# density

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## density

[den´sĭ-te]
1. the ratio of the mass of a substance to its volume.
2. the quality of being compact.
3. the quantity of matter in a given space.
4. the quantity of electricity in a given area, volume, or time.
5. the degree of film blackening in an area of a photograph or radiograph.

## den·si·ty (ρ),

(den'si-tē),
1. The compactness of a substance; the ratio of mass to unit volume, usually expressed as g/cm3 (kg/m3 in the SI).
2. The quantity of electricity on a given surface or in a given time per unit of volume.
3. radiologic physics the opacity to light of an exposed radiographic or photographic film; the darker the film, the greater will be the measured density.
4. clinical radiology a less exposed area on a film, corresponding to a region of greater x-ray attenuation (radiopacity) in the subject; the more light transmitted by the film, the greater the density of the subject will be; this is not actually the opposite of sense 3, because one concerns film density and the other subject density.
[L. densitas, fr. densus, thick]

## density

The amount of a substance per unit volume Imaging
1. The compactness in a scan which reflects the type of tissues seen in CT and MR scans.
2. The amount of 'hard' or mineralized tissue in a plain film. See Bone mineral, Current density, Muscle fiber density, Spin density, Vapor density.

## den·si·ty

, pl. densities (dens'i-tē, -tēz)
1. The compactness of a substance; the ratio of mass to unit volume, usually expressed as g:cm3 (kg:m3 in SI).
2. The quantity of electricity on a given surface or in a given time per unit of volume.
3. radiologic physics The opacity to light of an exposed radiographic or photographic film; the darker the film, the greater the measured density.
4. clinical radiology A less-exposed area on a film, corresponding to a region of greater x-ray attenuation (radiopacity) in the subject; the more light transmitted by the film, the greater the density of the subject; this is not actually the opposite of the sense 3 definition, because one concerns film density and the other subject density.
[L. densitas, fr. densus, thick]

## density

An indication of the compactness of a substance. It is expressed as the ratio of the mass of the substance to its unit volume. The common units are g/cm3 and kg/m3. This property is usually given by lens manufacturers, the greater the density of a material, the greater its weight, all other factors being equal.

## den·si·ty

, pl. densities (dens'i-tē, -tēz)
1. Compactness of a substance.
2. Quantity of electricity on a given surface or in a given time per unit of volume.
3. radiologic physics opacity to light of an exposed radiographic or photographic film; the darker the film, the greater the measured density.
4. clinical radiology a less exposed area on a film, corresponding to a region of greater x-ray attenuation (radiopacity) in the subject.
[L. densitas, fr. densus, thick]

Q. what are the sources for high density lipoprotein? I have heard that high density lipoprotein is good for heart. What differences does it make in heart’s health and what are the sources for high density lipoprotein?

A. Hi Liam, it is very important that we have high density lipoprotein (HDL) in our body. The fact is that the HDL is formed inside the body. They are known as good cholesterol as they are famous for their protection for heart against the heart diseases. It has been found that Vitamin B3 or Niacin consumption increases the count of HDL. It’s good to cut on the diet having more of saturated fats and oils, which increases the chances of heart attack.

References in periodicals archive ?
Caption: Figure 9: Relationships of the rock energy density percentage and the strain under the different confining pressure conditions.
The two batteries must meet different requirements, but on a basic comparison, the Tesla battery comes out ahead with an energy density of 140 Wh/kg versus Formula E's 80 Wh/kg.
The strain energy density function must be invariant under coordinate transformations.
It will be a few years before the commercial and energy density benefits of graphene are clear enough to warrant adoption into mainstream supercap manufacturing processes.
Use of a standard LiSOCl2 battery pack, with its high energy density, enables this wearable device to be lighter and more compact, resulting in greater user comfort.
If the fish was large enough, up to three pellets were made to ensure accurate energy density values.
Pipistrel's Tomazic said doubling energy density would open up some possibilities, such as two more takeoffs in the C2 motorglider before recharge or more "get home" energy from a longer flight.
Compared with those fed low energy density diets prepartum, cows fed high energy density diets consumed lower dry matter pre-partum (p<0.01) and post-partum (p<0.05).
Given minimum energy density and power density specifications that are beyond current energy storage capabilities, systems like lightweight vehicles and handheld leaf blowers for yard cleanup often turn to fuel-burning engines.
But the electrical properties of the supercapacitor having lithium perchlorate were very high as compared to Fig 4 shows the optimization of various structural supercapacitor specimens with different electrolytes by plotting energy density and flexural modulus on y-axis and supercapacitors with varying electrolyte on x-axis.
The extent to which humankind uses and manipulates the energy around us sets us apart from other forms of life and we have progressively sought materials of high "energy density" to develop our civilisation.
The energy density of oil is nearly double that of coal and three times that of wood.

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