Migration and Development? The Gendered Costs of Migration on Mexico's Rural “Left Behind”          下载免费PDF全文

Rebecca M. Torres  Lindsey Carte 《Geographical review》2016,106(3):399-420

Governments, civil society, and policymakers assert the potential of international migration to foster development and alleviate poverty. Often such claims are rooted in macroscale geopolitical analyses of migration and development, which mask the localized, uneven, and embodied ways family members “left behind” bear the costs and subsidize the U.S./Mexico (inter)national integration project. Informed by feminist geopolitics, this article demonstrates how the left behind disproportionately bear the hidden costs of neoliberal restructuring and migration. We draw upon Mexican Migration Project (MMP) ethnosurvey data to frame the narratives of migrant family members left behind. Narratives were constructed through in‐depth interviews conducted in rural Veracruz. We conclude that in the absence of geographically specific examinations of the hidden costs associated with neoliberal development and migration it is possible that “migration for development” programs and policies may exacerbate inequities that will perpetuate migration and further weaken Mexican origin communities.  相似文献   

Basic Principles of Solar Acoustic Holography – (Invited Review)     

Lindsey  C.  Braun  D.C. 《Solar physics》2000,192(1-2):261-284

We summarize the basic principles of holographic seismic imaging of the solar interior, drawing on familiar principles in optics and parallels with standard optical holography. Computational seismic holography is accomplished by the phase-coherent wave-mechanical reconstruction of the p-mode acoustic field into the solar interior based on helioseismic observations at the solar surface. It treats the acoustic field at the solar surface in a way broadly analogous to how the eye treats electromagnetic radiation at the surface of the cornea, wave-mechanically refocusing radiation from submerged sources to render stigmatic images that can be sampled over focal surfaces at any desired depth. Holographic diagnostics offer a straight-forward assessment of the informational content of the observed p-mode spectrum independent of prospective physical models of the local interior anomalies that it represents. Computational holography was proposed as the optimum approach whereby to address the severe diffraction effects that confront standard tomography in the solar p-mode environment. It has given us a number of remarkable discoveries in the last two years and now promises a new insight into solar interior structure and dynamics in the local perspective. We compare the diagnostic roles of simple acoustic-power holography and phase-sensitive holography, and anticipate approaches to solar interior modeling based on holographic signatures. We identify simple computational principles that, applied to high-quality helioseismic observations, make it easy for prospective analysts to produce high-quality holographic images for practical applications in local helioseismology.  相似文献   

Using structure‐from‐motion to create glacier DEMs and orthoimagery from historical terrestrial and oblique aerial imagery          下载免费PDF全文

Jordan R. Mertes  Jason D. Gulley  Douglas I. Benn  Sarah S. Thompson  Lindsey I. Nicholson 《地球表面变化过程与地形》2017,42(14):2350-2364

Increased resolution and availability of remote sensing products, and advancements in small‐scale aerial drone systems, allows observations of glacial changes at unprecedented levels of detail. Software developments, such as structure‐from‐motion (SfM), now allow users an easy and efficient method to generate three‐dimensional (3D) models and orthoimages from aerial or terrestrial datasets. While these advancements show promise for current and future glacier monitoring, many regions still suffer a lack of observations from earlier time periods. We report on the use of SfM to extract spatial information from various historic imagery sources. We focus on three geographic regions, the European Alps, high Arctic Norway and the Nepal Himalayas. We used terrestrial field photographs from 1896, high oblique aerial photographs from 1936 and aerial handheld photographs from 1978 to generate digital elevation models (DEMs) and orthophotos of the Rhone glacier, Brøggerhalvøya and the lower Khumbu glacier, respectively. Our analysis shows that applying SfM to historic imagery can generate high quality models using only ground control points. Limited camera/orientation information was largely reproduced using self‐calibrated model data. Using these data, we calculated mean ground sampling distances across each site which demonstrates the high potential resolution of resulting models. Vertical errors for our models are ±5.4 m, ±5.2 m and ±3.3 m. Differencing shows similar patterns of thinning at lower Rhone (European Alps) and Brøggerhalvøya (Norway) glaciers, which have mean thinning rates of 0.31 m a^?1 (1896–2010) to 0.86 m a^?1 (1936–2010) respectively. On these clean ice glaciers thinning is highest in the terminus region and decreasing up‐glacier. In contrast to these glaciers, uneven topography, exposed ice‐cliffs and debris cover on the Khumbu glacier create a highly variable spatial distribution of thinning. The mean thinning rate for the Khumbu study area was found to be 0.54 ± 0.9 m a^?1 (1978–2015). Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Relationship between long‐term changes in algal community structure and herbivore diet at the Three Kings Islands,New Zealand     

