How fit are your teeth? Are you lazy about brushing them? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush, and it lets you track your performance on your phone.

    The Kolibree toothbrush was exhibited at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection.

    The toothbrush will be able to teach you to brush right (don't forget the insides of the teeth!) and make sure you're brushing long enough. “It's kind of like having a dentist actually watch your brushing on a day-to-day basis,” says Thomas Serval, the French inventor.

    The toothbrush will also be able to talk to other applications on your phone, so developers could, for instance, create a game controlled by your toothbrush. You could score points for beating monsters among your teeth. “We try to make it smart but also  fun,” Several says.

    Serval says he was inspired by his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They said “yes,” but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed.

    The company says the Kolibree will go on sale this summer, for $99 to $199, developing on features. The U.S. is the first target market.

    Serval says that one day, it'll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.

    When was the last time someone unexpectedly did something nice for you? Not someone you knew, but a total stranger? It's happened to me a few times, but two instances really stand out.

    A few years ago, I was dining in a restaurant with a friend who kept talking about himself, completely not aware of the fact that I was sitting there in misery. It wasn't my friend's talks that made me suffer. I was recovering from a broken heart, and just sitting down to dinner reminded me of my last relationship. I could have burst into tears right there at the table.

    When we picked up the check, the waitress said, ―Your meal was already paid for.  My friend and I didn't have a clue how it happened. Then I remembered a man coming in out of the corner of my eye. He was dressed in mostly white, sat down at the bar, had a beer, and stayed for maybe ten minutes. The waitress said, ―Yes, the gentleman in white paid for you.  It felt like an angel was saying ―I see you, honey. It's going to be okay.

    Just last year, I was running a half-marathon. With just 1 mile to go, I was out of gas. Runners call it ―hitting the wall . I thought I couldn't move another inch. Out of nowhere, a stranger came up to me and said, ―What's your name, sweetie? Jennifer? Okay, Jennifer, let's go! Come on! It's just around the corner! You can do it!  And he ran with me until I picked up my pace. I found him at the finish line to thank him for the encouragement only to learn he wasn't even supposed to be in the race that day.

    I still shake my head when I think of these momentary angels that came to me at my point of need.

    Do you have any experiences like these?

    Bats are the only mammals(哺乳动物) that can fly a great distance, but they have another ability. Many bats live a very long time for an animal of their size. European researchers are studying bats to understand why they lives0 long. They hope to make discoveries aimed at fighting the aging process in human beings.

    Last week, the group of scientists said they had identified important biological qualities in some bat species. The group studied bat chromosomes(染色体), a line of genes found in the nucleus(细胞核) of cells. The scientists were most interested in structures connected to the ends of the chromosomes. They are called telomeres(端粒), which protect the ends of chromosomes and shorten each time a cell divides. Scientists believe this shortening process causes cells to breakdown. They say this is what causes aging.

    The European researchers studied 493 bats from four bat species. The group used information that had been gathered over more than 60 years. Of these animals ，the greater mouse-eared bat generally lived the longest, an average of 37 years. The scientists said this and a related species, which are grouped together under the name Myotis, had telomeres that did not shorten with age. Another Myotis bat holds the record for oldest age, reaching 41years. The scientists' findings suggest that these bats cells have the ability to maintain and repair their telomeres. This, they said, helps guard against the aging process.

    Based on its body size, a bat like the greater mouse-eared bat would be expected to live four years. But, these mammals have been found to live nearly 10 times longer than that. The scientists found that only 19 species of mammals live longer than humans when their body size is considered. Eighteen of these are bats.

    A medical study has shown that excess(过度的)coffee drinking could cause heart attacks in people who do not metabolize(使新陈代谢)caffeine fast enough.

    The study, published recently in the Journal of the American Medical Association, says an enzyme(酶)that metabolizes caffeine in the liver works differently in some people, depending on the make­up of the gene(基因). People who have a slow version (版本)of the enzyme are at a greater risk(风险)of a heart attack when they drink more coffee. The risk had something to do with a person's age and how many cups of coffee he drinks.

