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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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Mathematics of Sudoku
The class of Sudoku puzzles consists of a partially completed row-column grid of cells partitioned into N regions each of size N cells, to be filled in ("solved") using a prescribed set of N distinct symbols (typically the numbers {1, ..., N}), so that each row, column and region contains exactly one of each element of the set. The properties of Sudoku puzzles and their solutions can be investigated using mathematics and algorithms.
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  • 12 Oct 2022
Topic Review
PSR J0737-3039
PSR J0737−3039 is the only known double pulsar. It consists of two neutron stars emitting electromagnetic waves in the radio wavelength in a relativistic binary system. The two pulsars are known as PSR J0737−3039A and PSR J0737−3039B. It was discovered in 2003 at Australia's Parkes Observatory by an international team led by the radio astronomer Marta Burgay during a high-latitude pulsar survey.
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  • 12 Oct 2022
Topic Review
Drvspace
DriveSpace (initially known as DoubleSpace) is a disk compression utility supplied with MS-DOS starting from version 6.0 in 1993 and ending in 2000 with the release of Windows Me. The purpose of DriveSpace is to increase the amount of data the user could store on disks by transparently compressing and decompressing data on-the-fly. It is primarily intended for use with hard drives, but use for floppy disks is also supported. This feature was removed in Windows XP and later.
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Topic Review
Yarovaya Law
The Yarovaya law (in Russian: Закон Яровой, transliteration: Zakon Jarovoy), also Yarovaya package/bag, is a set of two Russia n federal bills, 374-FZ and 375-FZ, passed in 2016. The bills amend previous counter-terrorism law and separate laws regulating additional counter-terror and public safety measures. It is known to the public under the last name of one of its creators—Irina Yarovaya. The amendments included an expansion of authority for law enforcement agencies, new requirements for data collection and mandatory decoding in the telecommunications industry, as well as the increased regulation of evangelism, including a ban on the performance of "missionary activities" in non-religious settings.
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  • 12 Oct 2022
Topic Review
Range (Aeronautics)
The maximal total range is the maximum distance an aircraft can fly between takeoff and landing. Powered aircraft range is limited by the aviation fuel energy storage capacity (chemical or electrical) considering both weight and volume limits. Unpowered aircraft range depends on factors such as cross-country speed and environmental conditions. The range can be seen as the cross-country ground speed multiplied by the maximum time in the air. The fuel time limit for powered aircraft is fixed by the available fuel (considering reserve fuel requirements) and rate of consumption. Some aircraft can gain energy while airborne through the environment (e.g. collecting solar energy or through rising air currents from mechanical or thermal lifting) or from in-flight refueling. These aircraft could theoretically have infinite range. Ferry range means the maximum range that a aircraft engaged in ferry flying can achieve. This usually means maximum fuel load, optionally with extra fuel tanks and minimum equipment. It refers to transport of aircraft without any passengers or cargo. Combat radius is a related measure based on the maximum distance a warplane can travel from its base of operations, accomplish some objective, and return to its original airfield with minimal reserves.
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  • 18 Oct 2022
Topic Review
Hubsan X4
The Hubsan X4 is a series of very small lightweight remotely-controlled quadcopters (sometimes considered unmanned aerial vehicles or "drones") which utilize four propellers (hence the "X4" designation) powered by a single lithium-polymer battery. Since the marketing of the first model, several upgrades and improvements have taken place, each with a subsequent model number and designation attached.
