The effects of grain shape and frustration in a granular column near jamming

We investigate the full phase diagram of a column of grains near jamming, as a function of varying levels of frustration. Frustration is modelled by the effect of two opposing fields on a grain, due respectively to grains above and below it. The resulting four dynamical regimes (ballistic, logarithmic, activated and glassy) are characterised by means of the jamming time of zero-temperature dynamics, and of the statistics of attractors reached by the latter. Shape effects are most pronounced in the cases of strong and weak frustration, and essentially disappear around a mean-field point.Comment: 17 pages, 19 figure

How do you foresee the requirements for ultrasonic standards changing as NDE evolves from a defect detection mode to a quantitative defect characterization mode?

The topic of our panel discussion is: How do you foresee the requirements for ultrasonic standards changing as NDE evolves from a defect detection mode to a defect characterization mode? We\u27ve heard a number of comments yesterday and today about the problem of standards. Our plan for the balance of the day in the panel session is to hear from a group of experts who have had considerable experience, and therefore, have developed varied opinions on the problem of standards. We\u27ll hear briefly from each of them, and then have an open discussion where those in the audience are invited to participate

Well-being, job satisfaction, stress and burnout in speech-language pathologists: A review.

Purpose: The purpose of this review was to evaluate the factors that influence well-being, job satisfaction, stress, and burnout in speech-language pathologists (SLPs), and to identify the impact of these variables on worker recruitment and retention. Method: A systematic literature search was conducted. Four electronic databases (PsycARTICLES & PsycINFO, PubMed/Medline, CINHAL and ABI/INFORM) were searched. The search was limited to articles published in English between 1998 and June 2018. To be eligible for inclusion, studies needed to investigate or report well-being, job satisfaction, stress or burnout in SLPs. The methodological quality of each paper was assessed using the “Strengthening the Reporting of Observational Studies in Epidemiology” (for quantitative data) and “Consolidated criteria for Reporting Qualitative research” (for qualitative data) checklists. A data-driven thematic analysis of the literature was used to identify key themes. Result: Seventeen of 2050 studies met the inclusion criteria, of which fifteen were cross-sectional surveys yielding quantitative data. Two were qualitative studies. There was consistent evidence for SLPs in the USA and Canada experiencing satisfaction in their jobs. Facet analysis revealed six contributory themes, three of which were clearly associated with well-being: workload/caseload size, professional support, and salary. The contribution of job control (autonomy), length of time in practice and work setting was inconclusive. Evidence for stress and dissatisfaction leading to workforce attrition was found. Conclusion: Job satisfaction, stress, and burnout were found to be associated with various occupational features, including elements of demand, support and reward. No previous studies have investigated the interaction between different elements of a job, which might boost satisfaction or ameliorate stress in SLPs. This is the first review using a systematic approach to focus on well-being, satisfaction, stress and burnout in SLPs and suggests more work needs to be done to help identify and improve the well-being of the workforce

Supersymmetric solutions of PT-/non-PT-symmetric and non-Hermitian Screened Coulomb potential via Hamiltonian hierarchy inspired variational method

The supersymmetric solutions of PT-symmetric and Hermitian/non-Hermitian forms of quantum systems are obtained by solving the Schrodinger equation for the Exponential-Cosine Screened Coulomb potential. The Hamiltonian hierarchy inspired variational method is used to obtain the approximate energy eigenvalues and corresponding wave functions.Comment: 13 page

Energy-Momentum Tensor of Particles Created in an Expanding Universe

We present a general formulation of the time-dependent initial value problem for a quantum scalar field of arbitrary mass and curvature coupling in a FRW cosmological model. We introduce an adiabatic number basis which has the virtue that the divergent parts of the quantum expectation value of the energy-momentum tensor are isolated in the vacuum piece of , and may be removed using adiabatic subtraction. The resulting renormalized is conserved, independent of the cutoff, and has a physically transparent, quasiclassical form in terms of the average number of created adiabatic `particles'. By analyzing the evolution of the adiabatic particle number in de Sitter spacetime we exhibit the time structure of the particle creation process, which can be understood in terms of the time at which different momentum scales enter the horizon. A numerical scheme to compute as a function of time with arbitrary adiabatic initial states (not necessarily de Sitter invariant) is described. For minimally coupled, massless fields, at late times the renormalized goes asymptotically to the de Sitter invariant state previously found by Allen and Folacci, and not to the zero mass limit of the Bunch-Davies vacuum. If the mass m and the curvature coupling xi differ from zero, but satisfy m^2+xi R=0, the energy density and pressure of the scalar field grow linearly in cosmic time demonstrating that, at least in this case, backreaction effects become significant and cannot be neglected in de Sitter spacetime.Comment: 28 pages, Revtex, 11 embedded .ps figure

Bessel Process and Conformal Quantum Mechanics

Different aspects of the connection between the Bessel process and the conformal quantum mechanics (CQM) are discussed. The meaning of the possible generalizations of both models is investigated with respect to the other model, including self adjoint extension of the CQM. Some other generalizations such as the Bessel process in the wide sense and radial Ornstein- Uhlenbeck process are discussed with respect to the underlying conformal group structure.Comment: 28 Page

How does the electromagnetic field couple to gravity, in particular to metric, nonmetricity, torsion, and curvature?

The coupling of the electromagnetic field to gravity is an age-old problem. Presently, there is a resurgence of interest in it, mainly for two reasons: (i) Experimental investigations are under way with ever increasing precision, be it in the laboratory or by observing outer space. (ii) One desires to test out alternatives to Einstein's gravitational theory, in particular those of a gauge-theoretical nature, like Einstein-Cartan theory or metric-affine gravity. A clean discussion requires a reflection on the foundations of electrodynamics. If one bases electrodynamics on the conservation laws of electric charge and magnetic flux, one finds Maxwell's equations expressed in terms of the excitation H=(D,H) and the field strength F=(E,B) without any intervention of the metric or the linear connection of spacetime. In other words, there is still no coupling to gravity. Only the constitutive law H= functional(F) mediates such a coupling. We discuss the different ways of how metric, nonmetricity, torsion, and curvature can come into play here. Along the way, we touch on non-local laws (Mashhoon), non-linear ones (Born-Infeld, Heisenberg-Euler, Plebanski), linear ones, including the Abelian axion (Ni), and find a method for deriving the metric from linear electrodynamics (Toupin, Schoenberg). Finally, we discuss possible non-minimal coupling schemes.Comment: Latex2e, 26 pages. Contribution to "Testing Relativistic Gravity in Space: Gyroscopes, Clocks, Interferometers ...", Proceedings of the 220th Heraeus-Seminar, 22 - 27 August 1999 in Bad Honnef, C. Laemmerzahl et al. (eds.). Springer, Berlin (2000) to be published (Revised version uses Springer Latex macros; Sec. 6 substantially rewritten; appendices removed; the list of references updated