2,638 research outputs found
An evaluation of the nomina for death adders (Acanthophis Daudin, 1803) proposed by Wells & Wellington (1985), and confirmation of A. cryptamydros Maddock et al., 2015 as the valid name for the Kimberley death adder
FIGURE 1. The four death adder species, genus Acanthophis, whose valid nomina we discuss herein. (A) A. cryptamydros Maddock et al., 2015 from the Mueller Ranges, ca. 110 km southwest of Halls Creek, Western Australia. (B) A. pyrrhus Boulenger, 1898 from 40 km south of Port Hedland, Western Australia. (C) A. hawkei Wells & Wellington, 1985 from the Barkly Tableland, Northern Territory, Australia. (D) A. antarcticus (Shaw & Nodder, 1802) from Canning Dam, near Ashendon, Western Australia. Photos by Ray Lloyd (A, B, D) and Tom Parkin (C).Published as part of Ellis, Ryan J., Kaiser, Hinrich, Maddock, Simon T., Doughty, Paul & WĂĽster, Wolfgang, 2021, An evaluation of the nomina for death adders (Acanthophis Daudin, 1803) proposed by Wells & Wellington (1985), and confirmation of A. cryptamydros Maddock et al., 2015 as the valid name for the Kimberley death adder, pp. 161-172 in Zootaxa 4995 (1) on page 167, DOI: 10.11646/zootaxa.4995.1.9, http://zenodo.org/record/504390
The Impact of Depression on Patient Outcomes in Hip Arthroscopic Surgery.
Background: Mental health impairments have been shown to negatively affect preoperative self-reported function in patients with various musculoskeletal disorders, including those with femoroacetabular impingement.
Hypothesis: Those with symptoms of depression will have lower self-reported function, more pain, and less satisfaction on initial assessment and at 2-year follow-up than those without symptoms of depression.
Study Design: Cohort study; Level of evidence, 3.
Methods: Patients who were enrolled in a multicenter hip arthroscopic surgery registry and had 2-year outcome data available were included in the study. Patients completed the 12-item International Hip Outcome Tool (iHOT-12), visual analog scale (VAS) for pain, and 12-item Short-Form Health Survey (SF-12) when consenting for surgery. At 2-year follow-up, patients were emailed the iHOT, the VAS, and a rating scale of surgical satisfaction. Initial SF-12 mental component summary (MCS) scores
Results: A total of 781 patients achieved the approximate 2-year milestone (mean follow-up, 735 ± 68 days), with 651 (83%) having 2-year outcome data available. There were 434 (67%) female and 217 (33%) male patients, with a mean age of 35.8 ± 13.0 years and a mean body mass index of 25.4 ± 8.8 kg/m
Conclusion: A large number of patients who underwent hip arthroscopic surgery presented with symptoms of depression, which negatively affected self-reported function, pain levels, and satisfaction on initial assessment and at 2-year follow-up. Surgeons who perform hip arthroscopic surgery may need to identify the symptoms of depression and be aware of the impact that depression can have on surgical outcomes
Quantum Cosmology of Kantowski-Sachs like Models
The Wheeler-DeWitt equation for a class of Kantowski-Sachs like models is
completely solved. The generalized models include the Kantowski-Sachs model
with cosmological constant and pressureless dust. Likewise contained is a
joined model which consists of a Kantowski-Sachs cylinder inserted between two
FRW half--spheres. The (second order) WKB approximation is exact for the wave
functions of the complete set and this facilitates the product structure of the
wave function for the joined model. In spite of the product structure the wave
function can not be interpreted as admitting no correlations between the
different regions. This problem is due to the joining procedure and may
therefore be present for all joined models. Finally, the {s}ymmetric {i}nitial
{c}ondition (SIC) for the wave function is analyzed and compared with the ``no
bouindary'' condition. The consequences of the different boundary conditions
for the arrow of time are briefly mentioned.Comment: 21 pages, uses LaTeX2e, epsf.sty and float.sty, three figures (50
kb); changes: one figure added, new interpretation of quantizing procedure
for the joined model and many minor change
FRW Quantum Cosmology with a Generalized Chaplygin Gas
Cosmologies with a Chaplygin gas have recently been explored with the
objective of explaining the transition from a dust dominated epoch towards an
accelerating expansion stage. We consider the hypothesis that the transition to
the accelerated period involves a quantum mechanical process. Three physically
admissible cases are possible. In particular, we identify a minisuperspace
configuration with two Lorentzian sectors, separated by a classically forbidden
region. The Hartle-Hawking and Vilenkin wave functions are computed, together
with the transition amplitudes towards the accelerating epoch. Furthermore, it
is found that for specific initial conditions, the parameters characterizing
