Journal articles: 'Pixelated LED'

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Kim, Tae Kyoung, Abu Bashar Mohammad Hamidul Islam, Yu-Jung Cha, and Joon Seop Kwak. "32 × 32 Pixelated High-Power Flip-Chip Blue Micro-LED-on-HFET Arrays for Submarine Optical Communication." Nanomaterials 11, no. 11 (November 12, 2021): 3045. http://dx.doi.org/10.3390/nano11113045.

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This work proposes the use of integrated high-power InGaN/GaN multiple-quantum-well flip-chip blue micro light-emitting diode (μ-LED) arrays on an AlGaN/GaN-based heterojunction field-effect transistor (HFET), also known as a high electron mobility transistor (HEMT), for various applications: underwater wireless optical communication (UWOC) and smart lighting. Therefore, we demonstrate high-power μ-LED-on-HEMT arrays that consist of 32 × 32 pixelated μ-LED arrays and 32 × 32 pixelated HEMT arrays and that are interconnected by a solder bump bonding technique. Each pixel of the μ-LED arrays emits light in the HEMT on-state. The threshold voltage, the off-state leakage current, and the drain current of the HEMT arrays are −4.6 V, <~1.1 × 10−9 A at gate-to-source voltage (VGS) = −10 V, and 21 mA at VGS = 4 V, respectively. At 12 mA, the forward voltage and the light output power (LOP) of μ-LED arrays are ~4.05 V and ~3.5 mW, respectively. The LOP of the integrated μ-LED-on-HEMT arrays increases from 0 to ~4 mW as the VGS increases from −6 to 4 V at VDD = 10 V. Each pixel of the integrated μ-LEDs exhibits a modulated high LOP at a peak wavelength of ~450 nm, showing their potential as candidates for use in UWOC.

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Lee, Sang-Youl, Kiman Kang, Eunduk Lee, Yoomin Jo, Doyub Kim, Jeong-Tak Oh, Hwan-Hee Jeong, Tae-Yeon Seong, and Hiroshi Amano. "Improved Leakage and Output Characteristics of Pixelated LED Array for Headlight application." ECS Journal of Solid State Science and Technology 9, no. 4 (April 29, 2020): 045011. http://dx.doi.org/10.1149/2162-8777/ab8b6f.

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Lu, Tao, Wei Feng, Yibo Liu, Ruoning Wang, Zhiyi Yu, and Zhaojun Liu. "P-9.3: Triple Modulation Visible Light Communications with Pixelated Addressable LED Array." SID Symposium Digest of Technical Papers 49 (April 2018): 665–69. http://dx.doi.org/10.1002/sdtp.12809.

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Zufri, Tubagus, and Nurul Aqmarina Ardani. "Reseach on the Application of Pixel Art in Game Character Design." IJVCDC (Indonesian Journal of Visual Culture, Design, and Cinema) 2, no. 1 (April 30, 2023): 100–106. http://dx.doi.org/10.21512/ijvcdc.v2i1.8238.

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This paper analyses the trend, design fundamentals, and design principles of contemporary character design from digital game. It discusses that even though the design styles of today’s digital art era are flourishing with diverse thinking and visual approach, the classic pixel art style will never go out of style. The fundamental element of artistic design in pixel art style is a single element, a pixel. Many designers prefer using the single pixel style as the fundamental element of their artistic design, which has led to the creation of various intriguing design categories. Despite the prevalent use of full high-definition 3D rendering images in contemporary digital game design, the pixelated style remains a timeless tribute to the classics with an enduring impact, given its promising development prospects. Pixelated design is now being applied to practice by more designers and artists, and it has gradually become a unique form of artistic visual expression.

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Heo, Duchang, Kang-Woo Kim, Keedong Yang, Seongchae Jeon, and Beom Jin Moon. "Pixelated Photoinduced Discharge Readout X-Ray Detector Using 450-nm LED Line Beam." IEEE Sensors Journal 21, no. 17 (September 1, 2021): 18656–62. http://dx.doi.org/10.1109/jsen.2021.3086502.

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Zhu, L., P. T. Lai, and H. W. Choi. "Microlens Array on Flip-Chip LED Patterned With an Ultraviolet Micro-Pixelated Emitter." IEEE Photonics Technology Letters 23, no. 15 (August 2011): 1067–69. http://dx.doi.org/10.1109/lpt.2011.2154323.

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Zhao, Xin-Yu, Li-Jing Li, Lei Cao, and Ming-Jie Sun. "Bionic Birdlike Imaging Using a Multi-Hyperuniform LED Array." Sensors 21, no. 12 (June 14, 2021): 4084. http://dx.doi.org/10.3390/s21124084.

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Digital cameras obtain color information of the scene using a chromatic filter, usually a Bayer filter, overlaid on a pixelated detector. However, the periodic arrangement of both the filter array and the detector array introduces frequency aliasing in sampling and color misregistration during demosaicking process which causes degradation of image quality. Inspired by the biological structure of the avian retinas, we developed a chromatic LED array which has a geometric arrangement of multi-hyperuniformity, which exhibits an irregularity on small-length scales but a quasi-uniformity on large scales, to suppress frequency aliasing and color misregistration in full color image retrieval. Experiments were performed with a single-pixel imaging system using the multi-hyperuniform chromatic LED array to provide structured illumination, and 208 fps frame rate was achieved at 32 × 32 pixel resolution. By comparing the experimental results with the images captured with a conventional digital camera, it has been demonstrated that the proposed imaging system forms images with less chromatic moiré patterns and color misregistration artifacts. The concept proposed verified here could provide insights for the design and the manufacturing of future bionic imaging sensors.

