Symmetric angular momentum coupling, the quantum volume operator and the 7-spin network: a computational perspective

A unified vision of the symmetric coupling of angular momenta and of the quantum mechanical volume operator is illustrated. The focus is on the quantum mechanical angular momentum theory of Wigner's 6j symbols and on the volume operator of the symmetric coupling in spin network approaches: here, crucial to our presentation are an appreciation of the role of the Racah sum rule and the simplification arising from the use of Regge symmetry. The projective geometry approach permits the introduction of a symmetric representation of a network of seven spins or angular momenta. Results of extensive computational investigations are summarized, presented and briefly discussed.Comment: 15 pages, 10 figures, presented at ICCSA 2014, 14th International Conference on Computational Science and Application

Macroscopic behavior of bidisperse suspensions of noncolloidal particles in yield stress fluids

We study both experimentally and theoretically the rheological behavior of isotropic bidisperse suspensions of noncolloidal particles in yield stress fluids. We focus on materials in which noncolloidal particles interact with the suspending fluid only through hydrodynamical interactions. We observe that both the elastic modulus and yield stress of bidisperse suspensions are lower than those of monodisperse suspensions of same solid volume fraction. Moreover, we show that the dimensionless yield stress of such suspensions is linked to their dimensionless elastic modulus and to their solid volume fraction through the simple equation of Chateau et al.[J. rheol. 52, 489-506 (2008)]. We also show that the effect of the particle size heterogeneity can be described by means of a packing model developed to estimate random loose packing of assemblies of dry particles. All these observations finally allow us to propose simple closed form estimates for both the elastic modulus and the yield stress of bidisperse suspensions: while the elastic modulus is a function of the reduced volume fraction $\phi/\phi_m$ only, where $\phi_m$ is the estimated random loose packing, the yield stress is a function of both the volume fraction $\phi$ and the reduced volume fraction

The screen representation of vector coupling coefficients or Wigner 3j symbols: exact computation and illustration of the asymptotic behavior

The Wigner $3j$ symbols of the quantum angular momentum theory are related to the vector coupling or Clebsch-Gordan coefficients and to the Hahn and dual Hahn polynomials of the discrete orthogonal hyperspherical family, of use in discretization approximations. We point out the important role of the Regge symmetries for defining the screen where images of the coefficients are projected, and for discussing their asymptotic properties and semiclassical behavior. Recursion relationships are formulated as eigenvalue equations, and exploited both for computational purposes and for physical interpretations.Comment: 14 pages, 8 figures, presented at ICCSA 2014, 14th International Conference on Computational Science and Application

Energy and directional signatures for plane quantized gravity waves

Solutions are constructed to the quantum constraints for planar gravity (fields dependent on z and t only) in the Ashtekar complex connection formalism. A number of operators are constructed and applied to the solutions. These include the familiar ADM energy and area operators, as well as new operators sensitive to directionality (z+ct vs. z-ct dependence). The directionality operators are quantum analogs of the classical constraints proposed for unidirectional plane waves by Bondi, Pirani, and Robinson (BPR). It is argued that the quantum BPR constraints will predict unidirectionality reliably only for solutions which are semiclassical in a certain sense. The ADM energy and area operators are likely to have imaginary eigenvalues, unless one either shifts to a real connection, or allows the connection to occur other than in a holonomy. In classical theory, the area can evolve to zero. A quantum mechanical mechanism is proposed which would prevent this collapse.Comment: 54 pages; LaTe

Tratamento Clínico e Cirúrgico de Hiperplasia Palatina Causada por Câmara de Sucção

ResumoA hiperplasia palatina por câmara de sucção ou hiperplasia inflamatória do palato está associada ao uso de prótese totais superiores com câmara de vácuo, acometendo de 1% a 11% dos indivíduos que fazem uso de próteses totais. Odiagnóstico é realizado através do exame clínico, com uma maior incidência em pacientes na 5a e 6a décadas de vida e que fazem o uso da mesma prótese há mais de 15 anos. É apresentado o tratamento de um caso de hiperplasia palatina causada pela câmara de sucção numa paciente que fazia o uso da mesma dentadura há mais de 15 anos, com completa resolução do caso.AbstractThe palatine hyperplasia caused by suction chamber or the palatine inflammatory hyperplasia is associated to suction chambers confectioned on totally prosthesis, been present in 1% to 11% of all the patients that ware this type of prosthesis. The diagnosis is done by the clinical exam, with a higher incidence in individuals living during the 5th and 6th decade of live and wearing the same apparatus more than 15 years. It is presented the treatment of a suction chamber palatine hyperplasia in a patient wearing the same prosthesis for more than 15 years, with good result

Living with multiple losses: Insights from patients living with pressure injury

© 2017 Australian College of Nursing Ltd Background: Pressure injury is a common problem. Its prevention and treatment is predominantly focussed on views, perceptions and knowledge of healthcare staff rather than on patient experience, particularly those patients living in their own homes. Aim: This paper reports findings on patients experiences and perceptions of loss associated with PI. These findings are drawn from a larger study of pressure injury patients living and receiving care in the community. Methods: Qualitative interviews with 12 participants with pressure injury and five carers. Data was audio recorded and thematically analysed. The study is reported in accordance with the COREQ guidelines. Findings: Having a pressure injury negatively affected many aspects of life for our participants resulting in multiple losses. These losses included loss of mobility and independence, privacy and dignity, and social engagement and ability to engage in preferred activities. Discussion: Although the effects of a pressure injury may be similar for many people, the most important issues will differ from person-to-person thus treatment and prevention of pressure injury requires a multidisciplinary team having a holistic care approach. Some patients’ pressure injury will never heal and it is increasingly important to involve the patient to find out what matters most to them and how their wound is impacting on them, to jointly develop a holistic, person-centred plan. Conclusion: Policy and practice should recognise and reflect that patients living with a pressure injury at home have different challenges and needs to those in acute or long term care. Pragmatic solutions in the delivery of pressure injury care are needed to compliment the drive to move healthcare from the hospital-to-home

