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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.

Abstract 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article informs direct light–induced spin transfer between different elements in a spintronic Heusler material via femtosecond laser excitation. Topic include Ultrafast Extreme Ultraviolet (EUV) high harmonic pulses make it possible to uncover the element-specific spin dynamics in multi-component magnetic systems, providing rich new information not accessible using visible light.

The microscopic state of a magnetic material is characterized by its resonant magneto-optical response through the off-diagonal dielectric tensor component εxy . However, the measurement of the full complex εxy in the extreme ultraviolet spectral region covering the M absorption edges of 3 d ferromagnets is challenging due to the need for either a careful polarization analysis, which is complicated by a lack of efficient polarization analyzers, or scanning the angle of incidence in fine steps. Here, we propose and demonstrate a technique to extract the complex resonant permittivity εxy simply by scanning the polarization angle of linearly polarized high harmonics to measure the magneto-optical asymmetry in reflection geometry. Because this technique is more practical and faster to experimentally implement than previous approaches, we can directly measure the full time evolution of εxy(t) during laser-induced demagnetization across the entire M2,3 absorption edge of cobalt with femtosecond time resolution. We find that for polycrystalline Co films on an insulating substrate, the changes in εxy are uniform throughout the spectrum, to within our experimental precision. This result suggests that, in the regime of strong demagnetization, the ultrafast demagnetization response is primarily dominated by magnon generation. We estimate the contribution of exchange-splitting reduction to the ultrafast demagnetization process to be no more than 25%. [ABSTRACT FROM AUTHOR]

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.