Papers made digestable

2022-11-30

- In this regard, we have performed RMHD simulations of a representative section of blazar jet
- We have further compared the effects of different radiation mechanisms through numerical simulation of 2D slab jet as a validation test
- We observe that shocks produced with the evolution of instabilities give rise to flaring signatures in the high energy band
- The impact of such shocks is also evident from the instantaneous flattening of the synchrotron component of the SEDs
- At later stages, we observe the transition in X-ray emission from the synchrotron process to that dominated by EC.

Authors: Sriyasriti Acharya, Bhargav Vaidya, Indu Kalpa Dihingia, Sushmita Agarwal, Amit Shukla.

2022-11-30

- We estimate proto-SSC ages of 5-9.7$\times$10$^4$ yr
- Heating by the HII regions in the SSC ZAMS phase seems to be rather local
- The proto-SSCs in NGC 4945 seem to be more evolved than in the starburst galaxy NGC 253
- We propose that sequential SSC formation can explain the spatial distribution and different ages of the SSCs in both galaxies.

Authors: Enrica Bellocchi, Jesús Martín-Pintado, Fernando Rico-Villas, Sergio Martín, Izaskun Jiménez-Sierra.

2022-11-30

- We present a novel approach that addresses both challenges
- First, we focus on ReLU networks with Gaussian output and illustrate their connection to probabilistic PCA.

Authors: Yookoon Park, Chris Dongjoo Kim, Gunhee Kim.

2022-11-30

- We more directly make use of pointwise estimates that are implicit in the work of Berard [2] and avoid the use of weak-type spaces that were used in the previous works [6] and [22]
- This allows us to prove new results for manifolds of negative curvature and some new sharp estimates for tori
- We also have new and improved techniques in two dimensions for general manifolds of non-positive curvature.

Authors: Matthew D. Blair, Xiaoqi Huang, Christopher D. Sogge.

2022-11-30

- Interpretability is a pressing issue for machine learning
- The optimal compression of each feature -- at every stage of approximation -- allows fine-grained inspection of the distinctions among feature values that are most impactful for prediction
- We develop a framework for extracting insight from the spectrum of approximate models and demonstrate its utility on a range of tabular datasets.

Authors: Kieran A. Murphy, Dani S. Bassett.

2022-11-30

- We can, therefore, provide one-to-one comparisons to traditional collocation and Galerkin methods within the tau framework
- We then impose additional mutual compatibility conditions to ensure boundary conditions match at shared subsurfaces
- The tau corrections and compatibility conditions can be fully isotropic and easily incorporated into existing solvers
- We present the method explicitly for the Poisson equation in two and three dimensions and describe its extension to arbitrary elliptic equations (e.g
- biharmonic) in any dimension.

Authors: Keaton J. Burns, Daniel Fortunato, Keith Julien, Geoffrey M. Vasil.

2022-11-30

- We analyze a family of graphs known as banana graphs, with two marked vertices, through the lens of Hurwitz-Brill-Noether theory
- As an application, we construct explicit new examples of finite graphs which are Brill-Noether general
- These are the first such examples since the analysis of chains of loops by Cools, Draisma, Payne and Robeva.

We analyze a family of graphs known as banana graphs, with two marked
vertices, through the lens of Hurwitz-Brill-Noether theory. As an application,
we construct explicit new examples of finite graphs which are Brill-Noether
general. These are the first such examples since the analysis of chains of
loops by Cools, Draisma, Payne and Robeva. The graphs constructed are chains of
loops and "theta graphs," which are banana graphs of genus 2. We also
demonstrate that almost all banana graphs of genus at least 3 cannot be used
for this purpose, due either to failure of a submodularity condition or to the
presence of far too many inversions in certain permutations associated to
divisors called transmission permutations.

Authors: Nathan Pflueger, Noah Solomon.

2022-11-30

- Most existing question answering (QA) datasets, in contrast, assume all questions have well defined answers
- This is in large part due to difficulty in retrieving relevant evidence passages from a large text corpus.

Authors: Xinyan Velocity Yu, Sewon Min, Luke Zettlemoyer, Hannaneh Hajishirzi.

2022-11-30

- We distinguish between two types of abstraction
- The second is defined by the visual simplicity of the sketch, moving from a detailed depiction to a sparse sketch
- The first network learns the desired placement of strokes, while the second network learns to gradually remove strokes from the sketch without harming its recognizability and semantics.

In this paper, we present a method for converting a given scene image into a
sketch using different types and multiple levels of abstraction. We distinguish
between two types of abstraction. The first considers the fidelity of the
sketch, varying its representation from a more precise portrayal of the input
to a looser depiction. The second is defined by the visual simplicity of the
sketch, moving from a detailed depiction to a sparse sketch. Using an explicit
disentanglement into two abstraction axes -- and multiple levels for each one
-- provides users additional control over selecting the desired sketch based on
their personal goals and preferences. To form a sketch at a given level of
fidelity and simplification, we train two MLP networks. The first network
learns the desired placement of strokes, while the second network learns to
gradually remove strokes from the sketch without harming its recognizability
and semantics. Our approach is able to generate sketches of complex scenes
including those with complex backgrounds (e.g., natural and urban settings) and
subjects (e.g., animals and people) while depicting gradual abstractions of the
input scene in terms of fidelity and simplicity.

Authors: Yael Vinker, Yuval Alaluf, Daniel Cohen-Or, Ariel Shamir.

