The aim of this study was to assess the efficacy of non-selective and selective non-steroidal anti-inflammatory drugs (NSAIDs) in preventing heterotopic ossification (HO) after total hip arthroplasty ...(THA).
A thorough and systematic literature search was conducted and 29 studies were found that met inclusion criteria. Data were extracted and statistical analysis was carried out generating forest plots.
Non-selective NSAIDs showed a significant decrease in the odds for forming HO after THA (odds ratio (OR) -1.35, confidence interval (CI) -1.83 to -0.86) when compared with placebo. Selective NSAIDs also showed a significant decrease in the odds for forming HO after THA when compared with placebo (OR -1.58, CI -2.41 to -0.75). When comparing non-selective NSAIDs with selective NSAIDs, there was no significant change in the odds for forming HO after THA (OR 0.22, CI -0.36 to 0.79).
Our meta-analyses of all available data suggest that both non-selective and selective NSAIDs are effective HO prophylaxis and can be used routinely after THA for pain control as well as prevention of HO. Indomethacin may serve as the benchmark among non-selective NSAIDs and celecoxib among selective NSAIDs. There was no difference in the incidence of HO between non-selective and selective NSAIDs, allowing physicians to choose either based on the clinical scenario and patient-specific factors. Cite this article: Bone Joint J 2018;100-B:915-22.
Aims.
Among the
γ
-ray sources discovered at high and very-high energies, a large fraction still lack a clear identification. In particular, the H.E.S.S. Galactic Plane Survey (HGPS) revealed 78 TeV ...sources among which 47 are not clearly associated with a known object. Multiwavelength data can help identify the origin of the very-high energy
γ
-ray emission, although some bright TeV sources have been detected without clear counterparts. We present a multiwavelength approach to constrain the origin of the emission from unidentified HGPS sources.
Methods.
We present a generic pipeline that explores a large database of multiwavelength archival data toward any region in the Galactic plane. Along with a visual inspection of the retrieved multiwavelength observations to search for faint and uncataloged counterparts, we derive a radio spectral index that helps disentangle thermal from nonthermal emission and a mean magnetic field through X-ray and TeV data in case of a leptonic scenario. We also search for a spectral connection between the GeV and the TeV regimes with the
Fermi
-LAT cataloged sources that may be associated with the unidentified HGPS source. We complete the association procedure with catalogs of known objects (supernova remnants, pulsar wind nebulae, H
II
regions, etc.) and with the source catalogs from instruments whose data are retrieved.
Results.
The method is applied on two unidentified sources, namely HESS J1427−608 and HESS J1458−608, for which the multiwavelength constraints favor the pulsar wind nebula (PWN) scenario. We model their broadband nonthermal spectra in a leptonic scenario with a magnetic field
B
≲ 10
μ
G, which is consistent with that obtained from ancient PWNe. We place both sources within the context of the TeV PWN population to estimate the spin-down power and the characteristic age of the putative pulsar. We also shed light on two possibly significant
γ
-ray excesses in the HGPS: the first is located in the south of the unidentified source HESS J1632−478 and the second is spatially coincident with the synchrotron-emitting supernova remnant G28.6−0.1. The multiwavelength counterparts found toward both
γ
-ray excesses make these promising candidates for being new very-high energy
γ
-ray sources.
Abstract
InGaN/GaN quantum wells (QWs) with sub-nanometer thickness can be employed in short-period superlattices for bandgap engineering of efficient optoelectronic devices, as well as for ...exploiting topological insulator behavior in III-nitride semiconductors. However, it had been argued that the highest indium content in such ultra-thin QWs is kinetically limited to a maximum of 33%, narrowing down the potential range of applications. Here, it is demonstrated that quasi two-dimensional (quasi-2D) QWs with thickness of one atomic monolayer can be deposited with indium contents far exceeding this limit, under certain growth conditions. Multi-QW heterostructures were grown by plasma-assisted molecular beam epitaxy, and their composition and strain were determined with monolayer-scale spatial resolution using quantitative scanning transmission electron microscopy in combination with atomistic calculations. Key findings such as the self-limited QW thickness and the non-monotonic dependence of the QW composition on the growth temperature under metal-rich growth conditions suggest the existence of a substitutional synthesis mechanism, involving the exchange between indium and gallium atoms at surface sites. The highest indium content in this work approached 50%, in agreement with photoluminescence measurements, surpassing by far the previously regarded compositional limit. The proposed synthesis mechanism can guide growth efforts towards binary InN/GaN quasi-2D QWs.
