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Stuck bridges, buckling roads − extreme heat is wreaking havoc on America’s aging infrastructure

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theconversation.com – Suyun Paul Ham, Associate Professor of Civil Engineering, University of Texas at Arlington – 2024-08-05 07:40:16

When highways buckle, the damage can happen quickly, putting drivers in danger and tying up traffic.
AP Photo/David Goldman

Suyun Paul Ham, University of Texas at Arlington

Summer 2024’s record heat is creating problems for transportation infrastructure, from roads to rails.

New York’s Third Avenue Bridge, which swings open for ship traffic on the Harlem River, was stuck for hours after its metal expanded in the heat and it couldn’t close. Roads have buckled on hot days in several states, including Washington and Wisconsin. Amtrak warned passengers to prepare for heat-related problems hours before a daylong outage between New York and New Jersey; the risks to power lines and rails during high temperatures are a growing source of delays for the train system.

It doesn’t help that the worsening heat is hitting a U.S. infrastructure system that’s already in trouble.

The American Society of Civil Engineers gave U.S. infrastructure an overall grade of C- in its latest national Infrastructure Report Card, released in 2021. While there has been some improvement – about 7.5% of U.S. bridges were in poor condition, compared with over 12% a decade earlier – many bridges are aging, making them difficult to maintain. Forty percent of the road system was considered in poor or mediocre condition, and maintenance costs have substantially increased.

YouTube video
Firefighters try to cool down New York City’s Third Avenue Bridge after its metal expanded in the heat and the bridge couldn’t close. Even relatively young bridges – this one was partially rebuilt in 2004 – can struggle in high heat.

The rate at which a bridge or road deteriorates depends not only on the materials and construction methods used but also on the climate during the structure’s life span. Extreme heat, in particular, significantly affects transportation infrastructure. As climate change progresses, the frequency and intensity of heat waves are expected to increase, exacerbating these issues.

I lead the Smart Infrastructure and Testing Laboratory at the University of Texas at Arlington, where my team works on ways to better monitor the structural health of infrastructure. Here’s why infrastructure struggles in the heat – and how engineers are innovating to help extend its life.

Buckling highways pose a hazard for drivers

When a road is built, it is cut into segments to create space for the pavement to expand during high heat or to contract in the cold. Without that space, the pavement can buckle when the road material heats up. Buckling of concrete pavement has become a serious problem in several states.

Pavement becomes vulnerable to buckling for a number of reasons. The roadway’s design, the materials it is made out of, the climate when it was built and the weather during its lifetime can affect its life span, as can damage to the road and improper repairs.

Extreme temperatures and heavy precipitation can cause significant damage to roadways and jeopardize the structural integrity of rail systems. Additionally, sea-level rise is accelerating coastal erosion that can undermine roads and rail lines. The deterioration of pavement leads to traffic delays and damaged vehicles. And, most critically, it can cause traffic accidents.

YouTube video
Roads have been buckling across Wisconsin this summer.

Hot rails can expand and also buckle

Rail expansion is another significant concern, especially with continuous welded rails like the main lines that trains use.

When temperatures rise, rails expand due to the heat. This expansion can create high pressure and tension within the rail material. Combined with the forces exerted by moving trains, this pressure can cause the tracks to buckle to the side and become misaligned. It is sometimes referred to as a “sun kink.”

Buckling rails are a serious safety hazard that can cause derailments. That’s one of the reasons Amtrak slows its speed in extreme heat, often leading to schedule delays. Washington, D.C.’s Metro cuts its trains speed to a maximum of 35 mph once rails reach a temperature of 135 degrees Fahrenheit (57 degrees Celsius).

High heat caused thermal expansion of the rails, buckling this section of railway.
U.S. Department of Transportation

Predicting these thermal stresses can be challenging. Rail temperature measurements alone are not enough, because there are many unknown factors related to the track’s structure and how it moves. This makes it difficult to accurately forecast how much the rails will expand or contract.

Engineers can reduce rail expansion risk by using heat-resistant materials, such as hypereutectoid rail steel and martensite rail steel, adjusting track design and ensuring timely repairs.

To prevent roadways from buckling, engineers also have protective measures, such as using single-cut sawed joints filled with sealant to provide flexibility while keeping water out. They can also implement cold weather concreting practices that avoid pouring concrete during low temperatures or on cold bases, and they can use stronger and more durable concrete. Performing timely repairs when pavement cracks and becomes damaged can also help avoid buckling.

Keeping infrastructure healthy

Infrastructure health is similar to human health: If doctors detect problems such as tumors or cancer only in the later stages, it is often too late. Like human bodies, infrastructure needs to be maintained from the beginning to reduce costs and increase the potential for effective rehabilitation.

