778 research outputs found
Multi-Shooting Differential Dynamic Programming for Hybrid Systems using Analytical Derivatives
Differential Dynamic Programming (DDP) is a popular technique used to
generate motion for dynamic-legged robots in the recent past. However, in most
cases, only the first-order partial derivatives of the underlying dynamics are
used, resulting in the iLQR approach. Neglecting the second-order terms often
slows down the convergence rate compared to full DDP. Multi-Shooting is another
popular technique to improve robustness, especially if the dynamics are highly
non-linear. In this work, we consider Multi-Shooting DDP for trajectory
optimization of a bounding gait for a simplified quadruped model. As the main
contribution, we develop Second-Order analytical partial derivatives of the
rigid-body contact dynamics, extending our previous results for fixed/floating
base models with multi-DoF joints. Finally, we show the benefits of a novel
Quasi-Newton method for approximating second-order derivatives of the dynamics,
leading to order-of-magnitude speedups in the convergence compared to the full
DDP method.Comment: https://www.youtube.com/watch?v=C0h6mEpcnA
Novel inferences of ionisation & recombination for particle/power balance during detached discharges using deuterium Balmer line spectroscopy
The physics of divertor detachment is determined by divertor power, particle
and momentum balance. This work provides a novel analysis technique of the
Balmer line series to obtain a full particle/power balance measurement of the
divertor. This supplies new information to understand what controls the
divertor target ion flux during detachment.
Atomic deuterium excitation emission is separated from recombination
quantitatively using Balmer series line ratios. This enables analysing those
two components individually, providing ionisation/recombination source/sinks
and hydrogenic power loss measurements. Probabilistic Monte Carlo techniques
were employed to obtain full error propagation - eventually resulting in
probability density functions for each output variable. Both local and overall
particle and power balance in the divertor are then obtained. These techniques
and their assumptions have been verified by comparing the analysed synthetic
diagnostic 'measurements' obtained from SOLPS simulation results for the same
discharge. Power/particle balance measurements have been obtained during
attached and detached conditions on the TCV tokamak.Comment: The analysis results of this paper were formerly in arXiv:1810.0496
Does patient satisfaction of general practice change over a decade?
Background The Patient Participation Program (PPP) was a patient satisfaction survey endorsed by the Royal Australian College of General Practitioners and designed to assist general practitioners in continuous quality improvement (CQI). The survey was been undertaken by 3500 practices and over a million patients between 1994 and 2003. This study aimed to use pooled patient questionnaire data to investigate changes in satisfaction with primary care over time. Methods The results of 10 years of the PPP surveys were analyzed with respect to 10 variables including the year of completion, patient age, gender, practice size, attendance at other doctors, and whether the practice had previously undertaken the survey. Comparisons were made using Logistic Generalized Estimating Equations (LGEE). Results There was a very high level of satisfaction with general practice in Australia (99% of respondents). An independent indicator of satisfaction was created by pooling the results of 12 questions. This new indicator had a greater variance than the single overall satisfaction question. Participants were shown to have higher levels of satisfaction if they were male, older, did not attend other practitioners or the practice was small in size. A minimal improvement in satisfaction was detected in this pooled indicator for the second or third survey undertaken by a practice. There was however no statistically significant change in pooled satisfaction with the year of survey. Conclusion The very high level of satisfaction made it difficult to demonstrate change. It is likely that this and the presentation of results made it difficult for GPs to use the survey to improve their practices. A more useful survey would be more sensitive to detect negative patient opinions and provide integrated feedback to GPs. At present, there are concerns about the usefulness of the PPP in continuous quality improvement in general practice.James Allan, Peter Schattner, Nigel Stocks and Emmae Ramsa
Does patient satisfaction of general practice change over a decade?
