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🔗 Mathematics

The Trachtenberg system is a system of rapid mental calculation. The system consists of a number of readily memorized operations that allow one to perform arithmetic computations very quickly. It was developed by the Russian Jewish engineer Jakow Trachtenberg in order to keep his mind occupied while being in a Nazi concentration camp.

The rest of this article presents some methods devised by Trachtenberg. Some of the algorithms Trachtenberg developed are ones for general multiplication, division and addition. Also, the Trachtenberg system includes some specialised methods for multiplying small numbers between 5 and 13.

The section on addition demonstrates an effective method of checking calculations that can also be applied to multiplication.

🔗 Economics 🔗 Business

The principal–agent problem, in political science, supply chain management and economics (also known as agency dilemma or the agency problem) occurs when one person or entity (the "agent"), is able to make decisions and/or take actions on behalf of, or that impact, another person or entity: the "principal". This dilemma exists in circumstances where agents are motivated to act in their own best interests, which are contrary to those of their principals, and is an example of moral hazard. Issues also arise when companies have an incentive to become increasingly deferential to management that have ownership stakes. As shareholders are dis-incentived to intervene, there are fewer checks on management. Issues can also arise among different types of management.

Common examples of this relationship include corporate management (agent) and shareholders (principal), elected officials (agent) and citizens (principal), or brokers (agent) and markets (buyers and sellers, principals). Consider a legal client (the principal) wondering whether their lawyer (the agent) is recommending protracted legal proceedings because it is truly necessary for the client's well-being, or because it will generate income for the lawyer. In fact the problem can arise in almost any context where one party is being paid by another to do something where the agent has a small or nonexistent share in the outcome, whether in formal employment or a negotiated deal such as paying for household jobs or car repairs.

The principal–agent problem typically arises where the two parties have different interests and asymmetric information (the agent having more information), such that the principal cannot directly ensure that the agent is always acting in their (the principal's) best interest, particularly when activities that are useful to the principal are costly to the agent, and where elements of what the agent does are costly for the principal to observe (see moral hazard and conflict of interest). Often, the principal may be sufficiently concerned at the possibility of being exploited by the agent that they choose not to enter into the transaction at all, when it would have been mutually beneficial: a suboptimal outcome that can lower welfare overall. The deviation from the principal's interest by the agent is called "agency costs".

The agency problem can be intensified when an agent acts on behalf of multiple principals (see multiple principal problem). When one agent acts on behalf of multiple principals, the multiple principals have to agree on the agent's objectives, but face a collective action problem in governance, as individual principals may lobby the agent or otherwise act in their individual interests rather than in the collective interest of all principals. As a result, there may be free-riding in steering and monitoring, duplicate steering and monitoring, or conflict between principals, all leading to high autonomy for the agent. The multiple principal problem is particularly serious in the public sector, where multiple principals are common and both efficiency and democratic accountability are undermined in the absence of salient governance. This problem may occur, for example, in the governance of the executive power, ministries, agencies, intermunicipal cooperation, public-private partnerships, and firms with multiple shareholders.

The relationships between investment managers and corporate management is an especially common example of the principal–agent relationship. There are several drivers of agency problems that affect investment managers of index funds and mutual funds include. First, investment managers receive a fraction of the benefits resulting from stewardship activities while having to handle all the costs. competition among investment managers is can also contribute to agency problems.And, lastly, another driver of agency problems is that investment managers can be heavily influenced by private incentives provided by the managers of corporations.

Various mechanisms may be used to align the interests of the agent with those of the principal. In employment, employers (principal) may use piece rates/commissions, profit sharing, efficiency wages, performance measurement (including financial statements), the agent posting a bond, or the threat of termination of employment to align worker interests with their own.

🔗 Philadelphia 🔗 Pennsylvania 🔗 National Register of Historic Places 🔗 Pipe organ

The Wanamaker Grand Court Organ, located in Philadelphia, Pennsylvania, is the largest fully functioning pipe organ in the world, based on the number of playing pipes, the number of ranks and its weight. The Wanamaker Organ is located within a spacious 7-story Grand Court at the John Wanamaker Store (originally Wanamaker's and most recently Macy's) and was played twice a day Monday through Saturday. The organ was featured at several special concerts held throughout the year, including events featuring the Friends of the Wanamaker Organ Festival Chorus and Brass Ensemble.

