Association of spinal-pelvic parameters with recurrence of lumbar disc herniation after endoscopic surgery: a retrospective case-control study.

PURPOSE: This study aimed to investigate the relationship between spinal-pelvic parameters and recurrence of lumbar disc herniation (rLDH) after percutaneous endoscopic lumbar discectomy (PELD) through a retrospective case-control study. METHODS: Patients who underwent PELD for single-segment LDH at our hospital were included in this study. The relationship between sagittal balance parameters of the spine and recurrence was analysed through correlation analysis, and ROC curves were plotted. The baseline characteristics, sagittal balance parameters of the spine and radiological parameters of the case and control groups were compared, and the relationship between sagittal balance parameters of the spine and recurrence of rLDH after PELD was determined through univariate and multivariate logistic regression analysis. RESULTS: Correlation analysis showed that PI and ∆PI-LL were negatively correlated with grouping (r = -0.090 and -0.120, respectively, P = 0.001 and 0.038). ROC curve analysis showed that the area under the curve (ROC-AUC) for predicting rLDH based on PI was 0.65 (CI95% = 0.598, 0.720), with a cut-off of 50.26°. The ROC-AUC for predicting rLDH based on ∆PI-LL was 0.56 (CI95% = 0.503, 0.634), with a cut-off of 28.21°. Multivariate logistic regression analysis showed that smoking status (OR = 2.667, P = 0.008), PI ≤ 50.26 (OR = 2.161, P = 0.009), ∆PI-LL ≤ 28.21 (OR = 3.185, P = 0.001) and presence of Modic changes (OR = 4.218, P = 0.001) were independent risk factors, while high DH (OR = 0.788, P = 0.001) was a protective factor. CONCLUSION: PI < 50.26 and ∆PI-LL < 28.21 were risk factors for recurrence of lumbar disc herniation after spinal endoscopic surgery and had some predictive value for post-operative recurrence.

Tuberculosis among migrant workers in Taiwan.

BACKGROUND: Although the worldwide incidence of tuberculosis (TB) has been slowly decreasing, the migrant workers remains an important gap for regional TB control. In Taiwan, the numbers of the migrant workers from countries with high TB incidence increase significantly in past decades and the impact on public health remains unknown. This study aimed to explore the difference of TB incidence between Taiwanese and the migrant workers. METHODS: The migrant workers are obligated to receive pre-arrival, post-arrival and regular chest X-ray screening during their stay in Taiwan. We retrospectively collected these data extracted from the Alien Workers Health Database in Centers for Disease Control, Taiwan from Jan. 1, 2004 to Dec. 31, 2013. Poisson regression models were used to compare the hazard ratios of TB between Taiwanese and the migrant workers after adjusting gender and age groups. RESULTS: The total migrant workers in Taiwan reached 314,034 persons in 2004 and 489,134 persons in 2013, accounting for 2% of Taiwan population. The TB incidence of migrant workers was similar to Taiwanese (53-73.7 per 105 vs 45.5-76.8 per 105). Comparing with Taiwanese, the TB risk was significantly lower in male migrant workers (HR: 0.76; 95% CI: 0.70-0.83, P < 0.001), but higher in female migrant workers (HR: 1.40; 95% CI: 1.35-1.46, P < 0.001). Besides, we found that the TB risk in migrant workers was 5.30-fold (95% CI: 4.83-5.83, P < 0.001) in youngest group (≤24 year-old) comparing with Taiwanese. CONCLUSIONS: Migrant workers in Taiwan have higher TB incidence than Taiwanese in young groups, especially in females. The mainstay young laborers with latent tuberculosis infection risk is an important vulnerability for public health. Further investigation and health screening are warranted.

Continuously and widely tunable frequency-stabilized laser based on an optical frequency comb.

Continuously and widely tunable lasers, actively stabilized on a frequency reference, are broadly employed in atomic, molecular, and optical (AMO) physics. The frequency-stabilized optical frequency comb (OFC) provides a novel optical frequency reference, with a broadband spectrum that meets the requirement of laser frequency stabilization. Therefore, we demonstrate a frequency-stabilized and precisely tunable laser system based on it. In this scheme, the laser frequency locked to the OFC is driven to jump over the ambiguity zones, which blocks the wide tuning of the locked laser, and tuned until the mode hopping happens with the always-activated feedback loop. Meanwhile, we compensate the gap of the frequency jump with a synchronized acoustic optical modulator to ensure the continuity. This scheme is applied to an external cavity diode laser (ECDL), and we achieve tuning at a rate of about 7 GHz/s, with some readily available commercial electronics. Furthermore, we tune the frequency-stabilized laser only with the feedback of diode current, and its average tuning speed can exceed 100 GHz/s. Due to the resource-efficient configuration and the simplicity of completion, this scheme can be referenced and can find wide applications in AMO experiments.

