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🔗 Climate change 🔗 Environment 🔗 Geography 🔗 Antarctica 🔗 Arctic 🔗 Geology 🔗 Globalization 🔗 Science Policy 🔗 Weather 🔗 Sanitation

Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

The largest driver of warming is the emission of gases that create a greenhouse effect, of which more than 90% are carbon dioxide (CO
2) and methane. Fossil fuel burning (coal, oil, and natural gas) for energy consumption is the main source of these emissions, with additional contributions from agriculture, deforestation, and manufacturing. The human cause of climate change is not disputed by any scientific body of national or international standing. Temperature rise is accelerated or tempered by climate feedbacks, such as loss of sunlight-reflecting snow and ice cover, increased water vapour (a greenhouse gas itself), and changes to land and ocean carbon sinks.

Temperature rise on land is about twice the global average increase, leading to desert expansion and more common heat waves and wildfires. Temperature rise is also amplified in the Arctic, where it has contributed to melting permafrost, glacial retreat and sea ice loss. Warmer temperatures are increasing rates of evaporation, causing more intense storms and weather extremes. Impacts on ecosystems include the relocation or extinction of many species as their environment changes, most immediately in coral reefs, mountains, and the Arctic. Climate change threatens people with food insecurity, water scarcity, flooding, infectious diseases, extreme heat, economic losses, and displacement. These impacts have led the World Health Organization to call climate change the greatest threat to global health in the 21st century. Even if efforts to minimise future warming are successful, some effects will continue for centuries, including rising sea levels, rising ocean temperatures, and ocean acidification.

Many of these impacts are already felt at the current level of warming, which is about 1.2 °C (2.2 °F). The Intergovernmental Panel on Climate Change (IPCC) has issued a series of reports that project significant increases in these impacts as warming continues to 1.5 °C (2.7 °F) and beyond. Additional warming also increases the risk of triggering critical thresholds called tipping points. Responding to climate change involves mitigation and adaptation. Mitigation – limiting climate change – consists of reducing greenhouse gas emissions and removing them from the atmosphere; methods include the development and deployment of low-carbon energy sources such as wind and solar, a phase-out of coal, enhanced energy efficiency, reforestation, and forest preservation. Adaptation consists of adjusting to actual or expected climate, such as through improved coastline protection, better disaster management, assisted colonisation, and the development of more resistant crops. Adaptation alone cannot avert the risk of "severe, widespread and irreversible" impacts.

Under the 2015 Paris Agreement, nations collectively agreed to keep warming "well under 2.0 °C (3.6 °F)" through mitigation efforts. However, with pledges made under the Agreement, global warming would still reach about 2.8 °C (5.0 °F) by the end of the century. Limiting warming to 1.5 °C (2.7 °F) would require halving emissions by 2030 and achieving near-zero emissions by 2050.

🔗 International relations 🔗 Lists 🔗 Countries

This is a list of purchases of territory by a sovereign nation from another sovereign nation.

🔗 Video games

Doom, a first-person shooter game by id Software, was released in December 1993 and is considered one of the most significant and influential titles in video game history. Development began in November 1992, with programmers John Carmack and John Romero, artists Adrian Carmack and Kevin Cloud, and designer Tom Hall. Late in development, Hall was replaced by Sandy Petersen and programmer Dave Taylor joined. The music and sound effects were created by Bobby Prince.

The Doom concept was proposed in late 1992, after the release of Wolfenstein 3D and its sequel Spear of Destiny. John Carmack was working on an improved 3D game engine from those games, and the team wanted to have their next game take advantage of his designs. Several ideas were proposed, including a new game in their Commander Keen series, but John proposed a game about using technology to fight demons inspired by the Dungeons & Dragons campaigns the team played. The initial months of development were spent building prototypes, while Hall created the Doom Bible, a design document for his vision of the game and its story; after id released a grandiose press release touting features that the team had not yet begun working on, the Doom Bible was rejected in favor of a plotless game with no design document at all.

Over the next six months, Hall designed levels based on real military bases, Romero built features, and artists Adrian and Cloud created textures and demons based on clay models they built. Hall's level designs, however, were deemed uninteresting and Romero began designing his own levels; Hall, increasingly frustrated with his limited influence, was fired in July. He was replaced by Petersen in September, and the team worked increasingly long hours until the game was completed in December 1993. Doom was self-published by id on December 10, 1993, and immediately downloaded by thousands of players.

🔗 Biography 🔗 Mathematics 🔗 Germany 🔗 Physics 🔗 Women scientists 🔗 Biography/science and academia 🔗 Women's History 🔗 Women writers 🔗 Physics/Biographies 🔗 Toys

🔗 Politics 🔗 Socialism 🔗 Chicago 🔗 Holidays 🔗 Organized Labour

International Workers' Day, also called Labour Day in some countries and often referred to as May Day, is a celebration of labourers and the working classes that is promoted by the international labour movement and occurs every year on 1 May, or the first Monday in May.

