Most people know that listening to music when they are feeling down or depressed can encourage their spirits.

    However studies have also shown that music, especially certain tones can reduce stress. Music can change brainwave patterns, deepen breathing, and bring on a totally stress-free and more open mindset（心态）. Using music to relax when considering a particular problem may not only raise your mood, but also could help you reach that "a-ha"moment and find a solution.

    Music has also been shown not only to make you feel good, but also, to be a great motivator. For example, during exercise, listening to music can keep you going, or get you to exercise more by helping you to ignore negative feelings of tiredness and focus on the pleasurable feelings you get from being absorbed in the music.

    Music is mainly used to record emotion. When we listen to a piece of music we share the artist's feelings on a visceral（本来的）level. That can be sad, and who among us hasn't put on a painful love song to share in the misery after a bad break-up? On the contrary, we can share in the delight of songs of joy and happiness, or any song or piece of music that reminds us of a particular happy time in our past.

    So next time you are feeling down, put on Beethoven' s Ode to Joy, I bet you will feel a lot better about whatever it was that was bothering you!

    While we all try to find happiness, sometimes we still end up feeling low. While most people can control this feeling, low moods can stay with some, leading to depression. About 322 million people suffered from depression in 2015, according to a report by the World Health Organization in February. This is more than 4 percent of the world's population.

    Depression is described by the WHO as a mental disorder. It has several symptoms including sadness, loss of interest and feelings of low self-worth. In severe cases, depression may even lead to suicide.

    The number of people living with depression is increasing. The WHO reported a rise of 18.4 percent between 2005 and 2015. Young people are a group known to suffer with depression. “The pressures on today's youth are like no other generation, perhaps," Dan Chisholm, an official of WHO, told Reuters.

    In China, depression among young people is on the rise, Zhu Zhuohong, a psychology professor with the Chinese Academy of Sciences, told Xinhua News Agency. Competition to outperform others, especially in education, can cause a lot of pressure for Chinese youth.

    Almost 1.2 million Chinese people aged 15 to 24 suffer from depression, according to a report released by British science journal The Lancet in May.

    Luckily, more and more efforts are being made to deal with this problem. This year's World Health Day, held on April 7, will focus on depression. The day will highlight the “Depression: let's talk" campaign. The campaign aims to make sure that people with depression both seek and get help.

    Dutch officials toasted on Tuesday the opening of what is being called the world's first 3D-printed concrete bridge, which is meant to be used by cyclists. There was applause as officials wearing hard hats and workmen's jackets rode over the bridge on their bikes at the opening ceremony in the southeastern town of Gemert.

    "The bridge is not very big, but it was rolled out by a printer which makes it unique," Theo Salet, from the Eindhoven University of Technology, told Dutch broadcaster NOS. Work on printing the bridge, which has some 800 layers, took about three months after starting in June and it is made of pre-stressed concrete, according to the university. "One of the advantages of printing a bridge is that much less concrete is needed than in the conventional technique in which a mould (泥浆) is filled," it said on its website, adding "a printer deposits the concrete only where it is needed."

    The eight-metre (26-foot) bridge crosses a water-filled channel to connect two roads, and it was tested for safety to bear loads of up to two metric tons in cooperation with the BAM Infra Construction company. Although designed for bikes, it could take up to 40 trucks, the designers said "We are looking to the future," said the head of BAM, Marinus Schimmel. "3D printing meant fewer rare resources were needed and there was significantly less waste," he added.

    The Netherlands is among countries, with the United States and China, taking a lead in the cutting-edge technology of 3D printing, using computers and robotics to construct objects and structures from scratch without using much traditional manpower. Last year a Dutch architect unveiled (提示) a unique 3D printer with which he hopes to construct an "endless loop" building. And a Dutch start-up called MX3D has begun printing a stainless-steel bridge, of which a third is already completed. The aim is to finish printing by March and lay the bridge over an Amsterdam canal in the future.