Two energy scales and close relationship between the pseudogap and superconductivity in underdoped cuprate superconductors

By measuring the low temperature specific heat, the low energy quasi-particle excitation has been derived and analyzed in systematically doped La$_{2-x}$Sr$_{x}$CuO$_{4}$ single crystals. The Volovik's relation predicted for a d-wave superconductor has been well demonstrated in wide doping regime, showing a robust evidence for the d-wave pairing symmetry. Furthermore the nodal gap slope $v_\Delta$ of the superconducting gap is derived and is found to follow the same doping dependence of the pseudogap obtained from ARPES and tunnelling measurement. This strongly suggests a close relationship between the pseudogap and superconductivity. Taking the entropy conservation into account, we argue that the ground state of the pseudogap phase should have Fermi arcs with finite density of states at zero K, and the transport data show that it behaves like an insulator due to probably weak localization. A nodal metal picture for the pseudogap phase cannot interpret the data. Based on the Fermi arc picture for the pseudogap phase it is found that the superconducting energy scale or $T_c$ in underdoped regime is governed by both the maximum gap and the spectral weight from the Fermi arcs. This suggests that there are two energy scales: superconducting energy scale and the pseudogap. The superconductivity may be formed by the condensation of Fermi arc quasiparticles through pairing by exchanging virtue bosons.Comment: 4 pages, 5 figure

Point Contrastive Prediction with Semantic Clustering for Self-Supervised Learning on Point Cloud Videos

We propose a unified point cloud video self-supervised learning framework for object-centric and scene-centric data. Previous methods commonly conduct representation learning at the clip or frame level and cannot well capture fine-grained semantics. Instead of contrasting the representations of clips or frames, in this paper, we propose a unified self-supervised framework by conducting contrastive learning at the point level. Moreover, we introduce a new pretext task by achieving semantic alignment of superpoints, which further facilitates the representations to capture semantic cues at multiple scales. In addition, due to the high redundancy in the temporal dimension of dynamic point clouds, directly conducting contrastive learning at the point level usually leads to massive undesired negatives and insufficient modeling of positive representations. To remedy this, we propose a selection strategy to retain proper negatives and make use of high-similarity samples from other instances as positive supplements. Extensive experiments show that our method outperforms supervised counterparts on a wide range of downstream tasks and demonstrates the superior transferability of the learned representations.Comment: Accepted by ICCV 202

Efficacy of Ultrasound-guided Radiofrequency Ablation of Parathyroid Hyperplasia: Single Session vs. Two-Session for Effect on Hypocalcemia

To evaluate safety and efficacy of one- vs. two-session radiofrequency ablation (RFA) of parathyroid hyperplasia for patients with secondary hyperparathyroidism (SHPT) and to compare the outcome of both methods on hypocalcemia. Patients with secondary hyperparathyroidism underwent ultrasound guided RFA of parathyroid hyperplasia. Patients were alternately assigned to either group 1 (n = 28) with RFA of all 4 glands in one session or group 2 (n = 28) with RFA of 2 glands in a first session and other 2 glands in a second session. Serum parathyroid hormone (PTH), calcium, phosphorus and alkaline phosphatase (ALP) values were measured at a series of time points after RFA. RFA parameters, including operation duration and ablation time and hospitalization length and cost, were compared between the two groups. Mean PTH decreased in group 1 from 1865.18 ± 828.93 pg/ml to 145.72 ± 119.27 pg/ml at 1 day after RFA and in group 2 from 2256.64 ± 1021.72 pg/ml to 1388.13 ± 890.15 pg/ml at 1 day after first RFA and to 137.26 ± 107.12 pg/ml at 1 day after second RFA. Group 1\u27s calcium level decreased to 1.79 ± 0.31 mmol/L at day 1 after RFA and group 2 decreased to 1.89 ± 0.26 mmol/L at day 1 after second session RFA (P \u3c 0.05). Multivariate analysis showed that hypocalcemia was related to serum ALP. Patients with ALP ≥ 566 U/L had lower calcium compared to patients with ALP \u3c 566 U/L up to a month after RFA (P \u3c 0.05). Group 1\u27s RFA time and hospitalization were shorter and had lower cost compared with Group 2. US-guided RFA of parathyroid hyperplasia is a safe and effective method for treating secondary hyperparathyroidism. Single-session RFA was more cost-effective and resulted in a shorter hospital stay compared to two sessions. However, patients with two-session RFA had less hypocalcemia, especially those with high ALP

