Earth

University of Delaware data scientist Jing Gao is fascinated by the ways that cities and towns grow over time. This concept is known as urbanization.

Take Chicago, Los Angeles and New York. All of these are cities, but they each grow differently, in terms of how the city's land areas expand. The same is true globally, from New Delhi, India, to Paris, France.

Gao, an assistant professor of geography and spatial sciences in UD's College of Earth, Ocean and Environment, and collaborator Brian O'Neill, a UD alumnus and professor from the University of Denver, have created a new global simulation model to predict how urban land will change over the next 100 years under different social and economic conditions.

The research leverages data science and machine learning to provide a first long-term look at how urbanization will unfold -- decade by decade.

The researchers describe their simulations in a paper published in the journal Nature Communications on Friday, May 8.

Data science helps long-term forecasting

According to Gao, until recently it has been difficult to generate long-term, global forecasts of urban expansion. This is because while urbanization is a global trend, the way cities develop (buildings, roads, people, economics) can change over time. Additionally, this development can vary widely country to country, and even within different parts of the same country.

To understand how this change occurs, Gao and O'Neill used data science to analyze 15 global data sets depicting various aspects of urbanization, including a newly available global map series showing urban land change over the past 40 years based on satellite images of Earth. The global maps are accurate to within approximately 125 feet (38 meters) and provide a uniquely detailed look at past urban development that was not previously possible with this degree of specificity.

"Mining historical data revealed that there are three different urbanization styles: urbanized, steadily urbanizing and rapidly urbanizing," Gao said. "And countries evolve from rapidly urbanizing to steadily urbanizing to urbanized over time."

It should come as no surprise that the United States and most western European countries are already urbanized. India and China, which previously experienced rapid development, have now transitioned to steadily urbanizing. Rapidly urbanizing countries at present include many countries in Africa.

And here's the data science part. Understanding these broad styles is not enough to capture -- globally -- how urbanization is playing out on the ground at a local scale.

To do this, the researchers divided the world into 375 small regions and ran a unique model for each region simultaneously, then pieced results from all models together to develop a global map. This information can shed light on how our cities may change and reveal potential impacts of urbanization that can inform local to global urban planners and policymakers.

The research team's projections show that the total amount of urban areas on Earth can grow anywhere from 1.8 to 5.9-fold by 2100. On average, if past urbanization trends continue, the world will build approximately 618,000 square miles (1.6 million square kilometers) of new urban areas globally over the century. This is an area roughly 4.5 times the size of Germany, or, more than 225 million football fields.

How this urban expansion occurs, however, largely depends on societal trends in the years to come. This includes trends in economic growth, population change and lifestyle habits, and what level of consideration is given to how our habits affect the environment.

For both developed and developing countries, for example, countries in Europe and Southeast Asia, urban expansion is expected to roughly triple if society favors materialistic and fossil-fuel driven development instead of adopting a sustainability mindset.

In the U.S., the least urban expansion occurs if people are focused on sustainability, such as green development and environmental awareness. In this case, urban land is expected to grow by 1.3 times by 2100. But if people favor highly materialistic development over the same timeframe, with high consumption of fossil fuels and a material-driven society, sprawl-like urban expansion is expected, with close to four times the amount of expansion the U.S. had at the beginning of the century.

The U.S. already is among the countries with the largest amount of developed land, so four-fold growth in urban expansion is a lot.

"This is where our projections can inform policy and planning," said Gao. "These projections can help researchers and analysts understand how large-scale changes that occur over a long time period, such as climate change, may affect local urban areas."

Most individuals do not realize how changes to the landscape, such as buildings and roads, may affect their lives. In Delaware, for example, second homes being built near the coast often come at the cost of agricultural farmland. While these developments may increase an area's economic prosperity, they can have other unintended consequences, such as increased potential exposure to coastal flooding and sea level rise.

And, no matter what socio-economic scenario was selected, the simulations show that most countries will become urbanized by the end of the century.

One interesting finding from the work is that although prevailing thought is that urbanization is primarily happening in the developing world, Gao said this may not be the case.

"If you look at the data collected over the past 40 years, the absolute amount of new urban land construction in the developed world is comparable to the developing world," she said. "However, the changes seem faster in the developing world because there currently is much less developed land there, so the rate of change appears greater."

This begs the question: as developing countries in Africa continue to grow, will they ever catch up to or surpass developed countries like the United States in terms of urbanized land?

"According to today's definition, Africa is expected to become urbanized by 2100," said Gao. "But even if it continues developing at a very fast rate relative to the rest of the world throughout the century, it won't catch up to developed countries like the U.S. because the difference at the outset is large and the developed world still keeps expanding its urban area."

Tsukuba, Japan - The advances in optical devices that we expect as consumers must be supported by the development of new materials. Microcrystallites of luminescent organic compounds can act as tiny laser sources for such devices, for example for use in displays and other components. Dendrimers offer numerous advantages as luminescent materials, however so far they have not been used as microcrystallites owing to their fragility and poor crystallinity. Now a team of researchers has produced dendrimers that form robust crystals with lasing properties. Their findings are published in Angewandte Chemie.

Dendrimers are polymers that grow out from a core through the addition of small molecules to form extended branches--which explains their name, derived from the Greek word for tree. Dendrimers have many advantages that make them interesting luminescent materials. They are highly soluble, which makes them easy to incorporate into systems; they have high quantum yields, meaning you get a lot of the light you put in back again; they are good at harvesting light; and they tend to show relatively low luminescence loss when condensed into a solid.

