Press releases


Mar 3 2015

Satellite data shows that growing periods have changed worldwide/ Publication in Nature Climate Change

The Green Lungs of Our Planet are Changing

FRANKFURT.Are leaves and buds developing earlier in the spring? And do leaves stay on the trees longer in autumn? Do steppe ecosystems remaining green longer and are the savannas becoming drier and drier?  In fact, over recent decades, the growing seasons have changed everywhere around the world. This was determined by a doctoral candidate at the Goethe University as part of an international collaboration based on satellite data. The results are expected to have consequences for agriculture, interactions between species, the functioning of ecosystems, and the exchange of carbon dioxide and energy between the land surface and the atmosphere.  

"There is almost no part of the Earth that is not affected by these changes", explains Robert Buitenwerf, doctoral candidate at the Institute for Physical Geography at the Goethe University. He has evaluated satellite data from 1981 to 2012 with regard to 21 parameters on vegetation activity, in order to determine the point in time, the duration, and the intensity of growth from the northernmost conifer forests to tropical rain forests. His conclusion: On 54 percent of the land surface, at least one parameter of vegetation activity has moved away from the mean value by more than two standard deviations.

As reported by researchers from Frankfurt, Freiburg and New Zealand in the current edition of the professional journal "Nature Climate Change", leaves are now sprouting earlier in most of the climate zones of the far north. Although they are also dropped somewhat earlier in autumn, the overall vegetation period has grown longer. On the other hand, in our latitudes, trees and shrubs are losing their leaves later than they have up to now.

To date, not much research has been conducted on the regions of the southern hemisphere.  In those areas, the researchers found that in several savannas of South America, southern Africa and Australia, the vegetation activity has decreased during dry seasons. "Although these savannas have similar vegetation and comparable climates, the changes in vegetation activity differ. That may be attributable to the differences in the functioning of the respective ecosystems", says Buitenwerf.

In this respect, the seasonal distribution of leaf growth constitutes a sensitive indicator: it indicates how various ecosystems react to changes in the environment. "Although vegetation changes in the northern hemisphere have conclusively been attributed to climate change by other studies, attributing all the changes found in our study would require a more complex analysis," Buitenwerf emphasizes. In the northern hemisphere it has already been shown that species whose life cycles depend on the vegetation period are endangered by these severe changes.  Consequences for species in the southern hemisphere are as yet unclear.

Robert Buitenwerf, Laura Rose and Steven I. Higgins: Three decades of multi-dimensional change in global leaf phenology, in: Nature Climate Change, March 2 2015,
DOI: 10.1038/NCLIMATE2533.

Robert Buitenwerf, Landcare Research, Lincoln, New Zealand. Tel: +6433219706,

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Mar 3 2015

Simulations provide insight into their characteristics/gravitational waves as a unique fingerprint

Solving the Riddle of Neutron Stars

FRANKFURT. It has not yet been possible to measure the gravitational waves predicted by Einstein's theory of general relativity. They are so weak that they get lost in the noise of the measurements. But thanks to the latest simulations of the merging of binary neutron star systems, the structure of the sought-after signals is now known. As a team of German and Japanese theoretical astrophysicists reports in the Editor’s choice of the current edition of the scientific journal "Physical Review D", gravitational waves have a characteristic spectrum that is similar to the spectral lines of atoms.

Gravitational waves are generated when masses accelerate. The first indirect evidence for their existence was detected in 1974 when the binary pulsar PSR B1913+16 was discovered in the constellation Aquila. The two rapidly rotating neutron stars are drifting towards each other in a spiral shape, which is why, the astrophysicists explain, they are losing energy and emitting gravitational waves. Russell A. Hulse and Joseph H. Taylor received the 1993 Nobel Prize in Physics for this discovery. In the meantime, there are now several large-scale experiments for detecting gravitational waves: the American LIGO experiment, the European Virgo experiment, and the Japanese KAGRA detector. Experts estimate that signals of gravitational waves from merging binary neutron star systems will be detected within the next five years.

"These signals are not easy to detect, because they have an extremely small amplitude." But despite these difficult conditions, it is possible to find them, if you know what to look for in advance," explained Professor Luciano Rezzolla from the Institute for Theoretical Physics at Goethe University. Together with a Japanese colleague from Osaka University, he has studied a number of binary neutron star systems with the help of the latest simulation techniques and has discovered that the merging of the stars generates characteristic gravitational wave spectra. "These spectra correspond, at least logically, to the electromagnetic spectral lines emitted by atoms or molecules. From these we can derive information on the characteristics of the stars," explains Rezzolla.

As the astrophysicists show in two publications with related content in "Physical Review Letters" (published in November 2014) and in the current edition of "Physical Review D," the gravitational waves spectrum is like a fingerprint for the two stars. If scientists learn how to interpret these spectra, they will know what the neutron stars are made of and will be able to determine what is their equation of state, which is so far unknown. Equations of state describe the thermodynamic properties of systems as a function of variables, such as pressure, temperature, volume, or particle number. To this Rezzolla adds: "This is a very exciting possibility, because then we would be able to solve a riddle that has remained unsolved for 40 years: What are neutron stars made of and what is their stellar structure?"

