There are two very different pictures of the students roaming the hallways and labs of Tandon School of Engineering in New York University (NYU).
At the undergraduate level, 80 per cent are United States residents. At the graduate level, the number is reversed: About 80 per cent hail from India, China, Korea, Turkey and other countries.
For graduate students far from home, the swirl of cultures is reassuring and invigorating. "You're comfortable everyone is going through the same struggles and journeys as you are," said Ms Vibhati Joshi from Mumbai, who's in her final semester for a master's degree in financial engineering. "It's pretty exciting."
The Tandon School - a consolidation of NYU's science, technology, engineering and math programmes on its Brooklyn campus - is an extreme example of how scarce Americans are in graduate programmes in Stem. Overall, these programmes have the highest percentage of international students of any broad academic field. In the autumn of 2015, about 55 per cent of all graduate students in mathematics, computer sciences and engineering were from abroad, according to a survey by the Council of Graduate Schools and the Graduate Record Examinations Board.
In arts and humanities, the figure was about 16 per cent; in business, a little more than 18 per cent. The dearth of Americans is even more pronounced in Stem fields like computer science, which serve as talent pipelines for the likes of Google, Amazon, Facebook and Microsoft: About 64 per cent of doctoral candidates and almost 68 per cent in master's programmes last year were international students. In comparison, only about 9 per cent of undergraduates in computer science were international students (perhaps, because families are nervous about sending offspring who are barely adults across the ocean to study).
Many factors contribute to the gap, but a major one is the booming job market in technology. For the most part, Americans do not see the need for an advanced degree when there are so many professional opportunities. For some, the price is just too high when they have so much student debt already. "You can believe that US bachelor's students, if they're good, can go get a job at Microsoft or Google with a bachelor's degree," said University of Washington's professor of computer science Edward Lazowska.
Mr Hadi Partovi, a tech investor, received his master's in computer science from Harvard in the 1990s. His roommate did not. They both got job offers from the same company. "Master's grads are valued more, but not enough more for American students to get a master's degree," said Mr Partovi, a founder of Code.org, a nonprofit that promotes computer science in grade school and high school.
Universities and employers are eager to tap the pool of international talent that helps them stay competitive globally, and graduate programmes have a financial incentive in attracting them: Demand from abroad is so high, administrators don't see a need to offer as much tuition assistance. There's concern, though, that the current climate around immigration could jeopardise that flow of talent. Incidents of xenophobia, hostile political rhetoric and President Donald Trump's attempts at banning travellers from some Muslim-majority countries may weigh on the minds of potential applicants.
The Thayer School of Engineering at Dartmouth, for example, saw a 30 per cent decrease in international applications for its professional master's programme for a recent semester, according to dean Joseph Helble. He surveyed more than two dozen engineering deans earlier this year, and three quarters of them said they, too, had seen significant drops in international graduate applications. But enrolment, he said, was not off.
Still, trends are not clear.
"If there are one or two more years of comparable 20 to 30 per cent decreases in international applications, we're very concerned about our ability to conduct research and spin off and start companies," he said. "We're concerned from a competitive perspective."
Mr Dan Spaulding, who oversees human resources at Zillow Group, the online real estate company, said that in specialised areas like machine learning and artificial intelligence, his firm favours graduate degrees, but for the vast majority of its technical jobs, a bachelor's degree in computer science is adequate. He said he has heard concerns from students and managers about an international chill, but for now the supply of students with computer science skills is not affected.
"A great many of them are coming in with programming skills first and looking to radiate out into other business disciplines, product management, product design," he said. "I think going deep academically is not a priority for as many computer science students today."
In 1994, only about 40 per cent of students who were enrolled in computer science PhD programmes were from outside the country, according to the Computing Research Association survey. As the economy improved, the percentage of Americans in graduate programmes dropped. "Going to grad school became less of a priority for so many students," said Dr Stuart Zweben, co-author of the survey and professor emeritus of computer science and engineering at Ohio State University. "You had to really be interested in research or something special."
The balance of computer science graduate programmes began to tilt towards so-called non-resident aliens in the late 1990s, when well-capitalised dot.coms began scouring for programmers, sometimes encouraging summer interns to drop out of school, Dr Zweben said.
Students from other countries see graduate school as their best path to employment and residency in the US, and for the industry connections they are not likely to find back home. "It's easier to get access from here," said Ms Joshi, who is president of the NYU finance club. She wanted to attend NYU so she could merge her background in information technology with her interest in the financial industry.
Her decision paid off. Ms Joshi, 25, has accepted an offer to work in risk management at American Express once she completes her master's. She will apply for Optional Practical Training, a programme that allows her to work in the US for a year, with an option of extending it for up to another 24 months. It will be up to her employer to sponsor her for an H1-B visa after that, allowing her to stay longer.
The Tandon School recently started "A Bridge to NYU Tandon", aimed at preparing students with non-Stem backgrounds like liberal arts for master's programmes. Dean Katepalli Sreenivasan believes this could attract Americans who have not yet found decent jobs. And he would like to see more of them enrolled in the graduate programmes. "I feel that's an imbalance," he said, "that absolutely needs to be corrected."