Author Martin Bier in an aerodynamic tuck, a cycling position that reduces wind resistance. Credit: Martin Bier
Within the cycling realm, “to Everest” involves riding up and down the same mountain until your ascents total the elevation of Mt. Everest—8,848 meters.
After a new cycling “Everesting” record was set a few years ago, a debate ensued on social media about the strong tailwind the cyclist had on climbs—5.5 meters per second (20 kilometers per hour or 12 miles per hour)—when he set the record. To what extent did the tailwind help him? Should limits be set on the allowed windspeed?
Martin Bier, a physics professor at East Carolina University in North Carolina, became intrigued by this debate and decided to explore the physics, and a little project ensued. In the American Journal of Physics, he shares his finding that ultimately, the wind turns out to be of negligible consequence.
First, a little background: From a physics perspective, cycling is easier to comprehend than running.
“In running, the motion of the legs is repeatedly accelerated and decelerated, and the runner’s center of mass moves up and down,” said Bier. “Cycling uses ‘rolling,’ which is much smoother and faster, and more efficient—all of the work is purely against gravity and friction.”
But there’s something odd about air resistance. The force of air friction you fight goes up with the square of your speed. If air resistance is the main thing limiting your speed—which is true for a cyclist on flat ground or going downhill—then to double your speed, you need four times the force. Tripling your speed requires nine times as much force. But, on the other hand, when cycling uphill, your speed is much slower, so air resistance isn’t a big factor.
“When you’re riding up a hill and fighting gravity, doubling your power input means doubling your speed. In bike races, attacks occur on climbs because it’s where your extra effort gets you a bigger gap.”
On a solo Everesting effort, calculations are straightforward. A rider isn’t getting an aerodynamic draft from another rider ahead of them. The inputs are simply watts, gravity, and resistance.
“Naively, you may think that a strong tailwind can compensate for an uphill slope,” said Bier. “You then ride up the hill as if it’s a flat road, and on the way down the headwind and downward slope balance out and again give you the feel of a flat road. But it doesn’t work—the square I mentioned earlier wreaks havoc.”
His work shows the tailwind may help a little on the climb, but most of the work on the way up is the fight against gravity. The subsequent descent is fast and lasts a much shorter time, while the headwind there actually has a huge effect. And the speed on a descent is high—about 80 kph (49.7 mph).
“Air resistance goes with the square of the speed, which leads to the headwind on the descent and causes a big reduction in speed,” Bier said. “The wind boost on the ascent is canceled out.”
The obvious implication of Bier’s work is that there’s no point in waiting for the ideal wind if you want to improve your Everesting time.
“There are no easy tricks,” he said. “If you want to be a better Everester, you need to lose weight and generate more watts (exercise). This is what matters—there’s no way around it.”
More information:
The physics of ‘Everesting’ on a bicycle, American Journal of Physics (2024). DOI: 10.1119/5.0131679
Citation:
Physicist reveals tailwind has negligible effect on cycling speed (2024, September 20)
retrieved 20 September 2024
from https://phys.org/news/2024-09-physicist-reveals-tailwind-negligible-effect.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
A new analysis led by a group of college researchers finds the U.S. will fall short of its recently finalized target for reducing vehicle emissions by nearly 15 percent over the next decade because of unrealistic goals for increasing electric-vehicle production. But adding more hybrids to the mix could help.
The study, published in Nature Communications, finds the U.S. won’t come close to its EV sales target by 2032, due mostly to bottlenecks in supply chains for crucial minerals like graphite and cobalt. Failing to correct these issues would amount to nearly 60 million extra tons of carbon dioxide emissions over the next eight years.
Paper co-author and economics concentrator Megan Yeo ’25 said the team sought to break down the EPA’s stringent new emissions goals and assess whether they were realistic.
“First we asked, ‘How many EVs need to be sold to reach that target?’ After that, we looked at different scenarios,” said Yeo, who co-authored the paper with Harvard Law School senior research associate Ashley Nunes, along with first author Lucas Woodley ’23 and Chung Yi See ’22.