One area my department works on is nondestructive evaluation methods for monitoring infrastructure without causing damage or requiring long road closures.

We use mobile scanning systems that are almost like portable MRI machines to look for weakness or defects in bridges, roads and runways. We are also developing advanced sensors that use mechanical and magnetic field phenomena to assess the condition of infrastructure, and we are using artificial intelligence to spot problems in the materials.

A truck with a row of four scanning devices spaced out behind. Each is about the size of a cinder block.
Devices attached to a vehicle can quickly scan a roadway for weaknesses and defects. They act like mobile MRI machines.
Suyun Paul Ham/University of Texas, Arlington, CC BY-ND
What a scan looks like, with sections in red showing defects in the road lanes.
A scan of a bridge roadway shows areas with weaknesses.
Smart Infrastructure and Testing Laboratory/University of Texas, Arlington

Infrastructure will face increasing challenges as the climate changes and roads, bridges and other infrastructure age. The large number of buckling roadways and other problems this summer highlight the urgent need for resilient infrastructure to stand up to the future.The Conversation

Suyun Paul Ham, Associate Professor of Civil Engineering, University of Texas at Arlington

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

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The Conversation

Are twins allergic to the same things?

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theconversation.com – Breanne Hayes Haney, Allergy and Immunology Fellow-in-Training, School of Medicine, West Virginia University – 2025-04-14 07:42:00

If one has a reaction to a new food, is the other more likely to as well?
BjelicaS/iStock via Getty Images Plus

Breanne Hayes Haney, West Virginia 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.


Are twins allergic to the same things? – Ella, age 7, Philadelphia


Allergies, whether spring sneezes due to pollen or trouble breathing triggered by a certain food, are caused by a combination of someone’s genes and the environment they live in.

The more things two people share, the higher their chances of being allergic to the same things. Twins are more likely to share allergies because of everything they have in common, but the story doesn’t end there.

I’m an allergist and immunologist, and part of my job is treating patients who have environmental, food or drug allergies. Allergies are really complex, and a lot of factors play a role in who gets them and who doesn’t.

What is an allergy?

Your immune system makes defense proteins called antibodies. Their job is to keep watch and attack any invading germs or other dangerous substances that get inside your body before they can make you sick.

An allergy happens when your body mistakes some usually harmless substance for a harmful intruder. These trigger molecules are called allergens.

diagram of Y-shaped antibodies sticking to other molecules
Y-shaped antibodies are meant to grab onto any harmful germs, but sometimes they make a mistake and grab something that isn’t actually a threat: an allergen.
ttsz/iStock via Getty Images Plus

The antibodies stick like suction cups to the allergens, setting off an immune system reaction. That process leads to common allergy symptoms: sneezing, a runny or stuffy nose, itchy, watery eyes, a cough. These symptoms can be annoying but minor.

Allergies can also cause a life-threatening reaction called anaphylaxis that requires immediate medical attention. For example, if someone ate a food they were allergic to, and then had throat swelling and a rash, that would be considered anaphylaxis.

The traditional treatment for anaphylaxis is a shot of the hormone epinephrine into the leg muscle. Allergy sufferers can also carry an auto-injector to give themselves an emergency shot in case of a life-threatening case of anaphylaxis. An epinephrine nasal spray is now available, too, which also works very quickly.

A person can be allergic to things outdoors, like grass or tree pollen and bee stings, or indoors, like pets and tiny bugs called dust mites that hang out in carpets and mattresses.

A person can also be allergic to foods. Food allergies affect 4% to 5% of the population. The most common are to cow’s milk, eggs, wheat, soy, peanuts, tree nuts, fish, shellfish and sesame. Sometimes people grow out of allergies, and sometimes they are lifelong.

Who gets allergies?

Each antibody has a specific target, which is why some people may only be allergic to one thing.

The antibodies responsible for allergies also take care of cleaning up any parasites that your body encounters. Thanks to modern medicine, people in the United States rarely deal with parasites. Those antibodies are still ready to fight, though, and sometimes they misfire at silly things, like pollen or food.

Hygiene and the environment around you can also play a role in how likely it is you’ll develop allergies. Basically, the more different kinds of bacteria that you’re exposed to earlier in life, the less likely you are to develop allergies. Studies have even shown that kids who grow up on farms, kids who have pets before the age of 5, and kids who have a lot of siblings are less likely to develop allergies. Being breastfed as a baby can also protect against having allergies.

