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Low-level blasts from heavy weapons can cause traumatic brain injury − 2 engineers explain the physics of invisible cell death

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Low-level blasts from heavy weapons can cause traumatic brain injury − 2 engineers explain the physics of invisible cell death

Low-level blasts can cause physical changes in the brain.
Libkos/AP Photo

Alice Lux Fawzi, University of Wisconsin-Madison and Christian Franck, University of Wisconsin-Madison

When the force of a blast shoots a round out of a large-caliber rifle, howitzer or M1 Abrams tank gun, the teams of people operating these weapons are exposed to low-level blasts that can cause traumatic brain injuries.

Low-level blasts do not cause visible trauma, such as bleeding from ruptured eardrums, and they don’t cause injury through violent head motion, such as a concussion. Yet, these blasts can cause physical changes in the brain that lead to a host of neuropsychiatric symptoms.

The link between the force of a blast and the resulting changes in the brain is not completely understood. So our team of engineers and scientists in the PANTHER program, funded by the Department of Defense, is using physics to elucidate how blasts cause traumatic brain injury.

What is a blast?

When a weapon like a rifle is fired, the round is initially in its barrel. Pulling the trigger engages a primer that produces a flame, igniting the propellant. This chemical reaction releases stored energy and creates high-pressure, rapidly expanding gas. This is the blast.

The rate and magnitude of gas expansion are often so extreme that they create a shock wave, where high-pressure air molecules travel outward faster than the speed of sound. This invisible pulse of high pressure carries a tremendous amount of energy. It’s the same force that can propel a 24-pound warhead out of the muzzle of a howitzer to hit a target 19 miles (30.6 kilometers) away.

Cross-section of a cartridge
This cross-section shows: 1. bullet; 2. case; 3. gunpowder; 4. rim; and 5. primer.
Glrx/Quadrell via Wikimedia Commons, CC BY-SA

After the blast leaves the gun’s muzzle, it dissipates quickly because it is free to expand in the open air. This is when the high pressure washes over the bodies of nearby people.

The blast from the muzzle of a large gun like the M777 howitzer does not pulverize rocks or knock someone off their feet. But some of the blast pressure enters the body, passing through the skin and rigid skull bone and into the soft tissue of the brain.

Linking blast to brain injury

As blast pressure enters the brain, it is initially compressive, meaning it squeezes the tissue equally from all sides. Because brain tissue is largely composed of water molecules, which are difficult to compress, this type of pressure tends to cause little known harm to cells.

An initially compressive wave, or positive pressure wave, that squeezes brain tissue changes when it bounces off the inside of the skull. It is reflected as a tensile wave, or negative pressure wave, which tends to pull brain tissue apart. With low enough pressures, micron-sized bubbles can form in a process called cavitation. These bubbles can grow 10 to 50 times their initial size over the course of less than a tenth of a millisecond, rapidly stretching the adjacent brain tissue.

Experiments from our lab have shown that the deformation caused by cavitation bubbles happens so rapidly – like the speed of a bullet – that cells tend to get torn apart. The extreme speed of stretching and squeezing causes nearby brain cells to die immediately. Afterward, we see only fragments where healthy cells used to be.

Diagram showing blast pressure creating microbubbles in the brain after reflecting off surfaces, stretching and destroying cells in a process called cavitation.
This diagram depicts how blast pressure from a gun can result in brain trauma.
Alice Lux Fawzi and Manik Bansal., CC BY-NC-ND

Cell death is the physical root cause of brain injury. In the lab, when the cells that make up brain tissue are deformed at a magnitude and rate beyond what they can withstand, they die – either immediately, as in the case of blast-induced cavitation, or slowly over six to 24 hours, as in most brain injuries from blunt impacts such as concussions.

In low-level blast exposure, the cavitation bubbles are very small, and the trauma is contained to the small area around them. However, repeated exposure to blasts can lead to an accumulation of these microtraumas, eventually reaching a volume large enough to cause significant and irreversible neurological symptoms.

Although evidence is mounting, it has yet to be fully proven that cavitation directly causes blast-induced traumatic brain injury. The hypothesis fits with post-mortem analyses of the brains of service members with a history of blast exposure. It also fits with the physics that link blast exposure to injury from tissue deformation.