The researchers found that meeting the new standards would require replacing at least 10.21 million internal combustion engine vehicles with EVs between 2027 and 2032. But they estimated the U.S. and its allies would only be able to support the manufacture of about 5.09 million EVs during that period, falling short of the goal by about half.
Manufacturing EVs and their rechargeable batteries requires large amounts of minerals including cobalt, graphite, lithium, and nickel. The U.S. and its allies likely have ample reserves of the raw materials.
The problem is production capacity—the ability to adequately mine and refine the materials. The challenge is particularly acute for graphite, which has not been mined domestically since the mid-20th century.
Overview of EV sales scenarios and impact of mineral supply constraints. Credit: Nature Communications (2024). DOI: 10.1038/s41467-024-51152-9
The team scoured for solutions, including rethinking emissions goals by producing more hybrid-electric vehicles. HEVs require fewer mineral resources but have reduced tailpipe emissions, offering a way to close the gap on emissions and expand the government’s focus beyond EVs.
“We suggest exploring HEVs as an alternative pathway,” Yeo said.
According to Nunes, another of the study’s takeaways is that the U.S. might be able to build enough electric cars if it leaned more heavily on China for mineral resources. But U.S. lawmakers are wary of this approach for national security reasons.
“Americans may have to ask, what do we value more—fewer emissions or energy security?” Nunes said.
Singapore native Yeo said she aspires to be a public-sector economist in her home country and that joining Nunes’ research group to work on the EV analysis opened her eyes to the rigors and constraints of evaluating public policy.
“Setting lower and upper bounds for different scenarios, and running through alternative possibilities, robustness checks, and assumptions, were all very valuable skills for me to learn,” Yeo said.
Working in the Nunes group, there’s “never a dull moment,” she continued, with multiple projects related to EVs and other transportation-sector climate goals in the works.
The paper’s other co-authors were Peter Cook and Seaver Wang of the Breakthrough Institute, Laurena Huh of MIT, and Daniel Palmer, a high school student at the Groton School who participated in Harvard’s precollege and secondary school programs.
More information:
Lucas Woodley et al, Climate impacts of critical mineral supply chain bottlenecks for electric vehicle deployment, Nature Communications (2024). DOI: 10.1038/s41467-024-51152-9
Provided by
Harvard Gazette
This story is published courtesy of the Harvard Gazette, Harvard University’s official newspaper. For additional university news, visit Harvard.edu.
Citation:
Analysis finds flaw in US plan to cut vehicle emissions—and possible solution (2024, September 20)
retrieved 20 September 2024
from https://techxplore.com/news/2024-09-analysis-flaw-vehicle-emissions-solution.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
A small team of biologists at the University of Bristol has found that black garden ants modify the physical structure of their nests to mitigate infection spread. The group has written a paper describing the experiments they conducted with black garden ants and fungal infections in their lab and posted it on the bioRxiv preprint server.
Prior research has shown that some animals change their behavior to avoid spreading infections, whether they be viral, bacterial or fungal. Among those, only humans have been found to alter their surroundings as a way to further protect themselves—people might close off parts of their house, for example, or establish quarantine zones within hospital areas.
In this new study, the research team found an instance of an insect altering its nest to deter the spread of an infecting fungus.
To learn more about how insects, such as ants, attempt to prevent the spread of an infection among members of a nest, the research team went into the field and collected black garden ants—enough to set up 20 colonies in their lab, each in its own glass enclosure.
After giving the ants a single day to acclimate themselves to their new environment, the researchers added 20 more ants to each colony—half of which were infected with a fungus known to spread among the ants.
The research team then set up cameras to record the behavior of the ants and micro-CT scanners to study the nature of the nest tunnels that the ants dug beneath the soil.
The team found that in the colonies with the infected ants, new tunnels were dug faster than in those not infected. After six days, the spacing between the tunnels was farther apart in the infected nest as well.
