Sound Synthesis for Contact-Driven Musical Instruments via Discretisation of Hamilton's Equations

Physical modelling of musical instruments involves studying nonlinear interactions between parts of the instrument. These can pose several difficulties concerning the accuracy and stability of numerical algorithms. In particular, when the underlying forces are non-analytic functions of the phase-space variables, a stability proof can only be obtained in limited cases. An approach has been recently presented by the authors, leading to unconditionally stable simulations for lumped collision models. In that study, discretisation of Hamilton’s equations instead of the usual Newton’s equation of motion yields a numerical scheme that can be proven to be energy conserving. In this paper, the above approach is extended to collisions of distributed objects. Namely, the interaction of an ideal string with a flat barrier is considered. The problem is formulated within the Hamiltonian framework and subsequently discretised. The resulting nonlinearmatrix equation can be shown to possess a unique solution, that enables the update of the algorithm. Energy conservation and thus numerical stability follows in a way similar to the lumped collision model. The existence of an analytic description of this interaction allows the validation of the model’s accuracy. The proposed methodology can be used in sound synthesis applications involving musical instruments where collisions occur either in a confined (e.g. hammer-string interaction, mallet impact) or in a distributed region (e.g. string-bridge or reed-mouthpiece interaction).

A methodological review of the Short Form Health Survey 36 (SF-36) and its derivatives among breast cancer survivors

Purpose: A systematic review of the validity, reliability and sensitivity of the Short Form (SF) health survey measures among breast cancer survivors.
Methods: We searched a number of databases for peer-reviewed papers. The methodological quality of the papers was assessed using the COnsenus-based Standards for the selection of health Measurement INstruments (COSMIN).
Results: The review identified seven papers that assessed the psychometric properties of the SF-36 (n = 5), partial SF-36 (n = 1) and SF-12 (n = 1) among breast cancer survivors. Internal consistency scores for the SF measures ranged from acceptable to good across a range of language and ethnic sub-groups. The SF-36 demonstrated good convergent validity with respective subscales of the Functional Assessment of Cancer Treatment—General scale and two lymphedema-specific measures. Divergent validity between the SF-36 and Lymph-ICF was modest. The SF-36 demonstrated good factor structure in the total breast cancer survivor study samples. However, the factor structure appeared to differ between specific language and ethnic sub-groups. The SF-36 discriminated between survivors who reported or did not report symptoms on the Breast Cancer Prevention Trial Symptom Checklist and SF-36 physical sub-scales, but not mental sub-scales, discriminated between survivors with or without lymphedema. Methodological quality scores varied between and within papers.
Conclusion: Short Form measures appear to provide a reliable and valid indication of general health status among breast cancer survivors though the limited data suggests that particular caution is required when interpreting scores provided by non-English language groups. Further research is required to test the sensitivity or responsiveness of the measure.

Arbuscular mycorrhizal fungal communities are phylogenetically clustered at small scales

Next-generation sequencing technologies with markers covering the full Glomeromycota phylum were used to uncover phylogenetic community structure of arbuscular mycorrhizal fungi (AMF) associated with Festuca brevipila. The study system was a semi-arid grassland with high plant diversity and a steep environmental gradient in pH, C, N, P and soil water content. The AMF community in roots and rhizosphere soil were analyzed separately and consisted of 74 distinct operational taxonomic units (OTUs) in total. Community-level variance partitioning showed that the role of environmental factors in determining AM species composition was marginal when controlling for spatial autocorrelation at multiple scales. Instead, phylogenetic distance and spatial distance were major correlates of AMF communities: OTUs that were more closely related (and which therefore may have similar traits) were more likely to co-occur. This pattern was insensitive to phylogenetic sampling breadth. Given the minor effects of the environment, we propose that at small scales closely related AMF positively associate through biotic factors such as plant-AMF filtering and interactions within the soil biota.

