---
_id: '8574'
abstract:
- lang: eng
text: "This thesis concerns itself with the interactions of evolutionary and ecological
forces and the consequences on genetic diversity and the ultimate survival of
populations. It is important to understand what signals processes \r\nleave on
the genome and what we can infer from such data, which is usually abundant but
noisy. Furthermore, understanding how and when populations adapt or go extinct
is important for practical purposes, such as the genetic management of populations,
as well as for theoretical questions, since local adaptation can be the first
step toward speciation. \r\nIn Chapter 2, we introduce the method of maximum entropy
to approximate the demographic changes of a population in a simple setting, namely
the logistic growth model with immigration. We show that this method is not only
a powerful \r\ntool in physics but can be gainfully applied in an ecological framework.
We investigate how well it approximates the real \r\nbehavior of the system, and
find that is does so, even in unexpected situations. Finally, we illustrate how
it can model changing environments.\r\nIn Chapter 3, we analyze the co-evolution
of allele frequencies and population sizes in an infinite island model.\r\nWe
give conditions under which polygenic adaptation to a rare habitat is possible.
The model we use is based on the diffusion approximation, considers eco-evolutionary
feedback mechanisms (hard selection), and treats both \r\ndrift and environmental
fluctuations explicitly. We also look at limiting scenarios, for which we derive
analytical expressions. \r\nIn Chapter 4, we present a coalescent based simulation
tool to obtain patterns of diversity in a spatially explicit subdivided population,
in which the demographic history of each subpopulation can be specified. We compare
\r\nthe results to existing predictions, and explore the relative importance of
time and space under a variety of spatial arrangements and demographic histories,
such as expansion and extinction. \r\nIn the last chapter, we give a brief outlook
to further research. "
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Eniko
full_name: Szep, Eniko
id: 485BB5A4-F248-11E8-B48F-1D18A9856A87
last_name: Szep
citation:
ama: Szep E. Local adaptation in metapopulations. 2020. doi:10.15479/AT:ISTA:8574
apa: Szep, E. (2020). Local adaptation in metapopulations. Institute of Science
and Technology Austria. https://doi.org/10.15479/AT:ISTA:8574
chicago: Szep, Eniko. “Local Adaptation in Metapopulations.” Institute of Science
and Technology Austria, 2020. https://doi.org/10.15479/AT:ISTA:8574.
ieee: E. Szep, “Local adaptation in metapopulations,” Institute of Science and Technology
Austria, 2020.
ista: Szep E. 2020. Local adaptation in metapopulations. Institute of Science and
Technology Austria.
mla: Szep, Eniko. Local Adaptation in Metapopulations. Institute of Science
and Technology Austria, 2020, doi:10.15479/AT:ISTA:8574.
short: E. Szep, Local Adaptation in Metapopulations, Institute of Science and Technology
Austria, 2020.
date_created: 2020-09-28T07:33:38Z
date_published: 2020-09-20T00:00:00Z
date_updated: 2023-09-07T13:11:39Z
day: '20'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: NiBa
doi: 10.15479/AT:ISTA:8574
file:
- access_level: open_access
checksum: 20e71f015fbbd78fea708893ad634ed0
content_type: application/pdf
creator: dernst
date_created: 2020-09-28T07:25:35Z
date_updated: 2020-09-28T07:25:35Z
file_id: '8575'
file_name: thesis_EnikoSzep_final.pdf
file_size: 6354833
relation: main_file
success: 1
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checksum: a8de2c14a1bb4e53c857787efbb289e1
content_type: application/x-zip-compressed
creator: dernst
date_created: 2020-09-28T07:25:37Z
date_updated: 2020-09-28T07:25:37Z
file_id: '8576'
file_name: thesisFiles_EnikoSzep.zip
file_size: 23020401
relation: source_file
file_date_updated: 2020-09-28T07:25:37Z
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '158'
publication_identifier:
eissn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
status: public
supervisor:
- first_name: Nicholas H
full_name: Barton, Nicholas H
id: 4880FE40-F248-11E8-B48F-1D18A9856A87
last_name: Barton
orcid: 0000-0002-8548-5240
title: Local adaptation in metapopulations
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2020'
...
---
_id: '7196'
abstract:
- lang: eng
text: 'In this thesis we study certain mathematical aspects of evolution. The two
primary forces that drive an evolutionary process are mutation and selection.
Mutation generates new variants in a population. Selection chooses among the variants
depending on the reproductive rates of individuals. Evolutionary processes are
intrinsically random – a new mutation that is initially present in the population
at low frequency can go extinct, even if it confers a reproductive advantage.
