Daily briefing: Why get two PhDs

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Reproducibility fears over machine learning

Two researchers have sounded the alarm about the use of machine learning to make predictions on the basis of patterns in data. In some cases, methodological pitfalls could lead to wildly overoptimistic conclusions, they say. A prominent issue is ‘data leakage’, when information from the data set a model learns on includes data that it is later evaluated on. If these are not entirely separate, the model has effectively already seen the answers, and its predictions seem much better than they really are. Machine-learning researchers Sayash Kapoor and Arvind Narayanan have created guidelines for scientists to avoid such pitfalls, including a checklist to submit with each paper.

Nature | 7 min read

Reference: arXiv preprint (not peer reviewed)

How long is COVID infectious?

Evidence is mounting that some people can continue to pass on SARS-CoV-2 for much longer than the few days often suggested by public-health agencies. A series of studies shows that many people with COVID-19 remain infectious well into the second week after they first experience symptoms. “The facts of how long people are infectious for have not really changed,” says infectious-disease specialist Amy Barczak, whose research suggests that one-quarter of people who have caught the Omicron variant of SARS-CoV-2 could still be infectious after eight days. “There is not data to support five days or anything shorter than ten days.”

Nature | 6 min read

Reference: medRxiv preprint 1 & medRxiv preprint 2 (not peer reviewed)

China approves homegrown COVID antiviral

China’s drug regulator granted conditional approval on Monday for an HIV drug to be used to treat COVID-19. The drug, Azvudine, developed by Chinese drugmaker Genuine Biotech, is the first oral antiviral for the disease made in China. In an announcement, the company said that 40% of people with COVID-19 who were given Azvudine for a week in a phase III clinical trial showed “improved clinical symptoms”, compared with 11% of those given a placebo. Detailed data from the trial, including whether the treatment reduced the risk of hospitalization or death, have not been released. Another Chinese-made oral antiviral, VV116, is in the final stages of development, and another dozen are in various stages of development.

Nature | 4 min read

Features & opinion

‘Red flags’ in key Alzheimer’s research

Neuroscientists are reeling from claims that images show signs of having been fabricated in dozens of influential Alzheimer’s research papers. Physician-scientist Matthew Schrag says that there are “red flags” in research led by neuroscientist Sylvain Lesné, which underpins the dominant yet controversial theory that beta-amyloid plaques are a root cause of Alzheimer’s disease. Science reports that Lesné did not respond to requests for comment. “The immediate, obvious damage is wasted NIH funding and wasted thinking in the field because people are using these results as a starting point for their own experiments,” says Nobel-prizewinning Alzheimer’s researcher Thomas Südhof.

Pharmaceutical researcher Derek Lowe, who is sceptical of the amyloid hypothesis, argues that the reality is even worse. “I’ve noticed a lot of takes along the lines of ‘OMG, because of this fraud we’ve been wasting our time on Alzheimer’s research since 2006’,” he writes. “We’ve been actually been wasting our time in Alzheimer’s research for even longer than that.”

Science news story | 20 min read & Science opinion column | 15 min read

Double doctors: why get two PhDs

Earning one PhD is difficult enough — but there are the rare individuals who opt to swim extra laps in the stress pool to secure a second one. Some do it to carve out a distinct research niche for themselves, others to access resources that are unavailable in their home countries. Some might simply enjoy the challenge. Three ‘double doctors’ share what they gained — and whether it was worth it.

Nature | 8 min read

From Togo to Kunming: a PhD abroad

After earning her bachelor’s degree in Togo in West Africa, biomedical researcher Manzama-Esso Abi moved to Kunming, China, to study for a PhD. Her welcome was a warm one: after missing a connecting flight and arriving late, a woman she met on the plane paid for a hotel, breakfast and a ride to her university. Abi has since applied herself to learning Mandarin and improving her English — and plans eventually to return home. “I am eager to share everything I have learnt with the people of my country,” she writes.

Nature | 5 min read

This article is part of a series about the career experiences of African scientists.

Infographic of the week

Physicists have built a molecular-scale motor entirely from DNA strands, and used it to store energy by winding up a DNA ‘spring’. It is not the first DNA nanomotor, but it’s “certainly the first one to actually perform measurable mechanical work”, says biophysicist and co-author Hendrik Dietz. The tiny machine gains energy from Brownian motion — the constant random argy-bargy of molecules in a medium. The machine turns like the ratchet wheel in a clock, winding a string of DNA like a spiral spring. (Nature | 4 min read)See more: A 3-minute video introduces DNA origami — the art of folding DNA to create tiny nanoscale machines that could work inside the human body. (Nature, from 2016)