Extracts from recent PhD theses

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Below are extract from a selection of recent PhD theses:

January 2019

"Rapid diagnosis of hemolysis"

Illustration: Chen Zhou

Hemolysis - red blood cells that rupture prematurely - is a global health problem. The disorder may have many causes - hereditary being among them. Currently, there is no fast and reliable method to detect hemolysis in clinical practice because the diagnosis requires the separation of red blood cells and blood plasma by means of centrifugation, for example.

Chen Zhou from DTU Nanotech has - among other things - developed a sensor which solves the problem. Using new nanofilters on an optical waveguide it is possible to measure very small blood samples without any further preparation. The nanosensor, which has shown promising results, is integrated in a commercially available analyser from Radiometer Medical Aps.

Illustration: Chen Zhou


"Algorithm can work with compressed data"

Illustration: Colourbox

In line with the exponential increase in data volume, there is a corresponding requirement for data storage, transmission, and processing.  While hardware development - among other things - has supported these needs in the form of more powerful computers and large data centres, it can no longer keep pace.  There is now a need for solutions that can fully exploit the hardwaree.g. by compressing data. However, this is not a simple exercise.

Mikko Berggren Ettienne from DTU Compute has designed algorithms, data structures, and protocols which can work directly with compressed data. Among other things, he has designed a data structure that can determine whether a sentence or a word is part of a larger compressed text without first having to unpack the entire text.

The response time is as fast as if the text were not compressed - and the space requirement will often be significantly lower. This makes it possible to make calculations on larger volumes of data at the same speed as today - and most importantly without increasing hardware requirements.

Illustration: COLOURBOX


"Database of unknown materials"

Illustration: Colourbox

A wealth of applications is expected to come into play,
as large numbers of new 2D materials are discovered. To date, approximately 50 different 2D materials have been produced - graphene being the first and best-known material.

Sten Haastrup from DTU Physics has systematically investigated the properties of more than 3,000 new 2D materials which have not yet been manufactured. By starting with known 2D materials, he has used a computer to systematically replace the atoms of these materials with similar atoms from the periodic table.

This method offers thousands of potential structures. Sten Haastrup has then calculated the stability, resilience, and the thermodynamic, electronic, and optical properties of the materials. The database has subsequently found hundreds of all-new materials - approximately 30 of which have particularly interesting properties. These will now be studied in detail with a view to potential manufacture.

Illustration: Colourbox


December 2018

"Better modelling of complex winds"

Photo: Bjarke Tobias Olsen
The demand for sustainable energy is increasing — and with it, the need for new wind turbine sites. As a result, these sites are increasingly being located in areas where the wind’s patterns are complex — e.g. next to mountains, coastlines, or forests. This poses a challenge for the models used to assess wind movements, as the local conditions vary greatly.

At the town of Perdigão in Portugal where the terrain is hilly, the wind is affected by many factors — with potentially very strong local wind conditions as a result. Here, Bjarke Tobias Olsen from DTU Wind Energy  has tested a so-called model chain method, which can connect modelling of weather phenomena measuring more than 2,000 km with those of less than a kilometre.

The method, which successfully measured the wind movements on site, produced a marked improvement in accuracy. The result is encouraging with a view to creating the basis for modelling the conditions in other complex terrains.

Photo: Bjarke Tobias Olsen


"New understanding of intestinal bacteria"

Photo: ColourboxThe microbial community that colonize the lower part of the human digestive tract (gut flora) have a major impact on health. While we know that diet — in particular carbohydrates and bioactive substances of plant origin — have a strong impact on health, the underlying mechanisms are far from clear.

However, MIA Christine Theilmann from DTU Bioengineering has made significant progress and shown that Lactobacillus acidophilus — which is commonly found in the small intestine (and in A38 ed.) — grows exceptionally well on the composite sugars found in e.g fruit, nuts, wine, and dark chocolate.

After utilizing the sugar, the bacterium releases bioactive metabolites with antioxidative, anti-inflammatory, and cancer-preventive properties into the intestinal system. This interaction between plant sugars and intestinal bacteria has not been previously documented.


"From pig bristles to high-protein fish feed"

Photo: Francesco Cristino FalcoFeathers, horn, wool, hair, and bristles are a natural source of the protein keratin, which constitutes the Earth’s third most common source of renewable biomass. Keratin is used as a source of protein in animal feed — e.g. in pig bristle meal — but production involves an aggressive process which results in insufficiently high levels of amino acid.

Francesco Cristino Falco from DTU Chemical Engineering has developed a technique whereby microorganisms and enzymes are used to break down e.g. pig bristles into a high-protein meal which still contains the essential amino acids and can thus be used for fish feed.

In his thesis, Francesco Cristino Falco estimates that over 60,000 tonnes of proteins can be extracted annually from a renewable source — in 2014, 250 million pigs were slaughtered in the EU alone. Utilization is sustainable in the sense that it reduces the need for other sources of protein and makes better use of slaughterhouse waste.