The researchers made a family of dendrimers--getting larger in size as the generation number increased--made up of carbazole units forming the branches around a highly fluorescent core. The dendrimers formed stable single crystals even when the solvent was removed, and could be analyzed by single crystal X-ray analysis. In fact, the third generation dendrimer, which has a molecular weight of 4,600 Da, is the largest organic dendrimer ever to have been analyzed in this way.

"Our dendrimers have two key parts," study corresponding author Professor Yohei Yamamoto explains. "The branches are made up of aromatic molecules that act as light harvesting antennas, collecting light made up of waves in many different planes, which is known as non-polarized light. This light is then transferred to the fluorescent core, whose structure leads to polarized light--light with waves in a single plane--being generated."

When the dendrimer crystals were subjected to strong optical pumping--the process used to amplify the signal in laser materials--they produced amplified spontaneous emission and lasing with little damage to the structure of the material or the optical properties.

"The family of dendrimers we produced remedies a number of issues that have prevented the properties of these materials being exploited. We therefore expect them to make a significant contribution to the development of organic materials for laser optics," says Professor Yamamoto. "The robust properties and laser emission of the crystals will be useful for components such as full-color optical displays and micro-optical circuits."

A manually constructed 3D atlas offers a cellular-level view of the entire mouse brain. Presented May 7 in the journal Cell, this reference brain, called the Allen Mouse Brain Common Coordinate Framework (CCFv3, https://portal.brain-map.org/), is derived from serial two-photon tomography images of 1,675 mice.

"We hope the wider neuroscience community will use it as a new standard reference atlas," says co-senior author Lydia Ng (@2queues) of the Allen Institute for Brain Science. "By making our atlas and related tools open access, new data and data types generated across our community can be more easily integrated and compared in the same spatial context, and the atlas in turn can be modified as our knowledge about brain structure evolves."

"Reference atlases are truly multi-purpose tools that are used for teaching neuroanatomy, providing common nomenclature to identify brain regions, supporting analyses to describe where data was collected, and representing our collective current knowledge on the organization of brain structure," says co-senior study author Julie Harris of the Allen Institute for Brain Science.

Historically, the development and refinement of brain atlases have co-evolved with advances in the field of neuroanatomy. Knowledge of mouse brain neuroanatomy has advanced dramatically over the past decade, with the advent of whole-brain mapping projects adding new data types and revealing cellular architecture in rich new detail.

"Modern digital reference atlases must evolve to stay current," Harris says. "Yet classic standard atlases do not meet the demands of these cellular-resolution datasets in 3D. So, we produced a truly 3D atlas to serve as a standard anatomical framework for the whole-brain datasets being produced."

Aligning different types of datasets into CCFv3 allowed the researchers to label more than 800 brain structures. By doing so, the researchers identified several brain structures not previously described in standard mouse brain atlases, and several new nerve fiber tracts not described in other atlases.

"Given that each dataset reveals a unique labeling pattern for certain mouse brain regions, combining all these data types should complement or confirm each other, demonstrating a tremendous methodological advantage for accurately defining brain structures," Ng says.

The authors say that CCFv3 has higher spatial resolution than any currently existing 3D mouse brain reference space based on magnetic resonance imaging. Because CCFv3 is an average from a large population of mice, it can be used to study inter-individual variability in the volumes of 3D brain structures in the context of different disease states. In addition, many anatomical details were apparent in the average brain that were not readily discernable in any single mouse brain.

"We are now using this atlas as the common anatomical reference space for many large-scale projects, including whole-brain circuit mapping, single-cell reconstructions, and the generation of a comprehensive brain cell-type census," Harris says. "All these data, and what we learn about brain architecture in turn, will at some point necessitate an updated, next-generation 3D atlas, although it is likely to be constructed with different, more automated, data-driven methods."

Restoration ecologist Karen Holl has a simple message for anyone who thinks planting 1 trillion trees will reverse the damage of climate change.

"We can't plant our way out of climate change," says Holl, professor of environmental studies at UC Santa Cruz and a leading expert in forest restoration. "It is only one piece of the puzzle."

In a commentary that appears in the May 8 issue of Science, Holl and coauthor Pedro Brancalion, a professor in the Department of Forest Sciences at the University of São Paulo, endorse the benefits of trees but caution against a simplistic view of tree-planting as a panacea for environmental degradation.

"Trees are deeply entrenched in the human psyche," said Holl, a restoration ecologist who has prepared hundreds of students for careers in environmental stewardship. "It's very satisfying to go out and put a tree in the ground. It's a concrete, tangible thing to do."

But broad-scale tree planting initiatives, such as 1t.org and the Trillion Tree Campaign, must be undertaken carefully and with a commitment to long-term management, if the benefits are to be fully realized.

"Planting trees is not a simple solution," said Holl. "It's complicated, and we need to be realistic about what we can and cannot achieve. We need to be thoughtful and plan for the long term."

On the plus side, planting trees can improve biodiversity, water quality, and increase shade. But depending on where and how it is done, tree planting can also harm native ecosystems and species, reduce water supply, and dispossess local landholders and increase social inequity.

In their commentary, Holl and Brancalion present four principles that should guide forest enhancement initiatives:

Reduce forest clearing and degradation: Protecting and maintaining intact forests is more efficient, more ecologically sound, and less costly than planting trees, or replanting.

