The research team found that, even in regions that keep receiving about the same amount of precipitation, streamflow will become more variable and unpredictable. As snowpack recedes in a warmer future and fails to provide reliable runoff, the amount and timing of water resources will become increasingly reliant on periodic episodes of rain.

“Water managers will be at the whim of individual precipitation events instead of having four-to-six months lead time to anticipate snowmelt and runoff,” said NCAR scientist Will Wieder, the lead author. “Water management systems in snow-dominated regions are based on the predictability of snowpack and runoff, and much of that predictability could go away with climate change.”

Observations show that snowpack is already melting earlier, and even declining in many regions. This decline will become so pronounced toward the end of the century that the amount of water contained in snowpack at the end of an average winter in parts of the U.S. Rocky Mountains could plummet by nearly 80 percent, the scientists found.

The changes in runoff and streamflow are likely to have cascading impacts on ecosystems that depend on reliable water from snow, the study warns. Although the changes won’t be uniform across regions, more snow-free days and longer growing seasons will put stress on water resources, drying out soils in many areas and heightening fire risk.

The study assumes that emissions of greenhouse gasses continue at a high rate (a scenario known as SSP3-7.0). Wieder said that the most severe impacts on snowpack, runoff, and ecosystems would likely be avoided if society successfully reduced greenhouse gas emissions.

The scientists drew on an advanced set of computer simulations to fill in details about the future of water resources, showing the extent to which changes in temperature and precipitation will alter snow accumulation and runoff patterns in the Northern Hemisphere. Although past research looked at the impacts of climate change on water availability, the new study focuses on the increasing variability of water resources.

The study is being published the week of July 18 in the Proceedings of the National Academy of Sciences. It was funded by the U.S. National Science Foundation, which is NCAR’s sponsor.

A race with predictability

Many regions of Earth rely on the accumulation of snow during the winter and subsequent melting in the spring and summer for regulating runoff and streamflow. For years, however, scientists have warned that the snowpack will become thinner and melt earlier as more precipitation during the colder months falls as rain instead of snow, and as melting occurs at times during the winter instead of the spring runoff season.

To determine how reduced snowpack will affect the variability of water resources, Wieder and his co-authors turned to a powerful NCAR-based climate model: the Community Earth System Model, version 2. They drew on a recently created database of simulations, known as the CESM2 Large Ensemble, to compare a past period (1940-1969) with a future period (2070-2099). The simulations were run on the Aleph supercomputer at the Institute for Basic Science supercomputer in Busan, South Korea.

The results illuminate the extent to which widespread shifts in the timing and extent of water flows will occur in much of the world by 2100. There will be an average of about 45 more snow-free days yearly in the Northern Hemisphere, assuming high greenhouse gas emissions. The largest increases will occur in midlatitudes that are relatively warm and high-latitude maritime regions that are influenced by changes in sea ice.

Many regions that rely the most on predictable relationships between snowpack and runoff will experience the largest loss in predictability because of a sharp decline in reliable pulses of spring runoff. These regions include the Rocky Mountains, Canadian Arctic, Eastern North America, and Eastern Europe. The authors warn that this will substantially complicate the management of freshwater resources, both for society and ecosystems.

“We are in a race with predictability when it comes to streamflow because we’re trying to improve our forecasts through better data, models, and physical understanding, but these efforts are being canceled by the rapid disappearance of our best predictor: snow,” said Flavio Lehner, a professor of earth and atmospheric science at Cornell University and a co-author of the study. “It might be a race we’ll lose, but we’re trying to win it, and that is why we need to study these topics.”

Although the reduced runoff will result in drier summertime soil conditions in much of the Northern Hemisphere, the simulations showed that certain regions — including East Asia, the Himalayas, and Northwestern North America — will maintain soil moisture because of increased rainfall.

“Snow-related metrics are critical for informing society’s management of precious water resources,” said Keith Musselman, a hydrologist at the University of Colorado Boulder and co-author of the study. “As utilities and civil works agencies plan new reservoirs and other infrastructure to adapt to a changing climate, we must address basic research questions about the changing characteristics of winter snowpack and resulting streamflow that we have long relied upon.”

The research, in collaboration with Zoo Atlanta, finds that an elephant’s skin doesn’t uniformly stretch. The top of the trunk is more flexible than the bottom, and the two sections begin to diverge when an elephant reaches more than 10%. When stretching for food or objects, the dorsal section of the trunk slides further forward.

The findings could improve robotics, which today are typically built for either great strength or flexibility. Unlike an elephant’s trunk, the machines can’t do both.

