Meetings Schedule and Slides
Common meetings at the Department of Astronomy and
Theoretical Physics, and slides presented in the seminars.
Current location and format are preliminary, to be
replaced when the official webpages of the new Department
7 May 2014, 15.15, in Lundmarksalen
Formation of galactic bars and bulges
Like many other disc galaxies, the Milky Way has a bar and a boxy
bulge in its central parts. I will use N-body simulations to discuss
the formation, evolution and properties of such structures, with
emphasis in our Milky Way bar/bulge region. I will also discuss the
role of the dark matter and of gas in these processes,
and how baryonic and dark matter interact.
5 March 2014, 15.15, in Lundmarksalen
can we understand the strong force?
5 February 2014, 15.15, in Lundmarksalen
of survival data and some nice applications in clinical
13 November 2013, 15.15, in sal F (K404)
explosions from compact binaries
The majority of observed high-energy transient astrophysical events are
associated with massive stars, and these massive stars are in the most part
in binaries: gravitationally bound systems in which two stars orbit their
common centre of mass. Interactions between the two stars can profoundly
change their evolution and lead directly to explosive events such as
gamma-ray bursts. I will briefly review the evolution of single and binary
stars and discuss three examples of binary interactions leading to
high-energy transients: long-duration gamma-ray bursts from black-hole
binaries, short-duration gamma-ray bursts from neutron star-binaries and
calcium-rich explosions from white-dwarf--neutron-star binaries.
23 October 2013, 15.15, in sal F (K404)
protein aggregation - from sticks to atomic representation
2 October 2013, 15.15, in sal F (K404)
Subir Sarkar (Niels Bohr Institute and University of Oxford)
Connecting Inner Space & Outer Space
We have just celebrated the centenary of the finding that
the Earth is constantly bombarded by high energy `cosmic rays'
from outer space. This initiated a glorious era of discovery
of many new elementary particles (positron, muon, pion, ...) and
developed into accelerator-based research in high energy physics.
A century later this has given us the triumphant `Standard Model'
of particle physics which provides a precise quantum description
of all fundamental processes in terrestrial laboratories,
including (with the recent discovery of "a Higgs boson")
an understanding of how particles acquire mass.
Unfortunately the Standard Model does not explain any of the
salient features of the universe as a whole - Why there is matter
but no antimatter? Why there is so much more `dark matter'
of unknown origin? Why is the expansion rate apparently
accelerating, as if driven by a Cosmological Constant-like,
dominant component of `dark energy'? I will describe how new
experiments and theoretical developments at the rapidly growing
interface of astro-particle physics are attempting to answer
these cosmic questions, by linking them to possible new physics
beyond the Standard Model.
10 April 2013, 15.15, in Lundmarksalen
three colours of the strong force
6 March 2013, 15.15, in sal F
Mixing in Galactic Disks
Observations show that radial metallicity gradients in disk galaxies
are relatively shallow, if not flat, especially at large galactocentric
distances and for galaxies in the high-redshift universe. Given that
star formation and metal production are centrally concentrated, this
requires a mechanism to redistribute metals. However, the nature of
this mechanism is poorly understood, let alone quantified. I will
present my first-principle calculations of turbulent mixing driven
by thermal instability, and argue that this is an efficient process
in redistributing metals on large scales. And then I will discuss
the on-going extension of this work to understand the chemical
homogeneity in old star clusters.
6 February 2013, 15.15, in Lundmarksalen
Patterns in Biology
There has been some interest lately in certain mechanisms for pattern
formation in biological tissue, where the dynamics is based not only on
diffusion and local production/deletion, as in conventional reaction-
diffusion models, but also on so called active transport.
Some of the related equations bear relations to Newton's and
Schrödinger's equations, and the dynamics sometimes allow for
quasiperiodic patterns due to the existence of a non-trivial
spatial conservation law.
14 November 2012, 15.15, in Lundmarksalen
Lithium in the Cosmos
17 October 2012, 15.15, in Sal F
The "Higgs" discovery - a portal to new physics
Starting from the experimental discovery of a Higgs-like particle,
I will recapitulate the role of the Higgs boson in the standard model
of particle physics. Then I move on to discuss the implications of
the discovery, and how the detailed properties of the "Higgs" particle
can tell us something about physics beyond the standard model,
such as supersymmetric theories.
19 September 2012, 15.15, in Sal F
Modelling the plant circadian clock
The vast majority of living organisms are exposed to daily cycles
in temperature, sunlight and other environmental factors. The ability
to anticipate these rhythmic changes is highly beneficial: clocks with
a 24-hour period are found in many different lifeforms, including both
animals and plants.