Understanding the connection between blasts and cellular damage in the brain will help researchers develop better ways to protect against repetitive blast-induced traumatic brain injury.The Conversation

Alice Lux Fawzi, PANTHER Engineering Project Manager and Associate Director of the Center for Traumatic Brain Injury, University of Wisconsin-Madison and Christian Franck, Bjorn Borgen Professor of Mechanical Engineering and Director of the Center for Traumatic Brain Injury, University of Wisconsin-Madison, University of Wisconsin-Madison

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

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Understanding paranormal beliefs and conspiracy theories isn’t just about misinformation – this course unpacks the history

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theconversation.com – Jeb Card, Associate Teaching Professor of Anthropology, Miami University – 2025-01-27 07:50:00

Understanding paranormal beliefs and conspiracy theories isn’t just about misinformation – this course unpacks the history

The ‘black mailbox’ along Highway 375 near Rachel, Nev., a traditional spot for UFO hunters to meet and search the skies near Area 51.
AP Photo/John Locher

Jeb Card, Miami University

Uncommon Courses is an occasional series from The Conversation U.S. highlighting unconventional approaches to teaching.

Title of course:

“Investigating the Paranormal”

What prompted the idea for the course?

My training and professional work have been in Mesoamerican archaeology, but I’ve had a lifelong fascination with paranormal concepts. In fact, I considered studying the UFO community for my doctoral research in cultural anthropology.

I eventually fused these two interests in my book “Spooky Archaeology: Myth and the Science of the Past,” which examines why archaeology shows up so much in ideas about the mysterious and weird. Most people are familiar with pop culture characters like Indiana Jones seeking magical artifacts. Perhaps less immediately obvious is just how common archaeological topics are in paranormal and conspiracy culture.

The popularity of paranormal ideas – from television shows and thousands of podcasts to UFOs on the front page of The New York Times and in government investigations – made it clear that a course on paranormal culture would be an excellent way for students to get a taste of social science research.

What does the course explore?

The material begins with premodern ideas of magic, myth and metaphysics. The narrative that “Western” societies tell of the development of the modern world is that the Enlightenment cast off supernatural thinking in favor of science. The historical reality, however, is not so simple.

As science based on observation of material evidence emerged in the 17th through 19th centuries, so did a paranormal worldview: theories about a nonmaterial or hidden reality beyond the mundane, from monsters to psychic powers. Some of these ideas were tied to older religious notions of the sacred or strange but not divine phenomena. Others were new – particularly those suggesting the hidden existence of prehistoric extinct creatures or lost cities.

In either case, the key element was that proponents of these ideas often tried to support their existence with the kind of evidence used in science, though their “proofs” fell short of scientific standards. In other words, the paranormal is in conflict with the knowledge and worldview of modernity but also attempts to use the concepts of modernity to oppose it.

The class examines how this tension produced 20th century “-ologies” like parapsychology, which examines evidence for consciousness beyond matter, and cryptozoology, which searches the ends of the Earth for creatures tied to the mythic past. We also learn about UFOlogy, whose proponents have collected alleged contacts with technology and beings from beyond this world ever since the Cold War, as great earthly powers filled the skies with secretive hi-tech aircraft and spaceships.

As the class concludes, we examine how the “-ologies” declined after the Cold War, alongside the cultural capital of science, whose height of public respect was in the mid-20th century. Since then, proving the existence of paranormal things to institutional scientists has become less important in paranormal communities than promoting them to a broader public.

Why is this course relevant now?

Beyond public interest in paranormal topics, the paranormal is entwined with sociocultural forces that have dramatically increased the role of conspiracy rhetoric in the United States and elsewhere. At their core, both types of belief claim to have figured out some kind of supposedly hidden knowledge.

Furthermore, the conspiracy theories that are now commonplace in American political discourse are more rooted in paranormal ideas than in previous decades. Conspiracy theories about the JFK assassination or even 9/11 were still largely within the materialist realm. People argued that “the truth” had been covered up, but their arguments did not rely on metaphysical ideas. Today, major conspiracy theories involve secret cabals, mystical symbols and code words, demonic forces and extraterrestrial entities.

What’s a critical lesson from the course?

Evidence must be interrogated on its own, regardless of whether it fits your perspective. I find time and again that students have a hard time approaching evidence without bias, whether that bias is conscious or not: “knowing” that something must be true, or must be absurd.

