Naviculocuneiform Arthrodesis in Adult Flatfoot: A Case Series.

Medial column arthrodesis and calcaneal osteotomies are commonly used for adult-acquired flatfoot surgical reconstruction. In this case series, 10 patients (11 feet) with a mean age of 54 ± 13 years underwent a medial column arthrodesis, with or without calcaneal osteotomy, between 2010 and 2017. The indication for surgery was a painful flatfoot deformity with peritalar subluxation and a fault in the naviculocuneiform joint. At a mean of 9.9 (range 2.5 to 33.1) months after surgery, in patients who underwent a medial column arthrodesis, radiographs showed a mean decrease in the talonavicular coverage angle of 8.4° ± 8.5° (p = .013), and mean increases in the lateral talometatarsal and calcaneal inclination angle of 10.6° ± 10.3° (p = .002) and 2.2° ± 4.4° (p = .067), respectively. One nonunion (1 of 11 [9.1%]) occurred at the naviculocuneiform. These findings demonstrate marked improvement of radiographic flatfoot parameters after medial column arthrodesis.

2D IR spectroscopy at 100 kHz utilizing a Mid-IR OPCPA laser source.

We present a 100 kHz 2D IR spectrometer. The system utilizes a ytterbium all normal dispersion fiber oscillator as a common source for the pump and seed beams of a MgO:PPLN OPCPA. The 1030 nm OPCPA pump is generated by amplification of the oscillator in cryocooled Yb:YAG amplifiers, while the 1.68 µm seed is generated in a OPO pumped by the oscillator. The OPCPA outputs are used in a ZGP DFG stage to generate 4.65 µm pulses. A mid-IR pulse shaper delivers pulse pairs to a 2D IR spectrometer allowing for data collection at 100 kHz.

Effect of patient positioning on toe pressure measurement using noninvasive vascular testing.

OBJECTIVE: Interpretation of digital pressure in the assessment of healing potential for diabetic foot disease has become common because of the potential for false elevation with the ankle-brachial index. However, the specific testing protocol for segmental Doppler examinations and photoplethysmography require patients to be in the supine position, with the lower limbs at heart level, in order to minimise the effect of hydrostatic pressure. This may be difficult in many patients with lower extremity pathology, particularly those who are nonambulatory, with painful wounds, or with orthopnea. In these situations, the noninvasive vascular test may be performed with the patient in a more comfortable position, which may include sitting in a wheelchair with the leg in a dependent position. The objective of this investigation was to evaluate the effect of patient positioning on measurement of the digital pressure. METHOD: Hallux pressures were measured in 20 healthy volunteers in 3 variable positions of limb dependency. RESULTS: The mean±standard deviation of digital pressure for subjects while lying supine with the limb at heart level was 103.5±26.0 mmHg (the recommended position for performance of the test), while sitting upright with the limb level on the table was 130.6±27.9 mmHg (+26.2%, p<0.0001) and sitting upright with the limb in a dependent position was 169.8±30.8 mmHg (+64.1%, p<0.0001). CONCLUSION: On the basis of these results, we conclude that patient positioning has a significant effect on measurement of digital pressure.

Phase matching of high harmonic generation in the soft and hard X-ray regions of the spectrum.

We show how bright, tabletop, fully coherent hard X-ray beams can be generated through nonlinear upconversion of femtosecond laser light. By driving the high-order harmonic generation process using longer-wavelength midinfrared light, we show that, in theory, fully phase-matched frequency upconversion can extend into the hard X-ray region of the spectrum. We verify our scaling predictions experimentally by demonstrating phase matching in the soft X-ray region of the spectrum around 330 eV, using ultrafast driving laser pulses at 1.3-microm wavelength, in an extended, high-pressure, weakly ionized gas medium. We also show through calculations that scaling of the overall conversion efficiency is surprisingly favorable as the wavelength of the driving laser is increased, making tabletop, fully coherent, multi-keV X-ray sources feasible. The rapidly decreasing microscopic single-atom yield, predicted for harmonics driven by longer-wavelength lasers, is compensated macroscopically by an increased optimal pressure for phase matching and a rapidly decreasing reabsorption of the generated X-rays.

Nondestructive, high-resolution, chemically specific 3D nanostructure characterization using phase-sensitive EUV imaging reflectometry.

Next-generation nano- and quantum devices have increasingly complex 3D structure. As the dimensions of these devices shrink to the nanoscale, their performance is often governed by interface quality or precise chemical or dopant composition. Here, we present the first phase-sensitive extreme ultraviolet imaging reflectometer. It combines the excellent phase stability of coherent high-harmonic sources, the unique chemical sensitivity of extreme ultraviolet reflectometry, and state-of-the-art ptychography imaging algorithms. This tabletop microscope can nondestructively probe surface topography, layer thicknesses, and interface quality, as well as dopant concentrations and profiles. High-fidelity imaging was achieved by implementing variable-angle ptychographic imaging, by using total variation regularization to mitigate noise and artifacts in the reconstructed image, and by using a high-brightness, high-harmonic source with excellent intensity and wavefront stability. We validate our measurements through multiscale, multimodal imaging to show that this technique has unique advantages compared with other techniques based on electron and scanning probe microscopies.

Direct light-induced spin transfer between different elements in a spintronic Heusler material via femtosecond laser excitation.

Heusler compounds are exciting materials for future spintronics applications because they display a wide range of tunable electronic and magnetic interactions. Here, we use a femtosecond laser to directly transfer spin polarization from one element to another in a half-metallic Heusler material, Co2MnGe. This spin transfer initiates as soon as light is incident on the material, demonstrating spatial transfer of angular momentum between neighboring atomic sites on time scales < 10 fs. Using ultrafast high harmonic pulses to simultaneously and independently probe the magnetic state of two elements during laser excitation, we find that the magnetization of Co is enhanced, while that of Mn rapidly quenches. Density functional theory calculations show that the optical excitation directly transfers spin from one magnetic sublattice to another through preferred spin-polarized excitation pathways. This direct manipulation of spins via light provides a path toward spintronic devices that can operate on few-femtosecond or faster time scales.