---
_id: '7186'
abstract:
- lang: eng
text: "Tissue morphogenesis in developmental or physiological processes is regulated
by molecular\r\nand mechanical signals. While the molecular signaling cascades
are increasingly well\r\ndescribed, the mechanical signals affecting tissue shape
changes have only recently been\r\nstudied in greater detail. To gain more insight
into the mechanochemical and biophysical\r\nbasis of an epithelial spreading process
(epiboly) in early zebrafish development, we studied\r\ncell-cell junction formation
and actomyosin network dynamics at the boundary between\r\nsurface layer epithelial
cells (EVL) and the yolk syncytial layer (YSL). During zebrafish epiboly,\r\nthe
cell mass sitting on top of the yolk cell spreads to engulf the yolk cell by the
end of\r\ngastrulation. It has been previously shown that an actomyosin ring residing
within the YSL\r\npulls on the EVL tissue through a cable-constriction and a flow-friction
motor, thereby\r\ndragging the tissue vegetal wards. Pulling forces are likely
transmitted from the YSL\r\nactomyosin ring to EVL cells; however, the nature
and formation of the junctional structure\r\nmediating this process has not been
well described so far. Therefore, our main aim was to\r\ndetermine the nature,
dynamics and potential function of the EVL-YSL junction during this\r\nepithelial
tissue spreading. Specifically, we show that the EVL-YSL junction is a\r\nmechanosensitive
structure, predominantly made of tight junction (TJ) proteins. The process\r\nof
TJ mechanosensation depends on the retrograde flow of non-junctional, phase-separated\r\nZonula
Occludens-1 (ZO-1) protein clusters towards the EVL-YSL boundary. Interestingly,
we\r\ncould demonstrate that ZO-1 is present in a non-junctional pool on the surface
of the yolk\r\ncell, and ZO-1 undergoes a phase separation process that likely
renders the protein\r\nresponsive to flows. These flows are directed towards the
junction and mediate proper\r\ntension-dependent recruitment of ZO-1. Upon reaching
the EVL-YSL junction ZO-1 gets\r\nincorporated into the junctional pool mediated
through its direct actin-binding domain.\r\nWhen the non-junctional pool and/or
ZO-1 direct actin binding is absent, TJs fail in their\r\nproper mechanosensitive
responses resulting in slower tissue spreading. We could further\r\ndemonstrate
that depletion of ZO proteins within the YSL results in diminished actomyosin\r\nring
formation. This suggests that a mechanochemical feedback loop is at work during\r\nzebrafish
epiboly: ZO proteins help in proper actomyosin ring formation and actomyosin\r\ncontractility
and flows positively influence ZO-1 junctional recruitment. Finally, such a\r\nmesoscale
polarization process mediated through the flow of phase-separated protein\r\nclusters
might have implications for other processes such as immunological synapse\r\nformation,
C. elegans zygote polarization and wound healing."
acknowledged_ssus:
- _id: Bio
- _id: LifeSc
- _id: EM-Fac
- _id: SSU
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Cornelia
full_name: Schwayer, Cornelia
id: 3436488C-F248-11E8-B48F-1D18A9856A87
last_name: Schwayer
orcid: 0000-0001-5130-2226
citation:
ama: Schwayer C. Mechanosensation of tight junctions depends on ZO-1 phase separation
and flow. 2019. doi:10.15479/AT:ISTA:7186
apa: Schwayer, C. (2019). Mechanosensation of tight junctions depends on ZO-1
phase separation and flow. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:7186
chicago: Schwayer, Cornelia. “Mechanosensation of Tight Junctions Depends on ZO-1
Phase Separation and Flow.” Institute of Science and Technology Austria, 2019.
https://doi.org/10.15479/AT:ISTA:7186.
ieee: C. Schwayer, “Mechanosensation of tight junctions depends on ZO-1 phase separation
and flow,” Institute of Science and Technology Austria, 2019.
ista: Schwayer C. 2019. Mechanosensation of tight junctions depends on ZO-1 phase
separation and flow. Institute of Science and Technology Austria.
