Global Identification of Drive Gains and Dynamic Parameters of Parallel Robots - Part 2: Case Study

International audienceUsually, identification models of parallel robots are simplified and take only the dynamics of the moving platform into account. Moreover the input efforts are estimated through the use of the manfucaturer's actuator drive gains that are not calibrated thus leading to identification errors. In this paper a systematic way to derive the full dynamic identification model of the Orthoglide parallel robot in combination with a method that allows the identification of both robot inertial parameters and drive gains

Wound fluid ceftriaxone concentrations after local application with calcium sulphate as carrier material in the treatment of orthopaedic device-associated hip infections.

There is a considerable challenge in treating bone infections and orthopaedic device-associated infection (ODAI), partly due to impaired penetration of systemically administrated antibiotics at the site of infection. This may be circumvented by local drug administration. Knowledge of the release kinetics from any carrier material is essential for proper application. Ceftriaxone shows a particular constant release from calcium sulphate (CaSO <sub>4</sub> ) in vitro, and is particularly effective against streptococci and a large portion of Gram-negative bacteria. We present the clinical release kinetics of ceftriaxone-loaded CaSO <sub>4</sub> applied locally to treat ODAI. A total of 30 operations with ceftriaxone-loaded CaSO <sub>4</sub> had been performed in 28 patients. Ceftriaxone was applied as a single local antibiotic in 21 operations and combined with vancomycin in eight operations, and in an additional operation with vancomycin and amphotericin B. Sampling of wound fluid was performed from drains or aspirations. Ceftriaxone concentrations were measured by liquid chromatography with tandem mass spectrometry (LC-MS/MS). A total of 37 wound fluid concentrations from 16 operations performed in 14 patients were collected. The ceftriaxone concentrations remained approximately within a range of 100 to 200 mg/l up to three weeks. The median concentration was 108.9 mg/l (interquartile range 98.8 to 142.5) within the first ten days. No systemic adverse reactions were observed. Our study highlights new clinical data of locally administered ceftriaxone with CaSO <sub>4</sub> as carrier material. The near-constant release of ceftriaxone from CaSO <sub>4</sub> observed in vitro could be confirmed in vivo. The concentrations remained below known local toxicity thresholds.Cite this article: Bone Joint Res 2022;11(11):835-842

Création d’un score d’évaluation du risque de symptômes musculo-squelettiques basé sur des facteurs professionnels

Objectif L’objectif de ce travail est la création d’un score d’évaluation du risque de symptômes musculo-squelettiques (SMS) chroniques des membres supérieurs, uniquement basé sur des données d’exposition professionnelle aux déterminants biomécaniques, psychosociaux et organisationnels. Ce score ne prenant pas en compte les facteurs individuels, permettra de classer les situations de travail devant bénéficier d’une action de prévention. Méthodes L’échantillon d’étude était constitué de 1749 salariés recrutés lors de la phase d’inclusion de la cohorte des salariés ligériens (COSALI). Les facteurs organisationnels, biomécaniques et psychosociaux et les variables associées aux SMS chroniques ont été recueillis par auto-questionnaire. Un score a été créé selon trois méthodes statistiques : une régression logistique binaire, une analyse en clusters suivie d’une analyse par arbre de décision et une modélisation par classes latentes. Chacune de ces méthodes est susceptible d’entraîner la création de scores différents. Résultats L’area under the curve (AUC) obtenu par la régression logistique était de 0,75 contre 0,66 pour l’analyse en clusters et 0,65 pour l’analyse en classes latentes. La régression logistique a donc été retenue pour la création du score. Les facteurs associés aux SMS chroniques des membres supérieurs étaient l’intensité élevée des efforts physiques ressentie (échelle RPE de Borg), la répétitivité des gestes plus de 4 h/j, la flexion du coude plus de 2 h/j, l’utilisation de la pince pouce-index plus de 4 h/j, la possibilité d’influencer le déroulement de son travail et l’aide des collègues. Le score a ensuite été créé à partir des paramètres estimés de la régression logistique, il s’étend de −1 à 15. Par exemple, 66 % de l’échantillon a un score supérieur ou égal à deux. Pour ce seuil, la valeur prédictive négative est de 93,4 %. Conclusions Selon le seuil choisi, le score aboutit à une forte valeur prédictive négative. Il pourrait constituer un outil utile aux préventeurs en entreprise afin de cibler l’effectif pour lequel il n’est pas indispensable de mettre en place des actions de prévention. Néanmoins ce score ne permet pas de prédire avec confiance les salariés qui seront atteints de SMS. Pour avoir un score plus performant, il faudrait intégrer des facteurs individuels tels que l’âge et le sexe, mais la caractérisation par situation de travail n’est alors plus envisageable

