Supporting the roads that support us

Texas A&M civil engineers investigated the reasons for embankment slope failure of an important Houston highway.

Texas A&M University

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Roads and highways are the lifeline of a country. The United States has over 4 million miles of public roads, including the Interstate Highway System. It’s critical to prevent damage and maintain roads and highways to support the longevity of the sprawling transportation infrastructure within the United States. 

Toward that effort, Texas A&M researchers recently published a report in the journal Transportation Geotechnics on a forensic investigation of a collapsed slope of a Texas highway embankment using a variety of methods, including numeric modeling and laboratory tests.

“Failures of embankment slopes are quite common every year,” said Dr. Anand Puppala, professor in the Zachry Department of Civil and Environmental Engineering. “Repairing these failures involves a tremendous amount of work, especially if the highways are in the middle of a city, for example. In our study, we investigated the reasons for failure of embankment slopes and the best way to repair such damages.”

According to the Federal Highway Administration, embankments are structures that are made of compacted earthen materials, like soil, rock or aggregate. They raise roadways above the level of the existing surrounding ground surface to provide structural support, prevent flooding and improve drainage from roads by directing water through defined paths. 

But even embankments can fail over time due to heavy rainfall, snowmelt, seismic activity and construction defects. These failures can lead to loss of life and property damage. Highway embankments made of heavy materials are often built over soft ground and this can sometimes lead to settlement and instability of the embankment.

“Most of the embankments in Texas, for example, are built with the local clayey soils,” said Puppala. “Embankment slopes made with compacted clayey soils are highly problematic. After 10 to 15 years of continuous use along with the natural impact of weather, embankments tend to fail.”

For their study, the researchers selected a collapsed highway embankment slope in Houston. They performed in-situ site investigation, collected the soil specimens using a coring barrel and transported the specimens to the laboratory for testing and analysis. Here, the team performed a variety of tests, including basic soil characterization and laboratory experiments, to determine the shear strength of the soil. 

Next, they used the results from these tests, such as the soil strength, as parameters for a numerical model that can analyze the stability of the embankment slope. In addition, they also used the model to explore scenarios of extreme rainfall on the embankment slope.

“The model was telling us that a 24-hour rainfall or an extreme flooding event, for example, can lead to the development of a water table on the top surface, which generally results in the failure of the slope,” said Ayush Kumar, a graduate student in Puppala’s laboratory and lead author on the study. “Texas soils tend to be quite plastic that increase and decrease in volume based on wetting and drying cycles, making them more susceptible to moisture change.”

Based on their findings, the researchers noted there are practical solutions that could have prevented collapse of the embankment slope investigated in this study. Their recommendations include using stabilizing agents, like cement, to reduce the impact of moisture and the placement of perforated pipes to drain the water quickly. 

Although the study is a forensic analysis on the reasons underlying the failure of a specific embankment slope, the researchers noted that a similar comprehensive analysis can be carried out for different slopes and weather scenarios. 

Thus, this research has the potential to be useful for transportation workers tasked with maintaining roads and highways across the country.

“This study is a result of good teamwork,” said Puppala. “We’ve been fortunate to get a lot of help from TxDOT Houston district personnel to get the right samples and then point us to places where the embankment failures have happened. We hope that our study in turn provides a rehabilitation strategy that can be used by different transportation agencies to prevent failure in the future.”

Contributors to the research include Nripojyoti Biswas from the University of Massachusetts and Benamar Mebarkia from the Texas Materials and Tests Division at the Texas Department of Transportation.

This research was supported by the Houston District of the Texas Department of Transportation.

Texas A&M University College of Engineering 

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Journal

Transportation Geotechnics

DOI

10.1016/j.trgeo.2025.101503 

Method of Research

Case study

Subject of Research

Not applicable

Article Title

Forensic investigation and chemical remediation of a collapsed highway embankment slope in Houston, Texas

 

First ancient genomes from the Green Sahara deciphered

A new study reveals a long-isolated North African human lineage in the Central Sahara during the African humid period more than 7,000 years ago

Max Planck Institute for Evolutionary Anthropology

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View from the Takarkori rock shelter in Southern Libya.

