It might be something that you miss unless it's pointed out to you. Next time you go to a public bathroom, take a look before you sit down on the toilet seat. You won't see a circle shape, but something designed not connected in the front part: a U.

    This is an open-front toilet seat, and thanks to the American Standard National Plumbing (水管装置) Technology, it's the go-to for most public restrooms. This technology was created in 1955 and further developed by the Uniform Plumbing Technology in 1973, according to Mental Floss.

    As to the plumbing rules which fit water seats, the first two requirements are as follows:

    Toilet seats shall be of smooth, non-absorbed material.

    All Toilet seats, except those within apartment units, shall be either of the open front type or have an automatic seat cover.

    This part of the rules also clears up why you won't meet fur toilet seats in truck stop bathrooms. The reason for both of these rules comes down to health. With an open front, there's less surface area that can make incidental touch with your private regions. But what about the toilet seat covers you can use? Unfortunately, those don't offer as much protection against bacteria as you think they do.

    They were also designed with women in mind, according to Lynne Simick, the senior vice president of technology development at IAPMO. The open front of the seat is fairly good for women.

Now that you know why the public toilet seat is shaped the way it is, learn which one is the cleanest you can use.

    There's a new achievement in 3D printing that's beginning to come into focus: food. Recent development has made possible machines that print, cook, and serve foods on a mass scale(大规模地). And the industry isn't stopping there.

    Food production

    With a 3D printer, a cook can print complicated chocolate sculptures and beautiful pieces for decoration on a wedding cake. Not everybody can do that—it takes years of experience, but a printer makes it easy. A restaurant in Spain uses a Foodini to "re-create forms and pieces" of food that are "exactly the same", freeing cooks to complete other tasks. In another restaurant, all of the dishes and desserts it serves are 3D-printed, rather than farm to table.

    Nutrition

    Future 3D food printers could make processed food healthier. Hod Lipson, a professor at Columbia University, said, "Food printing could allow consumers(消费者) to print food with customized(定制的) nutritional content, like vitamins. So instead of eating a piece of yesterday's bread from the supermarket, you'd eat something baked just for you on demand."

    Challenges

    Despite recent advancements in 3D food printing, the industry has many challenges to overcome. Currently, most ingredients (烹饪原料) must be changed to a paste（糊状物）before a printer can use them, and the printing process is quite time-consuming, because ingredients interact with each other in very complex ways. On top of that, most of the 3D food printers now are limited to dry ingredients, because meat and milk products may easily go bad. Some experts are doubtful about 3D food printers, believing they are better suited for fast food restaurants than homes and high-end restaurants.

    Life's greatest joys and its greatest sorrows often come from the relationships we have developed with others. In fact, our existence is quite dependent upon this interaction with other individuals (个人) and groups of individuals.

    In our world today, it seems that most people struggle for happiness through pleasant physical surroundings and economic security. These are great, but if there is conflict in human relations, these things do not bring happiness. Think about the last time you were having an argument or a disagreement with one of your co­workers, your boss, your friend, or a family member. Even though you might have been having some success in many areas of your life, did you find yourself still feeling some discomfort due to the stress in that particular relationship? On the contrary, you may know people who are happy in great poverty and with physical stress if they have meaningful, pleasant relations with people around them.

    Consider the best relationship that you have ever had with any individual. To some degree it probably is or was marked by absolute honesty, deep levels of trust, respect for that person's skills, knowledge, or capabilities, open communication, acceptance of different views, and little concern for images.

    In effort to make the relationships we currently have the best that they can be, remember that persuasion usually cannot take place unless there is some sort of close, meaningful connection between the two people involved. The result will be a relationship of respect and progression.

    Many of us have difficulty in accepting the faults and weaknesses of others: co­workers, work leaders, family members, or members of our social or religious groups. Our tendency to demand perfection of others can cause us to lose sight that we, ourselves, are less than perfect.       
    Undoubtedly, there are differences among us. Some of us are even cruel and unpleasant. Others may have cultural differences that are blocks that affect us. But learning to look for the similarities instead of those things that set us apart, bearing differences, and seeing the best in others rather than the worst will lead to relationships of deep respect and lasting value.

    Stocky, slow-moving whale, rarely grows beyond 15 metres in length

    Flippers are a third of body length; variable dorsal fin size and shape; saw-toothed trailing edge on flukes, often raised when diving

    Bumpy tubercles on top of head

    Body colour is dark brown to black; often extensive white on flippers and underside of body and flukes; such patterns enable individual recognition

    Bushy blow, occasionally V-shaped

    270-400 olive baleen plates

    Humpback whales belong to the rorqual (groove-throated) family, which includes fin, sei, Bryde's, minke and blue whales. The big family migrate between winter tropical breeding areas (North West Shelf, Great Barrier Reef, New Caledonia, Vanuatu, Fiii, Tonga) and summer Antarctic feeding areas. Once common in New Zealand waters, humpbacks are now rarely seen and may migrate further offshore. Males compete for mates either by physical fight or by song. Females give birth to their young every two to three years; some non-breeding females probably remain in the southern waters during winter. Young humpback whales return to their area of birth but in later life some wander between breeding areas. Humpbacks eat small shrimps and other schooling prey, such as fish, forming small, cooperative groups of two to three individuals to feed.

