Aging enhances serum cytokine response but not task-induced grip strength declines in a rat model of work-related musculoskeletal disorders

<p>Abstract</p> <p>Background</p> <p>We previously reported early tissue injury, increased serum and tissue inflammatory cytokines and decreased grip in young rats performing a moderate demand repetitive task. The tissue cytokine response was transient, the serum response and decreased grip were still evident by 8 weeks. Thus, here, we examined their levels at 12 weeks in young rats. Since aging is known to enhance serum cytokine levels, we also examined aged rats.</p> <p>Methods</p> <p>Aged and young rats, 14 mo and 2.5 mo of age at onset, respectfully, were trained 15 min/day for 4 weeks, and then performed a high repetition, low force (HRLF) reaching and grasping task for 2 hours/day, for 12 weeks. Serum was assayed for 6 cytokines: IL-1alpha, IL-6, IFN-gamma, TNF-alpha, MIP2, IL-10. Grip strength was assayed, since we have previously shown an inverse correlation between grip strength and serum inflammatory cytokines. Results were compared to naïve (grip), and normal, food-restricted and trained-only controls.</p> <p>Results</p> <p>Serum cytokines were higher overall in aged than young rats, with increases in IL-1alpha, IFN-gamma and IL-6 in aged Trained and 12-week HRLF rats, compared to young Trained and HRLF rats (p < 0.05 and p < 0.001, respectively, each). IL-6 was also increased in aged 12-week HRLF versus aged normal controls (p < 0.05). Serum IFN-gamma and MIP2 levels were also increased in young 6-week HRLF rats, but no cytokines were above baseline levels in young 12-week HRLF rats. Grip strength declined in both young and aged 12-week HRLF rats, compared to naïve and normal controls (p < 0.05 each), but these declines correlated only with IL-6 levels in aged rats (r = -0.39).</p> <p>Conclusion</p> <p>Aging enhanced a serum cytokine response in general, a response that was even greater with repetitive task performance. Grip strength was adversely affected by task performance in both age groups, but was apparently influenced by factors other than serum cytokine levels in young rats.</p

A demonstration of interstellar navigation using new horizons

As NASA’s New Horizons spacecraft exits the solar system bound for interstellar space, it has traveled so far that the nearest stars have shifted markedly from their positions seen from Earth. We demonstrated this by imaging the Proxima Centauri and Wolf 359 fields from Earth and New Horizons on 2020 April 23, when the spacecraft was 47.1 au distant. The observed parallaxes for Proxima Centauri and Wolf 359 are 32.″4 and 15.″7 , respectively. These measurements are not of research grade, but directly seeing large stellar parallaxes between two widely separated simultaneous observers is vividly educational. Using the New Horizons positions of the two stars alone, referenced to the three-dimensional model (3D) of the solar neighborhood constructed from Gaia DR3 astrometry, further provides the spacecraft spatial position relative to nearby stars with 0.44 au accuracy. The range to New Horizons from the solar system barycenter is recovered to 0.27 au accuracy, and its angular direction to 0.°4 accuracy, when compared to the precise values from NASA Deep Space Network tracking. This is the first time optical stellar astrometry has been used to determine the 3D location of a spacecraft with respect to nearby stars and the first time any method of interstellar navigation has been demonstrated for a spacecraft on an interstellar trajectory. We conclude that the best astrometric approach to navigating spacecraft on their departures to interstellar space is to use a single pair of the closest stars as references, rather than a large sample of more distant stars

Damage tolerance analysis of bonded joints on helicopter’s blade leading edge. Study of defaults solicited in mode I and II, in static and fatigue in different environmental conditions