Absolute Stability of a Class of Nonlinear Singular Systems with Time Delay

This paper deals with the absolute stability for a class of nonlinear singular systems with time delay. By employing a new Lyapunov-Krasovskii functional with the idea of partitioning delay length, improved delay-dependent stability criteria are established. The resulting condition is formulated in terms of linear matrix inequalities (LMIs), which is easy to be verified by exiting LMI optimization algorithms. A numerical example is given to show the effectiveness of the proposed technique and its improvements over the existing results

Influence Mechanism of Main Roof Height on Surrounding Rock Stability of Gob-Side Entry Driving

The main roof directly affects the stress environment and the control effect of the surrounding rock of gob-side entry driving. A mechanical model of the surrounding rock of gob-side entry driving was established to analyze the influence mechanism of different main roof heights on the surrounding rock stability of the roadway under similar geological conditions. In addition, the influences of the main roof heights on the stress distribution of the surrounding rock were qualitatively analyzed. A quantitative analysis of the stress and deformation distribution characteristics of the surrounding rock were conducted by Universal Distinct Element Code (UDEC) when the heights were 0, 5, and 10 m based on the actual geological conditions. Results show that waste rocks in the caving zone and damaged immediate roof could provide four different stress combinations to key rock block, which is affected by the main roof height and other related parameters. With the increase in the main roof height, the hinged stress between the key rock blocks and the plastic damage area of the physical coal wall are reduced, the damage range of immediate roof gradually increases, and the vertical stress of narrow coal pillars first increases to 5.22 MPa and then remains at approximately 1.92 MPa. Therefore, the supporting strength of roof and the physical coal wall should be enhanced. Research results are successfully applied in the Yanjiahe Coal Mine. The conclusions provide significant theoretical guidance for controlling surrounding rock stability of the roadway under similar conditions

Boron diffusion in magnetic tunnel junctions with MgO (001) barriers and CoFeB electrodes

We map the magnetic field sensitivity and low-frequency 1 / f voltage noise of high magnetoresistance MgO-based magnetic tunnel junctions in an orthogonal magnetic field arrangement. Large sensitivity values of over 1%/Oe are obtained only when a sufficiently large hard-axis bias field is applied. The low-frequency voltage noise is observed to scale with the field sensitivity. The magnetic field noise map reveals that the signal-to-noise ratios of these devices get gradually better at higher hard-axis bias fields

Serum β

Objective. To demonstrate the role of Wnt/β-catenin canonical pathway in postmenopausal osteoporosis by evaluating serum β-catenin levels in patients with postmenopausal osteoporosis and analyzing their possible relationship with serum OPG, RANKL, the ratio of RANKL/OPG, sclerostin, and bone turnover markers. Methods. 480 patients with postmenopausal osteoporosis and 170 healthy postmenopausal women were enrolled in the study. Serum β-catenin, OPG, RANKL, and sclerostin levels were measured by enzyme-linked immunosorbent assay. Bone status was assessed by measuring bone mineral density and bone turnover markers. Estradiol levels were also detected. Results. Serum β-catenin levels were lower in postmenopausal osteoporotic women compared to nonosteoporotic postmenopausal women (26.26±14.81 versus 39.33±5.47 pg/mL, P<0.001). Serum β-catenin was positively correlated with osteoprotegerin (r=0.232, P<0.001) and negatively correlated with the ratio of RANKL/OPG, body mass index, and sclerostin (r=-0.128, P=0.005; r=-0.117, P=0.010; r=-0.400, P<0.001, resp.) in patients with postmenopausal osteoporosis. Conclusion. The results indicate that lower serum β-catenin and concomitantly higher ratio of RANKL/OPG may be involved in the pathogenesis of postmenopausal osteoporosis. Functional communication between RANKL/RANK/OPG system and Wnt pathways plays an important role in postmenopausal osteoporosis