View tree planting as one part of multifaceted environmental solutions: Enhanced tree cover is one of the best options to offset a portion of the greenhouse gas emissions driven by human activities, but they represent only a small portion of the carbon reductions that are needed--and estimates vary by more than tenfold depending on variables used in modeling.

Balance ecological and social goals: Acknowledge competing land uses and focus on landscapes with the potential to generate large-scale benefits, such as the Atlantic Forest in Brazil, where regional planning of tree planting initiatives can lead to three times the conservation gains at half the cost.

Plan, coordinate, and monitor: Work with local stakeholders to resolve conflicting land-use goals and ensure maximum effectiveness over the long term. Planting trees doesn't ensure they will survive; a review of mangrove forest restoration efforts in Sri Lanka following the 2004 tsunami showed fewer than 10 percent of trees survived in 75 percent of sites.

To be successful, tree-planting initiatives need to engage local stakeholders and confront conflicting goals for land use. "Much of the land proposed for tree planting is already being used to grow crops, harvest timber, and other subsistence activities, so tree planting initiatives need to consider how landowners will earn income," said Holl. "Otherwise, activities such as agriculture or logging will just move to other lands"

Holl chooses her words carefully when she says she applauds the widespread enthusiasm for "increasing forest cover," which is not the same thing as planting more trees.

"The first thing we can do is keep existing forests standing, and the second is to allow trees to regenerate in areas that were formerly forests," said Holl, who specializes in tropical forest restoration. "In many cases, trees will recover on their own--just look at the entire eastern United States that was deforested 200 years ago. Much of that has come back without actively planting trees. Yes, in some highly degraded lands we will need to plant trees, but that should be the last option since it is the most expensive and often is not successful. I've spent my life on this. We need to be thoughtful about how we bring the forest back."

Critically, slowing the pace of climate change requires a comprehensive strategy that starts with burning less fossil fuel, said Holl.

"Trees are a small piece of what needs to be a broader strategy," said Holl. "We're better off not releasing greenhouse gases to begin with."

Combining microfluidics and the natural photosynthetic membranes from spinach plants, researchers have developed "synthetic chloroplasts," which are capable of mimicking complex and life-like photosynthetic processes, a new study reports. "[The authors] demonstrate a major advancement in synthetic biology and a crucial milestone toward the construction of a self-sustaining synthetic cell," write Nathaniel Gaut and Katarzyna Adamala in a related Perspective. Photosynthetic carbon fixation is a fundamental biological process that uses light energy to convert inorganic carbon into the organic compounds required to sustain the vast majority of life on Earth. Thus, the ability to harness the near-limitless supply of light to provide anabolic energy to artificial living cells using photosynthetic-like processes is a highly sought-after goal in the effort to develop fully synthetic organisms. In nature, photosynthesis occurs in specialized organelles called chloroplasts, where enzyme complexes in thylakoid membranes convert light energy into adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH), which are subsequently used to build organic molecules from inorganic carbon dioxide. However, the ability to engineer synthetic carbon fixing mechanisms that mimic complex natural photosynthetic processes in artificial systems remains elusive. Here, Tarryn Miller and colleagues integrate natural and synthetic biological parts to build chloroplast-mimicking microfluidic droplets that possess the essential characteristics of photosynthesis. Their approach uses microfluidics and natural thylakoid membranes from spinach to trigger light-driven complex biosynthetic tasks in synthetic, cell-sized droplets, including carbon fixation. According to the authors, the "synthetic chloroplast" micro-droplets can be programmed to achieve improved or new-to-nature photosynthetic processes with applications that range from small-molecule or drug synthesis to artificial biological systems for sequestering environmental carbon.

What The Study Did: Death certificate data were used to compare the rate of opioid-related deaths in the U.S. among cancer survivors with that of the general population from 2006 through 2016. Whether opioid-associated deaths in cancer survivors, who are often prescribed opioids for cancer-related pain, are rising at the same rate as in the general population is unknown.

Authors: Fumiko Chino, M.D., of the Memorial Sloan Kettering Cancer Center in New York, is the corresponding author.

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

(doi:10.1001/jamaoncol.2020.0799)

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

What Viewpoint Says: This Viewpoint discusses the exclusion of children from coronavirus disease 2019 (COVID-19) clinical trials and why that could harm treatment options for children.

Authors: Florence T. Bourgeois, M.D., M.P.H., of Boston Children's Hospital and Harvard Medical School is Boston, is the corresponding author.

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

(doi:10.1001/jamapediatrics.2020.1888)

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

A research group led by Associate Professor TACHIKAWA Takashi of Kobe University's Molecular Photoscience Research Center has succeeded in developing a strategy that greatly increases the amount of hydrogen produced from sunlight and water using hematite photocatalysts (*1).

Hydrogen has received attention as a possible next generation energy solution, and it can be produced from sunlight and water using photocatalysts. In order to make this practicable, it is necessary to develop foundation technologies to optimize the potential of the photocatalysts, in addition to finding new materials for catalysts.

This time, Tachikawa et al. successfully produced a photoanode with an extremely high conductivity. This was achieved solely by annealing hematite (*2) mesocrystals (*3, superstructures consisting of tiny nanoparticles of approx. 5nm) to a transparent electrode substrate. Hematite can absorb a wide range of visible light and is safe, stable, and inexpensive. With this photoanode, the electrons and holes produced by the light source separated quickly and, at the same time, a large number of holes densely accumulated on the surface of the particles. The accumulation of holes improved the efficiency of the water oxidation reaction; the slow oxidation of the water has previously been a bottleneck in water-splitting.

