Happy July 1, 2024, also known as, Canada Day!

Onto breakdancing (or breaking), which for the first time will be an official event at the 2024 Paris Summer Olympics. Amy Pope, principal lecturer, physics and astronomy, Clemson University (South Carolina, US), has written a June 12, 2024 essay for The Conversation that describes breakdancing as physics in action, (h/t June 13, 2024 news item in phys.org), Note: Links have been removed,

Two athletes square off for an intense dance battle. The DJ starts spinning tunes, and the athletes begin twisting, spinning and seemingly defying gravity, respectfully watching each other and taking turns showing off their skill.

The athletes converse through their movements, speaking through a dance that celebrates both athleticism and creativity. While the athletes probably aren’t consciously thinking about the physics behind their movements, these complex and mesmerizing dances demonstrate a variety of different scientific principles.

Breaking, also known as breakdancing, originated in the late 1970s in the New York City borough of the Bronx. Debuting as an Olympic sport in the 2024 Summer Olympics, breaking will showcase its dynamic moves on a global stage. This urban dance style combines hip-hop culture, acrobatic moves and expressive footwork.

Since its inception, breaking has evolved into a competitive art form. An MC narrates the movements, while a DJ mixes songs to create a dynamic atmosphere. The Olympics will feature two events: one for men, called B-boys, and one for women, called B-girls. In these events, athletes will face off in dance battles.

… Success in this sport requires combining dance moves from three basic categories: top rock, down rock and freeze.

…

And now for the physics of it all, from Pope’s June 12, 2024 essay, Note: Links have been removed,

…

Top rock moves [emphasis mine] are performed while standing up, focusing on fancy footwork and hand movements. These movements are reminiscent of hip-hop dancing.

Top rock moves rely on having lots of friction between an athlete’s shoes and the floor. Friction is the force [emphasis miine] that resists when you slide something across a surface.

This friction allows the athlete to take very quick steps and to stop abruptly. The dancers must intuitively understand inertia, or the fact that their bodies will continue in the direction they’re moving unless they are acted upon by an external force. To stop abruptly, athletes need to engage their muscles, getting their shoes to grip the ground to stop themselves from continuing forward.

…

Down rock moves [emphasis mine] are performed while on the floor. Athletes may spin in circles with their head, back, elbows or shoulders touching the ground and their feet in the air. B-boys and B-girls rely heavily on an internal knowledge of physics to complete these moves.

Consider the physics of a backspin. A backspin occurs when the athlete is on their back with their feet lifted in the air, rotating around a specific area of their back.

Sitting on the floor, the athlete’s left foot stays in contact with the floor while they spread their right leg wide, gathering linear momentum [emphasis mine] as they sweep their right leg toward their left foot in a wide arc. Then, they release their left leg from contact with the ground and roll onto their back.

Now that only their back is in contact with the ground, the linear momentum from their leg turns into angular momentum [emphasis mine], which rotates the athlete around an axis that extends upward from their back’s contact point with the ground. This move turns magical when they bring their legs and arms inward, toward the axis of rotation. This principal is called conservation of angular momentum.

When an athlete brings their mass in more closely to the axis of rotation, the athlete’s rotations speed up. Extending their legs and arms once again and moving their mass away from the axis of rotation will cause the competitor to slow their rotation speed down. Once they slow down, they can transition to another move.

…

Freeze [emphasis mine] occurs when athletes come to a stop in a funky pose, often occurring in time to the music and in an upside-down position. To freeze effectively, the athlete must have full control over their center of mass, placing it right above the point of their body that is in contact with the floor. The center of mass is the average position of all the parts of an athlete, weighted according to their masses. The “balance point” where the entire mass of the athlete seems to be concentrated is the center of mass.

Athletes are most stable when their center of mass is as close to the ground as possible. You will see many competitors freeze with arms bent in an effort to lower their center of mass. This lowered center of mass reduces their distance from the floor and minimizes the tendency of their body to rock to one side or the other due to torque.

Torque is a twisting force [emphasis mine], like the force used to turn a wrench. The torque depends on two things: the amount of force you apply, and how far from the pivot point you apply the force. With an athlete’s center of mass closer to the ground, the athlete decreases the distance between the pivot point – the ground – and where the force of gravity is applied – the athlete’s center of mass.

Athletes need great strength to halt their motion mid-movement because they have to apply a force to resist the change in inertia.