🔗 Computing 🔗 Computing/Computer hardware 🔗 Computing/Computer science

The replay system is a little-known subsystem within the Intel Pentium 4 processor. Its primary function is to catch operations that have been mistakenly sent for execution by the processor's scheduler. Operations caught by the replay system are then re-executed in a loop until the conditions necessary for their proper execution have been fulfilled.

🔗 United States 🔗 Biography 🔗 United States/Ohio 🔗 Backpacking

Emma Rowena (Caldwell) Gatewood, known as Grandma Gatewood, (October 25, 1887 – June 4, 1973), was an American ultra-light hiking pioneer. After a difficult life as a farm wife, mother of eleven children, and survivor of domestic violence, she became famous as the first solo female thru-hiker of the 2,168-mile (3,489 km) Appalachian Trail (A.T.) in 1955 at the age of 67. She subsequently became the first person (male or female) to hike the A.T. three times, after completing a second thru-hike two years later, followed by a section-hike in 1964. In the meantime, she hiked 2,000 miles (3,200 km) of the Oregon Trail in 1959. In her later years, she continued to travel and hike, and worked on a section of what would become the Buckeye Trail. The media coverage surrounding her feats was credited for generating interest in maintaining the A.T. and in hiking generally. Among many other honors, she was posthumously inducted into the Appalachian Trail Hall of Fame in 2012.

🔗 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.

🔗 Literature

A chrestomathy ( kreh-STOM-ə-thee; from the Ancient Greek χρηστομάθεια khrēstomátheia 'desire of learning', from χρηστός khrēstós 'useful' + μανθάνω manthánō 'learn') is a collection of selected literary passages (usually from a single author); a selection of literary passages from a foreign language assembled for studying the language; or a text in various languages, used especially as an aid in learning a subject.

In philology or in the study of literature, it is a type of reader which presents a sequence of example texts, selected to demonstrate the development of language or literary style. It is different from an anthology because of its didactic purpose.

🔗 Anthropology 🔗 Archaeology 🔗 Yorkshire

The Heslington Brain is a 2,600-year-old human brain found inside a skull buried in a pit in Heslington, Yorkshire, in England, by York Archaeological Trust in 2008. It is the oldest preserved brain ever found in Eurasia, and is believed to be the best-preserved ancient brain in the world. The skull was discovered during an archaeological dig commissioned by the University of York on the site of its new campus on the outskirts of the city of York. The area was found to have been the site of well-developed permanent habitation between 2,000–3,000 years before the present day.

A number of possibly ritualistic objects were found to have been deposited in several pits, including the skull, which had belonged to a man probably in his 30s. He had been hanged before being decapitated with a knife and his skull appears to have been buried immediately. The rest of the body was missing. Although it is not known why he was killed, it is possible that it may have been a human sacrifice or ritual murder.

The brain was found while the skull was being cleaned. It had survived despite the rest of the tissue on the skull having disappeared long ago. After being extracted at York Hospital, the brain was subjected to a range of medical and forensic examinations by York Archaeological Trust which found that it was remarkably intact, though it had shrunk to only about 20% of its original size. It showed few signs of decay, though most of its original material had been replaced by an as yet unidentified organic compound, due to chemical changes during burial.

According to the archaeologists and scientists who have examined it, the brain has a "resilient, tofu-like texture". It is not clear why the Heslington brain survived, although the presence of a wet, anoxic environment underground seems to have been an essential factor, and research is still ongoing to shed light on how the local soil conditions may have contributed to its preservation.

🔗 Aviation 🔗 New Zealand

On 22 December 1978, a small Cessna 188 aircraft, piloted by Jay Prochnow, became lost over the Pacific Ocean. The only other aircraft in the area that was able to assist was a commercial Air New Zealand flight. After several hours of searching, the crew of the Air New Zealand flight located the lost Cessna and led it to Norfolk Island, where the plane landed safely.

🔗 Biography 🔗 Medicine 🔗 Women's History 🔗 New York (state) 🔗 Medicine/Society and Medicine 🔗 New York (state)/Long Island 🔗 Northern Ireland

Mary Mallon (September 23, 1869 – November 11, 1938), also known as Typhoid Mary, was an Irish-born cook believed to have infected 53 people with typhoid fever, three of whom died, and the first person in the United States identified as an asymptomatic carrier of the disease, Salmonella typhi. Because she persisted in working as a cook, by which she exposed others to the disease, she was twice forcibly quarantined by authorities, eventually for the final two decades of her life. Mallon died after a total of nearly 30 years in isolation.