The capability to externally influence the contents of dreams with various stimulus during sleep is an ongoing area of study among dream researchers. Experiments have been made to determine which sense has the most power to evoke memory and emotion, and smell has been found to be the most potent stimulus for evoking memory and the emotions associated with it.

In one study, the participants were allowed to drift into sleep, and as they entered the REM phase (the period most associated with dreaming) the strong odor of either rotten eggs or sweet roses was wafted under their noses. A minute later the subjects were woken and asked about the nature of their dreams and how they felt.

It was found that the sleepers hardly ever dreamed of smelling something. Nevertheless, the emotional tone of the dream did change depending on the stimulation. The unpleasant smell changed the emotional content of the dream to mostly negative, while the scent of roses coloured the dreams with a positive glow.

Other studies have found that using smells during sleep can also have a powerful effect on memory. A group of researchers used the scent of roses on volunteers as they studied, and later as they slept. It improved their performance on a memory test by almost 15 per cent.

Technological singularity refers to the hypothesis that technological progress will become extremely fast, and so make the future unpredictable and qualitatively different from today. Although technological progress has been accelerating, it has been limited by the basic intelligence of the human brain, which has not changed significantly for millennia. However, with the increasing power of computers and other technologies, it might be possible to build a machine that is fundamentally more intelligent than humans.

If such a machine were built, then the machine itself could build a more intelligent machine. If the machine is more intelligent than humans, then presumably it would be better at building a more intelligent machine. The more intelligent machine would then be better at building an even more intelligent machine. This process might continue exponentially, with ever more intelligent machines making bigger increments to the intelligence of the next machine.

Superhuman intelligences could have goals inconsistent with human survival. When we create the first superintelligent entity, we might make a mistake and give it goals that lead it to annihilate humankind, assuming its enormous intellectual advantage gives it the power to do so. For example, we could tell it to solve a mathematical problem, and it might turn all the matter in the solar system into a giant calculating device, in the process killing the person who asked the question.

Many prominent technologists and academics dispute the plausibility of the notion of a technological singularity. Belief in the idea is based on a naive understanding of what intelligence is. As an analogy, imagine we had a computer that could design new computers faster than itself. It might accelerate the rate of improvements for a while, but in the end there are limits to how big and fast computers can run. We would end up in the same place, we would just get there a bit faster.

Daylight saving time is the practice of advancing clocks so that afternoons have more daylight and mornings have less. Typically clocks are adjusted forward one hour near the start of spring and are adjusted backward in autumn.

During his time as an American envoy to France, Benjamin Franklin, author of the proverb, “Early to bed, and early to rise, makes a man healthy, wealthy and wise”, anonymously published a letter suggesting that Parisians economize on candles by rising earlier to use morning sunlight. This 1784 satire proposed taxing shutters and waking the public by ringing church bells and firing cannons at sunrise.

William Willett independently conceived daylight saving time in 1905 during a pre-breakfast ride, when he observed with dismay how many Londoners slept through a large part of a summer day. An avid golfer, he also disliked cutting short his round at dusk. His solution was to advance the clock during the summer months, a proposal he published two years later. He independently proposed daylight saving time in 1907 and advocated it tirelessly.

The practice is controversial. Adding daylight to afternoons benefits retailing, sports, and other activities that exploit sunlight after working hours, but causes problems for farming, evening entertainment and other occupations tied to the sun. Although an early goal of daylight saving time was to reduce evening usage of incandescent lighting, modern heating and cooling usage patterns differ greatly and research about how daylight saving time currently affects energy use is limited and often contradictory.

Daylight saving time’s occasional clock shifts present other challenges. They complicate timekeeping and can disrupt meetings, travel, billing, recordkeeping, medical devices, heavy equipment, and sleep patterns. Changing clocks and daylight saving time has a direct economic cost, entailing extra work to support remote meetings, computer applications and corrections to errors.

