shear stress

(redirected from Sheer stress)
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Related to Sheer stress: Shear strain, Normal stress

shear stress

the force acting in shear flow expressed per unit area; units in the CGS system: dynes/cm2.

shear stress

Biophysics
A frictional force tangential to the direction of a flowing fluid, the force of which is directly related to the fluid’s viscosity shear stress. In blood vessels, shear stress acts on endothelium and is the mechanical force responsible for the acute changes in luminal diameter. 

Geomedicine
Stress parallel to a given surface (e.g., a fault plane) that results from forces applied parallel to the surface or from remote forces transmitted through surrounding rock.

stress

(stres) [Fr. estresse, narrowness]
1. Any physical, physiological, or psychological force that disturbs equilibrium
2. The consequences of forces that disturb equilibrium.
3. Force applied per unit area. In the physical sciences, stresses include forces that deform or damage materials, such as impact, shear, torsion, compression, and tension. These physical stresses are particularly important in certain branches of health care, e.g., dentistry or orthopedic surgery, and in biotechnology industries, e.g., in the design and use of prostheses, grafts, and perfusion pumps.

Physiological stresses include agents that upset homeostasis, such as infection, injury, disease, internal organ pressures, or psychic strain.

In psychology, stresses include perceptions, emotions, anxieties, and interpersonal, social, or economic events that are considered threatening to one's physical health, personal safety, or well-being. Marital discord; conflicts with others; battle, torture, or abuse; bankruptcy; incarceration; health care crises; and self-doubt are all examples of conditions that increase psychic stresses. The response of an organism or material to stress is known as adaptation. See: adaptation; anxiety; fracture; homeostasis; Laplace, law of; relaxation response

critical incident stress

One's emotional reaction to a catastrophic event such as a mass casualty incident or the death of a patient or coworker. Often such events negatively affect the well-being of health care providers.

oxidative stress

The cellular damage caused by oxygen-derived free radical formation. The three most important are superoxide (O2-), hydrogen peroxide (H2O2), and hydroxyl ions; these are produced during normal metabolic processes as well as in reaction to cell injury. The extent of their damaging potential can be decreased by antioxidants.
See: antioxidant; free radical; superoxide; superoxide dismutase

prenatal stress

Anxiety, tension, depression, or other psychological discomfort experienced by a pregnant woman.

shear stress

Shear.

shear

1. to remove the fleece of a sheep.
2. pressure on a mass in such a way that planes within it are pressured to move in a direction parallel to the pressure. Any movement is proportional to the distance from the plane at which movement occurs.

shear injury
injury to tissues caused by shear pressure. See shearing injuries (2).
shear stress
the stress to which a tissue is subjected by a shear force without injury actually occurring.
References in periodicals archive ?
The paper, titled "Identification of Vascular Endothelial Genes Differentially Responsive to Fluid Mechanical Stimuli: Cyclooxygenase-2, Manganese Superoxide Dismutase, and Endothelial Cell Nitric Oxide Synthase are Selectively Up-Regulated by Steady Laminar Shear Stress," explains how three endothelial genes thought to play a role in atherosclerotic disease -- manganese superoxide dismutase, cyclooxygenase-2 and the endothelial isoform of nitric oxide synthase -- are differentially expressed in response to laminar sheer stress (LSS) or uniform blood flow.
Consisting of friction plates submerged in silicone fluid, when the drive (front) axle loses grip, the relative speed difference between the plates produces a sheer stress that transfers torque from one plate to the other and redistributes it to the rear axle.
Doctors have warned that fans who smoke or have high blood pressure could experience a heart attack from the sheer stress of watching a match - in January 2006 another American football fan suffered a heart attack during a tense moment in a game between the Pittsburgh Steelers and the Indianapolis Colts.
Theatre boss Paul Scarbrow said: "From what I can understand it is sheer stress and the pressure has got to her.
When the sheer stress of caring for her threatened their own health - this was in the days before care allowances and support services - my parents reluctantly agreed to allow Julie to go into a hospital.
The precious wilderness and its myriad species are being destroyed by pollution, over-exploitation, loss of habitat and the sheer stress of coming into contact with humans.