Children who grow up in cities are more likely to develop allergies, probably due to air pollution, as are children who are around people who smoke.

Kids are less likely to develop food allergies if they try foods early in life rather than waiting until they are older. Sometimes a certain job can contribute to an adult developing environmental allergies. For example, hairdressers, bakers and car mechanics can develop allergies due to chemicals they work with.

Genetics can also play a huge role in why some people develop allergies. If a mom or dad has environmental or food allergies, their child is more likely to have allergies. Specifically for peanut allergies, if your parent or sibling is allergic to peanuts, you are seven times more likely to be allergic to peanuts!

two boys in identical shirts side by side look at each other
Do you have an allergy twin in your family?
Ronnie Kaufman/DigitalVision via Getty Images Plus

Identical in allergies?

Back to the idea of twins: Yes, they can be allergic to the same things, but not always.

Researchers in Australia found that 60% to 70% of twins in one study both had environmental allergies, and identical twins were more likely to share allergies than fraternal (nonidentical) twins. Identical twins share 100% of their genes, while fraternal twins only share about 50% of their genes, the same as any pair of siblings.

A lot more research has been done on the genetics of food allergies. One peanut allergy study found that identical twins were more likely to both be allergic to peanuts than fraternal twins were.

So, twins can be allergic to the same things, and it’s more likely that they will be, based on their shared genetics and growing up together. But twins aren’t automatically allergic to the exact same things.

Imagine if two twins are separated at birth and raised in different homes: one on a farm with pets and one in the inner city. What if one’s parents smoke, and the others don’t? What if one lives with a lot of siblings and the other is an only child? They certainly could develop different allergies, or maybe not develop allergies at all.

Scientists like me are continuing to research allergies, and we hope to have more answers in the future.


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

Breanne Hayes Haney, Allergy and Immunology Fellow-in-Training, School of Medicine, West Virginia University

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

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AI-generated images can exploit how your mind works − here’s why they fool you and how to spot them

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theconversation.com – Arryn Robbins, Assistant Professor of Psychology, University of Richmond – 2025-04-11 07:43:00

A beautiful kitchen to scroll past – but check out the clock.
Tiny Homes via Facebook

Arryn Robbins, University of Richmond

I’m more of a scroller than a poster on social media. Like many people, I wind down at the end of the day with a scroll binge, taking in videos of Italian grandmothers making pasta or baby pygmy hippos frolicking.

For a while, my feed was filled with immaculately designed tiny homes, fueling my desire for minimalist paradise. Then, I started seeing AI-generated images; many contained obvious errors such as staircases to nowhere or sinks within sinks. Yet, commenters rarely pointed them out, instead admiring the aesthetic.

These images were clearly AI-generated and didn’t depict reality. Did people just not notice? Not care?

As a cognitive psychologist, I’d guess “yes” and “yes.” My expertise is in how people process and use visual information. I primarily investigate how people look for objects and information visually, from the mundane searches of daily life, such as trying to find a dropped earring, to more critical searches, like those conducted by radiologists or search-and-rescue teams.

With my understanding of how people process images and notice − or don’t notice − detail, it’s not surprising to me that people aren’t tuning in to the fact that many images are AI-generated.

We’ve been here before

The struggle to detect AI-generated images mirrors past detection challenges such as spotting photoshopped images or computer-generated images in movies.

But there’s a key difference: Photo editing and CGI require intentional design by artists, while AI images are generated by algorithms trained on datasets, often without human oversight. The lack of oversight can lead to imperfections or inconsistencies that can feel unnatural, such as the unrealistic physics or lack of consistency between frames that characterize what’s sometimes called “AI slop.”

Despite these differences, studies show people struggle to distinguish real images from synthetic ones, regardless of origin. Even when explicitly asked to identify images as real, synthetic or AI-generated, accuracy hovers near the level of chance, meaning people did only a little better than if they’d just guessed.

In everyday interactions, where you aren’t actively scrutinizing images, your ability to detect synthetic content might even be weaker.

Attention shapes what you see, what you miss

Spotting errors in AI images requires noticing small details, but the human visual system isn’t wired for that when you’re casually scrolling. Instead, while online, people take in the gist of what they’re viewing and can overlook subtle inconsistencies.

Visual attention operates like a zoom lens: You scan broadly to get an overview of your environment or phone screen, but fine details require focused effort. Human perceptual systems evolved to quickly assess environments for any threats to survival, with sensitivity to sudden changes − such as a quick-moving predator − sacrificing precision for speed of detection.

