title: Coordinate-measuring machine

text: Probing systems for microscale metrology applications are another emerging area. There are several commercially available coordinate measuring machines (CMM) that have a microprobe integrated into the system, several specialty systems at government laboratories, and any number of university-built metrology platforms for microscale metrology. Although these machines are good and in many cases excellent metrology platforms with nanometric scales, their primary limitation is a reliable, robust, capable micro/nano probe. Challenges for microscale probing technologies include the need for a high aspect ratio probe giving the ability to access deep, narrow features with low contact forces so as to not damage the surface and high precision (nanometer level). Additionally microscale probes are susceptible to environmental conditions such as humidity and surface interactions such as stiction (caused by adhesion, meniscus, and/or Van der Waals forces among others).


title: Coordinate-measuring machine

text: Technologies to achieve microscale probing include scaled down version of classical CMM probes, optical probes, and a standing wave probe among others. However, current optical technologies cannot be scaled small enough to measure deep, narrow feature, and optical resolution is limited by the wavelength of light. X-ray imaging provides a picture of the feature but no traceable metrology information.


title: Coordinate-measuring machine

text: Optical probes and/or laser probes can be used (if possible in combination), which change CMMs to measuring microscopes or multi-sensor measuring machines. Fringe projection systems, theodolite triangulation systems or laser distant and triangulation systems are not called measuring machines, but the measuring result is the same: a space point. Laser probes are used to detect the distance between the surface and the reference point on the end of the kinematic chain (i.e.: end of the Z-drive component). This can use an interferometrical function, focus variation, light deflection or a beam shadowing principle.


title: Coordinate-measuring machine

text: Whereas traditional CMMs use a probe that moves on three Cartesian axes to measure an object's physical characteristics, portable CMMs use either articulated arms or, in the case of optical CMMs, arm-free scanning systems that use optical triangulation methods and enable total freedom of movement around the object.


title: Coordinate-measuring machine

text: Portable CMMs with articulated arms have six or seven axes that are equipped with rotary encoders, instead of linear axes. Portable arms are lightweight (typically less than 20 pounds) and can be carried and used nearly anywhere. However, optical CMMs are increasingly being used in the industry. Designed with compact linear or matrix array cameras (like the Microsoft Kinect), optical CMMs are smaller than portable CMMs with arms, feature no wires, and enable users to easily take 3D measurements of all types of objects located almost anywhere.


title: Coordinate-measuring machine

text: Certain nonrepetitive applications such as reverse engineering, rapid prototyping, and large-scale inspection of parts of all sizes are ideally suited for portable CMMs. The benefits of portable CMMs are multifold. Users have the flexibility in taking 3D measurements of all types of parts and in the most remote/difficult locations. They are easy to use and do not require a controlled environment to take accurate measurements. Moreover, portable CMMs tend to cost less than traditional CMMs.


title: Coordinate-measuring machine

text: The inherent trade-offs of portable CMMs are manual operation (they always require a human to use them). In addition, their overall accuracy can be somewhat less accurate than that of a bridge type CMM and is less suitable for some applications.


title: Coordinate-measuring machine

text: Traditional CMM technology using touch probes is today often combined with other measurement technology. This includes laser, video or white light sensors to provide what is known as multisensor measurement.


title: Coordinate-measuring machine

text: To verify the performance of a coordinate measurement machine, the ISO 10360 series is available. This series of standards define the characteristics of the probing system and the length measurement error:


title: Peace treaty

text: A peace treaty is an agreement between two or more hostile parties, usually countries or governments, which formally ends a state of war between the parties. It is different from an armistice, which is an agreement to stop hostilities; a surrender, in which an army agrees to give up arms; or a ceasefire or truce, in which the parties may agree to temporarily or permanently stop fighting. The art of negotiating a peace treaty in the modern era has been referred to by legal scholar Christine Bell as the , with a peace treaty potentially contributing to the legal framework governing the post conflict period, or .


title: Peace treaty

text: The content of a treaty usually depends on the nature of the conflict being concluded. In the case of large conflicts between numerous parties, international treaty covering all issues or separate treaties signed between each party.


title: Peace treaty

text: In modern history, certain intractable conflict situations may be brought to a ceasefire before they are dealt with via a peace process in which a number of discrete steps are taken on each side to reach the mutually-desired eventual goal of peace and the signing of a treaty.


title: Peace treaty

text: A peace treaty also is often not used to end a civil war, especially in cases of a failed secession, as it implies mutual recognition of statehood. In cases such as the American Civil War, it usually ends when the losing side's army surrenders and its government collapses. By contrast, a successful secession or declaration of independence is often formalized by means of a peace treaty.


title: Peace treaty

text: Treaties are often ratified in territories deemed neutral in the previous conflict and delegates from the neutral countries acting as witnesses to the signatories.


title: Peace treaty

text: Since its founding after World War II the United Nations has sought to act as a forum for resolution in matters of international conflict.


title: Peace treaty

text: A number of international treaties and obligations are involved in which member states seek to limit and control behavior during wartime. The action of declaring war is now very unlikely to be undertaken.


title: Peace treaty

text: Since the end of World War II, United Nations Charter Article 2 restricts the use of military force. The UN Charter allows only two exceptions: "military measures by UN Security Council resolutions" and "exercise of self-defense" in countries subjected to armed attacks in relation to the use of force by states. Under the current UN system, war is triggered only by the enforcement of military measures under UN Security Council resolutions or the exercise of self-defense rights against illegal armed attacks.


title: Peace treaty

text: Therefore, if the use of military force arises, it is called 'international armed conflict' instead of 'war'. The fact that the current international law system avoids the use of the term 'war' also avoids the conclusion of a peace treaty based on the existence of war. A peace treaty was not signed after the end of the Iraq War in 2003, and only the UN Security Council Resolution 1483, adopted on May 22, 2003, stipulated the postwar regime for the stability and security of Iraq exclusively.


title: Peace treaty

text: One of the UN's roles in peace processes is to conduct post-conflict elections but, on the whole, they are thought to have no effect, or even a negative effect, on peace after civil war.


title: Peace treaty

text: However, when peace agreements transform rebel groups into political parties, the effect on peace is positive, especially if international interveners use their moments of power distribution to hold the former combatants to the terms of their peace agreement.


title: Peace treaty

text: Probably the earliest recorded peace treaty, although it is rarely mentioned or remembered, was between the Hittite Empire and the Hayasa-Azzi confederation, around 1350 BC. More famously, one of the earliest recorded peace treaties was concluded between the Hittite and the Egyptian Empires after 1274 BC Battle of Kadesh (see Egyptian-Hittite peace treaty). The battle took place in what is modern-day Syria, the entire Levant being at that time contested between the two empires. After an extremely costly four-day battle, in which neither side gained a substantial advantage, both sides claimed victory. The lack of resolution led to further conflict between Egypt and the Hittites, with Ramesses II capturing the city of Kadesh and Amurru in his 8th year as king. However, the prospect of further protracted conflict between the two states eventually persuaded both their rulers, Hatusiliš III and Ramesses, to end their dispute and sign a peace treaty. Neither side could afford the possibility of a longer conflict since they were threatened by other enemies: Egypt was faced with the task of defending its long western border with Libya against the incursion of Libyan tribesmen by building a chain of fortresses stretching from Mersa Matruh to Rakotis, and the Hittites faced a more formidable threat in the form of the Assyrian Empire, which "had conquered Hanigalbat, the heartland of Mitanni, between the Tigris and the Euphrates" rivers, which had previously been a Hittite vassal state.


title: Peace treaty

text: The peace treaty was recorded in two versions, one in Egyptian hieroglyphs, and the other in Akkadian using cuneiform script; both versions survive. Such dual-language recording is common to many subsequent treaties. The treaty differs from others, however, in that the two language versions are worded differently. Although the majority of the text is identical, the Hittite version claims that the Egyptians came suing for peace, and the Egyptian version claims the reverse. The treaty was given to the Egyptians in the form of a silver plaque, and the "pocket-book" version was taken back to Egypt and carved into the Temple of Karnak.


title: Peace treaty

text: The Treaty was concluded between Ramesses II and Hatusiliš III in the twenty-first year of Ramesses' reign (c. 1258 BC). Its eighteen articles call for peace between Egypt and Hatti and then proceed to maintain that their respective people also demand peace. It contains many elements found in more modern treaties, but it is more far-reaching than later treaties' simple declaration of the end of hostilities. It also contains a mutual-assistance pact in case one of the empires should be attacked by a third party or in the event of internal strife. There are articles pertaining to the forced repatriation of refugees and provisions that they should not be harmed, which might be thought of as the first extradition treaty. There are also threats of retribution, should the treaty be broken.


title: Peace treaty

text: The treaty is considered of such importance in the field of international relations that a replica of it hangs in the UN's headquarters.


title: Peace treaty

text: Following the five years war between Kushite Kandake, Amanirenas and Augustus of Rome, a peace treaty was conducted in the year 21/20 BC. Mediators were sent from Kush to Augustus who was in Samos at that time. An entente between the two parties was beneficial to both. The Kushites were a regional power in their own right and resented paying tribute. The Romans also sought a quiet southern border for their absolutely essential Egyptian grain supplies, without constant war commitments, and welcomed a friendly buffer state in a border region beset with raiding nomads. The Kushites too appear to have found nomads like the Blemmyes to be a problem. The conditions were ripe for a deal. During negotiations, Augustus granted the Kushite envoys all they asked for, and also cancelled the tribute earlier demanded by Rome. Premmis (Qasr Ibrim), and areas north of Qasr Ibrim in the southern portion of the "Thirty-Mile Strip" were ceded to the Kushites. The Dodekaschoinos was established as a buffer zone, and Roman forces were pulled back to the old Greek Ptolemaic border at Maharraqa. Roman emperor Augustus signed the treaty with the Kushites on Samos. The settlement bought Rome peace and quiet on its Egyptian frontier, as well as increased the prestige of Roman Emperor Augustus, demonstrating his skill and ability to broker peace without constant warfare, and do business with the distant Kushites, who a short time earlier had been fighting his troops. The respect accorded the emperor by the Kushite envoys as the treaty also created a favorable impression with other foreign ambassadors present on Samos, including envoys from India, and strengthened Augustus' hand in upcoming negotiations with the powerful Parthians. The settlement ushered in a period of peace between the two empires for around three centuries. Inscriptions erected by Queen Amanirenas on an ancient temple at Hamadab, south of Meroe, record the war and the favorable outcome from the Kushite perspective. Along with his signature on the official treaty, Roman emperor Augustus marked the agreement by directing his administrators to collaborate with regional priests in the erection of a temple at Dendur, and inscriptions depict the emperor himself celebrating local deities.


