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Short Circuit in the Food Web

Chemists of Jena University shed light upon mechanisms of viral diseases of marine algae

They are amongst the most numerous inhabitants of the sea: tiny haptophytes of the type Emiliania huxleyi. Not visible to the naked eye, when they are in bloom in spring, they form square kilometer sized patches, they are even visible on satellite images. "Together with other phytoplankton, Emiliania huxleyi is responsible for approximately half of the global photosynthesis output," states Prof. Dr. Georg Pohnert of the Friedrich Schiller University Jena (Germany). In the process the greenhouse gas carbon dioxide - CO2 - is extracted from the atmosphere and oxygen is set free. "Additionally the microalgae use CO2 to produce tiny calcified discs which re-enforce their outer skin," the chair for Instrumental Analysis and Bio-organic Analysis continues. Thus the unicellular algae are a decisive factor for a stable world climate.

However the annual bloom of Emiliania huxleyi regularly comes to a rapid ending: the algae are massively affected by viruses and thus die off. Until now it remained unclear exactly how the viruses killed the algae. But together with scientists of the Weizman Institute in Israel the team around Prof. Pohnert has now analyzed the complex interaction between the algae and the viruses. In the science magazine 'The Plant Cell' the researchers describe how they could clarify the molecular mechanisms of the relationship between the virus and the algae, which crucially influences the food chain of the oceans. (DOI: 10.1105/tpc.114.125641).

To find this out, the researchers infected algae in controlled conditions in a laboratory and afterwards analyzed the whole metabolism of the microalgae. "The viruses intervene massively with the metabolism of the algae," Pohnert sums up the results. So for instance they use chemical components of the algae to multiply themselves, because for viruses replication is only possible with the active help of a host organism. "The viruses prompt the algae to produce exactly the molecular components which they, the viruses, need for themselves," Pohnert says. As early as one hour after the beginning of the infection the viruses completely turned the metabolism of the algae upside down. The algae then increase the production of certain sphingolipids, which the viruses need to multiply. After a few hours the infected algae burst and each one sets free about 500 new viruses.

But the micro algae don't succumb to their fate without a fight, as the scientists were able to show in their new study. "They fight back by drastically reducing the biosynthesis of so-called terpenes," Pohnert explains. The viruses also rely on these hydrocarbons. If their production is switched off by so-called inhibitors in model experiments, the production of viruses decreases distinctly.

The Jena researchers and their Israeli colleagues are now planning to double-check their results from the laboratory in real life - in the sea. Emiliania huxleyi and its viruses thereby serve as a model system to better our understanding of the marine food chain. Until recently, the food web of the oceans was mostly considered a linear organization, according to Prof. Pohnert: Algae, which store solar energy and combine with CO2, are the basic food resource for small animals and fish, which in turn are being eaten by bigger fish. The viruses however create a kind of 'short circuit' in this chain. "Thus the viruses divert a substantial part of the whole fixed carbon from the food chain as we know it so far, and supply deep sea bacteria with it," Pohnert says. Which consequences this will have for other organisms in the sea and the whole ecological system will be shown by future studies. US

Contact:
Prof. Dr. Georg Pohnert
Institute for Inorganic and Analytical Chemistry Bioorganic Analytics
Friedrich Schiller University Jena
Lessingstraße 8, 07743 Jena
Germany
Phone:++49 3641 948170
Email:

 

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Common grounds for trans-continental photonics research

The Abbe Center of Photonics (ACP) of the Friedrich Schiller University Jena (Germany) and the Australian Centre for Ultrahigh bandwidth Devices and Optical Systems (CUDOS) agree on a Memorandum of Understanding to foster trans-continental research

The 21st century is becoming the century of optical technologies and photonics. Photonics today is a key technology in every respect, meeting challenges of globalized human society. In Jena, a medium-sized city at the heart of Germany, "Light" indeed reflects the long history of optics and photonics research and teaching, as well as the strong link between research and local industries. For more than a century, the city of Jena has been a world-leading location in the sciences of light. The breakthrough work of the physicist Ernst Abbe, the first to formulate the limit of optical resolution due to diffraction, provided the roots to develop an exceptionally strong community specializing in optics and photonics. The significance of this field continues to flourish to this day. There is hardly another place where science penetrates all aspects of life as much as it does in Jena - more than 25,000 students and junior scientists shape the city's character, and more than 15 % of Jena's residents are employed in the sector of optics and photonics. At the Friedrich Schiller University, the Abbe Center of Photonics (ACP) is the academic key player in that field: This interfaculty center projects the distinguished recognition of Jena as the "City of Light" and of the University as an international center for optical sciences to a national and international audience.