It has been argued that clock shifts correlate with decreased economic efficiency, and that in 2000 the daylight-saving effect implied an estimated one-day loss of $31 billion on U.S. stock exchanges, althought the results have been disputed. The 2007 North American daylight saving time cost an estimated $500 million to $1 billion.

Cryptomnesia, or inadvertent plagiarism, is a memory bias whereby a person falsely recalls generating a thought, an idea, a song, or a joke, when the thought was actually generated by someone else. In these cases, the person is not deliberately engaging in plagiarism, but is rather experiencing a memory as if it were a new inspiration.

Self-plagiarism is not as costly as plagiarizing the work of others. In a famous case, George Harrison was sued over royalties for his first solo song “My Sweet Lord”, a song that sounded too similar to the Chiffons’ “He’s So Fine”. Harrison lost the case when a judge said he “subconsciously plagiarized”, and was ordered to pay $587,000 to Bright Tunes Music, who owned the copyright. Plagiarism of this sort is a kind of sleeper effect whereby old ideas come to feel new.

As explained by Carl Jung in Man and His Symbols, “An author may be writing steadily to a preconceived plan, working out an argument or developing the line of a story, when he suddenly runs off at a tangent. Perhaps a fresh idea has occurred to him, or a different image, or a whole new sub-plot. If you ask him what prompted the digression, he will not be able to tell you. He may not even have noticed the change, though he has now produced material that is entirely fresh and apparently unknown to him before. Yet it can sometimes be shown convincingly that what he has written bears a striking similarity to the work of another author, a work that he believes he has never seen.”

Helen Keller seriously compromised her and her teacher’s credibility with an incident of cryptomnesia which was misapprehended as plagiarism. The Frost King, which Keller wrote out of buried memories of a fairytale read to her four years previously, left Keller a nervous wreck, and unable to write fiction for the rest of her life.

Cryptomnesia may be the result of some memories becoming forcibly unconscious, due to lack of reinforcement through use. There may be enough of the memory left to recall it but not its origin. Therefore it does not always take the shape of plagiarism, as it would in writing, as well as musical compositions, but can also be the basis of philosophy.

The Meyer lemon is a citrus fruit native to China, thought to be a cross between a true lemon and a mandarin orange or sweet orange. The Meyer lemon was introduced to the United States in 1908 by the agricultural explorer Frank Nicholas Meyer, an employee of the United States Department of Agriculture who collected a sample of the plant on a trip to China. It is commonly grown in China potted as an ornamental plant.

The fruit is yellow and rounder than a true lemon with a slight orange tint when ripe. It has a sweeter, less acidic flavor than the more common grocery store varieties of lemon and has a fragrant edible skin. All lemons are widely known as powerful digestive aids. The combination of high acidity and fiber are effective in cleansing digestion organs.

The white coating or inner rind of a lemon contains the highest vitamin content per volume of most any food. Some studies show that the white coating of a single lemon can contain ten times the amount of Vitamin C as an entire bottle of Vitamin C supplements.

A lemon battery is a device used in experiments proposed in many science textbooks around the world. It is made by inserting two different metallic objects, for example a galvanized nail and a copper coin, into a lemon. The copper coin serves as the positive electrode or cathode and the galvanized nail as the electron-producing negative electrode or anode. These two objects work as electrodes, causing an electrochemical reaction which generates a small potential difference.

In practice, a single lemon battery is incapable of lighting a light bulb. One would need about 500 lemons wired in parallel to light a standard flashlight bulb.

Strong optimism, is the overarching mental state wherein people believe that things are more likely to go well for them than go badly. Compare this with the valence effect of prediction, a tendency for people to overestimate the likelihood of good things happening rather than bad things. It is the demonstrated systematic tendency for people to be over-optimistic about the outcome of planned actions.

Personal optimism correlates strongly with self-esteem, with psychological well-being and with physical and mental health. Optimism has been shown to be correlated with better immune systems in healthy people who have been subjected to stress. Martin Seligman, in researching this area, criticizes academics for focusing too much on causes for pessimism and not enough on optimism. He states that in the last three decades of the 20th century journals published 46,000 psychological papers on depression and only 400 on joy.

