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Tropical climates are the most biodiverse on Earth − but it’s not only because of how warm and wet they are

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Tropical climates are the most biodiverse on Earth − but it’s not only because of how warm and wet they are

Natural selection can get to work in isolated locations.
Birger Strahl/Unsplash, CC BY

Marco Túlio Pacheco Coelho, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL); Catherine Graham, Stony Brook University (The State University of New York), and Dave Roberts, Montana State University

Life exists in every conceivable environment on Earth, from the peaks of towering mountains to the remote stretches of isolated islands, from sunlit surfaces to the darkest depths of the oceans. Yet, this intricate tapestry of existence isn’t spread uniformly.

For centuries, scientists have marveled at the extraordinary variety of species exhibited in tropical regions. The breathtaking biodiversity of the Amazon rainforest, the teeming life in Madagascar’s unique ecosystems, the species-rich cloud forests of Costa Rica – the tropics showcase nature’s opulence.

What makes the tropics so incredibly diverse?

Since the dawn of biodiversity studies, scientists have believed the predominant factor is climate – the long-term patterns of temperature, precipitation and other atmospheric conditions. Thinkers like Alexander von Humboldt set the stage in the early 19th century with their keen observations, highlighting how life-rich regions often shared certain climatic features. Fast-forward to the present, and scientists confidently correlate climate with biodiversity. Simply put, hotter, wetter, resource-rich regions are veritable cradles of life.

hilly landscape descending toward blue inlet
The Mediterranean climate is named after where it occurs in Southern Europe, but similar isolated conditions are scattered across the globe in parts of California, central Chile, the Western Cape of South Africa and southwestern Australia.
bodrumsurf/iStock via Getty Images Plus

Some climatic conditions spread across vast landscapes, while others appear fragmented, resembling isolated islands amid varying climates. This difference raises an intriguing question: Is an area’s biodiversity solely due to its climate? Or do the size and relative isolation of these climatic pockets influence the richness and abundance of species that thrive within them?

We are part of an international, interdisciplinary team interested in the puzzle of how the geography of climate and the global patterns of species diversity fit together. Geography of climate is a bigger part of the biodiversity picture than previously assumed, according to our study findings recently published in the journal Nature.

map of continents showing areas with more amphibian species marked red, mostly in the tropics
Researchers commonly consider the geographical distribution of species, as displayed on this map highlighting the number of amphibian species across various regions of the world.
Marco Túlio Pacheco Coelho

Unraveling the geography of climate

Historically, to study global biodiversity patterns, researchers divided the world into equal area grids and counted the species in each square.

Our study diverged from conventional methods. Instead of focusing solely on specific geographical locations, we centered our attention on the unique climate profiles of regions. Essentially, we weren’t just looking at plots on Earth but every place that shared a particular set of climatic conditions. We then classified these conditions globally and meticulously counted the species – birds, mammals, amphibians and reptiles – that live within the boundaries of each climate.

a heat map of amphibian richness along a horizontal axis from cold to warm and a vertical axis from wet to dry
Mapping species in this climate space, rather than traditional geographical analyses of species diversity, revealed deeper insights into the relationships between biodiversity and climate.
Marco Túlio Pacheco Coelho

Central to our investigation was an exploration of the geography of these climates, examining both their size and isolation. Some climates are widespread and common, sprawling over vast areas. Others are more fragmented, emerging as isolated pockets amid different climatic zones, reminiscent of islands in a vast ocean of other diverse climates. Consider tropical climates: They cover vast expanses cumulatively, despite being broken up into smaller, unconnected bits, even on different continents.

Our findings were illuminating. Climate, of course, was an important factor in how many species flourished in a location. But we were intrigued to find that about a third of the variation we found in species diversity across the globe can be attributed solely to the size and degree of isolation of all the instances of a particular climate.

lush green forest scene
The warm, resource-rich Costa Rican tropical forest bursts with biodiversity − partly because it’s a unique climate island amid a vast ocean of varying conditions.
bogdanhoria/iStock via Getty Images Plus

Biodiversity responds not just to the type of climate but its spatial distribution. Beyond the known effects of warmth and moisture, we found that larger and more isolated climates foster greater species diversity. Moreover, these expansive, broken-up climates not only housed a greater number of species but also nurtured a more unique combination of species.

