Slim-panel holographic video display An, Jungkwuen; Won, Kanghee; Kim, Young ...
Nature communications,
11/2020, Letnik:
11, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Since its discovery almost 70 years ago, the hologram has been considered to reproduce the most realistic three dimensional images without visual side effects. Holographic video has been extensively ...researched for commercialization, since Benton et al. at MIT Media Lab developed the first holographic video systems in 1990. However, commercially available holographic video displays have not been introduced yet for several reasons: narrow viewing angle, bulky optics and heavy computing power. Here we present an interactive slim-panel holographic video display using a steering-backlight unit and a holographic video processor to solve the above issues. The steering-backlight unit enables to expand the viewing angle by 30 times and its diffractive waveguide architecture makes a slim display form-factor. The holographic video processor computes high quality holograms in real-time on a single-chip. We suggest that the slim-panel holographic display can provide realistic three-dimensional video in office and household environments.
This study examines the learning patterns of intermediate and advanced Korean learners in the acquisition of causative expressions according to their proficiency and the causative sentence type. We ...measured their grammatical knowledge using three types of grammaticality judgment tasks (GJTs) and self-paced reading tasks (SPRTs) differing in time limit and modality. We included the GJT
A'
score and reading time (RT) for SPRTs’ target and spillover regions. The results showed that intermediate learners’ accuracy for morphological and lexical causatives was lower than that for syntactic causatives, while advanced learners’ accuracy for lexical causatives was lower than that for syntactic and morphological causatives. Learners showed a lower accuracy for timed written and aural GJTs than untimed GJT. In SPRT, learners took twice as long to process the target regions as native speakers and even longer to process spillover regions. Advanced learners had a longer RT. Learners had a low correct rate for causative suffix substitution and adjectival root questions, substitution questions on causative markers, and substitution questions on causee case postpositions in morphological, syntactic, and lexical causatives. Learners showed confusion with active sentences in lexical causatives. This study has implications for understanding causative expression acquisition for learners’ proficiency levels.
The Chicxulub bolide impact 66 million years ago drove the near-instantaneous collapse of ocean ecosystems. The devastating loss of diversity at the base of ocean food webs probably triggered ...cascading extinctions across all trophic levels
and caused severe disruption of the biogeochemical functions of the ocean, and especially disrupted the cycling of carbon between the surface and deep sea
. The absence of sufficiently detailed biotic data that span the post-extinction interval has limited our understanding of how ecosystem resilience and biochemical function was restored; estimates
of ecosystem 'recovery' vary from less than 100 years to 10 million years. Here, using a 13-million-year-long nannoplankton time series, we show that post-extinction communities exhibited 1.8 million years of exceptional volatility before a more stable equilibrium-state community emerged that displayed hallmarks of resilience. The transition to this new equilibrium-state community with a broader spectrum of cell sizes coincides with indicators of carbon-cycle restoration and a fully functioning biological pump
. These findings suggest a fundamental link between ecosystem recovery and biogeochemical cycling over timescales that are longer than those suggested by proxies of export production
, but far shorter than the return of taxonomic richness
. The fact that species richness remained low as both community stability and biological pump efficiency re-emerged suggests that ecological functions rather than the number of species are more important to community resilience and biochemical functions.
Measuring, recording and analyzing spectral information of materials as its unique finger print using a ubiquitous smartphone has been desired by scientists and consumers. We demonstrated it as drug ...classification by chemical components with smartphone Raman spectrometer. The Raman spectrometer is based on the CMOS image sensor of the smartphone with a periodic array of band pass filters, capturing 2D Raman spectral intensity map, newly defined as spectral barcode in this work. Here we show 11 major components of drugs are classified with high accuracy, 99.0%, with the aid of convolutional neural network (CNN). The beneficial of spectral barcodes is that even brand name of drug is distinguishable and major component of unknown drugs can be identified. Combining spectral barcode with information obtained by red, green and blue (RGB) imaging system or applying image recognition techniques, this inherent property based labeling system will facilitate fundamental research and business opportunities.
This study presents a modified version of the Korean Elicited Imitation (EI) test, designed to resemble natural spoken language, and validates its reliability as a measure of proficiency. The study ...assesses the correlation between average test scores and Test of Proficiency in Korean (TOPIK) levels, examining score distributions among beginner, intermediate, and advanced learner groups. Using item response theory (IRT), the study explores the influence of four key facets—learners, items, raters, and constructs—on performance evaluation. An explanatory item response modeling (EIRM) analysis identified linguistic factors impacting the EI test’s performance. Notably, the study uncovered a robust positive correlation between EI test scores and TOPIK levels. Significant score disparities were observed between beginner and intermediate, as well as beginner and advanced, learner cohorts. An IRT-based exploration of each facet revealed that item difficulty was comparatively lower in contrast to learners’ commendable performance, and raters exhibited a high degree of scoring consistency. The EIRM analysis underscores the significance of variables such as the number of syllables, vocabulary score, and content word density in influencing test performance.