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Credit: © Archaeological Mission in the Sahara, Sapienza University of Rome

The study provides critical new insights into the African Humid Period, a time between 14,500 and 5,000 years ago when the Sahara desert was a green savanna, rich in water bodies that facilitated human habitation and the spread of pastoralism. Later aridification turned this region into the world's largest desert. Due to the extreme aridity of the region today, DNA preservation is poor, making this pioneering ancient DNA study all the more significant.

Genomic analyses reveal that the ancestry of the Takarkori rock shelter individuals primarily derives from a North African lineage that diverged from sub-Saharan African populations at about the same time as the modern human lineages that spread outside of Africa around 50,000 years ago. The newly described lineage remained isolated, revealing deep genetic continuity in North Africa during the late Ice Age. While this lineage no longer exists in unadmixed form, this ancestry is still a central genetic component of present-day North African people, highlighting their unique heritage.

North Africa remained genetically isolated

Furthermore, these individuals share close genetic ties with 15,000-year-old foragers that lived during the Ice Age in Taforalt Cave, Morocco, associated with the Iberomaurusian lithic industry that predates the African Humid Period. Notably, both groups are equally distant from sub-Saharan African lineages, indicating that despite the Sahara's greening, gene flow between sub-Saharan and North African populations remained limited during the African Humid Period, contrary to previous suggestions.

The study also sheds light on Neandertal ancestry, showing that the Takarkori individuals have ten-fold less Neandertal DNA than people outside Africa, but more than contemporary sub-Saharan Africans. “Our findings suggest that while early North African populations were largely isolated, they received traces of Neandertal DNA due to gene flow from outside Africa,” said senior author Johannes Krause, director at the Max Planck Institute for Evolutionary Anthropology.

The spread of pastoralism in the Green Sahara

"Our research challenges previous assumptions about North African population history and highlights the existence of a deeply rooted and long-isolated genetic lineage," said first author Nada Salem from the Max Planck Institute for Evolutionary Anthropology. "This discovery reveals how pastoralism spread across the Green Sahara, likely through cultural exchange rather than large-scale migration."

"The study highlights the importance of ancient DNA for reconstructing human history in regions like Central Northern Africa, providing independent support to archaeological hypotheses," said senior author David Caramelli from the University of Florence. "By shedding light on the Sahara's deep past, we aim to increase our knowledge of human migrations, adaptations, and cultural evolution in this key region," added senior author Savino di Lernia from Sapienza University in Rome.

View of the Takarkori rock shelter in Southern Libya.

7,000-year-old natural mummy found at the Takarkori rock shelter (Individual H1) in Southern Libya.

Credit

© Archaeological Mission in the Sahara, Sapienza University of Rome

Journal

Nature

DOI

10.1038/s41586-025-08793-7 

Article Title

Ancient DNA from the Green Sahara reveals ancestral North African lineage

Article Publication Date

2-Apr-2025

 

Increased utilization of overtime and agency nurses and patient safety

JAMA Network Open

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About The Study:

 The findings of this study suggest that both nurse overtime and nurse agency hours are associated with increased rates of pressure ulcers, a measure that is one of the most sensitive to nursing care. In future research, hospitals could use their own data to track safe thresholds.

Corresponding Author: To contact the corresponding author, Patricia Pittman, PhD, email ppittman@gwu.edu.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2025.2875)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

#  #  #

Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time https://jamanetwork.com/journals/jamanetworkopen/fullarticle/10.1001/jamanetworkopen.2025.2875?guestAccessKey=c0957767-f5eb-4d6d-88a4-15c747418b57&utm_source=for_the_media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=040225

About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication. 

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Journal

JAMA Network Open

 

Early-life ozone exposure and asthma and wheeze in children

JAMA Network Open

About The Study:

 In this cohort study with relatively low ambient ozone exposure, early-life ozone was associated with asthma and wheeze outcomes at age 4 to 6 and in mixture with other air pollutants but not at age 8 to 9. Regulating and reducing exposure to ambient ozone may help reduce the significant public health burden of asthma among U.S. children.

