525 research outputs found

    Convolution operators supporting hypercyclic algebras

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    [EN] We show that any convolution operator induced by a non-constant polynomial that vanishes at zero supports a hypercyclic algebra. This partially solves a question raised by R. AronThis work is supported in part by MICINN and FEDER, Project MTM2013-47093-P, and by GVA, Project ACOMP/2015/005.Bès, JP.; Conejero, JA.; Papathanasiou, D. (2017). Convolution operators supporting hypercyclic algebras. Journal of Mathematical Analysis and Applications. 445(2):1232-1238. https://doi.org/10.1016/j.jmaa.2016.01.029S12321238445

    A mesoscopic model for microscale hydrodynamics and interfacial phenomena: Slip, films, and contact angle hysteresis

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    We present a model based on the lattice Boltzmann equation that is suitable for the simulation of dynamic wetting. The model is capable of exhibiting fundamental interfacial phenomena such as weak adsorption of fluid on the solid substrate and the presence of a thin surface film within which a disjoining pressure acts. Dynamics in this surface film, tightly coupled with hydrodynamics in the fluid bulk, determine macroscopic properties of primary interest: the hydrodynamic slip; the equilibrium contact angle; and the static and dynamic hysteresis of the contact angles. The pseudo- potentials employed for fluid-solid interactions are composed of a repulsive core and an attractive tail that can be independently adjusted. This enables effective modification of the functional form of the disjoining pressure so that one can vary the static and dynamic hysteresis on surfaces that exhibit the same equilibrium contact angle. The modeled solid-fluid interface is diffuse, represented by a wall probability function which ultimately controls the momentum exchange between solid and fluid phases. This approach allows us to effectively vary the slip length for a given wettability (i.e. the static contact angle) of the solid substrate

    Isokinetic Evaluation of the Elbow Joint at 45° and 80° of Shoulder Abduction

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    Since Hislop and Thistle published the first reports on isokinetic exercise, a lot of progress has been made towards the use of isokinetic exercise and isokinetic evaluation of muscle and joint performance in sports and orthopedic physical therapy. Cybex II+ with the Cybex Data Reduction Computer is one of the most widely used isokinetic systems for research and rehabilitation purposes. There are more than 500 published works describing the use of Cybex in various applications, Many investigations have used the Cybex isokinetic system to develop normative data on torque and work measurements of various muscle groups. Normative data are valuable to clinicians in the evaluation of the severity of an injury in terms of muscle performance deficits. In addition, such data provide physical therapists with objective data in setting rehabilitation goals, and enabling sports medicine experts to identify functional deficiencies during screening of athletes. There is a limited number of published works that have developed normative data for elbow flexor and extensor muscle groups. While there is some information about peak torque and agonist-antagonist ratios, minimal information is available about torque acceleration energy, work endurance ratios, average power and flexion-extension total work ratios. The purpose of this study was to examine the effects of 450 and 800 of shoulder abduction on torque and work measurements of the elbow joint. In addition, normative data for elbow flexion and extension at both arm positions (testing positions suggested by Cybex) were developed

    Marginal discoloration of all-ceramic restorations cemented adhesively versus nonadhesively

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    BACKGROUND: The authors conducted a systematic review to correlate the clinical incidence of marginal discoloration of all-ceramic restorations with the mode of cementation (adhesive versus nonadhesive). TYPES OF STUDIES REVIEWED: The authors conducted a literature search by using electronic databases, relevant references, database citations and journal hand searches for clinical studies of marginal discoloration of all-ceramic restorations with a mean follow-up time of at least five years. The search period spanned January 1990 through February 2011. The authors reported and compared summary estimates and five-year event rates. RESULTS: The authors selected 16 studies for final analysis from an initial yield of 346 articles. The mean observation time ranged between five and 10 years. The majority of studies used adhesive luting procedures for definitive cementation. In only one study did investigators report regarding the incidence of marginal discoloration of both adhesively and nonadhesively cemented all-ceramic restorations, and the difference between the luting types in terms of discoloration was not statistically significant (P = .5). CLINICAL IMPLICATIONS: The results of this systematic review showed that there is a lack of studies with findings regarding marginal discoloration rates of nonadhesively luted all-ceramic restorations. Unacceptable marginal discoloration rates of adhesively luted all-ceramic prostheses were relatively low even at 10 years of service
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