4,137 research outputs found
Trash in the Courtroom: The Problem of Solid Waste Control Ordinances after \u3ci\u3eHuish Detergents, Inc. v. Warren County\u3c/i\u3e
Wall-liquid and wall-crystal interfacial free energies via thermodynamic integration: A molecular dynamics simulation study
A method is proposed to compute the interfacial free energy of a
Lennard-Jones system in contact with a structured wall by molecular dynamics
simulation. Both the bulk liquid and bulk face-centered-cubic crystal phase
along the (111) orientation are considered. Our approach is based on a
thermodynamic integration scheme where first the bulk Lennard-Jones system is
reversibly transformed to a state where it interacts with a structureless flat
wall. In a second step, the flat structureless wall is reversibly transformed
into an atomistic wall with crystalline structure. The dependence of the
interfacial free energy on various parameters such as the wall potential, the
density and orientation of the wall is investigated. The conditions are
indicated under which a Lennard-Jones crystal partially wets a flat wall.Comment: 15 pages, 11 figure
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Tibial Tubercle Osteotomy and Medial Patellofemoral Ligament Imbrication for Patellar Instability Due to Trochlear Dysplasia.
BackgroundThe treatment of patellar instability in the setting of trochlear dysplasia is challenging.Purpose/hypothesisThe purpose of this study was to evaluate outcomes for the treatment of recurrent patellar dislocations due to trochlear dysplasia using anteromedialization tibial tubercle osteotomy combined with medial patellofemoral ligament (MPFL) imbrication. We hypothesized that the treatment of patellar instability with tibial tubercle osteotomy and MPFL imbrication would result in improved patient satisfaction and decrease patellar instability events in patients with prior instability and trochlear dysplasia.Study designCase series; Level of evidence, 4.MethodsWe performed a retrospective analysis of patients who underwent MPFL imbrication and concomitant anteromedialization tibial tubercle osteotomy for recurrent patellofemoral instability at a single institution. The minimum follow-up was 1 year. Patient demographic information including age at the time of surgery, sex, body mass index (BMI), tibial tubercle-trochlear groove (TT-TG) distance, and grade of trochlear dysplasia was collected along with relevant operative data. Postoperatively, recurrent dislocation events as well as Knee injury and Osteoarthritis Outcome Score (KOOS), Western Ontario and McMaster Universities Osteoarthritis Index, and Kujala scores were collected, and satisfaction was ascertained by asking patients whether they would undergo the procedure again.ResultsA total of 37 knees from 31 patients (23 female) with a mean follow-up of 3.8 years (range, 1-8.9 years) were included. The mean patient age was 28.8 years (range, 14-45 years), the mean BMI was 24 kg/m2 (range, 20-38 kg/m2), and the mean preoperative TT-TG distance was 18.9 mm (range, 8.4-32.4 mm). Two knees were classified as low-grade trochlear dysplasia (Dejour A) and 35 as high-grade trochlear dysplasia (Dejour B-D). At final follow-up, patients reported mean KOOS subscale scores of 86.5 (Pain), 79.8 (Symptoms), 93.9 (Activities of Daily Living), 74.3 (Sports/Recreation), and 61.9 (Quality of Life), as well as a mean Kujala score of 81.3. Mean patient satisfaction was 8.3 of 10. The majority of knees (86.5%; 32/37) remained stable without recurrent instability after this procedure, while 13.5% (5 knees) suffered a recurrent dislocation, with 2 requiring revision surgery. Eight knees (21.6%) underwent subsequent hardware removal.ConclusionAnteromedialization tibial tubercle osteotomy with MPFL imbrication can improve recurrent patellofemoral instability and provide significant clinical benefit to patients with trochlear dysplasia
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New methods for digital modeling of historic sites
We discuss new methods for building 3D models of historic sites. Our algorithm automatically computes pairwise registrations between individual scans, builds a topological graph, and places the scans in the same frame of reference
Airway expression of Transient Receptor Potential (TRP) Vanniloid-1 and Ankyrin-1 channels is not increased in patients with Idiopathic Pulmonary Fibrosis
Dry cough is a common symptom described in patients with Idiopathic Pulmonary Fibrosis
(IPF) and impairs quality of life. The exact mechanisms causing cough in IPF remain unclear,
however evidence suggests altered cough neurophysiology and sensitisation plays a role; IPF
patients have an enhanced cough reflex sensitivity to inhaled capsaicin. The Transient Receptor
Potential Vanniloid-1 channel (TRPV-1) has a role in the cough reflex and airway expression
is increased in patients with chronic cough. The Ankyrin-1 receptor (TRPA-1) is often coexpressed.