title: Peace treaty

text: Famous examples include the Treaty of Paris (1815), signed after Napoleon's defeat at the Battle of Waterloo, and the Treaty of Versailles, formally ending the First World War between Germany and the Allies. Despite popular belief, the war did not end completely until the Allies concluded peace with the Ottoman Empire in 1919 at the Treaty of Sèvres.


title: Peace treaty

text: The Treaty of Versailles, as well as the Kellogg-Briand Pact, is possibly the most notorious of peace treaties, and is blamed by many historians for the rise of Nazism in Germany and the eventual outbreak of the Second World War in 1939. The costly reparations that Germany was forced to pay the victors, the fact that Germany had to accept sole responsibility for starting the war, and the harsh restrictions on German rearmament were all listed in the Treaty of Versailles and caused massive resentment in Germany. Whether or not the treaty can be blamed for starting another war, it exemplifies the difficulties involved in making peace. However, no such conflict resulted from the more punitive settlement with the Ottoman Empire.


title: Peace treaty

text: Another famous example would be the series of peace treaties known as the Peace of Westphalia. It initiated modern diplomacy, involving the modern system of nation-states. Subsequent wars were no longer over religion but revolved around issues of state. That encouraged Catholic and Protestant powers to ally, leading to a number of major realignments.


title: Peace treaty

text: The Korean War is an example of a conflict that was ended by an armistice, rather than a peace treaty with the Korean Armistice Agreement. However, that war has never technically ended, because a final peace treaty or settlement has never been achieved.


title: Peace treaty

text: A more recent example of a peace treaty is the 1973 Paris Peace Accords that sought to end the Vietnam War.


title: Alexander Nübel

text: Alexander Nübel (born 30 September 1996) is a German professional footballer who plays as a goalkeeper for Ligue 1 club Monaco, on loan from Bayern Munich.


title: Alexander Nübel

text: Nübel grew up in Salzkotten-Tudorf in East Westphalia, and began playing football at TSV Tudorf. In 2005 he moved to the youth department of SC Paderborn, where he was initially active as an outfield player until under-14 level. Initially with Paderborn, he moved up to the professional squad for the 2014–15 season, but remained inactive throughout the season.


title: Alexander Nübel

text: Nübel then moved to Schalke 04, where he was utilised in the second team competing in the Regionalliga West. On 14 May 2016, he made his Bundesliga debut against TSG Hoffenheim when he replaced Ralf Fährmann after 90 minutes.


title: Alexander Nübel

text: Nübel started the season as Schalke's backup goalkeeper to Fährmann. On 24 October 2018, he made his Champions League debut for Schalke in a 0–0 away draw against Galatasaray.


title: Alexander Nübel

text: After the winter break, Schalke's head coach Domenico Tedesco, dropped Fährmann as the club's first-choice goalkeeper and promoted Nübel. On 2 February 2019, Nübel was sent off with a straight red card in a match against Borussia Mönchengladbach and was suspended for the club's next two Bundesliga matches. He started in every match for Schalke after he was selected as the first-choice goalkeeper, with the exception of the two matches he was suspended for.


title: Alexander Nübel

text: On 6 August 2019, Nübel was selected by Schalke's head coach David Wagner as the club's new captain. He entered the season with only one year left on his contract with Schalke. On 22 December 2019, Schalke revealed that Nübel had informed the club that he would not renew his contract. On 4 January 2020, Nübel agreed to join Bayern Munich on a free transfer at the end of the season. He then handed the captaincy over to Omar Mascarell.


title: Alexander Nübel

text: Nübel joined Bayern Munich on 30 June 2020. He made his debut for Bayern in the first round of the DFB-Pokal on 15 October where the club defeated fifth division side 1. FC Düren by a score of 3–0. On 1 December 2020, he made his Champions League debut in a 1–1 away draw against Atlético Madrid. On 15 May 2021, he made his Bundesliga debut in a 2–2 away draw against Freiburg.


title: Alexander Nübel

text: On 27 June 2021, Nübel was loaned out to Monaco on a two-season loan, with Bayern having the option to cut the loan short after one season.


title: Micah Hyde (American football)

text: Micah Richmond Hyde (born December 31, 1990) is an American football free safety for the Buffalo Bills of the National Football League (NFL). He played college football at Iowa and was drafted by the Green Bay Packers in the fifth round of the 2013 NFL Draft.


title: Micah Hyde (American football)

text: Hyde was born in Fostoria, Ohio, and attended Fostoria High School where he lettered in three sports: baseball, basketball and football. On the gridiron, he was a team captain during his sophomore, junior, and senior seasons with the team. As a junior, Hyde earned northern Ohio first-team honors as a quarterback, defensive back, and place kicker. He was also named honorable mention as a punter. He was additionally named a first-team defensive back and quarterback in his senior year. He also earned first-team all-conference basketball and baseball honors and averaged 22 points a game in basketball during his time there. During his career, he had 165 tackles, eight interceptions and seven defended passes as a cornerback. As a quarterback, he had 549 rushing attempts for 3,443 yards and 46 touchdowns and also completed 606 out of 997 passes for 7,864 yards and 65 touchdowns. Hyde broke 17 school records, including those for touchdown passes in a season and a career.


title: Micah Hyde (American football)

text: Hyde was heavily recruited coming out of high school and received scholarship offers from numerous schools including Iowa, Ball State, Bowling Green, Miami (OH), Ohio, and Toledo. He was ranked as a two-star dual-threat quarterback by Rivals.com He ran the 40-yard dash in 4.45 seconds, had a 3.2 grade point average at Fostoria and scored a 20 on his ACT.


title: Micah Hyde (American football)

text: Hyde ultimately decided to play for the Iowa Hawkeyes and competed mainly on special teams and on a defense that had 11 players who would go on to be drafted into the NFL. He received his first college playing time in a game against Northern Iowa and contributed one tackle on special teams. He also appeared against the Michigan Wolverines and recorded two tackles.


title: Micah Hyde (American football)

text: During his sophomore year, Hyde played a much more expanded role on defense and started all 13 games at cornerback. He made his first big impact in a game against the Ball State Cardinals, where he forced a fumble and intercepted a pass. Later in the season when the Hawkeyes played Michigan State, Hyde scored his first touchdown on a lateral from teammate Tyler Sash late in the first quarter. He finished the season with a career-high in tackles with 82, 58 of them solo, with 4 interceptions. His performance led to him being named as an honorable mention to the All-Big Ten team.


title: Micah Hyde (American football)

text: After the successes of his second year, Hyde was rotated between free safety and cornerback during spring practice and started the first two games at safety. He was moved back to cornerback against Pittsburgh and had two interceptions, the second winning the game for the Hawkeyes as it allowed them to run the clock out. He finished the year with 72 tackles (1.5 for loss), 3 interceptions, and a forced fumble. He was named an honorable mention to the All-Big Ten team.


title: Micah Hyde (American football)

text: In his final year with the Hawkeyes, Hyde was named a first-team All-Big Ten selection and also won the Tatum-Woodson Award, annually given to the best defensive back in the conference. He finished his career starting every game for three consecutive seasons. He finished his senior year with 78 tackles, 14 defensed passes, an interception, three forced fumbles and two fumble recoveries.


title: Micah Hyde (American football)

text: Hyde was one of 60 defensive backs to attend the NFL Scouting Combine in Indianapolis, Indiana and performed all of the combine drills. On March 25, 2013, Hyde attended Iowa's Pro Day and ran positional drills. He attempted to perform better in multiple combine drills, but was only able to lower his time in the three-cone drill (6.67s). He was projected to be a sixth round pick by NFL draft experts and scouts. He was also ranked the 25th best cornerback prospect in the draft by DraftScout.com.


title: Micah Hyde (American football)

text: The Green Bay Packers selected Hyde in the fifth round (159th overall) of the 2013 NFL Draft. He was the 23rd cornerback selected in 2013. It was speculated by draft analysts and media members that his fall from the fifth round was in part due to his past arrest (see Personal life).


title: Micah Hyde (American football)

text: On May 10, 2013, the Green Bay Packers signed Hyde to a four-year, $2.33 million contract that includes a signing bonus of $178,108.


title: Micah Hyde (American football)

text: Throughout training camp, Hyde competed to be a backup cornerback against Casey Hayward, Davon House, Jarrett Bush, and James Nixon. Head coach Mike McCarthy named Hyde the fifth cornerback on the Packers' depth chart to start the regular season, behind Sam Shields, Tramon Williams, Casey Hayward, and Davon House. He was also selected to be a backup punt and kick returner by special teams coordinator Shawn Slocum.


title: Micah Hyde (American football)

text: He made his professional regular season debut in the Green Bay Packers' season-opener at the San Francisco 49ers and recorded four combined tackles during their 34–28 loss. Hyde recorded his first career tackle on wide receiver Anquan Boldin after a nine-yard reception in the first quarter. Hyde was promoted to first-team nickelback after Casey Hayward aggravated a hamstring injury during their third preseason game and was sidelined for the first seven regular season games. In Week 5, Hyde returned the first punt of his career for a two-yard gain before being tackled by Don Carey in the third quarter of the Packers' 22–9 win against the Detroit Lions. On October 13, 2013, Hyde recorded a season-high seven combined tackles and made his first career sack on quarterback Joe Flacco during a 19–17 victory at the Baltimore Ravens in Week 6. On October 27, 2013, he made six combined tackles and returned a punt for a 93-yard touchdown during a 44–31 victory at the Minnesota Vikings. His touchdown marked the first score of his career and occurred in the second quarter off a 53-yard punt by Jeff Locke. On December 22, 2013, Hyde earned his first career start and recorded six combined tackles during a 38–31 loss to the Pittsburgh Steelers in Week 16. He also returned five kicks for 167 yards during their matchup against the Steelers. Hyde finished his rookie season with 55 combined tackles (41 solo), two pass deflections, and a sack in 16 games and three starts. As a returner, he finished the season with 22 kick returns (24.14 YPR) for 531 yards and 24 punt returns for 296 yards (12.33 YPR) and a touchdown.


