Less Snowy Winters

Winter might mean snowball fights in many places. But this might not be the case for much longer. While many people around the world are currently experiencing heavy snowfall, Earth is getting less snowy — a trend that isn’t temporary. That’s because the planet is heating up and winter is warming faster than any other season in America. The water falling to earth in winter is more commonly falling as raindrops than snow.

With water falling as rain instead of snow, and then freezing, some animals may struggle to feed on grass on frozen ground. Species with white coats could be at higher risk of being eaten as food, while polar bears may have fewer options to build their snowy habitations. Not every species can adapt or move to snowier climates, which may cause the extinction of some animals.

As air temperatures warm, trees release water into the atmosphere through a process called evapotranspiration, loss of water from the soil. When there hasn’t been much snow, the soil can’t replace lost moisture, and forests experience more heat stress, making severe wildfires more likely. “When a fire does spark, it runs away as fast as possible and burns as much area as it can,” says Andrew Schwartz, lead scientist at UC Berkeley’s Central Sierra Snow Laboratory.

For humans, less snowfall is “problematic because snow supplies so much of our water,” says Schwartz. About 1.9 billion people rely on snowpacks and big mass of ice for drinking water. Snow on the mountains acts like a natural lake used to store water. As it slowly melts into streams, snow supplies water through spring and summer, while rain flows immediately downstream and can be wasted. “It becomes more difficult to manage our water when we have these wild swings from year to year,” says Schwartz.

7 . Why Are You Still Coughing?

Have you caught a cold recently — but can’t get rid of the cough? You’re not alone. The symptom can stick around for weeks after our bodies have cleared a virus. Michael Shiloh, a physician specializing in infectious disease research at UT Southwestern Medical Center, says coughing patients often report that they were sick as many as eight weeks prior to seeing him. He says, “    1    ”

The United States saw a sharp rise in cases of influenza in late 2023 that’s dragged on into 2024. And though positive tests for the illness have leveled off or decreased countrywide over the past weeks, the number of people seeking healthcare for respiratory (呼吸的) diseases is still elevated across much of the U.S.     2     But research on how infections affect nerves in the airway is revealing new clues.

Coughing is an important reaction that protects the airway from dangers like water or bits of mis-swallowed food, says doctor and researcher Lorcan McGarvey of Queen’s University Belfast.     3     These nerves are decorated with receptor (受体) proteins that react to everything from cold air to hot pepper. When a stimulus causes those receptors, nerves send signals to the brain that we experience as the urge to cough.

While it may seem obvious that coughing is meant to clear our throats, it’s also possible that viruses cause the reaction to help themselves spread.     4     And if we do ultimately cough to clear out our airway during an infection, that still wouldn’t explain what exactly our nerves sense during an infection that causes a cough.

“We don’t know,” says electrophysiologist Thomas Taylor-Clark of the University of South Florida. “But what we can say is that we do know some things, one being that viruses cause infection.”

8 . I was sitting in my high school classroom, nervously tapping my pencil against the desk as I awaited the start of the English exam.

As the clock struck, signaling the beginning of the exam, my heart began to race. I opened the exam booklet and scanned the questions, and I felt a wave of panic over me. The questions seemed foreign, and the topics unfamiliar. In a state of panic, I hurriedly wrote down my answers, hoping that somehow, by some stroke of luck, they would be correct. But as the minutes went by, I realized I couldn’t seem to make sense of the questions before me. As the final bell rang, I handed in my paper with a heavy heart.

In the days that followed, I couldn’t shake the feeling of failure that hung over me like a dark cloud. I replayed the exam over and over in my mind, analyzing every question, every answer, searching for clues as to where I had gone wrong.

But in the depression, a realization began to dawn on me — I had failed, yes, but I had also learned valuable lessons along the way. Armed with this newfound wisdom, I ensured that I would do better next time. I threw myself into my studies with renewed determination, devouring books and practicing past exams with an eagerness I had never known before.