By leveraging but transcending traditional methodologies, our approach unearthed novel insights about the geographical characteristics of climates. We discovered that the larger a climatic zone is, the more fragmented and scattered it tends to be across the landscape.

Isolation spurs diversity

sea of snowy pine trees on mountainous terrain
Cooler extra-tropical climates connect more cohesively around the globe.
Ciprian Boiciuc/Unsplash, CC BY

Traditionally, scientists have thought of tropical climates as cohesive expanses, standing as barriers between the distinct extra-tropical climates of our planet’s poles. Our analysis confirmed that cooler extra-tropical climates are relatively well connected across much of the planet.

Yet, our findings reveal a different narrative for the tropics: Tropical climates appear more as fragmented islands amid a sea of diverse climates, rather than expansive, interconnected realms. Our revelation underscores that tropical climates, while abundant, are dispersed and disjointed across the Earth’s surface.

Drawing a parallel, consider how mountainous regions harbor isolated valleys where people speak distinct dialects shaped by their seclusion. Nature mirrors this: Species in isolated climatic niches evolve distinctly, creating a diverse and unique tableau of life.

The specter of climate change, however, casts a long shadow over these insights. A world undergoing rapid warming might witness once vast climates fragmenting further. Such shifts could challenge species, compelling them to traverse daunting landscapes to find suitable habitats. If these once expansive climates recede, it could disrupt the entire balance of species interactions.

Understanding the interplay between biodiversity and climate is not merely an intellectual pursuit. It provides direction in helping people protect and appreciate the diverse symphony of life in our evolving world.The Conversation

Marco Túlio Pacheco Coelho, Postdoctoral research associate, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL); Catherine Graham, Senior Researcher at Swiss Federal Institute for Forest, Snow and Landscape Research and Adjunct Associate Professor of Ecology and Evolution, Stony Brook University (The State University of New York), and Dave Roberts, Professor Emeritus of Ecology, Montana State University

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

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Mark Zuckerberg thinks workplaces need to ‘man up’ − here’s why that’s bad for all employees, no matter their gender

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theconversation.com – Adam Stanaland, Assistant Professor of Psychology, University of Richmond – 2025-01-23 07:48:00

Meta CEO Mark Zuckerberg attends a UFC match on Feb. 17, 2024.

Sean M. Haffey/Getty Images

Adam Stanaland, University of Richmond

When Meta CEO Mark Zuckerberg appeared on a Jan. 10, 2025, episode of “The Joe Rogan Experience,” he lamented that corporate culture had become too “feminine,” suppressing its “masculine energy” and abandoning supposedly valuable traits such as aggression.

The workplace, he concluded, has been “neutered.”

Perhaps not surprisingly, Zuckerberg has also embraced stereotypically masculine pursuits in his personal life. He’s become a mixed martial arts aficionado and has shared his affinity for smoking meats. On his expansive Hawaii compound, he’s even taken up bow-and-arrow pig hunting.

He’s come a long way from the geeky image of his youth.

But is Zuckerberg right? Do workplaces in the U.S. need to embrace a more diesel-fueled, street-fighting, meat-eating mentality?

As a social psychologist who studies masculinity and aggression, I think it’s important to evaluate what the science says about Zuckerbeg’s claims – and to consider what it means for the future of workplace culture in the U.S.

Show no weakness

In 2018, sociologist Jennifer Berdahl and her colleagues coined the term “masculinity contest culture” to describe workplaces rife with cutthroat competition, toxic leadership, bullying and harassment.

Integrating decades of prior research on masculinity in the workplace, Berdahl and her collaborators were able to map how masculinity contest cultures operate, as well as show how they affect organizations and individual employees.

In her experiments, she had participants agree or disagree with statements such as “expressing any emotion other than anger or pride is seen as weak,” based on their perceptions of their own organization. Using advanced statistical techinques, Berdahl’s team was able to distill masculinity contest cultures down to four components: “showing no weakness,” “strength and stamina,” “putting work first” and “dog eat dog.”