The overall rate of evolution is largely determined by two quantities: the probability
that an invading advantageous mutation spreads through the population (called
fixation probability) and the time until it does so (called fixation time). Both
those quantities crucially depend not only on the strength of the invading mutation
but also on the population structure. In this thesis, we aim to understand how
the underlying population structure affects the overall rate of evolution. Specifically,
we study population structures that increase the fixation probability of advantageous
mutants (called amplifiers of selection). Broadly speaking, our results are of
three different types: We present various strong amplifiers, we identify regimes
under which only limited amplification is feasible, and we propose population
structures that provide different tradeoffs between high fixation probability
and short fixation time.'
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Josef
full_name: Tkadlec, Josef
id: 3F24CCC8-F248-11E8-B48F-1D18A9856A87
last_name: Tkadlec
orcid: 0000-0002-1097-9684
citation:
ama: Tkadlec J. A role of graphs in evolutionary processes. 2020. doi:10.15479/AT:ISTA:7196
apa: Tkadlec, J. (2020). A role of graphs in evolutionary processes. Institute
of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:7196
chicago: Tkadlec, Josef. “A Role of Graphs in Evolutionary Processes.” Institute
of Science and Technology Austria, 2020. https://doi.org/10.15479/AT:ISTA:7196.
ieee: J. Tkadlec, “A role of graphs in evolutionary processes,” Institute of Science
and Technology Austria, 2020.
ista: Tkadlec J. 2020. A role of graphs in evolutionary processes. Institute of
Science and Technology Austria.
mla: Tkadlec, Josef. A Role of Graphs in Evolutionary Processes. Institute
of Science and Technology Austria, 2020, doi:10.15479/AT:ISTA:7196.
short: J. Tkadlec, A Role of Graphs in Evolutionary Processes, Institute of Science
and Technology Austria, 2020.
date_created: 2019-12-20T12:26:36Z
date_published: 2020-01-12T00:00:00Z
date_updated: 2023-10-17T12:29:46Z
day: '12'
ddc:
- '519'
degree_awarded: PhD
department:
- _id: KrCh
- _id: GradSch
doi: 10.15479/AT:ISTA:7196
file:
- access_level: closed
checksum: 451f8e64b0eb26bf297644ac72bfcbe9
content_type: application/zip
creator: jtkadlec
date_created: 2020-01-12T11:49:49Z
date_updated: 2020-07-14T12:47:52Z
file_id: '7255'
file_name: thesis.zip
file_size: 21100497
relation: source_file
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checksum: d8c44cbc4f939c49a8efc9d4b8bb3985
content_type: application/pdf
creator: dernst
date_created: 2020-01-28T07:32:42Z
date_updated: 2020-07-14T12:47:52Z
file_id: '7367'
file_name: 2020_Tkadlec_Thesis.pdf
file_size: 11670983
relation: main_file
file_date_updated: 2020-07-14T12:47:52Z
has_accepted_license: '1'
language:
- iso: eng
month: '01'
oa: 1
oa_version: Published Version
page: '144'
publication_identifier:
eissn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '7210'
relation: dissertation_contains
status: public
- id: '5751'
relation: dissertation_contains
status: public
- id: '7212'
relation: dissertation_contains
status: public
status: public
supervisor:
- first_name: Krishnendu
full_name: Chatterjee, Krishnendu
id: 2E5DCA20-F248-11E8-B48F-1D18A9856A87
last_name: Chatterjee
orcid: 0000-0002-4561-241X
title: A role of graphs in evolutionary processes
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2020'
...
---
_id: '7680'
abstract:
- lang: eng
text: "Proteins and their complex dynamic interactions regulate cellular mechanisms
from sensing and transducing extracellular signals, to mediating genetic responses,
and sustaining or changing cell morphology. To manipulate these protein-protein
interactions (PPIs) that govern the behavior and fate of cells, synthetically
constructed, genetically encoded tools provide the means to precisely target proteins
of interest (POIs), and control their subcellular localization and activity in
vitro and in vivo. Ideal synthetic tools react to an orthogonal cue, i.e. a trigger
that does not activate any other endogenous process, thereby allowing manipulation
of the POI alone.\r\nIn optogenetics, naturally occurring photosensory domain
from plants, algae and bacteria are re-purposed and genetically fused to POIs.