In addition to boosting the high efficiency of what is thought to be the world's highest performing photoanode, this strategy will also be applied to artificial photosynthesis and solar water-splitting technologies via collaborations between the university and industries.

These results will be published in the German online chemistry journal 'Angewandte Chemie International Edition' on April 30. This work was also featured in the inside cover.

Main points:

Numerous oxygen vacancies (*5) were formed inside the hematite mesocrystals by accumulating and sintering tiny highly-orientated nanoparticles of less than 10 nanometers.

The presence of oxygen vacancies improved the conductivity of the photocatalyst electrode, at the same time giving it a significant surface potential gradient, thereby promoting the separation of electrons and holes.

At the same time a large amount of holes moved to the surface of the particles, allowing a high rate of oxygen evolution from water. This enabled the researchers to achieve the world's highest solar water-splitting performance for hematite anodes.

This strategy can be applied to a wide range of photocatalysts, beginning with solar water-splitting.

Research Background

With the world facing increasing environmental and energy issues, hydrogen has gained attention as one of the possible next generation energy sources. Ideally, photocatalysts could be used to convert water and sunlight into hydrogen. However, a solar energy conversion rate of over 10% is necessary to enable such a system to be adopted industrially. Utilizing Japan's strengths in new materials discovery, it is vital to establish a common foundation technology that can unlock the potential of photocatalysts in order to achieve this aim.

Previously, Tachikawa et al. developed 'mesocrystal technology', which involves precisely aligning nanoparticles in photocatalysts to control the flow of electrons and their holes. Recently, they applied this technology to hematite (a-Fe2O3), and succeeded in dramatically increasing the conversion rate.

This time, they were able to raise the conversion rate up to 42% of its theoretical limit (16%) by synthesizing tiny nanoparticle subunits in the hematite.

Research methodology

Mesocrystal technology:

The main problem that causes a conversion rate decline in photocatalytic reactions is that the electrons and holes produced by light recombine before they can react with the molecules (in this case, water) on the surface. Tachikawa et al. created hematite mesocrystal superstructures with highly oriented nanoparticles via solvothermal synthesis (*7). They were able to develop conductive mesocrystal photoanodes for water splitting by accumulating and sintering mesocrystals onto the transparent electrode substrate (Figure 1).

Photocatalyst formation and performance:

Mesocrystal photoanodes were produced by coating the transparent electrode substrate with hematite mesocrystals containing titanium and then annealing them at 700ºC. A co-catalyst (*8) was deposited on the surface of the mesocrystals. When the photocatalysts were placed in an alkaline solution and illuminated with artificial sunlight, the water-splitting reaction took place at a photocurrent density of 5.5mAcm-2 under an applied voltage of 1.23V (Figure 1). This is the highest performance achieved in the world for hematite, which is one of the most ideal photocatalyst materials due to both its low cost and light absorption properties. In addition, the hematite mesocrystal photoanodes functioned stably during repeated experiments over the course of 100 hours.

The key to achieving a high conversion rate is the size of the nanoparticles that make up the mesocrystal structure. It is possible to greatly increase the amount of oxygen vacancies that form during the sintering process by making the nanoparticles as small as 5 nm and increasing the connecting interfaces between the nanoparticles. This boosted the electron density, and significantly increased the conductivity of the mesocrystals (Figure 2).

The high electron density is connected to the formation of a large band bending (*9) near the mesocrystal surface. This promotes the initial charge separation as well as making it easier for holes to accumulate on the surface. This result was optimized due to the tiny nanoparticle structure of the mesocrystals, and boosted the water oxidation reaction that had been a bottleneck for efficient water-splitting (Figure 3).

Further Research

This study revealed that mesocrystal technology is able to significantly minimize the recombination issue, which is the main cause of low efficiency in photocatalysts, and exponentially accelerate the water splitting reaction.

It is hoped that this strategy can be applied to other metal oxides as well. Next, the researchers will collaborate with industries to optimize the hematite mesocrystal photoanodes and implement an industrial system for producing hydrogen from solar light. At the same time, the strategy developed by this study will be applied to various reactions, including artificial photosynthesis.

Tsukuba, Japan - In a new genetic study of rice, Professor Hiroaki Iwai and his team from the University of Tsukuba have revealed that pectin plays a vital role in plant reproductive development, which could have major implications in the development of new crop varieties.

Pectin is a carbohydrate that acts as a vital building block in the cell walls of land plants. Plant cell walls have multiple important functions, such as providing shape and structure to plant organs, and participating in communication between cells. Previous studies have already shown the importance of pectin in plant development and growth and in the interactions between plants and stressors such as pathogens.

"It is clear that pectin has critical involvement in cell walls and thus plant development, but its importance in reproductive development, especially of female reproductive tissues, was little known," explains Professor Iwai. "We focused on the gene OsPMT16, which has a specific function relating to the adhesiveness of pectin. By removing this gene from some rice plants, we were able to compare the structure of the female reproductive tissues in plants with and without the gene."

The study revealed that cell walls of vegetative tissues in general contained ~5% pectin, whereas the cell walls of the pistil (female reproductive tissue) contained ~43%. The OsPMT16 gene was strongly expressed in the pistil but barely at all in the root, stem, or leaf. Furthermore, there was delayed vegetative growth in the mutant rice without the gene compared with the intact rice, and its fertility had decreased by 12%.

