Scientists finally work out how clapping hands generates sound

A study has unravelled the physics behind the sound of hand claps, revealing it's more complex than just hands hitting each other.
The sound is generated by a pocket of air compressed between the hands and rapidly expelled, causing air molecules to vibrate, similar to the Helmholtz resonance principle.
Researchers used live experiments, theoretical modelling, and silicone replicas of hands, modifying speed, shape, and skin softness to understand clapping.
The elasticity of hands causes energy absorption, resulting in a short "pop" sound rather than a longer noise.
Researchers suggest clapping could potentially be used for human identification due to the unique sound and frequency of each person's clap.

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Daily Mail​

2 hours ago

• Daily Mail​

Study pinpoints exact number of coffees per day that can cut the risk of sudden cardiac death

A coffee a day might be enough to keep the doctor away. For US researchers have found coffee lovers tend to have healthier hearts, putting them at lower risk of cardiac death. And the benefits can be achieved by drinking just one cup a day, they claimed—but only if they drink it black. Those who drank between two to three cups, however, saw the most benefits, slashing their risk by almost a fifth. The findings, from the study of more than 46,000 people, add to the growing body of evidence highlighting the drink's health benefits. Professor Fang Fang Zhang, a nutrition expert at Tufts University in Boston, said: 'Coffee is among the most-consumed beverages in the world, and with nearly half of American adults reporting drinking at least one cup per day, it's important for us to know what it might mean for health.' Some research has already linked coffee to reducing the risk of heart disease, heart failure and strokes, while other studies report it prolongs life. But medics remain divided, warning that excessive amounts of coffee—packed full of caffeine—can actually damage the heart. The new study, in The Journal of Nutrition, tracked the daily coffee consumption of 46,332 people over the age of 20. Over a follow up of 11 years, they found black coffee and coffee with low levels of added sugar and saturated fat—like milk or cream—had a 14 per cent lower risk of death compared to no coffee consumption. But one cup of black coffee a day, specifically, slashed the risk of death including cardiovascular death, by 16 per cent. Those who drank between two and three a day saw the risk lowered by 17 per cent. However, researchers noted that the benefits peaked at three cups a day. They also found that those who added high amounts of sweeteners and dairy to their coffee did not experience the same benefits. Researchers acknowledged, however, that the coffee consumption was self-reported by volunteers, so may have been underreported, limiting the findings. It was also assessed without detailing the roast used and preparation methods. NHS data shows a rise in the number of younger adults suffering from heart attacks over the past decade. The biggest increase (95 per cent) was recorded in the 25-29 year-old demographic, though as numbers of patients are low even small spikes can look dramatic Under NHS guidance, consuming more than four cups a day can increase blood pressure. Around 2million people in the UK are diagnosed with some form of heart disease, according to Government figures. But charities estimate that a further six million have undiagnosed high blood pressure—one of the leading risk factors for stroke and heart attack. Heart disease describes a range of conditions that affect the heart and blood vessels. It's often caused by fatty deposits in the arteries that can make it harder for blood and oxygen to flow properly through the vessels and to and from the heart. This increases the risk of a blockage, and therefore stroke or heart attack. Last year, alarming data revealed that premature deaths from cardiovascular problems, such as heart attacks and strokes, had hit their highest level in more than a decade. MailOnline has previously highlighted how the number of young people, under 40, in England being treated for heart attacks by the NHS is on the rise. Cases of heart attacks, heart failure and strokes among the under-75s has tumbled since the 1960s thanks to plummeting smoking rates, advanced surgical techniques and breakthroughs such as stents and statins. But now, rising obesity rates, and its catalogue of associated health problems such as high blood pressure and diabetes, are thought to be one of the major contributing factors.

The Guardian

3 hours ago

• The Guardian

Do electric vehicles make people more carsick?

