Recently, I learned firsthand why it's a bad idea to judge people prematurely (过早地).

    I'm a nursing supervisor, and my job is to evaluate workers' performances at the hospital.

    Kenny was a new employee. After weeks' probation (试用), I had to admit that he was clean, punctual and efficient.

    But he had this self-assured and energetic presence. He was a large man, both physically and socially — he was independent and strong. I worried that our hospital, which demanded teamwork, was not right for such a personality.

    We had a patient named Mary. At 94 years old, Mary was weak. She had outlived her husband and sisters.

    Mary had an obsessive (强迫性的) belief that someone had taken her purse. She searched for it all the time. Unless tied to her wheelchair, she would go through the door onto the street mindlessly searching and never giving up. She was often sitting in her wheelchair in the hallway, where she stopped everyone who came near.

    “Can you lend me a comb?” she would ask. “I've lost mine. It was in my red purse. Where is my purse?”

    Every day it was the same. We all knew Mary didn't have a purse, but we would answer: “Sure, if I see your purse I'll bring it back.”

    One afternoon, I saw Kenny walking down the hall with a grocery bag. He walked toward Mary in her wheelchair. He pulled out a red purse.

    Mary's old hands flew up to her face in a gesture of wonder and joy, and then flew out hungrily like a starved child taking bread. Mary grabbed the red purse. She held it for a moment, and then pressed it to her breast, rocking it like a baby.

    Kenny leaned over, unzipped the purse open and showed Mary a comb inside. Tears of joy poured down Mary's face.

    Instead of paying lip service like the rest of us, Kenny had made Mary's problem his problem. I had been wrong about Kenny.

    It was an autumn day, and 1 was standing in the kitchen, hanging my head over the counter and trying to figure out how many calories were in a bowl of homemade yogurt and fruit. And I felt annoyed.

    I was 16, and my best friend and I had gone to our first Weight Watchers meeting. It was the trend in the mid-1980s, and even though I was an athlete, like many teen girls, I didn't necessarily like what I saw in the mirror. But after a week or so of recording every meal and snack and calculating the calories, I had had enough. I went back to my routine of chowing whatever I wanted, running and skiing, and let that be that. And it's still pretty much what I do; as long as the workouts are regular and the food is whole and balanced, my body's set point hasn't varied for years.

    The weight loss trend of three decades ago−full of scales and counting calories−has fallen away. Now fasting is popular. The ways to keep fit vary: on the 5:2 diet a person eats for five days and fasts for two days each week, while the 18:6 refers 10 fasting for 18 hours and then eating within a six-hour window each day.

    In this issue, Associate Editor Mark Barna tries to understand the science behind the fasting plans. Researchers have found that animals like monkeys age more slowly after years of eating less, and in the lab in humans, they saw improvements in a number of signs that indicate risk of some hard to cure diseases. The hope for healthy weight loss isn't over yet, but at least now the calculators don't have to be out at every meal.

    The Notre Dame fire has been put out, but its spire and a large portion of its wooden roof have been damaged. The terrible destruction causes a sudden sharp pain to people around the world. On Chinese social media network Wechat a common comment on the disaster is: "What a pity that we cannot see the damaged parts of the wonder anymore."

    But the good news is that there is at least one way of seeing them, namely via a video game called Assassin's Creed: Unity. In this game, the player can travel to one city after another and enter the buildings exactly like what they are in reality, and see Notre Dame as it was before the fire. Further, with virtual reality technology, which is already quite mature, one can even look around the undamaged Notre Dame as if it is still there. Maybe digital technology could help to better protect architectural cultural heritage.

    The idea of digitizing ancient buildings, making digital models of them so their data can be saved, dates back to the 1990s and the necessary technology has continued to advance since then. By scanning the ancient buildings with lasers, building 3D models with multiple images, as well as measuring everything precisely, engineers can make a copy as accurate as the real one.

    As computers and smartphones are hugely popular, the digital replica（复制品）has great use value  First, it allows tourists to feel the cultural relics without touching them, which helps protect them. The virtual tour of Dunhuang Grottoes in Gansu Province is a good example of this as tourists can view the paintings without standing near them. Furthermore, it can make the digitized cultural relics more famous by spreading awareness about them via the Internet. In 2000, a virtual tour of the Great Wall became very popular at the Hannover World Expo, which increased the number of foreign tourists visiting the site in the following years. Above all, it preserves all the information of the cultural relics. Even if the original ones are damaged one day, people can still know what they were like and can build a replica if desired.

    Of course, however precise a model is, it is not the original. Time is the biggest threat to a country's architectural heritage, which will always become ruins with the passing of time. Maybe we will have better technologies in the future, but the digital technology offers a practical way to preserve architectural cultural heritage at the moment.