"We found few differences in the specific morphogenesis, that is the biological process that governs the shape of tissues and organs, between the reproductive organs of the two types of rice," says Professor Iwai. "Nonetheless, it was clear that the pistil of the plants without the OsMPT16 gene exhibited some abnormal and disordered tissues. This shows that the modifications of the pectin provided by this gene are required for normal development of the pistil and therefore enhance rice fertility." The team's findings could also be applied to breed improvement that eliminates seeds in fruit by promoting female sterility, and could have other implications in preventing gene diffusion of genetically modified and genome-edited crops.

Recently, Prof. YANG Xueming from the Dalian Institute of Chemical Physics of the Chinese Academy of Sciences and Prof. YANG Tiangang from the Southern University of Science and Technology discussed significant advances in the study of quantum resonances in atomic and molecular collisions at near absolute zero temperature. Their article was published in Science on May 7.

The rules of quantum mechanics govern all atomic and molecular collision processes. Understanding the quantum nature of atomic and molecular collisions is essential for understanding energy transfer and chemical reaction processes, especially in the low collisional energy region, where quantum effect is the most prominent.

A remarkable feature of quantum nature in atomic and molecular collision is quantum scattering resonances, but probing them experimentally has been a great challenge due to the transient nature of these resonances.

This article introduced a quantum resonance study published in the same issue of Science by a research group from University of Nijmegen. By using the Stark decelerated molecular beam of NO(j=1/2f) and a cryogenic helium beam combined with high resolution velocity map imaging technique, De Jongh and coworkers observed resonances in the NO+He inelastic collisions at the temperature range of 0.3 to 12.3 K.

Accurate quantum dynamics calculations are in excellent agreement with experimental results. Particularly interesting is that the resonances can only be accurately described using a new NO-He potential energy surface (PES) at the CCSDT(Q) level, demonstrating the exceptionally high accuracy of the resonance picture developed for this benchmark inelastic collision system.

In addition to inelastic scattering processes, resonances in chemical reactive collisions in the low collision energy regime have been discussed. An important benchmark system for reaction resonances, discussed in the article, is the F+H2 to HF+H reaction, which is a major source of HF formation in interstellar clouds (ISC).

The F+H2 reaction is known to have a significant reaction barrier (629 cm-1), therefore its reactivity should be negligible at the temperature near absolute zero. Understanding the HF formation mechanism through this reaction at the cold temperatures is important, which can help to determine hydrogen column density in space.

With the improved molecular crossed beam apparatus, the F reaction and H2 have been studied as low as 14 K (9.8 cm-1) at the State Key Laboratory of Molecular Reaction Dynamics, DICP. A clear resonance peak at the collision energy of ~40 cm-1 has been discovered, which is found responsible for the enhanced reactivity near absolute zero temperature from the detailed dynamics analysis on an accurate PES. Because of the resonance enhanced quantum tunneling, this reaction should have unusually high reactivity at temperature below 1 K.

Further theoretical analysis indicated that if the contribution of the resonance-enhanced tunneling were removed from the reactivity, the reaction rate constant of F + H2 below 10 K would be reduced more than three orders of magnitude.

In this article, the authors pointed out that strong interaction between experiment and theory has been crucial in the study of transient collision resonances. The dynamics studies in atomic and molecular collisions are especially important to understanding energy transfer and chemical reaction processes that could have a wide impact on complicated systems, such as terrestrial and planetary atmospheres, interstellar clouds, gas-phase lasers, semiconductor processing, plasmas, and combustion processes.

For Dr. Fabian Dembski, who works at the intersection of architecture, city planning, and computational science, cities are more than just the places we live. They function like living organisms, growing and changing over time. From this perspective, decisions made in city planning can either improve or degrade the health of urban spaces.

As cities have gotten larger and more complicated, and technology has opened up new ways of observing and simulating cities' dynamic processes, researchers have tried to find new ways to make city planning decisions more efficient, equitable, and inclusive. Much like CT scans gave medical professionals new ways of observing the human body, advanced digital approaches involving data-driven modelling and visualization now offer researchers new ways of understanding how cities function and predicting how changes in their design could affect life there.

Together with investigators at the Fraunhofer Institute, the University of Stuttgart, and Kommunikationsbüro Ulmer, Dembski and other researchers at the High-Performance Computing Center Stuttgart (HLRS) have been developing new applications of 3D visualization to support urban planning. Specifically, the team has been adapting the concept of the "digital twin" for cities, using high-performance computing (HPC) technologies for analyzing, integrating, and visualizing data describing urban phenomena in order to simulate the complex, dynamic processes that are important to consider in urban planning.

Over the past several years, the team has been developing a digital twin of Herrenberg, a small city just outside of Stuttgart. The Herrenberg study has already provided valuable information for city planners and government officials in the state of Baden-Württemberg, and paves the way for improving the model to include additional kinds of data. The team published a detailed report describing its methods and results in the journal Sustainability.

Approaching digital doppelgängers

Digital twins are essentially hyper-realistic computer models of complex objects that are capable of simulating their function at a high level of detail. In the past, scientists and engineers have used HPC to create digital twins of many kinds of objects, including buildings, engines, and utility networks. Dembski and his colleagues are among the first to apply this concept to the modeling of entire urban environments.

Their approach begins with the idea that life in a city is the result of complex interactions among many factors. With the availability of new sensors and other digital tools for producing high-quality data, researchers can now collect large datasets representing air quality, traffic flow, and the prevalence of pedestrian traffic, among other dimensions of urban life. By merging these large datasets using supercomputers and visualizing them in virtual reality, it becomes easier to understand their complex interactions -- for example, to see how a change in traffic patterns or a new building could affect air quality.