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  • 12 Oct 2022
Topic Review
Psychodrama
Psychodrama is an action method, often used as a psychotherapy, in which clients use spontaneous dramatization, role playing, and dramatic self-presentation to investigate and gain insight into their lives. Developed by Jacob L. Moreno, psychodrama includes elements of theater, often conducted on a stage, or a space that serves as a stage area, where props can be used. A psychodrama therapy group, under the direction of a licensed psychodramatist, reenacts real-life, past situations (or inner mental processes), acting them out in present time. Participants then have the opportunity to evaluate their behavior, reflect on how the past incident is getting played out in the present and more deeply understand particular situations in their lives. Psychodrama offers a creative way for an individual or group to explore and solve personal problems. It may be used in a variety of clinical and community-based settings in which other group members (audience) are invited to become therapeutic agents (stand-ins) to populate the scene of one client. Besides benefits to the designated client, "side-benefits" may accrue to other group members, as they make relevant connections and insights to their own lives from the psychodrama of another. A psychodrama is best conducted and produced by a person trained in the method, called a psychodrama director. In a session of psychodrama, one client of the group becomes the protagonist, and focuses on a particular, personal, emotionally problematic situation to enact on stage. A variety of scenes may be enacted, depicting, for example, memories of specific happenings in the client's past, unfinished situations, inner dramas, fantasies, dreams, preparations for future risk-taking situations, or unrehearsed expressions of mental states in the here and now. These scenes either approximate real-life situations or are externalizations of inner mental processes. Other members of the group may become auxiliaries and support the protagonist by playing other significant roles in the scene, or they may step in as a "double" who plays the role of the protagonist. A core tenet of psychodrama is Moreno's theory of "spontaneity-creativity". Moreno believed that the best way for an individual to respond creatively to a situation is through spontaneity, that is, through a readiness to improvise and respond in the moment. By encouraging an individual to address a problem in a creative way, reacting spontaneously and based on impulse, they may begin to discover new solutions to problems in their lives and learn new roles they can inhabit within it. Moreno's focus on spontaneous action within the psychodrama was developed in his Theatre of Spontaneity, which he directed in Vienna in the early 1920s. Disenchanted with the stagnancy he observed in conventional, scripted theatre, he found himself interested in the spontaneity required in improvisational work. He founded an improvisational troupe in the 1920s. This work in the theatre impacted the development of his psychodramatic theory.
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  • 13 Oct 2022
Topic Review
SpaceX Dragon
Dragon, also known as Dragon 1 or Cargo Dragon, was a class of partially reusable cargo spacecraft developed by SpaceX, an American private space transportation company. Dragon was launched into orbit by the company's Falcon 9 launch vehicle to resupply the International Space Station (ISS). During its maiden flight in December 2010, Dragon became the first commercially built and operated spacecraft to be recovered successfully from orbit. On 25 May 2012, a cargo variant of Dragon became the first commercial spacecraft to successfully rendezvous with and attach to the ISS. SpaceX is contracted to deliver cargo to the ISS under NASA's Commercial Resupply Services program, and Dragon began regular cargo flights in October 2012. With the Dragon spacecraft and the Orbital ATK Cygnus, NASA seeks to increase its partnerships with domestic commercial aviation and aeronautics industry. On 3 June 2017, the C106 capsule, largely assembled from previously flown components from the CRS-4 mission in September 2014, was launched again for the first time on CRS-11, with the hull, structural elements, thrusters, harnesses, propellant tanks, plumbing and many of the avionics reused, while the heat shield, batteries and components exposed to sea water upon splashdown for recovery were replaced. SpaceX developed a second version called Dragon 2, which is capable of transporting humans. Flight testing was completed in 2019, after a delay caused by a test pad anomaly in April 2019, which resulted in the loss of a Dragon 2 capsule. The first flight of astronauts on Dragon 2 occurred on the Crew Dragon Demo-2 mission in May 2020. The last flight of the first version of the Dragon spacecraft (Dragon 1) launched 7 March 2020 (UTC); it was a cargo resupply mission (CRS-20) to International Space Station (ISS). This mission was the last mission of SpaceX of the first Commercial Resupply Services (CRS-1) program, and marked the retirement of the Dragon 1 fleet. Further SpaceX commercial resupply flights to ISS under the second Commercial Resupply Services (CRS-2) program use the cargo-carrying variant of the SpaceX Dragon 2 spacecraft.
