Human brains begin growing and developing at a very young age. They learn from the simplest experiences, which enable your children to be aware of the world. There's no denying that outdoor play helps a lot!

Times when children have to wait for their turns on playground equipment and following the playground rules by sharing, all these form components of a healthy social-emotional development. Young children develop their social-emotional skills through practice and small steps over time.

As parents or caregivers, it is fairly simple to support your child's social-emotional skills. Acts like holding him, touching him, and speaking to him and giving him loving care and attention are all helping factors. When you allow them freedom to play, it is important to follow their interests in helping build their social-emotional skills.

Difficulties in social-emotional skills can often lead to children having trouble when playing with other children. Becoming easily angry or not empathizing (理解) with other children are all signs that may point in this direction. This can in turn lead to them not empathizing with the needs of other children.

    As for the development of cognitive (认知的) skills, these develop through practice and opportunity over time. And while some cognitive skills may be genetic, most are learned through real life situations. In other words, learning and thinking skills can be improved through experiences.

    To enable them to learn, it is important that we are mindful of what our children are interested in. And this realization is only set in place once the child is given enough room and time to grow and explore.

    Depriving children of such experiences can mean that they might struggle with higher- level thinking skills. And while it is normal to keep them safe, we forget that by rushing them and cutting down on play time, we're actually causing more harm than good.

    A black hole is created when a large star burns out. Like our sun, stars are unbelievably hot furnaces(熔炉) that burn their own matter as fuel. When most of the fuel is used up, the star begins to die.

    The death of a star is not a quiet event. First there is a huge explosion. As its outer layer is blasted off into space, the dying star shines as brightly as a billion suns.

    After the explosion, gravity pulls in what's left of the star. As the outside of the star sinks toward the center, the star gets smaller and smaller. The material the star is made of becomes tightly packed together. A star is so solid that a teaspoon of matter from it weighs billion of pounds.

    The more the star shrinks(收缩), the stronger the gravity inside it becomes. Soon the star is very tiny, and the gravity pulling it in is unbelievably strong. In fact, the gravity is so strong that it even pulls light into the star! Since all the light is pulled in, none can go out. The star becomes black when there is no light. Then a black hole is born!

    That's what we know about black holes. What we don't know is this: What happens inside a black hole after the star has been squeezed into a tiny ball? Does it keep getting smaller and smaller forever? Such a possibility is hard to imagine.

    But if the black hole doesn't keep shrinking, what happens to it? Some scientists think black holes are like doorways to another world. They say that as the star disappears from our universe, it goes into another universe. In other words a black hole in our universe could turn into a "white hole" in a different universe. As the black hole swallows(吞噬) light, the white hole shines brightly--somewhere else. But where? A different place, perhaps, or a different time--many years in the past or future.

    Could you travel through a black hole? Right now, no. Nothing we know of could go into a black hole without being crushed(挤压). So far the time being, black hole must remain a mystery.

    Black holes are a mystery--but that hasn't stopped scientists from dreaming about them. One scientist suggested that in the future we might make use of the power of black holes. They would supply all of Earth's energy needs, with plenty to spare. Another scientist wondered if a black hole could some day be used to swallow earthly waste--a sort of huge waste disposal(处理) in the sky!

    LastPass Password strength has been a topic about the Internet lately. I have seen lots of clever methods for creating and remembering strong passwords. Some are better than others, but in my opinion, none are enough. Here's the problem: It doesn't matter how strong your passwords are if you use the same one on multiple sites. All it takes is for a site to get hacked, like Gawker media, or even Sony did, and now your super-strong password has been stolen, and every site on which you used that password has been accessed.

    Enter LastPass. It's not the only password manager out there, but I like it the best. You create ONE strong password that you have to memorize and use it to access you LastPass database. The LastPass database is stored online, on LastPass's services. LastPass recognizes the site you're on and automatically logs you in (after, optionally, asking you to re-enter your master password). LastPass also has automatic form fill and automatic password generation. This means that you can have a different, unique, very strong password for every site you log into, but you only have to remember one master password. It's the best of both worlds.