This speed-accuracy trade-off allows for rapid, efficient processing, which helped early humans survive in natural settings. But it’s a mismatch with modern tasks such as scrolling through devices, where small mistakes or unusual details in AI-generated images can easily go unnoticed.

People also miss things they aren’t actively paying attention to or looking for. Psychologists call this inattentional blindness: Focusing on one task causes you to overlook other details, even obvious ones. In the famous invisible gorilla study, participants asked to count basketball passes in a video failed to notice someone in a gorilla suit walking through the middle of the scene.

YouTube video
If you’re counting how many passes the people in white make, do you even notice someone walk through in a gorilla suit?

Similarly, when your focus is on the broader content of an AI image, such as a cozy tiny home, you’re less likely to notice subtle distortions. In a way, the sixth finger in an AI image is today’s invisible gorilla − hiding in plain sight because you’re not looking for it.

Efficiency over accuracy in thinking

Our cognitive limitations go beyond visual perception. Human thinking uses two types of processing: fast, intuitive thinking based on mental shortcuts, and slower, analytical thinking that requires effort. When scrolling, our fast system likely dominates, leading us to accept images at face value.

Adding to this issue is the tendency to seek information that confirms your beliefs or reject information that goes against them. This means AI-generated images are more likely to slip by you when they align with your expectations or worldviews. If an AI-generated image of a basketball player making an impossible shot jibes with a fan’s excitement, they might accept it, even if something feels exaggerated.

While not a big deal for tiny home aesthetics, these issues become concerning when AI-generated images may be used to influence public opinion. For example, research shows that people tend to assume images are relevant to accompanying text. Even when the images provide no actual evidence, they make people more likely to accept the text’s claims as true.

Misleading real or generated images can make false claims seem more believable and even cause people to misremember real events. AI-generated images have the power to shape opinions and spread misinformation in ways that are difficult to counter.

Beating the machine

While AI gets better at detecting AI, humans need tools to do the same. Here’s how:

  1. Trust your gut. If something feels off, it probably is. Your brain expertly recognizes objects and faces, even under varying conditions. Perhaps you’ve experienced what psychologists call the uncanny valley and felt unease with certain humanoid faces. This experience shows people can detect anomalies, even when they can’t fully explain what’s wrong.
  2. Scan for clues. AI struggles with certain elements: hands, text, reflections, lighting inconsistencies and unnatural textures. If an image seems suspicious, take a closer look.
  3. Think critically. Sometimes, AI generates photorealistic images with impossible scenarios. If you see a political figure casually surprising baristas or a celebrity eating concrete, ask yourself: Does this make sense? If not, it’s probably fake.
  4. Check the source. Is the poster a real person? Reverse image search can help trace a picture’s origin. If the metadata is missing, it might be generated by AI.

AI-generated images are becoming harder to spot. During scrolling, the brain processes visuals quickly, not critically, making it easy to miss details that reveal a fake. As technology advances, slow down, look closer and think critically.The Conversation

Arryn Robbins, Assistant Professor of Psychology, University of Richmond

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Trump’s nomination for NASA leader boasts business and commercial spaceflight experience during a period of uncertainty for the agency

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theconversation.com – Wendy Whitman Cobb, Professor of Strategy and Security Studies, Air University – 2025-04-10 07:54:00

Jared Isaacman, the nominee for next NASA administrator, has traveled to orbit on two commercial space missions.
AP Photo/John Raoux

Wendy Whitman Cobb, Air University

Jared Isaacman, billionaire, CEO and nominee to become the next NASA administrator, faced questions on April 9, 2025, from members of the Senate Committee on Commerce, Science, and Transportation during his confirmation hearing for the position.

Should the Senate confirm him, Isaacman will be the first billionaire – but not the first astronaut – to head NASA. Perhaps even more significant, he will be the first NASA administrator with significant ties to the commercial space industry.

As a space policy expert, I know that NASA leadership matters. The head of the agency can significantly shape the missions it pursues, the science it undertakes and, ultimately, the outcome of America’s space exploration.

A man with short dark hair wearing a black jumpsuit with an American flag patch and the Polaris mission insignia.
Jared Isaacman speaks at a news conference in 2024, before his Polaris Dawn mission.
AP Photo/John Raoux, File

An unconventional background

At 16 years old, Isaacman dropped out of high school to start a payment processing company in his basement. The endeavor succeeded and eventually became known as Shift4.

Though he found early success in business, Isaacman also had a love for aviation. In 2009, he set a record for flying around the Earth in a light jet, beating the previous record by more than 20 hours.

While remaining CEO of Shift4, Isaacman founded another company, Draken International. The company eventually assembled the world’s largest fleet of privately owned fighter jets. It now helps to train U.S. Air Force pilots.

