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🔗 Spaceflight

A diffractive solar sail, or diffractive lightsail, is a type of solar sail which relies on diffraction instead of reflection for its propulsion. Current diffractive sail designs use thin metamaterial films, containing micrometer-size gratings based on polarization or subwavelength refractive structures, causing light to spread out (i.e. diffract) and thereby exert radiation pressure when it passes through them.

🔗 Medicine 🔗 Chemicals 🔗 Medicine/Neurology 🔗 Pharmacology 🔗 Medicine/Psychiatry 🔗 Epilepsy

Benzodiazepines (BZD, BDZ, BZs), colloquially called "benzos", are a class of depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed to treat conditions such as anxiety disorders, insomnia, and seizures. The first benzodiazepine, chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955 and was made available in 1960 by Hoffmann–La Roche, who soon followed with diazepam (Valium) in 1963. By 1977, benzodiazepines were the most prescribed medications globally; the introduction of selective serotonin reuptake inhibitors (SSRIs), among other factors, decreased rates of prescription, but they remain frequently used worldwide.

Benzodiazepines are depressants that enhance the effect of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABA_A receptor, resulting in sedative, hypnotic (sleep-inducing), anxiolytic (anti-anxiety), anticonvulsant, and muscle relaxant properties. High doses of many shorter-acting benzodiazepines may also cause anterograde amnesia and dissociation. These properties make benzodiazepines useful in treating anxiety, panic disorder, insomnia, agitation, seizures, muscle spasms, alcohol withdrawal and as a premedication for medical or dental procedures. Benzodiazepines are categorized as short, intermediate, or long-acting. Short- and intermediate-acting benzodiazepines are preferred for the treatment of insomnia; longer-acting benzodiazepines are recommended for the treatment of anxiety.

Benzodiazepines are generally viewed as safe and effective for short-term use—about two to four weeks—although cognitive impairment and paradoxical effects such as aggression or behavioral disinhibition can occur. A minority of people have paradoxical reactions after taking benzodiazepines such as worsened agitation or panic. Benzodiazepines are associated with an increased risk of suicide due to aggression, impulsivity, and negative withdrawal effects. Long-term use is controversial because of concerns about decreasing effectiveness, physical dependence, benzodiazepine withdrawal syndrome, and an increased risk of dementia and cancer. The elderly are at an increased risk of both short- and long-term adverse effects, and as a result, all benzodiazepines are listed in the Beers List of inappropriate medications for older adults. There is controversy concerning the safety of benzodiazepines in pregnancy. While they are not major teratogens, uncertainty remains as to whether they cause cleft palate in a small number of babies and whether neurobehavioural effects occur as a result of prenatal exposure; they are known to cause withdrawal symptoms in the newborn.

Taken in overdose, benzodiazepines can cause dangerous deep unconsciousness, but they are less toxic than their predecessors, the barbiturates, and death rarely results when a benzodiazepine is the only drug taken. Combined with other central nervous system (CNS) depressants such as alcohol and opioids, the potential for toxicity and fatal overdose increases significantly. Benzodiazepines are commonly used recreationally and also often taken in combination with other addictive substances, and are controlled in most countries.

🔗 Computer Security 🔗 Computer Security/Computing 🔗 Crime and Criminal Biography

The Morris worm or Internet worm of November 2, 1988, is one of the oldest computer worms distributed via the Internet, and the first to gain significant mainstream media attention. It resulted in the first felony conviction in the US under the 1986 Computer Fraud and Abuse Act. It was written by a graduate student at Cornell University, Robert Tappan Morris, and launched on 8:30 pm November 2, 1988, from the Massachusetts Institute of Technology network.

Clifford Stoll of Harvard wrote that "Rumors have it that [Morris] worked with a friend or two at Harvard's computing department (Harvard student Paul Graham sent him mail asking for 'Any news on the brilliant project')."

🔗 Philosophy 🔗 Philosophy/Philosophy of religion 🔗 Philosophy/Philosophy of mind 🔗 Philosophy/Metaphysics

Neutral monism is an umbrella term for a class of metaphysical theories in the philosophy of mind, concerning the relation of mind to matter. These theories take the fundamental nature of reality to be neither mental nor physical; in other words it is "neutral".

Neutral monism has gained prominence as a potential solution to theoretical issues within the philosophy of mind, specifically the mind–body problem and the hard problem of consciousness. The mind–body problem is the problem of explaining how mind relates to matter. The hard problem is a related philosophical problem targeted at physicalist theories of mind specifically: the problem arises because it is not obvious how a purely physical universe could give rise to conscious experience. This is because physical explanations are mechanistic: that is, they explain phenomena by appealing to underlying functions and structures. And, though explanations of this sort seem to work well for a wide variety of phenomena, conscious experience seems uniquely resistant to functional explanations. As the philosopher David Chalmers has put it: "even when we have explained the performance of all the cognitive and behavioral functions in the vicinity of experience - perceptual discrimination, categorization, internal access, verbal report - there may still remain a further unanswered question: Why is the performance of these functions accompanied by experience?" The hard problem has motivated Chalmers and other philosophers to abandon the project of explaining consciousness in terms physical or chemical mechanisms (only 56.5% of philosophers are physicalists, according to the most recent PhilPapers survey).

With this, there has been growing demand for alternative ontologies (such as neutral monism) that may provide explanatory frameworks more suitable for explaining the existence of consciousness. It has been accepted by several prominent English-speaking philosophers, such as William James and Bertrand Russell.

🔗 Video games 🔗 Visual arts

The Atari Video Music (Model C240) is the earliest commercial electronic music visualizer released. It was manufactured by Atari, Inc., and released in 1977 for $169.95. The system creates an animated visual display that responds to musical input from a Hi-Fi stereo system for the visual entertainment of consumers.

