Evaluation of Metarhizium brunneum- and Metarhizium-Derived VOCs as Dual-Active Biostimulants and Pest Repellents in a Wireworm-Infested Potato Field.

Wireworm, the larval stages of click beetles, are a serious pest of tubers, brassicas and other important commercial crops throughout the northern hemisphere. No effective control agent has been developed specifically for them, and many of the pesticides marketed as having secondary application against them have been withdrawn from EU and Asian markets. Metarhizium brunneum, an effective entomopathogenic fungus, and its derived volatile metabolites are known to be effective plant biostimulants and plant protectants, although field efficacy has yet to be validated. Field validation of a combined M. brunneum and derived VOC treatments was conducted in Wales, UK, to assess the effects of each as a wireworm control agent and biostimulant. Plots were treated with Tri-Soil (Trichoderma atroviridae), M. brunneum, 1-octen-3-ol or 3-octanone, or combinations thereof. Treatments were applied subsurface during potato seeding (n = 52), and potatoes were harvested at the end of the growing season. Each potato was weighed individually and scored for levels of wireworm damage. Applications of both the VOCs and the M. brunneum individually were found to significantly decrease wireworm burden (p < 0.001). Combinations of M. brunneum and 3-octanone were also found to significantly decrease wireworm damage (p < 0.001), while no effect on yield was reported, resulting in an increased saleable mass over controls (p < 0.001). Herein, we present a novel 'stimulate and deter' wireworm control strategy that can be used to significantly enhance saleable potato yields and control wireworm populations, even under high pest pressure densities.

Coherent beam combination of seven 1.5 µm fiber amplifiers through up to 1 km atmospheric turbulence: near- and far-field experimental analysis.

A laser testbed based on active coherent beam combination (CBC) of seven 1.5 µm, 3 W fiber amplifiers was developed for applications requiring high power such as power density deposition on targets or free space laser communication. For the first time to our knowledge, the frequency-tagging locking of optical coherence by single-detector electronic-frequency tagging technique was implemented in the field in real atmospheric turbulence conditions in a target-in-the-loop configuration. Successful combination was achieved after horizontal propagation of 311 m and 1 km, at 1.5 m above the ground, while the estimated average turbulence strength was Cn2∼4.10-14m-2/3. We present the CBC laser bench and an embedded near-field interferometer called PISTIL (PISton and TILt) able to measure the relative phase shift of each emitter. We show that this measurement can provide information on relative turbulence-induced phase variation of the combined laser beams. In particular, the far-field beam envelope wandering can be estimated through this diagnosis. Results are supported by an analytical model and confirmed by numerical post-analysis of measured far-field interference. This additional interferometer may improve CBC beam pointing through turbulence.

Realization and simulation of high-power holmium doped fiber lasers for long-range transmission.

We report on our realization of a high-power holmium doped fiber laser, together with the validation of our numerical simulation of the laser. We first present the measurements of the physical parameters that are mandatory to model accurately the laser-holmium interactions in our silica fiber. We then describe the realization of the clad-pumped laser, based on a triple-clad large mode area holmium (Ho) doped silica fiber. The output signal power is 90 W at 2120 nm, with an efficiency of about 50% with respect to the coupled pump power. This efficiency corresponds to the state of the art for clad-pumped Ho-doped fiber lasers in the 100 W power class. By comparing the experimental results to our simulation, we demonstrate its validity and use it to show that the efficiency is limited, for our fiber, by the non-saturable absorption caused by pair-induced quenching between adjacent holmium ions.

Evaluating unmet needs in patients undergoing surgery for colorectal cancer: a patient reported outcome measures study.

AIM: Patient reported outcome measures (PROMs) are self-reported measures of patients' health status or health-related quality of life at a single point in time. We aimed to evaluate the use of a colorectal PROM and conducted a focus group to further explore this and other unmet needs in our patient population treated surgically for colorectal cancer. METHOD: A multidisciplinary research group consisting of colorectal surgeons, nurse specialists, psychologists, sociologists and patient representatives devised a composite tool of new and existing outcome measures which was piloted in our local population (n = 35). Participants were subsequently invited to attend a semi-structured focus group during which the PROM was reviewed and an unmet needs analysis was performed. Thematic analysis of focus group transcripts was undertaken for emergent themes. RESULTS: Initial consensus was for a tool including the EQ-5D, Functional Assessment of Cancer Therapy - Colorectal (FACT-C), the distress thermometer, a validated measure of stigma, an unmet needs analysis, and questions assessing the psychological impact of cancer. Median and interquartile range values suggested that all metrics were discriminatory with the exception of FACT-C. All participants agreed that the tool was acceptable and reflected the current state of their health and emotions. Thematic analysis of focus group transcripts identified four major themes: physical symptoms, emotional response, information provision and coping mechanisms. CONCLUSION: Through expert consensus, local piloting and patient focus groups we have evaluated a novel PROM for colorectal cancer. Furthermore, through our direct engagement with patients we have identified several unmet needs which we are currently exploring within the clinical service.

Coherent combining of mid-infrared difference frequency generators.

We report what is, to the best of our knowledge, the first experimental demonstration of coherent combining of two mid-infrared difference frequency generators by active phase control in the continuous-wave regime. Using the phase relation that is inherent to the nonlinear process, we are able to phase lock and combine the idler waves by the sole phase control of one of the pump waves. This control is done by an all-fiber electro-optic modulator. Combining is achieved with an excellent efficiency with a residual phase error of λ/28.

Coherent combining of second-harmonic generators by active phase control of the fundamental waves.

Coherent beam combining by active phase control could be useful for power scaling fiber-laser-pumped optical frequency converters. However, a fast phase modulator operating at the frequency-converted wavelength, a non-standard component, would be necessary. Fortunately, nonlinear conversion processes rely on a phase-matching condition allowing for indirect phase control using standard phase modulators. In this Letter, coherent combining of second-harmonic generators is demonstrated in both birefringent and quasi-phase-matching schemes in CW regime. Phase control operates at the fundamental wavelength, using all-fiber electro-optic modulators. An excellent beam combination is achieved with a residual phase error of λ/30 on the second-harmonic wave.

26 nJ picosecond solitons from thulium-doped single-mode master oscillator power fiber amplifier.

We report on an all single-mode master oscillator power fiber amplifier delivering high energy picosecond solitons at 1960 nm. The Bragg stabilized and self-starting oscillator delivers 62 pJ transform-limited pulses at 11.2 MHz pulse repetition frequency. Solitons are amplified in a core-pumped single-mode heavily thulium-doped fiber up to 26 nJ. The average and peak power are 291 mW and 7.4 kW, respectively. Pulses remain transform limited without significant self-phase-modulation distortion. We discuss the limitations of picosecond pulse amplification in a core-pumped single-mode fiber amplifier.

Analysis of the multifilament core fiber using the effective index theory.

Multifilament core (MFC) fibers are a new type of microstructured fiber recently introduced. We investigate their properties using finite element modeling and show that the equivalent step index fiber based on moments theory does not provide similar properties. We propose an effective index theory based on the fundamental space filling mode which allows to predict the MFC properties using a semi-analytical modeling. Good resistance to bending is thus attributed to increased core effective index due to the high index filaments.