scholarly journals Spatial distribution of inselbergs in Igbajo district of Western Nigeria

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Matthew Afolabi ◽  
Olayinka Ogunkoya
Keyword(s):  
Spatial Distribution ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
P Value ◽  
Distribution Analysis ◽  
Nearest Neighbour ◽  
Test Statistic ◽  
Drainage Pattern ◽  
River Drainage ◽  
Significant Difference

Inselbergs’ spatial distribution is the primary focus of this study carried out in Igbajo District of Western Nigeria. Additionally, a common hypothesis that spatial distribution of inselbergs is informed by the differing modes of evolution of the landforms was also examined. Inselbergs are defined as points on the topographic sheet and satellite terrain elevation data and are thereafter subjected to point pattern analysis. Two point pattern analyses: Poisson Probability Distribution (PPD) and Nearest Neighbour Analysis (NNA) are employed to determine the pattern of inselberg distribution over space. Additional analysis focused on the relationship between regional river drainage and inselbergs’ spatial distribution. Findings from the study confirmed that inselberg form a clustered distribution. The PPD results suggest that the observed distribution of inselbergs has a statistically significant difference from the expected pattern generated by the random process (c2 test statistic = 49.82 >  =12.59 (α= 0.05) and 16.81 (α= 0.01). Similarly, the NNA with a R < 1 (Nearest Neighbour Ratio, R = 0.92) and p-value = -2.52, also indicated a clustered distribution. Analysis of river drainage pattern similarly revealed a cluster of high rising landforms situated in the centre of the regional watershed. It is concluded that inselberg distribution in the study area is clustered although the observed pattern does not necessarily validate or invalidate the alternative evolutionary theories.

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 Characteristics and factors influencing the natural regeneration of Larix principis-rupprechtii seedlings in northern China

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12327
Author(s):  
Weiwen Zhao ◽  
Wenjun Liang ◽  
Youzhi Han ◽  
Xi Wei
Keyword(s):  
Spatial Distribution ◽  
Natural Regeneration ◽  
Pair Correlation ◽  
Principal Component ◽  
Northern China ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Adult Trees ◽  
Herb Diversity ◽  
Univariate Distribution

Larix principis-rupprechtii is an important and widely distributed species in the mountains of northern China. However, it has inefficient natural regeneration in many stands and difficulty recruiting seedlings and saplings. In this study, we selected six plots with improved naturally-regenerated L. principis-rupprechtii seedlings. A point pattern analysis (pair-correlation function) was applied to identify the spatial distribution pattern and correlation between adult trees and regenerated seedlings mapped through X/Y coordinates. Several possible influencing factors of L. principis-rupprechtii seedlings’ natural regeneration were also investigated. The results showed that the spatial distribution patterns of Larix principis-rupprechtii seedlings were concentrated 0–5 m around adult trees when considering the main univariate distribution type of regeneration. There was a positive correlation at a scale of 1.5–4 m between seedlings and adult trees according to bivariate analyses. When the scale was increased, these relationships were no longer significant. Generally, adult trees raised regenerated L. principis-rupprechtii seedlings at a scale of 1.5–4 m. Principal component analysis showed that the understory herb diversity and litter layer had a negative correlation with the number of regenerated seedlings. There was also a weak relationship between regenerated numbers and canopy density. This study demonstrated that the main factors promoting natural regeneration were litter thickness, herb diversity, and the distance between adult trees and regenerated seedlings. Additionally, these findings will provide a basis for the late-stage and practical management of natural regeneration in northern China’s mountain ranges.

scholarly journals Analyzing the Spatial Distribution of Drumlins: A Two-Phase Mosaic Approach

1984 ◽  
Vol 30 (106) ◽  
pp. 302-307
Author(s):  
B. N. Boots ◽  
R. K. Burns
Keyword(s):  
Spatial Distribution ◽  
Pattern Analysis ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Statistical Bias ◽  
Two Phase ◽  
Alternative Approach ◽  
Mosaic Approach ◽  
The Individual

