54 may refer to:
- 54 (number)
- one of the years 54 BC, AD 54, 1954, 2054
- 54 (novel), a 2002 novel by Wu Ming
- Studio 54, a New York City nightclub from 1977 until 1981
- 54 (film), a 1998 American drama film about the club
- 54 (album), a 2010 album by Metropole Orkest
- "Fifty Four", a song by Karma to Burn from the album Arch Stanton, 2014
- 54th Division (disambiguation)
- 54th Regiment of Foot (disambiguation)
- 54th Infantry (disambiguation)
- 54 Alexandra, a main-belt asteroid
- Tatra 54, an automobile
In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coordinate is needed to specify a point on it – for example, the point at 5 on a number line. A surface, such as the boundary of a cylinder or sphere, has a dimension of two (2D) because two coordinates are needed to specify a point on it – for example, both a latitude and longitude are required to locate a point on the surface of a sphere. A two-dimensional Euclidean space is a two-dimensional space on the plane. The inside of a cube, a cylinder or a sphere is three-dimensional (3D) because three coordinates are needed to locate a point within these spaces.
In classical mechanics, space and time are different categories and refer to absolute space and time. That conception of the world is a four-dimensional space but not the one that was found necessary to describe electromagnetism. The four dimensions (4D) of spacetime consist of events that are not absolutely defined spatially and temporally, but rather are known relative to the motion of an observer. Minkowski space first approximates the universe without gravity; the pseudo-Riemannian manifolds of general relativity describe spacetime with matter and gravity. 10 dimensions are used to describe superstring theory (6D hyperspace + 4D), 11 dimensions can describe supergravity and M-theory (7D hyperspace + 4D), and the state-space of quantum mechanics is an infinite-dimensional function space.
The concept of dimension is not restricted to physical objects. High-dimensional spaces frequently occur in mathematics and the sciences. They may be Euclidean spaces or more general parameter spaces or configuration spaces such as in Lagrangian or Hamiltonian mechanics; these are abstract spaces, independent of the physical space.
Foams are two-phase material systems where a gas is dispersed in a second, non-gaseous material, specifically, in which gas cells are enclosed by a distinct liquid or solid material.: 6 : 4 The foam "may contain more or less liquid [or solid] according to circumstances",: 6 although in the case of gas-liquid foams, the gas occupies most of the volume.: 4 The word derives from the medieval German and otherwise obsolete veim, in reference to the "frothy head forming in the glass once the beer has been freshly poured" (cf. ausgefeimt).: 1
Theories regarding foam formation, structure, and properties—in physics and physical chemistry—differ somewhat between liquid and solid foams in that the former are dynamic (e.g., in their being "continuously deformed"), as a result of gas diffusing between cells, liquid draining from the foam into a bulk liquid, etc.: 1–2 Theories regarding liquid foams have as direct analogs theories regarding emulsions,: 3 two-phase material systems in which one liquid is enclosed by another.
In most foams, the volume of gas is large, with thin films of liquid or solid separating the regions of gas. A bath sponge and the head on a glass of beer are examples of foams; soap foams are also known as suds.
Solid foams can be closed-cell or open-cell. In closed-cell foam, the gas forms discrete pockets, each completely surrounded by the solid material. In open-cell foam, gas pockets connect to each other. A bath sponge is an example of an open-cell foam: water easily flows through the entire structure, displacing the air. A sleeping mat is an example of a product composed of closed-cell foam.
Foams are examples of dispersed media. In general, gas is present, so it divides into gas bubbles of different sizes (i.e., the material is polydisperse)—separated by liquid regions that may form films, thinner and thinner when the liquid phase drains out of the system films. When the principal scale is small, i.e., for a very fine foam, this dispersed medium can be considered a type of colloid.
Foam can also refer to something that is analogous to foam, such as quantum foam.
Full may refer to:
- People with the surname Full, including:
- Mr. Full (given name unknown), acting Governor of German Cameroon, 1913 to 1914
- A property in the mathematical field of topology; see Full set
- A property of functors in the mathematical field of category theory; see Full and faithful functors
- Satiety, the absence of hunger
- A standard bed size, see Bed
- Fulling, also known as tucking or walking ("waulking" in Scotland), term for a step in woollen clothmaking (verb: to full)
- Full-Reuenthal, a municipality in the district of Zurzach in the canton of Aargau in Switzerland
A mattress is a large, usually rectangular pad for supporting a person lying down, especially for sleeping. It is designed to be used as a bed, or on a bed frame as part of a bed. Mattresses may consist of a quilted or similarly fastened case, usually of heavy cloth, containing materials such as hair, straw, cotton, foam rubber, or a framework of metal springs. Mattresses may also be filled with air or water.
