Impact on adherence of a telephone follow up strategy in HIV-naïve patients who start antiretroviral therapy: cohort study

Antiretroviral therapy changed the prognosis of people living with HIV/AIDS. However, lack of adherence jeopardizes the success of antiretroviral therapy and enhances the development of treatment-resistant strains, treatment failure, and therefore it stands as a public health problem. The main goal of this study was to measure the impact on treatment discontinuations and lost to follow up, of a telephone follow-up strategy in naïve patients who start antiretroviral therapy. We conducted a single-site, cohort study during a 12-month period (May 2011–May 2012). A prospective cohort of naïve patients received the standard of care plus a specific telephone follow-up strategy. Results were compared with a retrospective cohort of naïve patients followed up at the same site, who started antiretroviral therapy receiving only the standard of care during a similar period (January–December 2009). We used descriptive statistics and Fisher exact test for the comparisons of variables. We enrolled 41 patients in the prospective cohort and 50 in the retrospective one. Both cohorts had similar general characteristics. We found a lower number of patients who were lost to follow up in the prospective cohort (intervention) consistent with lower rates of treatment abandonment, suspensions and a similar tendency for events, including death, even when none of these findings was statistically significant. Baseline characteristics and main results are shown in the table below. Further randomized studies should be conducted applying a telephone follow-up strategy to confirm these findings

Secondary Frequency and Voltage Control of Islanded Microgrids via Distributed Averaging

In this work we present new distributed controllers for secondary frequency and voltage control in islanded microgrids. Inspired by techniques from cooperative control, the proposed controllers use localized information and nearest-neighbor communication to collectively perform secondary control actions. The frequency controller rapidly regulates the microgrid frequency to its nominal value while maintaining active power sharing among the distributed generators. Tuning of the voltage controller provides a simple and intuitive trade-off between the conflicting goals of voltage regulation and reactive power sharing. Our designs require no knowledge of the microgrid topology, impedances or loads. The distributed architecture allows for flexibility and redundancy, and eliminates the need for a central microgrid controller. We provide a voltage stability analysis and present extensive experimental results validating our designs, verifying robust performance under communication failure and during plug-and-play operation.Comment: Accepted for publication in IEEE Transactions on Industrial Electronic

Moving constraints as stabilizing controls in classical mechanics

The paper analyzes a Lagrangian system which is controlled by directly assigning some of the coordinates as functions of time, by means of frictionless constraints. In a natural system of coordinates, the equations of motions contain terms which are linear or quadratic w.r.t.time derivatives of the control functions. After reviewing the basic equations, we explain the significance of the quadratic terms, related to geodesics orthogonal to a given foliation. We then study the problem of stabilization of the system to a given point, by means of oscillating controls. This problem is first reduced to the weak stability for a related convex-valued differential inclusion, then studied by Lyapunov functions methods. In the last sections, we illustrate the results by means of various mechanical examples.Comment: 52 pages, 4 figure

Dynamic Vehicle Routing for Robotic Systems

Recent years have witnessed great advancements in the science and technology of autonomy, robotics, and networking. This paper surveys recent concepts and algorithms for dynamic vehicle routing (DVR), that is, for the automatic planning of optimal multivehicle routes to perform tasks that are generated over time by an exogenous process. We consider a rich variety of scenarios relevant for robotic applications. We begin by reviewing the basic DVR problem: demands for service arrive at random locations at random times and a vehicle travels to provide on-site service while minimizing the expected wait time of the demands. Next, we treat different multivehicle scenarios based on different models for demands (e.g., demands with different priority levels and impatient demands), vehicles (e.g., motion constraints, communication, and sensing capabilities), and tasks. The performance criterion used in these scenarios is either the expected wait time of the demands or the fraction of demands serviced successfully. In each specific DVR scenario, we adopt a rigorous technical approach that relies upon methods from queueing theory, combinatorial optimization, and stochastic geometry. First, we establish fundamental limits on the achievable performance, including limits on stability and quality of service. Second, we design algorithms, and provide provable guarantees on their performance with respect to the fundamental limits.United States. Air Force Office of Scientific Research (Award FA 8650-07-2-3744)United States. Army Research Office. Multidisciplinary University Research Initiative (Award W911NF-05-1-0219)National Science Foundation (U.S.) (Award ECCS-0705451)National Science Foundation (U.S.) (Award CMMI-0705453)United States. Army Research Office (Award W911NF-11-1-0092