W. Lindsey Zemke‐White  Kendall D. Clements 《新西兰海洋与淡水研究杂志》2013,47(5):837-844

We examined temporal changes at the Three Kings Islands, New Zealand in 1993 and 2002 in the diet of the endemic herbivorous fish Odax cyanoallix (Family Labridae) and in habitat‐forming macroalgae, and compared these with published accounts from 1979. The diet of O. cyanoallix predominantly comprised the laminarian Ecklonia radiata in 1993, and the fucoids Sargassum johnsonii and Landsburgia quercifolia in 2002. In depths <10 m, the endemic fucoid S. johnsonii was dominant in 1979 and 2002 and absent in 1993. E. radiata was absent in 1979, abundant in 1993, and rare in 2002. A period of significantly lower sea‐surface temperatures (SST) at the Three Kings Islands in 1990–95 corresponded to an unusually long El Niño event. The low SST may have resulted in the failure of S. johnsonii to grow and/or recruit during the El Niño event, leading to the observed changes. This study demonstrates variability in fucoid and laminarian assemblages over large time scales that are reflected in diet shifts in a species of herbivorous fish.  相似文献   

Far ultraviolet spectral properties of Saturn’s rings from Cassini UVIS     

E. Todd Bradley  Joshua E. Colwell  Jeffrey N. Cuzzi  Lindsey Chambers 《Icarus》2010,206(2):458-466

Spectra taken by the Cassini Ultraviolet Imaging Spectrograph (UVIS) of Saturn’s C ring, B ring, Cassini Division, and A ring have been analyzed in order to characterize ring particle surface properties and water ice abundance in the rings. UVIS spectra sense the outer few microns of the ring particles. Spectra of the normalized reflectance (I/F) in all four regions show a characteristic water ice absorption feature near 165 nm. Our analysis shows that the fractional abundance of surface water ice is largest in the outer B ring and decreases by over a factor of 2 across the inner C ring. We calculate the mean path length of UV photons through icy ring particle regolith and the scattering asymmetry parameter using a Hapke reflectance model and a Shkuratov reflectance model to match the location of the water ice absorption edge in the data. Both models give similar retrieved values of the photon mean length, however the retrieved asymmetry (g) values are different. The photon mean path lengths are nearly uniform across the B and A rings. Shortward of 165 nm the rings exhibit a slope that turns up towards shorter wavelengths, while the UV slope of 180/150 nm (reflectance outside the water absorption ratioed to that inside the absorption band) tracks I/F with maxima in the outer B ring and in the central A ring. Retrieved values of the scattering asymmetry parameter show the regolith grains to be highly backscattering in the FUV spectral regime.  相似文献   

Long-term database of Beasley Lake Watershed with 25 years of agricultural conservation practices     

Richard E. Lizotte Jr  Lindsey M. W. Yasarer  Mark K. Griffith  Martin A. Locke  Ronald L. Bingner 《水文研究》2021,35(2):e14061

Beasley Lake Watershed is an agriculturally influenced drainage basin in western Mississippi that has been intensively studied for 25 years. As part of the USDA Conservation Effects Assessment Project (CEAP), the watershed has archived hydrology, precipitation, and water quality data in order to measure the effects of multiple USDA Natural Resources Conservation Service conservation practices on lake water quality. The long-term database is available to researchers using a web-based application, Sustaining the Earth's Watersheds, Agricultural Research Data System (STEWARDS). STEWARDS is a GIS-based data retrieval application that encompasses spatial and temporal data collected from multiple sites within the watershed. This data note describes information located in the STEWARDS Beasley Lake Watershed database, including hydrology, precipitation, and water quality data. This information is valuable to researchers and agencies beyond the USDA as an available and useful database to improve the understanding of how land-use practices affect the water quality of shallow lake systems.  相似文献   