AbstractResearchers have analyzed various properties of drumlins within individual drumlin fields in order to provide evidence to help in identifying the processes involved in drumlin formation. One property which has been examined is the spatial distribution of drumlins within a field. Traditionally, in such endeavours the individual drumlins have been represented as points and their distribution examined using techniques of point-pattern analysis. We suggest that not only is such a representation inappropriate at this scale, it also introduces statistical bias which makes the results of such analyses questionable. Consequently, we propose an alternative approach which involves representing individual drumlins as areal phenomena and considering their pattern as a two-phase mosaic. The advantages of such an approach are discussed and it is illustrated by applying it to two different drumlin fields.

scholarly journals Predicting Growing Stock Volume of Eucalyptus Plantations Using 3-D Point Clouds Derived from UAV Imagery and ALS Data

Forests ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 905 ◽  
Author(s):  
Guerra-Hernández ◽  
Cosenza ◽  
Cardil ◽  
Silva ◽  
Botequim ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Basal Area ◽  
Remote Sensing Data ◽  
Tree Height ◽  
Point Clouds ◽  
Volume Estimation ◽  
P Value ◽  
Test Statistic ◽  
Individual Tree ◽  
Significant Difference

Estimating forest inventory variables is important in monitoring forest resources and mitigating climate change. In this respect, forest managers require flexible, non-destructive methods for estimating volume and biomass. High-resolution and low-cost remote sensing data are increasingly available to measure three-dimensional (3D) canopy structure and to model forest structural attributes. The main objective of this study was to evaluate and compare the individual tree volume estimates derived from high-density point clouds obtained from airborne laser scanning (ALS) and digital aerial photogrammetry (DAP) in Eucalyptus spp. plantations. Object-based image analysis (OBIA) techniques were applied for individual tree crown (ITC) delineation. The ITC algorithm applied correctly detected and delineated 199 trees from ALS-derived data, while 192 trees were correctly identified using DAP-based point clouds acquired from Unmanned Aerial Vehicles (UAV), representing accuracy levels of respectively 62% and 60%. Addressing volume modelling, non-linear regression fit based on individual tree height and individual crown area derived from the ITC provided the following results: Model Efficiency (Mef) = 0.43 and 0.46, Root Mean Square Error (RMSE) = 0.030 m3 and 0.026 m3, rRMSE = 20.31% and 19.97%, and an approximately unbiased results (0.025 m3 and 0.0004 m3) using DAP and ALS-based estimations, respectively. No significant difference was found between the observed value (field data) and volume estimation from ALS and DAP (p-value from t-test statistic = 0.99 and 0.98, respectively). The proposed approaches could also be used to estimate basal area or biomass stocks in Eucalyptus spp. plantations.

scholarly journals The Method and Results of a Treatment Targeting SARS-CoV-2-Activated Inflammasomes

2021 ◽  
Author(s):  
Jong Hoon Lee ◽  
Badar Kanwar ◽  
Chul Joong Lee ◽  
Jenny Balentine ◽  
Asif Khattak ◽  
...  
Keyword(s):  
Controlled Trial ◽  
P Value ◽  
Test Statistic ◽  
Chi Square ◽  
Exact Test ◽  
Pyrin Domain ◽  
Significant Difference ◽  
Chemically Reacting ◽  
Second Period ◽  
Receptor Family

Abstract Background Clinicians considered dapsone administration to treat SARS-CoV-2 inflammasome. Dapsone is helpful in the molecular regulation of Nod-like receptor family pyrin domain-containing 3 (NLRP3).Objective To study the targeting of NLRP3 itself or up-/downstream factors of the NLRP3 inflammasome by dapsone must be responsible for its observed preventive effects, functioning as a competitor.Methods This is a randomized controlled trial (RCT). We set out to use objective criteria of improvement, such as A. a reduction in the FIO2 requirement and B. a decrease in the progression of hypoxia. We treated the patients with standard COVID-19 acute respiratory distress syndrome (ARDS) treatment with dapsone. The RCT results were analyzed.Results ARDS progression was blocked in 17 of 19 total patients at the first period. The 44 (trial 22/ control 22) subjects were analyzed during the second period. The chi-square statistic is 5.1836. The p-value is .02280. (RR 0.21, OR 0.1) Fisher's exact test statistic value is 0.0433. (The result is significant at p < .05) (RR 0.15, OR 0) It is significant at the ARDS onset stage.Conclusion There was a significant difference in dapsone treatment results in the ARDS-onset group. We confirmed that dapsone clinically treated the onset of ARDS by targeting SARS-CoV-2-activated inflammasomes. Like chemically reacting substances, inflammasome and dapsone compete, proving that it is effective in early ARDS. ClinicalTrials.gov Identifier NCT04918914