One person apparently makes a death bed confession of faking a famous Loch Ness Monster photo, pleasing skeptics. Another claims to have seen a Bigfoot at close range, pleasing believers. Without further evidence, both are stories: no more, no less.

The issue isn’t to draw an equivalence between the bigger concepts. Not all narratives are equally well-founded. But students learn how to collect evidence, rather than simply rely on their gut sense of what is plausible or not.

What will the course prepare students to do?

This course is meant to help students discern useful and reliable information about claims and events, separating them from irrelevant or inaccurate narratives or sources. The goal is not just “critical thinking” aimed at combating disinformation, though that is part of what they should learn. Students practice evaluating evidence but also develop an approach for analyzing and understanding phenomena behind it: how factors like history, culture and institutions of authority, such as science and government, shape what people trust and what they believe.The Conversation

Jeb Card, Associate Teaching Professor of Anthropology, Miami University

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Can Trump just order new names for Denali and the Gulf of Mexico? A geographer explains who decides what goes on the map

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theconversation.com – Innisfree McKinnon, Associate Professor of Geography, University of Wisconsin-Stout – 2025-01-24 15:02:00

Known as Mount McKinley until 2015, Denali’s current name reflects what Native Alaskans call the mountain.
Arterra/Universal Images Group via Getty Images

Innisfree McKinnon, University of Wisconsin-Stout

President Donald Trump’s executive order to rename the Gulf of Mexico and Alaska’s Denali, the tallest peak in the country, has resulted in lots of discussion. While for some, such renaming might seem less important than the big problems the country faces, there is a formal process in the United States for renaming places, and that process is taken seriously.

Usually, so people don’t get confused, official, agreed-upon names are used by the government. In the U.S., place names are standardized by the U.S. Board on Geographic Names, which is part of the U.S. Geological Survey, the agency in charge of making maps.

In his executive order, Trump asks the Board on Geographic Names “to honor the contributions of visionary and patriotic Americans” and change its policies and procedures to reflect that.

Usually, renaming a place starts locally. The people in the state or county propose a name change and gather support. The process in each state is different.

A lake with sailboats and a city skyline in the background
Lake Bde Maka Ska, formerly Lake Calhoun, is the largest lake in Minneapolis.
YinYang/E+ via Getty

How to change a place name

Minnesota recently changed the name of a large lake in Minneapolis to Bde Maka Ska, which the Minneapolis Park Board described as “a Dakota name for the lake that has been passed down in oral history for many years.”

The board voted to change the name and took its request to the county commissioners. When the county agreed, the request was then sent to the Minnesota Department of Natural Resources, which made it official for Minnesota. Then, the state of Minnesota sent the request to the Board on Geographic Names, which made it official for the entire U.S.

It’s a lot of paperwork for something so seemingly minor, but people get passionate about place names. It took 40 years to rename Denali from the name established in the late 19th century, Mount McKinley.

The state of Alaska requested the name change in 1975, but the Board on Geographic Names didn’t take action. Members of the Ohio congressional delegation – President William McKinley was from Ohio – objected over many years to requests to rename the mountain, and the board did not act on those requests.

The president appoints the secretary of the Interior Department. The secretary works with the heads of related agencies to appoint the Board on Geographic Names. Current committee policy states, “Input from State geographic names authorities, land
management agencies, local governments, and Tribal Governments
are actively pursued.”

In 2015, President Barack Obama named a new leader for the Department of the Interior, Sally Jewell. Just as Obama made a trip to Alaska in late August 2015, Jewell declared the name change official under a law that allows the secretary of the Interior to change a name if the board doesn’t act on the proposal in a “reasonable” amount of time.

“This name change recognizes the sacred status of Denali to many Alaska Natives,” Jewell said. “The name Denali has been official for use by the State of Alaska since 1975, but even more importantly, the mountain has been known as Denali for generations. With our own sense of reverence for this place, we are officially renaming the mountain Denali in recognition of the traditions of Alaska Natives and the strong support of the people of Alaska.”

If someone objects to a name change, they could ask the courts to rule on whether the name change was made legally. Going back to Bde Maka Ska, some people objected to changing the name from Lake Calhoun, so they took the state natural resources agency to court. Eventually, the Minnesota Supreme Court ruled that the name change was done correctly.