Then they were able to show how these cultures are tied to a host of negative outcomes for workers and companies, such as burnout, turnover and poor well-being. And at the organization level, they can foment a dysfunctional office environment, toxic leadership and even bullying and harassment.

An imagined grievance

Based on this research, then, it seems like promoting rigid masculinity in the workplace is not the best solution for an arguably already struggling Meta.

What, then, led Zuckerberg to claim that the workplace has been neutered and must be infused with masculine energy? Has the American office really gone full “Legally Blonde”?

Zuckerberg’s own company isn’t exactly a paragon of parity: Its total workforce, as of 2022, was nearly two-thirds male, while its tech workforce was three-quarters male. Furthermore, according to psychologists Sapna Cheryan and Hazel Markus, workplaces in the U.S. still reflect what they call “masculine defaults” – cultures that reward characteristics or behaviors generally associated with men.

This can range from how companies describe themselves – for example, as places that are “aggressive” and “unrestrained” – to hosting events catering to traditionally male pursuits, such as golf outings.

A group of men observe another man participating in a golf simulator.

Many workplaces in the U.S. still promote and prize traditionally masculine traits and pursuits.

Daniel Boczarski/Getty Images for PXG

Although Cheryan and Markus’ analysis centers on how masculine defaults make it harder for women to carve out their professional paths, they can harm everybody, including men.

My research, for example, has shown that when men feel pressured to fulfill certain masculine expectations, they can develop fragile masculine identities, which are linked with aggression and anxiety.

Although the pervasiveness of masculinity norms can give men an upper hand in the workplace, I wonder whether men are contorting themselves to fit into outdated molds of who succeeds at work. Indeed, research shows that successful organizations promote a healthy mix of stereotypically masculine and feminine qualities.

In other words, it’s best when people of all genders feel comfortable showcasing traits such as cooperation and agency, qualities that don’t necessarily fall into one gender camp.

The rise of the fragile billionaire

If many workplaces still possess dog-eat-dog cultures and celebrate masculinity – with evidently poor outcomes – you might wonder why billionaire corporate leaders would advocate for them.

The most generous explanation is ignorance. Zuckerberg could simply be unaware that most offices in the U.S. still possess competitive environments and traits associated with traditional masculinity.

Although this could be the case, I think there could be two other explanations for Zuckerberg’s promotion of rigid masculinity norms.

There could be an economic motive. Perhaps Zuckerberg thinks that promoting his company as an arena of high-stakes competition and aggression is the best way to attract talent and spur innovation in a field already dominated by men. It’s often thought that competition drives innovation. So “Meta needs to be more masculine” could actually be code for “Meta needs to breed more internal competition, which will spur innovation and turn a profit.” This assumption is also misguided: Recent research has shown that internal competition may actually stifle innovation.

There could also be a psychological motive. I’ve found in my research that men are most likely to cling to notions of rigid masculinity when they feel pressure to “man up” and are insecure about themselves.

Perhaps Zuckerberg sees diversity efforts as a challenge to his power. Maybe he thinks aligning himself with President Donald Trump’s version of masculinity will help him gain and retain power, especially as he faces challenges from other tech giants. So his promotion of an aggressive workplace, along with his slashing of policies that could make him look “weak,” are moves to reinforce his status as a leader, as an innovator and as a man.

This isn’t to say that activities such as hunting and mixed martial arts are inherently bad, or even inherently masculine: There are plenty of female hunters and UFC fighters. Nor is it to say that certain masculine characteristics in the workplace are inherently bad.

But when I see middle-aged billionaires – Zuckerberg isn’t the only one – exhibiting the signs of fragile masculinity that I’ve observed among young adult men and adolescent boys, I can’t help but wonder what the country’s future holds.The Conversation

Adam Stanaland, Assistant Professor of Psychology, University of Richmond

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

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FDA bans Red 3 dye from food and drugs – a scientist explains the artificial color’s health risks and long history

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theconversation.com – Lorne J. Hofseth, Professor and Associate Dean for Research, College of Pharmacy, University of South Carolina – 2025-01-23 07:45:00

Look out for Red 3, FD&C Red No. 3, erythrosine or E127 in the ingredients list of your favorite processed foods.

