The potential relevance of altered muscle activity and fatigue in the development of performance-related musculoskeletal injuries in high string musicians

Background: Muscle fatigue has been reported as a risk factor for the development of performance-related musculoskeletal disorders (PRMD) in musicians. However, little research exists to support this claim. The aim of this study was to investigate whether changes occur in muscle activity patterns during high string performance over a prolonged playing period, and whether this is influenced by PRMD. Methods: High string musicians were divided into a PRMD and a non-PRMD group. They played a chromatic scale pre and post and a self-chosen “hard” (Borg scale 16-17) piece of music for one hour. Electromyography data recorded from arm, shoulder and trunk muscles was analyzed: the amplitude to measure muscle activity characteristics and the lower frequency to measure muscle fatigue. Differences between and within groups and the frequency spectrum were analyzed using linear mixed models. Results: Fifteen musicians participated (7 PRMD: 22.8 years, 2 male/5 female and 8 non-PRMD: 34.3 years, 2 male/6 female). Changes in muscle activation patterns were observed between and within both groups, however changes varied significantly depending on group affiliation. Significant low frequency spectrum changes between groups were observed in overall muscles of the right arm (p=0.04) and left forearm flexors (p=0.05) following one hour of playing. Conclusions: Muscle activity and frequency spectrum shifts differ in high string musicians with and without PRMD, suggesting possible differential muscle fatigue effects between the groups

Dynamical Equations For The Period Vectors In A Periodic System Under Constant External Stress

The purpose of this paper is to derive the dynamical equations for the period vectors of a periodic system under constant external stress. The explicit starting point is Newton's second law applied to halves of the system. Later statistics over indistinguishable translated states and forces associated with transport of momentum are applied to the resulting dynamical equations. In the final expressions, the period vectors are driven by the imbalance between internal and external stresses. The internal stress is shown to have both full interaction and kinetic-energy terms.Comment: 10 pages, 2 figures include

Towards Efficient Verification of Population Protocols

Population protocols are a well established model of computation by anonymous, identical finite state agents. A protocol is well-specified if from every initial configuration, all fair executions reach a common consensus. The central verification question for population protocols is the well-specification problem: deciding if a given protocol is well-specified. Esparza et al. have recently shown that this problem is decidable, but with very high complexity: it is at least as hard as the Petri net reachability problem, which is EXPSPACE-hard, and for which only algorithms of non-primitive recursive complexity are currently known. In this paper we introduce the class WS3 of well-specified strongly-silent protocols and we prove that it is suitable for automatic verification. More precisely, we show that WS3 has the same computational power as general well-specified protocols, and captures standard protocols from the literature. Moreover, we show that the membership problem for WS3 reduces to solving boolean combinations of linear constraints over N. This allowed us to develop the first software able to automatically prove well-specification for all of the infinitely many possible inputs.Comment: 29 pages, 1 figur

Playing-related musculoskeletal disorders among classical piano students at tertiary institutions in Malaysia: proportion and associated risk factors

Musicians are prone to performance injuries due to the nature of musical practice, and classical pianists are among the groups at high risk for playing-related musculoskeletal disorders (PRMDs). With the growing number of classical pianists in Malaysia, this study aimed to investigate the proportion of PRMDs occurring among classical piano students in tertiary institutions in Malaysia. Associations between gender, practice habits, diet, sports involvement, and PRMD were investigated. A survey was conducted among classical piano students (n=192) at tertiary institutions of Kuala Lumpur and Selangor. Results showed that 35.8% (n=68) students reported having PRMD. The shoulder was the most commonly affected body site, followed by the arm, finger, and wrist. Pain, fatigue, and stiffness were the most cited symptoms by those who suffered from a PRMD. Chi-square analysis showed a significant relationship between the occurrence of PRMD and practice hours (p=0.031), the habit of taking breaks during practice (p=0.045), physical cool-down exercises (p=0.037), and special diet (p=0.007). Multivariate logistic regression analyses confirmed the independent correlation between PRMDs and the lack of taking a break during practice, physical cool-down exercises, and special diet. Because PRMDs are reported at various severity levels, this study should increase awareness of PRMD among classical piano students and encourage injury prevention in musicians in the future to ensure long-lasting music careers

