The Airy fibre: an optical fibre that guides light diffracted by a circular aperture

We have designed and made an optical fibre that guides an approximate Airy pattern as one of its guided modes. The fibre's attenuation was 11.0 dB/km at 1550 nm wavelength, the match between the fibre's mode and the ideal infinite Airy pattern was 93.7%, and the far field resembled a top-hat beam. The guidance mechanism has strong similarities to photonic bandgap guidance.Comment: 11 page

Global mindedness and dispositions towards diversity in the classroom

This study examined global mindedness and dispositions towards diversity in the classroom between two groups of teacher candidates. One group had obtained a bachelors degree before starting the teacher education program while the other group started the teacher education program without a college degree. The global mindedness scale (GMS) and the Teacher Multicultural Attitude Scale developed by Hett (1993) and Ponterrotto (2004) respectively were used for the study.;The study was guided by four research questions and four corresponding hypotheses. Univariate t-tests were use to analyze data for research questions one and two to determine the difference between the mean scores of the two groups of teacher candidates. For research question three, a correlation analysis was used to determine the relationship between teacher candidates\u27 global mindedness and dispositions towards diversity in the classroom. A multivariate analysis of variance (MANOVA) was used to determine the interactions between the demographic variables and the latent variables of global mindedness and dispositions towards diversity.;Though both groups of teacher candidates were positively disposed to global mindedness and diversity in the classroom, the study found that teacher candidates with a prior college degree showed a more positive orientation towards global mindedness and diversity issues in the classroom. The study also found a positive relationship between global mindedness and disposition toward diversity in the classroom. Thus the more globally minded teacher candidates were the more positively they were disposed to diversity issues in the classroom and vice versa. Finally, the study found that the demographic variables of age, teaching experience, travel/study abroad experience were positively related to global mindedness and disposition towards diversity in the classroom

Semantic bottleneck for computer vision tasks

This paper introduces a novel method for the representation of images that is semantic by nature, addressing the question of computation intelligibility in computer vision tasks. More specifically, our proposition is to introduce what we call a semantic bottleneck in the processing pipeline, which is a crossing point in which the representation of the image is entirely expressed with natural language , while retaining the efficiency of numerical representations. We show that our approach is able to generate semantic representations that give state-of-the-art results on semantic content-based image retrieval and also perform very well on image classification tasks. Intelligibility is evaluated through user centered experiments for failure detection

Texture, twinning and metastable "tetragonal" phase in ultrathin films of HfO₂ on a Si substrate

Thin HfO<sub>2</sub> films grown on the lightly oxidised surface of (100) Si wafers have been examined using dark-field transmission electron microscopy and selected area electron diffraction in plan view. The polycrystalline film has a grain size of the order of 100 nm and many of the grains show evidence of twinning on (110) and (001) planes. Diffraction studies showed that the film had a strong [110] out-of-plane texture, and that a tiny volume fraction of a metastable (possibly tetragonal) phase was retained. The reasons for the texture, twinning and the retention of the metastable phase are discussed

Flexible Blue-Light Fiber Amplifiers to Improve Signal Coverage in Advanced Lighting Communication Systems

Visible-light communication (VLC) based on white light-emitting diodes has recently attracted much attention to provide high-bitrate data communication in indoor environments. One of the remaining challenges to be resolved to enable the proliferation of VLC systems is related to channel attenuation and multiple path fading. Here, we introduce an advanced VLC system integrating an optical amplifier as a promising solution to overcome channel impairments, providing high bitrate coverage. The optical amplifier is a flexible fiber based on a poly(fluorene)-based lumophore doped within a di-ureasil organic-inor- ganic hybrid. Optical amplification is demonstrated for pre-amplifier and relay node scenarios, yielding a maximum gain of 5.9 G 0.2 dB and 3.7 G 0.2 dB, respectively, establishing the proposed approach as a promising cost-effective solution for VLCs. Additionally, numerical simulations show, for a realistic envi- ronment, a 207% improvement in the coverage area, using existing lighting infrastructure without extra cost.R.C.E. acknowledges funding from the European Research Council (ERC) under the European Union’s Ho- rizon 2020 research and innovation programme (grant agreement no. 818762 - SPECTRACON)

Procoagulant changes in fibrin clot structure in patients with cirrhosis are associated with oxidative modifications of fibrinogen

