Issue 1, 2014
Issue 4, 2012
Lucia Night (13 December) outside the Nordita buildings
With shock and disbelief we have learned that Professor Dmitri Diakonov
passed away on December 26, 2012.
Dmitri was Professor at Nordita in Copenhagen from 1997 to 2005. He was a great colleague to many of us, with deep insight into many aspects of physics, and always ready to help and explain complicated connections in simple and meaningful terms.
Dmitri's research made headlines in the early and mid 2000s, when several experiments claimed to reveal pentaquark states. In particular, a resonance with a mass of 1,540 MeV/c2 was reported by LEPS in 2003. This coincided with a pentaquark state with a mass of 1,530 MeV/c2 predicted in 1997 by Dmitri Diakonov, Victor Petrov, and Maxim Polyakov (Zeitschr. Phys. A359, 305). This was followed by a number of experiments at different installations worldwide, and hundreds of theoretical papers. Dmitri's contribution stimulated a lot of activity in the study of hadron resonances and in the search of new ones. It caused certain long-standing prejudices in the theory of strong interactions to be questioned even if later experiments and re-analysis of the data showed the presumed pentaquark states to be statistical effects rather than true resonances.
Dmitry received several prestigious awards, including the von Humboldt Research Award for "outstanding achievements in the field of theoretical physics" in 1992, a Royal Danish Academy of Sciences award, in association with the Carlsberg Foundation, of free residence at the "Academy Villa" in 1997-2002, where Niels Bohr lived, the Governor's of St. Petersburg region Research Award in 2009, and the Mercator Professorship of the DFG at Ruhr-University Bochum (Germany) during 2008-2010.
For further details about Dmitri Diakonov see www.ae-info.org/ae/User/Diakonov_Dmitri. About the current status of the pentaquark see en.wikipedia.org/wiki/Pentaquark.
The visiting PhD student program at Nordita is open for applications for visits during spring and summer 2013. The program offers selected students the opportunity to spend time at Nordita and take advantage of the research environment and ongoing scientific activities at the institute and the AlbaNova University Center in Stockholm. This can, in particular, include collaboration on research projects with Nordita academic staff and participation in Nordita Scientific Programs in areas of interest for the students. Visiting PhD fellows may also be interested in taking PhD-level courses offered at Stockholm area universities.
A Visiting PhD Fellowship will be awarded for a period of one to three months, providing accommodation and a contribution towards travel and living expenses in Stockholm. Priority will be given to applicants who are registered PhD students in theoretical physics or a related subject at a university in the Nordic countries at the time of the fellowship visit to Nordita, but students from other countries will also be considered.
Ebru Devlen
Astrophysics
Ebru Devlen did her PhD in 2008 on "The Magnetorotational Instability in Accretion Disks" and is now a Research Assistant at the Department of Astronomy and Space Science at the University of Ege in Turkey. She received a grant from the Scientific & Technological Research Council of Turkey (TÜBITAK) to work at Nordita for a year. She has been working on the influence of plasma diamagnetism on the magnetorotational instability in accretion discs and on anisotropic transport effects in dilute plasmas. Since her arrival at Nordita she has focused on turbulent transport effects and discovered that the dynamo effect from a particular flow field (the Roberts-IV flow) acts as a mean field dynamo owing to negative eddy diffusivity; for details, see xxx.lanl.gov/abs/1212.2626.
Francesco Mancarella
Condensed Matter, Statistical Physics and Biophysics
Francesco Mancarella received his PhD in physics in 2012 from SISSA, where he investigated thermodynamical features of a family of non-Abelian anyonic systems. Some homological properties of the Chern-Simons theory defined over non-trivial topological 3-manifolds had been his main research interest in the past. His current project is instead about magnetic properties of 2D high-temperature superconductors of nanoscopic scale. On a completely different side, he is dealing with transmission properties of density waves produced in 1D Bose-Einstein condensates which are described in the Gross-Pitaevskii approximation.