With electric cars skyrocketing in popularity around the world – in 2024, 22% of new car sales worldwide were electric vehicles, compared with 18% in 2023 – a growing body of studies and an increasing number of people have found that they feel more motion sick riding in EVs than in traditional petrol or diesel cars. Anecdotes of feeling sick in the passenger or back seat of electric cars litter social media, as do questions from wary prospective buyers. There is a scientific explanation behind why a person might feel more sick in an EV, though, according to multiple academic studies. 'Greater sickness in EVs can be attributed to a lack of previous experience, as both a driver and as a passenger, where the brain lacks accuracy in estimating the motion forces because it relies on previous experience in other types of cars,' said William Emond, a PhD student researching car sickness at the Université de Technologie de Belfort-Montbéliard in France. Though EVs are becoming more popular, combustion cars still dominate. Riders have a longer history with gas cars and so have had more time to adapt to their specific cues. If a person has spent most of their life driving a combustion engine car, their brain anticipates acceleration after the rev of the engine, a warning that they are about to experience a change in speed. In a battery-powered car, the electric motor makes no such noises. In addition to general unfamiliarity, research has found links between specific features common to electric vehicles and motion sickness. One 2024 study concluded that there were strong correlations between motion sickness severity and the seat vibrations of electric vehicles, while a 2020 study found that the lack of engine sound in an EV might be a major contributing factor to increased feelings of carsickness. 'If we are accustomed to traveling in non-EVs, we are used to understanding the car's motion based on signals such as engine revs, engine vibrations, torque, etc. Yet, traveling in an EV for the first time is a new motion environment for the brain, which needs adaptation,' Emond explains. Additionally, the regenerative braking technology used in EVs – where the motor converts the slowing car's kinetic energy into electricity that then is stored in the battery – results in low-frequency deceleration, meaning that the vehicle slows down gradually and steadily, over a relatively longer period, rather than rapidly or in quick pulses. Such low-frequency deceleration tends to be associated with higher levels of motion sickness. A 2024 study suggested the feature acted as one of the main triggers of motion sickness in electric vehicles. The study's authors wrote: 'Our results confirmed that higher levels of RB [regenerative braking] can induce MS [motion sickness].' Motion sickness is thought to be caused by a mismatch between various sensory signals the brain simultaneously receives about the body's movement. Specifically, it happens when the inner ear, which helps control balance, the eyes, and the body send conflicting information to the brain. 'Better knowledge on self-motion allows us to anticipate motion forces, which is crucial for motion sickness. Yet, when the motion forces as estimated or anticipated by the brain differ from what actually is experienced, then the brain interprets this 'neural mismatch' as a situation of conflict,' Emond said. 'If this conflict persists over time, it may surpass a threshold for triggering autonomic reactions of the body such as symptoms apparent to 'motion sickness'.' Being able to anticipate the movement of a vehicle appears to be integral to the experience of motion sickness, which is why people who are driving a car don't tend to experience symptoms. They know what is coming. The interplay between anticipation of motion and actual motion experienced may be why EVs are associated with worse motion sickness, as these vehicles provide fewer clues regarding upcoming movements. 'When discovering a new motion environment, the brain needs to habituate because there is no knowledge of previous experience in such a context. This is, for example, why almost everyone becomes sick in zero-gravity environments,' Emond says. As EV ownership continues to increase, some researchers are already looking into a solution for the cars' specific type of nausea. Several research papers have suggested that motion sickness in autonomous EVs could be treated by using visual signals, such as interactive screens and ambient lighting, or vibrational cues to allow a passenger's brain to anticipate motion changes, alleviating the lurching feeling in the back of an electric taxi.

