scholarly journals Modelling Citrus Huanglongbing Spread in Scenarios involving Alternative Hosts, Vector Populations and Removal of Symptomatic Plants

2020 ◽  
Author(s):  
Sônia Ternes ◽  
Raphael G. d’A. Vilamiu ◽  
Alécio S. Moreira ◽  
Marcelo Rossi ◽  
Tâmara T. de C. Santos ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Crucial Role ◽  
Alternative Host ◽  
Diaphorina Citri ◽  
Associated Bacteria ◽  
Alternative Hosts ◽  
Murraya Paniculata ◽  
The World ◽  
Citrus Huanglongbing ◽  
Citrus Disease

AbstractHuanglongbing (HLB, ex-greening) is the most devastating citrus disease around the world. We modelled HLB spread in scenarios with different populational levels of the main alternative host (Murraya paniculata) and Diaphorina citri Kuwayama, vector of HLB associated bacteria; and removal of HLB-symptomatic plants. A compartmental deterministic mathematical model was built for representing the HLB dynamics in the Reconcavo Baiano, Bahia State, Brazil. The model encompasses delays on latency and incubation disease periods and on the D. citri nymphal stages. The simulations indicated that the presence of alternative hosts at low proportion would not play a crucial role in HLB dynamics in situations of poor D. citri management, regardless of HLB-symptomatic plants eradication. Symptomatic citrus plants contribute more to increase the HLB-incidence than the alternative host in scenarios without a suitable D. citri management.

scholarly journals Knockdown of the Trehalose-6-Phosphate Synthase Gene Using RNA Interference Inhibits Synthesis of Trehalose and Increases Lethality Rate in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Psyllidae)

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 605
Author(s):  
Xinyu Liu ◽  
Zhiwen Zou ◽  
Cong Zhang ◽  
Xian Liu ◽  
Jing Wang ◽  
...  
Keyword(s):  
Growth And Development ◽  
Developmental Stages ◽  
Expression Patterns ◽  
Diaphorina Citri ◽  
Citrus Industry ◽  
Cdna Sequences ◽  
Citrus Huanglongbing ◽  
Citrus Disease ◽  
Trehalose Content ◽  
Phosphate Synthase

Diaphorina citri Kuwayama is the vector of citrus “huanglongbing”, a citrus disease which poses a significant threat to the global citrus industry. Trehalose-6-phosphate synthase (TPS) plays an important role in the regulation of trehalose levels of insects, while its functions in D. citri are unclear. In this study, full-length cDNA sequences of the TPS gene from D. citri (DcTPS) were cloned and its expression patterns at various developmental stages were investigated. The results indicated that DcTPS mRNA was expressed at each developmental stage and the highest DcTPS expression was found in the fifth-instar nymphs of D. citri. Additionally, mortality and deformity of D. citri were observed after 24 and 48 h by feeding with three different dsRNA concentrations (20, 100 and 500 ng/μL). The results indicated that DcTPS expression was declined, and mortality and malformation in nymphs were increased via feeding with dsDcTPS. Moreover, the enzyme and trehalose content were decreased, while the content of glucose was significantly higher than that of untreated (control) individuals. This suggests that DcTPS might be vital for the growth and development of D. citri and further studies of the genes should be related to molting and metabolism for controlling D. citri.

scholarly journals The contemporary distribution of Trypanosoma cruzi infection in humans, alternative hosts and vectors

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Annie J. Browne ◽  
Carlos A. Guerra ◽  
Renato Vieira Alves ◽  
Veruska Maia da Costa ◽  
Anne L. Wilson ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Human Population ◽  
Infection Prevalence ◽  
Alternative Host ◽  
Alternative Hosts ◽  
Large Numbers ◽  
Wide Range ◽  
The World ◽  
Cruzi Infection ◽  
Human Population Movement

Abstract Chagas is a potentially fatal chronic disease affecting large numbers of people across the Americas and exported throughout the world through human population movement. It is caused by the Trypanosoma cruzi parasite, which is transmitted by triatomine vectors to humans and a wide range of alternative host species. The database described here was compiled to allow the risk of vectorial transmission to humans to be mapped using geospatial models. The database collates all available records, published since 2003, for prevalence and occurrence of infection in humans, vectors and alternative hosts, and links each record to a defined time and location. A total of 16,802 records of infection have been extracted from the published literature and unpublished sources. The resulting database can be used to improve our understanding of the geographic variation in vector infection prevalence and to estimate the risk of vectorial transmission of T. cruzi to humans.