Popular culture has reflected the link between optimism and well-being with works like the fable “The Moth and the Star”, and Barack Obama’s speech and book, The Audacity of Hope.

A number of scholars have suggested that although optimism and pessimism might seem like opposites, in psychological terms they do not function in this way. Having more of one does not mean you have less of the other. The factors that reduce one do not necessarily increase the other. On many occasions in life we need both in equal supply. 

Hope can become a force for social change when it combines optimism and pessimism in healthy proportions. John Braithwaite, an academic at the Australian National University, suggests that in modern society we undervalue hope because we wrongly think of it as a choice between hopefulness and naiveness as opposed to scepticism and realism.

Diablo wind is a relatively recent term for a hot, dry offshore wind from the northeast that typically occurs in the San Francisco Bay Area of Northern California during the Autumn. The same wind pattern also affects other parts of California’s coastal ranges. 

The winds are created by the combination of strong high pressure at the surface over the Great Basin, strongly sinking air aloft, and lower pressure off the California coast. The air descending from aloft as well as from the Coast Ranges compresses at sea level where it warms as much as 20 °F, and loses humidity.

Unlike the Santa Ana wind which drains surface air off the high deserts, the so-called Diablo wind mainly originates from areas of strongly sinking air aloft, associated with the development of high atmospheric pressure inland following the passage of storms just north and east of California. The similar, though distinctive mechanisms can be distinguished by where the strongest winds in each type of event occur.

Typically, Santa Anas are strongest in canyons whereas a Diablo wind is first noted and blows strongest atop the various mountain peaks and ridges around the Bay Area. In both cases, as the air sinks, it heats up by compression and its humidity drops. This heat is in addition to, and usually greater than, any heat picked up by the wind as it crosses the Central Valley and the Diablo Valley. This is the reverse of the normal summertime weather pattern in which a trough of low rather than high pressure lies east of the Bay Area, drawing in cooler, more humid air from the ocean.

If the pressure gradient is large enough, the dry offshore wind can become quite strong with gusts reaching speeds of 40 mph or higher, particularly along and in the lee of the ridges of the Coast Range where the higher wind speed aloft acts like a pump, drawing warm, dry surface air from the windward eastern side up and over the ridgelines. This effect is especially dangerous with respect to wildfires as it can enhance the updraft generated by the heat in such fires.

Tides are the rising of Earth’s ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans.Tides cause changes in the depth of the marine and estuarine water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation. The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zone, is an important ecological product of ocean tides.

The changing tide produced at a given location is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of Earth rotation and the bathymetry of oceans, seas and estuaries. Besides the ocean, tidal phenomena can occur in other systems whenever a gravitational field that varies in time and space is present.

In addition to oceanic tides, there are atmospheric tides as well as earth tides. All of these are continuum mechanical phenomena, the first two being fluids and the third being essentially the thin solid Earth’s crust on top of the semi-liquid Earth’s interior.

Atmospheric tides are negligible from ground level and aviation altitudes, drowned by the much more important effects of weather. Atmospheric tides are both gravitational and thermal in origin and are the dominant dynamics from about 80 km to 120 km where the molecular density becomes too small to behave as a fluid.

Earth tides or terrestrial tides affect the entire mass of the Earth, which can be viewed as a liquid gyro with a very thin crust. The Earth’s crust shifts in response to the Moon’s and Sun’s gravitation, ocean tides, and atmospheric loading. While negligible for most human activities, the semidiurnal amplitude of terrestrial tides can reach about 55 cm at the equator which is important in GPS calibration.

When oscillating tidal currents in the stratified ocean flow over uneven bottom topography, they generate internal waves with tidal frequencies. Such waves are called internal tides. The galactic tide is the tidal force exerted by galaxies on stars within them and satellite galaxies orbiting them. The effects of the galactic tide on the Solar System’s Oort cloud are believed to be the cause of 90 percent of all observed long-period comets.