A Fast Order-Based Approach for Core Maintenance

Graphs have been widely used in many applications such as social networks, collaboration networks, and biological networks. One important graph analytics is to explore cohesive subgraphs in a large graph. Among several cohesive subgraphs studied, k-core is one that can be computed in linear time for a static graph. Since graphs are evolving in real applications, in this paper, we study core maintenance which is to reduce the computational cost to compute k-cores for a graph when graphs are updated from time to time dynamically. We identify drawbacks of the existing efficient algorithm, which needs a large search space to find the vertices that need to be updated, and has high overhead to maintain the index built, when a graph is updated. We propose a new order-based approach to maintain an order, called k-order, among vertices, while a graph is updated. Our new algorithm can significantly outperform the state-of-the-art algorithm up to 3 orders of magnitude for the 11 large real graphs tested. We report our findings in this paper

Spectral Compressive Sensing with Model Selection

The performance of existing approaches to the recovery of frequency-sparse signals from compressed measurements is limited by the coherence of required sparsity dictionaries and the discretization of frequency parameter space. In this paper, we adopt a parametric joint recovery-estimation method based on model selection in spectral compressive sensing. Numerical experiments show that our approach outperforms most state-of-the-art spectral CS recovery approaches in fidelity, tolerance to noise and computation efficiency.Comment: 5 pages, 2 figures, 1 table, published in ICASSP 201

Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials - A general bond polarizability model

2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences (e.g. ABAB, ABCABC), leading to different physical properties. Here, we show that regardless of the space group of the 2D material, the Raman frequencies of the interlayer shear modes observed under the typical configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials.Comment: 30 pages, 8 figure

Single deep ultraviolet light emission from boron nitride nanotube film

Light in deep ultraviolet DUV region has a wide range of applications and the demand for finding DUV light emitting materials at nanoscale is increasingly urgent as they are vital for building miniaturized optic and optoelectronic devices. We discover that boron nitride nanotubes BNNTs with a well-crystallized cylindrical multiwall structure and diameters smaller than 10 nm can have single DUV emission at 225 nm 5.51 eV. The measured BNNTs are grown on substrate in the form of a thin film. This study suggests that BNNTs may work as nanosized DUV light sources for various applications. © 20

Factors associated with the utilization of antenatal care services among pregnant women in Eswatini - A cross-sectional study

The study aimed to assess the utilization of antenatal care services and its associated factors among pregnant women in Eswatini. A cross-sectional study was adopted. Convenience sampling was conducted in a public referral hospital in central Eswatini from 1st of August to the 30 of September 2021. A total of 400 newly delivered women who met the inclusion criteria were recruited. SPSS version 22.0 was used to analyze data including descriptive and bivariate analysis. Results indicated that only 13% of pregnant women booked their first ANC in the first trimester and 24.8% of them attended less than four ANC visits. Maternal education, gestational age, gravity, pregnant-related complications, medical history, and maternal health literacy were significantly associated with the utilization of ANC services (p< .05). To increase the utilization of ANC service, healthcare professionals should pay special attention to pregnant women with tertiary education, gave birth below 38 weeks, multi-gravities, medical history, and poor maternal health literacy. (Afr J Reprod Health 2022; 26[12]: 67-77). L'étude visait à évaluer l'utilisation des services de soins prénatals et ses facteurs associés chez les femmes enceintes en Eswatini. Une étude transversale a été retenue. Un échantillonnage de commodité a été effectué dans un hôpital public de référence du centre d'Eswatini du 1er août au 30 septembre 2021. Un total de 400 femmes nouvellement accouchées qui répondaient aux critères d'inclusion ont été recrutées. La version SPSS 22.0 a été utilisée pour analyser les données, y compris l'analyse descriptive et bivariée. Les résultats ont indiqué que seulement 13 % des femmes enceintes ont réservé leur première CPN au cours du premier trimestre et 24,8 % d'entre elles ont assisté à moins de quatre visites CPN. L'éducation de la mère, l'âge gestationnel, la gravité, les complications liées à la grossesse, les antécédents médicaux et les connaissances en matière de santé maternelle étaient significativement associés à l'utilisation des services de soins prénatals (p < 0,05). Pour accroître l'utilisation des services de soins prénatals, les professionnels de la santé doivent accorder une attention particulière aux femmes enceintes ayant fait des études supérieures, ayant accouché à moins de 38 semaines, multigravités, ayant des antécédents médicaux et une faible littératie en matière de santé maternelle. (Afr J Reprod Health 2022; 26[12]: 67-77)