Refine
Year of publication
Document Type
- Part of Periodical (20)
- Article (4)
Language
- English (24) (remove)
Is part of the Bibliography
- yes (24)
Institute
The influence of Daphnia galeata x hyalina grazing and of infochemicals released by the daphnids on the colony size and growth rate of the colonial gelatinous green alga Sphaerocystis schroeteri (Chlorococcales) was investigated in laboratory batch experiments run for 96 h. High zooplankton grazing pressure was exerted by a final concentration of 100 daphnids L-1 in the Daphnia treatments. Infochemicals were obtained by filtration (0.2 µm) of water from D. galeata x hyalina cultures (200 ind. L-1 exposed for 24 h). This filtrate was added to the S. schroeteri cultures in two concentrations corresponding to 7 and 50 daphnids L-1, respectively. The growth rate of S. schroeteri was neither affected significantly by direct Daphnia grazing nor by the presence of Daphnia infochemicals in comparison to the control. However, the portion of inedible S. schroeteri colonies (diameter > 50 µm) increased under direct grazing pressure, whereas the Daphnia infochemicals did not influence the colony size significantly. We conclude that the shift in colony size by direct zooplankton grazing denotes an effective defence mechanism against size selective feeding for colonial gelatinous green algae. This effective defence in combination with unchanged growth rates of the larger colonies (under non-limiting nutrient and light conditions) falsifies the assumption of a trade-off between minimising grazing losses and maximising growth by optimising the colony size.
For a long time, there were things on this planet that only humans could do, but this time might be coming to an end. By using the universal tool that makes us unique – our intelligence – we have worked to eliminate our uniqueness, at least when it comes to solving cognitive tasks. Artificial intelligence is now able to play chess, understand language, and drive a car – and often better than we.
How did we get here? The philosopher Aristotle formulated the first “laws of thought” in his syllogisms, and the mathematicians Blaise Pascal and Wilhelm Leibniz built some of the earliest calculating machines. The mathematician George Boole was the first to introduce a formal language to represent logic. The natural scientist Alan Turing created his deciphering machine “Colossus,” the first programmable computer. Philosophers, mathematicians, psychologists, and linguists – for centuries, scientists have been developing formulas, machines, and theories that were supposed to enable us to reproduce and possibly even enhance our most valuable ability.
But what exactly is “artificial intelligence”? Even the name calls for comparison. Is artificial intelligence like human intelligence? Alan Turing came up with a test in 1950 to provide a satisfying operational definition of intelligence: According to him, a machine is intelligent if its thinking abilities equal those of humans. It has to reach human levels for any cognitive task. The machine has to prove this by convincing a human interrogator that it is human. Not an easy task: After all, it has to process natural language, store knowledge, draw conclusions, and learn something new. In fact, over the past ten years, a number of AI systems have emerged that have passed the test one way or another in chat conversations with automatically generated texts or images. Nowadays, the discussion usually centers on other questions: Does AI still need its creators? Will it not only outperform humans but someday replace them – be it in the world of work or even beyond? Will AI solve our problems in the age of all-encompassing digital networking – or will it become a part of the problem?
Artificial intelligence, its nature, its limitations, its potential, and its relationship to humans were being discussed even before it existed. Literature and film have created scenarios with very different endings. But what is the view of the scientists who are actually researching with or about artificial intelligence? For the current issue of our research magazine, a cognitive scientist, an education researcher, and a computer scientist shared their views. We also searched the University for projects whose professional environment reveals the numerous opportunities that AI offers for various disciplines. We cover the geosciences and computer science as well as economics, health, and literature studies.
At the same time, we have not lost sight of the broad research spectrum at the University: a legal expert introduces us to the not-so-distant sphere of space law while astrophysicists work on ensuring that state-of-the-art telescopes observe those regions in space where something “is happening” at the right time. A chemist explains why the battery of the future will come from a printer, and molecular biologists explain how they will breed stress-resistant plants. You will read about all this in this issue as well as about current studies on restless legs syndrome in children and the situation of Muslims in Brandenburg. Last but not least, we will introduce you to the sheep currently grazing in Sanssouci Park – all on behalf of science. Quite clever!
