Here's a selection of festivals for tourists to the United States in summer.

San Francisco Silent Film Festival

    Films at this odd cinematic event have a variety of musical accompaniments, including piano and violin. It includes some classic silent movies. If you want to see them all, you can buy a festival pass.

May 29 to June 1; www.silent film. org

Union Street Festival

    This popular street fair stretches out over six blocks of the city, in the fashionable shopping area of Union Street. This year, there's beer, wine tasting and more separate themes–––fashion, cuisine, tech, locals craft, and health and fitness.

    June 7 to 10: www.unionstreetfestival.com

North Beach Festival

    This is San Francisco's oldest street party, with live entertainment, delicious food and arts and crafts. Situated in the Little Italy district, known for its associations with the “Beat Generation”, festival goers are guaranteed plenty of good Italian food. There is also as the “blessing of the animals”, a San Francisco tradition which takes place at the National Shrine of Saint Francis of Assisi (610 Vallejo Street) at 2 pm on both days of the festival

June 14 to 16; www.sfhorthbeach. org

Stern Grove Festival

    This is the oldest free summer arts festival of its kind in the United States, It includes a wide variety of acts, from the local symphony orchestra to well-known artists such as Smokey Robinson.

Sundays from June 22 to Aug 24; www.sterngrove. org

    Yesterday night, over a dinner with my elder brother's family, a topic of happiness came up. My wife, Marla, a psychologist, was sharing Csikszentmihalyi's concept of “flow” with us. Marla explained that according to the research on flow, people are happiest when they are absorbed in a task that is just challenging enough for them to experience a sense of mastery(熟练).

    A few moments later my brother, Yuri, offered the following opinion: “The first and only, necessary and sufficient factor for happiness is to stop associating happiness with pleasure. The two — happiness and pleasure — have nothing to do with each other.” This morning, with my cup of coffee, I searched through a pile of books on my bedside table and—at the bottom—found a book by Bertrand Russell, I started reading but didn't finish. In it, I found the following thought:

    “The human animal, like others, is adapted to a certain amount of struggle for life, and when by means of great wealth homo sapiens can gratify all his whims (突发奇想) without effort, the mere absence of effort from his life removes an essential ingredient of happiness.”

    The conversation came full circle: people are happiest when they are in a state of flow (Csikszentmihalyi's language )…which is the effortful devotion in a moment…which has nothing to do with pleasure.

    Indeed, as Yuri insisted : happiness–as–pleasure is a myth; the association between happiness and pleasure is nothing but a semantic(语义的) habit; psychologically, the two—happiness and pleasure—are arguably different; and breaking up this association between pleasure and happiness might, in fact, be a powerfully first step in pursuit of happiness.

    As I look back on that exchange, I recall that there was an effort, a struggle to find a common understanding about this seemingly difficult idea—a struggle that made me happy.

    Does stress cause gray hair? Many people believe that tension and stress can cause your hair to lose its color. In fact, it is an old-wives' tale that being upset all the time can result in premature graying. Here is a closer look at this situation and why some believe that this old wives' tale could be true.

    As one ages, the hairs on the head also age. In fact, just about everything on the human body begins to show signs of wear and tear (磨损) after a while. The joints wear and become stiff and skin wears and becomes wrinkled. Hairs on the head grow and eventually die. They are replaced, but in the process something else happens.

    When new hairs are replacing the old ones, the color or pigment (色素) is also added to them. However, as one ages, this pigment becomes less and less available. At first, hairs will have a limited amount of pigment and they will appear to be grayish in color. In time, they will lose all of their pigment and will be white. Many things are known to cause graying, and genetics is a very powerful factor. If one of your parents turns gray at an early age, there is a good chance that you will too. Some people begin the graying process in high school, while others may be over the age of forty.

    Constant worry and tension can have many harmful effects on the human body. It is a known fact that stressful times can cause one to suffer hair loss. It would make sense that if it can cause these problems, perhaps it also may contribute to graying. However, there is no sound evidence to support this.

    On the other hand, many medical professionals believe that there may be a link between graying and a constant state of anxiety or tension. Does stress cause gray hair? There is no scientific evidence to support the theory, but it is best to avoid stressful situations.

    A new officer with the Huntington Park Police patrols (巡逻) local parks 24 hours a day seven days a week. He doesn't need rest, coffee breaks, a salary or medical insurance, and that is because it is a Robocop.

    The main function of the Robocop is to scan and film the surroundings. Besides cameras with night vision that report 360 degrees, it also has a distress button which is located here, so if somebody is to need assistance or they want to contact the communication center, they can do it by way of that distress button. There are people that are monitoring on the other end.

    This newest police employee is self-charging. It's easy to program it and make changes to the software if necessary. Its maintenance (维护) costs are roughly 75 thousand dollars a year. It travels the entire park. It is a programmed path, but the police are able to change the path and adapt it.

    The Robocop can record the license plates (车牌) of passing cars and check them against an online database of stolen cars. It can also help locate a lost iPhone because it is able to determine a smartphone's MAC address. The police can see from the robot if something wrong happens and then come and figure it out.

    The Robocop can't replace its human handlers. The whole goal is to give police more time to do things machines can't do. The police have been having some concerns about safety of the parks and want an extra set of eyes that will help patrol a 24/7.Robocop's creators believe this model known as K5 is best used for providing security at public places like hospitals, parking lots, parks and airports. So far, it seems to be working out just fine.

    "Don't tell anyone". We hear these words when someone tells a secret to us. But it can be hard to keep a secret. We often tend to "spill the beans", even if we regret it later.

    According to Asim Shah, professor in the Menninger Department of Psychiatry and Behavioral Sciences at Baylor College of Medicine, US, keeping a secret may well" become a burden". This is because people often have an "obsessive (强迫性的) and anxious urge to share it with someone".

    An earlier study, led by Anita E. Kelly, a scientist at the University of Notre Dame, US, suggested that keeping a secret could cause stress. People entrusted with secrets can suffer from depression, anxiety, and body aches, reported the Daily Mail.

    But with secrets so often getting out, why do people share them at all? Shah explained that people often feel that it will help them keep a person as a friend. Another reason people share secrets is guilt over keeping it from someone close to them. A sense of distrust can develop when people who are close do not share it with each other." Keeping or sharing secrets often puts people in a position of either gaining or losing the trust of someone." according to Shah.

    He added that talkative people could let secrets slip out. But this doesn't mean that it is a good idea only to share secrets with quiet people. A quiet person may be someone who keeps everything inside. To tell such a person a secret may cause them stress, and make them talk about the secret.

    Shah said that to judge whether to tell someone a secret, you'd better put yourself in their position. Think about how you would feel to be told that you mustn't give the information away. Shah also recommended that if you accidentally give up someone's secret you should come clean about it. Let the person know that their secret isn't so secret anymore.