Mattresses are usually placed on top of a bed base which may be solid, as in the case of a platform bed, or elastic, such as an upholstered wood and wire box spring or a slatted foundation. Popular in Europe, a divan incorporates both mattress and foundation in a single upholstered, footed unit. Divans have at least one innerspring layer as well as cushioning materials. They may be supplied with a secondary mattress or a removable "topper". Mattresses may also be filled with air or water, or a variety of natural fibers, such as in futons. Kapok is a common mattress material in Southeast Asia, and coir in South Asia.
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, it would be impossible for language, relationships, or personal identity to develop. Memory loss is usually described as forgetfulness or amnesia.
Memory is often understood as an informational processing system with explicit and implicit functioning that is made up of a sensory processor, short-term (or working) memory, and long-term memory. This can be related to the neuron.
The sensory processor allows information from the outside world to be sensed in the form of chemical and physical stimuli and attended to various levels of focus and intent. Working memory serves as an encoding and retrieval processor. Information in the form of stimuli is encoded in accordance with explicit or implicit functions by the working memory processor. The working memory also retrieves information from previously stored material. Finally, the function of long-term memory is to store through various categorical models or systems.
Declarative, or explicit memory, is the conscious storage and recollection of data. Under declarative memory resides semantic and episodic memory. Semantic memory refers to memory that is encoded with specific meaning. Meanwhile, episodic memory refers to information that is encoded along a spatial and temporal plane. Declarative memory is usually the primary process thought of when referencing memory. Non-declarative, or implicit, memory is the unconscious storage and recollection of information. An example of a non-declarative process would be the unconscious learning or retrieval of information by way of procedural memory, or a priming phenomenon. Priming is the process of subliminally arousing specific responses from memory and shows that not all memory is consciously activated, whereas procedural memory is the slow and gradual learning of skills that often occurs without conscious attention to learning.
Memory is not a perfect processor and is affected by many factors. The ways by which information is encoded, stored, and retrieved can all be corrupted. Pain, for example, has been identified as a physical condition that impairs memory, and has been noted in animal models as well as chronic pain patients. The amount of attention given new stimuli can diminish the amount of information that becomes encoded for storage. Also, the storage process can become corrupted by physical damage to areas of the brain that are associated with memory storage, such as the hippocampus. Finally, the retrieval of information from long-term memory can be disrupted because of decay within long-term memory. Normal functioning, decay over time, and brain damage all affect the accuracy and capacity of the memory.
Size in general is the magnitude or dimensions of a thing. More specifically, geometrical size (or spatial size) can refer to three geometrical measures: length, area, or volume. Length can be generalized to other linear dimensions (width, height, diameter, perimeter).
Size can also be measured in terms of mass, especially when assuming a density range.
In mathematical terms, "size is a concept abstracted from the process of measuring by comparing a longer to a shorter". Size is determined by the process of comparing or measuring objects, which results in the determination of the magnitude of a quantity, such as length or mass, relative to a unit of measurement. Such a magnitude is usually expressed as a numerical value of units on a previously established spatial scale, such as meters or inches.
The sizes with which humans tend to be most familiar are body dimensions (measures of anthropometry), which include measures such as human height and human body weight. These measures can, in the aggregate, allow the generation of commercially useful distributions of products that accommodate expected body sizes, as with the creation of clothing sizes and shoe sizes, and with the standardization of door frame dimensions, ceiling heights, and bed sizes. The human experience of size can lead to a psychological tendency towards size bias, wherein the relative importance or perceived complexity of organisms and other objects is judged based on their size relative to humans, and particularly whether this size makes them easy to observe without aid.
by Venkata
The mattress looks premium and very comfy. Definitely miss my bad during travel or vacations.
by Christopher
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by Kyle
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by Julia
This is the first mattress I have ever bought. The process was extremely easy to buy and set up. The mattress is pretty firm which I like.
by Brittney
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by Anabelle
I love it so much, makes me want to lay in bed all day. Noticed a big difference from my last mattress and I get a much better sleep at night. I hardly wake up with pains anymore. I went through many reviews for a few days of up to 15 different mattress brands and came down to this one and I’m very pleased with my purchase.
by Andrew
The Dreamcloud mattress is the perfect bed for me as a back and stomach sleeper. Just the right amount of firmness for back support.
by Brianna
This mattress feels like luxury at a non-luxury price. It’s supportive enough to keep my back aligned but feels soft enough that I sigh into bed every night. Extremely happy with my first ever nice mattress purchase.
by Yvonne
I’ve enjoyed sleeping on this mattress
Its soft, comfortable good support, I enjoy going to bed.
by Carolyn
Love it since day 1…everything you guys said it would be…
by Pablo
The mattress is right between firm and soft. It was easy to unbox and set up.
by Austin
I’ve been trying to find a good mattress for stomach sleeping, and this one is just the right comfort level between soft and firm, highly recommended if you sleep the same way!