Input: Antenna (radio)
As an electro-magnetic wave travels through the different parts of the antenna system (radio, feed line, antenna, free space) it may encounter differences in impedance (E/H, V/I, etc.). At each interface, depending on the impedance match, some fraction of the wave's energy will reflect back to the source, forming a standing wave in the feed line. The ratio of maximum power to minimum power in the wave can be measured and is called the standing wave ratio (SWR). A SWR of 1:1 is ideal. A SWR of 1.5:1 is considered to be marginally acceptable in low power applications where power loss is more critical, although an SWR as high as 6:1 may still be usable with the right equipment. Minimizing impedance differences at each interface (impedance matching) will reduce SWR and maximize power transfer through each part of the antenna system.

What is created by a portion of a radio waves energy reversing?
Output: standing wave

Input: European Central Bank
However, if the debt rescheduling causes losses on loans held by European banks, it weakens the private banking system, which then puts pressure on the central bank to come to the aid of those banks. Private-sector bond holders are an integral part of the public and private banking system. Another possible response is for wealthy member countries to guarantee or purchase the debt of countries that have defaulted or are likely to default. This alternative requires that the tax revenues and credit of the wealthy member countries be used to refinance the previous borrowing of the weaker member countries, and is politically controversial.

What happens when the private banking system is weakened?
Output: pressure on the central bank to come to the aid of those banks

Input: Late Middle Ages
The Bulgarian Empire was in decline by the 14th century, and the ascendancy of Serbia was marked by the Serbian victory over the Bulgarians in the Battle of Velbazhd in 1330. By 1346, the Serbian king Stefan Dušan had been proclaimed emperor. Yet Serbian dominance was short-lived; the Serbian army led by the Lazar Hrebljevanovic was defeated by the Ottomans at the Battle of Kosovo in 1389, where most of the Serbian nobility was killed and the south of the country came under Ottoman occupation, as much of southern Bulgaria had become Ottoman territory in 1371. Northern remnants of Bulgaria were finally conquered by 1396, Serbia fell in 1459, Bosnia in 1463, and Albania was finally subordinated in 1479 only a few years after the death of Skanderbeg. Belgrade, an Hungarian domain at the time, was the last large Balkan city to fall under Ottoman rule, in 1521. By the end of the medieval period, the entire Balkan peninsula was annexed by, or became vassal to, the Ottomans.

What event resulted in the triumph of Serbia over Bulgaria in 1330?
Output: Battle of Velbazhd

Input: Bacteria
Bacterial infections may be treated with antibiotics, which are classified as bacteriocidal if they kill bacteria, or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. An example of how antibiotics produce selective toxicity are chloramphenicol and puromycin, which inhibit the bacterial ribosome, but not the structurally different eukaryotic ribosome. Antibiotics are used both in treating human disease and in intensive farming to promote animal growth, where they may be contributing to the rapid development of antibiotic resistance in bacterial populations. Infections can be prevented by antiseptic measures such as sterilizing the skin prior to piercing it with the needle of a syringe, and by proper care of indwelling catheters. Surgical and dental instruments are also sterilized to prevent contamination by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection.

What kind of antibiotics are used for prevention of bacterial growth
Output:
bacteriostatic