Corresponding Author: To contact the corresponding author, Logan C. Dearborn, MPH, email dearbl@uw.edu.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2025.4121)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

#  #  #

Embed this link to provide your readers free access to the full-text article This link will be live at the embargo time https://jamanetwork.com/journals/jamanetworkopen/fullarticle/10.1001/jamanetworkopen.2025.4121?guestAccessKey=c0957767-f5eb-4d6d-88a4-15c747418b57&utm_source=for_the_media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=040225

About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication. 

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Journal

JAMA Network Open

 

Early Earth's first crust composition discovery rewrites geological timeline

Modern continental rocks carry chemical signatures from the very start of our planet’s history, challenging current theories about plate tectonics.

Macquarie University

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Continental clues: Modern continental rocks carry chemical signatures from the very start of our planet’s history, challenging current theories about plate tectonics.

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Credit: Morris McLennan, Macquarie University

Researchers have made a new discovery that changes our understanding of Earth’s early geological history, challenging beliefs about how our continents formed and when plate tectonics began.

A study published in Nature on 2 April reveals that Earth's first crust, formed about 4.5 billion years ago, probably had chemical features remarkably like today’s continental crust.

This suggests the distinctive chemical signature of our continents was established at the very beginning of Earth’s history.

Professor Emeritus Simon Turner from the Faculty of Science and Engineering at Macquarie University led the study, which included researchers from elsewhere in Australia, the UK and France.

“This discovery has major implications for how we think about Earth’s earliest history,” says Professor Turner.

"Scientists have long thought that tectonic plates needed to dive beneath each other to create the chemical fingerprint we see in continents.

“Our research shows this fingerprint existed in Earth’s very first crust, the protocrust – meaning those theories need to be reconsidered,” says Professor Turner.

Rethinking early Earth formation

For decades, scientists have tried to identify when plate tectonics first began, marking the earliest evolution of life.
The chemical signature of rocks formed in subduction zones (where one plate has slipped beneath another) is distinctive in its low quantity of the element Niobium.

Scientists thought finding the age of the earliest low-Niobium rocks was the key to identifying when plate tectonics first began; but while a series of research teams tried to track this down, the results from each study were remarkably inconsistent.

“I began to wonder if we were asking the right question,” says Professor Turner.

Together with collaborators across six universities, he created mathematical models simulating early Earth conditions when our planet’s core was forming and an ocean of molten rock covered the planet’s surface.

The team’s calculations showed the protocrust – Earth’s earliest crust formed during the Hadean eon (4.5-4.0 billion years ago) – would naturally develop the same chemical signatures found in today’s continents, without needing plate tectonics to create them.

Chemical clues to formation

The initial results from the model showed that under the reducing conditions of early Earth, the element niobium would become siderophilic, or attracted to metal, sinking through the global magma ocean into the Earth’s core.

“I realised there might be a connection between early core formation, high siderophile element patterns, and the infamous negative niobium anomaly observed in continental crust,” says Professor Turner.

The distinctive signature of the continental crust matched the probable signature of material extracted from the mantle after core formation but before meteorites bombarded early Earth – solving the mystery of why the chemical signature appears in nearly all continental rocks regardless of age.

Early Earth’s evolution

“Our research shows that the chemical signatures we see in continental crust were created in Earth’s earliest period - regardless of how the planet’s surface was behaving,” says Professor Turner.

“This early crust was reshaped and made richer in silica thanks to a combination of meteor impacts, chunks of crust peeling off, and the beginning of plate movements.”

The first crust likely broke into pieces that became thicker in some areas, forming the beginnings of continents.

As these pieces moved sideways, the molten magma between them created crust similar to what we find in ocean floors today.

Meteor impacts and plate tectonics

The heavy meteor bombardment during this early period caused extensive disruption and recycling of the crust.

