Novel Device for Measuring Lung Function using Oscillometry

The forced oscillation technique (FOT) is a non-invasive means of measuring lung mechanics. Broad-band oscillations in flow are delivered to the lungs while the resultant pressure oscillations are recorded. These signals are processed to yield the input impedance of the respiratory system (Zrs), which encapsulates the mechanical properties of the lung over the frequency range spanned by the oscillations. Clinically, can be used to assess pulmonary pathologies such as asthma and COPD. Standard methods of performing FOT are limited to the non-ambulatory clinical setting. Production of a light-weight device that operates without an external power source would allow real-time measurements of in a wide variety of more natural settings. Breath-driven oscillators, such as the Smith’s Medical Acapella and D R Burton vPEP, are currently used clinically to help cystic fibrosis patients clear mucus from their lungs by generating pressure oscillations that travel into the airways. We hypothesized that these oscillations could be used to determine . We performed FOT on healthy individuals without history of lung disease using a calibrated piston oscillator (Flexivent) to determine reference between 1 and 20 Hz. We then measured airway pressure and flow using the same sensors but with the oscillations produced by the Acapella and vPEP during tidal breathing. Respiratory resistance (Rrs), elastance (Ers) and Inertance (Irs) were determined by fitting the single-compartment model of the respiratory system to the time-domain signals from all three measurement devices. Correlation coefficients, Bland-Altman plots, and coefficients of variation were used to compare the results obtained with the three devices. We found bias values of 0.633857 [0.214382378, 1.053331908] cmH2O.s.L-1, 0.041333 [-0.38432604, 0.46699271] cmH2O.s.L-1 for comparing the Flexivent against the Acapella and vPEP, respectively. Coefficients of variation of 9.003%, 9.855%, and 9.643% were obtained for the Flexivent, Acapella, and vPEP, respectively. These results demonstrate that breath-driven oscillators are promising alternatives to conventional powered oscillators for the measurement of

Tort Law - Social Host Liability - Non-Liability of Minors

The Supreme Court of Pennsylvania held that there is no liability when a minor furnishes alcohol to another minor who is subsequently injured due to intoxication. Kapres v. Heller, 640 A.2d 888 (Pa. 1994)

Resistive Magnetohydrodynamic Equilibria in a Torus

It was recently demonstrated that static, resistive, magnetohydrodynamic equilibria, in the presence of spatially-uniform electrical conductivity, do not exist in a torus under a standard set of assumed symmetries and boundary conditions. The difficulty, which goes away in the ``periodic straight cylinder approximation,'' is associated with the necessarily non-vanishing character of the curl of the Lorentz force, j x B. Here, we ask if there exists a spatial profile of electrical conductivity that permits the existence of zero-flow, axisymmetric r esistive equilibria in a torus, and answer the question in the affirmative. However, the physical properties of the conductivity profile are unusual (the conductivity cannot be constant on a magnetic surface, for example) and whether such equilibria are to be considered physically possible remains an open question.Comment: 17 pages, 4 figure

An Optimal Dimensionality Multi-shell Sampling Scheme with Accurate and Efficient Transforms for Diffusion MRI

This paper proposes a multi-shell sampling scheme and corresponding transforms for the accurate reconstruction of the diffusion signal in diffusion MRI by expansion in the spherical polar Fourier (SPF) basis. The sampling scheme uses an optimal number of samples, equal to the degrees of freedom of the band-limited diffusion signal in the SPF domain, and allows for computationally efficient reconstruction. We use synthetic data sets to demonstrate that the proposed scheme allows for greater reconstruction accuracy of the diffusion signal than the multi-shell sampling schemes obtained using the generalised electrostatic energy minimisation (gEEM) method used in the Human Connectome Project. We also demonstrate that the proposed sampling scheme allows for increased angular discrimination and improved rotational invariance of reconstruction accuracy than the gEEM schemes.Comment: 4 pages, 4 figures presented at ISBI 201

Toroidal Vortices in Resistive Magnetohydrodynamic Equilibria

Resistive steady states in toroidal magnetohydrodynamics (MHD), where Ohm's law must be taken into account, differ considerably from ideal ones. Only for special (and probably unphysical) resistivity profiles can the Lorentz force, in the static force-balance equation, be expressed as the gradient of a scalar and thus cancel the gradient of a scalar pressure. In general, the Lorentz force has a curl directed so as to generate toroidal vorticity. Here, we calculate, for a collisional, highly viscous magnetofluid, the flows that are required for an axisymmetric toroidal steady state, assuming uniform scalar resistivity and viscosity. The flows originate from paired toroidal vortices (in what might be called a ``double smoke ring'' configuration), and are thought likely to be ubiquitous in the interior of toroidally driven magnetofluids of this type. The existence of such vortices is conjectured to characterize magnetofluids beyond the high-viscosity limit in which they are readily calculable.Comment: 17 pages, 4 figure