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Do you crush microbes when you step on them?

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Do you crush microbes when you step on them?

You don’t need to watch where you step when it comes to bacteria.
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Ashok Prasad, Colorado State University and Kenneth F. Reardon, Colorado State University

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.


Do viruses, bacteria and other small things get crushed like an ant when stepped on? – Ryan L., age 12, Chapel Hill, North Carolina


When you step on some things, like a banana, they squish and flatten to the ground. But when you step on other things, like a rock, they maintain their shape and aren’t affected. So what happens when you step on bacteria? Are they squishy?

While we work with microorganisms and other cells as chemical and biological engineers, neither of us has actually tried squishing them in the lab. One of us has a background in physics and studies mechanical forces in biology, while one of us genetically engineers microorganisms and cultivates them to make biofuels and other chemicals.

Between the two of us, we thought we could figure out the answer.

Forces and pressures

Let’s think about what happens when you step on something. Any time you push or pull on an object, you exert a force on it. What happens after that depends on how much force you’re exerting and the properties of the object.

The force your footstep exerts comes mainly from your body weight. Also important is the area over which that force is distributed on your foot, which creates pressure. That part about the area is important – it’s why you can walk on snow with snowshoes, but you’d sink with regular shoes.

You can calculate pressure by dividing the weight of an object by its area. If your foot is approximately a rectangle of 7 inches (about 18 centimeters) in length and 4 inches (10 cm) in width, it has a surface area of 28 square inches (180 square cm). And if your weight is 110 pounds (50 kilograms), the force you exert per square inch is roughly 3.9 pounds per square inch.

For comparison, the pressure of the air, or atmospheric pressure, on your body at sea level is 14.7 pounds per square inch. The atmosphere exerts significantly more pressure on you than your footstep does on the ground – you just don’t feel it because it is balanced by the internal pressure of the air inside your body.

Microscopy image of Salmonella Typhimurium invading a human epithelial cell
It takes a little more than a stomp to kill bacteria like Salmonella.
NIAID/Flickr, CC BY

Stepping on a microbe

Now what happens to a bacterial cell when you apply the force of your footstep on it?

Bacteria have different shapes, ranging from spheres to rods and spirals. Bacterial cells have walls that protect their gel-like insides from the environment. How strong is a bacterial cell wall, and can it withstand the force of your footstep?

Scientists have studied the strength of bacterial cell walls for several reasons, including to find out whether high pressure can kill bacteria. People in the food industry use high pressure to make food such as milk safe for us to consume.

To determine the toughness of bacterial cell walls, researchers use a variety of tools to measure their ultimate tensile strength, which is the maximum pressure an object can withstand before breaking. This can be done, for example, by putting them in a sealed container and rapidly lowering the pressure until they explode. A 1985 study found that it would take nearly 1,500 pounds per square inch to make the bacterium Salmonella explode, and later experiments showed it would take about 1,900 pounds per square inch for the common soil bacterium Bacillus subtilis to explode. That’s 400 to 500 times more pressure than your sneaker is going to have on the sidewalk and any microbes lying about.

To understand these numbers in a different way, imagine a bacterium large enough for a person to stand on top of it. If it had the same cell wall strength as Salmonella, it could support over 350 people of 110 pounds each standing on it at the same time. While high pressures can kill bacteria in some applications such as food processing, one person standing on them won’t work.

Slipping through the cracks

It’s clear that bacterial cell walls are very strong. But there’s an added complication that makes it even harder to squish bacteria: They’re incredibly small. The average bacterium is only about 1 to 5 microns or millionths of a meter (smaller than ten-thousandth of an inch) in size. In comparison, the tip of a common pin is about 130 microns in diameter.

Close-up of skin wrinkles
Your skin, like the soles of your shoes, contains grooves that bacteria can slide into to take off the pressure of getting stepped on.
deyangeorgiev/iStock via Getty Images Plus

The surface of your skin has fine grooves called sulci cutis that are, on average, tens of microns deep. The soles of your shoes also have grooves that are much deeper than the ones in your skin. As a result, whether you are stepping on bacteria with your bare feet or while wearing shoes, most of the cells will slide into one of those grooves and escape from the full pressure you exert on the ground.

