XLIM

A compact, frequency-tunable, and efficient relativistic magnetron (RM) featuring a reducing coaxial section (RCS) and tilted tuners was developed and experimentally tested. The study validates numerical predictions through experiments, focusing on sustained oscillations, power efficiency, and frequency tuning. Four cathode configurations were tested. The solid cathode with reduced diameter yielding the best results: up to 34% efficiency, 450-MW average output power, and 1.55-GW peak power at 430 kV. A tuning bandwidth of 16% was achieved between 1.8 and 2.12 GHz. Plasma effects were investigated via improved particle-in-cell (PIC) simulations using a dispersive Drude model, identifying plasma as the main source of observed RF instabilities and pulse shortening.

We have demonstrated the excellent SERS sensitivity of suspended core photonic crystal fibre (SuC-PCF) for the label-free detection of Poly A nucleotide, highlighting its potential for highly sensitive, SERS-based nucleic acid sensing applications.

We report on what we believe is the first demonstration of on-chip supercontinuum generation through dual-wavelength pumping of a nonlinear photonic integrated circuit, fabricated from high-index doped silica glass. In addition to the bandwidth enhancement through cross-phase modulation, we also observe multiple temporal reflections that help to extend the bandwidth further through far-detuned radiations. The experimental results show good agreement with the phase-matching theory and numerical simulations. Additionally, our real-time, pulse-to-pulse, spectral measurements through the dispersive Fourier transform technique reveal a significant increase in relative intensity noise for dual-wavelength pumping compared to the case of single-wavelength pumping.

<title>Abstract</title> Background Falls can occur unpredictably or follow patterns linked to modifiable risk factors and adverse outcomes. Identifying fall trajectories and their key predictors can help clinicians implement targeted prevention strategies. We hypothesize that distinct clinical fall trajectories exist, each with identifiable baseline predictors. Methods This seven-year prospective study followed 1,648 community-dwelling older adults (≥ 60 years). Participants were assessed at home. Data collection included cardiovascular risk factors, fall occurrences, socio-environmental characteristics and a comprehensive geriatric assessment summary score. Fall trajectories were identified using a Gaussian Mixture Model (GMM) and Multinomial Logistic Regression (MLR) determined the predictors of each trajectory. Marginal prediction allowed us to refine predictor analysis by identifying the category within each feature that contributes the most to the steadiest trajectory. Results Four distinct fall trajectories were identified during the 7 years follow up: Cluster Falls and No Falls (65.5%), Increasing Falls (6.7%), Chronic Recurring Falls (15.7%) and Low-Rate Chronic Falls (12.1%). At baseline the steadiest trajectory is Increasing Falls. Clustered Falls and No Falls trajectory is characterized by lack of leisure activities, functional impairment (Instrumental Activities of Daily Living [IADL] &lt; 8) and pathological performance on the Single Leg Balance (SLB) test. The Chronic Recurring Falls trajectory was primarily composed of women with obesity. The Low-Rate Chronic Falls group also consisted mainly of obese women with IADL &lt; 8 and pathological SLB. We also investigated predictors at the 18-month follow-up. Conclusions Falls in older individuals may occur at discrete intervals or follow recurrent patterns, including chronic recurrence, all of which are associated with increased risks. Women, obesity, impairment in activities of daily living, reduced physical performance and depressive symptoms should be prioritized for intervention.

This paper presents a 5W MMIC Doherty Power Amplifier (DPA) operating in the Ka-band (28-32 GHz). The simulated and measured S-parameters and power performance are compared to those of a 5 W MMIC Class AB conventional reactively-matched power amplifier having similar chip area. Both amplifiers exhibit a peak linear gain of 20.8 dB. At saturation, the Class AB amplifier demonstrates a peak Power-Added Efficiency (PAE) ranging from 31% to 36% with an output power of 37 dBm, while the DPA achieves a peak PAE of 29% to 33% with a similar output power. As expected at 6 dB output back-off (OBO), the DPA shows a significantly higher PAE of 24% to 31%, compared to the Class AB amplifier's 16% to 22%. The amplifiers demonstrate performances in line with the latest state-of-the-art published results.

This study investigates a pre-matched HEMT GaN device with an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$8 \times 50 \mu m$</tex> gate width, operating at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$29 \mathbf{G H z}$</tex> and manufactured using UMS Foundry's GH15 process technology. Performance characterization was conducted using Unequally Spaced Multi-Tone (USMT) signals to analyze behavior under various modulated signal conditions. This method enables the evaluation of large-signal performance in realistic operating scenarios. Experimental results were compared with Harmonic Balance simulations to ensure result consistency, where passive components were modeled using EM tools, while active components were designed with the GH15 design kit. The analysis showed that increasing the number of frequencies led to a greater current drop, due to the device's trapping effects, and a reduction in maximum Power Added Efficiency (PAE). Lastly, the Adjacent Channel Power Ratio (ACPR) results exhibited good agreement between simulations and measurements, confirming the reliability of the test bench.