637 research outputs found
Who the hell was that? Stories, bodies and actions in the world
This article explores a two-way relationship between stories and the experiential actions of bodies in the world. Through an autoethnographic approach, the article presents a series of interlinked story fragments in an effort to show and evoke a feel for the ways in which stories, bodies, and actions influence and shape each other over time. It offers some reflections on the experiences the stories portray from the perspective of a social constructionist conception of narrative theory and suggest that while stories exert a powerful influence on the actions of our bodies, our bodies intrude on or ‘talk back’ to this process because bodies have an existence beyond stories
Origin and Dynamical Evolution of Neptune Trojans - II: Long Term Evolution
We present results examining the fate of the Trojan clouds produced in our
previous work. We find that the stability of Neptunian Trojans seems to be
strongly correlated to their initial post-migration orbital elements, with
those objects that survive as Trojans for billions of years displaying
negligible orbital evolution. The great majority of these survivors began the
integrations with small eccentricities (e < 0.2) and small libration amplitudes
(A < 30 - 40{\deg}). The survival rate of "pre-formed" Neptunian Trojans (which
in general survived on dynamically cold orbits (e < 0.1, i < 5 - 10{\deg}))
varied between ~5 and 70%. By contrast, the survival rate of "captured" Trojans
(on final orbits spread across a larger region of e-i element space) were
markedly lower, ranging between 1 and 10% after 4 Gyr. Taken in concert with
our earlier work, we note that planetary formation scenarios which involve the
slow migration (a few tens of millions of years) of Neptune from an initial
planetary architecture that is both resonant and compact (aN < 18 AU) provide
the most promising fit of those we considered to the observed Trojan
population. In such scenarios, we find that the current day Trojan population
would number ~1% of that which was present at the end of the planet's
migration, with the bulk being sourced from captured, rather than pre-formed
objects. We note, however, that even those scenarios still fail to reproduce
the currently observed portion of the Neptune Trojan population moving on
orbits with e 20{\deg}. Dynamical integrations of the currently
observed Trojans show that five out of the seven are dynamically stable on 4
Gyr timescales, while 2001 QR322, exhibits significant dynamical instability.
The seventh Trojan object, 2008 LC18, has such large orbital uncertainties that
only future studies will be able to determine its stability.Comment: 24 pages, 6 figures, accepted for publication in MNRAS (The abstract
was shortened. Original version can be found in the pdf file
Negotiating sexuality and masculinity in school sport: An autoethnography
This autoethnography explores challenging and ethically sensitive issues around sexual orientation, sexual identity and masculinity in the context of school sport. Through storytelling, I aim to show how sometimes ambiguous encounters with heterosexism, homophobia and hegemonic masculinity through sport problematise identity development for young same-sex attracted males. By foregrounding personal embodied experience, I respond to an absence of stories of gay and bisexual experiences among males in physical education and school sport, in an effort to reduce a continuing sense of Otherness and difference regarding same-sex attracted males. I rely on the story itself to express the embodied forms of knowing that inhabit the experiences I describe, and resist a finalising interpretation of the story. Instead, I offer personal reflections on particular theoretical and methodological issues which relate to both the form and content of the story
The CORALIE survey for southern extra-solar planets XV. Discovery of two eccentric planets orbiting HD4113 and HD156846
We report the detection of two very eccentric planets orbiting HD4113 and
HD156846 with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss
telescope at La Silla. The first planet, HD4113b, has minimum mass of
, a period of days and an
eccentricity of . It orbits a metal rich G5V star at
AU which displays an additional radial velocity drift of 28 m s/yr
observed during 8 years. The combination of the radial-velocity data and the
non-detection of any main sequence stellar companion in our high contrast
images taken at the VLT with NACO/SDI, characterizes the companion as a