Illumination with light of a specific wavelength triggers a conformational change
that can mediate PPIs, such as dimerization or oligomerization. By using light
as a trigger, these tools can be activated with high spatial and temporal precision,
on subcellular and millisecond scales. Chemogenetic tools consist of protein domains
that recognize and bind small molecules. By genetic fusion to POIs, these domains
can mediate PPIs upon addition of their specific ligands, which are often synthetically
designed to provide highly specific interactions and exhibit good bioavailability.\r\nMost
optogenetic tools to mediate PPIs are based on well-studied photoreceptors responding
to red, blue or near-UV light, leaving a striking gap in the green band of the
visible light spectrum. Among both optogenetic and chemogenetic tools, there is
an abundance of methods to induce PPIs, but tools to disrupt them require UV illumination,
rely on covalent linkage and subsequent enzymatic cleavage or initially result
in protein clustering of unknown stoichiometry.\r\nThis work describes how the
recently structurally and photochemically characterized green-light responsive
cobalamin-binding domains (CBDs) from bacterial transcription factors were re-purposed
to function as a green-light responsive optogenetic tool. In contrast to previously
engineered optogenetic tools, CBDs do not induce PPI, but rather confer a PPI
already upon expression, which can be rapidly disrupted by illumination. This
was employed to mimic inhibition of constitutive activity of a growth factor receptor,
and successfully implement for cell signalling in mammalian cells and in vivo
to rescue development in zebrafish. This work further describes the development
and application of a chemically induced de-dimerizer (CDD) based on a recently
identified and structurally described bacterial oxyreductase. CDD forms a dimer
upon expression in absence of its cofactor, the flavin derivative F420. Safety
and of domain expression and ligand exposure are demonstrated in vitro and in
vivo in zebrafish. The system is further applied to inhibit cell signalling output
from a chimeric receptor upon F420 treatment.\r\nCBDs and CDD expand the repertoire
of synthetic tools by providing novel mechanisms of mediating PPIs, and by recognizing
previously not utilized cues. In the future, they can readily be combined with
existing synthetic tools to functionally manipulate PPIs in vitro and in vivo."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Stephanie
full_name: Kainrath, Stephanie
id: 32CFBA64-F248-11E8-B48F-1D18A9856A87
last_name: Kainrath
citation:
ama: Kainrath S. Synthetic tools for optogenetic and chemogenetic inhibition of
cellular signals. 2020. doi:10.15479/AT:ISTA:7680
apa: Kainrath, S. (2020). Synthetic tools for optogenetic and chemogenetic inhibition
of cellular signals. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:7680
chicago: Kainrath, Stephanie. “Synthetic Tools for Optogenetic and Chemogenetic
Inhibition of Cellular Signals.” Institute of Science and Technology Austria,
2020. https://doi.org/10.15479/AT:ISTA:7680.
ieee: S. Kainrath, “Synthetic tools for optogenetic and chemogenetic inhibition
of cellular signals,” Institute of Science and Technology Austria, 2020.
ista: Kainrath S. 2020. Synthetic tools for optogenetic and chemogenetic inhibition
of cellular signals. Institute of Science and Technology Austria.
mla: Kainrath, Stephanie. Synthetic Tools for Optogenetic and Chemogenetic Inhibition
of Cellular Signals. Institute of Science and Technology Austria, 2020, doi:10.15479/AT:ISTA:7680.
short: S. Kainrath, Synthetic Tools for Optogenetic and Chemogenetic Inhibition
of Cellular Signals, Institute of Science and Technology Austria, 2020.
date_created: 2020-04-24T16:00:51Z
date_published: 2020-04-24T00:00:00Z
date_updated: 2023-09-22T09:20:10Z
day: '24'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: CaGu
doi: 10.15479/AT:ISTA:7680
file:
- access_level: open_access
checksum: fb9a4468eb27be92690728e35c823796
content_type: application/pdf
creator: stgingl
date_created: 2020-04-28T11:19:21Z
date_updated: 2021-10-31T23:30:05Z
embargo: 2021-10-30
file_id: '7692'
file_name: Thesis_without-signatures_PDFA.pdf
file_size: 3268017
relation: main_file
- access_level: closed
checksum: f6c80ca97104a631a328cb79a2c53493
content_type: application/octet-stream
creator: stgingl
date_created: 2020-04-28T11:19:24Z
date_updated: 2021-10-31T23:30:05Z
embargo_to: open_access
file_id: '7693'
file_name: Thesis_without signatures.docx
file_size: 5167703
relation: source_file
file_date_updated: 2021-10-31T23:30:05Z
has_accepted_license: '1'
language:
- iso: eng
month: '04'
oa: 1
oa_version: None
page: '98'
publication_identifier:
eissn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '1028'
relation: dissertation_contains
status: public
status: public
supervisor:
- first_name: Harald L
full_name: Janovjak, Harald L
id: 33BA6C30-F248-11E8-B48F-1D18A9856A87
last_name: Janovjak
orcid: 0000-0002-8023-9315
title: Synthetic tools for optogenetic and chemogenetic inhibition of cellular signals
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2020'
...
