Accurate automatic detection of end-diastole from left ventricular pressure using peak curvature

Precise identification of end-diastole (ED), corresponding to the end of diastole and start of systole, is crucial for accurate assessment of cardiac function. The aims of this study were to develop a new algorithm based on peak curvature (kappa(p)) for detecting ED as a "corner" in left ventricular pressure (LVP) signals, and to compare this approach with "gold-standard" ED obtained by manual annotation (ED(man)) and ED calculated with previously described algorithms that use an LVP first-derivative threshold (dP/dt(0) or dP/dt(100)), the peak LVP second-derivative (d(2)P/dt(2)(p)) or ECG R-wave peak (ECG(R)). Using customized software, all algorithms were applied to data derived from 213 large animal studies spanning a wide range of animal ages (fetus to adult), heart rates, inotropic states, and loading conditions. Differences between ED(man) and each algorithm were then compared after defining an acceptance region for the ED detection based on ED(man) interobserver variability. ED detected with kappa(p) was the most accurate (p < 0.001) and least variable (p < 0.001), with 97% of measurements within the acceptance region and difference from ED(man) of (1.5 +/- 4.2) ms. By contrast, ED was often detected early with dP/dt(0) and dP/dt(100) , and late with d(2)P/dt(2)(p) and ECG(R). These results indicate that the peak curvature algorithm using LVP provides accurate and reliable detection of ED.     

High resolution SE-fMRI in humans at 3 and 7 T using a motor task

Object The sensitivity of spin echo (SE) experiments to blood oxygenation level dependent (BOLD) contrast was explored in a study of the same six subjects carried out at 3 and 7 T. Materials and methods Multi-slice, single shot, spin echo, echo planar images with a voxel size of 1 × 1 × 3 mm³ were acquired at three different echo times, during execution of a simple motor task. Results Significant activation was observed at all echo times at both field strengths. Analysis of the fractional signal change as a function of echo time indicated that the change in relaxation rate, ΔR ₂, at 7 T was −0.51 ± 0.14 s ⁻¹, which was 1.3 times larger than the value found at 3 T. Measurements of the percentage signal change on activation and temporal signal to noise ratio showed that there was an increase in the BOLD contrast to noise ratio (CNR) at 7 versus 3 T by a factor of 1.9. There was no overlap of areas of significant activation in the SE data acquired at either field strength with the site of large veins. Conclusion SE-BOLD CNR in motor cortex was found to increase significantly at 7 T compared with 3 T.     

Current Progress and Future Directions for Tau-Based Fluid Biomarker Diagnostics in Alzheimer’s Disease

Despite continued efforts, there remain no disease-modifying drugs approved by the United States Food and Drug Administration (FDA) or European Medicines Agency (EMA) to combat the global epidemic of Alzheimer’s disease. Currently approved medicines are unable to delay disease progression and are limited to symptomatic treatment. It is well established that the pathophysiology of this disease remains clinically silent for decades prior to symptomatic clinical decline. Identifying those at risk of disease progression could allow for effective treatment whilst the therapeutic window remains open for preservation of quality of life. This review aims to evaluate critically the current advances in the interpretation of tau-based biomarkers and their use to provide insights into the onset and progression of Alzheimer’s disease, whilst highlighting important future directions for the field. This review emphasises the need for a more comprehensive analysis and interrogation of tau within biological fluids, to aid in obtaining a disease specific molecular signature for each stage of Alzheimer’s disease. Success in achieving this could provide essential utility for presymptomatic patient selection for clinical trials, monitoring disease progression, and evaluating disease modifying therapies.     

Minor morbidity after day-case surgery

The number of patients and procedures considered suitable for day-case anaesthesia and surgery continues to grow and it is hoped that 50-60% of all operations in the UK will eventually be performed on a day-patient basis. However, minor but troublesome post-operative side effects remain common. We have examined the incidence of the most common causes of minor morbidity, namely headache, nausea/vomiting and pain occurring after a wide variety of day-case surgical and diagnostic procedures. Patient satisfaction with treatment and the impact of day case surgery on the workload of the general practitioner was also assessed. The anaesthetic records of the patients involved were reviewed in an attempt to determine if there was any association between the anaesthetic technique and an adverse outcome. A simple postal questionnaire completed on the morning after surgery was returned by 553 patients (response rate over 87%). More than 50% of respondents complained of some morbidity, with 40% complaining of pain, 19% of headache and 9% of nausea and vomiting. One third self-medicated to modify their symptoms, and in most cases (81%) this was effective. However, 6% of patients called their GP for advice and 2% received a home visit. No patient required readmission. A total of 92 patients (17%) would have preferred treatment as an in-patient. Analysis of the anaesthetic drugs and techniques suggested that the commonly used anti-emetics droperidol and metoclopramide had little effect on the incidence of postoperative nausea and vomiting. Intubation was associated with a significantly higher incidence of minor morbidity although this may be related to surgical factors.     

Simultaneous tridiagonalization of two symmetric matrices

We show how to simultaneously reduce a pair of symmetric matrices to tridiagonal form by congruence transformations. No assumptions are made on the non‐singularity or definiteness of the two matrices. The reduction follows a strategy similar to the one used for the tridiagonalization of a single symmetric matrix via Householder reflectors. Two algorithms are proposed, one using non‐orthogonal rank‐one modifications of the identity matrix and the other, more costly but more stable, using a combination of Householder reflectors and non‐orthogonal rank‐one modifications of the identity matrix with minimal condition numbers. Each of these tridiagonalization processes requires O(n³) arithmetic operations and respects the symmetry of the problem. We illustrate and compare the two algorithms with some numerical experiments. Copyright © 2003 John Wiley & Sons, Ltd.     

Some characteristics of jobs announced in the APA Monitor..

For this study, all 2,914 first-time U.S. job advertisements listed in the 1984 APA Monitor were content analyzed. Findings include data on types of jobs advertised, academic levels, salary, job duration, month of first announcement, and areas of psychology. These data complement employment surveys to provide information about job availability for psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

HBT transmitter and data regenerator arrays for WDM opticalcommunications application

Current research on next generation Wavelength Division Multiplexed (WDM) all optical networks has identified the need for arrays of laser driver circuits and arrays of receivers, clock recovery, and decision circuits. This paper reports on the development of two AlGaAs-GaAs HBT-based circuits: an eight-channel laser driver array and four-channel signal regeneration array including the limiting amplifier, clock recovery, and decision functions one intended for operation at 155 Mb/s. Subcircuits of the clock recovery array have been verified as suitable for use up to 2.488 Gb/s     

Simulation of damage in industrial gas bottles

This paper reports an investigation into the influence of dents on the displacement and stress characteristics of industrial gas bottles subject to internal pressure. The work was used as a basis for the development, fingerprinting and automation of a Gas Bottle Inspection System based upon Electronic Speckle Pattern Interferometry (ESPI). The paper also reports on an investigation into the influence of dents on the performance of gas bottles. It was concluded that the presence of dents currently accepted by the Codes of Practice may detrimentally affect the integrity of the bottle.