title: Micah Hyde (American football)

text: The Green Bay Packers finished the season atop the NFC North with an 8–7–1 record. On January 5, 2014, Hyde appeared in his first career playoff game and collected five combined tackles and a pass deflection in the Packers' 23–20 loss to the San Francisco 49ers in the NFC Wildcard Game.


title: Micah Hyde (American football)

text: During organized team activities, Hyde began to transition to free safety. Head coach Mike McCarthy opted to change his position due to the Packers lack of depth at safety after the departure of M. D. Jennings to the Chicago Bears in free agency. Throughout training camp, Hyde competed against rookie first round pick Ha Ha Clinton-Dix for the job as the starting free safety. Defensive coordinator Dom Capers named Hyde the starting free safety to start the regular season, opposite strong safety Morgan Burnett. He also remained the backup kick and punt returner for the season.


title: Micah Hyde (American football)

text: He started the Green Bay Packers' season-opener at the Seattle Seahawks and made five combined tackles in their 36–16 loss. On October 26, 2014, Hyde recorded a season-high seven combined tackles during a 44–23 loss at the New Orleans Saints in Week 8. In Week 10, Hyde made a season-high two pass deflections, a tackle, and his first career interception in the Packers' 55–14 victory against the Chicago Bears. His interception occurred in the first quarter off a pass by quarterback Jay Cutler and was originally intended for tight end Martellus Bennett. On November 16, 2014, Hyde collected four solo tackles, broke up a pass, and returned a punt by Donnie Jones for a 75-yard touchdown during a 53–20 victory against the Philadelphia Eagles. On November 23, 2014, he made four solo tackles, a pass deflection, a sack, and intercepted a pass by Teddy Bridgewater during a 24–21 win at the Minnesota Vikings. He finished the season with 59 combined tackles (45 solo), seven pass deflections, two interceptions, and a sack in 16 games and 12 starts. Hyde also had 14 punt returns for 221 yards and two touchdowns in 2014.


title: Micah Hyde (American football)

text: The Green Bay Packers finished first in their division with a 12–4 record and went on to defeat the Dallas Cowboys in the NFC Divisional Round. On January 18, 2015, Hyde made his first start in a playoff game and made a tackle during a 28–22 loss at the Seattle Seahawks in the NFC Championship Game.


title: Micah Hyde (American football)

text: During training camp, Hyde competed against Casey Hayward to be the Packers' starting nickelback. He was named the backup free safety, behind Ha Ha Clinton-Dix, and the starting nickelback to begin the regular season.


title: Micah Hyde (American football)

text: He started at strong safety in the season-opener and for four other games (Weeks 3–6) after Morgan Burnett sustained a calf injury. On October 18, 2015, Hyde recorded a season-high nine combined tackles and a pass deflection during a 27–20 victory against the San Diego Chargers. Hyde was inactive for the Packers' Week 12 loss to the Chicago Bears due to a hip injury. He finished the season with 55 combined tackles (51 solo), six pass deflections, three interceptions, and a sack in 15 games and seven starts. Hyde also returned eight kicks for 187 yards and 27 punts for 157 yards.


title: Micah Hyde (American football)

text: The Green Bay Packers finished second in the NFC North with a 10-6 record. On January 10, 2016, Hyde made eight combined tackles and a pass deflection in the Packers' 35–18 victory at the Washington Redskins in the NFC Wildcard Game. The Packers were eliminated from the playoffs after losing 26–20 at the Arizona Cardinals in the NFC Divisional Round the following week.


title: Micah Hyde (American football)

text: Head coach Mike McCarthy named Hyde the No. 1 nickelback and backup strong safety, behind Morgan Burnett, to start the 2016 regular season.


title: Micah Hyde (American football)

text: In Week 3, he started at strong safety after Morgan Burnett was declared inactive due to a groin injury. In his place, Hyde recorded a season-high 11 combined tackles (eight solo) during a 34–27 win over the Detroit Lions. On December 18, 2016, Hyde recorded a season-high three pass deflections, three solo tackles, and intercepted a pass by Jay Cutler in the Packers' 30–27 victory at the Chicago Bears. He finished the season with 58 combined tackles (47 solo), nine pass deflections, three interceptions, and a sack in 16 games and 11 starts. He received an overall grade of 73.9 from Pro Football Focus and ranked 53rd among qualified safeties.


title: Micah Hyde (American football)

text: The Green Bay Packers finished atop the NFC North with a 10–6 record. On January 8, 2017, Hyde made seven combined tackles and a pass deflection during a 36–13 victory against the New York Giants in the NFC Wildcard Game. The following week, he recorded four solo tackles, two pass deflections, and intercepted a pass by Dak Prescott during a 34–31 victory against the Dallas Cowboys in the NFC Divisional Round. The Green Bay Packers were eliminated after losing 44–21 to the Atlanta Falcons in the NFC Championship Game.


title: Micah Hyde (American football)

text: After the 2016 season, Hyde became an unrestricted free agent. Packers' general manager Ted Thompson neglected to make Hyde a contract offer and later apologized for not being able to work out a deal. He was named as one of the most overlooked free agents on the market and was named one of the top sleeper free agents. It was reported by NFL analyst Ian Rapoport that Hyde had received two strong offers.


title: Micah Hyde (American football)

text: On March 9, 2017, the Buffalo Bills signed Hyde to a five-year, $30.50 million contract that includes $14 million guaranteed and a signing bonus of $8 million.


title: Micah Hyde (American football)

text: Head coach Sean McDermott named Hyde the starting free safety to begin the regular season, along with strong safety Jordan Poyer.


title: Micah Hyde (American football)

text: He made his Buffalo Bills regular season debut in their season-opener against the New York Jets and recorded three solo tackles, broke up a pass, and intercepted a pass by Josh McCown in the 21–12 victory. On October 1, 2017, Hyde made seven combined tackles, two pass deflections, and intercepted two passes by Matt Ryan during a 23–17 win at the Atlanta Falcons. It marked Hyde's first time intercepting multiple passes in a single game. In Week 8, he recorded five solo tackles, a pass deflection, and intercepted a pass by Derek Carr in the Bills' 34–14 win against the Oakland Raiders. On November 2, 2017, Hyde was named the AFC Defensive Player of the Month for October after making four interceptions in the last four games. On December 3, 2017, he collected a career-high 12 combined tackles (ten solo) and a pass deflection during a 23–3 loss to the New England Patriots in Week 13. On December 19, 2017, it was announced that Hyde was voted to the 2018 Pro Bowl, marking the first time he received the honor. He finished his first season with the Buffalo Bills with 82 combined tackles (65 solo), 13 pass deflections, and five interceptions in 16 games and 16 starts. He set new career-highs in all four statistical categories. Pro Football Focus gave Hyde an overall grade of 86.2, ranking 14th among all qualified safeties in 2017. Hyde and Poyer were one of the highest graded safety duos in 2017 and were considered as possibly the best tandem in the league by many NFL analysts and media members. He was ranked 62nd by his peers on the NFL Top 100 Players of 2018.


title: Micah Hyde (American football)

text: The Buffalo Bills finished second in the AFC East with a 9–7 record and received a wildcard berth. On January 7, 2018, Hyde recorded four solo tackles before exiting the Bills' 10–3 loss at the Jacksonville Jaguars in the fourth quarter after sustaining a concussion.


title: Micah Hyde (American football)

text: Hyde started 15 games at safety in 2018, missing one game due to a groin injury. He finished the season with 2 interceptions, 58 combined tackles, 5 passes defensed and a fumble recovery. He also saw significant time as a punt returner. Despite his statistically quiet season, the Bills finished with the league's second-ranked pass defense.


title: Micah Hyde (American football)

text: In week 4 against the New England Patriots, Hyde intercepted Tom Brady in the end zone. Other notable plays in Hyde's 2019 season included returning an onside kick for a touchdown to clinch a 31–21 Bills win over the Miami Dolphins in week 7, and a fumble recovery in the week 16 rematch against the Patriots.


title: Micah Hyde (American football)

text: In Week 13 against the San Francisco 49ers on "Monday Night Football", Hyde recorded a team high 12 tackles and his first interception of the season off a pass thrown by Nick Mullens during the 34–24 win.


title: Micah Hyde (American football)

text: In the Wild Card Round of the playoffs against the Indianapolis Colts, Hyde broke up a pass thrown by Philip Rivers on fourth down late in the fourth quarter to secure a 27–24 win for the Bills.


title: Micah Hyde (American football)

text: Prior to the 2021 season, Hyde signed a two-year, $19.25 million contract extension with the Bills on March 5, 2021, keeping him under contract through 2023. For the season, Hyde tied his career high for interceptions, fumble recoveries, and scored his first career touchdown in Week 5 after intercepting Chiefs quarterback Patrick Mahomes. They faced the Chiefs again in the AFC Divisional Round where lost 42–36 in overtime. Hyde was named a second-team All-Pro at safety for the second time in his career.


title: Micah Hyde (American football)

text: Hyde has an older brother named Marcus who played safety for Michigan State's football team from 2006-2010.


title: Micah Hyde (American football)

text: On October 5, 2012, Hyde was arrested for public intoxication and interference with official acts by the Iowa City Police Department. It was reported that Hyde and a group of 15 people declined to leave Old Capitol Brew Works after staff asked multiple times around closing. After Iowa City Police arrived, Hyde and a group of friends were pointed out by staff as some of the subjects involved in the disturbance. Police confronted the group, but their commands to stop and flashing lights were ignored by the group and they all fled on foot. Hyde was apprehended two blocks away and police claimed he had bloodshot eyes and multiple signs of impairment. He was arrested and lodged in Johnson County Jail until he bonded out at 11AM. He appeared in court two days later and pled guilty to interfering with an official and paid a $397.50 fine. He pled not guilty to the charge of public intoxication and was given a new court date.