Enjoy your read!
THE EDITORS
Portal Wissen = Believe
(2014)
People want to know what is real. Children enjoy listening to a story but when my children were about four years old they started asking whether the story really happened or was just invented. Likewise, only on a higher level, our academic curiosity is fuelled by our interest in knowing what is real. When we analyze poetic texts or dreams we are trying to distinguish between the facts (e.g. neurological ones or linguistic structures) and merely assumed influences. Ideally we can present results that were logically understood by others and that we can repeat empirically. But in most cases this is not possible. We cannot read every book and cannot look through every microscope, not even within our own discipline. In the world we live in we depend on trusting the information of others, like how to get to the train station or what the weather is like in Ulaanbataar. This is why we are used to believing others, our friends or the news anchors. This is not a childish behavior but a necessity. Of course, it is risky because they could all be lying to us, like in a Truman Show situation. The only time we are able to know that we are in reality is when we transcend our selfconsciousness and when we accept two propositions: first, that we are not only objects but also subjects in the consciousness of others and second that our dialogic relations are again observed by a third party that is not part of this intersubjective world.
For religious people this is “belief” - belief as the assumption that all human relations only become real, serious and beyond any doubt if they know they are under the eyes of God. Only before Him something is in itself and not only “for me” or “among us”. That is why biblical language distinguishes between three forms of belief: the relationship with the world of things (“to believe that”), the relationship to the world of subjects (“to believe somebody”) and the assumption of a subjective supernatural reality (“to believe in” or “faith”). From an academic point of view belief is a holistic hypothesis. Belief is not the opposite of knowledge but it is the attempt to save reality from doubt by comprehending the fragile empirical world as an expression of a stable transcendent world.
When I talk to students they often ask not only about what I know but what I believe. As a professor for Religious Studies and a believing Catholic I am caught in the middle. On the one hand, it is my duty as a professor to doubt everything, i.e. to attribute each religious text to its historical context and sociological functions. On the other hand, I, as a Christian, consider certain religious documents, in my case the Bible, an interpretable but nevertheless irreversible, revealed text about the origin of reality. On weekdays the New Testament is a collection of ancient writings among many others, on Sundays it is the revelation. You can make a clear distinction between these two perspectives but it is difficult to decide whether doubt or belief is more real.
This issue of “Portal Wissen” explores this dual relationship of belief. What is the attitude of science towards belief – is it a religious one? Where does science bring things to light that we can hardly believe or that make us believe (again)? What happens if research clears up erroneous assumptions or myths? Is science able to investigate things that are convincing but inexplicable? How can it maintain its credibility and develop even so?
These questions appear again and again in the contributions of this “Portal Wissen”. They form a manifold, exciting and surprising picture of the research projects and academics at the University of Potsdam. Believe me, it will be an enjoyable read.
Prof. Johann Hafner
Professor of Religious Studies with Focus on Christianity Dean of the Faculty of Arts
Portal Wissen = Borders
(2013)
The new edition of the Potsdam Research Magazine “Portal Wissen” approaches the subject “Borders” from different perspectives.
As a linguist, this headline makes me think of linguistic borders and the effects that might result from the contact of two languages at a particular border. There is, for instance, ample evidence of code-switching, i.e. the use of material from at least two languages in a single utterance. The reasons for code-switching can be manifold. On the one hand, code-switching may result from a limited language competence, for example if a speaker lacks a particular word in a nonnative language. On the other hand, code-switching may be a matter of prestige if the speaker wants to demonstrate his or her affiliation to a certain social group by switching languages. If code-switching does not only occur sporadically but involves whole language communities over a longer period of time, it can result in significant changes of the involved languages. Which language “gives” and which one “takes” is determined by sociolinguistic factors. It is, hence, quite easy to predict that German varieties spoken in language islands in South and Eastern Europe as well as in North and Latin America will absorb more and more language material from their neighbouring languages until they disappear unless political will strives to preserve these language varieties. Increasing mobility of modern societies has multiplied the extent and the intensity of language contact and certainly comprises a large number of different contact situations besides the one most commonly known, i.e. the contact between German and English.
