1,720,961 research outputs found
Mathematical modeling of pest invasion and application to the fight against pest-borne diseases in the Philippines
No full textLa dengue est une infection virale transmise par les moustiques dans les régions tropicales et subtropicales du monde entier. Il s'agit d’une infection virale causée par quatre types de virus (DENV-1, DENV-2, DENV-3, DENV-4), qui se transmettent par la piqûre de moustiques femelles infectés (Aedes aegypti) et (Aedes albopictus) pendant la journée. Le premier vaccin à être utilisé commercialement est le CYD-TDV, commercialisé sous le nom de dengvaxia par Sanofi Pasteur. Dengvaxia est un vaccin vivant des sérotypes 1, 2, 3 et 4. Il doit être administré en trois doses de 0,5 ml par voie sous-cutanée (SC) à six mois d'intervalle. Sanofi Pasteur recommande que le vaccin ne soit utilisé que chez les personnes âgées de 9 à 45 ans et chez les personnes déjà infectées par un type de virus. Cet article présente un modèle épidémique de type Ross pour décrire l'interaction vaccinale entre les humains et les moustiques en utilisant différents modèles de croissance de la population. Après avoir établi le nombre de reproduction de base R0 et la stabilité de l'équilibre, nous présentons trois stratégies de contrôle : la vaccination, le contrôle des vecteurs par l'application de pesticides, et la combinaison de la vaccination et du contrôle des vecteurs. En tenant compte du cycle de vie des moustiques, nous avons introduit le copépode comme contrôle vectoriel pour les larves. Le principe du maximum de Pontryagin est utilisé pour caractériser le contrôle optimal, et des simulations numériques sont appliquées pour déterminer les stratégies les mieux adaptées à la population. De plus, nous avons défini un nouveau modèle dans lequel les moustiques adultes impliquent une distribution spatiale. Dans ce modèle, nous avons montré qu'en appliquant le théorème du point fixe de Picard, nous avons l'unique solution faible globale en temps du système d'équation. Nous déterminons la stratégie de contrôle optimal en appliquant trois contrôles : l'exposition au copépode wY pour les jeunes moustiques, le pesticide wA pour les moustiques adultes, et l'application de la vaccination wH pour les humains. Nos résultats montrent que la vaccination des humains sensibles secondaires uniquement n'est pas idéale. Cela demande un effort constant et prend beaucoup de temps pour les vacciner. Par ailleurs, les copépodes et les pesticides constituent une bonne stratégie pour éliminer les humains infectés et les populations de moustiques. Cependant, l'élimination des humains infectés est lente. La combinaison des pesticides et de la vaccination semble moins efficace que la combinaison des copépodes et des pesticides. Il faut moins de temps pour réduire le nombre de moustiques avec une durée d'application de la lutte réduiteDengue is a mosquito-borne viral infection found in tropical and subtropical regions worldwide. It is a viral infection caused by four types of viruses (DENV-1, DENV-2, DENV-3, DENV-4), which transmit through the bite of infected Aedes aegypti and Aedes albopictus female mosquitoes during the daytime. The first vaccine to be used commercially is CYD-TDV, marketed as dengvaxia by Sanofi Pasteur. Dengvaxia is a live vaccine of serotypes 1, 2, 3, and 4. It should be administered in three doses of 0.5 mL subcutaneous (SC) six months apart. Sanofi Pasteur recommended that the vaccine only be used in people between the age of 9 to 45 and people already infected by one type of virus. This paper presents a Ross-type epidemic model to describe the vaccine interaction between humans and mosquitoes using different population growth models. After establishing the basic reproduction number R0 and the stability of the equilibrium, we present three control strategies: vaccination, vector control through pesticide application, and the combination of vaccination and vector control. Accounting for mosquitoes’ life cycle, copepod as a vector control for larvae was introduced. Pontryagin’s maximum principle is used to characterize optimal control, and numerical simulations are applied to determine which strategies best suit the population. Moreover, we defined a new model wherein adult mosquitoes involved spatial distribution. In this model, we have shown that by applying Picard’s fixed point theorem, we have the unique global in time weak solution of the equation system. We determine the optimal control strategy by applying three control: exposure to copepod wY for the young mosquitoes, pesticide wA for the adult mosquitoes, and application of vaccination wH for the humans. Our results show that vaccinating secondary susceptible humans only is not ideal. It requires constant effort and takes a long time to vaccinate them. Also, copepods and pesticides are a good strategy for eliminating infected humans and mosquito populations. However, the elimination of infected humans is slow. The combination of pesticide and vaccination seems less efficient than the combination of copepods and pesticides. It takes a shorter time to reduce the number of mosquitoes with a reduced duration of the control applicatio
Unveiling SIR Model Parameters: Empirical Parameter Approach for Explicit Estimation and Confidence Interval Construction
Full text linkWe propose a simple parameter estimation method for the Susceptible-Infectious-Recovered (SIR) model. This method offers explicit estimates of parameters using second-order numerical derivatives to construct empirical parameters. In addition, the method constructs confidence intervals, providing a robust assessment of parameter uncertainty. To validate the accuracy of our method, we applied it to simulated data, in order to demonstrate its effectiveness in accurately estimating the true model parameters. Furthermore, we applied this method to actual COVID-19 case data from the USA, Indonesia, and the Philippines. This application enables the estimation of parameters and reproductive numbers, along with their confidence intervals, thus underscoring the efficacy of our technique. Notably, the parameter estimates obtained through our approach successfully predicted the case numbers in all three countries, confirming its predictive reliability. Our method offers significant advantages in terms of simplicity and accuracy, making it an invaluable tool for epidemiological modeling and public health planning
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Hybrid Modeling of COVID-19 Spatial Propagation over an Island Country
No full textInternational audienc
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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