Uncertainty can be hard for humans. It drives anxiety, an emotion neuroscientists are trying to understand and psychologists are trying to better treat.

Why it matters: Under the threat of a virus, job insecurity, election uncertainty, and a general pandemic life-in-limbo that is upending school, holidays and more, people are especially anxious.

• Before the pandemic, anxiety was already climbing in the U.S., especially among young adults, according to a recent study.
• Add the pandemic and its many unknowns: 35% of adults in the Household Pulse Survey reported symptoms of anxiety disorder in July. (In the first half of 2019, it was roughly 8%.)

The big picture: "We have anxiety for a reason," says Stephanie Gorka, who studies the neurobiology of anxiety and treatments for anxiety-related disorders and phobias at the Ohio State University.

• Anxiety alerts people to pay attention to their environment and is key to our survival, but if it is chronic or excessive, it can have negative health consequences, she says.
• But how exactly the brain responds to uncertainty and leads to anxiety is unclear.

What's new: Recent research suggests the brain circuitry for anxiety and fear, separate emotions long thought to activate different regions in the brain, overlap.

• Fear is typically a reaction to a certain, immediate threat, whereas anxiety is a prolonged state of worrying about and anticipating an uncertain harm.
• Both involve many parts and processes of the brain, but fear has been linked to activity in the amygdala and anxiety to a structure called the bed nucleus of the stria terminalis (BNST).

In a study published last week, neuroscientist Alexander Shackman of the University of Maryland and his colleagues presented 99 student participants "triple threat" stimuli to invoke both emotions.

• A combination of a painful electric shock, a disturbing image and an aversive recording (a scream, for example) was given either after a countdown (to spur fear) or at an unpredictable time (to invoke anxiety).
• Whether the subjects experienced fear or anxiety, both the amygdala and the BNST responded.

The impact: The amygdala-is-fear/BNST-is-anxiety concept has guided research on mental health disorders, says Shackman, who adds that recognizing the connection and overlap between fear and anxiety could possibly lead to better treatments.

What to watch: There is evidence building that another region of the brain — the insula — is key to anticipating threat, says Gorka.

• Gorka has found that individuals who are more sensitive to uncertainty have a greater connectivity between the insula and the dorsal anterior cingulate cortex, an area linked to strategizing and future-planning.
• Sensitivity in that circuit seems to make someone more vulnerable to anxiety and alcohol use disorders.
• "Those individual differences in how people tolerate uncertainty are clinically meaningful," says Gorka.

How it works: Psychological tests, including the Intolerance of Uncertainty scale, capture those differences as well.

• People employ different strategies for coping with uncertainty — some may avoid it if they are sensitive to it, whereas others may be more flexible.
• Lucy McBride, who practices medicine in D.C., tells her patients that "anxiety is part of the human condition and the survival mechanisms we have," and she stresses the importance of sleep, therapy, minimizing stimulants and other lifestyle modifications.

Keep in mind: Humans are resilient and, as Arthur C. Brooks recently wrote in the Atlantic, difficulty and uncertainty can be "an opportunity for improvement and personal growth, without pushing away the negative emotions that are a natural by-product of hard times."

Americans need to prioritize getting their influenza vaccine now, public health officials warned Thursday, Eileen Drage O'Reilly reports.

Why it matters: The seasonal flu combined with the coronavirus pandemic could lead to a "twindemic" with increased chances of co-infections with the viruses and an overwhelmed health system.

• Because symptoms are similar and diagnostics aren't fast, people can best mitigate their risks with the flu shot plus social distancing and mask-wearing this fall and winter.

What's happening: "This is going to be a diagnostic area of confusion this entire winter season, what with these two viruses and other respiratory viruses that are out there," National Foundation for Infectious Diseases medical director William Schaffner said during a press briefing.

• The good news: Similar behaviors are helpful in preventing both viruses, and if people get the flu shot and continue practicing measures like mask-wearing, social distancing and handwashing, the U.S. may see a mild flu season similar to the Southern Hemisphere, NIAID director Anthony Fauci said.

By the numbers: The most-cited reason for participants to not get a vaccine, per an NFID survey out Thursday, continues to be disbelief in the shot's effectiveness — but this dropped from 51% last year to 34% this year, Schaffner said.

Between the lines: Many of the same people most vulnerable to serious complications of COVID-19, such as older adults and those with chronic health conditions, are also at risk for complications from the flu, including myocarditis, pneumonia, heart attacks and strokes.

• Cardiologist Federico M. Asch of Georgetown University said flu vaccinations and pneumococcal vaccines have been shown to lower rates of cardiac arrest in people with heart disease, diabetes, COPD and asthma.

Health disparities — seen prominently in the pandemic — play a role with flu vaccinations as well, multiple health officials said.

