Close encounters of a rotating star with planets in parabolic orbits of varying inclination and the formation of Hot Jupiters

(abbreviated) We extend the theory of close encounters of a planet on a parabolic orbit with a star to include the effects of tides induced on the central rotating star. Orbits with arbitrary inclination to the stellar rotation axis are considered. We obtain results both from an analytic treatment and numerical one that are in satisfactory agreement. These results are applied to the initial phase of the tidal circularisation problem. We find that both tides induced in the star and planet can lead to a significant decrease of the orbital semi-major axis for orbits having periastron distances smaller than 5-6 stellar radii (corresponding to periods $\sim 4-5$ days after the circularisation has been completed) with tides in the star being much stronger for retrograde orbits compared to prograde orbits. We use the simple Skumanich law for the stellar rotation with its rotational period equal to one month at the age of 5Gyr. The strength of tidal interactions is characterised by circularisation time scale, $t_{ev}$ defined as a time scale of evolution of the planet's semi-major axis due to tides considered as a function of orbital period $P_{obs}$ after the process of tidal circularisation has been completed. We find that the ratio of the initial circularisation time scales corresponding to prograde and retrograde orbits is of order 1.5-2 for a planet of one Jupiter mass and $P_{obs}\sim$ four days. It grows with the mass of the planet, being of order five for a five Jupiter mass planet with the same $P_{orb}$. Thus, the effect of stellar rotation may provide a bias in the formation of planetary systems having planets on close orbits around their host stars, as a consequence of planet-planet scattering, favouring systems with retrograde orbits. The results may also be applied to the problem of tidal capture of stars in young stellar clusters.Comment: to be published in Celestial Mechanics and Dynamical Astronom

Doings with the land and sea: Decolonising geographies, Indigeneity, and enacting place-agency

Indigenous and decolonising geographies should be unsettling and challenging to the ontological foundations of the geographical discipline. Yet despite many scholars recognising and arguing for the need for these perspectives, Indigeneity remains marginal and Indigenous knowledge has been denied academic legitimacy within geography. Using ‘doings’ as an active, emergent, and evolving praxis, this paper examines how we can do Indigenous and settler geographies better. It illustrates how knowledge, emotions, feelings and intuition only come into being through the doings of the body with other bodies, places, and objects, including non-humans. Action and thought are indistinguishable, feeling is knowing, and the world becomes known through doing and movement. In these doings, place – particularly the land and sea – is an active agent in the making of beings and knowledge. By focusing on active doings in place, and acknowledging the temporalities of Indigenous ontologies, geographers are better able to support political and everyday struggles, situate our work in relation to colonialism, recognise and value everyday practices of resurgence, and spend time building relationships. ‘Doing’ geography differently would decentre academics as the source of knowledge production, employ more diverse voices in our teaching and provide embodied and material resistance to colonialism and neoliberal capitalism

Energy Issues in Canada

During the Fall Semester, 1977 the Department of Geography and ContinuingStudies, Simon Fraser University presented a public lecture series, \u27EnergyIssues in Canada.\u27 The series was intended as a forum for public debate, with six lectures presented by experts playing significant roles in today\u27s energydecisions. The lectures addressed a range of topics, including energy supplyand demand forecasts, the problems and potential of fossil fuels, the opportunitiesoffered by renewable energy sources, and energy conservation. Thefinal lecture in the series focussed upon current federal energy policy.In response to the interest shown in the series, we decided to issue avolume of proceedings in order that the infonnation and viewpoints presentedin the lectures could reach a wider audience. The following papers arearranged in order of presentation. Unfortunately it has not been possible toinclude the discussion of renewable energy sources and technologies given inthe fifth lecture of the series. Most authors address the Canadian and provincial energy scene in thecontext of world trends: the price increases introduced by OPEC (Organisationof Petroleum Exporting Countries) in 1973, and the looming gap between worlddemand and supply of petroleum which will result in a deficit sometime duringthe 1980s. These trends have undermined our sense of energy security, forceda reexamination of present energy use patterns, and given support to theidea of energy conservation

Hydration and Ordering of Lamellar Block Copolymer Films under Controlled Water Vapor

