Adiabatic processes are useful for quantum technologies1, 2, 3 but, despite their robustness to experimental imperfections, they remain susceptible to decoherence due to their long evolution time. A ...general strategy termed shortcuts to adiabaticity4, 5, 6, 7, 8, 9 (STA) aims to remedy this vulnerability by designing fast dynamics to reproduce the results of a slow, adiabatic evolution. Here, we implement an STA technique known as superadiabatic transitionless driving10 (SATD) to speed up stimulated Raman adiabatic passage1, 11, 12, 13, 14 in a solid-state lambda system. Using the optical transitions to a dissipative excited state in the nitrogen-vacancy centre in diamond, we demonstrate the accelerated performance of different shortcut trajectories for population transfer and for the initialization and transfer of coherent superpositions. We reveal that SATD protocols exhibit robustness to dissipation and experimental uncertainty, and can be optimized when these effects are present. These results suggest that STA could be effective for controlling a variety of solid-state open quantum systems.
Tumour necrosis factor-alpha (TNF-
α
) is an important inflammatory factor that acts as a master switch in establishing an intricate link between inflammation and cancer. A wide variety of evidence ...has pointed to a critical role of TNF-
α
in tumour proliferation, migration, invasion and angiogenesis. The function of TNF-
α
as a key regulator of the tumour microenvironment is well recognised. We will emphasise the contribution of TNF-
α
and the nuclear factor-
κ
B pathway on tumour cell invasion and metastasis. Understanding the mechanisms underlying inflammation-mediated metastasis will reveal new therapeutic targets for cancer prevention and treatment.
Studies have reported inconsistent results concerning the association of cesarean section with offspring obesity. We performed a systematic review and meta-analysis to examine whether cesarean ...section increases the risk of later overweight and obesity. Pubmed, Embase and Web of Science were searched using different combinations of two groups of keywords: 'cesarean' and 'overweight/obesity'. Cohort or case-control studies that reported the association of cesarean section with childhood (3-8 years), adolescence (9-18 years) and/or adult (>19 years) overweight/obesity were eligible. Where possible, adjusted risk estimates were pooled using a random effects model; otherwise unadjusted estimates were pooled. Statistical heterogeneity was assessed with I(2) statistics; the values of 25%, 50% and 75% were considered to indicate low, medium and high heterogeneity, respectively. We conducted a subgroup analysis to identify the sources of heterogeneity according to study quality defined on the basis of the Newcastle-Ottawa Scale. In total, two case-control and seven cohort studies were identified for the literature review and 15 separate risk estimates were included in the meta-analysis. The overall pooled odds ratio (OR) of overweight/obesity for offspring delivered by cesarean section compared with those born vaginally was 1.33 (95% confidence interval (CI) 1.19, 1.48; I(2)=63%); the OR was 1.32 (1.15, 1.51) for children, 1.24 (1.00, 1.54) for adolescents and 1.50 (1.02, 2.20) for adults. In subgroup analysis, the overall pooled OR was 1.18 (1.09, 1.27; I(2)=29%) for high-quality studies and 1.78 (1.43, 2.22; I(2)=24%) for medium-quality (P for interaction=0.0005); no low-quality studies were identified. The ORs for children, adolescents and adults all tended to be lower for high-quality studies compared with medium-quality studies. Our results indicated that cesarean section was moderately associated with offspring overweight and obesity. This finding has public health implications, given the increase in cesarean births in many countries.