Sarah Jabbari
Astrophysics
Sarah Jabbari started her PhD in September 2012 in the astrophysics group at Nordita and the Department of Astronomy at Stockholm University under the supervision of Axel Brandenburg. She arrived from Zanjan University in Iran where she worked on magnetohydrodynamic waves in curved and low plasma-beta solar coronal loops. The topic of her PhD thesis is the "Origin of solar surface activity and sunspots". Her position is funded jointly by the Astronomy Department at Stockholm University and a research grant from the Swedish Research Council with Axel Brandenburg as PI. She is doing simulations with the Pencil Code on solar activity and the origin of sunspots. She is working on theories which try to explain the formation of sunspots as a shallow phenomenon. She is also interested in helioseismic signature of flux concentration at solar surface.
Atefeh Barekat
Astrophysics
Atefeh Barekat is a master student at the Astronomy Department at Stockholm University. She started her master thesis in November on a "Radiative mean-field model of convection in and around a sunspot" under the supervision of Axel Brandenburg. In particular, using the Pencil Code, she is modeling the local suppression of the convective heat flux by the magnetic field, which is expected to lead to local cooling, local contraction, and thereby further field amplification. She is including fully nonlocal radiation transport along rays permeating the domain at a number of different angles. The idea is that this process can amplify the magnetic field beyond the level that is possible through the negative magnetic pressure instability mentioned in Newsletter 2011/3. This might therefore explain the formation of sunspots within so-called active regions.
Visiting postdoc Kjartan Thor Wikfeldt
Condensed Matter, Statistical Physics and Biophysics
Thor Wikfeldt received his PhD in physics from Stockholm University in 2011. His main research focus was on elucidating structural, thermodynamic and dynamic properties of liquid water by means of molecular-scale computer simulations based on both empirical force fields and first-principles electronic structure methods. After his PhD Thor spent 1 year at University College London investigating nuclear quantum effects, such as quantum tunneling and zero-point delocalization, in hydrogen-bonded ferroelectric crystals and in hydrogen atom surface-diffusion using Feynman path-integral simulation methods. Currently Thor is working jointly at Nordita and at the University of Iceland where he is continuing his research on water and other hydrogen-containing systems.
Visiting postdoc Steven Lade
Condensed Matter, Statistical Physics and Biophysics
Steven Lade has a postdoc position at the Stockholm Resilience Centre (in Stockholm University) as well as a visiting postdoc affiliation with NORDITA. At the SRC, Steven is researching feedbacks in social-ecological systems and their effects on the resilience of these systems. Previously, Steven has worked on interdisciplinary projects in molecular biology (molecular motors, ratchets, and protein aggregation), ecology (early warning signals) and psychology (bifurcations in intertemporal choice experiments) during his PhD in physics at the Australian National University and a postdoc at the Max Planck Institute for the Physics of Complex Systems.
Visiting postdoc Konstantin Zakharchenko
Condensed Matter, Statistical Physics and Biophysics
We wish all of them good fortune and success in their future careers.
In continuation of the ERC-supported research on Astrophysical
Dynamos at Nordita (see www.nordita.org/astrodyn),
there will be post-doc positions in local helioseismology and the
formation of active regions and sunspots, supported through the Swedish
Research Council through a special grant for break-through research. The
successful candidates will be working on forward modeling to infer seismic
signatures from magnetic flux concentrations beneath the solar surface
and on numerical models of radiation magnetohydrodynamics to explain the
spontaneous formation of active regions and ultimately sunspots.
Senior members of the Nordita dynamo group include Dhrubaditya Mitra, Matthias Rheinhardt, and Axel Brandenburg. Close ties exist also with Göran Scharmer and his group at the Institute for Solar Physics.
For further details; see jobregister.aas.org/job_view?JobID=44103.
Sabine Hossenfelder
won the Third Prize in the 2012 Questioning the Foundations essay contest. Her essay "Gravity can be neither classical nor quantized" contemplates the possibility that gravity, at the fundamental level, is neither classical nor quantized, which is achieved by allowing the Planck constant to vary in time and space.
