Approximate Dynamic Programming via Sum of Squares Programming

We describe an approximate dynamic programming method for stochastic control problems on infinite state and input spaces. The optimal value function is approximated by a linear combination of basis functions with coefficients as decision variables. By relaxing the Bellman equation to an inequality, one obtains a linear program in the basis coefficients with an infinite set of constraints. We show that a recently introduced method, which obtains convex quadratic value function approximations, can be extended to higher order polynomial approximations via sum of squares programming techniques. An approximate value function can then be computed offline by solving a semidefinite program, without having to sample the infinite constraint. The policy is evaluated online by solving a polynomial optimization problem, which also turns out to be convex in some cases. We experimentally validate the method on an autonomous helicopter testbed using a 10-dimensional helicopter model.Comment: 7 pages, 5 figures. Submitted to the 2013 European Control Conference, Zurich, Switzerlan

On the connections between PCTL and Dynamic Programming

Probabilistic Computation Tree Logic (PCTL) is a well-known modal logic which has become a standard for expressing temporal properties of finite-state Markov chains in the context of automated model checking. In this paper, we give a definition of PCTL for noncountable-space Markov chains, and we show that there is a substantial affinity between certain of its operators and problems of Dynamic Programming. After proving some uniqueness properties of the solutions to the latter, we conclude the paper with two examples to show that some recovery strategies in practical applications, which are naturally stated as reach-avoid problems, can be actually viewed as particular cases of PCTL formulas.Comment: Submitte

Stochastic dynamics of genetic networks: modelling and parameter identification

Motivation: Identification of regulatory networks is typically based on deterministic models of gene expression. Increasing experimental evidence suggests that the gene regulation process is intrinsically random. To ensure accurate and thorough processing of the experimental data, stochasticity must be explicitly accounted for both at the modelling stage and in the design of the identification algorithms. Results: We propose a model of gene expression in prokaryotes where transcription is described as a probabilistic event, whereas protein synthesis and degradation are captured by first-order deterministic kinetics. Based on this model and assuming that the network of interactions is known, a method for estimating unknown parameters, such as synthesis and binding rates, from the outcomes of multiple time-course experiments is introduced. The method accounts naturally for sparse, irregularly sampled and noisy data and is applicable to gene networks of arbitrary size. The performance of the method is evaluated on a model of nutrient stress response in Escherichia coli. Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics onlin

A multiscale approximation scheme for explicit model predictive control with stability, feasibility, and performance guarantees

In this paper, an algorithm is introduced based on classical wavelet multiresolution analysis that returns a low complexity explicit model predictive control law built on a hierarchy of second order interpolating wavelets. It is proven that the resulting interpolation is everywhere feasible. Further, tests to confirm stability and to compute a bound on the performance loss are introduced. Since the controller approximation is built on a gridded hierarchy, the evaluation of the control law in real-time systems is naturally fast and runs in a bounded logarithmic time. A simple example is provided which both illustrates the approach and motivates further research in this direction

Fast Explicit Nonlinear Model Predictive Control Via Multiresolution Function Approximation with Guaranteed Stability Nonlinear Control Systems

In this paper an algorithm for nonlinear explicit model predictive control is introduced based on multiresolution function approximation that returns a low complexity approximate receding horizon control law built on a hierarchy of second order interpolets. Feasibility and stability guarantees for the approximate control law are given using reachability analysis, where interval methods are used to construct a capture basin (feasible region). A constructive algorithm is provided that combines adaptive function approximation with interval methods to build a receding horizon control law that is suboptimal, yet with a region of guaranteed feasibility and stability. The resulting control law is built on a grid hierarchy that is fast to evaluate in real-time systems

LCSH, SKOS and Linked Data

A technique for converting Library of Congress Subject Headings MARCXML to Simple Knowledge Organization System (SKOS) RDF is described. Strengths of the SKOS vocabulary are highlighted, as well as possible points for extension, and the integration of other semantic web vocabularies such as Dublin Core. An application for making the vocabulary available as linked-data on the Web is also described.Comment: Submission for the Dublin Core 2008 conference in Berli

Identifying Priorities for Physiotherapy Research in the UK: the James Lind Alliance Physiotherapy Priority Setting Partnership

