271 research outputs found
Algorithm for Femoral and Periacetabular Osteotomies in Complex Hip Deformities
Background: Residual acetabular dysplasia of the hip in most patients can be corrected by periacetabular osteotomy. However, some patients have intraarticular abnormalities causing insufficient coverage, containment or congruency after periacetabular osteotomy, or extraarticular abnormalities that limit either acetabular correction or hip motion. For these patients, we believe an additional proximal femoral osteotomy can improve coverage, containment, congruency and/or motion. Purposes: We provide algorithms for (1) identifying patients we believe will benefit from proximal femoral osteotomy, (2) selecting the appropriate osteotomy, and (3) choosing the sequence of these osteotomies. Methods: Anteroposterior, false-profile and functional radiographs and MR can identify most patients we believe will benefit from periacetabular and femoral osteotomies. Recently described techniques, including relative femoral neck lengthening, femoral neck osteotomy and femoral head osteotomy have expanded indications for a combined procedure. Historically performed first, periacetabular osteotomy is now frequently performed following femoral osteotomy. Results: The rate of intertrochanteric osteotomy performed with periacetabular osteotomy has decreased from approximately 10% in the first 500 surgeries to about 2% currently. Among 151 relative neck lengthenings (23 with PAO), 53 femoral neck osteotomies (4 with PAO) and 14 femoral head osteotomies (11 with PAO), eleven complications occurred including osteonecrosis in two and delayed unions in eight. No complication occurred following a combined procedure. Conclusion: Although isolated periacetabular osteotomy can provide sufficient coverage, containment and congruency for most patients with residual hip dysplasia, some may benefit from an additional proximal femoral osteotomy. Knowing the appropriate indications, selection, and sequencing of these osteotomies is critical for enhancing patient outcomes. Level of Evidence: Level V, therapeutic study. See Guidelines for Authors for a complete description of levels of evidenc
Enabling III-V-based optoelectronics with low-cost dynamic hydride vapor phase epitaxy
Silicon is the dominant semiconductor in many semiconductor device
applications for a variety of reasons, including both performance and cost.
III-V materials have improved performance compared to silicon, but currently
they are relegated to applications in high-value or niche markets due to the
absence of a low-cost, high-quality production technique. Here we present an
advance in III-V materials synthesis using hydride vapor phase epitaxy that has
the potential to lower III-V semiconductor deposition costs by orders of
magnitude while maintaining the requisite optoelectronic material quality that
enables III-V-based technologies to outperform Si. We demonstrate the impacts
of this advance by addressing the use of III-Vs in terrestrial photovoltaics, a
highly cost-constrained market. The emergence of a low-cost III-V deposition
technique will enable III-V electronic and opto-electronic devices, with all
the benefits that they bring, to permeate throughout modern society.Comment: pre-prin
Minimum energetic cost to maintain a target nonequilibrium state
In the absence of external driving, a system exposed to thermal fluctuations will relax to equilibrium. However, the constant input of work makes it possible to counteract this relaxation and maintain the system in a nonequilibrium steady state. In this article, we use the stochastic thermodynamics of Markov jump processes to compute the minimum rate at which energy must be supplied and dissipated to maintain an arbitrary nonequilibrium distribution in a given energy landscape. This lower bound depends on two factors: the undriven probability current in the equilibrium state and the distance from thermal equilibrium of the target distribution. By showing the consequences of this result in a few simple examples, we suggest general implications for the required energetic costs of macromolecular repair and cytosolic protein localization.Gordon and Betty Moore Foundation (GBMF4343
In situ pinning with arthroscopic osteoplasty for mild SCFE: A preliminary technical report
There is emerging evidence that even mild slipped capital femoral epiphysis leads to early articular damage. Therefore, we have begun treating patients with mild slips and signs of impingement with in situ pinning and immediate arthroscopic osteoplasty. DESCRIPTION OF TECHNIQUES: Surgery was performed using the fracture table. After in situ pinning and diagnostic arthroscopy, peripheral compartment access was obtained and head-neck osteoplasty was completed
Spinning Black Holes in (2+1)-dimensional String and Dilaton Gravity
We present a new class of spinning black hole solutions in
-dimensional general relativity minimally coupled to a dilaton with
potential . When , the corresponding spinning black hole
is a solution of low energy -dimensional string gravity. Apart from the
limiting case of the black hole, these spinning black holes have no inner
horizon and a curvature singularity only at the origin. We compute the mass and
angular momentum parameters of the solutions at spatial infinity, as well as
their temperature and entropy.Comment: 8 pages, Latex, statements about mass of 2+1 Hirschmann and Welch
magnetic solution corrected, in press in Phys. Lett.
