Here is an astonishing and significant fact: Mental work alone can't make us tire. It sounds absurd. But a years ago, scientists tried to find out how long the human brain could labor without reaching a stage of fatigue (疲劳). To the amazement of these scientists, they discovered that blood passing through the brain, when it is active, shows no fatigue at all! If we took a drop of blood from a day laborer, we would find it full of fatigue toxins(毒素) and fatigue products. But if we took blood from the brain of an Albert Einstein, it would show no fatigue toxins at the end of the day.

    So far as the brain is concerned, it can work as well and swiftly at the end of eight or even twelve hours of effort as at the beginning. The brain is totally tireless. So what makes us tired?

    Some scientists declare that most of our fatigue comes from our mental and emotional(情绪的) attitudes. One of England's most outstanding scientists, J.A. Hadfield, says, “The greater part of the fatigue from which we suffer is of mental origin. In fact, fatigue of purely physical origin is rare.” Dr. Brill, a famous American scientist, goes even further. He declares, “One hundred percent of the fatigue of sitting worker in good health is due to emotional problems.”

What kinds of emotions make sitting workers tired? Joy? Satisfaction? No! A feeling of being bored, anger, anxiety, tenseness, worry, a feeling of not being appreciated—those are the emotions that tire sitting workers. Hard work by itself seldom causes fatigue. We get tired because our emotions produce nervousness in the body.

    In the movie Alice in Wonderland, Alice comes across a Cheshire cat and asks the cat which road she should take. The cat responds, “Well, that depends on where you're trying to get to.” Alice replies, “I don't know.” The cat responds, “Then any road will do.”

    You see, knowing where you're going increases your chances dramatically of getting there, and there is no better way of “GETTING THERE” than setting your goals for the upcoming year. Think of your goals as destinations and the action steps as your GPS guiding and directing you. If you are like many other people, for years you have resisted the need to set goals and even laughed at the thought that setting goals and, even more importantly, committing them to writing have positive effects on your life. However, a closer look might convince you that setting goals is a sensible thing to do.

    In 1979, a class of Harvard MBA students was asked: Have you set clear, written goals for your future and made an action plan to accomplish them? The following will astonish you. Only 3 percent of the class had written goals and a plan in place, 13% just had goals, and an amazing 84% had no specific goals at all.

    Ten years later the numbers of the class were interviewed once again and the following results will no doubt give the reason for our setting goals. The findings were that the 13% who had goals were earning, on average, twice as much as the 84% who had no goals at all. And the 3 percent who had clear, written goals with a plan to achieve them were achieving ten times as much as the entire 97% combined.

    Goal setting will increase your chances of arriving successfully at your destination. Remember, always set SMART goals. Goals should be: Specific, Measurable, Attainable, Relevant, and Time-bound!

    If you're new to San Francisco, paying the city a visit, or simply looking for a new playground for you and your dog, here are four of the finest dog parks in San Francisco.

    Corona Heights Dog Park

    Often visited by residents from all over the city because of its nearness to the Randall Museum, Corona Heights Dog Park offers pets and owners breathtaking view after a steep hillside climb, and a fenced dog area that allows dogs to let loose without a leash（狗链）. Owners will also enjoy the playground, tennis courts and basketball courts.

    Dolores Dog Park

    The grounds of Dolores Park once served as camps for those who were left homeless by the 1906 earthquake, but now are often visited by crowds of Mission District people. Four-legged friends can also wander about carefree off-leash while making friends with other members of the doggie community.

    Pine Lake Dog Park

    Famous for its place as a rest stop for hundreds of species of birds to fly to and from warmer climates, Pine Lake Park is also prized by city dogs and their owners for their nice hiking paths, picturesque lake suited for swimming, and off-leash area on the park's west end that lets dogs run free.

    Buena Vista Dog Park

    With a history of 146 years, Buena Vista Park is San Francisco's oldest park. Dogs and owners with plus energy will love burning it on this park's steep paths and winding staircases. Dog owners should have good control over their dogs, as it's quite easy for dogs to get separated when going through Buena Vista's many twists and turns.

    When I was 3 years old, I was found to be deaf in my left ear and have a small problem in my right. Being hard of hearing has been difficult, but I've never lived in a state of self-hating sorrow.

