The propagation behavior of high-frequency intensity-modulated signals through turbid water is of significant interest for underwater laser ranging, imaging, and communications. Prior experimental measurements have focused only on the magnitude response of the underwater optical channel to forward-scattered and unscattered modulated light. In this study we include, for the first time to our knowledge, both the magnitude and phase of the underwater optical channel to forward-scattered light. The magnitude and phase response is measured out to 1 GHz, using three different artificial scattering agents in scattering environments in excess of 25 attenuation lengths. The phase response provides additional insight into the behavior of forward-scattered light carrying high-frequency intensity modulation.

The attenuation and temporal dispersion of beams with and without orbital angular momentum (OAM) underwater are investigated in a controlled laboratory water tank environment. Both spherical polystyrene beads and a commercial antacid are used to determine the effect of scattering particle size and shape on the results. Varying concentrations of the scattering agents were used to study the propagation of light in both minimally scattered and multiply scattered regimes (over 20 attenuation lengths). To study temporal dispersion, a custom diode seeded fiber amplified laser source is used to modulate beams up to 1 GHz, and diffractive spiral phase plates are used to compare performance over different spatial modes. We observe an increase in received signal with increasing OAM order (|m|=0, 8, and 16) under multiple scattering conditions. Initial experimental results suggest that this variation is dependent on particle shape and size. We do not observe any dependency of OAM order on temporal dispersion.

We present a novel chaotic lidar system designed for underwater impulse response measurements. The system uses two recently introduced, low-cost, commercially available 462 nm multimode InGaN laser diodes, which are synchronized by a bi-directional optical link. This synchronization results in a noise-like chaotic intensity modulation with over 1 GHz bandwidth and strong modulation depth. An advantage of this approach is its simple transmitter architecture, which uses no electrical signal generator, electro-optic modulator, or optical frequency doubler.

We report what is to our knowledge the first use of Fourier phase microscopy (FPM) to estimate diameters of individual single-micrometer beads and to classify cells based upon changes in scatterer size distribution. FPM, a quantitative phase imaging (QPI) method, combines the planar illumination typically used in off-axis QPI (ideal for Mie theory analysis) with the common-path geometry typically used in on-axis QPI (ideal for optimizing angular scattering range). Low-spatial-frequency imaging artifacts inherent to FPM have negligible impact upon these angular-domain applications. The system is simple to align and stable, and requires no external reference beam. Angular scattering patterns obtained from single 1 µm polystyrene beads in glycerol ( Δ n = 0.11 ) display unprecedented fidelity to Mie theory, produce diameter estimates consistent with the manufacturer’s specifications, and offer precision on the scale of tens of nanometers. Measurements of macrophages at different stages of antibody-dependent cellular phagocytosis demonstrate the ability to detect changes in a cell’s scattering caused by the presence of phagocytosed material within.

Purpose: To determine if cancer survivors who perform physical activity (PA) during chemotherapy have improved levels of cognitive function compared to those who do not. Method: E-databases (Ovid MEDLINE, Embase, CINAHL, PsycINFO, AMED) were searched from inception to February 4, 2020. Quantitative studies that assessed cognitive outcomes for adults with any cancer type who received chemotherapy concurrent with PA were selected. Risk of bias was assessed using Cochrane’s RoB 2, ROBINS-I, and Newcastle Ottawa scales. A meta-analysis was performed using standardized mean difference (SMD). Results: Twenty-two studies (15 randomized controlled trials (RCTs) and 7 non-RCTs) met the inclusion criteria. The meta-analysis demonstrated that combined resistance and aerobic training had a small yet statistically significant effect on social cognition compared to usual care (SMD (95% CI) = 0.23 (0.04, 0.42), p = 0.020). Conclusions: Combined resistance and aerobic exercise may benefit social cognition in cancer survivors undergoing chemotherapy. Due to high risk of bias and low quality of evidence of included studies, we recommend further investigation to support these findings and make specific PA recommendations.