In the plant model organism Arabidopsis thaliana, more than a
dozen genes form the core of the clock. Together they form a complex
network of interactions, with positive and negative feedbacks and many
inputs and outputs. Over the past decade, more and more complete
models clock have been created, typically in the form of ordinary
differential equations, based on a vast number of experiments.
In this talk, I will present the biological background and
building blocks of circadian clocks, and show how the models have been
- and, despite their complexity, are still being - iteratively
improved through feedback between modelling and experimentation.
24 May 2012, 10.00, at the Ecology House
Honorary Doctor's Seminar by Bryan Webber
Improving the precision of high-energy simulation
and analysis tools
18 April 2012, 15.15, in Lundmarksalen
Stellar Clusters: Factories Producing Exotic Objects
14 March 2012, 15.15, in Lundmarksalen
Status of the LHC and Anatomy of LHC Events
22 February 2012, 15.15, in sal F, theoretical physics
Dimitri Argyriou (Director of Science, ESS)
The European Spallation Source: What is it and what
can I do with it !
In this talk I will discuss briefly what is the European Spallation
Source and why it is different from other sources. Apart from
highlighting how neutrons are used in science today, the talk will
also focus on some of the special opportunities that ESS offers.
25 January 2012, 15.15, in sal F, theoretical physics
Erik Lindahl (KTH)
Simulation of Structure & Function of Biological
Biological macromolecules are fascinating machines with highly
complex functional roles determined by their structure, but this
in turn is determined by fairly simple physical interactions. In
principle it is possible to simulate the folding of e.g. a protein
in a computer, but the very high computational complexity has
limited this to small systems even when using special-purpose
hardware. I will discuss how we are trying to address this problem
by using different approaches to computation that originally
came out of our work on the Folding@Home project, and how it
might be possible to model quite complex and general biological
processes with large numbers of simulations running as an ensemble
on extremely large future "exascale" computers, in particular
by using Markov State Models. I will also present how we are
applying these techniques to model functions and drug interactions
for ligand-gated ion channel membrane proteins to illustrate
how current simulations provide concrete functional conclusions
for proteins that complement and guide other experimental methods.
7 December 2011, 15.15, at Lundmarksalen
The chemical history of the Galactic bulge and disk
16 November 2011, 15.15, at Lundmarksalen
The Physical Vacuum: Where Particle Physics Meets
The Nobel Prize in Physics this year has been awarded "for the
discovery of the accelerating expansion of the Universe through
observations of distant supernovae". Such a fundamental discovery
together with up-to-date results from the Large Hadron Collider
poses even more fundamental questions to our understanding of the
structure of the Physical Vacuum, both at micro and macro scales.
Many diverse unsolved problems ranging from e.g. the Supersymmetry
breaking mechanism giving a natural candidate for the Dark Matter,
the Higgs issue in the Standard Model and the confinement issue in
the Quantum Chromodynamics up to the Dark Energy issue leading to
observable acceleration of the Universe originate from poorly
understood structure of the Physical Vacuum. In this talk, I make an
attempt to review this very complicated problem from different
perspectives, as well as to go through major current and possible
theoretical developments at frontiers of Particle Physics and
2 November 2011, 15.00 (note time!), at Lundmarksalen
Monte Carlo simulation of proteins: from folding to
"nonfolding" to interactions
4 May 2011, 15.15, in sal F, theoretical physics
Sven-Erik Strand and Freddy Ståhlberg
Imaging possibilities at Lund University BioImaging Center
2 February 2011, 15.15, at Lundmarksalen
The physics of musical instruments
Why does a clarinet sound one octave lower than an oboe or a saxophone
of the same length, and why is the first overtone missing in the clarinet?
Why should you not hit a drum in the center?
What is the motion of a violin string?
Why can you have finger holes in a flute but not in a trumpet?
These are some of the questions to be discussed in the talk.
8 December 2010, 15.15, at sal F
The art of moving when you are stuck - from Darwins'
research on plants to state of the art methods for resolving the
underlying mechanisms of multicellular life
The differentiation of stem cells into different cell types and the
possibility of guiding cells back to stem cells are currently
attracting much attention within developmental biology and medical
research. Plants, unable to move around, rely on an ability to respond
to the environment and continue the production of organs throughout
their lives. Hence they have developed the competence to regulate stem
cells and growth depending on intrinsic and external signals. I will
discuss our research on combining mathematical models and live imaging
techniques to gain insights in the mechanisms regulating multicellular
development. I will show that a combination of gene regulation,
hormone signaling, and mechanical stresses are important for
17 November 2010, 15.15, at Lundmarksalen
How migrating geese and falling pens inspire
Planets form in gaseous discs around young stars as tiny dust grains collide to
form larger and larger bodies. This paradigm however faces major problems as
particles reach cm sizes, as macroscopic bodies are more prone to bouncing and
shattering than to sticking. I will talk about my computational work on
explaining the formation of km-sized planetesimals from cm-sized pebbles.
