scholarly journals Estimating the relationship between abundance and distribution

2012 ◽  
Vol 69 (2) ◽  
pp. 382-397 ◽  
Author(s):  
Anna Rindorf ◽  
Peter Lewy
Keyword(s):  
Spatial Distribution ◽  
Count Data ◽  
Gini Index ◽  
Euclidean Distance ◽  
Gadus Morhua ◽  
Lorenz Curves ◽  
Centre Of Gravity ◽  
Unbiased Estimates ◽  
Abundance And Distribution ◽  
The Relationship

Numerous studies investigate the relationship between abundance and distribution using indices reflecting one of the three aspects of distribution: proportion of area occupied, aggregation, and geographical range. Using simulations and analytical derivations, we examine whether these indices provide unbiased estimates of the relationship when estimated from count data. The indices investigated include the proportion of empty samples, the proportion of structurally empty samples, Lloyds index of patchiness, measures derived from Lorenz curves (such as D95 and the Gini index), and measures based on Euclidean distance to the centre of gravity of the spatial distribution. Only the proportion of structurally empty areas, Lloyds index, and indices of the distance to the centre of gravity of the spatial distribution are unbiased at all levels of abundance. The remaining indices generate relationships between abundance and distribution even in cases where no underlying relationships exists, although the problem decreases for measures derived from Lorenz curves when samples contain more than four individuals on average. To illustrate the problem, the indices are applied to juvenile North Sea cod, Gadus morhua .

scholarly journals Do North Sea cod (Gadus morhua) fisheries maintain high catch rates at low stock size?

2008 ◽  
Vol 65 (9) ◽  
pp. 1800-1813 ◽  
Author(s):  
Anna Rindorf ◽  
Bo Sølgaard Andersen
Keyword(s):  
Spatial Distribution ◽  
North Sea ◽  
Gadus Morhua ◽  
Commercial Fishing ◽  
Stock Size ◽  
Two Factors ◽  
Cod Fisheries ◽  
Catch Rates ◽  
Fishing Fleets ◽  
The Relationship

This study presents an investigation of the relationship between stock size of North Sea cod ( Gadus morhua ) and catch rates in seven commercial fishing fleets. The shape of the relationship was estimated using a new model allowing both density-dependent changes in catchability and bias in the assessment biomass estimates. Catchability in fisheries targeting a mixed species composition either remained constant or decreased with decreasing stock size, whereas catchability in targeted cod fisheries increased with decreasing stock size. However, even in the cases where catchability increased, the change was insufficient to compensate for the decrease in stock size, and catch rates of all fleets decreased. Two factors that could lead to nonconstant catchability were investigated: (i) the presence of a decoupling between stock size and density in high-density areas and (ii) the presence of concurrent shifts in the spatial distribution of the cod stock and the cod fishery. No evidence of the former was found, but there was a northern shift in the spatial distribution of both effort and the cod stock.

Conclusion

2017 ◽  
Author(s):  
Frédéric Grare
Keyword(s):  
United States ◽  
The United States ◽  
The Political ◽  
Slow Pace ◽  
Centre Of Gravity ◽  
The Us ◽  
The Future ◽  
Economic Interaction ◽  
The Asymmetry ◽  
The Relationship

India’s relationship with the United States remains crucial to its own objectives, but is also ambiguous. The asymmetry of power between the two countries is such that the relationship, if potentially useful, is not necessary for the United States while potentially risky for India. Moreover, the shift of the political centre of gravity of Asia — resulting from the growing rivalry between China and the US — is eroding the foundations of India’s policy in Asia, while prospects for greater economic interaction is limited by India’s slow pace of reforms. The future of India-US relations lies in their capacity to evolve a new quid pro quo in which the US will formulate its expectations in more realistic terms while India would assume a larger share of the burden of Asia’ security.

scholarly journals Insights Into the Correspondence Between Land Use Pattern and Spatial Distribution of Rail Transit Services

2021 ◽  
Author(s):  
Zhongqi Wang ◽  
Qi Han ◽  
Bauke de Vries ◽  
Li Dai
Keyword(s):  
Land Use ◽  
Spatial Distribution ◽  
Operations Management ◽  
Latent Variable ◽  
Structural Equation ◽  
Equation Modeling ◽  
Rail Transit ◽  
Land Use Patterns ◽  
Transit Services ◽  
The Relationship

