Underwater weighing

Body density (D0) is the ratio of body weight (BWg j.) to body volume. Body volume can be measured by water displacement or helium dilution, but the method of choice is underwater weighing (BWu2q) with corrections for the density of water (DHh2q) nd residual lung volume (RV) (40). Density is then estimated as follows ... 

Buskirk, E. R. (1961) Underwater weighing and body density a review of procedures. In Techniques for Measuring Body Composition (Brozek, J. Henschel, A., eds.), pp. 90-106, National Academy of Sciences and National Research Council, Washington, DC. 

Densitomelry. Densitometry involves underwater weighing. By weighing the subject in air, and when totally submerged in water, one can calculate the density of the subject s entire body. Work over the course of the decades has produced a formula that relates this density to the total amount of body fat. 

Skinfoid measurements reflect the thickness of layers of fat at specific points of the body. In contrast, the technique of densitometry is sensitive to the proportion of fat in the entire body. Density, whether measured by chemists, physicists, or dieticians always means mass/volume grams/ml). The density of a human being is often measured by using underwater weighing- This technique requires a tub of water, a scale for measuring the subject s weight, and a special chair that is attached to the scale. The subject needs to have defecated and urinated shortly... 

The term "RV" in the density formula means "residual volume." RV Is the amount of air remaining in the lungs after maximal exhalation. The KV can be measured at the same time as the underwater weighing. A technique for measuring the air... 

Rice, T, Borecki, I. B., Bouchard, C., and Rao, D. C. (1993). Segregation analysis of fat mass and other body composition measures derived from underwater weighing. Am. ]. Hum. Genet. 52, 967-973. 

The ASTM procedure covers the determination of the water absorption of cellular plastics (lighter than water) by measuring the change in buoyant force resulting from immersion. It can be applicable to WPC, having density less than 1.0, in its methodological part of underwater weighing of specimens. 

Calibration can be done with alternative but cumbersome methods using, for example, deuterium, underwater weighing, or dual-energy x-ray absorption. Standardization of the type of electrodes used and their placement is a major concern (Cornish et al. 1999 Kyle et al. 2004). 

Calibration is also a major concern in BIA. Calibration can be done with more accurate but cumbersome methods such as using deuterium, underwater weighing or dual energy X-ray absorption. However, dilution methods have their own errors (>2 L for TBW) and yield different results (e.g., 4% difference between the deuterium-TBW method and the... 

Cellular plastics are used extensively in flotation applications because of their ability to maintain a low buoyancy factor. The buoyancy factor is directly affected by the amount of water a particular foam plastic will absorb. The test method developed to determine water absorption of rigid cellular plastics is fully described in the ASTM Standards Manual. Basically, the test consists of determining the volume of initial dry weight of the object and calculating the initial buoyancy force. The object is then immersed in water and, at the end of the immersion period, the final buoyancy force is measured with an underwater weighing assembly. The difference between the initial and final buoyancy force is the weight of water absorbed. This difference is expressed in terms of water absorbed per unit of specimen volume. The test results are seriously affected if proper steps are not followed closely and variables are not controlled carefully. 

Long term recording of body weight and possibly body composition would result in data for the substrate flow to or from body stores. The dietary food intake can be assessed by questionnaires or prediction formulas, provided by earlier measurements. So energy expenditure and substrate oxidation rates can be calculated from energy and substrates balances. All these approaches would not need calorimetry at all it could however be used to verify some of the results of these methods. Body composition can be assessed by various established methods like dual energy X-ray analysis (DEXA), skin fold measurements, underwater weighing and body impedance measurements. 

The batoids swim solely by the movement of their greatly expanded pectoral fins, which are flapped vertically in a way similar to the flight of birds. This kind of movement is called oscillatory locomotion and is considered extremely energy efficient. The manta ray is also considered the most evolutionarily advanced batoid fish. Also, manta rays may be over 6 meters wide and weigh over 1580 kg. These parameters make them comparable in size with autonomous underwater vehicles (AUVs) and thus eliminate the problems associated with scalability. For these three reasons, manta rays have caught the attention of researchers, just as humpback whales became the focus of research because of their extreme maneuverability. 

Finally, to expose the lower plenum, the core support floor had to be raised and removed. During construction of the plant the core support floor (CSF) as installed weighed 270-ton. The CSF is a five-foot-thick, 31-foot-diameter, concrete structure encased in a carbon steel liner. Since the CSF was radioactive, steel shielding plates were positioned on top of the floor prior to its removal with a hydraulic jacking system (Fig. 7). Shield water in the PCRV protected underwater divers who entered into the steam generator ducts that went through the core support floor. Once inside these ducts the divers had to cut their way out to access the underside of the CSF. Once under the CSF the divers were used to sever all connections so it could be raised and removed. The CSF, due to the added weight of the shield plates, the attachments on the underside that had been cut and any entrained water... 

A chunk of coal is weighed twice while suspended from a spring scale (see Figure 1-10). When the coal is suspended in air, the scale registers 156 g when the coal is suspended underwater at 20 °C, the scale registers 59 g. What is the density of the coal The density of water at 20 °C is 0.9982 g cm. ... 

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