Traditionally, 1 May is the date of the European spring festival of May Day. The International Workers Congress held in Paris in 1889 established the Second International for labor, socialist, and Marxist parties. It adopted a resolution for a "great international demonstration" in support of working-class demands for the eight-hour day. The date was chosen by the American Federation of Labor to commemorate a general strike in the United States, which had begun on 1 May 1886 and culminated in the Haymarket affair on 4 May. The demonstration subsequently became a yearly event. The 1904 Sixth Conference of the Second International, called on "all Social Democratic Party organisations and trade unions of all countries to demonstrate energetically on the First of May for the legal establishment of the eight-hour day, for the class demands of the proletariat, and for universal peace".

The 1st of May, or first Monday in May, is a national public holiday in many countries, in most cases known as "International Workers' Day" or a similar name. Some countries celebrate a Labour Day on other dates significant to them, such as the United States and Canada, which celebrate Labor Day on the first Monday of September. In 1955, the Catholic Church dedicated 1 May to "Saint Joseph the Worker". Saint Joseph is the patron saint of workers and craftsmen, among others.

🔗 United States 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 United States/Military history - U.S. military history 🔗 Military history/Military science, technology, and theory 🔗 Physics 🔗 Women's History 🔗 History of Science 🔗 Tennessee 🔗 Military history/World War II 🔗 Physics/History 🔗 Science

The Calutron Girls were a group of young women, mostly high school graduates who joined the World War II efforts in Oak Ridge, Tennessee in 1945.

Although they were not allowed to know at the time, they were monitoring dials and watching meters for a calutron, a mass spectrometer that separates uranium isotopes. The enriched uranium was used to make the first atomic bomb.

Calutron Girls were trained and employed at the Y-12 National Security Complex. Wartime labor shortages forced the Tennessee Eastman Corporation to hire women to work at the Y-12 plant.

According to Gladys Owens, one of the few Calutron Girls, a manager at the facility once told them: "We can train you how to do what is needed, but cannot tell you what you are doing. I can only tell you that if our enemies beat us to it, God have mercy on us!"

🔗 Telecommunications 🔗 Software 🔗 Software/Computing 🔗 Hong Kong

KaiOS is a mobile operating system based on Linux, developed by KaiOS Technologies, a US-based company. It is forked from B2G OS (Boot to Gecko OS), an open source community-driven fork of Firefox OS, which was discontinued by Mozilla in 2016.

The primary features of KaiOS bring support for 4G LTE E, VoLTE, GPS and Wi-Fi with HTML5-based apps and longer battery life to non-touch devices with optimized user interface, less memory and energy consumption. It also features over-the-air updates. A dedicated app marketplace (KaiStore) enables users to download applications. Some services are preloaded as HTML5 applications, including Twitter, Facebook and YouTube. The operating system is comparatively lightweight on hardware resource usage, and is able to run on devices with just 256 MB of memory.

The operating system first appeared in 2017 and is developed by KaiOS Technologies Inc., a San Diego, California-based company headed by CEO Sebastien Codeville with offices in other countries. In June 2018, Google invested US$22 million in the operating system. India-based telecom operator Reliance Jio also invested $7 million in cash to pick up a 16% stake in the company.

In market share study results announced in May 2018, KaiOS beat Apple's iOS for second place in India, while Android dominates with 71%, albeit down by 9%. KaiOS growth is being largely attributed to popularity of the competitively-priced Jio Phone. In Q1 2018, 23 million KaiOS devices were shipped.

KaiOS is also the name of an unrelated Linux project, dating from 2014 and targeted at embedded systems.

🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Military history/Military science, technology, and theory 🔗 Military history/Weaponry

The MIM-104 Patriot is a surface-to-air missile (SAM) system, the primary of its kind used by the United States Army and several allied nations. It is manufactured by the U.S. defense contractor Raytheon and derives its name from the radar component of the weapon system. The AN/MPQ-53 at the heart of the system is known as the "Phased Array Tracking Radar to Intercept on Target" which is a backronym for PATRIOT. The Patriot System replaced the Nike Hercules system as the U.S. Army's primary High to Medium Air Defense (HIMAD) system, and replaced the MIM-23 Hawk system as the U.S. Army's medium tactical air defense system. In addition to these roles, Patriot has been given the function of the U.S. Army's anti-ballistic missile (ABM) system, which is now Patriot's primary mission. The system is expected to stay fielded until at least 2040.

Patriot uses an advanced aerial interceptor missile and high-performance radar systems. Patriot was developed at Redstone Arsenal in Huntsville, Alabama, which had previously developed the Safeguard ABM system and its component Spartan and hypersonic speed Sprint missiles. The symbol for Patriot is a drawing of a Revolutionary War-era Minuteman.

