Eating a juicy steak is worse for the environment than frying up some tofu: that should come as no surprise. Going vegan can greatly cut the carbon footprint of your diet. But what about the fewer calories, and lower levels of protein, found in most plant-based foods when compared with meat?

To make the relative carbon impact of foods easier to understand, The Economist proposes a banana index (指数). It compares popular foodstuffs in three aspects—weight, calories and protein—compared to the humble banana, a fruit of middling nutritional value and impact on weather conditions.

Indexing greenhouse-gas emissions to a single food gives a sense of how different foodstuffs rank. Unfortunately for carnivores (食肉动物), beef is bad for the environment no matter how you slice it. Producing one kilogram of mince (馅) causes as many emissions as 109kg of bananas (call it a “banana score” of 109). As for nutritional value, beef’s banana score falls to 54 (one calorie of beef mince causes 54 times as much carbon emissions as one calorie of banana). By protein, it scores seven.

Poultry (家禽) scores 11 bananas by weight and four by calorie. However, as a source of protein, it is more carbon-friendly than bananas: poultry protein emits just three-fifths of the same amount of banana protein. The same applies to salmon. Unsurprisingly, plant-based alternatives to meat do even better: a meat-free burger, for instance, scores just one-fifth of the emissions of bananas per gram of protein.

Our banana index relies on average emissions for a given food. In the real world some producers are more climate-friendly than others, and some foods travel farther to consumers. Our banana index also does not capture other environmental impacts, such as land and water use (though here too, beef tends to perform poorly).

Voting in Europe suggests that most consumers want to be more climate-friendly—and with food production responsible for perhaps a quarter of global emissions, eating with the climate in mind would make a difference. Three-quarters of the respondents said they want labels that would explain the climate impact of their food. In the meantime, our banana index might help.

Gold Coast family holidays are always great fun whether you are from Australia or from abroad. There are beautiful beaches, adventure parks, nature parks and so much more.

There are so many sights to see here. It is a pity to drive in a car and you'll miss a great part of it. Australia is home to many animals and birds that can only be seen when moving slowly and going into the areas that they live.

When you are on a bicycle, you have the advantage of being able to stop whenever you want to see an interesting animal or bird that you have never seen before. It is a quieter mode(方式) of transportation as well, so you might even be able to take a picture. When you are on the beach, you can breathe that clean air and view the beauty of the water and sand. It is a totally different experience from either simply sunbathing or passing it in a car.

There are many choices of hiring a bicycle to experience the Gold Coast attractions. There are stores that will fit a bike perfectly to your size. These bikes for both adults and children are in many styles and colors to please any taste. If you have ever wanted to try a tandem bike (双人单车), now is your chance, because they have those too.

A bicycle hire on Gold Coast is something that everyone should try at least once. This is a wonderful chance for anyone who likes to cycle and it is also a cheap way to travel with your family.

A new study of older adults finds excessive daytime napping (小睡) may signal an increasing risk of Alzheimer’s disease (阿尔茨海默症). Investigators from Brigham and Women’s Hospital report a relationship between daytime napping and cognitive (认知的) aging: excessive daytime napping predicts an increased future risk of Alzheimer’s, and a diagnosis of Alzheimer’s speeds up the increase in daytime napping during aging.

“Daytime sleep behaviors of older adults are often ignored, and a consensus for daytime napping in clinical practice and health care is still lacking,” said Peng Li of the Medical Biodynamics Program in Brigham’s Division of Sleep and Circadian Disorders. “Our team calls for a closer attention to 24-hour sleep patterns — not only nighttime sleep but also daytime sleep — for tracking the health of older adults.”

Researchers at the Brigham recognized that all previous studies on Alzheimer’s disease assessed napping within a participant only once, and most of which were subjective and questionnaire-based. In the new study, more than 1000 individuals, with an average age of 81, were provided Actical, a watch-like device, to wear on their wrist for up to 14 days. After napping episodes were identified, the nap duration and frequency were calculated.

The results suggest that excessive daytime napping may signal an increasing risk of Alzheimer’s, and that faster yearly increase in daytime napping may be a sign of worsening or unfavored clinical progression of the disease.

Researchers acknowledge that although the method of the new study has been widely used in sleep field studies, they recognize that polysomnography (多导睡眠记录仪) is the gold standard for sleep scoring. Moreover, the participants studied were older, and therefore, the findings may not be easily translated to younger people. In addition, future studies should test whether a direct intervention in daytime napping can lower the risk of Alzheimer’s or cognitive decline.

“We hope to draw more attention to daytime sleep patterns and the importance of patients noting if their sleep schedule changes over time,” said co-senior author Kun Hu of the Medical Biodynamics Program. “Sleep changes are critical in shaping the internal changes in the brain.”