Without variable valve timing or variable valve lift, the valve timing must be the same for all engine speeds and conditions, therefore compromises are necessary. An engine equipped with a variable valve timing actuation system is freed from this constraint, allowing performance to be improved over the engine operating range.
A variety of medical specialists treat people with osteoporosis, including internists, gynecologists, family doctors, endocrinologists, rheumatologists, physiatrists, orthopaedists, and geriatricians. There are a number of ways to find a doctor who treats osteoporosis patients. If you have a primary care or family doctor, discuss your concerns with him or her. Your doctor may treat the disease or be able to refer you to an osteoporosis specialist.
Primary-care doctors or dermatologists can treat psoriatic arthritis, but psoriatic arthritis patients should consider seeing a rheumatologist, a doctor who specializes in arthritis. There is no definitive test for psoriatic arthritis. The diagnosis is made mostly on a clinical basis and by a process of elimination. Medical history, physical examination, blood tests, MRIs and X-rays of the joints that have symptoms may be used to diagnose psoriatic arthritis. It is important to communicate your history of psoriasis to your doctor.