We have explored the impact of elevated growth and annealing temperatures on the local interfacial structure of thin Fe(12 nm)/Pt(10 nm) spintronic bilayers, epitaxially grown on MgO (100), and their ...correlation to magnetization reversal and dynamics. Electron-beam evaporation growth and subsequent annealing at 450 °C causes significant roughening of the MgO/Fe interface with irregular steps and multilevel (100) MgO surface terraces. Consequently, threading dislocations emerging at the step edges propagated in the Fe layer and terminated at the Fe/Pt interface, which appears pitted with pits 1.5–3 nm deep on the Fe side. Most of the pits are filled with the overlying Pt, whereby others by ferrimagnetic Fe3O4, forming nanoparticles that occupy nearly 9% of the Fe/Pt interfacial area. Fe3O4 nanoparticles occur at the termination sites of threading dislocations at the Fe/Pt interface, and their population density is equivalent to the density of threading dislocations in the Fe layer. The morphology of the Fe/Fe3O4/Pt system has a strong impact on the magnetization reversal, enhancing the coercive field and inducing an exchange bias below 200 K. Furthermore, low-temperature spin pumping and inverse spin Hall effect voltage measurements reveal that below their blocking temperature the nanoparticles can influence the spin current transmission and the spin rectification effects.
The use of strained substrates may overcome indium incorporation limits without inducing plastic relaxation in InGaN quantum wells, and this is particularly important for short-period InGaN/GaN ...superlattices. By incorporating elastic strain into these heterostructures, their optoelectronic behavior is modified. Our study employed density functional theory calculations to investigate the variation in the band-gap energy of short-period InGaN/GaN superlattices that comprise pseudomorphic quantum wells with a thickness of just one monolayer. Heterostructures with equibiaxially strained GaN barriers were compared with respective ones with relaxed barriers. The findings reveal a reduction of the band gap for lower indium contents, which is attributed to the influence of the highly strained nitrogen sublattice. However, above mid-range indium compositions, the situation is reversed, and the band gap increases with the indium content. This phenomenon is attributed to the reduction of the compressive strain in the quantum wells caused by the tensile strain of the barriers. Our study also considered local indium clustering induced by phase separation as another possible modifier of the band gap. However, unlike the substrate-controlled strain, this was not found to exert a significant influence on the band gap. Overall, this study provides important insights into the behavior of the band-gap energy of strained superlattices toward optimizing the performance of optoelectronic devices based on InGaN/GaN heterostructures.
An elastic lidar system for the H.E.S.S. Experiment Bregeon, J.; Compin, M.; Rivoire, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
05/2016, Letnik:
819
Journal Article
Recenzirano
Odprti dostop
The H.E.S.S. experiment in Namibia, Africa, is a high energy gamma ray telescope sensitive in the energy range from ~100Gev to a few tens of TeV, via the use of the atmospheric Cherenkov technique. ...To minimize the systematic errors on the derived fluxes of the measured sources, one has to calculate the impact of the atmospheric properties, in particular the extinction parameter of the Cherenkov light (~300–650nm) exploited to observe and reconstruct atmospheric particle showers initiated by gamma-ray photons. A lidar can provide this kind of information for some given wavelengths within this range. In this paper we report on the hardware components, operation and data acquisition of such a system installed at the H.E.S.S. site.
