Comparative Analysis of Eccentric Glenosphere in Reverse Total Shoulder Arthroplasty: A Computer Simulation Study.

Objective: The aim was to evaluate the effects of different glenosphere eccentricities on impingement, range of motion (ROM), and muscle length during standard activities in reverse total shoulder arthroplasty (RSA). Methods: In this study, we utilized computational modeling techniques to create native shoulder and shoulder models undergoing RSA and simulate shoulder movements in all abduction-adduction, flexion-extension, and rotation. We tested a total of 36 different glenosphere configurations, which included three different inferior tilts (0°, +10°, +20°) and two different lateral offsets (0 mm and +4 mm), as well as six different glenosphere eccentricities (concentricity, inferior, posterior, anterior, anteroinferior, and posteroinferior). We evaluated the maximum impingement-free ROM, impingement sites, and muscle lengths. Results: All glenosphere configurations exceeded 50% of native shoulder ROM in three planes and total global ROM. In abduction-adduction, there was no significant difference among the different glenosphere eccentricities (p > 0.05). In flexion-extension, the posteroinferior eccentricity had the maximum ROM among the different eccentricities, but no significant difference among the different glenosphere eccentricities (p > 0.05). In rotation, there was a significant difference overall, and anteroinferior eccentricity had a significant advantage over concentricity (p < 0.05). In total global ROM, anteroinferior eccentricity had a significant advantage over concentricity when lateral offset was 0 mm (p < 0.05). In all models of glenosphere eccentricities, only the elongation of the infraspinatus muscle was statistically significant (p < 0.05). Conclusion: Glenosphere eccentricity significantly influenced rotation, total global ROM, and the length of the subscapularis muscle. Among them, anteroinferior offset achieved the maximum ROM in abduction-adduction, rotation, and total global activities. Both anteroinferior and inferior glenoid eccentricity showed significant advantages over the concentricity in rotation and total global ROM. Level of Evidence: Basic Science Study; Computer Modeling.

The orbital eccentricity distribution of planets orbiting M dwarfs.

We investigate the underlying distribution of orbital eccentricities for planets around early-to-mid M dwarf host stars. We employ a sample of 163 planets around early- to mid-M dwarfs across 101 systems detected by NASA's Kepler Mission. We constrain the orbital eccentricity for each planet by leveraging the Kepler lightcurve together with a stellar density prior, constructed using metallicity from spectroscopy, Ks magnitude from 2MASS, and stellar parallax from Gaia. Within a Bayesian hierarchical framework, we extract the underlying eccentricity distribution, assuming alternately Rayleigh, half-Gaussian, and Beta functions for both single- and multi-transit systems. We described the eccentricity distribution for apparently single-transiting planetary systems with a Rayleigh distribution with [Formula: see text], and for multitransit systems with [Formula: see text]. The data suggest the possibility of distinct dynamically warmer and cooler subpopulations within the single-transit distribution: The single-transit data prefer a mixture model composed of two distinct Rayleigh distributions with [Formula: see text] and [Formula: see text] over a single Rayleigh distribution, with 7:1 odds. We contextualize our findings within a planet formation framework, by comparing them to analogous results in the literature for planets orbiting FGK stars. By combining our derived eccentricity distribution with other M dwarf demographic constraints, we estimate the underlying eccentricity distribution for the population of early- to mid-M dwarf planets in the local neighborhood.

The role of peripheral vision during decision-making in dynamic viewing sequences.

Decision-making in team sports necessitates monitoring multiple performers located at different distances (i.e., viewing eccentricities) from a critical information source. The processing of peripheral information is generally impaired under anxiety and when responding to stimuli located at larger eccentricities. These hypotheses have not been sufficiently tested in dynamic performance environments. We examined how pressure and eccentricities affect decision-making and visual behaviour in 4v4 basketball defensive scenarios using a head mounted display. Experienced players monitored plays from the first-person perspective (centre position) and made defensive steps towards opponents threatening the basket from different eccentricities under low- and high-pressure. To tax working memory, participants simultaneously performed a backward counting task. Players responded slower and with lower accuracy to opponents at larger eccentricities. Players mostly fixated on the ball-carrier, but over 50% of fixations were located on peripheral players, indicating that information in the periphery must be frequently updated with foveal vision (i.e., pivot strategy). When pressured, participants increased mental effort and improved counting performance; however, gaze behaviour and decision-making were relatively unaffected. Findings suggest that basketball players respond more quickly to opponents positioned at lower compared to higher eccentricities at the cost of impaired responses to opponents in the periphery.

