James' World 2

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When wildfire smoke is in the air, doctors urge people to stay indoors to avoid breathing in harmful particles and gases. But what happens to trees and other plants that can’t escape from the smoke?

They respond a bit like us, it turns out: Some trees essentially shut their windows and doors and hold their breath.

As atmospheric and chemical scientists, we study the air quality and ecological effects of wildfire smoke and other pollutants. In a study that started quite by accident when smoke overwhelmed our research site in Colorado, we were able to watch in real time how the leaves of living pine trees responded.

How plants breathe

Plants have pores on the surface of their leaves called stomata. These pores are much like our mouths, except that while we inhale oxygen and exhale carbon dioxide, plants inhale carbon dioxide and exhale oxygen.

Both humans and plants inhale other chemicals in the air around them and exhale chemicals produced inside them – coffee breath for some people, pine scents for some trees.

Unlike humans, however, leaves breathe in and out at the same time, constantly taking in and releasing atmospheric gases.

Clues from over a century of research

In the early 1900s, scientists studying trees in heavily polluted areas discovered that those chronically exposed to pollution from coal-burning had black granules clogging the leaf pores through which plants breathe. They suspected that the substance in these granules was partly created by the trees, but due to the lack of available instruments at the time, the chemistry of those granules was never explored, nor were the effects on the plants’ photosynthesis.

Most modern research into wildfire smoke’s effects has focused on crops, and the results have been conflicting.

For example, a study of multiple crop and wetland sites in California showed that smoke scatters light in a way that made plants more efficient at photosynthesis and growth. However, a lab study in which plants were exposed to artificial smoke found that plant productivity dropped during and after smoke exposure – though those plants did recover after a few hours.

There are other clues that wildfire smoke can impact plants in negative ways. You may have even tasted one: When grapes are exposed to smoke, their wine can be tainted.

What makes smoke toxic, even far from the fire

When wildfire smoke travels long distances, the smoke cooks in sunlight and chemically changes.

Mixing volatile organic compounds, nitrogen oxides and sunlight will make ground-level ozone, which can cause breathing problems in humans. It can also damage plants by degrading the leaf surface, oxidizing plant tissue, and slowing photosynthesis.

While scientists usually think about urban regions as being large sources of ozone that effect crops downwind, wildfire smoke is an emerging concern. Other compounds, including nitrogen oxides, can also harm plants and reduce photosynthesis.

Taken together, studies suggest that wildfire smoke interacts with plants, but in poorly understood ways. This lack of research is driven by the fact that studying smoke effects on the leaves of living plants in the wild is hard: Wildfires are hard to predict, and it can be unsafe to be in smoky conditions.

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Organize with other parents

Being the only parent refusing to give your child a smartphone can be isolating for both you and your kid, Rausch said.

“Before you act on your own, find a couple of your kid’s friends, three to five of them. Talk with their parents, and if you all together decide to delay smartphones till high school, then it’s going to be much easier because then you can say ’Well, Johnny is also not getting his smartphone till 14,” he said, adding that this will make the conversation “much more digestible” for the child.

Pike also advised working with other parents. She shared an anecdote about a parent whose child’s fifth grade class formed a parent-teacher association.

“The class parents, as a collective, agreed that they would postpone giving their kids cell phones until they entered middle school. So when nobody else in the classroom has a cell phone, it makes it a whole lot easier for your child not to have a cellphone,” Pike said.

“If your child is the only one without a smartphone, that may present a whole additional set of stressors for your child,” she added.

Phone-based childhood versus play-based childhood

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Sharks swimming off the cost of Brazil have something a little startling coursing through their systems: cocaine.

The drug had never previously been found in wild sharks. But that doesn’t mean these fish are unique; scientists just hadn’t previously tested any shark for coke. The effort was a slam dunk, with the 13 sharks that were examined all testing positive for the drug in their muscles and liver, according to a new study in Science of the Total Environment.

