1,108 research outputs found
Fast Min-Sum Algorithms for Decoding of LDPC over GF(q)
In this paper, we present a fast min-sum algorithm for decoding LDPC codes
over GF(q). Our algorithm is different from the one presented by David Declercq
and Marc Fossorier in ISIT 05 only at the way of speeding up the horizontal
scan in the min-sum algorithm. The Declercq and Fossorier's algorithm speeds up
the computation by reducing the number of configurations, while our algorithm
uses the dynamic programming instead. Compared with the configuration reduction
algorithm, the dynamic programming one is simpler at the design stage because
it has less parameters to tune. Furthermore, it does not have the performance
degradation problem caused by the configuration reduction because it searches
the whole configuration space efficiently through dynamic programming. Both
algorithms have the same level of complexity and use simple operations which
are suitable for hardware implementations.Comment: Accepted by IEEE Information Theory Workshop, Chengdu, China, 200
Molecule Generation by Principal Subgraph Mining and Assembling
Molecule generation is central to a variety of applications. Current
attention has been paid to approaching the generation task as subgraph
prediction and assembling. Nevertheless, these methods usually rely on
hand-crafted or external subgraph construction, and the subgraph assembling
depends solely on local arrangement. In this paper, we define a novel notion,
principal subgraph, that is closely related to the informative pattern within
molecules. Interestingly, our proposed merge-and-update subgraph extraction
method can automatically discover frequent principal subgraphs from the
dataset, while previous methods are incapable of. Moreover, we develop a
two-step subgraph assembling strategy, which first predicts a set of subgraphs
in a sequence-wise manner and then assembles all generated subgraphs globally
as the final output molecule. Built upon graph variational auto-encoder, our
model is demonstrated to be effective in terms of several evaluation metrics
and efficiency, compared with state-of-the-art methods on distribution learning
and (constrained) property optimization tasks.Comment: Accepted by NeurIPS 202
Unsupervised Explanation Generation via Correct Instantiations
While large pre-trained language models (PLM) have shown their great skills
at solving discriminative tasks, a significant gap remains when compared with
humans for explanation-related tasks. Among them, explaining the reason why a
statement is wrong (e.g., against commonsense) is incredibly challenging. The
major difficulty is finding the conflict point, where the statement contradicts
our real world. This paper proposes Neon, a two-phrase, unsupervised
explanation generation framework. Neon first generates corrected instantiations
of the statement (phase I), then uses them to prompt large PLMs to find the
conflict point and complete the explanation (phase II). We conduct extensive
experiments on two standard explanation benchmarks, i.e., ComVE and e-SNLI.
According to both automatic and human evaluations, Neon outperforms baselines,
even for those with human-annotated instantiations. In addition to explaining a
negative prediction, we further demonstrate that Neon remains effective when
generalizing to different scenarios.Comment: Accepted to AAAI-2
Interface engineering of mesoporous triphasic cobalt-copper phosphides as active electrocatalysts for overall water splitting
Efficient electrocatalysts for water splitting are essential for viable generation of highly purified hydrogen. Hence there is a need to develop robust catalysts to eliminate barriers associated with sluggish kinetics associated with both anodic oxygen and cathodic hydrogen evolution reactions. Herein, we report a two-step nanocasting-solid phase phosphorization approach to generate ordered mesoporous triphasic phosphides CoP@Cu2P-Cu3P. We show that it is a highly efficient bifunctional electrocatalyst useful for overall water splitting. The mesoporous triphasic CoP@Cu2P-Cu3P only requires a low overpotential of 255 mV and 188 mV to achieve 10 mA cm(-2) for oxygen and hydrogen evolution reactions, respectively. The combination of mesoporous pores (similar to 5.6 nm) with very thin walls (similar to 3.7 nm) and conductive networks in triphasic CoP@Cu2P-Cu3P enable rapid rate of electron transfer and mass transfer. In addition, when CoP@Cu2P-Cu3P is used to fabricate symmetric electrodes, the high surface area mesoporous structure and synergetic effects between phases together contribute to a low cell voltage of 1.54 V to drive a current density 10 mA cm(-2). This performance is superior to noble-metal-based Pt/C-IrO2/C. This work provides a new approach for the facile design and application of multiphase phosphides as highly active bifunctional and stable electrocatalysts for water-alkali electrolyzers