Patients with cirrhosis have hemostatic changes, which may contribute to a risk of thrombosis. This in vitro study compares clot formation and structure between patients and healthy subjects. Clot formation is delayed in patients; ultimately, however, clot permeability is decreased. The thrombogenic structure of fibrin clots may contribute to the thrombotic risk in cirrhosis. Background and Objectives: Patients with cirrhosis can be at risk of thrombotic complications due to an imbalance between hemostatic components. However, little is known on how the disease affects clot generation or how alterations in the structure of fibrin clots may affect the hemostatic function of these patients. Methods: We investigated the formation and structure of clots generated with plasma and purified fibrinogen of 42 patients with cirrhosis. Clots generated with plasma and fibrinogen of 29 healthy volunteers were studied for comparison. Clot formation and structure were assessed by turbidity, permeation studies, confocal laser and scanning electron microscopy (SEM). The extent of fibrinogen oxidation was assessed by measuring the carbonyl content of purified fibrinogen samples. Results: Tissue factor and thrombin-induced clotting of plasma was delayed in patients. The clotting rate was also decreased, but change in turbidity, fibrin density and fiber thickness were largely comparable to healthy volunteers. Conversely, clot permeability was significantly decreased in patients. When clots were generated with purified fibrinogen, differences in clot formation and structure similar to those in plasma were found. The carbonyl content was increased in patient fibrinogen and correlated with disease severity and clot permeability. Conclusions: Delayed clot formation in cirrhosis ultimately results in decreased clot permeability. Similar alterations in clots generated with purified fibrinogen suggest that modifications of the molecule are (partly) responsible. Taken together, these findings are indicative of hypercoagulable features of clots of patients with cirrhosis, which may explain the increased risk of thrombosis associated with this condition

A Systematic Review with Meta-Analysis of Randomized Controlled Trials

Objective Epidemiological evidence has linked consumption of black tea, produced from Camellia sinensis, with a reduced risk of cardiovascular diseases. However, intervention studies on the effects of tea consumption on blood pressure (BP) have reported inconsistent results. Our objective was to conduct a systematic literature review with meta-analysis of controlled human intervention studies examining the effect of tea consumption on BP. Methods We systematically searched Medline, Biosis, Chemical Abstracts and EMBASE databases through July 2013. For inclusion, studies had to meet the following pre-defined criteria: 1) placebo controlled design in human adults, 2) minimum of 1 week black tea consumption as the sole intervention, 3) reported effects on systolic BP (SBP) or diastolic BP (DBP) or both. A random effects model was used to calculate the pooled overall effect of black tea on BP. Results Eleven studies (12 intervention arms, 378 subjects, dose of 4–5 cups of tea) met our inclusion criteria. The pooled mean effect of regular tea ingestion was −1.8 mmHg (95% CI: −2.8, −0.7; P = 0.0013) for SBP and −1.3 mmHg (95% CI: −1.8, −0.8; P<0.0001) for DBP. In covariate analyses, we found that the method of tea preparation (tea extract powders versus leaf tea), baseline SBP and DBP, and the quality score of the study affected the effect size of the tea intervention (all P<0.05). No evidence of publication bias could be detected. Conclusions Our meta-analysis indicates that regular consumption of black tea can reduce BP. Although the effect is small, such effects could be important for cardiovascular health at population level

Why Fibrin Biomechanical Properties Matter for Haemostasis and Thrombosis.

Polymeric fibrin displays unique structural and biomechanical properties that contribute to its essential role of generating blood clots that stem bleeds. The aim of this review is to discuss how the fibrin clot is formed, how protofibrils make up individual fibrin fibers, what the relationship is between the molecular structure and fibrin biomechanical properties, and how fibrin biomechanical properties relate to the risk of thromboembolic disease. Fibrin polymerization is driven by different types of bonds, including knob-hole interactions displaying catch-slip characteristics, and covalent crosslinking of fibrin polypeptides by activated factor XIII. Key biophysical properties of fibrin polymer are its visco-elasticity, extensibility and resistance to rupture. The internal packing of protofibrils within fibers changes fibrin biomechanical behavior. There are several methods to analyze fibrin biomechanical properties at different scales, including AFM force spectroscopy, magnetic or optical tweezers and rheometry, amongst others. Clinically, fibrin biomechanical characteristics are key for the prevention of thromboembolic disorders such as pulmonary embolism. Future studies are needed to address unanswered questions regarding internal molecular structure of the fibrin polymer, the structural and molecular basis of its remarkable mechanical properties and the relationship of fibrin biomechanical characteristics with thromboembolism in patients with deep vein thrombosis and ischemic stroke