For a typical steel framed 30 ft by 30 ft office building bay, the fre-quency will be in the 5-8 Hz range. Frequency is a function of span (the longer the span, the lower the frequen-cy) and weight supported (the heavier the floor and the supported contents, the lower the frequency).
Anxiety doesn't appear to cause any dramatic changes to your skin color. You're not going to turn blue or purple. But some degree of skin color change is normal with anxiety and stress, especially under extreme anxiety like during a panic attack.
Skin Diseases That Cause Dark Spots. 1  Melasma: Itâs one of the commonest causes of grayish patches on the face. 2  Riehlâs Melanosis: It causes grayish or brownish patches on your face resulting from hyper-pigmentation. 3  Poikiloderma of Civatte: This mostly affects the neck area that has been exposed to sunâs rays.