137 research outputs found
Time evolution of a toy semiholographic glasma
We extend our previous study of a toy model for coupling classical Yang-Mills
equations for describing overoccupied gluons at the saturation scale with a
strongly coupled infrared sector modeled by AdS/CFT. Including propagating
modes in the bulk we find that the Yang-Mills sector loses its initial energy
to a growing black hole in the gravity dual such that there is a conserved
energy-momentum tensor for the total system while entropy grows monotonically.
This involves a numerical AdS simulation with a backreacted boundary source far
from equilibrium.Comment: 17 pages, 7 figures, v2: minor changes in section 3 and
acknowledgement
dS2 as excitation of AdS2
Title- dS2 as excitation of AdS2
We introduce a family of 2D dilaton gravity models with state-dependent constant curvature so that dS2 emerges as an excitation of AdS2. Curiously, the strong coupling region corresponds to the asymptotic region geometrically. Apart from these key differences, many features resemble the Almheiri–Polchinski model. We discuss perturbative and non-perturbative thermodynamical stability, bubble nucleation through matter shockwaves, and semiclassical backreaction effects. In some of these models, we find that low temperatures are dominated by AdS2 but high temperatures are dominated by dS2, concurrent with a recent proposal by Susskind
GmbH vs. Privatstiftung
Diese theoretische Arbeit hat zum Ziel die Gesellschaft mit beschränkter Haftung mit der Privatstiftung zu vergleichen. Besonderes Augenmerk wird im Zuge der Arbeit auf die Vorteilhaftigkeit der jeweiligen Rechtsform aus Sicht eines Gründers mit eigennützigen Gründungsinteressen gerichtet. Hierfür wird der Begriff des eigennützigen Gründerinteresses zu Beginn der Arbeit definiert. Anschließend werden verschiedene Entscheidungskriterien herausgearbeitet, anhand derer am Ende der Arbeit versucht wird, eine Entscheidung hinsichtlich der GmbH oder der Privatstiftung zu treffen.
Danach findet der allgemeine Vergleich in den Bereichen des Gesellschaftsrechts, Steuerrechts und der Rechnungslegung statt. Innerhalb dieser Kapitel wird auf verschiedene Teilpunkte der jeweiligen Bereiche eingegangen, um dem Leser eine allgemeine Übersicht über die rechtlichen Bestimmungen der jeweiligen Rechtform zu geben. Anschließend werden die Privatstiftung und die GmbH in den ausgearbeiteten Entscheidungskriterien miteinander verglichen.
Am Ende der Arbeit wird herausgearbeitet und begründet, warum die GmbH für einen eigennützigen Gründer insgesamt vorteilhafter ist. Der Gründer hat nicht nur hinsichtlich der Laufzeit, sondern auch der Beeinflussbarkeit einen großen Handlungsspielraum und damit einen maßgeblichen Vorteil gegenüber der Privatstiftung. Zusätzlich ist das zur Gründung einer GmbH erforderliche Vermögen geringer als bei einer Privatstiftung und sollte für Privatpersonen keine hohe Eintrittsschwelle darstellen. Die Privatstiftung ist demgegenüber nur hinsichtlich der haftungsrechtlichen Bestimmungen und der fehlenden Offenlegungspflicht empfehlenswerter
Equivalences between 2D dilaton gravities, their asymptotic symmetries, and their holographic duals
Dilaton gravities in two dimensions can be formulated as particular Poisson
sigma models. Target space diffeomorphisms map different models to each other
and establish a one-to-one correspondence between their classical solutions. We
obtain a general form of such diffeomorphisms in Lorentzian and Euclidean
signatures and use them to extend known holographic results, including the
Schwarzian action on the asymptotic boundary, from JT to a large class of
dilaton gravity models.Comment: 53 pp, 4 fig
Overcoming Noise in Entanglement Distribution
Noise can be considered the natural enemy of quantum information. An often
implied benefit of high-dimensional entanglement is its increased resilience to
noise. However, manifesting this potential in an experimentally meaningful
fashion is challenging and has never been done before. In infinite dimensional
spaces, discretisation is inevitable and renders the effective dimension of
quantum states a tunable parameter. Owing to advances in experimental
techniques and theoretical tools, we demonstrate an increased resistance to
noise by identifying two pathways to exploit high-dimensional entangled states.