To create such a complex, multidimensional model, the researchers must first develop a basic foundation that can then be expounded upon with more detailed datasets. In building the digital twin of Herrenberg, the team began by using a concept called space syntax. Just as the human skeleton provides a scaffolding for all of the other systems and functions of the human body, space syntax produces a 2D outline of physical grids in a city, offering a framework for performing spatial analysis, such as predicting the likely paths that car or pedestrian traffic might take to move from one point to another.

The team then folds in geographic information system (GIS) data and traffic control systems data in order to incorporate topography, road geometry, and realistic traffic flows in more detail, adding another layer of complexity. Using the open-source fluid dynamics code OpenFOAM--more often used for modeling fuel injector sprays or airplane aerodynamics, for example--they can also create realistic models of the movement of wind and emissions through the city.

In addition to this kind of high-precision physical modeling, the HLRS team also developed an app inviting Herrenberg residents to submit their emotional responses to different areas in the city. Residents provided qualitative data about whether certain locations feel comfortable, unsafe, or ugly, for example. As Dembski explained, "Emotions like joy and fear, the aesthetic experience of green space and architecture, and other emotion-driven factors play a major role in the success of urban design, but are very difficult to represent in architectural models or simulations. Our approach is an early attempt to gather and incorporate these complicated datasets."

Using a Faro 3D laser scanner, the team also created a 3D visualization of the Herrenberg city centre. The team could then integrate visualizations of its various data sets into an immersive virtual reality model, enabling decision makers to see abstract data "come to life." For Dembski and the team, this element moves the work one step closer to visualizing a city in a more realistic way.

High-performance computing resources are necessary for this work because of the large datasets involved. Dembski explained, "In a world in which even singular objects such as buildings are already so complex, simulations with supercomputers can provide great support in the design process--just think of wind flow simulation or building physics simulations. If you then consider entire cities and regions in all their complexity and want to understand parts of them, HPC can provide enormous support."

At the same time, Dembski also noted that the integration of tools, expertise, and the convergence of disparate skill sets and technologies also make HPC centres essential for this work. "It isn't just about supercomputers and infrastructures," he said. "It is about the variety of computational resources we have at our disposal, and perhaps most importantly, the interdisciplinary, collaborative environment that makes this work successful."

Planning ahead

"Cities are not one-dimensional, so it does not make sense to design them on a piece of paper," Dembski said. "The third dimension helps us understand cities and their spatiality. Especially in the context of conventional urban planning and development, the "vista," or the perception of space at the human scale, is often forgotten. Many people cannot imagine abstract planning at the scale of 1:1,000 or 1:10,000. This also applies to planners, as they often lack the necessary sensitivity for the human scale, which is why we know many urban development projects don't work. By allowing decision makers to experience an immersive vista in VR, we are helping them experience it more realistically, ultimately helping them better assess and evaluate designs, plans, or other scenarios."

The team shared its digital twin with Herrenberg city officials and has presented its model at several public events there to encourage public participation in city planning. The response thus far has been very positive.

"When we demonstrated a mobile 3D version of our digital twin using a rear-projection VR environment, it was very well received by the public," Dembski commented. "It was exciting to see groups taking part in a discussion about city planning who would be difficult or impossible to attract in any other format. There is also great interest in the opportunities that digital twins could open up among planners and decision-makers."

Currently, HLRS is working with a small group of partners in the context of the International Building Exhibition Stuttgart (IBA'27), a major upcoming architectural event. The collaboration will focus on opportunities offered by digital technologies for city planning processes.

Artificial intelligence to support city planning

In the near future, the team will also be exploring how artificial intelligence (AI) applications could be used to better represent the myriad factors affecting how residents emotionally experience their home cities.

"We would like to start including larger-scale, more dynamic phenomena in our model," Dembski said. "This could include factors like regional migration, the effects of gentrification, and the growth, shrinkage, settlement patterns, and overall social and economic resilience of cities. Considering the complex data sets needed to quantify such activities we will need even more computational support, and we think that artificial intelligence applications could also help."

Although Dembski is excited about the opportunities that digital twins offer for city planning, he acknowledges that even with the arrival of more powerful computing systems there will always be limitations in using computers to fully understand such a complex, "living" structure as a city. "What brings individual people joy? How do unplanned things enrich a built environment?" he asks. "Digital tools can help us envision a more equitable and complete way to design cities of the future, but the human factor is irreplaceable."

Are today's children, who grew up with mobile technology from birth, worse at reading emotions and picking up cues from people's faces than children who didn't grow up with tablets and smartphones? A new UCLA psychology study suggests today's kids are all right.

Infancy and early childhood are critical developmental phases during which children learn to interpret important non-verbal cues such as facial expressions, tone of voice and gestures. Traditionally, this happens through direct face-to-face communication. But with the ubiquitous use of tablets and other devices today -- among toddlers, as well as their caregivers -- the psychologists wanted to know: Have younger children missed the opportunity to understand these cues?

The study tested the ability of more than 50 sixth graders in 2017, and more than 50 sixth graders in 2012 -- both male and female, from the same Southern California public school -- to correctly identify emotions in photographs and videos. Most children from the sixth-grade class of 2012 were born in 2001, while the first iPhone came out in 2007, for example, and the first iPad in 2010 -- a time when the sixth graders from the 2017 class were infants and toddlers.

