Exploring flatfeet morphology in children aged 6-12 years: relationships with body mass and body height through footprints and three-dimensional measurements.

The aim of the study was to determine the relationship between flatfoot morphology and body mass and height in children aged 6-12 years. A total of 6471 Chinese children (mean age 9.0 ± 1.9 years, 41% female) were assessed for foot morphometry, body height, and body mass index. Foot morphology, including foot length, width, girth, arch height, hallux valgus angle, and rearfoot valgus angle, was measured using a 3D laser scanner. Flatfoot evaluations were conducted using the Sztriter-Godunov index (KY) from footprints. All measurements were analyzed by age and sex using the mean values of the left and right sides. Comparisons were performed between flatfoot groups, between body mass index (BMI) groups, and between body height groups. The study revealed a significant decrease in the incidence of bipedal flatfoot with age (p < 0.001), whereas the prevalence of obesity remained consistent (p > 0.05). Bipedal flatfoot was associated with distinct morphological changes, including lower arches, reduced instep height, diminished ankle heights and a greater rearfoot valgus angle (p < 0.05). When comparing the BMI groups, overweight children had larger and thicker feet (p < 0.05), but no differences were found in arch height and ankle height (p > 0.05). When comparing the body height groups, short-statured children had a shorter feet girth, shorter arches, and shorter ankle height (p < 0.05), but no differences were found in the rearfoot valgus angle (p > 0.05). CONCLUSION: The main characteristics of flat feet include lower arches and instep heights and ankle heights but higher rearfoot valgus angles. In general, overweight children's feet do not have the common features of flat feet. In contrast, short children had similar features of flatfoot except for rearfoot valgus. Assessment of posture, such as rearfoot valgus, can be critical in identifying children with flat feet. WHAT IS KNOWN: • The morphology of children's feet is associated with body growth, but the relationship between flatfeet and body mass and height remains controversial. WHAT IS NEW: • Three-dimensional foot measurement shows that body mass is generally not associated with flatfeet, while short children have lower arches but no rearfoot valgus.

Optical orbital-angular-momentum-multiplexed data transmission under high scattering.

Multiplexing multiple orbital angular momentum (OAM) channels enables high-capacity optical communication. However, optical scattering from ambient microparticles in the atmosphere or mode coupling in optical fibers significantly decreases the orthogonality between OAM channels for demultiplexing and eventually increases crosstalk in communication. Here, we propose a novel scattering-matrix-assisted retrieval technique (SMART) to demultiplex OAM channels from highly scattered optical fields and achieve an experimental crosstalk of -13.8 dB in the parallel sorting of 24 OAM channels after passing through a scattering medium. The SMART is implemented in a self-built data transmission system that employs a digital micromirror device to encode OAM channels and realize reference-free calibration simultaneously, thereby enabling a high tolerance to misalignment. We successfully demonstrate high-fidelity transmission of both gray and color images under scattering conditions at an error rate of <0.08%. This technique might open the door to high-performance optical communication in turbulent environments.

Calibrating oscillation response of a piezo-stage using optical tweezers.

In optical tweezers, a piezo-stage (PZT) is widely used to precisely position samples for force clamp, calibrating optical trap and stretching DNA. For a trapped bead in solution, the oscillation response of PZT is vital for all kinds of applications. A coupling ratio, actual amplitude to nominal amplitude, can be calibrated by power spectral density during sinusoidal oscillations. With oscillation frequency increasing, coupling ratio decreases in both x- and y-directions, which is also confirmed by the calibration with light scattering of scanning two aligned beads on slide. Those oscillation responses are related with deformability of chamber and the intrinsic characteristics of PZT. If we take nominal amplitude as actual amplitude for sinusoidal oscillations at 50 Hz, the amplitude is overestimated ~2 times in x-direction and ~3 times in y-direction. That will lead to huge errors for subsequent calibrations.

Two-dimensional infrared correlation spectroscopy study of sequential events in the heat-induced unfolding and aggregation process of myoglobin.

Unfolding and aggregation are basic problems in protein science with serious biotechnological and medical implications. Probing the sequential events occurring during the unfolding and aggregation process and the relationship between unfolding and aggregation is of particular interest. In this study, two-dimensional infrared (2D IR) correlation spectroscopy was used to study the sequential events and starting temperature dependence of Myoglobin (Mb) thermal transitions. Though a two-state model could be obtained from traditional 1D IR spectra, subtle noncooperative conformational changes were observed at low temperatures. Formation of aggregation was observed at a temperature (50-58 degrees C) that protein was dominated by native structures and accompanied with unfolding of native helical structures when a traditional thermal denaturation condition was used. The time course NMR study of Mb incubated at 55 degrees C for 45 h confirmed that an irreversible aggregation process existed. Aggregation was also observed before fully unfolding of the Mb native structure when a relative high starting temperature was used. These findings demonstrated that 2D IR correlation spectroscopy is a powerful tool to study protein aggregation and the protein aggregation process observed depends on the different environmental conditions used.