367 research outputs found
The Lamb shift in the BTZ spacetime
We study the Lamb shift of a two-level atom arising from its coupling to the
conformal massless scalar field, which satisfies the Dirichlet boundary
conditions, in the Hartle-Hawking vacuum in the BTZ spacetime, and find that
the Lamb shift in the BTZ spacetime is structurally similar to that of a
uniformly accelerated atom near a perfectly reflecting boundary in
(2+1)-dimensional flat spacetime. Our results show that the Lamb shift is
suppressed in the BTZ spacetime as compared to that in the flat spacetime as
long as the transition wavelength of the atom is much larger than radius
of the BTZ spacetime while it can be either suppressed or enhanced if the
transition wavelength of the atom is much less than radius. In contrast,
the Lamb shift is always suppressed very close to the horizon of the BTZ
spacetime and remarkably it reduces to that in the flat spacetime as the
horizon is approached although the local temperature blows up there.Comment: 21 pages,2 figure
Information Theory of Blockchain Systems
In this paper, we apply the information theory to provide an approximate
expression of the steady-state probability distribution for blockchain systems.
We achieve this goal by maximizing an entropy function subject to specific
constraints. These constraints are based on some prior information, including
the average numbers of transactions in the block and the transaction pool,
respectively. Furthermore, we use some numerical experiments to analyze how the
key factors in this approximate expression depend on the crucial parameters of
the blockchain system. As a result, this approximate expression has important
theoretical significance in promoting practical applications of blockchain
technology. At the same time, not only do the method and results given in this
paper provide a new line in the study of blockchain queueing systems, but they
also provide the theoretical basis and technical support for how to apply the
information theory to the investigation of blockchain queueing networks and
stochastic models more broadly.Comment: 14 pages, 5 figure
Research on Strategies of Stock Index Futures Transaction Based on LMS Linear Regression
In recent years, stock index futures has developed into an important financial derivative in the global capital market and provided an indispensable investment and hedging tool for investors. This paper is mainly studying the low frequency transaction of stock index futures. Firstly, it conducts data cleaning to the stock index futures data and has an interpolation calculation to the missing values. Afterwards, it judges the market information in the short period and achieves the purpose of gaining profits through the basis. Furthermore, the time and the price difference are used as the key factors for establishing the quantitative model of gaining profits. Through lease square regression and inventory analysis technology, it completes the whole transaction process with several actions such as judging the open position time, transaction direction, reverse position closing time and yield accounting. Finally, as to the regression testing of the model, it detects the expression of the strategy through annual earnings, maximum drawback, transaction frequency, Sharpe ratio, variety commonality and cycle commonality. In the end, it conducts scientific analysis to the approaches used in the model and discusses the advantages and disadvantages of the model, thus providing some optimizing strategies in considering the improvement direction in practical application
ERNIE-UniX2: A Unified Cross-lingual Cross-modal Framework for Understanding and Generation
Recent cross-lingual cross-modal works attempt to extend Vision-Language
Pre-training (VLP) models to non-English inputs and achieve impressive
performance. However, these models focus only on understanding tasks utilizing
encoder-only architecture. In this paper, we propose ERNIE-UniX2, a unified
cross-lingual cross-modal pre-training framework for both generation and
understanding tasks. ERNIE-UniX2 integrates multiple pre-training paradigms
(e.g., contrastive learning and language modeling) based on encoder-decoder
architecture and attempts to learn a better joint representation across
languages and modalities. Furthermore, ERNIE-UniX2 can be seamlessly fine-tuned
for varieties of generation and understanding downstream tasks. Pre-trained on
both multilingual text-only and image-text datasets, ERNIE-UniX2 achieves SOTA
results on various cross-lingual cross-modal generation and understanding tasks
such as multimodal machine translation and multilingual visual question
answering.Comment: 13 pages, 2 figure
A Highly Selective Colorimetric Sensor for Cysteine in Water Solution and Bovine Serum Albumin
A simple colorimetric sensor, 2-bromonaphthalene-1,4-dione, has been developed for the Cysteine detection. The sensor showed its best performance in a mixture of ethanol and HEPES (5β:β5, v/v) solution at pH of 7.0. The results of UV-vis and fluorescence indicated that 2-bromonaphthalene-1,4-dione was selective and sensitive for Cysteine detection without the interference of other amino acids (Cysteine, Alanine, Arginine, Aspartinie, Glutamine, Glycine, Histidine, Isoleucine, Leucine, Lysine, Methionine, Proline, Serine, Threonine, Phenylalanine, Valine, Tryptophan, and Hydroxyproline). 2-Bromonaphthalene-1,4-dione also showed binding ability for Cysteine in bovine serum albumin and could be used as a potential colorimetric sensor among eighteen kinds of natural amino acids. Importantly, the recognition of CySH could be observed by naked eye
Dynamic active-site generation of atomic iridium stabilized on nanoporous metal phosphides for water oxidation
Designing efficient single-atom catalysts (SACs) for oxygen evolution reaction (OER) is critical for water-splitting. However, the self-reconstruction of isolated active sites during OER not only influences the catalytic activity, but also limits the understanding of structure-property relationships. Here, we utilize a self-reconstruction strategy to prepare a SAC with isolated iridium anchored on oxyhydroxides, which exhibits high catalytic OER performance with low overpotential and small Tafel slope, superior to the IrO2. Operando X-ray absorption spectroscopy studies in combination with theory calculations indicate that the isolated iridium sites undergo a deprotonation process to form the multiple active sites during OER, promoting the OβO coupling. The isolated iridium sites are revealed to remain dispersed due to the support effect during OER. This work not only affords the rational design strategy of OER SACs at the atomic scale, but also provides the fundamental insights of the operando OER mechanism for highly active OER SACs
Study of the doubly Cabibbo-suppressed decays and
Based on 7.33 fb of collision data collected at
center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector,
the experimental studies of the doubly Cabibbo-suppressed decays and are reported. We determine the
absolute branching fraction of to be
() . No
significant signal of is observed and the upper
limit on its decay branching fraction at 90\% confidence level is set to be
.Comment: 10 pages, 4 figures, 4 table
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