---
_id: '6891'
abstract:
- lang: eng
text: "While cells of mesenchymal or epithelial origin perform their effector functions
in a purely anchorage dependent manner, cells derived from the hematopoietic lineage
are not committed to operate only within a specific niche. Instead, these cells
are able to function autonomously of the molecular composition in a broad range
of tissue compartments. By this means, cells of the hematopoietic lineage retain
the capacity to disseminate into connective tissue and recirculate between organs,
building the foundation for essential processes such as tissue regeneration or
immune surveillance. \r\nCells of the immune system, specifically leukocytes,
are extraordinarily good at performing this task. These cells are able to flexibly
shift their mode of migration between an adhesion-mediated and an adhesion-independent
manner, instantaneously accommodating for any changes in molecular composition
of the external scaffold. The key component driving directed leukocyte migration
is the chemokine receptor 7, which guides the cell along gradients of chemokine
ligand. Therefore, the physical destination of migrating leukocytes is purely
deterministic, i.e. given by global directional cues such as chemokine gradients.
\r\nNevertheless, these cells typically reside in three-dimensional scaffolds
of inhomogeneous complexity, raising the question whether cells are able to locally
discriminate between multiple optional migration routes. Current literature provides
evidence that leukocytes, specifically dendritic cells, do indeed probe their
surrounding by virtue of multiple explorative protrusions. However, it remains
enigmatic how these cells decide which one is the more favorable route to follow
and what are the key players involved in performing this task. Due to the heterogeneous
environment of most tissues, and the vast adaptability of migrating leukocytes,
at this time it is not clear to what extent leukocytes are able to optimize their
migratory strategy by adapting their level of adhesiveness. And, given the fact
that leukocyte migration is characterized by branched cell shapes in combination
with high migration velocities, it is reasonable to assume that these cells require
fine tuned shape maintenance mechanisms that tightly coordinate protrusion and
adhesion dynamics in a spatiotemporal manner. \r\nTherefore, this study aimed
to elucidate how rapidly migrating leukocytes opt for an ideal migratory path
while maintaining a continuous cell shape and balancing adhesive forces to efficiently
navigate through complex microenvironments. \r\nThe results of this study unraveled
a role for the microtubule cytoskeleton in promoting the decision making process
during path finding and for the first time point towards a microtubule-mediated
function in cell shape maintenance of highly ramified cells such as dendritic
cells. Furthermore, we found that migrating low-adhesive leukocytes are able to
instantaneously adapt to increased tensile load by engaging adhesion receptors.
This response was only occurring tangential to the substrate while adhesive properties
in the vertical direction were not increased. As leukocytes are primed for rapid
migration velocities, these results demonstrate that leukocyte integrins are able
to confer a high level of traction forces parallel to the cell membrane along
the direction of migration without wasting energy in gluing the cell to the substrate.
\r\nThus, the data in the here presented thesis provide new insights into the
pivotal role of cytoskeletal dynamics and the mechanisms of force transduction
during leukocyte migration. \r\nThereby the here presented results help to further
define fundamental principles underlying leukocyte migration and open up potential
therapeutic avenues of clinical relevance.\r\n"
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Aglaja
full_name: Kopf, Aglaja
id: 31DAC7B6-F248-11E8-B48F-1D18A9856A87
last_name: Kopf
orcid: 0000-0002-2187-6656
citation:
ama: Kopf A. The implication of cytoskeletal dynamics on leukocyte migration. 2019.
doi:10.15479/AT:ISTA:6891
apa: Kopf, A. (2019). The implication of cytoskeletal dynamics on leukocyte migration.
Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:6891
chicago: Kopf, Aglaja. “The Implication of Cytoskeletal Dynamics on Leukocyte Migration.”
Institute of Science and Technology Austria, 2019. https://doi.org/10.15479/AT:ISTA:6891.
ieee: A. Kopf, “The implication of cytoskeletal dynamics on leukocyte migration,”
Institute of Science and Technology Austria, 2019.
ista: Kopf A. 2019. The implication of cytoskeletal dynamics on leukocyte migration.
Institute of Science and Technology Austria.
mla: Kopf, Aglaja. The Implication of Cytoskeletal Dynamics on Leukocyte Migration.