Anhelina Chumak/iStock via Getty Images Plus

Lorne J. Hofseth, University of South Carolina

Red 3 – also called FD&C Red No. 3, erythrosine or E127 – has been widely used in food, cosmetics and pharmaceuticals since its FDA approval in 1969. You’ve likely encountered Red 3 before. It’s a common additive to many candies, beverages, baked goods, cereals, maraschino cherries and gelatin desserts, as well as certain medications, syrups and cosmetics.

However, mounting scientific evidence suggests that consuming Red 3 poses significant health risks. These risks prompted California to ban its use in food in 2023 and the Food and Drug Administration to ban its use in both food and pharmaceuticals nationwide on Jan. 15, 2025.

As a researcher studying inflammation and cancer, I investigate how synthetic food dyes affect human health. Stricter regulations reflect growing concerns over the negative physiological effects of Red 3 and other synthetic dyes on your body, including causing cancer.

Health risks of Red 3

Over the past 35 years, an increasing amount of scientific evidence has identified the negative health effects of Red 3. While researchers haven’t yet established a direct link between Red 3 and cancer in people, substantial evidence from animal studies points to its carcinogenic potential.

First, Red 3 disrupts thyroid hormone regulation through several mechanisms. It inhibits the thyroid gland’s ability to absorb iodine, a key component for synthesizing thyroid hormones, and blocks an enzyme essential for converting one thyroid hormone to another, contributing to thyroid dysfunction. Along with other impairments in thyroid hormone function, Red 3 increases the risk of thyroid-related disorders.

Second, Red 3 may promote thyroid tumor formation. Several studies exposing rats and pigs to Red 3 observed enlarged tumorous thyroid glands and abnormalities in hormone regulation.

Third, Red 3 can have toxic effects on the brain in multiple ways. Rat studies have found that this synthetic dye increases oxidative stress, which damages tissues, and reduces the antioxidants that control oxidative stress, impairing communication between neurons. Studies in rodents also found that Red 3 triggers neuroinflammation that leads to neuronal damage and dysfunction. Additionally, Red 3 may interact with the amyloid-beta peptides linked to neurodegenerative conditions like Alzheimer’s disease and worsen those conditions.

Regulatory momentum

Red 3 first faced scrutiny in the 1980s when several animal studies linked it to thyroid tumors in male rats. This led to its 1990 ban in cosmetics in the U.S., although its use in food persisted under industry pressure. While the European Union restricted the use of Red 3 to only certain types of processed cherries in 1994, the U.S. has lagged behind.

California’s 2023 ban of Red 3 in foods, effective in 2027, reignited debate on Red 3 and its link to cancer and spurred 24 organizations to advocate for federal action.

Several countries have banned the use of Red 3 in food. Until January 2025, the U.S. had only banned it in cosmetics and topical drugs.

This debate culminated in the FDA’s nationwide ban in January 2025. While the FDA cites no direct evidence of Red 3’s carcinogenic effect in people, it acknowledges that animal studies provide sufficient basis for regulatory action. The FDA’s decision aligns with the 1958 Delaney Clause of the Federal Food, Drug and Cosmetic Act, mandating a ban on additives shown to cause cancer in humans or animals.

Notably, it took over 35 years from the initial findings of thyroid cancer in rodents to the eventual ban in 2025.

A path forward

The progression from Red 3’s approval to its prohibition highlights the conflict between industrial interests and public health. Continued vigilance over Red 3 could help the nation prioritize consumer safety.

Under the FDA’s mandate, manufacturers must reformulate food products and ingested drugs to leave out Red 3 by January 2027 and January 2028, respectively. While some countries still permit use of Red 3, U.S. imports must meet domestic safety standards. Harmonizing global standards on regulating and evaluating synthetic dyes is essential to protect consumer health.

