Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Q: Abstract: Twenty years of published experience with the Workman-Armstrong equation for predicting walking VO2 is reviewed. The equation is reexpressed in currently accepted terminology, and it is shown that the equation serves well as a basic model of normal walking. Employing this model to analyze VO2/step leads to the elaboration of a three-compartment model of the metabolic cost of walking. This three-compartment model provides a rational estimate of the fraction of walking's metabolic cost that powers the actual walking movement. Doubt is expressed that "comfortable speed of walking" is definable in energy terms. It is suggested that the requirements of maintaining balance while walking may determine both the comfortable speed of walking and the curvilinearity of the relationship between ground-speed and freely chosen step frequency of walking.

A: Metabolic cost of walking: equation and model.
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Q: Abstract: The best treatment for diseases of the hip can begin if one diagnoses the disorder as soon as possible after onset. In many cases, successful management of the disease will prevent permanent damage to the hip joint. If injury occurs to the developing hip joint, major hip surgery may be necessary in adult life.

A: Diseases of the developing hip joint.
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Q: Abstract: Hepatitis B virus deoxyribonucleic acid (DNA) and antigens (HBsAg and HBcAg) were studied in liver biopsy specimens from 105 HBsAg-positive patients with chronic liver diseases. Free or integrated viral DNA, or both, was detected in 83 of 105 (79%) patients, whereas HBsAg and HBcAg were demonstrated immunohistologically in 96 (91%) and 39 (37%), respectively. Of 60 patients with detectable free viral DNA, 38 (63%) were positive for HBcAg, whereas only 1 of 45 (2%) with either integrated viral DNA alone (n = 23) or no detectable viral DNA (n = 22) was positive for HBcAg (p less than 0.001). Furthermore, the amount of HBcAg was positively correlated with the amount of free viral DNA in the liver tissue. In contrast, HBsAg was well expressed not only in the liver with free viral DNA, but also in the liver with integrated DNA. These data suggest that the synthesis of HBcAg is primarily directed by free viral DNA, whereas that of HBsAg may be directed by free as well as integrated viral DNAs.

A:
Correlation of hepatitis B virus DNA and antigens in the liver. A study in chronic liver disease.
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