Analysis, Simulation and Control of a New Measles Epidemic Model

In this paper the problem of modeling and controlling the measles epidemic spread is faced. A new model is proposed and analysed; besides the categories usually considered in measles modeling, the susceptible, the exposed, the infected, the removed and, less frequently, the quarantine individuals, two new categories are herein introduced: the immunosuppressed subjects, that can not be vaccinated, and the patients with an additional complication, not risky by itself but dangerous if caught togeter with the measles. These two novelties are taken into account in designing and scheduling suitably control actions such as vaccination, whenever possible, prevention, quarantine and treatment, when limited resources are available. An analysis of the model is developed and the optimal control strategies are compared with other not optimized actions. By using the Pontryagin principle, it is shown the prevailing role of the vaccination in guaranteeing the protection to immunosuppressed individuals, as well as the importance of a prompt response of the society when an epidemic spread occurs, such as the quarantine intervention

Optimal Control to Limit the Propagation Effect of a Virus Outbreak on a Network

The aim of this paper is to propose an optimal control strategy to face the propagation effects of a virus outbreak on a network; a recently proposed model is integrated and analysed. Depending on the specific model caracteristics, the epidemic spread could be more or less dangerous leading to a virus free or to a virus equilibrium. Two possible controls are introduced: a test on the computers connected in a network and the antivirus. In a condition of limited resources the best allocation strategy should allow to reduce the spread of the virus as soon as possible

State Feedback Optimal Control with Singular Solution for a Class of Nonlinear Dynamics

The paper studies the problem of determining the optimal control when singular arcs are present in the solution. In the general classical approach the expressions obtained depend on the state and the costate variables at the same time, so requiring a forward-backward integration for the computation of the control. In this paper, sufficient conditions on the dynamics structure are provided and discussed in order to have both the control and the switching function depending on the state only, so simplifying the computation avoiding the necessity of the backward integration. The approach has been validated on a classical SIR epidemic model

An Improvement in a Local Observer Design for Optimal State Feedback Control: The Case Study of HIV/AIDS Diffusion

The paper addresses the problem of an observer design for a nonlinear system for which a preliminary linear state feedback is designed but the full state is not measurable. Since a linear control assures the fulfilment of local approximated conditions, usually a linear observer is designed in these cases to estimate the state with estimation error locally convergent to zero. The case in which the control contains an external reference, like in regulations problems, is studied, showing that the solution obtained working with the linear approximation to get local solutions produces non consistent results in terms of local regions of convergence for the system and for the observer. A solution to this problem is provided, proposing a different choice for the observer design which allows to obtain all conditions locally satisfied on the same local region in the neighbourhood of a new equilibrium point. The case study of an epidemic spread control is used to show the effectiveness of the procedure. The linear control with regulation term is present in this case because the problem is reconducted to a Linear Quadratic Regulation problem. Simulation results show the differences between the two approaches and the effectiveness of the proposed on

Update on medication-overuse headache and its treatment

OPINION STATEMENT: Medication-overuse headache-i.e., a too-frequent consumption of acute headache medications leading to increased headache frequency and reduced effectiveness of acute and preventive treatments-is a serious medical condition whose pathophysiology still remains incompletely known, which is reflected into a lack of mechanism-based treatments. The first mandatory step in the therapeutic strategy remains withdrawal of the abused drug, preferably abrupt, in concomitance with a detoxification pharmacological regimen to lessen withdrawal symptoms. Intravenous hydration, antiemetics, corticosteroids (prednisone), tranquilizers (benzodiazepine), neuroleptics, and rescue medication (another analgesic than the overused) should be delivered in various combinations, on an inpatient (hospitalization and day hospital) basis or outpatient basis, depending on the characteristics of the specific patient and type of overuse. Inpatient withdrawal should be preferred in barbiturate and opioid overuse, in concomitant depression, or, in general, in patients who have difficulty in stopping the overused medication as outpatients. In contrast, in overuse limited to simple analgesics in highly motivated patients, without high levels of depression and/or anxiety, home detoxification should be chosen. Re-prophylaxis should immediately follow detoxification, ideally with local injections of onabotulinumtoxinA every 3 months or topiramate orally for at least 3 months. Adequate information to patients about the risks of a too-frequent consumption of symptomatic headache medications is essential and should constantly parallel treatment to help preventing relapse after detoxification and re-prophylaxis

Measurements Of Electrostatic Double Layer Potentials With Atomic Force Microscopy

