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Six feet not far enough to stop virus transmission in light winds

Shorter adults and children could be at higher risk if they are located within the trajectory of the traveling saliva droplets.

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Photo by Elena Mozhvilo from Unsplash.com

Airborne transmission of viruses, like the virus causing COVID-19, is not well understood, but a good baseline for study is a deeper understanding of how particles travel through the air when people cough.

In a paper published in Physics of Fluids, from AIP Publishing, Talib Dbouk and Dimitris Drikakis discovered that with even a slight breeze of 4 kph, saliva travels 18 feet in 5 seconds.

“The droplet cloud will affect both adults and children of different heights,” Drikakis said. “Shorter adults and children could be at higher risk if they are located within the trajectory of the traveling saliva droplets.”

Saliva is a complex fluid, and it travels suspended in a bulk of surrounding air released by a cough. Many factors affect how saliva droplets travel, including the size and number of droplets, how they interact with one another and the surrounding air as they disperse and evaporate, how heat and mass are transferred, and the humidity and temperature of the surrounding air.

To study how saliva moves through air, Dbouk and Drikakis created a computational fluid dynamics simulation that examines the state of every saliva droplet moving through the air in front of a coughing person. Their simulation considered the effects of humidity, dispersion force, interactions of molecules of saliva and air, and how the droplets change from liquid to vapor and evaporate.

The computational domain in the simulation is a grid representing the space in front of a coughing person. The analysis involved running partial differential equations on 1,008 saliva droplets and solving approximately 3.7 million equations in total.

“Each cell holds information about variables like pressure, fluid velocity, temperature, droplet mass, droplet position, etc.,” Dbouk said. “The purpose of the mathematical modeling and simulation is to take into account all the real coupling or interaction mechanisms that may take place between the main bulk fluid flow and the saliva droplets, and between the saliva droplets themselves.”

Further studies are needed to determine the effect of ground surface temperature on the behavior of saliva in air and to examine indoor environments, where air conditioning significantly affects the particle movement through air.

“This work is vital, because it concerns health and safety distance guidelines, advances the understanding of spreading and transmission of airborne diseases, and helps form precautionary measures based on scientific results,” said Drikakis.

The article, “On coughing and airborne droplet transmission to humans,” is authored by Talib Dbouk and Dimitris Drikakis. The article will appear in Physics of Fluids on May 19, 2020.

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Cardio-fitness cuts death and disease by nearly 20%

Running, cycling, or swimming – if you regularly exercise, you’re on track for a long and healthy life.

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Running, cycling, or swimming – if you regularly exercise, you’re on track for a long and healthy life.

This is according to a study – “Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses representing over 20.9 million observations from 199 unique cohort studies” – that was published in the British Journal of Sports Medicine.

The study comprised of 26 systematic reviews with meta-analysis representing more than 20.9 million observations from 199 unique cohort studies. It is the first study to collate all the scientific evidence that looked at the prospective link between cardiorespiratory fitness and health outcomes among adults.

The study found that:

  • for every 1-MET increase in cardiorespiratory fitness – the amount of energy used for quiet sitting – a person can reduce their risk of death by 11-17%, and specifically, their risk of heart disease by 18%.
  • an increased cardio fitness level will reduce your risk of death from any cause by 11-17%.

Senior author Grant Tomkinson said that cardiorespiratory fitness is probably the most important type of fitness for good health. “Cardiorespiratory fitness (or CRF) is your ability to perform physical activity for a long period of time like running, cycling, and swimming. And in this study, we found prolonged cardiorespiratory fitness is strongly and consistently associated with all types of premature death and incident disease – spanning heart failure, depression, diabetes, dementia and even cancer.”

Tomkinson added that the researchers “summarized the evidence linking CRF to numerous health outcomes and found that those with low levels of CRF are far more likely to die early or develop chronic conditions like heart disease later in life.” Specifically, “we found that every 1-MET increase in CRF, which is the amount of energy used when sitting quietly, reduced the risk of early death from any cause and heart failure by 11–17% and 18%, respectively. For most people, a 1-MET increase in CRF can be achieved through a regular aerobic exercise program.”

For Tomkinson, the message is quite simple: if you do a lot of “huff and puff” exercise, then your risk of dying early or developing diseases in the future is reduced. If you avoid exercise your health may suffer.

Chronic health conditions are an ongoing cause of poor health, disability, and premature death. In Australia, an estimated 11.6 million people (47%) have a chronic and debilitating health conditions, which contributes to two thirds of the burden of disease.

“Clearly, cardiorespiratory fitness is as an important factor for good health. If you are already exercising, this is good news; but if you know you need to up your fitness and movement, then this is a timely reminder,” co-author Dr Justin Lang said.

“People can make meaningful improvements through additional moderate physical activity, such as brisk walking, at least 150 minutes a week. And as they improve their fitness, their risk of death and disease will decline. But the onus for improvement should not just sit with the individual, it should also be routinely assessed in clinical and public health practice, so that we can support people to improve their health outcomes,” Lang added.

Through regular assessment, clinicians and exercise professionals could better identify adults at greater risk of early death and initiate exercise programs aimed at increasing CRF through regular physical activity.

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Natural therapy shows promise for dry-eye disease

Castor oil has been proposed as a natural product that could offer a safe, effective and easy-to-use alternative to existing therapies.