Standing on a pin

How could you increase the pressure your feet exert on a bacteria cell to squish it?

One theoretical way would be to change the bottoms of your shoes from flat to very pointy, with the bottom of the point having a diameter as wide as the tip of a pin. While walking on these shoes would be impossible, a 110-pound person would exert a pressure of 5.6 million pounds per square inch. That is enough to smash any known bacteria.

While people can’t actually do this, it turns out that some insects can. Cicada wings have tiny molecular structures that look like needles. These needle-like structures are only nanometers in size, a thousand times smaller than most bacteria, and are called nanorods.

Cicada wings are covered with cone-shaped nanopillars that can puncture bacteria.

When a bacterium lands on the surface of the cicada wing, it makes special chemicals that help it stick to the surface. When the bacteria divides, it produces tiny forces that allow the new cells to separate from each other. These small forces are magnified into enormous pressures when they push against the nanorods on the cicada wing, puncturing the bacteria and killing it.

Cicadas, dragonflies and many other flying insects have similar wing surfaces that are naturally bactericidal, meaning bacteria killing. Bioengineers are taking inspiration from nature and trying to make surfaces with needle-like structures that kill bacteria in a similar way.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.The Conversation

Ashok Prasad, Associate Professor of Chemical and Biological Engineering, Colorado State University and Kenneth F. Reardon, Professor of Chemical and Biological Engineering, Colorado State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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I’m an economist. Here’s why I’m worried the California insurance crisis could triggerbroader financial instability

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theconversation.com – Gary W. Yohe, Huffington Foundation Professor of Economics and Environmental Studies, Wesleyan University – 2025-01-21 07:42:00

Gary W. Yohe, Wesleyan University

The devastating wildfires in Los Angeles have made one threat very clear: Climate change is undermining the insurance systems American homeowners rely on to protect themselves from catastrophes. This breakdown is starting to become painfully clear as families and communities struggle to rebuild.

But another threat remains less recognized: This collapse could pose a threat to the stability of financial markets well beyond the scope of the fires.

It’s been widely accepted for more than a decade that humanity has three choices when it comes to responding to climate risks: adapt, abate or suffer. As an expert in economics and the environment, I know that some degree of suffering is inevitable — after all, humans have already raised the average global temperature by 1.6 degrees Celsius, or 2.9 degrees Fahrenheit. That’s why it’s so important to have functioning insurance markets.

While insurance companies are often cast as villains, when the system works well, insurers play an important role in improving social welfare. When an insurer sets premiums that accurately reflect and communicate risk — what economists call “actuarially fair insurance” — that helps people share risk efficiently, leaving every individual safer and society better off.

But the scale and intensity of the Southern California fires — linked in part to climate change, including record-high global temperatures in 2023 and again in 2024 — has brought a big problem into focus: In a world impacted by increasing climate risk, traditional insurance models no longer apply.

How climate change broke insurance

Historically, the insurance system has worked by relying on experts who study records of past events to estimate how likely it is that a covered event might happen. They then use this information to determine how much to charge a given policyholder. This is called “pricing the risk.”

Many California wildfire survivors face insurance struggles, as this ABC News report shows.

When Americans try to borrow money to buy a home, they expect that mortgage lenders will make them purchase and maintain a certain level of homeowners insurance coverage, even if they chose to self-insure against unlikely additional losses. But thanks to climate change, risks are increasingly difficult to measure, and costs are increasingly catastrophic. It seems clear to me that a new paradigm is needed.

California provided the beginnings of such a paradigm with its Fair Access to Insurance program, known as FAIR. When it was created in 1968, its authors expected that it would provide insurance coverage for the few owners who were unable to get normal policies because they faced special risks from exposure to unusual weather and local climates.

But the program’s coverage is capped at US$500,000 per property – well below the losses that thousands of Los Angeles residents are experiencing right now. Total losses from the wildfires’ first week alone are estimated to exceed $250 billion.