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Xiong, Zhaobin, CHO Wai Keung, Lihuan Qin, Zhiyi Yu, and Zhaojun Liu. "P-9.9: Design and Fabrication of Fine-Pitch-flexible-transparent Pixelated-Addressed Micro-LED Arrays." SID Symposium Digest of Technical Papers 49 (April 2018): 685–87. http://dx.doi.org/10.1002/sdtp.12815.

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Koch-Mehrin, Kjell A. L., Sarah L. Bugby, John E. Lees, Matthew C. Veale, and Matthew D. Wilson. "Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors." Sensors 21, no. 9 (May 8, 2021): 3260. http://dx.doi.org/10.3390/s21093260.

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Cadmium zinc telluride (CdZnTe) detectors are known to suffer from polarization effects under high photon flux due to poor hole transport in the crystal material. This has led to the development of a high-flux capable CdZnTe material (HF-CdZnTe). Detectors with the HF-CdZnTe material have shown promising results at mitigating the onset of the polarization phenomenon, likely linked to improved crystal quality and hole carrier transport. Better hole transport will have an impact on charge collection, particularly in pixelated detector designs and thick sensors (>1 mm). In this paper, the presence of charge sharing and the magnitude of charge loss were calculated for a 2 mm thick pixelated HF-CdZnTe detector with 250 μm pixel pitch and 25 μm pixel gaps, bonded to the STFC HEXITEC ASIC. Results are compared with a CdTe detector as a reference point and supported with simulations from a Monte-Carlo detector model. Charge sharing events showed minimal charge loss in the HF-CdZnTe, resulting in a spectral resolution of 1.63 ± 0.08 keV Full Width at Half Maximum (FWHM) for bipixel charge sharing events at 59.5 keV. Depth of interaction effects were shown to influence charge loss in shared events. The performance is discussed in relation to the improved hole transport of HF-CdZnTe and comparison with simulated results provided evidence of a uniform electric field.

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Ahn, Hyun-A., Seong-Kwan Hong, and Oh-Kyong Kwon. "An Active Matrix Micro-Pixelated LED Display Driver for High Luminance Uniformity Using Resistance Mismatch Compensation Method." IEEE Transactions on Circuits and Systems II: Express Briefs 65, no. 6 (June 2018): 724–28. http://dx.doi.org/10.1109/tcsii.2018.2790412.

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Sen, Rwik, Ngoc Tran, Sarah Traynor, Eric Maina, and Jason Poole. "Abstract 4731: Novel epigenetics technology for high-throughput processing of limited samples to study cancer using cavitation-based pixelated ultrasound and tagmentation-indexing ChIP-Seq." Cancer Research 83, no. 7_Supplement (April 4, 2023): 4731. http://dx.doi.org/10.1158/1538-7445.am2023-4731.

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Abstract Epigenetics has shown great potential in translational, clinical, and precision medicine research, but with inadequate implementation. This is due to major problems with sample availability, and processing which is laborious, costly, slow, inconsistent, and leads to sample loss. Epigenetics studies need samples with certain minimum concentrations and volumes to address all necessary questions. The samples often need to be in single cell or nuclear suspensions. For chromatin immunoprecipitation (ChIP), a consistent size of approximately 300 base pairs of DNA is essential but difficult to achieve. To address the above problems, we present novel cutting-edge epigenetics methodologies. Homogenization of various tissue types from diverse patients with different disease states is the first crucial step in sample processing. Hence, we present new protocols which are compatible with high-throughput cavitation-based pixelated ultrasound sonication. It processes limited quantities of samples in a 96-well plate where cells can be grown and antibody can be coated for ChIP. Further, 1 to 12 columns of the 96-well plate can be flexibly regulated to extract lysates. Our results show how this rapid and simple technology integrates with ChIP-sequencing (seq) and RNA-seq workflows, yielding very consistent output from limited tissue samples. Bioinformatics analysis of the ChIP-seq shows the corresponding biological significance. Certain limitations of ChIP has led to the evolution of other methods but they are mostly unsuccessful in mapping transcription factors. Hence, we next present a modified ChIP-seq combined with tagmentation, indexing and pooling, coupled to pixelated ultrasound based-cavitation. Here, individual samples are placed in each well of a 96-well plate containing unique indexing adapters fused to Tn5 transposase. Hence, each sample undergoes tagmentation - a process where DNA gets fragmented and simultaneously inserted with index adapters. Next, pixelated ultrasound helps to rapidly extract the complex of protein-tagmented DNA from 96 samples which are pooled into a single tube because they are uniquely indexed, then split up for immunoprecipitation by different antibodies. Bioinformatics analysis shows that the results are robust, consistent, and match ENCODE datasets. Hence, our methods can help to process high-throughput samples for AACR Project GENIE. Overall, we present novel technology to process limited human samples for enabling epigenetics research at the clinical interface from bench to bedside. The simple and less expensive methods yield high quality samples to enable high-throughput analysis of epigenetics including transcription factors which are important in cancer. They help us to understand targeted epigenetic regulations of genes for therapeutic developments and treating cancer. Citation Format: Rwik Sen, Ngoc Tran, Sarah Traynor, Eric Maina, Jason Poole. Novel epigenetics technology for high-throughput processing of limited samples to study cancer using cavitation-based pixelated ultrasound and tagmentation-indexing ChIP-Seq. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4731.

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Hong, In Yeol, Jae Hyeok Lee, Sung Min Cho, Jae Bong So, Tae Kyoung Kim, Yu-Jung Cha, and Joon Seop Kwak. "Impact of Hydrothermally Grown ZnO Nanorods on External Quantum Efficiency of 32 × 32 Pixelated InGaN/GaN Micro-LED Array." IEEE Transactions on Nanotechnology 18 (2019): 160–66. http://dx.doi.org/10.1109/tnano.2018.2876467.

