247 research outputs found
Supereulerian Locally Semicomplete Multipartite Digraphs
In this paper, we generalized the above known results and show that this conjecture holds for every strong locally semicomplete multipartite digraph
catena-Poly[[[diaquairon(II)]-μ-pyridine-2,5-dicarboxylato-[tetraaquairon(II)]-μ-pyridine-2,5-dicarboxylato] tetrahydrate]
In the crystal structure of the title compound, {[Fe2(C7H3NO4)2(H2O)6]·4H2O}n, there are two types of coordination for the FeII atoms. One FeII atom is in a distorted octahedral N2O4 environment, with two chelating rings from the pyridinedicarboxylate ligands and two O atoms from the water molecules, while the other is in a distorted octahedral O6 environment with two O atoms from the pyridinedicarboxylate ligands and four O atoms from the water molecules. Both FeII atoms lie on crystallographic centers of symmetry. The complex possesses an infinite chain structure running along the [101] direction. These chains are interconnected by the uncoordinated water molecules through O—H⋯O hydrogen bonds
Quality of reporting of systematic reviews published in “evidence-based” Chinese journals
BACKGROUND: The number of systematic reviews (SRs)/meta-analyses (MAs) has increased dramatically in China over the past decades. However, evaluation of quality of reporting of systematic reviews published has not been undertaken. The objective of this study is to evaluate the quality of reporting of SRs/MAs assessing efficacy and/or harms of clinical interventions published in “evidence-based” Chinese journals. METHODS: Web-based database searches were conducted for the Chinese Journal of Evidence-based Medicine, the Journal of Evidence-Based Medicine, the Chinese Journal of Evidence Based Pediatrics, and the Chinese Journal of Evidence-Based Cardiovascular Medicine. SRs/MAs assessing efficacy and/or harms of clinical interventions were included. The cut-off was December 31st 2011. The PRISMA statement was applied to assess the quality of reporting. Each item was assessed as follows: ‘Yes’ for total compliance, scored ‘1’; ‘partial’ for partial compliance, scored ‘0.5’; and ‘No’ for non-compliance, scored ‘0’. The review was considered to have major flaws if it received a total score of ≤15.0, minor flaws if it received a total score of 15.5 to 21.0, and minimal flaws if it received a total score 21.5 to 27.0. Odds ratios were used for binary variables, and the mean difference was used for continuous variables. Analyses were performed using RevMan 5.0 software. RESULTS: Overall, 487 SRs/MAs were identified and assessed. The included reviews had medium quality with minor flaws based on PRISMA total scores (range: 8.5–26.0; mean: 19.6 ± 3.3). The stratified analysis showed that SRs/MAs with more than 3 authors, from a university, hospital + university cooperation, multiple affiliations (≥2), and funding have significantly higher quality of reporting of SRs/MAs; 58% of the included reviews were considered to have minor flaws (total score of 15.6 to 21.0). Only 9.6% of reviews were considered to have major flaws. Specific areas needing improvement in reporting include the abstract, protocol and registration, and characteristics of the search. CONCLUSIONS: The reporting of SRs published in “evidence-based” Chinese journals is poor and needs to be improved in order for reviews to be useful. SR authors should use the PRISMA checklist to ensure complete and accurate accounts of their SRs
Quantum interface between frequency-uncorrelated down-converted entanglement and atomic-ensemble quantum memory
Photonic entanglement source and quantum memory are two basic building blocks
of linear-optical quantum computation and long-distance quantum communication.
In the past decades, intensive researches have been carried out, and remarkable
progress, particularly based on the spontaneous parametric down-converted
(SPDC) entanglement source and atomic ensembles, has been achieved. Currently,
an important task towards scalable quantum information processing (QIP) is to
efficiently write and read entanglement generated from a SPDC source into and
out of an atomic quantum memory. Here we report the first experimental
realization of a quantum interface by building a 5 MHz frequency-uncorrelated
SPDC source and reversibly mapping the generated entangled photons into and out
of a remote optically thick cold atomic memory using electromagnetically
induced transparency. The frequency correlation between the entangled photons
is almost fully eliminated with a suitable pump pulse. The storage of a
triggered single photon with arbitrary polarization is shown to reach an
average fidelity of 92% for 200 ns storage time. Moreover,
polarization-entangled photon pairs are prepared, and one of photons is stored
in the atomic memory while the other keeps flying. The CHSH Bell's inequality
is measured and violation is clearly observed for storage time up to 1
microsecond. This demonstrates the entanglement is stored and survives during
the storage. Our work establishes a crucial element to implement scalable
all-optical QIP, and thus presents a substantial progress in quantum
information science.Comment: 28 pages, 4 figures, 1 tabl
CROP: Conservative Reward for Model-based Offline Policy Optimization
Offline reinforcement learning (RL) aims to optimize policy using collected
data without online interactions. Model-based approaches are particularly
appealing for addressing offline RL challenges due to their capability to
mitigate the limitations of offline data through data generation using models.
Prior research has demonstrated that introducing conservatism into the model or
Q-function during policy optimization can effectively alleviate the prevalent
distribution drift problem in offline RL. However, the investigation into the
impacts of conservatism in reward estimation is still lacking. This paper
proposes a novel model-based offline RL algorithm, Conservative Reward for
model-based Offline Policy optimization (CROP), which conservatively estimates
the reward in model training. To achieve a conservative reward estimation, CROP
simultaneously minimizes the estimation error and the reward of random actions.
Theoretical analysis shows that this conservative reward mechanism leads to a
conservative policy evaluation and helps mitigate distribution drift.
Experiments on D4RL benchmarks showcase that the performance of CROP is
comparable to the state-of-the-art baselines. Notably, CROP establishes an
innovative connection between offline and online RL, highlighting that offline
RL problems can be tackled by adopting online RL techniques to the empirical
Markov decision process trained with a conservative reward. The source code is
available with https://github.com/G0K0URURI/CROP.git
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