As an example, the study’s authors point to soft robotics. Their fluid-filled cavities allow flexible movements but can easily break when forces are applied. The researchers say the elephant findings suggest that wrapping soft robotics with a skin-like structure could give the machines protection and strength while continuing to allow flexibility.

The paper is published in the Proceedings of the National Academy of Sciences (PNAS) by the same Georgia Tech team that authored a study last summer about how elephants use their trunk muscles to inhale food and water.

“When people extend their tongue — a muscle-filled, boneless tissue similar in composition to an elephant’s trunk — it stretches uniformly. We expected the same when we challenged an elephant to reach for food,” said Andrew Schulz, the study’s lead author and a Ph.D. student in Georgia Tech’s George W. Woodruff School of Mechanical Engineering. He and the team filmed two African savanna elephants reaching for bran cubes and apples at Zoo Atlanta.

“But when we looked at our high-speed camera footage and plotted the trunk’s movements, we were surprised. The top and bottom weren’t the same at all,” Schulz said.

After seeing the video, Schulz stretched the tissue of a dissected elephant to better understand the skin’s elasticity. That’s when he found that the top of the skin, which is folded, is 15% more flexible than the wrinkled bottom side. It’s also when the team realized they weren’t just seeing muscle movement on the video. They were also tracking a thick sheet of skin.

“Flexible skin folds are the elephant’s innovation,” said David Hu, Schulz’s advisor and a professor in the Woodruff School and the School of Biological Sciences. “They protect the dorsal section and make it easier for the elephant to reach downward, the most common gripping style when picking up items.”

The Georgia Tech study also found that an elephant trunk differs in another way from other boneless, muscle-filled appendages found in nature, such as squid and octopus tentacles. Instead of extending evenly, an elephant telescopically stretches its trunk like an umbrella, gradually lengthening in waves.

An elephant first extends the section that includes the tip of its trunk, then the adjacent section and so on, gradually working its way back toward its body. Schulz says the progressive movement towards the base is intentional.

“Elephants are like people: they’re lazy,” he said. “The section at the end of the trunk is 1 liter of muscle. The section closest to its mouth is 11-15 liters of muscle. An elephant will first stretch the end of its trunk, then the adjacent section, because they’re easier to move. If an elephant doesn’t have to work very hard to reach something, it won’t.”

Schulz said he had to rely on a drawing from 1908 when learning about trunk anatomy because scientists and engineers haven’t done much research on the biomechanics of elephants during the last century. Part of his curiosity of elephants is based on helping them; he thinks a better understanding of the animals will lead to better conservation efforts. As a mechanical engineer, Schulz also sees the applications of robotics.

“Soft robotics created with biologically inspired design are always based on muscle movement. If they were wrapped with a protective skin, like an elephant’s muscle-filled trunk, the machines could apply larger forces,” he said. “Last year we learned that a trunk is a multi-purpose, muscular hydrostat. Now we know that skin is another tool at its disposal.”

“Being able to read and respond to someone’s body language is important in our daily interactions with others,” said Emily Knight, M.D., Ph.D., clinical and postdoctoral fellow in Pediatrics and Neuroscience, is the first author of the study recently published in Molecular Autism. “Our findings suggest that when children with autism are distracted by something else, their brains process the movements of another person differently than their peers.”

Key differences in brain processes

Using electroencephalogram (EEG), researchers recorded the brain waves of children with and without autism as they watched videos of moving dots that were arranged to look like a person. In these videos the dots moved to represent actions such as running, kicking, or jumping, and at times were turned in different directions or jumbled to no longer move like a person. The six- to 16-year-olds were asked to either focus on the color of the dots or to focus on whether the dots moved like a person. Researchers found the brainwaves of children with autism did not process when the dots moved like a person if they were focused on the dot color.

“If their brain is processing body movements less they might have a harder time understanding other people, and need to pay extra attention to body language in order to see it,” said Knight. “Knowing this can help guide new ways to support people with autism.”

“This is more evidence of how the brain of someone with autism is processing the world around them,” said John Foxe, Ph.D., lead author of the study. “This research is a vital step in creating a more inclusive space for people with autism by giving a glimpse of how their brain processes an unspoken part of communication.”

Additional authors include Ed Freedman, Ph.D., from the University of Rochester Medical Center, John Butler, Ph.D., Aaron Krakowski, and Sophie Molholm, Ph.D., of Einstein College of Medicine. This research was supported by the National Institute of Mental Health and the University of Rochester Intellectual and Developmental Disability Research Center (UR-IDDRC) and the Rose F. Kennedy Intellectual and Developmental Disabilities Research Center (RFK-IDDRC).