Institute of Science and Technology Austria, 2019, doi:10.15479/AT:ISTA:6891.
short: A. Kopf, The Implication of Cytoskeletal Dynamics on Leukocyte Migration,
Institute of Science and Technology Austria, 2019.
date_created: 2019-09-19T08:19:44Z
date_published: 2019-07-24T00:00:00Z
date_updated: 2023-10-18T08:49:17Z
day: '24'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: MiSi
doi: 10.15479/AT:ISTA:6891
file:
- access_level: closed
checksum: 00d100d6468e31e583051e0a006b640c
content_type: application/vnd.openxmlformats-officedocument.wordprocessingml.document
creator: akopf
date_created: 2019-10-15T05:28:42Z
date_updated: 2020-10-17T22:30:03Z
embargo_to: open_access
file_id: '6950'
file_name: Kopf_PhD_Thesis.docx
file_size: 74735267
relation: source_file
- access_level: open_access
checksum: 5d1baa899993ae6ca81aebebe1797000
content_type: application/pdf
creator: akopf
date_created: 2019-10-15T05:28:47Z
date_updated: 2020-10-17T22:30:03Z
embargo: 2020-10-16
file_id: '6951'
file_name: Kopf_PhD_Thesis1.pdf
file_size: 52787224
relation: main_file
file_date_updated: 2020-10-17T22:30:03Z
has_accepted_license: '1'
keyword:
- cell biology
- immunology
- leukocyte
- migration
- microfluidics
language:
- iso: eng
month: '07'
oa: 1
oa_version: Published Version
page: '171'
project:
- _id: 265E2996-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: W01250-B20
name: Nano-Analytics of Cellular Systems
publication_identifier:
eissn:
- 2663-337X
isbn:
- 978-3-99078-002-2
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
link:
- relation: press_release
url: https://ist.ac.at/en/news/feeling-like-a-cell/
record:
- id: '6328'
relation: part_of_dissertation
status: public
- id: '15'
relation: part_of_dissertation
status: public
- id: '6877'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Michael K
full_name: Sixt, Michael K
id: 41E9FBEA-F248-11E8-B48F-1D18A9856A87
last_name: Sixt
orcid: 0000-0002-6620-9179
title: The implication of cytoskeletal dynamics on leukocyte migration
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2019'
...
---
_id: '6894'
abstract:
- lang: eng
text: "Hybrid automata combine finite automata and dynamical systems, and model
the interaction of digital with physical systems. Formal analysis that can guarantee
the safety of all behaviors or rigorously witness failures, while unsolvable in
general, has been tackled algorithmically using, e.g., abstraction, bounded model-checking,
assisted theorem proving.\r\nNevertheless, very few methods have addressed the
time-unbounded reachability analysis of hybrid automata and, for current sound
and automatic tools, scalability remains critical. We develop methods for the
polyhedral abstraction of hybrid automata, which construct coarse overapproximations
and tightens them incrementally, in a CEGAR fashion. We use template polyhedra,
i.e., polyhedra whose facets are normal to a given set of directions.\r\nWhile,
previously, directions were given by the user, we introduce (1) the first method\r\nfor
computing template directions from spurious counterexamples, so as to generalize
and\r\neliminate them. The method applies naturally to convex hybrid automata,
i.e., hybrid\r\nautomata with (possibly non-linear) convex constraints on derivatives
only, while for linear\r\nODE requires further abstraction. Specifically, we introduce
(2) the conic abstractions,\r\nwhich, partitioning the state space into appropriate
(possibly non-uniform) cones, divide\r\ncurvy trajectories into relatively straight
sections, suitable for polyhedral abstractions.\r\nFinally, we introduce (3) space-time
interpolation, which, combining interval arithmetic\r\nand template refinement,
computes appropriate (possibly non-uniform) time partitioning\r\nand template
directions along spurious trajectories, so as to eliminate them.\r\nWe obtain
sound and automatic methods for the reachability analysis over dense\r\nand unbounded
time of convex hybrid automata and hybrid automata with linear ODE.\r\nWe build
prototype tools and compare—favorably—our methods against the respective\r\nstate-of-the-art
tools, on several benchmarks."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Mirco
full_name: Giacobbe, Mirco
id: 3444EA5E-F248-11E8-B48F-1D18A9856A87
last_name: Giacobbe
orcid: 0000-0001-8180-0904
citation:
ama: Giacobbe M. Automatic time-unbounded reachability analysis of hybrid systems.