What this means for the sharks is an open question, say the study co-authors Enrico Mendes Saggioro and Rachel Ann Hauser-Davis, an ecotoxicologist and a biologist, respectively, at Brazil’s Oswaldo Cruz Foundation. No one has ever studied the behavioral or physiological impacts of cocaine in sharks, Hauser-Davis says, but her ongoing research on environmental contamination in these apex predators suggests the notorious drug is only one of the animals’ worries.

“We detected high levels of metals and also detected ‘forever chemicals’ [perfluoroalkyl and polyfluoroalkyl substances, or PFASs], pesticides and polycyclic aromatic hydrocarbons, PCBs, and PBDEs in over 30 shark and ray species,” Hauser-Davis says. PCBs, or polychlorinated biphenyls, are carcinogenic chemicals banned by the U.S. in 1976 and by signatories of the United Nations’ Stockholm Convention in 2001. PBDEs, or polybrominated diphenyl ethers, are flame retardants that can disrupt brain development and hormones.

The researchers became interested in drug testing sharks after Mendes Saggioro detected cocaine while researching river water contaminants in Brazil’s state of Rio de Janeiro. Brazil has an estimated 1.5 million cocaine users, according to the World Drug Report 2020 And many areas in the country lack sewage treatment, meaning drug-contaminated urine goes right into waterways. Drug runners may also sometimes dump loads of cocaine into the ocean to avoid a bust. A Discovery Channel Shark Week special in 2023 explored the notion that sharks might take bites of floating cocaine bales, and it found that sharks did investigate dummy packages dropped near the Florida Keys. But researchers don’t think that’s the main way drugs enter sharks’ system. A 2007 study in Florida found that bull sharks have been contaminated with prescription medications via failed sewage systems. Other fish, which are a very common prey for sharks, have also been shown to be contaminated—so sharks may be exposed directly in the water or take on these compounds from their diet. Given the ubiquity of legal pharmaceuticals showing up in aquatic animals, “to think that you wouldn’t find cocaine or other illegal drugs in sharks is kind of crazy,” says Chris Lowe, a marine biologist and director of the Shark Lab at California State University,, Long Beach, who was not involved in the new study.

The researchers in this study tested Brazilian sharpnose sharks (Rhizoprionodon lalandii), a small species that lives near coastlines, from the waters off Rio de Janeiro. They found an average cocaine concentration of 23 micrograms per kilogram in the sharks’ tissue, as well as an average concentration of seven micrograms per kilogram of benzoylecgonine (the compound that cocaine breaks down into as it is metabolized). This is a fairly low level: studies on the impact of cocaine in humans tend to use doses of around 0.4 milligram per kilogram of body weight (one milligram equals 1,000 micrograms). Female sharks had higher concentrations of cocaine than males, however, and half of the females that were caught were pregnant. Previous research on stingrays, which are relatives of sharks, suggests they can pass on environmental contamination to developing fetuses.

“Adults may have better developed immune systems or enzyme systems to metabolize some of those things, but a developing fetus may not,” Lowe says. “We really don’t know what the developmental impacts could be.”

Mendes Saggioro plans to continue drug testing sharks in the area and to expand this to rays that live in the nearby estuary to see how far the contamination extends. He and his team also want to look at cocaine concentrations in migratory fish that spend less of their life near coastlines.

While researchers unravel the consequences of cocaine-contaminated sharks, there are two major takeaways. One comes from Mendes Saggioro and Hauser-Davis: don’t eat sharks because the animals are both overfished and full of compounds you don’t want in your body.

David Shiffman, a marine conservation biologist at Arizona State University, notes the other takeaway, which focuses on the health of the sharks themselves: “Please don’t dump your trash, including illegal drugs, into the water,” he says.

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A large clinical trial in South Africa and Uganda has shown that a twice-yearly injection of a new pre-exposure prophylaxis drug gives young women total protection from HIV infection.

The trial tested whether the six-month injection of lenacapavir would provide better protection against HIV infection than two other drugs, both daily pills. All three medications are pre-exposure prophylaxis (or PrEP) drugs.

Physician-scientist Linda-Gail Bekker, principal investigator for the South African part of the study, tells Nadine Dreyer what makes this breakthrough so significant and what to expect next.

