Talk in activity during young children’s use of digital technologies at home

This article establishes ways that family members engage and disengage in talk so as to manage their individual activity with mobile devices and accomplish interaction with each other.AbstractInternet-connected tablets and smart phones are being used increasingly by young children. Little is known, however, about their social interactions with family members when engaged with these technologies. This article examines video-recorded interactions between a father and his two young children, one aged 18 months using an iPhone and one aged three years accessing an iPad. Drawing on Ethnomethodology and Conversation Analysis, analysis establishes ways the family members engage and disengage in talk so as to manage their individual activity with mobile devices and accomplish interaction with each other. Findings are relevant for understanding children’s everyday practices with mobile technologies.Authored by Susan Danby, Christina Davidson, Maryanne Theobald, Brooke Scriven, Charlotte Cobb-Moore, Sandra Houen, Sandra Grant, Lisa M. Given, and Karen Thorpe

Ab initio R-matrix calculations of e+-molecule scattering

The adaptation of the molecular R-matrix method, originally developed for electron-molecule collision studies, to positron scattering is discussed. Ab initio R-matrix calculations are presented for collisions of low energy positrons with a number of diatomic systems including H2, HF and N2. Differential elastic cross sections for positron-H2 show a minimum at about 45 deg for collision energies between 0.3 and 0.5 Ryd. The calculations predict a bound state of positronHF. Calculations on inelastic processes in N2 and O2 are also discussed

How terrestrial planets traverse spin-orbit resonances: A camel goes through a needle's eye

The dynamical evolution of terrestrial planets resembling Mercury in the vicinity of spin-orbit resonances is investigated using comprehensive harmonic expansions of the tidal torque taking into account the frequency-dependent quality factors and Love numbers. The torque equations are integrated numerically with a small step in time, includng the oscillating triaxial torque components but neglecting the layered structure of the planet and assuming a zero obliquity. We find that a Mercury-like planet with its current value of orbital eccentricity (0.2056) is always captured in the 3:2 resonance. The probability of capture in the higher 2:1 resonance is approximately 0.23. These results are confirmed by a semi-analytical estimation of capture probabilities as functions of eccentricity for both prograde and retrograde evolution of spin rate. As follows from analysis of equilibrium torques, entrapment in the 3:2 resonance is inevitable at eccentricities between 0.2 and 0.41. Considering the phase space parameters at the times of periastron, the range of spin rates and phase angles, for which an immediate resonance passage is triggered, is very narrow, and yet, a planet like Mercury rarely fails to align itself into this state of unstable equilibrium before it traverses the 2:1 resonance.Comment: 10 figures. Fig. 8 may be corrupted when printed on some printers but shows fine in the PDF file. Submitted in ApJ v. 2: the probabilities of capture of Mercury in 2:1 resonance are re-evaluated; a general formula for capture probability derived. v3: accepted in ApJ under a different title: Conditions of passage and entrapment of terrestrial planets in spin-orbit resonance

Dust Grain Orbital Behavior Around Ceres

Many asteroids show indications they have undergone impacts with meteoroid particles having radii between 0.01 m and 1 m. During such impacts, small dust grains will be ejected at the impact site. The possibility of these dust grains (with radii greater than 2.2x10-6 m) forming a halo around a spherical asteroid (such as Ceres) is investigated using standard numerical integration techniques. The orbital elements, positions, and velocities are determined for particles with varying radii taking into account both the influence of gravity, radiation pressure, and the interplanetary magnetic field (for charged particles). Under the influence of these forces it is found that dust grains (under the appropriate conditions) can be injected into orbits with lifetimes in excess of one year. The lifetime of the orbits is shown to be highly dependent on the location of the ejection point as well as the angle between the surface normal and the ejection path. It is also shown that only particles ejected within 10 degrees relative to the surface tangential survive more than a few hours and that the longest-lived particles originate along a line perpendicular to the Ceres-Sun line.Comment: 8 pages, Presented at COSPAR '0