2019. doi:10.15479/AT:ISTA:6894
apa: Giacobbe, M. (2019). Automatic time-unbounded reachability analysis of hybrid
systems. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:6894
chicago: Giacobbe, Mirco. “Automatic Time-Unbounded Reachability Analysis of Hybrid
Systems.” Institute of Science and Technology Austria, 2019. https://doi.org/10.15479/AT:ISTA:6894.
ieee: M. Giacobbe, “Automatic time-unbounded reachability analysis of hybrid systems,”
Institute of Science and Technology Austria, 2019.
ista: Giacobbe M. 2019. Automatic time-unbounded reachability analysis of hybrid
systems. Institute of Science and Technology Austria.
mla: Giacobbe, Mirco. Automatic Time-Unbounded Reachability Analysis of Hybrid
Systems. Institute of Science and Technology Austria, 2019, doi:10.15479/AT:ISTA:6894.
short: M. Giacobbe, Automatic Time-Unbounded Reachability Analysis of Hybrid Systems,
Institute of Science and Technology Austria, 2019.
date_created: 2019-09-22T14:08:44Z
date_published: 2019-09-30T00:00:00Z
date_updated: 2023-09-19T09:30:43Z
day: '30'
ddc:
- '000'
degree_awarded: PhD
department:
- _id: ToHe
doi: 10.15479/AT:ISTA:6894
file:
- access_level: open_access
checksum: 773beaf4a85dc2acc2c12b578fbe1965
content_type: application/pdf
creator: mgiacobbe
date_created: 2019-09-27T14:15:05Z
date_updated: 2020-07-14T12:47:43Z
file_id: '6916'
file_name: giacobbe_thesis.pdf
file_size: 4100685
relation: main_file
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checksum: 97f1c3da71feefd27e6e625d32b4c75b
content_type: application/gzip
creator: mgiacobbe
date_created: 2019-09-27T14:22:04Z
date_updated: 2020-07-14T12:47:43Z
file_id: '6917'
file_name: giacobbe_thesis_src.tar.gz
file_size: 7959732
relation: source_file
file_date_updated: 2020-07-14T12:47:43Z
has_accepted_license: '1'
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: '132'
publication_identifier:
eissn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
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- id: '647'
relation: part_of_dissertation
status: public
- id: '140'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Thomas A
full_name: Henzinger, Thomas A
id: 40876CD8-F248-11E8-B48F-1D18A9856A87
last_name: Henzinger
orcid: 0000−0002−2985−7724
title: Automatic time-unbounded reachability analysis of hybrid systems
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2019'
...
---
_id: '6957'
abstract:
- lang: eng
text: "In many shear flows like pipe flow, plane Couette flow, plane Poiseuille
flow, etc. turbulence emerges subcritically. Here, when subjected to strong enough
perturbations, the flow becomes turbulent in spite of the laminar base flow being
linearly stable. The nature of this instability has puzzled the scientific community
for decades. At onset, turbulence appears in localized patches and flows are spatio-temporally
intermittent. In pipe flow the localized turbulent structures are referred to
as puffs and in planar flows like plane Couette and channel flow, patches arise
in the form of localized oblique bands. In this thesis, we study the onset of
turbulence in channel flow in direct numerical simulations from a dynamical system
theory perspective, as well as by performing experiments in a large aspect ratio
channel.\r\n\r\nThe aim of the experimental work is to determine the critical
Reynolds number where turbulence first becomes sustained. Recently, the onset
of turbulence has been described in analogy to absorbing state phase transition
(i.e. directed percolation). In particular, it has been shown that the critical
point can be estimated from the competition between spreading and decay processes.
Here, by performing experiments, we identify the mechanisms underlying turbulence
proliferation in channel flow and find the critical Reynolds number, above which
turbulence becomes sustained. Above the critical point, the continuous growth
at the tip of the stripes outweighs the stochastic shedding of turbulent patches
at the tail and the stripes expand. For growing stripes, the probability to decay
decreases while the probability of stripe splitting increases. Consequently, and
unlike for the puffs in pipe flow, neither of these two processes is time-independent
i.e. memoryless. Coupling between stripe expansion and creation of new stripes
via splitting leads to a significantly lower critical point ($Re_c=670+/-10$)
than most earlier studies suggest. \r\n\r\nWhile the above approach sheds light
on how turbulence first becomes sustained, it provides no insight into the origin
of the stripes themselves. In the numerical part of the thesis we investigate
how turbulent stripes form from invariant solutions of the Navier-Stokes equations.
The origin of these turbulent stripes can be identified by applying concepts from
the dynamical system theory. In doing so, we identify the exact coherent structures
underlying stripes and their bifurcations and how they give rise to the turbulent
attractor in phase space. We first report a family of localized nonlinear traveling
wave solutions of the Navier-Stokes equations in channel flow. These solutions
show structural similarities with turbulent stripes in experiments like obliqueness,
quasi-streamwise streaks and vortices, etc. A parametric study of these traveling
wave solution is performed, with parameters like Reynolds number, stripe tilt
angle and domain size, including the stability of the solutions. These solutions
emerge through saddle-node bifurcations and form a phase space skeleton for the
turbulent stripes observed in the experiments. The lower branches of these TW
solutions at different tilt angles undergo Hopf bifurcation and new solutions
branches of relative periodic orbits emerge. These RPO solutions do not belong
to the same family and therefore the routes to chaos for different angles are
different. \r\n\r\nIn shear flows, turbulence at onset is transient in nature.
