Monthly Archives:   April 2016

Understanding fundamental particles in strong magnetic fields
        
22
  22 April, 2016
        


When the universe was created, strong magnetic fields existed. The same type of magnetic fields can be created in experiments when heavy ions are made to collide. We study how elementary particles behave in these fields. The theoretical understanding of this is important in order to explain the experiments as well the history of the universe.

Elementary particles, such as protons, neutrons, and pions are composed of different types of quarks and anti-quarks. For example, a proton is composed of two u-quarks and one d-quark, while a pion is built out of a u-quark and an anti d-quark.(see Figure 1). Elementary particles that consist of quarks and/or antiquarks are called hadrons.

protons

Figure 1: Protons are composed of three quarks (left) and pions are built out of a quark and an antiquark

Extreme temperatures
When a hadron gas is heated to extreme temperatures, the hadrons “melt”. This means that the quarks and antiquarks are no longer bound together, but can move freely around. This is called
a phase transition from the hadronic phase to a so-called quark-gluon plasma phase.
The temperature required for this phase transition is approximately 4 trillion degrees Celsius, which is many orders of magnitude higher than the temperature in the core of the Sun, which
approximately 15 million degrees Celsius.

Temperature drop after the Big Bang
The opposite of the melting process mentioned above, took place shortly after the Big Bang.
Immediately after the Big Bang, the temperature was so high that a quark-gluon
plasma existed. As the universe expanded, the temperature dropped rapidly, and approximately 10 microseconds after the Big Bang it was so “cold” that hadrons were formed.
This is schematically illustrated in Figure 2.

Heavy-ion collision experiments at CERN
A quark-gluon plasma can be created in the lab by colliding two heavy ions, for example
gold or lead ions. This kind of experiments are carried out at the Large Hadron Collider at CERN, Geneva. The energy of the particles in these experiments is so high that the associated temperature created in the collision is sufficient for the hadrons to melt (see Figure 2).

quark-gluon-plasma

Figure 2. Quark-gluon plasma in the early universe and heavy-ion collisions

It is known that very strong magnetic field existed in the early universe. Strong magnetic fields are also created in some of the heavy-ion collision experiments. The theoretical understanding of how hadrons behave in these fields, is therefore important in order to explain the experiment as well the history of the universe.

Elementary particles in strong magnetic fields
In a recently published paper, we have discussed in detail the properties of elementary particles in strong magnetic fields at temperatures in the vicinity of the phase transition. The material that we have covered includes the contributions from a large number of authors. It also includes the PhD work of William Naylor in collaboration with Anders Tranberg (UiS) and Jens O. Andersen.
 
This new knowledge is a step of the way towards understanding what happened in the early universe.

Figure 3: The melting temperature for a gas of pions as a function of the magnetic field measured in units of the pion mass

Figure 3: The melting temperature for a gas of pions as a function of the magnetic field measured in units of the pion mass

Figure 3 shows how the melting temperature of a pion gas varies with the temperature. In this model calculation, the melting temperature increases as the magnetic fields grows. The green curve corresponds to massless pions while the blue curve corresponds to pions with the mass found in nature.

 

Seriously, you caught an eagle?
        
20
  20 April, 2016
        


mari-eagle-1

One of the perks of being a biologist, is to pet a wild eagle. Photo: Igor Eulaers

 
When I try to explain to people what I do for my research, they seem to be more interested in how I catch and approach my subjects, than what I detect in them. However, it is pretty cool what I can tell about a bird by studying its feathers.

My name is Mari Løseth and I’m an environmental detective, also called an ecotoxicologist. This is a fancy title for someone who studies contamination in wildlife. For my PhD project at the Bird Ecotoxicology group (IBI, NTNU) I investigate environmental contamination in birds. I want to find out how new, current-use and regulated compounds released into the environment can affect birds feeding high up in the food chain. I want to know how they are coping. Are they more stressed with higher contamination load? Or will the compounds they are exposed to challenge their immune system?

mari-eagle-2

The white-tailed eagle (Haliaeetus albicilla) breeds all over Europe and northern Asia, and the largest population is found in Norway. Photo: Mari Løseth


 

Why?

I wanted to work with birds because they are fascinating and complex creatures. They are long lived, intelligent, beautiful and the coolest thing of all – they can fly. The birds I study, the white-tailed eagle (Haliaeetus albicilla) and the glaucous gull (Larus Hyperboreus) are both top predators in their habitats.

Looking at them, it might be hard to imagine that the inconspicuous glaucous gull could be anywhere near as superior a hunter as the huge white-tailed eagle with its impressive claws and over 2 meter wingspan. Truth is – despite being around half the size – the gull is equally fierce. The two species have quite similar diets – varied, opportunistic and seasonal. Prey species are often fish, other seabirds and mammals.

The glaucous gull (Larus hyperboreus) has a circumpolar and high-Arctic distribution, and in the northeast Atlantic Ocean its breeding grounds span from Greenland to North-Russia. Photo: Mari Løseth

The glaucous gull (Larus hyperboreus) has a circumpolar and high-Arctic distribution, and in the northeast Atlantic Ocean its breeding grounds span from Greenland to North-Russia. Photo: Mari Løseth

 
Feeding on such a high level in the food chain is great as you usually don’t have to compete for food. Unfortunately, it also has some down sides.