Spatial methods for event reconstruction in CLEAN
In CLEAN (Cryogenic Low Energy Astrophysics with Noble gases), a proposed
neutrino and dark matter detector, background discrimination is possible if one
can determine the location of an ionizing radiation event with high accuracy.
We simulate ionizing radiation events that produce multiple scintillation
photons within a spherical detection volume filled with liquid neon. We
estimate the radial location of a particular ionizing radiation event based on
the observed count data corresponding to that event. The count data are
collected by detectors mounted at the spherical boundary of the detection
volume. We neglect absorption, but account for Rayleigh scattering. To account
for wavelength-shifting of the scintillation light, we assume that photons are
absorbed and re-emitted at the detectors. Here, we develop spatial Maximum
Likelihood methods for event reconstruction, and study their performance in
computer simulation experiments. We also study a method based on the centroid
of the observed count data. We calibrate our estimates based on training data
A Qualitative Analysis of Student Understanding of Team Function Through the use of the Jefferson Teamwork Observation Guide (JTOG)
Background:
Several early IOM reports identified the need to educate medical and health professions students in delivering patient-centered care as members of interprofessional teams (IOM, 2001; IOM, 2003). Evidence shows that conducting interprofessional education during education and training prepares student learners for collaborative practice when they enter the workplace, which in turn helps to achieve the Triple Aim of 1) enhancing the patient experience; 2) improving the health of populations; and 3) decreasing costs (WHO, 2010; Berwick, et al., 2008). One way to prepare students for collaborative practice is to have them observe real teams in action. Thus, the Jefferson Teamwork Observation Guide (JTOG) was created to serve as an educational tool in aiding students to better recognize the characteristics of effective teams. It has since been used to assess teams in the majority of clinical observation, simulation and collaborative practice activities offered by Jefferson Center for Interprofessional Education (JCIPE).
The JTOG is a two-part assessment comprised of identifiable characteristics of well-functioning teams drawn from the literature about teamwork. The first part consists of Likert Scale questions (strongly disagree to strongly agree) regarding the behavior of the interprofessional team observed in the domains of Values/Ethics in Interprofessional Practice, Roles/Responsibilities, Interprofessional Communication, Teams and Teamwork, and Leadership (IPEC, 2011; IPEC 2016). The second part includes qualitative questions relating to team-based care, patient-centered care, and teamwork
Stacking non-BPS D-Branes
We present a candidate supergravity solution for a stacked configuration of
stable non-BPS D-branes in Type II string theory compactified on T^4/Z_2. This
gives a supergravity description of nonabelian tachyon condensation on the
brane worldvolume.Comment: 10 pages, revte
Cosmological Plebanski theory
We consider the cosmological symmetry reduction of the Plebanski action as a
toy-model to explore, in this simple framework, some issues related to loop
quantum gravity and spin-foam models. We make the classical analysis of the
model and perform both path integral and canonical quantizations. As for the
full theory, the reduced model admits two types of classical solutions:
topological and gravitational ones. The quantization mixes these two solutions,
which prevents the model to be equivalent to standard quantum cosmology.
Furthermore, the topological solution dominates at the classical limit. We also
study the effect of an Immirzi parameter in the model.Comment: 20 page
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Interannual variability in ozone removal by a temperate deciduous forest
The ozone (O3) dry depositional sink and its contribution to observed variability in tropospheric O3 are both poorly understood. Distinguishing O3 uptake through plant stomata versus other pathways is relevant for quantifying the O3 influence on carbon and water cycles. We use a decade of O3, carbon, and energy eddy covariance (EC) fluxes at Harvard Forest to investigate interannual variability (IAV) in O3 deposition velocities ( math formula). In each month, monthly mean math formula for the highest year is twice that for the lowest. Two independent stomatal conductance estimates, based on either water vapor EC or gross primary productivity, vary little from year to year relative to canopy conductance. We conclude that nonstomatal deposition controls the substantial observed IAV in summertime math formula during the 1990s over this deciduous forest. The absence of obvious relationships between meteorology and math formula implies a need for additional long-term, high-quality measurements and further investigation of nonstomatal mechanisms
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