Nutrients

Vitamin K participates in brain physiology. This study aimed to determine whether using vitamin K antagonists (VKAs), which interfere with the vitamin K cycle, were (i) cross-sectionally associated with altered cognitive performance, and (ii) independent predictors of cognitive changes in older adults over 24 months. Information was collected on the use of VKAs (i.e., warfarin, acenocoumarol, and fluindione) among 378 geriatric outpatients (mean, 82.3 +/- 5.6 years; 60.1% female). Global cognitive performance and executive functions were assessed with Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB) scores, respectively, at baseline and after 12 and 24 months of follow-up. Age, gender, body mass index, mean arterial pressure, disability, gait speed, comorbidities, atrial fibrillation, stroke, carotid artery stenosis, leukoaraiosis grade on computed tomography (CT) scan, psychoactive drugs, antidementia drugs, blood-thinning drugs (i.e., anticoagulants other than VKAs, antiplatelet medications), serum creatinine levels, and vitamin B12 concentrations were considered as potential confounders. Using VKAs was associated with lower (i.e., worse) FAB score at baseline (adjusted beta = -2.1, p = 0.026), and with a decrease in FAB score after 24 months (adjusted beta = -203.6%, p = 0.010), but not after 12 months (p = 0.659). Using VKAs was not associated with any change in MMSE score at baseline (p = 0.655), after 12 months (p = 0.603), or after 24 months (p = 0.201). In conclusion, we found more severe executive dysfunction at baseline and incident executive decline over 24 months among geriatric patients using VKAs, when compared with their counterparts

AVHRR and VISSR satellite instrument calibration results for both Cirrus and marine stratocumulus IFO periods

Accurate characterizations of some cloud parameters are dependent upon the absolute accuracy of satellite radiance measurements. Visible wavelength measurements from both the AVHRR and VISSR instruments are often used to study cloud characteristics. Both of these instruments were radiometrically calibrated prior to launch, but neither has an onboard device to monitor degradation after launch. During the FIRE/SRB cirrus Intensive Field Operation (IFO), a special effort was made to monitor calibration of these two instruments onboard the NOAA-9 and GOES-6 spacecraft. In addition, several research groups have combined their efforts to assess the long-term performance of both instruments. These results are presented, and a limited comparison is made with the ERBE calibration standard

Anomalous material-dependent transport of focused, laser-driven proton beams.

Intense lasers can accelerate protons in sufficient numbers and energy that the resulting beam can heat materials to exotic warm (10 s of eV temperature) states. Here we show with experimental data that a laser-driven proton beam focused onto a target heated it in a localized spot with size strongly dependent upon material and as small as 35 μm radius. Simulations indicate that cold stopping power values cannot model the intense proton beam transport in solid targets well enough to match the large differences observed. In the experiment a 74 J, 670 fs laser drove a focusing proton beam that transported through different thicknesses of solid Mylar, Al, Cu or Au, eventually heating a rear, thin, Au witness layer. The XUV emission seen from the rear of the Au indicated a clear dependence of proton beam transport upon atomic number, Z, of the transport layer: a larger and brighter emission spot was measured after proton transport through the lower Z foils even with equal mass density for supposed equivalent proton stopping range. Beam transport dynamics pertaining to the observed heated spot were investigated numerically with a particle-in-cell (PIC) code. In simulations protons moving through an Al transport layer result in higher Au temperature responsible for higher Au radiant emittance compared to a Cu transport case. The inferred finding that proton stopping varies with temperature in different materials, considerably changing the beam heating profile, can guide applications seeking to controllably heat targets with intense proton beams

