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Analytical and experimental methods are used to determine the natural frequencies and mode shapes of Aluminum 6061-T651 beams with rectangular and circular cross-sections. A unique test stand is developed to provide the rectangular beam with different boundary conditions including clamped-free, clamped-clamped, clamped-pinned, and pinned-pinned. The first 10 bending natural frequencies and mode shapes for each set of boundary conditions are measured. The effect of the bolt torque on the measured natural frequencies is examined. A new technique is used to mount an accelerometer on the circular beam to measure its torsional modes; its first 20 natural frequencies and first 10 mode shapes are measured. The measured natural frequencies and mode shapes of both beams are compared with their theoretical predictions. The Timoshenko beam theory is shown to provide better predictions of the higher bending natural frequencies of the circular beam than the Bernoulli-Euler beam theory. The material properties of the circular beam, including the elastic modulus, shear modulus, and Poisson's ratio, are determined accurately. The use of the rectangular and circular beam test stands as a teaching tool for undergraduate and graduate students is discussed. The laboratory demonstration using the test stands was well received by students in the undergraduate vibrations class.

Objective. The aim of this study was to identify serum markers that are modulated by an investigational anti-IFN-α mAb, sifalimumab, in adult DM or PM patients.Methods. In a phase 1b clinical trial, sera were collected from a total of 48 DM or PM adult patients receiving either placebo for 3 months or sifalimumab for 6 months. Samples were tested for 128 selected proteins using a multiplex luminex immunoassay. Muscle biopsies from selected patients were stained for T cell infiltration using an anti-CD3 antibody.Results. A robust overexpression of multiple serum proteins in DM or PM patients was observed, particularly in patients with an elevated baseline type I IFN gene signature in the blood or muscle. Neutralization of the type I IFN gene signature by sifalimumab resulted in coordinated suppression of T cell-related proteins such as soluble IL-2RA, TNF receptor 2 (TNFR2) and IL-18. Muscle biopsies from two patients with the highest serum protein suppression were selected and found to have a pronounced reduction of muscle T cell infiltration. Down-regulation of IL-2RA correlated with favourable manual muscle test 8 (MMT-8) alterations in sifalimumab-dosed patients.Conclusion. A reduced level of multiple T cell-associated proteins after sifalimumab but not placebo administration suggests a suppressive effect of blocking type I IFN signalling on T cell activation and chemoattraction that may lead to a reduction of T cell infiltration in the muscle of myositis patients. Further, soluble IL-2RA changes from baseline may serve as a responsive and/or predictive marker for type I IFN-targeted therapy in adult DM or PM patients. [ABSTRACT FROM PUBLISHER]