Feedback Setting Research Articles

Which Intervention Characteristics are Related to More Exposure to Internet-Delivered Healthy Lifestyle Promotion Interventions? A Systematic Review

BackgroundThe Internet has become a popular medium for the delivery of tailored healthy lifestyle promoting interventions. The actual reach of Internet-delivered interventions seems, however, lower than expected, and attrition from interventions is generally high. Characteristics of an intervention, such as personally tailored feedback and goal setting, are thought to be among the important factors related to of use of and exposure to interventions. However, there is no systematic overview of which characteristics of Internet-delivered interventions may be related to more exposure.ObjectiveThe present study aims to identify (1) which potentially exposure-promoting methods and strategies are used in existing Internet interventions, (2) which objective outcome measures are used to measure exposure to Internet interventions, and (3) which potentially exposure-promoting methods and strategies are associated with better exposure.MethodsA systematic review of the literature was conducted based on the Cochrane guidelines. Papers published between 1995 and 2009 were searched in the PubMed, PsycINFO, and Web of Science databases. In total, 64 studies were included that reported objective exposure measures such as completion of an initial visit, number of log-ins, and time spent on the website. Information about intervention-related characteristics (ie, interactive behavior change strategies, interactive elements for fun, peer or counsel support, email/phone contact, and regular updates of the website) that could potentially contribute to better exposure and objective exposure outcomes were abstracted from the studies and qualitative systematic descriptive analyses were performed.ResultsThe results showed that a large variety of behavior change techniques and other exposure-promoting elements were used in the interventions and that these methods and strategies varied for the various lifestyle behaviors. Feedback, interactive elements, and email/phone contact were used most often. In addition, there was much variety and a lack of consistency in the exposure measures that were reported. Of all the categories of intervention characteristics that may be associated with better exposure, there were indications that peer and counselor support result in a longer website visit and that email/phone contact and updates of the website result in more log-ins.ConclusionsResults of this qualitative systematic review indicate that of all intervention characteristics that could potentially enhance exposure, only peer support, counselor support, email/phone contact with visitors, and updates of the intervention website were related to better exposure. The diversity of intervention methods used and the inconsistency in the report of exposure measures prevented us from drawing firmer conclusions. More research is needed to identify whether other characteristics of Internet interventions are associated with greater exposure.

Distributed Adaptation of Quantized Feedback for Downlink Network MIMO Systems

This paper focuses on quantized channel state information (CSI) feedback for downlink network MIMO systems. Specifically, we propose to quantize and feedback the CSI of a subset of BSs, namely the feedback set. Our analysis reveals the tradeoff between better interference mitigation with large feedback set and high CSI quantization precision with small feedback set. Given the number of feedback bits and instantaneous/long-term channel conditions, each user optimizes its feedback set distributively according to the expected SINR derived from our analysis. Simulation results show that the proposed feedback adaptation scheme provides substantial performance gain over non-adaptive schemes, and is able to effectively exploit the benefits of network MIMO under various feedback bit budgets.

Lateral Manipulation of Single Defect on Insulating Surface Using Noncontact Atomic Force Microscope

A single atomic defect on an ionic crystal surface was manipulated at the atomic level using an atomic force microscope. During raster scanning, the defect was manipulated at near the tip–sample distance and at room temperature. The defect, which is imaged as a sharp half-moon shape, moves continuously if the tip is close to the sample surface. The defect randomly moves along a zigzag or straight path or jumps long distances. The movement of the defect on an insulator is complex in contrast to that on semiconductors. The defect moves suddenly owing to the tip approaching the surface when the distance feedback is overshot under the condition of a large difference in frequency shift between the feedback set point and a weak interaction on the defect.

Linear programming based approximation algorithms for feedback set problems in bipartite tournaments

We consider the feedback vertex set and feedback arc set problems on bipartite tournaments. We improve on recent results by giving a 2-approximation algorithm for the feedback vertex set problem. We show that this result is the best that we can attain when using optimal solutions to a certain linear program as a lower bound on the optimal value. For the feedback arc set problem on bipartite tournaments, we show that a recent 4-approximation algorithm proposed by Gupta (2008) [8] is incorrect. We give an alternative 4-approximation algorithm based on an algorithm for the feedback arc set on (non-bipartite) tournaments given by van Zuylen and Williamson (2009) [14].

