Nonlinear phononic crystals based on chains of disks alternating with toroidal structures

We study experimentally the acoustic response of a load-bearing, phononic crystal composed of alternating steel disks, and polytetrafluoroethylene o-rings under precompression. The crystal allows for axial, rocking, and shear-polarized wavemodes when excited by a broad-band signal applied off-axis. Finite element analysis is employed to determine the system’s wave modes. The nonlinear interaction between disks and o-rings supports a dynamic response that is tunable with variations in static precompression, leading to controllable frequency shifts in a large band gap. A modal analysis reveals that four of the six principal wave modes are susceptible to external precompression while two modes are not

A Groenewold-Van Hove Theorem for S^2

We prove that there does not exist a nontrivial quantization of the Poisson algebra of the symplectic manifold S^2 which is irreducible on the subalgebra generated by the components {S_1,S_2,S_3} of the spin vector. We also show that there does not exist such a quantization of the Poisson subalgebra P consisting of polynomials in {S_1,S_2,S_3}. Furthermore, we show that the maximal Poisson subalgebra of P containing {1,S_1,S_2,S_3} that can be so quantized is just that generated by {1,S_1,S_2,S_3}.Comment: 20 pages, AMSLaTe

Constrained Dynamics for Quantum Mechanics I. Restricting a Particle to a Surface

We analyze constrained quantum systems where the dynamics do not preserve the constraints. This is done in particular for the restriction of a quantum particle in Euclidean n-space to a curved submanifold, and we propose a method of constraining and dynamics adjustment which produces the right Hamiltonian on the submanifold when tested on known examples. This method we hope will become the germ of a full Dirac algorithm for quantum constraints. We take a first step in generalising it to the situation where the constraint is a general selfadjoint operator with some additional structures.Comment: 49 pages, TEX, input files amssym.def, amssym.te

Capitalizing on the placebo component of treatments

A placebo treatment is traditionally administered in a double-blind, randomized controlled trial to control for the ‘real’ effects of the treatment under investigation. In the present paper a broader view of the placebo is proposed, one in which the idea of a potentially ‘useable’ placebo component of a sports or exercise medicine treatment is presented. It is argued that many interventions in sport and exercise psychology might contain a placebo component that could be capitalized upon by practitioners, through processes often as simple as communicating positive expectations of a treatment to clients. Research findings relating to factors that might influence an individual’s response to a placebo, such as personality, situation and genetics, are briefly addressed. Ethical considerations for practice and future research are discussed

Glueball Spin

The spin of a glueball is usually taken as coming from the spin (and possibly the orbital angular momentum) of its constituent gluons. In light of the difficulties in accounting for the spin of the proton from its constituent quarks, the spin of glueballs is reexamined. The starting point is the fundamental QCD field angular momentum operator written in terms of the chromoelectric and chromomagnetic fields. First, we look at the restrictions placed on the structure of glueballs from the requirement that the QCD field angular momentum operator should satisfy the standard commutation relationships. This can be compared to the electromagnetic charge/monopole system, where the quantization of the field angular momentum places restrictions (i.e. the Dirac condition) on the system. Second, we look at the expectation value of this operator under some simplifying assumptions.Comment: 11 pages, 0 figures; added references and some discussio

The 6-vertex model of hydrogen-bonded crystals with bond defects

It is shown that the percolation model of hydrogen-bonded crystals, which is a 6-vertex model with bond defects, is completely equivalent with an 8-vertex model in an external electric field. Using this equivalence we solve exactly a particular 6-vertex model with bond defects. The general solution for the Bethe-like lattice is also analyzed.Comment: 13 pages, 6 figures; added references for section

Stochastic models which separate fractal dimension and Hurst effect

Fractal behavior and long-range dependence have been observed in an astonishing number of physical systems. Either phenomenon has been modeled by self-similar random functions, thereby implying a linear relationship between fractal dimension, a measure of roughness, and Hurst coefficient, a measure of long-memory dependence. This letter introduces simple stochastic models which allow for any combination of fractal dimension and Hurst exponent. We synthesize images from these models, with arbitrary fractal properties and power-law correlations, and propose a test for self-similarity.Comment: 8 pages, 2 figure