The psychologists found that the 2017 sixth graders scored 40% higher than the 2012 class at correctly identifying emotions in photographs and made significantly fewer errors than the 2012 students. In addition, the 2017 students were better at identifying the emotions in a series of videos, but only slightly better, a difference the researchers said is not statistically significant. The psychologists did not look at face-to-face communication.

The study is published in the journal Cyberpsychology, Behavior, and Social Networking.

"At a time when so many people are communicating through screens, I hope our findings give parents some peace of mind that kids seem to be able to learn to read social cues in photos," said lead author Yalda T. Uhls, a UCLA adjunct assistant professor of psychology and founder and executive director of the UCLA-based Center for Scholars and Storytellers.

In today's world, young people use photos and, increasingly, video to communicate. In 2018, for instance, 69% of teens reported they used Snapchat and 72% used Instagram, both of which incorporate pictures and text messages, Uhls said.

A 2017 study with 500 participants found that nearly half of children between the ages of 6 and 12 regularly used a social media app or website, with 29% of those aged 6 to 8 reporting they used Snapchat. Another study, from 2016, found that 50% of children had a social media account before age 12, with 11% getting their account before age 10.

Uhls noted that even text-based communication can convey emotion through capitalization, emoticons and repetition.

"Perhaps our 2017 participants had more opportunities to see, communicate and learn nonverbal emotion expressed in photographs of faces than those from 2012 because of the time spent taking and reviewing photos of themselves and others," she said.

Uhls strongly recommends that families have face-to-face conversations around the dinner table and at other times of the day. She also encourages parents to put their devices away when talking with other people, especially their children.

She noted that while the 2017 participants improved in their ability to read emotional cues in photos, she is not we certain whether this ability transfers to their ability to assess emotions in person; she thinks it may.

"With so many of our kids are on screens so frequently, it is important to know that good things can come from their interactions with photos," Uhls said. "I would expect with the recent increase in video communication, they may be now learning these cues from video chat too."

She said that by evaluating the nuances of screen time, researchers can learn which practices have educational value and which do not.

"Technology is always evolving, and I expect that researchers will seek to understand how increased exposure to pictures, videos, live chats, games, virtual reality and other emerging platforms for communication impact our youth," Uhls said.

Even 18-month-old babies can learn from video chat, she said, citing other research, while another study found that time on screens did not seem to impact kids' social skills.

ITHACA, N.Y. - Already known for their shape-shifting abilities, stem cells can now add "death-defying" to their list of remarkable qualities.

A new study shows how stem cells - which can contribute to creating many parts of the body, not just one organ or body part - are able to postpone their own death in order to respond to an injury that needs their attention. The study was done in planarians, which are tiny worms used as model organisms to study regeneration because of their ability to recover from any injury using stem cells.

"Planarian stem cells, even when challenged and under a lot of duress, will still respond to an injury by delaying death," said Divya Shiroor, first author and a graduate student in Dr. Carolyn Adler's lab, in the College of Veterinary Medicine.

The study, published May 7 in Current Biology, is the first to demonstrate this reaction in planarians.

The research team exposed planarians to radiation, then subjected half of them to injury. Radiated worms that had not been injured experienced predicted levels of stem cell death. Stem cells of the injured worms, however, survived, gathering around the site of the wound and postponing their deaths to mount a response.

"We show that this inevitable radiation-induced cell death can be significantly delayed if animals are injured soon after radiation exposure," said Shiroor.

This could have important implications for cancer research and therapies, particularly when examining chemotherapy and surgery options for patients.

"By understanding how injury prompts planarian stem cells to withstand radiation," Shiroor said, "we hope to identify genes that, if shared with mammals, could perhaps help hone existing therapies."

Planarians are commonly used in basic research because of their similarities to humans. Like humans, planarians have stem cells, similar organs and similar genes, but are much more adept at responding to injury, thanks to their higher volume of stem cells and lack of a developed immune system, which in humans complicates the healing process.

"This really simplifies the process of understanding the effects of both injury and radiation on stem cells, and allows us to study it directly without being hampered by parallel processes integral to wound healing, such as inflammation, that get simultaneously triggered in mammals," Shiroor said.

By uncovering the mechanisms that govern stem cells after wounding in a system like planarians, researchers could also apply this knowledge when engineering stem cells to respond similarly in the human body.

Labs have many ways to understand how planarians use stem cells to successfully recover and regenerate, but the Adler lab's combination of radiation and injury to identify a novel stem cell response is unique. The researchers plan on digging deeper to understand how the stressed stem cells know that there is an injury and what role other cells may play in their response.

"We have identified a key gene that is required for stem cell persistence after radiation and injury," Shiroor said, "and we plan on using this as a stepping stone for further exploration."

UNIVERSITY PARK, Pa. -- If life feels more stressful now than it did a few decades ago, you're not alone. Even before the novel coronavirus started sweeping the globe, a new study found that life may be more stressful now than it was in the 1990s.

A team of researchers led by Penn State found that across all ages, there was a slight increase in daily stress in the 2010s compared to the 1990s. But when researchers restricted the sample to people between the ages of 45 and 64, there was a sharp increase in daily stress.

"On average, people reported about 2 percent more stressors in the 2010s compared to people in the past," said David M. Almeida, professor of human development and family studies at Penn State. "That's around an additional week of stress a year. But what really surprised us is that people at mid-life reported a lot more stressors, about 19 percent more stress in 2010 than in 1990. And that translates to 64 more days of stress a year."