Our study is based on two separate experiments utilising canonical
spatio-temporal properties of entangled photon pairs. Following these different
pathways to noise resilience, we are able to certify entanglement in the
photonic orbital-angular-momentum and energy-time degrees of freedom up to
noise conditions corresponding to a noise fraction of 72 % and 92 %
respectively. Our work paves the way towards practical quantum communication
systems that are able to surpass current noise and distance limitations, while
not compromising on potential device-independence.Comment: 12 pages main text, 7 pages supplementary information, 6 figure
Carroll black holes
Despite the absence of a lightcone structure, some solutions of Carroll
gravity show black hole-like behaviour. We define Carroll black holes as
solutions of Carroll gravity that exhibit Carroll thermal properties and have a
Carroll extremal surface, notions introduced in our work. The latter is a
Carroll analogue of a Lorentzian extremal surface. As examples, we discuss the
Carroll versions of Schwarzschild, Reissner-Nordstr\"om, and BTZ black holes
and black hole solutions of generic 1+1 dimensional Carroll dilaton gravity,
including Carroll JT and Carroll Witten black holes.Comment: 58pp, 7 fig
Carroll black holes
Despite the absence of a lightcone structure, some solutions of Carroll gravity show black hole-like behaviour. We define Carroll black holes as solutions of Carroll gravity that exhibit Carroll thermal properties and have a Carroll extremal surface, notions introduced in our work. The latter is a Carroll analogue of a Lorentzian extremal surface. As examples, we discuss the Carroll versions of Schwarzschild, Reissner-Nordstroem, and BTZ black holes and black hole solutions of generic 1+1 dimensional Carroll dilaton gravity, including Carroll JT and Carroll Witten black holes
Targeting class I histone deacetylase 2 in MYC amplified group 3 medulloblastoma
Introduction: Medulloblastoma (MB) is the most frequent malignant brain tumor in children. Four subgroups with distinct genetic, epigenetic and clinical characteristics have been identified. Survival remains particularly poor in patients with Group 3 tumors harbouring a MYC amplification. We herein explore the molecular mechanisms and translational implications of class I histone deacetylase (HDAC) inhibition in MYC driven MBs. Material and Methods: Expression of HDACs in primary MB subgroups was compared to normal brain tissue. A panel of MB cell lines, including Group 3 MYC amplified cell lines, were used as model systems. Cells were treated with HDAC inhibitors (HDACi) selectively targeting class I or IIa HDACs. Depletion of HDAC2 was performed. Intracellular HDAC activity, cellular viability, metabolic activity, caspase activity, cell cycle progression, RNA and protein expression were analyzed. Results: HDAC2 was found to be overexpressed in MB subgroups with poor prognosis (SHH, Group 3 and Group 4) compared to normal brain and the WNT subgroup. Inhibition of the enzymatic activity of the class I HDACs reduced metabolic activity, cell number, and viability in contrast to inhibition of class IIa HDACs. Increased sensitivity to HDACi was specifically observed in MYC amplified cells. Depletion of HDAC2 increased H4 acetylation and induced cell death. Simulation of clinical pharmacokinetics showed time-dependent on target activity that correlated with binding kinetics of HDACi compounds. Conclusions: We conclude that HDAC2 is a valid drug target in patients with MYC amplified MB. HDACi should cover HDAC2 in their inhibitory profile and timing and dosing regimen in clinical trials should take binding kinetics of compounds into consideration
Identification of low and very high-risk patients with non-WNT/non-SHH medulloblastoma by improved clinico-molecular stratification of the HIT2000 and I-HIT-MED cohorts
Molecular groups of medulloblastoma (MB) are well established. Novel risk stratification parameters include Group 3/4 (non-WNT/non-SHH) methylation subgroups I-VIII or whole-chromosomal aberration (WCA) phenotypes. This study investigates the integration of clinical and molecular parameters to improve risk stratification of non-WNT/non-SHH MB. Non-WNT/non-SHH MB from the HIT2000 study and the HIT-MED registries were selected based on availability of DNA-methylation profiling data. MYC or MYCN amplification and WCA of chromosomes 7, 8, and 11 were inferred from methylation array-based copy number profiles. In total, 403 non-WNT/non-SHH MB were identified, 346/403 (86%) had a methylation class family Group 3/4 methylation score (classifier v11b6) ≥ 0.9, and 294/346 (73%) were included in the risk stratification modeling based on Group 3 or 4 score (v11b6) ≥ 0.8 and subgroup I-VIII score (mb_g34) ≥ 0.8. Group 3 MB (5y-PFS, survival estimation ± standard deviation: 41.4 ± 4.6%; 5y-OS: 48.8 ± 5.0%) showed poorer survival compared to Group 4 (5y-PFS: 68.2 ± 3.7%; 5y-OS: 84.8 ± 2.8%). Subgroups II (5y-PFS: 27.6 ± 8.2%) and III (5y-PFS: 37.5 ± 7.9%) showed the poorest and subgroup VI (5y-PFS: 76.6 ± 7.9%), VII (5y-PFS: 75.9 ± 7.2%), and VIII (5y-PFS: 66.6 ± 5.8%) the best survival. Multivariate analysis revealed subgroup in combination with WCA phenotype to best predict risk of progression and death. The integration of clinical (age, M and R status) and molecular (MYC/N, subgroup, WCA phenotype) variables identified a low-risk stratum with a 5y-PFS of 94 ± 5.7 and a very high-risk stratum with a 5y-PFS of 29 ± 6.1%. Validation in an international MB cohort confirmed the combined stratification scheme with 82.1 ± 6.0% 5y-PFS in the low and 47.5 ± 4.1% in very high-risk groups, and outperformed the clinical model. These newly identified clinico-molecular low-risk and very high-risk strata, accounting for 6%, and 21% of non-WNT/non-SHH MB patients, respectively, may improve future treatment stratification
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