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  • 12 Oct 2022
Topic Review
Substance Use Disorder
Substance use disorder (SUD) is the persistent use of drugs (including alcohol) despite substantial harm and adverse consequences. Substance use disorders are characterized by an array of mental/emotional, physical, and behavioral problems such as chronic guilt; an inability to reduce or stop consuming the substance(s) despite repeated attempts; driving while intoxicated; and physiological withdrawal symptoms. Drug classes that are involved in SUD include: alcohol; cannabis; phencyclidine and other hallucinogens, such as arylcyclohexylamines; inhalants; opioids; sedatives, hypnotics, or anxiolytics; stimulants; tobacco; and other or unknown substances. In the Diagnostic and Statistical Manual of Mental Disorders 5th edition (2013), also known as DSM-5, the DSM-IV diagnoses of substance abuse and substance dependence were merged into the category of substance use disorders. The severity of substance use disorders can vary widely; in the DSM-5 diagnosis of a SUD, the severity of an individual's SUD is qualified as mild, moderate, or severe on the basis of how many of the 11 diagnostic criteria are met. The International Classification of Diseases 11th revision (ICD-11) divides substance use disorders into two categories: (1) harmful pattern of substance use; and (2) substance dependence. In 2017, globally 271 million people (5.5% of adults) were estimated to have used one or more illicit drugs. Of these, 35 million had a substance use disorder. An additional 237 million men and 46 million women have alcohol use disorder as of 2016. In 2017, substance use disorders from illicit substances directly resulted in 585,000 deaths. Direct deaths from drug use, other than alcohol, have increased over 60 percent from 2000 to 2015. Alcohol use resulted in an additional 3 million deaths in 2016.
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Topic Review
Mindfulness
Mindfulness is the psychological process of purposely bringing one's attention to experiences occurring in the present moment without judgment which one develops through the practice of meditation and through other training. Mindfulness derives from sati, a significant element of Buddhist traditions, and based on Zen, Vipassanā, and Tibetan meditation techniques. Though definitions and techniques of mindfulness are wide-ranging, Buddhist traditions explain what constitutes mindfulness such as how past, present and future moments arise and cease as momentary sense impressions and mental phenomena. Individuals who have contributed to the popularity of mindfulness in the modern Western context include Thích Nhất Hạnh (1926– ), Herbert Benson (1935– ), Jon Kabat-Zinn (1944– ), and Richard J. Davidson (1951– ). Clinical psychology and psychiatry since the 1970s have developed a number of therapeutic applications based on mindfulness for helping people experiencing a variety of psychological conditions. Mindfulness practice has been employed to reduce depression, to reduce stress, anxiety, and in the treatment of drug addiction. Programs based on mindfulness models have been adopted within schools, prisons, hospitals, veterans' centers, and other environments, and mindfulness programs have been applied for additional outcomes such as for healthy aging, weight management, athletic performance, helping children with special needs, and as an intervention during the perinatal period. Clinical studies have documented both physical- and mental-health benefits of mindfulness in different patient categories as well as in healthy adults and children. Research studies have shown a positive relationship between trait mindfulness (see below) and psychological health. The practice of mindfulness appears to provide therapeutic benefits to people with psychiatric disorders, including moderate benefits to those with psychosis. Studies also indicate that rumination and worry contribute to a variety of mental disorders, and that mindfulness-based interventions can reduce both rumination and worry. Further, the practice of mindfulness may be a preventive strategy to halt the development of mental-health problems. There is also evidence that suggest engaging in mindfulness meditation may influence physical health. For example, the psychological habit of repeatedly dwelling on stressful thoughts (i.e., rumination) appears to intensify the physiological effects of the stressor (as a result of the continual activation of the sympathetic nervous system and the hypothalamus-pituitary-adrenal axis) with the potential to lead to physical health related clinical manifestations. Studies indicate that mindfulness meditation, which brings about reductions in rumination, may alter these biological clinical pathways. Further, research indicates that mindfulness may favourably influence the immune system as well as inflammation,Cite error: Closing missing for tag
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