Parameter Estimation and Optimal Control of the Dynamics Of Transmission of Tuberculosis with Application to Cameroon

This paper deals with the problem of parameter estimation and optimal control of a tuberculosis (TB) model with seasonal fluctuations. We first present a uncontrolled TB model with seasonal fluctuations. We present the theoretical analysis of the uncontrolled TB model without seasonal fluctuations. After, we propose a numerical study to estimate the unknown parameters of the TB model with seasonal fluctuations according to demographic and epidemiological data from Cameroon. Simulation results are in good accordance with the seasonal variation of the new active reported cases of TB in Cameroon. Using this TB model with seasonality, the tuberculosis control is formulated and solved as an optimal control problem, indicating how control terms on the chemoprophylaxis and treatment should be introduced in the considered TB model to reduce the number of individuals with active TB. Results provide a framework for designing cost-effective strategies for TB with two strategies of intervention

Causes of road traffic accidents in Juba

Introduction: Road traffic accidents (RTAs) are a major cause of death and disability in South Sudan. The purpose of this study was to investigate whether violation of traffic rules is the main cause of RTAs.Method: A cross sectional study design was used with quantitative data covering January – December 2014. The main objective of the research was to understand the epidemiology of RTAs in order to develop preventive measures. A total of 1,725 cases from road RTAs data were extracted from the directorate of traffic police Central Equatoria state Juba and Juba teaching hospital.Results: Most (99.5%) of the RTA drivers were not under the influence of alcohol. Most accidents were caused by male drivers (99%). The highest number of RTAs took place in August (11%). Drivers of private vehicles caused most accidents (37%). Most drivers (46%) were aged 20-30 years. RTAs occurred most often on city roads (89.83%). Conclusion: This leads us to conclude that a comprehensive safety system is needed that are premised on the idea of community-based awareness of traffic rules and safety regulations. Resources are limited so there is a need to harness local resources including the local community. More efforts are needed to improve road safety education among the youth/ integrate safety into road design.Key Words: Road traffic accidents, private vehicles, alcoho

MATHEMATICAL ANALYSIS OF A DRUG RESISTANCE IN A TUBERCULOSIS TRANSMISSION MODEL

International audienceIn this paper, we investigate the effect of the emergence of TB drug-resistant within a human population. We first propose a drug resistance in a tuberculosis transmission model with two strains of Mycobacterium tuberculosis: those that are sensitive to anti-tuberculosis drugs and those that are resistant. After, we present the theoretical results of the model. More precisely, we compute the disease-free equilibrium and derive the basic reproduction number R 0 that determines the outcome of the disease. We show that there exists a threshold parameter ξ such that the disease-free equilibrium is globally asymptotically stable in a feasible region whenever R 0 ≤ ξ < 1, while when ξ < R 0 < 1, the model exhibits the phenomenon of backward bifurcation and if R 0 > 1, the disease-free equilibrium is unstable and there exists an unique endemic equilibrium which is stable. Conditions for the coexistence of sensitive and resistant strains are derived. We also show that the model undergoes the Hopf-bifurcation with respect to the transmission rates. A dynamically consistent non standard finite difference scheme is developed to illustrate and validate theoretical result. The motivation comes to the fact the classical Runge-Kutta scheme cannot preserve the positivity of solutions of the model

Causes of road traffic accidents in Juba

Introduction: Road traffic accidents (RTAs) are a major cause of death and disability in South Sudan. The purpose of this study was to investigate whether violation of traffic rules is the main cause of RTAs. Method: A cross sectional study design was used with quantitative data covering January – December 2014. The main objective of the research was to understand the epidemiology of RTAs in order to develop preventive measures. A total of 1725cases from road RTAs data were extracted from the directorate of traffic police Central Equatoria state Juba and Juba teaching hospital. Results: Most (99.5%) of the RTA drivers were not under the influence of alcohol. Most accidents were caused by male drivers (99%). The highest number of RTAs took place in August (11%). Drivers of private vehicles caused most accidents (37%). Most drivers (46%) were aged 20-30 years. RTAs occurred most often on city roads (89.83%). Conclusion: This leads us to conclude that a comprehensive safety system is needed that are premised on the idea of community-based awareness of traffic rules and safety regulations. Resources are limited so there is a need to harness local resources including the local community. More efforts are needed to improve road safety education among the youth/integrate safety into road design

A bistable, self-latching inverter by the monolithic integration of resonant tunnelling diode and high electron mobility transistor

This paper reports that the structures of AlGaAs/InGaAs high electron mobility transistor (HEMT) and AlAs/GaAs resonant tunnelling diode (RTD) are epitaxially grown by molecular beam epitaxy ( MBE) in turn on a GaAs substrate. An Al0.24Ga0.76As chair barrier layer, which is grown adjacent to the top AlAs barrier, helps to reduce the valley current of RTD. The peak-to-valley current ratio of fabricated RTD is 4.8 and the transconductance for the 1-mu m gate HEMT is 125mS/mm. A static inverter which consists of two RTDs and a HEMT is designed and fabricated. Unlike a conventional CMOS inverter, the novel inverter exhibits self-latching property

A small signal equivalent circuit model for resonant tunnelling diode

We report a resonant tunneling diode (RTD) small signal equivalent circuit model consisting of quantum capacitance and quantum inductance. The model is verified through the actual InAs/In0.53Ga0.47As/AlAs RTD fabricated on an InP substrate. Model parameters are extracted by fitting the equivalent circuit model with ac measurement data in three different regions of RTD current-voltage (I-V) characteristics. The electron lifetime, representing the average time that the carriers remain in the quasibound states during the tunneling process, is also calculated to be 2.09 ps