scholarly journals Spatio-temporal patterns in herring (Clupea harengus L.) school abundance and size in the northwest North Sea: modelling space–time dependencies to allow examination of the impact of local school abundance on school size

2002 ◽  
Vol 59 (3) ◽  
pp. 469-479 ◽  
Author(s):  
D Beare
2021 ◽  
Vol 906 (1) ◽  
pp. 012030
Author(s):  
Bingbing Song ◽  
Yanlin Wang ◽  
Fang Li

Abstract Map is a traditional visualization tool to represent distribution and interaction of spatial objects or spatial phenomenon. However, with the continuous development of acquisition and processing technologies for spatio-temporal data, traditional map can hardly meet the visualization requirement for this type of data. In other words, the dynamic information about spatial object or phenomenon cannot be expressed fully by traditional map. The Space-Time-Cube (STC), as a three-dimensional visualization environment, whose base represents the two-dimensional geographical space and whose height represents the temporal dimension, can simultaneously represent the spatial distribution as well as the temporal changes of spatio-temporal data. For some spatial object or phenomenon, its moving trajectory can be visualized in STC as a Space-Time-Path (STP), by which the speed and state of motion can be clearly reflected. Noticeably, the problem of visual clutter about STP is inevitably due to the complexity of three-dimensional visualization. In order to reduce the impact of visual clutter, this paper discusses different aspects about visualization representation of STP in the STC. The multiple scales representation and the multiple views display can promote interactive experience of users, and the application of different visual variables can help to represent different kinds of attribute information of STP. With the visualization of STP, spatio-temporal changes and attributive characters of spatial object or phenomenon can be represented and analysed.


2019 ◽  
Vol 5 (1) ◽  
pp. 105-108 ◽  
Author(s):  
Vincent Fleischhauer ◽  
Nora Ruprecht ◽  
Sebastian Zaunseder

AbstractImaging photoplethysmography allows to capture spatio-temporal patterns related to the perfusion. One such approach is based on the analysis of the time delay between pulse waves at different locations by so-called phase maps. There are different ways to establish such maps. However, neither a comparison between existing methods has been published nor has the impact of different stimuli been sufficiently examined until today. In this work, we compare three previously published approaches for the generation of phase maps and investigate the impact of two physiological stimuli on such maps. Our results show pairwise correlation coefficients between the different approaches of phase map generation from r = 0.65 to r = 0.82, indicating substantial differences between maps. The different maps reflect our physiological expectation in varying degrees. Particularly for a weaker (distant) stimulation refinements are needed to reveal characteristic changes.


Electronics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 1083 ◽  
Author(s):  
Zakria ◽  
Jianhua Deng ◽  
Jingye Cai ◽  
Muhammad Umar Aftab ◽  
Muhammad Saddam Khokhar ◽  
...  

Vehicle re-identification (Re-Id) is the key module in an intelligent transportation system (ITS). Due to its versatile applicability in metropolitan cities, this task has received increasing attention these days. It aims to identify whether the specific vehicle has already appeared over the surveillance network or not. Mostly, the vehicle Re-Id method are evaluated on a single dataset, in which training and testing of the model is performed on the same dataset. However in practice, this negatively effects model generalization ability due to biased datasets along with the significant difference between training and testing data; hence, the model becomes weak in a practical environment. To demonstrate this issue, we have empirically shown that the current vehicle Re-Id datasets are usually strongly biased. In this regard, we also conduct an extensive study on the cross and the same dataset to examine the impact on the performance of the vehicle Re-Id system, considering existing methods. To address the problem, in this paper, we have proposed an approach with augmentation of the training dataset to reduce the influence of pose, angle, camera color response, and background information in vehicle images; whereas, spatio-temporal patterns of unlabelled target datasets are learned by transferring siamese neural network classifiers trained on a source-labelled dataset. We finally calculate the composite similarity score of spatio-temporal patterns with siamese neural-network-based classifier visual features. Extensive experiments on multiple datasets are examined and results suggest that the proposed approach has the ability to generalize adequately.