Alaska’s two U.S. senators and prominent state figures have strongly objected to Trump’s renaming attempt.

How not to change a place name

Renaming the Gulf of Mexico is a different kind of case, however, from renaming a geographic place within U.S. borders.

The gulf is not within the territorial U.S. On the coast, the first 12 miles from shore are considered part of that country, but outside of that is international waters.

The Board on Geographic Names could change the name to Gulf of America on official U.S. maps, but there is no international board in charge of place names. Each country decides what to call places. And there is no official way for the U.S. to make other countries change the name.

It’s possible that the U.S. could formally ask other countries to change the name, or even impose sanctions against countries that don’t comply.

If the names were officially changed in the U.S., the government would use the new names in official documents, signage and maps. As for all the people and companies in the world that make maps, they usually use the official names. But there is nothing that would force them to, if they believed that a certain name is more widely recognized.The Conversation

Innisfree McKinnon, Associate Professor of Geography, University of Wisconsin-Stout

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Trump inherits the Guantánamo prison, complete with 4 ‘forever prisoners’

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theconversation.com – Lisa Hajjar, Professor of Sociology, University of California, Santa Barbara – 2025-01-24 10:57:00

A control tower overlooks the Camp VI detention facility, at Guantánamo Bay Naval Base, Cuba.
AP Photo/Alex Brandon

Lisa Hajjar, University of California, Santa Barbara

President Joe Biden’s record of handling the U.S. military prison at Guantánamo Bay, Cuba, is decidedly mixed. He succeeded in reducing the detainee population he inherited by more than half, but he compounded problems in the military commissions that the Bush administration had invented in the wake of the 9/11 attacks to try people captured in the “war on terror.” Now all the problems at Guantánamo are again President Donald Trump’s.

When Biden took office in 2021, there were 40 prisoners. Today there are 15, the lowest number since the first 20 Muslim men and boys captured in Afghanistan were airlifted to the base on Jan. 11, 2002.

Biden left Trump four people the U.S. will not release but also cannot put on trial – the so-called “forever prisoners.” He also left intact the troubled military commissions system, with three pending criminal cases against a total of six detainees.

In December 2021, former chief military defense attorney Brig. Gen. John Baker testified before the Senate Judiciary Committee: “It is too late in the process for the current military commissions to do justice for anyone. The best that can be hoped for at this point … is to bring this sordid chapter of American history to an end.” Baker made clear that the only viable option is to resolve the cases with plea bargains for the defendants.

Marine Brig. Gen. John Baker tells U.S. senators that there is no opportunity for justice to be done at Guantánamo.

A chance to make progress

There are three cases that have not yet gone to trial – the 9/11 case with four defendants facing charges for their connections with the attacks, the USS Cole bombing in October 2000 with one defendant and the Bali bombing in October 2002 with one defendant.

The 9/11 and USS Cole cases have been stuck in the pretrial phase since Biden was Barack Obama’s vice president. In the summer of 2024, a breakthrough in the 9/11 case appeared imminent: Prosecutors and defense lawyers for three of the four defendants reportedly reached plea-bargain agreements. Khalid Sheikh Mohammad – the alleged “mastermind” of the attacks – Walid bin Attash and Mustafa Hawsawi agreed to plead guilty and accept life sentences in exchange for the government taking the death penalty off the table. There was no deal for the fourth 9/11 defendant, Ammar al-Baluchi.

The deals were approved on July 31 by the top military officer overseeing the Guantánamo commissions, retired Brig. Gen. Susan Escallier. But two days later, Biden’s defense secretary, Lloyd Austin, stepped into the process and overrode Escallier – whom he had appointed. Austin announced that the plea deals were revoked.

The judge, Air Force Col. Matthew McCall, decided to schedule plea hearings for early January. But after some legal back-and-forth that forced a stay, he had to cancel them. Biden left the case against three 9/11 defendants in limbo.

A beige one-story building with a sign above the door.
The basement of this government building in Bucharest, Romania, held a secret CIA prison, one of many across the world.
AP Photo

Witness to the transition

In mid-January 2025, I made my sixteenth reporting trip to Guantánamo. I came for closing arguments on a motion in the 9/11 case that seeks to suppress statements that Ammar al-Baluchi made to the FBI in January 2007. That was four months after he and 13 others were transferred to Guantánamo from CIA black sites where they were held for years. The litigation to suppress those statements started in 2019.