In and out of home care decisions: The influence of confirmation bias in developing decision supportive reasoning

The aims of this study were to identify the themes Social Workers regard as important in supporting decisions to remove children from, or return them to, the care of their parents. To further elicit underlying hypotheses that are discernible in interpretation of evidence. A case study, comprising a two-part vignette with a questionnaire, recorded demographic information, child welfare attitudes and risk assessments, using scales derived from standardised instruments, was completed by 202 Social Workers in Northern Ireland. There were two manipulated variables, mother’s attitude to removal and child’s attitude to reunification2 years later. In this paper we use data derived from respondents’ qualitative comments explaining their reasoning for in and out of home care decisions. Some 60.9% of respondent’s chose the parental care option at part one, with 94% choosing to have the child remain in foster care at part two. The manipulated variables were found to have no significant statistical effect. However, three underlying hypotheses were found to underpin decisions; (a)child rescue, (b) kinship defence and (c) a hedged position on calculation of risk subject to further assessment. Reasoning strategies utilised by social workers to support their decision making suggest that they tend to selectively interpret information either positively or negatively to support pre-existing underlying hypotheses. This finding is in keeping with the literature on ‘confirmation bias.’ The research further draws attention to the need to incorporate open questions in quantitative studies, to help guard against surface reading of data, which often does not ‘speak for itself.’

Scales and Hierarchies: A Cross-Disciplinary Perspective

The volume advances our understanding of the role of scales and hierarchies across the linguistic sciences. Although scales and hierarchies are widely assumed to play a role in the modelling of linguistic phenomena, their status remains controversial, and it is these controversies that the present volume tackles head-on.

Plant community assembly at small scales: spatial versus environmental factors in a central European grassland

Dispersal limitation and environmental conditions are crucial drivers of plant species distribution and establishment. As these factors operate at different spatial scales, we asked: Do the environmental factors known to determine community assembly at broad scales operate at fine scales (few meters)? How much do these factors account for community variation at fine scales? In which way do biotic and abiotic interactions drive changes in species composition? We surveyed the plant community within a dry grassland along a very steep gradient of soil characteristics like pH and nutrients. We used a spatially explicit sampling design, based on three replicated macroplots of 15x15, 12x12 and 12x12 meters in extent. Soil samples were taken to quantify several soil properties (carbon, nitrogen, plant available phosphorus, pH, water content and dehydrogenase activity as a proxy for overall microbial activity). We performed variance partitioning to assess the effect of these variables on plant composition and statistically controlled for spatial autocorrelation via eigenvector mapping. We also applied null model analysis to test for non-random patterns in species co-occurrence using randomization schemes that account for patterns expected under species interactions. At a fine spatial scale, environmental factors explained 18% of variation when controlling for spatial autocorrelation in the distribution of plant species, whereas purely spatial processes accounted for 14% variation. Null model analysis showed that species spatially segregated in a non-random way and these spatial patterns could be due to a combination of environmental filtering and biotic interactions. Our grassland study suggests that environmental factors found to be directly relevant in broad scale studies are present also at small scales, but are supplemented by spatial processes and more direct interactions like competition.

How the mollusc got its scales: Convergent evolution of the molluscan scleritome

Radiation of dramatically disparate forms among the phylum Mollusca remains a key question in metazoan evolution, and requires careful evaluation of homology of hard parts throughout the deep fossil record. Enigmatic early Cambrian taxa such as Halkieria and Wiwaxia (in the clade Halwaxiida) have been proposed to represent stem-group aculiferan molluscs (Caudofoveata+Solenogastres+Polyplacophora), as complex scleritomes were considered to be unique to aculiferans among extant molluscs. The 'scaly-foot gastropod' (Neomphalina: Peltospiridae) from hydrothermal vents of the Indian Ocean, however, also carries dermal sclerites and thus challenges this inferred homology. Despite superficial similarities to various mollusc sclerites, the scaly-foot gastropod sclerites are secreted in layers covering outpockets of epithelium and are largely proteinaceous, while chiton (Polyplacophora: Chitonida) sclerites are secreted to fill an invaginated cuticular chamber and are largely calcareous. Marked differences in the underlying epithelium of the scaly-foot gastropod sclerites and operculum suggest that the sclerites do not originate from multiplication of the operculum. This convergence in different classes highlights the ability of molluscs to adapt mineralized dermal structures, as supported by the extensive early fossil record of molluscs with scleritomes. Sclerites of halwaxiids are morphologically variable, undermining the assumed affinity of specific taxa with chitons, or the larger putative clade Aculifera. Comparisons with independently derived similar structures in living molluscs are essential for determining homology among fossils and their position with respect to the enigmatic evolution of molluscan shell forms in deep time.

