As 2015 draws to a close, the Gazette looks back on some of its top stories. It was a year when breakthrough research identified harmful chemicals in e-cigarettes and learned how toxic co-workers can be, but also how coffee and even a little sarcasm can be good for us.And it was a year in which esteemed scholars such as poetry critic Helen Vendler and physicist Gerald Holton spoke deeply about their intellectual journeys, while pianist Vijay Iler touched on the value of practice. And faculty shared the books that shaped them.As always, inspiring students sparkled, such as the five members of the Class of 2016 selected as Rhodes Scholars, a onetime Somali refugee determined to lead her homeland in a new direction, the young writers stepping up to be journalism’s hopeful future, and a cadre of Buddhist monks from Asia studying at Harvard Divinity School.In arts and sciences, an Academy Award-winning actress confessed to feelings of self-doubt while at Harvard College, the Faculty of Arts and Sciences added a new theater, dance, and media concentration for undergraduates, and a historic $400 million gift secured the bright future of Harvard’s School of Engineering and Sciences (SEAS).Students, faculty, and administrators grappled with disturbing results of a national survey on sexual assault on college campuses. President Drew Faust spoke candidly about many developments, including the House renewal project, the Harvard Campaign, and the expanded Harvard Art Museums, as well as some of her top priorities for the academic year, while Provost Alan Garber made a persuasive case for protecting academic disciplines.The Gazette took readers to Mexico for a series exploring Harvard’s many efforts to confront housing, pollution, and traffic challenges, and brought home the remarkable journey taken by middle school students from a hardscrabble Brooklyn neighborhood to Harvard’s campus last spring to learn that college is not an abstraction, but a possibility. A three-part series examined the epidemic of opioid abuse and what can be done to counter it.Stories glimpsed life in earliest Colonial America, with a look at the Old Burying Ground that opened in 1636, the year of Harvard’s founding, and an ambitious archival project to digitize the University’s collection of priceless diaries, journals, notebooks, and other documents from 17th and 18th centuries.Here are some of the year’s most popular and significant Gazette stories, along with the top videos shared on YouTube.Harvard’s Colonial North American Project website includes 150,000 images of diaries, journals, notebooks, and other rare documents from the 17th and 18th centuries. A sampling of them are on display at the Pusey Library. Stephanie Mitchell/Harvard Staff PhotographerA digital portrait of Colonial lifeWealth of detail in wide-ranging archival projectPart of the University’s endeavor to digitize all its collections and make them available free of charge, the Colonial North American Project contains material scattered through 12 repositories — from Houghton Library to the Harvard University Archives to Loeb Music Library.Go ahead, be sarcasticResearch uncovers creative benefits — yes, benefits — in using sarcasm when people trust each otherDespite sarcasm’s nasty reputation, new research finds that it can boost creativity and problem-solving in the workplace.Beware those toxic co-workersStudy says they undercut groups in destructive, expensive waysThe new study examined both the human and fiscal costs of toxic workers.Class Day speaker Natalie Portman urged students to take advantage of the brimming self-confidence of youth and take chances even at the risk of not coming out on top. Stephanie Mitchell/Harvard Staff PhotographerPortman: I, too, battled self-doubtClass Day speaker says that even as a Harvard student and successful actress, she questioned her worth, but learned to set her own goalsNatalie Portman, the Academy Award-winning actress, returned to Harvard for Class Day to share her own experience with insecurity.Harvard receives its largest giftJohn A. Paulson gives $400 million to endow School of Engineering and Applied Sciences, securing vision for Allston-based innovationAs the School prepares for an expansion into Allston, it receives funding to secure its impact on the world.The books that shaped themSix professors reflect on their most memorable titlesFaculty members talk about the formative books that shaped their lives and even their scholarship.Harvard President Drew Faust is pictured in her Massachusetts Hall office. Stephanie Mitchell/Harvard Staff PhotographerQ&A with Harvard President Drew FaustFaust discusses University’s priorities and challengesAt the beginning of her ninth year as president of Harvard, Drew Faust outlined her plans for the University, and the challenges it faces.A onetime refugee aims highWhen she graduates from the Kennedy School, Fadumo Dayib plans to run for president of SomaliaA 2015 graduate from Harvard Kennedy School explains her journey from Somalia to Cambridge, and what she hopes to accomplish upon her return home.Chemical flavorings found in e-cigarettes linked to lung diseaseFocus on nicotine overshadowed other hazards attached to smoking deviceDiacetyl, a flavoring chemical linked to cases of severe respiratory disease, was found in more than 75 percent of flavored electronic cigarettes and refill liquids tested by researchers at the Harvard T.H. Chan School of Public Health.Student scholars, with dreams aplentyFive Rhodes recipients from Harvard share goals before heading to OxfordThe Harvard students chosen as Rhodes Scholars explained how they’ll spend their time.Jermont Haines (from left), Tukoya Boone, and Aaron Abdulmalik get a science lesson from Graduate School of Arts and Sciences student Tessa Montague. Kris Snibbe/Harvard Staff PhotographerA college vision, made real200 middle school visitors from Brooklyn sample what a university can offerAfter “Humans of New York” photographer Brendan Stanton organized a campaign, the middle school students from Mott Hall Bridges Academy in Brooklyn, N.Y., visited Harvard to sample what a university can provide them.Heroin’s descentStages of losing control, on the street and in the bodyThe Gazette sought insights into the heroin epidemic across several disciplines, including law, health, and the science of addiction, for a three-part report on the crisis and new ideas for responding to it.How coffee loves us backHealth benefits are a recurring theme in Harvard researchCoffee is everywhere, through history and across the world. And increasingly, science is demonstrating that its popularity is a good thing.Jill Johnson applauds a student dance during rehearsal. Stephanie Mitchell/Harvard Staff PhotographerTheater, Dance & MediaFAS approves a new concentration in the artsMembers of the Harvard Faculty of Arts and Sciences (FAS) backed a concentration for College undergraduates in Theater, Dance & Media that blends historical and theoretical study with arts practice.Troubling findings on sexual assaultHarvard’s portion of national study paints disturbing pictureFollowing the release of national survey results, President Faust and the University’s Task Force on the Prevention of Sexual Assault responded to sexual misconduct on campus.The makeover of Mexico CityAided by Harvard experts, officials are tackling housing, pollution, and traffic problems — and solving themWith Harvard experts helping, clever and dynamic Mexico City is dealing with global megacity challenges like traffic and housing, and could be a template for a flexible, functioning urbanism of the future.Harvard’s top three YouTube videos for 2015Natalie Portman’s Class Day Speech | Harvard Commencement 2015 <a href=”https://www.youtube.com/watch?v=jDaZu_KEMCY” rel=”nofollow” target=”_blank”> <img src=”https://img.youtube.com/vi/jDaZu_KEMCY/0.jpg” alt=”0″ title=”How To Choose The Correct Channel Type For Your Video Content ” /> </a> Academy Award-winning actress Natalie Portman ’03 addresses graduating seniors at Harvard’s Class Day ceremony on May 27 at Tercentenary Theatre.A public address by Shinzo Abe, prime minister of JapanJapanese Prime Minister Shinzo Abe addressed the John F. Kennedy Jr. Forum on a range of policy issues affecting his country and the Asian community.Jumping on water: Robotic water striderWatch how novel robotic insects developed by a team of Harvard and Seoul National University scientists can jump directly off water’s surface.Digital communications coordinator Rebecca Wickel contributed to this report.