Psychometric Properties of the Purdue Pharmacist Directive Guidance (PPDG) Scale in a Sample of Diabetes Patients in the Southwestern United States

Despite the fairly widespread adoption of the 10-item Purdue Pharmacist Directive Guidance Scale (PPDG) over the last decade, only one study has assessed its psychometric properties. The present study examined the validity and reliability of the scale in a sample of 99 diabetic patients in the Southwestern United States. Principal axis factor analysis with Varimax rotation yielded two factors, "Instruction" and "Feedback and Goal Setting," similar to those found when the scale was originally developed. Cronbach's alphas for the total scale and the two factors were 0.95, 0.95, and 0.92, respectively. The scale and the two factors correlated significantly and positively with number of visits by patients to the pharmacist in the past 3 mo. These results provide further evidence for the internal consistency, and construct and criterion-related validities of the scale.

PSYCHOMETRIC PROPERTIES OF THE PURDUE PHARMACIST DIRECTIVE GUIDANCE (PPDG) SCALE IN A SAMPLE OF DIABETES PATIENTS IN THE SOUTHWESTERN UNITED STATES1

Despite the fairly widespread adoption of the 10-item Purdue Pharmacist Directive Guidance Scale (PPDG) over the last decade, only one study has assessed its psychometric properties. The present study examined the validity and reliability of the scale in a sample of 99 diabetic patients in the Southwestern United States. Principal axis factor analysis with Varimax rotation yielded two factors, “Instruction” and “Feedback and Goal Setting,” similar to those found when the scale was originally developed. Cronbach's alphas for the total scale and the two factors were 0.95, 0.95, and 0.92, respectively. The scale and the two factors correlated significantly and positively with number of visits by patients to the pharmacist in the past 3 mo. These results provide further evidence for the internal consistency, and construct and criterion-related validities of the scale.

Effect of accelerometry on the functional mobility of older rehabilitation inpatients as measured by functional independence measure--locomotion (FIM) gain: a retrospective matched cohort study.

To examine the effect of wearing an accelerometer (without provision of feedback) on the mobility of older rehabilitation inpatients, using the locomotion component of the FIM at admission and discharge. A retrospective matched cohort study of patients aged >60 years admitted to a rehabilitation unit between 1 January 2008 and 1 January 2009. The exposed group was 17 patients who had worn an accelerometer daily during their rehabilitation stay. These patients were matched with 17 controls (the unexposed group) identified from the unit database using the following variables: age (within 5 years), sex, admission Functional Independence Measure (locomotion) score and reason for admission to rehabilitation. The median length of stay, median FIM (locomotion) gain and median FIM (locomotion) efficiency for the two groups were compared using the Wilcoxon Signed Ranks Test. There were no statistically significant differences between the two groups at baseline. There was a trend towards a greater FIM-locomotion gain in the accelerometer group (mean 2.88+/- 2.12, median 3.00) compared with the no-accelerometer group (mean 2.53+/- 2.07, median 3.00), but this did not reach statistical significance (p=0.08). There was no significant difference in the FIM -locomotion efficiency for the accelerometer group (mean 0.08 +/- 0.07, median 0.05) compared with the no accelerometer group(mean 0.01 +/- 0.09, median 0.06) (p= 0.33). In the absence of feedback and goal setting, wearing a monitoring device does not significantly increase physical activity.

Design of switched linear systems in the presence of actuator saturation and L-infinity disturbances

This paper considers the problem of disturbance tolerance/rejection of a switched system resulting from a family of linear systems subject to actuator saturation and L-infinity disturbances. For a given set of linear feedback gains, a given switching scheme and a given bound on the L-infinity norm of the disturbances, conditions are established, in terms of linear or bilinear matrix inequalities, under which a set of a certain form is invariant for a given switched linear system in the presence of actuator saturation and L-infinity disturbances, and the closed-loop system possesses a certain level of disturbance rejection capability. With these conditions, the design of feedback gains and switching scheme can be formulated and solved as constrained optimization problems. Disturbance tolerance is measured by the largest bound on the disturbances for which the trajectories starting from a given set remain bounded. Disturbance rejection is measured either by the L-infinity norm of the system output or by the system’s ability to steer its state into and/or keep it within a small neighborhood of the origin. In the event that all systems in the family are identical, the switched system reduces to a single system under a switching feedback law. Simulation results show that such a single system under a switching feedback law could have stronger disturbance tolerance/rejection capability than a single linear feedback law can.

Feedback min–max model predictive control using robust one-step sets

A solution to the infinite-horizon min–max model predictive control (MPC) problem of constrained polytopic systems has recently been defined in terms of a sequence of free control moves over a fixed horizon and a state feedback law in the terminal region using a time-varying terminal cost. The advantage of this formulation is the enlargement of the admissible set of initial states without sacrificing local optimality, but this comes at the expense of higher computational complexity. This article, by means of a counterexample, shows that the robust feasibility and stability properties of such algorithms are not, in general, guaranteed when more than one control move is adopted. For this reason, this work presents a novel formulation of min–max MPC based on the concept of within-horizon feedback and robust contractive set theory that ensures robust stability for any choice of the control horizon. A parameter-dependent feedback extension is also proposed and analysed. The effectiveness of the algorithms is demonstrated with two numerical examples.