Proportional Derivative (PD) Control on the Euclidean Group

In this paper we study the stabilization problem for control systems defined on SE(3) (the special Euclidean group of rigid-body motions) and its subgroups. Assuming one actuator is available for each degree of freedom, we exploit geometric properties of Lie groups (and corresponding Lie algebras) to generalize the classical proportional derivative (PD) control in a coordinate-free way. For the SO(3) case, the compactness of the group gives rise to a natural metric structure and to a natural choice of preferred control direction: an optimal (in the sense of geodesic) solution is given to the attitude control problem. In the SE(3) case, no natural metric is uniquely defined, so that more freedom is left in the control design. Different formulations of PD feedback can be adopted by extending the SO(3) approach to the whole of SE(3) or by breaking the problem into a control problem on SO(3) x R^3. For the simple SE(2) case, simulations are reported to illustrate the behavior of the different choices. We also discuss the trajectory tracking problem and show how to reduce it to a stabilization problem, mimicking the usual approach in R^n. Finally, regarding the case of underactuated control systems, we derive linear and homogeneous approximating vector fields for standard systems on SO(3) and SE(3)

Tracking for Fully Actuated Mechanical Systems: A Geometric Framework

We present a general framework for the control of Lagrangian systems with as many inputs as degrees of freedom. Relying on the geometry of mechanical systems on manifolds, we propose a design algorithm for the tracking problem. The notion of error function and transport map lead to a proper definition of configuration and velocity error. These are the crucial ingredients in designing a proportional derivative feedback and feedforward controller. The proposed approach includes as special cases a variety of results on control of manipulators, pointing devices and autonomous vehicles. Our design provides particular insight into both aerospace and underwater applications where the configuration manifold is a Lie group

Exercise prescription to improve clinical practice on cancer patients suffering chemotherapy-induced peripheral neuropathy undergoing treatment: a systematic review

This document aims to summarize and analyze systematically the current body of evidence about the effects of specific exercise proto- cols on physical function, balance control and quality of life in patients with peripheral neuropathy (PNP) induced by chemotherapy. Methods: Systematic Review, Literature survey Specific terms were identified for the literature research in MEDLINE, Scopus, Bandolier, PEDro, and Web of Science. Only studies pub- lished in peer-reviewed journals written in English language were considered. Four manuscripts were classified as eligible with 88 total participants, with an average of 57.1 years old. Quality appraisal classified two studies as high quality investigations while two with low quality. Results were summarized in the following domains: \u201cCIPN symptoms\u201d, \u201cStatic balance control\u201d, \u201cDynamic balance control\u201d, \u201cQuali- ty of life and Physical function\u201d. Results Specific exercise protocols were able to counteract common symptoms of chemotherapy-induced peripheral neuropathy (CIPN) during chemotherapy treatments. Significant improvements were detected on postural control. Additionally, patients\u2019 quality of life and inde- pendence were found ameliorated after exercise sessions, together with reductions on altered sensations and in other peripheral neu- ropathy symptoms. Combined exercise protocols including endurance, strength and sensorimotor training showed larger improvements. Conclusions Exercise prescriptions for cancer patients undergoing chemotherapy with CIPN symptoms should be recommended since these exercise interventions appeared as feasible and have been demonstrated as useful tools to counteract some common side effects of chemother- apeutic agents

Control on the Sphere and Reduced Attitude Stabilization

This paper focuses on a new geometric approach to (fully actuated) control systems on the sphere. Our control laws exploit the basic and intuitive notions of geodesic direction and of distance between points, and generalize the classical proportional plus derivative feedback (PD) without the need of arbitrary local coordinate charts. The stability analysis relies on an appropriate Lyapunov function, where the notion of distance and its properties are exploited. This methodology then applies to spin-axis stabilization of a spacecraft actuated by only two control torques: discarding the rotation about the unactuated axis, a reduced system is considered, whose state is in fact defined on the sphere. For this reduced stabilization problem our approach allows us not only to deal optimally with the inevitable singularity, but also to achieve simplicity, versatility and (coordinate independent) adaptive capabilities