During those long car and airplane trips to visit family, spare a thought for Irving Liberman, a scientist who helped make GPS a reliable, precise resource. He died on Nov. 6 at his home in the Squirrel Hill section of Pittsburgh. He was 86.

A lifelong tinkerer, Mr. Liberman was always fascinated by how things worked. At a young age, he would take things apart and put them back together, sometimes with parts left over, yet they still worked. Before he would use any gadget, he had to know how it worked.

The owner of eight patents and author of more than 50 publications, Mr. Liberman, who had earned master’s and doctoral degrees in electrical engineering, was recruited by Westinghouse Research & Development. In 1995, he was the project manager for a cohort that developed the miniature atomic clock, which was accurate within a millionth of a second per day and would come to be used for many disciplines, especially GPS technology, and also smart bombs, cellular communication systems and even the ankle bracelets worn by prisoners.

Andrea Fay Friedman, an actress with Down syndrome, who starred in the television series “Life Goes On” died on Dec. 3 at her home in Santa Monica, CA. She was 53.

Ms. Friedman was known for her portrayals of people with developmental disabilities. She called her Down syndrome her “up syndrome,” her father, Hal Friedman, said in a phone interview.

Her breakthrough in acting came in 1992 on the TV drama “Life Goes On” about a character with Down syndrome. Ms. Friedman played the main character’s girlfriend and later wife, for two seasons. She also appeared in other TV shows, including “Baywatch,” “ER,” and “Law and Order: SVU.”

Rabbi David Ellenson, a scholar who wrestled with the interplay of tradition and modernity in Judaism,, and who shaped a generation of Reform rabbis as a teacher and later as the president of Hebrew Union College-Jewish Institute of Religion, died on Dec. 7 at his home in Manhattan. He was 76.

He taught for more than 40 years at the Reform seminary, which trains rabbis, cantors and Jewish educators on four campuses: in New York, Cincinnati, Los Angeles and Jerusalem. He forged important academic and intellectual alliances across the Orthodox, Conservative, Reform and Reconstructionist branches of Judaism. The question that animated his life was: How does the Jewish religious tradition adapt, transform and resist the powerful forces of modernity?

Rabbi Ellenson wrote seven books and more than 300 articles and reviews. His book, After Emancipation: Jewish Religious Responses to Modernity (2005) won the 2006 National Jewish Book Award as the outstanding book on Jewish thought.

Shlomo Avineri, an Israeli political scientist, historian and former government official whose pessimism about resolving the conflict with Palestinians did not stop him from advocating measures to ease it, died on Nov. 30 in Jerusalem. He was 90.

In his writings, Mr. Avineri was consistently skeptical about Israel’s prospects for achieving peace with its enemies. He was convinced of Palestinian and Arab hatred for Israel and Zionism, whose 19th-century roots he chronicled in 1981 in his book, The Making of Modern Zionism. The Hamas attack in Israel on Oct. 7 buttressed this view. Immediately afterward, speaking to The New York Times, he noted what he said was Hamas’s view that in Israel “every civilian is a soldier.”

Mr. Avineri had a distinguished academic career behind him when he entered Israel’s foreign ministry in 1975 as director general in the government of Yitzhak Rabin. “What I have in mind specifically,” he wrote at that time, “is a discussion with the Palestinians now under Israeli rule concerning the possibility of establishing a Palestinian Arab state on the West Bank and in Gaza.”

George A. Cohon, a Chicago-born entrepreneur who, by introducing the Big Mac — or the Bolshoi Mac — to Moscow in 1990, died on Nov. 24 at his home in Toronto. He was 86.

A Fuller Brush salesman in college with a flair for merchandising, Mr. Cohon abandoned his law practice when Ray Kroc, the McDonald’s founder, offered him the chain’s franchise for eastern Canada. Mr. Cohon borrowed $70,000 to buy the rights and opened his first restaurant in London, Ontario, in 1968. In 1971, he traded the franchise for McDonald’s stock and in 1992 became senior chairman of McDonald’s Restaurants of Canada, which included some 1500 eateries, and of McDonald’s in Russia.

Though waiting on lines was part of daily life in Soviet Russia, opening day in Moscow — Jan. 31, 1990 — exceeded all expectations when an estimated 10,000 people queued up in Pushkin Square for Happy Meals and double cheeseburgers. By the end of the day, around 30,000 people had sampled the menu at the mammoth 700-seat restaurant, emblazoned with its trademark golden arches. It was the beginning of what Mr. Cohon called “hamburger diplomacy.”

At McDonald’s in Canada, where he was chairman, president, and chief executive until 1992, Mr. Colon was a self-styled, hands-on “front counter kind of guy,” as he wrote in his memoir. He handed out hamburger-shaped business cards that included a voucher for a free Big Mac.

Mort Engelberg, a movie producer behind such hits as “Smokey and the Bandit” and “The Big Easy” who drew on his Hollywood expertise to stage manage appearances for politicians, notably a bus tour for Bill Clinton and Al Gore following the 1992 Democratic convention, died Dec. 9 in Los Angeles. He was 86.

He drew on the tropes of road movies to invent the modern presidential bus tour for Clinton and Gore through Pennsylvania, Indiana, Kentucky and other heartland states. The eight-day bus trip drew throngs of people, and helped to cement Mr. Clinton’s image as a down-home politician.