Recent developments in nanomagnetism and spintronics have enabled the use of ultrafast spin physics for terahertz (THz) emission. Spintronic THz emitters, consisting of ferromagnetic ...(FM)/non-magnetic (NM) thin film heterostructures, have demonstrated impressive properties for the use in THz spectroscopy and have great potential in scientific and industrial applications. In this work, we focus on the impact of the FM/NM interface on the THz emission by investigating Fe/Pt bilayers with engineered interfaces. In particular, we intentionally modify the Fe/Pt interface by inserting an ordered L10-FePt alloy interlayer. Subsequently, we establish that a Fe/L10-FePt (2 nm)/Pt configuration is significantly superior to a Fe/Pt bilayer structure, regarding THz emission amplitude. The latter depends on the extent of alloying on either side of the interface. The unique trilayer structure opens new perspectives in terms of material choices for the next generation of spintronic THz emitters.
Display omitted
•THz generation efficiency from Fe/Pt and Fe/L10-FePt/Pt trilayers•The alloyed interlayer of 2 nm thickness boosts the THz emission•Correlation of THz emission with the interface transparency•Induce the growth of L10-FePt phase by manipulating the temperature growth of Pt
Physics; Radiation physics; Radiation transport
The configurations of basal stacking fault (BSF) manifolds often observed in III‐nitride alloy epilayers, particularly InGaN, are considered herein. Using high‐resolution transmission electron ...microscopy (HRTEM), it is shown that the folds and steps of intrinsic BSFs can acquire a Shockley‐like partial dislocation character depending on the relative senses of the BSF stackings. This can lead to the introduction of extra geometrically necessary threading dislocations in the epilayer on account of variant coexistence. Moreover, it is demonstrated that the overlap of two I1 BSFs can transform into a single I2 BSF, which is terminated by a glissile Shockley dislocation. Shockley and Shockley‐like partial dislocations can acquire line directions comprising either <1¯1¯20> a‐line or <11¯00> m‐line segments. Using atomistic calculations, the core structures of the m‐line partials are provided and their visibility is examined by HRTEM as well as the possibility of their discrimination from the a‐line ones.
Stacking fault manifolds in InGaN epilayers are studied by high‐resolution transmission electron microscopy. It is shown that their folds and steps can exhibit partial dislocation character and can cause the introduction of threading dislocations due to variant coexistence. Using atomistic calculations, the core structures of Shockley partial dislocations along m‐line directions are studied in comparison to a‐line ones.
Abstract
III-nitride compound semiconductors are breakthrough materials regarding device applications. However, their heterostructures suffer from very high threading dislocation (TD) densities that ...impair several aspects of their performance. The physical mechanisms leading to TD nucleation in these materials are still not fully elucidated. An overlooked but apparently important mechanism is their heterogeneous nucleation on domains of basal stacking faults (BSFs). Based on experimental observations by transmission electron microscopy, we present a concise model of this phenomenon occurring in III-nitride alloy heterostructures. Such domains comprise overlapping intrinsic I
1
BSFs with parallel translation vectors. Overlapping of two BSFs annihilates most of the local elastic strain of their delimiting partial dislocations. What remains combines to yield partial dislocations that are always of screw character. As a result, TD nucleation becomes geometrically necessary, as well as energetically favorable, due to the coexistence of crystallographically equivalent prismatic facets surrounding the BSF domain. The presented model explains all observed BSF domain morphologies, and constitutes a physical mechanism that provides insight regarding dislocation nucleation in wurtzite-structured alloy epilayers.
The H.E.S.S experimental project Vasileiadis, Georges
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment,
11/2005, Letnik:
553, Številka:
1
Journal Article, Conference Proceeding
Recenzirano
The H.E.S.S experiment (for High Energy Stereoscopic System) consists of four imaging Cherenkov telescopes situated in the Namibia Khomas Highland desert (1800
m
asl). Its main characteristics are ...the low energy threshold (100
GeV) and substantial flux sensitivity (1% Crab units). The combination of the four telescope data analysis provide good background rejection and angular resolution. Recent results on the performance and operation are reported here.
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