Tell us about the trial and what it set out to achieve

The Purpose 1 trial with 5,000 participants took place at three sites in Uganda and 25 sites in South Africa to test the efficacy of lenacapavir and two other drugs.

Lenacapavir (Len LA) is a fusion capside inhibitor. It interferes with the HIV capsid, a protein shell that protects HIV’s genetic material and enzymes needed for replication. It is administered just under the skin, once every six months.

The randomized controlled trial, sponsored by the drug developers Gilead Sciences, tested several things.

The first was whether a six-monthly injection of lenacapavir was safe and would provide better protection against HIV infection as PrEP for women between the ages of 16 and 25 years than Truvada F/TDF, a daily PrEP pill in wide use that has been available for more than a decade.

Secondly, the trial also tested whether Descovy F/TAF, a newer daily pill, was as effective as F/TDF. The newer F/TAF has superior pharmacokinetic properties to F/TDF. Pharmacokinetic refers to the movement of a drug into, through, and out of the body. F/TAF is a smaller pill and is in use among men and transgender women in high-income countries.

The trial had three arms. Young women were randomly assigned to one of the arms in a 2:2:1 ratio (Len LA: F/TAF oral: F/TDF oral) in a double blinded fashion. This means neither the participants nor the researchers knew which treatment participants were receiving until the clinical trial was over.

In eastern and southern Africa, young women are the population who bear the brunt of new HIV infections. They also find a daily PrEP regimen challenging to maintain, for a number of social and structural reasons.

During the randomized phase of the trial, none of the 2,134 women who received lenacapavir contracted HIV. There was 100 percent efficiency.

By comparison, 16 of the 1,068 women (or 1.5%) who took Truvada (F/TDF) and 39 of 2,136 (1.8%) who received Descovy (F/TAF) contracted the HIV virus.

The results at a recent independent data safety monitoring board review led to the recommendation that the trial’s “blinded” phase should be stopped, and all participants should be offered a choice of PrEP.

This board is an independent committee of experts who are put in place at the start of a clinical trial. They see the unblinded data at stipulated times during the trial to monitor progress and safety. They ensure that a trial does not continue if there is harm or a clear benefit in one arm over others.

What is the significance of these trials?

This breakthrough gives great hope that we have a proven, highly effective
prevention tool to protect people from HIV.

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Most people probably don’t think of mathematics when they hear “busy beavers.” But these eager little animals symbolize one of the most amazing concepts of the knotty field: not everything can be calculated, no matter how hard you try (or how busy of a beaver you are). The busy beaver function is the first example of a noncalculable mathematical expression. The function itself is easy to explain: it refers to the largest number of steps a computer program can take before stopping if the program has n states, where states refer to the complexity of the problem. But its values, called BB(n), will never be known for all quantities of n. Mathematicians and theoretical computer scientists have long pondered at which n mathematical tools fail: Where exactly is the limit of what can be calculated?

For more than 40 years, many experts assumed that BB(5) could lie beyond this limit of computability and would therefore be unattainable. But now an international collaborative project called the Busy Beaver Challenge has succeeded in determining the value of BB(5), and its calculation was formally verified by a computer-aided proof assistant. According to the new research, the magic number for BB(5) is 47,176,870, meaning that a program with five states can take a maximum of 47,176,870 steps before halting—or it will never halt at all. The last big “busy beaver” achievement occurred in 1983, when the late computer scientist Allen Brady proved that BB(4) equals 107.

Busy beavers are deeply rooted in the foundations of mathematics. In the 20th century, many experts dreamed of finding a foundation on which all mathematical truths could be proven. But in 1931 logician Kurt Gödel, aged just 25 at the time, dashed their hopes. He proved that there are inevitably unprovable statements in mathematics—statements that can neither be proven nor disproven. Initially, experts hoped this was an abstract result with no significant applications. But they were wrong.

