5,221 research outputs found
Regulation of growth, patterning and cell fate-specification during imaginal disc regeneration in drosophila
No full textThe process of regeneration is immensely complicated and requires the exquisitely precise orchestration of growth, patterning and cell-fate specification. Drosophila melanogaster larval tissues have recently emerged as a useful model organism to study this process. These larval tissues are simple but experience complex gene expression to finally form the adult tissue. As such, Drosophila is an ideal model organism to study the complicated process of regeneration. In this study we have used the experimental tractability of Drosophila to investigate how growth, patterning, cell-fate specification and fate plasticity are regulated in regenerating imaginal discs.
Regenerative growth must be carefully controlled and constrained to prevent overgrowth and to allow correct organization of the regenerating tissue. However, the factors that restrict regenerative growth have not been identified. In this study, we have identified one mechanism that constrains regenerative growth, impairment of which leads to erroneous patterning of the final appendage. Regenerating discs with reduced levels of the RNA-regulator Brain tumor (Brat) exhibit enhanced regeneration but produce adult wings with disrupted margins. The loss of cell-fate specification is due to the aberrantly high expression of the pro-growth factor Myc and the self-renewal factor Chinmo. Thus, Brat ensures that the regenerating tissue forms the proper final structure by constraining expression of pro-regeneration genes.
Dissociation of imaginal disc cells has previously been carried out to enable flow cytometry and cell sorting to analyze cell cycle progression, cell size, gene expression, and other aspects of imaginal tissues. However, the lengthy dissociation protocols employed may alter gene expression, cell behavior and overall viability. In this study, we developed a new rapid and gentle method of dissociating the cells of wing imaginal discs that significantly enhanced cell viability and reduced the likelihood of gene expression changes. This method was successfully used to create a transcriptional profile of the regenerating tissue leading to the identification of many novel regulators of regeneration. We have also extended our investigation of regeneration to the antennal imaginal disc.
Drosophila imaginal discs have also been used to study cell-fate specification and plasticity, including homeotic changes and regeneration-induced transdetermination. In this study, we identified a change from antennal fate to eye fate induced by a Distal-less-GAL4 (DllGAL4) P-element insertion that is a mutant allele of Dll and expresses GAL4 in the antennal imaginal disc. While this fate change was not induced by tissue damage, it appeared to be a hybrid of transdetermination and homeosis. This plasticity appears to be unique to the DllGAL4 line, possibly due to cellular stress induced by the high GAL4 expression combined with the severity of the Dll mutation. Thus, we propose that even in the absence of tissue damage, other forms of cellular stress caused by high GAL4 expression can induce determined cell fates to change, and selector gene mutations can sensitize the tissue to these transformations.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-12-01The student, Syeda Nayab Abidi, accepted the attached license on 2019-11-07 at 12:27.The student, Syeda Nayab Abidi, submitted this Dissertation for approval on 2019-11-07 at 12:54.This Dissertation was approved for publication on 2019-11-11 at 14:20.DSpace SAF Submission Ingestion Package generated from Vireo submission #14532 on 2020-02-28 at 17:21:56Made available in DSpace on 2020-03-02T22:12:16Z (GMT). No. of bitstreams: 2
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Previous issue date: 2019-11-11Embargo set by: Seth Robbins for item 113879
Lift date: 2022-03-02T22:12:26Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 113879
Lift date: 2022-03-02T22:15:21Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 113879
Lift date: 2022-03-02T22:18:25Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 113879 on 2022-03-03T10:15:13Z
Search for the Exclusive W Boson Hadronic Decays W ± → π ± γ , W ± → K ± γ and W ± → ρ ± γ with the ATLAS Detector
No full textA search for the exclusive hadronic decays W ± → π ± γ , W ± → K ± γ , and W ± → ρ ± γ is performed using up to 140 fb − 1 of proton-proton collisions recorded with the ATLAS detector at a center-of-mass energy of s = 13 TeV . If observed, these rare processes would provide a unique test bench for the quantum chromodynamics factorization formalism used to calculate cross sections at colliders. Additionally, at future colliders, these decays could offer a new way to measure the W boson mass through fully reconstructed decay products. The search results in the most stringent upper limits to date on the branching fractions B ( W ± → π ± γ ) < 1.9 × 10 − 6 , B ( W ± → K ± γ ) < 1.7 × 10 − 6 , B ( W ± → ρ ± γ ) < 5.2 × 10 − 6 at 95% confidence level. © 2024 CERN, for the ATLAS Collaboration 2024 CER
Measurement of and production in dileptonic events in collisions at TeV with the ATLAS detector
No full textSimitthus (Chimtou, Tunesien). Vorbericht über die Aktivitäten 2009–2012
No full textK. Abbès, H. Abidi, S. Ardeleanu, S. Arnold, E. Ben Azouz, M. Bues, H. Khanachi, M. Khanoussi, H. Möller, K. Müller, E. Pamberg, P. Scheding, C. Touihri, P. v. Rummel, 2012 Römische Mitteilungen 118, 179–22
Abidi, “Hierarchical approach to enhanced active shape model for color video tracking
No full textTracking and recognizing non-rigid objects in video image sequences are complex tasks of increasing importance to many applications. In this paper, we present a hierarchical realization of an enhanced active shape model for color video tracking and we study the performance of hierarchical and non-hierarchical implementations in the RGB, YUV, and HSI color spaces. 1
Measurement of the nuclear modification factor of b-jets in 5.02 TeV Pb+Pb collisions with the ATLAS detector