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Peng, Deng, Ke Zhang, and Zhaojun Liu. "Design and Fabrication of Fine-Pitch Pixelated-Addressed Micro-LED Arrays on Printed Circuit Board for Display and Communication Applications." IEEE Journal of the Electron Devices Society 5, no. 1 (January 2017): 90–94. http://dx.doi.org/10.1109/jeds.2016.2631220.

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Kilpi, Linnea. "Knittedness: On the expressivity of knitting as metaphoric process." Craft Research 14, no. 2 (September 1, 2023): 237–53. http://dx.doi.org/10.1386/crre_00108_1.

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Knitted fabric is a part of everyday life for many, whether it be worn, made or metaphorically referenced. It can also be, when critically considered, an expressive practice with philosophical merit. The ostensibly simple looping of yarns into a continuous surface suggests conceptual depth through poetic comparisons to processes of living and storytelling, among others. The practice-led research project ‘Stranded colourwork: Meaning-making through experimental knitting practices’ worked to define the intrinsic qualities of knitting that make it meaningful, and to uncover its expressive potential as an experimental artistic practice. Through the creation of a series of figurative machine-knit artworks, the confluence of knitting and narrative created an opportunity to study the implications of stitched life. This article elucidates the theoretical framework behind the project and focuses on knittedness, a concept proposed through the research. Knittedness refers to the specific aesthetic and technical qualities inherent to the process, and how these qualities can become symbolically significant both in art making and in finding meaning and connection in life. The idea of pixelness is also proposed as an integral part of knitting and other pixelated processes, where the process and aesthetic quality is informed by a repetitive technical structure. These concepts can be expanded to advocate for a notion of craftedness, suggesting the value of determining the idiosyncratic expressivity of individual creative practices, and how a maker might use this knowledge to create technique-focused work and find new appreciation for the process.

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Deumel, Sarah, Albert van Breemen, Gerwin Gelinck, Bart Peeters, Joris Maas, Roy Verbeek, Santhosh Shanmugam, et al. "High-sensitivity high-resolution X-ray imaging with soft-sintered metal halide perovskites." Nature Electronics 4, no. 9 (September 2021): 681–88. http://dx.doi.org/10.1038/s41928-021-00644-3.

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AbstractTo realize the potential of artificial intelligence in medical imaging, improvements in imaging capabilities are required, as well as advances in computing power and algorithms. Hybrid inorganic–organic metal halide perovskites, such as methylammonium lead triiodide (MAPbI3), offer strong X-ray absorption, high carrier mobilities (µ) and long carrier lifetimes (τ), and they are promising materials for use in X-ray imaging. However, their incorporation into pixelated sensing arrays remains challenging. Here we show that X-ray flat-panel detector arrays based on microcrystalline MAPbI3 can be created using a two-step manufacturing process. Our approach is based on the mechanical soft sintering of a freestanding absorber layer and the subsequent integration of this layer on a pixelated backplane. Freestanding microcrystalline MAPbI3 wafers exhibit a sensitivity of 9,300 µC Gyair–1 cm–2 with a μτ product of 4 × 10–4 cm2 V–1, and the resulting X-ray imaging detector, which has 508 pixels per inch, combines a high spatial resolution of 6 line pairs per millimetre with a low detection limit of 0.22 nGyair per frame.

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Li, Yang, Jin Tao, Yongzhou Zhao, Jiaxian Wang, Jinguang Lv, Yuxin Qin, Jingqiu Liang, and Weibiao Wang. "48 × 48 pixelated addressable full-color micro display based on flip-chip micro LEDs." Applied Optics 58, no. 31 (October 22, 2019): 8383. http://dx.doi.org/10.1364/ao.58.008383.

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Xu, Feng, Yuxue Zhou, Xiangdong Meng, Liming Zhou, Zili Xie, Guohao Yu, and Baoshun Zhang. "Monolithic high-performance micro-LEDs using planar-geometry pixelation process for high-resolution micro-display applications." Applied Physics Letters 121, no. 24 (December 12, 2022): 241103. http://dx.doi.org/10.1063/5.0131616.

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Herein, a monolithic micro-pixelated light-emitting diode ( μLED) display realized using ion-surface-treatment-based planar-geometry pixelation is reported. A high-resolution blue-emitting μLED array is fabricated by optimizing ion species of a near-surface selectively positioned isolation process. The μLED array exhibiting inhibited surface recombination and higher output power is achieved by using heavy ions, such as fluorine (F−), due to more stable opto-electrical isolation and better process reliability. Furthermore, the low forward voltage of F−-IST-based μLED pixels can effectively improve the wall-plug efficiency for the μLED array with a pixel diameter of 6 μm. Conversely, the poor thermal stability of light hydrogen (H+) ions limits its device applications. Analysis based on a rate equation model reveals that the luminescence mechanism of F−-IST-based μLEDs is dominated by radiative recombination, which will benefit the planar-geometry pixelation for realizing highly efficient full-color microdisplays.

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Dorrigiv, Dina, Pierre-Alexandre Goyette, Amélie St-Georges-Robillard, Anne-Marie Mes-Masson, and Thomas Gervais. "Pixelated Microfluidics for Drug Screening on Tumour Spheroids and Ex Vivo Microdissected Tumour Explants." Cancers 15, no. 4 (February 7, 2023): 1060. http://dx.doi.org/10.3390/cancers15041060.