Particles fall at their terminal velocity towards the point of highest
pressure, like objects on earth falling to the floor. High-pressure regions in
circumstellar discs collect particles this way. An aerodynamical streaming
instability causes particles to clump further, analogous to how migrating geese
and bicycle riders travel in groups to reduce their common air resistance. The
local particle density can become high enough to initiate a gravitational
collapse of the pebble component. This planet formation picture has widespread
implications for observations of exoplanets and for explaining why the solar
system formed when it did.
3 November 2010, 15.15, at sal F
Joakim Edsjö (Stockholm University)
Dark matter searches in the sky and underground
Finding the dark matter in the Universe is one of the big questions in
science today. I will here go through various ways to search for dark
matter and discuss the current status both from a particle physics and
astrophysics point of view. I will also discuss future searches that
will take place in the near future.
20 October 2010, 15.15, at Lundmarksalen
Near field cosmology, now and in the Gaia era
I will review the current status of the field often
referred to as near field cosmology, i.e. the study of cosmologically
interesting process but in the local volume. In particular I will
focus on our understanding of the Milky Way as a galaxy and how it
constrains the cosmological models. The advent of Gaia will radically
change the impact of near field cosmology on cosmology in general.
9 June 2010, 15.15 at sal F
Zoran Konkoli (Department of Microtechnology and Nanoscience - MC2,
Chalmers University of Technology, Sweden)
Computational modeling of the living cell biochemistry:
What statistical physicists are not but should do
The talk will discuss how Statistical Physics tools
can be used to understand biochemistry of the living cell. Structures
found in the living cell are rather special and to achieve such task
tchniques used in the field of Statistical Physics need to be slightly
modified. A critical reflection is needed on which techniques to use and
for what purpose. As an example the theory of diffusion controlled
reactions will be reviewed with a purpose of using it for understanding
spatio-temporal organization of the living cell.
It will be argued that formalism of diffusion controlled reactions is a
suitable framework for describing living cell and the scope and the
limitations of such approach will be discussed. Informal discussion will
be given around problems (and possible traps) one meets when trying to
compute properties of biochemical reactions in the cell interior. For
example, assumption of perfect mixing is frequently used for modeling.
However, large number of processes in the cell exists to battle precisely
lack of perfect mixing. Few selected issues related to validity of mean
field equations (perfect mixing) in describing intracellular kinetics will
The last part of the talk will cover more applied topics. It will be
shown how framework of diffusion controlled reactions (and Markov chains)
can be used to analyze spatio-temporal organization of the living cell.
A platform for doing such analysis, Geometry-Reaction InterPlay (GRIP),
will be presented. If the time allows some issues related to complex
noise formation will be discussed.
26 May 2010, 15.15 at sal F
Boson Interferometry: From astronomy to particle physics,
28 April 2010, 14.15 at Lundmarksalen
(double feature, early start!)
14 April 2010, 15.15 at sal F
Hadrons, Flavours and Effective Theories
17 March 2010, 15.15 at Lundmarksalen
Black holes and cosmic explosions
Stellar mass black holes are the end product of massive stars.
Their formation may be accompanied by spectacular events such as
supernovae and gamma-ray bursts. In this presentation I will
briefly outline this connection and show how observational
results from studies of black holes in binary systems can be used
to probe their formation.
3 March 2010, 14.15 at sal F (double lecture, early start!)
Bengt E Y Svensson
ACCELERATED COSMIC EXPANSION: Observations, theoretical ideas
I will review the present understanding of the accelerated expansion
of the universe, the "dark energy" enigma, observationally
discovered about a decade ago and still without a satisfactory explanation.
To try to get everyone on-board, I will start with a "crash
course" in cosmology by presenting all the basics needed (so if you are
unfamiliar with the topic, you will have a cheap chance to get updated!)
After giving a brief summary of the relevant observational data, I will
then dwell on some of the theoretical ideas that have been put forward
to explain the phenomenon.
17 February 2010, 15.15 at Lundmarksalen
The physics of subcellular processes
3 February 2010, 15.15 at sal F
Gaia: A brief overview of the ESA space astrometry project