From a historic point of view, German witnesses a strong influence of various Romance languages such as Latin, French and Italian. In Potsdam, one cannot help being reminded of the French influence during the 18th century.
Overcoming language borders becomes also apparent in the everyday life of an international research university. In March this year, the Annual Conference of the German Linguistic Society took place in Potsdam, with more than 500 participants. Lingua franca of this conference was English. Compared to previous conferences, this further increased the number of international participants.
The articles in this edition illustrate various approaches to the topic “Borders”: On the trail of “Boundary Surveys”, we follow the Australian explorer Ludwig Leichhardt. “Travellers Across Borders” is focussed on articles dealing with the literature of the colonial Caribbean or with the work of an Italian geologist deep beneath the earth’s surface, for example. Looking for the “Boundless”, our authors follow scientists who discuss questions like “Why love hurts?”. The present issue of “Portal Wissen” also takes into account “Drawing Up Borders” in an article that is concerned with the limits of workrelated stress. Instances of successful “Border Crossing” are provided by the “Handkerchief Lab” as well as by new biotechnological applications.
I would like to wish you inspiring border experiences, hoping that you will get many impulses for crossing professional borders in your field of expertise.
Prof. Ulrike Demske
Professor of the History and the Varieties of the German Language
Vice President International Affairs, Alumni and Fundraising
Portal Wissen = Change
(2021)
Change makes everything different. Let’s be honest: Just about everything is constantly in transformation. Even huge massifs that seem like eternity turned to stone will eventually dissolve into dust. So is change itself the only constant? The Greek philosopher Heraclitus certainly thought so. He said, “The only thing that is constant is change.”
Change is frightening. A change that we cannot explain throws us into turmoil – like a magic trick we cannot decipher. Viruses that mutate, ecosystems that collapse, stars that perish – they all seem to threaten the fragile balance that makes our existence possible. Humanity is late in recognizing that we ourselves are all too often the impetus for dangerous transformations.
Change gives hope. People have always been fascinated by change and felt compelled to explore its origin and essence. Quite successfully. We understand many things much better than generations before. But well enough? Not at all. Alexander von Humboldt said, “Every law of nature that reveals itself to the observer suggests a higher, as yet unrecognized one.” There is still much to be done.
The current issue of Portal Wissen is all about change. We spoke to an astrophysicist who has found her happiness in researching the formation and change of stars. We also look at different aspects of the very earthly climate change and its consequences: A geoscientist explains how global warming affects the stability of mountain ranges.
A legal expert makes clear that the call for a right to climate protection has gone largely unheard until now. How human land use affects biodiversity is being investigated by young researchers of the “Bio- Move” research training group, who have provided us with insights into their work on brown hares, water fleas, and mallard ducks. Other researchers focus on change in the contexts of humans. A group of nutrition scientists at the German Institute of Human Nutrition (DIfE) and sports scientists at the University of Potsdam are investigating the factors that cause our bodies to change as we age – and why some people lose muscles more quickly than others.
Despite all these changes, we do not lose sight of the diversity of research at the University of Potsdam. A visit to the laboratory of the project “OptiZeD” gives us an idea of the possibilities offered by optical sensors for the personalized medicine of tomorrow, while an educational researcher explains why cultural diversity is an asset beneficial to our education. In addition, a cultural scientist reports on the fascination of comics. They are all part of the hopeful change that science is initiating and accomplishing! Enjoy the read!
Portal Wissen = Cosmos
(2018)
Speaking of the cosmos means speaking about nothing less than everything, about the entirety of space filled with matter and energy. We only see a tiny fraction of it from Earth: planets like Venus or stars like the Sun. There are at least 100 billion stars in our home galaxy alone. Bound by gravity, these luminescent celestial bodies of very hot gas form a system visible from Earth as a whitish ribbon, which we call the Milky Way. The observable cosmos contains at least 100 billion such galaxies with stars, cosmic dust, gas, and probably dark matter as well. The universe is 13.8 billion years old; crossing it once would probably take 78 billion light-years.