Network analysis models – the secret for success

2004 ◽  
Vol 4 (5-6) ◽  
pp. 383-388
Author(s):  
D.M. Rogers
Keyword(s):  
Mathematical Model ◽  
Field Data ◽  
Essential Element ◽  
Distribution Networks ◽  
Automatic Calibration ◽  
Supply And Distribution ◽  
The World ◽  
Optimum Approach ◽  
Analysis Models

Water is a fundamental necessity of life. Yet water supply and distribution networks the world over are old and lacking in adequate maintenance. Consequently they often leak as much water as they deliver and provide an unacceptable quality of service to the customer. In certain parts of the world, water is available only for a few hours of the day. The solution is to build a mathematical model to simulate the operation of the real network in all of its key elements and apply it to optimise its operation. To be of value, the results of the model must be compared with field data. This process is known as calibration and is an essential element in the construction of an accurate model. This paper outlines the optimum approach to building and calibrating a mathematical model and how it can be applied to automatic calibration systems.

scholarly journals Modelling the impact of delaying vaccination against SARS-CoV-2 assuming unlimited vaccine supply

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Marcos Amaku ◽  
Dimas Tadeu Covas ◽  
Francisco Antonio Bezerra Coutinho ◽  
Raymundo Soares Azevedo ◽  
Eduardo Massad
Keyword(s):  
Mathematical Model ◽  
Vaccination Campaign ◽  
Vaccination Rate ◽  
Sao Paulo ◽  
The State ◽  
São Paulo ◽  
Health Authorities ◽  
The World ◽  
The Moment ◽  
The Impact

Abstract Background At the moment we have more than 177 million cases and 3.8 million deaths (as of June 2021) around the world and vaccination represents the only hope to control the pandemic. Imperfections in planning vaccine acquisition and difficulties in implementing distribution among the population, however, have hampered the control of the virus so far. Methods We propose a new mathematical model to estimate the impact of vaccination delay against the 2019 coronavirus disease (COVID-19) on the number of cases and deaths due to the disease in Brazil. We apply the model to Brazil as a whole and to the State of Sao Paulo, the most affected by COVID-19 in Brazil. We simulated the model for the populations of the State of Sao Paulo and Brazil as a whole, varying the scenarios related to vaccine efficacy and compliance from the populations. Results The model projects that, in the absence of vaccination, almost 170 thousand deaths and more than 350 thousand deaths will occur by the end of 2021 for Sao Paulo and Brazil, respectively. If in contrast, Sao Paulo and Brazil had enough vaccine supply and so started a vaccination campaign in January with the maximum vaccination rate, compliance and efficacy, they could have averted more than 112 thousand deaths and 127 thousand deaths, respectively. In addition, for each month of delay the number of deaths increases monotonically in a logarithmic fashion, for both the State of Sao Paulo and Brazil as a whole. Conclusions Our model shows that the current delay in the vaccination schedules that is observed in many countries has serious consequences in terms of mortality by the disease and should serve as an alert to health authorities to speed the process up such that the highest number of people to be immunized is reached in the shortest period of time.

