scholarly journals Structure of epidemic models: toward further applications in economics

2021 ◽  
Author(s):  
Toshikazu Kuniya
Keyword(s):  
Periodic Solutions ◽  
Age Structure ◽  
Epidemic Models ◽  
Effective Control ◽  
Spatial Diffusion ◽  
Mathematical Epidemiology ◽  
Scientific Attitude ◽  
Single Model ◽  
Reproduction Numbers ◽  
The Future

AbstractIn this paper, we review the structure of various epidemic models in mathematical epidemiology for the future applications in economics. The heterogeneity of population and the generalization of nonlinear terms play important roles in making more elaborate and realistic models. The basic, effective, control and type reproduction numbers have been used to estimate the intensity of epidemic, to evaluate the effectiveness of interventions and to design appropriate interventions. The advanced epidemic models includes the age structure, seasonality, spatial diffusion, mutation and reinfection, and the theory of reproduction numbers has been generalized to them. In particular, the existence of sustained periodic solutions has attracted much interest because they can explain the recurrent waves of epidemic. Although the theory of epidemic models has been developed in decades and the development has been accelerated through COVID-19, it is still difficult to completely answer the uncertainty problem of epidemic models. We would have to mind that there is no single model that can solve all questions and build a scientific attitude to comprehensively understand the results obtained by various researchers from different backgrounds.

scholarly journals Real-Time Mode Switching and Beam Scanning of High-Gain OAM Waves Using a 1-Bit Reconfigurable Reflectarray Antenna

Electronics ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2181
Author(s):  
Ziyang Wang ◽  
Xiaotian Pan ◽  
Fan Yang ◽  
Shenheng Xu ◽  
Maokun Li
Keyword(s):  
Real Time ◽  
Dimensional Space ◽  
Large Angle ◽  
High Gain ◽  
Mode Switching ◽  
Effective Control ◽  
Vortex Beam ◽  
Beam Scanning ◽  
The Future ◽  
Reflectarray Antenna

A reconfigurable electromagnetic surface has been studied to realize the adjustable orbital angular momentum (OAM) beams for real-time wireless communication and dynamic target detection in the future. OAM mode switching realized by many previous designs suffers from low gains without OAM beam scanning. In this article, a 1-bit reconfigurable reflectarray antenna is designed, fabricated, and tested for the real-time control of OAM mode switching and large-angle vortex beam scanning in three-dimensional space. The proposed reflectarray surface is composed of 1-bit electronically reconfigurable cells, and the size is 24 λ × 24 λ with 2304 units. The reconfigurable element is designed by using a radiation patch loading a PIN diode with effective control of two states, “ON” and “OFF”, for the demand of 180° phase difference. The reflectarray surface can be assigned to a code sequence of 0 or 1 by the Field-Programmable Gate Array (FPGA) in real time. Henceforth, the coding surface can dynamically control the generation of high-gain OAM beams, where only the optimized phase distributions on the surface need to be changed according to demand. To verify the concept, a large-scale reflectarray surface is fabricated and measured with an oblique feed at 15°. Different OAM-carrying phase distributions for different OAM beam states are calculated and tested. The test results show that the OAM mode switching between l = 1 and l = 2 is realized, and other variable modes such as l = 3 or l = 5 can also be achieved by modifying the phase encoding sequence. Furthermore, the direction of the vortex beams can be accurately controlled with gains over 20 dBi, and the large-angle vortex beam scanning is verified. Therefore, all results demonstrate that the proposed 1-bit reconfigurable reflectarray is efficient for the regulation and control of OAM-carrying beams for the demand of real-time dynamic wireless communications in the future.

Effective Control of Enzyme Activity Based on a Subtle Nanoreactor: A Promising Strategy for Biomedical Applications in the Future

2017 ◽  
Vol 1 (1) ◽  
pp. 302-309 ◽  
Author(s):  
Ronghua Jin ◽  
Zhongning Liu ◽  
Yongkang Bai ◽  
Yongsheng Zhou ◽  
Xin Chen
Keyword(s):  
Enzyme Activity ◽  
Biomedical Applications ◽  
Effective Control ◽  
Promising Strategy ◽  
The Future

scholarly journals Optimum contribution selection using differential evolution

2010 ◽  
Vol 39 (7) ◽  
pp. 1429-1436 ◽  
Author(s):  
Roberto Carvalheiro ◽  
Sandra Aidar de Queiroz ◽  
Brian Kinghorn
Keyword(s):  
Differential Evolution ◽  
Objective Function ◽  
Overlapping Generations ◽  
Selection Response ◽  
Effective Control ◽  
Computationally Efficient ◽  
Genetic Merit ◽  
Practical Applications ◽  
The Future

A program to determine optimum contribution selection using differential evolution was developed. The objective function to be optimized was composed by the expected merit of the future progeny and the coancestry among selected parents. Simulated and real datasets of populations with overlapping generations were used to validate and test the performance of the program. The program was computationally efficient and feasible for practical applications. The expected consequences of using the program, in contrast to empirical procedures to control inbreeding and/or to selection based exclusively on expected genetic merit, would be the improvement of the selection response and a more effective control of inbreeding.