…

It’s not just about the moves, clothing is a factor, Pope’s June 12, 2024 essay,

Many sports require a specific uniform. Breaking doesn’t – an athlete can wear whatever they want – but the right outfit will maximize their chance of success.

The athlete wants a shirt that minimizes the friction between their body and the ground during a spin. Lettering or images on the back of the shirt will add friction, which hinders an athlete’s ability to perform some down rock moves. An athlete may choose to wear long sleeves if they plan to slide on their elbows, as bare skin in contact with the floor provides more friction.

Athletes also have to think about the headgear they wear. …

There’s a bit more information about the breakdancing competition on the 2024 Olympics website.I cannot find a full list of athletes for the August 9, 2024 (B-Girls) and August 10, 2024 (B-Boys) competitions. There is this June 2, 2024 article (from the Associated Press) on the CBC (Canadian Broadcasting Corporation) online news website,

…

Victor Montalvo (B-boy Victor), United States: A breaker who describes himself as a student of old school b-boys from the founding era of hip-hop, the 30-year-old Montalvo, who is from Kissimmee, Florida, qualified for Paris by besting all other b-boys at the 2023 WDSF World Breaking Championship in Belgium.

Sunny Choi (B-girl Sunny), United States: The 35-year-old Choi, a cheerful Queens, New York-bred breaker, has long been an ambassador for b-girls globally. She qualified for the Paris Games with her win at the 2023 Pan American Games in Chile.

Philip Kim (B-boy Phil Wizard), Vancouver, Canada: Consistently ranked in the top three b-boys in the international breaking competitive community, Kim secured a spot for Paris when he came out on top at last year’s Pan American Games.

Dominika Banevič (B-girl Nicka), Lithuania: Banevič was the youngest in her category at last year’s WDSF World Breaking Championship, when she punched her ticket to Paris. Banevič turns 17 this month.

…

I thought the competition would be dominated by Americans and certainly wasn’t expecting to see a Lithuanian (Dominika Banevič or ‘Nicka’) listed as a competitor to watch. The Canadian (Philip Kim or ‘Phil Wizard’) is also a surprise. Who knew Vancouver was home to a leading B-boy?

Two comments: heat and mosquitoes (dengue and other fevers)

The organizers of the Paris 2024 Summer Olympics are to be complimented for their work towards making the games ‘green’ but that is a complex process.

Heat

For example, the Canadian Broadcasting Corporation (CBC) ran a news item on The National news telecast on June 17, 2024 (see telecast for embedded video clip) regarding concerns about and preparations for heat,

Preparing for extreme heat at the Paris Olympics

Paris Olympic organizers plan to make this summer’s games the greenest ever, but that includes offering less air conditioning to cut down on energy use. [emphases mine] As temperatures rise globally, some suggest the organizers should take extreme heat into account when awarding cities with the next big Olympic games.

Some of the reporting in the CBC news item is based on information from a June 18, 2024 University of Portsmouth (UK) press release, Note: Links have been removed,

Leading athletes are warning that intense heat at the Paris Olympics in July-August 2024 could lead to competitors collapsing and in worst case scenarios dying during the Games. [emphasis mine]

Eleven Olympians, including winners of five World Championships and six Olympic medals, have come together with climate scientists and leading heat physiologists Professor Mike Tipton and Dr Jo Corbett from the University of Portsmouth to unpack the serious threat extreme heat poses for athletes in a new Rings of Fire report.

Dr Corbett, Associate Professor of Environmental Physiology in the School of Sport, Health and Exercise Science at the University of Portsmouth, said: “A warming planet will present an additional challenge to athletes, which can adversely impact on their performance and diminish the sporting spectacle of the Olympic Games,. Hotter conditions also increase the potential for heat illness amongst all individuals exposed to high thermal stress, including officials and spectators, as well as athletes.”

“For athletes, from smaller performance-impacting issues like sleep disruption and last-minute changes to event timings, to exacerbated health impacts and heat related stress and injury, the consequences can be varied and wide-ranging. With global temperatures continuing to rise, climate change should increasingly be viewed as an existential threat to sport,” said Lord Sebastian Coe, President of World Athletics and four-time Olympic medallist.

The Tokyo Games became known as the “hottest in history,” with temperatures exceeding 34°C and humidity reaching nearly 70 per cent, leading to severe health risks for competitors. The Paris Games have the potential to surpass that, with climate change driven by the burning of fossil fuels contributing to record heat streaks during the past months.