Mathematical modeling of fluid movement inside the eyeball during intravitreal injection

2021 ◽  
pp. 106-109
Author(s):  
D.V. Lipatov ◽  
◽  
S.A. Skladchikov ◽  
N.P. Savenkova ◽  
V.V. Novoderezkin ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Residence Time ◽  
Complex Structure ◽  
Posterior Vitreous Detachment ◽  
Vitreous Body ◽  
Complete Removal ◽  
Intravitreal Injections ◽  
The World

Background. The avalanche-like growth of intravitreal injections in the world has significantly increased interest in the hemodynamics of the processes that occur in the eye when a drug is injected into the vitreous cavity. Every year, the number of intravitreally used drugs and promising areas in which they can be used is growing. This also applies to the creation of new combined medicines and the development of drugs with a long-term therapeutic effect. Aims. Create mathematical model of eyeball to evaluate the movement of the drug substance in it; to estimate the time of the drug's presence in the eye cavity before its complete removal, to characterize the ways of its removal from the eye cavity; to assess the significance of posterior vitreous detachment during the time when the drug is present in the eye cavity; to evaluate the effect on the hydrodynamics of the depth of drug administration. Results. When the drug is administered closer to the center of the eyeball, its residence time increases in comparison with the parietal administration. With a complete posterior detachment of the vitreous body, the time of finding the drug in the eye is prolonged compared to its absence. The obtained results of mathematical modeling of the movement of the drug administered intravitreally cannot be mechanically transferred to the human eye, due to the more complex structure of the latter. Key words: intravitreal injections, vitreous body, mathematic computing.

Ideological Underpinnings in President John Dramani Mahama’s 2013 State of the Nation Address

2021 ◽  
Vol 1 (1) ◽  
pp. 1-17
Author(s):  
Kojo Fenyi ◽  
◽  
Georgina Afeafa Sapaty ◽  
Keyword(s):  
Critical Discourse Analysis ◽  
Thematic Analysis ◽  
Crucial Role ◽  
Critical Discourse ◽  
Cultural Character ◽  
Economic Difficulty ◽  
Human Value ◽  
Biblical Allusion ◽  
The World

This study sets out to investigate, examine and understand the hidden ideologies and ideological structures/devices in the 2013 State of the Nation Address of President John Dramani Mahama. The study specifically aimed to (i) ascertain the ideologies embedded in the speech and (ii) investigate linguistic expressions and devices which carry these ideological colourations in the speech under review. It uses Critical Discourse Analysis as the theoretical framework to examine the role of language in creating ideology as well as the ideological structures in the speech. These hidden ideologies are created, enacted and legitimated by the application of certain linguistic devices. The researchers deem a study of this nature important as it will expose hidden motives that Ghanaian presidents cloth in language in order to manipulate their audience through their speeches in order to win and/or sustain political power. Through thematic analysis, it was revealed that Mahama projected these ideologies in his speech: ideology of positive self-representation, ideology of human value, ideology of economic difficulty, ideology of power relations and ideology of urgency. It also revealed that Mahama projects his ideologies through the following ideological discursive structures: pronouns, biblical allusion and metaphor. The study has shown that language plays a crucial role in human existence as a means of socialisation. Language has been revealed as a means of communicating ideologies and events of the world. In the tradition of CDA, this study has confirmed that text and talk have social and cultural character and that discourse functions ideologically.

Design of a Migrating Crawler Based on a Novel URL Scheduling Mechanism using AHP

2017 ◽  
Vol 4 (1) ◽  
pp. 95-110 ◽  
Author(s):  
Deepika Punj ◽  
Ashutosh Dixit
Keyword(s):  
World Wide Web ◽  
Significant Role ◽  
Crucial Role ◽  
World Wide ◽  
Web Crawler ◽  
Redundancy Elimination ◽  
The World ◽  
Meta Information ◽  
Elimination Mechanism ◽  
The Web