The ants in the exposed colonies also placed their queen, food and brooding area in a less central location. And finally, those ants that were infected tended to spend most of their time on the surface, rather than underground with their nestmates.
The researchers next used disease transmission simulations to speed up the process of disease spread and found that the techniques used by the ants did indeed reduce the fungal load in the colony, helping the nest survive.
Citation:
Black garden ants modify the structure of their nests to mitigate fungal infection spread (2024, September 20)
retrieved 20 September 2024
from https://phys.org/news/2024-09-black-garden-ants-mitigate-fungal.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
23andMe CEO Anne Wojcicki speaks at an announcement for the Breakthrough Prize in Life Sciences at Genentech Hall on UCSF’s Mission Bay campus in San Francisco, Feb. 20 2013. Credit: AP Photo/Jeff Chiu, File
All of 23andMe’s independent directors resigned from its board this week, a rare move that marks the latest challenge for the genetic-testing company.
The resignations follow drawn-out negotiations with 23andMe CEO and co-founder Anne Wojcicki, who wants to take the company private. In a Tuesday letter addressed to Wojcicki, the seven directors said they had yet to receive a “a fully financed, fully diligenced, actionable proposal that is in the best interests of the non-affiliated shareholders” from the chief executive after months of efforts.
The directors said they would be resigning effective immediately — arguing that, while they still believed in 23andMe’s mission, their departures were for the best due to Wojcicki’s concentrated voting power and a “clear” difference of opinion on the company’s future.
Wojcicki later responded to the resignations in a memo to employees, published in a securities filing, saying she was “surprised and disappointed” by the directors’ decision. Still, she maintained that taking 23andMe private and “outside of the short term pressures of the public markets” would be best for the company long term.
Wojcicki added that 23andMe would immediately be identifying independent directors to join the board. Wojcicki, who holds 49% of the voting power at 23andMe, was the only remaining board member listed on the company’s website as of Thursday. A spokesperson had no further updates to share when reached by The Associated Press.
23andMe, which went public in 2021, has struggled to find a profitable business model since. The company reported a net loss of $667 million for its last fiscal year, more than double the loss of $312 million for the year prior.
Shares for 23andMe have also plummeted — with the company’s stock closing at 33 cents Thursday, down more than 97% since its 2021 stock market debut, according to FactSet.
Wojcicki announced her intention to take 23andMe private, by way of acquiring all outstanding shares that she doesn’t own, in April. Wojcicki also said that she wished to maintain control of the company and was not willing to support alternative transactions from other bidders. She submitted a proposal in late July, but the board’s evaluating committee found it to be wanting.
Beyond the resignations, 23andMe has made other a handful of other headlines in recent months — particularly around privacy concerns. Last week, 23andMe agreed to pay $30 million in cash to settle a class-action lawsuit accusing the company of failing to protect customers whose personal information was exposed in a 2023 data breach.
23andMe has shared preliminary support of the settlement, which is set to be heard by a judge for approval next month. In a statement, a spokesperson said that the company looked forward to finalizing the agreement, which it believe is “in the best interest of 23andMe customers.” The $30 million payment would settle all U.S. claims, the spokesperson added, and $25 million of it is expected to be covered by insurance coverage.
Citation:
23andMe directors resign as the CEO of the genetic-testing company seeks to take it private (2024, September 20)
retrieved 20 September 2024
from https://techxplore.com/news/2024-09-23andme-directors-resign-ceo-genetic.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
The Madagascan tomato frog, Dyscophus guineti, secretes glue from its skin as a way to defend itself against predator attacks. Credit: Shabnam Zaman
Skin-secreted adhesives, or glues, are highly effective defense adaptations that have evolved recurrently in a small number of amphibians. From an ecological standpoint, this rapidly solidifying material—essentially, a sticky slime—encumbers the predator long enough for its would-be prey to escape.