Background The Patient Participation Program (PPP) was a patient satisfaction survey endorsed by the Royal Australian College of General Practitioners and designed to assist general practitioners in continuous quality improvement (CQI). The survey was been undertaken by 3500 practices and over a million patients between 1994 and 2003. This study aimed to use pooled patient questionnaire data to investigate changes in satisfaction with primary care over time. Methods The results of 10 years of the PPP surveys were analyzed with respect to 10 variables including the year of completion, patient age, gender, practice size, attendance at other doctors, and whether the practice had previously undertaken the survey. Comparisons were made using Logistic Generalized Estimating Equations (LGEE). Results There was a very high level of satisfaction with general practice in Australia (99% of respondents). An independent indicator of satisfaction was created by pooling the results of 12 questions. This new indicator had a greater variance than the single overall satisfaction question. Participants were shown to have higher levels of satisfaction if they were male, older, did not attend other practitioners or the practice was small in size. A minimal improvement in satisfaction was detected in this pooled indicator for the second or third survey undertaken by a practice. There was however no statistically significant change in pooled satisfaction with the year of survey. Conclusion The very high level of satisfaction made it difficult to demonstrate change. It is likely that this and the presentation of results made it difficult for GPs to use the survey to improve their practices. A more useful survey would be more sensitive to detect negative patient opinions and provide integrated feedback to GPs. At present, there are concerns about the usefulness of the PPP in continuous quality improvement in general practice.James Allan, Peter Schattner, Nigel Stocks and Emmae Ramsa
CACTO: Continuous Actor-Critic with Trajectory Optimization -- Towards global optimality
This paper presents a novel algorithm for the continuous control of dynamical
systems that combines Trajectory Optimization (TO) and Reinforcement Learning
(RL) in a single framework. The motivations behind this algorithm are the two
main limitations of TO and RL when applied to continuous nonlinear systems to
minimize a non-convex cost function. Specifically, TO can get stuck in poor
local minima when the search is not initialized close to a "good" minimum. On
the other hand, when dealing with continuous state and control spaces, the RL
training process may be excessively long and strongly dependent on the
exploration strategy. Thus, our algorithm learns a "good" control policy via
TO-guided RL policy search that, when used as initial guess provider for TO,
makes the trajectory optimization process less prone to converge to poor local
optima. Our method is validated on several reaching problems featuring
non-convex obstacle avoidance with different dynamical systems, including a car
model with 6D state, and a 3-joint planar manipulator. Our results show the
great capabilities of CACTO in escaping local minima, while being more
computationally efficient than the Deep Deterministic Policy Gradient (DDPG)
and Proximal Policy Optimization (PPO) RL algorithms.Comment: 8 pages, 8 figures. Submitted to IEEE RA-
A research agenda on patient safety in primary care. Recommendations by the LINNEAUS collaboration on patient safety in primary care
This is the final version of the article. Available from Taylor & Francis via the DOI in this record.BACKGROUND: Healthcare can cause avoidable serious harm to patients. Primary care is not an exception, and the relative lack of research in this area lends urgency to a better understanding of patient safety, the future research agenda and the development of primary care oriented safety programmes. OBJECTIVE: To outline a research agenda for patient safety improvement in primary care in Europe and beyond. METHODS: The LINNEAUS collaboration partners analysed existing research on epidemiology and classification of errors, diagnostic and medication errors, safety culture, and learning for and improving patient safety. We discussed ideas for future research in several meetings, workshops and congresses with LINNEAUS collaboration partners, practising GPs, researchers in this field, and policy makers. RESULTS: This paper summarizes and integrates the outcomes of the LINNEAUS collaboration on patient safety in primary care. It proposes a research agenda on improvement strategies for patient safety in primary care. In addition, it provides background information to help to connect research in this field with practicing GPs and other healthcare workers in primary care. CONCLUSION: Future research studies should target specific primary care domains, using prospective methods and innovative methods such as patient involvement.The research leading to these results has received funding from the European Community’s Seventh Framework Programme FP7/2008–2012 under grant agreement no. 223424
General practitioners' experience and benefits from patient evaluations
<p>Abstract</p> <p>Background</p> <p>It has now for many years been recognised that patient evaluations should be undertaken as an integral part of the complex task of improving the quality of general practice care. Yet little is known about the general practitioners' (GPs') benefit from patient evaluations. Aim 1 was to study the impact on the GPs of a patient evaluation and subsequent feedback of results presented at a plenary session comprising a study guide for the results and group discussions. Aim 2 was to study possible facilitators and barriers to the implementations of the results raised by the patient evaluation process.</p> <p>Methods</p> <p>A patient evaluation survey of 597 voluntarily participating GPs was performed by means of the EUROPEP questionnaire. Evaluation results were fed back to the GPs as written reports at a single feedback meeting with group discussions of the results. Between 3 and 17 months after the feedback, the 597 GPs received a questionnaire with items addressing their experience with and perceived benefit from the evaluations.</p> <p>Results</p> <p>79.4% of the GPs responded. 