Mapping surgical coordinates of the sphenopalatine foramen : surgical navigation study

Aims to identify measurements that may help intra operative localisation of the sphenopalatine foramen. The study used three dimensional surgical navigation software to study radiological anatomy, in order to define the distances and angulations between identifiable bony landmarks and the sphenopalatine foramen. The distance from the anterior nasal spine to the sphenopalatine foramen was 59 mm (+4 mm; inter observer variation = 0.866; intra observer variation = 0.822). The distance from the piriform aperture to the sphenopalatine foramen was 48 mm (+4 mm; inter observer variation = 0.828; intra observer variation = 0.779). The angle of elevation from the nasal floor to the sphenopalatine foramen was 22 degrees (+3 degrees; inter observer variation = 0.441; intra observer variation = 0.499). The sphenopalatine foramen is consistently identifiable on three dimensional, reconstructed computed tomography scans. Repeatable measurements were obtained. The centre point of the foramen lies 59 mm from the anterior nasal spine at 22 degrees elevation above the plane of the hard palate and 48 mm from the piriform aperture. We discuss how these data could be used to facilitate intra operative location of the sphenopalatine foramen in difficult cases

Inter-observer variability for cardiac ultrasound measurements in cats repeated at different time points in early adult life

Abstract A high degree of accuracy is required when using echocardiography to diagnose hypertrophic cardiomyopathy (HCM) in cats, as variation in measurements of 0.5 mm may affect classification of individuals as ‘abnormal’. This study in adult cats examined at different time points inter-observer variability between two Board certified echocardiographers in veterinary cardiology. Twenty-four female European shorthair cats were examined at 12, 18 and 24 months of age by observer 1. Two dimensional (2D) echocardiographic images were collected in conscious cats to measure left ventricular, aortic and left atrial dimensions. Measurements were repeated by observer 2 on stored images, and analyzed for effect of time, observer and time-observer interaction. Based on end-diastolic left ventricular wall thickness, cats were diagnosed as ‘normal’ or 'abnormal'. Linear mixed models (generalized when appropriate) were performed. A significant difference between observers was found for all septal (IVSd) and free wall (LVFWd) thickness measurements and left ventricular internal diameters but not for aortic or left atrial measurements. All measurement coefficients of variation (CV) were 5 mm in cats >6 kg bodyweight) was significantly different between observers for IVSd but not LVFWd. Caution is warranted when diagnosing as ‘abnormal’ or interpreting small changes based on IVSd, due to significant inter-observer differences in this measurement

Spatial Models to Account for Variation in Observer Effort in Bird Atlases

To assess the importance of variation in observer effort between and within bird atlas projects and demonstrate the use of relatively simple conditional autoregressive (CAR) models for analyzing grid-based atlas data with varying effort. Pennsylvania and West Virginia, United States of America. We used varying proportions of randomly selected training data to assess whether variations in observer effort can be accounted for using CAR models and whether such models would still be useful for atlases with incomplete data. We then evaluated whether the application of these models influenced our assessment of distribution change between two atlas projects separated by twenty years (Pennsylvania), and tested our modeling methodology on a state bird atlas with incomplete coverage (West Virginia). Conditional Autoregressive models which included observer effort and landscape covariates were able to make robust predictions of species distributions in cases of sparse data coverage. Further, we found that CAR models without landscape covariates performed favorably. These models also account for variation in observer effort between atlas projects and can have a profound effect on the overall assessment of distribution change. Accounting for variation in observer effort in atlas projects is critically important. CAR models provide a useful modeling framework for accounting for variation in observer effort in bird atlas data because they are relatively simple to apply, and quick to run

A cascaded H-bridge BLDC drive incorporating battery management

A multilevel BLDC drive is proposed using cascaded H-bridges with isolated sources to provide superior output waveforms and reduced current ripple whilst incorporating observer based SoC estimation. Energy management, based on SoC, is incorporated to improve battery performance, reduce variation between cells and to control charge/discharge profiles

Quantum state smoothing: Why the types of observed and unobserved measurements matter