Close-up of colorful cereal loops

Stronger, more standardized regulation of synthetic food dyes would help protect consumer health.

choness/iStock via Getty Images

Several companies selling ultra-processed foods have begun the shift away from synthetic dyes. In 2016, Mars announced plans to remove all artificial colors from its human food products over a five-year period. In 2024, General Mills announced that it would eliminate artificial colors and flavors from its products.

Consumers can protect themselves from Red 3 exposure by reading ingredient labels for “FD&C Red No. 3” or “E127” and choosing products that use natural dyes. Preparing homemade foods with natural color alternatives like beet juice or turmeric is another option. Supporting dye-free brands and staying informed about regulatory changes can further reduce your exposure while promoting safer food practices.

Ongoing research and policy reforms focused on public safety could help ensure that food additives like Red 3 no longer put consumer health at risk.The Conversation

Lorne J. Hofseth, Professor and Associate Dean for Research, College of Pharmacy, University of South Carolina

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

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As Gaza ceasefire takes hold, Israeli forces turn to Jenin – a regular target seen as a center of Palestinian resistance

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theconversation.com – Maha Nassar, Associate Professor in the School of Middle Eastern and North African Studies, University of Arizona – 2025-01-22 17:42:00

Maha Nassar, University of Arizona

Just two days after a shaky ceasefire took hold in the Gaza Strip, Israel on Jan. 21, 2025, launched a large-scale incursion of the Jenin refugee camp in the West Bank.

Soldiers raided hundreds of homes in the West Bank city in what the Israeli military called a “counterterrorism” operation, aiming to reassert control there. Many analysts have suggested the raid is an attempt by Israeli Prime Minister Benjamin Netanyahu to appease far-right members of his coalition who oppose the ceasefire deal.

Whatever the motive, the offensive has been devastating for many of the camp’s residents. The Israeli military has destroyed infrastructure, closed entrances to local hospitals and forcibly displaced about 2,000 families, according to reports on the raids. As it was, life for inhabitants of the densely populated camp – home to some 24,000 Palestinian refugees – was hard. The West Bank director of UNRWA, the U.N. agency overseeing refugees, recently described camp conditions as “nearly uninhabitable.”

The focus of the latest Israeli operation is not new. The Jenin refugee camp, on the western edge of the town of Jenin in the north of the occupied West Bank, has often experienced violence between Israeli soldiers and Palestinian militants.

That violence has escalated since the Oct. 7, 2023, attacks, when Hamas gunmen led an incursion into Israel in which around 1,200 people were killed. The camp has faced repeated large-scale military operations by Israeli forces, including drone strikes, ground raids, and airstrikes that have caused widespread destruction. Meanwhile, Israeli settlers have torched Palestinian cars and properties, with 64 such attacks in the Jenin area alone since Oct. 7, 2023. Last December, the Palestinian Authority, which coordinates with Israel to oversee security in parts of the West Bank, also attacked local militants.

These events have deepened political tensions and worsened the economic and humanitarian crises in the West Bank. According to the U.N., more than a quarter of the 800-plus Palestinians killed in the West Bank since Oct. 7 attack have come from the Jenin district; several Israeli civilians have also been killed in the West Bank during the same period.

As a scholar of Palestinian history, I see this recent episode as the latest chapter in a much longer history of Palestinian displacement and defiance of Israeli occupation. Understanding this history helps explain why the Jenin camp in particular has become a target of Israeli offensives and a center of Palestinian militant resistance.

Camp conditions

Jenin, an agricultural town that dates back to ancient times, has long been a center of Palestinian resistance. During the 1948 Arab-Israeli War, Arab fighters successfully pushed back Israeli attempts to capture the town.

At the end of that war, the town became a refuge for some of the hundreds of thousands of Palestinian refugees who fled or were expelled from lands that became part of Israel. Jenin, along with the hilly interior of Palestine known as the West Bank, was annexed by Jordan.

The U.N. Relief and Works Agency established the Jenin camp in 1953, just west of the city. Since then, the agency has provided basic services to the camp’s residents, including food, housing and education.

Camp conditions have always been difficult. In the early years of the camp, refugees had to stand in long lines to receive food rations, and for decades their cramped homes lacked electricity or running water.