On the Error Exponents of ARQ Channels with Deadlines

We consider communication over Automatic Repeat reQuest (ARQ) memoryless channels with deadlines. In particular, an upper bound L is imposed on the maximum number of ARQ transmission rounds. In this setup, it is shown that incremental redundancy ARQ outperforms Forney's memoryless decoding in terms of the achievable error exponents.Comment: 16 pages, 6 figures, Submitted to the IEEE Trans. on Information Theor

The hull variation problem for projective Reed-Muller codes and quantum error-correcting codes

Long quantum codes using projective Reed-Muller codes are constructed. Projective Reed-Muller are evaluation codes obtained by evaluating homogeneous polynomials at the projective space. We obtain asymmetric and symmetric quantum codes by using the CSS construction and the Hermitian construction, respectively. We provide entanglement-assisted quantum error-correcting codes from projective Reed-Muller codes with flexible amounts of entanglement by considering equivalent codes. Moreover, we also construct quantum codes from subfield subcodes of projective Reed-Muller codes

The prevalence of playing-related musculoskeletal disorders in selected Western classical music students at the South African College of Music, University of Cape Town

The study aimed to ascertain the prevalence of playing-related musculoskeletal disorders (PRMDs) among Western classical instrumentalists at the South African College of Music. Seventy-two undergraduate string, woodwind and keyboard instrumental students were approached during classes or individually and asked to complete a specially designed questionnaire. Data were sent to a statistician at the University of Cape Town Statistics Consulting Unit and the statistical package SPSS (Version 22) was used to analyse the data. Seventy-one (71) of the 72 questionnaires were returned. The average respondent was a 20-year-old, right-handed female who had been playing her instrument for 10.8 years; 88.8% of the respondents had experienced a PRMD at some point in their lives, 82.1% within the preceding 12 months and 46.3% had a PRMD at the time of the study. No correlation was found between the prevalence of a PRMD and age, gender, instrument type, number of years of playing the instrument, playing another instrument or the university programme, stream or year. A significant relationship was found between the instrument level and the current prevalence of PRMDs. The most commonly affected area was the shoulder followed by the back, neck, hand or wrist and fingers. The most commonly indicated duration was 1 week (35.3%), though many PRMDs had lasted for more than 2 years (19.6%); 46.3% of the PRMDs had a severity of 3/5 or higher, and 34.2% of PRMDs were both 3/5 or higher for severity and frequency. Only 3.7% of the responses indicated that a body awareness technique was being used regularly, while 37.4% of the answers indicated that the techniques had "never been heard of". Over half (51.7%) of respondents had consulted a health professional. Physiotherapists and Alexander teachers were the most frequently consulted professionals. Treatment strategies were non-invasive and mostly self-reliant and though most respondents felt that the treatment strategies had helped temporarily, there was little long-term satisfaction. This study concludes that the prevalence of PRMDs in students at the South African College of music is high and around half of the PRMDs affect the students' ability to play or perform their instrument at an optimum level. Actions can and need to be taken to reduce these values in future

Grant-Free Massive MTC-Enabled Massive MIMO: A Compressive Sensing Approach

A key challenge of massive MTC (mMTC), is the joint detection of device activity and decoding of data. The sparse characteristics of mMTC makes compressed sensing (CS) approaches a promising solution to the device detection problem. However, utilizing CS-based approaches for device detection along with channel estimation, and using the acquired estimates for coherent data transmission is suboptimal, especially when the goal is to convey only a few bits of data. First, we focus on the coherent transmission and demonstrate that it is possible to obtain more accurate channel state information by combining conventional estimators with CS-based techniques. Moreover, we illustrate that even simple power control techniques can enhance the device detection performance in mMTC setups. Second, we devise a new non-coherent transmission scheme for mMTC and specifically for grant-free random access. We design an algorithm that jointly detects device activity along with embedded information bits. The approach leverages elements from the approximate message passing (AMP) algorithm, and exploits the structured sparsity introduced by the non-coherent transmission scheme. Our analysis reveals that the proposed approach has superior performance compared to application of the original AMP approach.Comment: Submitted to IEEE Transactions on Communication