Circumferences and minimum degrees in 3-connected claw-free graphs

AbstractIn this paper, we prove that every 3-connected claw-free graph G on n vertices contains a cycle of length at least min{n,6δ−15}, thereby generalizing several known results

Non-Abelian dynamical gauge field and topological superfluids in optical Raman lattice

We propose an experimental scheme to realize non-Abelian dynamical gauge field for ultracold fermions, which induces a novel pairing mechanism of topological superfluidity. The dynamical gauge fields arise from nontrivial interplay effect between the strong Zeeman splitting and Hubbard interaction in a two-dimensional (2D) optical Raman lattice. The spin-flip transitions are forbidden by the large Zeeman detuning, but are restored when the Zeeman splitting is compensated by Hubbard interaction. This scheme allows to generate a dynamical non-Abelian gauge field that leads to a Dirac type correlated 2D spin-orbit interaction depending on local state configurations. The topological superfluid from a novel pairing driven by 2D dynamical gauge fields is reached, with analytic and numerical results being obtained. Our work may open up a door to emulate non-Abelian dynamical gauge fields and correlated topological phases with experimental feasibility.Comment: 5+7 pages, 4+6 figure

Hemodynamic changes after transcatheter aortic valve implantation during sequential follow-ups in patients with bicuspid aortic valve compared with tricuspid aortic valve

Background: To investigate the individual sequential hemodynamic changes after transcatheter aortic valve implantation (TAVI), especially for patients with bicuspid aortic valve (BAV), in comparison with tricuspid aortic valve (TAV). Methods: The study population comprised 85 patients with severe aortic stenosis who underwent TAVI for BAV (n = 49) or TAV (n = 36) with at least two serial echocardiographic follow-ups. Doppler echocardiography was scheduled to be performed at discharge and 1, 3, 6 months and 1 year after the procedure. D peak transvalvular velocities and D mean transvalvular gradients were calculated as the difference at follow-up time points and discharge. Paravalvular leak (PVL) was assessed as another indicator for prosthesis performance. Results: Comparisons between patients with BAV and TAV revealed similar gradient performances (1.00 [–2.00, 2.00] vs. 1.00 [–0.25, 5.00] mm Hg, p = 0.57 at 1 month; –0.71 ± 7.52 vs. 1.55 ± 3.97 mm Hg, p = 0.21 at 3 months; 0.96 ± 7.81 vs. 1.53 ± 5.85 mm Hg, p = 0.79 at 6 months; 1.00 [–0.50, 2.25] vs. 3.00 [–0.50, 7.50] mm Hg, p = 0.07 at 1 year). Moreover, the incidence of ≥ mild PVL was not significantly different in patients with BAV and TAV during follow-up (34.88% vs. 19.35%, p = 0.14 at 1 month; 45.83% vs. 27.27%, p = 0.19 at 3 months; 30.00% vs. 23.53%, p = 0.89 at 6 months; 30.00% vs. 17.65%, p = 0.56 at 1 year). Conclusions: TAVI is effective and applicable in BAV anatomy with sustained and acceptable mid- -term prosthesis hemodynamic performance. (Cardiol J 2017; 24, 4: 350–357

Recent advances on the synthesis, structure, and properties of polyoxotantalates

Polyoxotantalates (POTas) are an important branch of polyoxometalates (POMs) that remain largely undeveloped compared with other members of the POM family including polyoxovanadates, polyoxotungstates, polyoxomolybdates, and polyoxoniobates. Owing to their promising applications in diverse fields such as photo/electrocatalysis, ion conduction, environmental protection, and magnetism, the development of synthetic strategies for new POTas has attracted continuous interest over the past decades. This review summarizes the current status in the development of POTas, including their synthetic methods, crystal structures, physicochemical properties, and potential applications. Additionally, synthetic challenges and prospects are also discussed. It is hoped that this review will be of reference value for the further development of POTas

Association Between Serum Vitamin D Levels and Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: Vitamin D is an important secosteroid which is involved the development and regulation of brain activity. Several studies have focused on exploring the relationship between serum vitamin D levels and Parkinson's disease (PD), but the conclusion remains ambiguous.Methods: We searched observational studies that explored the association between serum vitamin D levels and PD based on PubMed, EMBASE and Cochrane library from inception through to January 2018. The quality of included studies was evaluated by using Newcastle-Ottawa Scale (NOS). Statistical analysis of this meta-analysis was performed by Stata version 12.0 and R software.Results: Twenty studies with a total of 2,866 PD patients and 2,734 controls were included. Compared with controls, PD patients had lower serum vitamin D levels (WMD −3.96, 95%CI −5.00, −2.92), especially in higher latitude regions (WMD −4.20, 95%CI −5.66, −2.75). Assay methods contributed significantly to high heterogeneity. Furthermore, PD patients with deficient vitamin D levels had advanced risk (OR 2.08, 95%CI 1.35, 3.19) than those patients with insufficient ones (OR = 1.73, 95%CI 1.48, 2.03). In addition, serum vitamin D levels were also related to the severity of PD (WMD −5.27, 95%CI −8.14, −2.39) and the summary correlation coefficient showed strongly negative correlation (r = −0.55, 95%CI −0.73, −0.29). Moreover, the pooled correlation coefficient revealed that serum vitamin D levels were also negatively correlated to the Unified Parkinson's Disease Rating Scale III (UPDRS III) (r = −0.36, 95%CI −0.53, −0.16), but did not correlate with the duration of PD (P = 0.37) and age of patients (P = 0.49).Conclusion: Serum vitamin D levels are inversely associated with the risk and severity of PD. Our results provided an updated evidence of association between low vitamin D levels and PD and prompt the adjunctive therapeutic decisions about vitamin D replacement in PD

Distributed UAV Swarm Augmented Wideband Spectrum Sensing Using Nyquist Folding Receiver

Distributed unmanned aerial vehicle (UAV) swarms are formed by multiple UAVs with increased portability, higher levels of sensing capabilities, and more powerful autonomy. These features make them attractive for many recent applica-tions, potentially increasing the shortage of spectrum resources. In this paper, wideband spectrum sensing augmented technology is discussed for distributed UAV swarms to improve the utilization of spectrum. However, the sub-Nyquist sampling applied in existing schemes has high hardware complexity, power consumption, and low recovery efficiency for non-strictly sparse conditions. Thus, the Nyquist folding receiver (NYFR) is considered for the distributed UAV swarms, which can theoretically achieve full-band spectrum detection and reception using a single analog-to-digital converter (ADC) at low speed for all circuit components. There is a focus on the sensing model of two multichannel scenarios for the distributed UAV swarms, one with a complete functional receiver for the UAV swarm with RIS, and another with a decentralized UAV swarm equipped with a complete functional receiver for each UAV element. The key issue is to consider whether the application of RIS technology will bring advantages to spectrum sensing and the data fusion problem of decentralized UAV swarms based on the NYFR architecture. Therefore, the property for multiple pulse reconstruction is analyzed through the Gershgorin circle theorem, especially for very short pulses. Further, the block sparse recovery property is analyzed for wide bandwidth signals. The proposed technology can improve the processing capability for multiple signals and wide bandwidth signals while reducing interference from folded noise and subsampled harmonics. Experiment results show augmented spectrum sensing efficiency under non-strictly sparse conditions