65,581 research outputs found
Basins of attraction on random topography
We investigate the consequences of fluid flowing on a continuous surface upon
the geometric and statistical distribution of the flow. We find that the
ability of a surface to collect water by its mere geometrical shape is
proportional to the curvature of the contour line divided by the local slope.
Consequently, rivers tend to lie in locations of high curvature and flat
slopes. Gaussian surfaces are introduced as a model of random topography. For
Gaussian surfaces the relation between convergence and slope is obtained
analytically. The convergence of flow lines correlates positively with drainage
area, so that lower slopes are associated with larger basins. As a consequence,
we explain the observed relation between the local slope of a landscape and the
area of the drainage basin geometrically. To some extent, the slope-area
relation comes about not because of fluvial erosion of the landscape, but
because of the way rivers choose their path. Our results are supported by
numerically generated surfaces as well as by real landscapes
Evolutionary Economics celebrates Innovation and Creativity based Economy\ud
The paper draws issue on the evolutionary economics that open our mind on seeing economy as growing and living organism with any characters of robustness, self-organization, adaptation, and evolution. This has been recognized, as in global picture, we enter the phase in which information and knowledge acquisition rapidly plays a major role in economy. The discussions is presented by demonstrating some qualitative properties and theoretical explorations on long range historical economic growth and development and thus followed by some highlights on innovation, creativity and elaborations regarding to fitness landscapes incorporating memetics, as works related to social and cultural aspects of social system, while talking about economic system in general. The discussions depicts some important notions on market and product diversifications that have been the source of the economic growth in general
Highly Variable Genomic Landscape of Endogenous Retroviruses in the C57BL/6J Inbred Strain, Depending on Individual Mouse, Gender, Organ Type, and Organ Location.
Transposable repetitive elements, named the "TREome," represent ~40% of the mouse genome. We postulate that the germ line genome undergoes temporal and spatial diversification into somatic genomes in conjunction with the TREome activity. C57BL/6J inbred mice were subjected to genomic landscape analyses using a TREome probe from murine leukemia virus-type endogenous retroviruses (MLV-ERVs). None shared the same MLV-ERV landscape within each comparison group: (1) sperm and 18 tissues from one mouse, (2) six brain compartments from two females, (3) spleen and thymus samples from four age groups, (4) three spatial tissue sets from two females, and (5) kidney and liver samples from three females and three males. Interestingly, males had more genomic MLV-ERV copies than females; moreover, only in the males, the kidneys had higher MLV-ERV copies than the livers. Perhaps, the mouse-, gender-, and tissue/cell-dependent MLV-ERV landscapes are linked to the individual-specific and dynamic phenotypes of the C57BL/6J inbred population
Dynamic landscapes and human dispersal patterns : tectonics, coastlines, and the reconstruction of human habitats
Studies of the impact of physical environment on human evolution usually focus on climate as the main external forcing agent of evolutionary and cultural change. In this paper we focus on changes in the physical character of the landscape driven by geophysical processes as an equally potent factor. Most of the landscapes where finds of early human fossils and artefacts are concentrated are ones that have been subjected to high levels of geological instability, either because of especially active tectonic processes associated with faulting and volcanic activity or because of proximity to coastlines subject to dramatic changes of geographical position and physical character by changes of relative sea level. These processes can have both beneficial effects, creating ecologically attractive conditions for human settlement, and deleterious or disruptive ones, creating barriers to movement, disruption of ecological conditions, or hazards to survival. Both positive and negative factors can have powerful selective effects on human behaviour and patterns of settlement and dispersal. We consider both these aspects of the interaction, develop a framework for the reconstruction and comparison of landscapes and landscape change at a variety of scales, and illustrate this with selected examples drawn from Africa and Arabia
Scale-dependence of lithological control on topography: Bedrock channel geometry and catchment morphometry in western Scotland
We propose that a scale-dependent topographic signature of erodibility arises due to fluvial and glacial erosion acting
on different parts of the landscape at different times. For 14 catchments in western Scotland, we define three levels
