This week, the killings of George Floyd, Breonna Taylor, and other Black Americans by police brutality and racial inequality continue to fuel demonstrations around the nation. In many cities, police are using tear gas, rubber bullets, and other control tactics on protesters. A history of 50 years of research reveals what makes a protest safe for participants and police alike. The findings show that police response is what makes the biggest difference: de-escalating and building trust supports peaceful demonstrations rather than responding with weapons and riot gear. And, as thousands of protesters risk abrasive, cough-inducing tear gas and mass arrests, health researchers are concerned a militant response could increase demonstrators’ risk of acquiring COVID-19. Maggie Koerth, senior science writer for FiveThirtyEight and a Minneapolis, Minnesota resident, joins Ira to discuss these stories. Dermatologists presented with a new patient have a number of symptoms to look at in order to diagnose. Does the patient have a rash, bumps, or scaling skin? Is there redness, inflammation, or ulceration? For rare conditions a doctor may have never seen in person before, it’s likely that they were trained on photos of the conditions—or can turn to colleagues who may themselves have photos. But in people with darker, melanin-rich skin, the same skin conditions can look drastically different, or be harder to spot at all—and historically, there have been fewer photos of these conditions on darker-skinned patients. And for these patients, detection and diagnosis can be life-saving: people of color get less melanoma, for example, but are also less likely to survive it. Dr. Jenna Lester, who started one of the few clinics in the country to focus on such patients, explains the need for more dermatologists trained to diagnose and treat people with darker skin tones—and why the difference can be both life-saving and life-altering. A cup of coffee first thing in the morning is a ritual—from grinding the beans to boiling the water and brewing your cup. But following those steps won’t always get you a consistent pour. Researchers developed a mathematical model to determine how the size of grind affects water flow and the amount of coffee that gets into the final liquid. Their results were published in the journal Matter. Computational chemist Christopher Hendon, who was an author on that study, talks about how understanding atomic vibration, particle size distribution, and water chemistry can help you brew the perfect cup of coffee. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

Ask this episode

“What did the council decide on item 42?” — answered with the speaker and the moment.