The value of a novel percutaneous lung puncture clamp biopsy technique in the diagnosis of pulmonary nodules
Abstract
Background: Computed tomography-guided percutaneous lung biopsy is a crucial method to determine pulmonary anomalies, and is highly accurate in detecting evidence of malignancies, allowing medical practitioners to identify the stage of malignancy and thus help to plan the treatment regimens of patients.Objective: To explore the clinical application of a new computed tomography-guided percutaneous lung puncture clamp biopsy technique in the diagnosis of pulmonary nodules, characterized by ground-glass opacity on chest computed tomography images.Methods: A unique instrument named ‘combined percutaneous lung biopsy forceps’, consisting of a biopsy forceps, a 15-gauge coaxial needle and needle core, was designed. The new tool was used to obtain specimens in nine patients with pulmonary ground-glass opacity. The specimen volumes and the safety of using the instrument were measured. The samples obtained were also assessed to see if they were sufficient for conducting histological tests.Result: Samples were obtained in all nine patients – a success rate of 100%. Consistently, the volume of each specimen was sufficient to make a histological diagnosis. No serious complications, such as pneumothorax – primary spontaneous pneumothorax or secondary spontaneous pneumothorax – occurred during the biopsy.Conclusions: The application of this new tool in obtaining tissue specimens in patients with pulmonary ground-glass opacity under the guidance of chest computed tomography was invaluable in terms of its high accuracy and safety. Moreover, its effect was better compared to using a fine-needle aspiration biopsy or a cutting-needle biopsy. Therefore, this instrument can be used for histological diagnosis. [Ethiop. J. Health Dev. 2021; 35(2):85-90]Key words: Ground-glass opacity; percutaneous lung puncture clamp biopsy; fine-needle aspiration biopsy; cutting-needle biops
Clinical Features and Visual Acuity Outcomes in Culture-Positive Endogenous Fungal Endophthalmitis in Southern China
Purpose. To report the causative organisms, management strategies, and visual outcomes of culture-proven endogenous fungal endophthalmitis in a case series from southern China. Methods. We reviewed the microbiological and medical records of patients with culture-positive endogenous fungal endophthalmitis visiting the Zhongshan Ophthalmic Center, Guangzhou, China, between January 1, 2006, and March 31, 2016. Results. The inclusion criteria were met in 32 eyes of 29 patients. Molds were a common causative organism in 15 patients (51.7%), while yeasts appeared in 14 patients (48.3%). Initial visual acuity (VA) at the level of finger counting or better was significantly related to a good visual outcome (P=0.002). Molds as a causative agent were significantly associated with worse visual outcome than yeasts (P=0.020). Conclusion. Molds were a common cause of culture-proven fungal endophthalmitis. Endogenous fungal endophthalmitis is generally associated with poor VA outcomes, especially if caused by molds and if the patient’s initial VA is too low to permit finger counting
Facile template-free synthesis of vertically aligned polypyrrole nanosheets on nickel foams for flexible all-solid-state asymmetric supercapacitors
This paper reports a novel and remarkably facile approach towards vertically aligned nanosheets on three-dimensional (3D) Ni foams. Conducting polypyrrole (PPy) sheets were grown on Ni foam through the volatilization of the environmentally friendly solvent from an ethanol–water solution of pyrrole (Py), followed by the polymerization of the coated Py in ammonium persulfate (APS) solution. The PPy-decorated Ni foams and commercial activated carbon (AC) modified Ni foams were employed as the two electrodes for the assembly of flexible all-solid-state asymmetric supercapacitors. The sheet-like structure of PPy and the macroporous feature of the Ni foam, which render large electrode–electrolyte interfaces, resulted in good capacitive performance of the supercapacitors. Moreover, a high energy density of ca. 14 Wh kg−1 and a high power density of 6.2 kW kg−1 were achieved for the all-solid-state asymmetric supercapacitors due to the wide cell voltage window
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