Tools for Assessing Outcomes in Studies of Chronic Cough: CHEST Guideline and Expert Panel Report

BACKGROUND: Since the publication of the 2006 American College of Chest Physicians (CHEST) cough guidelines, a variety of tools has been developed or further refined for assessing cough. The purpose of the present committee was to evaluate instruments used by investigators performing clinical research on chronic cough. The specific aims were to (1) assess the performance of tools designed to measure cough frequency, severity, and impact in adults, adolescents, and children with chronic cough and (2) make recommendations or suggestions related to these findings.

METHODS: By following the CHEST methodologic guidelines, the CHEST Expert Cough Panel based its recommendations and suggestions on a recently published comparative effectiveness review commissioned by the US Agency for Healthcare Research and Quality, a corresponding summary published in CHEST, and an updated systematic review through November 2013. Recommendations or suggestions based on these data were discussed, graded, and voted on during a meeting of the Expert Cough Panel.

RESULTS: We recommend for adults, adolescents (≥ 14 years of age), and children complaining of chronic cough that validated and reliable health-related quality-of-life (QoL) questionnaires be used as the measurement of choice to assess the impact of cough, such as the Leicester Cough Questionnaire and the Cough-Specific Quality-of-Life Questionnaire in adult and adolescent patients and the Parent Cough-Specific Quality of Life Questionnaire in children. We recommend acoustic cough counting to assess cough frequency but not cough severity. Limited data exist regarding the performance of visual analog scales, numeric rating scales, and tussigenic challenges.

CONCLUSIONS: Validated and reliable cough-specific health-related QoL questionnaires are recommended as the measurement of choice to assess the impact of cough on patients. How they compare is yet to be determined. When used, the reporting of cough severity by visual analog or numeric rating scales should be standardized. Previously validated QoL questionnaires or other cough assessments should not be modified unless the new version has been shown to be reliable and valid. Finally, in research settings, tussigenic challenges play a role in understanding mechanisms of cough.

Psychometric evaluation of the Student Authorship Questionnaire: a confirmatory factor analysis approach

This research provides new insights into the measurement of students’ authorial identity and its potential for minimising the incidence of unintentional plagiarism by providing evidence about the psychometric properties of the Student Authorship Questionnaire (SAQ). Exploratory and confirmatory factor analyses (EFA and CFA) are employed to investigate the measurement properties of the scales which comprise the SAQ using data collected from accounting students. The results provide limited psychometric support in favour of the factorial structure of the SAQ and raise a number of questions regarding the instrument’s robustness and generalisability across disciplines. An alternative model derived from the EFA outperforms the SAQ model with regard to its psychometric properties. Explanations for these findings are proffered and avenues for future research suggested.

Current and Turbulence Measurement with Collocated ADP and Turbulence Profiler Data

This paper presents a current and turbulence measurement campaign conducted at a test site in an energetic tidal channel known as Strangford Narrows, Northern Ireland. The data was collected as part of the MaRINET project funded by the EU under their FP7 framework. It was a collaborative effort between Queen’s University Belfast, SCHOTTEL and Fraunhofer IWES. The site is highly turbulent with a strong shear flow. Longer term measurements of the flow regime were made using a bottom mounted Acoustic Doppler Profiler (ADP). During a specific turbulence measurement campaign, two collocated in- struments were used to measure incoming flow characteristics: an ADP (Aquadopp, Nortek) and a turbulence profiler (MicroRider, Rockland Scientific International). The instruments recorded the same incoming flow, so that direct comparisons between the data can be made. In this study the methodology adopted to deploy the instruments is presented. The resulting turbulence measurements using the different types of instrumentation are compared and the usefulness of each instrument for the relevant range of applications is discussed. The paper shows the ranges of the frequency spectra obtained using the different instruments, with the combined measurements providing insight into the structure of the turbulence across a wide range of scales.