Given these dimensions, it is hardly surprising that for us humans, the mystery of the properties of the cosmos is connected with questions of being. Where do we come from? Where are we going? Are we alone in the universe? Such questions are in the wheelhouse of astrophysicists, who explore the vastness of the cosmos through physical means, even though they, of course, deal with physical laws, mathematical formulas, and complicated measuring methods. In this issue of Portal Wissen, we talked with astrophysicists at the University of Potsdam about their research and everyday work.
Lutz Wisotzki showed us a 3D spectrograph, which he has developed in collaboration with colleagues from the Leibniz Institute for Astrophysics (AIP) and six other European institutes. This technical masterpiece enables scientists to look deeply into space and to “journey” through time to galaxies shortly after the Big Bang. Philipp Richter introduced us to the astrophysics research initiative and demonstrated how the University of Potsdam is working together with the AIP, the Albert Einstein Institute (AEI) and the Deutsches Elektronen-Synchrotron (DESY) to train junior researchers. The newly appointed Professor of Stellar Astrophysics, Stephan Geier, presented us with stars so close together to each other that they appear to be one to the naked eye. The physicist, who is also a historian, researches their turbulent relationships.
We have not confined ourselves to cosmic themes, though, but also questioned rather earthly matters such as modern consumption. We have thought about potential love relationships with robots and testimonials in literature and art. We learned why the rainforest in Central Africa disappeared 2,600 years ago, how to produce knee prostheses on a production line, and how animals in the field benefit from big data.
But back to the cosmos. The writing of late astrophysicist Stephen Hawking fundamentally shaped our concepts and knowledge of the universe. And that is because he was both an important physicist and a literary genius. Hardly anyone has been able to capture difficult facts in such a clear, understandable, and beautiful language. With this exemplary understanding of science in mind, we hope to offer you a stimulating read.
The Editors
Portal Wissen = Data
(2019)
Data assimilation? Stop! Don’t be afraid, please, come closer! No tongue twister, no rocket science. Or is it? Let’s see. It is a matter of fact, however, that data assimilation has been around for a long time and (almost) everywhere. But only in the age of supercomputers has it assumed amazing proportions.
Everyone knows data. Assimilation, however, is a difficult term for something that happens around us all the time: adaptation. Nature in particular has demonstrated to us for millions of years how evolutionary adaptation works. From unicellular organisms to primates, from algae to sequoias, from dinosaurs ... Anyone who cannot adapt will quickly not fit in anymore.
We of course have also learned to adapt in new situations and act accordingly. When we want to cross the street, we have a plan of how to do this: go to the curb, look left and right, and only cross the street if there’s no car (coming). If we do all this and adapt our plan to the traffic we see, we will not just safely cross the street, but we will also have successfully practiced data assimilation.
Of course, that sounds different when researchers try to explain how data assimilation helps them. Meteorologists, for example, have been working with data assimilation for years. The German Weather Service writes, “In numerical weather prediction, data assimilation is the approximation of a model run to the actual development of the atmosphere as described by existing observations.” What it means is that a weather forecast is only accurate if the model which is used for its calculation is repeatedly updated, i.e. assimilated, with new measurement data.
In 2017 an entire Collaborative Research Center was established at the University of Potsdam, CRC 1294, to deal with the mathematical basics of data assimilation. For Portal Wissen, we asked the mathematicians and speakers of the CRC Prof. Sebastian Reich and Prof. Wilhelm Huisinga how exactly data assimilation works and in which areas of research they can be used profitably in the future. We have looked at two projects at the CRC itself: the analysis of eye movements and the research on space weather.
In addition, the current issue is full of research projects that revolve around data in very different ways. Atmospheric physicist Markus Rex throws a glance at the spectacular MOSAiC expedition. Starting in September 2019, the German research icebreaker “Polarstern” will drift through the Arctic Ocean for a year and collect numerous data on ice, ocean, biosphere, and atmosphere. In the project “TraceAge”, nutritionists will use the data from thousands of subjects who participated in a long-term study to find out more about the function of trace elements in our body. Computer scientists have developed a method to filter relevant information from the flood of data on the worldwide web so as to enable visually impaired to surf the Internet more easily. And a geophysicist is working on developing an early warning system for volcanic eruptions from seemingly inconspicuous seismic data.