How insurance could break the economy

This state of affairs isn’t just dangerous for homeowners and communities — it could create widespread financial instability. And it’s not just me making this point. For the past several years, central bankers at home and abroad have raised similar concerns. So let’s talk about the risks of large-scale financial contagion.

Anyone who remembers the Great Recession of 2007-2009 knows that seemingly localized problems can snowball.

In that event, the value of opaque bundles of real estate derivatives collapsed from artificial and unsustainable highs, leaving millions of mortgages around the U.S. “underwater.” These properties were no longer valued above owners’ mortgage liabilities, so their best choice was simply to walk away from the obligation to make their monthly payments.

Lenders were forced to foreclose, often at an enormous loss, and the collapse of real estate markets across the U.S. created a global recession that affected financial stability around the world.

Forewarned by that experience, the U.S. Federal Reserve Board wrote in 2020 that “features of climate change can also increase financial system vulnerabilities.” The central bank noted that uncertainty and disagreement about climate risks can lead to sudden declines in asset values, leaving people and businesses vulnerable.

At that time, the Fed had a specific climate-based example of a not-implausible contagion in mind – global risks from sudden large increases in global sea level rise over something like 20 years. A collapse of the West Antarctic Ice Sheet could create such an event, and coastlines around the world would not have enough time to adapt.

In a 2020 press conference, Federal Reserve Chair Jerome Powell discusses climate change and financial stability.

The Fed now has another scenario to consider – one that’s not hypothetical.

It recently put U.S. banks through “stress tests” to gauge their vulnerability to climate risks. In these exercises, the Fed asked member banks to respond to hypothetical but not-implausible climate-based contagion scenarios that would threaten the stability of the entire system.

We will now see if the plans borne of those stress tests can work in the face of enormous wildfires burning throughout an urban area that’s also a financial, cultural and entertainment center of the world.The Conversation

Gary W. Yohe, Huffington Foundation Professor of Economics and Environmental Studies, Wesleyan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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How nonprofits pitch in before, during and after disasters strike

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theconversation.com – Vanessa Crossgrove Fry, Associate Research Faculty/Interim Director, Boise State University – 2025-01-21 07:41:00

Social Border Grill delivers food as part of World Central Kitchen relief efforts at an Eaton Fire temporary shelter in Pasadena, Calif., on Jan. 9, 2025.
Kirby Lee/Getty Images

Vanessa Crossgrove Fry, Boise State University

Los Angeles is reeling after fires of historic proportions raced through many communities in January 2025, destroying thousands of homes. The Conversation U.S. asked Vanessa Crossgrove Fry, an associate research professor and director of the Idaho Policy Institute at Boise State University, and an expert on sustainable management and nonprofit administration, to explain what role nonprofits can play in staving off disasters and dealing with them when and after they occur.

What’s the role of nonprofits when disasters strike?

They play a critical role by complementing government efforts and filling gaps in immediate and long-term recovery needs.

Collaboration is a hallmark of how nonprofits respond to disasters. These organizations often work alongside government agencies and private sector partners in coordinated efforts. This approach ensures that aid is distributed efficiently, directing resources where they are needed most.

Often, national groups lead efforts to establish emergency shelters, distribute food and water, and offer mental health support. In a best-case scenario, these large organizations partner with local nonprofits that are uniquely positioned to mobilize quickly, leveraging their deep understanding of community needs and established trust with residents.

In some disasters, especially large ones like the Lahaina, Hawaii, fire in 2023, nonprofits also act as coordinators. They make sure that volunteers, donations and other resources flow to people who need help.

Nonprofits’ flexibility and community-based networks enable them to respond to local challenges, such as supporting displaced families or addressing unmet needs in underserved areas. Beyond immediate relief, many nonprofits remain involved in long-term recovery efforts, assisting with rebuilding homes, restoring livelihoods and fostering community resilience.

Two women sit at a table crowded with food, but look desolate.
While surrounded by food donations, Evangeline Balintona, left, and her sister Elsie Rosales, sit inside a hotel-condo after they both lost homes in Lahaina to the wildfire, Sept. 1, 2023, in Kahana, Hawaii.
AP Photo/Marco Garcia

What do nonprofits do before disasters occur?

