scholarly journals The spatial evolution of young massive clusters. III. Effect of the Gaia filter on 2D spatial distribution studies

2021 ◽  
Author(s):  
A. S. M Buckner ◽  
Z. Khorrami ◽  
M. Gonzalez ◽  
S. L. Lumsden ◽  
P. Clark ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Evolution ◽  
Distribution Studies ◽  
Massive Clusters

Geostatistics as a tool to study mite dispersion in physic nut plantations

2015 ◽  
Vol 105 (4) ◽  
pp. 381-389 ◽  
Author(s):  
J.F. Rosado ◽  
M.C. Picanço ◽  
R.A. Sarmento ◽  
R.M. Pereira ◽  
M. Pedro-Neto ◽  
...  
Keyword(s):  
Experimental Data ◽  
Spatial Distribution ◽  
Pest Management ◽  
Mite Species ◽  
Spatial Distributions ◽  
Physic Nut ◽  
Distribution Models ◽  
Polyphagotarsonemus Latus ◽  
Mite Density ◽  
Distribution Studies

AbstractSpatial distribution studies in pest management identify the locations where pest attacks on crops are most severe, enabling us to understand and predict the movement of such pests. Studies on the spatial distribution of two mite species, however, are rather scarce. The mitesPolyphagotarsonemus latusandTetranychus bastosiare the major pests affecting physic nut plantations (Jatropha curcas). Therefore, the objective of this study was to measure the spatial distributions ofP. latusandT. bastosiin the physic nut plantations. Mite densities were monitored over 2 years in two different plantations. Sample locations were georeferenced. The experimental data were analyzed using geostatistical analyses. The total mite density was found to be higher when only one species was present (T. bastosi). When both the mite species were found in the same plantation, their peak densities occurred at different times. These mites, however, exhibited uniform spatial distribution when found at extreme densities (low or high). However, the mites showed an aggregated distribution in intermediate densities. Mite spatial distribution models were isotropic. Mite colonization commenced at the periphery of the areas under study, whereas the high-density patches extended until they reached 30 m in diameter. This has not been reported forJ. curcasplants before.

Geostatistical Assessment of Frankliniella schultzei (Thysanoptera: Thripidae) Spatial Distribution in Commercial Watermelon Crops

2019 ◽  
Author(s):  
Poliana Silvestre Pereira ◽  
Renato Almeida Sarmento ◽  
Carlos Henrique Oliveira Lima ◽  
Cleovan Barbosa Pinto ◽  
Gerson Adriano Silva ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Opposite Direction ◽  
Insect Pests ◽  
Citrullus Lanatus ◽  
Dispersal Patterns ◽  
Frankliniella Schultzei ◽  
The World ◽  
The Common ◽  
Distribution Studies ◽  
Surrounding Areas

Abstract Spatial distribution studies of insect pests make it possible to determine their colonization and dispersal patterns. Watermelon (Citrullus lanatus (Thunb.) Matsum. et Nakai) is among the most frequently consumed fruits in the world, and the common blossom thrips, Frankliniella schultzei (Trybom) (Thysanoptera: Thripidae), is one of the most important insect pests of this plant. The objective of this study was to determine the spatial distribution of F. schultzei in commercial watermelon crops using geostatistics. The studied F. schultzei populations presented an aggregated distribution. The colonization of thrips began at the borders of the crops, especially in the areas located in the opposite direction to that of the prevailing winds. The highest densities of thrips occurred in crops that had cucurbits in the surrounding areas. When monitoring for F. schultzei populations, greater attention should be given to sampling that part of the crop located in the opposite direction to that of the prevailing winds because this is where colonization begins. Even at low densities, the aggregation points of thrips in the crop should be located and controlled so that they do not cause damage. In sampling programs for F. schultzei, samples should be taken at distances greater than 9 m apart because this is the distance up to which densities of this species show spatial dependence. Planting watermelon crops close to other cucurbits should be avoided, as these alternate hosts may act as a source of infestation by this pest.

Spatial distribution studies of thermoluminescence using a high-gain image intensifier

Nature ◽  
1980 ◽  
Vol 284 (5751) ◽  
pp. 42-44 ◽  
Author(s):  
Alan J. Walton ◽  
N. C. Debenham
Keyword(s):  
Spatial Distribution ◽  
Image Intensifier ◽  
High Gain ◽  
Distribution Studies

scholarly journals Temporal and Spatial Evolution Analysis of Earthquake Events in California and Nevada Based on Spatial Statistics

2021 ◽  
Vol 10 (7) ◽  
pp. 465
Author(s):  
Weifeng Shan ◽  
Zhihao Wang ◽  
Yuntian Teng ◽  
Maofa Wang
Keyword(s):  
Spatial Distribution ◽  
Local Governments ◽  
Weighted Average ◽  
Earthquake Risk ◽  
Spatial Evolution ◽  
Temporal And Spatial Evolution ◽  
The North ◽  
Evolution Analysis ◽  
Temporal And Spatial ◽  
New Perspective

