Surface topography of viable articular cartilage measured with scanning white light interferometry

SummaryObjectiveBy means of scanning white light interferometry, develop a noncontact, nondestructive technique capable of measuring surface topography of viable cartilage.MethodsUsing full thickness cylindrical cartilage explants obtained from bovine calf knees, experiments were performed to produce a surface preparation protocol that yields highly repeatable topographical measurements while maintaining cartilage viability. To further validate the technique, a series of human talar cartilage samples, displaying varying degrees of cartilage degeneration, was then subjected to interferometric measurements and compared to their histology.ResultsA key aspect of the technique of surface topographic measurement by interferometry was the development of an optimal surface preparation process. The technique was successfully validated against standard 2-D profilometry. The intrinsic variability of the technique is less than 2%, which is much less than the average point-to-point variability of 17% observed across a cartilage specimen. The technique was hence sufficiently sensitive to readily detect differences in roughness between surfaces of healthy cartilage in different locations on the bovine knee. Thus, the average roughness of the medial explants exceeded that of the lateral explants by 0.35μmRa (P=0.003) and the roughness of the trochlear explants exceeded that of the condylar explants by 0.55μmRa (P<0.0001). Also, applying this technique to diseased human talar cartilage samples, a statistically significant increase in the average surface roughness value per unit increase in histological degeneration score was observed (≥0.2μmRa, P≤0.041), making surface roughness obtained via interferometry a useful parameter for evaluating cartilage health nondestructively.ConclusionsThe aim of developing a protocol based on white light interferometry to measure the surface topography of viable articular cartilage was achieved. This interferometric technique opens the door to monitoring the surface topography of live cartilage, as is desirable for ex vivo tests on cartilage explants

Anti-apoptotic treatments prevent cartilage degradation after acute trauma to human ankle cartilage

SummaryObjectivesTo investigate the effect of anti-apoptotic agents on cartilage degradation after a single impact to ankle cartilage.DesignTen human normal tali were impacted with the impulse of 1Ns generating peak forces in the range of 600N using a 4mm diameter indenter. Eight millimeter cartilage plugs containing the 4mm diameter impacted core and a 4mm adjacent ring were removed and cultured with or without P188 surfactant (8mg/ml), caspase-3 (10uM), or caspase-9 (2uM) inhibitors for 48h. Results were assessed in the superficial and middle-deep layers immediately after injury at day 0 and at 2, 7 and 14 days after injury by live/dead cell and Tunel assays and by histology with Safranin O/fast green staining.ResultsA single impact to human articular cartilage ex vivo resulted in cell death, cartilage degeneration, and radial progression of apoptosis to the areas immediately adjacent to the impact. The P188 was more effective in preventing cell death than the inhibitors of caspases. It reduced cell death by more than 2-fold (P<0.05) in the core and by about 30% in the ring in comparison with the impacted untreated control at all time points. P188 also prevented radial expansion of apoptosis in the ring region especially in the first 7 days post-impaction (7.5% Tunel-positive cells vs 46% in the untreated control; P<0.01). Inhibitors of caspase-3 or -9 were effective in reducing cell death in the impacted core only at early time points, but were ineffective in doing so in the ring. Mankin score was significantly improved in the P188 and caspase-3 treated groups.ConclusionsEarly intervention with the P188 and caspase-3 inhibitor may have therapeutic potential in the treatment of cartilage defects immediately after injury

The European VCD System: Facilitating Public Procurement through Criteria-to-Evidence Mapping

International audienceTo facilitate European Union (EU)-wide interoperability in public eProcurement, the European Commission co-funds the PEPPOL project. PEPPOL aims at setting up pan-European pilot solutions that conjointly exist with national infrastructures. One of the key building blocks is the Virtual Company Dossier (VCD), an electronic cross-border document container that carries attestations and candidate statements required to evidence the fulfilment of non-exclusion and selection criteria in public tendering procedures. The attestations and candidate statements available in the various Member States often differ in their quality, relevance to certain criteria and format. In this contribution we present a concept to facilitate the correct mapping of national evidences to selection and exclusion criteria of a contracting authority from a different EU Member State. We present a solution that supports mutual recognition of diplomas, certificates or other evidence with a decision-support system called the European VCD System

Tribocorrosion behavior of CoCrMo alloy for hip prosthesis as a function of loads: A comparison between two testing systems

Metal-on-metal (MOM) hip prosthesis bearings have enjoyed renewed popularity, but concerns remain with wear debris and metal ion release causing a negative response in the surrounding tissues. Further understanding into the wear and corrosion mechanisms occurring in MOM hips is therefore essential. The purpose of this study was to evaluate the tribocorrosion behavior, or interplay between corrosion and wear, of a low-carbon CoCrMo alloy as a function of loading. The tribocorrosion tests were performed using two tribometer configurations. In the first configuration, “System A”, a linearly reciprocating alumina ball slid against the flat metal immersed in a phosphate buffer solution (PBS). In the second configuration, “System B”, the flat end of a cylindrical metal pin was pressed against an alumina ball that oscillated rotationally, using bovine calf serum (BCS) as the lubricant and electrolyte. System B was custom-built to emulate in vivo conditions. The tribocorrosion tests were performed under potentiostatic conditions at −0.345 V, with a sliding duration of 1800 s and a frequency of 1 Hz. In System A the applied loads were 0.05, 0.5, and 1 N (138, 296 and 373 MPa, respectively) and in System B were 16, 32, and 64 N (474, 597, and 752 MPa, respectively). Electrochemical impedance spectroscopy (EIS) and polarization resistance were estimated. The total mass loss (Kwc) in the CoCrMo was determined. The mass loss due to wear (Kw) and that due to corrosion (Kc) were determined. The dominant wear regime for the CoCrMo alloy subjected to sliding changes from wear–corrosion to mechanical wear as the contact stress increases. An attempt was made to compare both system, in their tribochemical responses and formulate some insights in the total degradation processes. Our results also suggest that the proteins in the serum lubricant assist in the generation of a protective layer against corrosion during sliding. The study highlights the need of adequate methodology/guidelines to compare the results from different test systems and translating in solving the practical problems