• Black adults (61%) are more worried about co-infections than Hispanic (53%) and white adults (39%) — but nearly 62% of Black adults said they are either unsure about getting, or will not get, a flu vaccine this year, per the survey.
• "This disconnect is a big concern," said NFID president Patricia N. Whitley-Williams, citing multiple barriers to vaccination in communities, including unconscious bias, institutional racism, distrust of the health care system, and vaccine hesitancy.
• 65% of Hispanic and 59% of white adults plan to get flu shots this season.

Go deeper.

• "New coronavirus infections rose over the past week in half the country," Axios' Sam Baker and Andrew Witherspoon write. The U.S. is continuing to average about 43,000 new cases per day.

• More than 1 million people have now died of COVID-19 globally. Excess mortality figures from the U.S. and elsewhere point to an even higher true death toll.
• 85%–90% of Americans are still susceptible to SARS-CoV-2, the NYT's Donald McNeil Jr. reports. That means herd immunity is "still very far off."
• A study claims a segment of DNA that increases the risk for developing severe COVID-19 was inherited from Neanderthals, The Guardian's Ian Sample writes. Experts said making the connection risks oversimplifying the disease's causes and are skeptical of the finding's meaning.

Startup IonQ today announced what it's calling "the world's most powerful quantum computer," Axios' Bryan Walsh writes.

Why it matters: Quantum is the next frontier in computing, theoretically capable of solving problems beyond the ability of classical computers. IonQ's next-generation computer looks set to push the boundaries of quantum, but it will still take years before the technology becomes truly reliable.

How it works: IonQ reports its new quantum computer system has 32 "perfect" qubits — the basic unit of information in a quantum computer — that the company says gives it an expected quantum volume of more than 4,000,000.

• Quantum volume is a metric that attempts to calculate the computing effectiveness of a quantum computer. These types of metrics are necessary because quantum computers are built in different ways and to different specifications.
• "The way we achieved it is by having good fidelity in our qubits," says Peter Chapman, IonQ's president and CEO. "You can have a million qubits, but if your fidelity isn't good enough, it doesn't really matter."

The catch: IonQ hasn't yet released detailed specifications of its new system, and its research needs to be verified.

• That fact "puts me in wait-and-see mode," Greg Kuperberg, a quantum computing expert at the University of California-Davis, told Fortune.

Context: IonQ's announcement comes in the same week that its competitor Honeywell, which also uses a version of trapped ions, reported achieving a quantum volume of 128, and the Canadian startup D-Wave announced a 5,000-qubit system built in yet another way that would be available for customers, including via the cloud.

Be smart: Comparing different kinds of quantum computing systems is difficult because they function in fundamentally different ways.

• But given that quantum computers tap the confounding principles of quantum physics, where qubits can be superposed in two different states at the same time, perhaps that makes a kind of sense.

The age of engineering life begins (Bryan Walsh — Axios)

The end of deafness (Emily Mullin — Future Human)

Scientists discover two newborn stars encased in table salt (Miriam Kramer — Axios)

The deep Anthropocene (Lucas Stephens, Erle Ellis, Dorian Fuller — Aeon)

Official inaction: An investigation of the FDA's clinical trial enforcement (Charles Piller — Science)

A songbird that appears to have characteristics of both males and females of the species was spotted last week in southeastern Pennsylvania.

The big picture: The condition known as gynandromorphy, which has been documented in bees, crabs, cardinals, butterflies, and other birds and insects (but not in mammals), may provide insights into reproduction, body symmetry and adaptation.

Details:

• The plumage of male rose-breasted grosbeaks is pink on the underside of their wings and breast when they aren't mating; females have yellow feathers. That difference makes it easier to spot the condition.
• The bird, caught and banded at Powdermill Nature Reserve, a field station of the Carnegie Museum of Natural History, appears female on its left side and male on its right.
• The bird's wing is also a few millimeters shorter on the female side, reflecting a difference typically seen between male and female birds, says Annie Lindsay, bird banding program manager at Powdermill.
• She says as far as she knows, it is the fifth gynandromorph spotted in the program's 60-plus year history.

Zoom in: It's not entirely clear how gynandromorphy arises, but it appears to be one possible result of complex evolutionary processes involving hormones, chromosomes and environmental cues for determining sex.

• Birds have Z and W sex chromosomes — two Zs for a male, and a Z and a W for a female.
• One explanation is that in rare instances, an egg (ZW) doesn't shed half of its genetic material in a polar body.
• If both the polar body and nucleus are then fertilized with Z sperm, the cells divide and the body has one side with cells that are predominantly male (ZZ) and the other female (ZW).

The "condition is normal but it is just very uncommon," says Lindsay, echoing other biologists.

Go deeper: Split-sex animals are unusual, yes, but not as rare as you'd think (NYT)