title: Micah Hyde (American football)

text: On December 9, 2012, Hyde was charged with disorderly conduct after Iowa City Police arrived at his apartment building due to complaints of a loud party on the top floor of the building. He was not arrested, but was cited for misdemeanor disorderly conduct and given a court date.


title: Micah Hyde (American football)

text: On July 7, 2018, Micah married Amanda Kamiksisian. The Hydes have a son, Micah, Jr., born March 2020, and a daughter, Maverick Hudson Hyde, born in August 2021.


title: Free Download Manager

text: Free Download Manager is proprietary software, but was free and open-source software between versions 2.5 and 3.9.7. Starting with version 3.0.852 (15 April 2010), the source code was made available in the project's Subversion repository instead of being included with the binary package. This continued until versions 3.9.7. The source code for version 5.0 and newer is not available and the GNU General Public License agreement has been removed from the app.


title: Free Download Manager

text: The ability to download YouTube videos was included in the program's functionality until October 16th, 2021, when one of the developers, Alex, indicated that Google had filed a complaint report, requesting the option be disabled. Attempts to download any videos from YouTube currently result in the message, "Youtube downloads are not available" being shown in the download box. A resolution with Google's legal team still has yet to be reached.


title: Volcanic ash

text: Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as "tephra"), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away.


title: Volcanic ash

text: Due to its wide dispersal, ash can have a number of impacts on society, including animal and human health, disruption to aviation, disruption to critical infrastructure (e.g., electric power supply systems, telecommunications, water and waste-water networks, transportation), primary industries (e.g., agriculture), buildings and structures.


title: Volcanic ash

text: Volcanic ash is formed during explosive volcanic eruptions and phreatomagmatic eruptions, and may also be formed during transport in pyroclastic density currents.


title: Volcanic ash

text: Explosive eruptions occur when magma decompresses as it rises, allowing dissolved volatiles (dominantly water and carbon dioxide) to exsolve into gas bubbles. As more bubbles nucleate a foam is produced, which decreases the density of the magma, accelerating it up the conduit. Fragmentation occurs when bubbles occupy ~70–80 vol% of the erupting mixture. When fragmentation occurs, violently expanding bubbles tear the magma apart into fragments which are ejected into the atmosphere where they solidify into ash particles. Fragmentation is a very efficient process of ash formation and is capable of generating very fine ash even without the addition of water.


title: Volcanic ash

text: Volcanic ash is also produced during phreatomagmatic eruptions. During these eruptions fragmentation occurs when magma comes into contact with bodies of water (such as the sea, lakes and marshes) groundwater, snow or ice. As the magma, which is significantly hotter than the boiling point of water, comes into contact with water an insulating vapor film forms (Leidenfrost effect). Eventually this vapor film will collapse leading to direct coupling of the cold water and hot magma. This increases the heat transfer which leads to the rapid expansion of water and fragmentation of the magma into small particles which are subsequently ejected from the volcanic vent. Fragmentation causes an increase in contact area between magma and water creating a feedback mechanism, leading to further fragmentation and production of fine ash particles.


title: Volcanic ash

text: Pyroclastic density currents can also produce ash particles. These are typically produced by lava dome collapse or collapse of the eruption column. Within pyroclastic density currents particle abrasion occurs as particles violently collide, resulting in a reduction in grain size and production of fine grained ash particles. In addition, ash can be produced during secondary fragmentation of pumice fragments, due to the conservation of heat within the flow. These processes produce large quantities of very fine grained ash which is removed from pyroclastic density currents in co-ignimbrite ash plumes.


title: Volcanic ash

text: Physical and chemical characteristics of volcanic ash are primarily controlled by the style of volcanic eruption. Volcanoes display a range of eruption styles which are controlled by magma chemistry, crystal content, temperature and dissolved gases of the erupting magma and can be classified using the volcanic explosivity index (VEI). Effusive eruptions (VEI 1) of basaltic composition produce <10 m of ejecta, whereas extremely explosive eruptions (VEI 5+) of rhyolitic and dacitic composition can inject large quantities (>10 m) of ejecta into the atmosphere.


title: Volcanic ash

text: The types of minerals present in volcanic ash are dependent on the chemistry of the magma from which it erupted. Considering that the most abundant elements found in silicate magma are silicon and oxygen, the various types of magma (and therefore ash) produced during volcanic eruptions are most commonly explained in terms of their silica content. Low energy eruptions of basalt produce a characteristically dark coloured ash containing ~45–55% silica that is generally rich in iron (Fe) and magnesium (Mg). The most explosive rhyolite eruptions produce a felsic ash that is high in silica (>69%) while other types of ash with an intermediate composition (e.g., andesite or dacite) have a silica content between 55–69%.


title: Volcanic ash

text: The principal gases released during volcanic activity are water, carbon dioxide, hydrogen, sulfur dioxide, hydrogen sulfide, carbon monoxide and hydrogen chloride. The sulfur and halogen gases and metals are removed from the atmosphere by processes of chemical reaction, dry and wet deposition, and by adsorption onto the surface of volcanic ash.


title: Volcanic ash

text: It has long been recognised that a range of sulfate and halide (primarily chloride and fluoride) compounds are readily mobilised from fresh volcanic ash. It is considered most likely that these salts are formed as a consequence of rapid acid dissolution of ash particles within eruption plumes, which is thought to supply the cations involved in the deposition of sulfate and halide salts.


title: Volcanic ash

text: While some 55 ionic species have been reported in fresh ash leachates, the most abundant species usually found are the cations Na, K, Ca and Mg and the anions Cl, F and SO. Molar ratios between ions present in leachates suggest that in many cases these elements are present as simple salts such as NaCl and CaSO. In a sequential leaching experiment on ash from the 1980 eruption of Mount St. Helens, chloride salts were found to be the most readily soluble, followed by sulfate salts Fluoride compounds are in general only sparingly soluble (e.g., CaF, MgF), with the exception of fluoride salts of alkali metals and compounds such as calcium hexafluorosilicate (CaSiF). The pH of fresh ash leachates is highly variable, depending on the presence of an acidic gas condensate (primarily as a consequence of the gases SO, HCl and HF in the eruption plume) on the ash surface.


title: Volcanic ash

text: The crystalline-solid structure of the salts act more as an insulator than a conductor. However, once the salts are dissolved into a solution by a source of moisture (e.g., fog, mist, light rain, etc.), the ash may become corrosive and electrically conductive. A recent study has shown that the electrical conductivity of volcanic ash increases with (1) increasing moisture content, (2) increasing soluble salt content, and (3) increasing compaction (bulk density). The ability of volcanic ash to conduct electric current has significant implications for electric power supply systems.


title: Volcanic ash

text: Volcanic ash particles erupted during magmatic eruptions are made up of various fractions of vitric (glassy, non-crystalline), crystalline or lithic (non-magmatic) particles. Ash produced during low viscosity magmatic eruptions (e.g., Hawaiian and Strombolian basaltic eruptions) produce a range of different pyroclasts dependent on the eruptive process. For example, ash collected from Hawaiian lava fountains consists of sideromelane (light brown basaltic glass) pyroclasts which contain microlites (small quench crystals, not to be confused with the rare mineral microlite) and phenocrysts. Slightly more viscous eruptions of basalt (e.g., Strombolian) form a variety of pyroclasts from irregular sideromelane droplets to blocky tachylite (black to dark brown microcrystalline pyroclasts). In contrast, most high-silica ash (e.g. rhyolite) consists of pulverised products of pumice (vitric shards), individual phenocrysts (crystal fraction) and some lithic fragments (xenoliths).


title: Volcanic ash

text: Ash generated during phreatic eruptions primarily consists of hydrothermally altered lithic and mineral fragments, commonly in a clay matrix. Particle surfaces are often coated with aggregates of zeolite crystals or clay and only relict textures remain to identify pyroclast types.


title: Volcanic ash

text: The morphology (shape) of volcanic ash is controlled by a plethora of different eruption and kinematic processes. Eruptions of low-viscosity magmas (e.g., basalt) typically form droplet shaped particles. This droplet shape is, in part, controlled by surface tension, acceleration of the droplets after they leave the vent, and air friction. Shapes range from perfect spheres to a variety of twisted, elongate droplets with smooth, fluidal surfaces.


title: Volcanic ash

text: The morphology of ash from eruptions of high-viscosity magmas (e.g., rhyolite, dacite, and some andesites) is mostly dependent on the shape of vesicles in the rising magma before disintegration. Vesicles are formed by the expansion of magmatic gas before the magma has solidified. Ash particles can have varying degrees of vesicularity and vesicular particles can have extremely high surface area to volume ratios. Concavities, troughs, and tubes observed on grain surfaces are the result of broken vesicle walls. Vitric ash particles from high-viscosity magma eruptions are typically angular, vesicular pumiceous fragments or thin vesicle-wall fragments while lithic fragments in volcanic ash are typically equant, or angular to subrounded. Lithic morphology in ash is generally controlled by the mechanical properties of the wall rock broken up by spalling or explosive expansion of gases in the magma as it reaches the surface.


title: Volcanic ash

text: The morphology of ash particles from phreatomagmatic eruptions is controlled by stresses within the chilled magma which result in fragmentation of the glass to form small blocky or pyramidal glass ash particles. Vesicle shape and density play only a minor role in the determination of grain shape in phreatomagmatic eruptions. In this sort of eruption, the rising magma is quickly cooled on contact with ground or surface water. Stresses within the "quenched" magma cause fragmentation into five dominant pyroclast shape-types: (1) blocky and equant; (2) vesicular and irregular with smooth surfaces; (3) moss-like and convoluted; (4) spherical or drop-like; and (5) plate-like.


title: Volcanic ash

text: The density of individual particles varies with different eruptions. The density of volcanic ash varies between 700–1200 kg/m for pumice, 2350–2450 kg/m for glass shards, 2700–3300 kg/m for crystals, and 2600–3200 kg/m for lithic particles. Since coarser and denser particles are deposited close to source, fine glass and pumice shards are relatively enriched in ash fall deposits at distal locations. The high density and hardness (~5 on the Mohs Hardness Scale) together with a high degree of angularity, make some types of volcanic ash (particularly those with a high silica content) very abrasive.


