Non-intrusive real-time breathing pattern detection and classification for automatic abdominal functional electrical stimulation

Abdominal Functional Electrical Stimulation (AFES) has been shown to improve the respiratory function of people with tetraplegia. The effectiveness of AFES can be enhanced by using different stimulation parameters for quiet breathing and coughing. The signal from a spirometer, coupled with a facemask, has previously been used to differentiate between these breath types. In this study, the suitability of less intrusive sensors was investigated with able-bodied volunteers. Signals from two respiratory effort belts, positioned around the chest and the abdomen, were used with a Support Vector Machine (SVM) algorithm, trained on a participant by participant basis, to classify, in real-time, respiratory activity as either quiet breathing or coughing. This was compared with the classification accuracy achieved using a spirometer signal and an SVM. The signal from the belt positioned around the chest provided an acceptable classification performance compared to the signal from a spirometer (mean cough (<i>c</i>) and quiet breath (<i>q</i>) sensitivity (<i>Se</i>) of <i>Se<sup>c</sup></i> = 92.9% and <i>Se<sup>q</sup></i> = 96.1% vs. <i>Se<sup>c</sup></i> = 90.7% and <i>Se<sup>q</sup></i> = 98.9%). The abdominal belt and a combination of both belt signals resulted in lower classification accuracy. We suggest that this novel SVM classification algorithm, combined with a respiratory effort belt, could be incorporated into an automatic AFES device, designed to improve the respiratory function of the tetraplegic population

PRECISE - pregabalin in addition to usual care for sciatica: Study protocol for a randomised controlled trial

Background: Sciatica is a type of neuropathic pain that is characterised by pain radiating into the leg. It is often accompanied by low back pain and neurological deficits in the lower limb. While this condition may cause significant suffering for the individual, the lack of evidence supporting effective treatments for sciatica makes clinical management difficult. Our objectives are to determine the efficacy of pregabalin on reducing leg pain intensity and its cost-effectiveness in patients with sciatica.Methods/Design: PRECISE is a prospectively registered, double-blind, randomised placebo-controlled trial of pregabalin compared to placebo, in addition to usual care. Inclusion criteria include moderate to severe leg pain below the knee with evidence of nerve root/spinal nerve involvement. Participants will be randomised to receive either pregabalin with usual care (n = 102) or placebo with usual care (n = 102) for 8 weeks. The medicine dosage will be titrated up to the participant's optimal dose, to a maximum 600 mg per day. Follow up consultations will monitor individual progress, tolerability and adverse events. Usual care, if deemed appropriate by the study doctor, may include a referral for physical or manual therapy and/or prescription of analgesic medication. Participants, doctors and researchers collecting participant data will be blinded to treatment allocation. Participants will be assessed at baseline and at weeks 2, 4, 8, 12, 26 and 52. The primary outcome will determine the efficacy of pregabalin in reducing leg pain intensity. Secondary outcomes will include back pain intensity, disability and quality of life. Data analysis will be blinded and by intention-to-treat. A parallel economic evaluation will be conducted from health sector and societal perspectives.Discussion: This study will establish the efficacy of pregabalin in reducing leg pain intensity in patients with sciatica and provide important information regarding the effect of pregabalin treatment on disability and quality of life. The impact of this research may allow the future development of a cost-effective conservative treatment strategy for patients with sciatica.Trial registration: ClinicalTrial.gov, ACTRN 12613000530729

PRECISE - pregabalin in addition to usual care: Statistical analysis plan

Background: Sciatica is a severe, disabling condition that lacks high quality evidence for effective treatment strategies. This a priori statistical analysis plan describes the methodology of analysis for the PRECISE study. Methods/design: PRECISE is a prospectively registered, double blind, randomised placebo controlled trial of pregabalin compared to placebo, in addition to usual care in patients with sciatica. The aim of this study is to determine the efficacy and cost-effectiveness of pregabalin in reducing leg pain intensity (primary outcome). Secondary outcomes include disability (key secondary), back pain intensity, quality of life, participants' perceived global effect, work absenteeism and health utilisation. Information about medication usage and tolerability are also collected. Outcomes are collected over one year (weeks 2, 4, 8, 12, 26 and 52). Double data entry will be conducted for primary and key secondary outcomes. Other outcomes will be checked using a risk-based approach. Analyses will be consistent with the intention-to-treat principle. Statistical tests will be two-tailed with a p value <0.05 considered significant. Group allocation will remain masked until analyses and interpretation are finalised. Repeated-measure linear mixed models will assess the effect of treatment (pregabalin versus placebo) on primary and secondary outcomes at all time points. Fixed effects will include group allocation, visit as a categorical variable and the interaction between group and visit. Covariates will include baseline leg pain and symptom duration, with an interaction term between baseline leg pain and visit. Pairwise differences between groups will be tested at weeks 8 and 52. The number of serious adverse events and adverse events will be reported, and the proportion of patients per group who have at least one event will be compared using Fisher's exact test. An economic evaluation will be conducted if there is a treatment effect on the primary outcome at week 8. A subgroup analysis will assess whether presenting features of neuropathic pain at baseline modify the treatment effect of leg pain at week 8. Discussion: This statistical analysis plan provides detailed methodology for the analysis of the PRECISE study, which aims to deliver much needed evidence about effective and affordable management of sciatica. Trial registration: Australian and New Zealand Clinical Trials Registry ( ACTRN12613000530729. Registered 13 May 2013

Variational and Geometric Structures of Discrete Dirac Mechanics

In this paper, we develop the theoretical foundations of discrete Dirac mechanics, that is, discrete mechanics of degenerate Lagrangian/Hamiltonian systems with constraints. We first construct discrete analogues of Tulczyjew's triple and induced Dirac structures by considering the geometry of symplectic maps and their associated generating functions. We demonstrate that this framework provides a means of deriving discrete Lagrange-Dirac and nonholonomic Hamiltonian systems. In particular, this yields nonholonomic Lagrangian and Hamiltonian integrators. We also introduce discrete Lagrange-d'Alembert-Pontryagin and Hamilton-d'Alembert variational principles, which provide an alternative derivation of the same set of integration algorithms. The paper provides a unified treatment of discrete Lagrangian and Hamiltonian mechanics in the more general setting of discrete Dirac mechanics, as well as a generalization of symplectic and Poisson integrators to the broader category of Dirac integrators.Comment: 26 pages; published online in Foundations of Computational Mathematics (2011

Suitability of linear quadrupole ion traps for large Coulomb crystals

Growing and studying large Coulomb crystals, composed of tens to hundreds of thousands of ions, in linear quadrupole ion traps presents new challenges for trap implementation. We consider several trap designs, first comparing the total driven micromotion amplitude as a function of location within the trapping volume; total micromotion is an important point of comparison since it can limit crystal size by transfer of radiofrequency drive energy into thermal energy. We also compare the axial component of micromotion, which leads to first-order Doppler shifts along the preferred spectroscopy axis in precision measurements on large Coulomb crystals. Finally, we compare trapping potential anharmonicity, which can induce nonlinear resonance heating by shifting normal mode frequencies onto resonance as a crystal grows. We apply a non-deforming crystal approximation for simple calculation of these anharmonicity-induced shifts, allowing a straightforward estimation of when crystal growth can lead to excitation of different nonlinear heating resonances. In the axial micromotion and anharmonicity points of comparison, we find significant differences between the compared trap designs, with an original rotated-endcap trap performing slightly better than the conventional in-line endcap trap