mla: Schwayer, Cornelia. Mechanosensation of Tight Junctions Depends on ZO-1
Phase Separation and Flow. Institute of Science and Technology Austria, 2019,
doi:10.15479/AT:ISTA:7186.
short: C. Schwayer, Mechanosensation of Tight Junctions Depends on ZO-1 Phase Separation
and Flow, Institute of Science and Technology Austria, 2019.
date_created: 2019-12-16T14:26:14Z
date_published: 2019-12-16T00:00:00Z
date_updated: 2023-09-07T12:56:42Z
day: '16'
ddc:
- '570'
degree_awarded: PhD
department:
- _id: CaHe
doi: 10.15479/AT:ISTA:7186
file:
- access_level: closed
checksum: 585583c1c875c5d9525703a539668a7c
content_type: application/zip
creator: cschwayer
date_created: 2019-12-19T15:18:11Z
date_updated: 2020-07-14T12:47:52Z
file_id: '7194'
file_name: DocumentSourceFiles.zip
file_size: 19431292
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checksum: 9b9b24351514948d27cec659e632e2cd
content_type: application/pdf
creator: cschwayer
date_created: 2019-12-19T15:19:21Z
date_updated: 2020-07-14T12:47:52Z
file_id: '7195'
file_name: Thesis_CS_final.pdf
file_size: 19226428
relation: main_file
file_date_updated: 2020-07-14T12:47:52Z
has_accepted_license: '1'
language:
- iso: eng
month: '12'
oa: 1
oa_version: Published Version
page: '107'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '1096'
relation: dissertation_contains
status: public
- id: '7001'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Carl-Philipp J
full_name: Heisenberg, Carl-Philipp J
id: 39427864-F248-11E8-B48F-1D18A9856A87
last_name: Heisenberg
orcid: 0000-0002-0912-4566
title: Mechanosensation of tight junctions depends on ZO-1 phase separation and flow
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2019'
...
---
_id: '6681'
abstract:
- lang: eng
text: "The first part of the thesis considers the computational aspects of the homotopy
groups πd(X) of a topological space X. It is well known that there is no algorithm
to decide whether the fundamental group π1(X) of a given finite simplicial complex
X is trivial. On the other hand, there are several algorithms that, given a finite
simplicial complex X that is simply connected (i.e., with π1(X) trivial), compute
the higher homotopy group πd(X) for any given d ≥ 2.\r\nHowever, these algorithms
come with a caveat: They compute the isomorphism type of πd(X), d ≥ 2 as an abstract
finitely generated abelian group given by generators and relations, but they work
with very implicit representations of the elements of πd(X). We present an algorithm
that, given a simply connected space X, computes πd(X) and represents its elements
as simplicial maps from suitable triangulations of the d-sphere Sd to X. For fixed
d, the algorithm runs in time exponential in size(X), the number of simplices
of X. Moreover, we prove that this is optimal: For every fixed d ≥ 2,\r\nwe construct
a family of simply connected spaces X such that for any simplicial map representing
a generator of πd(X), the size of the triangulation of S d on which the map is
defined, is exponential in size(X).\r\nIn the second part of the thesis, we prove
that the following question is algorithmically undecidable for d < ⌊3(k+1)/2⌋,
k ≥ 5 and (k, d) ̸= (5, 7), which covers essentially everything outside the meta-stable
range: Given a finite simplicial complex K of dimension k, decide whether there
exists a piecewise-linear (i.e., linear on an arbitrarily fine subdivision of
K) embedding f : K ↪→ Rd of K into a d-dimensional Euclidean space."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Stephan Y
full_name: Zhechev, Stephan Y
id: 3AA52972-F248-11E8-B48F-1D18A9856A87
last_name: Zhechev
citation:
ama: Zhechev SY. Algorithmic aspects of homotopy theory and embeddability. 2019.
doi:10.15479/AT:ISTA:6681
apa: Zhechev, S. Y. (2019). Algorithmic aspects of homotopy theory and embeddability.
Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:6681
chicago: Zhechev, Stephan Y. “Algorithmic Aspects of Homotopy Theory and Embeddability.”