    Similar species: Easily identifiable due to a 'hump' back when submerging, but at a distance may be confused with other species that raise their flukes when diving, such as sperm, right and blue whales.

    Protection status: Recovering well from past whaling and now numerous in some former migration and aggregation areas, rarely seen in others.

    A tiny clue found in ancient deposits has unlocked big secrets about Greenland's past and future climate. Just beyond the northwest edge of the vast Greenland Ice Sheet, researchers have discovered lake mud that have survived the last ice age. The mud, and remains of common flies in it, record two interglacial periods(间冰期)in northwest Greenland.

    Although researchers have long known these two periods—the early Holocene and Last Interglacial—experienced warming in the Arctic, the mix of fly species shows that Greenland was even warmer than previously thought. "As far as we know, it has never been found in Greenland. We think this is the first time anyone has reported it in ancient deposits or modern lakes there," Axford said. "We were really surprised to see how far north it migrated (迁徙)."

    This new information could help researchers better measure Greenland's sensitivity to warming, by testing and improving models of climate and ice sheet behaviour. Those models could then improve predictions of how Greenland's ice sheet might respond to man-made global warming. After all, Greenland covers 80 per cent of the Arctic country and holds enough ice to equal 20 feet of global sea level. "Northwest Greenland might feel really remote, but what happens to that ice sheet is going to matter to everyone in every coastal city around the world," said Yarrow Axford, an associate professor in the team. "One of the big uncertainties in climate science is how fast the Earth changes when it gets warmer. Geology gives us an opportunity to see what happened when the Earth was warmer than today," said Axford.

    People might be surprised to see how today's Greenland looked during the last two interglacial periods. During the Last Interglacial, global sea levels increased by 15 to 30 feet, largely due to thinning of Greenland and Antarctica's ice sheets. However, now researchers believe northern Greenland's ice sheet experienced stronger warming than previously thought, which could mean that Greenland is more responsible for that sea-level rise.

    Finding lake deposits older than about 10,000 years, however, has been historically very difficult in Greenland. To measure these ancient temperatures, researchers look to ice cores (冰核) and lake deposits. Since ice and lake deposits form by a gradual buildup on annual layers of snow or mud, these cores contain history of the past. By looking through the layers, researchers can obtain climate clues from centuries ago.

Any schoolchild knows that a whale breathes through its blowhole. Fewer know that a blowhole is a nostril （鼻孔） slightly changed by evolution into a form more useful for a mammal that spends its life at sea. And only a dedicated expert would know that while toothed whales, such as sperm whales, have one hole, baleen （鲸须） whales, such as humpback and Rice whales, have two. 

Even among the baleen whales, the placing of those nostrils differs. In some species they are close together. In others, they are much further apart. In a paper published in Biology Letters Conor Ryan, a marine biologist at the Scottish Association for Marine Science, suggests why that might be. Having two nostrils, he argues, helps whales smell in stereo （立体空间）. 

Many types of baleen whales eat tiny animals known as zooplankton （浮游动物）， which they catch by filtering （过滤） them from seawater using the sheets of fibrous baleen that have replaced teeth in their mouths. But to eat something you first have to find it. Toothed whales do not hunt by scent. In fact, the olfactory bulb-the part of the brain that processes smell-is absent in such creatures. But baleen whales still have olfactory bulbs, which suggests smell remains important. And scent can indeed give zooplankton away. Zooplankton like to eat other tiny creatures called phytoplankton （浮游植物）. When these are under attack, they release a special gas called dimethyl sulphide, which in turn attracts baleen whales. 

Most animals have stereoscopic senses. Having two eyes, for instance, allows an animal to compare the images from each in order to perceive depth. Having two ears lets them locate the direction from which a sound is coming. Dr Ryan theorized that paired blowholes might bring baleen whales the same sorts of benefits. 

The farther apart the sensory organs are, the more information can be extracted by the animal that bears them. The researchers used drones to photograph the nostrils of 143 whales belonging to 14 different species. Sure enough, baleen whales that often eat zooplankton, such as the North Atlantic right whale, have nostrils that are farther apart than do those, such as humpback whales, that eat zooplankton occasionally. Besides allowing them to breathe, it seems that some whales use their blowholes to determine in which direction dinner lies.