Technische Universität Darmstadt

Scientists recently presented a report on the status of global water resources. According to this report, large parts of the world experienced drier conditions in 2022 than those recorded on average for the equivalent periods over the last 30 years. The World Meteorological Organization (WMO) recently presented its second report on the status of global water resources. According to this report, large parts of the world experienced drier conditions in 2022 than those recorded on average for the equivalent periods over the last 30 years. "Nearly 40 percent of the territories examined were suffering from drier than normal conditions," said Professor Robert Reinecke of Johannes Gutenberg University Mainz (JGU). "This means that the flow rate of many rivers worldwide was significantly below what would normally be expected. Added to this, the levels of moisture in the soil were frequently indicative of the effects of the heatwaves we have experienced while the need for greater use of water has resulted in the groundwater table becoming lower than in the reference period." Reinecke, who joined the JGU Institute of Geography in May 2023, has made a major contribution to the new WMO report -- in collaboration with Dr. Hannes Müller Schmied of Goethe University Frankfurt and the Senckenberg Leibniz Biodiversity and Climate Research Center Frankfurt (SBiK-F) as well as the Global Runoff Database Center (GRDC) in Koblenz. Together they supplied simulation data based on hydrological modeling, participated in the development of the corresponding methodology, and provided scientific validation of the report's key statements. With the WMO acting as coordinating body, the report results from the expertise provided by 11 international modeling groups. The State of Global Water Resources 2022 report was published on October 12, 2023. Scientifically validated findings on the global water situation The first State of Global Water Resources Report for 2021 was presented in late November 2022 at the WMO headquarters in Geneva. The report is to appear annually and provide an overview of the status of the Earth's water resources. The effects of climatic fluctuations and changes can often also be seen by what happens to our water: Heatwaves coupled with droughts can make wildfires more likely and these can then spread more rapidly due to the lack of soil moisture, to give only one example. "The WMO report is thus also designed to provide politicians and the industry with knowledge so as to identify regions that are at risk of experiencing water emergencies or are already in crisis," added Reinecke. Among the data shown in the 2022 report is information on the discharge rate of rivers, the levels of groundwater, soil moisture, and evaporation. However, generation of the data basis itself is problematic in that there are currently insufficient global statistics available. "Thus, we need to undertake simulation modeling," explained Reinecke, a specialist in modeling techniques. There is a particular lack of data on the situation regarding groundwater. Even Germany cannot provide complete figures as to the related circumstances. However, there is no doubt that the dry conditions in 2022 had considerable impact in Germany, too. Just as in the case of the River Po in Italy, the water levels of the Rhine fell dramatically over longer periods, with the associated consequences for river traffic. France suffered from insufficient precipitation, resulting in difficulties when it came to providing the cooling required by nuclear power plants. South America experienced severe drought conditions while, despite increasing precipitation, groundwater levels in the important Murray-Darling Basin in Australia continued to drop below normal. New Earth System Modeling group at Mainz University Robert Reinecke was appointed to a junior professorship at JGU's Institute of Geography in May 2023. Here he will establish an Earth System Modeling group. After studying computer science at TU Darmstadt, being awarded a doctorate by Goethe University Frankfurt, and undertaking research in California, he was employed at the International Center for Water Resources and Global Change (ICWRGC). He subsequently undertook research as a postdoc at the Institute of Environmental Science and Geography of the University of Potsdam. His research focuses on global groundwater in the context of global hydrological modeling. He also investigates surface water/groundwater interaction, the human impact on groundwater resources, and the impact of climate change on the hydrological cycle.