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Anticancer drugs have the lowest success rate of approval in drug development programs. Thus, preclinical assays that closely predict the clinical responses to drugs are of utmost importance in both clinical oncology and pharmaceutical research. 3D tumour models preserve the tumoral architecture and are cost- and time-efficient. However, the short-term longevity, limited throughput, and limitations of live imaging of these models have so far driven researchers towards less realistic tumour models such as monolayer cell cultures. Here, we present an open-space microfluidic drug screening platform that enables the formation, culture, and multiplexed delivery of several reagents to various 3D tumour models, namely cancer cell line spheroids and ex vivo primary tumour fragments. Our platform utilizes a microfluidic pixelated chemical display that creates isolated adjacent flow sub-units of reagents, which we refer to as fluidic ‘pixels’, over tumour models in a contact-free fashion. Up to nine different treatment conditions can be tested over 144 samples in a single experiment. We provide a proof-of-concept application by staining fixed and live tumour models with multiple cellular dyes. Furthermore, we demonstrate that the response of the tumour models to biological stimuli can be assessed using the platform. Upscaling the microfluidic platform to larger areas can lead to higher throughputs, and thus will have a significant impact on developing treatments for cancer.

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Luechinger, Norman A. "86‐3: Why perovskite quantum dots will be key for LCD‐, OLED‐ and microLED displays." SID Symposium Digest of Technical Papers 54, no. 1 (June 2023): 1214–15. http://dx.doi.org/10.1002/sdtp.16795.

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Green perovskite quantum dots are well known to be the best green color conversion material with respect to color purity (FWHM) and conversion efficiency (quantum yield). These two properties are essential for picture quality (color gamut and peak brightness) but also for minimizing the display power consumption which is getting more and more important for ecological reasons but also for regulatory reasons (especially in the EU). Furthermore there is also a development trend for displays equipped with a so‐called low‐ blue‐light function where the blue primary peak emission wavelength is increased in order to minimized the short‐wave blue light intensity which has a negative influence on the human circadian rhythm. However, such blue wavelength change intrinsically reduces the color gamut of the display and increases the power consumption at the same time. These two adverse effects can be mitigated and even improved by replacing the commonly used green B‐Sialon phosphor by green perovskite quantum dots.Over the last 7 years we have intensively worked on our green perovskite quantum dots and achieved a near‐unity quantum efficiency, an FWHM of 22nm and last but not least a sufficient stability against humidity, temperature and blue flux turning our perovsite QDs commercially viable now. In this presentation we give an overview about our technical perovskite solutions for miniLED backlight films (LCD displays) and also QD pixelated color converters for microLED displays and QD‐OLED displays.

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Kim, Tae Kyoung, Moon Uk Cho, Jae Min Lee, Yu-Jung Cha, Seung Kyu Oh, Bikramjit Chatterjee, Jae-Hyun Ryou, Sukwon Choi, and Joon Seop Kwak. "Improved Light Output Power of 16 × 16 Pixelated Micro-LEDs for Headlights by Enhancing the Reflectivity and Coverage of the p -Electrode." physica status solidi (a) 215, no. 10 (January 10, 2018): 1700571. http://dx.doi.org/10.1002/pssa.201700571.

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Mauss, B., T. Roger, J. Pancin, S. Damoy, and G. F. Grinyer. "MICROMEGAS calibration for ACTAR TPC." EPJ Web of Conferences 174 (2018): 01010. http://dx.doi.org/10.1051/epjconf/201817401010.

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Active targets, such as the ACtive TARget and Time Projection Chamber (ACTAR TPC) being developed at GANIL, are detection systems that operate on the basis of a time projection chamber but where the filling gas also serves as a thick target for nuclear reactions. In nuclear physics experiments, the energy resolution is of primary importance to identify the reaction products and to precisely reconstruct level schemes of nuclei. These measurements are based on the energy deposited on a pixelated pad plane. A MICROMEGAS detector is used in ACTAR TPC for the ionization electron collection and amplification, and it is a major contributor to the energy dispersion through, for example, inhomogeneities of the amplification gap. A variation of one percent in the gap can lead to an amplitude variation of more than two percent which is of the same order as the resolution obtained with an energy deposition of 5 MeV. One way to calibrate the pad plane is through the use of a two dimensional source scanning table. It is used to calibrate the gain inhomogeneities and, using MAGBOLTZ calculations, deduce the corresponding gap variations. The inverse of this method would allow the relative gain variations to be calculated for the different gas mixtures and pressures used in experiments with ACTAR TPC.

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Pettingill, Daniel, Daniel Kurtz, and Daniel Smalley. "Static Structures in Leaky Mode Waveguides." Applied Sciences 9, no. 2 (January 11, 2019): 247. http://dx.doi.org/10.3390/app9020247.

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In this work, we suggest a new method of expanding the field of view in bottom-exit, leaky mode devices for transparent, monolithic, holographic, near-eye display. In this approach, we propose the use of static, laser-induced, grating structures within the device substrate to break the leaky mode light into diffracted orders. We then propose to use carefully timed illumination pulses to select which diffracted order is visible to the eye at every display refresh interval (up to 100 kHz). Each of these orders becomes a view for a different image point. To describe this new method, we use K-vector analysis. We give the relevant equations and a list of parameters which lead to a near-eye geometry with little or no overlap in higher-order view zones. We conclude that it should be possible to increase the field of view of our bottom-exit, leaky mode devices by as much as one order of magnitude by simply adding a laser-induced grating structure to the substrate and by carefully timing the device illumination. If successful, this method would make possible a transparent, holographic, near-eye display that is simple to fabricate, relative to pixelated approaches, and which has a wide field-of-view relative to our current bottom-exit displays.