Close coupling calculations of dimer energy levels

The aim of this thesis is to calculate the bound state energies of molecular dimers. The problem is formulated for a system consisting of any two ${^l\sum}$ diatomic molecules, treated as rigid rotors. Simplifications which arise from symmetry considerations are fully discussed. The de Vogelaere and R-matrix propagator algorithms have been used to solve the resulting systems of coupled second order differential equations. Their numerical convergence properties are compared in test calculations on the Ar-HCl system. The above methods are used to calculate the bound state energies of $H_{2}-H_{2}$, using four separate ab initio potentials. The CI potential of Meyer, Schaefer and Liu (designated "M80") is found to give the best agreement with spectroscopic measurements, though a small shift in the position of the repulsive wall is indicated. The M80 potential is then used in the remaining calculations; these include the evaluation of the energies of resonances and bound states lying above the dissociation limit of the dimer, corresponding to rotationally excited $H_{2}$. The results of these calculations are used to assess the validity of approximations made in the proposed identification of $H_{2}$-$H_{2}$ features in the far infrared spectra of the Jovian atmosphere. The Born-Oppenheimer approximation permits the use of the M80 potential to calculate the bound states and resonances of $D_{2}$-$D_{2}$. That some of these resonances have dual Feshbach/shape character is noted. The dimer structure, accompanying the observed near infrared $S_{1}$(0) and $Q_{1}$(0) + $S_{o}$(0) spectra in ortho-deuterium, is modelled by treating the two $D_{2}$ molecules as distinguishable rigid rotors. We conclude that the experiments provide evidence both for rotational splitting of the levels and for internal rotational predissociation. Alternative line assignments to those hitherto made are also suggested. We end with a general discussion in which suggestions for future work are made

“So yes, you’ve battered me. Yes, you’ve hurt me. But you know what? I’m not giving up on you”: The experiences of Teaching Assistants supporting excluded children in Alternative Provisions

Alternative Provisions (APs) are under increasing pressure, the result of rising exclusions, increasing accountability measures and difficulties with recruitment and retention of educational staff. Described as challenging and emotionally demanding environments, staff within these settings are required to manage a range of diverse needs and complex behaviours. Whilst the significance of their role is emphasised from the level of the government to the Child and Young Person (CYP), a paucity of research exists exploring the experiences of those working within APs, particularly in relation to Teaching Assistants (TAs). Addressing a gap in the literature base, the current study aimed to explore the experiences of TAs supporting excluded CYP within APs. Semi-structured interviews were conducted with six TAs supporting excluded CYP within APs. Using an idiographic and interpretative method to explore lived experiences, the study adopted an Interpretative Phenomenological Analysis (IPA) approach, resulting in the development of five overarching themes: ‘Relationships: a complex landscape’, ‘A juggling act: behaviour, need and strength from the team’, ‘A rocky road: highs, lows and a journey of development’, ‘Battles, clashes and superiority’ and ‘The journey towards a future’. Relational connections and disconnections co-existed alongside the strains of managing challenging behaviour and diversity of need, with TAs experiencing a range of emotive responses and personal change. Adding further complexity, were battles with mainstream schools and parents, with TAs striving to compensate, empower and promote positive change. Findings are discussed in relation to previous literature and psychological theory, with implications for AP settings, school staff and Educational Psychology practice

Resonance Behavior and Partial Averaging in a Three-Body System with Gravitational Radiation Damping

In a previous investigation, a model of three-body motion was developed which included the effects of gravitational radiation reaction. The aim was to describe the motion of a relativistic binary pulsar that is perturbed by a third mass and look for resonances between the binary and third mass orbits. Numerical integration of an equation of relative motion that approximates the binary gives evidence of such resonances. These $(m:n)$ resonances are defined for the present purposes by the resonance condition, $m\omega=2n\Omega$, where $m$ and $n$ are relatively prime integers and $\omega$ and $\Omega$ are the angular frequencies of the binary orbit and third mass orbit, respectively. The resonance condition consequently fixes a value for the semimajor axis $a$ of the binary orbit for the duration of the resonance because of the Kepler relationship $\omega=a^{-3/2}$. This paper outlines a method of averaging developed by Chicone, Mashhoon, and Retzloff which renders a nonlinear system that undergoes resonance capture into a mathematically amenable form. This method is applied to the present system and one arrives at an analytical solution that describes the average motion during resonance. Furthermore, prominent features of the full nonlinear system, such as the frequency of oscillation and antidamping, accord with their analytically derived formulae.Comment: 19 pages, 4 Postscript figure