\ Consequently,turbulence can not be tracked to lower Reynolds numbers, where
the dynamics may simplify. Before this happens, turbulence becomes short-lived
and laminarizes. In the last part of the thesis, we show that using numerical
simulations we can continue turbulent stripes in channel flow past the 'relaminarization
barrier' all the way to their origin. Here, turbulent stripe dynamics simplifies
and the fluctuations are no longer stochastic and the stripe settles down to a
relative periodic orbit. This relative periodic orbit originates from the aforementioned
traveling wave solutions. Starting from the relative periodic orbit, a small increase
in speed i.e. Reynolds number gives rise to chaos and the attractor dimension
sharply increases in contrast to the classical transition scenario where the instabilities
affect the flow globally and give rise to much more gradual route to turbulence."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Chaitanya S
full_name: Paranjape, Chaitanya S
id: 3D85B7C4-F248-11E8-B48F-1D18A9856A87
last_name: Paranjape
citation:
ama: Paranjape CS. Onset of turbulence in plane Poiseuille flow. 2019. doi:10.15479/AT:ISTA:6957
apa: Paranjape, C. S. (2019). Onset of turbulence in plane Poiseuille flow.
Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:6957
chicago: Paranjape, Chaitanya S. “Onset of Turbulence in Plane Poiseuille Flow.”
Institute of Science and Technology Austria, 2019. https://doi.org/10.15479/AT:ISTA:6957.
ieee: C. S. Paranjape, “Onset of turbulence in plane Poiseuille flow,” Institute
of Science and Technology Austria, 2019.
ista: Paranjape CS. 2019. Onset of turbulence in plane Poiseuille flow. Institute
of Science and Technology Austria.
mla: Paranjape, Chaitanya S. Onset of Turbulence in Plane Poiseuille Flow.
Institute of Science and Technology Austria, 2019, doi:10.15479/AT:ISTA:6957.
short: C.S. Paranjape, Onset of Turbulence in Plane Poiseuille Flow, Institute of
Science and Technology Austria, 2019.
date_created: 2019-10-22T12:08:43Z
date_published: 2019-10-24T00:00:00Z
date_updated: 2023-09-07T12:53:25Z
day: '24'
ddc:
- '532'
degree_awarded: PhD
department:
- _id: BjHo
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keyword:
- Instabilities
- Turbulence
- Nonlinear dynamics
language:
- iso: eng
month: '10'
oa: 1
oa_version: Published Version
page: '138'
publication_identifier:
eissn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
status: public
supervisor:
- first_name: Björn
full_name: Hof, Björn
id: 3A374330-F248-11E8-B48F-1D18A9856A87
last_name: Hof
orcid: 0000-0003-2057-2754
title: Onset of turbulence in plane Poiseuille flow
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2019'
...
---
_id: '7172'
abstract:
- lang: eng
text: "The development and growth of Arabidopsis thaliana is regulated by a combination
of genetic programing and also by the environmental influences. An important role
in these processes play the phytohormones and among them, auxin is crucial as
it controls many important functions. It is transported through the whole plant
body by creating local and temporal concentration maxima and minima, which have
an impact on the cell status, tissue and organ identity. Auxin has the property
to undergo a directional and finely regulated cell-to-cell transport, which is
enabled by the transport proteins, localized on the plasma membrane. An important
role in this process have the PIN auxin efflux proteins, which have an asymmetric/polar
subcellular localization and determine the directionality of the auxin transport.
