Observations on Spatial Heterogeneity of Surface Chlorophyll in one and two Dimensions

1978 ◽  
Vol 58 (2) ◽  
pp. 487-502 ◽  
Author(s):  
J. W. Horwood
Keyword(s):  
The Netherlands ◽  
Spatial Heterogeneity ◽  
Large Scale ◽  
Two Dimensions ◽  
Temporal Heterogeneity ◽  
English Channel ◽  
Spatial And Temporal Heterogeneity ◽  
Careful Measurement ◽  
Present Understanding ◽  
Northeast Coast

I trust that I will not be criticized for saying that, in general, the argument between Hensen and Haeckel has been resolved. Hensen (1887, 1895) believed that true spatial and temporal heterogeneity of the plankton could be resolved by careful measurement and analyses of variance. Haeckel (1893) thought these analyses might give more information than the data possessed. Our present understanding of spatial heterogeneity, and its analysis, does not lead us to disagree with either. Investigations carried out by a number of marine ecologists have shown large-scale spatial variations in phytoplankton. Amongst many others, this feature can be seen in studies off the northeast coast of England (Cushing, 1955), in the English Channel and Celtic Sea (Cushing, 1957; Pingree et al. 1976), off Scotland (Adams, Baird & Dunn, 1975,1976) and off the coast of the Netherlands (Gieskes & Kraay, 1975). Nevertheless the statistics of sampling heterogeneous distributions is far from simple, estimates of density for instance can be greatly influenced by the sample size (e.g. Greig-Smith, 1964; Cassie, 1963). Bainbridge (1957) summarized his review by saying that patches occurred on all scales from a few feet to as much as 30 or 40 miles by 120 or 180 miles. Our present understanding of the nature of turbulence in the sea would reduce his few feet to centimetres.

Biodiversity in Heterogeneous and Dynamic Landscapes

2016 ◽  
Author(s):  
Clélia Sirami
Keyword(s):  
Landscape Ecology ◽  
Spatial Heterogeneity ◽  
Environmental Changes ◽  
Landscape Heterogeneity ◽  
Landscape Patterns ◽  
Global Changes ◽  
Time Lags ◽  
Temporal Heterogeneity ◽  
Landscape Models ◽  
Spatial And Temporal Heterogeneity

Although the concept of biodiversity emerged 30 years ago, patterns and processes influencing ecological diversity have been studied for more than a century. Historically, ecological processes tended to be considered as occurring in local habitats that were spatially homogeneous and temporally at equilibrium. Initially considered as a constraint to be avoided in ecological studies, spatial heterogeneity was progressively recognized as critical for biodiversity. This resulted, in the 1970s, in the emergence of a new discipline, landscape ecology, whose major goal is to understand how spatial and temporal heterogeneity influence biodiversity. To achieve this goal, researchers came to realize that a fundamental issue revolves around how they choose to conceptualize and measure heterogeneity. Indeed, observed landscape patterns and their apparent relationship with biodiversity often depend on the scale of observation and the model used to describe the landscape. Due to the strong influence of island biogeography, landscape ecology has focused primarily on spatial heterogeneity. Several landscape models were conceptualized, allowing for the prediction and testing of distinct but complementary effects of landscape heterogeneity on species diversity. We now have ample empirical evidence that patch structure, patch context, and mosaic heterogeneity all influence biodiversity. More recently, the increasing recognition of the role of temporal scale has led to the development of new conceptual frameworks acknowledging that landscapes are not only heterogeneous but also dynamic. The current challenge remains to truly integrate both spatial and temporal heterogeneity in studies on biodiversity. This integration is even more challenging when considering that biodiversity often responds to environmental changes with considerable time lags, and multiple drivers of global changes are interacting, resulting in non-additive and sometimes antagonistic effects. Recent technological advances in remote sensing, the availability of massive amounts of data, and long-term studies represent, however, very promising avenues to improve our understanding of how spatial and temporal heterogeneity influence biodiversity.

scholarly journals Spatial and Temporal Heterogeneity Creates a “Brown Tide” in Root Phenology and Nutrition

ISRN Ecology ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Sean C. P. Coogan ◽  
Scott E. Nielsen ◽  
Gordon B. Stenhouse
Keyword(s):  
Spatial Heterogeneity ◽  
Protein Content ◽  
Crude Protein ◽  
Brown Tide ◽  
Ground Vegetation ◽  
Grizzly Bears ◽  
Temporal Heterogeneity ◽  
Crude Protein Content ◽  
Spatial And Temporal Heterogeneity ◽  
Below Ground

