DreamA dream is a succession of s, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep. Humans spend about two hours dreaming per night, and each dream lasts around 5 to 20 minutes, although the dreamer may perceive the dream as being much longer than this. The content and function of dreams have been topics of scientific, philosophical and religious interest throughout recorded history.
Pareto efficiencyPareto efficiency or Pareto optimality is a situation where no action or allocation is available that makes one individual better off without making another worse off. The concept is named after Vilfredo Pareto (1848–1923), Italian civil engineer and economist, who used the concept in his studies of economic efficiency and income distribution. The following three concepts are closely related: Given an initial situation, a Pareto improvement is a new situation where some agents will gain, and no agents will lose.
Compressed-air vehicleA compressed-air vehicle (CAV) is a transport mechanism fueled by tanks of pressurized atmospheric gas and propelled by the release and expansion of the gas within a pneumatic motor. CAV's have found application in torpedoes, locomotives used in situations where standard locomotives are a hazard, and early prototype submarines.
Weighing scaleA scale or balance is a device used to measure weight or mass. These are also known as mass scales, weight scales, mass balances, and weight balances. The traditional scale consists of two plates or bowls suspended at equal distances from a fulcrum. One plate holds an object of unknown mass (or weight), while objects of known mass or weight, called weights, are added to the other plate until static equilibrium is achieved and the plates level off, which happens when the masses on the two plates are equal.
Lucid dreamA lucid dream is a type of dream in which the dreamer becomes aware that they are dreaming while dreaming. During a lucid dream, the dreamer may gain some amount of control over the dream characters, narrative, or environment. Lucid dreaming has been studied and reported for many years. Prominent figures from ancient to modern times have been fascinated by lucid dreams and have sought ways to better understand their causes and purpose. Many different theories have emerged as a result of scientific research on the subject and have even been shown in pop culture.
Reading disabilityA reading disability is a condition in which a person displays difficulty reading. Examples of reading disabilities include: developmental dyslexia, alexia (acquired dyslexia), and hyperlexia (word-reading ability well above normal for age and IQ). The National Institute of Neurological Disorders and Stroke defines reading disability or dyslexia as follows: "Dyslexia is a brain-based type of learning disability that specifically impairs a person's ability to read.
Learning disabilityLearning disability, learning disorder, or learning difficulty (British English) is a condition in the brain that causes difficulties comprehending or processing information and can be caused by several different factors. Given the "difficulty learning in a typical manner", this does not exclude the ability to learn in a different manner. Therefore, some people can be more accurately described as having a "learning difference", thus avoiding any misconception of being disabled with a possible lack of an ability to learn and possible negative stereotyping.
Dream interpretationDream interpretation is the process of assigning meaning to dreams. In many ancient societies, such as those of Egypt and Greece, dreaming was considered a supernatural communication or a means of divine intervention, whose message could be interpreted by people with these associated spiritual powers. In modern times, various schools of psychology and neurobiology have offered theories about the meaning and purpose of dreams.
Mass versus weightIn common usage, the mass of an object is often referred to as its weight, though these are in fact different concepts and quantities. Nevertheless, one object will always weigh more than another with less mass if both are subject to the same gravity (i.e. the same gravitational field strength). In scientific contexts, mass is the amount of "matter" in an object (though "matter" may be difficult to define), but weight is the force exerted on an object's matter by gravity.
Unmanned aerial vehicleAn unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without any human pilot, crew, or passengers on board. UAVs were originally developed through the twentieth century for military missions too "dull, dirty or dangerous" for humans, and by the twenty-first, they had become essential assets to most militaries. As control technologies improved and costs fell, their use expanded to many non-military applications.