Objectives To identify unanswered questions for physiotherapy research and help set and prioritise the top 10 generic research priorities for the UK physiotherapy profession; updating previous clinical condition- specific priorities to include patient and carer perspectives, and reflect changes in physiotherapy practice, service provision and new technologies. Design The James Lind Alliance (JLA) Priority Setting Partnership (PSP) methodology was adopted, utilising evidence review, survey and consensus methods. Participants Anyone with experience and/or an interest in UK physiotherapy: patients, carers, members of the public, physiotherapists, student physiotherapists, other healthcare professionals, researchers, educators, service providers, commissioners and policy makers. Results Five hundred and ten respondents (50% patients, carers or members of the public) identified 2152 questions (termed “uncertainties”). Sixty-five indicative questions were developed from the uncertainties using peer reviewed thematic analysis. These were ranked in a second national survey (1,020 responses (62% were complete)). The top 25 questions were reviewed in a final prioritisation workshop using an adapted nominal group technique. The top 10 research priorities focused on optimisation (top priority); access; effectiveness; patient and carer knowledge, experiences, needs and expectations; supporting patient engagement and self-management; diagnosis and prediction. Conclusions This study is currently the UK's most inclusive consultation exercise to identify patients‘and healthcare professionals‘priorities for physiotherapy research. The exercise deliberately sought to capture generic issues relevant to all specialisms within physiotherapy. The research priorities identified a range of gaps in existing evidence to inform physiotherapy policy and practice. The results will assist research commissioning bodies and inform funding decisions and strategy

The Grizzly, November 21, 2002

Well-known Political Consultant Mark Moskowitz at Ursinus • Greek Organizations Come Together for GPC Activities Fair • Too Big for our Buildings • Eye on Your Future: Internships • \u27Tis the Season to Ignore the Needy? • Do You Care About Political Apathy? • Should a Minor Receive the Death Penalty? • Opinions: Feeling Uninvited in Your Own Home; Smoking or Non? You Decide; 17-Year-Old Could be Tried as Adult • Be a Film Society Member • Howard, Roesch Look to Lead Wrestling to C.C. Championship • On Your Mark...Indoor Track Ready to Go • Dougherty Rockets Off to National Meethttps://digitalcommons.ursinus.edu/grizzlynews/1526/thumbnail.jp

Transcutaneous Auricular Vagus Nerve Stimulation-Paired Rehabilitation for Oromotor Feeding Problems in Newborns: An Open-Label Pilot Study

Neonates born premature or who suffer brain injury at birth often have oral feeding dysfunction and do not meet oral intake requirements needed for discharge. Low oral intake volumes result in extended stays in the hospital (\u3e2 months) and can lead to surgical implant and explant of a gastrostomy tube (G-tube). Prior work suggests pairing vagus nerve stimulation (VNS) with motor activity accelerates functional improvements after stroke, and transcutaneous auricular VNS (taVNS) has emerged as promising noninvasive form of VNS. Pairing taVNS with bottle-feeding rehabilitation may improve oromotor coordination and lead to improved oral intake volumes, ultimately avoiding the need for G-tube placement. We investigated whether taVNS paired with oromotor rehabilitation is tolerable and safe and facilitates motor learning in infants who have failed oral feeding. We enrolled 14 infants [11 premature and 3 hypoxic–ischemic encephalopathy (HIE)] who were slated for G-tube placement in a prospective, open-label study of taVNS-paired rehabilitation to increase feeding volumes. Once-daily taVNS was delivered to the left tragus during bottle feeding for 2 weeks, with optional extension. The primary outcome was attainment of oral feeding volumes and weight gain adequate for discharge without G-tube while also monitoring discomfort and heart rate (HR) as safety outcomes. We observed no adverse events related to stimulation, and stimulation-induced HR reductions were transient and safe and likely confirmed vagal engagement. Eight of 14 participants (57%) achieved adequate feeding volumes for discharge without G-tube (mean treatment length: 16 ± 6 days). We observed significant increases in feeding volume trajectories in responders compared with pre-stimulation (p \u3c 0.05). taVNS-paired feeding rehabilitation appears safe and may improve oral feeding in infants with oromotor dyscoordination, increasing the rate of discharge without G-tube, warranting larger controlled trials