Institute of Science and Technology Austria, 2019. https://doi.org/10.15479/AT:ISTA:6681.
ieee: S. Y. Zhechev, “Algorithmic aspects of homotopy theory and embeddability,”
Institute of Science and Technology Austria, 2019.
ista: Zhechev SY. 2019. Algorithmic aspects of homotopy theory and embeddability.
Institute of Science and Technology Austria.
mla: Zhechev, Stephan Y. Algorithmic Aspects of Homotopy Theory and Embeddability.
Institute of Science and Technology Austria, 2019, doi:10.15479/AT:ISTA:6681.
short: S.Y. Zhechev, Algorithmic Aspects of Homotopy Theory and Embeddability, Institute
of Science and Technology Austria, 2019.
date_created: 2019-07-26T11:14:34Z
date_published: 2019-08-08T00:00:00Z
date_updated: 2023-09-07T13:10:36Z
day: '08'
ddc:
- '514'
degree_awarded: PhD
department:
- _id: UlWa
doi: 10.15479/AT:ISTA:6681
file:
- access_level: open_access
checksum: 3231e7cbfca3b5687366f84f0a57a0c0
content_type: application/pdf
creator: szhechev
date_created: 2019-08-07T13:02:50Z
date_updated: 2020-07-14T12:47:37Z
file_id: '6771'
file_name: Stephan_Zhechev_thesis.pdf
file_size: 1464227
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checksum: 85d65eb27b4377a9e332ee37a70f08b6
content_type: application/octet-stream
creator: szhechev
date_created: 2019-08-07T13:03:22Z
date_updated: 2020-07-14T12:47:37Z
file_id: '6772'
file_name: Stephan_Zhechev_thesis.tex
file_size: 303988
relation: source_file
- access_level: closed
checksum: 86b374d264ca2dd53e712728e253ee75
content_type: application/zip
creator: szhechev
date_created: 2019-08-07T13:03:34Z
date_updated: 2020-07-14T12:47:37Z
file_id: '6773'
file_name: supplementary_material.zip
file_size: 1087004
relation: supplementary_material
file_date_updated: 2020-07-14T12:47:37Z
has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
month: '08'
oa: 1
oa_version: Published Version
page: '104'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '6774'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
title: Algorithmic aspects of homotopy theory and embeddability
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: '8182'
abstract:
- lang: eng
text: "Suppose that $n\\neq p^k$ and $n\\neq 2p^k$ for all $k$ and all primes $p$.
We prove that for any Hausdorff compactum $X$ with a free action of the symmetric
group $\\mathfrak S_n$ there exists an $\\mathfrak S_n$-equivariant map $X \\to\r\n{\\mathbb
R}^n$ whose image avoids the diagonal $\\{(x,x\\dots,x)\\in {\\mathbb R}^n|x\\in
{\\mathbb R}\\}$.\r\n Previously, the special cases of this statement for certain
$X$ were usually proved using the equivartiant obstruction theory. Such calculations
are difficult and may become infeasible past the first (primary) obstruction.
We\r\ntake a different approach which allows us to prove the vanishing of all
obstructions simultaneously. The essential step in the proof is classifying the
possible degrees of $\\mathfrak S_n$-equivariant maps from the boundary\r\n$\\partial\\Delta^{n-1}$
of $(n-1)$-simplex to itself. Existence of equivariant maps between spaces is
important for many questions arising from discrete mathematics and geometry, such
as Kneser's conjecture, the Square Peg conjecture, the Splitting Necklace problem,
and the Topological Tverberg conjecture, etc. We demonstrate the utility of our
result applying it to one such question, a specific instance of envy-free division
problem."
article_number: '1910.12628'
article_processing_charge: No
author:
- first_name: Sergey
full_name: Avvakumov, Sergey
id: 3827DAC8-F248-11E8-B48F-1D18A9856A87
last_name: Avvakumov
- first_name: Sergey
full_name: Kudrya, Sergey
id: ecf01965-d252-11ea-95a5-8ada5f6c6a67
last_name: Kudrya
citation:
ama: Avvakumov S, Kudrya S. Vanishing of all equivariant obstructions and the mapping
degree. arXiv.