scholarly journals The misleading illusion of COVID-19 confirmed case data: alternative estimates and a monitoring tool

2020 ◽  
Author(s):  
Rogelio Macías-Ordóñez ◽  
Damián Villaseñor-Amador
Keyword(s):  
Decision Making ◽  
Incubation Period ◽  
Age Structure ◽  
Fatality Rate ◽  
Monitoring Tool ◽  
Steep Increase ◽  
The Future ◽  
Near Future ◽  
Case Data ◽  
Country Specific

AbstractConfirmed Case Data have been widely cited during the current COVID-19 pandemic as an estimate of the spread of the SARS-CoV-2 virus. However, their central role in media, official reports and decision-making may be undeserved and misleading. Previously published Infection Fatality Rates were weighted by age structure in the 50 countries with more reported deaths to obtain country-specific rates. For each country, the number of infections up to the Infection Date (23 days ago = Incubation Period + Onset to Death period) and the present percentage of immune population were estimated using Infection Fatality Rate, the number of reported deaths (which is less prone to undersampling), and projecting back to Infection Date. We then estimated a Detection Index for each country as the percentage of estimated infections that confirmed cases represent. Assuming that detection remains constant after Infection Date, we estimated the number of deaths and the estimated percentage of the population of each country expected to be immune up to 23 days into the future. Estimated Infection Fatality Rates are higher in Europe. In most countries, confirmed cases currently represent less than 30% of estimated infections on Infection Date, and this value decreases with time. Countries with flat curves throughout the pandemic show the lowest immunity percentages and these values seem unlikely to change in the near future, suggesting that they remain vulnerable to new outbreaks. Estimates for some countries with low Infection Fatality Rates suggest a still steep increase in the number of casualties in the next three weeks. Countries that did not control initial outbreaks seem to have reached higher immunity percentages, although mostly still under 5%. We provide the code to monitor the trajectories of these estimates in 178 countries throughout the COVID-19 pandemic.

scholarly journals Control Strategies for the Third wave of COVID-19 infection in India: A Mathematical Model Incorporating Vaccine Effectiveness

2022 ◽  
Author(s):  
Ashutosh Mahajan ◽  
Namitha Sivadas ◽  
Pooja Panda
Keyword(s):  
Transmission Rate ◽  
Control Strategies ◽  
Control Measures ◽  
Disease Spread ◽  
Effective Control ◽  
Third Wave ◽  
Social Distancing ◽  
Vaccination Rates ◽  
New Variant ◽  
The Future

The waning effectiveness of the COVID-19 vaccines and the emergence of a new variant Omicron has given rise to the possibility of another outbreak of the infection in India. COVID-19 has caused more than 34 million reported cases and 475 thousand deaths in India so far, and it has affected the country at the root level, socially as well as economically. After going through different control measures, mass vaccination has been achieved to a large extent for the highly populous country, and currently under progress. India has already been hit by a massive second wave of infection in April-June, 2021 mainly due to the delta variant, and might see a third wave in the near future that needs to be controlled with effective control strategies. In this paper, we present a compartmental epidemiological model with vaccinations incorporating the dose-dependent effectiveness. We study a possible sudden outbreak of SARS-CoV2 variants in the future, and bring out the associated predictions for various vaccination rates and point out optimum control measures. Our results show that for transmission rate 30% higher than the current rate due to emergence of new variant or relaxation of social distancing conditions, daily new cases can peak to 250k in March 2022, taking the second dose effectiveness dropping to 50% in the future. A combination of vaccination and controlled lockdown or social distancing is the key to tackling the current situation and for the coming few months. Our simulation results show that social distancing measures show better control over the disease spread than the higher vaccination rates. <br>

scholarly journals The Challenge of Addressing Obesity: Moving to the Extremes

Challenges ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 33
Author(s):  
Glenn Laverack
Keyword(s):  
Population Health ◽  
Middle Ground ◽  
Top Down ◽  
Single Model ◽  
Bottom Up ◽  
The Public ◽  
Self Help ◽  
The Future ◽  
Self Help Groups

Obesity is preventable but there is still no single model for prevention and no country has managed to convincingly reverse the growing trend, estimated in 2016 to be 650 million adults. Globally, the increase in obesity will have catastrophic consequences for the economy and for population health. ‘Desperate times breed desperate measures’ and this paper outlines the shift that many governments are being forced to make to halt the growth of obesity. Moving to the extremes means that the planning and coordination of strategies places an equal emphasis on top-down (policy, regulation, and taxation) and bottom-up (local actions, self-help groups, volunteerism) interventions. There is still an important role for communication, the middle-ground between the extremes of bottom-up and top-down, but governments must use ‘power-over’ measures to take control of the causes of obesity. Bringing the public with them will be crucial to success and can be achieved through a sharing of resources, a ‘power-with’, to combine top-down and bottom-up interventions in the future.

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