Free and open source GIS in South America: political inroads and local advocacy     

Sterling Quinn 《International journal of geographical information science》2020,34(3):464-483

ABSTRACT

Geographical information systems (GIS) practitioners worldwide enjoy a growing array of free and open source software (FOSS) options. This software has expanded the accessibility of GIS in economically developing countries while fostering local technical expertise. This article reviews FOSS GIS uptake and advocacy in South America, especially how it relates to a climate of political friendliness toward FOSS in the region. The use or absence of FOSS GIS is assessed in public-facing web maps in South America, first at the national government level, and then at the provincial level using Argentina as a country of study. Local technical support groups and software development initiatives surrounding FOSS GIS in South America are then summarized. Finally, three case studies are presented of notable efforts to build FOSS GIS technical communities at the local level: the FOSSGIS Brasil online magazine, the Geoinquietos Argentina professional network, and the FOSS.4GIS.GOV conference in Brazil. A study of the leaders, dynamics, and practices of these groups can inform others in similar circumstances around the world who are trying to promote FOSS GIS adoption, development, skills, and services.  相似文献   

Topography of the salar de Uyuni, Bolivia from kinematic GPS     

Adrian A. Borsa  Helen A. Fricker  Bruce G. Bills  Jean-Bernard Minster  Claudia C. Carabajal  Katherine J. Quinn 《Geophysical Journal International》2008,172(1):31-40

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Forming a large disc galaxy from a z < 1 major merger     

F. Governato  C. B. Brook  A. M. Brooks  L. Mayer  B. Willman †  P. Jonsson  A. M. Stilp  L. Pope  C. Christensen  J. Wadsley  T. Quinn 《Monthly notices of the Royal Astronomical Society》2009,398(1):312-320

Using high-resolution SPH simulations in a fully cosmological Λ cold dark matter context, we study the formation of a bright disc-dominated galaxy that originates from a 'wet' major merger at   z = 0.8  . The progenitors of the disc galaxy are themselves disc galaxies that formed from early major mergers between galaxies with blue colours. A substantial thin stellar disc grows rapidly following the last major merger and the present-day properties of the final remnant are typical of early-type spiral galaxies, with an i -band bulge-to-disc ratio ∼0.65, a disc scalelength of 7.2 kpc,   g − r = 0.5 mag  , an H  i linewidth ( W ₂₀/2) of 238 km s⁻¹ and total magnitude   i =−22.4  . The key ingredients for the formation of a dominant stellar disc component after a major merger are (i) substantial and rapid accretion of gas through cold flows followed at late times by cooling of gas from the hot phase, (ii) supernova feedback that is able to partially suppress star formation during mergers and (iii) relative fading of the spheroidal component. The gas fraction of the progenitors' discs does not exceed 25 per cent at   z < 3  , emphasizing that the continuous supply of gas from the local environment plays a major role in the regrowth of discs and in keeping the galaxies blue. The results of this simulation alleviate the problem posed for the existence of disc galaxies by the high likelihood of interactions and mergers for galaxy-sized haloes at relatively low z .  相似文献   

Dynamics of barred galaxies: effects of disc height     

Anatoly Klypin  Octavio Valenzuela  Pedro Colín  Thomas Quinn 《Monthly notices of the Royal Astronomical Society》2009,398(2):1027-1040

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Using small cities to understand the crowd behind OpenStreetMap     

Sterling Quinn 《GeoJournal》2017,82(3):455-473

As businesses and governments integrate OpenStreetMap (OSM) into their services in ways that require comprehensive coverage, there is a need to expand research outside of major urban areas and consider the strength of the map in smaller cities. A place-specific inquiry into the OSM contributor sets in small cities allows an intimate look at user motives, locations, and editing habits that are readily described in the OSM metadata and user profile pages, but often missed by aggregate studies of OSM data. Using quantitative and qualitative evidence from the OSM history of five small cities across North and South America, I show that OSM is not accumulating large local corpuses of editors outside of major urban areas. In these more remote places OSM remains largely at the mercy of an unpredictable mix of casual contributions, business interests, feature-specific “hobbyists”, bots, and importers, all passing through the map at different scales for different reasons. I present a typology of roles played by contributors as they expand and fix OSM in casual, systematic, and automated fashion. I argue that these roles are too complex to be conceptualized with the traditional “citizen as sensor” model of understanding volunteered geographic information. While some contributors are driven by pride of place, others are more interested in improving map quality or ensuring certain feature types are represented. Institutions considering the use of OSM data in their projects should be aware of these varied influences and their potential effects on the data.  相似文献   

Detecting active comets in the SDSS     

Michael Solontoi  ?eljko Ivezi?  Mark Claire  Andrew Becker  Patrick B. Hall  Robert H. Lupton  Tom Quinn  Don Schneider 《Icarus》2010,205(2):605-618

Using a sample of serendipitously discovered active comets in the Sloan Digital Sky Survey (SDSS), we develop well-controlled selection criteria for greatly increasing the efficiency of comet identification in the SDSS catalogs. After follow-up visual inspection of images to reject remaining false positives, the total sample of SDSS comets presented here contains 19 objects, roughly one comet per 10 million other SDSS objects. The good understanding of selection effects allows a study of the population statistics, and we estimate the apparent magnitude distribution to r∼18, the ecliptic latitude distribution, and the comet distribution in SDSS color space. The most surprising results are the extremely narrow range of colors for comets in our sample (e.g. root-mean-square scatter of only ∼0.06 mag for the g-r color), and the similarity of comet colors to those of jovian Trojans. We discuss the relevance of our results for upcoming deep multi-epoch optical surveys such as the Dark Energy Survey, Pan-STARRS, and the Large Synoptic Survey Telescope (LSST), and estimate that LSST may produce a sample of about 10,000 comets over its 10-year lifetime.  相似文献   