As part of the ERC-supported AstroDyn project, three PhD students started their work in February 2009. They were all enrolled at the Astronomy Department, defended their Licentiate dissertations in 2011, and have now completed their PhD studies. They were the first PhD students to begin and complete their work at Nordita in its new environment in Stockholm.
Koen Kemel, "From mean-field hydromagnetics to solar magnetic flux concentrations"
26 October 2012
Opponent: Alexander Ruzmaikin (Jet Propulsion Laboratory, California Institute of Technology)
One of the main results of Koen's thesis is the numerical demonstration of the so-called negative effective magnetic pressure effect. In a strongly stratified layers, it can lead to the spontaneous formation of magnetic flux concentrations. This effect was first anticipated in the late 1980s by Nathan Kleeorin, a student of Alexander Ruzmaikin. We had the great honor to have Professor Ruzmaikin as the opponent of a thesis that demonstrated, for the first time in direct numerical simulations, the validity of an effect that even Ruzmaikin himself had a hard time believing at the time! Altogether, Koen's thesis includes 8 papers. He is the lead author on 5 of them. The examination committee consisted of Elisabeth Rachlew (KTH), Oleg Kochukhov (Uppsala University), and Anders Johansen (Lund University).
Fabio Del Sordo, "From irrotational flows to turbulent dynamos"
14 November 2012
Opponent: Mordecai-Mark Mac Low (Department of Astrophysics and American Museum of Natural History)
Fabio's thesis deals with the generation of magnetic fields in galactic discs, in which turbulence is generated through expanding shock waves from supernova explosions. One important result was a quantitative estimate of the amount of vorticity that can be generated from rotation, shear, and the departures of perfect alignment of pressure and density gradients. He also showed that magnetic field generation proceeds owing to shedding small-scale magnetic helicity fluxes. His work showed for the first time that the magnetic helicity flux divergence becomes asymptotically independent of the magnetic Reynolds number. Altogether, Fabio's thesis includes 7 papers. He is the lead author on 3 of them. The examination committee consisted of Maria Sundin (Gothenburg University), Vladimir Pavlenko (Uppsala University), and Gunnlaugur Björnsson (University of Iceland).
Simon Candelaresi, "Magnetic helicity in astrophysical dynamos"
7 December 2012
Opponent: Renzo Ricca (University of Milano-Bicocca)
Simon's thesis also deals with magnetic helicity and demonstrates its important role in characterizing the decay speed of complicated magnetic flux topologies. Even flux configurations with initially zero magnetic helicity can develop nontrivial behavior by producing spatially separated regions with opposite magnetic helicity. His work also confirmed an early result that the amount of kinetic helicity needed to drive large-scale dynamo action is inversely proportional to the scale separation ratio to the first power, and not, as has been claimed in a recent paper, to the third power. Altogether, Simon's thesis includes 6 papers. He is the lead author on 3 of them. The examination committee consisted of Mattias Marklund (Umeå), Cathy Horellou (Chalmers), and Geert Brethouwer (KTH).
Roughly every second year all the physics and astronomy departments at AlbaNova University Center and the House of Science - and since 2007 also Nordita - have an open house for the general public, who are treated with popular lectures, hands-on experiments and guided tours of the physics labs and the telescope. This year the Open House took place on October 20.
Nordita contributed to this popular event with several physics presentations in our seminar room, an opportunity to give visitors a (photographic) scientific background using green-screen techniques, a viewing of the documentary of the Galileo Mobile outreach project of which Nordita is a proud sponsor, and a presentation of the Sweden Solar System artistic-scientific outreach project (within which Nordita is currently lobbying to get the model of Venus placed at AlbaNova).
An interview with Nordita assistant professor Sabine Hossenfelder appeared in issue 2012-4 of the Swedish popular astronomy journal . In the article "Vetenskapen slår tillbaka" ("Science Strikes Back") Sabine and science journalist Anna Davour discuss the search for quantum gravity, science blogging and living a life as a research nomad.
Nordita visitor Lars Samuelsson was involved in a headline making paper in PRL
together with Kostas Glampedakis and David Jones; see
prl.aps.org/abstract/PRL/v109/i8/e081103.