of substrate erodibility in order of decreasing resistance: quartzite rocks, nonquartzite rocks, and zones of fault-related fracture. Then, using digital topographic and planimetric data coupled with field measurements, we identify regression based scaling relationships between substrate erodibility and morphometric parameters at two spatial scales. Catchment-scale morphometry shows a weak to variable relationship with substrate metrics overall. Erodibility can be inferred from catchment steepness indices (i.e., channel steepness index and relief ratio), but the existence of multiple exceptions could confound a more general application of this approach. Nonetheless, major valley troughs trace fault zones and nonquartzite rocks, leaving much of the higher and steeper ground formed in quartzite. At the reach scale, bedrock channel slope is far more sensitive to substrate erodibility than is channel width. Quartzite outcrops steepen bedrock channels by a factor of 1.5–6.0, and in terms of unit stream power, channels increase their erosional capacity by a factor of 2.7–3.5. Yet only 4%–13% of this increase is due to channel narrowing. Based on a large data set of bedrock channel width (n = 5825) from four rivers, we find that width scales with drainage area (in m<sup>2</sup>) as W = 0.01A<sup>0.28</sup>. Our results are consistent with the view that width-area scaling is similar in all single-thread rivers subject to transport-limited conditions but that for increasingly sediment supply limited settings, erosional thresholds at the channel boundary are the key determinants of bedrock channel width
Discriminating small wooded elements in rural landscape from aerial photography: a hybrid pixel/object-based analysis approach
While small, fragmented wooded elements do not represent a large surface area in
agricultural landscape, their role in the sustainability of ecological processes is
recognized widely. Unfortunately, landscape ecology studies suffer from the lack
of methods for automatic detection of these elements. We propose a hybrid
approach using both aerial photographs and ancillary data of coarser resolution
to automatically discriminate small wooded elements. First, a spectral and textural
analysis is performed to identify all the planted-tree areas in the digital photograph.
Secondly, an object-orientated spatial analysis using the two data sources
and including a multi-resolution segmentation is applied to distinguish between
large and small woods, copses, hedgerows and scattered trees. The results show the
usefulness of the hybrid approach and the prospects for future ecological
applications
Ecological Landscape Planning : A Gaming Approach in Education
An understanding of the complex problems of land use competition requires an appreciation of natural processes, cultural values, economic imperatives and political agendas. This integrated understanding is an important component of the study program for tertiary students about to complete their professional qualification in landscape architecture at the Queensland University of Technology. This paper introduces a repertoire of game templates as an initial step in formulating a conceptual framework for the curriculum/games designer to explore the potential of play in ecological landscape planning. The concepts of social action space, permissible action space and motivational action space are used to investigate the qualities of each template for further game design development. The abstraction of these concepts may assist the designer to move beyond the usability of games into viewing their value as a learning method
Mapping and analysis of changes in the riparian landscape structure of the Lockyer Valley Catchment, Queensland, Australia
[Abstract]: A case study of the Lockyer Valley catchment in Queensland, Australia, was conducted to develop appropriate mapping and assessment techniques to quantify the nature and magnitude of riparian landscape structural changes within a catchment. The study employed digital image processing techniques to produce land cover maps from the 1973 and 1997 Landsat imagery. Fixed and variable width buffering of streams were implemented using a geographic information system (GIS) to estimate the riparian zone and to subsequently calculate the landscape patterns using the Patch Analyst (Grid) program (a FRAGSTATS interface). The nature of vegetation clearing was characterised based on land tenure, slope and stream order. Using the Pearson chi-square test and Cramer’s V statistic, the relationships between the vegetation clearing and land tenure were further assessed. The results show the significant decrease in woody vegetation areas mainly due to conversion to pasture. Riparian vegetation corridors have become more fragmented, isolated and of much smaller patches. Land tenure was found to be significantly associated with the vegetation clearing, although the strength of association was weak. The large proportion of deforested riparian zones within steep slopes or first-order streams raises serious questions about the catchment health and the longer term potential for land degradation by upland clearing. This study highlights the use of satellite imagery and geographic information systems in mapping and analysis of landscape structural change, as well as the identification of key issues related to sensor spatial resolution, stream buffering widths, and the quantification of land transformation processes
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