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To detect white matter abnormalities in patients with mild Alzheimer disease (AD) by diffusion tensor imaging and to determine their topographic relationship with gray matter atrophy.

The crack tip opening displacement (CTOD), δp, in the plastic zone at a crack tip has been determined according to the dislocation-free zone (DFZ) theory. From this, the total CTOD, δT, can be obtained. It follows that the total CTOD range, ΔδT under an applied cyclic stress can be achieved through a transposition from monotonic loading to cyclic loading. Under the assumption that when Δδr ≥ Δδcrita fatigue crack can propagate, where Δδcrit is the critical CTOD range which corresponds to the fatigue crack propagation threshold ΔKth, then a very simple relationship between ΔKth and the yield strength, σ, is obtained, namely [image omitted] where m and n are constants. This formula is in good agreement with experimental results in the literature.

We describe a rare pituitary cryptococcoma in an immunocompetent patient, with radiological features similar to those of a pituitary macroadenoma. Although unusual, it should be added to the list of differential diagnosis of pituitary masses. Contrast enhancement of adjacent meninges differentiated the lesion from an adenoma.