Cette thèse concerne l'analyse de propagation de dommages dans une structure hybride métal/composite assemblée par collage structural. L'approche choisie est basée sur l'identification expérimentale du taux de restitution d'énergie, G, pour une sollicitation en mode I et II. L'éprouvette de type DCB (Double Cantilever Beam), qui a d’abord été adaptée pour être représentative de la structure hybride, permet de construire la R-Curve (évolution de G en fonction de la longueur de fissure, a) et d'étudier la cinétique de propagation de fissure sous sollicitations dynamiques. La même étude a été portée sur l’éprouvette ENF (End Notched Flexure). Une machine d’essais a été créée afin de réaliser les essais quasi-statiques et dynamiques. Un caisson thermique a été conçu pour faire des essais en température et regarder son impact sur les propriétés de la mécanique de rupture des adhésifs. L'originalité de ce travail est le pilotage des essais dynamiques à ΔG imposé, ce qui permet de s'affranchir de la dépendance de G à la longueur du dommage pour le mode I.Les résultats obtenus mettent en évidence les variations des vitesses de propagation (da/dN) à différentes conditions environnementales en mode I et II sur des assemblages composite/métal collés.This thesis explains the analysis of damage propagation in a metallic/composite hybrid structure, assembled with structural adhesives. The chosen approach is based on the experimental identification of the energies release rates for a solicitation in mode I and II. The DCB (Double Cantilever Beam) specimen, which design was first adapted in order to adequately represent the hybrid structure, allows the construction of the R-Curve (evolution of G versus the crack length, a) and the study of the crack speed propagation under dynamic solicitations. The same study was carried out on the ENF specimen (End Notched Flexure).A testing machine was created in order to perform quasi-static and dynamic tests. A thermal chamber was designed to carry out temperature tests and observe the impact of the latter on the fracture mechanics properties of the adhesives. Performing dynamic tests with an imposed ΔG, which allows one to overcome the dependence of G to the damage length in mode I, is what makes this work original.The obtained results highlight the variation of the speed propagation in different environmental conditions, for mode I and II, on composite/metal bonded assemblies

Theoretical and experimental investigation of all-optical gain-clamped discrete fiber raman amplifiers

Using numerical simulations, we design and analyze the performance of gain-clamped discrete fiber Raman amplifiers. In particular, we investigate a configuration which generates a feedback signal through the use of fiber Bragg gratings. We examine the impact of the feedback wavelength on the gain-clamping properties.From the simulation results, we conclude that in order to achieve uniform gain-clamping across the DWDM band of interest, the optical pumps must be depleted evenly by the feedback signal. The effect of the feedback signal on the amplifier may be mostly predicted based on the Raman gain coefficients corresponding to the frequency separation between the feedback signal and the pumps. A 58 nm wide uniformly gain-clamped Raman amplifier having over 20 dB gain and a critical power of -3 dBm is developed.We also verify gain-clamping for this configuration experimentally

The usefulness of electrodiagnostic consultation in an outpatient clinic

The aim of this study was to record all patients referred to a private outpatient clinic for electrodiagnostic consultation during one calendar year. The demographic data of the patients, the specialty of the referring physicians, the referral diagnosis, the electromyographic (EMG) diagnosis and the concordance of referral and EMG diagnosis among all the referring physician&apos;s specialties were recorded. There were one thousand patients (385 men and 615 women). 65.7% of the patients were referred from orthopedists and 22.4% from neurologists. EMG was normal in 498 patients (49.8%). Abnormal in 47.3% of the patients referred by orthopedists and 58.9% of those referred by neurologists. Carpal tunnel syndrome (CTS) was the most frequent electrophysiological diagnosis (26.8%), followed by polyneuropathy (8.9%), radiculopathy (7.1%) and mononeuropathy (4.6%). In this study electrodiagnostic consultation was abnormal in only half of the referred patients. The high proportion of normal EDX tests in this study denotes the need for more accurate clinical diagnosis in order to reduce the time spent and resources. The orthopedist is the initial physician to whom patients with neuromuscular symptoms are seen in the majority of cases. Neurologists seem to be more familiar with neuromuscular symptoms and diseases. © 2019 Elsevier Lt

Information wars: assessing the social media battlefield in Syria

Efforts to understand the nuances inherent to the political turmoil in Syria present daunting challenges. While the numerous insurgent factions and the Syrian security forces engage each other in combat in towns and cities to secure tangible battlefield gains, the warring parties are also waging a contentious information war in cyberspace, specifically within the virtual arena of online social media. The various strands of the opposition in Syria—political and violent—have taken to social media since the earliest stages of the uprising to advance their agendas. Analogous to their role in facilitating communication and information exchange during the wave of revolts that have been sweeping the Arab world since 2011, new media platforms such as the array of social media websites and related technologies that are available to the public at virtually little or no cost have become crucial to shaping how the crisis in Syria is portrayed and perceived. This article examines the social media battlefield in the Syrian uprising with specific attention on the Free Syrian Army’s online activities. It also addresses the relative impact of the social media battlefield on dictating the course of events in Syria