Studying the temporal and spatial evolution trends in earthquakes in an area is beneficial for determining the earthquake risk of the area so that local governments can make the correct decisions for disaster prevention and reduction. In this paper, we propose a new method for analyzing the temporal and spatial evolution trends in earthquakes based on earthquakes of magnitude 3.0 or above from 1980 to 2019 in California and Nevada. The experiment’s results show that (1) the frequency of earthquake events of magnitude 4.5 or above present a relatively regular change trend of decreasing–rising in this area; (2) by using the weighted average center method to analyze the spatial concentration of earthquake events of magnitude 3.0 or above in this region, we find that the weighted average center of the earthquake events in this area shows a conch-type movement law, where it moves closer to the center from all sides; (3) the direction of the spatial distribution of earthquake events in this area shows a NW–SE pattern when the standard deviational ellipse (SDE) method is used, which is basically consistent with the direction of the San Andreas Fault Zone across the north and south of California; and (4) the spatial distribution pattern of the earthquake events in this region is found to be clustered using the global spatial autocorrelation analysis method. This study provides a new perspective for the exploration of the temporal and spatial evolution trends in earthquakes and understanding the earthquake risk in an area.

scholarly journals Can Bayesian phylogeography reconstruct migrations and expansions in linguistic evolution?

2021 ◽  
Vol 8 (1) ◽  
pp. 201079
Author(s):  
Nico Neureiter ◽  
Peter Ranacher ◽  
Rik van Gijn ◽  
Balthasar Bickel ◽  
Robert Weibel
Keyword(s):  
Spatial Distribution ◽  
Simulation Study ◽  
Historical Linguistics ◽  
State Of The Art ◽  
Descriptive Statistics ◽  
The Other ◽  
Spatial Evolution ◽  
Spatial Processes ◽  
The One ◽  
Linguistic Evolution

Bayesian phylogeography has been used in historical linguistics to reconstruct homelands and expansions of language families, but the reliability of these reconstructions has remained unclear. We contribute to this discussion with a simulation study where we distinguish two types of spatial processes: migration , where populations or languages leave one place for another, and expansion , where populations or languages gradually expand their territory. We simulate migration and expansion in two scenarios with varying degrees of spatial directional trends and evaluate the performance of state-of-the-art phylogeographic methods. Our results show that these methods fail to reconstruct migrations, but work surprisingly well on expansions, even under severe directional trends. We demonstrate that migrations and expansions have typical phylogenetic and spatial patterns, which in the one case inhibit and in the other facilitate phylogeographic reconstruction. Furthermore, we propose descriptive statistics to identify whether a real sample of languages, their relationship and spatial distribution, better fits a migration or an expansion scenario. Bringing together the results of the simulation study and theoretical arguments, we make recommendations for assessing the adequacy of phylogeographic models to reconstruct the spatial evolution of languages.

scholarly journals Spatial Evolution of Urban Expansion in the Beijing–Tianjin–Hebei Coordinated Development Region

2021 ◽  
Vol 13 (3) ◽  
pp. 1579
Author(s):  
Zhanzhong Tang ◽  
Zengxiang Zhang ◽  
Lijun Zuo ◽  
Xiao Wang ◽  
Xiaoli Zhao ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
High Speed ◽  
Urban Expansion ◽  
Urban Land ◽  
Main Trend ◽  
Spatial Evolution ◽  
Coordinated Development ◽  
Development Region ◽  
The Difference ◽  
Trend Direction

Against the background of coordinated development of the Beijing–Tianjin–Hebei region (BTH), it is of great significance to quantitatively reveal spatiotemporal dynamics of urban expansion for optimizing the layout of urban land across regions. However, the urban expansion characteristics, types and trends, and spatial coevolution (including urban land, GDP, and population) have not been well investigated in the existing research studies. This study presents a new spatial measure that describes the difference of the main trend direction. In addition, we also introduce a new method to classify an urban expansion type based on other scholars. The results show the following: (1) The annual urban expansion area (UEA) in Beijing and Tianjin has been ahead of that in Hebei; the annual urban expansion rate (UER) gradually shifted from the highest in megacities to the highest in counties; the high–high clusters of the UEA presented an evolution from a “seesaw” pattern to a “dumbbell” pattern, while that of the UER moved first from Beijing to Tianjin and eventually to Hebei. (2) Double high speed for both UEA and UER was the main extension type; most cities presented a U-shaped trend. (3) Qinhuangdao has the largest difference between the main trend direction of spatial distribution of urban land, GDP and population; the spatial distribution of GDP is closer to that of urban land than population. (4) The area and proportion of land occupied by urban expansion varied greatly across districts/counties. BTH experienced dramatic urban expansion and has a profound impact on land use. These research results can provide a data basis and empirical reference for territorial spatial planning.