During the last years, there were significant advances in understanding how the
trafficking molecular machineries function, including studies on molecular interactions,
function, subcellular localization and intracellular distribution. However, there
is still a lack of detailed characterization on the steps of endocytosis, exocytosis,
endocytic recycling and degradation. Due to this fact, I focused on the identification
of novel trafficking factors and better characterization of the intracellular
trafficking pathways. My PhD thesis consists of an introductory chapter, three
experimental chapters, a chapter containing general discussion, conclusions and
perspectives and also an appendix chapter with published collaborative papers.\r\nThe
first chapter is separated in two different parts: I start by a general introduction
to auxin biology and then I introduce the trafficking pathways in the model plant
Arabidopsis thaliana. Then, I explain also the phosphorylation-signals for polar
targeting and also the roles of the phytohormone strigolactone.\r\nThe second
chapter includes the characterization of bar1/sacsin mutant, which was identified
in a forward genetic screen for novel trafficking components in Arabidopsis thaliana,
where by the implementation of an EMS-treated pPIN1::PIN1-GFP marker line and
by using the established inhibitor of ARF-GEFs, Brefeldin A (BFA) as a tool to
study trafficking processes, we identified a novel factor, which is mediating
the adaptation of the plant cell to ARF-GEF inhibition. The mutation is in a previously
uncharacterized gene, encoding a very big protein that we, based on its homologies,
called SACSIN with domains suggesting roles as a molecular chaperon or as a component
of the ubiquitin-proteasome system. Our physiology and imaging studies revealed
that SACSIN is a crucial plant cell component of the adaptation to the ARF-GEF
inhibition.\r\nThe third chapter includes six subchapters, where I focus on the
role of the phytohormone strigolactone, which interferes with auxin feedback on
PIN internalization. Strigolactone moderates the polar auxin transport by increasing
the internalization of the PIN auxin efflux carriers, which reduces the canalization
related growth responses. In addition, I also studied the role of phosphorylation
in the strigolactone regulation of auxin feedback on PIN internalization. In this
chapter I also present my results on the MAX2-dependence of strigolactone-mediated
root growth inhibition and I also share my results on the auxin metabolomics profiling
after application of GR24.\r\nIn the fourth chapter I studied the effect of two
small molecules ES-9 and ES9-17, which were identified from a collection of small
molecules with the property to impair the clathrin-mediated endocytosis.\r\nIn
the fifth chapter, I discuss all my observations and experimental findings and
suggest alternative hypothesis to interpret my results.\r\nIn the appendix there
are three collaborative published projects. In the first, I participated in the
characterization of the role of ES9 as a small molecule, which is inhibitor of
clathrin- mediated endocytosis in different model organisms. In the second paper,
I contributed to the characterization of another small molecule ES9-17, which
is a non-protonophoric analog of ES9 and also impairs the clathrin-mediated endocytosis
not only in plant cells, but also in mammalian HeLa cells. Last but not least,
I also attach another paper, where I tried to establish the grafting method as
a technique in our lab to study canalization related processes."
acknowledged_ssus:
- _id: LifeSc
- _id: Bio
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Mina K
full_name: Vasileva, Mina K
id: 3407EB18-F248-11E8-B48F-1D18A9856A87
last_name: Vasileva
citation:
ama: Vasileva MK. Molecular mechanisms of endomembrane trafficking in Arabidopsis
thaliana. 2019. doi:10.15479/AT:ISTA:7172
apa: Vasileva, M. K. (2019). Molecular mechanisms of endomembrane trafficking
in Arabidopsis thaliana. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:7172
chicago: Vasileva, Mina K. “Molecular Mechanisms of Endomembrane Trafficking in
Arabidopsis Thaliana.” Institute of Science and Technology Austria, 2019. https://doi.org/10.15479/AT:ISTA:7172.
ieee: M. K. Vasileva, “Molecular mechanisms of endomembrane trafficking in Arabidopsis
thaliana,” Institute of Science and Technology Austria, 2019.
ista: Vasileva MK. 2019. Molecular mechanisms of endomembrane trafficking in Arabidopsis
thaliana. Institute of Science and Technology Austria.
mla: Vasileva, Mina K. Molecular Mechanisms of Endomembrane Trafficking in Arabidopsis
Thaliana. Institute of Science and Technology Austria, 2019, doi:10.15479/AT:ISTA:7172.
short: M.K. Vasileva, Molecular Mechanisms of Endomembrane Trafficking in Arabidopsis
Thaliana, Institute of Science and Technology Austria, 2019.
date_created: 2019-12-11T21:24:39Z
date_published: 2019-12-12T00:00:00Z
date_updated: 2025-05-07T11:12:29Z
day: '12'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: JiFr
doi: 10.15479/AT:ISTA:7172
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creator: mvasilev
date_created: 2019-12-12T09:32:36Z
date_updated: 2020-07-14T12:47:51Z
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language:
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month: '12'
oa: 1
oa_version: Published Version
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publication_identifier:
eissn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
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relation: part_of_dissertation
status: public
- id: '449'
relation: part_of_dissertation
status: public
- id: '1346'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Jiří
full_name: Friml, Jiří
id: 4159519E-F248-11E8-B48F-1D18A9856A87
last_name: Friml
orcid: 0000-0002-8302-7596
title: Molecular mechanisms of endomembrane trafficking in Arabidopsis thaliana
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2019'
...