    A typical school day in the UK starts around 8:30 am. This is often even earlier elsewhere in the world, with students sitting down to their first lesson at 7:30 am in the US. The average teenager ideally needs eight to nine hours' sleep each night, but in reality a lot of teenagers struggle to get this much. A lot of the problems happen because our sleep patterns are not fixed, and they change as we grow.

    So a later school start time could help to solve this problem, by ensuring to get their eight plus hours of sleep and react properly to their body's natural rhythms(规律). There has been a general change over the past 25 years to shorten the school day. This is not at the cost of teaching time (which has remained constant) but at the cost of natural breaks, which has led to reduced lunch time and lesson breaks.

    Later start times could help teens' grades and health. This is mainly because it makes the management of children easier. Managing hundreds of children "playing" requires effective staffing. And there is always the fear that behavior worsens during breaks. So the theory goes that having them in class and strictly managed must be better.

    But this means that students barely have enough time to absorb what they were doing in maths before suddenly they are forced to study ancient history. And teaching staff also move through from one class to another, with hardly a rest or time to refocus.

    Clearly rethinking the school day could benefit everyone included. Anyway, it could also lead to better achievement in teenagers and less of a struggle for parents in the mornings. For teachers, it could also mean a less stressful day all around and what could be better than that?

    Water is a necessity of life. Rain, especially, helps plants grow and stay green. But too much rain, especially in cities, can lead to flooding. That can cause waste water systems to overflow and send pollutants into rivers and other waterways. To fight the problem, several cities in the United States are starting programs like rooftop gardens.

    A team at the University of the District of Columbia in the nation's capital has created a garden on the top of one school building. The garden holds many kinds of plants to help absorb rainwater and grow food at the same time. Architect David Bell has designed five "green roofs" for the university. He says he is excited about the project because "it meant doing something more than just dealing with storm water management. It took advantage of a resource above the city and these flat roofs that aren't doing anything really became something that was about urban agriculture." Rainwater is collected in large containers and sent through a system that waters the rooftop garden. The roof is filled with green life that appeals to insects.

    In cities, "you don't have that many spaces to choose from and so rooftops are just (unused) space," says Caitlin Arlotta. She is a student in the school's Urban Agriculture program. The project is part of a research program to see which plants do well on rooftops. The researchers are looking at plants including strawberries, tomatoes and sweet potatoes. The university also has other green spaces. "We also have our own farm experiments," Arlotta said. "Within each of those growing systems, we want to be able to tell people which sorts of these crops grow the best."

    Sandy Farber Bandier helps run UDC's Master Gardener program. It seeks to improve cities and make them beautiful by training people to become Master Gardeners. She says she's been surprised by the garden's output. "My biggest surprise was that we produced 4, 250 pounds of produce the first year and was able to spread that to people in need." She also likes being able to show people who live in D. C. and others beyond the nation's capital what and how food can be grown on a rooftop. "This is the future for food. You grow it here, you prepare it in a commercial kitchen, you distribute through farmers markets, food trucks, and then you recycle."

    City trees grow faster and die younger than trees in rural forestry, a new study finds. Over their lifetimes, then, urban trees will likely absorb less CO₂ from the air thah forest trees.

    As we all know, the earth would be freezing or burning hot without CO₂. However, CO₂ is a greenhouse gas, meaning it traps energy from the sun as/heat. That makes temperatures near the ground rise. Human activities, especially the widespread burning-of fossil(化石)fuels, have been sending extra greenhouse gases into the air. This has led to a rise in average temperatures across the globe.

    Studies had shown forests readily absorb CO₂, but there hadn't been much data on whether city trees grow, die and absorb CO₂ at the same rate as forest trees do. So some researchers decided to find out.

    To figure out how quickly trees were growing, researchers tracked their diameters (the width of their trunks) between 2005 and 2014. A tree's diameter increases as it grows, just as a person's waist size increases as they gain weight. About half the weight of a tree is carbon, research has shown. Most of the rest is water. Over the nine years' tracking, the researchers found city trees absorbed four times as much carbon from the air as forest trees. However, they were twice as likely to die. So over the lifetime of each type of tree, forest trees actually absorbed more CO₂.

    City trees grew faster because they had less competition for light from their neighbors. In a forest, trees tend to grow close together, shading their neighbors. Street trees also benefit from higher levels of nitrogen (氮)in rainwater. Nitrogen helps plants grow. Waste gases from gas-burning cars also contain nitrogen, thus enriching city air with nitrogen. Later, rainwater may wash much of it to the ground. Some street trees may also have better access to water than trees in the country because the underground water pipes can leak.