Context: Death from laughter is a rare form of death, usually resulting from cardiac arrest or asphyxiation, caused by a fit of laughter. Instances of death by laughter have been recorded from the times of ancient Greece to the modern day.
 Question: can you have a heart attack from laughing Context: There are three types of viral infections that can be considered under the topic of viral transformation. These are cytocidal, persistent, and transforming infections. Cytocidal infections can cause fusion of adjacent cells, disruption of transport pathways including ions and other cell signals, disruption of DNA, RNA and protein synthesis, and nearly always leads to cell death. Persistent infections involve viral material that lays dormant within a cell until activated by some stimulus. This type of infection usually causes few obvious changes within the cell but can lead to long chronic diseases. Transforming infections are also referred to as malignant transformation. This infection causes a host cell to become malignant and can be either cytocidal (usually in the case of RNA viruses) or persistent (usually in the case of DNA viruses). Cells with transforming infections undergo immortalization and inherit the genetic material to produce tumors. Since the term cytocidal, or cytolytic, refers to cell death, these three infections are not mutually exclusive. Many transforming infections by DNA tumor viruses are also cytocidal.
 Question: can some viruses change normal cells to tumor cells Context: An invoice, bill or tab is a commercial document issued by a seller to a buyer, relating to a sale transaction and indicating the products, quantities, and agreed prices for products or services the seller had provided the buyer.
 Question: is a bill the same as an invoice Context: Total internal reflection is the phenomenon which occurs when a propagated wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary and the incident angle is greater than the critical angle, the wave cannot pass through and is entirely reflected. The critical angle is the angle of incidence above which the total internal reflection occurs. This is particularly common as an optical phenomenon, where light waves are involved, but it occurs with many types of waves, such as electromagnetic waves in general or sound waves. When a wave reaches a boundary between different materials with different refractive indices, the wave will in general be partially refracted at the boundary surface, and partially reflected. However, if the angle of incidence is greater (i.e. the direction of propagation is closer to being parallel to the boundary) than the critical angle -- the angle of incidence at which light is refracted such that it travels along the boundary -- then the wave will not cross the boundary, but will instead be totally reflected back internally. This can only occur when the wave in a medium with a higher refractive index (n) reaches a boundary with a medium of lower refractive index (n). For example, it will occur with light reaching air from glass, but not when reaching glass from air.
 Question: does total internal reflection occur at the critical angle
Yes
Yes
Yes
No