title: Volcanic ash

text: Volcanic ash consists of particles (pyroclasts) with diameters <2 mm (particles >2 mm are classified as lapilli), and can be as fine as 1 μm. The overall grain size distribution of ash can vary greatly with different magma compositions. Few attempts have been made to correlate the grain size characteristics of a deposit with those of the event which produced it, though some predictions can be made. Rhyolitic magmas generally produce finer grained material compared to basaltic magmas, due to the higher viscosity and therefore explosivity. The proportions of fine ash are higher for silicic explosive eruptions, probably because vesicle size in the pre-eruptive magma is smaller than those in mafic magmas. There is good evidence that pyroclastic flows produce high proportions of fine ash by communition and it is likely that this process also occurs inside volcanic conduits and would be most efficient when the magma fragmentation surface is well below the summit crater.


title: Volcanic ash

text: Ash particles are incorporated into eruption columns as they are ejected from the vent at high velocity. The initial momentum from the eruption propels the column upwards. As air is drawn into the column, the bulk density decreases and it starts to rise buoyantly into the atmosphere. At a point where the bulk density of the column is the same as the surrounding atmosphere, the column will cease rising and start moving laterally. Lateral dispersion is controlled by prevailing winds and the ash may be deposited hundreds to thousands of kilometres from the volcano, depending on eruption column height, particle size of the ash and climatic conditions (especially wind direction and strength and humidity).


title: Volcanic ash

text: Ash fallout occurs immediately after the eruption and is controlled by particle density. Initially, coarse particles fall out close to source. This is followed by fallout of accretionary lapilli, which is the result of particle agglomeration within the column. Ash fallout is less concentrated during the final stages as the column moves downwind. This results in an ash fall deposit which generally decreases in thickness and grain size exponentially with increasing distance from the volcano. Fine ash particles may remain in the atmosphere for days to weeks and be dispersed by high-altitude winds. These particles can impact on the aviation industry (refer to impacts section) and, combined with gas particles, can affect global climate.


title: Volcanic ash

text: Volcanic ash plumes can form above pyroclastic density currents, these are called co-ignimbrite plumes. As pyroclastic density currents travel away from the volcano, smaller particles are removed from the flow by elutriation and form a less dense zone overlying the main flow. This zone then entrains the surrounding air and a buoyant co-ignimbrite plume is formed. These plumes tend to have higher concentrations of fine ash particles compared to magmatic eruption plumes due to the abrasion within the pyroclastic density current.


title: Volcanic ash

text: Population growth has caused the progressive encroachment of urban development into higher risk areas, closer to volcanic centres, increasing the human exposure to volcanic ash fall events.


title: Volcanic ash

text: Direct health effects of volcanic ash on humans are usually short-term and mild for persons in normal health, though prolonged exposure potentially poses some risk of silicosis in unprotected workers. Of greater concern is the impact of volcanic ash on the infrastructure critical to supporting modern societies, particularly in urban areas, where high population densities create high demand for services. Several recent eruptions have illustrated the vulnerability of urban areas that received only a few millimetres or centimetres of volcanic ash. This has been sufficient to cause disruption of transportation, electricity, water, sewage and storm water systems. Costs have been incurred from business disruption, replacement of damaged parts and insured losses. Ash fall impacts on critical infrastructure can also cause multiple knock-on effects, which may disrupt many different sectors and services.


title: Volcanic ash

text: Volcanic ash fall is physically, socially, and economically disruptive. Volcanic ash can affect both proximal areas and areas many hundreds of kilometres from the source, and causes disruptions and losses in a wide variety of different infrastructure sectors. Impacts are dependent on: ash fall thickness; the grain size and chemistry of the ash; whether the ash is wet or dry; the duration of the ash fall; and any preparedness, management and prevention (mitigation) measures employed to reduce effects from the ash fall. Different sectors of infrastructure and society are affected in different ways and are vulnerable to a range of impacts or consequences. These are discussed in the following sections.


title: Volcanic ash

text: Ash particles of less than 10 µm diameter suspended in the air are known to be inhalable, and people exposed to ash falls have experienced respiratory discomfort, breathing difficulty, eye and skin irritation, and nose and throat symptoms. Most of these effects are short-term and are not considered to pose a significant health risk to those without pre-existing respiratory conditions. The health effects of volcanic ash depend on the grain size, mineralogical composition and chemical coatings on the surface of the ash particles. Additional factors related to potential respiratory symptoms are the frequency and duration of exposure, the concentration of ash in the air and the respirable ash fraction; the proportion of ash with less than 10 µm diameter, known as PM. The social context may also be important.


title: Volcanic ash

text: Chronic health effects from volcanic ash fall are possible, as exposure to free crystalline silica is known to cause silicosis. Minerals associated with this include quartz, cristobalite and tridymite, which may all be present in volcanic ash. These minerals are described as ‘free’ silica as the SiO is not attached to another element to create a new mineral. However, magmas containing less than 58% SiO are thought to be unlikely to contain crystalline silica.


title: Volcanic ash

text: The exposure levels to free crystalline silica in the ash are commonly used to characterise the risk of silicosis in occupational studies (for people who work in mining, construction and other industries,) because it is classified as a human carcinogen by the International Agency for Research on Cancer. Guideline values have been created for exposure, but with unclear rationale; UK guidelines for particulates in air (PM10) are 50 µg/m and USA guidelines for exposure to crystalline silica are 50 µg/m. It is thought that the guidelines on exposure levels could be exceeded for short periods of time without significant health effects on the general population.


title: Volcanic ash

text: There have been no documented cases of silicosis developed from exposure to volcanic ash. However, long-term studies necessary to evaluate these effects are lacking.


title: Volcanic ash

text: For surface water sources such as lakes and reservoirs, the volume available for dilution of ionic species leached from ash is generally large. The most abundant components of ash leachates (Ca, Na, Mg, K, Cl, F and SO) occur naturally at significant concentrations in most surface waters and therefore are not affected greatly by inputs from volcanic ashfall, and are also of low concern in drinking water, with the exception of fluorine. The elements iron, manganese and aluminium are commonly enriched over background levels by volcanic ashfall. These elements may impart a metallic taste to water, and may produce red, brown or black staining of whiteware, but are not considered a health risk. Volcanic ashfalls are not known to have caused problems in water supplies for toxic trace elements such as mercury (Hg) and lead (Pb) which occur at very low levels in ash leachates.


title: Volcanic ash

text: Ingesting ash may be harmful to livestock, causing abrasion of the teeth, and in cases of high fluorine content, fluorine poisoning (toxic at levels of >100 µg/g) for grazing animals. It is known from the 1783 eruption of Laki in Iceland that fluorine poisoning occurred in humans and livestock as a result of the chemistry of the ash and gas, which contained high levels of hydrogen fluoride. Following the 1995/96 Mount Ruapehu eruptions in New Zealand, two thousand ewes and lambs died after being affected by fluorosis while grazing on land with only 1–3 mm of ash fall. Symptoms of fluorosis among cattle exposed to ash include brown-yellow to green-black mottles in the teeth, and hypersensibility to pressure in the legs and back. Ash ingestion may also cause gastrointestinal blockages. Sheep that ingested ash from the 1991 Mount Hudson volcanic eruption in Chile, suffered from diarrhoea and weakness.


title: Volcanic ash

text: Ash accumulating in the back wool of sheep may add significant weight, leading to fatigue and sheep that can not stand up. Rainfall may result in a significant burden as it adds weight to ash. Pieces of wool may fall away and any remaining wool on sheep may be worthless as poor nutrition associated with volcanic eruptions impacts the quality of the fibre. As the usual pastures and plants become covered in volcanic ash during eruption some livestock may resort to eat whatever is available including toxic plants. There are reports of goats and sheep in Chile and Argentina having natural abortions in connection to volcanic eruptions.


title: Volcanic ash

text: Volcanic ash can disrupt electric power supply systems at all levels of power generation, transformation, transmission, and distribution. There are four main impacts arising from ash-contamination of apparatus used in the power delivery process:


title: Volcanic ash

text: Groundwater-fed systems are resilient to impacts from ashfall, although airborne ash can interfere with the operation of well-head pumps. Electricity outages caused by ashfall can also disrupt electrically powered pumps if there is no backup generation.


title: Volcanic ash

text: The physical impacts of ashfall can affect the operation of water treatment plants. Ash can block intake structures, cause severe abrasion damage to pump impellers and overload pump motors. Ash can enter filtration systems such as open sand filters both by direct fallout and via intake waters. In most cases, increased maintenance will be required to manage the effects of an ashfall, but there will not be service interruptions.


title: Volcanic ash

text: The final step of drinking water treatment is disinfection to ensure that final drinking water is free from infectious microorganisms. As suspended particles (turbidity) can provide a growth substrate for microorganisms and can protect them from disinfection treatment, it is extremely important that the water treatment process achieves a good level of removal of suspended particles. Chlorination may have to be increased to ensure adequate disinfection.


title: Volcanic ash

text: Many households, and some small communities, rely on rainwater for their drinking water supplies. Roof-fed systems are highly vulnerable to contamination by ashfall, as they have a large surface area relative to the storage tank volume. In these cases, leaching of chemical contaminants from the ashfall can become a health risk and drinking of water is not recommended. Prior to an ashfall, downpipes should be disconnected so that water in the tank is protected. A further problem is that the surface coating of fresh volcanic ash can be acidic. Unlike most surface waters, rainwater generally has a very low alkalinity (acid-neutralising capacity) and thus ashfall may acidify tank waters. This may lead to problems with plumbosolvency, whereby the water is more aggressive towards materials that it comes into contact with. This can be a particular problem if there are lead-head nails or lead flashing used on the roof, and for copper pipes and other metallic plumbing fittings.


title: Volcanic ash

text: During ashfall events, large demands are commonly placed on water resources for cleanup and shortages can result. Shortages compromise key services such as firefighting and can lead to a lack of water for hygiene, sanitation and drinking. Municipal authorities need to monitor and manage this water demand carefully, and may need to advise the public to utilise cleanup methods that do not use water (e.g., cleaning with brooms rather than hoses).