Mathematicians now know of many unprovable problems. One of the first examples is the halting problem, which deals with the execution of algorithms. In the 1930s Alan Turing figured out that there is no algorithm that can predict whether a computer program with certain inputs will run forever or will stop at some point. At the time, Turing was working on the theoretical model of such a computer, now called the Turing machine. This theoretical machine consists of an infinitely long tape labeled with 1’s and 0’s and a head that reads the tape, describes it, and shifts it to the right or left. Such a machine can theoretically perform any kind of calculation—just like a computer.

Suppose you want to program a Turing machine to multiply two numbers. The 1’s and 0’s on the tape then correspond to the two numbers. Before the calculation, you define a certain number of states, or rules, for the machine, such as A, B, C, and D, as well as HALT. These states determine how the Turing machine acts with each input. For example: If the five-state machine reads a 1 on the tape in state A, it overwrites this with a 0, moves the tape to the left, and switches to state C. Two instructions are therefore required for each of the states A to D, depending on whether the machine finds a 1 or a 0 on the tape. Under certain circumstances (for example, state B when reading a 1), the machine can switch to the HALT state. In this case, the Turing machine stops, and the calculation is complete. The result would then be the numbers on the tape at that point.

As Turing proved, there is no Turing machine that can determine, for all possible configurations of Turing machines, meaning all algorithms, whether they will stop at some point. And this is where the industrious beavers come into play.

The Halting Problem

In the “busy beaver game,” developed in 1962, Hungarian mathematician Tibor Radó searched for the most diligent Turing machine of a certain size: What is the maximum number of calculation steps that a Turing machine with n states, which comes to a halt at some point, can perform?

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Your kids might hate your corny jokes, but those same bad jokes might be the key to making them love you forever.

OK, that might be a slight exaggeration. But a fascinating new study recently published in the journal PLOS One indicates that using humor in our parenting might have a bigger impact than we realize.

The authors of the pilot study found that while there was a lot of existing research on how parents can use play in their child-rearing efforts, there was very little information about humor, specifically.

So, they asked a selection of adult respondents about if and how their own parents used humor at home and how those people viewed those childhood experiences years later.

The results were decisive. Funny parents were viewed more positively, had stronger relationships with their adult kids, and were perceived as better and more effective parents.

Before you go draining your life savings to enroll in clown college, it’s worth noting that the study is only a starting point. It didn’t feature a large or diverse group of respondents (a majority were white males) and it relied on self-reporting many years after the fact.

Still, the findings offer a really reassuring and optimistic view of parenting. Along with cooking, cleaning, and doing endless laundry—plus those little things like being a good person and role model—taking time to make your kids laugh is always a worthwhile task.

Why Humor Is an Important Parenting Tool

Laughing together as a family is obviously fun, but the researchers were particularly interested in humor as a tool and how it can be used in everyday parenting situations.

“Notably, humor can induce frameshifts (i.e., changes in perspective) that alter how we interpret an event or response, and thereby open new possibilities for children and parents alike,” the study says.1

In other words, joking around can change the dynamic of situations that are headed for conflict in a way that few other parenting techniques can.

One example in the study notes how, when all efforts to soothe a toddler tantrum fail, a parent might try playfully throwing a tantrum of their own. It may get their child laughing and feeling better, with the added bonus of helping to prevent the parent from growing overly frustrated.1

I absolutely love this idea. I’m naturally extremely silly and goofy with my kids, especially in high-pressure moments. I can tell when I’m getting nowhere with a lesson or admonishment and it’s time to break the tension with a joke or a game. But I had never considered using humor as an opportunity to reframe my own reaction to a situation when I feel myself losing patience or getting frustrated.

It may also have lasting effects too. Reena Patel, LEP, BCBA, positive psychologist and parenting expert, says that learning how to joke around in stressful scenarios from watching you is a highly beneficial lifelong skill for kids to pick up. “It can really help kids’ perspective and help with seeing things in a positive light,” says Patel.

Easy Tips To Add Humor To Parenting

But what if being silly or goofy with the kids doesn’t come as easy to you? What if you’re…not funny?

Patel says that playing is often close enough, if you’re a total beginner to the comedy game. “Get on your child’s level and just purely enjoy time with them,” she says. “The laughs will come when you are playing and enjoying time together.”

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