The Jenin camp soon became the poorest and most densely populated of the West Bank’s 19 refugee camps. And given its location near the “Green Line” – the armistice line that serves as Israel’s de facto border – camp residents who were expelled from northern Palestine could actually see the homes and villages from which they were expelled. But they were prevented from returning to them.

The rise of militancy

Since 1967, Jenin, along with the rest of the West Bank, has been occupied by the Israeli military.

The Israeli occupation of Jenin compounded the difficulties of these refugees. As stateless Palestinians, they couldn’t return home. But under Israeli occupation, they couldn’t live freely in Jenin, either. Human rights groups have long documented what has been described as “systematic oppression,” which includes discriminatory land seizures, forced evictions and travel restrictions.

Seeing no other path forward, many of the camp’s young refugees turned to armed resistance.

In the 1980s, groups such as the Black Panthers, which was affiliated with the Palestinian nationalist Fatah organization, launched attacks on Israeli targets in an effort to end the occupation and liberate their ancestral lands. Throughout the first intifada – a Palestinian uprising lasting from 1987 to 1993 – the Israeli army raided the Jenin camp many times, seeking to arrest members of militant groups. In the process, Israeli forces also sometimes demolished family members’ homes and arrested relatives. Such acts of apparent collective punishment reinforced the idea for many Palestinians that the Israeli occupation could only be ended by force.

A group of men in headscarves stand in front of flags and banners. One holds a pistol up in the air.
Members of the militant group Fatah in Jenin in 1991.
Esaias Baitel/Gamma-Rapho via Getty Images)

The Oslo peace process of the 1990s – which consisted of a series of meetings between Israeli government and Palestinian representatives – led some former militants to hope that the occupation could be ended through negotiations instead. But Jenin’s camp residents remained marginalized in the West Bank and sealed off from Israel, seeing little improvement in their lives, even after the transfer of administrative powers from Israel to the Palestinian Authority in 1995.

Independent projects like the The Freedom Theatre provided some relief to the camp’s refugee children, but it was not enough to overcome the grinding poverty or the violence they faced from Israeli soldiers and settlers. By the time the second intifada broke out in 2000, many of the camp’s teenagers joined militant groups. That included Freedom Theatre co-founder Zakaria Zubeidi, who joined the Fatah-affiliated Al-Aqsa Martyrs Brigade. Like the youth of the 1980s, they, too, concluded that only armed resistance would bring an end to the occupation.

A cycle of violence?

In April 2002, the Israeli army invaded the Jenin camp, hoping to put an end to such armed groups. There were fierce clashes between Israeli soldiers and young Palestinian men in the camp, solidifying Jenin’s reputation among Palestinians as “the capital of the resistance.”

The lack of progress on peace talks since then, Israel’s settlement building on occupied land – deemed illegal under international law – and the inclusion of hard-line Israeli politicians in the government have exacerbated resentment in the camp. Polls show Palestinians increasingly support armed resistance.

Seeking to protect the camp from Israeli incursions, in 2021 a group of local residents formed the Jenin Brigades. While its founder was affiliated with Palestinian Islamic Jihad, the group quickly drew in militants from various political factions. Members acquired weapons, patrolled the streets and fought off Israeli military incursions. By 2022, they had declared parts of the camp to be “liberated” from the Israeli occupation.

Seemingly alarmed by the increase in militancy and the stockpiling of weapons in the camp, Israel dramatically stepped up its raids in 2022. It was during such a raid that Palestinian American journalist Shireen Abu Akleh was killed by an Israeli soldier.

On July 3, 2023, the Israeli military again invaded Jenin, withdrawing after two days of heavy aerial bombardment and a ground invasion that killed 12 Palestinians and wounded over 100.

The latest offensive could well surpass that death toll, with at least 10 killed in the first day of fighting. But the militancy associated with the camp was built on decades of resistance and defiance to occupation that Israel has had little success in extinguishing. Similarly this time, I believe, such militancy within the camp will only increase with the latest deaths and destruction.

This article is an updated version of a story that was first published by The Conversation on July 5, 2023.The Conversation

Maha Nassar, Associate Professor in the School of Middle Eastern and North African Studies, University of Arizona

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

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