The low level of debris disk activity at the time of the Late Heavy Bombardment: a Spitzer study of Praesepe

We present 24 micron photometry of the intermediate-age open cluster Praesepe. We assemble a catalog of 193 probable cluster members that are detected in optical databases, the Two Micron All Sky Survey (2MASS), and at 24 micron, within an area of ~ 2.47 square degrees. Mid-IR excesses indicating debris disks are found for one early-type and for three solar-type stars. Corrections for sampling statistics yield a 24 micron excess fraction (debris disk fraction) of 6.5 +- 4.1% for luminous and 1.9 +- 1.2% for solar-type stars. The incidence of excesses is in agreement with the decay trend of debris disks as a function of age observed for other cluster and field stars. The values also agree with those for older stars, indicating that debris generation in the zones that emit at 24 micron falls to the older 1-10 Gyr field star sample value by roughly 750 Myr. We discuss our results in the context of previous observations of excess fractions for early- and solar-type stars. We show that solar-type stars lose their debris disk 24 micron excesses on a shorter timescale than early-type stars. Simplistic Monte Carlo models suggest that, during the first Gyr of their evolution, up to 15-30% of solar-type stars might undergo an orbital realignment of giant planets such as the one thought to have led to the Late Heavy Bombardment, if the length of the bombardment episode is similar to the one thought to have happened in our Solar System. In the Appendix, we determine the cluster's parameters via boostrap Monte Carlo isochrone fitting, yielding an age of 757 Myr (+- 36 Myr at 1 sigma confidence) and a distance of 179 pc (+- 2 pc at 1 sigma confidence), not allowing for systematic errors.Comment: 22 pages, 14 figures, 9 tables, emulateapj format; Accepted for publication in The Astrophysical Journa

Molecular prevalence of Chlamydia and Chlamydia-like bacteria in Tunisian domestic ruminant farms and their influencing risk factors

Chlamydia and Chlamydia-like bacteria are well known to infect several organisms and may cause a wide range of diseases, particularly in ruminants. To gain insight into the prevalence and diversity of these intracellular bacteria, we applied a pan-Chlamydiales real-time PCR to 1,134 veterinary samples taken from 130 Tunisian ruminant herds. The true adjusted animal population-level prevalence was 12.9% in cattle, against 8.7% in sheep. In addition, the true adjusted herd-level prevalence of Chlamydiae was 80% in cattle and 25.5% in sheep. Chlamydiales from three familylevel lineages were detected indicating a high biodiversity of Chlamydiales in ruminant herds. Our results showed that Parachlamydia acanthamoebae could be responsiblefor bovine and ovine chlamydiosis in central-eastern Tunisia. Multivariable logistic regression analysis at the animal population level indicated that strata and digestive disorders variables were the important risk factors of bovine and ovine chlamydiosis. However, origin and age variables were found to be associated withbovine and ovine chlamydiosis, respectively. At the herd level, risk factors for Chlamydia positivity were as follows: abortion and herd size for cattle against breeding system, cleaning frequency, quarantine, use of disinfectant and floor type for sheep. Paying attention to these risk factors will help improvement of control programs against this harmful zoonotic disease

Magnetic Phase Diagram and Metal-Insulator Transition of NiS2-xSex

Magnetic phase diagram of NiS2-xSex has been reexamined by systematic studies of electrical resistivity, uniform magnetic susceptibility and neutron diffraction using single crystals grown by a chemical transport method. The electrical resistivity and the uniform magnetic susceptibility exhibit the same feature of temperature dependence over a wide Se concentration. A distinct first order metal-insulator (M-I) transition accompanied by a volume change was observed only in the antiferromagnetic ordered phase for 0.50<x<0.59. In this region, the M-I transition makes substantial effects to the thermal evolution of staggered moments. In the paramagnetic phase, the M-I transition becomes broad; both the electrical resistivity and the uniform magnetic susceptibility exhibit a broad maximum around the temperatures on the M-I transition-line extrapolated to the paramagnetic phase.Comment: 6 pages, 8 figures, corrected EPS fil