The role of wetlands, and especially peatlands, in biosphere processes and global ecological stability involves several global and regional mechanisms, which so-far have not been adequately synthesized and linked to Earth system science. In my lecture, I will argue that wetland ecosystems, especially peatlands, have been critically important to several major transformations in Earth's history and remain key mechanisms of the planetary homeostasis. I will present arguments that the evolution of this homeostasis, involving the interplay of feedbacks between the Earth's biotic and physical systems, as originally proposed by Lovelock and Margulis (1974), would not have been possible without the numerous processes occurring in wetlands, including the burial of organic carbon (responsible for the removal of atmospheric CO2 and the long-term increase in O2), the regulation of nitrogen and other nutrient cycling in landscapes and ‘riverscapes’, the maintenance of regional water cycling and hydrological regimes, the protection of permafrost in discontinuous permafrost zones, and several other processes. At the same time, these ecosystems, when disturbed, can shift to destabilizing functions, such as the rapid release of greenhouse gases (CO2 and methane [CH4]), nutrient emissions to surface waters, loss of water-holding capacity and catastrophic decline in biodiversity. Therefore, the protection of remaining mires and rewetting of drained peatlands is necessary in sustainable climate policies (mitigation and adaptation). Peatlands should also be key elements in predictions of the future developments of Earth system, including in post-apocalyptic scenarios following catastrophic climate change and hothouse Earth (their enormous potential of cooling and stabilising climate can be instrumental in long-term recovery).
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Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:00
dr hab. Beata Brzozowska (Wydział Fizyki UW)
DNA is the fundamental molecule encoding and storing the genetic information of all living organisms. DNA damage and repair is by essence a multidisciplinary line of research, and it is one of the main topics of medical physics studies performed in Radiobiological Laboratory at Faculty of Physics, University of Warsaw. The genetic material is a labile substance that is constantly damaged either spontaneously or due to the action of DNA damaging agents like ionising radiation.
During colloquium I will discuss the results of experiments performed with cells exposed to radiations, which differ in the way how interactions are distributed inside a nucleus. While X-rays are sparsely ionizing, alpha particles hit cells in a highly condensed manner, as single tracks. A combined exposure places the cell in a particularly difficult situation of experiencing both hit scenarios which leads to the formation of clustered damage posing serious problems for the DNA repair machinery.
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Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:00
dr hab. Andrzej Hennel, prof. UW The lecture will be devoted to the ``forgotten" eighth Polish Nobel Prizewinner.
Józef Rotblat was born in 1908 in Warsaw, and in 1938 he received a PhD inphysics from the Faculty of Mathematics and Natural Sciences of the University of Warsaw. From 1939 he worked at the University of Liverpool, and in 1944 at the Los Alamos laboratory. In 1946 he became a British citizen and from 1949 he was a professor of physics at St Bartholomew's Hospital in London. He was a signatory of the Einstein-Russel Manifesto in 1955 and co-founder of the Pugwash Conference on Science and World Problems. In the years 1957-1973 he was the Secretary General of Pugwash, and in the years 1988-1997 its President. In 1995, they received the Nobel Peace Prize jointly - Pugwash (50%) and Józef Rotblat (50%). He died in London in 2005.
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Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:00
prof. dr hab. Tomasz Dietl (International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Warsaw, Poland)
In 2019, four of the seven SI base units specified in the International System of Quantities were redefined in terms of natural physical constants rather than human artifacts such as the standard kilogram. In particular, the kilogram and ampere are now defined by setting exact numerical values for the Planck constant h and the elementary electric charge e. That redefinition was prompted by the existence of the Josephson and quantum Hall effects, making us possible to connect directly quantum fundamental constants h and e to the lab practice. In the talk, I will present recent progress in fabricating resistance quantum Hall standards working in magnetic fields low enough to allow for integration with superconducting Josephson junctions that constitute the voltage standard. Such an integrated device establishes the ampere standard and the kilogram standard via the Kibble balance. I will emphasize the role of dilute magnetic semiconductors and our experimental [1] and theoretical [2] contributions to the field of quantum Hall resistance standards.
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Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:00
dr hab. Katarzyna Krajewska, prof. UW, dr hab. Piotr Wasylczyk, prof. UW (Faculty of Physics, University of Warsaw)
This year, the Nobel Prize in Physics was awarded to Pierre Agostini, Anne L’Huillier, and Ferenc Krausz for their groundbreaking research leading to the development of experimental methods for generating attosecond pulses of light. These unprecedentedly short bursts of electromagnetic fields have become the foundation of new spectroscopic techniques with the highest temporal resolution and enabled scientists to take snapshots of electron dynamics in matter. In this lecture, we will describe the experimental methods behind the creation and metrology of such pulses and present examples of using attosecond techniques to capture ultrafast processes in atoms, molecules, and solids.
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Pobierz slajdy (prof. K. Krajewska) / Download the slides (prof. K. Krajewska)
Pobierz slajdy (prof. P. Wasylczyk) / Download the slides (prof. P. Wasylczyk)
Obejrzyj nagranie / Watch the video
Zapraszamy do sali 0.06, ul. Pasteura 5 o godzinie 11:00
Prof. dr hab. Stefan Pokorski (Wydział Fizyki UW)