Energy conserving schemes for the simulation of musical instrument contact dynamics

Collisions are an innate part of the function of many musical instruments. Due to the nonlinear nature of contact forces, special care has to be taken in the construction of numerical schemes for simulation and sound synthesis. Finite difference schemes and other time-stepping algorithms used for musical instrument modelling purposes are normally arrived at by discretising a Newtonian description of the system. However because impact forces are non-analytic functions of the phase space variables, algorithm stability can rarely be established this way. This paper presents a systematic approach to deriving energy conserving schemes for frictionless impact modelling. The proposed numerical formulations follow from discretising Hamilton׳s equations of motion, generally leading to an implicit system of nonlinear equations that can be solved with Newton׳s method. The approach is first outlined for point mass collisions and then extended to distributed settings, such as vibrating strings and beams colliding with rigid obstacles. Stability and other relevant properties of the proposed approach are discussed and further demonstrated with simulation examples. The methodology is exemplified through a case study on tanpura string vibration, with the results confirming the main findings of previous studies on the role of the bridge in sound generation with this type of string instrument.

Extended contact through cross-group romantic relationships

Cross-group romantic relationships are an extremely intimate and often maligned form of intergroup contact. Yet, according to intergroup contact theory, these relationships have the potential to improve the intergroup attitudes of others via extended contact. This study combines the interpersonal and intergroup literatures to examine the outcomes associated with knowing a partner in a cross-group romantic relationship. Results suggest that cross-group romantic partners encounter greater disapproval toward their relationships than same-group partners and, as a result, their relationships are perceived more negatively. Nevertheless, extended contact with cross-group partners, controlling for participants' cross-group friendships and romantic relationships, predicts more positive attitudes toward cross-group dating and positive intergroup attitudes in general, mediated by perceived ingroup norms toward cross-group relationships.

Applying imagined contact to improve physiological responses in anticipation of intergroup interactions and the perceived quality of these interactions

This experiment (N 5 49) is the first to show that imagined contact can bufferanticipatory physiological responses to future interactions, and improve the qualityof these interactions. Participants imagined a positive interaction with a person withschizophrenia, or in a control condition, a person who did not have schizophrenia. They then interacted with a confederate whom they believed had schizophrenia. Participants in the imagined contact condition reported more positive attitudes andless avoidance of people with schizophrenia, displayed smaller anticipatory physio-logical responses, specifically smaller changes in interbeat interval and skin conduct-ance responses, and had a more positive interaction according to the confederate.These findings support applying imagined contact to improve interactions with people with severe mental illnesses.

Supervised walking in comparison with fitness training for chronic back pain in physiotherapy: results of the SWIFT single-blinded randomized controlled trial (ISRCTN17592092)

Effectiveness of brief/minimal contact self-activation interventions that encourage participation in physical activity (PA) for chronic low back pain (CLBP >12 weeks) is unproven. The primary objective of this assessor-blinded randomized controlled trial was to investigate the difference between an individualized walking programme (WP), group exercise class (EC), and usual physiotherapy (UP, control) in mean change in functional disability at 6 months. A sample of 246 participants with CLBP aged 18 to 65 years (79 men and 167 women; mean age ± SD: 45.4 ± 11.4 years) were recruited from 5 outpatient physiotherapy departments in Dublin, Ireland. Consenting participants completed self-report measures of functional disability, pain, quality of life, psychosocial beliefs, and PA were randomly allocated to the WP (n = 82), EC (n = 83), or UP (n = 81) and followed up at 3 (81%; n = 200), 6 (80.1%; n = 197), and 12 months (76.4%; n = 188). Cost diaries were completed at all follow-ups. An intention-to-treat analysis using a mixed between-within repeated-measures analysis of covariance found significant improvements over time on the Oswestry Disability Index (Primary Outcome), the Numerical Rating Scale, Fear Avoidance-PA scale, and the EuroQol EQ-5D-3L Weighted Health Index (P < 0.05), but no significant between-group differences and small between-group effect sizes (WP: mean difference at 6 months, 6.89 Oswestry Disability Index points, 95% confidence interval [CI] -3.64 to -10.15; EC: -5.91, CI: -2.68 to -9.15; UP: -5.09, CI: -1.93 to -8.24). The WP had the lowest mean costs and the highest level of adherence. Supervised walking provides an effective alternative to current forms of CLBP management.

