information), developments in data systems (including new data high resolution data
products and online resources such as multi-scale map interfaces and dashboards),
and in methods such as time–space models, agent-based models, microsimulation,
and small-area estimation. There were also several challenges identifed including,
but not limited to, study designs, data integration, data validation, confdentiality,
non-representative data, historic data, defnitions of place, residential selection and
mobility as well as two overarching challenges related to the role and contribution of
spatial demographers in interdisciplinary population and health research, and many,
many comments on training issues. Substantively the attendees research focused
on all forms of interaction between people and place (and the reciprocal relations
between the people in social, built, and physical environment contexts) covering the
gamut of demographic processes from reproductive health to mortality, though with
perhaps an overrepresentation of researchers in areas related to population and environment research, racial and residential segregation, and migration.The R25 Training Grant was funded through the Eunice Kennedy Shriver National Institutes of Child
Health and Human Development (NICHD 5R-25 HD057002; Principal Investigator: Stephen A. Matthews).
new technologies for the sustainable management and planning of rural land and environment
New technologies could be adequately introduced for an improved analysis aimed to the sustainable management and planning of the rural land, as well as its environment and landscape. Nowadays, this analysis is easier and more complete through the use of powerful and reliable tools. Several changes can be considered to be as models of territorial development, useful for an appropriate planning of the human interventions in a rural area. Remote sensing techniques could be employed for the monitoring of agricultural land variation, while Geographical Information Systems are excellent tools for landscape modeling and three-dimensional analysis. In this chapter, land-use changes in a rural area located in southern Italy were analyzed by comparing some historical cartographic supports with modern maps, in order to evaluate the morphological and vegetation variations of the agroforestry land during time. Moreover, a landscape analysis was conducted through the implementation of digital terrain models, which were enriched by draping land cover pictures over them. These elaborations finally enabled an evaluation in a scenic way of the aesthetic quality of the agroforestry landscape, allowing a virtual jump back to time periods when digital aerial photography was not yet even possible. This multi-temporal analysis with the support of GIS techniques revealed to have a great potential for assessing and managing landscape diversity and changes of vegetation, as well as for planning sound interventions over the landscape structures
Physiological aspects of the determination of comprehensive arterial inflows in the lower abdomen assessed by Doppler ultrasound
Non-invasive measurement of splanchnic hemodynamics has been utilized in the clinical setting for diagnosis of gastro-intestinal disease, and for determining reserve blood flow (BF) distribution. However, previous studies that measured BF in a "single vessel with small size volume", such as the superior mesenteric and coeliac arteries, were concerned solely with the target organ in the gastrointestinal area, and therefore evaluation of alterations in these single arterial BFs under various states was sometimes limited to "small blood volumes", even though there was a relatively large change in flow. BF in the lower abdomen (BFAb) is potentially a useful indicator of the influence of comprehensive BF redistribution in cardiovascular and hepato-gastrointestinal disease, in the postprandial period, and in relation to physical exercise. BFAb can be determined theoretically using Doppler ultrasound by subtracting BF in the bilateral proximal femoral arteries (FAs) from BF in the upper abdominal aorta (Ao) above the coeliac trunk. Prior to acceptance of this method of determining a true BFAb value, it is necessary to obtain validated normal physiological data that represent the hemodynamic relationship between the three arteries. In determining BFAb, relative reliability was acceptably high (range in intra-class correlation coefficient: 0.85-0.97) for three arterial hemodynamic parameters (blood velocity, vessel diameter, and BF) in three repeated measurements obtained over three different days. Bland-Altman analysis of the three repeated measurements revealed that day-to-day physiological variation (potentially including measurement error) was within the acceptable minimum range (95% of confidence interval), calculated as the difference in hemodynamics between two measurements. Mean BF (ml/min) was 2951 ± 767 in Ao, 316 ± 97 in left FA, 313 ± 83 in right FA, and 2323 ± 703 in BFAb, which is in agreement with a previous study that measured the sum of BF in the major part of the coeliac, mesenteric, and renal arteries. This review presents the methodological concept that underlies BFAb, and aspects of its day-to-day relative reliability in terms of the hemodynamics of the three target arteries, relationship with body surface area, respiratory effects, and potential clinical usefulness and application, in relation to data previously reported in original dedicated research
Evaluating the spatial uncertainty of future land abandonment in a mountain valley (Vicdessos, Pyrenees-France) : insights form model parameterization and experiments
International audienceEuropean mountains are particularly sensitive to climatic disruptions and land use changes. The latter leads to high rates of natural reforestation over the last 50 years. Faced with the challenge of predicting possible impacts on ecosystem services, LUCC models offer new opportunities for land managers to adapt or mitigate their strategies. Assessing the spatial uncertainty of future LUCC is crucial for the defintion of sustainable land use strategies. However, the sources of uncertainty may differ, including the input parameters, the model itself, and the wide range of possible futures. The aim of this paper is to propose a method to assess the probability of occurrence of future LUCC that combines the inherent uncertainty of model parameterization and the ensemble uncertainty of the future based scenarios. For this purpose, we used the Land Change Modeler tool to simulate future LUCC on a study site located in the Pyrenees Mountains (France) and 2 scenarios illustratins 2 land use strategies. The model was parameterized with the same driving factors used for its calibration. The defintion of static vs. dynamic and quantitative vs. qualitative (discretized) driving factors, and their combination resulted in 4 parameterizations. The combination of model outcomes produced maps of spatial uncertainty of future LUCC. This work involves literature to future-based LUCC studies. It goes beyond the uncertainty of simulation models by integrating the unceertainty of the future to provide maps to help decision makers and land managers
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