But what makes some skin secretions stickier than others, and why has it arisen multiple times throughout the history of amphibian evolution?
Adhesives in nature: Ancient tools for survival
There’s no denying that materials that help us stick things to other things—that is, glue—are omnipresent. On any given day, you may find yourself reaching for a stack of sticky notes or a universally reliable roll of sticky tape. But what about glue in other, less dexterous animals? What is it used for, and how does it work?
Before we go any further, let’s clarify what exactly is meant by “animal glue.” In the context of glue-producing organisms, the materials I’m referring to are called “biological adhesives.” These are naturally secreted materials that occur in a wide range of species, with many serving vital functions necessary for that particular organism’s survival.
The potential uses of these glues are as diverse as the animals producing them, and include substrate attachment (typical of sessile marine organisms such as mussels, barnacles and tubeworms), locomotion (used by starfish to move across the ocean floor) and prey capture (most easily recognizable in the form of spider silk).
Indeed, the sheer utility and adaptive value of glue is reflected in its broad taxonomic distribution, spanning several anciently diverged lineages.
There’s one thing you may have noticed: All the animals I’ve described so far are invertebrates. What about species that look and feel a little closer to home—say, a fellow tetrapod?
If you ever find yourself in the company of herpetologists, simply utter the words “sticky” and “frog” and you will inevitably hear about that time a wild specimen oozed vast amounts of slime all over the offender’s hands.
This slime rapidly took on the properties of superglue: Hands were stuck together, the frog was stuck to the hands—all in all, a very sticky situation. This may just be anecdotal evidence, but search the literature and you will find scant mention of this relatively obscure phenomenon. However, that doesn’t make the stories any less true.
The wonderful world of frog glue: a sticky topic. Discover what makes this defense strategy so remarkable, all in under three minutes. Credit: Science Figured Out
How frogs use glue as a defensive strategy
Skin-secreted chemicals constitute the most widespread antipredator adaptation among amphibians. In a small number of amphibians, this mechanism occurs in the form of glue. When stressed, the amphibian discharges a viscous fluid from its back that quickly solidifies into a sticky mass (i.e., glue).
This glue functions as an effective defense weapon, incapacitating the attacking predator—often a snake—by clogging its mouth and making the act of swallowing impossible. The energetic cost of overcoming this stickiness eventually becomes too high, forcing the predator to give up and release the amphibian.
While toxic skin secretions (i.e., poisons) have long persisted as the focus of most biochemical investigations, research on glue remains scarce and superficial. One possible reason for this disparity may be the fact that glue is a rare feature in frogs, having emerged only sporadically in species that are—on an evolutionary timescale—distantly related.
Although frog glue has been discovered throughout the world, its absence in most species (and especially close relatives) is conspicuous. For instance, a glue-producing frog in Madagascar might not share the island with glue-producing amphibians from other lineages.
Instead, similar sticky secretions may be found in frogs with distributions restricted to Australia or South America, for example.
This brings us to the crux of my study published in Nature Communications : How, exactly, did glue as a defense adaptation evolve in only some frogs, but not in others?
And, as an aside: Does frog glue have anything in common with that sticky tape you have at home?
The bonding process: From interdisciplinary to intermolecular
To answer these questions, I investigated the glue produced by a species endemic to Madagascar: the tomato frog, Dyscophus guineti. Together with several collaborating research institutions, I integrated functional, molecular and evolutionary analyses to uncover what, exactly, makes frog glue stick.
To this end, I identified two proteins that demonstrably interact within the glue milieu to sustain its adhesive and cohesive strength. One is a large glycoprotein (cleverly assigned the acronym PRIT, courtesy of my supervisor) with a presumed glue-specific role, and contains duplicate copies of an evolutionarily conserved domain that is also present in many extracellular metazoan proteins.
The second, much smaller protein is a glycan-binding member of an ubiquitous protein family known as galectin. These findings are consistent with previous reports on the importance of both glycoproteins and glycan-binding proteins in other animal glues, although their interactions and probable mechanism of action were unresolved until recently.