Medical News Today

4 hours ago

• Medical News Today

Modified DASH diet may reduce blood pressure in people with type 2 diabetes

Many people with diabetes also have high blood pressure, as well as unique nutritional study found that reducing sodium intake and following a modified version of the DASH diet helped to decrease blood pressure in participants with type 2 main reason for the observed decrease in blood pressure was the decreased sodium is common for people with diabetes to also experience high blood pressure. A study tested how a modified version of the DASH diet that focused on the nutritional needs of people with type 2 diabetes, combined with minimizing sodium intake, affected blood pressure dietary combination lowered systolic blood pressure among participants by around five points and diastolic blood pressure by around two points compared to the comparison diet with more sodium. This result was mainly from the decreased sodium findings were published in JAMA Internal DASH4D diet for blood pressure management The dietary approaches to stop hypertension (DASH) diet is a diet for heart health. Study author Scott J. Pilla, MD, MHS, explained to Medical News Today that 'The DASH diet is a healthy diet that is rich in fruits, vegetables and low-fat dairy products, and is lower in saturated fat and cholesterol.'However, the study notes that the DASH diet doesn't consider the unique dietary needs of people with type 2 diabetes. So, researchers created the 'Dietary Approaches to Stop Hypertension for Diabetes (DASH4D) diet,' which is similar to the DASH diet but considers what adults with type 2 diabetes need. For example, this diet was lower in carbohydrates than the typical DASH diet. Researchers tested how this diet, combined with decreased sodium intake, affected participants' blood randomized clinical trial included 102 adults with type 2 diabetes whose systolic blood pressure was between 120 and 159 mmHg. Participants were designated as having type 2 diabetes if they had a hemoglobin A1C of 6.5% or greater, were taking medications for diabetes treatment, or were ineligible to participate in the study for a number of reasons, including having type 1 diabetes, if their A1C was over 9%, or if they were taking weight loss average age of participants was 66 years. About two-thirds of participants used at least two medications to help lower blood pressure, and a little over half used at least two medications to lower blood 4 different dietsResearchers assigned participants to receive four diets in varying orders, each for five weeks. One was a DASH4D diet with low sodium, and another was the DASH4D diet but with higher sodium intake. The other two were comparison diets: one with lower sodium and one with higher sodium, and these diets were similar to the intake of adults with diabetes living in the United States. The participants were provided with the food for their assigned diets, and aside from allowed beverages, they were not supposed to eat food from other sources outside the did not lose weight throughout the study. Researchers measured systolic blood pressure during the last two weeks of each diet intervention. They kept track of adverse events among participants, such as any very high blood pressure self-reported how well they stuck to their assigned diets, but researchers also did a 24-hour urine excretion test during the fourth or fifth weeks to look at sodium, creatinine, and potassium levels, which also was a way to test how well participants were following diet findings showed that the lowering of blood pressure mostly occurred during the first three weeks of participants following a diet. The researchers found that the DASH4D diet with reduced sodium showed a better overall decrease in blood pressure versus the comparison diet that had higher sodium intake. The average difference in systolic blood pressure between these two groups was 4.6 mmHg, and the average difference in diastolic blood pressure was 2.3 mmHg.'The main finding was that a low-sodium DASH4D diet (compared to a higher sodium typical American diet) caused a statistically and clinically significant reduction in blood pressure. Sodium reduction appeared to contribute more strongly to reducing blood pressure than the DASH4D diet.'— Scott J. Pilla, MDJennifer Wong, MD, a board-certified cardiologist and medical director of Non-Invasive Cardiology at MemorialCare Heart and Vascular Institute at Orange Coast Medical Center in Fountain Valley, CA, also noted that 'Studies like these remind us of the beneficial impact of a heart-healthy diet, especially a low salt diet designed to modify blood pressure.'Study limitations This research only included a small number of participants and focused on a niche subgroup of individuals, limiting generalizability. The majority of participants were Black, which provided important information about this at-risk group. Two-thirds of the participants were women. However, research in other groups may also be dietary interventions for this study each only lasted five weeks, so long-term follow-up may be helpful with further data, such as following the assigned diet and health history, was self-reported by participants, so inaccuracies are adverse events on the DASH4D diet with low sodium were low, more research into the potential risks may be helpful. Researchers also suggest the need for more research in people with a higher level of risk. The amount that blood pressure was lowered by could have been less in this study for many reasons, such as the high number of participants taking diuretics and the number of participants who experienced changes to their blood pressure medications during the acknowledge that they weren't able to detect the separate impact of the DASH4D diet and decreased sodium intake. Another struggle was the COVID-19 pandemic. The authors explain that this 'interrupted participant feeding at several points.' It was also only a single-site also noted that 'More work is needed on how to make healthy, low sodium diets accessible. Following a healthy diet can be challenging and costly, and we would like to design diets that meet the DASH4D nutrient targets that are more affordable and tailored to different cultures.'Researchers note that it may be hard to decrease sodium intake to only 1,500 mg a day, and future research in this area will be helpful. The authors say this research should include 'implementation research in community settings.'Should I follow a DASH4D diet if I have diabetes?The result suggests that the DASH4D eating plan combined with lower sodium intake helps with blood pressure reduction in people with type 2 diabetes. Researchers note that a five mmHg reduction in systolic blood pressure can decrease the risk of stroke, heart failure, and cardiovascular events. It can also help with kidney noted the following regarding the clinical implications of the study:'Diet change can effectively improve blood pressure in people with diabetes, even those on multiple antihypertensive medications, so clinicians should still focus on diet even in these individuals.''Dietary sodium reduction is an important part of dietary change in people with diabetes to achieve better blood pressure control. Our specific DASH4D diet with lower sodium now has strong evidence for benefiting people with diabetes, so it should be strongly considered as a recommended diet in this population.'— Scott J. Pilla, MDEven though there may be a need for more research, Patrick Kee, MD, PhD, a cardiologist at Vital Heart & Vein, noted the following about the study's results:'The acceptability and adherence to the lower sodium intake (~1500 mg/day) was high among participants, suggesting that with proper guidance and access to prepared meals or education, such dietary targets are feasible in practice. This finding counters a long-standing belief that stringent sodium targets may be unrealistic for patients.'