Nonprofits play a crucial role in disaster preparedness by working to reduce risks and build resilience.

In fire-prone regions like the Los Angeles foothills, organizations often focus on educating the public, helping residents understand fire risks and creating evacuation plans. They also implement fire mitigation strategies, such as spreading awareness about the importance of clearing brush and replacing wooden roofs.

Nonprofits also run community training programs, such as CPR certification or Community Emergency Response Team – CERT – training, or Sound the Alarm events to empower residents to respond effectively during emergencies.

With CERT training, a local fire department might equip volunteers to prepare for the hazards they’re likely to face in their communities. That kind of exercise empowers them with essential disaster-response skills, including fire safety and light search and rescue know-how. During Sound the Alarm events, smoke detectors are installed in vulnerable communities and residents get help creating evacuation plans.

Partnerships with government agencies, private companies and other nonprofits should ideally be in place before a disaster occurs to ensure a coordinated response when the time comes.

For example, nonprofits may establish agreements about setting up emergency shelters or accessing and distributing food supplies. They also build networks to ensure vulnerable populations – such as low-income residents, people experiencing homelessness, and those with disabilities – are included in disaster planning and response efforts.

Other roles include advocating for more funding for disaster preparedness and infrastructure, like wildfire-resistant construction or community-wide firebreaks – areas of cleared vegetation.

In some cases, nonprofits may help coordinate the use of government resources. For instance, Idaho Department of Insurance Director Dean Cameron recently drafted a bill that’s pending in the Idaho Legislature that would provide funding for homeowners to make fire mitigation upgrades on their property.

Additionally, nonprofits often develop detailed contingency plans for their own operations so they can continue to deliver services during a crisis.

Through these proactive measures, nonprofits help communities prepare for the worst while fostering resilience that can temper the long-term impacts of disasters.

What does the situation in LA have in common with what happens in Idaho?

Los Angeles and Idaho might seem worlds apart, but when it comes to handling disasters like wildfires, they face surprisingly similar challenges.

Both places grapple with dry seasons, rising temperatures and increasing invasive vegetation that amplify wildfire risks. Climate change is exacerbating these conditions, making fires more frequent and intense.

In Los Angeles, urban sprawl has expanded development into fire-prone areas, known as the wildland-urban interface. Similarly, Idaho has seen increased development in the wildland-urban interface surrounding Boise – where the population is surging.

This type of growth poses significant risks to both homes and lives as seen in Idaho’s 2016 Table Rock Fire and the more recent 2024 Valley Fire.

In addition, wildfires in Idaho’s forested and rural areas put not only people and infrastructure at risk, but can impact valuable grazing land, as occurred in the 2024 Wapiti Fire.

In both regions, balancing the demand for housing with the need for fire-resilient planning and mitigation measures is a critical challenge.

Another shared concern for nonprofits in Idaho and California is ensuring that vulnerable populations receive enough support during and after disasters. In both urban and rural settings, people experiencing homelessness, low-income families, and those in remote areas may have a lot of trouble evacuating, accessing resources and rebuilding after disasters.

Firefighters spray down the rubble of burned homes.
A firefighter from Idaho sprays down the rubble of homes demolished by the Eaton Fire in Altadena, Calif., on Jan. 15, 2025.
Photo by Frederic J. Brown/AFP via Getty Images

What are some common misconceptions about nonprofits in disasters?

Many people tend to think that nonprofits only provide immediate relief, such as food, shelter or medical care. While these services are critical in the early stages of a disaster, many nonprofits also focus on long-term recovery and rebuilding efforts.

Nonprofits may help communities rebuild homes, restore livelihoods or address emotional trauma months – or even years – after a disaster occurs.

There is also a tendency to overlook the role of local nonprofits. High-profile national organizations often command the public’s attention, but local nonprofits are often better positioned to address community-specific needs and work directly with vulnerable populations.

These misunderstandings can lead to the underfunding – and underappreciation – of local nonprofits.

Should people still donate to established organizations?