 "If the signal is strong and thus the fingerprint is very clear, even a single measurement would be sufficient," Rezzolla predicts. "The prospects of solving the riddle of neutron stars have never been this good. The gravitational waves that we hope to detect in a few years are already on their way from the farthest reaches of the universe."

You can download images at:

Caption: Four snapshots from the merging of two neutron stars. Convergence to merger takes only a few milliseconds, during which immense masses are accelerated. The signals of the theoretically generated gravitational waves have now been calculated in simulations.

K. Takami, L. Rezzolla, and L. Baiotti, Constraining the Equation of State of Neutron Stars from Binary Merger, Phys. Rev. Lett. 113, 091104 (2014).

DOI: 10.1103/PhysRevLett.113.091104

K. Takami, L. Rezzolla, and L. Baiotti, Spectral properties of the post-merger gravitational-wave signal from binary neutron stars, Phys. Rev. D. 113, 091104 (2015), 2. März 2015.

Prof. Luciano Rezzolla, Institute for Theoretical Physics, Campus Riedberg, Tel.: (069) 798-47871,

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Feb 25 2015

Perception and memory are based on the same principles

The brain treats real and imaginary objects in the same way

The human brain can select relevant objects from a flood of information and edit out what is irrelevant. It also knows which parts belong to a whole. If, for example, we direct our attention to the doors of a house, the brain will preferentially process its windows, but not the neighbouring houses. Psychologists from Goethe University Frankfurt have now discovered that this also happens when parts of the objects are merely maintained in our memory.

"Perception and memory have mainly been investigated separately until now", explains Benjamin Peters, doctoral researcher at the Institute for Medical Psychology in the working group of Prof. Jochen Kaiser. There are close parallels, for in the same way as we can preferentially process external stimuli, we are also able to concentrate on the memory content that is currently the most important. These are essential skills of our brain, which are closely connected to intelligence and which are impaired in various psychiatric illnesses.

In their study, Peters and colleagues examined "object-based attention", a well-known phenomenon in perception research. This refers to the fact that we automatically extend our attention to the whole object when we attend only part of an object – like the front door and the windows.  In the experiment the subjects were asked to direct their attention alternately to one of four screen positions, which formed the ends of each of two artificial objects. In accordance with the principle of object-based attention the subjects were able to shift their attention more quickly between two positions that belonged to the same object than between those that were part of different objects. It was discovered that this effect also occurred when the subjects envisaged these positions only in short-term memory.

The researchers were able to describe the effect physiologically by examining the neuronal activity using magnetic resonance imaging (MRI). As expected, they initially found increased activity at those positions in the cerebral cortex where the currently focused position was represented (visual and parietal cortex). However, this increased activity also extended to the areas in the brain that represent the relevant associated position of the same object, despite the fact that the subject was not concentrating on it. Peters explains the results of the experiment by saying: "It is remarkable that this effect was observed in regions of the brain that are normally involved in perception, despite the fact that here, objects and positions were only maintained in memory". On the other hand, the regions in which the equidistant positions of the other object are represented remained unchanged.

This concordance of an underlying principle of attention in perception and in memory suggests that it may be possible to attribute many functions of human cognition to a few basic mechanisms.

Benjamin Peters et al.: Activity in Human Visual and Parietal Cortex Reveals Object-
Based Attention in Working Memory, in: The Journal of Neuroscience, February 25, 2015, 35(8):3360 –3369

Benjamin Peters, Institut für Medizinische Psychologie, Campus Niederrad, Tel.: (069) 6301-84735,

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Feb 12 2015

Frankfurt-based intensive care medical practitioner, Kai Zacharowski, is working on a joint curriculum for Europe

Cross-border intensive care medicine

FRANKFURT. Anyone who becomes seriously ill or has an accident while on holiday would like to be treated as well as they are at home. It is vitally important for the patient that the doctor has been well trained, in particular in intensive care medicine. A commission at the European Union under the leadership of Prof. Kai Zacharowski, the Director of the Clinic for Anaesthesiology, Intensive Care Medicine and Pain Therapy at the Goethe University Frankfurt is striving for uniform standards across Europe. This commission - shortened to MJC ICM for Multiple Joint Committee Intensive Care Medicine - has worked out general guidelines, which the member states are now expected to ratify. This will certainly not happen without compromises.

"United in diversity" - this is the motto of the European Union. At the level of professional training this diversity can also be obstructive, as it restricts the freedom there actually is in this diversity. And in the field of medicine diversity can also become a disadvantage to the patient. The regulations in intensive care medicine are particularly inconsistent. For example, in Germany medical practitioners initially finish their specialist medical training before they can be further trained as a practitioner in intensive care medicine, while in Spain, intensive care medicine is a specialist medical training directly connected to study. It's not surprising that a change within Europe for practitioners of intensive care medicine might be difficult.

