Context and question: In the United States, 25 Hz, a once-common industrial power frequency is used on Amtrak's 25 Hz traction power system at 12 kV on the Northeast Corridor between Washington, D.C. and New York City and on the Keystone Corridor between Harrisburg, Pennsylvania and Philadelphia. SEPTA's 25 Hz traction power system uses the same 12 kV voltage on the catenary in Northeast Philadelphia. This allows for the trains to operate on both the Amtrak and SEPTA power systems. Apart from having an identical catenary voltage, the power distribution systems of Amtrak and SEPTA are very different. The Amtrak power distribution system has a 138 kV transmission network that provides power to substations which then transform the voltage to 12 kV to feed the catenary system. The SEPTA power distribution system uses a 2:1 ratio autotransformer system, with the catenary fed at 12 kV and a return feeder wire fed at 24 kV. The New York, New Haven and Hartford Railroad used an 11 kV system between New York City and New Haven, Connecticut which was converted to 12.5 kV 60 Hz in 1987.
What uses a catenary fed at 24 kV?
Answer: unanswerable
Context and question: The PhilippineAmerican War (18991902) was an armed conflict between a group of Filipino revolutionaries and the American forces following the ceding of the Philippines to the United States after the defeat of Spanish forces in the Battle of Manila. The Army sent in 100,000 soldiers (mostly from the National Guard) under General Elwell Otis. Defeated in the field and losing its capital in March 1899, the poorly armed and poorly led rebels broke into armed bands. The insurgency collapsed in March 1901 when the leader Emilio Aguinaldo was captured by General Frederick Funston and his Macabebe allies. Casualties included 1,037 Americans killed in action and 3,340 who died from disease; 20,000 rebels were killed.
When was the Philippine-American War fought?
Answer: 18991902
Context and question: Another effective way to decrease the transmission rate of infectious diseases is to recognize the effects of small-world networks. In epidemics, there are often extensive interactions within hubs or groups of infected individuals and other interactions within discrete hubs of susceptible individuals. Despite the low interaction between discrete hubs, the disease can jump to and spread in a susceptible hub via a single or few interactions with an infected hub. Thus, infection rates in small-world networks can be reduced somewhat if interactions between individuals within infected hubs are eliminated (Figure 1). However, infection rates can be drastically reduced if the main focus is on the prevention of transmission jumps between hubs. The use of needle exchange programs in areas with a high density of drug users with HIV is an example of the successful implementation of this treatment method. Another example is the use of ring culling or vaccination of potentially susceptible livestock in adjacent farms to prevent the spread of the foot-and-mouth virus in 2001.
What is an example of a successful implementation of increasing transmission jumps?
Answer:
unanswerable