One day as I drove toward my home, I passed the local bus depot. I pulled up as a group of people crossed the road in front of me. As I watched, I noticed a thin, shabbily dressed older lady struggling with a large suitcase.

Witnessing this lady and remembering similar struggles I had experienced in the past when traveling, I pulled up alongside her and leaned over to call out through the open passenger window, "I'm going right into the town," I said. "I can drop you off. That suitcase looks awfully heavy." "Well, all right," she answered. When we got there, she thanked me, "Well, God bless you, lady. No one has ever done me a kindness like that before. I hope someone will do a good turn for you one day." 

Shortly after the encounter with the suitcase lady, I decided to spend a day in the mountains alone. I set off with my dog in my pickup, which was elderly but still serviceable. After driving for nearly two hours, I heard a sudden loud noise and my truck came to a full stop. I found its axle was broken and needed to be towed. In a remote area, with no hope of finding another person, I knew I was in big trouble. Over and over, I blamed my own stupidity for being in a deserted area with no possible chance of help. I hoped that no wandering bear would come to investigate. Or a hungry mountain lion — with babies. My imagination ran riot. I started to panic.

Then faintly, in the distance, came the roar of motorbikes. As they drew nearer, I could see that they were a group of motorcycle riders. "Do you need help, ma'am?" I heard a concerned voice say. The rest is history. My pickup, my dog and I were all transported back to safety. I shall never forget the kindness of the motorcycle riders who stopped. Some people may think it was a happy coincidence, but personally I like to say, it was someone that really did a good turn for me, just as the suitcase lady said.

Numerous studies, including a 2019 review in the journal Annual Research & Review in Biology, have found that both performing and listening to music can have a significant impact on the immune system.

"Certainly music has an impact on the brain, and anxiety and stress impact the immune system," said Andrew Levin, a neurologist at the University of Pittsburgh. Dr. Levin, an amateur trumpet player who performs with several local ensembles, said he's not an expert in the ways music interacts with the brain. But it works for him. "Music is a part of my stress release paradigm," he said. "We know that music can affect brain states, so I don't believe it is much of a stretch to say that music can indirectly affect our physiology, and there is research that supports this notion."

According to a 2013 review in the journal Brain Behavior and Immunity, the emotional and psychological effects of listening to music have direct impacts on biomarkers and hormone levels. There is also general consensus among researchers that listening to music reduces cortisol (皮质醇)levels.

Does the type of music matter? It does. Prior associations and relationships with different types of music affect how your body responds. In general, research indicates that "relaxing music" (i. e. slower pace, peaceful music) is better for calming tense nerves， decreasing blood pressure and breath and settling the heart rate.

Singing a different tune? Potvin, a professor of music therapy at Duquesne University, is skeptical of some of the research linking music with the immune system, questioning whether it's healthy to use music or any other tool to resist anxiety. "The research is superficial, though I don't mean that in a negative way," he said. "I think the information we have is valuable, but we need to go deeper."

Every year, the staff of Popular Science barricades itself in a room to fight. No, this is not some nerdy（书呆子；笨蛋）fight club；it's where we select our Innovation of the Year, the breakthrough that we agree is the most important from the previous 12 months. Below are some examples.

Smart AI Hand

Getting through daily life without the use of one's hand can be quite difficult. While prosthetic（假体的）hands have seen great progress over the years, a new smart prosthetic hand built by BrainRobotics is attractive. The hand is powered by an AI software that allows it to "learn" from its user. The hand is still being tested, but one tester is able to successfully play a song on the piano with the hand. The hand is expected to cost somewhere between $10,000 and $15,000, which is cheaper with the use of 3D printing. It allows each hand to be printed to fit the user.

LightSail 2

The fuel not only takes up space on the spacecraft, but also increases its weight, making it more expensive to launch. But a new type of spacecraft, the LightSail 2 satellite, could end this problem by using the thrust（推力）of photons（光子）bouncing off the spacecraft to sail through space. It takes advantage of the thrust and needs little to no fuel to move through space. LightSail 2 will return to Earth in one year.

Lenovo ThinkPad X1 Fold

Lenovo has introduced a laptop that can be folded up like a book. You can use it anytime and anywhere if you want to. It can also be held like a traditional laptop. It can be held flat, just as you would hold a tablet, or folded like a book when you're lying in bed. It has already been on the market.

Meal Delivery Robot

Food delivery workers have hard jobs. Can robots do the same job? US company Postmates has designed a meal delivery robot called Serve. With two eyes and four wheels, it can drive down footways thanks to the cameras inside it. Still, a human driver can control it remotely if there are any problems. The company has begun testing the robot in some parts of San Francisco, the US.