FPT algorithms for path-transversal and cycle-transversal problems

We study the parameterized complexity of several vertex- and edge-deletion problems on graphs, parameterized by the number p of deletions. The first kind of problems are separation problems on undirected graphs, where we aim at separating distinguished vertices in a graph. The second kind of problems are feedback set problems on group-labelled graphs, where we aim at breaking nonnull cycles in a graph having its arcs labelled by elements of a group. We obtain new FPT algorithms for these different problems, relying on a generic O ∗ ( 4 p ) algorithm for breaking paths of a homogeneous path system.

Enhancing the Motivational Affordance of Information Systems: The Effects of Real-Time Performance Feedback and Goal Setting in Group Collaboration Environments

Increasing globalization has created tremendous opportunities and challenges for organizations and societies. Consequently, a broad range of information technologies to better support the collaboration of diverse, and increasingly distributed, sets of participants is ever more utilized. Arguably, the success of such technology-mediated collaboration is dependent upon the quality of each individual's contributions; however, although individuals' motivations to do their best could be significantly influenced by the design of a system's human–computer interface, this area has received little attention within the context of group collaboration environments. We fill this gap by integrating research from human–computer interaction, motivation, and technology-supported group work to theoretically derive mechanisms for increasing each individual's motivation within a collective setting. Specifically, we manipulate the interface of a computer-mediated idea generation system (a widely used collaboration tool) to enhance the system's motivational affordance, i.e., the system's properties that fulfill users' motivational needs. Results from two studies demonstrate that by embedding the theoretically derived mechanisms “providing feedback” and “designing for optimal challenge” into the collaboration environment, significant performance gains were realized. The results suggest that even slight manipulations of the human–computer interface can contribute significantly to the successful design of a wide variety of group collaboration environments.

Control of a separated boundary layer: reduced-order modeling using global modes revisited

The possibility of model reduction using global modes is readdressed, aiming at the controlling of a globally unstable separation bubble induced by a bump geometry. A combined oblique and orthogonal projection approach is proposed to design an estimator and controller in a Riccati-type feedback setting. An input–output criterion is used to appropriately select the modes of the projection basis. The full-state linear instability dynamics is shown to be successfully controlled by the feedback coupling with controllers of moderate degrees of freedom.

Design of a Robust State Feedback Controller for a STATCOM Using a Zero Set Concept

A static synchronous compensator (STATCOM) is one of the fundamental flexible ac transmission system devices that can be used for voltage regulation and dynamic voltage control. In this paper, a new approach to the problem of the STATCOM state feedback design is presented. The proposed solution technique is based on a zero set concept. It allows one to calculate a complete set of the admissible feedback gains that place closed-loop poles into a prespecified region in the complex plane under parametric uncertainties in the plant model. These uncertainties represent load pattern variations and topological changes due to line tripping. Computational examples show that by using the design technique based on the zero set concept, it is possible to derive the state feedback controllers with better robustness properties than those achieved using the approaches utilizing linear matrix inequalities.

Adaptive Control for a Mobile Robot Under Slip Conditions Using an LMI-Based Approach

This paper presents a control law for the trajectory tracking of mobile robots under slip conditions and subject to both system constraints and varying dynamics. First, a control law is obtained based on a Lyapunov function to guarantee closed-loop asymptotic stability, resulting in a set of feedback gains, one for each extreme model realization. On-line computation is devoted to determine an adaptive feedback control law for the current realization of the state as a convex combination of the gains previously obtained. Simulations comparing the proposed control law with other strategies under slip conditions are provided. They show the satisfactory behavior of the proposed control strategy.