There are more ways to give to people experiencing a crisis than there used to be.

You might hesitate to donate to large nonprofits after a big disaster like the Los Angeles fires, for several reasons. Maybe you’re concerned about transparency or the group’s effectiveness. It might feel less personal to you than giving money, say, to a GoFundMe campaign.

I think that people should still consider donating to large and established organizations, but I also believe that it’s important to do so thoughtfully. Large nonprofits, such as the American Red Cross or Salvation Army, often have the infrastructure, expertise and logistical capacity to mobilize quickly and scale their operations to address disasters effectively.

These organizations also maintain established relationships with government agencies, local nonprofits and international partners. Those networks facilitate coordinated responses that smaller or newer groups might struggle to achieve.

However, the emergence of giving options, such as crowdfunding platforms, grassroots campaigns and community-based nonprofits, has expanded opportunities for individuals to direct their support to specific causes or populations. These avenues can make a big difference, particularly when donors want to address local or niche needs. Still, newer or less established groups may lack transparency or accountability.

Established organizations tend to have robust financial oversight and accountability systems in place. They are often better equipped to address not only immediate relief needs but also long-term recovery efforts, which smaller or informal groups may not have the capacity to support.

To be sure, it’s always wise to do some research before giving money to a cause of any kind.

Ultimately, the choice depends on your own priorities. Do you want to support immediate relief, contribute to systemic solutions or help a specific community?

By donating to both large organizations and local efforts alike, you can maximize your impact and help ensure everyone in a community gets support. And that’s important, especially after a disaster as big as the Los Angeles wildfires.The Conversation

Vanessa Crossgrove Fry, Associate Research Faculty/Interim Director, Boise State University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Luce, a cartoon mascot for Catholic Church’s 2025 Jubilee, appeals to a younger generation while embracing time-honored traditions

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theconversation.com – Virginia Raguin, Distinguished Professor of Humanities Emerita, College of the Holy Cross – 2025-01-21 07:38:00

The Vatican introduces Luce at the Lucca Comics and Game convention in 2024.
https://www.youtube.com/watch?v=uKiGMGkc0xk screenshot via Wikimedia.com, CC BY

Virginia Raguin, College of the Holy Cross

Luce, the anime-inspired official mascot for the Catholic Church’s 2025 Jubilee, whose name means “light” in Italian, has been getting a lot of attention on social media. Some people love the cartoon and find her “cute,” but a few others consider her “unsuitable” and even “repugnant.”

The Vatican introduced Luce at a comics convention in Italy, with the goal of engaging young people and speaking about the theme of hope.

Designed by Simone Legno, the mascot with big blue eyes and blue hair, and rosary beads around her neck, represents a Catholic pilgrim. She is dressed in pilgrimage garments that were standard attire throughout the centuries. Her badge, the Pilgrimage of Hope, identifies the 2025 Jubilee. It shows blue, green, yellow and red figures embracing a cross that ends in an anchor at the base, a symbol of hope. The figures form an outline of a ship sailing over the waves, evoking images of travel.

I have long been interested in the central role played by pilgrimage in many faith traditions, culminating in an exhibition and book, “Pilgrimage and Faith: Buddhism, Christianity, and Islam” in 2010. Luce brings a contemporary perspective to the time-honored Christian pilgrimage tradition.

Pilgrimage symbols

The symbols that Luce carries serve as a reminder of the origins of Christian pilgrimage, which began with visits to the Holy Land, the place where Christ lived his life.

This pilgrimage was documented by a person who came to be known as the Anonymous Pilgrim of Bordeaux. He wrote in his diary “The Bordeaux Pilgrim” in 333 about his trip to the Holy Land when the basilica of the Holy Sepulcher, the site where Jesus was buried and is believed to have resurrected, was still under construction.

Luce carries symbols that have been associated with pilgrimage in Europe since the 12th century, particularly those connected to the shrine of St. James in northwestern Spain.

This Holy Land pilgrimage built a tradition of Christians not just visiting the holy sites but also returning with tangible souvenirs, such as a stone from the Holy Land, water from a well, or even a piece of cloth or a statue that touched Christ’s tomb. A sixth-century painted box now in the Vatican contains bits of soil and stones as souvenirs of places in the Holy Land.

