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The coronavirus disease 2019 (covid-19) pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 has necessitated changes to the way patients with chronic diseases are managed. Given that patients with multiple myeloma are at increased risk of covid-19 infection and related complications, national bodies and experts around the globe have made recommendations for risk mitigation strategies for those vulnerable patients. Understandably, because of the novelty of the virus, many of the proposed risk mitigation strategies have thus far been reactionary and cannot be supported by strong evidence. In this editorial, we highlight some of the risk mitigation strategies implemented at our institutions across Canada during the first wave of covid-19, and we discuss the considerations that should be made when managing patients during the second wave and beyond. [ABSTRACT FROM AUTHOR]

In this paper the subject of friction prediction is revisited, with the aim of obtaining a general formula predicting the coefficient of friction over a wide range of operating conditions. By means of full numerical simulations of the smooth isothermal elliptic contact, and assuming an Eyring non-Newtonian behavior, the coefficient of friction is computed for a wide range of operating conditions. It is shown that with respect to sliding friction, all results can be presented on a single generalized friction curve relating a reduced coefficient of friction to a characteristic nondimensional shear stress. Finally, it is shown that some measured data presented in the literature when presented in terms of the derived parameters closely follow the derived behavior, which provides a validation of the theoretical results. [DOI: 10.1115/1.1308021]

In view of increasingly severe operating conditions and the use of composite (strongly) heterogeneous materials, detailed modelling and optimisation methods are needed to predict the effects of subsurface material topology, either by design or resulting from inclusions and material anisotropy, on rolling-sliding contact fatigue life. In this paper, a method is proposed showing that such predictions can at present be obtained for realistic configurations on small-scale computers by integrating efficient numerical solution of the 3D displacement and stress field in the (heterogeneous) material with fast rough surface-lubricated contact models.Contact pressures, subsurface stresses and surface fatigue effects are shown for cases of bonded individual or multiple (clusters) of statistically distributed inhomogeneities close to the surface in realistic actual rolling–sliding rough contact geometries. The model contributes to the development of optimised failure criteria for composite/heterogeneous materials close to the surface. [ABSTRACT FROM AUTHOR]

A high-order polynomial gas distribution cam mechanism is investigated theoretically from the viewpoint of thermal elastohydrodynamic lubrication (EHL). First, a cam with a larger base circle radius is employed, which results in slide-roll ratio 2.0 < S <9.0 when the two surfaces move oppositely. The pressure, film thickness, and temperature profiles at a number of angular positions of the cam are presented, together with the isothermal results. The comparison between thermal and isothermal oil characteristics is also shown. It is revealed that the isothermal analysis partly overestimates the actual film thickness and it also misses some essential local phenomena. Second, a cam with a smaller base circle radius is studied, which leads to drastic variations in the slide-roll ratio which encounters four times' occurrences of infinity in one working period. The pressure, film thickness, and temperature profiles at some angular cam positions together with the oil characteristics are given, showing much dramatic variations. A very small film thickness is observed at the contact of the tappet with the start of the cam basic segment, which suggests a possible risk of direct contact of both surfaces. [ABSTRACT FROM AUTHOR]

The effect of single-sided and double-sided harmonic surface waviness on the film thickness, pressure, and temperature oscillations in an elastohydrodynamically lubricated eccentric-tappet pair has been investigated in relation to the eccentricity and the waviness wavelength. The results show that, during one working cycle, the waviness causes significant fluctuations of the oil film, pressure, and temperature, as well as a reduction in minimum film thickness. Smaller wavelength causes more dramatic variations in oil film. The fluctuations of the pressure, film thickness, temperature, and traction coefficient caused by double-sided waviness are nearly the same compared with the single-sided waviness, but the variations are less intense. [ABSTRACT FROM AUTHOR]

Somatic mosaicism is present in slightly more than 50% of small supernumerary marker chromosome (sSMC) carriers. Interestingly, non-acrocentric derived sSMC show mosaicism much more frequently than acrocentric ones. sSMC can be present in different mosaic rates, which may go below 5% of the studied cells. Also cryptic mosaicism can be present and mosaics may be differently expressed in different tissues of the body. Even though in the overwhelming majority of the cases somatic sSMC mosaicism has no direct clinical effect, there are also cases with altered clinical outcomes due to mosaicism. Also clinically important is the fact that a de novo sSMC, even present in mosaic, may be a hint of uniparental disomy (UPD). As it is under discussion to possibly replace standard karyotyping by methods like array-CGH, the impracticality of the latter to detect low-level sSMC mosaics and/or UPD has to be considered as well. Overall, sSMC mosaicism has to be studied carefully in each individual case, as it can be extremely informative and of importance, especially for prenatal genetic counseling. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The prediction of bearing life and performance requires detailed knowledge of the behaviour of elasto-hydrodynamically lubricated (EHL) contacts under varying conditions of load and lubricant supply during many load cycles. Considering starved lubrication, a model is developed that predicts the change of the supply layer to the EHL contact. As the film thickness inside a starved EHL contact is determined by the thickness and distribution of the supply layer, this model can be used to predict the film thickness decay. A formula for the central film thickness decay is obtained for the long-term operation of circular or elliptical contacts under starved conditions. The model is validated experimentally. [ABSTRACT FROM AUTHOR]

This article traces the contribution of the Dowson and Higginson work to numerical line contact elasto-hydrodynamic lubricated film thickness prediction and the Hamrock and Dowson contribution to the film thickness prediction in elliptical contacts. Considering the line contact work, this article shows that both the numerical pressure and film thickness results and the curve-fitted film thickness predictions are very accurate, even by today's standards. Concerning the elliptical results, the authors show that the original predictions remain surprisingly accurate but that the issue of the minimum to central film thicknesss ration Hm/Hc is not yet completely settled. The article then continues to discuss some limitations of the current models that require additional work, mainly in the area of realistic non-Newtonian lubricant rheology for film thickness predictions and pressure spike analysis. [ABSTRACT FROM AUTHOR]