Close interconnections and collaborative schemes with numerous partners in science and industry contribute to ACP´s success. Now, it has gained another international prime partner: the Australian Centre for Ultrahigh bandwidth Devices and Optical Systems (CUDOS), an Australian Research Council (ARC) Centre of Excellence merging seven Australian Universities, among them universities from Canberra, Sydney and Melbourne.

Both centers will team up to tackle one of the major challenges which photonic technologies are expected to meet in the 21st century: the bottleneck of electronic components in the IT industry. When the first computers emerged more than 70 years ago, they were still space filling behemoths. Ever since, the next-generation computer chips have not only become much more powerful, but also smaller by orders of magnitude. However, the end of this development seems in reach as the miniaturization of electronic components does have physical limits. Many scientists and engineers believe that the signal processing by means of light will play an increasingly important role in the near future. In addition, optical components are less susceptible and more sustainable as, for instance, less pure and thus less expensive silicon is needed for their production. The photonics community therefore shares the vision to develop unprecedented fast, small and cheap optical computer chips. At this point, the interests of ACP and CUDOS overlap: While ACP tackles this goal by exploring the fundamentals of novel photonic materials and miniaturized light sources, CUDOS fosters the development of photonic chips for all-optical signal processing. On the one hand, within ACP's core research domain "Ultra Optics", the German center's principal scientists strive to attain control of light and of all its properties, which would potentially allow for using light as an instrument, tool or carrier of information. Among others, ACP combines laser physics, nanooptics, photonic materials and optical design in a synergistic way. The CUDOS mission, on the other hand, focuses on integrated nanophotonics for all-optical information processing as well as on signal processing applications with excellent power efficiency. By going to single photon power levels, CUDOS scientists also aim at opening up a host of applications on the quantum scale. These exciting research opportunities will be explored by CUDOS over the coming years to develop ultrafast signal processors, quantum photonic processors, and integrated photonic devices for the mid infrared. The partnership of the two centers is an exciting match with a trans-continental reach - both centers expect that their complementary expertise will create an added value along the whole chain of research and development of future photonic components.

To that end, a Memorandum of Understanding (MoU) was signed on September 15, 2014 by ACP director Prof. Thomas Pertsch and CUDOS director Prof. Benjamin in Jena. The MoU was further embedded in a two-day scientific workshop on optical materials, photonic devices and nonlinear optics to ignite future collaborative projects between the centers. "We are very excited about the approach of this event. The Memorandum of Understanding and the workshop are excellent first steps in establishing and promoting long-lasting synergies in photonics research around the globe," both Prof. Eggleton and Prof. Pertsch agree.

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Welcome and “Good-bye”

Investiture of the new president and farewell of the rector

In a ceremonial act on Monday, 6 October 2014, the rector Prof. Dr. Klaus Dicke was bid farewell and the new president Prof. Dr. Walter Rosenthal was officially inaugurated. A number of high-profile guests from far and wide attended the investiture in the auditorium of the Friedrich Schiller University Jena (FSU). The well-attended event was accentuated by music. Among the guests were the minister-president Christine Lieberknecht and her deputy, the minister of science Christoph Matschie. After the greeting by the chairman of the University Council Dr. Josef Lange, Lieberknecht and Matschie emphasised the importance of the FSU in their speeches and stressed the necessity of an adequate financial funding of the University. Matschie renewed his promise to compensate for the increase in costs, with the additional 1 % increase. The minister-president called the FSU "the flagship among the Universities and institutions of higher education in Thuringia" - a credit which - according to her - also belongs to the departing rector Klaus Dicke. All speakers thanked Dicke for his commitment and his circumspection during his time as rector.

Dicke, who will continue in his office until 15. October, titled his speech - which was as brilliant as usual - "Looking back ahead". Apart from acknowledging many colleagues, he couldn't be deterred from pointing out the remaining challenges - like the development of the Inselplatz - and to remind the politicians of their financial responsibilities: "In order to prevent severe damage to the performance of institutions of higher education in Germany, the federal states have to increase their basic financing with the support of the federal government significantly. The argument about the overhead has to be resolved, and not by 20 %, but by 40 %". He also warned: "In the development of higher education institutions as well as in the infrastructure, Thuringia is lagging behind in what is necessary with all creditable performances. Let me add: Germany urgently needs a higher education tax law to stop a large number of bureaucratic and fiscal absurdities. The energy expended in these should instead be focused on the process of science and teaching. The overriding vision is that higher education policy is the policy of the future."