Spatial and temporal heterogeneity in plant phenology and nutrition benefits herbivores by prolonging the period in which they can forage on nutritious plants. Landscape heterogeneity can therefore enhance population performance of herbivores and may be a critically important feature of their habitat. The benefits of resource heterogeneity over space and time should extend not only to large herbivores using above-ground vegetation but also to omnivores that utilize below-ground resources. We used generalized linear models to evaluate whether spatial heterogeneity influenced temporal variation in the crude protein content of alpine sweetvetch (Hedysarum alpinum) roots in west-central Alberta, Canada, thereby potentially offering nutritional benefits to grizzly bears (Ursus arctos). We demonstrated that temporal patterns in the crude protein content of alpine sweetvetch roots were influenced by spatial heterogeneity in annual growing season temperatures and soil moisture and nutrients. Spatial heterogeneity and asynchrony in the protein content of alpine sweetvetch roots likely benefit grizzly bears by prolonging the period they can forage on high quality resources. Therefore, we have presented evidence of what we termed a “brown wave” or “brown tide” in the phenology and nutrition of a below-ground plant resource, which is analogous to the previously described “green wave” in above-ground resources.

scholarly journals Spatial and Temporal Heterogeneity of Tumor-Infiltrating Lymphocytes in Advanced Urothelial Cancer

2022 ◽  
Vol 12 ◽  
Author(s):  
Sandra van Wilpe ◽  
Mark A. J. Gorris ◽  
Lieke L. van der Woude ◽  
Shabaz Sultan ◽  
Rutger H. T. Koornstra ◽  
...  
Keyword(s):  
Spatial Heterogeneity ◽  
Urothelial Cancer ◽  
Immune Cell ◽  
Checkpoint Inhibitors ◽  
Tumor Infiltrating Lymphocytes ◽  
Temporal Heterogeneity ◽  
Platinum Based Chemotherapy ◽  
Spatial And Temporal Heterogeneity ◽  
Cell Densities ◽  
Infiltrating Lymphocytes

Checkpoint inhibitors targeting PD-(L)1 induce objective responses in 20% of patients with metastatic urothelial cancer (UC). CD8+ T cell infiltration has been proposed as a putative biomarker for response to checkpoint inhibitors. Nevertheless, data on spatial and temporal heterogeneity of tumor-infiltrating lymphocytes in advanced UC are lacking. The major aims of this study were to explore spatial heterogeneity for lymphocyte infiltration and to investigate how the immune landscape changes during the disease course. We performed multiplex immunohistochemistry to assess the density of intratumoral and stromal CD3+, CD8+, FoxP3+ and CD20+ immune cells in longitudinally collected samples of 49 UC patients. Within these samples, spatial heterogeneity for lymphocyte infiltration was observed. Regions the size of a 0.6 tissue microarray core (0.28 mm2) provided a representative sample in 60.6 to 71.6% of cases, depending on the cell type of interest. Regions of 3.30 mm2, the median tumor surface area in our biopsies, were representative in 58.8 to 73.8% of cases. Immune cell densities did not significantly differ between untreated primary tumors and metachronous distant metastases. Interestingly, CD3+, CD8+ and FoxP3+ T cell densities decreased during chemotherapy in two small cohorts of patients treated with neoadjuvant or palliative platinum-based chemotherapy. In conclusion, spatial heterogeneity in advanced UC challenges the use of immune cell infiltration in biopsies as biomarker for response prediction. Our data also suggests a decrease in tumor-infiltrating T cells during platinum-based chemotherapy.

Burning history, time of burning, and year effects on plant community structure and heterogeneity in Fescue Prairie

Botany ◽  
2010 ◽  
Vol 88 (1) ◽  
pp. 1-12 ◽  
Author(s):  
D. V. Gross ◽  
J. T. Romo
Keyword(s):  
Community Structure ◽  
Species Composition ◽  
Spatial Heterogeneity ◽  
Plant Community ◽  
Canopy Cover ◽  
Plant Functional Groups ◽  
Plant Community Structure ◽  
Temporal Heterogeneity ◽  
Spatial And Temporal Heterogeneity ◽  
Festuca Hallii

Structure, as well as spatial and temporal heterogeneity in plant species composition were studied in a Festuca hallii (Vasey) Piper – dominated Prairie in Canada for 6 years following burning before, during, or after the growing season on sites burned 1× or 3×. Structure, spatial heterogeneity, and temporal heterogeneity were never (P > 0.05) influenced by the time of burning. Diversity and richness of graminoids, perennial forbs, and shrubs fluctuated among years after burning, but were unaffected by burning history. Excepting shrubs, canopy cover of plant functional groups positively correlated with precipitation. After a single burn, spatial heterogeneity in species composition increased with years after burning, indicating plant communities were becoming patchier, whereas those burned 3× did not change predictably through time. Spatial heterogeneity in species composition between consecutive years was positively correlated, but temporal heterogeneity in species composition did not correlate with spatial heterogeneity. Burning history and precipitation appear important in controlling the plant community structure and spatial heterogeneity in species composition in Fescue Prairie.