No full textAbstract
This paper presents a measurement of b-jet production in Pb+Pb and pp collisions at
s
NN
=
5.02
TeV with the ATLAS detector at the LHC. The measurement uses 260
pb
-
1
of pp collisions collected in 2017 and 1.4
nb
-
1
of Pb+Pb collisions collected in 2018. In both collision systems, jets are reconstructed via the anti-
k
t
algorithm. The b-jets are identified from a sample of jets containing muons from the semileptonic decay of b-quarks using template fits of the muon momentum relative to the jet axis. In pp collisions, b-jets are reconstructed for radius parameters
R
=
0.2
and
R
=
0.4
, and only
R
=
0.2
jets are used in Pb+Pb collisions. For comparison, inclusive
R
=
0.2
jets are also measured using 1.7
nb
-
1
of Pb+Pb collisions collected in 2018 and the same pp collision data as the b-jet measurement. The nuclear modification factor,
R
AA
, is calculated for both b-jets and inclusive jets with
R
=
0.2
over the transverse momentum range of 80–290 GeV. The nuclear modification factor for b-jets decreases from peripheral to central collisions. The ratio of the b-jet
R
AA
to inclusive jet
R
AA
is also presented and suggests that the
R
AA
for b-jets is larger than that for inclusive jets in central Pb+Pb collisions. The measurements are compared with theoretical calculations and suggest a role for mass and colour-charge effects in partonic energy loss in heavy-ion collisions
Search for exclusive Higgs and Z boson decays to ωγ and Higgs boson decays to K⁎γ with the ATLAS detector
No full textNew techniques for jet calibration with the ATLAS detector
No full textA determination of the jet energy scale is presented using proton–proton collision data with a centre-of-mass energy of s = 13 TeV, corresponding to an integrated luminosity of 140 fb - 1 collected using the ATLAS detector at the LHC. Jets are reconstructed using the ATLAS particle-flow method that combines charged-particle tracks and topo-clusters formed from energy deposits in the calorimeter cells. The anti- k t jet algorithm with radius parameter R = 0.4 is used to define the jet. Novel jet energy scale calibration strategies developed for the LHC Run 2 are reported that lay the foundation for the jet calibration in Run 3. Jets are calibrated with a series of simulation-based corrections, including state-of-the-art techniques in jet calibration such as machine learning methods and novel in situ calibrations to achieve better performance than the baseline calibration derived using up to 81 fb 1 of Run 2 data. The performance of these new techniques is then examined in the in situ measurements by exploiting the transverse momentum balance between a jet and a reference object. The b-quark jet energy scale using particle flow jets is measured for the first time with around 1% precision using γ +jet events
A precise measurement of the jet energy scale derived from single-particle measurements and in situ techniques in proton–proton collisions at s = 13 TeV with the ATLAS detector
No full textThe jet energy calibration and its uncertainties are derived from measurements of the calorimeter response to single particles in both data and Monte Carlo simulation using proton–proton collisions at s = 13 TeV collected with the ATLAS detector during Run 2 at the Large Hadron Collider. The jet calibration uncertainty for anti- k T jets with a jet radius parameter of R jet = 0.4 and in the central jet rapidity region is about 2.5% for transverse momenta ( p T ) of 20 GeV , about 0.5 % for p T = 300 GeV and 0.7 % for p T = 4 TeV . Excellent agreement is found with earlier determinations obtained from p T -balance based in situ methods ( Z / γ +jets). The combination of these two independent methods results in the most precise jet energy measurement achieved so far with the ATLAS detector with a relative uncertainty of 0.3 % at p T = 300 GeV and 0.6 % at 4 TeV. The jet energy calibration is also derived with the single-particle calorimeter response measurements separately for quark- and gluon-induced jets and furthermore for jets with R jet varying from 0.2 to 1.0 retaining the correlations between these measurements. Differences between inclusive jets and jets from boosted top-quark decays, with and without grooming the soft jet constituents, are also studied
Searching Personalized -wing in Large and Dynamic Bipartite Graphs
No full textThere are extensive studies focusing on the application scenario that all the
bipartite cohesive subgraphs need to be discovered in a bipartite graph.
However, we observe that, for some applications, one is interested in finding
bipartite cohesive subgraphs containing a specific vertex. In this paper, we
study a new query dependent bipartite cohesive subgraph search problem based on
-wing model, named as the personalized -wing search problem. We introduce
a -wing equivalence relationship to summarize the edges of a bipartite graph
into groups. Therefore, all the edges of are segregated into different
groups, i.e. -wing equivalence class, forming an efficient and wing number
conserving index called EquiWing. Further, we propose a more compact version of
EquiWing, EquiWing-Comp, which is achieved by integrating our proposed
-butterfly loose approach and discovered hierarchy properties. These indices
are used to expedite the personalized -wing search with a non-repetitive
access to , which leads to linear algorithms for searching the personalized
-wing. Moreover, we conduct a thorough study on the maintenance of the
proposed indices for evolving bipartite graphs. We discover novel properties
that help us localize the scope of the maintenance at a low cost. By exploiting
the discoveries, we propose novel algorithms for maintaining the two indices,
which substantially reduces the cost of maintenance. We perform extensive
experimental studies in real, large-scale graphs to validate the efficiency and
effectiveness of EquiWing and EquiWing-Comp compared to the baseline.Comment: 13 pages, 10 figures and 4 table
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