scholarly journals Spatial Movement Patterns and Local Co-Occurrence of Nutria Individuals in Association with Habitats Using Geo-Self-Organizing Map (Geo-SOM)

Biology ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 598
Author(s):  
Do-Hun Lee ◽  
Nam Jung ◽  
Yong-Hyeok Jang ◽  
KyoungEun Lee ◽  
Joobaek Lim ◽  
...  

Nutrias (Myocastor coypus) were imported to South Korea for farming in 1985; individuals escaped captivity and established wild populations in natural ecosystems in the late 1990s. Numerous studies have focused on their monitoring and management; however, information on the continuous movement of individuals is not available. In this study, telemetry data from field conditions were used to identify the nearest-neighbor distances of individuals in association with environmental factors, including plant type, land cover, and biological parameters. The minimum nearest-neighbor distances for the different sexes were, overall, according to the minimum distances for the same sex. Local co-occurrences of individuals, either of the same or different sex, were seasonal. Tall grasslands, followed by herbaceous vegetation, were associated with the co-occurrence of different sexes. Conversely, floating-leaved hydrophytes, followed by xeric herbaceous vegetation, were correlated with the co-occurrence of the same sex. Local female–male co-occurrences were negatively associated with male–male co-occurrences but not with female–female co-occurrences, suggesting male dominance in group formations. Movement and co-occurrence information extracted using Geo-self-organizing maps furthers our understanding of population dispersal and helps formulate management strategies for nutria populations.

2022 ◽  
Author(s):  
Luca Pedruzzi ◽  
Anna Schertler ◽  
Silvia Giuntini ◽  
Ivan Leggiero ◽  
Emiliano Mori

AbstractThe coypu, Myocastor coypus, has been introduced worldwide for fur farming and is widely recognized as one of the most invasive alien mammals of the world, affecting natural ecosystems, crops and possibly human health. Here we present a comprehensive up-to-date review of its distribution and status in Asia and Africa. Using a multi-source approach, we collected occurrences from published literature as well as from online biodiversity platforms (e.g. GBIF, iNaturalist), video sharing platforms, and local experts. Additionally, we used an ensemble modelling approach to predict the climatic suitability across Africa and Asia. We present an updated distribution map, including a total of 1506 spatially explicit records from 1973 to 2021, covering 1 African and 16 Asian countries. We find evidence for current populations in Kenya and five new countries since the last review of (Carter and Leonard, Wildl Soc Bull 30:162–175, 2002): Iran, Jordan, Lebanon, Uzbekistan, and Vietnam, and identify main clusters of coypu occurrence in Western (including Transcaucasia) and East Asia. We show that warm temperate and Mediterranean areas on both continents are predicted to be climatically suitable for the coypu and highlight not only areas of possible spread, but also potential data gaps, i.e. with high suitability and low availability of concrete information (e.g. China, Southern Russia). We emphasize the importance of citizen involvement and the urgency for coypu-targeted studies in data-poor regions to obtain a clear picture of the geographical distribution and to better address management strategies.


Knowledge discovery is also known as Data mining in databases, in recent years that technique plays a major role in research area. Data mining in healthcare domain has noteworthy usage in real world. The mining method can enable the healthcare field for the enhancement of institutionalization of its administrations and become quicker with best in class technologies. Innovation utilization isn't restricted to basic leadership in undertakings, yet spread to different social statuses in all fields. In this paper a novel approach for the detection of brain tumor is proposed. The novel approach uses the classification technique of K-nearest neighbor (KNN) and for ignoring the error of the dataset image SOM (self-organizing map) algorithm has been used. Discrete wavelet transform (DWT) is used for transforming input image data set, in which RGB color of input data image has been converted into gray scale. Then it has been classified using KNN after that the error avoiding algorithm has been carried out. This will help to differentiate tumor cells and the normal cells. The presence of tumor in brain image is detected using parametric analysis by simulation.


Author(s):  
XIAOLIAN GUO ◽  
HAIYING WANG ◽  
DAVID H. GLASS

The Bayesian self-organizing map (BSOM) has typically been used for density estimation. In this study, we implemented an adaptation of the model for performing unsupervized and supervised classification. In order to determine the optimal number of neurons to represent the given dataset during the learning process, an extended Bayesian learning process is proposed called the growing BSOM. It starts with two neurons and adds new neurons to the network via a process in which the neuron with the lowest individual log-likelihood is identified. The system has been tested using three synthetic datasets and one real dataset. The experimental results suggest that the BSOM-based approach can achieve better classification performance in comparisons to several widely-used models such as k-nearest neighbor (KNN), support vector machine (SVM) and Gaussian mixture model (GMM). By using the Bayesian information criterion (BIC) as a stopping criterion, the growing BSOM can model the data under study and estimate the number of clusters.


Author(s):  
S. R. Herd ◽  
P. Chaudhari

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.


2012 ◽  
Vol 132 (10) ◽  
pp. 1589-1594 ◽  
Author(s):  
Hayato Waki ◽  
Yutaka Suzuki ◽  
Osamu Sakata ◽  
Mizuya Fukasawa ◽  
Hatsuhiro Kato

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