A painting of a saint with a halo around his head and a staff in his hand.
St. James, depicted as a pilgrim on a stained-glass window at the monastery of Wettingen, Switzerland.
Virginia Raguin, CC BY

The pilgrimage to honor St. James, one of Christ’s apostles, whose tomb was believed to have been found in northwestern Spain, became popular in the early 12th century. The pilgrimage route was called the Way of St. James, Camino de Santiago de Compostela. The pilgrimage guided the faithful through several routes across Spain, France and Portugal, culminating in Santiago de Compostela in Galicia, in the north of Spain.

The itinerary of the journey, written in 1137 by an anonymous Frenchman, names natural landmarks, local customs and specific churches built to honor different saints. Along this route flowed artistic, economic and cultural exchanges. As was customary, pilgrims who returned after visiting St. James’ tomb adopted an emblem. Since the shrine was close to the sea, James’ symbol became a scallop shell that pilgrims wore to demonstrate their achievement.

Pilgrims were proud of these voyages that entailed much physical hardship as well as devotion. In the church of Santa Prassede, Rome, Giovanni de Montpoli, who describes his trade as preparing medicines, commissioned a 13th-century tomb slab showing himself as a pilgrim. He is dressed in a pilgrim’s fur overcoat to repel rain and retain warmth. He carries a staff and wears a wallet slung over his shoulder. A scallop shell adorning his broad-brimmed hat indicates that he had traveled to Compostela.

The popularity of the pilgrimage to St. James persisted through the Renaissance, supported by pilgrimage fraternities that helped people find companions for the journey and stay connected with each other after they returned. Sometimes subgroups of the fraternity even sponsored pilgrimage-related art such as a stained-glass window.

Evidence of such activities is seen in the monastery of Wettingen, near Zurich in Switzerland. St. James is depicted as a pilgrim in a stained-glass window dated 1522, donated by a Hans Hünegger and Regina von Sur. He wears a cloak and a hat decorated with pilgrim badges.

Pilgrim badges

A stained glass window depicts two men, each holding a staff, with one gazing up at the sky.
St. Louis of France wears scallop shell pilgrim emblems, Sainte-Clotilde, Paris, 1855.
Virginia Raguin, CC BY

By the middle decades of the 12th century, metal pilgrim badges were produced at low costs. They were soon available at shrines throughout Europe. Each pilgrimage location had its own distinctive badge.

Santiago’s scallop shell remained a universal pilgrim emblem over the centuries. A 19th-century stained-glass window in the church of Sainte-Clotilde in Paris shows 13th-century French King Louis IX – the only French monarch to be named a saint – with scallop shells on his cloak, even though his pilgrimage was to Jerusalem, not the shrine of Santiago.

A sketch of a man on a white marble slab.
Tomb slab of Giovanni de Montpoli, late 13th century, church of Santa Prassede, Rome.
Virginia Raguin, CC BY

Sometimes the Supper at Emmaus, when Christ met two disciples after his resurrection, was depicted showing the disciples as contemporary pilgrims.

One of the most memorable examples is Caravaggio’s painting from 1601, in the National Gallery in London, showing an astonished apostle wearing a scallop shell on his vest.

Luce, the pilgrim

Luce continues, as well as transforms, these traditions. In her large eyes gleam two scallop shells that reflect this thousand-year-old symbol. Like Giovanni de Montpoli in Rome, she wears a coat that shields her from the elements and she carries a staff. The yellow of the cloak references the color of the flag of Vatican City.

Like the 16th-century Swiss image of St. James, she wears a pilgrimage badge, this one proclaiming the Pilgrimage of Hope of the 2025 Jubilee. Her muddy boots indicate outdoor hiking, with which any young person can identify. She is depicted as female, representing all people, not just women.

Drawn in a contemporary and globally popular style, she suggests an openness to new encounters across the world.The Conversation

Virginia Raguin, Distinguished Professor of Humanities Emerita, College of the Holy Cross

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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