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Kim, Tae Kyoung, Moon Uk Cho, Jae Min Lee, Yu-Jung Cha, Seung Kyu Oh, Bikramjit Chatterjee, Jae-Hyun Ryou, Sukwon Choi, and Joon Seop Kwak. "Improved Light Output Power of 16 × 16 Pixelated Micro-LEDs for Headlights by Enhancing the Reflectivity and Coverage of the p -Electrode (Phys. Status Solidi A 10∕2018)." physica status solidi (a) 215, no. 10 (May 2018): 1870019. http://dx.doi.org/10.1002/pssa.201870019.

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Huang, Chi-Cheng, Nam Nhut Phan, and Ling-Ming Tseng. "Abstract P1-02-15: Predicting molecular subtypes of breast cancer using." Cancer Research 82, no. 4_Supplement (February 15, 2022): P1–02–15—P1–02–15. http://dx.doi.org/10.1158/1538-7445.sabcs21-p1-02-15.

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Abstract Purpose: Breast cancer is a heterogeneously complex disease. A number of molecular subtypes with distinct biological features lead to different treatment responses and clinical outcomes. Traditionally, breast cancer is classified into subtypes based on gene expression profiles; these subtypes, namely intrinsic subtypes, include luminal A, luminal B, basal-like and HER2-enriched breast cancer. This molecular taxonomy, however, could only be appraised through transcriptome analyses. We aim to classify breast cancer intrinsic subtypes using un-annotated approach using deep learning models.Methods: 388 pathological whole slide images (WSIs) from TCGA-BRCA dataset were downloaded from TCGA-GDC portal. These WSIs underwent patches generation and normalization using PyHIST tool and Macenko algorithm, respectively. Laplacian algorithm was applied to remove patches with blurry areas and pixelated. The remaining patches (n = 1,833,889) were divided into 3 parts for training (70%), testing (5%) and validation (25%). We applied a 2-step transfer learning with 2 pre-trained models, namely ResNet50, ResNet101, Xception and VGG16, which have been trained on another in-house breast cancer pathological image dataset. Results: these four models shown promising classification results of 4 breast cancer intrinsic subtypes with accuracy ranged from 0.68 (ResNet50 model) to 0.78 (ResNet101 model) in both testing and validation sets. The average AUC score for these models were from 0.88 (ResNet50 model) to 0.94 (ResNet101 model), whereas ResNet101_imgnet with “imagenet” weight archived an accuracy of 0.73 and AUC of 0.92. The overall accuracy of patient-wise prediction even shown a higher average accuracy of 0.914. These models’ prediction visualization was also used to demonstrate that the process of model learning was based on pathological cells’ clusters. Conclusion: Our study demonstrated the feasibility and capability of the deep learning model in classifying breast cancer intrinsic subtypes without region of interest annotation, which wound facilitate the clinical applicability of proposed models. Citation Format: Chi-Cheng Huang, Nam Nhut Phan, Ling-Ming Tseng. Predicting molecular subtypes of breast cancer using [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P1-02-15.

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Caplins, Benjamin. "(Invited) The Importance of Characterizing and Calibrating Light Engines in Vat Photopolymerization Additive Manufacturing." ECS Meeting Abstracts MA2023-01, no. 22 (August 28, 2023): 1588. http://dx.doi.org/10.1149/ma2023-01221588mtgabs.

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Vat photopolymerization (VP) is an additive manufacturing technique that uses spatially patterned light to cure liquid resins into solid materials. As an additive manufacturing technique, parts with complex geometries can be manufactured that would not be possible with conventional techniques. Large scale VP has found wide adoption by a range of industries including automotive, dental, consumer goods, and prototyping. On a smaller scale, hobbyist level users have found innumerable uses for VP and this market, in particular, has fueled the development of a plethora of low-cost printers. Common to all VP printers is the need for a light engine which illuminates the resin and initiates the photopolymerization process. Historically, this light engine was a UV laser with relatively simple optical properties including low divergence, narrow spectral bandwidth, and fixed wavelength – spatial extent of the photopolymerization was controlled by rastering the focused beam across the build plate. More recently, digital micromirror device (DMD) and liquid crystal display (LCD) based light engines have been developed which expose the resin in a parallel fashion by controlling the exposure in a 2-dimensional pixelated manner. These more recent light engine designs tend to rely upon light emitting diodes (LEDs) as the photon source and these have more complex properties including high divergence (i.e. Lambertian emitter), broad spectral bandwidth, and less well-defined wavelength. Many printer manufacturers have developed multi-emitter light engine designs that compound these characteristics. As VP manufacturing continues to mature, the reproducibility of parts, both in terms of dimensional and functional properties, is becoming more and more critical. Here, we present our work on characterizing existing VP printer light engines. We show the types of heterogeneity that are present in these light engines and how they can directly impact printed parts. This then leads us to a discussion about what optical properties are important to control in VP light engines for improved print reproducibility. Finally, we discuss our latest efforts to develop a fully calibrated and characterized uniform light engine for performing careful photopolymerization studies that inform on the underlying photopolymerization physics without convolving light engine heterogeneity with the underlying photophysics. Figure 1

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Jeon, Wungki, Sungho Hwang, Jae Joon Kim, and Myunghee Lee. "Active-Matrix Pixelated-LED Control System for Automotive Headlamps." IEEE Access, 2022, 1. http://dx.doi.org/10.1109/access.2022.3170113.

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Peng, Xuhui, Yang Zeng, Sitao Huo, Zhenyuan Yang, Xiaoping Huang, and Qing Zhao. "Investigation of Quantum Dot Color Filter Micro-LED Display." Photonic Sensors 14, no. 1 (December 1, 2023). http://dx.doi.org/10.1007/s13320-023-0698-5.