"Young doctors do not want to commit themselves for their whole professional life to the field of intensive care medicine", Kai Zacharowski gives the reasons for the organisation of training in Germany. Shift work and the considerable psychological strain suggest that doctors should not commit themselves to intensive care medicine at too early a stage, according to the professor, who also represents Germany in the Union Européene des Médicins Spécialistes (UEmS). He considers a training period of a total of seven years to be essential: "After three years we cannot allow a young colleague to work independently". In the end, however, the length of training remains a matter for the individual states. There should, however, be uniform standards in the contents. Guidelines for the medical professions are drawn up nationally, by health ministries or by professional associations. There are already obligatory general requirements for subjects such as heart surgery, anaesthesia or neurosurgery. Now there is also to be a new European framework for intensive care medicine, which was worked out in agreement with the national professional associations.

"Intensive care medicine has changed a lot in the last few years", says Zacharowski: "We can now revive people, who would certainly have died ten years ago". This is resulting in new challenges for intensive care medicine and nursing treatment. A medical practitioner on the intensive care ward must competently manage the whole spectrum required in working with critically ill people: the replacement of organ functions, dialysis, artificial ventilation, the recognition and treatment of different types of blood poisoning, the correct use of antibiotics, the management of blood transfusions - and, not least, dealing with relatives.

On the basis of the EU-sponsored programme, CoBaTriCE, a paper was drawn up, which Zacharowski presented to the European Commission at the end of 2014 . Before parliament decides on the guidelines, the various national authorities must have ruled on them. Zacharowski is expecting a conclusion by the end of the year, before then, however, he will have to have many discussions. Individual countries such as Great Britain have already indicated a positive response, reports Zacharowski. Nevertheless, compromises will have to be reached, as in the end a more extensive training also means higher costs. It is certain, however: If Europe is to draw closer, a uniform training is essential.

Information: Prof. Dr. Dr. mailto:Direktion.Anaesthesie@kgu.deKai Zacharowski,

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Feb 10 2015

The German Meteorological Service sponsors a new professorship at the Goethe University with 1.2 million euros

Weather forecasts: Obtaining a better understanding of processes in the atmospheric boundary layer

FRANKFURT. Thunderstorms, wind, fog, extreme rainfall – all these weather events develop in the near-surface layer of air in the earth's atmosphere. Quantifying the processes that occur in this layer using meteorological models is still problematic. In order to improve its forecasts, over the next four years the German Meteorological Service will be sponsoring a new professorship for boundary layer meteorology at the Goethe University with the amount of 1.2 million euros.

The atmospheric boundary layer, up to one thousand metres thick, can attain altitudes comparable to that of the great Feldberg in the Taunus. This is where the exchange of humidity between the ground and the air occurs, triggering cloud formation, which in turn influences solar radiation. The enhanced description of the boundary layer in numerical weather forecasting, especially in the corresponding models of the German Meteorological Service, promises more reliable forecasting of extreme weather events such as heavy rainfall. At the same time, it could also provide more precise predictions of near-ground winds and solar radiation for wind farms and solar facilities.

"Without a good description of the atmospheric boundary layer, an accurate weather forecast is impossible", explains Prof. Ulrich Achatz of the Institute for Atmosphere and Environment at the Goethe University. It is particularly difficult to describe the boundary layer at night. During the day the ground is warmed up by solar radiation. The associated drop in temperature from the ground up to greater atmospheric altitudes promotes the formation of turbulence that can be described relatively well. At night, the near-ground temperatures drop while the boundary layer is stabilised and experiences a complex interaction between turbulence and atmospheric waves. This is not taken sufficiently into consideration in the weather forecast programmes currently in use.

Along with the professorship, the positions of a post-doctoral fellow and two doctoral candidates are being sponsored by the Hans Ertel Centre of the German Meteorological Service (DWD), which is assigning one of its own staff members to work at the university for the duration of the sponsorship. With this programme, which goes into its second sponsorship phase in 2015, the DWD is establishing research collaborations with German universities that are relevant for its own work. At the Goethe University, the new research field of boundary layer meteorology is being integrated into the course studies for the Bachelor's and Master's Programmes for Meteorology.

Information: Prof. Ulrich Achatz, Institute for Atmosphere and Environment, Phone +49 (0)69 798-40243,

Goethe University is a research-oriented university in the European financial centre Frankfurt Founded in 1914 with purely private funds by liberally-oriented Frankfurt citizens, it is dedicated to research and education under the motto "Science for Society" and to this day continues to function as a "citizens’ university".  Many of the early benefactors were Jewish.   Over the past 100 years, Goethe University has done pioneering work in the social and sociological sciences, chemistry, quantum physics, brain research and labour law.  It gained a unique level of autonomy on 1 January 2008 by returning to its historic roots as a privately funded university.   Today, it is among the top ten in external funding and among the top three largest universities in Germany, with three clusters of excellence in medicine, life sciences and the humanities.

Publisher: The President of Goethe University, Marketing and Communications Department, 60629 Frankfurt am Main

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