Do you often feel lonely? What do you do when you feel that way? Hide yourself away and spend your time reading, watching TV or walking around?

You might think that feeling lonely is just like feeling happy, sad or scared — that it's just one of your various moods. That is true. However, if you let yourself be lonely for too long without dealing with it, you could be making a serious mistake.

    Doctors have known for some time that feeling lonely is bad for the mind. It can lead to mental health problems such as depression, stress and reduce confidence. “Being lonely means not feeling connected or cared for, but it's not about being mentally alone,” Lisa Jaremka, scientist from Ohio State University, US, told Live Science in January. And there's growing evidence that not having friends is connected with physical illness as well.

    In 2006, for example, scientists studied 2,800 women who had cancer. They found that those who had few friends or family were five times more likely to die of their disease than women with many social contacts. Also, even healthy people had a better chance of falling ill if they felt left out by others, according to the BBC.

    The results have scientists thinking that loneliness might hurt the immune system(免疫系统), which protects the body from diseases.

    Hoping to prove this theory, Jaremka and her research team put volunteers(志愿者) through a stress test. During the test, volunteers were asked to make an unprepared speech in front of a group of stony-faced people. The researchers found that volunteers who said they were lonely in their daily lives felt more stress during the test. And their blood samples showed that all the stress had managed to cause harmful changes to their immune system.

     “Loneliness has been thought of in many ways as a chronic stressor(慢性增压器) — a socially painful situation that can last for quite a long time, ” explained Jaremka, who led the study.

    The number of people suffering from loneliness is increasing all over the world. However, solving the problem is easier said than done. It won't work to just “tell anyone to go out and find someone to love you”, said Jaremka. “We need to create support networks.”

    Researchers in the psychology department at the University of California at Los Angeles (UCLA) have discovered a major difference in the way men and women respond to stress.This difference may explain why men are more likely to suffer from stress related disorders.

    Until now，psychological research has maintained that both men and women have the same “fightorflight” reaction to stress.In other words，individuals either react with aggressive behavior，such as verbal or physical conflict (“fight”)，or they react by withdrawing from the stressful situation (“flight”)．However，the UCLA research team found that men and women have quite different biological and behavioral responses to stress.While men often react to stress in the fightorflight response，women often have another kind of reaction which could be called “tend and befriend.” That is，they often react to stressful conditions by protecting and nurturing their young (“tend”)，and by looking for social contact and support from others—especially other females (“befriend”)．

    Scientists have long known that in the fightorflight reaction to stress，an important role is played by certain hormones(激素) released by the body.The UCLA research team suggests that the female tendorbefriend response is also based on a hormone.This hormone，called oxytocin，has been studied in the context of childbirth，but now it is being studied for its role in the response of both men and women to stress.The principal investigator，Dr.Shelley E．Taylor，explained that “animals and people with high levels of oxytocin are calmer，more relaxed，more social，and less anxious.” While men also secrete(分泌) oxytocin，its effects are reduced by male hormones.

    In terms of everyday behavior，the UCLA study found that women are far more likely than men to seek social contact when they are feeling stressed.They may phone relatives or friends，or ask directions if they are lost.

    The study also showed how fathers and mothers responded differently when they came home to their family after a stressful day at work.The typical father wanted to be left alone to enjoy some peace and quiet.For a typical mother，coping with a bad day at work meant focusing her attention on her children and their needs.

    The differences in responding to stress may explain the fact that women have lower frequency of stressrelated disorders such as high blood pressure or aggressive behavior.The tendandbefriend regulatory(调节的) system may protect women against stress，and this may explain why women on average live longer than men.

    Pat O'Burke was a poor Irishman with a large family, and one morning, waking up very early from cold and hunger, he decided to go shooting in a wood near his cottage. The wood belonged to Lord Northwood, a rich gentleman, Pat had no right to go there, but in it there were swarms of rabbits and flocks of birds that were good to eat, and Pat determined to take the risk. Suddenly he saw the owner, with a group of friends, coming towards him in the wood. There was a look of anger on Lord Northwood's face as he caught sight of the gun in Pat's hands. Pat's heart sank with fear, but he saw there was no hope of escape, so he walked boldly(大胆) up to the company and said to Lord Northwood, “Good morning, sir, and what has brought you out so early this morning?” Lord Northwood, rather surprised, said he and his Mends were taking a little exercise to get an appetite(食欲) for their breakfast. Then, looking at Pat with suspicion(怀疑), he said, “but why are you out so early in the morning?” “Well, sir” said Pat, “I just came out to see if I could get a breakfast for my appetite.” The whole crowed burst into laughter at Pat's ready wit(机智), and with a smile Lord Northwood walked on, leaving Pat to try his luck with the rabbits.

    Sharpshooters refer to those who are skilled at firing a gun and accurately hitting what they are aiming at. However, some fish are also called amazing sharpshooters. People wonder how they hit their targets without using tools? By spitting! The fish shoot so accurately that they rarely miss their target.

    These amazing fish are archerfish (印度射水鱼).There are several different types of archerfish living in Southeast Asia. They spit at their dinner to catch it. To catch dinner, a fish first sets itself in a certain place, for example just below the surface of the water. It puts the tip of its mouth so it barely breaks through the water. Then, the fish waits for an unsuspecting insect to land on a leaf or branch hanging over the water.