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AbstractIn this work, we present the investigation of the quantum dot color filter (QDCF) micro-light emitting diode (micro-LED) display. Green and red quantum dot photoresist (QDPR) materials are patterned into a pixelated array and precisely bonded with an all-blue micro-light emitting diode (micro-LED) substrate, forming a red, green, and blue (RGB) full color display through color conversion. A few factors that influence the achievable color gamut are further investigated. The resulting 1.1-inch 228-pixels per inch (ppi) display demo shows the good performance. The findings in this paper pave a way to the future industrialization of the micro-LED display.

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Yoon, Sunggun, Joonyun Kim, Young Ho Chu, Jinu Park, Ki‐Tae Park, Kyung Tak Yoon, Nakyung Kim, et al. "Controlled Fracture‐Based Micropatterning of Ruddlesden–Popper Halide Perovskite for Ultra High‐Density Arrays of Micro Light Emitting Diodes." Advanced Functional Materials, May 20, 2024. http://dx.doi.org/10.1002/adfm.202403151.

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AbstractQuasi‐2D Ruddlesden–Popper perovskite (RPP) have surfaced as a promising candidate for light emitting diodes (LEDs) due to its outstanding optoelectronic properties. However, a reliable approach for patterning RPPs remains elusive due to the use of polar solvents in lithographic processes, which can damage the RPP. Here, a reliable and damage‐free dry micropatterning method of RPPs is reported, which also offers a cost/time advantage compared to conventional patterning methods. The sharp edges of high aspect ratio silicon micropillars are used to cut RPPs to a pre‐defined shape and then the cut RPPs are delaminated to obtain a patterned array of RPPs. The resultant patterned array exhibits no sign of degradation or discernable difference between adjacent pixels, achieving a ≈100% yield. The obtained array is utilized to fabricate a pixelated LED where a sharp electroluminescence (EL) spectrum peaking at 410 nm with full‐width‐at‐half‐maximum (FWHM) of 10 nm is observed. The pixelated devices demonstrate the potential to suppress EQE drops as the pixel size decreases, attributed to both the damage‐free micropatterning process and the defect tolerance of RPPs. Moreover, further improvements of the patterning method are demonstrated to avoid parasitic emission and suggest a promising strategy to fabricate pixel‐accessible micro‐LEDs.

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Baron, Alisa, Vanessa Harwood, Daniel Kleinman, Luca Campanelli, Joseph Molski, Nicole Landi, and Julia Irwin. "Where on the face do we look during phonemic restoration: An eye-tracking study." Frontiers in Psychology 14 (May 25, 2023). http://dx.doi.org/10.3389/fpsyg.2023.1005186.

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Face to face communication typically involves audio and visual components to the speech signal. To examine the effect of task demands on gaze patterns in response to a speaking face, adults participated in two eye-tracking experiments with an audiovisual (articulatory information from the mouth was visible) and a pixelated condition (articulatory information was not visible). Further, task demands were manipulated by having listeners respond in a passive (no response) or an active (button press response) context. The active experiment required participants to discriminate between speech stimuli and was designed to mimic environmental situations which require one to use visual information to disambiguate the speaker’s message, simulating different listening conditions in real-world settings. Stimuli included a clear exemplar of the syllable /ba/ and a second exemplar in which the formant initial consonant was reduced creating an /a/−like consonant. Consistent with our hypothesis, results revealed that the greatest fixations to the mouth were present in the audiovisual active experiment and visual articulatory information led to a phonemic restoration effect for the /a/ speech token. In the pixelated condition, participants fixated on the eyes, and discrimination of the deviant token within the active experiment was significantly greater than the audiovisual condition. These results suggest that when required to disambiguate changes in speech, adults may look to the mouth for additional cues to support processing when it is available.

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Reinhold, Ingo, Moritz Thielen, Wolfgang Voit, Werner Zapka, Reiner Götzen, and Helge Bohlmann. "Electrical Through-Hole and Planar Interconnect Generation in Roll-to-Roll LED Lighting Manufacturing using Industrial Inkjet Printheads." MRS Proceedings 1340 (2011). http://dx.doi.org/10.1557/opl.2011.1270.

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ABSTRACTDespite the availability of many high-volume and low-cost manufacturing processes for LED-based lighting applications, relying mainly on fixed patterns such as LED-backlights and RGB-pixelated displays, novel applications, such as “mood lighting” or interior wall displays call for more complicated and shaped LED arrangements. The presented work is based of a novel roll-to-roll (R2R) process to adaptively and cost-efficiently generate LED arrangements on RMPD® substrates.Inkjet printing of planar and though-hole electrical interconnections is of high importance to the process, as it provides a fully digital way of interconnecting devices electrically, accounting for the actual position of the component and spatially provide different ink film thicknesses.Xaar’s industrial inkjet printheads are used to dispense defined volumes of 50 pL of a silver nanoparticle ink in order to provide high reliability and good positioning accuracy while main-taining low satellite drop densities. Specific printing strategies are investigated at a print speed of 0.1 m/s to allow for a reliable electrical connection in case of up to 50 μm deep via connections to the buried component.Due to the low glass-transition nature of the underlying substrates, low sintering tempera-tures are required to preserve the mechanical properties of the substrate. Low temperature oven sintering yielding sufficient conductivity to drive a current of 40 mA will be discussed.

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Bae, Junho, Yuseop Shin, Hyungyu Yoo, Yongsu Choi, Jinho Lim, Dasom Jeon, Ilsoo Kim, Myungsoo Han, and Seunghyun Lee. "Quantum dot-integrated GaN light-emitting diodes with resolution beyond the retinal limit." Nature Communications 13, no. 1 (April 6, 2022). http://dx.doi.org/10.1038/s41467-022-29538-4.