apa: Avvakumov, S., & Kudrya, S. (n.d.). Vanishing of all equivariant obstructions
and the mapping degree. arXiv. arXiv.
chicago: Avvakumov, Sergey, and Sergey Kudrya. “Vanishing of All Equivariant Obstructions
and the Mapping Degree.” ArXiv. arXiv, n.d.
ieee: S. Avvakumov and S. Kudrya, “Vanishing of all equivariant obstructions and
the mapping degree,” arXiv. arXiv.
ista: Avvakumov S, Kudrya S. Vanishing of all equivariant obstructions and the mapping
degree. arXiv, 1910.12628.
mla: Avvakumov, Sergey, and Sergey Kudrya. “Vanishing of All Equivariant Obstructions
and the Mapping Degree.” ArXiv, 1910.12628, arXiv.
short: S. Avvakumov, S. Kudrya, ArXiv (n.d.).
date_created: 2020-07-30T10:45:08Z
date_published: 2019-10-28T00:00:00Z
date_updated: 2023-09-07T13:12:17Z
day: '28'
department:
- _id: UlWa
external_id:
arxiv:
- '1910.12628'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1910.12628
month: '10'
oa: 1
oa_version: Preprint
project:
- _id: 26611F5C-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: P31312
name: Algorithms for Embeddings and Homotopy Theory
publication: arXiv
publication_status: submitted
publisher: arXiv
related_material:
record:
- id: '11446'
relation: later_version
status: public
- id: '8156'
relation: dissertation_contains
status: public
status: public
title: Vanishing of all equivariant obstructions and the mapping degree
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2019'
...
---
_id: '8185'
abstract:
- lang: eng
text: "In this paper we study envy-free division problems. The classical approach
to some of such problems, used by David Gale, reduces to considering continuous
maps of a simplex to itself and finding sufficient conditions when this map hits
the center of the simplex. The mere continuity is not sufficient for such a conclusion,
the usual assumption (for example, in the Knaster--Kuratowski--Mazurkiewicz and
the Gale theorem) is a certain boundary condition.\r\n We follow Erel Segal-Halevi,
Fr\\'ed\\'eric Meunier, and Shira Zerbib, and replace the boundary condition by
another assumption, which has the economic meaning of possibility for a player
to prefer an empty part in the segment\r\npartition problem. We solve the problem
positively when $n$, the number of players that divide the segment, is a prime
power, and we provide counterexamples for every $n$ which is not a prime power.
We also provide counterexamples relevant to a wider class of fair or envy-free
partition problems when $n$ is odd and not a prime power."
article_number: '1907.11183'
article_processing_charge: No
author:
- first_name: Sergey
full_name: Avvakumov, Sergey
id: 3827DAC8-F248-11E8-B48F-1D18A9856A87
last_name: Avvakumov
- first_name: Roman
full_name: Karasev, Roman
last_name: Karasev
citation:
ama: Avvakumov S, Karasev R. Envy-free division using mapping degree. arXiv.
doi:10.48550/arXiv.1907.11183
apa: Avvakumov, S., & Karasev, R. (n.d.). Envy-free division using mapping degree.
arXiv. https://doi.org/10.48550/arXiv.1907.11183
chicago: Avvakumov, Sergey, and Roman Karasev. “Envy-Free Division Using Mapping
Degree.” ArXiv, n.d. https://doi.org/10.48550/arXiv.1907.11183.
ieee: S. Avvakumov and R. Karasev, “Envy-free division using mapping degree,” arXiv.
.
ista: Avvakumov S, Karasev R. Envy-free division using mapping degree. arXiv, 1907.11183.
mla: Avvakumov, Sergey, and Roman Karasev. “Envy-Free Division Using Mapping Degree.”