Tribological properties of aluminium-clay composites for brake disc rotor applications

In this paper, the mechanical and tribological behaviours of various compositions of aluminium 6063 alloy – clay (Al-clay) composites for brake pad applications were studied. The Al-clay composites with 5-30 wt.% of clay particles of grain size of 60 BSS (250 microns) were developed through stir casting route. The wear characteristics of Al-clay in dry sliding conditions were subjected to a series of Denison T62 HS pin-on-disc wear tests. The action of two different loads (4 and 10N), three sliding speeds of 200, 500 and 1000 rpm were investigated. The results of the mechanical and wear tests as well as the metallographic investigation of optical, scanning electron microscopy and energy dispersive X-ray microscopy revealed an improvement in the tensile strength, hardness and wear resistance in the composites with 10-25 wt.% clays. The best values were obtained at 15 wt.%. Wear rate was highly influenced by applied load and sliding speed. The developed composites with 15-25 wt.% clay addition were similar to conventional semi metallic brake pad in terms of wear and friction properties

Socio-demographic, psychosocial and home-environmental attributes associated with adults' domestic screen time.

BACKGROUND: Sedentary behaviors (involving prolonged sitting time) are associated with deleterious health consequences, independent of (lack of) physical activity. To inform interventions, correlates of prevalent sedentary behaviors need to be identified. We examined associations of socio-demographic, home-environmental and psychosocial factors with adults' TV viewing time and leisure-time Internet use; and whether psychosocial and environmental correlates differed according to gender, age and educational attainment. METHODS: This cross-sectional study was conducted in Ghent, Belgium, between March and May 2010. Respondents to a mail-out survey (n = 419; 20-65 years; mean age 48.5 [12.1] years; 47.3% men) completed a questionnaire on sedentary behaviors and their potential socio-demographic, psychosocial and home environmental correlates. Statistical analyses were performed using multiple linear regression models. RESULTS: The independent variables explained 31% of the variance in TV viewing time and 38% of the variance in leisure-time Internet use. Higher education, greater perceived pros of and confidence about reducing TV time were negatively associated with TV viewing time; older age, higher body mass index, larger TV set size and greater perceived cons of reducing TV time showed positive associations. Perceived pros of and confidence about reducing Internet use were negatively associated with leisure-time Internet use; higher education, number of computers in the home, positive family social norms about Internet use and perceived cons of reducing Internet use showed positive associations. None of the socio-demographic factors moderated these associations. CONCLUSIONS: Educational level, age, self-efficacy and pros/cons were the most important correlates identified in this study. If further cross-sectional and longitudinal research can confirm these findings, tailored interventions focusing on both psychosocial and environmental factors in specific population subgroups might be most effective to reduce domestic screen time.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Unemployment, parental distress and youth emotional well-being : the moderation roles of parent-youth relationship and financial deprivation

We investigated, in a sample of 112 unemployed parents of adolescents aged 10-19 years, the links between parental distress and change in youth emotional problems related to parental unemployment, and the moderation roles of parent-youth relationship and financial deprivation. Data were analyzed using descriptive statistics and correlations. Further, simple moderation, additive moderation, and moderated moderation models of regression were performed to analyze the effects of parental distress, parent-youth relationship and financial deprivation in predicting change in youth emotional problems related to parental unemployment. Results show that parental distress moderated by parent-youth relationship predicted levels of change in youth emotional problems related to parental unemployment. This study provides evidence that during job loss, parental distress is linked to youth emotional well-being and that parent-youth relationships play an important moderation role. This raises the importance of further researching parental distress impacts on youth well-being, especially during periods of high unemployment rates.PostprintPeer reviewe

Older adults' reporting of specific sedentary behaviors : validity and reliability

Background: Previous questionnaires targeting older adults' sedentary time have underestimated total sedentary time, possibly by not including all relevant specific sedentary behaviors. The current study aimed to investigate the criterion validity and test-retest reliability of a new questionnaire assessing a comprehensive set of sedentary behaviors. Additionally, we examined whether the criterion validity of the questionnaire differed according to age, gender and educational level. Methods: A sample of home-dwelling Belgian older adults (>64 years, n = 508) completed a newly-developed questionnaire assessing twelve specific sedentary behaviors and wore an accelerometer for seven consecutive days as criterion measure. A subsample (n = 28) completed the questionnaire a second time to examine test-retest reliability. Data collection occurred between September 2010 and October 2012. Results: Correlational analyses examining self-reported total sitting time and accelerometer-derived sedentary time yielded a Spearman's. of 0.30. Using the Bland-Altman regression procedure, self-reported total sitting time underestimated accelerometer-derived sedentary time by -82 minutes/day for a participant with an average level of sedentary time (539 minutes/day). Corresponding 95% limits of agreement were wide (-364, 200 minutes/day). Better, but still not ideal, validity findings were observed in the younger, male and tertiary-educated subgroups. Acceptable test-retest reliability (ICC > 0.70) was found for total sitting time, TV viewing, computer use, and driving a car. Conclusion: Validity for older adults' self-reported total sitting time against accelerometer-derived sedentary time was not strong, but comparable to previous studies. However, underestimation of total sedentary time was lower compared to previous studies, possibly explained by the inclusion of additional specific sedentary behaviors. Further research is needed to develop self-report tools and objective criterion measures that accurately measure engagement in (specific) sedentary behavior(s) among different subgroups of the older population