Where lean construction and value management meet

The lean construction (LC) community’s key vision and goal is to provide value, yet they are increasingly challenged with understanding and dealing with the concept of value, with reports that value is one of the weakest points. Regardless of the previous studies and contributions already made on the concept of value in LC, the absence of a consistent understanding of value has resulted in misperceptions and indistinct boundaries with other construction value-related disciplines. Without a consistent understanding of value, the full potential of applying value-established concepts will not occur. Thus, the study of different concepts in construction will open new opportunities to deliver value in the future. Literature reviewed only revealed a small number of interdisciplinary comparisons of Lean manufacturing and LC with value management (VM)/value engineering (VE) on value. Secondary data was used to present an in-depth comparison of the principal points of the current practice and theories of LC and VM, which are seen as ways to improve the delivery of value to clients and building users. The study revealed a range of similarities at a high level, which could easily point to an early conclusion that LC and VM are interchangeable, leading to the same goal of value delivery and shared misapplication of cost reduction techniques. However, a more detailed examination indicates significant differences in the philosophy and scope in different areas, including project timing, practitioner duties, and areas of practice which could complement each other. Also the study identified that LC is a broader philosophy which covers more aspects than VM, it is evident that LC has advanced over the years towards discussions on the concept of value. The current work in LC on value relies less on other construction value-related disciplines such as VM, VE and partnering. Furthermore, LC literature still views value as a confusing concept associated with different interpretations, forming the basisof its understanding. The study established that value plays a central role in both LC and VM. Their combination could offer great synergy regarding the concept of value

Is the intention to use sport supplements a predictor of placebo and nocebo responding among athletes?

Background: Placebo and nocebo effects have been observed in relation to many interventions in sport. Given variance in response, a key question is whether individual difference variables identify likely ‘responders.’ Hypothetically, such a variable might be the person’s intention to use the intervention. We aimed to explore relationships between athletes' intention to use sport supplements and their responses to a placebo/nocebo intervention. Methods: Participants completed a single-item measure of intention to use sport supplements (‘intending’, ‘undecided’ or ‘not intending’) prior to 5×20-m sprints. Participants were then randomised to Placebo (n=219), Nocebo (n=168) and Control (n = 134) conditions. Participants in Placebo and Nocebo conditions were administered a capsule deceptively presented as a sport supplement that would have a positive (Placebo) or negative (Nocebo) effect on performance. Controls were provided with no instructions and received no capsule. After 20 minutes, all participants completed another set of 5×20-m sprints. Results: Among ‘intending to use’ participants, the Placebo treatment was associated with faster times than the Nocebo treatment (P=0.023, Cohen’s d [d]=0.34). In the Placebo treatment, ‘intending to use’ participants were significantly faster than ‘not intending to use’ participants (P=0.004, d=0.49), as were ‘intending to use’ participants in relation to ‘undecided’ participants in the Nocebo treatment (P=0.044, d=0.44). No significant differences in performance by intention were observed in the Control condition. Conclusions: Placebo and nocebo responses appear to be mediated by the participant’s intention to use supplements. These findings have value in explaining placebo/nocebo responses, and should be tested in clinical medical settings

Is there a role for implicit and explicit information about placebo and nocebo effects in reducing the use of drugs in sport?

Background: The gateway hypothesis posits that the use of sport supplements by athletes can lead to the use of banned and possibly harmful performance-enhancing drugs. Previous data suggest that athletes implicitly exposed to a placebo intervention and/or explicitly informed about the role of placebo effects in sport may be less likely to use sports supplements, and therefore - in line with the gateway hypothesis - less likely to progress to drugs. Methods: Participants (n=629) completed the Sports Supplements Beliefs Scale (SSBS), Performance Enhancement Attitude Scale (PEAS) and a Likert-type scale measuring intention to use sports supplements. They were then randomised to Placebo (n=263), Nocebo (n=209) and Control (n=157). All participants completed a performance trial (see Hurst et al., this conference). Placebo and Nocebo participants subsequently received the results of the trial as well as a brief educational session describing the role of placebo/nocebo effects in sports performance. Controls received no information. All participants re-completed the questionnaires. Results: Analyses indicated that following the intervention, beliefs (P=0.009, Cohens d [d]=0.43), attitudes (P=0.047, d=0.29) and intentions (P=0.020, d=0.33) relating to the use of drugs and sport supplements were significantly lower in the Placebo and Nocebo group compared to Controls. Conclusions: Implicit exposure to a placebo/nocebo intervention and explicit exposure to a brief educational intervention about placebo effects influenced athlete’s beliefs, attitudes and intentions about drugs and sport supplements. Given the gateway hypothesis, experience of, or education about the placebo and nocebo effect may prevent athletes transitioning towards doping