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Researchers at the University of Auckland are running a trial of castor oil as a potential safe and natural treatment for dry-eye disease following a successful pilot study.

While exact figures aren’t available for New Zealand, in Australia, it is estimated dry-eye disease affects around 58% of the population aged over 50. Advancing age, menopause, increased screen time, contact lens wear are just some of the risk factors for developing dry eye disease.

Blepharitis is the most common cause of dry-eye disease, accounting for more than 80 percent of cases. It is a chronic condition with no known cure.

“Currently, patients are left grappling with symptoms of dryness, grittiness and, in some cases, watery eyes that feel uncomfortable impacting on their quality of life and work productivity,” says doctoral candidate and lead clinical investigator Catherine Jennings.

Current treatments, such as antibacterials and anti-inflammatories, are generally unsuitable for long-term use, due to significant side-effects and potential for antimicrobial resistance.

“Often patients are left feeling helpless when attempting to manage a chronic condition,” Jennings says.

The current trial is of a product containing cold-pressed castor oil enhanced with mānuka and kanuka oils applied using a rollerball attached to a small glass bottle.

“The previous pilot study, conducted by our research team, was unique in its use of castor oil in such an application on the eyelids, with the product not known to be used anywhere else in the world for treating blepharitis,” says Jennings.

Castor oil comes from a flowering tropical or subtropical shrub from the species Riccinus communis. It has been used therapeutically for millenia, including more recently in eye cosmetics and eye makeup removers.

In the pilot study, 26 patients with blepharitis were treated with cold-pressed castor oil over four weeks. They had measurable improvements in symptoms, such as reduced redness of the lid margin, decreased thickening of the eyelid, and a decline in bacterial profusion, as well as reduced eyelash crusting.

Building on the success of the pilot study, the research team is now engaged in the more extensive double-blinded, randomised and placebo-controlled study. They are aiming to recruit 92 participants and generate robust scientific evidence for clinicians.

The ultimate goal is to sustainably improve quality of life for this large group of patients using a natural, safe and effective product, principal investigator Professor Jennifer Craig says.

“Castor oil has been proposed as a natural product that could offer a safe, effective and easy-to-use alternative to existing therapies,” Craig says.

“My hope is this study will produce evidence-based guidance for clinicians with regard to offering castor oil as a possible management option for patients suffering from blepharitis, so they continue to enjoy a great quality of life, read the books they love, be productive in their work environment and enjoy other visual hobbies.”

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For epilepsy, yoga may be good for your mind

People who did yoga were more than four times as likely to have more than a 50% reduction in their seizure frequency after six months than the people who did sham yoga.

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For people with epilepsy, doing yoga may help reduce feelings of stigma about the disease along with reducing seizure frequency and anxiety, according to new research published in the November 8, 2023, online issue of Neurology, the medical journal of the American Academy of Neurology.

“People with epilepsy often face stigma that can cause them to feel different than others due to their own health condition and that can have a significant impact on their quality of life,” said study author Manjari Tripathi, MD, DM, of All India Institute of Medical Sciences in New Delhi. “This stigma can affect a person’s life in many ways including treatment, emergency department visits and poor mental health. Our study showed that doing yoga can alleviate the burden of epilepsy and improve the overall quality of life by reducing this perceived stigma.” 

For the study, researchers looked at people with epilepsy with an average age of 30 in India.

Researchers measured stigma based on participants’ answers to questions such as: “Do you feel other people discriminate against you?” “Do you feel you cannot contribute anything in society?” and “Do you feel different from other people?”

Researchers then identified 160 people who met the criteria for experiencing stigma. Participants had an average of one seizure per week and on average took at least two anti-seizure medications.

Researchers then randomly assigned participants to receive yoga therapy or sham yoga therapy. Yoga therapy included exercises in loosening muscles, breathing, meditation and positive affirmations. Sham yoga consisted of exercises that mimic the same yoga exercises, but participants were not given instructions on two key components of yoga believed to induce a relaxation response: slow and synchronized breathing, and attention to the body movements and sensations during practice.

Each group received seven supervised group sessions of 45 to 60 minutes over three months. Participants were also asked to practice sessions at home at least five times a week for 30 minutes. They tracked seizures and yoga sessions in a journal. After the three months of therapy, participants were followed for another three months.

Researchers found when compared to people who did sham yoga, people who did yoga were more likely to reduce their perceived stigma of the disease. People who did yoga had an average score of seven at the start of the study and an average score of four at the end of the study, while people who did sham yoga had an increase from an average score of six at the start of the study to an average score of seven at the end.

Researchers also found that people who did yoga were more than four times as likely to have more than a 50% reduction in their seizure frequency after six months than the people who did sham yoga.

In addition, people who did yoga were more than seven times more likely to no longer have seizures than those who did sham yoga.

There was also a significant decrease in anxiety symptoms for people who did yoga versus people who did not. They saw improvements in quality of life measures and mindfulness.

“These study findings elevate the need to consider alternative therapies and activities for people with epilepsy facing stigma,” said Tripathi. “Yoga may not only help reduce stigma, but also improve quality of life and mindfulness. Plus, yoga can be easily prerecorded and shared with patients online using minimal resources and costs.”

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