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🔗 United States/U.S. Government 🔗 United States 🔗 Philately 🔗 Donald Trump 🔗 United States/U.S. presidential elections

The 2020 United States Postal Service crisis is a series of events that have caused backlogs and delays in the delivery of mail by the United States Postal Service (USPS). The crisis stems primarily from changes implemented by Postmaster General Louis DeJoy shortly after taking office in June 2020. The delays have had substantial legal, political, economic, and health repercussions.

There is controversy and speculation about whether the delays are unintended consequences of restructuring operations, or if they were intentionally created for political and/or financial gain. DeJoy has supported and donated to President Donald Trump, who has publicly linked his opposition to emergency funding for the Postal Service to his desire to restrict voting by mail in the 2020 elections.

On August 18, 2020, under heavy political and legal pressure, DeJoy announced that he would be "suspending" the policy changes until after the November 2020 election. He testified to the Senate on August 21, and to the House of Representatives on August 24, concerning the changes and their effects.

🔗 Soviet Union 🔗 Armenia

The Radio Yerevan jokes, also known as the Armenian Radio jokes, have been popular in the Soviet Union and other countries of the former Communist Eastern bloc since the second half of the 20th century. These jokes of the Q&A type pretended to come from the Question & Answer series of the Armenian Radio. A typical format of a joke was: "Radio Yerevan was asked," and "Radio Yerevan answered."

🔗 United States 🔗 Spaceflight 🔗 Automobiles

Elon Musk's Tesla Roadster is an electric sports car that served as the dummy payload for the February 2018 Falcon Heavy test flight and became an artificial satellite of the Sun. "Starman", a mannequin dressed in a spacesuit, occupies the driver's seat. The car and rocket are products of Tesla and SpaceX, respectively, both companies founded by Elon Musk. The 2008-model Roadster was previously used by Musk for commuting to work and is the only production car in space.

The car, mounted on the rocket's second stage, acquired enough velocity to escape Earth's gravity and enter an elliptical heliocentric orbit crossing the orbit of Mars. The orbit reaches a maximum distance from the Sun at aphelion of 1.66 astronomical units (au). During the early portion of the voyage outside the Earth's atmosphere, live video was transmitted back to the mission control center and live-streamed for slightly over four hours.

Advertising analysts noted Musk's sense of brand management and use of new media for his decision to launch a Tesla into space. While some commenters voiced concern that the car contributed to space debris, others saw it as a work of art. Musk explained he wanted to inspire the public about the "possibility of something new happening in space" as part of his larger vision for spreading humanity to other planets.

🔗 Telecommunications 🔗 Radio 🔗 Electronics 🔗 Engineering

A plasma antenna is a type of radio antenna currently in development in which plasma is used instead of the metal elements of a traditional antenna. A plasma antenna can be used for both transmission and reception. Although plasma antennas have only become practical in recent years, the idea is not new; a patent for an antenna using the concept was granted to J. Hettinger in 1919.

Early practical examples of the technology used discharge tubes to contain the plasma and are referred to as ionized gas plasma antennas. Ionized gas plasma antennas can be turned on and off and are good for stealth and resistance to electronic warfare and cyber attacks. Ionized gas plasma antennas can be nested such that the higher frequency plasma antennas are placed inside lower frequency plasma antennas. Higher frequency ionized gas plasma antenna arrays can transmit and receive through lower frequency ionized gas plasma antenna arrays. This means that the ionized gas plasma antennas can be co-located and ionized gas plasma antenna arrays can be stacked. Ionized gas plasma antennas can eliminate or reduce co-site interference. Smart ionized gas plasma antennas use plasma physics to shape and steer the antenna beams without the need of phased arrays. Satellite signals can be steered or focused in the reflective or refractive modes using banks of plasma tubes making unique ionized gas satellite plasma antennas. The thermal noise of ionized gas plasma antennas is less than in the corresponding metal antennas at the higher frequencies. Solid state plasma antennas (also known as plasma silicon antennas) with steerable directional functionality that can be manufactured using standard silicon chip fabrication techniques are now also in development. Plasma silicon antennas are candidates for use in WiGig (the planned enhancement to Wi-Fi), and have other potential applications, for example in reducing the cost of vehicle-mounted radar collision avoidance systems.

🔗 Astronomy 🔗 Sweden 🔗 Solar System 🔗 Astronomy/Solar System

The Sweden Solar System is the world's largest permanent scale model of the Solar System. The Sun is represented by the Ericsson Globe in Stockholm, the largest hemispherical building in the world. The inner planets can also be found in Stockholm but the outer planets are situated northward in other cities along the Baltic Sea. The system was started by Nils Brenning and Gösta Gahm and is on the scale of 1:20 million.

