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What Happens When Water Comes in Contact With Your Touchscreen

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When they work, touchscreens can make you feel like you've got the future in the palm of your hand. When they don’t, trying to use one can make you feel like a bit of a lunatic. If you’ve ever wondered how a small droplet of sweat can confuse such a high-tech interface, the answer lies in electrical charges.

In their latest issue, Popular Science explores the science behind what’s happening when your phone’s screen comes in contact with water. A touchscreen works by measuring the charges going across its grid of ultra-thin electrodes. Because your body is made primarily from highly-conductive water, when you press your finger to your screen it absorbs some of that charge. The phone is able to pinpoint your finger’s location on the screen’s grid by calculating how much the charge drops between two of the intersecting electrodes.

If traces of sweat or rain are present, that can also reduce the charge and confuse your phone's touchscreen. Engineers have tried tackling this problem in recent years by implementing a different approach to touch-sensing technology. “Self-capacitance” measures an increase in charge between an electrode on the screen and the ground you’re standing on, rather than just measuring the charge between two electrodes. Any water that ends up on your screen won't be grounded, which makes it easier for your phone to differentiate between water droplets and a finger. 

Using this method alone wouldn’t be very effective because the signal corresponds to whole rows or columns instead of just individual points on the grid. Actions that require multiple touches like zooming in or out could cause the screen to respond to points that aren’t really there. To solve this, some phones have combined the classic sensing method with the newer, waterproof one. By registering both types of signals, a screen can respond to multi-touch gestures and account for moisture at the same time. The next time your phone responds to your sweaty fingers, you know exactly which kind of tech to thank.

[h/t: Popular Science]

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New Patient Test Could Suggest Whether Therapy or Meds Will Work Better for Anxiety
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Like many psychological disorders, there's no one-size-fits-all treatment for patients with anxiety. Some might benefit from taking antidepressants, which boost mood-affecting brain chemicals called neurotransmitters. Others might respond better to therapy, and particularly a form called cognitive behavioral therapy, or CBT.

Figuring out which form of treatment works best often requires months of trial and error. But experts may have developed a quick clinical test to expedite this process, suggests a new study published in the journal Neuropsychopharmacology.

Researchers at the University of Illinois at Chicago have noted that patients with higher levels of anxiety exhibit more electrical activity in their brains when they make a mistake. They call this phenomenon error-related negativity, or ERN, and measure it using electroencephalography (EEG), a test that records the brain's electric signals.

“People with anxiety disorders tend to show an exaggerated neural response to their own mistakes,” the paper’s lead author, UIC psychiatrist Stephanie Gorka, said in a news release. “This is a biological internal alarm that tells you that you've made a mistake and that you should modify your behavior to prevent making the same mistake again. It is useful in helping people adapt, but for those with anxiety, this alarm is much, much louder.”

Gorka and her colleagues wanted to know whether individual differences in ERN could predict treatment outcomes, so they recruited 60 adult volunteers with various types of anxiety disorders. Also involved was a control group of 26 participants with no history of psychological disorders.

Psychiatrists gauged subjects’ baseline ERN levels by having them wear an EEG cap while performing tricky computer tasks. Ultimately, they all made mistakes thanks to the game's challenging nature. Then, randomized subjects with anxiety disorders were instructed to take an SSRI antidepressant every day for three months, or receive weekly cognitive behavioral therapy for the same duration. (Cognitive behavioral therapy is a type of evidence-based talk therapy that forces patients to challenge maladaptive thoughts and develop coping mechanisms to modify their emotions and behavior.)

After three months, the study's patients took the same computer test while wearing EEG caps. Researchers found that those who'd exhibited higher ERN levels at the study's beginning had reduced anxiety levels if they'd been treated with CBT compared to those treated with medication. This might be because the structured form of therapy is all about changing behavior: Those with enhanced ERN might be more receptive to CBT than other patients, as they're already preoccupied with the way they act.

EEG equipment sounds high-tech, but it's relatively cheap and easy to access. Thanks to its availability, UIC psychiatrists think their anxiety test could easily be used in doctors’ offices to measure ERN before determining a course of treatment.

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Newly Discovered 350-Year-Old Graffiti Shows Sir Isaac Newton's Obsession With Motion Started Early
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Long before he gained fame as a mathematician and scientist, Sir Isaac Newton was a young artist who lacked a proper canvas. Now, a 350-year-old sketch on a wall, discovered at Newton’s childhood home in England, is shedding new light on the budding genius and his early fascination with motion, according to Live Science.

While surveying Woolsthorpe Manor, the Lincolnshire home where Newton was born and conducted many of his most famous experiments, conservators discovered a tiny etching of a windmill next to a fireplace in the downstairs hall. It’s believed that Newton made the drawing as a boy, and may have been inspired by the building of a nearby mill.

A windmill sketch, believed to have been made by a young Sir Isaac Newton at his childhood home in Lincolnshire, England.
A windmill sketch, believed to have been made by a young Sir Isaac Newton at his childhood home in Lincolnshire, England.
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Newton was born at Woolsthorpe Manor in 1642, and he returned for two years after a bubonic plague outbreak forced Cambridge University, where he was studying mechanical philosophy, to close temporarily in 1665. It was in this rural setting that Newton conducted his prism experiments with white light, worked on his theory of “fluxions,” or calculus, and famously watched an apple fall from a tree, a singular moment that’s said to have led to his theory of gravity.

Paper was a scarce commodity in 17th century England, so Newton often sketched and scrawled notes on the manor’s walls and ceilings. While removing old wallpaper in the 1920s and '30s, tenants discovered several sketches that may have been made by the scientist. But the windmill sketch remained undetected for centuries, until conservators used a light imaging technique called Reflectance Transformation Imaging (RTI) to survey the manor’s walls.

Conservators using light technology to survey the walls of Woolsthorpe Manor,  the childhood home of Sir Isaac Newton.
A conservator uses light technology to survey the walls of Woolsthorpe Manor, the childhood home of Sir Isaac Newton.
National Trust

RTI uses various light conditions to highlight shapes and colors that aren’t immediately visible to the naked eye. “It’s amazing to be using light, which Newton understood better than anyone before him, to discover more about his time at Woolsthorpe,” conservator Chris Pickup said in a press release.

The windmill sketch suggests that young Newton “was fascinated by mechanical objects and the forces that made them work,” added Jim Grevatte, a program manager at Woolsthorpe Manor. “Paper was expensive, and the walls of the house would have been repainted regularly, so using them as a sketchpad as he explored the world around him would have made sense," he said.

The newly discovered graffiti might be one of many hidden sketches drawn by Newton, so conservators plan to use thermal imaging to detect miniscule variations in the thickness of wall plaster and paint. This technique could reveal even more mini-drawings.

[h/t Live Science]

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