Effusion

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effusion

1. the flow of a gas through a small aperture under pressure, esp when the density is such that the mean distance between molecules is large compared to the diameter of the aperture
2. Med
a. the escape of blood or other fluid into a body cavity or tissue
b. the fluid that has escaped

Effusion

 

the slow leakage of gas through a small aperture. Two cases of effusion are distinguished. In the first case, the diameter of the opening is small compared with the mean free path of the molecules (the pressure in the vessel is very low). In such a case, molecular effusion occurs in which collisions between molecules play no part, and the overall volume of gas escaping per unit time is Effusion, where S is the area of the aperture, μ is the molecular mass of the gas, R is the universal gas constant, T is the absolute temperature of the gas, and p1 and p2 are the gas pressures on the two sides of the aperture. The effusion method of measuring very low pressures (about 10–3–10–4 mm Hg) is based on this case.

In the second case, where the gas pressure is so high that the mean free path is smaller than the diameter of the aperture, the leakage of gas obeys the laws of hydrodynamics. The molecules escape from the aperture in the form of a jet, and the volume of gas discharged per unit time is inversely proportional to the square root of the density of the gas. This law underlies a method of determining the density of gases from the time of their discharge through small apertures (0.10–0.01 mm). However, if the pressure within the vessel is considerably greater than the external pressure, the amount of gas escaping is proportional to the pressure in the vessel.


Effusion

 

the process of lava (magma) pouring out onto the earth’s surface. When the lava cools, effusive rocks are formed, bedded in the form of lava flows and lava sheets. Effusion, one of the manifestations of volcanic activity, is usually accompanied by an explosion, with discharges of small fragments (volcanic ash, sand, or tuff) or large chunks (volcanic bombs and slags). Viscous acidic lava sometimes will not flow, but rather is extended, forming volcanic domes.

effusion

[e′fyü·zhən]
(medicine)
A pouring out of any fluid into a body cavity or tissue.
(physical chemistry)
The movement of a gas through an opening which is small as compared with the average distance which the gas molecules travel between collisions.
(science and technology)
The act or process of leaking or pouring out.
Any material that is effused.
References in periodicals archive ?
The clinical characteristics of the pericollapse stage are serious pain in the groin that occurs suddenly, painful limping, and aggravated pain with strong internal rotation, while the imaging manifestations include a band-like low signal with T1-weighted images, BME with STIR and joint effusion on MRI, fracture of the subchondral bone plate on CT, or crescent signs with no visible collapse on plain radiographs.
Bilateral Title Total Cases Percentage Unilateral 30 66.6 Bilateral 15 33.3 Table 6: Classified Changes in Total Pathologies Changes Cases Percentage Joint Space Reduction 20 44% Joint Space Widening 10 22% Altered Femoral Lead Shape Erosion 8 18% Joint Effusion 27 60% Altered femoral Head Shape 22 49% Subchondral Sclerosis 14 31% Subchondral cysts 9 20% Periarticular Osteopenia 3 7% Osteophytes 8 18% Table 7: Comparison Between Total Pathologies and AVN Total Pathologies AVN Percentage 45 13 29% Table 8: Distribution of AVN Various Age Group Age Group Total Cases Percentage 10-20 years 3 23 20-30 years 7 53 30-40 years 1 8 40-50 years 2 16 Table 9: AVN Detected-Male vs.
Hip joint effusion (seen in this study) is a consistent finding in many cases of TOH.
Risk of temporomandibular joint effusion related to magnetic resonance imaging signs of disc displacement.
Previous studies on the effect of long-distance running on the structures of the knee have used serial magnetic resonance (MR) images to follow the appearance and resolution of joint effusions, abnormal signal intensity in the menisci, and marrow changes with conflicting interpretations.
The highest probability is associated with glenohumeral joint effusion (0.686).
Patients usually present with progressive symptoms which include pain, repeated nontraumatic joint effusion, and decreased range of motion in the diffuse form.
An ultrasound of the right knee showed moderate joint effusion and synovial hyperemia.
aureus isolated from a normally sterile body site, including blood, pleural effusion, cerebrospinal fluid, joint effusion, and bone marrow, or a skin and soft tissue infection (SSTI) requiring hospital admission for surgical drainage/debridement under general anesthetic and/or intravenous antimicrobial therapy.[2] PCR amplification was used for multilocus sequence typing, agr typing, and spa typing.
Radiography of both hip joints with pelvis (Figure 1D) revealed displacement of fat stripes along the left hip joint, s/o possibly left hip joint effusion. Visualized bones were normal.
Performing synovectomy in TKA will give complete pathological diagnosis avoiding persistence of synovial pathology along with long-term benefits of synovectomy like no joint effusion, less pain, no synovial hypertrophy, and good range of movement of knee.
(1,7,9) MRI findings include a synovial mass, fat signal intensity on all sequences, suppression of signal with fat-selective presaturation, joint effusion, and absence of MRI supporting hemosiderin.

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