Bottlenecks in the Implementation of On-Site Wastewater Treatment Plants on a Large Scale in The Netherlands

1990 ◽  
Vol 22 (3-4) ◽  
pp. 291-298
Author(s):  
Frits A. Fastenau ◽  
Jaap H. J. M. van der Graaf ◽  
Gerard Martijnse
Keyword(s):  
Wastewater Treatment ◽  
The Netherlands ◽  
Large Scale ◽  
Wastewater Treatment Plants ◽  
Housing Stock ◽  
Research Work ◽  
Field Research ◽  
Domestic Wastewater ◽  
Research Programme ◽  
Definition Of

More than 95 % of the total housing stock in the Netherlands is connected to central sewerage systems and in most cases the wastewater is treated biologically. As connection to central sewerage systems has reached its economic limits, interest in on-site treatment of the domestic wastewater of the remaining premises is increasing. A large scale research programme into on-site wastewater treatment up to population equivalents of 200 persons has therefore been initiated by the Dutch Ministry of Housing, Physical Planning and Environment. Intensive field-research work did establish that the technological features of most on-site biological treatment systems were satisfactory. A large scale implementation of these systems is however obstructed in different extents by problems of an organisational, financial and/or juridical nature and management difficulties. At present research is carried out to identify these bottlenecks and to analyse possible solutions. Some preliminary results are given which involve the following ‘bottlenecks':-legislation: absence of co-ordination and absence of a definition of ‘surface water';-absence of subsidies;-ownership: divisions in task-setting of Municipalities and Waterboards; divisions involved with cost-sharing;-inspection; operational control and maintenance; organisation of management;-discharge permits;-pollution levy;-sludge disposal. Final decisions and practical elaboration of policies towards on-site treatment will have to be formulated in a broad discussion with all the authorities and interest groups involved.

scholarly journals Social Media in and Around a Temporary Large-Scale Refugee Shelter in the Netherlands

2021 ◽  
Vol 7 (2) ◽  
pp. 205630512110249
Author(s):  
Peer Smets ◽  
Younes Younes ◽  
Marinka Dohmen ◽  
Kees Boersma ◽  
Lenie Brouwer
Keyword(s):  
Social Media ◽  
The Netherlands ◽  
Crisis Communication ◽  
Asylum Seekers ◽  
Large Scale ◽  
State Policies ◽  
Refugee Crisis ◽  
Top Down ◽  
And Migration

During the 2015 refugee crisis in Europe, temporary refugee shelters arose in the Netherlands to shelter the large influx of asylum seekers. The largest shelter was located in the eastern part of the country. This shelter, where tents housed nearly 3,000 asylum seekers, was managed with a firm top-down approach. However, many residents of the shelter—mainly Syrians and Eritreans—developed horizontal relations with the local receiving society, using social media to establish contact and exchange services and goods. This case study shows how various types of crisis communication played a role and how the different worlds came together. Connectivity is discussed in relation to inclusion, based on resilient (non-)humanitarian approaches that link society with social media. Moreover, we argue that the refugee crisis can be better understood by looking through the lens of connectivity, practices, and migration infrastructure instead of focusing only on state policies.

TRANSFER-MATRIX STUDY OF NEGATIVE-FUGACITY SINGULARITY OF HARD-CORE LATTICE GAS

1999 ◽  
Vol 10 (04) ◽  
pp. 517-529 ◽  
Author(s):  
SYNGE TODO
Keyword(s):  
Large Scale ◽  
Lattice Gas ◽  
Central Charge ◽  
Hard Core ◽  
Universality Class ◽  
Two Dimensions ◽  
Square Lattice ◽  
Lattice Gas Models ◽  
Renormalization Technique ◽  
Phenomenological Renormalization

A singularity on the negative-fugacity axis of the hard-core lattice gas is investigated in terms of numerical diagonalization of large-scale transfer matrices. For the hard-square lattice gas, the location of the singular point [Formula: see text] and the critical exponent ν are accurately determined by the phenomenological renormalization technique as -0.11933888188(1) and 0.416667(1), respectively. It is also found that the central charge c and the dominant scaling dimension xσ are -4.399996(8) and -0.3999996(7), respectively. Similar analyses for other hard-core lattice-gas models in two dimensions are also performed, and it is confirmed that the universality between these models does hold. These results strongly indicate that the present singularity belongs to the same universality class as the Yang–Lee edge singularity.

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