The Landscape of Differences: Contact and Segregation in the Everyday Encounters

The article examines everyday life in Northern Ireland’s segregated communities and focus on a neglected empirical dimension of ethnic and social segregation developed within the socio-spatial relations between people and their built environment. It shows how the everyday urban encounters are reproduced through negotiating differences and the ways in which living in divided communities lead to social inequality and imbalanced use of space. The article employed qualitative research methods with individuals and community groups from the Fountain estate, a small Protestant enclave in Derry/Londonderry. Their stories were replete with cases of injustice and insights into the daily struggles that have generally occurred within theories of contact and social segregation as a whole. In fact, people in the Fountain presented their own intertextual references on what was more significant for them as a matter of routine survival and belonging, which allowed them to be more constructive about themselves. While segregation has persisted for multiple decades; time is believed to be the factor most likely to change it, as it is hoped that the younger generation will provide lasting change to Northern Ireland and eventual peace between currently segregated communities.

On Irish sticklebacks: morphological diversification in a secondary contact zone

Question: How parallel is adaptive evolution when it occurs from different genetic backgrounds?
Background: Divergent evolutionary lineages of several post-glacial fish species including the threespine stickleback are found together in Ireland.
Goals: To investigate the morphological diversity of stickleback populations in Ireland and assess whether morphology evolved in parallel between evolutionary lineages.
Methods: We sampled stickleback from lake, river, and coastal habitats across Ireland. Microsatellite and mitochondrial DNA data revealed evolutionary history. Geometric morphometrics and linear trait measurements characterized morphology. We used a multivariate approach to quantify parallel and non-parallel divergence within and between lineages.
Results: Repeated evolution of similar morphologies in similar habitats occurred across Ireland, concordant with patterns observed elsewhere in the stickleback distribution. A strong pattern of habitat-specific morphology existed even among divergent lineages. Furthermore, a strong signal of shared morphological divergence occurred along a marine–freshwater axis. Evidently, deterministic natural selection played a more important role in driving freshwater adaptation than independent evolutionary history.

Wahrnehmungs- und Betätigungsformen des Vertrauens im deutsch-französischen Vergleich:Representations, Forms and practice of Trust in French and German comparison

Thomas Würtenberger, Dieter K. Tscheulin, Jean-Claude Usunier, Dominique Jeannerod, Eric Davoine (Hrsg.):
Wahrnehmungs- und Betätigungsformen des Vertrauens im deutsch-französischen Vergleich
Berlin, Berlin GmbH, 2002

Where the Lake Meets the Sea: Strong Reproductive Isolation Is Associated with Adaptive Divergence between Lake Resident and Anadromous Three-Spined Sticklebacks

Contact zones between divergent forms of the same species are often characterised by high levels of phenotypic diversity over small geographic distances. What processes are involved in generating such high phenotypic diversity? One possibility is that introgression and recombination between divergent forms in contact zones results in greater phenotypic and genetic polymorphism. Alternatively, strong reproductive isolation between forms may maintain distinct phenotypes, preventing homogenisation by gene flow. Contact zones between divergent freshwater-resident and anadromous stickleback (Gasterosteus aculeatus L.) forms are numerous and common throughout the species distribution, offering an opportunity to examine these contrasting hypotheses in greater detail. This study reports on an interesting new contact zone located in a tidally influenced lake catchment in western Ireland, characterised by high polymorphism for lateral plate phenotypes. Using neutral and QTL-linked microsatellite markers, we tested whether the high diversity observed in this contact zone arose as a result of introgression or reproductive isolation between divergent forms: we found strong support for the latter hypothesis. Three phenotypic and genetic clusters were identified, consistent with two divergent resident forms and a distinct anadromous completely plated population that migrates in and out of the system. Given the strong neutral differentiation detected between all three morphotypes (mean FST = 0.12), we hypothesised that divergent selection between forms maintains reproductive isolation. We found a correlation between neutral genetic and adaptive genetic differentiation that support this. While strong associations between QTL linked markers and phenotypes were also observed in this wild population, our results support the suggestion that such associations may be more complex in some Atlantic populations compared to those in the Pacific. These findings provide an important foundation for future work investigating the dynamics of gene flow and adaptive divergence in this newly discovered stickleback contact zone.