scholarly journals Spatial distribution patterns of plague hosts: point pattern analysis of the burrows of great gerbils in Kazakhstan

2015 ◽  
Vol 42 (7) ◽  
pp. 1281-1292 ◽  
Author(s):  
Liesbeth I. Wilschut ◽  
Anne Laudisoit ◽  
Nelika K. Hughes ◽  
Elisabeth A. Addink ◽  
Steven M. de Jong ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Pattern Analysis ◽  
Distribution Patterns ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Spatial Distribution Patterns

scholarly journals Analyzing the Spatial Distribution of Drumlins: A Two-Phase Mosaic Approach

1984 ◽  
Vol 30 (106) ◽  
pp. 302-307 ◽  
Author(s):  
B. N. Boots ◽  
R. K. Burns
Keyword(s):  
Spatial Distribution ◽  
Pattern Analysis ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Statistical Bias ◽  
Two Phase ◽  
Alternative Approach ◽  
Mosaic Approach ◽  
The Individual

AbstractResearchers have analyzed various properties of drumlins within individual drumlin fields in order to provide evidence to help in identifying the processes involved in drumlin formation. One property which has been examined is the spatial distribution of drumlins within a field. Traditionally, in such endeavours the individual drumlins have been represented as points and their distribution examined using techniques of point-pattern analysis. We suggest that not only is such a representation inappropriate at this scale, it also introduces statistical bias which makes the results of such analyses questionable. Consequently, we propose an alternative approach which involves representing individual drumlins as areal phenomena and considering their pattern as a two-phase mosaic. The advantages of such an approach are discussed and it is illustrated by applying it to two different drumlin fields.

scholarly journals Proliferation of household waste irregular dumpsites in Niger Delta region (Nigeria): unsustainable public health monitoring and future restitution

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
Donatus A. Okpara ◽  
Marianna Kharlamova ◽  
Vladimir Grachev
Keyword(s):  
Spatial Distribution ◽  
Negative Impact ◽  
Point Pattern Analysis ◽  
Household Waste ◽  
Point Pattern ◽  
Governmental Agencies ◽  
Public Health Monitoring ◽  
Niger Delta Region ◽  
Waste Dumps ◽  
Disease Occurrence

AbstractInadequate collection and improper disposal of municipal waste have a direct negative impact on cities. Disease occurrence in Obio-Akpor (Port Harcourt metropolis, Nigeria) was suspected and linked to the proliferation of dumpsites and proximity to residential households. Evidence showed frequent incidence of diseases outbreak coupled with the topographic coastal nature and the morphological propelling dynamics of sediments transport in the area assisting the situation. The main objective of this study was to assess how the spatial distribution of irregular dumpsites is linked to the disease occurrence (cholera, diarrhoea and malaria) in the community. The data used for the study was obtained through questionnaires administrated at the hospitals, use of GPS for locating disease incidences and waste dumps, interviews and observations. Point pattern analysis using the G-function and the K-function was employed in analyzing the spatial distribution of dumpsites and disease incidences. Correlation tests were performed to test for the relationship between disease incidences and presence of dumpsites. The results showed that there was a significant relationship (p < 0.05) between disease incidences and presence of dumpsites. It was also observed that diseases could occur in areas where dumpsites were not present as cholera and diarrhoea are contagious but malaria is not, though it spreads. The study will be beneficial to governmental agencies, waste managers, institutions, environmentalists, health, social workers and future researchers.

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