probable brown dwarf or as a faint white dwarf. The second planet, \object{HD
156846 b}, has minimum mass of M, a period
of days, an eccentricity of and is located
at AU from its parent star. HD156846 is a metal rich G0 dwarf and is
also the primary of a wide binary system ( AU, years). Its
stellar companion, \object{IDS 17147-1914 B}, is a M4 dwarf. The very high
eccentricities of both planets can be explained by Kozai oscillations induced
by the presence of a third object.Comment: 4 pages, 5 figures, A&A Letter accepte
Origin and Dynamical Evolution of Neptune Trojans - I: Formation and Planetary Migration
We present the results of detailed dynamical simulations of the effect of the
migration of the four giant planets on both the transport of pre-formed Neptune
Trojans, and the capture of new Trojans from a trans-Neptunian disk. We find
that scenarios involving the slow migration of Neptune over a large distance
(50Myr to migrate from 18.1AU to its current location) provide the best match
to the properties of the known Trojans. Scenarios with faster migration (5Myr),
and those in which Neptune migrates from 23.1AU to its current location, fail
to adequately reproduce the current day Trojan population. Scenarios which
avoid disruptive perturbation events between Uranus and Neptune fail to yield
any significant excitation of pre-formed Trojans (transported with efficiencies
between 30 and 98% whilst maintaining the dynamically cold nature of these
objects). Conversely, scenarios with periods of strong Uranus-Neptune
perturbation lead to the almost complete loss of such pre-formed objects. In
these cases, a small fraction (~0.15%) of these escaped objects are later
recaptured as Trojans prior to the end of migration, with a wide range of
eccentricities (<0.35) and inclinations (<40 deg). In all scenarios (including
those with such disruptive interaction between Uranus and Neptune) the capture
of objects from the trans-Neptunian disk (through which Neptune migrates) is
achieved with efficiencies between ~0.1 and ~1%. The captured Trojans display a
wide range of inclinations (<40 deg for slow migration, and <20 deg for rapid
migration) and eccentricities (<0.35), and we conclude that, given the vast
amount of material which undoubtedly formed beyond the orbit of Neptune, such
captured objects may be sufficient to explain the entire Neptune Trojan
population. (Shortened version)Comment: 25 pages, 6 figure
The frequency of planets in multiple systems
The frequency of planets in binaries is an important issue in the field of
extrasolar planet studies, because of its relevance in estimating of the global
planet population of our Galaxy and the clues it can give to our understanding
of planet formation and evolution. However, only preliminary estimates are
available in the literature. We analyze and compare the frequency of planets in
multiple systems to the frequency of planets orbiting single stars. We also try
to highlight possible connections between the frequency of planets and the
orbital parameters of the binaries (such as the periastron and mass ratio.) A
literature search was performed for binaries and multiple systems among the
stars of the sample with uniform planet detectability defined by Fischer &
Valenti (2005), and 202 of the 850 stars of the sample turned out to be
binaries, allowing a statistical comparison of the frequency of planets in
binaries and single stars and a study of the run of the planet frequency as a
function of the binary separation. We found that the global frequency of
planets in the binaries of the sample is not statistically different from that
of planets in single stars. Even conservatively taking the probable
incompleteness of binary detection in our sample into account, we estimate that
the frequency of planets in binaries can be no more than a factor of three
lower than that of planets in single stars. There is no significant dependence
of planet frequency on the binary separation, except for a lower value of
frequency for close binaries. However, this is probably not as low as required
to explain the presence of planets in close binaries only as the result of
modifications of the binary orbit after the planet formation
Cosmology From Random Multifield Potentials
We consider the statistical properties of vacua and inflationary trajectories
associated with a random multifield potential. Our underlying motivation is the
string landscape, but our calculations apply to general potentials. Using
random matrix theory, we analyze the Hessian matrices associated with the
extrema of this potential. These potentials generically have a vast number of