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AbstractNear-eye display technology is a rapidly growing field owing to the recent emergence of augmented and mixed reality. Ultrafast response time, high resolution, high luminance, and a dynamic range for outdoor use are all important for non-pixelated, pupil-forming optics. The current mainstream technologies using liquid crystals and organic materials cannot satisfy all these conditions. Thus, finely patterned light-emissive solid-state devices with integrated circuits are often proposed to meet these requirements. In this study, we integrated several advanced technologies to design a prototype microscale light-emitting diode (LED) arrays using quantum dot (QD)-based color conversion. Wafer-scale epilayer transfer and the bond-before-pattern technique were used to directly integrate 5-µm-scale GaN LED arrays on a foreign silicon substrate. Notably, the lithography-level alignment with the bottom wafer opens up the possibility for ultrafast operation with circuit integration. Spectrally pure color conversion and solvent-free QD patterning were also achieved using an elastomeric topographical mask. Self-assembled monolayers were applied to selectively alter the surface wettability for a completely dry process. The final emissive-type LED array integrating QD, GaN, and silicon technology resulted in a 1270 PPI resolution that is far beyond the retinal limit.

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Lee, Hsu-Chi, Yun-Chih Lu, Yu-Chen Lin, Wei-Lin Lai, Hsiang-Yuan Hsieh, Boy-Yiing Jaw, Chin-Tang Chuang, Yung-Chih Chen, and Yi-Jan Emery Chen. "A High Voltage Driving Chiplet in Standard 0.18-μm CMOS for Micro-Pixelated LED Displays Integrated with LTPS TFTs." IEEE Transactions on Circuits and Systems for Video Technology, 2022, 1. http://dx.doi.org/10.1109/tcsvt.2022.3168051.

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Rao, Tianyu, Qun Hao, Ge Mu, Tianling Qin, Yimei Tan, Pengfei Zhao, Dexi Kong, Menglu Chen, and Xin Tang. "Large-scale Fabrication of CMOS-compatible Silicon-OLED Heterojunctions enabled Infrared Upconverters." APL Photonics, February 15, 2023. http://dx.doi.org/10.1063/5.0138070.

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Infrared-to-visible upconverters have widespread application prospects, including bioimaging, night vision, and defense security. A typical upconverter is generally constructed by integrating an infrared photodetector (PD) detecting low-energy infrared with a visible light-emitting diode (LED) emitting high-energy visible light. However, when photocarriers transport through the interface between PD and LED, lateral current spreading inevitably presents, which leads to optical cross-talking and hinders the realization of high-resolution and large-area infrared imaging. Here, near-infrared (NIR) upconverters are fabricated via the integration of silicon (Si) NIR detectors with organic LED (OLED) by complementary-metal-oxide-semiconductor compatible manufacturing processes. The pixelated indium tin oxide (ITO) electrodes introduced as the interfacial carrier transfer channel effectively suppress lateral current spreading and ensure that the photogenerated carrier of PD could transport into the OLED with well-defined spatial resolution. The Si-OLED upconverters possess wafer-level luminous area and large-scale fabrication capacity and realize high-resolution infrared imaging with a resolution as high as 3629 dpi. By changing the organic luminescent layer of OLED, the Si-OLED upconverters could emit red/ green/ blue visible light under NIR illumination with a low turn-on voltage of 3 V and excellent upconversion efficiency of 9.2%. Furthermore, the large-area Si-OLED upconverters exhibit flexibility with an infrared upconversion ability even under bending.

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Miyata, Masashi. "Dispersion-engineered metasurfaces for high-sensitivity color image sensors." Optical Review, April 24, 2024. http://dx.doi.org/10.1007/s10043-024-00882-8.

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AbstractIncreasing the sensitivity of image sensors is a major challenge for current imaging technology. Researchers are tackling it because highly sensitive sensors enable objects to be recognized even in dark environments, which is critical for today’s smartphones, wearable devices, and automobiles. Unfortunately, conventional image-sensor architectures use light-absorptive color filters on every pixel, which fundamentally limits the detected light power per pixel. Recent advances in optical metasurfaces have led to the creation of pixelated light-transmissive color splitters with the potential to enhance sensor sensitivity. These metasurfaces can be used instead of color filters to distinguish primary colors, and unlike color filters, they can direct almost all of the incident light to the photodetectors, thereby maximizing the detectable light power. This review focuses on such metasurface-based color splitters enabling high-sensitivity color-image sensors. Their underlying principles are introduced with a focus on dispersion engineering. Then, their capabilities as optical elements are assessed on the basis of our recent findings. Finally, it is discussed how they can be used to create high-sensitivity color-image sensors.

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Xu, Han, Renzhi Hu, Shuai Chen, Junhong Zhu, Chi Zhou, and Yong Chen. "Vibration-assisted Vat Photopolymerization for Pixelated-aliasing-free Surface Fabrication." International Journal of Extreme Manufacturing, February 28, 2024. http://dx.doi.org/10.1088/2631-7990/ad2e14.