Operational Parameters,Data Density and Benthic Ecology: Considerations for Image-Based Classification of Multibeam Backscatter     

Chris McGonigle  Craig J. Brown  Rory Quinn 《Marine Geodesy》2013,36(1):16-38

Efforts to develop a procedurally robust method for automated classification of multibeam backscatter have taken a variety of approaches (e.g., image-based, textural, angular range analysis). For image-based classification, little research has focused on the roles of operational parameters of vessel and sonar system in affecting the final classification. Repeat multibeam surveys (2005 and 2006) conducted at the same area with different sounding densities were classified using QTC-Multiview. Comparison of class areas revealed 78% agreement between classifications derived from the two surveys. Cross-tabulation of ground truth video and class demonstrate 71% agreement in the low-density survey and 77% for the high-density. Differences between classifications are primarily attributed to variation in along track data density, errors in the compensation process, and/ or insufficient quality control of the input data. Natural change detection at the scales observed was determined not to be practically discernable from the errors associated with the classification process.  相似文献   

Land‐use effects on the hyporheic ecology of five small streams near Hamilton,New Zealand     

Andrew J. Boulton  Mike R. Scarsbrook  John M. Quinn  Greg P. Burrell 《新西兰海洋与淡水研究杂志》2013,47(5):609-622

Although the importance of the subsurface saturated interstitial zone (hyporheic zone) to the ecological functioning and maintenance of water quality of stream ecosystems is well known, there is little information on the impacts of different forms of land use upon this zone. Hyporheic physico‐chemistry and invertebrates were compared among small streams draining hill‐country catchments under pasture, exotic pine forest, and native forest near Hamilton, New Zealand. In streams draining native forest, the hyporheic zone harboured a relatively diverse invertebrate fauna comprising mostly taxa common in the surface benthos, although a few apparently obligate hyporheic taxa (ostracods, blind amphipods) were collected. Few individuals and taxa occupied the hyporheic zones of streams draining pasture with some groups such as water mites conspicuously absent. The hyporheos of the stream in exotic pine forest was similar in richness and abundance to that of the pasture streams. Hyporheic water temperatures were significantly higher in the pasture streams than those in pine or native forest. There were strong positive correlations between percentage saturation of dissolved oxygen in the hyporheic zones of all streams and both species richness and total invertebrate abundance. We suggest that land clearance for pasture leads to hill slumping and siltation that bury the lateral bars along the stream channels, rendering this habitat unsuitable for hyporheic invertebrates. Channel narrowing and incision may physically remove further hyporheic habitat, and the reduction of flushing flows to remove interstitial silt and clay leads to low hyporheic dissolved oxygen concentrations and reduced colonisation by surface benthos.  相似文献   

Shade effects on stream periphyton and invertebrates: An experiment in streamside channels   总被引：4，自引：4，他引：0  

John M. Quinn  A. Bryce Cooper  Morag J. Stroud  Gregory P. Burrell 《新西兰海洋与淡水研究杂志》2013,47(5):665-683

Abstract

The effects of shade on periphyton and invertebrates were investigated by comparisons in 12 replicate channels beside a pasture stream where shade cloth reduced the photosynthetically available radiation (PAR) by 0, 60, 90, and 98%. Periphytic productivity decreased with increasing shade. Periphyton chlorophyll a was consistently low (< 30 mg m^?2) under 98 and 90% shade and usually low at 60% shade, whereas blooms were common during summer in the unshaded channels. More periphytic taxa occurred in the open than shaded channels and the relative concentration of the photo‐protective pigment beta‐carotene decreased with increasing shade. Nitrate uptake rates by periphyton, measured in separate chamber studies, decreased progressively as shade increased from 60% through 90% to 98%, and were more strongly correlated with gross primary productivity than periphyton chlorophyll a and particulate carbon levels. Total invertebrate and chironomid densities declined significantly as shade increased from 60 to 90% and invertebrate taxa richness declined markedly between 90 and 98% shade. Most collector‐browsing invertebrates (other than chironomids) had similar densities under 0–90% shade and only declined at 98%. This suggests a weak coupling of these invertebrates with local periphyton production and also suggests that energy derived from up‐stream sources may be their most important food in these pastoral streams.  相似文献   

Fecundity of chinook salmon (Oncorhynchus tshawytscha) from the Waitaki and Rakaia Rivers,New Zealand     

Thomas P. Quinn  Simon Bloomberg 《新西兰海洋与淡水研究杂志》2013,47(3-4):429-434

The fecundity of chinook salmon (Oncorhynchus tshawytscha) was estimated from maturing fish captured by anglers in the lower Waitaki River in 1985 and 1987–89, and from mature fish spawned at the Glenariffe Research Station on the Rakaia River in 1992. Fecundity was positively correlated with fork length (FL); estimated fecundities at 750 mm FL were 5024 eggs for Waitaki and 4829 eggs for Glenariffe salmon. The slopes of the regressions of fecundity on FL differed between the populations but the Glenariffe data did not differ from Rakaia River samples from 1967, 1973, and 1976. Significant inter‐annual variation in the FL‐fecundity relationship was detected in Waitaki River samples. Egg weights, taken from the Glenariffe samples, were positively correlated with length and averaged 0.17 g. However, salmon with high fecundity for their FL tended to have small eggs, and vice versa.  相似文献