A lethal dose (LD) is an indication of the lethality of a given substance or type of radiation. Because resistance varies from one individual to another, the 'lethal dose' represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die. The LD may be based on the standard person concept, a theoretical individual that has perfectly "normal" characteristics, and thus not apply to all sub-populations.

Lethal doses are usually expressed as median lethal dose (LD50), the point where 50% of test subjects exposed would die, in the units of mg/kg body weight. For gases and aerosols, lethal concentration (mg/m³ or ppm, parts per million) is the analogous concept, although this also depends on the duration of exposure, which has to be included in the definition. The lowest known lethal dose, derived from an individual case of poisoning, is abbreviated LCLo.

LD values for humans are best estimated by extrapolating results from human cell cultures. One outdated form of extrapolation involves measuring LD on animals like mice or dogs, converting to dosage per kilogram of biomass, and extrapolating to human norms. The degree of error from animal-extrapolated LD values is very large. The biology of test animals differs in important aspects to that of humans. For instance, mouse tissue is approximately fifty times less responsive than human tissue to the venom of the Sydney funnel-web spider. The square-cube law also complicates the scaling relationships involved. Researchers are now shifting away from animal-based LD measurements. The U.S. Food and Drug Administration has begun to approve more reliable non-animal methods in response to research cruelty concerns and the lack of validity/sensitivity of animal tests as they relate to humans.

Roderick David "Rod" Stewart, CBE (born 10 January 1945) is a British singer-songwriter, born and raised in North London, England, and currently residing in Epping. He is of Scottish and English ancestry.

With his distinctive raspy singing voice, Stewart came to prominence in the late 1960s and early 1970s with The Jeff Beck Group and then Faces. He launched his solo career in 1969 with his debut album An Old Raincoat Won't Ever Let You Down (US: The Rod Stewart Album). His work with The Jeff Beck Group and Faces influenced heavy metal genres.

With his career in its fifth decade, Stewart has sold over 100 million records worldwide, making him one of the best selling artists of all time. In the UK, he has had six consecutive number one albums, and his tally of 62 hit singles include 31 that reached the top 10, six of which gained the number one position. He has had 16 top ten singles in the U.S, with four of these reaching number one on the Billboard Hot 100. In 2008, Billboard magazine ranked him the 17th most successful artist on the "The Billboard Hot 100 Top All-Time Artists". He was voted at #33 in Q Magazine's list of the top 100 Greatest Singers of all time, and #59 on Rolling Stone 100 Greatest Singers of all time. As a solo artist, Stewart was inducted into the Rock and Roll Hall of Fame in 1994, and was inducted a second time, as a member of Faces, in April 2012.

Vincent Kennedy "Vince" McMahon (born August 24, 1945) is an American professional wrestling promoter, announcer, commentator, film producer, actor and former occasional professional wrestler. McMahon is the Chairman, CEO and Chairman of the Executive Committee of professional wrestling promotion WWE. Upon acquiring World Championship Wrestling (WCW) and Extreme Championship Wrestling (ECW), McMahon's WWE became the sole remaining major American professional wrestling promotion (until the national expansion of Total Nonstop Action Wrestling and Ring of Honor).

As an on-camera character, he can appear on all WWE brands (though the majority of the time, he appears on Raw). McMahon plays a character known by the ring name Mr. McMahon, based on his real life persona. In the world of WWE, he is a two-time world champion, having won the WWF Championship and ECW World Championship. He was also the winner of the 1999 Royal Rumble.

Vince is the husband of Linda McMahon, with whom he ran WWE from its establishment in 1980 until she resigned as the CEO in September 2009.

Doctor of Philosophy, abbreviated as Ph.D., PhD, D.Phil., or DPhil (for the Latin philosophiae doctor or doctor philosophiae), in English-speaking countries, is a postgraduate academic degree awarded by universities. The academic level of degrees known as doctorates of philosophy varies considerably according to the country, institution, and time period, from entry-level research degrees to higher doctorates. A person who attains a doctorate may be referred to as a doctor.

In the context of academic degrees, the term "philosophy" does not refer solely to the field of philosophy, but is used in a broader sense in accordance with its original Greek meaning, which is "love of wisdom". In most of Europe, all fields other than theology, law and medicine were traditionally known as philosophy. The doctorate of philosophy as it exists today originated as a doctorate in the liberal arts at the Humboldt University of Berlin, and was eventually adopted by United States universities, becoming common in large parts of the world in the 20th century. In many countries, the doctorate of philosophy is still awarded only in the liberal arts, which is known as "philosophy" in continental Europe.