Photo: Francesco Cristino Falco

 Oktober 2018

"Satellite monitoring of water reservoirs"

Illustration: Liguang JiangSurface water is an important global resource, but reservoir water levels can often be difficult to monitor  - e.g. in remote regions. Here, satellite monitoring provides a  viable solution. Thanks to its orbit around the Earth, the ESA CryoSat-2 mission is able to monitor a very high number of water bodies. Liguang Jiang from DTU Environment used six years of data from CryoSat-2 to investigate more than 1,000 Chinese Lakes and reservoirs. 

The dynamics of these water bodies varies according to region. Lakes in the Northern Tibetan Plateau are rising - e.g. noticeably in populated areas presumably due to human intervention. The satellite has also managed to map the surface of six rivers over long distances. The results for Songhua River in Northeast China were compared with data from a modelling which showed a strong correlation between simulated and measured river levels.

The assumption, therefore, is that measurements of surface water with modelling can be used to project the risk of flooding - crucial for poorly studied rivers.

Illustration: Liguang Jiang

"Better CT scan models"

Photo: ColourboxX-ray computed tomography - better known as CT scanning - has become an indispensable technology  with many applications ranging from medical imaging to materials science. In some applications, high-quality CT images are crucial in order to avoid misinterpretations or false conclusions. For example, it can be difficult for a doctor to make a correct diagnosis on the basis of a CT image polluted by noise and artefacts (man-made phenomena, ed.). And within the field of materials science, serious artefacts can be confused with cracks in an object - or vice versa.

Hari Om Aggrawal from DTU Compute has studied the factors affecting the quality of CT images and has - among other things, devised a new mathematical model that can reduce certain types of noise. He has also developed a model that can better accommodate movement from e.g. a beating heart - or a pill that has been dissolved.

The models can lead to significant improvements in picture quality and pave the way for improved methods that can help researchers to study dynamic processes using a CT scan.


"Modelling of cities’ future energy consumption"

Photo: ColourboxModern cities account for the majority of the world’s energy consumption, and as cities generally continue to grow, energy systems must undergo radical change in order to be sustainable. Using, among other things, nine case studies, Dominik F. Dominkovic from DTU Energy has focused on the roles that can be taken by different technologies in the urban energy mix of the future - and on different technologies that can increase energy system flexibility.

Among other things, he found that 72 per cent of the demand in the transport sector could be electrified immediately using available technology. In addition, both district heating and cooling can exploit thermal energy storage, which is much cheaper than storage in batteries.

Finally, he concluded that air pollution increased significantly through the use of biomass despite a reduction in CO2 emissions. Including air pollution - rather than simply focusing on CO2 emissions - is therefore an important part of future modelling of urban energy systems.

Illustration: COLOURBOX

August 2018

"MRSA infections in almost every pig herd and about every third mink farm tested"

Mink The rising incidence of MRSA multidrug-resistant bacteria has received considerable attention in recent years, particularly due to an increase in the number of people carrying the bacteria.

MRSA is primarily associated with pig herds, but Julie Elvekjær Hansen from DTU Vet shows in her thesis that new reservoirs of MRSA have arisen, and these have most likely arisen as a result of carry-over from pigs via routes which are still relatively unknown. These include dairy cow and veal calf herds (in which the number of carriers is low, however), while 33 per cent of the screened mink farms tested positive for MRSA.

An increasing number of people in contact with mink have also tested positive for MRSA since 2011. This is a worrying trend, as the emergence of new reservoirs increases the number of people who are exposed to the bacteria and in danger of getting an infection or unintentionally adding to the spread of the bacteria in society.

The thesis emphasizes the importance of lowering the levels of MRSA in pig production and illustrates that it is vitally important to identify potential new MRSA reservoirs and continue to screen MRSA-positive herds with low incidence.


"New radioactive sources to fight cancer"

Cancer - colourbox

A challenge in cancer treatment is that a high percentage of patients find that their cancer or metastases return, even though the treatment had a positive effect. Effective and safe treatments are therefore needed which improve the therapeutic effect and minimize side effects on healthy tissue.

Radiation is one of the most effective treatments for cancer. This includes brachytherapy, where the radioactive source is inserted into the tumour tissue - a very successful form of treatment. But even state-of-the-art brachytherapy depends on solid physical sources and design principles that were developed over 50 years ago.

In collaboration with DTU Nutech and DTU Nanotech, Gocke Engudar from DTU Chemistry has developed new brachytherapy sources which are biocompatible and biodegradable, and distribute the therapeutic dose uniformly in the tumour tissue. The new radioactive sources are showing potential for improving the effectiveness of brachytherapy.


"Genomic diversity in Aspergillus fungi"

Thorkild Amdi Christensen vandkandeskimmel

Aspergillus is a genus of mould which is very commonly found, for example as black mould on onions. Some species can make us ill, even very ill. Others are used in enzyme and chemical production and in the food industry. These differences within the same genus are extraordinary, and identification of the genes behind the diversity is therefore of great significance to both the industrial and academic world.

The genomic era for moulds actually began in 2005 with the sequencing of three Aspergillus species. Jane Lind Nybo Rasmussen has now sequenced and developed bioinformatics tools to compare the 350 Aspergillus species. She has also helped to release and analyse more than 40 genomes in cooperation with the Aspergillus whole genus sequencing project.

Within a few years the project will have published all known Aspergillus genomes, giving researchers and industry a resource which permits research at a level not previously possible in fungi.

Photo: Thorkild Amdi Christensen


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