State-space control of prosthetic hand shape.

In the field of neuroprosthetic control, there is an emerging need for simplified control of high-dimensional devices. Advances in robotic technology have led to the development of prosthetic arms that now approach the look and number of degrees of freedom (DoF) of a natural arm. These arms, and especially hands, now have more controllable DoFs than the number of control DoFs available in many applications. In natural movements, high correlations exist between multiple joints, such as finger flexions. Therefore, discrepancy between the number of control and effector DoFs can be overcome by a control scheme that maps low-DoF control space to high-DoF joint space. Imperfect effectors, sensor noise and interactions with external objects require the use of feedback controllers. The incorporation of feedback in a system where the command is in a different space, however, is challenging, requiring a potentially difficult inverse high-DoF to low-DoF transformation. Here we present a solution to this problem based on the Extended Kalman Filter.

Homicide surveillance--United States, 1979-1988.

From 1979 through 1988, 217,578 homicides occurred in the United States, an average of greater than 21,000 per year. Homicide rates during this 10-year period were about 1.5 times higher than the rates during the 1950s. The national homicide rate of 10.7/100,000 in 1980 was the highest ever recorded. Homicide occurs disproportionately among young adults. Among the 15- to 34-year age group, homicide is the fourth most common cause of death among white females, the third most common cause among white males, and the most common cause among both black females and black males. In 1988, nearly two-thirds (61%) of homicide victims were killed with a firearm, 75% of these with a handgun. More than half (52%) of homicide victims were killed by a family member or acquaintance, and about one-third (35%) of homicides stemmed from a conflict not associated with another felony. The homicide mortality rate among young black males 15-24 years of age has risen 54% since 1985. Ninety-nine percent of the increase was accounted for by homicides in which the victim was killed with a firearm. The surveillance data summarized in this report should assist public health practitioners, researchers, and policymakers in addressing this important public health problem.