People often take the ability to communicate for granted, but when you grow up with a sibling who is nonverbal, it changes the way you look at the world.

Archer Calder is a 16-year-old high school student from Utah. His sister is 14-year-old Della, who has a rare genetic condition called Bainbridge-Ropers syndrome. Even though Della isn’t able to speak, she and her brother are very close. Last year, Archer was searching online for an app that might help Della express her needs, wants, likes, and dislikes.

However, he found that the available apps were too expensive, and didn’t offer everything he was looking for. Since Archer has always loved coding and computer programming, he decided to make his own app. Apart from that, Archer was determined to make his app better than the rest, completely open source, and free. That’s how Freespeech was born.

Archer said he decided to help his sister communicate because he wanted to hear her thoughts, but he also had a deeper reason. Growing up, he had a stutter (口吃) that kept him from expressing himself. It took him four years of speech therapy to overcome the difficulty, and the feeling of not being able to get his words out stuck with him.

Freespeech refers to the augmentative and alternative communication (AAC) that helps people communicate by pressing buttons that represent words. Users like Della can make sentences by pressing multiple buttons in a sequence. It opens up a whole new world of communication for people who are nonverbal. Now Della can communicate like anybody else, through the iPad.

Archer first put it on TikTok, and the response was so positive that he continued sharing it on GitHub, where experienced programmers helped beef it up. Archer says even if Freespeech only helps one person, his sister, all the time and the put in was worth it.

When we think about ways to prevent heart disease, looking after our teeth is probably not the first thing that comes to mind. But in recent years, studies have established a closer link between poor oral health and inflammation (发炎)—a known trigger for many serious illnesses, including heart disease, cancer, and even diabetes.

But how exactly does poor oral health cause such diseases in the body?

While you can’t see or taste them, your mouth is home to microbes. According to the National Institutes of Health, your mouth is home to 700 different species of bacteria. While the good microbes help your mouth manage bad microbes’ growth and protect against the harmful bacteria in food, the bad microbes form communities with other bacteria, which can increase the acidity of your mouth.

Poor dental health can result in a weakened immune system. When we have dental disease, the bacteria from our mouth can get into our bloodstream. From there, it then produces a protein which causes the blood to thicken. This means that clots (凝块) are more likely to form, which can stop the heart from receiving the nutrients and oxygen it needs in order to function well, the results of which can lead to an increased risk of heart attack. Similarly, dental disease can also cause inflammation of the blood vessels (血管), thereby blocking the blood supply to the brain, which can lead to potential stroke.

By brushing our teeth twice daily, maintaining a low-sugar diet, and regularly visiting our dentists, we can help reduce the risk of developing dental disease, which can result in tooth loss.

A healthy mouth can be beneficial. Tooth loss through dental disease is almost entirely preventable. There is no reason why, with a good daily oral health routine, we cannot keep our teeth for life.

Whether it’s a tricky maths problem or an unexpected bill, daily life is full of stressful experiences. Now researchers have found that humans produce a different smell when under pressure and dogs can sniff it out.

While previous studies have suggested dogs might pick up on human emotions, possibly through smell, questions remained over whether they could detect stress and if this could be done through scent.

“This study has definitively proven that people, when they have a stress response, their smell profile changes,” said Clara Wilson, a PhD student at Queen’s University Belfast, and first author of the research Wilson added the findings could prove useful when training service dogs, such as those that support people with post-traumatic stress disorder(PTSD)(创伤后应激障碍).

Wilson and colleagues first constructed a stand bearing three containers, each topped by a lid with holes. They were able to train four dogs to identify the container holding a particular breath and sweat sample, even when the other containers included unused cloth, samples from another person, or samples from the same person taken at a different time of the day. Then the team turned to breath and sweat samples collected from 36 people asked to count backwards from 9,000 in units of 17. The participants reported feeling stressed by the task and, for the 27 who carried it out in the laboratory, their blood pressure and heart rate rose.

The dogs were taught to pick out samples taken just after the task from a line-up that included two containers holding unused cloth. The researchers then tested whether the dogs could do the same when the line-up included not only unused cloth but samples taken from the same participant just before the task, when they were more relaxed. Each set of samples was shown to a single dog in 20 trials.

The results reveal that the dogs chose the “stressed” sample in 675 out of the 720 trials. The team say while it was unclear what chemicals the dogs were picking up on, the study shows humans produce a different smell when stressed.