Contaminants

When feeding high up in the food chain, the birds risk exposure to high concentrations of several environmental contaminants. Some of these contaminants possess bioaccumulative properties. This means that the concentrations of the compound will increase in the exposed individual, because the uptake rate is higher than the excretion rate. Some of these compounds can also increase with each step up in the food chain, resulting in very high concentration in predatory species. This process is
called biomagnification.

Modified from buzzle.com

Modified from buzzle.com

 
As both the white-tailed eagle and the glaucous gull are feeding on the top of the food chain they can be exposed to high contamination levels, even though they live in non-urbanized and remote areas. This is due to the physical and chemical properties of the compounds. They can be volatile or bind to particles and thus be transported long-distances with wind and/or water currents away from the pollution source, reaching remote areas such as the high Arctic.

The compounds I investigate are the ones making our daily products water- and dirt repellent, non-flammable and long lasting, such as perfluorinated compounds and flame retardants. This is done by introducing the chemicals with the desired properties into consumer products. And as we produce, use and dispose of the products, these chemicals can be released into the environment. At this point they become environmental chemicals, contamination or pollution – and they can potentially harm vulnerable ecosystems already under a lot of stress from urbanization, deforestation and climate change.

A beautiful glaucous gull, soon to be released. Photo: Marte Melnes

A beautiful glaucous gull, soon to be released. Photo: Marte Melnes

 

What for?

I aim to look at differences in contamination patterns in different habitats to see if some locations are more exposed than others. When doing this, we usually look at concentrations in blood plasma. This time I’m also investigating the compounds in the feathers, in hope that this can replace the blood samples and the need to capture and restrain the birds when collecting samples.

To see how the birds are coping with the contaminants, I look at their general health and immune functioning. I do this by exposing extracted lymphocytes (a type of white blood cells present in the blood) to an immune challenge and observing the response. In order to measure how stressed the birds are, I detect their major stress hormone – corticosterone – in their blood and feathers. The blood will tell me how stressed the birds are right before and in the actual sample situation, while the feather sample will allow me to assess how stressed they have been over a longer period (during the period of feather growth).

How can you detect this in feathers?

 

Preparing an eagle feather for analysis. Photo: Mari Løseth

Preparing an eagle feather for analysis. Photo: Mari Løseth

Well, during the growth, the feather is continuously supplied with blood though the “stem” of the feather, the rachis. As the feather continues to grow, the blood supply of the new grown feather part is shut off, and the hormones and compounds that were supplied to the feather remain there forever. This process of incorporation continues until the feathers if fully grown and the blood supply is disconnected. The feather thus integrates contaminants and hormones present in the blood during the whole period of feather growth. This makes the feather an ideal sample matrix – in an ideal world.

A lot of research needs to be done in order to find the right method to detect all the desired compounds in the feather, and this is something I aim to do during my PhD.

I hope to see that the birds are coping well, and that their health and immune system will not be affected by their contaminant load, even if they become stressed as I approach them in the field for another session of measures and selfies.

Wish me luck!

The ultimate selfie, an “eaglefie”. Photo: Mari Løseth

The ultimate selfie, an “eaglefie”. Photo: Mari Løseth

 

How cyanobacteria eat iron
        
6
  6 April, 2016
        


Anne_Vogel-1

I am looking at an ongoing integration of DNA I gave my cyanobacteria to delete the building blocks of the nanowires


 
Cyanobacteria (commonly known as blue-green algae) obtain energy from photosynthesis: they use sunlight as energy source to convert CO2 and water to sugar and oxygen. Therefore, they contribute a significant part to global carbon fixation. Just like humans, cyanobacteria require iron to survive. While humans can simply eat e.g. spinach, cyanobacteria need to take up iron via other mechanisms. Iron is an abundant element on land so no problem there. However, iron form insoluble particles (rust) when in contact with oxygen and water. Therefore, in oceans, we can hardly find any soluble, easy-to-take-up iron but instead we find rust particles blown from the land into the sea.

The cyanobacteria living there need to deal with rust as their iron source. But everyone who tries to clean his or her bike chain from rust knows how persistent rust can be and that it does not dissolve without difficulty. Therefore, we think that certain cyanobacteria have developed a trick and our hypothesis is as follows: They produce electrons inside of the cell and conduct those via nanowires (hair-like structures on the outside of the cyanobacteria) to the rust particles thereby making the iron soluble again. Then they can take up the newly formed (now called bioavailable) iron.

Anne_Vogel-samples

We see strains of Synechococcus with a deletion of building blocks of nanowires


 
There is compelling evidence that our hypothesis is true for non-photosynthetic bacteria. It will be my job to identify the building blocks of the nanowires and to see what happens to ‘my’ cyanobacteria (Synechococcus PCC7002) when I delete these building blocks using molecular techniques. If we understand how the electrons are generated and conducted, we could ultimately use cyanobacteria as an alternative renewable source for electricity. Additionally, since cyanobacteria use CO2, the findings of my project could help to reduce the amount of CO2 in our atmosphere and to fight global warming.