33% of the responding GPs reported that the patient evaluation had raised their attention to the patient perspective on the quality of general practice care. Job satisfaction had improved among 26%, and 21% had developed a more positive attitude to patient evaluations. 77% of the GPs reported having learnt from the evaluation. 54% had made changes to improve practice, 82% would recommend a patient evaluation to a colleague and 75% would do another patient evaluation if invited. 14% of the GPs had become less positive towards patient evaluations, and job satisfaction had decreased among 3%.</p> <p>Conclusions</p> <p>We found a significant impact on the GPs regarding satisfaction with the process and attitude towards patient evaluations, GPs' attention to the patients' perspective on care quality and their job satisfaction. Being benchmarked against the average seemed to raise barriers to the concept of patient evaluations and difficulties interpreting the results may have formed a barrier to their implementation which was partly overcome by adding qualitative data to the quantitative results. The GPs' significant willingness to share and discuss the results with others may have served as a facilitator.</p
Hybrid Volitional Control of a Robotic Transtibial Prosthesis using a Phase Variable Impedance Controller
For robotic transtibial prosthesis control, the global kinematics of the
tibia can be used to monitor the progression of the gait cycle and command
smooth and continuous actuation. In this work, these global tibia kinematics
are used to define a phase variable impedance controller (PVIC), which is then
implemented as the nonvolitional base controller within a hybrid volitional
control framework (PVI-HVC). The gait progression estimation and biomechanic
performance of one able-bodied individual walking on a robotic ankle prosthesis
via a bypass adapter are compared for three control schemes: a passive
benchmark controller, PVIC, and PVI-HVC. The different actuation of each
controller had a direct effect on the global tibia kinematics, but the average
deviation between the estimated and ground truth gait percentage were 1.6%,
1.8%, and 2.1%, respectively, for each controller. Both PVIC and PVI-HVC
produced good agreement with able-bodied kinematic and kinetic references. As
designed, PVI-HVC results were similar to those of PVIC when the user used low
volitional intent, but yielded higher peak plantarflexion, peak torque, and
peak power when the user commanded high volitional input in late stance. This
additional torque and power also allowed the user to volitionally and
continuously achieve activities beyond level walking, such as ascending ramps,
avoiding obstacles, standing on tip-toes, and tapping the foot. In this way,
PVI-HVC offers the kinetic and kinematic performance of the PVIC during level
ground walking, along with the freedom to volitionally pursue alternative
activities.Comment: 7 pages, 7 figures, submitted to ICRA 202
Tearing down walls: opening the border between hospital and ambulatory care for quality improvement in Germany
The hospital benchmarking system in Germany was originally introduced to detect unintended consequences of reimbursement based on diagnosis-related groups. The new nationwide SQG programme aims to provide information on quality and outcomes of health care provided in hospital, ambulatory specialist and primary care settings, including the healthcare delivery across different sectors. In 2010 the topics for indicator development were cataract surgery, cervical conization, colectoral cancer and percutaneous coronary interventions or coronary angiography. A systematic stepwise modified RAND/UCLA procedure is applied to develop quality indicators in each of these domains. A general framework for data collection is implemented. Benchmarking results are fed back to providers on a regular basis
Patient Care Teams in treatment of diabetes and chronic heart failure in primary care: an observational networks study
Contains fulltext :
97203.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Patient care teams have an important role in providing medical care to patients with chronic disease, but insight into how to improve their performance is limited. Two potentially relevant determinants are the presence of a central care provider with a coordinating role and an active role of the patient in the network of care providers. In this study, we aimed to develop and test measures of these factors related to the network of care providers of an individual patient. METHODS: We performed an observational study in patients with type 2 diabetes or chronic heart failure, who were recruited from three primary care practices in The Netherlands. The study focused on medical treatment, advice on physical activity, and disease monitoring. We used patient questionnaires and chart review to measure connections between the patient and care providers, and a written survey among care providers to measure their connections. Data on clinical performance were extracted from the medical records. We used network analysis to compute degree centrality coefficients for the patient and to identify the most central health professional in each network. A range of other network characteristics were computed including network centralization, density, size, diversity of disciplines, and overlap among activity-specific networks. Differences across the two chronic conditions and associations with disease monitoring were explored. RESULTS: Approximately 50% of the invited patients participated. Participation rates of health professionals were close to 100%. We identified 63 networks of 25 patients: 22 for medical treatment, 16 for physical exercise advice, and 25 for disease monitoring. General practitioners (GPs) were the most central care providers for the three clinical activities in both chronic conditions. The GP's degree centrality coefficient varied substantially, and higher scores seemed to be associated with receiving more comprehensive disease monitoring. The degree centrality coefficient of patients also varied substantially but did not seem to be associated with disease monitoring. CONCLUSIONS: Our method can be used to measure connections between care providers of an individual patient, and to examine the association between specific network parameters and healthcare received. Further research is needed to refine the measurement method and to test the association of specific network parameters with quality and outcomes of healthcare
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