AbstractThe identification of the relationship between land use and transport lays the foundation for integrated land use and transport planning and management. This work aims to investigate how rail transit is linked to land use. The research on the relationship between land use and rail-based transport is dominated by the impacts of rail projects on land use, without an in-depth understanding of the reverse. However, it is important to note that issues of operation management rather than new constructions deserve greater attention for regions with established rail networks. Given that there is a correspondence between land use patterns and spatial distribution of heavy railway transit (HRT) services at such regions, the study area (i.e., the Netherlands) is partitioned by the Voronoi diagram of HRT stations and the causal relationship between land use and HRT services is examined by structural equation modeling (SEM). The case study of Helmond (a Dutch city) shows the potential of the SEM model for discussing the rail station selection problem in a multiple transit station region (MTSR). Furthermore, in this study, the node place model is adapted with the derivatives of the SEM model (i.e., the latent variable scores for rail service levels and land use characteristics), which are assigned as node and place indexes respectively, to analyze and differentiate the integration of land use and HRT services at the regional level. The answer to whether and how land use affects rail transit services from this study strengthens the scientific basis for rail transit operations management. The SEM model and the modified node place model are complementary to be used as analytical and decision-making tools for rail transit-oriented regional development.

scholarly journals Double parton distributions in the pion from lattice QCD

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Gunnar S. Bali ◽  
Luca Castagnini ◽  
Markus Diehl ◽  
Jonathan R. Gaunt ◽  
Benjamin Gläßle ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Lattice Qcd ◽  
Quark Mass ◽  
Matrix Elements ◽  
Parton Distributions ◽  
Almost All ◽  
The Relationship

Abstract We perform a lattice study of double parton distributions in the pion, using the relationship between their Mellin moments and pion matrix elements of two local currents. A good statistical signal is obtained for almost all relevant Wick contractions. We investigate correlations in the spatial distribution of two partons in the pion, as well as correlations involving the parton polarisation. The patterns we observe depend significantly on the quark mass. We investigate the assumption that double parton distributions approximately factorise into a convolution of single parton distributions.

scholarly journals Men's health: non-communicable chronic diseases and social vulnerability

2016 ◽  
Vol 24 (0) ◽  
Author(s):  
Daniele Natália Pacharone Bertolini Bidinotto ◽  
Janete Pessuto Simonetti ◽  
Silvia Cristina Mangini Bocchi
Keyword(s):  
Spatial Distribution ◽  
Chronic Diseases ◽  
Glucose Intolerance ◽  
Social Vulnerability ◽  
Medical Records ◽  
Urban Areas ◽  
International Classification Of Diseases ◽  
Classification Of Diseases ◽  
Mixed Approach ◽  
The Relationship

ABSTRACT Objectives: to evaluate the relationship between absences in scheduled appointments and the number of non-communicable chronic diseases and to investigate the relationship between spatial distribution of these diseases and social vulnerability, using geoprocessing. Method: a quantitative study of sequential mixed approach by analyzing 158 medical records of male users to relate the absences and 1250 medical records for geoprocessing Results: the higher the number of absences in the scheduled medical appointments, the less were the number of non-communicable chronic diseases and the ones listed in the International Classification of Diseases in single men. There were 21 significant geostatistically cases of glucose intolerance in the urban area. Of these, 62% lived in a region with a social vulnerability rating of Very Low, Medium 19%, 14% Low and 5% High. Conclusion: it was observed that the older the men, the greater is the number of chronic diseases and the less they miss scheduled appointments. Regarding the use of geoprocessing, we obtained a significant number of cases of glucose intolerance in urban areas, the majority classified as Very Low social vulnerability. It was possible to relate the spatial distribution of these diseases with the social vulnerability classification; however, it was not possible to perceive a relationship of them with the higher rates of social vulnerability.

scholarly journals Spatial distribution of sunflower cultivars and the relationship between growth features

2012 ◽  
Vol 43 (2) ◽  
pp. 338-345 ◽  
Author(s):  
Thomas Newton Martin ◽  
Paulo Sérgio Pavinato ◽  
Leandro Homrich Lorentz ◽  
Renice Paula Zielinski ◽  
Rosana Refatti
Keyword(s):  
Spatial Distribution ◽  
Growth Features ◽  
The Relationship

Potential contact statistics for measuring scale-dependent spatial pattern and association: an example of northern cod (Gadus morhua) and capelin (Mallotus villosus)