Then he handed over the chain of office as a symbol of responsibility to Prof. Rosenthal. He put on the gown as "expression of respect of the history of this University, its tradition and its autonomy". In his inaugural address he presented the leading team, apart from the chancellor Dr. Klaus Bartholmé, the new vice president Prof. Dr. Iris Winkler and the vice presidents Prof. Dr. Thorsten Heinzel and Prof. Dr. Uwe Cantner. At the same time he explained his vision of his office and task and his principal goals. In his speech, entitled "Education for Freedom", he thanked his predecessor and emphasised: "The Friedrich Schiller University is well positioned and I am not arriving in Jena with a definite implementation concept in my luggage. I don't think developing concepts for the future is a task only confined to the president and the chair, but it concerns the whole community of the University." His goals which he will be working towards - or which he will preserve - can be summarised in six sentences:
The University has to have a conception of itself as a place of freedom.
The University embraces its responsibility for our society.
The Friedrich Schiller University is committed to the excellence in research and teaching.
The Friedrich Schiller University takes on the national and international competition.
The Friedrich Schiller University is the motor of a region of science and economy.
The Friedrich Schiller University needs adequate financial funding.

Finally he stressed the added value the Universities bring to the state and said: "Our University needs the diversity of disciplines." With this he invited all members of the University to join forces and embark on interdisciplinary discourse and the development of a profile. A recording of the complete investiture can be found at http://www.db-thueringen.de/servlets/DocumentServlet?id=24722 , fotografic impressions at: http://www.uni-jena.de/Investitur.html.

The piece of Jena TV about the investiture is online at: http://www.jenatv.de/wissenschaft/Amtswechsel:_Der_Mediziner_Prof_Dr_Walter_Rosenthal_ist_der_erste_Praesident_der_Jenaer_Universitaet-24517.html
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Speed at its limits

Physicists at the University of Jena together with colleagues from Imperial College London develop ultra-fast semiconductor nano-lasers

One thousand billion operations per second - this peak value is achieved by semiconductor nano-lasers developed by physicists at the University of Jena together with their colleagues from Imperial College London. As the researcher report in the current issue of the journal of "Nature Physics", they are capable of producing the fastest lasers to date (DOI: 10.1038/NPHYS3103).

The fastest, in this case means the speed at which the laser can be turned on and off and not the length of laser pulse, as Prof. Dr. Carsten Ronning from the University of Jena clarifies. "While the fastest lasers typically need several nanoseconds for one cycle our semiconductor nano-laser only needs less than a picosecond and is therefore a thousand times faster," the solid state physicist continues.#

Roeder_kasper

For their nano lasers the researchers use tiny wires made of zinc oxide. These wires have diameters of a few hundreds of nanometres - around a thousandth of the diameter of human hair - and are about a few micro meters long. Their properties make these nanowires an active laser medium and a resonator at the same time. "Light is being reflected at the ends of the nanowire, similar to a mirror, and is then amplified while propagating through the nanowire," says Robert Röder. The PhD student in Prof. Ronning's team is one of the authors on this current publication.

For the researchers the concept of using nanowires as a laser is not new. However, the new idea in this publication is the possibility to fundamentally modify the speed of these lasers. To this end the physicists combined the semiconductor with a metallic layer, leaving only a 10 nanometre thin gap layer between both in which the light field is constricted. "This is how light-matter interactions are accelerated," says Robert Röder. This is not only "world record" regarding the switching speed. "Most likely we also achieved the maximum possible speed, at which such a semiconductor laser can be operated". Applications for these ultrafast und nanometer small lasers are especially optical transistors and sensors. "Using such tiny sensors single molecules or microbes can be detected in medical diagnostics," emphasizes Prof. Ronning. US

Contact:
Prof. Dr. Carsten Ronning, Robert Röder
Institute for Solid State Physics
Friedrich Schiller University Jena
Helmholtzweg 5, 07743 Jena
Germany
Phone: ++49 3641 / 947300, ++49 3641 / 947318
Email: ,
http://www.nano.uni-jena.de

PhD student Robert Röder from the University of Jena achieved together with colleagues from Imperial College London the maximum possible speed at which a semiconductor laser can be operated (photo: Jan-Peter Kasper/FSU).

 

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