Watershed studies at the Hubbard Brook Experimental Forest: Building on a long legacy of research with new approaches and sources of data     

John L. Campbell  Lindsey E. Rustad  Scott W. Bailey  Emily S. Bernhardt  Charles T. Driscoll  Mark B. Green  Peter M. Groffman  Gary M. Lovett  William H. McDowell  Kevin J. McGuire  Emma J. Rosi 《水文研究》2021,35(1):e14016

The Hubbard Brook Experimental Forest (HBEF) was established in 1955 by the U.S. Department of Agriculture, Forest Service out of concerns about the effects of logging increasing flooding and erosion. To address this issue, within the HBEF hydrological and micrometeorological monitoring was initiated in small watersheds designated for harvesting experiments. The Hubbard Brook Ecosystem Study (HBES) originated in 1963, with the idea of using the small watershed approach to study element fluxes and cycling and the response of forest ecosystems to disturbances, such as forest management practices and air pollution. Early evidence of acid rain was documented at the HBEF and research by scientists at the site helped shape acid rain mitigation policies. New lines of investigation at the HBEF have built on the long legacy of watershed research resulting in a shift from comparing inputs and outputs and quantifying pools and fluxes to a more mechanistic understanding of ecosystem processes within watersheds. For example, hydropedological studies have shed light on linkages between hydrologic flow paths and soil development that provide valuable perspective for managing forests and understanding stream water quality. New high frequency in situ stream chemistry sensors are providing insights about extreme events and diurnal patterns that were indiscernible with traditional weekly sampling. Additionally, tools are being developed for visual and auditory data exploration and discovery by a broad audience. Given the unprecedented environmental change that is occurring, data from the small watersheds at the HBEF are more relevant now than ever and will continue to serve as a basis for sound environmental decision-making.  相似文献   

Erratum to: Pan evaporation and wind run decline in the Cape Floristic Region of South Africa (1974�C2005): implications for vegetation responses to climate change     

M. Timm Hoffman  Michael D. Cramer  Lindsey Gillson  Michael Wallace 《Climatic change》2011,109(3-4):453-454

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A Statistical Correlation of Sunquakes Based on Their Seismic and White-Light Emission     

J. C. Buitrago-Casas  J. C. Martínez Oliveros  C. Lindsey  B. Calvo-Mozo  S. Krucker  L. Glesener  S. Zharkov 《Solar physics》2015,290(11):3151-3162

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Gastropod shell repair tracks predator abundance          下载免费PDF全文

Emily S. Stafford  Carrie L. Tyler  Lindsey R. Leighton 《Marine Ecology》2015,36(4):1176-1184

Predator‐prey interactions can shape biological communities and drive evolutionary change. The assessment of predation rates in modern and ancient ecosystems presents many challenges. We examined the utility of one common predation metric, shell repair frequency, as a proxy for crushing predation on marine gastropod populations. Our six localities near Bamfield, British Columbia, represented two contrasting predation regimes: three high‐wave‐energy (exposed) environments have low predation rates, while three low‐wave‐energy (protected) environments exhibit high predation rates. We measured the occurrence of repair scars for local populations of the gastropod Chlorostoma funebrale, and recorded multiple independent variables (shell measurements, water velocity, predatory crab abundance) at each locality. Fisher's exact test established that the repair frequencies observed in the protected localities were significantly greater than those of the exposed environments. Factors important in predicting the likelihood of an individual having a repair scar were examined using binomial logistic regression. A model containing the main effects of crab abundance, shell height, shell thickness and water velocity provided the best fit in predicting the presence of repair scars, with crab abundance having the largest contribution. The strong relationship between the presence of repair scars and predator abundance indicates that repair frequency is a valid tool for assessing predation intensity in gastropod populations.  相似文献