High-power single-frequency fiber lasers with exceptional properties, such as mode-hop-free and narrower linewidths, lower noise, and compact all-fiber designs, have been attractive in many ...applications, including high-resolution sensing, coherent telecommunications, optical frequency domain reflectometry, and as a seed laser for light detection and ranging (LIDAR). However, the development of high-power single-frequency fiber lasers is constrained greatly by the lack of high-gain optical fiber and components. In this review, we discuss the basic considerations of advanced techniques for soft glass fiber and fiber preform as well as three key issues among them. Then, the recent advances in RE-doped soft glass and fiber lasers operating at near-infrared (NIR) and mid-infrared (MIR) wavelengths are evaluated in detail. Finally, prospects, applications and challenges for the realization of high-efficiency soft optical fibers in single-frequency fiber laser applications are analyzed and discussed. The review is organized as follows: Sections 1–3 introduce the basic requirements for the rare-earth (RE) ions and host matrix material for obtaining efficient NIR-MIR laser output, a review of the background of processing fundamentals on the fabrication and characterization for newly developed soft optical glass fibers, an outline of the key issues of platinum removal and the dehydration technique, effective doping of RE, and low splicing loss together with the recent theoretical and experimental results. Section 4 summaries the design and development of RE-doped soft optical glass and fiber lasers operating at 1, 1.5, 2, and 3 μm with emphatical discussions on the related luminescence mechanism and laser foundation as well as single-frequency lasers. Section 5 reviews the recent progress of various novel glass fibers and fiber lasers with unique photoelectricity properties, such as transparent glass-ceramic fiber and fiber lasers, quantum-dot fiber and fiber lasers, Bi-doped fiber and fiber lasers, as well as other novel glass fibers and devices, and outlines their prospects, applications, and challenges. Furthermore, Section 6 presents the conclusions of this review, which include the following: (1) From the single-component silica fiber to the multicomponent soft optical glass fiber, the glass compositions become more and more complex and the corresponding preparation method is constantly developing and improving. Various new types of optical fiber materials and components greatly expand their applications in the fields of fiber amplifiers, fiber lasers, and nonlinear optics, etc. (2) High-gain optical fiber is the key to the development of high-power single-frequency fiber lasers. To achieve intense and highly-efficient luminescence and lasers at the NIR and MIR regions from soft glass and optical fiber, the following methods were adopted, including using RE sensitization, uniform doping with high-concentration RE, hydroxyl and impurity-removing, new optical fiber and laser cavity design, low fusing loss, and the high-efficiency pumping method, etc. These novel glass systems and luminescence mechanisms enrich the glass systems of the past and provide a wealth of valuable data for optoelectronic materials and devices.
We perform a systematic study of all cities in Europe to assess the Urban Heat Island (UHI) intensity by means of remotely sensed land surface temperature data. Defining cities as spatial clusters of ...urban land cover, we investigate the relationships of the UHI intensity, with the cluster size and the temperature of the surroundings. Our results show that in Europe, the UHI intensity in summer has a strong correlation with the cluster size, which can be well fitted by an empirical sigmoid model. Furthermore, we find a novel seasonality of the UHI intensity for individual clusters in the form of hysteresis‐like curves. We characterize the shape and identify apparent regional patterns.
Key Points
Nouvelle method to automatically measure UHI intensity
Typical maximum UHI intensity of 3{degree sign}C (Europe)
Hysterisis‐like seasonality
Summary
To identify the relationship between proton-pump inhibitors (PPIs) and the risk of fracture, we conducted an update meta-analysis of observational studies. Results showed that PPI use was ...associated with a modestly increased risk of hip, spine, and any-site fracture.
Introduction
Many studies have investigated the association of proton-pump inhibitors (PPIs) with fracture risk, but the results have been inconsistent. To evaluate this question, we performed a meta-analysis of relevant observational studies.
Methods
A systematic literature search up to February 2015 was performed in PubMed. We combined relative risks (RRs) for fractures using random-effects models and conducted subgroup and stratified analyses.
Results
Eighteen studies involving a total of 244,109 fracture cases were included in this meta-analysis. Pooled analysis showed that PPI use could moderately increase the risk of hip fracture RR = 1.26, 95 % confidence intervals (CIs) 1.16–1.36. There was statistically significant heterogeneity among studies (
p
< 0.001;
I
2
= 71.9 %). After limiting to cohort studies, there was also a moderate increase in hip fracture risk without evidence of study heterogeneity. Pooling revealed that short-term use (<1 year) and longer use (>1 year) were similarly associated with increased risk of hip fracture. Furthermore, a moderately increased risk of spine (RR = 1.58, 95 % CI 1.38–1.82) and any-site fracture (RR = 1.33, 95 % CI 1.15–1.54) was also found among PPI users.
Conclusion
In this update meta-analysis of observational studies, PPI use modestly increased the risk of hip, spine, and any-site fracture, but no evidence of duration effect in subgroup analysis.
Three-dimensional (3D) topological Dirac semimetals (TDSs) represent an unusual state of quantum matter that can be viewed as "3D graphene." In contrast to 2D Dirac fermions in graphene or on the ...surface of 3D topological insulators, TDSs possess 3D Dirac fermions in the bulk. By investigating the electronic structure of Na3Bi with angle-resolved photoemission spectroscopy, we detected 3D Dirac fermions with linear dispersions along all momentum directions. Furthermore, we demonstrated the robustness of 3D Dirac fermions in Na3Bi against in situ surface doping. Our results establish Na3Bi as a model system for 3D TDSs, which can serve as an ideal platform for the systematic study of quantum phase transitions between rich topological quantum states.
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