Do myopes have deficits in peripheral flicker sensitivity?

Purpose: Signals from the peripheral retina are important for myopia development. Unlike temporal vision, deficits in peripheral spatial visual functions of myopes have been investigated previously. This study investigated temporal contrast thresholds in emmetropes and myopes at different retinal eccentricities.Methods: Forty-four young adults (mean age 23 ± 3 years) including 21 emmetropes (Spherical Equivalent (SE): +0.01 ± 0.30D) and 23 myopes (SE: -3.98 ± 2.41D) participated in this prospective study. Flicker modulation thresholds (FMT) were determined monocularly (right eye) for 15 Hz flicker stimulus at 0°, nasal (23°, 10°) and temporal (-23°, -10°) retinal eccentricities along the horizontal meridian. FMTs were measured psychophysically using 5-adaptive interleaved staircases and threshold was taken as the average of the last 6 reversals.Results: In both the groups (emmetropes and myopes), there was a naso-temporal asymmetry in FMTs with higher thresholds in the far temporal retina (Median; Interquartile range: 40.97%; 17.06) than the nasal retina (28.07%; 9.36) (p < 0.001). Flicker modulation thresholds were significantly higher in myopes (30.58%; 12.15) compared to emmetropes (26.77%; 7.74; p = 0.04) at far nasal retina (23°), while at other eccentricities there was no effect (p > 0.05). Further sub-analysis revealed only high myopes (34.48 %, 21.9) showed significantly higher FMT compared to emmetropes (26.77%; 7.74; p = 0.04).Conclusion: Greater FMTs were seen in high myopes than that of emmetropes in the nasal retina. Further studies exploring the structural aspects of the myopic eye with FMT would provide a better understanding of role of flicker sensitivity in myopiogenesis. (AU)

Do myopes have deficits in peripheral flicker sensitivity?

PURPOSE: Signals from the peripheral retina are important for myopia development. Unlike temporal vision, deficits in peripheral spatial visual functions of myopes have been investigated previously. This study investigated temporal contrast thresholds in emmetropes and myopes at different retinal eccentricities. METHODS: Forty-four young adults (mean age 23 ± 3 years) including 21 emmetropes (Spherical Equivalent (SE): +0.01 ± 0.30D) and 23 myopes (SE: -3.98 ± 2.41D) participated in this prospective study. Flicker modulation thresholds (FMT) were determined monocularly (right eye) for 15 Hz flicker stimulus at 0°, nasal (23°, 10°) and temporal (-23°, -10°) retinal eccentricities along the horizontal meridian. FMTs were measured psychophysically using 5-adaptive interleaved staircases and threshold was taken as the average of the last 6 reversals. RESULTS: In both the groups (emmetropes and myopes), there was a naso-temporal asymmetry in FMTs with higher thresholds in the far temporal retina (Median; Interquartile range: 40.97%; 17.06) than the nasal retina (28.07%; 9.36) (p < 0.001). Flicker modulation thresholds were significantly higher in myopes (30.58%; 12.15) compared to emmetropes (26.77%; 7.74; p = 0.04) at far nasal retina (23°), while at other eccentricities there was no effect (p > 0.05). Further sub-analysis revealed only high myopes (34.48 %, 21.9) showed significantly higher FMT compared to emmetropes (26.77%; 7.74; p = 0.04). CONCLUSION: Greater FMTs were seen in high myopes than that of emmetropes in the nasal retina. Further studies exploring the structural aspects of the myopic eye with FMT would provide a better understanding of role of flicker sensitivity in myopiogenesis.

