We present a first attempt to experimentally extract an effective strong coupling constant that we define to be a low Q2 extension of a previous definition by S. Brodsky et al. following an initial work of G. Grunberg. Using Jefferson Lab data and sum rules, we establish its Q2-behavior over the complete Q2-range. The result is compared to effective coupling constants inferred from different processes and to calculations based on Schwinger-Dyson equations, hadron spectroscopy or lattice QCD. Although the connection between the experimentally extracted effective coupling constants and the calculations is not established it is interesting to note that their behaviors are similar.Comment: Published in Physics Letters B 650 4 24

In this paper, we report 4 different saturable absorbers based on 4 transition metal dichalcogenides (MoS(2), MoSe(2), WS(2), WSe(2)) and utilize them to Q-switch a ring-cavity fiber laser with identical cavity configuration. It is found that MoSe(2) exhibits highest modulation depth with similar preparation process among four saturable absorbers. Q-switching operation performance is compared from the aspects of RF spectrum, optical spectrum, repetition rate and pulse duration. WS(2) Q-switched fiber laser generates the most stable pulse trains compared to other 3 fiber lasers. These results demonstrate the feasibility of TMDs to Q-switch fiber laser effectively and provide a meaningful reference for further research in nonlinear fiber optics with these TMDs materials.

Two-dimensional (2D) nanomaterials, especially the transition metal sulfide semiconductors, have drawn great interests due to their potential applications in viable photonic and optoelectronic devices. In this work, 2D tungsten disulfide (WS2) based saturable absorber (SA) for ultrafast photonic applications was demonstrated. WS2 nanosheets were prepared using liquid-phase exfoliation method and embedded in polyvinyl alcohol (PVA) thin film for the practical usage. Saturable absorption was discovered in the WS2-PVA SA at the telecommunication wavelength near 1550 nm. By incorporating WS2-PVA SA into a fiber laser cavity, both stable mode locking operation and Q-switching operation were achieved. In the mode locking operation, the laser obtained femtosecond output pulse width and high spectral purity in the radio frequency spectrum. In the Q-switching operation, the laser had tunable repetition rate and output pulse energy of a few tens of nano joule. Our findings suggest that few-layer WS2 nanosheets embedded in PVA thin film are promising nonlinear optical materials for ultrafast photonic applications as a mode locker or Q-switcher.

PurposeTo describe the imaging standards, grading protocol and baseline characteristics of polypoidal choroidal vasculopathy (PCV) from the EVEREST study.MethodsIn a prospective, multicentre study, confocal scanning laser ophthalmoscope indocyanine green angiography (ICGA) was performed using a standardised imaging protocol. All images were graded using standardised, calibrated equipment by fellowship-trained ophthalmologists at the Central Reading Center.ResultsSixty-one patients with PCV were included in the study. ICGA characteristics included: nodular appearance stereoscopically (56 eyes, 91.8%), hypofluorescent halo (42, 68.9%), abnormal vascular network (54, 88.5%) and pulsation of the polyps (4, 6.6%). Colour fundus photography revealed orange subretinal nodules (34, 55.7%) and massive submacular haemorrhage (8, 13.1%). The mean area of the PCV lesion was 3.11 mm2 (range, 0.2–10.7 mm2). The vascular channels filled within 7.3–32.0 s (mean: 17.9 s) while the mean filling time for polyps was 21.9 s (range, 7.3–40.4 s). Patients with massive submacular haemorrhage were less likely to have abnormal vascular channels seen on ICGA (28.6% vs 83.3% for those without massive haemorrhage, p=0.001).ConclusionsThe imaging and grading protocols and baseline characteristics of a multicentre, randomised controlled trial of PCV are described in detail, and may serve as reference for future randomised, controlled trials on PCV.Clinical trial numberThis work was supported by Novartis Pharma AG, Basel, Switzerland grant number NCT00674323 (clinicaltrials.gov).

Plant hormones play a vital role in plant immune responses. However, in contrast to the relative wealth of information on hormone-mediated immunity in dicot plants, little information is available on monocot-virus defense systems. We used a high-throughput-sequencing approach to compare the global gene expression of Rice black-streaked dwarf virus (RBSDV)-infected rice plants with that of healthy plants. Exogenous hormone applications and transgenic rice were used to test RBSDV infectivity and pathogenicity. Our results revealed that the jasmonic acid (JA) pathway was induced while the brassinosteroid (BR) pathway was suppressed in infected plants. Foliar application of methyl jasmonate (MeJA) or brassinazole (BRZ) resulted in a significant reduction in RBSDV incidence, while epibrassinolide (BL) treatment increased RBSDV infection. Infection studies using coi1-13 and Go mutants demonstrated JA-mediated resistance and BR-mediated susceptibility to RBSDV infection. A mixture of MeJA and BL treatment resulted in a significant reduction in RBSDV infection compared with a single BL treatment. MeJA application efficiently suppressed the expression of BR pathway genes, and this inhibition depended on the JA coreceptor OsCOI1. Collectively, our results reveal that JA-mediated defense can suppress the BR-mediated susceptibility to RBSDV infection.