Predicting theater chair absorption from reverberation chamber measurements - comment

The relationship between the measured acoustic absorption coefficient of an array of theater chairs and the ratio of the perimeter length to plan area of the array is considered. It is shown that the linear relationship measured by Bradley in a reverberation chamber and reported in ''Predicting theater chair absorption from reverberation chamber measurements'' [J. Acoust. Soc. Am. 91, 1514-1524 (1992)] is to be expected from simple theory. This means that any nonlinear influence of diffracted energy on the relationship is small. Bradley is also unduly harsh on the usefulness of a chair absorption measurement method involving screens. A sample result is given, showing that this method can predict in-situ theater chair absorption with reasonable accuracy

Measuring auditorium seat absorption

There is a need for a more accurate laboratory measurement method to predict auditorium seat absorption. The traditional method tends to overpredict the absorption of the exposed front and sides of seating blocks. An alternative reverberation chamber method was studied that involves the use of barriers to obtain realistic measurements of front and side absorption. This method was validated by comparing measurements of seats made in a reverberation chamber with in situ absorption data for the same seats, calculated from reverberation time measurements in ten auditoria with and without the seats present. The accuracy of the alternative method was satisfactory in all cases, although a severe lack of diffusion in two of the halls hindered the validation process. It was found that using a frequency-constant edge correction strip to account for side and front absorption could lead to significant errors in auditorium absorption prediction

Understanding student satisfaction and dissatisfaction : an interpretive study in the UK higher education context

This article represents a cross-sectional study of undergraduate students across two north-west university business schools in the UK. A purposefully designed questionnaire was collected from 350 students. The student experience was described in the form of hand-written narratives by first and final year students and had been identified by the respondents themselves as being satisfying or dissatisfying with the areas of teaching and learning and the supporting service environment. The study also assessed whether their experiences were likely to influence their loyalty behaviours with respect to remaining on their chosen course of study; recommending the university; and continuing at a higher level of study. The data were captured and analysed using the qualitative critical incident technique to capture the voice of the student and identified the critical determinants of quality within higher education, i.e. those areas that would influence loyalty behaviour, as being Access; Attentiveness; Availability; and Communication. A number of new determinants of quality have been identified out of the research by three independent judges, namely motivation, reward, social inclusion, usefulness, value for money and fellow student behaviour

Response to pulmonary arterial hypertension drug therapies in patients with pulmonary arterial hypertension and cardiovascular risk factors.

The age at diagnosis of pulmonary arterial hypertension (PAH) and the prevalence of cardiovascular (CV) risk factors are increasing. We sought to determine whether the response to drug therapy was influenced by CV risk factors in PAH patients. We studied consecutive incident PAH patients (n = 146) between January 1, 2008, and July 15, 2011. Patients were divided into two groups: the PAH-No CV group included patients with no CV risk factors (obesity, systemic hypertension, type 2 diabetes mellitus, permanent atrial fibrillation, mitral and/or aortic valve disease, and coronary artery disease), and the PAH-CV group included patients with at least one. The response to PAH treatment was analyzed in all the patients who received PAH drug therapy. The PAH-No CV group included 43 patients, and the PAH-CV group included 69 patients. Patients in the PAH-No CV group were younger than those in the PAH-CV group (P < 0.0001). In the PAH-No CV group, 16 patients (37%) improved on treatment and 27 (63%) did not improve, compared with 11 (16%) and 58 (84%) in the PAH-CV group, respectively (P = 0.027 after adjustment for age). There was no difference in survival at 30 months (P = 0.218). In conclusion, in addition to older age, CV risk factors may predict a reduced response to PAH drug therapy in patients with PAH

Nonequilibrium Forces Between Neutral Atoms Mediated by a Quantum Field

We study all known and as yet unknown forces between two neutral atoms, modeled as three dimensional harmonic oscillators, arising from mutual influences mediated by an electromagnetic field but not from their direct interactions. We allow as dynamical variables the center of mass motion of the atom, its internal degrees of freedom and the quantum field treated relativistically. We adopt the method of nonequilibrium quantum field theory which can provide a first principle, systematic and unified description including the intrinsic field fluctuations and induced dipole fluctuations. The inclusion of self-consistent back-actions makes possible a fully dynamical description of these forces valid for general atom motion. In thermal equilibrium we recover the known forces -- London, van der Waals and Casimir-Polder forces -- between neutral atoms in the long-time limit but also discover the existence of two new types of interatomic forces. The first, a `nonequilibrium force', arises when the field and atoms are not in thermal equilibrium, and the second, which we call an `entanglement force', originates from the correlations of the internal degrees of freedom of entangled atoms.Comment: 16 pages, 2 figure

Total extraperitoneal endoscopic hernioplasty (TEP) versus Lichtenstein hernioplasty: a systematic review by updated traditional and cumulative meta-analysis of randomised-controlled trials.