They show that gravitational radiation from hypothetic color-magnetic
mountains in young pulsars could provide a probe of paired quark matter in
neutron stars.
In www.bbc.com/future/story/20120831-written-in-the-stars/1, BBC Future therefore asks whether gravitational waves could be written in the stars.
During October 15-17, Nordita had the pleasure of hosting this year's annual meeting of the European Astrobiology Network Association (EANA, www.astrobiologia.pl/eana). This 12th workshop was co-sponsored by the Swedish Research Council, the Swedish National Space Board, the Stockholm University Astrobiology Centre, and the City of Stockholm and the European Space Agency ESA. 28 travel grants were awarded by EANA to students and young scientists.
The workshop included oral presentations, poster sessions with moderated discussions, as well as a student contest under the theme "The Space Factor". A panel was devoted to Pan-European projects in astrobiology. About 160 scientists attended EANA'12; for details see the programme and the book of abstracts on www.nordita.org/eana2012.
The Editor-in-Chief of Origins of Life and Evolution of Biospheres has agreed to publish a special issue with some of the new research presented at the EANA'2012 Workshop. Axel Brandenburg and Nils Holm (Department of Geological Sciences) will act as guest editors.
The next EANA workshop EANA'13 will be held in Szczecin,
Poland, on July 22-25, 2013.
Photo: Fabio Del Sordo
Program
21 January — 15 February 2013
Coordinators: Jonas Larson, Emil Lundh, Jani-Petri Martikainen, Chris Pethick, Päivi Törmä
During the last years, numerous achievements have been presented in the research with cold atoms, such as realizations of; various lattice models, synthetic gauge fields, orbital physics, disordered systems, non-equilibrium dynamics, dipolar gases, and many-body cavity QED. This program will gather both experamentalists and theoriticians for discussions and presentations of these topics as well as others.
Program
4—15 March 2013
Coordinators: Ralf Eichhorn, Erik Aurell
Stochastic Thermodynamics represents an exciting new research direction in statistical physics, which explores fundamental aspects of non-equilibrium processes. The developments summarized under this term may be characterized by the common idea to adapt and generalize concepts from equilibrium thermodynamics to the non-equilibrium realm, typically on the level of single particle trajectories monitored over the entire system evolution.
Program
8 April — 3 May 2013
Coordinators: Maarit Mantere, Petri Käpylä, Rainer Arlt
The goal of the programme is to advance our understanding of the physical processes generating differential rotation in various types of stars, and the role that this effect plays for stellar magnetic activity and dynamos. The Sun is the only star for which the internal rotation profile is observationally known thanks to helioseismology ? for other stars, only the surface differential rotation can be inferred from photometric or spectroscopic observations. The main goal of the program is to investigate the connection between the theories and observations and obtain better understanding of the generation and role of differential rotation for stellar magnetism.
School
7—18 January 2013
Coordinators: Axel Brandenburg, Claes Fransson, Juri Poutanen, Lárus Thorlacius, Stephan Rosswog, Josefin Larsson
The purpose of this winter school is to provide PhD students and young postdocs in the Nordic countries with introductory courses in a range of the most important topics in the field of astrophysics. The school will provide a way to bring together students and young postdocs across different fields, research institutions and countries.
Workshop
20—22 March 2013
Coordinators: Ralf Eichhorn, Alberto Imparato
This workshop provides a forum where scientists in the Nordic countries working in the area of Statistical Physics can meet regularly. The workshop series brings together experts interested in the broad spectrum of timely problems in (classical) Statistical Physics, ranging from fundamental aspects in the theory of non-equilibrium processes to modern applications in biophysics.
→ Link to electronic preprints: www.nordita.org/preprints
The following preprints have been posted to the Nordita on-line archive since the last newsletter issue:
If you have information about meetings or other items that would be useful to include in Nordita News, please send it to Anne Jifält, Nordita, email: anne@kth.se.
For back issues of the Nordita newsletter, see www.nordita.org/news/nordita_news/available_issues.