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The UDSpace Institutional Repository collects and disseminates research material from the University of Delaware.
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Recent Submissions
HIV Activist Identity, Commitment, and Orientation Scale (HAICOS): Psychometric Evaluation to Assess Clinician’s Propensity Towards HIV Activism in Malaysia
(AIDS and Behavior, 2024-05-28) Chong, Norman; Azwa, Iskandar; Hassan, Asfarina Amir; Mousavi, Mohammad Ebrahimzadeh; Wong, Pui Li Wong; Ng, Rong Xiang; Saifi, Rumana; Basri, Sazali; Omar, Sharifah Faridah Syed; Walters, Suzan M.; Collier, Zachary K.; Haddad, Marwan S.; Altice, Frederick L.; Kamarulzaman, Adeeba; Earnshaw, Valerie A.
HIV activism has a long history of advancing HIV treatment and is critical in dismantling HIV-related stigma. This study evaluated the psychometric quality of the HIV Activist Identity, Commitment, and Orientation Scale (HAICOS) to assess clinicians’ propensity towards HIV activism in Malaysia. From November 2022 to March 2023, 74 general practitioners and primary care physicians in Malaysia participated in the study. The exploratory factor analysis (EFA) extracted an internally consistent three-factor solution with 13 items: (1) HIV activist identity and commitment, orientation towards (2) day-to-day, and (3) structural activism. The Cronbach’s alpha value was 0.91, and intra-class correlation coefficient for test-retest reliability was 0.86. Stigma-related (prejudice and discrimination intent) and clinical practice (comfort in performing clinical tasks with key populations and knowledge about HIV pre-exposure prophylaxis) measures supported the construct validity of the scale. The study provided concise, structurally valid, and reliable measures to evaluate HIV activism among clinicians.
Resumen
El activismo del VIH tiene una larga historia de avanzar el tratamiento del VIH y es crítico para desmantelar el estigma relacionado al VIH. Este estudio evaluó la calidad psicométrica de la Escala de Identidad, Compromiso y Orientación de Activistas del VIH (HAICOS) para evaluar la propensión de los médicos hacia el activismo del VIH en Malasia. Desde noviembre del 2022 hasta marzo del 2023, 74 médicos generales y de atención primaria en Malasia participaron en este estudio. El análisis factorial exploratorio (AFE) extrajo una solución de tres factores internamente consistente con 13 ítems: (1) identidad y compromiso del activismo del VIH; orientación hacia (2) el activismo cotidiano y (3) el activismo estructural. El valor alfa de Cronbach fue de 0.91 y el coeficiente de correlación intraclase para la confiabilidad prueba-reprueba fue de 0.86. Las medidas relacionadas con el estigma (prejuicio e intención de discriminación) y la práctica clínica (comodidad realizando tareas clínicas con poblaciones claves y conocimiento sobre la profilaxis pre-exposición del VIH) respaldaron la validez de constructo de la escala. El estudio proporcionó medidas concisas, estructuralmente válidas y confiables para evaluar el activismo de VIH entre los médicos.
Super-resolution ISAR Imaging using Off-the-grid Structured Low-rank Method
(IEEE Transactions on Antennas and Propagation, 2024-11-12) Zhang, Bangjie; Xu, Gang; Xia, Xiang-Gen; Yu, Hanwen; Xing, Mengdao; Hong, Wei
Inverse synthetic aperture radar (ISAR) imaging relies on wideband waveform and viewing angle variation to achieve range and cross-range resolutions, respectively. To enhance the resolutions of two-dimensional (2-D) image, sparse signal processing techniques, such as compressed sensing (CS), have been applied to ISAR imaging using a sparse prior. Despite its efficiency in super-resolution imaging, the performance of CS is constrained due to the mismatch of discrete dictionary, such as Fourier transform. To address this issue, we propose a novel off-the-grid super-resolution ISAR imaging algorithm that employs a structured low-rank approach to effectively extrapolate the data bandwidth and aperture. To fully capture the low-rank property of ISAR data, the structured data model is constructed and its low-rank property is deduced to exhibit that the signal is embedded in a limited dimensional subspace. Then, the annihilating filter is derived by constructing structured data matrix to formulate the proposed structured low-rank method, termed as Off-the-grid Super-resolution using Annihilation Constraint (OSAC). Taking into account that the super-resolution imaging is highly reliant on the accuracy of annihilating filter, the optimal annihilating filter is also estimated with the updating of extrapolated ISAR data. Through iterative updates of the annihilating filter and solution of the minimization problem, the super-resolution ISAR imaging can be achieved by avoiding the discrete mismatch of conventional CS method. Due to the effective exploration of structured low-rank property, the proposed OSAC algorithm offers superior precision in scatterer location and structure interpretation of a target. Experimental results using both simulated and real data are presented to verify the enhanced performance of 2-D resolution in ISAR imaging.