Boron: An essential element for vascular plants

[No abstract available

Progressive transformation of a flux rope to an ICME

The solar wind conditions at one astronomical unit (AU) can be strongly disturbed by the interplanetary coronal mass ejections (ICMEs). A subset, called magnetic clouds (MCs), is formed by twisted flux ropes that transport an important amount of magnetic flux and helicity which is released in CMEs. At 1 AU from the Sun, the magnetic structure of MCs is generally modeled neglecting their expansion during the spacecraft crossing. However, in some cases, MCs present a significant expansion. We present here an analysis of the huge and significantly expanding MC observed by the Wind spacecraft during 9 and 10 November, 2004. After determining an approximated orientation for the flux rope using the minimum variance method, we precise the orientation of the cloud axis relating its front and rear magnetic discontinuities using a direct method. This method takes into account the conservation of the azimuthal magnetic flux between the in- and out-bound branches, and is valid for a finite impact parameter (i.e., not necessarily a small distance between the spacecraft trajectory and the cloud axis). Moreover, using the direct method, we find that the ICME is formed by a flux rope (MC) followed by an extended coherent magnetic region. These observations are interpreted considering the existence of a previous larger flux rope, which partially reconnected with its environment in the front. These findings imply that the ejected flux rope is progressively peeled by reconnection and transformed to the observed ICME (with a remnant flux rope in the front part).Comment: Solar Physics (in press

Anisotropy of the orbital methods and the magnetic dipole term TzT_z in CrO2{\rm CrO_2}: An {\it ab-initio} studt

A systematic study is performed by the {\it ab-initio} density functional theory of the anisotropy of the orbital moments $$and the magnetic dipole term$$ in bulk ${\rm CrO_2}$. Two different band-structure techniques are used (FLAPW and LMTO-ASA), and the electronic correlations are treated by the local-spin-density approximation (LSDA), the LSDA+ orbital polarization method, and the LSDA+$U$ method. The calculated anisotropies of $$and$$ are very large compared to Fe, Ni and Co but still a factor of 5 and 2 smaller than the anisotropies obtained from a recently suggested analysis of the X-ray magnetic circular dichroism spectra for a thick layer of ${\rm CrO_2}$

Radial evolution of the April 2020 stealth coronal mass ejection between 0.8 and 1 AU - Comparison of Forbush decreases at Solar Orbiter and near the Earth

Aims. We present observations of the first coronal mass ejection (CME) observed at the Solar Orbiter spacecraft on April 19, 2020, and the associated Forbush decrease (FD) measured by its High Energy Telescope (HET). This CME is a multispacecraft event also seen near Earth the next day. Methods. We highlight the capabilities of HET for observing small short-term variations of the galactic cosmic ray count rate using its single detector counters. The analytical ForbMod model is applied to the FD measurements to reproduce the Forbush decrease at both locations. Input parameters for the model are derived from both in situ and remote-sensing observations of the CME. Results. The very slow (~350 km/s) stealth CME caused a FD with an amplitude of 3 % in the low-energy cosmic ray measurements at HET and 2 % in a comparable channel of the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter, as well as a 1 % decrease in neutron monitor measurements. Significant differences are observed in the expansion behavior of the CME at different locations, which may be related to influence of the following high speed solar wind stream. Under certain assumptions, ForbMod is able to reproduce the observed FDs in low-energy cosmic ray measurements from HET as well as CRaTER, but with the same input parameters, the results do not agree with the FD amplitudes at higher energies measured by neutron monitors on Earth. We study these discrepancies and provide possible explanations. Conclusions. This study highlights that the novel measurements of the Solar Orbiter can be coordinated with other spacecraft to improve our understanding of space weather in the inner heliosphere. Multi-spacecraft observations combined with data-based modeling are also essential to understand the propagation and evolution of CMEs as well as their space weather impacts

GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers Observed by LIGO and Virgo during the First and Second Observing Runs

We present the results from three gravitational-wave searches for coalescing compact binaries with component masses above 1 Ma™ during the first and second observing runs of the advanced gravitational-wave detector network. During the first observing run (O1), from September 12, 2015 to January 19, 2016, gravitational waves from three binary black hole mergers were detected. The second observing run (O2), which ran from November 30, 2016 to August 25, 2017, saw the first detection of gravitational waves from a binary neutron star inspiral, in addition to the observation of gravitational waves from a total of seven binary black hole mergers, four of which we report here for the first time: GW170729, GW170809, GW170818, and GW170823. For all significant gravitational-wave events, we provide estimates of the source properties. The detected binary black holes have total masses between 18.6-0.7+3.2 Mâ™ and 84.4-11.1+15.8 Mâ™ and range in distance between 320-110+120 and 2840-1360+1400 Mpc. No neutron star-black hole mergers were detected. In addition to highly significant gravitational-wave events, we also provide a list of marginal event candidates with an estimated false-alarm rate less than 1 per 30 days. From these results over the first two observing runs, which include approximately one gravitational-wave detection per 15 days of data searched, we infer merger rates at the 90% confidence intervals of 110-3840 Gpc-3 y-1 for binary neutron stars and 9.7-101 Gpc-3 y-1 for binary black holes assuming fixed population distributions and determine a neutron star-black hole merger rate 90% upper limit of 610 Gpc-3 y-1. © 2019 authors. Published by the American Physical Society