Isokinetic strength testing in research and practice.

Age-related losses in lower extremity strength result in functional disabilities that diminish the quality of life for many older adults. Multiple factors, including type of muscle fiber, size of the muscle, length and speed of the muscle at contraction, age, and gender, affect the magnitude of strength generated. Assessment in clinical practice, in order to be cost and time effective, screens older adults for loss in strength. Further evaluation of strength loss requires the use of sophisticated procedures and equipment. Research into the causes of loss of strength and interventions to lessen or prevent loss of strength requires valid and reliable assessment tools. This article examines components of isokinetic muscle strength, the measurement of strength in clinical practice, methods to measure isokinetic strength, and validity and reliability of these measures.

Difference between blocking and Néel temperatures in the exchange biased Fe3O4/CoO system.

The blocking temperature T(B) has been determined as a function of the antiferromagnetic layer thickness in the Fe3O4/CoO exchange biased system. For CoO layers thinner than 50 A, T(B) is reduced below the Néel temperature T(N) of bulk CoO (291 K), independent of crystallographic orientation or film substrate ( alpha-Al2O3, SrTiO3, and MgO). Neutron diffraction studies show that T(B) does not track the CoO ordering temperature and, hence, that this reduction in T(B) does not arise from finite-size scaling. Instead, the ordering temperature of the CoO layers is enhanced above the bulk T(N) for layer thicknesses approximately less than or equal to 100 A due to the proximity of magnetic Fe3O4 layers.