2021 ◽  
Vol 6 (1) ◽  
pp. 30
Author(s):  
Ayodhia Pitaloka Pasaribu ◽  
Tsheten Tsheten ◽  
Muhammad Yamin ◽  
Yulia Maryani ◽  
Fahmi Fahmi ◽  
...  

Dengue has been a perennial public health problem in Medan city, North Sumatera, despite the widespread implementation of dengue control. Understanding the spatial and temporal pattern of dengue is critical for effective implementation of dengue control strategies. This study aimed to characterize the epidemiology and spatio-temporal patterns of dengue in Medan City, Indonesia. Data on dengue incidence were obtained from January 2016 to December 2019. Kulldorff’s space-time scan statistic was used to identify dengue clusters. The Getis-Ord Gi* and Anselin Local Moran’s I statistics were used for further characterisation of dengue hotspots and cold spots. Results: A total of 5556 cases were reported from 151 villages across 21 districts in Medan City. Annual incidence in villages varied from zero to 439.32 per 100,000 inhabitants. According to Kulldorf’s space-time scan statistic, the most likely cluster was located in 27 villages in the south-west of Medan between January 2016 and February 2017, with a relative risk (RR) of 2.47. Getis-Ord Gi* and LISA statistics also identified these villages as hotpot areas. Significant space-time dengue clusters were identified during the study period. These clusters could be prioritized for resource allocation for more efficient prevention and control of dengue.


BIOMATH ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 1807217 ◽  
Author(s):  
Raluca Eftimie

The collective movement of animals occurs as a result of communicationbetween the members of the community. However, inter-individual commu-nication can be aected by the stochasticity of the environment, leading tochanges in the perception of neighbours and subsequent changes in individualbehaviour, which then in uence the overall behaviour of the animal aggre-gations. To investigate the eect of noise on the overall behaviour of animalaggregations, we consider a class of nonlocal stochastic and deterministic hy-perbolic models for the collective movement of animals. We show numericallythat strong noise does not seem to in uence the spatio-temporal pattern (i.e.,travelling aggregations) observed when all neighbours are perceived with thesame intensity (i.e., the environment is homogeneous). However, when neigh-bours ahead/behind are perceived dierently by a reference individual, noisecan lead to the destruction of the spatio-temporal pattern. Moreover, weshow that the increase in noise can lead to dierent transitions between dif-ferent spatio-temporal patterns, and these transitions are relatively similarto the transitions between patterns when we perturb deterministically someparameters.


2020 ◽  
Author(s):  
Mónica López-Lacort ◽  
Alejandro Orrico-Sánchez ◽  
Miguel Ángel Martínez-Beneito ◽  
Cintia Muñoz-Quiles ◽  
Javier Díez-Domingo

Abstract Background: Several studies have shown a substantial impact of Rotavirus (RV) vaccination on the burden of RV and all-cause acute gastroenteritis (AGE). However, the results of most impact studies could be confused by a dynamic and complex space-time process. Therefore, there is a need to analyse the impact of RV vaccination on RV and AGE hospitalisations in a space-time framework to detect geographical-time patterns while avoiding the potential confusion caused by population inequalities in the impact estimations.Methods: A retrospective population-based study using real-world data from the Valencia Region was performed among children aged less than 3 years old in the period 2005-2016. A Bayesian spatio-temporal model was constructed to analyse RV and AGE hospitalisations and to estimate the vaccination impact measured in averted hospitalisations. Results: We found important spatio-temporal patterns in RV and AGE hospitalisations, RV vaccination coverage and in their associated adverted hospitalisations. Overall, ~1866 hospital admissions for RV were averted by RV vaccination during 2007–2016. Despite the low-medium vaccine coverage (~50%) in 2015-2016, relevant 36% and 20% reductions were estimated in RV and AGE hospitalisations respectively.Conclusions: The introduction of the RV vaccines has substantially reduced the number of RV hospitalisations, averting ~1866 admissions during 2007-2016 which were space and time dependent. This study improves the methodologies commonly used to estimate the RV vaccine impact and their interpretation.


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