The Milky Way.Image: NASA
By combining data from the Hubble and Gaia space telescopes, an international team of astronomers has come up with the most accurate estimate yet of our galaxy’s mass. The results, set to be published in a future edition of the Astrophysical Journal (pre-print here), posits a total mass of the Milky Way at 1.5 trillion solar masses, which extends out some 129,000 light-years from the center of the galaxy. In the ESA press release, study co-author Roeland van der Marel, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland, said his team was able to “pin down the Milky Way’s mass in a way that would be impossible without these two space telescopes,” so this is a good example of scientists pooling their resources to produce research that wouldn’t otherwise be achievable.

The team identified 39 of these traditions that are practiced by some communities but not others—a pattern that, at the time, hadn’t been seen in any animal except humans. It was evidence, the team said, that chimps have their own cultures. It took a long time to convince skeptics that such cultures exist, but now we have plenty of examples of animals learning local traditions from one another.

According to Luana Colloca, a placebo expert at the University of Maryland, reactions like Peabody’s aren’t uncommon in depressed patients who are randomly assigned placebos in clinical drug trials — though they’re taking a fake drug, their depression will often improve and their good mood will last. They can help with major depression like Peabody’s, too; while real drugs are often more effective in these cases, research from University of Utah psychiatrist Jon-Kar Zubieta found that placebo was a productive treatment for 45 to 50 percent of severely depressed participants. This is a major reason why Peabody’s depression stayed manageable after her drug trial ended — because of her high expectations and her strong belief that she was getting the help she needed, she’d effectively conditioned her brain to respond in the way she thought it was supposed to.

By 2050, if current rates of emissions continue, roughly half of the world’s people will live in places where the Aedes aegypti mosquito—one of the most serious threats to global health, given its resilience in urban spaces and preference for things like stagnant water around homes—flourishes. These researchers specifically studied the spread of the Aedes aegypti and Asian tiger (or Aedes albopictus) mosquitoes—two tropical species that have become the predominant transmitters of viruses like Zika, chikungunya, and dengue—under 17 climate-change scenarios. Their predictive model combines more than 33,000 data points on where mosquitoes have been detected across the world with historical data about their spread into Europe and the U.S. beginning in the 1970s and ‘80s, as well as projections of climate changes, human movement, and urban growth.

Gabbett eventually found a report on “sesquizygotic twins”:  not identical, but not fraternal either. Biologists had first proposed their existence in 1984, but it wasn’t until 2007 that doctors documented the first case of sesquizygotic twins. The sesquizygotic twins are likely the result of three separate events in the womb, each one rare by itself.

It’s possible to use the position to calculate the angle to aim the mirror—but that’s not as much fun as using polar coordinates. Rhett Allain
Describing the velocity in polar coordinates isn’t just in one dimension and those values aren’t constant. With these values, I can use the differential equations to find the polar velocity and position after some short time interval.

This week, NASA released the first-ever images of shockwaves from two supersonic jets interacting, and they are simply stunning. They feature two T-38s from the US Air Force Test Pilot School at Edwards Air Force Base with shockwaves — the rapid pressure changes that produce sonic booms — emanating from them, looking a little bit like waves from a fast-moving motorboat. The picture above has been colorized to emphasize the interaction of the shockwaves; here’s what the original monochrome looks like:

Just for the hell of it, here’s what the shockwaves look like in blue:

The imaging system that captured these photographs will be used to help test a new jet design that produces “shockwaves in such a way that, instead of a loud sonic boom, only a quiet rumble may be heard.”

Professor Duncan P. Hand and his research team have developed a process called “ultrafast laser microwelding,” which uses very, very short pulses of infrared laser light to fuse two dissimilar materials together. Professor Hand described the process to Phys.org:
“The process relies on the incredibly short pulses from the laser. Being able to directly weld panels of, say, glass and aluminum could open up many interesting possibilities for auto design and manufacturing.

This is the starting point for his new book, The Creativity Code, a lucid, endlessly interesting exploration of what AI may mean for maths, the arts and even our understanding of what it is to be human. In Du Sautoy’s field of maths, it held out the prospect of AI moving beyond dull, if complex, number crunching, into the kind of quintessentially human activities that define how the subject works: strategising, discriminating and “making choices about the interesting pathways to take”. Du Sautoy also looks at AI-generated art, and programs that have come up with superficially convincing works based on the techniques of such old masters as Rembrandt (“a horrible, tasteless, insensitive and soulless travesty of all that is creative in human nature”, reckoned Guardian art critic, Jonathan Jones).

Over the past few years, Olson watched as the formerly notorious anesthetic cum party drug was rebranded as an experimental miracle for treatment-resistant depression. Ketamine has the ability to rebuild fraying connections between brain cells integral to networks that regulate emotions and mood, thanks to an effect known as neural plasticity. Olson suspected that the process by which ketamine promotes this type of plasticity could be activated by other substances as well, and in June his team published a paper showing that in rats, psychedelics such as LSD, ecstasy, and dimethyltryptamin, or DMT, mirror ketamine’s effects.