extrema. If the cross-couplings (off-diagonal terms) are of the same order as
the self-couplings (diagonal terms) we show that essentially all extrema are
saddles, and the number of minima is effectively zero. Avoiding this requires
the same separation of scales needed to ensure that Newton's constant is stable
against radiative corrections in a string landscape. Using the central limit
theorem we find that even if the number of extrema is enormous, the typical
distance between extrema is still substantial -- with challenging implications
for inflationary models that depend on the existence of a complicated path
inside the landscape.Comment: revtex, 3 figures, 10 pages v2 refs adde
The impact of mental illness on potentially preventable hospitalisations: a population-based cohort study
<p>Abstract</p> <p>Background</p> <p>Emerging evidence indicates an association between mental illness and poor quality of physical health care. To test this, we compared mental health clients (MHCs) with non-MHCs on potentially preventable hospitalisations (PPHs) as an indicator of the quality of primary care received.</p> <p>Methods</p> <p>Population-based retrospective cohort study of 139,208 MHCs and 294,180 matched non-MHCs in Western Australia from 1990 to 2006, using linked data from electoral roll registrations, mental health registry (MHR) records, hospital inpatient discharges and deaths. We used the electoral roll data as the sampling frame for both cohorts to enhance internal validity of the study, and the MHR to separate MHCs from non-MHCs. Rates of PPHs (overall and by PPH category and medical condition) were compared between MHCs, category of mental disorders and non-MHCs. Multivariate negative binomial regression analyses adjusted for socio-demographic factors, case mix and the year at the start of follow up due to dynamic nature of study cohorts.</p> <p>Results</p> <p>PPHs accounted for more than 10% of all hospital admissions in MHCs, with diabetes and its complications, adverse drug events (ADEs), chronic obstructive pulmonary disease (COPD), convulsions and epilepsy, and congestive heart failure being the most common causes. Compared with non-MHCs, MHCs with any mental disorders were more likely to experience a PPH than non-MHCs (overall adjusted rate ratio (ARR) 2.06, 95% confidence interval (CI) 2.03-2.09). ARRs of PPHs were highest for convulsions and epilepsy, nutritional deficiencies, COPD and ADEs. The ARR of a PPH was highest in MHCs with alcohol/drug disorders, affective psychoses, other psychoses and schizophrenia.</p> <p>Conclusions</p> <p>MHCs have a significantly higher rate of PPHs than non-MHCs. Improving primary and secondary prevention is warranted in MHCs, especially at the primary care level, despite there may be different thresholds for admission in people with established physical disease that is influenced by whether or not they have comorbid mental illness.</p
Benchmarking the power of amateur observatories for TTV exoplanets detection
This document is the Accepted Manuscript version of the following article: Roman v. Baluev, et al, ‘Benchmarking the power of amateur observatories for TTV exoplanets detection’, Monthly Notices of the Royal Astronomical Society, Vol. 450(3): 3101-3113, first published online 9 May 2015. The version of record is available at doi: https://doi.org/10.1093/mnras/stv788 © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We perform an analysis of ~80000 photometric measurements for the following 10 stars hosting transiting planets: WASP-2, -4, -5, -52, Kelt-1, CoRoT-2, XO-2, TrES-1, HD 189733, GJ 436. Our analysis includes mainly transit lightcurves from the Exoplanet Transit Database, public photometry from the literature, and some proprietary photometry privately supplied by other authors. Half of these lightcurves were obtained by amateurs. From this photometry we derive 306 transit timing measurements, as well as improved planetary transit parameters. Additionally, for 6 of these 10 stars we present a set of radial velocity measurements obtained from the spectra stored in the HARPS, HARPS-N, and SOPHIE archives using the HARPS-TERRA pipeline. Our analysis of these TTV and RV data did not reveal significant hints of additional orbiting bodies in almost all of the cases. In the WASP-4 case, we found hints of marginally significant TTV signals having amplitude 10-20 sec, although their parameters are model-dependent and uncertain, while radial velocities did not reveal statistically significant Doppler signals.Peer reviewe
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