We investigate the estimation technique called quantum state smoothing introduced by Guevara and Wiseman [Phys.~Rev.~Lett.~{\bf 115}, 180407 (2015)], which offers a valid quantum state estimate for a partially monitored system, conditioned on the observed record both prior and posterior to an estimation time. Partial monitoring by an observer implies that there may exist records unobserved by that observer. It was shown that, given only the observed record, the observer can better estimate the underlying true quantum states, by inferring the unobserved record and using quantum state smoothing, rather than the usual quantum filtering approach. However, the improvement in estimation fidelity, originally examined for a resonantly driven qubit coupled to two vacuum baths, was also shown to vary depending on the types of detection used for the qubit's fluorescence. In this work, we analyse this variation in a systematic way for the first time. We first define smoothing power using an average purity recovery and a relative average purity recovery, of smoothing over filtering. Then, we explore the power for various combinations of fluorescence detection for both observed and unobserved channels. We next propose a method to explain the variation of the smoothing power, based on multi-time correlation strength between fluorescence detection records. The method gives a prediction of smoothing power for different combinations, which is remarkably successful in comparison with numerically simulated qubit trajectories.Comment: 24 pages, 5 figure

Effect of delayed acquisition times on Gadolinium-enhanced MRI of the presumably normal canine brain

A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10 minute delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable CSF. Specific ROIs were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement greater than 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve and the trigeminal nerve root. Structures with an active blood-brain-barrier had minimal contrast enhancement (<6%). Enhancing structures had significantly more contrast enhancement at t=1min versus t=10min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Inter-observer agreement was moderate to good in favor of the initial post contrast T1w sequence. The observers found either no difference or poor agreement in identification of the non-vascular structures. Intra-observer agreement was very good with all vascular structures and most non-vascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w post contrast sequence is preferable but not essential should a delayed post contrast T1w sequence be performed

The Response of Test Masses to Gravitational Waves in the Coordinates of a Local Observer

The response of laser interferometers to gravitational waves has been calculated in a number of different ways, particularly in the transverse-traceless and the local Lorentz gauges. At first sight, it would appear that these calculations lead to different results when the separation between the test masses becomes comparable to the wavelength of the gravitational wave. In this paper this discrepancy is resolved. We describe the response of free test masses to plane gravitational waves in the coordinate frame of a local observer and show that it acquires contributions from three different effects: the displacement of the test masses, the apparent change in the photon velocity, and the variation in the clock speed of the local observer, all of which are induced by the gravitational wave. Only when taken together do these three effects represent a quantity which is translationally invariant. This translationally-invariant quantity is identical to the response function calculated in the transverse-traceless gauge. We thus resolve the well-known discrepancy between the two coordinates systems, and show that the results found in the coordinate frame of a local observer are valid for large separation between the masses.Comment: 25 pages, 3 figures, Latex2

Faraday rotation maps of disk galaxies

Faraday rotation is one of the most widely used observables to infer the strength and configuration of the magnetic field in the ionised gas of the Milky Way and nearby spiral galaxies. Here we compute synthetic Faraday rotation maps at $z=0$ for a set of disk galaxies from the Auriga high-resolution cosmological simulations, for different observer positions within and outside the galaxy. We find that the strength of the Faraday rotation of our simulated galaxies for a hypothetic observer at the solar circle is broadly consistent with the Faraday rotation seen for the Milky Way. The same holds for an observer outside the galaxy and the observed signal of the nearby spiral galaxy M51. However, we also find that the structure and angular power spectra of the synthetic all-sky Faraday rotation maps vary strongly with azimuthal position along the solar circle. We argue that this variation is a result of the structure of the magnetic field of the galaxy that is dominated by an azimuthal magnetic field ordered scales of several kpc, but has radial and vertical magnetic field components that are only ordered on scales of 1-2 kpc. Because the magnetic field strength decreases exponentially with height above the disk, the Faraday rotation for an observer at the solar circle is dominated by the local environment. This represents a severe obstacle for attempts to reconstruct the global magnetic field of the Milky Way from Faraday rotation maps alone without including additional observables.Comment: 10 pages, 10 figures, accepted by MNRA

Causality Implies Inflationary Back-Reaction

There is a widespread belief among inflationary cosmologists that a local observer cannot sense super-horizon gravitons. The argument goes that a local observer would subsume super-horizon gravitons into a redefinition of his coordinate system. We show that adopting this view for pure gravity on de Sitter background leads to time variation in the Hubble parameter measured by a local observer. It also leads to a violation of the gravitational field equation $R = 4 \Lambda$ because that equation is obeyed by the full metric, rather than the one which has been cleansed of super-horizon modes.Comment: 20 pages, 2 figures, uses LaTeX2e, version 2 slightly revised for publicatio