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- Gañez Zapater, Antoni, 1986-
(författare)
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Gene regulation by chromatin remodelling complexes : SWI/SNF complex in mRNA processing and B-WICH complex in ribosomal gene expression
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this project is to investigate the roles of chromatin remodelling complexes in gene regulation. It is focused on two groups of chromatin complexes: the mammalian BRG1 and BRM SWI/SNF complexes and the ISWI-containing B-WICH complex.Study 1 investigates the role of SWI/SNF complexes in alternative splicing. We show that the presence of the ATPase core subunits Brg1 and Brm influence the alternative splicing outcome of a subset of genes. We show that Brg1 and Brm interact with several splicing related factors in the nascent RNA, and that the recruitment of some of these factors to their target sites is regulated by the presence of Brg1 and Brm. We propose that SWI/SNF ATPases can modulate the interactions of RNA binding factors to the nascent RNA and in that way alter alternative splicing outcome.Study 2 focuses on SWI/SNF complexes and their influence on cleavage and polyadenylation of mRNA. We show that Brg1 and Brm interact with subunits of the cleavage and polyadenylation complexes in the nascent mRNA. SWI/SNF complexes facilitate the recruitment of the cleavage and polyadenylation complex to the polyadenylation site in a subset of genes, and this results in a more efficient cleavage and polyadenylation.Study 3 shows that B-WICH is required for ribosome gene transcriptional activation upon glucose stimulation. WSTF and SNF2h, two of the B-WICH subunits, are needed to establish an active chromatin state in the RNA pol I gene promoter when the glucose concentration is raised after a period of deprivation. We propose that it counteracts the silent, poised chromatin state imposed by the silencing chromatin remodelling complex NuRD to allow for the RNA pol I machinery to bind to the promoter.These studies show that the influence of chromatin remodelling complexes upon gene expression is important for remodelling nucleosomes at the promoter, for alternative splicing, cleavage and polyadenylation and transcriptional initiation. These complexes work together with other chromatin remodelling factors, interact with other complexes and regulate their activity by affecting their recruitment dynamics.
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| 2. |
- Nyberg, Roger G.
(författare)
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Automating condition monitoring of vegetation on railway trackbeds and embankments
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vegetation growing on railway trackbeds and embankments present potential problems. The presence of vegetation threatens the safety of personnel inspecting the railway infrastructure. In addition vegetation growth clogs the ballast and results in inadequate track drainage which in turn could lead to the collapse of the railway embankment.Assessing vegetation within the realm of railway maintenance is mainly carried out manually by making visual inspections along the track. This is done either on-site or by watching videos recorded by maintenance vehicles mainly operated by the national railway administrative body.A need for the automated detection and characterisation of vegetation on railways (a subset of vegetation control/management) has been identified in collaboration with local railway maintenance subcontractors and Trafikverket, the Swedish Transport Administration (STA). The latter is responsible for long-term planning of the transport system for all types of traffic, as well as for the building, operation and maintenance of public roads and railways.The purpose of this research project was to investigate how vegetation can be measured and quantified by human raters and how machine vision can automate the same process.Data were acquired at railway trackbeds and embankments during field measurement experiments. All field data (such as images) in this thesis work was acquired on operational, lightly trafficked railway tracks, mostly trafficked by goods trains. Data were also generated by letting (human) raters conduct visual estimates of plant cover and/or count the number of plants, either on-site or in-house by making visual estimates of the images acquired from the field experiments. Later, the degree of reliability of(human) raters’ visual estimates were investigated and compared against machine vision algorithms.The overall results of the investigations involving human raters showed inconsistency in their estimates, and are therefore unreliable. As a result of the exploration of machine vision, computational methods and algorithms enabling automatic detection and characterisation of vegetation along railways were developed. The results achieved in the current work have shown that the use of image data for detecting vegetation is indeed possible and that such results could form the base for decisions regarding vegetation control. The performance of the machine vision algorithm which quantifies the vegetation cover was able to process 98% of the im-age data. Investigations of classifying plants from images were conducted in in order to recognise the specie. The classification rate accuracy was 95%.Objective measurements such as the ones proposed in thesis offers easy access to the measurements to all the involved parties and makes the subcontracting process easier i.e., both the subcontractors and the national railway administration are given the same reference framework concerning vegetation before signing a contract, which can then be crosschecked post maintenance.A very important issue which comes with an increasing ability to recognise species is the maintenance of biological diversity. Biological diversity along the trackbeds and embankments can be mapped, and maintained, through better and robust monitoring procedures. Continuously monitoring the state of vegetation along railways is highly recommended in order to identify a need for maintenance actions, and in addition to keep track of biodiversity. The computational methods or algorithms developed form the foundation of an automatic inspection system capable of objectively supporting manual inspections, or replacing manual inspections.
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| 3. |
- Smith, Alexander J.
(författare)
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Tools for characterizing performance degradation in lithium-ion batteries
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lithium-ion batteries have enabled vast societal changes, ranging in scale from the adoption of personal electronics to electromobility and grid-scale, renewable energy storage. However, all applications face performance fade over time, observed as losses of battery capacity and power. This gradual degradation is most often due to electrochemical aging processes inside the cell, including phenomena causing a loss of cyclable lithium (e.g., lithium plating, growth of the solid‑electrolyte interphase or SEI), a loss of active material (e.g., particle cracking), and/or a loss of ionic or electronic conductivity. In the compiled works, many individual batteries have been aged and analyzed to better understand the conditions contributing to aging in different cell designs. The cells studied include lab-built pouch cells, commercial cylindrical cells (with electrodes LiNixMnyCo1‑x‑yO2‑LiMn2O4/C6 and LiNixCoyAl1‑x‑yO2/C6‑SiOx), and larger automotive-grade prismatic cells (LiNixMnyCo1‑x‑yO2/C6).Complementary in situ and post mortem methods are developed, with relevance for both battery research and battery control systems. Excellent characterization can often be achieved by a combination of differential voltage and incremental capacity analyses. Obtained from a simple, slow cycle, the derivatives of the voltage profile reveal many features that can be tracked over aging. This thesis particularly develops these techniques for blended electrodes, deconvoluting the aging of individual components. Dynamic performance is resolved with a novel polarization factor, impedance spectroscopy, and tools based on current pulses/interruptions. Finally, a protocol based on nuclear magnetic resonance spectroscopy is developed, enabling fast and direct quantification of lithium plating and SEI on harvested battery components. With such tools, we can improve how batteries are used and monitored, paving the way for efficient research and safer, more reliable batteries.
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