Analysis of Failure Mechanism in Joints with Positive Eccentricity in CFS Truss.

The paper presents studies concerning the load-bearing capacity of truss joints with a positive eccentricity resulting from the arrangement of geometric members and the failure mechanisms observed in the joints. Based on the previously conducted experimental study, a numerical model of the tested fragment of the CFS truss with eccentricity in the joint was created and validated. All structural details of the tested truss and the loading method consistent with the experiment were taken into account. The results obtained from a uniaxial tensile tests on a steel samples and results estimated during destructive tests carried out on a full-scale of research model were taken into account in validation of the numerical model. Next, appropriate numerical analyses were carried out and parameters such as the eccentricity size in the joint and the wall thickness of sections (t = 1.0, 1.5 and 4.0 mm) were modified. In the range of the studied wall slenderness from λ > 70 (1.0 mm and 1.5 mm thick), it was confirmed that the resistance of truss joints made from CFS open cross-sections with a positive eccentricity, is greater than the resistance that results from known methods of steel structure dimensioning.

Exoplanet orbital eccentricities derived from LAMOST-Kepler analysis.

The nearly circular (mean eccentricity [Formula: see text]) and coplanar (mean mutual inclination [Formula: see text]) orbits of the solar system planets motivated Kant and Laplace to hypothesize that planets are formed in disks, which has developed into the widely accepted theory of planet formation. The first several hundred extrasolar planets (mostly Jovian) discovered using the radial velocity (RV) technique are commonly on eccentric orbits ([Formula: see text]). This raises a fundamental question: Are the solar system and its formation special? The Kepler mission has found thousands of transiting planets dominated by sub-Neptunes, but most of their orbital eccentricities remain unknown. By using the precise spectroscopic host star parameters from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) observations, we measure the eccentricity distributions for a large (698) and homogeneous Kepler planet sample with transit duration statistics. Nearly half of the planets are in systems with single transiting planets (singles), whereas the other half are multiple transiting planets (multiples). We find an eccentricity dichotomy: on average, Kepler singles are on eccentric orbits with [Formula: see text] 0.3, whereas the multiples are on nearly circular [Formula: see text] and coplanar [Formula: see text] degree) orbits similar to those of the solar system planets. Our results are consistent with previous studies of smaller samples and individual systems. We also show that Kepler multiples and solar system objects follow a common relation [[Formula: see text](1-2)[Formula: see text]] between mean eccentricities and mutual inclinations. The prevalence of circular orbits and the common relation may imply that the solar system is not so atypical in the galaxy after all.

Exoplanet orbital eccentricity: multiplicity relation and the Solar System.

The known population of exoplanets exhibits a much wider range of orbital eccentricities than Solar System planets and has a much higher average eccentricity. These facts have been widely interpreted to indicate that the Solar System is an atypical member of the overall population of planetary systems. We report here on a strong anticorrelation of orbital eccentricity with multiplicity (number of planets in the system) among cataloged radial velocity (RV) systems. The mean, median, and rough distribution of eccentricities of Solar System planets fits an extrapolation of this anticorrelation to the eight-planet case rather precisely despite the fact that no more than two Solar System planets would be detectable with RV data comparable to that in the exoplanet sample. Moreover, even if regarded as a single or double planetary system, the Solar System lies in a reasonably heavily populated region of eccentricity-multiplicity space. Thus, the Solar System is not anomalous among known exoplanetary systems with respect to eccentricities when its multiplicity is taken into account. Specifically, as the multiplicity of a system increases, the eccentricity decreases roughly as a power law of index -1.20. A simple and plausible but ad hoc and model-dependent interpretation of this relationship implies that ∼ 80% of the one-planet and 25% of the two-planet systems in our sample have additional, as yet undiscovered, members but that systems of higher observed multiplicity are largely complete (i.e., relatively rarely contain additional undiscovered planets). If low eccentricities indeed favor high multiplicities, habitability may be more common in systems with a larger number of planets.