Not least, this issue deals with the fascination of fire and ice, the possibilities that digitization offers for administration, and the question of how to inspire children for sports and exercise. We hope you enjoy reading – and if you send us some of your reading experience, we will assimilate it into our next issue. Promised!
Portal Wissen = Departure
(2021)
On October 20, 1911, the Norwegian Roald Amundsen left the safe base camp “Framheim” at the Bay of Whales together with four other explorers and 52 sledge dogs to be the first person to reach the South Pole. Ahead of them lay the perpetual ice at temperatures of 20 to 30 degrees Celsius below zero and a distance of 1,400 kilometers. After eight weeks, the group reached its destination on December 13. The men planted the Norwegian flag in the lonely snow and shortly afterwards set off to make their way back – celebrated, honored as conquerors of the South Pole and laden with information and knowledge from the world of Antarctica. The voyage of Amundsen and his companions is undoubtedly so extraordinary because the five proved that it was possible and were the first to succeed. It is, however, also a symbol of what enables humans to push the boundaries of their world: the urge to set out into the unknown, to discover what has not yet been found, explored, and described.
What distinguishes science - even before each discovery and new knowledge – is the element of departure. Questioning apparent certainties, taking a critical look at outdated knowledge, and breaking down encrusted thought patterns is the starting point of exploratory curiosity. And to set out from there for new knowledge is the essence of scientific activities – neither protected nor supported by the reliable and known. Probing, trying, courageously questioning, and sensing that the solid ground, which still lies hidden, can only be reached again in this way. “Research is always a departure for new shoreless waters,” said chemist Prof. Dr. Hans-Jürgen Quadbeck-Seeger. Leaving behind the safe harbor, trusting that new shores are waiting and can be reached is the impetus that makes science so important and valuable.
For the current issue of the University of Potsdam’s research magazine, we looked over the shoulders of some researchers as they set out on new research journeys – whether in the lab, in the library, in space, or in the mind. Astrophysicist Lidia Oskinova, for example, uses the Hubble telescope to search for particularly massive stars, while hydrologist Thorsten Wagener is trying to better understand the paths of water on Earth. Economists and social scientists such as Elmar Kriegler and Maik Heinemann are researching in different projects what politics can do to achieve a turnaround in climate policy and stop climate change.
Time and again, however, such departures are themselves the focus of research: And a group of biologists and environmental scientists is investigating how nature revives forest fire areas and how the newly emerging forests can become more resilient to future fires.
Since – as has already been said – a departure is inherent in every research question, this time the entire issue of “Portal Wissen” is actually devoted to the cover topic. And so we invite you to set out with Romance linguist Annette Gerstenberg to research language in old age, with immunologist Katja Hanack to develop a quick and safe SARS-CoV-2 test, and with the team of the Potsdam Center for Industry 4.0 to the virtual factory of tomorrow. And we will show you how evidence- based economic research can inform and advise politicians, and how a warning system is intended to prevent future accidents involving cyclists.
So, what are you waiting for?!
Portal Wissen = Earth
(2017)
Earth’s surface is constantly changing. It is the synergetic overlap between the geosphere, biosphere, and climatic sphere and influences the development of our planet. It is our habitat and plays a key role in maintaining the wellbeing of humanity. Many aspects of this system as a whole, however, are not yet understood.
This needs to change immediately because there is not much time left for the Earth – or for us. Photographer and filmmaker Yann Arthus- Bertrand warned in 2009, “In less than 200 years we have disturbed the balance of the Earth that has been created in over four billion years.” Potsdam and Berlin geoscientists, biologists, and climatologists have now joined forces*: They are investigating processes of the Earth's surface in order to better understand them on various spatial and time scales and to predict how our living environment will develop.