Preliminary Screening of Mosquito Spatial Distribution in Togo: With Special Focus on the Aedes (Diptera: Culicidae) Species

2019 ◽  
Vol 56 (4) ◽  
pp. 1154-1158
Author(s):  
Hala S Thabet ◽  
Emadeldin Y Fawaz ◽  
Kossi Badziklou ◽  
Reham A Tag ElDin ◽  
Rania M Kaldas ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
West Africa ◽  
Virus Transmission ◽  
First Record ◽  
Special Focus ◽  
Humid Climate ◽  
Preliminary Screening ◽  
Negative Results ◽  
Aedes Mosquitoes ◽  
Distribution Studies

Abstract The Togolese Republic has a tropical and humid climate which constitutes an ideal environment for mosquitoes to breed and transmit diseases. The Aedes mosquito is known to transmit yellow fever (YF), dengue, chikungunya, and Zika viruses in West Africa. Togo has been suffering from YF virus transmission, despite vaccination efforts. Unfortunately, there is scarcity in the data that reflect mosquito spatial distribution in Togo, specifically possible YF vectors. In the current study, mosquito surveillance efforts targeted areas with confirmed YF cases between July and August 2012. Indoor mosquitoes were collected using knockdown insecticide spraying, whereas Biogents (BG) traps were used to collect outdoor mosquito adults. Mosquito larval surveillance was conducted as well. In total, 17 species were identified. This investigation revealed the presence of medically important vectors in Togo, especially the Aedes aegypti (Linnaeus) (Diptera: Culicidae) which was collected in the four regions. Screening of all pools of female Aedes mosquitoes for YF, by real-time PCR, showed negative results. This is the first record for Coquillettidia flavocincta (Edwards) (Diptera: Culicidae) species in West Africa. This preliminary work serves as a baseline for further mosquito distribution studies in Togo.

scholarly journals Study on the Driven Mechanism of Watershed Hydrological Drought Based on Geomorphological Spatial Distribution Pattern: A Case Study of Guizhou, China

2021 ◽  
Author(s):  
Zhonghua He ◽  
Hong Liang ◽  
zhaohui Yang
Keyword(s):  
Spatial Distribution ◽  
Distribution Pattern ◽  
Hydrological Drought ◽  
Guizhou Province ◽  
Spatial Evolution ◽  
The West ◽  
The North ◽  
Driving Mechanisms ◽  
Hydrological Droughts

In recent years, hydrological drought has become more and more frequent, which has caused serious ecological and environmental problems. This paper is taking Guizhou province of China as an example to analyze the geomorphologic distribution and temporal-spatial evolution of hydrological droughts, and to study driving mechanisms of both the rainfall in drought periods and geomorphologic factors on the hydrological droughts, based on the hydrometeorological data from the 2000 to 2010, and the TM and DEM data. The results show that (1) the rainfall and its temporal-spatial distribution have less impacts on the hydrological droughts and its temporal-spatial distribution, showing the obvious phase characteristics, and the regional hydrological droughts are more serious in the south than in the north, and the less serious in the east than in the west; and (3) in terms of the overall distribution of landform types, the mountain, hill and basin have less impacts on hydrological droughts; in terms of the distribution of single geomorphic type, hydrological droughts are significantly influenced by the high-medium mountain, deep-high hill and high basin, where the hydrological droughts are relatively lighter. While there are more serious areas in the low basin, shallow-low hill and low mountain.

Research on Spatial Evolution Mechanics of Urban Group in the Poyang Lake Ecological Economic Zone Based on RS

2011 ◽  
Vol 374-377 ◽  
pp. 2188-2192
Author(s):  
Chuan Li Liu ◽  
Qiu Min Liao
Keyword(s):  
Spatial Distribution ◽  
Spatial Structure ◽  
Poyang Lake ◽  
Dynamic Change ◽  
Present Situation ◽  
Structure Evolution ◽  
Spatial Evolution ◽  
Ecological Economic ◽  
Urban Group ◽  
Economic Zone

This paper first gives an introduction on the present study situation of urban group spatial structure evolution, then extracts the urban group spatial distribution information in Poyang Lake Ecological Economic Zone, and monitors in dynamic change of urban group spatial evolution from 1990 to 2009. Later, it analyzes the present situation and the reason of urban group spatial structure in Poyang Lake Ecological Economic Zone, and finally, presents some suggestion on how to over-all optimize and regulate the urban group spatial structure in Poyang Lake Ecological Economic Zone.

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