Question: The score for "To Gillian on Her 37th Birthday" was composed by James Horner, known for his frequent motifs associated with what kind of traditional music?

Context paragraphs:
To Gillian on Her 37th Birthday (play): To Gillian On Her 37th Birthday is an American play by Michael Brady, in 1984.  It was developed through the literary department of the Ensemble Studio Theatre and M Square Entertainment and moved to Circle-In-The-Square.

To Gillian on Her 37th Birthday: To Gillian on Her 37th Birthday is a 1996 American romantic drama film directed by Michael Pressman, and starring Peter Gallagher and Claire Danes as a father and daughter struggling to come to terms with the tragic death of wife and mother Gillian (Michelle Pfeiffer).  The original score was composed by James Horner.

Selective Training and Service Act of 1940: The Selective Training and Service Act of 1940, also known as the Burke-Wadsworth Act, Pub.L.  76–783 , 54 Stat.  885 , enacted  16, 1940 , was the first peacetime conscription in United States history.  This Selective Service Act required that men who had reached their 21st birthday but had not yet reached their 36th birthday register with local draft boards.  Later, when the U.S. entered World War II, all men from their 18th birthday until the day before their 45th birthday were made subject to military service, and all men from their 18th birthday until the day before their 65th birthday were required to register.

Pas de Deux (Horner): Pas de Deux is a double concerto for violin, cello, and orchestra by the American composer James Horner.  The work was commissioned by the Norwegian brother/sister musical duo of the violinist Mari Samuelsen and the cellist Hakon Samuelsen with contributions from the A. Wilhelmsen Foundation.  It was composed from 2011 through 2014 and was premiered on November 13, 2014, with Mari and Hakon accompanied by the Royal Liverpool Philharmonic under the conductor Vasily Petrenko.  "Pas de Deux" marked Horner's first major foray into classical music since the 1980s.

Laurie Fortier: Laurie Fortier (born  1974 ) is an American actress.  She is known for her television work on "Running the Halls", "Push" and "Hemlock Grove", and for her film work in "To Gillian on Her 37th Birthday" and "The In Crowd".

Braveheart (soundtrack): Braveheart – Original Motion Picture Soundtrack is the instrumental soundtrack album to the 1995 film of the same name composed and conducted by James Horner and performed by the London Symphony Orchestra.  It is Horner's second of three collaborations with Mel Gibson as director following "The Man Without a Face" (1993).  The soundtrack, comprising 77 minutes of film score, was noticeably successful and was nominated for Best Original Score at the 68th Academy Awards in 1996, but lost to Luis Bacalov's composition to "".

James Horner: James Roy Horner (August 14, 1953 – June 22, 2015) was an American composer, conductor and orchestrator of film scores.  He was known for the integration of choral and electronic elements, and for his frequent use of motifs associated with Celtic music.

Aliens (soundtrack): The score to the 1986 James Cameron film "Aliens" was composed by James Horner.  The score itself includes musical references to Gayane's Adagio from Aram Khachaturian's "Gayane" ballet suite, which had been used in Stanley Kubrick's "" (1968).  The score also uses musical motifs, sound treatments and excerpts from Jerry Goldsmith's original soundtrack to "Alien" (1979).  Additional cues taken from Jerry Goldsmith's "Alien" score were used in the climax of the film when Horner was unable to finish some cues to Cameron's satisfaction.  The film's editors also reportedly altered the score's chronological flow, sometimes looping, truncating or removing the music and placing it in fragmented form in the film out of context.  Despite production issues, it was nominated for an Academy Award in 1986.  It was performed by the London Symphony Orchestra.  The soundtrack album was released the following year, in 1987.

K'inich Yax K'uk' Mo': K'inich Yax K'uk' Mo' (] "Great Sun, Quetzal Macaw the First", ruled 426 – c. 437) is named in Maya inscriptions as the founder and first ruler, "k'ul ajaw" (also rendered "k'ul ahau" and "k'ul ahaw" - meaning holy lord), of the pre-Columbian Maya civilization polity centered at Copán, a major Maya site located in the southeastern Maya lowlands region in present-day Honduras.  The motifs associated with his depiction on Copán monuments have a distinct resemblance to imagery associated with the height of the Classic-era center of Teotihuacan in the distant northern central Mexican region, and have been interpreted as intending to suggest his origins and association with that prestigious civilization.  One of the most commonly cited motifs for this interpretation is the "goggle-eyed" headdress with which Yax K'uk' Mo' is commonly depicted, seemingly an invocation of the northern central Mexican rain deity known as Tlaloc to later peoples such as the Aztecs.  However, modern strontium isotope analysis of the human remains recovered from the tomb attributed to him indicate that K'inich Yax K'uk' Mo' spent his formative years much closer to Copán, at Tikal, and had not himself lived at Teotihuacan.

Swing Kids (soundtrack): Swing Kids: Music From The Original Motion Picture Soundtrack is the soundtrack from the 1993 film "Swing Kids".  The album combines swing music featured in the film with the film's original score by James Horner (Horner's tracks are in bold).

Supporting paragraphs: To Gillian on Her 37th Birthday James Horner
Answer: Celtic music