    The team from the University of Toronto in Canada studied 4,024 people living in coffee­rich Costa Rica between 1994 and 2004, of whom half suffered non­fatal(非致命的)heart attacks. They found slightly more than half had the slow version of the gene, while the rest had the fast form.

    Two to three cups of coffee a day increased the possibilities of a heart attack by 36 percent for those with the slow­acting gene and four or more cups a day lifted it by 64 percent.

    But those under 50 who had the fast version of the gene had a lower risk of heart disease, even with four or more cups a day.

    Those with the fast­acting gene who drank two to three cups of coffee a day had 22 percent reduced possibilities of having a heart attack, but drinking four or more cups a day only lessened the risk by 1 percent. Scientists recommend limiting coffee consumption(消耗量)to within four cups a day.

    In 1888 an Egyptian farmer digging in the sand near the village of Istabl Antar uncovered a mass grave. The bodies weren't human. They were feline — ancient cats that had been mummified(木乃伊化的) and buried in holes in astonishing numbers. "Not one or two here and there", reported English Illustrated Magazine, "but dozens, hundreds, hundreds of thousands, a layer of them, a layer thicker than most coal joints, ten to twenty cats deep. " Some of the linen-wrapped cats still looked presentable, and a few even had golden faces. Village children peddled the best ones to tourists for change; the rest were sold as fertilizer. One ship transported about 180,000, weighing some 38, 000 pounds, to Liverpool to be spread on the fields of England.

    Those were the days of generously funded explorations—that dragged through acres of desert in their quest for royal tombs, and for splendid gold and painted masks to decorate the estates and museums of Europe and America. The many thousands of mummified animals that turned up at religious sites throughout Egypt were just things to be cleared away to get at the good stuff. Few people studied them, and their importance was generally unrecognized.

    In the century since then, archaeology has become less of a treasure hunt and more of a science. Archaeologists now realize that much of their sites' wealth lies in the majority of details about ordinary folks—what they did, what they thought, how they prayed. And animal mummies are a big part of that.

    "They're really displays of daily life," says Egyptologist Salima Ikram. After peering beneath bandages with x-rays and cataloguing her findings, she created a gallery for the collection — a bridge between people today and those of long ago. "You look at these mummified animals, and suddenly you say, Oh, King So-and-So had a pet. I have a pet. And instead of being at a distance of 5,000-plus years, the ancient Egyptians become clearer and closer to us."

I'm standing on Rio's beach, one of the most famous 1 of sand. In this lively, multicultural country, the beach is not just a place;it's a state of mind—a way of thinking and living. 

Every Brazilian has his or her own ideas of the perfect beach, 2 to tell you where to find it. I'm happy to take their advice but my ultimate goal is to find my own dream beach. First, I go to Prainha's beach 3 by a row of perfect palm trees, moving softly in the ocean breeze. Its beauty is magnificent-its perfect graceful lines are like something in a 4 . But for me, it's somewhat too perfect. I am searching for something a bit 5 . 

I continue my search heading north to a legendary beach: Jeri. As an international destination, it attracts visitors from Tokyo to Toronto. Luckily, Jeri hasn't been 6 by tourists mostly because of its isolated(偏远的)location—at least five hours from any airport. I take a beach buggy(沙地车), driving for three hours. The boats lie on their sides while nets 7 to dry on lines between fishermen's houses. Peaceful and beautiful! How can it possibly get any better? I 8 . 

My final stop is the islands of Fernando, 9 a few hundred kilometers out in the Atlantic. They once were used as a prison and later by the army. Today, they are a national park and UNESCO World Heritage Site, 10 with birds and sea life. The beach there is a perfect 11 of sand, sea, and sky. The water is pale blue and warm, alive with colorful fish, 12 , and other marine life; the sand is the color of 13 . In the rocks and strong winds that 14 come in from the Atlantic, there is the wilderness I was seeking. Finally, I've found the beach of my dreams. I 15 my toes in the sand deeply and imagine I can hold on to this place forever.