🔗 Mathematics 🔗 Statistics 🔗 Systems 🔗 Robotics 🔗 Systems/Control theory

In statistics and control theory, Kalman filtering, also known as linear quadratic estimation (LQE), is an algorithm that uses a series of measurements observed over time, containing statistical noise and other inaccuracies, and produces estimates of unknown variables that tend to be more accurate than those based on a single measurement alone, by estimating a joint probability distribution over the variables for each timeframe. The filter is named after Rudolf E. Kálmán, one of the primary developers of its theory.

The Kalman filter has numerous applications in technology. A common application is for guidance, navigation, and control of vehicles, particularly aircraft, spacecraft and dynamically positioned ships. Furthermore, the Kalman filter is a widely applied concept in time series analysis used in fields such as signal processing and econometrics. Kalman filters also are one of the main topics in the field of robotic motion planning and control and can be used in trajectory optimization. The Kalman filter also works for modeling the central nervous system's control of movement. Due to the time delay between issuing motor commands and receiving sensory feedback, use of the Kalman filter supports a realistic model for making estimates of the current state of the motor system and issuing updated commands.

The algorithm works in a two-step process. In the prediction step, the Kalman filter produces estimates of the current state variables, along with their uncertainties. Once the outcome of the next measurement (necessarily corrupted with some amount of error, including random noise) is observed, these estimates are updated using a weighted average, with more weight being given to estimates with higher certainty. The algorithm is recursive. It can run in real time, using only the present input measurements and the previously calculated state and its uncertainty matrix; no additional past information is required.

Optimality of the Kalman filter assumes that the errors are Gaussian. In the words of Rudolf E. Kálmán: "In summary, the following assumptions are made about random processes: Physical random phenomena may be thought of as due to primary random sources exciting dynamic systems. The primary sources are assumed to be independent gaussian random processes with zero mean; the dynamic systems will be linear." Though regardless of Gaussianity, if the process and measurement covariances are known, the Kalman filter is the best possible linear estimator in the minimum mean-square-error sense.

Extensions and generalizations to the method have also been developed, such as the extended Kalman filter and the unscented Kalman filter which work on nonlinear systems. The underlying model is a hidden Markov model where the state space of the latent variables is continuous and all latent and observed variables have Gaussian distributions. Also, Kalman filter has been successfully used in multi-sensor fusion, and distributed sensor networks to develop distributed or consensus Kalman filter.

🔗 Medicine 🔗 Biology 🔗 Skepticism 🔗 Transhumanism 🔗 Alternative Views 🔗 Guild of Copy Editors 🔗 Alternative medicine 🔗 Longevity

Life extension is the idea of extending the human lifespan, either modestly – through improvements in medicine – or dramatically by increasing the maximum lifespan beyond its generally settled limit of 125 years. The ability to achieve such dramatic changes, however, does not currently exist.

Some researchers in this area, and "life extensionists", "immortalists" or "longevists" (those who wish to achieve longer lives themselves), believe that future breakthroughs in tissue rejuvenation, stem cells, regenerative medicine, molecular repair, gene therapy, pharmaceuticals, and organ replacement (such as with artificial organs or xenotransplantations) will eventually enable humans to have indefinite lifespans (agerasia) through complete rejuvenation to a healthy youthful condition. The ethical ramifications, if life extension becomes a possibility, are debated by bioethicists.

The sale of purported anti-aging products such as supplements and hormone replacement is a lucrative global industry. For example, the industry that promotes the use of hormones as a treatment for consumers to slow or reverse the aging process in the US market generated about $50 billion of revenue a year in 2009. The use of such products has not been proven to be effective or safe.

🔗 Internet 🔗 Media 🔗 Cuba

El Paquete Semanal ("The Weekly Package") or El Paquete is a one terabyte collection of digital material distributed since around 2008 on the underground market in Cuba as a substitute for broadband Internet. Since 2015, it has been the primary source of entertainment for millions of Cubans, as Internet in Cuba has been suppressed for many years with only about a 38.8% Internet penetration rate as of 2018. El Paquete Semanal has its own page that is running in the United States, where one could view its contents and is consistently updated every week.

🔗 Food and drink 🔗 Food and drink/Foodservice

An automat is a fast food restaurant where simple foods and drink are served by vending machines. The world's first automat was named Quisisana, which opened in Berlin, Germany in 1895.

🔗 Aviation 🔗 Aviation/aircraft 🔗 Automobiles

The AVE Mizar (named after the star Mizar) was a roadable aircraft built between 1971 and 1973 by Advanced Vehicle Engineers (AVE) of Van Nuys, Los Angeles, California. The company was started by Henry Smolinski and Harold Blake, both graduates of Northrop Institute of Technology's aeronautical engineering school.