title: Volcanic ash

text: Wastewater networks may sustain damage similar to water supply networks. It is very difficult to exclude ash from the sewerage system. Systems with combined storm water/sewer lines are most at risk. Ash will enter sewer lines where there is inflow/infiltration by stormwater through illegal connections (e.g., from roof downpipes), cross connections, around manhole covers or through holes and cracks in sewer pipes.


title: Volcanic ash

text: Ash-laden sewage entering a treatment plant is likely to cause failure of mechanical prescreening equipment such as step screens or rotating screens. Ash that penetrates further into the system will settle and reduce the capacity of biological reactors as well as increasing the volume of sludge and changing its composition.


title: Volcanic ash

text: The principal damage sustained by aircraft flying into a volcanic ash cloud is abrasion to forward-facing surfaces, such as the windshield and leading edges of the wings, and accumulation of ash into surface openings, including engines. Abrasion of windshields and landing lights will reduce visibility forcing pilots to rely on their instruments. However, some instruments may provide incorrect readings as sensors (e.g., pitot tubes) can become blocked with ash. Ingestion of ash into engines causes abrasion damage to compressor fan blades. The ash erodes sharp blades in the compressor, reducing its efficiency. The ash melts in the combustion chamber to form molten glass. The ash then solidifies on turbine blades, blocking air flow and causing the engine to stall.


title: Volcanic ash

text: The composition of most ash is such that its melting temperature is within the operating temperature (>1000 °C) of modern large jet engines. The degree of impact depends upon the concentration of ash in the plume, the length of time the aircraft spends within the plume and the actions taken by the pilots. Critically, melting of ash, particularly volcanic glass, can result in accumulation of resolidified ash on turbine nozzle guide vanes, resulting in compressor stall and complete loss of engine thrust. The standard procedure of the engine control system when it detects a possible stall is to increase power which would exacerbate the problem. It is recommended that pilots reduce engine power and quickly exit the cloud by performing a descending 180° turn. Volcanic gases, which are present within ash clouds, can also cause damage to engines and acrylic windshields, and can persist in the stratosphere as an almost invisible aerosol for prolonged periods of time.


title: Volcanic ash

text: There are many instances of damage to jet aircraft as a result of an ash encounter. On 24 June 1982, a British Airways Boeing 747-236B (Flight 9) flew through the ash cloud from the eruption of Mount Galunggung, Indonesia resulting in the failure of all four engines. The plane descended 24,000 feet (7,300 m) in 16 minutes before the engines restarted, allowing the aircraft to make an emergency landing. On 15 December 1989, a KLM Boeing 747-400 (Flight 867) also lost power to all four engines after flying into an ash cloud from Mount Redoubt, Alaska. After dropping 14,700 feet (4,500 m) in four minutes, the engines were started just 1–2 minutes before impact. Total damage was US$80 million and it took 3 months' work to repair the plane. In the 1990s, a further US$100 million of damage was sustained by commercial aircraft (some in the air, others on the ground) as a consequence of the 1991 eruption of Mount Pinatubo in the Philippines.


title: Volcanic ash

text: In April 2010, airspace all over Europe was affected, with many flights cancelled-which was unprecedented-due to the presence of volcanic ash in the upper atmosphere from the eruption of the Icelandic volcano Eyjafjallajökull. On 15 April 2010, the Finnish Air Force halted training flights when damage was found from volcanic dust ingestion by the engines of one of its Boeing F-18 Hornet fighters. On 22 April 2010, UK RAF Typhoon training flights were also temporarily suspended after deposits of volcanic ash were found in a jet's engines. In June 2011, there were similar closures of airspace in Chile, Argentina, Brazil, Australia and New Zealand, following the eruption of Puyehue-Cordón Caulle, Chile.


title: Volcanic ash

text: Volcanic ash clouds are very difficult to detect from aircraft as no onboard cockpit instruments exist to detect them. However, a new system called Airborne Volcanic Object Infrared Detector (AVOID) has recently been developed by Dr Fred Prata while working at CSIRO Australia and the Norwegian Institute for Air Research, which will allow pilots to detect ash plumes up to 60 km (37 mi) ahead and fly safely around them. The system uses two fast-sampling infrared cameras, mounted on a forward-facing surface, that are tuned to detect volcanic ash. This system can detect ash concentrations of <1 mg/m to > 50 mg/m, giving pilots approximately 7–10 minutes warning. The camera was tested by the easyJet airline company, AIRBUS and Nicarnica Aviation (co-founded by Dr Fred Prata). The results showed the system could work to distances of ~60 km and up to 10,000 ft but not any higher without some significant modifications.


title: Volcanic ash

text: In addition, ground and satellite based imagery, radar, and lidar can be used to detect ash clouds. This information is passed between meteorological agencies, volcanic observatories and airline companies through Volcanic Ash Advisory Centers (VAAC). There is one VAAC for each of the nine regions of the world. VAACs can issue advisories describing the current and future extent of the ash cloud.


title: Volcanic ash

text: Volcanic ash not only affects in-flight operations but can affect ground-based airport operations as well. Small accumulations of ash can reduce visibility, create slippery runways and taxiways, infiltrate communication and electrical systems, interrupt ground services, damage buildings and parked aircraft. Ash accumulation of more than a few millimeters requires removal before airports can resume full operations. Ash does not disappear (unlike snowfalls) and must be disposed of in a manner that prevents it from being remobilised by wind and aircraft.


title: Volcanic ash

text: Ash may disrupt transportation systems over large areas for hours to days, including roads and vehicles, railways and ports and shipping. Falling ash will reduce the visibility which can make driving difficult and dangerous. In addition, fast travelling cars will stir up ash, creating billowing clouds which perpetuate ongoing visibility hazards. Ash accumulations will decrease traction, especially when wet, and cover road markings. Fine-grained ash can infiltrate openings in cars and abrade most surfaces, especially between moving parts. Air and oil filters will become blocked requiring frequent replacement. Rail transport is less vulnerable, with disruptions mainly caused by reduction in visibility.


title: Volcanic ash

text: Marine transport can also be impacted by volcanic ash. Ash fall will block air and oil filters and abrade any moving parts if ingested into engines. Navigation will be impacted by a reduction in visibility during ash fall. Vesiculated ash (pumice and scoria) will float on the water surface in ‘pumice rafts’ which can clog water intakes quickly, leading to over heating of machinery.


title: Volcanic ash

text: Telecommunication and broadcast networks can be affected by volcanic ash in the following ways: attenuation and reduction of signal strength; damage to equipment; and overloading of network through user demand. Signal attenuation due to volcanic ash is not well documented; however, there have been reports of disrupted communications following the 1969 Surtsey eruption and 1991 Mount Pinatubo eruption. Research by the New Zealand-based Auckland Engineering Lifelines Group determined theoretically that impacts on telecommunications signals from ash would be limited to low frequency services such as satellite communication. Signal interference may also be caused by lightning, as this is frequently generated within volcanic eruption plumes.


title: Volcanic ash

text: Telecommunication equipment may become damaged due to direct ash fall. Most modern equipment requires constant cooling from air conditioning units. These are susceptible to blockage by ash which reduces their cooling efficiency. Heavy ash falls may cause telecommunication lines, masts, cables, aerials, antennae dishes and towers to collapse due to ash loading. Moist ash may also cause accelerated corrosion of metal components.


title: Volcanic ash

text: Reports from recent eruptions suggest that the largest disruption to communication networks is overloading due to high user demand. This is common of many natural disasters.


title: Volcanic ash

text: Computers may be impacted by volcanic ash, with their functionality and usability decreasing during ashfall, but it is unlikely they will completely fail. The most vulnerable components are the mechanical components, such as cooling fans, cd drives, keyboard, mice and touch pads. These components can become jammed with fine grained ash causing them to cease working; however, most can be restored to working order by cleaning with compressed air. Moist ash may cause electrical short circuits within desktop computers; however, will not affect laptop computers.


title: Volcanic ash

text: Damage to buildings and structures can range from complete or partial roof collapse to less catastrophic damage of exterior and internal materials. Impacts depend on the thickness of ash, whether it is wet or dry, the roof and building design and how much ash gets inside a building. The specific weight of ash can vary significantly and rain can increase this by 50–100%. Problems associated with ash loading are similar to that of snow; however, ash is more severe as 1) the load from ash is generally much greater, 2) ash does not melt and 3) ash can clog and damage gutters, especially after rain fall. Impacts for ash loading depend on building design and construction, including roof slope, construction materials, roof span and support system, and age and maintenance of the building. Generally flat roofs are more susceptible to damage and collapse than steeply pitched roofs. Roofs made of smooth materials (sheet metal or glass) are more likely to shed ash than roofs made with rough materials (thatch, asphalt or wood shingles). Roof collapse can lead to widespread injuries and deaths and property damage. For example, the collapse of roofs from ash during the 15 June 1991 Mount Pinatubo eruption killed about 300 people.


title: Volcanic ash

text: Volcanic ash can have a detrimental impact on the environment which can be difficult to predict due to the large variety of environmental conditions that exist within the ash fall zone. Natural waterways can be impacted in the same way as urban water supply networks. Ash will increase water turbidity which can reduce the amount of light reaching lower depths, which can inhibit growth of submerged aquatic plants and consequently affect species which are dependent on them such as fish and shellfish. High turbidity can also affect the ability of fish gills to absorb dissolved oxygen. Acidification will also occur, which will reduce the pH of the water and impact the fauna and flora living in the environment. Fluoride contamination will occur if the ash contains high concentrations of fluoride.


title: Volcanic ash

text: Ash accumulation will also affect pasture, plants and trees which are part of the horticulture and agriculture industries. Thin ash falls (<20 mm) may put livestock off eating, and can inhibit transpiration and photosynthesis and alter growth. There may be an increase in pasture production due to a mulching effect and slight fertilizing effect, such as occurred following the 1980 Mount St. Helens and 1995/96 Mt Ruapehu eruptions. Heavier falls will completely bury pastures and soil leading to death of pasture and sterilization of the soil due to oxygen deprivation. Plant survival is dependent on ash thickness, ash chemistry, compaction of ash, amount of rainfall, duration of burial and the length of plant stalks at the time of ash fall.


