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In this work we investigate transverse mode instability (TMI) in the presence of pump intensity noise and a controlled perturbation of the input coupling for a rod-type fiber amplifier using spatially and temporally resolved imaging (ST). We show that inherent pump intensity noise from the power supply can define significant peaks in the resulting TMI spectrum. ST measurements in the transition region of TMI also indicates that the simple picture of TMI being seeded by the combination of a static initial fraction of LP11 and pump or signal intensity noise is not valid for our measurements. Furthermore, we present seeding of TMI by perturbing the input coupling dynamically which allows measurements of the TMI gain as a function of frequency and signal power.

In this work a novel accurate method of measuring beam fluctuations is presented and applied to analyze transverse mode instabilities (TMI). The new measurement, ST-measurement, uses Fourier analysis on data from a high-speed camera to achieve raw spatial information about beam fluctuations. TMI in a 65 μm mode- field-diameter aeroGain-ROD-PM85 fiber is investigated using both the ST- and standard photo detector measurement. A comparison of the two measurements shows the quantitative and qualitative superiority of the new ST-measurement due to the spatial information. Numerical simulations are carried out to support the interpretation of the data.

In this work we investigate transverse mode instability (TMI) in the presence of pump intensity noise and a controlled perturbation of the input coupling for a rod-type fiber amplifier using spatially and temporally resolved imaging (ST). We show that inherent pump intensity noise from the power supply can define significant peaks in the resulting TMI spectrum. ST measurements show that the TMI in the transition region consists of different orientations of LP11. This finding indicates that the simple picture of TMI being seeded by the combination of a static initial fraction of LP11 and pump or signal intensity noise is not valid for our measurements. Furthermore we present seeding of TMI by perturbing the input coupling dynamically. ST measurements of the resulting TMI as a function of perturbation frequency provides quantitative information regarding the frequency response of the non-linear coupling coefficient. Finally, ST measurements of the resulting TMI as a function of signal power shows that the TMI experiences an exponential gain long before visible beam fluctuations appear.

Aims/hypothesis The aim was to investigate whether an intensive lifestyle intervention, with high volumes of exercise, improves beta cell function and to explore the role of low-grade inflammation and body weight.Methods This was a randomised, assessor-blinded, controlled trial. Ninety-eight individuals with type 2 diabetes (durationResults At baseline, individuals were 54.8 years (SD 8.9), 47% women, type 2 diabetes duration 5 years (IQR 3-8) and HbA(1c)was 49.3 mmol/mol (SD 9.2); 6.7% (SD 0.8). The intensive lifestyle group showed 40% greater improvement in the disposition index compared with the standard care group (ratio of geometric mean change [RGM] 1.40 [95% CI 1.01, 1.94]) from baseline to 12 months' follow-up. Plasma concentration of IL-1 receptor antagonist (IL-1ra) decreased 30% more in the intensive lifestyle group compared with the standard care group (RGM 0.70 [95% CI 0.58, 0.85]). Statistical single mediation analysis estimated that the intervention effect on the change in IL-1ra and the change in body weight explained to a similar extent (59%) the variance in the intervention effect on the disposition index.Conclusions/interpretation Our findings show that incorporating an intensive lifestyle intervention, with high volumes of exercise, in individuals with type 2 diabetes has the potential to improve beta cell function, associated with a decrease in low-grade inflammation and/or body weight.

Single-pass amplification using rod-type fibers has become a common route to pulsed laser sources around 1030 nm with high average and peak power. Average-power scaling is currently limited by the dynamic thermo-optic phenomenon of “transverse mode instability.” In comparison, double-pass amplifier configurations have not been extensively studied. Recent theoretical and experimental work has shown both static and dynamic mode degradation phenomena, including an unexpected nonlinear polarization rotation effect. Here we present new results obtained with a modified setup using polarization filtering between the first and the second pass. We obtain up to 113 W output power, i.e., more than 40 dB of amplification from a single amplifier module seeded by 10 mW of 20 ps/20 MHz/1030 nm pulses. We observe excellent beam quality and polarization extinction ratio. Finally, we investigate a wide range of seed powers and report a strong increase in the static mode deformation threshold with decreasing seed power. The experimental results are corroborated by numerical simulations.

In this work, an all-solid Ytterbium doped double-clad single-mode (SM) large-mode-area (LMA) photonic crystal fiber (PCF) is characterized in a monolithic amplifier setup. The characterized all-solid PCF combines the SM operation of LMA PCFs while maintaining simple splicing of all-solid fibers. The fiber has been tested in a pulsed monolithic forward pumped amplifier system achieving excellent modal properties. The fiber is polarization maintaining and has a mode field diameter of approximately 24 μm. At optimal fiber length the output signal power of the amplifier was measured to 43 W limited by pump power with an optical to optical efficiency of 61 %. Polarization extinction ratios (PER) above 18 dB was observed for all fiber lengths. Simple splicing with splice losses < 0.2 dB and maintained polarization are reported using a standard Fujikura fusion splicer.

OBJECTIVE: The primary objective was to test the hypothesis that increased frequency of interruptions in prolonged sitting reduces postprandial glycemia independent of energy intake and expenditure.MATERIALS/METHODS: Healthy, sedentary, centrally obese men (n = 14; age*, 28.2 (23.4; 38.3) years; BMI, 31.9 ± 6.7 kg/m2; VO2max*, 39.5 (38.8; 40.9) ml/min/kg; HbA1c, 5.3 ± 0.4% (34.1 ± 4.2 mmol/mol); mean ± SD (*median (25th; 75th percentile)) completed four 8-h interventions in randomized order: 1) uninterrupted sitting (SIT), 2) sitting interrupted by 2 min of walking (~30% of VO2max) every 20th minute (INT20), 3) sitting interrupted by 6 min of walking every hour (INT60), and 4) sitting interrupted by 12 min of walking every second hour (INT120). A standardized test drink was served at the beginning of and 4 h into the intervention (total of 2310 ± 247 kcal; 50% energy from carbohydrate, 50% energy from fat). Outcomes included the difference in the 8-h total area under the curve (tAUC) for primarily plasma glucose, and secondarily plasma insulin and C-peptide during INT20, INT60, and INT120 compared to SIT.RESULTS: No difference [95% CI] was observed in the primary outcome, the 8-h tAUC for the plasma glucose, during INT20, INT60, and INT120 compared to SIT (-65.3 mmol/l∗min [-256.3; 125.7], +53.8 mmol/l∗min [-143.1; 250.8], and +18.6 mmol/l∗min [-172.4; 209.6], respectively).CONCLUSIONS: Interrupting sitting with increasing frequency did not reduce the postprandial plasma glucose response to prolonged sitting in healthy, sedentary, centrally obese men.