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Abstract Mask image projection-based vat photopolymerization (MIP-VPP) offers advantages like low cost, high resolution, and a wide material range, making it popular in industry and education. Recently, MIP-VPP employing liquid crystal displays (LCDs) has gained traction, increasingly replacing digital micromirror devices (DMDs), particularly among hobbyists and in educational settings, and is now beginning to be used in industrial environments. However, LCD-based MIP-VPP suffers from pronounced pixelated aliasing arising from LCD's discrete image pixels and its direct-contact configuration in MIP-VPP machines, leading to rough surfaces on the 3D-printed parts. Here, we propose a vibration-assisted MIP-VPP method that utilizes a microscale vibration to uniformize the light intensity distribution of the LCD-based mask image on VPP’s building platform. By maintaining the same fabrication speed, our technique generates a smoother, non-pixelated mask image, reducing the roughness on flat surfaces and boundary segments of 3D-printed parts. Through light intensity modeling and simulation, we derived an optimal vibration pattern for LCD mask images, subsequently validated by experiments. We assessed the surface texture, boundary integrity, and dimensional accuracy of components produced using the vibration-assisted approach. The notably smoother surfaces and improved boundary roughness enhance the printing quality of MIP-VPP, enabling its promising applications in sectors like the production of 3D-printed optical devices and others.

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Wang, Bing, Xiaoping Ouyang, Xiaosuo He, Zhiliang Deng, Yifan Zhou, and Pei Li. "High‐Resolution X‐Ray Imaging of Mn Enhanced Lead‐Free Halide Scintillators in Pixelated Array Structures." Advanced Optical Materials, May 18, 2023. http://dx.doi.org/10.1002/adom.202300388.

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Varkevisser, Judith M., Ralph Simon, Ezequiel Mendoza, Martin How, Idse van Hijlkema, Rozanda Jin, Qiaoyi Liang, Constance Scharff, Wouter H. Halfwerk, and Katharina Riebel. "Adding colour-realistic video images to audio playbacks increases stimulus engagement but does not enhance vocal learning in zebra finches." Animal Cognition, August 17, 2021. http://dx.doi.org/10.1007/s10071-021-01547-8.

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AbstractBird song and human speech are learned early in life and for both cases engagement with live social tutors generally leads to better learning outcomes than passive audio-only exposure. Real-world tutor–tutee relations are normally not uni- but multimodal and observations suggest that visual cues related to sound production might enhance vocal learning. We tested this hypothesis by pairing appropriate, colour-realistic, high frame-rate videos of a singing adult male zebra finch tutor with song playbacks and presenting these stimuli to juvenile zebra finches (Taeniopygia guttata). Juveniles exposed to song playbacks combined with video presentation of a singing bird approached the stimulus more often and spent more time close to it than juveniles exposed to audio playback only or audio playback combined with pixelated and time-reversed videos. However, higher engagement with the realistic audio–visual stimuli was not predictive of better song learning. Thus, although multimodality increased stimulus engagement and biologically relevant video content was more salient than colour and movement equivalent videos, the higher engagement with the realistic audio–visual stimuli did not lead to enhanced vocal learning. Whether the lack of three-dimensionality of a video tutor and/or the lack of meaningful social interaction make them less suitable for facilitating song learning than audio–visual exposure to a live tutor remains to be tested.

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Rao, Neethi, and Devaki Nambiar. "Reflections on Required Competencies For Health Systems Monitoring, Evaluation, and Learning In India." Journal of MultiDisciplinary Evaluation 19, no. 46 (December 11, 2023). http://dx.doi.org/10.56645/jmde.v19i46.873.

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The movement towards systems thinking and complexity-informed monitoring and evaluation has been ongoing for some time. Covid-19 has accelerated this shift and increased the salience of contextually aware, adaptive forms of evaluation. Drawing from our experience over three years of providing monitoring, evaluation, research and learning (MERL) to a large international philanthropic organization’s health systems portfolio of work in India, we identify three types of evaluator capacities and associated set of competencies that derive from complexity-driven practice in a developing country. The first type of capacity relates to deriving evidence in contexts where there are very few traditional forms of data. The MERL portfolio related to health systems outcomes of access, financial protection, and equity even as the health programs themselves were evolving in a period of rapid transformation and dynamism of policy priorities and implementation mechanisms. This required an integration of traditional performance indicators drawn from government datasets with qualitative ‘signals’ focused on drivers of change within the system. Assessment of signals in turn required synthesizing different sources of information, including informal channels of obtaining evidence such as partner meetings or government-sponsored events. The evaluating team thus consciously empowered different kinds of researchers with differential expertise with the goal of building a much more pixelated picture. The goal was not to identify a single source of truth but rather a patchwork of validated information where the relevance of different pieces of data were dependent on evolving outcomes of interest. The second set of competencies related to the skills required to play a convening role for donors and implementing partners, supporting better understanding of the changing operating context and help inform decision-making by program officers and partners. This involved building and sustaining relationships across different stakeholders at different stages of the project – from proposal development to review. Competencies relating to effective dialogue and developing an understanding of the core interests of international, national and sub-national partners as well as international donors and experts could only be developed iteratively and over time, but this was crucial in a distributed health decision-making ecosystem like India. The third and final set of competencies relate to operational adaptiveness, while evaluating an ecosystem with few constants. This can be the hardest competency to acquire because it is the farthest from the traditional notions embedded in the training of evaluation scientists and MERL practitioners. We found that the degree of buy-in and commitment to previously agreed upon frames of reference for evaluation can be shifted by changes in personnel or internal organizational structures. These shifts can lead to chain reactions of mismatched expectations that needed to be understood and managed in real time by MERL partners. The pandemic further created a natural experiment that on the one hand required a reexamination of program priorities and on the other depended on reliability of donor support. Each of these three types of capacities – synthesizing nuanced evidence for adaptive action, relationship building and communication, and managing operational discontinuities are in fact inter-dependent. Building evaluator competencies isn’t simply about capacity-building but rather a recognition of the diversity of skills and worldviews that need to be encompassed within our monitoring and evaluation functions for today’s complex, discontinuous health systems.

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Journal articles on the topic 'Pixelated LED'

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