3,142 research outputs found
Black hole remnant in asymptotic Anti-de Sitter space
It is known that a solution of remnant were suggested for black hole ground
state after surface gravity is corrected by loop quantum effect. On the other
hand, a Schwarzschild black hole in asymptotic Anti-de Sitter space would
tunnel into the thermal soliton solution known as the Hawking-Page phase
transition. In this letter, we investigate the low temperature phase of
three-dimensional BTZ black hole and four-dimensional AdS Schwarzschild black
hole. We find that the thermal soliton is energetically favored than the
remnant solution at low temperature in three dimensions, while Planck-size
remnant is still possible in four dimensions. Though the BTZ remnant seems
energetically disfavored, we argue that it is still possible to be found in the
overcooled phase if strings were present and its implication is discussed.Comment: 13 pages, 5 figures, submitted versio
Cooperative Learning of Zero-Shot Machine Reading Comprehension
Pretrained language models have significantly improved the performance of
down-stream language understanding tasks, including extractive question
answering, by providing high-quality contextualized word embeddings. However,
learning question answering models still need large-scaled data annotation in
specific domains. In this work, we propose a cooperative, self-play learning
framework, REGEX, for question generation and answering. REGEX is built upon a
masked answer extraction task with an interactive learning environment
containing an answer entity REcognizer, a question Generator, and an answer
EXtractor. Given a passage with a masked entity, the generator generates a
question around the entity, and the extractor is trained to extract the masked
entity with the generated question and raw texts. The framework allows the
training of question generation and answering models on any text corpora
without annotation. We further leverage a reinforcement learning technique to
reward generating high-quality questions and to improve the answer extraction
model's performance. Experiment results show that REGEX outperforms the
state-of-the-art (SOTA) pretrained language models and zero-shot approaches on
standard question-answering benchmarks, and yields the new SOTA performance
under the zero-shot setting
(E)-2-Acetylpyrazine 4-nitrophenylhydrazone
In the title compound, C12H11N5O2, the molecule adopts an E configuration, with the benzene and pyrazine rings located on opposite sides of the N=C double bond. The face-to-face separations of 3.413 (14) and 3.430 (8) Å, respectively between parallel benzene rings and between pyrazine rings indicate the existence of π–π stacking between adjacent molecules. The crystal structure also contains N—H⋯N and C—H⋯O hydrogen bonding
Degree-degree Correlated Low-density Parity-check Codes Over a Binary Erasure Channel
Most existing works on analyzing the performance of a random ensemble of
low-density parity-check (LDPC) codes assume that the degree distributions of
the two ends of a randomly selected edge are independent. In the paper, we take
one step further and consider ensembles of LDPC codes with degree-degree
correlations. For this, we propose two methods to construct an ensemble of
degree-degree correlated LDPC codes. We then derive a system of density
evolution equations for such degree-degree correlated LDPC codes over a binary
erasure channel (BEC). By conducting extensive numerical experiments, we show
how the degree-degree correlation affects the performance of LDPC codes. Our
numerical results show that LDPC codes with negative degree-degree correlation
could improve the maximum tolerable erasure probability. Moreover, increasing
the negative degree-degree correlation could lead to better unequal error
protection (UEP) design.Comment: accepted by the 2023 IEEE International Symposium on Information
Theory (ISIT
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