ArXiv, 1907.11183, doi:10.48550/arXiv.1907.11183.
short: S. Avvakumov, R. Karasev, ArXiv (n.d.).
date_created: 2020-07-30T10:45:51Z
date_published: 2019-07-25T00:00:00Z
date_updated: 2023-09-07T13:12:17Z
day: '25'
department:
- _id: UlWa
doi: 10.48550/arXiv.1907.11183
external_id:
arxiv:
- '1907.11183'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1907.11183
month: '07'
oa: 1
oa_version: Preprint
project:
- _id: 26611F5C-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: P31312
name: Algorithms for Embeddings and Homotopy Theory
publication: arXiv
publication_status: submitted
related_material:
link:
- relation: later_version
url: https://doi.org/10.1112/mtk.12059
record:
- id: '8156'
relation: dissertation_contains
status: public
status: public
title: Envy-free division using mapping degree
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2019'
...
---
_id: '7524'
abstract:
- lang: eng
text: "We prove a lower bound for the free energy (per unit volume) of the two-dimensional
Bose gas in the thermodynamic limit. We show that the free energy at density $\\rho$
and inverse temperature $\\beta$ differs from the one of the non-interacting system
by the correction term $4 \\pi \\rho^2 |\\ln a^2 \\rho|^{-1} (2 - [1 - \\beta_{\\mathrm{c}}/\\beta]_+^2)$.
Here $a$ is the scattering length of the interaction potential, $[\\cdot]_+ =
\\max\\{ 0, \\cdot \\}$ and $\\beta_{\\mathrm{c}}$ is the inverse Berezinskii--Kosterlitz--Thouless
critical temperature for superfluidity. The result is valid in the dilute limit\r\n$a^2\\rho
\\ll 1$ and if $\\beta \\rho \\gtrsim 1$."
article_processing_charge: No
author:
- first_name: Andreas
full_name: Deuchert, Andreas
id: 4DA65CD0-F248-11E8-B48F-1D18A9856A87
last_name: Deuchert
orcid: 0000-0003-3146-6746
- first_name: Simon
full_name: Mayer, Simon
id: 30C4630A-F248-11E8-B48F-1D18A9856A87
last_name: Mayer
- first_name: Robert
full_name: Seiringer, Robert
id: 4AFD0470-F248-11E8-B48F-1D18A9856A87
last_name: Seiringer
orcid: 0000-0002-6781-0521
citation:
ama: Deuchert A, Mayer S, Seiringer R. The free energy of the two-dimensional dilute
Bose gas. I. Lower bound. arXiv:191003372.
apa: Deuchert, A., Mayer, S., & Seiringer, R. (n.d.). The free energy of the
two-dimensional dilute Bose gas. I. Lower bound. arXiv:1910.03372. ArXiv.
chicago: Deuchert, Andreas, Simon Mayer, and Robert Seiringer. “The Free Energy
of the Two-Dimensional Dilute Bose Gas. I. Lower Bound.” ArXiv:1910.03372.
ArXiv, n.d.
ieee: A. Deuchert, S. Mayer, and R. Seiringer, “The free energy of the two-dimensional
dilute Bose gas. I. Lower bound,” arXiv:1910.03372. ArXiv.
ista: Deuchert A, Mayer S, Seiringer R. The free energy of the two-dimensional dilute
Bose gas. I. Lower bound. arXiv:1910.03372, .
mla: Deuchert, Andreas, et al. “The Free Energy of the Two-Dimensional Dilute Bose
Gas. I. Lower Bound.” ArXiv:1910.03372, ArXiv.
short: A. Deuchert, S. Mayer, R. Seiringer, ArXiv:1910.03372 (n.d.).
date_created: 2020-02-26T08:46:40Z
date_published: 2019-10-08T00:00:00Z
date_updated: 2023-09-07T13:12:41Z
day: '08'
department:
- _id: RoSe
ec_funded: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1910.03372
month: '10'
oa: 1
oa_version: Preprint
page: '61'
project:
- _id: 25C6DC12-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '694227'
name: Analysis of quantum many-body systems
publication: arXiv:1910.03372
publication_status: draft
publisher: ArXiv
related_material:
record:
- id: '7790'
relation: later_version
status: public
- id: '7514'
relation: dissertation_contains
status: public
scopus_import: 1
status: public
title: The free energy of the two-dimensional dilute Bose gas. I. Lower bound
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2019'
...