In Chapter 10 of my book, “The War in Court: Inside the Long Fight against Torture,” I detail how the litigation on this suppression motion made public previously unknown details and under-acknowledged horrors of the CIA’s rendition, detention and interrogation program.

These closing arguments were the culmination of six years of litigation on the key question in the 9/11 case: Does torture matter in the pursuit of justice in the military commissions?

A figure strapped to a table has water poured on its face.
A drawing by Guantánamo detainee Abu Zubaydah depicts a person being waterboarded.
Copyright Abu Zubaydah 2019. Licensed by Professor Mark Denbeaux, Seton Hall Law School

Can Guantánamo be closed?

Of the 780 people ever detained at Guantánamo, 540 were released during the presidency of George W. Bush, who established the detention facility. Obama, who signed an executive order on his second day in office pledging to close Guantánamo within a year, released 200.

In his first term, Trump pledged to keep the facility open. The only man to leave Guantánamo during Trump’s first term was Ahmed al-Darbi, who was repatriated to Saudi Arabia in 2018 to serve out the remainder of his sentence from a 2014 plea bargain agreement.

When Biden took office, he said that he supported shutting down the military prison at Guantánamo. In the early years of his presidency, there was a slow stream of transfers, mostly people who had been cleared for release long ago and were freed.

In Biden’s last months, the pace of transfers quickened. In December 2024, a Kenyan detainee, two Malaysian members of al-Qaida who had pled guilty the previous January, and a Tunisian man who had been in Guantánamo since the day the facility was opened were all repatriated to their countries of origin and freed. In January 2024, 11 Yemenis were transported from the prison to Oman to be resettled.

15 men left behind

The Biden administration had also planned to repatriate a severely disabled Iraqi detainee, Abd al-Hadi al-Iraqi, to serve out his plea-bargained sentence in a Baghdad prison. But a federal judge blocked that transfer, ruling that al-Iraqi would not get necessary medical treatment in Iraq and might be subject to abuse there.

Al-Iraqi is one of the 15 that Biden left behind. Three of them – a Libyan, a Somali and a stateless Rohingya – have long been cleared for release. Their continuing detention without charges highlights a key element of the Guantánamo problem: No one can be released unless the U.S. government finds another country willing to accept them.

One of the remaining detainees, Ali Bahlul, is serving a life sentence for conspiracy to commit war crimes. Six others, including the four 9/11 defendants, are awaiting their trials.

There are also four detainees whom the government refuses to transfer but cannot put on trial for lack of evidence.

A man wearing a beard, mustache and glasses.
The U.S. goverment says it cannot release Abu Zubaydah from Guantánamo because he would disclose classified interrogation techniques critics have labeled torture.
U.S. Central Command via AP

These so-called “forever prisoners” include Abu Zubaydah, a Saudi-born man of Palestinian descent who was taken into CIA custody in 2002 and was used as the guinea pig for the CIA torture program. The government long ago conceded that Abu Zubaydah was not a top leader of al-Qaida – in fact he was not even a member. But he will not be released because he knows how he was treated by the CIA, and that treatment remains highly classified.

The newest forever prisoner is one of the original 9/11 defendants, Ramzi bin al-Shibh; in September 2023, he was declared mentally incompetent to stand trial. Now he is uncharged, unreleased and untreated for his psychological maladies that were caused by the torture he endured in CIA black sites.

The ‘War on Terror’ is not over

When Biden pulled U.S. troops out of Afghanistan in August 2021, he claimed to have ended America’s longest war – and repeated this claim in a January 2025 speech. But the Guantánamo prison remains open, and as long as it is, the “war on terror,” which first put U.S. troops in Afghanistan in 2001, is not over.

How Trump will deal with Guantánamo is an open question. If he focuses on the death penalty, he will press ahead with military commission trials like his predecessors, hoping for unanimous guilty verdicts and death sentences. If he prioritizes cutting wasteful government spending, he will release additional detainees and allow the three plea bargain agreements to go into effect.

No one I spoke to during my last trip was willing to predict what a second Trump term might bode for Guantánamo – except that it won’t be closed.The Conversation

Lisa Hajjar, Professor of Sociology, University of California, Santa Barbara

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

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