Level Statistics of XXZ Spin Chains with Discrete Symmetries: Analysis through Finite-size Effects

Level statistics is discussed for XXZ spin chains with discrete symmetries for some values of the next-nearest-neighbor (NNN) coupling parameter. We show how the level statistics of the finite-size systems depends on the NNN coupling and the XXZ anisotropy, which should reflect competition among quantum chaos, integrability and finite-size effects. Here discrete symmetries play a central role in our analysis. Evaluating the level-spacing distribution, the spectral rigidity and the number variance, we confirm the correspondence between non-integrability and Wigner behavior in the spectrum. We also show that non-Wigner behavior appears due to mixed symmetries and finite-size effects in some nonintegrable cases.Comment: 19 pages, 6 figure

Semiclassical theory for many-body Fermionic systems

We present a treatment of many-body Fermionic systems that facilitates an expression of the well-known quantities in a series expansion of the Planck's constant. The ensuing semiclassical result contains to a leading order of the response function the classical time correlation function of the observable followed by the Weyl-Wigner series, on top of these terms are the periodic-orbit correction terms. The treatment given here starts from linear response assumption of the many-body theory and in its connection with semiclassical theory, it makes no assumption of the integrability of classical dynamics underlying the one-body quantal system. Applications of the framework are also discussed.Comment: 18 pages, Te

Joint action modulates motor system involvement during action observation in 3-year-olds

When we are engaged in a joint action, we need to integrate our partner’s actions with our own actions. Previous research has shown that in adults the involvement of one’s own motor system is enhanced during observation of an action partner as compared to during observation of an individual actor. The aim of this study was to investigate whether similar motor system involvement is present at early stages of joint action development and whether it is related to joint action performance. In an EEG experiment with 3-year-old children, we assessed the children’s brain activity and performance during a joint game with an adult experimenter. We used a simple button-pressing game in which the two players acted in turns. Power in the mu- and beta-frequency bands was compared when children were not actively moving but observing the experimenter’s actions when (1) they were engaged in the joint action game and (2) when they were not engaged. Enhanced motor involvement during action observation as indicated by attenuated sensorimotor mu- and beta-power was found when the 3-year-olds were engaged in the joint action. This enhanced motor activation during action observation was associated with better joint action performance. The findings suggest that already in early childhood the motor system is differentially activated during action observation depending on the involvement in a joint action. This motor system involvement might play an important role for children’s joint action performance

Injury profile of musicians in the Bloemfontein-based Free State symphony orchestra: a short report

Similar  to  professional  athletes,  musicians  are  required  to perform optimally.  Few  studies  have  been  conducted  to  clarify  the  nature of injuries associated with musicians. This study aimed to determine the types of injuries and their prevalence amongst the musicians of the Free State Symphony orchestra (FSSo), contributing factors, the musicians’ response to injury, and their perception of physiotherapy. Forty-five members of the FSSO participated in this descriptive study. Analysis of data included frequencies and percentages for categorical data and percentiles for continuous data. Thirty-eight (84.4%) participants reported injuries related to playing their instruments. Insufficient resting  periods  during playing  sessions  (70.3%),  continuing  to  play  while experiencing symptoms (63.2%) and performing the same movement repetitively (64.9%) were identified as the perceived risk factors in the development of symptoms.  Seventeen  (44.7%)  participants  indicated that they  did  nothing  to relieve their symptoms, while 34.2% sought physiotherapy treatment, 31.6% took medication to alleviate their symptoms and 31.6% reduced their playing hours. Majority of participants (75%) felt that their symptoms could be relieved by physiotherapy. Injuries amongst musicians result from a combination of factors such as posture, repetitive movements and fatigue. Possible physiotherapeutic intervention identified included educating musicians on the advantages of early management of injuries in extending their professional careers

Polymorphisms within the adenosine receptor 2a gene are associated with adverse events in RA patients treated with MTX

Objective. To examine the role of adenosine receptor 2a gene (ADORA2a) polymorphisms on outcome of MTX treatment in RA

Degradation levels of continuous speech affect neural speech tracking and alpha power differently