the generalized Chaplygin gas become related through an expression involving an
integer . We also introduce a phenomenological association between some
brane-world scenarios and a FRW minisuperspace cosmology with a generalized
Chaplygin gas. The aim is to promote a discussion and subsequent research on
the quantum creation of brane cosmologies from such a perspective. Results
suggest that the brane tension would become related with generalized Chaplygin
gas parameters through another expression involving an integer.Comment: 13 pages, 3 figures, RevTeX
Anisotropic 'hairs' in string cosmology
In this letter we investigate whether the isotropy problem is naturally
solved in inflationary cosmologies inspired by string theory, so called
pre-big-bang cosmologies. We find that, in contrast to what happens in the more
common 'potential inflation' models, initial anisotropies do not decay during
pre-big-bang inflation.Comment: 4 pages, 1 figur
Self-similar Bianchi models: I. Class A models
We present a study of Bianchi class A tilted cosmological models admitting a
proper homothetic vector field together with the restrictions, both at the
geometrical and dynamical level, imposed by the existence of the simply
transitive similarity group. The general solution of the symmetry equations and
the form of the homothetic vector field are given in terms of a set of
arbitrary integration constants. We apply the geometrical results for tilted
perfect fluids sources and give the general Bianchi II self-similar solution
and the form of the similarity vector field. In addition we show that
self-similar perfect fluid Bianchi VII models and irrotational Bianchi
VI models do not exist.Comment: 14 pages, Latex; to appear in Classical and Quantum Gravit
On the Significance of the Weyl Curvature in a Relativistic Cosmological Model
The Weyl curvature includes the Newtonian field and an additional field, the
so-called anti-Newtonian. In this paper, we use the Bianchi and Ricci
identities to provide a set of constraints and propagations for the Weyl
fields. The temporal evolutions of propagations manifest explicit solutions of
gravitational waves. We see that models with purely Newtonian field are
inconsistent with relativistic models and obstruct sounding solutions.
Therefore, both fields are necessary for the nonlocal nature and radiative
solutions of gravitation.Comment: 15 pages, incorporating proof correction
Lithium abundances of halo dwarfs based on excitation temperature. I. LTE
The discovery of the Spite plateau in the abundances of 7Li for metal-poor
stars led to the determination of an observationally deduced primordial lithium
abundance. However, after the success of the Wilkinson Microwave Anisotropy
Probe (WMAP) in determining the baryon density, OmegaBh^2, there was a
discrepancy between observationally determined and theoretically determined
abundances in the case of 7Li. One of the most important uncertain factors in
the calculation of the stellar 7Li abundance is the effective temperature,
Teff. We use sixteen metal-poor halo dwarfs to calculate new Teff values using
the excitation energy method. With this temperature scale we then calculate new
Li abundances for this group of stars in an attempt to resolve the 7Li
discrepancy. Using high signal-to-noise (S/N ~ 100) spectra of 16 metal-poor
halo dwarfs, obtained with the UCLES spectrograph on the AAT, measurements of
equivalent widths from a set of unblended FeI lines are made. These equivalent
widths are then used to calculate new Teff values with the use of the single
line radiative transfer program WIDTH6, where we have constrained the gravity
using either theoretical isochrones or the Hipparcos parallax, rather than the
ionization balance. The lithium abundances of the stars are calculated with
these temperatures. The physical parameters are derived for the 16 programme
stars, and two standards. These include Teff, log g, [Fe/H], microturbulence
and 7Li abundances. A comparison between the temperature scale of this work and
those adopted by others has been undertaken. We find good consistency with the
temperatures derived from the Halpha line by Asplund et al. (2006), but not
with the hotter scale of Melendez & Ramirez (2004).Comment: 13 pages, 9 figure
Bianchi VIII Empty Futures
Using a qualitative analysis based on the Hamiltonian formalism and the
orthonormal frame representation we investigate whether the chaotic behaviour
which occurs close to the initial singularity is still present in the far
future of Bianchi VIII models. We describe some features of the vacuum Bianchi
VIII models at late times which might be relevant for studying the nature of
the future asymptote of the general vacuum inhomogeneous solution to the
Einstein field equations.Comment: 22 pages, no figures, Latex fil
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