    Imagine being able to shut out all sounds as you lay your head down to sleep by simply rolling over onto one side. That's my reality when I sleep on my “good ear”, and it even makes me feel like a superhero sometimes.

    People call my deaf side my “bad ear”, but when I wear my hearing aid, I have access to a range of features(特征)that some other deaf people don't.

    In cinemas, for example, with one click of a button I can enjoy a whole film as though it were whispered to me from the mouths of the actors.

    Having a hearing aid hasn't always felt good, however.

    On the first day I got my aid, when I was 8, I took it to school for show-and-tell. As I explained how it worked to my classmates, a boy yelled out, “Aren't those for old men?”

    At that moment, I felt different. It took a long time for me to get over that sense of being so unlike my peers(同龄人).

    But it's not just choolkids who can make us deaf and hard-of-hearing people feel like burdens(负担).

    Every video on social media that lacks subtitles, for example, means an entire community of deaf people is unable to enjoy it.

    Completely deaf people are excluded from enjoying many movies too, as subtitles in cinemas are almost impossible to find.

    And with hearing aids costing around $2,500 each, it can be hard for many people to afford to be able to listen to the things that others take for granted.

    As for me, I can listen to music, enjoy films, and catch conversations – I'm lucky.

I'm deaf, but I can still hear everything. I've been blessed with wonderful life experiences.

    Every time your fingers touch your cell phone, they leave behind trace of amounts of chemicals. And each chemical offers clues to you and your activities. By studying them, scientists might be able to piece together a story about your recent life, a new study finds.

    A molecule (分子) is a group of atoms. It is the smallest amounts of some chemicals. Your skin is covered in molecules picked up by everything you touched. With each new thing your skin contacts, you leave behind some small share of what it'd touched earlier.

    Researchers at the University of California, San Diego (UCSD) recently studied such chemical leftovers on the phones of 39 volunteers. The study was led by biochemist Amina Bouslimani. To explore those residues (剩余物), the UCSD team wiped the surface of each volunteer's phone with a cotton swab (药签). The scientists also swabbed each person's right hand. Then the researchers compared the chemicals found on each cell phone.

    The scientists discovered as many of the molecules as they could. They then compared those to a database of chemicals. Pieter Dorrestein, a UCSD pharmaceutical chemist, had helped set up that database a few years earlier, which contains various substances, including spices, caffeine and medicines.

    Traces of everything from hundreds to thousands of different molecules turned up on each phone. The molecules suggested what had been in the body, and what each person had handled before touching the phone. From all these molecules, Bouslimani says, “We could tell if a person is likely female, uses high-end cosmetics (化妆品), colors her hair, drinks coffee, prefers beer over wine or likes spicy food.”

    Police already use molecular analyses to look for traces of explosives or illegal drugs. To date, Dorrestein says, he's never heard of police using phone residues to narrow down behaviour clues to search for a suspect. But detectives might one day use such data to track down someone who left a phone behind at a crime scene.

    I had an old neighbor, a doctor named Gibbs. When Doctor Gibbs wasn't saving lives, he was planting trees. He had some interesting theories about planting trees. He hardly watered his new trees.

    Once I asked why and he told me that watering plants damaged them because it made them grow weaker. He said he had to make things difficult for the trees so that only the strongest could survive. He talked about how watering trees made them develop shallow roots and how, if they were not watered, trees would grow deep roots in search of water.

    So, instead of watering his trees every morning, he'd beat them with a rolled up newspaper. I asked him why he did that, and he said it was to get the trees' attention.

    Doctor Gibbs died a couple of years after I left home. Sometimes I walked by his house and looked at the trees I'd watched him plant 25 years ago. They were tall and strong.

    I planted several trees myself a few years ago. Two years of caring for these trees meant they grew up weakly. Whenever a cold wind blew, my trees trembled. Adversity seemed to benefit Doctor Gibb's trees in ways comfort and ease never could.

    Every night before I go to bed, I check on my two sons. I often pray that their lives will be easy. But lately I've been thinking that it's time to change my prayer. I know my children are going to experience difficulties. There's always a cold wind blowing somewhere. What we need to do is to pray for deep roots, so when the rains fall and the winds blow, we won't be torn apart.