It was hypothesised that, like chronic cough patients, IPF patients have increased
airway TRP receptor expression. Bronchial biopsies were obtained from 16 patients with IPF,
11 patients with idiopathic chronic cough and 8 controls without cough. All other causes of
cough were rigorously excluded. Real-time quantitative Polymerase Chain Reaction was used
to detect TRPV-1 and TRPA-1 mRNA expression with Immunohistochemistry demonstrating
protein expression. Mean TRPV-1 and TRPA-1 gene expression was higher in IPF patients
compared with controls, but the difference did not reach statistical significance. Immunostaining
supported these findings. This study suggests that structural up-regulation of central airway
TRP receptors is not the key mechanism for cough in IPF patients. It is probable that IPF
cough results from altered neuronal sensitivity at multiple levels of the cough pathway
Distribution and characteristics of Infrared Dark Clouds using genetic forward modelling
Infrared Dark Clouds (IRDCs) are dark clouds seen in silhouette in
mid-infrared surveys. They are thought to be the birthplace of massive stars,
yet remarkably little information exists on the properties of the population as
a whole (e.g. mass spectrum, spatial distribution). Genetic forward modelling
is used along with the Two Micron All Sky Survey and the Besancon Galactic
model to deduce the three dimensional distribution of interstellar extinction
towards previously identified IRDC candidates. This derived dust distribution
can then be used to determine the distance and mass of IRDCs, independently of
kinematic models of the Milky Way. Along a line of sight that crosses an IRDC,
the extinction is seen to rise sharply at the distance of the cloud. Assuming a
dust to gas ratio, the total mass of the cloud can be estimated. The method has
been successfully applied to 1259 IRDCs, including over 1000 for which no
distance or mass estimate currently exists. The IRDCs are seen to lie
preferentially along the spiral arms and in the molecular ring of the Milky
Way, reinforcing the idea that they are the birthplace of massive stars. Also,
their mass spectrum is seen to follow a power law with an index of -1.75 +/-
0.06, steeper than giant molecular clouds in the inner Galaxy, but comparable
to clumps in GMCs. This slope suggests that the IRDCs detected using the
present method are not gravitationally bound, but are rather the result of
density fluctuations induced by turbulence.Comment: 15 pages, 9 figures, accepted for publication in Ap
Curvature Dependence of Surface Free Energy of Liquid Drops and Bubbles: A Simulation Study
We study the excess free energy due to phase coexistence of fluids by Monte
Carlo simulations using successive umbrella sampling in finite LxLxL boxes with
periodic boundary conditions. Both the vapor-liquid phase coexistence of a
simple Lennard-Jones fluid and the coexistence between A-rich and B-rich phases
of a symmetric binary (AB) Lennard-Jones mixture are studied, varying the
density rho in the simple fluid or the relative concentration x_A of A in the
binary mixture, respectively. The character of phase coexistence changes from a
spherical droplet (or bubble) of the minority phase (near the coexistence
curve) to a cylindrical droplet (or bubble) and finally (in the center of the
miscibility gap) to a slab-like configuration of two parallel flat interfaces.
Extending the analysis of M. Schrader, P. Virnau, and K. Binder [Phys. Rev. E
79, 061104 (2009)], we extract the surface free energy gamma (R) of both
spherical and cylindrical droplets and bubbles in the vapor-liquid case, and
present evidence that for R -> Infinity the leading order (Tolman) correction
for droplets has sign opposite to the case of bubbles, consistent with the
Tolman length being independent on the sign of curvature. For the symmetric
binary mixture the expected non-existence of the Tolman length is confirmed. In
all cases {and for a range of radii} R relevant for nucleation theory, gamma(R)
deviates strongly from gamma (Infinity) which can be accounted for by a term of
order gamma(Infinity)/gamma(R)-1 ~ 1/R^2. Our results for the simple
Lennard-Jones fluid are also compared to results from density functional theory
and we find qualitative agreement in the behavior of gamma(R) as well as in the
sign and magnitude of the Tolman length.Comment: 25 pages, submitted to J. Chem. Phy
Convection in galaxy-cluster plasmas driven by active galactic nuclei and cosmic-ray buoyancy
Turbulent heating may play an important role in galaxy-cluster plasmas, but
if turbulent heating is to balance radiative cooling in a quasi-steady state,
some mechanism must set the turbulent velocity to the required value. This
paper explores one possible regulating mechanism associated with an active
galactic nucleus at cluster center. A steady-state model for the intracluster
medium is presented in which radiative cooling is balanced by a combination of
turbulent heating and thermal conduction. The turbulence is generated by
convection driven by the buoyancy of cosmic rays produced by a central radio
source. The cosmic-ray luminosity is powered by the accretion of intracluster
plasma onto a central black hole. The model makes the rather extreme assumption
that the cosmic rays and thermal plasma are completely mixed. Although the
intracluster medium is convectively unstable near cluster center in the model
solutions, the specific entropy of the thermal plasma still increases outwards
because of the cosmic-ray modification to the stability criterion. The model
provides a self-consistent calculation of the turbulent velocity as a function
of position, but fails to reproduce the steep central density profiles observed
in clusters. The principal difficulty is that in order for the fully mixed
intracluster medium to become convectively unstable, the cosmic-ray pressure
must become comparable to or greater than the thermal pressure within the
convective region. The large cosmic-ray pressure gradient then provides much of
the support against gravity, reducing the thermal pressure gradient near
cluster center and decreasing the central plasma density gradient. A more
realistic AGN-feedback model of intracluster turbulence in which relativistic
and thermal plasmas are only partially mixed may have greater success.Comment: version 2: minor changes in wordin
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