In 2019, Isaacman sold his stake in Draken International. In 2020, he took Shift4 public, making him a billionaire.

Isaacman continued to branch out into aerospace, working with SpaceX beginning in 2021. He purchased a crewed flight on the Falcon 9 rocket, a mission that eventually was called Inspiration4. The mission, which he led, represented the first private astronaut flight for SpaceX. It sent four civilians with no previous formal space experience into orbit.

Following the success of Inspiration4, Isaacman worked with SpaceX to develop the Polaris Program, a series of three missions to help build SpaceX’s human spaceflight capabilities. In fall 2024, the first of these missions, Polaris Dawn, launched.

Polaris Dawn added more accomplishments to Isaacman’s resume. Isaacman, along with his crewmate Sarah Gillis, completed the first private spacewalk. Polaris Dawn’s SpaceX Dragon capsule traveled more than 850 miles (1,367 kilometers) from Earth, the farthest distance humans had been since the Apollo missions.

A rocket launching into a dark sky, leaving behind a cloud of smoke.
The Polaris Dawn mission launched on a SpaceX Falcon 9 rocket in September 2024.
AP Photo/John Raoux

The next adventure: NASA

In December 2024, the incoming Trump administration announced its intention to nominate Isaacman for the post of NASA administrator.

As NASA administrator, Isaacman would oversee all NASA activities at a critical moment in its history. The Artemis program, which has been in progress since 2017, has several missions planned for the next few years.

This includes 2026’s Artemis II mission, which will send four astronauts to orbit the Moon. Then, in 2027, Artemis III will aim to land on it.

Four astronauts in blue NASA jumpsuits standing in front of a conical metal capsule.
If the mission proceeds as planned, the Artemis II crew will fly in an Orion crew capsule, pictured behind them, around the Moon in 2026.
Kim Shiflett/NASA via AP, File

But, if Isaacman is confirmed, his tenure would come at a time when there are significant questions about the Artemis program, as well as the extent to which NASA should use commercial space companies like SpaceX. The agency is also potentially facing funding cuts.

Some in the space industry have proposed scrapping the Artemis program altogether in favor of preparing to go to Mars. Among this group is the founder of SpaceX, Elon Musk.

Others have suggested canceling NASA’s Space Launch System, the massive rocket that is being used for Artemis. Instead, they argue that NASA could use commercial systems, like SpaceX’s Starship or Blue Origin’s New Glenn.

Isaacman has also dealt with accusations that he is too close to the commercial space industry, and SpaceX in particular, to lead NASA. This has become a larger concern given Musk’s involvement in the Trump administration and its cost-cutting efforts. Some critics are worried that Musk would have an even greater say in NASA if Isaacman is confirmed.

Since his nomination, Isaacman has stopped working with SpaceX on the Polaris Program. He has also made several supportive comments toward other commercial companies.

But the success of any of NASA’s plans depends on having the money and resources necessary to carry them out.

While NASA has been spared major cuts up to this point, it, like many other government agencies, is planning for budget cuts and mass firings. These potential cuts are similar to what other agencies such as the Department of Health and Human Services have recently made.

During his confirmation hearing, Isaacman committed to keeping the Artemis program, as well as the Space Launch System, in the short term. He also insisted that NASA could both return to the Moon and prepare for Mars at the same time.

Although Isaacman stated that he believed NASA had the resources to do both at the same time, the agency is still in a time of budget uncertainty, so that may not be possible.

About his relationship with Musk, Isaacman stated that he had not talked to Musk since his nomination in November, and his relationship with SpaceX would not influence his decisions.

Additionally, he committed to carrying out space science missions, specifically to “launch more telescopes, more probes, more rovers.”

But since NASA is preparing for significant cuts to its science budget, there is some speculation that the agency may need to end some science programs, like the Hubble space telescope, altogether.

Isaacman’s future

Isaacman has received support from the larger space community. Nearly 30 astronauts signed a letter in support of his nomination. Former NASA administrators, as well as major industry groups, have signaled their desire for Isaacman’s confirmation.

He also received the support of Senator Ted Cruz, the committee chair.

Barring any major development, Isaacman will likely be confirmed as NASA administrator by the Senate in the coming weeks. The Committee on Commerce, Science, and Transportation could approve his nomination once it returns from a two-week break at the end of April. A full vote from the Senate would follow.

If the Senate does confirm him, Isaacman will have several major issues to confront at NASA, all in a very uncertain political environment.The Conversation

Wendy Whitman Cobb, Professor of Strategy and Security Studies, Air University

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

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