Stackable select devices such as the oxide p-n junction diode and the Schottky diode (one-way switch) have been proposed for non-volatile unipolar resistive switching devices; however, bidirectional ...select devices (or two-way switch) need to be developed for bipolar resistive switching devices. Here we report on a fully stackable switching device that solves several problems including current density, temperature stability, cycling endurance and cycle distribution. We demonstrate that the threshold switching device based on As-Ge-Te-Si material significantly improves cycling endurance performance by reactive nitrogen deposition and nitrogen plasma hardening. Formation of the thin Si₃N₄ glass layer by the plasma treatment retards tellurium diffusion during cycling. Scalability of threshold switching devices is measured down to 30 nm scale with extremely fast switching speed of ~2 ns.
This study examined challenges Korean language teachers face in classroom teaching contexts, based on typologies derived from a cluster analysis. A total of 181 teachers teaching adult immigrants ...were surveyed on their challenges using a 24-item survey across the following five dimensions: (1) teaching contents and teaching methods, (2) curriculum design and resource development, (3) language ability assessment, (4) learner counseling, and (5) cultural education. The cluster analysis suggested a three-cluster pattern based on the degree of challenge. Results indicate that the clusters differed significantly in the degree and order of perceived challenges. In addition, when socio-demographic data were considered, results revealed contrasts in the motivation for pursuing professional development, teaching experiences, teaching region, and professional development experience. This study thus provides insight into the multifaceted challenges Korean language teachers face and holds important implications for future professional development.
Myopia is a substantial global public health concern primarily linked to the elongation of the axial length of the eyeball. While numerous animal models have been employed to investigate myopia, the ...specific contributions of genetic factors and the intricate signaling pathways involved remain incompletely understood. In this study, we conducted RNA-seq analysis to explore genes and pathways in two distinct myopia-inducing mouse models: form-deprivation myopia (FDM) and lens-induced myopia (LIM). Comparative analysis with a control group revealed significant differential expression of 2362 genes in FDM and 503 genes in LIM. Gene Set Enrichment Analysis (GSEA) identified a common immune-associated pathway between LIM and FDM, with LIM exhibiting more extensive interactions. Notably, downregulation was observed in OxPhos complex III of FDM and complex IV of LIM. Subunit A of complex I was downregulated in LIM but upregulated in FDM. Additionally, complex V was upregulated in LIM but downregulated in FDM. These findings suggest a connection between alterations in energy metabolism and immune cell activation, shedding light on a novel avenue for understanding myopia's pathophysiology. Our research underscores the necessity for a comprehensive approach to comprehending myopia development, which integrates insights from energy metabolism, oxidative stress, and immune response pathways.
This study aims to investigate the feasibility of Zenith Fenestrated AAA Endovascular Graft (Z-FEN, Cook Medical) from a single Korean institution database by evaluating the vascular anatomy of ...Korean abdominal aortic aneurysm (AAA) patients with hostile aortic neck.
This is a retrospective study on patients with AAA who underwent endovascular aortic repair (EVAR) and open surgery repair between January 2012 and December 2021 (n = 211). The anatomic characteristics of the aortic neck were evaluated using 3-dimensional reconstructed computed tomographic scans. For the juxtarenal AAA patients (n = 39), feasibility of fenestrated stent graft was evaluated under the protocol of fenestrated EVAR. For those who were not suitable for the application of Z-FEN, the reasons for unsuitability were analyzed.
Among 211 AAA patients, 108 patients (51.2%) had complex aortic neck, and 39 (18.5%) had insufficient aortic neck length (<15 mm) for conventional EVAR. Of the 39 patients with juxtarenal AAAs, 13 (33.3%) were determined feasible for Z-FEN. Twenty-six patients (66.7%) were noncandidate for Z-FEN due to severe neck angulation, short aortic neck length, inadequate iliac artery anatomy, large aortic neck diameter, and severe calcification and thrombosis. Proximal aortic neck length of the non-feasible group was significantly shorter than that of the feasible group (P = 0.002).
Z-FEN was applicable to 33.3% of the juxtarenal AAA patients. As recent studies confirm, the effectiveness and safety of fenestrated EVAR, Z-FEN can be an option for AAA patients with short aortic neck.
PDF