🔗 Business 🔗 Psychology 🔗 Marketing & Advertising 🔗 Sociology 🔗 Media 🔗 Retailing 🔗 Home Living

Overchoice or choice overload is the paradoxical phenomenon that choosing between a large variety of options can be detrimental to decision making processes. The term was first introduced by Alvin Toffler in his 1970 book, Future Shock.

🔗 Horticulture and Gardening 🔗 Animals 🔗 Sanitation

The nematodes ( NEM-ə-tohdz or NEEM-; Greek: Νηματώδη; Latin: Nematoda) roundworms or eelworms, constitute the phylum Nematoda. They are a diverse animal phylum inhabiting a broad range of environments. Most species are free-living, feeding on microorganisms, but there are many that are parasitic. The parasitic worms (helminths) are the cause of soil-transmitted helminthiases.

They are taxonomically classified along with arthropods, tardigrades and other moulting animals in the clade Ecdysozoa. Unlike the vaguely similar flatworms, nematodes have a tubular digestive system, with openings at both ends. Like tardigrades, they have a reduced number of Hox genes, but their sister phylum Nematomorpha has kept the ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum.

Nematode species can be difficult to distinguish from one another. Consequently, estimates of the number of nematode species are uncertain. A 2013 survey of animal biodiversity published in the mega journal Zootaxa puts this figure at over 25,000. Estimates of the total number of extant species are subject to even greater variation. A widely referenced article published in 1993 estimated there may be over 1 million species of nematode. A subsequent publication challenged this claim, estimating the figure to be at least 40,000 species. Although the highest estimates (up to 100 million species) have since been deprecated, estimates supported by rarefaction curves, together with the use of DNA barcoding and the increasing acknowledgment of widespread cryptic species among nematodes, have placed the figure closer to 1 million species.

Nematodes have successfully adapted to nearly every ecosystem: from marine (salt) to fresh water, soils, from the polar regions to the tropics, as well as the highest to the lowest of elevations. They are ubiquitous in freshwater, marine, and terrestrial environments, where they often outnumber other animals in both individual and species counts, and are found in locations as diverse as mountains, deserts, and oceanic trenches. They are found in every part of the earth's lithosphere, even at great depths, 0.9–3.6 km (3,000–12,000 ft) below the surface of the Earth in gold mines in South Africa. They represent 90% of all animals on the ocean floor. In total, 4.4 × 10²⁰ nematodes inhabit the Earth's topsoil, or approximately 60 billion for each human, with the highest densities observed in tundra and boreal forests. Their numerical dominance, often exceeding a million individuals per square meter and accounting for about 80% of all individual animals on earth, their diversity of lifecycles, and their presence at various trophic levels point to an important role in many ecosystems. They have been shown to play crucial roles in polar ecosystems. The roughly 2,271 genera are placed in 256 families. The many parasitic forms include pathogens in most plants and animals. A third of the genera occur as parasites of vertebrates; about 35 nematode species occur in humans.

Nathan Cobb, a nematologist, described the ubiquity of nematodes on Earth thus:

In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. The location of towns would be decipherable since, for every massing of human beings, there would be a corresponding massing of certain nematodes. Trees would still stand in ghostly rows representing our streets and highways. The location of the various plants and animals would still be decipherable, and, had we sufficient knowledge, in many cases even their species could be determined by an examination of their erstwhile nematode parasites.^(p 472)

🔗 Software 🔗 Software/Computing 🔗 Norway

Razor 1911 (RZR) is a warez and demogroup founded in Norway, 1986. It was the first ever such group to be initially founded exclusively as a demogroup, before moving into warez in 1987. According to the US Justice Department, Razor 1911 is the oldest software cracking group that is still active on the internet. Razor 1911 ran the diskmag 'Propaganda' until 1995.

🔗 Mathematics 🔗 Books 🔗 India 🔗 Pakistan 🔗 India/Indian history workgroup

The Bakhshali manuscript is an ancient Indian mathematical text written on birch bark that was found in 1881 in the village of Bakhshali, Mardan (near Peshawar in present-day Pakistan, historical Gandhara). It is perhaps "the oldest extant manuscript in Indian mathematics". For some portions a carbon-date was proposed of AD 224–383 while for other portions a carbon-date as late as AD 885–993 in a recent study, but the dating has been criticised by specialists on methodological grounds (Plofker et al. 2017 and Houben 2018 §3). The manuscript contains the earliest known Indian use of a zero symbol. It is written in a form of literary Sanskrit influenced by contemporary dialects.

🔗 Computing 🔗 Computing/Software

In computer programming, a poltergeist (or gypsy wagon) is a short-lived, typically stateless object used to perform initialization or to invoke methods in another, more permanent class. It is considered an anti-pattern. The original definition is by Michael Akroyd 1996 - Object World West Conference:

"As a gypsy wagon or a poltergeist appears and disappears mysteriously, so does this short lived object. As a consequence the code is more difficult to maintain and there is unnecessary resource waste. The typical cause for this anti-pattern is poor object design."

A poltergeist can often be identified by its name; they are often called "manager_", "controller_", "supervisor", "start_process", etc.

Sometimes, poltergeist classes are created because the programmer anticipated the need for a more complex architecture. For example, a poltergeist arises if the same method acts as both the client and invoker in a command pattern, and the programmer anticipates separating the two phases. However, this more complex architecture may actually never materialize.

Poltergeists should not be confused with long-lived, state-bearing objects of a pattern such as model–view–controller, or tier-separating patterns such as business-delegate.

To remove a poltergeist, delete the class and insert its functionality in the invoked class, possibly by inheritance or as a mixin.