Miniaturization is progressing rapidly in just any field and the trend towards the creation of ever smaller units is also prevalent in the world of robot technology. In the future, minuscule robots used in medical and pharmaceutical applications might be able to transport medication to targeted sites in the body. Statistical physics can contribute to the foundations for the development of such technologies. Miniaturization is progressing rapidly in just any field and the trend towards the creation of ever smaller units is also prevalent in the world of robot technology. In the future, minuscule robots used in medical and pharmaceutical applications might be able to transport medication to targeted sites in the body. Statistical physics can contribute to the foundations for the development of such technologies. A team of researchers at Johannes Gutenberg University Mainz (JGU) has now taken a new approach to the issue by analyzing a group of robots and how they behave as collectives of motile units based on the model of active Brownian particles. The team's findings demonstrating that there may be an alternative route to realize programmable active matter have been published in Science Advances. Collectives of robotic units could solve tasks that a single machine can not solve on its own Researchers are looking for new ways to perform tasks on the micro- and nanoscale that are otherwise difficult to realize, particularly as the miniaturization of devices and components is beginning to reach physical limits. One new option being considered is the use of collectives of robotic units in place of a single robot to complete a task. "The task-solving capabilities of one microrobot are limited due to its small size," said Professor Thomas Speck, who headed the study at Mainz University. "But a collective of such robots working together may well be able to carry out complex assignments with considerable success." Statistical physics becomes relevant here in that it analyzes models to describe how such collective behavior may emerge from interactions, comparable to bird behavior when they flock together. The research team studied the collective behavior of a number of small, commercially available robots. These so-called walkers are propelled through internal vibrations transmitted to two rows of tiny legs. Because the length, shape, and stiffness of the legs differ slightly from robot to robot, they follow circular orbits with a radius that is specific to each individual walker. Looking and moving like little beetles, these robots have an elliptical form and are sent off in a new direction when they happen to collide with each other. "Our aim was to examine and describe the collective behavior of these robots and determine whether it might be possible to derive potential uses from this," added Frank Siebers, lead author of the paper. "At the same time, we as physicists were also interested in the phenomena per se." The researchers were able to observe two effects when the collective of robots has variations in terms of their orbits, i.e., in a group showing greater diversity. Firstly, the walkers required less time to explore the space they were placed in. And secondly, when contained within an enclosed space, they began to undergo self-organized sorting. Depending on their orbital radius, the robots either accumulated at the confining wall or began to gather within the interior of the space. Statistical physics provides insights into the behavior of collectives "It would be possible to exploit this kind of activity to get robots to transport a load and to interact with that load, for example. The speed with which they would be able to traverse spaces would increase, meaning that the load would be delivered sooner," said Professor Thomas Speck, outlining one potential application. "Statistical physics can help to uncover new strategies that may be utilized by collectives of robots." The field of active matter models and robotics covers many realms of the living and the nonliving world in which collective behavior or collective movement can be observed, one prominent example being the way that flocks of birds move in unison. "What we have done here is to apply the theory underlying our understanding of clustering and swarming to robotic systems," said Frank Siebers of JGU. The research was funded under the aegis of the Collaborative Research Center/TRR 146 on Multiscale Simulation Methods for Soft Matter Systems, a cooperative project involving Johannes Gutenberg University Mainz, TU Darmstadt, and the Max Planck Institute for Polymer Research. The researchers based their conclusions on the outcome of their experiments as well as on model computations performed on JGU's supercomputer MOGON II. Principal investigator Professor Thomas Speck held a professorship at the JGU Institute of Physics from 2013 to 2022. He is now head of the Institute for Theoretical Physics IV of the University of Stuttgart.

Researchers are investigating the causes and consequences of the worldwide insect decline as well as considering potential countermeasures. A researcher from Mainz University has published work in a special issue of Biology Letters on the causes and consequences of the worldwide insect decline as well as potential countermeasures. Throughout the world we are witnessing not just a decline in the numbers of individual insects, but also a collapse of insect diversity. Major causes of this worrying trend are land-use intensification in the form of greater utilization for agriculture and building development as well as climate change and the spread of invasive animal species as a result of human trade. These are the main conclusions reached in the special feature on insect decline that recently appeared in Biology Letters. One of the three editors is PD Dr. Florian Menzel from the Institute of Organismic and Molecular Evolution at Johannes Gutenberg University Mainz (JGU). "As evidence of an on-going global crash in insect populations increased over the last few years, we decided it was time to edit and publish this special issue. Our aim was not to document insect population declines but to better understand their causes and consequences," said Menzel. Together with forest entomologist Professor Martin Gossner of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) and biologist Dr. Nadja Simons of TU Darmstadt, Menzel contacted international researchers in order to collate the information they could provide on insect declines and to stimulate new studies on the subject. The special issue authored by Menzel, Gossner and Simons includes 12 research-related articles, two opinion papers, and an extensive editorial. More extensive use of land, climate change, and invasive species are the main causes of insect decline "In view of the results available to us, we learned that not just land-use intensification, global warming, and the escalating dispersal of invasive species are the main drivers of the global disappearance of insects, but also that these drivers interact with each other," added Menzel. For example, ecosystems deteriorated by humans are more susceptible to climate change and so are their insect communities. Added to this, invasive species can establish easier in habitats damaged by human land-use and displace the native species. Hence, while many insect species decline or go extinct, few others, including invasive species, thrive and increase. This leads to an increasing homogenization of the insect communities across habitats. "It looks as if it is the specialized insect species that suffer most, while the more generalized species tend to survive. This is why we are now finding more insects capable of living nearly anywhere while those species that need specific habitats are on the wane," Menzel pointed out. The consequences of this development are numerous and generally detrimental for the ecosystems. For example, the loss of bumblebee diversity has resulted in a concomitant decline in plants that rely on certain bumblebee species for pollination. "Generally speaking, a decline in insect diversity threatens the stability of ecosystems. Fewer species means that there are fewer insects capable of pollinating plants and keeping pests in check. And, of course, this also means that there is less food available for insect-eating birds and other animals. Their continued existence can thus be placed at risk due to the decline in insect numbers," emphasized Menzel. In their editorial, Menzel, Gossner, and Simons suggest ways in which we can best respond to the effects that their gathered data has revealed. They advocate a particular approach for future research into insect decline. Standardized techniques should be employed to monitor insect diversity across many habitats and countries, the more so as in many regions of the world we still don't know how the insects are doing. The researchers also propose the creation of a network of interconnected nature reserves such that species can move from one habitat to another. Less heat-tolerant insects would thus be able to migrate from areas where global warming is causing temperatures to rise to higher elevations or cooler regions in the north. Furthermore, we need measures to reduce the dispersal of invasive animal and plant species through our globalized trade and tourism. "This is another problem that has become extremely serious in the last decades," concluded Menzel. One example cited in the current special issue is the invasion of non-native insectivorous fishes in Brazil that has caused a major decline in freshwater insects.