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Item type:Publication, Suppressing ripple distortions and spurious pistons in phase-shifting interferometry(OSA - The Optical Societycustserv@osa.org, 2020-04-01)In this paper, we present new phase-shifting algorithms (PSAs) that suppress the ripple distortions and spurious pistons in phase-shifting interferometry. These phase errors arise when non-uniform phase-shifting interferograms are processed with PSAs that assume uniform phase shifts. By modeling the non-uniform phase shifts as a polynomial of the unperturbed phase-shift value ω 0 , we show that the conditions for eliminating the ripple distortion and the spurious piston are associated with the m th derivative of the PSA’s frequency transfer function (FTF). Thus, we propose an approach to design robust algorithms based on the FTF formalism and we present four ready-to-apply PSAs formulas. Finally, our conclusions are supported by computer simulations. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Toward “Receive-Only” Nuclear Magnetic Resonance Complementary Metal-Oxide-Semiconductor Microcoil Arrays for High-Throughput Analysis of Environmental Samples(American Chemical Society, 2025-06-10)Daphnia magna neonates and eggs are critical life stages that show different susceptibilities to toxins and stressors compared to adults. Nuclear magnetic resonance (NMR) spectroscopy has unique potential to uncover the underlying biochemical causes, but such very small, mass-limited samples are challenging to study. While the enhanced mass sensitivity of microcoils leads to markedly improved NMR analysis, experiments are often still long, leading to low throughput. Microcoil arrays can improve throughput by allowing concurrent analysis of multiple samples, but practical and economical challenges, including expensive receivers and lack of physical space, are prohibitive. Here, approaches to overcome these challenges were examined. First, “receive-only” planar complementary metal-oxide-semiconductor (CMOS) microcoils were explored wherein the microcoil was used for detection, but an external volume coil was used for excitation. This resulted in considerably improved nutation and provided a 70% boost to the signal-to-noise ratio (SNR) compared to excitation on the planar CMOS coil. Steady-state free precession experiments further improved the SNR by a factor of at least 2.5, reducing acquisition time and improving throughput. To complete a three-coil “receive-only” array, an inexpensive ($315) software-defined radio board was adapted to act as an NMR receiver with similar performance to commercial receivers. The three-coil array was used to study three D. magna eggs concurrently, potentially opening the door for high-throughput analysis and toxicological studies, where the control and exposed cohorts can be studied concurrently, reducing day-to-day variability. Overall, microcoil arrays show considerable promise for the study of D. magna eggs and other mass-limited samples.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Andean agriculture and hand tools: A qualitative approach of exploration of needs, barriers, and opportunities for innovation(Public Library of Science, 2026-05-01)Peruvian Andean agriculture primarily consists of subsistence activities that rely on traditional methods. Rural farmers use locally made hand tools, often designed without technical or ergonomic considerations, increasing the risk of musculoskeletal disorders. This study examined farmers' views, needs, barriers, and support in hand tool design, and how they assess satisfaction with tools during potato harvesting. A qualitative study using a phenomenological design was conducted using semi-structured interviews with 13 rural farmers from Yanaca, Apurímac, Peru. A total of 25 interviews were conducted, audio-recorded, transcribed verbatim, and analyzed via a mixed coding strategy. Data was organized using a thematic approach and triangulated to validate coding. The results from the first guide were organized into five themes: task, human, product, qualitative and environmental. Some aspects such as social and techniques aspects for adopting hand tools emerged as well as enablers like economic accessibility, similarity to traditional tools. Six themes emerged from second guide covering tools conditions for efficient use, pre-work preparation, evaluation of the tool, consequences of a deficient tool, accumulated experience and appropriation; and family and gender dynamics. We found that hand tools used in high-Andean agriculture are shaped by technical features such as weight and handle size, and external aspects like climate effect and cultural familiarity, while material limitations, rough handle surface or inadequate tool size can act as barriers. In addition, efficiency of tools during work, preparation like a sharpened tip, fit between components head and handle, local maintenance facilitates farmers' satisfaction. These findings suggest that agricultural hand tool design should go beyond technical aspects to incorporate cultural and practical perspectives.1