    One argument against LastPass is that if their database is attacked, then all of your sites are in danger, and that's true, but if their entire line of work is keeping that information safe, I'm willing to take that chance. The alternative is rolling dice（掷骰子） or picking phrases to create passwords, writing all of them down on a piece of paper or something, and then having to manually type them in when I go to a site. A terrible mess.

    There is a free version of LastPass, with some additional features unlocked if you pay a $12 a year subscription.

    Why can some people sleep through noises like a honking car or flushing toilet, while others are awakened by the lightest sound?

    To find the answer, sleep researchers at Massachusetts General Hospital conducted an unusual study of 12 self-described deep sleepers. After tests confirmed that the healthy volunteers were solid sleepers, they took part in a three-night study in the university's sleep laboratory. The participants spent the night in a big and comfortable room. But the room also included four speakers positioned near the top of the bed.

    During the night, the deep sleepers were subjected to 14 different recorded sounds, like street traffic, toilets flushing, and an airplane flying overhead. Next door, the researchers monitored their sleep patterns and brain waves.

    As expected, all of the participants slept relatively well, but there were differences in how they responded to the noisy interruptions. Some of the sleepers didn't wake up even when a sound was blasted at 70 decibels（分贝）; others were awakened by sounds at 40 or 50 decibels.

    The researchers discovered that the difference in a sleeper's reaction to noise could be predicted by the level of brain activity called "sleep spindles（纺锤体）". A sleep spindle is a burst of high-frequency brain activity coming from deep inside the brain during sleep. The source of the spindles is the thalamus（丘脑）, a part of the brain that sends sensory information to the rest of the cortex（皮层）.

    Before the study, the Massachusetts researchers theorized that the spindles are the brain's way of preventing sensory information from passing through the thalamus and waking the rest of the brain during sleep. They found that sleepers who experienced the most sleep spindles during the night were also the soundest sleepers and were least likely to be awakened by noise.

    Scientists already know that most people become lighter sleepers with age, most likely because older people experience less "slow wave sleep", which is the deepest stage of sleep. People also produce fewer sleep spindles as they age. But even when controlling for the stage of sleep a person was in, the number of sleep spindles still predicted their risk for awakening because of noise.

    More research is needed, but the findings suggest that a better understanding of sleep spindles could lead to new behavioral or drug therapies for people with sleep disorders. For example, future studies may try to determine whether diet, exercise or other behaviors may influence the number of sleep spindles a person produces during the night.

    We can make mistakes at any age. Some mistakes we make are about money. But most mistakes are about people. "Did Jerry really care when I broke up with Helen?" "When I got that great job, did Jim, as a friend, really feel good about it?" "And was Paul friendly just because I had a car?" When we look back, doubts like these can make us feel bad. But when we look back, it's too late.

    Why do we go wrong about our friends or our enemies? Sometimes what people say hides their real meaning. And if we don't really listen we miss the feeling behind the words. Suppose someone tells you, "You're a lucky dog." That's being friendly. But "lucky dog"? There's a bit of envy in those words. Maybe he doesn't see it himself. But bringing in the "dog" bit puts you down a little. What he may be saying is that he doesn't think you deserve your luck.

    "Just think of all the things you have to be thankful for" is another noise that says one thing and means another. It could mean that the speaker is trying to get you to see your problem as part of your life as a whole. But is he? Wrapped up in this phrase is the thought that your problem isn't important. It's telling you to think of all the starving people in the world when you haven't got a date for Saturday night.

    How can you tell the real meaning behind someone's words? One way is to take a good look at the person talking. Do his words fit the way he looks? Does what he says agree with the tone of voice? His posture(姿态)? The look in his eyes? Stop and think. The minute you spend thinking about the real meaning of what people say to you may save another mistake.