Plate tectonics may have worked in fits and starts, triggered by meteor impacts until about 3.8 billion years ago, when meteor bombardment decreased dramatically as the early Solar System’s chaos gave way to more orderly orbits.

Plate tectonics then fell into a continuous, self-sustaining pattern.

“This discovery completely changes our understanding of Earth's earliest geological processes,” says Professor Turner.

“It also gives us a new way to think about how continents might form on other rocky planets across the universe.”

END

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Journal

Nature

DOI

10.1038/s41586-025-08719-3 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Formation and composition of Earth’s Hadean protocrust

Article Publication Date

2-Apr-2025

 

Dark diversity reveals global impoverishment of natural vegetation

Estonian Research Council

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Study revealed that in regions with little human impact (i.e Mongolia and Eastern Australia right on the picture) ecosystems typically contain over a third of potentially suitable species. In contrast regions heavily impacted by human activities (i.e grassland in Hungary and Italy left on the picture), the sites studied contained only one out of five suitable species. Source:DarkDivNet

 

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Credit: DarkDivNet

A study recently published in Nature indicates that human activities have a negative effect on the biodiversity of wildlife hundreds of kilometres away. A research collaboration led by the University of Tartu assessed the health of ecosystems worldwide, considering both the number of plant species found and the dark diversity – the missing ecologically suitable species.

For the study, over 200 researchers studied plants at nearly 5,500 sites in 119 regions worldwide, including all continents. At each site, they recorded all plant species on 100 m2 and identified the dark diversity – native species that could live there but were absent. About 300 km2 surrounding each site was considered the region affecting the site. This allowed researchers to understand the full potential of plant diversity at each site and measure how much of the potential diversity was actually present.

High human impact wipes out four of five species

The study revealed that in regions with little human impact, such as in the vast forest masses of North America or in Greenland’s tundra, ecosystems typically contain over a third of potentially suitable species, with other species remaining absent mainly due to natural reasons, such as habitats being too far apart or the lack of seed dispersers. By contrast, in forests of western and southern Europe and other regions heavily impacted by human activities, the sites studied contained only one out of five suitable species. Traditional biodiversity measurements, like simply counting the number of recorded species, did not detect this impact because natural variation in biodiversity across regions and ecosystems hid the true extent of human impact.

The level of human disturbance in each region was measured using the human footprint index. The index includes factors like human population density, land-use changes (i.e. urban development and conversion of natural to arable land), and infrastructure (roads and railways). The study found that plant diversity at a site is negatively influenced by human impact up to hundreds of kilometres away.

According to the lead author of the study, Professor of Botany of the University of Tartu Meelis Pärtel, the findings indicate that biodiversity can also be reduced in ecosystems that have not been directly modified by humans but are located in areas where human activities have caused habitat fragmentation or have had a dispersed impact on natural areas, for example through pollution.

“This result is alarming because it shows that human disturbances have a much wider impact than previously thought, even reaching nature reserves. Pollution, logging, littering, trampling and human-caused fires can trigger local extinctions and prevent recolonisation,” explained Pärtel.

Evidence-based nature conservation targets

Researchers found that the negative influence of human activity was less pronounced when at least 30% of the surrounding region remained relatively pristine. According to Pärtel, this supports the global nature conservation targets to protect about one third of the land.

The study highlights the importance of maintaining and improving ecosystem health beyond nature reserves. The concept of dark diversity provides a practical tool for conservationists to identify absent suitable species and track progress in restoring ecosystems.

The study was conducted thanks to the international research network DarkDivNet, which started in 2018. The network is led by the University of Tartu, and its partners include researchers from nearly two hundred research institutions in 37 countries.

 

Plant diversity in natural vegetation in relation to human effects in the surrounding regions. Source: DarkDivNet

Credit

DarkDivNet

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Journal

Nature

DOI

10.1038/s41586-025-08814-5 

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Global impoverishment of natural vegetation revealed by dark diversity

Article Publication Date

2-Apr-2025

COI Statement