Story Source:

Materials provided by University of Rochester Medical Center. Original written by Kelsie Smith Hayduk. Note: Content may be edited for style and length.

The vascular system within our body provides a constant flow of nutrients, hormones and other resources, thus ensuring efficient transport. The researchers Komal Bhattacharyya, David Zwicker, and Karen Alim investigated in which way such a network is able to adapt and change over time. Using computer simulations, they modelled the network and identified adaptation rules for its connections.

“We found that the strength of a connection within a network depends on the local flow,” explains Karen Alim, corresponding author of the study. “This means that links with a low flow below a certain threshold will decay more and more until they eventually vanish,” she continues. As the amount of biological material to build the vascular system is limited and should be used in an efficient way, this mechanism offers an elegant way to streamline the vascular system.

Changes in the network are persistent

Once a connection has become very weak due to a low flow rate, it is very difficult to recover that connection. A common example for this is the blockage of a blood vessel which in a bad case even might lead to a stroke. During a stroke some blood vessels in a certain brain region become very weak due of the blockage of blood flow. “We found that in such a case, adaptations in the network are permanent and are maintained after the obstacle is removed. One can say that the network prefers to reroute the flow through existing stronger connections instead of re-growing weaker connections — even if the flow would require the opposite,” explains Komal Bhattacharyya, principal author of the study.

With this new understanding of network memory, the researchers can now explain that blood flow permanently changes even after successful removal of the clot. This memory capability of networks can also be found in other living systems: the slime mold Physarum polycephalum uses its adaptive network to navigate its environment based on imprints by food stimuli, as demonstrated previously.

Story Source:

Materials provided by Max Planck Institute for Dynamics and Self-Organization. Note: Content may be edited for style and length.

Columbia researchers have now completed one of the most comprehensive studies of the cells inside melanoma brain metastases, uncovering details that could spur the development of a new generation of therapies.

“Brain metastases are extremely common in patients with melanoma, but we have only had a rudimentary understanding of the underlying biology,” says study leader Benjamin Izar, MD, PhD, assistant professor of medicine at Columbia University Vagelos College of Physicians and Surgeons. “Our study gives us new insights into the genomics, immunology, and spatial organization of these tumors and serves as a foundation for further discovery and therapeutic exploration.”

The findings were published online in Cell.

Innovative methods allow for deeper analysis

To begin understanding why melanoma brain metastases evade current treatments, Izar and his team needed to invent new techniques for performing single-cell genetic analyses of frozen brain samples.

“Such studies are typically performed on fresh brain samples, which are in short supply, drastically limiting the number of tumors that can be analyzed. In contrast, we have many frozen melanoma samples in our tissue bank,” Izar says.

“This innovation also allowed us to analyze tissues from patients who had not been treated, letting us see the biology of the tumor and its microenvironment before they’re altered by therapy.”

Therapeutic targets revealed

With metastatic tumors from several dozen melanoma patients, Izar and his colleagues analyzed the genes expressed in more than 100,000 individual cells.

The analysis revealed that melanoma brain metastases are more chromosomally unstable than melanoma metastases in other parts of the body.

“Chromosomal instability is the perpetual gain and loss of large chromosomal fragments; this process triggers signaling pathways that make cells more likely to spread and better able to suppress the body’s immune response,” says Johannes C. Melms, MD, a molecular postdoctoral fellow in the Izar lab and one of the study’s first authors.

These pathways could be important therapeutic targets. “Several experimental drugs that reduce chromosomal instability are going to be tested in humans soon,” Melms says. “We now have a rationale to evaluate these drugs in patients with melanoma metastases in the brain.”

Hiding from immune system

The researchers also uncovered two other characteristics of melanoma brain metastases that may help to hide the cells from the patient’s immune system. The researchers found that the metastases alter immune cells, specifically macrophages and T cells, in the tumor microenvironment in a way that promotes cancer growth. And they found that the cells adopt a neuronal-like state inside the brain.

“It’s possible that these changes help tumor cells adapt and survive in their new environment while avoiding ensuing immune responses,” says Jana Biermann, PhD, a computational postdoctoral fellow in the Izar lab and one of the study’s first authors.

First spatial analysis

Finally, the researchers were able to perform the first spatial analysis of melanoma brain metastases, by analyzing and piecing together analyses of multiple slices of the tumors much the way a CT scanner creates three-dimensional images.

“It turns out there’s quite a bit of geographic variability from one tumor to the next and even within a given tumor, in terms of metabolic and immune pathways,” says Izar.

“We are just beginning to understand how to think of spatial variability, but it’s clear that this will be key to increasing chances for complete tumor responses to novel therapies.”