Making sense of a poor auditory signal can pose a challenge. Previous attempts to quantify speech intelligibility in neural terms have usually focused on one of two measures, namely low-frequency speech-brain synchronization or alpha power modulations. However, reports have been mixed concerning the modulation of these measures, an issue aggravated by the fact that they have normally been studied separately. We present two MEG studies analyzing both measures. In study 1, participants listened to unimodal auditory speech with three different levels of degradation (original, 7-channel and 3-channel vocoding). Intelligibility declined with declining clarity, but speech was still intelligible to some extent even for the lowest clarity level (3-channel vocoding). Low-frequency (1-7 Hz) speech tracking suggested a u-shaped relationship with strongest effects for the medium degraded speech (7-channel) in bilateral auditory and left frontal regions. To follow up on this finding, we implemented three additional vocoding levels (5-channel, 2-channel, 1-channel) in a second MEG study. Using this wider range of degradation, the speech-brain synchronization showed a similar pattern as in study 1 but further showed that when speech becomes unintelligible, synchronization declines again. The relationship differed for alpha power, which continued to decrease across vocoding levels reaching a floor effect for 5-channel vocoding. Predicting subjective intelligibility based on models either combining both measures or each measure alone, showed superiority of the combined model. Our findings underline that speech tracking and alpha power are modified differently by the degree of degradation of continuous speech but together contribute to the subjective speech understanding

Применение технологии набрызгбетонирования в Новоавстрийском Методе Туннелирования (NATM)

У статті проаналізовані суть і основні принципи Новоавстрійського Методу Тунелювання (NATM), що широко застосовується в зарубіжній практиці будівництва транспортних тунелів. Також розглянуто застосування технології торкретування, яка лежить в основі методу.Essence and basic principles of New Austrian Tunnelling Method (NATM), which widely used in foreign practice building of transport tunnels, is analysed in the article. Application of gunite technology, being the basis of method, is also considered

Comparing three short questionnaires to detect psychosocial dysfunction among primary school children: a randomized method

BACKGROUND: Good questionnaires are essential to support the early identification of children with psychosocial dysfunction in community based settings. Our aim was to assess which of three short questionnaires was most suitable for this identification among school-aged children METHODS: A community-based sample of 2,066 parents of children aged 7-12 years (85% of those eligible) filled out the Child Behavior Checklist (CBCL) and - randomly determined - one of three questionnaires to be compared: the Strengths and Difficulties Questionnaire with Impact Supplement (SDQ), the Pediatric Symptom Checklist (PSC) and the PSYBOBA, a Dutch-origin questionnaire. Preventive Child Healthcare professionals assessed children's psychosocial functioning during routine health examinations. We assessed the scale structure (by means of Structural Equation Modelling), validity (correlation coefficients, sensitivity and specificity) and usability (ratings by parents and professionals) of each questionnaire and the degree to which they could improve the identification based only on clinical assessment (logistic regression). RESULTS: For the three questionnaires, Cronbach's alphas varied between 0.80 and 0.89. Sensitivities for a clinical CBCL at a cut off point with specificity = 0.90 varied between 0.78 and 0.86 for the three questionnaires. Areas under the Receiver Operating Curve, using the CBCL as criterion, varied between 0.93 and 0.96. No differences were statistically significant. All three questionnaires added information to the clinical assessment. Odds ratios (95% confidence intervals) for added information were PSC: 29.3 (14.4-59.8), SDQ: 55.0 (23.1-131.2) and PSYBOBA: 68.5 (28.3-165.6). Parents preferred the SDQ and PSYBOBA. Preventive Child Health Care professionals preferred the SDQ. CONCLUSIONS: This randomized comparison of three questionnaires shows that each of the three questionnaires can improve the detection of psychosocial dysfunction among children substantially

A Computational Clonal Analysis of the Developing Mouse Limb Bud

A comprehensive spatio-temporal description of the tissue movements underlying organogenesis would be an extremely useful resource to developmental biology. Clonal analysis and fate mappings are popular experiments to study tissue movement during morphogenesis. Such experiments allow cell populations to be labeled at an early stage of development and to follow their spatial evolution over time. However, disentangling the cumulative effects of the multiple events responsible for the expansion of the labeled cell population is not always straightforward. To overcome this problem, we develop a novel computational method that combines accurate quantification of 2D limb bud morphologies and growth modeling to analyze mouse clonal data of early limb development. Firstly, we explore various tissue movements that match experimental limb bud shape changes. Secondly, by comparing computational clones with newly generated mouse clonal data we are able to choose and characterize the tissue movement map that better matches experimental data. Our computational analysis produces for the first time a two dimensional model of limb growth based on experimental data that can be used to better characterize limb tissue movement in space and time. The model shows that the distribution and shapes of clones can be described as a combination of anisotropic growth with isotropic cell mixing, without the need for lineage compartmentalization along the AP and PD axis. Lastly, we show that this comprehensive description can be used to reassess spatio-temporal gene regulations taking tissue movement into account and to investigate PD patterning hypothesis