170 research outputs found
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Enhanced Wave-Based Modelling of Musical Strings. Part 2: Bowed Strings
An enhanced model of a bowed string is developed, incorporating several new features: realistic damping, detailed coupling of body modes to both polarisations of string motion, coupling to transverse and longitudinal bow-hair motion, and coupling to vibration of the bow stick. The influence of these factors is then explored via simulations of the Schelleng diagram, to reveal trends of behaviour. The biggest influence on behaviour is found to come from the choice of model to describe the friction force at the bow, but the other factors all produce effects that may be of musical significance under certain circumstances
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Enhanced Wave-Based Modelling of Musical Strings. Part 1: Plucked Strings
A physically-accurate time-domain model for a plucked musical string is developed. The model incorporates detailed dispersion and damping behaviour measured from cello strings, and a detailed description of body response measured from a cello body. The resulting model is validated against measured pizzicato notes using the same strings and cello, and good accuracy is demonstrated. The model is developed in a form that makes extension to the case of a bowed string very straightforward
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On Minimum Bow Force for Bowed Strings
A famous theoretical prediction of the minimum bow force to maintain Helmholtz motion of a bowed string is re-examined to take account of effects associated with resonances of the instrument body. Starting from a more robust assumption of an ideal stick-slip velocity waveform at the bowing point rather than a perfect sawtoothshaped excitation force at the bridge, the analysis predicts that the minimum bow force, and the force waveform exciting the instrument bridge, can depend in a complicated way on the position of the bow on the string. Also, the frequency of "maximum wolfiness" of an instrument like a cello is predicted to shift away from that of the strong body resonance causing a wolf note. Simulations are used to evaluate the new formulation. For the simple case in which the string vibrates only in a single polarisation, the results are accurately confirmed. However, simulation also reveals that string vibration in the second polarisation can change the detailed response. Further simulations are used to investigate the influence on minimum bow force of some physical details of the model, especially torsional string motion and the presence of sympathetic strings
What determines auditory similarity? The effect of stimulus group and methodology.
Two experiments on the internal representation of auditory stimuli compared the pairwise and grouping methodologies as means of deriving similarity judgements. A total of 45 undergraduate students participated in each experiment, judging the similarity of short auditory stimuli, using one of the methodologies. The experiments support and extend Bonebright's (1996) findings, using a further 60 stimuli. Results from both methodologies highlight the importance of category information and acoustic features, such as root mean square (RMS) power and pitch, in similarity judgements. Results showed that the grouping task is a viable alternative to the pairwise task with N > 20 sounds whilst highlighting subtle differences, such as cluster tightness, between the different task results. The grouping task is more likely to yield category information as underlying similarity judgements
HGF Mediates the Anti-inflammatory Effects of PRP on Injured Tendons
Platelet-rich plasma (PRP) containing hepatocyte growth factor (HGF) and other growth factors are widely used in orthopaedic/sports medicine to repair injured tendons. While PRP treatment is reported to decrease pain in patients with tendon injury, the mechanism of this effect is not clear. Tendon pain is often associated with tendon inflammation, and HGF is known to protect tissues from inflammatory damages. Therefore, we hypothesized that HGF in PRP causes the anti-inflammatory effects. To test this hypothesis, we performed in vitro experiments on rabbit tendon cells and in vivo experiments on a mouse Achilles tendon injury model. We found that addition of PRP or HGF decreased gene expression of COX-1, COX-2, and mPGES-1, induced by the treatment of tendon cells in vitro with IL-1ÎČ. Further, the treatment of tendon cell cultures with HGF antibodies reduced the suppressive effects of PRP or HGF on IL-1ÎČ-induced COX-1, COX-2, and mPGES-1 gene expressions. Treatment with PRP or HGF almost completely blocked the cellular production of PGE2 and the expression of COX proteins. Finally, injection of PRP or HGF into wounded mouse Achilles tendons in vivo decreased PGE2 production in the tendinous tissues. Injection of platelet-poor plasma (PPP) however, did not reduce PGE2 levels in the wounded tendons, but the injection of HGF antibody inhibited the effects of PRP and HGF. Further, injection of PRP or HGF also decreased COX-1 and COX-2 proteins. These results indicate that PRP exerts anti-inflammatory effects on injured tendons through HGF. This study provides basic scientific evidence to support the use of PRP to treat injured tendons because PRP can reduce inflammation and thereby reduce the associated pain caused by high levels of PGE2. © 2013 Zhang et al
Safety of pregnancy after breast cancer in young women with hormone receptor-positive disease: a systematic review and meta-analysis
Despite increasing evidence on the safety of pregnancy after anticancer treatments in breast cancer survivors, many physicians and patients remain concerned about a potential risk of pregnancy specifically in the case of hormone receptor-positive breast cancer.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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