An experimental and theoretical investigation of plane-stress fracture of 2024-T351 aluminum alloy

Plane-stress fracture behavior of precracked aluminum alloy

Confidentiality and surveillance challenges for psychologists working in men’s football academies in England

We examine challenges to confidentiality experienced by sports psychologists in men’s English football academies. Sixteen psychologists, six women, and ten men working in English football academies participated in two semi-structured interviews. We carried out a reflexive thematic analysis after each round of interviews and developed two themes: (1) challenges to client-psychologist confidentiality; (2) a context of normalized surveillance. First, participants explained that several staff members (e.g., coaches, managers, and support staff) would use covert and subtle ways to make psychologists break confidentiality. This included trying to get the psychologist to “slip up.” Second, the football academy context was characterized by widespread surveillance of players. It was evident that it is common practice for clubs to gather objective and self-report data creating extreme transparency in the young people’s lives. We also propose two research-based solutions allowing psychologists to handle these issues

Dynamics of positive- and negative-mass solitons in optical lattices and inverted traps

We study the dynamics of one-dimensional solitons in the attractive and repulsive Bose-Einstein condensates (BECs) loaded into an optical lattice (OL), which is combined with an external parabolic potential. First, we demonstrate analytically that, in the repulsive BEC, where the soliton is of the gap type, its effective mass is \emph{negative}. This gives rise to a prediction for the experiment: such a soliton cannot be not held by the usual parabolic trap, but it can be captured (performing harmonic oscillations) by an anti-trapping inverted parabolic potential. We also study the motion of the soliton a in long system, concluding that, in the cases of both the positive and negative mass, it moves freely, provided that its amplitude is below a certain critical value; above it, the soliton's velocity decreases due to the interaction with the OL. At a late stage, the damped motion becomes chaotic. We also investigate the evolution of a two-soliton pulse in the attractive model. The pulse generates a persistent breather, if its amplitude is not too large; otherwise, fusion into a single fundamental soliton takes place. Collisions between two solitons captured in the parabolic trap or anti-trap are considered too. Depending on their amplitudes and phase difference, the solitons either perform stable oscillations, colliding indefinitely many times, or merge into a single soliton. Effects reported in this work for BECs can also be formulated for optical solitons in nonlinear photonic crystals. In particular, the capture of the negative-mass soliton in the anti-trap implies that a bright optical soliton in a self-defocusing medium with a periodic structure of the refractive index may be stable in an anti-waveguide.Comment: 22pages, 9 figures, submitted to Journal of Physics

Confidentiality and surveillance challenges for psychologists working in men’s football academies in England

We examine challenges to confidentiality experienced by sports psychologists in men’s English football academies. Sixteen psychologists, six women, and ten men working in English football academies participated in two semi-structured interviews. We carried out a reflexive thematic analysis after each round of interviews and developed two themes: (1) challenges to client-psychologist confidentiality; (2) a context of normalized surveillance. First, participants explained that several staff members (e.g., coaches, managers, and support staff) would use covert and subtle ways to make psychologists break confidentiality. This included trying to get the psychologist to “slip up.” Second, the football academy context was characterized by widespread surveillance of players. It was evident that it is common practice for clubs to gather objective and self-report data creating extreme transparency in the young people’s lives. We also propose two research-based solutions allowing psychologists to handle these issues

Episodic vertical nutrient fluxes and nearshore phytoplankton blooms

Abstract Three distinct phytoplankton blooms lasting 4-9 d were observed in approximately 15-m water depth near Huntington Beach, California, between June and October of 2006. Each bloom was preceded by a vertical NO 3 flux event 6-10 d earlier. NO 3 concentrations were estimated using a temperature proxy that was verified by comparison with the limited NO 3 observations. The lower-water-column vertical NO 3 flux from vertical advection was inferred from observed vertical isotherm displacement. Turbulent vertical eddy diffusivity was parameterized based on the observed background (, 0.3 cycles h 21 ) stratification and vertical shear in the horizontal currents. The first vertical nitrate flux event in June contained both advective and turbulent fluxes, whereas the later two events were primarily turbulent, driven by shear in the lower part of the water column. The correlation between the NO 3 flux and the observed chlorophyll a (Chl a) was maximum (r 2 5 0.40) with an 8-d lag. A simple nitrate-phytoplankton model using a linear uptake function and driven with the NO 3 flux captured the timing, magnitude, and duration of the three Chl a blooms (skill 5 0.61) using optimal net growth rate parameters that were within the expected range. Vertical and horizontal advection of Chl a past the measurement site were too small to explain the observed Chl a increases during the blooms. The vertical NO 3 flux was a primary control on the growth events, and estimation of both the advective (upwelled) and turbulent fluxes is necessary to best predict these episodic blooms

Solitons in one-dimensional nonlinear Schr\"{o}dinger lattices with a local inhomogeneity

In this paper we analyze the existence, stability, dynamical formation and mobility properties of localized solutions in a one-dimensional system described by the discrete nonlinear Schr\"{o}dinger equation with a linear point defect. We consider both attractive and repulsive defects in a focusing lattice. Among our main findings are: a) the destabilization of the on--site mode centered at the defect in the repulsive case; b) the disappearance of localized modes in the vicinity of the defect due to saddle-node bifurcations for sufficiently strong defects of either type; c) the decrease of the amplitude formation threshold for attractive and its increase for repulsive defects; and d) the detailed elucidation as a function of initial speed and defect strength of the different regimes (trapping, trapping and reflection, pure reflection and pure transmission) of interaction of a moving localized mode with the defect.Comment: 12 pages, 10 figure

Energy funneling in a bent chain of Morse oscillators with long-range coupling

A bent chain of coupled Morse oscillators with long-range dispersive interaction is considered. Moving localized excitations may be trapped in the bending region. Thus chain geometry acts like an impurity. An energy funneling effect is observed in the case of random initial conditions.Comment: 6 pages, 12 figures. Submitted to Physical Review E, Oct. 13, 200

Viable tax constitutions

Taxation is only sustainable if the general public complies with it. This observation is uncontroversial with tax practitioners but has been ignored by the public finance tradition, which has interpreted tax constitutions as binding contracts by which the power to tax is irretrievably conferred by individuals to government, which can then levy any tax it chooses. However, in the absence of an outside party enforcing contracts between members of a group, no arrangement within groups can be considered to be a binding contract, and therefore the power of tax must be sanctioned by individuals on an ongoing basis. In this paper we offer, for the first time, a theoretical analysis of this fundamental compliance problem associated with taxation, obtaining predictions that in some cases point to a re-interptretation of the theoretical constructions of the public finance tradition while in others call them into question