Satellites Beam Hopping Scheduling for Interference Avoidance
(IEEE Journal on Selected Areas in Communications, 2024-10-10) Deng, Huimin; Ying, Kai; Feng, Daquan; Gui, Lin; He, Yuanzhi; Xia, Xiang-Gen
The deployment of low earth orbit (LEO) satellites megaconstellations presents a promising way for achieving global coverage and service, attributed to their comparatively low round-trip latency and launch costs. However, this surge in LEO satellite launches exacerbates the scarcity of the limited spectrum resources. Spectrum sharing between satellite constellations and terrestrial networks and beam hopping (BH) technology emerge as viable strategies to mitigate this spectrum shortage. To enhance spectrum efficiency and avoid serious inter-system interference, we investigate the beam hopping scheduling of satellites for interference avoidance. The beam hopping scheduling of the integrated satellite-terrestrial wireless networks system is formulated as throughput-driven beam hopping (TDBH) problem and satisfaction-rate-driven beam hopping (SDBH) problem, respectively. In particular, we decompose the TDBH problem into two sub-problems by relaxation, and a genetic algorithm (GA) is introduced to handle the SDBH problem. The impact of channel conditions and traffic load intensity on the satellite system throughput is analyzed in TDBH simulation. As for SDBH optimization problem, the simulation results show that the proposed GA algorithm improves the average traffic satisfaction rate by 16.96% at least, compared with other benchmarks and suits to scenarios with different traffic demands and fading channel conditions.
An Antiferroelectric-Coated Metal Foam Infiltrated with Liquid Metal as a Dielectric Capacitor
(Energy Technology, 2024-10-07) Hanrahan, Brendan; Leff, Asher; Sesar, Alexis; Fish, Michael; Jaszewski, Samantha T.; Kropp, Jaron A.; Strnad, Nicholas; Ihlefeld, Jon F.; Lazarus, Nathan
Nickel metal foams serve as both a substrate and bottom electrode for a dielectric capacitor using atomic-layer deposition (ALD) and a eutectic gallium–indium (EGaIn) liquid metal (LQM) counter electrode. The conformal dielectric has a composition of 6.25% Al–HfO2 in the antiferroelectric phase, confirmed with polarization versus electric field measurements. Liquid EGaIn is pressure-infiltrated within the coated foams to form the dielectric capacitor. Capacitances up to 4 μF are realized. Calorimetry of the infiltrated capacitor shows a 60 J g−1 latent heat upon melting a frozen EGaIn electrode, suggesting that the phase change can alleviate thermal deviations from pulsed power capacitor operation. Infiltrated capacitors are also shown to survive bending and freeze–thaw cycles. The metal foam–ALD dielectric–LQM capacitor shows a combined set of thermal and electrical properties not available in other classes of capacitors.
Composition Quantification of SiGeSn Alloys Through Time-of-Flight Secondary Ion Mass Spectrometry: Calibration Methodologies and Validation With Atom Probe Tomography
(IEEE Journal of Selected Topics in Quantum Electronics, 2024-09-09) Zhao, Haochen; Liu, Shang; Park, Suho; Feng, Xu; Zeng, Zhaoquan; Kolodzey, James
Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a powerful technique for elemental compositional analysis and depth profiling of materials. However, it encounters the problem of matrix effects that hinder its application. In this work, we introduce a pioneering ToF-SIMS calibration method tailored for SixGeySnz ternary alloys. SixGe1-x and Ge1-zSnz binary alloys with known compositions are used as calibration reference samples. Through a systematic SIMS quantification study of SiGe and GeSn binary alloys, we unveil a linear correlation between secondary ion intensity ratio and composition ratio for both SiGe and GeSn binary alloys, effectively mitigating the matrix effects. Extracted relative sensitivity factor (RSF) value from SixGe1-x (0.07 < x < 0.83) and Ge1-zSnz (0.066 < z < 0.183) binary alloys are subsequently applied to those of SixGeySnz (0.011 < x < 0.113, 0.863 < y < 0.935 and 0.023 < z < 0.103) ternary alloys for elemental compositions quantification. These values are cross-checked by Atom Probe Tomography (APT) analysis, an indication of the great accuracy and reliability of as-developed ToF-SIMS calibration process. The proposed method and its reference sample selection strategy in this work provide a low-cost as well as simple-to-follow calibration route for SiGeSn composition analysis, thus driving the development of next-generation multifunctional SiGeSn-related semiconductor devices.