2023 was the hottest year on record according to the EU’s [European Union] Copernicus Climate Change Service and 2024 has continued this streak. April 2024 was warmer globally than any previous April in the record books, said experts at Copernicus.

The Rings of Fire report discusses the deadly heatwave in France in 2003 – which killed over 14,000 people – and subsequent years of record-breaking temperatures, exceeding 42°C. It underscores the heightened risk of extreme heat during the Paris Olympics, especially considering the significant rise in the region’s temperatures since the city last hosted the Games a century ago.

…

You can find the Rings of Fire report here and the Corpernicus Climate Change Service here.

Mosquitoes and dengue and other fevers

Obviously, the world is changing as you can see in this June 18, 2024 Institut Pasteur press release (also on EurekAlert),

Olympics: how many days does it take for mosquitoes in Greater Paris to transmit arboviruses, and what preventive measures are needed?

The number of imported cases of dengue in the Greater Paris region increased significantly in the first few months of 2024. In the run-up to the Olympic Games, with huge numbers of international visitors set to come to Paris – especially from endemic dengue countries –, we need to be vigilant. Scientists from the Institut Pasteur, in collaboration with the Regional Mosquito Control Agency (ARD) and the National Reference Center for Arboviruses (Inserm-Irba), have demonstrated that the tiger mosquito, now present in Greater Paris, is capable of transmitting five viruses (West Nile, chikungunya, Usutu, Zika and dengue) within different time frames ranging from 3 to 21 days, at an external temperature of 28°C. These results highlight the importance of stepping up surveillance of imported cases of arboviruses this summer. The study was published on May 16 [2024] in Eurosurveillance.

Between January 1 and April 19, 2024, 1,679 imported dengue cases were reported in mainland France, 13 times more than the number reported over the same period the previous year (source SPF). It is likely that this number will increase during the Olympic Games, as more people come to Paris from countries that are endemic regions for other arboviruses. The vector for dengue transmission is Aedes albopictus, more commonly known as the tiger mosquito. Arboviruses are transmitted when a female mosquito bites a virus carrier and ingests viral particles. One particular feature of arboviruses is that they can replicate in mosquitoes (unlike other viruses such as influenza, which are destroyed when ingested by mosquitoes). The viral particles multiply and spread within the mosquito, reaching the salivary glands in a few days. When the female mosquito bites another human, she injects the virus while taking her blood meal.

The tiger mosquito is now present in 78 départements in mainland France, and this together with other climate change-related factors is facilitating vector-borne transmission. Scientists from the Institut Pasteur’s Arboviruses and Insect Vectors Unit, in collaboration with the Regional Vector Control Agency (ARD) and the National Reference Center for Arboviruses (Inserm-Irba), therefore decided to analyze the ability of Aedes albopictus in Greater Paris to transmit five arboviruses at a temperature of 28°C, which is likely in the region at this time of year, and counted the number of days between initial infection and the possibility of the virus being transmitted through a further mosquito bite. As well as the dengue, chikungunya and Zika viruses, which we already know can be transmitted by the tiger mosquito, the scientists studied the Usutu and West Nile viruses, which are naturally transmitted by another mosquito species, Culex pipiens (known as the “common mosquito”). Culex pipiens mosquitoes transmit viruses to humans after feeding on birds, which act as viral reservoirs.

Tiger mosquito susceptible to five arboviruses

Working in a BSL3 laboratory, the scientists studied the ability of tiger mosquitoes to transmit these five viruses and determined the extrinsic incubation period required for the virus to reach the mosquito’s salivary glands in sufficient quantities to infect a human. At 28°C, West Nile virus needs three days before it can be transmitted to humans by mosquitoes. The incubation period is 3 to 7 days for chikungunya and Usutu, and 14 to 21 days for dengue and Zika.⁽¹⁾ 

This information is crucial to gage the additional risk represented by the upcoming Olympic Games in Paris, which will see significant intermingling of populations combined with the return of travelers from endemic regions and a season conducive to mosquito proliferation. The findings can also be used to develop suitable control strategies.

“If a case of dengue is detected in the Greater Paris region, we now know that disinsection is required within 21 days. We can use these results to adjust our time frame for action and optimize our approach,” explains Anna-Bella Failloux, Head of the Institut Pasteur’s Arboviruses and Insect Vectors Unit, who led the study. “Depending on the temperatures we experience in and around Paris this summer, our findings will be essential for adjusting control measures as needed.”

