compression

Examples of compression in the following topics:

• Spinal Cord Compression

  • Spinal cord compression occurs when the spinal cord is compressed by bone fragments.
  • Example symptoms of cord compression include back pain, a dermatome of increased sensation, paralysis below the compression, decreased sensation below the compression, and more.
  • Spinal cord compression develops when the spinal cord is compressed by bone fragments from a vertebral fracture, a tumor, abscess, ruptured intervertebral disc, or other lesion .
  • Symptoms suggestive of cord compression are back pain, a dermatome of increased sensation, paralysis of limbs below the level of compression, decreased sensation below the level of compression, urinary and fecal incontinence and/or urinary retention.
  • In spinal cord compression, the spinal cord (shown here) may be compressed by bone fragments from a vertebral fracture, a tumor, abscess, ruptured intervertebral disc, or other lesion.

• Format

  • For Unix and Unix-like operating systems, the convention is to use TAR format, compressed by compress, gzip, bzip, or bzip2.
  • For MS Windows, the standard method for distributing directory trees is zip format, which happens to do compression as well, so there is no need to compress the archive after creating it.
  • Producing compressed tar files (or tarballs) is pretty easy.
  • On some systems, the tar command can produce a compressed archive itself; on others, a separate compression program is used.

• Longitudinal Waves

  • Longitudinal waves, sometimes called compression waves, oscillate in the direction of propagation.
  • A sound wave contains pulses, which are the products of compressing the air (or other media) particles.
  • Some longitudinal waves are also called compressional waves or compression waves.
  • Sound waves are created by the compression of a medium, usually air.
  • A compressed Slinky is an example of a longitudinal wave.

• Sciatic Nerve Injury

  • Pain caused by a compression or irritation of the sciatic nerve by a problem in the lower back is called sciatica.
  • Sciatica is a set of symptoms including pain that may be caused by general compression or irritation of one of five spinal nerve roots that give rise to each sciatic nerve, or by compression or irritation of the left or right or both sciatic nerves .
  • Sciatica is generally caused by the compression of lumbar nerves L3, L4 or L5, or sacral nerves S1, S2, or S3, or by compression of the sciatic nerve itself.
  • Sciatica due to compression of a nerve root is one of the most common forms of radiculopathy.
  • Pseudosciatic pain can also be caused by compression of peripheral sections of the nerve, usually from soft tissue tension in the piriformis or related muscles.

• Stress and Strain

  • Deformations come in several types: changes in length (tension and compression), sideways shear (stress), and changes in volume.
  • (b) Compression: The same rod is compressed by forces with the same magnitude in the opposite direction.
  • For very small deformations and uniform materials, $\Delta L$ is approximately the same for the same magnitude of tension or compression.
  • For larger deformations, the cross-sectional area changes as the rod is compressed or stretched.

• Elasticity, Stress, and Strain

  • (b) Compression: The same rod is compressed by forces with the same magnitude in the opposite direction.
  • For very small deformations and uniform materials, ΔL is approximately the same for the same magnitude of tension or compression.
  • For larger deformations, the cross-sectional area changes as the rod is compressed or stretched.

• The Hydrogen Bomb

  • A thermonuclear weapon is a nuclear weapon designed to use the heat generated by a fission bomb to compress a nuclear fusion stage.
  • After this, the secondary explosive is compressed by X-rays coming from the nuclear fission of the primary explosive.
  • Finally, the secondary explosive is heated, after cold compression, by a second fission explosion that occurs inside the secondary explosive.
  • Radiation from a primary fission bomb compresses a secondary section containing both fission and fusion fuel.
  • The compressed secondary is heated from within by a second fission explosion.

• Fractures of the Vertebral Column

  • A compression fracture is a collapse of vertebra.
  • Seen in lateral views in plain x-ray films, compression fractures of the spine characteristically appear as wedge deformities, with greater loss of height anteriorly than posteriorly and intact pedicles in the anteroposterior view.

• Speed of Sound

  • There are two different kinds of sound waves: compression waves and shear waves.
  • Compression waves can travel through any media, but shear waves can only travel through solids.
  • The speed of a compression wave is determined by the media's compression capacity, shear modulus, and density, while the speed of the shear wave is only determined by the shear modulus and density.

• Application of Bernoulli's Equation: Pressure and Speed

  • The Bernoulli equation can be adapted to flows that are both unsteady and compressible.
  • However, the assumption of inviscid flow remains in both the unsteady and compressible versions of the equation.
  • Compressibility effects depend on the speed of the flow relative to the speed of sound in the fluid.
  • Adapt Bernoulli's equation for flows that are either unsteady or compressible