Psi

Psi or the initials PSI or Ψ may refer to:

Alphabetic letters

• Psi (Greek) (Ψ, ψ), the 23rd letter of the Greek alphabet
• Psi (Cyrillic) (Ѱ, ѱ), letter of the early Cyrillic alphabet, adopted from Greek

Arts and entertainment

• "Psi" as an abbreviation for psionics

Comics

• Psi (comics), DC Comics character
• Psi Division, division in the Judge Dredd and 2000 AD series of comics
• Psi-Force, comic series
• Psi-Hawk, comic character
• Psi Lords, comic series

Music

• PSI (album), album by Pitchshifter (2002)
• Psi Com, 1980s rock band
• Psi Power, song by rock group Hawkwind (1978)
• PSI Records, music record label
• Phil Spector International, record label between 1970 and 1980
• Ψ CMX DVD, Finnish language video album by the band CMX
• Pitch Shifter Industries, acronym used by the British band Pitchshifter

Other uses in arts and entertainment

• Psi (TV series), Brazil
• Psi Corps, in the Babylon 5 fictional universe, the ruling body of Earth's telepaths
• Psi Factor: Chronicles of the Paranormal, Canadian television series
• Psi-Ops: The Mindgate Conspiracy, video game in which characters use psychic powers (2004)
• PSI, the psychic power used by some characters in the EarthBound series

Organizations

Government and politics

• Italian Socialist Party (Partito Socialista Italiano), socialist and later social-democratic political party in Italy
• Italian Socialist Party (2007), social-democratic political party in Italy
• Partai Sosialis Indonesia ("Indonesian Socialist Party")
• Partai Solidaritas Indonesia ("Indonesian Solidarity Party")
• Proliferation Security Initiative, international initiative to interdict transnational transfer of banned weapons and weapons technology
• Public Sector Information, as in:
  • The European Union Directive on the re-use of public sector information (PSI directive), adopted in November 2003
  • The United Kingdom's Office of Public Sector Information (OPSI), formerly Her Majesty's Stationery Office (HMSO)
• United States Senate Homeland Security Permanent Subcommittee on Investigations, sub-committee of the U.S. Senate

Other organizations

• Paul Scherrer Institute, research institute in Villigen, Switzerland
• Pechersk School International, school in Kyiv, Ukraine
• Phi Sigma Iota, honor society
• Physics Society of Iran, scientific society in Iran
• Planetary Science Institute, research institute in Tucson, Arizona
• Poetry Slam, Inc., international nonprofit organization
• Policy Studies Institute, UK research organization
• Population Services International, nonprofit global health organization
• Professional Skills Institute, private university in Toledo, Ohio
• Professors for a Strong Israel, right-wing group of academics in Israel
• Prudential Securities Incorporated, financial services company
• PSI Seminars, provider of personal and professional development seminars
• Psychiatric Solutions, Inc., American operator of psychiatric hospitals
• Public Services International, global federation of public sector trade unions
• Statisticians in the Pharmaceutical Industry, promotes use of statistics in the pharmaceutical industry

Parapsychology

For mainstream psychology, see § Psychology.

• Psi (parapsychology), psychic or paranormal phenomena
• Psi hit, parapsychological experimentation term
• Paranormal Site Investigators, in the UK

Science, technology, and mathematics

Biology and medicine

For psychology, see § Psychology.

• PSI (prion), infectious protein in yeast
• Pandemic severity index, used by the US Centers for Disease Control and Prevention
• Photosystem I, protein complex involved in photosynthesis
• Pneumonia severity index
• Protein Structure Initiative, structural genomics initiative of the U.S. NIGMS

Computing

• Psi (instant messaging client), XMPP client program
• Potentially Shippable Increment, in the Scrum software development methodology
• Program-specific information, part of the MPEG transport stream protocol

Economics

• PSI-20, stock market index of companies that trade on Euronext Lisbon, the main stock exchange of Portugal
• Private sector involvement, in sovereign-debt restructuring deals

Engineering

• "Yaw" angle, one of the Euler angles, denoted ψ in aerospace engineering
• Present serviceability index, a pavement performance indicator introduced by AASHTO

Geography

• Psi Islands, in the Melchior Islands, Antarctica

Mathematics

• Chebyshev function
• Dedekind psi function
• Digamma function
• Polygamma functions
• Stream function, in two-dimensional flows
• Polar tangential angle of a curve
• Probability of ultimate ruin, in ruin theory
• Supergolden ratio

Physics and chemistry

• Pounds per square inch, unit of pressure
• PSI (computational chemistry), software
• J/psi meson, subatomic particle
• Porous silicon
• Water potential, denoted Ψ, in physical chemistry, the potential energy of a water solution relative to pure water
• Wave function, denoted ψ, in quantum mechanics

Psychology

For paranormal phenomena, see § Parapsychology.

• Psychology or psychologist, denoted Ψ, used in the logo of various psychological associations
• Psi Chi, the National Honor Society in psychology
• Psi-theory, theory about the human mind, a cognitive architecture
• Psychiatric Solutions, Inc., corporation that owns psychiatric hospitals

Other uses

• Parasocial interaction, non-reciprocal interactions, as between a fanbase and a performer
• Permanent staff instructor, in the British Army
• Personalized System of Instruction
• Pollutant Standards Index, air pollution measure
• Pre-shipment inspection, method of quality control
• Presentence investigation report, investigation into the history of person convicted of a crime

See also

• Psy (disambiguation)
• Ps1 (disambiguation)