【推荐2】Vast underwater meadows (草甸) of gently waving sea grass cover hundreds of miles up and down the West Coast. These blue-green fields perform a variety of important services. They protect the shoreline from erosion, clear pollutants from the water and provide habitats for all kinds of marine animals.

New research suggests sea grass meadows may also mitigate a serious consequence of greenhouse gas emissions: the steady acidification of ocean waters. The study published in the journal Global Change Biology finds that sea grass forests can raise pH levels in coastal waters. As they perform photosynthesis (光合作用), they remove carbon dioxide from the water, counteracting the acidifying effect of the gas.

“I think we are all very excited about it,” said lead study author Aurora Ricart, a scientist at the Bigelow Laboratory for Marine Sciences.

Ocean acidification is a side effect of rising carbon dioxide levels in the atmosphere. Some of this CO₂ dissolves out of the air and into the sea, causing a chemical reaction that lowers the water’s pH. Scientists sometimes refer to it as global warming’s “evil twin”—an invisible companion to climate change.

Ocean acidification can have harmful effects on marine organisms like shellfish and coral by preventing them from properly forming the hard shells they need to survive. It’s a threat both to natural ecosystems and to shellfish fisheries around the world. The study presents a natural way to address the problem.

Researchers analyzed six years of data from sea grass meadows spanning more than 600 miles off the California coastline. It focused on the common eelgrass, one of the most widespread sea grass species on the West Coast. The authors claim it’s the largest, most comprehensive study of its kind.

According to the study, sea grass ecosystems can raise pH levels by more than 0.1 unit, equivalent to about a 30% decrease in acidity. The effect isn’t constant. It comes in waves and is influenced by temperature, daylight, ocean currents and other factors that affect water chemistry and sea grass photosynthesis rates. But the tempering influence on acidification can be lasting, sometimes persisting for up to three weeks at a time. The study also shows that pH is higher in sea grass ecosystems, compared to nearby areas with no sea grass, about 65% of the time.

The study didn’t investigate the effects of higher pH on marine organisms — that’s a question for future research. But there’s reason to believe these meadows may have a positive influence on shellfish and other ocean animals.

【推荐2】What is life? Like most great questions, this one is easy to ask but difficult to answer. The reason is simple: we know of just one type of life and it’s challenging to do science with a sample size of one. The field of artificial life-called ALife for short — is the systematic attempt to spell out life’s fundamental principles. Many of these practitioners, so-called ALifers, think that somehow making life is the surest way to really understand what life is.

So far no one has convincingly made artificial life. This track record makes ALife a ripe target for criticism, such as declarations of the field’s doubtful scientific value. Alan Smith, a complexity scientist, is tired of such complaints. Asking about “the point” of ALife might be, well, missing the point entirely, he says. “The existence of a living system is not about the use of anything.” Alan says. “Some people ask me, ‘So what’s the worth of artificial life?’ Do you ever think, ‘What is the worth of your grandmother?’”

As much as many ALifers hate emphasizing their research’s applications, the attempts to create artificial life could have practical payoffs. Artificial intelligence may be considered ALife’s cousin in that researchers in both fields are enamored by a concept called open-ended evolution (演化). This is the capacity for a system to create essentially endless complexity, to be a sort of “novelty generator”. The only system known to exhibit this is Earth’s biosphere. If the field of ALife manages to reproduce life’s endless “creativity” in some virtual model, those same principles could give rise to truly inventive machines.

Compared with the developments of Al, advances in ALife are harder to recognize. One reason is that ALife is a field in which the central concept — life itself — is undefined. The lack of agreement among ALifers doesn’t help either. The result is a diverse line of projects that each advance along their unique paths. For better or worse, ALife mirrors the very subject it studies. Its muddled (混乱的) progression is a striking parallel (平行线) to the evolutionary struggles that have shaped Earth biosphere.

Undefined and uncontrolled, ALife drives its followers to repurpose old ideas and generated novelty. It may be, of course, that these characteristics aren’t in any way surprising or singular. They may apply universally to all acts of evolution. Ultimately ALife may be nothing special. But even this dismissal suggests something：perhaps, just like life itself throughout the universe, the rise of ALife will prove unavoidable.

【推荐1】The Government’s sugar tax on soft drinks has brought in half as much money as Ministers first predicted it would generate, the first official data on the policy has shown.

First announced in April, 2016, the tax which applies to soft drinks containing more than 5g of sugar per 100ml, was introduced to help reduce childhood obesity (肥胖). It is believed that today’s children and teenagers are consuming three times the recommended level of sugar, putting them at a higher risk of the disease.

Initially the sugar tax was expected to make £520m a year for the Treasury. However, data of the first six months showed it would make less than half this amount. At present it is expected to generate £240m for the year ending in April 2019, which will go to school sports.

It comes after more than half of soft drinks sold in shops have had their sugar levels cut by manufacturers (制造商) so they can avoid paying the tax. Drinks now contain 45 million fewer kilos of sugar as a result of manufacturers’ efforts to avoid the charge, according to Treasury figures. Since April drinks companies have been forced to pay between 18p and 24p for every litre of sugary drink they produce or import, depending on the sugar content.

However, some high sugar brands, like Classic Coca Cola, have accepted the sugar tax and are refusing to change for fear of upsetting consumers. Fruit juices, milk-based drinks and most alcoholic drinks are free of the tax, as are small companies manufacturing fewer than 1m litres per year.

Today’s figures, according to one government official, show the positive influence the sugar tax is having by raising millions of pounds for sports facilities (设施) and healthier eating in schools. Helping the next generation to have a healthy and active childhood is of great importance, and the industry is playing its part.

【推荐2】After a salon(美发厅) turns away a physically challenged woman, a stranger makes a truly beautiful gesture. “Beauty isn’t about having a pretty face. It’s about having a pretty mind, a pretty heart, and a pretty soul, Oh, and pretty nails!” That may well be Angela Peters’s motto.

Last July, Peters, 36, rolled her wheelchair into a nail salon at the Walmart shopping center in Burton, Michigan, with the idea of painting her fingers. But Peters was turned away. The salon told her that they were afraid it would be too difficult to properly paint her nails given that her hands shook, What was meant to be a clay of happiness for Peters was now a disappointment.

Ebony Harris, 40, saw everything and approached Peters. Harris offered to do her nails. They shopped for nail polish. They settled on a bright blue — a statement color that would catch every eye. They then made their way into a neighboring Subway, found a table for two, and set up shop. Harris gently took Peters’s hand into hers and carefully began painting her nails.

Watching it all with awe and admiration was Subway employee Tasia Smith. What struck her most was the ease and gentleness displayed by Harris as she painted Peters’s nails, all the while chatting as if they were old friends.

Peters, who runs a poetry website, heavenlypoems. com, harbors(心怀) no bitterness toward the nail salon that turned her away. (The salon says they refused to offer Peters service because they were too busy.) “When people do us wrong we must forgive,” Peters wrote on her website. “I just want to educate people that people with different challenges, like being in a wheelchair, can have our own business and get our nails done like anyone else.”