In this issue of the research magazine “Portal Wissen”, we present some of the research projects as well as the researchers who drive them. We followed researchers to Ethiopia – to the “cradle of humankind” – where elaborate drilling is offering a glimpse into climate history. Analyses of the several-hundred-thousand- year old deposits provide insights not only for geological and climate researchers. Biologists were able to reconstruct how entire ecosystems developed over long periods using state-of-the-art genetic analysis. A geomicrobiologist shows us the vast insight you get when you cross disciplinary boundaries. His research is no longer taking place on and in the earth but even in outer space. The young researchers of the research training group StRatGy cut large boulders from the Argentinean Andes into the thinnest of slices in order to understand how the mountains developed. And a data analysis expert explains why it is not enough to collect and feed a lot of data into a computer; they also have to be made readable using the right analytic tools.
“The world is a fine place and worth the fighting for,” wrote Ernest Hemingway. This is exactly what researchers are doing when they look for solutions to prevent humanity from irreversibly damaging the Earth. We met a researcher who is working with colleagues throughout Europe to learn more about trace elements and using plants as pollutant “vacuum cleaners”. And it was explained to us how satellite images taken from afar are revolutionizing nature conservation.
The diversity of research at the University of Potsdam should not be forgotten. We followed administrative scientists on the trail of successful reforms around the world and we looked at how reading can be more successful. We asked what supplementary extracurricular lessons can offer (or not offer) and looked into the networked classroom of the future. Germanists also revealed their Brandenburg linguistic treasures to us, psychologists showed us their experiments, and a historian explained to us why the MfS – the GDR state security ministry – were active as development workers. Last but not least, we visited a chemist in the lab, were introduced to the language of climate images, and listened to a romance philologist who researches with all her senses.
Enjoy your read!
The Editors
Portal Wissen = Energy
(2020)
Energy – there is something to it. There is, of course, the matter-of-fact definition in every student encyclopedia: “the capacity to do mechanical work, transfer heat, or emit light.” In this way, energy accompanies us, often undetected, all day long: getting out of bed, turning on the heat, switching on the lights, taking a hot shower, getting dressed, making coffee, having breakfast – before we have even left the house, we have already released, transformed, applied, and refueled a lot of energy. And we haven’t even worked, at least not in the traditional sense.
But energy is not just a physical quantity that, due to its omnipresence, plays a key role in every natural science discipline, such as biology and chemistry, but also in almost every technical field. It is also indispensable when it comes to how we understand and describe our world and our activities – and it has been for a long time. How about an example? The Greek philosopher Aristotle was the first to speak of enérgeia, for him a rather nonphysical thing, a living “reality and effectiveness ” – that which makes the possible real. About 2,100 years later, the uncrowned king of German literature Johann Wolfgang von Goethe declared it to be a humanistic essence. “What can we call our own if not energy, strength, and will!” And for his contemporary Wilhelm von Humboldt, energy “was the human’s first and only virtue”. Although physics began to dominate the concept of energy when it became the leading science in the 19th century, energy remained significant in many areas.
Reason enough for us to take a look at energy-related matters at the University of Potsdam. We found them in a wide range of disciplines: While Iranian physicist Safa Shoaee is researching how organic materials can be used to manufacture the solar cells of the future, Swedish environmental researcher Johan Lilliestam is focusing on the different dimensions of the energy transition to learn what makes it successful. Slavicist Susanne Strätling, on the other hand, crosses the boundaries of her discipline as she examines a complex conceptual history and tries to find out why energy electrifies us today more than ever. And physicist Markus Gühr is able to use ultrashort flashes of light to investigate how molecules change under its influence and convert energy in the process.
Of course, we have enough energy to highlight the diversity of research at the University of Potsdam besides the feature topic of this issue. A cognitive researcher, for example, explains why our brain processes both music and language according to its own respective rhythm, while an environmental researcher presents a method that uses particles from outer space to measure soil moisture. Educational researchers have also launched a study on hate speech in schools and we introduce a palaeoclimatologist who is one of twelve researchers in the new postdoc program at the University of Potsdam. We have spared no energy!