Technetium-99m
Technetium-99m is a metastable nuclear isomer of technetium-99 (itself an isotope of technetium), symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical radioisotope.
Technetium-99m is used as a radioactive tracer and can be detected in the body by medical equipment (gamma cameras). It is well suited to the role because it emits readily detectable 140 keV gamma rays (these 8.8 pm photons are about the same wavelength as emitted by conventional X-ray diagnostic equipment) and its half-life for gamma emission is 6.0058 hours (meaning 93.7% of it decays to 99Tc in 24 hours). The relatively "short" physical half-life of the isotope and its biological half-life of 1 day (in terms of human activity and metabolism) allows for scanning procedures which collect data rapidly but keep total patient radiation exposure low. The same characteristics make the isotope suitable only for diagnostic but never therapeutic use.
MTC
MTC may stand for:
See also
Mandarin Training Center
Coordinates: 25°1′38.46″N 121°31′42.68″E / 25.0273500°N 121.5285222°E / 25.0273500; 121.5285222
Mandarin Training Center (Chinese: 國語教學中心) is one of the world's oldest and most distinguished programs for Chinese as a second language study. It is run by National Taiwan Normal University (NTNU) in Taipei, Taiwan and located at NTNU Da'an Campus.
History
The Mandarin Training Center (MTC) was founded in 1956. It was briefly known as the Center for Chinese Language and Culture Studies from 2002-2004. The center attracts students from all parts of the world to Taiwan to study Mandarin Chinese language and literature. Students also have access to courses in Chinese calligraphy, Chinese martial arts, and traditional music and theater. Courses are offered in three-month quarterly terms throughout the year. This system enables international students to engage in intensive language study during their summer breaks and within single semesters. The MTC sponsors travel, hosts speech contests, and stages workshops and performances.
Navajo
The Navajo (Navajo: Diné or Naabeehó) are a Native American people of the Southwestern United States. They are the second largest federally recognized tribe in the United States with 300,460 enrolled tribal members as of 2015. The Navajo Nation constitutes an independent governmental body that manages the Navajo reservation in the Four Corners area, including over 27,000 square miles of land in Arizona, Utah, and New Mexico. The Navajo language is spoken throughout the region with most Navajo speaking English as well.
The states with the largest Navajo populations are Arizona (140,263) and New Mexico (108,306). Over three-quarters of the Navajo population reside in these two states.
History
Early history
Until contact with Pueblos and the Spanish, the Navajo were largely hunters and gatherers. The tribe adopted crop farming techniques from the Pueblo peoples, growing mainly corn, beans, and squash. When the Spanish arrived, the Navajo began herding sheep and goats as a main source of trade and food, with meat becoming an essential component of the Navajo diet. Sheep also became a form of currency and status symbol among the Navajo based on the overall quantity of herds a family maintained. In addition, the practice of spinning and weaving wool into blankets and clothing became common and eventually developed into a form of highly valued artistic expression.
Navajo (film)
Navajo is a 1952 documentary film directed by Norman Foster. It was nominated for two Academy Awards for Best Documentary Feature and Best Cinematography.
Cast
References
External links
Navajo (train)
The Navajo was one of the named passenger trains of the Atchison, Topeka and Santa Fe Railway. The economy train entered daily service between Chicago-Los Angeles-San Francisco as train Nos. 9 & 10 on October 1, 1915, as a replacement for the railroad's Tourist Flyer, and ran until January 14, 1940.
In Summer 1926 train 9 left Chicago at 0945 and arrived Los Angeles three days later at 0730. It ran via Topeka, St John and Pasadena and carried no diner west of Kansas City, making three meal stops a day. In November 1939 it left Chicago 0135 and arrived Los Angeles 1140, 60 hrs by the same route except via Great Bend. (For several years earlier in the 1930s the westward train shifted to the Amarillo route, then both trains ran via Amarillo for a year or two before returning to the northern line.)
The Navajo name was also carried by a Santa Fe sleeper-lounge-observation cars built by the Budd Company in 1937 for the Super Chief. The car is on display at the Colorado Railroad Museum.
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