When the time came to retake the exam, I was ready. I approached each question with confidence and clarity, drawing upon the lessons I had learned from my previous missteps.

When the results were announced, I held my breath as I scanned the list of names. And there it was — my name, shining brightly among the list of successful candidates. At that moment, all the hard work, all the late nights and early mornings, were worth it.

And as I look back on that sunny afternoon in the high school classroom, I am grateful for the lessons it taught me, and the person it helped me become.

9 . Although many over-processed foods can satisfy the desire for sweet, fatty, salty foods, research suggests these items are particularly bad for the heart and brain, with mood and cognition taking a hit.

The most recent research looking at the _______ of over-processed food found the most far-reaching results. Researchers _______ direct links between higher consumption of over-processed foods and a greater risk of many health issues.

These results are _______ earlier studies. Diets high in these foods were linked to greater risk of depression and anxiety, according to an analysis published in the journal Nutrients. In one of these studies, risk rose from _______ just 33 percent of calories from over-processed food. A separate study found that taking in just 20 percent of calories from these foods was linked to a 28 percent faster rate of cognitive _______ compared with people who ate less processed food.

Also _______ is a study tracking about half a million people living in England, Scotland, and Wales that found the risk of dementia (痴呆) went up by 25 percent for every 10 percent increase in over-processed food. While the exact cause-and-effect relationship is still unknown, the strongest evidence from prospective studies _______ the idea that eating high amounts of over-processed foods increases the risk of depression in the future.

It is common knowledge that eating too much salt or sugar is linked to high blood pressure and Type 2 diabetes. What the public may not appreciate, _______, is that all these conditions affect the brain by raising the risk for dementia. _______ such as certain artificial sweeteners may also disturb the production and release of brain chemicals, such as dopamine, which can negatively affect mental and emotional ________.

Another problem with over-processed foods is that they might be addictive. Over-processed foods have more in common with a(n) ________ than foods by Mother Nature. Humans have evolved to respond to foods that are sweet, fatty, and high in calories. For most of human existence this helped us ________. But in nature, foods are ________ modestly high in sugar — like berries — or high in fat, like nuts. You don’t find foods high in both sugar and fat. That’s a distinctive ________ of over-processed foods. Add in salt, artificial flavorings and bright colors, and our brain simply ________ these foods.

How Long Is a Second?

The length of a second depends on how you’re measuring it. There are 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute — so surely a second is 1/86400, of a day, right? Well, it turns out that     1     time isn’t that simple.

“The second was     2     based on the length of the day,” Peter Whibberley, a senior scientist at the National Physical Laboratory in the U.K., told Live Science. “People observed the sun passing overhead and started measuring its     3     using sundials (日晷). However, sundials have a few disadvantages. Aside from the obvious problem of not being able to read a sundial when the sun isn’t visible, relying on Earth’s daily turning is surprisingly inaccurate. “The turning is not precisely     4    ,” Whibberley said. “The Earth speeds up and slows down over time.” So how can we precisely measure time if using the length of a day is so unreliable?

In the 16^th century, people turned to technological solutions to this problem, and the first recognizable mechanical clocks began to     5    . The earliest mechanical clocks, which were designed to click at a specific frequency, averaged over the     6     of a year.

By around 1940, quartz crystal clocks (石英钟) had become the new gold standard. However, problems arose, and this was where atomic clocks came in. “Atoms exist only in particular energy states and can only change from one state to another by     7     or giving out a fixed amount of energy,” Whibberley explained. “That energy     8     to a precise frequency, so you can use that frequency as a reference for time keeping.” The astronomical second continued to vary. Every few years, scientists must add a second to allow Earth’s slowing turning to keep up with atomic time.

In fact, scientists are discussing whether it’s time to redefine the second again. But while several important questions still need to be answered before this     9    , it’s clear that the strictly correct definition of a second is     10     to change.