BACKGROUND-PURPOSE: Totally extraperitoneal (TEP) endoscopic hernioplasty and Lichtenstein hernioplasty are the most commonly used approaches for inguinal hernia repair. However, current evidence on which is the preferred approach is inconclusive. This updated meta-analysis was conducted to track the accumulation of evidence over time. METHODS: Studies were identified by a systematic literature search of the EMBASE, PubMed, Cochrane Library, and Google Scholar databases. Fixed- and random-effects models were used to cumulatively assess the accumulation of evidence over time. RESULTS: The TEP cohort showed significantly higher rates of recurrences and vascular injuries compared to the Lichtenstein cohort; [Peto Odds ratio (OR) = 1.58 (1.22, 2.04), p = 0.005], [Peto OR = 2.49 (1.05, 5.88), p = 0.04], respectively. In contrast, haematoma formation rate, time to return to usual activities, and local paraesthesia were significantly lower in the TEP cohort compared to the Lichtenstein cohort; [Peto OR = 0.26 (0.16, 0.41), p ≤ 0.001], [mean difference = - 6.32 (- 8.17, - 4.48), p ≤ 0.001], [Peto OR = 0.26 (0.17, 0.40), p ≤ 0.001], respectively. CONCLUSIONS: This study, which is based on randomised-controlled trials (RCTs) of high quality, showed significantly higher rates of recurrences and vascular injuries in the TEP cohort than in the Lichtenstein cohort. In contrast, rate of postoperative haematoma formation, local paraesthesia, and time to return to usual activities were significantly lower in the TEP cohort than in the Lichtenstein cohort. Future multicentre RCTs with strict adherence to the standards recommended in the Consolidated Standards of Reporting Trials guidelines will shed further light on the topic

Promoting Behaviour Change in Long term Conditions using a Self-Management Platform

Physical rehabilitation of brain injuries and strokes is a time consuming and costly process. Over the past decade several studies have emerged looking at the use of highly sophisticated technologies, such as robotics and virtual reality to tap into the needs of clinicians and patients. While such technologies can be a valuable tool to facilitate intensive movement practice in a motivating and engaging environment, success of therapy also depends on self-administered therapy beyond hospital stay. With the emergence of low-cost gaming consoles such as the Nintendo Wii, new opportunities arise for home-therapy paradigms centred on social interactions and values, which could reduce the sense of isolation and other depression related complications. In this paper we examine the potential, user acceptance and usability of an unmodified Nintendo Wii gaming console as a low-cost treatment alternative to complement current rehabilitation programmes

Long-distance migration and venting of methane from the base of the hydrate stability zone

\ua9 2023, The Author(s).Marine methane hydrate is an ice-like substance that is stable in sediment around marine continental margins where water depths are greater than ~450–700 m. The release of methane due to melting of hydrates is considered to be a mechanism for past global carbon-cycle perturbations and could exacerbate ongoing anthropogenic climate change. Increases in bottom-water temperature at the landward limit of marine hydrate around continental margins, where vulnerable hydrate exists at or below the seabed, cause methane to vent into the ocean. However, this setting represents only ~3.5% of the global hydrate reservoir. The potential for methane from hydrate in deeper water to reach the atmosphere was considered negligible. Here we use three-dimensional (3D) seismic imagery to show that, on the Mauritanian margin, methane migrated at least 40 km below the base of the hydrate stability zone and vented through 23 pockmarks at the shelf break, probably during warmer Quaternary interglacials. We demonstrate that, under suitable circumstances, some of the 96.5% of methane bound in deeper water distal hydrates can reach the seafloor and vent into the ocean beyond the landward limit of marine hydrate. This reservoir should therefore be considered for estimating climate change-induced methane release during a warming world