2022-11-30

- We find the spectrum numerically and analytically in certain limits
- For intervals that almost touch the reflected entanglement spectrum approaches the spectrum of the thermal density matrix.

Authors: Souvik Dutta, Thomas Faulkner, Simon Lin.

2022-11-30

- The lack of evidence for such colored partners however drives these models into more and more fine-tuned regions
- Here, an alternative means to mitigate the top loop, allowing for natural electroweak symmetry breaking, is presented
- We first discuss possible effects via a modification of the running of the top Yukawa coupling
- Then, we turn to models where the top Yukawa is generated at one-loop level
- Originated from a dimension-six operator, it drops when crossing the mass threshold of new degrees of freedom
- In either case, the top partners are replaced by some new top-philic particles with strong interaction.

We discuss the role of the top-quark Yukawa coupling $y_t$ concerning the
hierarchy problem and construct an alternative scheme to the conventional
solutions with top partners. In traditional models, like SUSY or composite
Higgs, top partners cancel the top loop contribution to the Higgs quadratic
term. The lack of evidence for such colored partners however drives these
models into more and more fine-tuned regions. Here, an alternative means to
mitigate the top loop, allowing for natural electroweak symmetry breaking, is
presented. Emphasizing that we have not measured the top-Higgs interactions at
high scales yet, we envisage scenarios where this interaction is only
approaching its sizable strength in the infra-red, but gets strongly suppressed
at high scales. We first discuss possible effects via a modification of the
running of the top Yukawa coupling. Then, we turn to models where the top
Yukawa is generated at one-loop level. Originated from a dimension-six
operator, it drops when crossing the mass threshold of new degrees of freedom.
In either case, the top partners are replaced by some new top-philic particles
with strong interaction. Thus, a very different phenomenology, such as large
top mass running and signals in four top final states, is introduced, which
will be discussed in detail. With the assistance of this mechanism, the
solution to the hierarchy problem can be pushed to a (well-defined) higher
scale, and a final test of naturalness might be deferred to a 100 TeV Collider,
like the FCC.

Authors: Andreas Bally, Yi Chung, Florian Goertz.

2022-11-30

- The literature now contains different, and sometimes inequivalent, field theory definitions of entwinement
- We discuss similarities and differences with previous definitions of entwinement.

Authors: Ben Craps, Marine De Clerck, Alejandro Vilar López.

2022-11-30

- Like the known aluminum titanate pseudobrookites, anistropic thermal expansion is observed.

Dark blue single crystals of Al_1.75^(3+) Ti_1.0^(4+) Ti_0.25^(3+) O_5 were
grown with a novel synthesis method based on the reaction of a Ti3+/Ti4+
containing langbeinite melt and Al2O3. The obtained needles crystallize in the
pseudobrookite structure and undergo two reversible phase transitions from
orthorhombic Cmcm to C2/m first and subsequently to C2 symmetry. Like the known
aluminum titanate pseudobrookites, anistropic thermal expansion is observed.
The temperature evolution of the crystal structure reveals some insights into
the mechanism leading to the decomposition of the Al1.75Ti1.25O5 above
725{\deg}C. The magnetic and electrical properties are discussed and compared
to other reported aluminum titanate pseudobrookites.

Authors: Davor Tolj, WenHua Bi, Yong Liu, Ivica Zivkovic, Henrik M. Ronnow, Arnaud Magrez.

2022-11-30

- In one-dimension, quantum fluctuations prevent the appearance of long-range order in a supersolid, and only quasi long-range order can survive
- The analysis is based on an effective low-energy description accounting for the two coupled Goldstone modes.

Authors: Chris Bühler, Tobias Ilg, Hans Peter Büchler.

2022-11-30

- Safe reinforcement learning (RL) with assured satisfaction of hard state constraints during training has recently received a lot of attention
- Existing safety filter-based approaches typically involve learning of uncertain dynamics and quantifying the learned model error, which leads to conservative filters before a large amount of data is collected to learn a good model, thereby preventing efficient exploration
- This paper presents a method for safe and efficient model-free RL using disturbance observers (DOBs) and control barrier functions (CBFs)
- The DOB-based CBF can be used as a safety filter with any model-free RL algorithms by minimally modifying the actions of an RL agent whenever necessary to ensure safety throughout the learning process.

Safe reinforcement learning (RL) with assured satisfaction of hard state
constraints during training has recently received a lot of attention. Safety
filters, e.g., based on control barrier functions (CBFs), provide a promising
way for safe RL via modifying the unsafe actions of an RL agent on the fly.
Existing safety filter-based approaches typically involve learning of uncertain
dynamics and quantifying the learned model error, which leads to conservative
filters before a large amount of data is collected to learn a good model,
thereby preventing efficient exploration. This paper presents a method for safe
and efficient model-free RL using disturbance observers (DOBs) and control
barrier functions (CBFs). Unlike most existing safe RL methods that deal with
hard state constraints, our method does not involve model learning, and
leverages DOBs to accurately estimate the pointwise value of the uncertainty,
which is then incorporated into a robust CBF condition to generate safe
actions. The DOB-based CBF can be used as a safety filter with any model-free
RL algorithms by minimally modifying the actions of an RL agent whenever
necessary to ensure safety throughout the learning process. Simulation results
on a unicycle and a 2D quadrotor demonstrate that the proposed method
outperforms a state-of-the-art safe RL algorithm using CBFs and Gaussian
processes-based model learning, in terms of safety violation rate, and sample
and computational efficiency.

Authors: Yikun Cheng, Pan Zhao, Naira Hovakimyan.