title: Volcanic ash

text: Young forests (trees <2 years old) are most at risk from ash falls and are likely to be destroyed by ash deposits >100 mm. Ash fall is unlikely to kill mature trees, but ash loading may break large branches during heavy ash falls (>500 mm). Defoliation of trees may also occur, especially if there is a coarse ash component within the ash fall.


title: Volcanic ash

text: Land rehabilitation after ash fall may be possible depending on the ash deposit thickness. Rehabilitation treatment may include: direct seeding of deposit; mixing of deposit with buried soil; scraping of ash deposit from land surface; and application of new topsoil over the ash deposit.


title: Volcanic ash

text: Critical infrastructure and infrastructure services are vital to the functionality of modern society, to provide: medical care, policing, emergency services, and lifelines such as water, wastewater, and power and transportation links. Often critical facilities themselves are dependent on such lifelines for operability, which makes them vulnerable to both direct impacts from a hazard event and indirect effects from lifeline disruption.


title: Volcanic ash

text: The impacts on lifelines may also be inter-dependent. The vulnerability of each lifeline may depend on: the type of hazard, the spatial density of its critical linkages, the dependency on critical linkages, susceptibility to damage and speed of service restoration, state of repair or age, and institutional characteristics or ownership.


title: Volcanic ash

text: The 2010 eruption of Eyjafjallajokull in Iceland highlighted the impacts of volcanic ash fall in modern society and our dependence on the functionality of infrastructure services. During this event, the airline industry suffered business interruption losses of €1.5–2.5 billion from the closure of European airspace for six days in April 2010 and subsequent closures into May 2010. Ash fall from this event is also known to have caused local crop losses in agricultural industries, losses in the tourism industry, destruction of roads and bridges in Iceland (in combination with glacial melt water), and costs associated with emergency response and clean-up. However, across Europe there were further losses associated with travel disruption, the insurance industry, the postal service, and imports and exports across Europe and worldwide. These consequences demonstrate the interdependency and diversity of impacts from a single event.


title: Volcanic ash

text: Preparedness for ashfalls should involve sealing buildings, protecting infrastructure and homes, and storing sufficient supplies of food and water to last until the ash fall is over and clean-up can begin. Dust masks can be worn to reduce inhalation of ash and mitigate against any respiratory health affects. Goggles can be worn to protect against eye irritation.


title: Volcanic ash

text: At home, staying informed about volcanic activity, and having contingency plans in place for alternative shelter locations, constitutes good preparedness for an ash fall event. This can prevent some impacts associated with ash fall, reduce the effects, and increase the human capacity to cope with such events. A few items such as a flashlight, plastic sheeting to protect electronic equipment from ash ingress, and battery operated radios, are extremely useful during ash fall events.


title: Volcanic ash

text: Communication plans should be made beforehand to inform of mitigation actions being undertaken. Spare parts and back-up systems should be in place prior to ash fall events to reduce service disruption and return functionality as quickly as possible. Good preparedness also includes the identification of ash disposal sites, before ash fall occurs, to avoid further movement of ash and to aid clean-up.


title: Volcanic ash

text: Some effective techniques for the management of ash have been developed including cleaning methods and cleaning apparatus, and actions to mitigate or limit damage. The latter include covering of openings such as: air and water intakes, aircraft engines and windows during ash fall events. Roads may be closed to allow clean-up of ash falls, or speed restrictions may be put in place, in order to prevent motorists from developing motor problems and becoming stranded following an ash fall. To prevent further effects on underground water systems or waste water networks, drains and culverts should be unblocked and ash prevented from entering the system. Ash can be moistened (but not saturated) by sprinkling with water, to prevent remobilisation of ash and to aid clean-up. Prioritisation of clean-up operations for critical facilities and coordination of clean-up efforts also constitute good management practice.


title: Volcanic ash

text: Volcanic ash's primary use is that of a soil enricher. Once the minerals in ash are washed into the soil by rain or other natural processes, it mixes with the soil to create an andisol layer. This layer is highly rich in nutrients and is very good for agricultural use; the presence of lush forests on volcanic islands is often as a result of trees growing and flourishing in the phosphorus and nitrogen-rich andisol. Volcanic ash can also be used as a replacement for sand.


title: Medal of Honor (1999 video game)

text: Medal of Honor is a 1999 first-person shooter video game, developed by DreamWorks Interactive and published by Electronic Arts for PlayStation. It is the first installment in the "Medal of Honor" video game series. The gameplay features the combined arms warfare of World War II, as the player completes various missions for the Office of Strategic Services.


title: Medal of Honor (1999 video game)

text: The story was created by film director and producer Steven Spielberg, combining his deep interest in World War II with the inspiration of watching his son playing the game "GoldenEye 007." While in development, the game experienced controversy due to the 1999 Columbine High School massacre, and was criticized by the Congressional Medal of Honor Society for turning a serious topic into a video game. Game producer Peter Hirschmann convinced Medal of Honor Society president Paul Bucha that the project was made with serious and honorable intentions, saving the project from cancellation, and even earning Bucha's endorsement.


title: Medal of Honor (1999 video game)

text: The game was released to universal acclaim, and has been credited with popularizing the trend of World War II shooters. The game was followed by "," leading to a widely successful series.


title: Medal of Honor (1999 video game)

text: The game takes place near the end of World War II (mid-1944 to mid-1945). The goal of the game is to complete various Office of Strategic Services (OSS) missions, such as rescuing an American pilot, going undercover to board and destroy a U-boat, recovering stolen art work, and sabotaging the Nazi war effort.


title: Medal of Honor (1999 video game)

text: The game includes a split-screen deathmatch mode, pitting two players against each other in various maps. Players can unlock several secret characters after completing the game or through cheat codes, including notable historical figures such as Filipino patriot José Rizal and playwright William Shakespeare, as well as outlandish characters such as a German Shepherd and a dinosaur.


title: Medal of Honor (1999 video game)

text: Filmmaker Steven Spielberg founded DreamWorks Interactive in 1995, as part of a trend of Hollywood studios set up their own interactive divisions, such as Disney Interactive. Spielberg had recognized the entertainment potential of video games earlier than other Hollywood veterans, as he already had experience consulting on projects for both Atari and LucasArts.


title: Medal of Honor (1999 video game)

text: "Medal of Honor" was a passion project that emerged during Spielberg's work on the film "Saving Private Ryan," with development of the game beginning on November 11, 1997. Spielberg held a meeting with his staff, outlining his idea for a first-person shooter set during World War II. The idea originated from Spielberg's deep interest in World War II, while also watching his son Max playing the James Bond-themed game "GoldenEye 007".


title: Medal of Honor (1999 video game)

text: According to game producer Peter Hirschmann, the studio's corporate management was worried that World War II was dated, and players were more interested in "ray guns, hell-spawn and laser rifles". The studio recruited Dale Dye as the game's military advisor, who had previously advised Spielberg on "Saving Private Ryan". Dye criticized their first demo as exploitative and irresponsible, but continued with the project due to his belief that the studio had honorable intentions, improving the game's historical authenticity with nostalgic and educational segments.


title: Medal of Honor (1999 video game)

text: By March 1998, the game had reached its prototype stage with significant differences from the original version. Spielberg was determined to pioneer new experiences in interactive entertainment, such as a "show me your papers" sequence where the player brandishes fake ID papers instead of a gun. The new demo was well received by publisher Electronic Arts, but was soon mired in controversy as the 1999 Columbine High School massacre attracted more scrutiny onto video games. The team decided to remove particularly gory scenes from the game, particularly an animation where a maimed Nazi soldier appeared to dance around before collapsing. Still, the Congressional Medal of Honor Society president Paul Bucha heard about the game's development, and criticized them for using a serious and sacred symbol such as the Medal of Honor for a video game. Spielberg considered cancelling the project, but Peter Hirschmann showed Bucha a demo and convinced him of the project's seriousness, saving the project from cancellation, and earning an endorsement from the Medal of Honor society.


title: Medal of Honor (1999 video game)

text: The game was released in 1999, with Steven Spielberg credited for its story, and film composer Michael Giacchino credited with the game's full orchestral score. The studio experienced severe losses through the production of the game, and was sold to EA, ironically before the game became highly profitable. "Medal of Honor" was re-released on PlayStation Network as a PS one Classic on June 2, 2009 in North America.


title: Medal of Honor (1999 video game)

text: "Medal of Honor" received an aggregate score of 92 out of 100 on review aggregator Metacritic, indicating "universal acclaim". IGN gave the game its editor's choice award, with reviewer Doug Perry praising its gameplay, sound, level design, attention to detail. GamePro called the game "one of the year's top titles and a must-won game", praising it for featuring "some of the most tense first-person action ever delivered on the Playstation". Jeff Lundrigan of "Next Generation" called it "the best PlayStation first-person shooter in ages", while "" stated that the game was "an extraordinary game with no equal on the PlayStation".


title: Medal of Honor (1999 video game)

text: "Medal of Honor" received a "Gold" sales award from the Entertainment and Leisure Software Publishers Association (ELSPA), indicating sales of at least 200,000 copies in the United Kingdom.


title: Medal of Honor (1999 video game)

text: IGN ranked "Medal of Honor" as the 20th-best shooter game of all time, crediting it with popularizing the trend of World War II shooters, as well as creating the highly popular series. Several members of the game's team recall that the game was one of the first marriages between game and film, showing that video games could tackle a serious topic like World War II with gravitas. In the final issue of the "Official UK PlayStation Magazine", the game was chosen as the 8th-best game of all time. IGN ranked the game #21 on their list of the "Top 25 Games of All Time" for the PlayStation console.


title: Medal of Honor (1999 video game)

text: "Medal of Honor" is the first in the "Medal of Honor" series, and was followed by the direct sequel "".


title: Reflection coefficient

text: In physics and electrical engineering the reflection coefficient is a parameter that describes how much of a wave is reflected by an impedance discontinuity in the transmission medium. It is equal to the ratio of the amplitude of the reflected wave to the incident wave, with each expressed as phasors. For example, it is used in optics to calculate the amount of light that is reflected from a surface with a different index of refraction, such as a glass surface, or in an electrical transmission line to calculate how much of the electromagnetic wave is reflected by an impedance discontinuity. The reflection coefficient is closely related to the "transmission coefficient". The reflectance of a system is also sometimes called a "reflection coefficient".