Amphiphilic block copolymers within a range of volume fraction spontaneously form vesicles in aqueous solution, where a water core is enclosed by a polymer bilayer. Thin-film rehydration is a method used to produce vesicles routinely; a thin film is immersed in water, the film swells, and vesicles are formed which bleb off from the film surface. We have studied the early stages of hydration for PEO–PBO block copolymer thin films under controlled water vapor conditions to understand this formation mechanism and so enable more efficient ways to encapsulate molecules using this method. Neutron and X-ray measurements show that the initial film exhibits weakly ordered structure with isotropic parallel and vertical orientation; the films initially swell and maintain the same orientation. At a critical point the layer swells rapidly and makes highly ordered lamellae structure at the same time. The lamellae are almost exclusively oriented parallel to the substrate and swell with increasing water absorption

Phenomenological Determination of the Beauty Meson Decay Parameter fBf_B and the CP-Violating Angle δ\delta

We fit the ${\cal CKM}$-matrix to all recent data with the following free parameters: three mixing angles, the CP-violating angle $\delta$ in the Maiani parametrisation, the top quark mass $m_t$, and the product f_B{\cal B}_{\B}^{1/2}, where $f_B$ is the $B$-meson decay parameter and {\cal B}_{\B} is the bag parameter. Our fits span a contiguous region in the (f_B{\cal B}_{\B}^{1/2},\ \cos\delta)--plane, limited by 0.117\lsim f_B{\cal B}_{\B}^{1/2}/{\rm GeV}\lsim 0.231 and --0.95 \lsim $\cos\delta$ \lsim 0.70. The parameters f_B{\cal B}_{\B}^{1/2} and $\cos\delta$ are strongly positively correlated.Comment: 9 pages + 1 figure available upon request, HU-TFT-94-3

The impact of self-efficacy, expectations, and readiness on hearing aid outcomes

Objective: To examine the impact of self-efficacy and expectations for hearing aids, and readiness to improve hearing, on hearing aid outcome measures in first-time adult hearing aid users Design: A prospective, single centre design. Predictor variables measured at the hearing assessment included measures of self-efficacy, expectations and readiness to improve hearing. Outcome measures obtained at sixweek follow-up were the Glasgow Hearing Aid Benefit Profile and Satisfaction with Amplification in Daily Life. Study sample: A sample of 30 first-time adult hearing aid users were recruited through a public-sector funded audiology clinic. Results: When measured prior to hearing aid fitting, self-efficacy for hearing aids predicted satisfaction with hearing aids but was not related to other hearing aid outcomes. Expectations of hearing aids, in particular positive expectations, and readiness to improve hearing predicted outcomes for hearing aid satisfaction and benefit, although not hearing aid use. Hearing sensitivity was not correlated with hearing aid outcomes. Conclusions: These results suggest that assessment of expectations of hearing aids, and readiness to improve hearing, may be useful to help identify individuals attending audiology clinics who would most likely benefit from hearing aid provision

Phenomenological glass model for vibratory granular compaction

A model for weakly excited granular media is derived by combining the free volume argument of Nowak et al. [Phys. Rev. E 57, 1971 (1998)] and the phenomenological model for supercooled liquids of Adam and Gibbs [J. Chem. Phys. 43, 139 (1965)]. This is made possible by relating the granular excitation parameter \Gamma, defined as the peak acceleration of the driving pulse scaled by gravity, to a temperature-like parameter \eta(\Gamma). The resulting master equation is formally identical to that of Bouchaud's trap model for glasses [J. Phys. I 2, 1705 (1992)]. Analytic and simulation results are shown to compare favourably with a range of known experimental behaviour. This includes the logarithmic densification and power spectrum of fluctuations under constant \eta, the annealing curve when \eta is varied cyclically in time, and memory effects observed for a discontinuous shift in \eta. Finally, we discuss the physical interpretation of the model parameters and suggest further experiments for this class of systems.Comment: 2 references added; some figure labels tweaked. To appear in PR

Glassy dynamics in granular compaction: sand on random graphs

We discuss the use of a ferromagnetic spin model on a random graph to model granular compaction. A multi-spin interaction is used to capture the competition between local and global satisfaction of constraints characteristic for geometric frustration. We define an athermal dynamics designed to model repeated taps of a given strength. Amplitude cycling and the effect of permanently constraining a subset of the spins at a given amplitude is discussed. Finally we check the validity of Edwards' hypothesis for the athermal tapping dynamics.Comment: 13 pages Revtex, minor changes, to appear in PR