Patriot systems have been sold to the Netherlands, Poland, Germany, Egypt, Japan, Israel, Saudi Arabia, Kuwait, Republic of China (Taiwan), Greece, Spain, United Arab Emirates, Qatar and Romania. South Korea purchased several second-hand Patriot systems from Germany after North Korea test-launched ballistic missiles to the Sea of Japan and proceeded with underground nuclear testing in 2006. Jordan also purchased several second-hand Patriot systems from Germany. Poland hosts training rotations of a battery of U.S. Patriot launchers. This started in the town of Morąg in May 2010 but was later moved further from the Russian border to Toruń and Ustka due to Russian objections. On December 4, 2012, NATO authorized the deployment of Patriot missile launchers in Turkey to protect the country from missiles fired in the civil war in neighboring Syria. Patriot was one of the first tactical systems in the U.S. Department of Defense's (DoD) to employ lethal autonomy in combat.

The Patriot system gained notoriety during the Persian Gulf War of 1991 with the claimed engagement of over 40 Iraqi Scud missiles, but those claims became a source of controversy. The system was successfully used against Iraqi missiles in 2003 Iraq War, and has been also used by Saudi and Emirati forces in the Yemen conflict against Houthi missile attacks. The Patriot system achieved its first undisputed shootdowns of enemy aircraft in the service of the Israeli Air Defense Command. Israeli MIM-104D batteries shot down two Hamas UAVs during Operation Protective Edge on August 31, 2014 and later, on September 23, 2014, an Israeli Patriot battery shot down a Syrian Air Force Sukhoi Su-24 which had penetrated Israeli airspace, achieving the first shootdown of a manned enemy aircraft in the world for the system.

🔗 Crime 🔗 COVID-19 🔗 Women's History

The Signal for Help (or the Violence at Home Signal for Help) is a single-handed gesture that can be used by an individual to alert others that they feel threatened and need help over a video call, or in-person. It was originally created as a tool to combat the rise in domestic violence cases around the world as a result of the self-isolation measures related to the COVID-19 pandemic.

The signal is performed by holding one hand up with the thumb tucked into the palm, then folding the four other fingers down, symbolically trapping the thumb in the rest of the fingers. It was intentionally designed as a single continuous hand movement, rather than a sign held in one position, that could be made easily visible.

The Signal for Help was first introduced in Canada by the Canadian Women's Foundation on April 14, 2020, and on April 28, 2020 in the United States by the Women's Funding Network (WFN). It received widespread praise from local, national, and international news organizations for helping provide a modern solution to the issue of a rise in domestic violence cases.

Addressing concerns that abusers may become aware of such a widespread online initiative, the Canadian Women's Foundation and other organizations clarified that this signal is not "something that's going to save the day," but rather a tool someone could use to get help.

Instructions for what to do if an individual sees the signal, and how to check-in safely, were also created.

🔗 Physics 🔗 Astronomy

A helium flash is a very brief thermal runaway nuclear fusion of large quantities of helium into carbon through the triple-alpha process in the core of low mass stars (between 0.8 solar masses (M_☉) and 2.0 M_☉) during their red giant phase. The Sun is predicted to experience a flash 1.2 billion years after it leaves the main sequence. A much rarer runaway helium fusion process can also occur on the surface of accreting white dwarf stars.

Low-mass stars do not produce enough gravitational pressure to initiate normal helium fusion. As the hydrogen in the core is exhausted, some of the helium left behind is instead compacted into degenerate matter, supported against gravitational collapse by quantum mechanical pressure rather than thermal pressure. Subsequent hydrogen shell fusion further increases the mass of the core until it reaches temperature of approximately 100 million kelvin, which is hot enough to initiate helium fusion (or "helium burning") in the core.

However, a fundamental quality of degenerate matter is that increases in temperature do not produce an increase in the pressure of the matter until the thermal pressure becomes so very high that it exceeds degeneracy pressure. In main sequence stars, thermal expansion regulates the core temperature, but in degenerate cores, this does not occur. Helium fusion increases the temperature, which increases the fusion rate, which further increases the temperature in a runaway reaction which quickly spans the entire core. This produces a flash of very intense helium fusion that lasts only a few minutes, but during that time, produces energy at a rate comparable to the entire Milky Way galaxy.

In the case of normal low-mass stars, the vast energy release causes much of the core to come out of degeneracy, allowing it to thermally expand. This consumes most of the total energy released by the helium flash, and any left-over energy is absorbed into the star's upper layers. Thus the helium flash is mostly undetectable by observation, and is described solely by astrophysical models. After the core's expansion and cooling, the star's surface rapidly cools and contracts in as little as 10,000 years until it is roughly 2% of its former radius and luminosity. It is estimated that the electron-degenerate helium core weighs about 40% of the star mass and that 6% of the core is converted into carbon.