Motor Pool

Examples of Motor Pool in the following topics:

• Motor Units

  • A motor unit consists of the motor neuron and the grouping of muscle fibers innervated by the neuron.
  • Thus, small motor units can exercise greater precision of movement compared to larger motor units.
  • Groups of motor units are innervated to coordinate contraction of a whole muscle and generate appropriate movement; all of the motor units within a muscle are considered a motor pool.
  • There are often multiple sizes of motor unit within a motor pool as a means of modulating the precision and force produced by a single muscle.
  • These multiple motor units of different sizes within a motor pool allow for very fine control of force either spatially or temporally.

• Overview of Motor Integration

  • A motor unit is comprised of a single alpha-motor neuron and all the muscle fibers it innervates.
  • When a motor unit is activated, all of its fibers contract.
  • All of the motor units that subserve a single muscle are considered a motor unit pool.
  • Motor unit recruitment is a measure of how many motor neurons are activated in a particular muscle.
  • These small motor units may contain only 10 fibers per motor unit.

• Motor Areas

  • The motor areas of the brain are located in both hemispheres of the cortex.
  • The right half of the motor area controls the left side of the body, and the left half of the motor area controls the right side of the body.
  • Premotor cortex: Located anterior to the primary motor cortex, it is responsible for some aspects of motor control.
  • It is located on the midline surface of the hemisphere anterior to the primary motor cortex.
  • Various experiments examining the motor cortex map showed that each point in motor cortex influences a range of muscles and joints, indicating significant overlapping in the map.

• Reducing the costs of operating electric motors

  • The golden rule in reducing the cost of running a motor is to ensure that it's the right-size motor for the job.
  • Many businesses run motors that are too big for the task under the assumption that the additional horsepower may be needed in the future.
  • Over-sized (and therefore under-loaded) motors waste energy and cost more to run.
  • In many cases running two smaller energy-efficient motors can actually cost less than operating one over-sized motor.

• Introduction to Motors and Pumps

  • Motors are ubiquitous.
  • In fact, motors use up so much electricity that the amount they consume over their lifetime always costs more than the price of the motors themselves (some motors actually consume, in electricity costs, the amount of their purchase price every few weeks).
  • Compare these figures to an older model 100 horsepower motor running continuously at full load (as many motors are designed to do), which can cost $70,000 a year to operate – or an older 20 horsepower motor, which can consume up to $14,000 worth of electricity annually.
  • That's about six times the purchase price of the motor.
  • Diesel or gasoline motors can be even more costly.

• Organization of Motor Neuron Pathways

  • The motor pathway, also called the pyramidal tract or the corticospinal tract, serves as the motor pathway for upper motor neuronal signals coming from the cerebral cortex and from primitive brainstem motor nuclei.
  • The motor impulses originate in the giant pyramidal cells (Betz cells) of the motor area, i.e., precentral gyrus of the cerebral cortex.
  • These are the upper motor neurons of the corticospinal tract.
  • Peripheral motor nerves carry the motor impulses from the anterior horn to the voluntary muscles.
  • The midbrain nuclei include four motor tracts that send upper motor neuronal axons down the spinal cord to lower motor neurons.

• Foster Pools of Expertise in Multiple Places

• Voting as Political Participation

  • The pool of eligible voters has expanded from primarily white, male property owners at the founding, to include black men after the Civil War, women after 1920, and eighteen- to twenty-year-olds after 1971.
  • In 1993, Congress passed the National Voter Registration Act of 1993, also known as the "motor voter" law, allowing citizens to register at motor vehicle and social service offices.
  • "Motor voter's" success in increasing the ranks of registered voters differs by state depending on how well the program is publicized and executed.

• Determining the true costs of a motor

  • In the long run, however, motors designed to be more efficient always end up costing less.
  • The efficiency rating and amount of time the motor will be in operation are also needed.
  • For example, the normal lifespan of a typical 100 horsepower motor is around 40,000 hours or about five years of continuous operation (although a well-maintained motor can last much longer).
  • For example, the difference between a 96%-efficient 100 horsepower motor and a 92%-efficient 100 horsepower motor is four percentage points.
  • The total ($20,000) shows how much extra will have to be paid in electricity over the life of the motor (assuming the motor is in continuous operation).

• Pooled standard deviation estimate (special topic)

  • In such cases, we can make our t distribution approach slightly more precise by using a pooled standard deviation.
  • The pooled standard deviation of two groups is a way to use data from both samples to better estimate the standard deviation and standard error.
  • Caution: Pooling standard deviations should be done only after careful research
  • A pooled standard deviation is only appropriate when background research indicates the population standard deviations are nearly equal.
  • When the sample size is large and the condition may be adequately checked with data, the benefits of pooling the standard deviations greatly diminishes.