What precautions should be taken in the run-up to the Olympics?

Health care professionals are trained to detect the symptoms of arboviruses if people indicate that they have recently been to an endemic country. The difficulty of surveillance is that many cases are asymptomatic: although dengue is a notifiable disease, up to 80% of cases lead to few or no symptoms. If a diagnosis of one of these diseases is confirmed, an inquiry is carried out by France’s Regional Health Agencies to determine where the individuals live or spent time in the days before the diagnosis, so that they can identify the areas where disinsection is needed. Anyone coming back from a foreign trip who experiences fever or aches is advised to see their family physician immediately and indicate the region they recently returned from.

“The alert system in France is effective. The applicable procedure and measures are already well established because France’s overseas territories in endemic regions have provided us with expertise in these diseases and know-how on epidemiological monitoring. My team is affiliated with the Arbo-France network, and we are contacted as soon as an arbovirus is detected,” continues Anna-Bella Failloux.

Since 2006, vector control measures in France have led to increased surveillance of tiger mosquitoes between May 1 and November 30 each year. This involves monitoring mosquito populations in areas where they are likely to be present; disease surveillance coordinated by Santé publique France based on reporting of viruses such as dengue, chikungunya and Zika by health care professionals; and raising awareness among people living in areas where mosquitoes have been reported. France’s Regional Health Agencies (ARS) and their operators are responsible for managing reporting, monitoring the presence of mosquitoes and taking rapid action in response to human cases of infection (vector control).

This research, which focused on mosquitoes in the Greater Paris region for this first study, will soon be extended to the rest of mainland France. Extrinsic incubation periods vary from one tiger mosquito population to the next because of differences in their genetic makeup and in local temperatures. 

Find out more:

Video: “We are going to have to learn to live with tiger mosquitoes” – Anna-Bella Failloux

Disease-carrying mosquitoes – French Ministry of Employment, Health and Solidarity (sante.gouv.fr)

1. It is important to point out that for Usutu and West Nile, the ability of tiger mosquitoes to transmit these viruses to humans in real-life conditions, outside the experimental setting, is yet to be demonstrated, as they are naturally transmitted by Culex pipiens, another mosquito species.

Here’s a link to and a citation for the paper,

Aedes albopictus is a competent vector of five arboviruses affecting human health, greater Paris, France, 2023 by Chloé Bohers, Marie Vazeille, Lydia Bernaoui, Luidji Pascalin, Kevin Meignan, Laurence Mousson, Georges Jakerian, Anaïs Karchh, Xavier de Lamballerie, Anna-Bella Failloux. Euro Surveill. 2024; 29 (20): pii=2400271. DOI: https://doi.org/10.2807/1560-7917.ES.2024.29.20.2400271

This paper is open access.

I covered the movement of dengue fever and malaria into the Northern Hemisphere in an August 10, 2023 posting,

…

The World Health Organization (WHO) notes that dengue fever cases have increased exponentially since 2000 (from the March 17, 2023 version of the WHO’s “Dengue and severe dengue” fact sheet),

Global burden

The incidence of dengue has grown dramatically around the world in recent decades, with cases reported to WHO increased from 505 430 cases in 2000 to 5.2 million in 2019. A vast majority of cases are asymptomatic or mild and self-managed, and hence the actual numbers of dengue cases are under-reported. Many cases are also misdiagnosed as other febrile illnesses (1).

One modelling estimate indicates 390 million dengue virus infections per year of which 96 million manifest clinically (2). Another study on the prevalence of dengue estimates that 3.9 billion people are at risk of infection with dengue viruses.

The disease is now endemic in more than 100 countries in the WHO Regions of Africa, the Americas, the Eastern Mediterranean, South-East Asia and the Western Pacific. The Americas, South-East Asia and Western Pacific regions are the most seriously affected, with Asia representing around 70% of the global disease burden.

Dengue is spreading to new areas including Europe, [emphasis mine] and explosive outbreaks are occurring. Local transmission was reported for the first time in France and Croatia in 2010 [emphasis mine] and imported cases were detected in 3 other European countries.

…

The researchers from the University of Central Florida (UCF) couldn’t have known when they began their project to study mosquito bites and disease that Florida would register its first malaria cases in 20 years this summer, …

…

It seems pretty clear that there’s increasing concern about mosquito-borne diseases no matter where you live.

It looks like mega-sports events attract more visitors than you might expect.