If you were on the street in Mexico today you might think you were in an operating room, surrounded by doctors. You could see many concerned people with masks (口罩) trying their best to stop the swine flu (猪流感). And the masks aren’t only being used in Mexico. A friend of mine traveling from New York City to Florida was given a mask and a pair of gloves just after he reached the airport. And another friend went to get a haircut only to be faced with a hairdresser wearing a mask!

But do the masks really work? Is covering your nose and mouth the key to stopping the swine flu? To find out the truth, ABC’s reporter Sharyn Alfonsi talked with germ (细菌) expert Dr. Elaine Larsen. It turns out that when you sneeze (打喷嚏) the air coming out of your mouth at a speed of one hundred miles per hour carries germs which can travel anywhere around you and make people around you infected (被感染).

However, whether you become infected actually depends on the weather. As Sharyn reported, when you sneeze, the germs leave your body in small drops of water coming out of your mouth. If the weather is wet, the wet air will make the small drops bigger and heavier and they drop down towards our feet. If this happens, we won’t become infected. But if the air is dry, those small drops can float higher up, making it possible for them to touch someone else’s nose, mouth or their mask.

Larsen says the masks can stop the germs well but after a few hours, they start to get wet, holding a lot of germs they come across and causing you to breathe them in. The masks do work, but the key to stopping the germs is changing your masks often.

An estimated 5. 7 million people in the U. S. have Alzheimer's disease. The most common type of dementia(痴呆) -and that number is expected to more than double by 2050. Early diagnosis (诊断) is fundamental for patients to benefit from the few therapies available. But no scans can deliver a conclusive diagnosis while a person is alive; instead doctors have to conduct numerous and complicated clinical and neuropsychological tests. So there is growing interest in developing artificial intelligence to identify Alzheimer's based on brain imaging.

Researchers at the University of Califormia, San Francisco have now successfully trained an AI algorithm (算法) to recognize one of the early signs of Alzheimer's-a reduction in the brain's glucose(葡萄糖) consumption- in positron emission tomography(pet) imaging.

The algorithm accurately predicted an eventual Alzheimer's diagnosis in nearly all the test cases, d according to the study. In PET imaging, a very small amount of a radioactive compound are injected into the body, producing three-dimensional- images of metabolism(新陈代谢) circulation and other cellular activities. PET is well suited for an Al diagnostic tool because Alzheimer's leads to subtle changes in the oad0 brain's metabolism that begin years before neural tissue starts to go downhill, says study co-author Jae Ho Sohn, a radiologist at UCSF. These changes are "'very hard for radiologists to pick up. "he notes.

The algorithm was trained and tested on 2, 100 PET brain images from about 1, 000 people 55 years and older. The images came from a 12-year study that tracked people who were bound to be diagnosed with Alzheimer's, as well as those with mild memory declines and healthy control participants. The algorithm was trained on 90 percent of the data and tested on the remaining 10 percent. It was then retested on a second, independent data set from 40 patients monitored for 10 years. The algorithm was highly sensitive and was able to recognize 81 percent of the patients in the first test group and 100 percent in the second who would be diagnosed with Alzheimer's six years later, on average. The findings were published in February in Radiology.

The algorithm is based on "deep learning, a machine-learning technique that uses artificial neural networks programmed to learn from examples. "This is one of the first promising, initial applications of deep learning to the diagnosis of Alzheimer's, " says Christian Salvatore, a physicist at Italy's National Research Council, who was not involved in the study. "The model performs very well when identifying patients with mild or late diagnoses", he says, "but catching it in the earliest st ages remains one of the most critical open issues in this field. "

Have you ever heard of “children of the stars”? It might sound mysterious, but the expression refers to children with autism (自闭症). World Autism Awareness Day falls on April 2. It was initiated by the United Nations to raise awareness and promote acceptance of people with autism.

According to the US-based Autism Research Institute, autism is a disorder with symptoms (症状) that appear within the first three years of life. The condition is believed to involve deficits (缺陷) in social communication and interaction as well as restricted, repetitive behaviors, interests, or activities.

Meng Lingdi, whose daughter was diagnosed (诊断) with autism at 2 years old, shared that her daughter wouldn’t pay attention to her when Meng asked her to do something. “She made less eye contact with people compared to other kids,” Meng added.

Children with autism also suffer from physical pain. “Many children with autism experience epilepsy (癫痫) due to differences in brain activity,” said Sun Zhongkai at Beijing Stars and Rain Education Institute for Autism. Epilepsy among people with autism becomes even more prevalent (普遍的) starting from adolescence (青春期), he added.

At present, the precise cause of autism remains unknown, but research indicates that it is likely a result of a mix of developmental, genetic (遗传的), and environmental factors.

“According to our statistics, older parents are more likely to have autistic children than younger parents,” said Sun. “If the first child in a family has autism, the chances of subsequent children also having autism are about 10 times higher than in families where the first child is not autistic. The likelihood of identical twins both having autism is also significant.”

Although autism is a lifelong condition, there are various treatments available. According to Liu Wei, a teacher at the institute with 20 years of experience in teaching people with autism, it is crucial not to view people with autism with a sense of strangeness. Affirmations (肯定) from others will make them feel proud, enabling them to interact with others more effectively. For those close to autism sufferers, such as friends or family, it’s useful to establish certain principles for the individual, such as what is permissible and what is not. They should also have a deep understanding of autism and how to deal with it, which, for children with autism, may “benefit them for a lifetime,” said Sun.