Although the tomato frog is endemic to Madagascar, its defensive glue is strikingly similar to those produced by frogs found elsewhere in the world. Credit: Shabnam Zaman
Structural models predicted that while the conserved domains within PRIT are well defined, their intervening regions are structurally heterogenous. This is in contrast to most (nonadhesive) proteins, which have rigid and defined structures, whereas the structural dynamism of PRIT renders it highly flexible.
In practical terms, this means that frog glue can conformationally adapt to any surface it comes into contact with—for example, the oral epithelia of a snake. The transition from a viscous but fluid slime into a tough, fast-acting adhesive occurs once pressure is applied, such as the force exerted by a predator’s bite.
Reverting to our earlier question: What do the humble sticky tape and frog glue have in common? They’re both pressure sensitive, meaning that compressive force is required to fully “activate” their sticking power.
A recipe for recurrent evolution: Reuse, recycle, re-evolve
With the glue proteins identified, I could finally begin to examine the genetic and structural changes that lead to its evolution in distantly related lineages. As noted above, neither protein is inherently unique to D. guineti, or even frogs in general. In fact, the protein domains found in frog glue are present in all animals, including humans.
The specific architecture of the gene encoding PRIT, however, involves a deviation that evolved in an early amphibian ancestor. In other words, glue genes evolved before the glue itself.
Intriguingly, a second glue-producing species (the Mozambique rain frog, Breviceps mossambicus) also encodes a PRIT gene. Dyscophus and Breviceps diverged about 100 million years ago and belong to distinct radiations of frogs (Microhylidae and Afrobatrachia, respectively).
Other members of these lineages produce nonadhesive toxins that are known to have originated early in frog evolution, thus leaving little doubt that: (1) Dyscophus and Breviceps both descended from a poisonous ancestor; and (2) their skin secretions evolved into glues independently.
Alongside structural changes, shifting gene expression was identified as a decisive factor in the recurrent evolution of glue: PRITs and galectins exhibit the same pattern of elevated expression in both glue-producing species, from which we can surmise that regulatory changes also contributed to the parallel evolution of frog glue.
Unlike other glue-producing animals, each of which evolved a unique method of adhesion, highly diverged frog lineages have repeatedly recruited the same pre-existing genes, simply by boosting their expression.
Frog glue is therefore a culmination of evolutionary processes that came before it, with recurrent structural and regulatory changes acting on an ancient and near-universal template.
From forest floors to operating tables: The future of biomimetics
My recent work represents the first detailed analysis of a vertebrate defense glue, thus advancing our understanding of these unusual adaptations while simultaneously opening the door for the development of new, rapid-acting adhesive technologies.
The effectiveness of animal slimes as surgical sealants has already been demonstrated using slug defensive glue; for instance, now we know how it functions in a vertebrate, using a model with the potential to encompass biological glues from phylogenetically diverse sources.
Watch this space: Soon, frog glue derivatives may become as crucial and commonplace in surgical practices as the sticky tape is in our households today.
This story is part of Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.
More information:
Shabnam Zaman et al, Recurrent evolution of adhesive defence systems in amphibians by parallel shifts in gene expression, Nature Communications (2024). DOI: 10.1038/s41467-024-49917-3
From the molecular to the most majestic of biological marvels, Shabnam Zaman has always been driven to understand the “why” behind the whimsical. That’s how she ended up as a Ph.D. researcher at the Amphibian Evolution Lab (Vrije Universiteit Brussel, Belgium) with a mission to investigate a strange but little-known phenomenon: frog glue. Together with her trusty companion, Bob the Tomato Frog, they are on a quest to unravel the enduring mysteries of what makes these creatures so incredibly sticky.
Citation:
Independent origins of frog glue and its role in predator evasion (2024, September 20)
retrieved 20 September 2024
from https://phys.org/news/2024-09-independent-frog-role-predator-evasion.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.