Effect of directorial intervention on web‐based student feedback

The Medical Faculty of the University of Helsinki decided to employ a web-based evaluation system as an integral and essential part of all courses beginning in the autumn term of 2006. To analyse the effects of the intervention on dental students' web-based responses at the University of Helsinki, Finland. A previously developed web-based tool was used for all preclinical and clinical courses from the beginning of the 2006-2007 academic year. We analysed data sets of student feedback for all courses before (2005-2006) and after (2006-2007) the intervention. We then compared the quantity and quality of the students' feedback for the six standardised questions used in the evaluation, and calculated the means and standard deviations of values obtained with a Likert scale. The students' assessments in the open questions were categorised according to key issues. Implementation of the system resulted in a considerable increase in student feedback: the mean response rate for the preclinical phase rose from 59% (SD 15.0; range 25-80) before the intervention to 90% (SD 9.6; range 72-100) after it. In the clinical phase, the response rates more than doubled from 34% (SD 15.9; range 9-69) to 73% (SD 12.9; range 45-100). The students' assessments showed no significant change despite the marked rise in response rates. The educators' positive attitude towards the students was appreciated (4.2-4.3) whereas the general goals for the courses in the clinical phase seemed unclear to the students (3.4) (P < 0.05). Web-based evaluation as an integral part of all courses in the dental curriculum proved successful: shortly after the intervention, we observed a considerable increase in student feedback with no significant change in quality.

Similarity Learning for 3D Object Retrieval Using Relevance Feedback and Risk Minimization

We introduce a similarity learning scheme to improve the 3D object retrieval performance in a relevance feedback setting. The proposed algorithm relies on a score fusion approach that linearly combines elementary similarity scores originating from different shape descriptors into a final similarity function. Each elementary score is modeled in terms of the posterior probability of a database item being relevant to the user-provided query. The posterior parameters are learned via off-line discriminative training, while the optimal combination of weights to generate the final similarity function is obtained by on-line empirical ranking risk minimization. This joint use of on-line and off-line learning methods in relevance feedback not only improves the retrieval performance significantly as compared to the totally unsupervised case, but also outperforms the standard support vector machines based approach. Experiments on several 3D databases, including the Princeton Shape Benchmark, show also that the proposed algorithm has a better small sample behavior.

Leveraging Champions to Build a Knowledge Management System for the Research and Development and Marketing Interface

The research and development (R&D)-marketing interface is one of the most critical elements in the development of commercially successful products. When these two departments can effectively link their processes and information sharing, companies can improve their product development efforts. Champions contribute to the success of this relationship by facilitating the information flow in five critical success factors (CSFs): customer requirements, customer feedback, competition, product development, and goal setting. Management can help the efforts of champions by establishing a knowledge management system (KMS) based on the CSFs. Integrating principles and methodologies from customer relationship management (CRM), an organization can develop a framework to establish a KMS for the R&D-marketing interface.

Feedback control by low-order modelling of the laminar flow past a bluff body

In this work a two-dimensional laminar flow past a square cylinder is considered. Actuators placed on the cylinder enable active control by blowing and suction. Proportional feedback control is then applied using velocity measurements taken in the cylinder wake. Projection onto an empirical subspace is combined with a calibration technique to build a low-order model of the incompressible Navier–Stokes equations. This model is used within an optimization method to determine a set of feedback gains which reduces the unsteadiness of the wake at Re = 150. The resulting controlled flows are further characterized by computing the critical Reynolds numbers for the onset of the vortex shedding instability.

Fixed-parameter tractability results for feedback set problems in tournaments

Complementing recent progress on classical complexity and polynomial-time approximability of feedback set problems in (bipartite) tournaments, we extend and improve fixed-parameter tractability results for these problems. We show that Feedback Vertex Set in tournaments (FVST) is amenable to the novel iterative compression technique, and we provide a depth-bounded search tree for Feedback Arc Set in bipartite tournaments based on a new forbidden subgraph characterization. Moreover, we apply the iterative compression technique to d- Hitting Set, which generalizes Feedback Vertex Set in tournaments, and obtain improved upper bounds for the time needed to solve 4- Hitting Set and 5- Hitting Set. Using our parameterized algorithm for Feedback Vertex Set in tournaments, we also give an exact (not parameterized) algorithm for it running in O ( 1.709 n ) time, where n is the number of input graph vertices, answering a question of Woeginger [G.J. Woeginger, Open problems around exact algorithms, Discrete Appl. Math. 156 (3) (2008) 397–405].

Decomposition principle in model predictive control for linear systems with bounded disturbances

Considering a constrained linear system with bounded disturbances, this paper proposes a novel approach which aims at enlarging the domain of attraction by combining a set-based MPC approach with a decomposition principle. The idea of the paper is to extend the “pre-stabilizing” MPC, where the MPC control sequence is parameterized as perturbations to a given pre-stabilizing feedback gain, to the case where the pre-stabilizing feedback law is given as the linear combination of a set of feedback gains. This procedure leads to a relatively large terminal set and consequently a large domain of attraction even when using short prediction horizons. As time evolves, by minimizing the nominal performance index, the resulting controller reaches the desired optimal controller with a good asymptotic performance. Compared to the standard “pre-stabilizing” MPC, it combines the advantages of having a flexible choice of feedback gains, a large domain of attraction and a good asymptotic behavior.