2000 ◽  
Vol 57 (7) ◽  
pp. 1355-1368 ◽  
Author(s):  
Richard L O'Driscoll ◽  
David C Schneider ◽  
George A Rose ◽  
George R Lilly
Keyword(s):  
Spatial Distribution ◽  
Spatial Pattern ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Simulated Data ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Mallotus Villosus ◽  
Capelin Mallotus Villosus ◽  
Potential Contact

Analysis of simulated data showed that potential contact statistics could be used to describe spatial pattern in sample density data. Potential contact is a new method, analogous to Ripley's K function for mapped point pattern analysis. Potential contact can be used to describe spatial pattern and association over a range of scales without grouping data and is robust against the presence of zeros. The statistical output is ecologically interpretable, as a measure of the degree of contact between individuals. This new technique was applied to examine changes in the spatial distribution of Atlantic cod (Gadus morhua) off Newfoundland, Canada, from 1985 to 1994, a period that encompassed a collapse of the cod stock. Sample data from bottom-trawl surveys indicated that cod were aggregated in patches with dimensions of 100-250 km. During the period of cod decline in the 1990s, spatial structure changed in three ways: the number of patches decreased, patch size shrank, and contact with conspecifics at small (10-20 km) scales fell. Cod were broadly associated with capelin (Mallotus villosus), a major prey species. Spatial distribution of capelin changed over the same time period as changes in cod distribution, and there was no evidence that contact between cod and capelin decreased.

scholarly journals The Relationship Between Cloud Cover and Outgoing Longwave Radiation in the Southern of Vietnam

2018 ◽  
Vol 34 (1S) ◽  
Author(s):  
Chu Thi Thu Huong ◽  
Bui Thi Hop ◽  
Tran Dinh Linh ◽  
Vu Thanh Hang
Keyword(s):  
Spatial Distribution ◽  
Rainy Season ◽  
Outgoing Longwave Radiation ◽  
Cloud Cover ◽  
Temporal Evolution ◽  
El Nino ◽  
Longwave Radiation ◽  
Downward Trend ◽  
La Nina ◽  
The Relationship

Abstract: Based on the data that has the resolution is 1,00×1,00of the Outgoing Longwave Radiation (OLR) and the cloud cover from NCEP/NCAR in the 1981 – 2012 period, the relationship between the cloud cover and the OLR in the Southern of Vietnam wasinvestigated when analyze and compare the spatial distribution, temporal evolution and their correlation. The results show that the characteristics of the spatial distribution and the year cycle of cloud cover and OLR are inversely correlated. The region or time that the cloud cover is great, the OLR is small and vice versa. In the Southern of Vietnam, the OLR value isgreatest(or smallest) in the dry (or rainy) season and in the El-Nino (La-Nina) years. In addition, during the 1981-2012period, the OLR in this region shows a downward trend about 3.6 W/m2/decade, while the cloud cover tends to increase by 0.2%/decade. Keywords: Cloud cover, Outgoing Longwave Radiation, the Southern of Vietnam.

scholarly journals Correlation of environmental factors and spatial distribution of moluscs communities in mangrove reboisation areas of Seribu Islands, Indonesia

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Syahrial Syahrial ◽  
Eryc Pranata ◽  
Hendri Susilo
Keyword(s):  
Principal Component Analysis ◽  
Spatial Distribution ◽  
Environmental Factors ◽  
Principal Component ◽  
Quality Standard ◽  
Small Plot ◽  
Line Transects ◽  
Relationship Of ◽  
The Relationship ◽  
Mangrove Reforestation

Mangrove reforestation is often carried out in various regions or regions, but information about the relationship of environmental factors and the distribution of fauna associations is still very minimal. The Principal Component Analysis (PCA) study on the correlation of environmental factors and the spatial distribution of the molusks community in the Seribu Islands mangrove reforestation area was conducted in March 2014 with the aim of analyzing environmental factors for the diversity and presence of the molusks. Environmental factors are measured insecurely, while the moluccan community is collected by making line transects and plots measuring 10 x 10 m2 and in the size of 10 x 10 m2, a small plot of 1 x 1 m2 is made. The results of the study show that environmental factors are not so different between stations and do not exceed the quality standard for the lives of 4 species of mollusks, where the parameters of aquatic pH are the environmental factors that most influence their distribution.Keywords: environmental factors, distribution, mollusks community, mangrove reforestation, Seribu Islands

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