【推荐1】Many animals depend upon sound to find food, detect predators and communicate with one another. These species understandably suffer when loud motorways cut through their habitats. Some deal with this problem by singing more loudly, some change the timing of their calls to occur when fewer people are driving, others just move to quieter places.

It has always been assumed that noise is a problem unique to animals. But a new study by Ali Akbar Ghotbi-Ravandi, a botanist at Shahid Beheshti University in Tehran, has revealed that plants suffer too.

That plants can be affected indirectly by noise pollution has never been in doubt. Since most flowering species depend upon pollinators and most fruit-bearing species need animals to disperse their seeds, it is obvious that if these animal partners are harmed by noise then their botanical plants will do badly, too. What has remained unknown is whether or not plants themselves suffer directly from noise pollution.

Sounds are pressure waves transmitted through gases, liquids and solids. Scientists have previously predicted that plants may be able to sense these waves as they are struck by them. A number of experiments have confirmed this in recent years — plants attacked with ultrasound in the lab have shown a range of hurtful responses, including the expression of stress-related genes, underdeveloped growth and reduced germination (发芽) of seeds.

Working with a team of colleagues, Dr. Ghotbi-Ravandi grew two species in his lab that are commonly found in urban environments. The plants were grown from seeds and allowed to mature for two months in the same space before they were divided into two groups. One group was exposed to 73 decibels (分贝) of traffic noise recorded from a busy motorway in Tehran for 16 hours a day. The other group was left to grow in silence. After 15 days, samples were taken from the youngest fully expanded leaves on every plant in the experiment and studied.

None of the plants exposed to the traffic noise did well. Analysis of their leaves revealed that all of them were suffering. Harmful chemicals in them are indicators of stress in plants and both were found at much higher levels in the plants exposed to the traffic noise. Most notably, levels of the harmful chemicals in the plants exposed to noise were two to three times what they were in those grown in silence. The findings make it clear that the noise of traffic bothers the plants.

【推荐2】History is full of cases where dreams have been a pathway to creativity and discovery. A striking example is provided by Dr. Otto Loewi, a pharmacologist and winner of a Nobel Prize. Loewi had spent years studying the chemical transmission of nerve impulses (脉搏). A great breakthrough in his research came when he dreamed of an experiment three nights in a row. The first two nights he woke up and wrote down the experiment quickly and untidily on paper. But the next morning, he couldn’t tell what the notes meant. On the third night, he got up after having the dream. This time, instead of making notes he went straight to his laboratory and performed the important experiment. Loewi later said that if the experiment had occurred to him while awake he would have rejected it.

Loewi’s experiment gives some insight into using dreams to produce creative solutions. Nervous feelings are reduced while you are dreaming, which may be especially useful in solving problems that require a fresh point of view.

Being able to take advantage of dreams for solving is improved if you “set” yourself before retiring. Before you go to bed, try to think intently about a problem you wish to solve. Bury yourself in the problem by stating it clearly and reviewing all relevant information. Then use the suggestions listed in the previous section to catch your dreams. Although this method is not guaranteed to produce a novel solution or a new insight, it is certain to be an adventure. About half of a group of college students using the method for a week recalled a dream that helped them solve a personal problem.

【推荐3】Do you get nervous thinking about geometry, equations (方程式) or a coming math test? If your answer is “yes”, you are far from alone. Math anxiety has become a common psychological (心理的) condition among students around the world. Students in countries with higher levels of math anxiety tend to achieve lower math grades, according to a study published in the Proceedings of the National Academy of Sciences on Feb. 15.

Math anxiety-a negative emotional reaction to the core subject — causes fear, physical suffering and behavior problems among young pupils, according to a University of Cambridge study. In ordinary life, many people experience some degree of discomfort when meeting with a math problem, ranging from mild tension to strong fear.

Some people also experience physical symptoms such as sweaty palms or a racing heart. They may then try to avoid every situation involving numbers, meaning they are held back from pursuing careers related to this subject, such as science, technology or engineering, according to The Guardian.

Reassurance (慰藉) comes from the fact that those with math anxiety aren’t destined (注定的) to be bad at math. “If a child has math anxiety, don’t assume that they’re not good at math. They may have had a really bad experience with math and there are ways to improve math achievement,” Daniel Ansari, the senior author of the study told The London Free Press. “Students with math anxiety are not cognitively (认知地) disadvantaged.”

Also, there are ways to manage your stress related to math. If you’re feeling stressed before a math exam, it may help to spend a few minutes exploring those feelings before the exam begins. “It’s about making sure you’re interpreting your feelings correctly,” Sian Beilock, a cognitive scientist in the US told the BBC. “Just because you have a fast heartbeat and sweaty palms, that does not necessarily mean you will fail.”

A little math anxiety could be taken as a positive challenge to overcome. Just like many people get stage fright before delivering a speech, this nervous energy can help to motivate, according to Ian Lyons, a psychologist at Georgetown University in the US.