One-Step Exfoliation Method for Plasmonic Activation of Large-Area 2D Crystals.

Advanced exfoliation techniques are crucial for exploring the intrinsic properties and applications of 2D materials. Though the recently discovered Au-enhanced exfoliation technique provides an effective strategy for the preparation of large-scale 2D crystals, the high cost of gold hinders this method from being widely adopted in industrial applications. In addition, direct Au contact could significantly quench photoluminescence (PL) emission in 2D semiconductors. It is therefore crucial to find alternative metals that can replace gold to achieve efficient exfoliation of 2D materials. Here, the authors present a one-step Ag-assisted method that can efficiently exfoliate many large-area 2D monolayers, where the yield ratio is comparable to Au-enhanced exfoliation method. Differing from Au film, however, the surface roughness of as-prepared Ag films on SiO2 /Si substrate is much higher, which facilitates the generation of surface plasmons resulting from the nanostructures formed on the rough Ag surface. More interestingly, the strong coupling between 2D semiconductor crystals (e.g., MoS2 , MoSe2 ) and Ag film leads to a unique PL enhancement that has not been observed in other mechanical exfoliation techniques, which can be mainly attributed to enhanced light-matter interaction as a result of extended propagation of surface plasmonic polariton (SPP). This work provides a lower-cost and universal Ag-assisted exfoliation method, while at the same time offering enhanced SPP-matter interactions.

Author Correction: Universal mechanical exfoliation of large-area 2D crystals.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Universal mechanical exfoliation of large-area 2D crystals.

Two-dimensional materials provide extraordinary opportunities for exploring phenomena arising in atomically thin crystals. Beginning with the first isolation of graphene, mechanical exfoliation has been a key to provide high-quality two-dimensional materials, but despite improvements it is still limited in yield, lateral size and contamination. Here we introduce a contamination-free, one-step and universal Au-assisted mechanical exfoliation method and demonstrate its effectiveness by isolating 40 types of single-crystalline monolayers, including elemental two-dimensional crystals, metal-dichalcogenides, magnets and superconductors. Most of them are of millimeter-size and high-quality, as shown by transfer-free measurements of electron microscopy, photo spectroscopies and electrical transport. Large suspended two-dimensional crystals and heterojunctions were also prepared with high-yield. Enhanced adhesion between the crystals and the substrates enables such efficient exfoliation, for which we identify a gold-assisted exfoliation method that underpins a universal route for producing large-area monolayers and thus supports studies of fundamental properties and potential application of two-dimensional materials.

Moiré Phonons in Twisted Bilayer MoS2.

The material choice, layer thickness, and twist angle widely enrich the family of van der Waals heterostructures (vdWHs), providing multiple degrees of freedom to engineer their optical and electronic properties. The moiré patterns in vdWHs create a periodic potential for electrons and excitons to yield many interesting phenomena, such as Hofstadter butterfly spectrum and moiré excitons. Here, in the as-grown/transferred twisted bilayer MoS2 (tBLMs), one of the simplest prototypes of vdWHs, we show that the periodic potentials of moiré patterns also modify the properties of phonons of its monolayer MoS2 constituent to generate Raman modes related to moiré phonons. These Raman modes correspond to zone-center phonons in tBLMs, which are folded from the off-center phonons in monolayer MoS2. However, the folded phonons related to crystallographic superlattices are not observed in the Raman spectra. By varying the twist angle, the moiré phonons of tBLM can be exploited to map the phonon dispersions of the monolayer constituent. The lattice dynamics of the moiré phonons are modulated by the patterned interlayer coupling resulting from periodic potential of moiré patterns, as confirmed by density functional theory calculations. The Raman intensity related to moiré phonons in all tBLMs are strongly enhanced when the excitation energy approaches the C exciton energy. This study can be extended to various vdWHs to deeply understand their Raman spectra, moiré phonons, lattice dynamics, excitonic effects, and interlayer coupling.