Physics Friday Colloquia

– Autumn 2016

Department of Physics organizes a series of colloquia. Friday's colloquium is open to everyone. If you desire coffee/tea and something sweet, please meet up at 14:00 in the lunchroom D5-175.

Time: Friday at 14:15 - 15:00

Location: Realfagbygget R10

Friday colloquia Autumn 2016

December 2

Asle Sudbø, Department of Physics, NTNU
About the field that got the physics Nobel prize this year

December 2

Asle Sudbø, Department of Physics, NTNU
About the field that got the physics Nobel prize this year

Abstract

About the field that got the physics Nobel prize this year

The Nobel Prize in Physics 2016  was awarded to Fredrick Duncan Michael Haldane, Princeton University (1/4), John Michael Kosterlitz, Brown University (1/4), and David James Thouless, University of Washington (1/2), "for theoretical discoveries of topological phase transitions and topological phases of matter".

In this colloqium, I will explain in simple terms which fundamental ideas underpin this work, and why they are important.

Mon, 28 Nov 2016 13:07:16 +0100

November 18

Dmitriy Anistratov, North Carolina State University​
«Surprisingly Useful Equation: Boltzmann Equation»

November 18

Dmitriy Anistratov, North Carolina State University​
«Surprisingly Useful Equation: Boltzmann Equation»

Abstract

Surprisingly Useful Equation: Boltzmann Equation

Particles are everywhere. There are bunch of them around us. Some of them move freely and collide. The particles influence our world and affect our lives. The photons born in the Sun travel to the Earth, penetrate the atmosphere and make weather. We design machines that use their talents. We need particle energy to get light. They can help doctors to treat people and look inside of a human body. We want to predict weather and control behavior of the machines we build. We need accurate models that describe the complicated and beautiful world with particles starting from their microscopic level up to our macroscopic scale. Boltzmann formulated the equation that can help to make this happen. The Boltzmann equation describes statistical properties of an ensemble of particles and shows evolution of the particle density function. The moments of this function connect the parts of the world at different scales. We can use the Boltzmann equation to model interaction of particles with matter in a variety of physical systems. It works for particles in plasmas, nuclear reactors, semiconductors, etc. Scientists and engineers need this equation. This talk will present what everyone should know about the Boltzmann equation. It will give an introduction in its different applications and describe the main challenges of particle transport simulations.

Tue, 15 Nov 2016 14:07:37 +0100

October 21

Pål Gunnar Ellingsen​, The University Centre in Svalbard
«Aurora Borealis - A natural wonder»

October 21

Pål Gunnar Ellingsen​, The University Centre in Svalbard
«Aurora Borealis - A natural wonder»

Abstract

Aurora Borealis - A natural wonder

The Aurora Borealis has been surrounded by mystery throughout human history, and is still a fascinating physical phenomena today. It was not before the 1900s that we started understanding the underlying physics.  Being a phenomena so closely related to what happens on the Sun, it is one way of indirectly studying the Sun-Earth interaction. We have understood the general processes that generate the aurora, but we are still studying its finer details and how the magnetosphere around our earth reacts to changes in the solar wind. In addition, the increased reliability on electronics and communication requires us to understand the electric and magnetic disturbances generated by it.

This lecture will give an introduction to the mechanisms behind the aurora and the tools used to study these processes, as well as some results.

Wed, 19 Oct 2016 15:04:22 +0200

September 30

Magnus Ullner, Theoretical Chemistry, Lund University
«Polyelectrolytes - The Minefield»

September 30

Magnus Ullner, Theoretical Chemistry, Lund University
«Polyelectrolytes - The Minefield»

Abstract

Polyelectrolytes - The Minefield

Flexible polyelectrolytes can be described as highly charged polymers. It is therefore tempting to reuse the the concepts and theories that have successfully described neutral polymers and just add electrostatic interactions. However, the long-ranged nature of the electrostatic interactions and the presence of counterions break some of the underlying assumptions. Electrostatic persistence length and osmotic pressure are two areas where uncritical application of "common knowledge" has led to both unnecessary controversy and false consensus. Becoming aware of these pitfalls is the first step towards a proper understanding of polyelectrolytes in their own right and Monte Carlo simulation is one of important tools that allow us to peek behind the curtain.

Wed, 19 Oct 2016 15:05:03 +0200

August 26

August 26

This colloquium will be at a slightly unusual time and place: 

Time and place: 12:15 in the lunch room D5-175

Abstract

Prions and amyloids: self-replicating protein pathogens

Recently the prion disease Chronic Wasting Disease was unexpectedly discovered in Norway in reindeer and moose.

Prion diseases are lethal, infectious diseases associated with prion protein (PrP) misfolding. A large number of mammals are susceptible to both sporadic and acquired prion diseases. Prion diseases diseases are infectious. Transmissibility of prions occur through seeded conversion of endogenous normal PrP to misfolded PrP. The process is reminescent of the progression of amyloidosis of which 30 proteins are linked in diverse diseases.

Transmissibility is surprisingly efficient in prion diseases and given the rapid disease progression following initial symptoms the prionoses stand out from other amyloidoses. Several amyloidoses likewise appear to be transmissible under certain circumstances, especially in experimental settings, but with a much slower disease course. In vitro the prion replication process can be mimicked using synthetic PrP. Seeded conversion of various PrP sequences display significantly decreased lag phases demonstrating that nucleation dependent polymerization is a dominating mechanism in the fibrillation process. Different conformational states of PrP within prions appear to dictate the disease phenotype. A major question is what makes a certain prion transmissible and what makes it neurotoxic?

Wed, 19 Oct 2016 15:05:47 +0200