Input: Railway electrification system
Newly electrified lines often show a "sparks effect", whereby electrification in passenger rail systems leads to significant jumps in patronage / revenue. The reasons may include electric trains being seen as more modern and attractive to ride, faster and smoother service, and the fact that electrification often goes hand in hand with a general infrastructure and rolling stock overhaul / replacement, which leads to better service quality (in a way that theoretically could also be achieved by doing similar upgrades yet without electrification). Whatever the causes of the sparks effect, it is well established for numerous routes that have electrified over decades.

How can better service quality be achieved?
Output: rolling stock overhaul / replacement

Input: Capacitor
The simplest model capacitor consists of two thin parallel conductive plates separated by a dielectric with permittivity ε . This model may also be used to make qualitative predictions for other device geometries. The plates are considered to extend uniformly over an area A and a charge density ±ρ = ±Q/A exists on their surface. Assuming that the length and width of the plates are much greater than their separation d, the electric field near the centre of the device will be uniform with the magnitude E = ρ/ε. The voltage is defined as the line integral of the electric field between the plates

In an ideal model of a capacitor, what must be assumed about the size of the plates?
Output: much greater than their separation d

Input: Copper
Chromobacterium violaceum and Pseudomonas fluorescens can both mobilize solid copper, as a cyanide compound. The ericoid mycorrhizal fungi associated with Calluna, Erica and Vaccinium can grow in copper metalliferous soils. The ectomycorrhizal fungus Suillus luteus protects young pine trees from copper toxicity. A sample of the fungus Aspergillus niger was found growing from gold mining solution; and was found to contain cyano metal complexes; such as gold, silver, copper iron and zinc. The fungus also plays a role in the solubilization of heavy metal sulfides.

What fungi can grow in copper metalliferous soils?
Output: ericoid mycorrhizal fungi

Input: Mandolin
The mandolin has been used occasionally in rock music, first appearing in the psychedelic era of the late 1960s. Levon Helm of The Band occasionally moved from his drum kit to play mandolin, most notably on Rag Mama Rag, Rockin' Chair, and Evangeline. Ian Anderson of Jethro Tull played mandolin on Fat Man, from their second album, Stand Up, and also occasionally on later releases. Rod Stewart's 1971 No. 1 hit Maggie May features a significant mandolin riff. David Grisman played mandolin on two Grateful Dead songs on the American Beauty album, Friend of the Devil and Ripple, which became instant favorites among amateur pickers at jam sessions and campground gatherings. John Paul Jones and Jimmy Page both played mandolin on Led Zeppelin songs. The popular alt rock group Imagine Dragons feature the mandolin on a few of their songs, most prominently being It's Time. Dash Crofts of the soft rock duo Seals and Crofts extensively used mandolin in their repertoire during the 1970s. Styx released the song Boat on the River in 1980, which featured Tommy Shaw on vocals and mandolin. The song didn't chart in the United States but was popular in much of Europe and the Philippines.

What Rod Stewart song in 1971 featured the mandolin?
Output:
Maggie May