Almeida said the findings were part of a larger project aiming to discover whether health during the middle of Americans' lives has been changing over time. 

"Certainly, when you talk to people, they seem to think that daily life is more hectic and less certain these days," Almeida said. "And so we wanted to actually collect that data and run the analyses to test some of those ideas."

For the study, the researchers used data collected from 1,499 adults in 1995 and 782 different adults in 2012. Almeida said the goal was to study two cohorts of people who were the same age at the time the data was collected but born in different decades. All study participants were interviewed daily for eight consecutive days.

During each daily interview, the researchers asked the participants about their stressful experiences throughout the previous 24 hours. For example, arguments with family or friends or feeling overwhelmed at home or work. The participants were also asked how severe their stress was and whether those stressors were likely to impact other areas of their lives.

"We were able to estimate not only how frequently people experienced stress, but also what those stressors mean to them," Almeida said. "For example, did this stress affect their finances or their plans for the future. And by having these two cohorts of people, we were able to compare daily stress processes in 1990 with daily stress processes in 2010."

After analyzing the data, the researchers found that participants reported significantly more daily stress and lower well-being in the 2010s compared to the 1990s. Additionally, participants reported a 27 percent increase in the belief that stress would affect their finances and a 17 percent increase in the belief that stress would affect their future plans.

Almeida said he was surprised not that people were more stressed now than in the 90s, but at the age group that was mainly affected.

"We thought that with the economic uncertainty, life might be more stressful for younger adults," Almeida said. "But we didn't see that. We saw more stress for people at mid-life. And maybe that's because they have children who are facing an uncertain job market while also responsible for their own parents. So it's this generational squeeze that's making stress more prevalent for people at mid-life."

Almeida said that while there used to be a stereotype about people experiencing a midlife crisis because of a fear of death and getting older, he suspects the study findings -- recently published in the journal American Psychologist -- suggest midlife distress may be due to different reasons.

"It may have to do with people at mid-life being responsible for a lot of people," Almeida said. "They're responsible for their children, oftentimes they're responsible for their parents, and they may also be responsible for employees at work. And with that responsibility comes more daily stress, and maybe that's happening more so now than in the past."

Additionally, Almeida said the added stress could partially be due to life "speeding up" due to technological advances. This could be particularly true during stressful times like the coronavirus pandemic, when tuning out the news can seem impossible.

"With people always on their smartphones, they have access to constant news and information that could be overwhelming," Almeida said.

WEST LAFAYETTE, Ind. -- To just solve a puzzle or play a game, artificial intelligence can require software running on thousands of computers. That could be the energy that three nuclear plants produce in one hour.

A team of engineers has created hardware that can learn skills using a type of AI that currently runs on software platforms. Sharing intelligence features between hardware and software would offset the energy needed for using AI in more advanced applications such as self-driving cars or discovering drugs.

"Software is taking on most of the challenges in AI. If you could incorporate intelligence into the circuit components in addition to what is happening in software, you could do things that simply cannot be done today," said Shriram Ramanathan, a professor of materials engineering at Purdue University.

AI hardware development is still in early research stages. Researchers have demonstrated AI in pieces of potential hardware, but haven't yet addressed AI's large energy demand.

As AI penetrates more of daily life, a heavy reliance on software with massive energy needs is not sustainable, Ramanathan said. If hardware and software could share intelligence features, an area of silicon might be able to achieve more with a given input of energy.

Ramanathan's team is the first to demonstrate artificial "tree-like" memory in a piece of potential hardware at room temperature. Researchers in the past have only been able to observe this kind of memory in hardware at temperatures that are too low for electronic devices.

The results of this study are published in the journal Nature Communications.

The hardware that Ramanathan's team developed is made of a so-called quantum material. These materials are known for having properties that cannot be explained by classical physics. Ramanathan's lab has been working to better understand these materials and how they might be used to solve problems in electronics.

Software uses tree-like memory to organize information into various "branches," making that information easier to retrieve when learning new skills or tasks.

The strategy is inspired by how the human brain categorizes information and makes decisions.

“Humans memorize things in a tree structure of categories. We memorize ‘apple’ under the category of ‘fruit’ and ‘elephant’ under the category of ‘animal,’ for example,” said Hai-Tian Zhang, a Lillian Gilbreth postdoctoral fellow in Purdue's College of Engineering. "Mimicking these features in hardware is potentially interesting for brain-inspired computing."

The team introduced a proton to a quantum material called neodymium nickel oxide. They discovered that applying an electric pulse to the material moves around the proton. Each new position of the proton creates a different resistance state, which creates an information storage site called a memory state. Multiple electric pulses create a branch made up of memory states.

"We can build up many thousands of memory states in the material by taking advantage of quantum mechanical effects. The material stays the same. We are simply shuffling around protons," Ramanathan said.

Through simulations of the properties discovered in this material, the team showed that the material is capable of learning the numbers 0 through 9. The ability to learn numbers is a baseline test of artificial intelligence.

The demonstration of these trees at room temperature in a material is a step toward showing that hardware could offload tasks from software.

"This discovery opens up new frontiers for AI that have been largely ignored because implementing this kind of intelligence into electronic hardware didn't exist," Ramanathan said.

The material might also help create a way for humans to more naturally communicate with AI.

"Protons also are natural information transporters in human beings. A device enabled by proton transport may be a key component for eventually achieving direct communication with organisms, such as through a brain implant," Zhang said.