The aim of this thesis is to provide a thorough description of the development of theory and experiment pertaining to the electrostatic double layer (EDL) in aqueous electrolytic systems. The EDL is an important physical element of many systems and its behavior has been of interest to scientists for many decades. Because many areas of science and engineering move to test, build, and understand systems at smaller and smaller scales, this work focuses on nanoscopic experimental investigations of the EDL. In that vein, atomic force microscopy (AFM) will be introduced and discussed as a tool for making high spatial resolution measurements of the solid-liquid interface, culminating in a description of the development of a method for completely characterizing the EDL. This thesis first explores, in a semi-historical fashion, the development of the various models and theories that are used to describe the electrostatic double layer. Later, various experimental techniques and ideas are addressed as ways to make measurements of interesting characteristics of the EDL. Finally, a newly developed approach to measuring the EDL system with AFM is introduced. This approach relies on both implementation of existing theoretical models with slight modifications as well as a unique experimental measurement scheme. The model proposed clarifies previous ambiguities in definitions of various parameters pertaining to measurements of the EDL and also can be used to fully characterize the system in a way not yet demonstrated

Errors in Second Language Acquisition: A study based on the German and Spanish components of COREFL

openThis dissertation analyses a set of errors concerning the omission of the third person -s made by Spanish and German L2 learners of English in the COREFL learner corpus. With a corpus-based approach, the errors were analysed from a grammatical point of view. The errors were also sorted according to some variables, including the learners’ proficiency level and the texts’ medium. The data analyses were carried out on Microsoft Excel, to perform calculations and visualize the results by putting the data into tables and charts. The results were also normalised in order to correctly compare them. The findings suggest that the Spanish learners make more errors than the German learners, but both groups produce the errors mostly in the spoken medium. The results are also discussed in relation to some theories and hypotheses coming from the field of Second Language Acquisition. The dissertation concludes by presenting some possible causes for this error type and some possible solutions to overcome it.This dissertation analyses a set of errors concerning the omission of the third person -s made by Spanish and German L2 learners of English in the COREFL learner corpus. With a corpus-based approach, the errors were analysed from a grammatical point of view. The errors were also sorted according to some variables, including the learners’ proficiency level and the texts’ medium. The data analyses were carried out on Microsoft Excel, to perform calculations and visualize the results by putting the data into tables and charts. The results were also normalised in order to correctly compare them. The findings suggest that the Spanish learners make more errors than the German learners, but both groups produce the errors mostly in the spoken medium. The results are also discussed in relation to some theories and hypotheses coming from the field of Second Language Acquisition. The dissertation concludes by presenting some possible causes for this error type and some possible solutions to overcome it

Recursive Least Squares Filtering Algorithms for On-Line Viscoelastic Characterization of Biosamples

The mechanical characterization of biological samples is a fundamental issue in biology and related fields, such as tissue and cell mechanics, regenerative medicine and diagnosis of diseases. In this paper, a novel approach for the identification of the stiffness and damping coefficients of biosamples is introduced. According to the proposed method, a MEMS-based microgripper in operational condition is used as a measurement tool. The mechanical model describing the dynamics of the gripper-sample system considers the pseudo-rigid body model for the microgripper, and the Kelvin–Voigt constitutive law of viscoelasticity for the sample. Then, two algorithms based on recursive least square (RLS) methods are implemented for the estimation of the mechanical coefficients, that are the forgetting factor based RLS and the normalised gradient based RLS algorithms. Numerical simulations are performed to verify the effectiveness of the proposed approach. Results confirm the feasibility of the method that enables the ability to perform simultaneously two tasks: sample manipulation and parameters identification

Contract agreements via logic

We relate two contract models: one based on event structures and game theory, and the other one based on logic. In particular, we show that the notions of agreement and winning strategies in the game-theoretic model are related to that of provability in the logical model.Comment: In Proceedings ICE 2013, arXiv:1310.401

A linear quadratic regulator for nonlinear SIRC epidemic model

The control of an epidemic disease consists in introducing the strategies able to reduce the number of infected subjects by means of medication/quarantine actions, and the number of the subjects that could catch the disease through an informative campaign and, when available, a vaccination strategy. Some diseases, like the influenza, do not guarantee immunity; therefore, the subjects could get ill again by different strain of the same viral subtype. The epidemic model adopted in this paper introduces the cross-immune individuals; it is known in literature as SIRC model, since the classes of susceptible (S), infected (I), removed (R) and cross-immune (C) subjects are considered. Its control is herein determined in the framework of the linear quadratic regulator, by applying to the original nonlinear model the optimal control found on the linearized system. The results appear satisfactory, and the drawback of using a control law based on the linear approximation of the system is compensated by the advantages arising from such a solution: no costate equations to be solved and a solution depending on the current state evolution which allows a feedback implementation