title: Reflection coefficient

text: In telecommunications and transmission line theory, the reflection coefficient is the ratio of the complex amplitude of the reflected wave to that of the incident wave. The voltage and current at any point along a transmission line can always be resolved into forward and reflected traveling waves given a specified reference impedance "Z". The reference impedance used is typically the characteristic impedance of a transmission line that's involved, but one can speak of reflection coefficient without any actual transmission line being present. In terms of the forward and reflected waves determined by the voltage and current, the reflection coefficient is defined as the complex ratio of the voltage of the reflected wave (formula_1) to that of the incident wave (formula_2). This is typically represented with a formula_3 (capital gamma) and can be written as:


title: Reflection coefficient

text: It can as well be defined using the "currents" associated with the reflected and forward waves, but introducing a minus sign to account for the opposite orientations of the two currents:


title: Reflection coefficient

text: The reflection coefficient may also be established using other field or circuit pairs of quantities whose product defines power resolvable into a forward and reverse wave. For instance, with electromagnetic plane waves, one uses the ratio of the electric fields of the reflected to that of the forward wave (or magnetic fields, again with a minus sign); the ratio of each wave's electric field "E" to its magnetic field "H" is again an impedance "Z" (equal to the impedance of free space in a vacuum). Similarly in acoustics one uses the acoustic pressure and velocity respectively.


title: Reflection coefficient

text: In the accompanying figure, a signal source with internal impedance formula_6 possibly followed by a transmission line of characteristic impedance formula_6 is represented by its Thévenin equivalent, driving the load formula_8. For a real (resistive) source impedance formula_6, if we define formula_3 using the reference impedance formula_11 then the source's maximum power is delivered to a load formula_12, in which case formula_13 implying no reflected power. More generally, the squared-magnitude of the reflection coefficient formula_14 denotes the proportion of that power that is "reflected" and absorbed by the source, with the power actually delivered to the load being formula_15.


title: Reflection coefficient

text: Anywhere along an intervening (lossless) transmission line of characteristic impedance formula_16, the magnitude of the reflection coefficient formula_17 will remain the same (the powers of the forward and reflected waves stay the same) but with a different phase. In the case of a short circuited load (formula_18), one finds formula_19 at the load. This implies the reflected wave having a 180° phase shift (phase reversal) with the voltages of the two waves being opposite at that point and adding to zero (as a short circuit demands).


title: Reflection coefficient

text: The reflection coefficient is determined by the load impedance at the end of the transmission line, as well as the characteristic impedance of the line. A load impedance of formula_8 terminating a line with a characteristic impedance of formula_21 will have a reflection coefficient of


title: Reflection coefficient

text: This is the coefficient at the load. The reflection coefficient can also be measured at other points on the line. The "magnitude" of the reflection coefficient in a lossless transmission line is constant along the line (as are the powers in the forward and reflected waves). However its "phase" will be shifted by an amount dependent on the electrical distance formula_23 from the load. If the coefficient is measured at a point formula_24 meters from the load, so the electrical distance from the load is formula_25 radians, the coefficient formula_26 at that point will be


title: Reflection coefficient

text: Note that the phase of the reflection coefficient is changed by "twice" the phase length of the attached transmission line. That is to take into account not only the phase delay of the reflected wave, but the phase shift that had first been applied to the forward wave, with the reflection coefficient being the quotient of these. The reflection coefficient so measured, formula_26, corresponds to an impedance which is generally dissimilar to formula_8 present at the far side of the transmission line.


title: Reflection coefficient

text: The complex reflection coefficient (in the region formula_30, corresponding to passive loads) may be displayed graphically using a Smith chart. The Smith chart is a polar plot of formula_3, therefore the magnitude of formula_3 is given directly by the distance of a point to the center (with the edge of the Smith chart corresponding to formula_33). Its evolution along a transmission line is likewise described by a rotation of formula_34 around the chart's center. Using the scales on a Smith chart, the resulting impedance (normalized to formula_16) can directly be read. Before the advent of modern electronic computers, the Smith chart was of particular use as a sort of analog computer for this purpose.


title: Reflection coefficient

text: Along a lossless transmission line of characteristic impedance "Z", the SWR signifies the ratio of the voltage (or current) maxima to minima (or what it would be if the transmission line were long enough to produce them). The above calculation assumes that formula_3 has been calculated using "Z" as the reference impedance. Since it uses only the "magnitude" of formula_3, the SWR intentionally ignores the specific value of the load impedance "Z" responsible for it, but only the magnitude of the resulting impedance mismatch. That SWR remains the same wherever measured along a transmission line (looking towards the load) since the addition of a transmission line length to a load formula_8 only changes the phase, not magnitude of formula_3. While having a one-to-one correspondence with reflection coefficient, SWR is the most commonly used figure of merit in describing the mismatch affecting a radio antenna or antenna system. It is most often measured at the transmitter side of a transmission line, but having, as explained, the same value as would be measured at the antenna (load) itself.


title: Reflection coefficient

text: In optics and electromagnetics in general, "reflection coefficient" can refer to either the amplitude reflection coefficient described here, or the reflectance, depending on context. Typically, the reflectance is represented by a capital "R", while the amplitude reflection coefficient is represented by a lower-case "r". These related concepts are covered by Fresnel equations in classical optics.


title: Reflection coefficient

text: Acousticians use reflection coefficients to understand the effect of different materials on their acoustic environments.


title: Pogo (comic strip)

text: Pogo was a daily comic strip that was created by cartoonist Walt Kelly and syndicated to American newspapers from 1948 until 1975. Set in the Okefenokee Swamp in the Southeastern United States, "Pogo" followed the adventures of its anthropomorphic animal characters, including the title character, an opossum. The strip was written for both children and adults, with layers of social and political satire targeted to the latter. "Pogo" was distributed by the Post-Hall Syndicate. The strip earned Kelly a Reuben Award in 1951.


title: Pogo (comic strip)

text: Walter Crawford Kelly Jr. was born in Philadelphia on August 25, 1913. His family moved to Bridgeport, Connecticut, when he was only two. He went to California at age 22 to work on "Donald Duck" cartoons at Walt Disney Studios in 1935. He stayed until the animators' strike in 1941 as an animator on "The Nifty Nineties", "The Little Whirlwind", "Pinocchio, Fantasia, Dumbo" and "The Reluctant Dragon". Kelly then worked for Dell Comics, a division of Western Publishing of Racine, Wisconsin.


title: Pogo (comic strip)

text: Kelly created the characters of Pogo the possum and Albert the alligator in 1941 for issue No. 1 of Dell's "Animal Comics" in the story "Albert Takes the Cake". Both were comic foils for a young black character named Bumbazine (a corruption of bombazine, a fabric that was usually dyed black and used largely for mourning wear), who lived in the swamp. Bumbazine was retired early, since Kelly found it hard to write for a human child. He eventually phased humans out of the comics entirely, preferring to use the animal characters for their comic potential. Kelly said he used animals—nature's creatures, or "nature's screechers" as he called them—"largely because you can do more with animals. They don't hurt as easily, and it's possible to make them more believable in an exaggerated pose." Pogo, formerly a "spear carrier" according to Kelly, quickly took center stage, assuming the straight man role that Bumbazine had occupied.


title: Pogo (comic strip)

text: In his 1954 autobiography for the Hall Syndicate, Kelly said he "fooled around with the Foreign Language Unit of the Army during World War II, illustrating grunts and groans, and made friends in the newspaper and publishing business." In 1948 he was hired to draw political cartoons for the editorial page of the short-lived "New York Star"; he decided to do a daily comic strip featuring the characters from "Animal Comics". The first comic series to make the permanent transition to newspapers, "Pogo" debuted on October 4, 1948, and ran continuously until the paper folded on January 28, 1949.


title: Pogo (comic strip)

text: On May 16, 1949, "Pogo" was picked up for national distribution by the Post-Hall Syndicate. George Ward and Henry Shikuma were among Kelly's assistants on the strip. It ran continuously until (and past) Kelly's death from complications of diabetes on October 18, 1973. According to Walt Kelly's widow Selby Kelly, Walt Kelly fell ill in 1972 and was unable to continue the strip. At first, reprints, mostly with minor rewording in the word balloons, from the 1950s and 1960s were used, starting Sunday, June 4, 1972. Kelly returned for just eight Sunday pages, from October 8 to November 26, 1972, but according to Selby was unable to draw the characters as large as he customarily did. The reprints with minor rewording returned, continuing until Kelly's death. Other artists, notably Don Morgan, worked on the strip. Selby Kelly began to draw the strip with the Christmas strip from 1973 from scripts by Walt's son Stephen. The strip ended July 20, 1975. Selby Kelly said in a 1982 interview that she decided to discontinue the strip because newspapers had shrunk the size of strips to the point where people could not easily read it.


title: Pogo (comic strip)

text: Starting on January 8, 1989, the "Los Angeles Times" Syndicate revived the strip under the title "Walt Kelly's Pogo", written by Larry Doyle and drawn by Neal Sternecky. Doyle left the strip as of February 24, 1991, and Sternecky took over as both writer and artist until March 22, 1992. After Sternecky left, Kelly's son Peter and daughter Carolyn continued to produce the strip until October 2, 1993, but interest waned. The strip continued to run for a couple months with reprints of Doyle and Sternecky's work, and came to an end on November 28, 1993.


title: Pogo (comic strip)

text: "Pogo" is set in the Georgia section of the Okefenokee Swamp; Fort Mudge and Waycross are occasionally mentioned.


title: Pogo (comic strip)

text: The characters live, for the most part, in hollow trees amidst lushly rendered backdrops of North American wetlands, bayous, lagoons and backwoods. Fictitious local landmarks—such as "Miggle's General Store and Emporium" (a.k.a. "Miggle's Miracle Mart") and the "Fort Mudge Memorial Dump", etc.—are occasionally featured. The landscape is fluid and vividly detailed, with a dense variety of (often caricatured) flora and fauna. The richly textured trees and marshlands frequently change from panel to panel within the same strip. Like the Coconino County depicted in "Krazy Kat" and the Dogpatch of "Li'l Abner", the distinctive cartoon landscape of Kelly's Okefenokee Swamp became as strongly identified with the strip as any of its characters.