    When an unsuspecting, or unknowing insect lands, the fish attacks. The fish squeezes its gill (腮)covers very rapidly, which forces water into the fish's mouth. In the roof of its mouth the fish has a groove (槽）. The fish forms the small groove and its tongue into a narrow tube by pressing its tongue up against its groove. The water forced into the fish's mouth is forcefully pushed out of the fish's mouth through the tube. Archerfish have been known to send a stream up to 5 meters (16 feet). However, archerfish can only shoot insects up to 1-2 meters (3-6 feet) away due to their limited accuracy.

    When the unsuspecting insect is hit with a sudden stream of water, it is knocked into or falls into the water. Once in the water, the insect becomes dinner. Archerfish learn how to spit when they are young. They get more accurate with practice. Adult archerfish rarely miss.

    Within a meter, archerfish will often spring out of the water and grab an insect in their mouths.

    In some countries where racial prejudice is acute, violence has so come to be taken for granted as a means of solving differences that it is not even questioned. There are countries where the white man imposes his rule by brute force; there are countries where the black man protests by setting fire to cities and by looting and pillaging. Important people on both sides, who would in other respects appear to be reasonable men, get up and calmly argue in favor of violence—as if it were a legitimate solution, like any other. What is really frightening, what really fills you with despair, is the realization that when it comes to the crunch (关键时刻), we have made no actual progress at all. We may wear collars and ties instead of war-paint, but our instinct remain basically unchanged. The whole of the recorded history of the human race, that tedious documentation of violence, has taught us absolutely nothing. We have still not learned that violence never solves a problem but makes it more acute. The sheer horror, the bloodshed (流血), the suffering mean nothing. No solution ever comes to light the morning after when we dismally contemplate the smoking ruins and wonder what hit us.

    The truly reasonable men who know where the solutions lie are finding it harder and harder to get a hearing. They are despised mistrusted and even persuaded by their own kind because they advocate such apparently outrageous things as law enforcement (执行). If half the energy that goes into violent acts were put to good use, if our efforts were directed at cleaning up the slums and ghettos, at improving living standards and providing education and employment for all, we would have gone a long way to arriving at a solution. Our strength is sapped by having to mop to the mess that violence leaves in its wake. In a well-directed effort, it would not be impossible to fulfill the ideals of a stable social programme. The benefits that can be derived from constructive solutions are everywhere apparent in the world around us. Genuine and lasting solutions are always possible, providing we work within the framework of the law.

    Before we can even begin to contemplate peaceful co-existence between the races, we must appreciate each other's problems. And to do this, we must learn about them: it is a simple exercise in communication, in exchange information. "Talk, talk, talk" the advocates of violence say, "all you ever do is talk, and we are none the wiser." It's rather like the story of the famous barrister who painstakingly explained his case to the judge. After listening to a lengthy argument, the judge complained that after all this talk, he was none the wiser. "Possibly, my lord," the barrister replied, "none the wiser, but surely far better informed." Knowledge is the necessary prerequisite to wisdom: the knowledge that violence creates the evils it pretends to solve.

    Shark attacks not only disturb beach activities, but can affect associated tourist industries. Shark nets are a common solution to preventing shark attacks on beaches, but they cause dangers to sea ecosystems.

    Seeking a cost-effective way to monitor beach safety over large areas, we have developed a system called Shark Spotter. It combines artificial intelligence (AI), computing power, and drone (无人机) technology to identify and warn lifesavers to sharks near swimmers. The project is a cooperation between the University of Technology Sydney and The Ripper Group, which is pioneering the use of drones—called "Westpac Little Ripper Lifesavers"—in the search and rescue movement in Australia.

    SharkSpotter can detect sharks and other potential threats using real-time aerial imagery. The system analyses video from a camera attached to a drone to monitor beaches for sharks, send warnings, and conduct rescues. Developed with techniques known as "deep learning", the Shark Spotter system receives imagery from the drone camera and attempts to identify all objects in the scene. Once certain objects are detected, they are put into one of 16 categories: shark, whale, dolphin, rays, different types of boats, surfers, and swimmers.

    If a shark is detected, Shark Spotter provides both a visual sign on the computer screen and an audible warning to the operator. The operator confirms the warning and sends text messages from the Shark Spotter system to the Surf Life Savers for further action. In an emergency, the drone is equipped with a lifesaving flotation pod (漂浮仓) together with an electronic shark repellent (驱逐装置) that can be dropped into the water in cases where swimmers are in severe trouble, trapped in a rip, or if there are sharks close by.

    In January 2018, the Westpac Little Ripper Lifesavers was used to rescue two young swimmers caught in a rip at Lennox Head, NSW. The drone flew down the beach some 800 meters from the lifeguard station, and a lifesaving flotation pod was dropped from the drone. The complete rescue operation took 70 seconds.

    We believe Shark Spotter is a win-win for both marine life and beachgoers. This unique technology combines dynamic video image processing AI and advanced drone technology to creatively deal with the global challenge of ensuring safe beaches, protecting environments, and promoting tourism.