In order to manage the vast information available on web, crawler plays a significant role. The working of crawler should be optimized to get maximum and unique information from the World Wide Web. In this paper, architecture of migrating crawler is proposed which is based on URL ordering, URL scheduling and document redundancy elimination mechanism. The proposed ordering technique is based on URL structure, which plays a crucial role in utilizing the web efficiently. Scheduling ensures that URLs should go to optimum agent for downloading. To ensure this, characteristics of both agents and URLs are taken into consideration for scheduling. Duplicate documents are also removed to make the database unique. To reduce matching time, document matching is made on the basis of their Meta information only. The agents of proposed migrating crawler work more efficiently than traditional single crawler by providing ordering and scheduling of URLs.

scholarly journals Using fuzzy logic for evaluating the level of countries’ (regions’) economic development

2012 ◽  
Vol 59 (3) ◽  
pp. 293-310 ◽  
Author(s):  
Gordan Stojic
Keyword(s):  
Mathematical Model ◽  
Economic Development ◽  
Fuzzy Logic ◽  
Developed Countries ◽  
Gdp Per Capita ◽  
Industrial Growth ◽  
The Poor ◽  
The World ◽  
Level Of Economic Development ◽  
Per Capita

There are several divisions of countries and regions in the world. Besides geo-political divisions, there also are economic divisions. The most common economic division is the that on developed countries and the poor ones. These divisions are a consequence of the level of: GDP, GDP per capita, unemployment rate, industrial growth, and so on. The question is how to define a mathematical model based on which the following will be assessed: who is rich and who is poor, or who is economically developed and who is not? How the boundaries of transition from one category to another can be defined? This paper presents a model for evaluating the level of economic development of countries and regions using "fuzzy" logic. The model was tested on a sample of 19 EU member countries and aspirants for membership.

scholarly journals Calculation of productivity of multi-section trawls for extraction of ferromanganese nodules

2020 ◽  
Vol 177 ◽  
pp. 03010
Author(s):  
Maxim Rakhutin ◽  
Alexey Kashirsky ◽  
Yuliya Lagunova
Keyword(s):  
Mathematical Model ◽  
World Ocean ◽  
Ferromanganese Nodules ◽  
The World ◽  
Main Factors

A mathematical model of the operational productivity of trawls for the extraction of ferromanganese nodules from the bottom of the World Ocean is proposed. On the example of the previously proposed cassette trawl, the analysis of the influence of the main factors on the value of operational productivity is carried out.

scholarly journals Mathematical model and simulations of MERS outbreak: Predictions and implications for control measures

BIOMATH ◽  
2017 ◽  
Vol 5 (2) ◽  
pp. 1612141 ◽  
Author(s):  
Nofe Al-Asuoad ◽  
Libin Rong ◽  
Sadoof Alaswad ◽  
Meir Shillor
Keyword(s):  
Mathematical Model ◽  
Middle East ◽  
Coupled System ◽  
Control Measures ◽  
Nonlinear Ordinary Differential Equations ◽  
Contact Rate ◽  
Isolation Rate ◽  
Model Predictions ◽  
The World ◽  
The City

The Middle East Respiratory Syndrome (MERS) has been identified in 2012 and since then outbreaks have been reported in various localities in the Middle East and in other parts of the world. To help predict the possible dynamics of MERS, as well as ways to contain it, this paper develops a mathematical model for the disease. It has a compartmental structure similar to SARS models and is in the form of a coupled system of nonlinear ordinary differential equations (ODEs). The model predictions are fitted to data from the outbreaks in Riyadh (Saudi Arabia) during 2013-2016. The results reveal that MERS will eventually be contained in the city. However, the containment time and the severity of the outbreaks depend crucially on the contact coefficients and the isolation rate constant. When randomness is added to the model coefficients, the simulations show that the model is sensitive to the scaled contact rate among people and to the isolation rate. The model is analyzed using stability theory for ODEs and indicates that when using only isolation, the endemic steady state is locally stable and attracting. Numerical simulations with parameters estimated from the city of Riyadh illustrate the analytical results and the model behavior, which may have important implications for the disease containment in the city. Indeed, the model highlights the importance of isolation of infected individuals and may be used to assess other control measures. The model is general and may be used to analyze outbreaks in other parts of the Middle East and other areas.

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