281 research outputs found
Molecular Logic of Spinocerebellar Tract Neuron Diversity and Connectivity
No full textCoordinated motor behaviors depend on feedback communication between peripheral sensory systems and central circuits in the brain and spinal cord. Relay of muscle- and tendon-derived sensory information to the CNS is facilitated by functionally and anatomically diverse groups of spinocerebellar tract neurons (SCTNs), but the molecular logic by which SCTN diversity and connectivity is achieved is poorly understood. We used single-cell RNA sequencing and genetic manipulations to define the mechanisms governing the molecular profile and organization of SCTN subtypes. We found that SCTNs relaying proprioceptive sensory information from limb and axial muscles are generated through segmentally restricted actions of specific Hox genes. Loss of Hox function disrupts SCTN-subtype-specific transcriptional programs, leading to defects in the connections between proprioceptive sensory neurons, SCTNs, and the cerebellum. These results indicate that Hox-dependent genetic programs play essential roles in the assembly of neural circuits necessary for communication between the brain and spinal cord. © 2019 The Author(s)Baek et al. show that Hox-transcription-factor-dependent programs govern the specification and connectivity of spinal interneurons that relay muscle-derived sensory information to the cerebellum. These findings shed light on the development of neural circuits required for proprioception—the perception of body position. © 2019 The Author(s)1
Yagita's counter-examples and beyond
No full textA conjecture on a relationship between the Chow and Grothendieck rings for the generically twisted variety of Borel subgroups in a split semisimple group G, stated by the second author, has been disproved by Nobuaki Yagita in characteristic 0 for G=Spin(2n+1) with n =8 and n=9. For n=8, the second author provided an alternative simpler proof of Yagita's result, working in any characteristic, but failed to do so for n=9. This gap is filled here by involving a new ingredient - Pieri type K-theoretic formulas for highest orthogonal grassmannians. Besides, a similar counter-example for n=10 is produced. Note that the conjecture on Spin(2n+ 1) holds for n up to 5; it remains open for n=6, n=7, and every n >= 11.
Advanced in situ hydrogel assembly for guiding molecular release
No full textSince the emergence of hydrogels as carriers for cells, bioactive molecules, and even metallic nanoparticles, there were extensive efforts to control the rate and direction of embedded molecular release, largely by additional chemical modification of gel-forming polymers. However, these approaches often encountered several challenges including the instability of molecular cargos, the extensive labor of synthesis and purification, and the uncontrollability of the molecular release direction. In contrast, many biological systems use their geometry to guide the release of their molecules or signals. Inspired by nature, this study presents unique approaches with advanced in situ formation techniques, which can overcome the problems and control the release direction and rate of the diverse embedded materials in a hydrogel. First, I demonstrated a self-folding, multi-walled poly(ethylene glycol) diacrylate (PEGDA) hydrogel tube. This tubular structure was obtained by in situ self-folding of a bi-layered PEGDA hydrogel patch constructed with gels of significantly different rigidity and expansion ratio. The radiuses of the resulting gel tubes were estimated with bilayer curvature equations and agreed with experimental data. Second, the resulting hydrogel was used to control the release rate and direction of embedded molecules by localizing the molecules in a center of the tube. A finite element method (FEM) based simulation was performed to explain the geometrical effect on controlling the molecular release. Additionally, the bilayered PEGDA hydrogel encapsulating VEGF was implanted on a chicken chorioallantoic membrane (CAM) to evaluate the neovascularization. Due to the spatiotemporal release of VEGF, the gel tubes significantly increased the density and diameters of blood vessels, compared to unfolded hydrogel patches and other ring-shaped hydrogels. Third, I presented a bio patch delivery system with minimal invasive manner by using the self-folding and unfolding technique. I assembled the hydrogel patch with a sacrificial layer that can dissolve in media after a controlled time. This hydrogel patch self-folded into a compact tube shape and delivered via a catheter to a targeted area followed by unfolding to a patch after a particular time. Lastly, I reported an in situ synthesis of metal nanoparticle-hydrogel composite that can sustainably reduce the release rate of embedded metal nanoparticles. The resulting gel composite with antimicrobial property of embedded metallic nanoparticles could control bacterial cell growth in an aqueous media and also inhibit biofilm formation on a polymeric and metallic substrates coated with the gel composite. Overall, this study was conducted for enhancing the efficacy of molecular compounds used for various agricultural products, food additives, sensor devices, and clinical treatments.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2017-05-01The student, Kwanghyun Baek, accepted the attached license on 2015-04-08 at 11:39.The student, Kwanghyun Baek, submitted this Dissertation for approval on 2015-04-08 at 12:02.This Dissertation was approved for publication on 2015-04-13 at 13:21.DSpace SAF Submission Ingestion Package generated from Vireo submission #7802 on 2015-07-22 at 14:24:15Made available in DSpace on 2015-07-22T22:45:11Z (GMT). No. of bitstreams: 2
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Author Correction: Genetic factors affecting dopaminergic deterioration during the premotor stage of Parkinson disease
No full textErratum for:
Genetic factors affecting dopaminergic deterioration during the premotor stage of Parkinson disease.
Lee MJ, Pak K, Kim HK, Nudelman KN, Kim JH, Kim YH, Kang J, Baek MS, Lyoo CH.
NPJ Parkinsons Dis. 2021 Nov 26;7(1):104. doi: 10.1038/s41531-021-00250-2.
PMID: 3483696
Variability study of Si nanowire FETs with different junction gradients
No full textRandom dopant fluctuation effects of gate-all-around Si nanowire field-effect transistors (FETs) are investigated in terms of different diameters and junction gradients. The nanowire FETs with smaller diameters or shorter junction gradients increase relative variations of the drain currents and the mismatch of the drain currents between source-drain and drain-source bias change in the saturation regime. Smaller diameters decreased current drivability critically compared to standard deviations of the drain currents, thus inducing greater relative variations of the drain currents. Shorter junction gradients form high potential barriers in the source-side lightly-doped extension regions at on-state, which determines the magnitude of the drain currents and fluctuates the drain currents greatly under thermionic-emission mechanism. On the other hand, longer junction gradients affect lateral field to fluctuate the drain currents greatly. These physical phenomena coincide with correlations of the variations between drain currents and electrical parameters such as threshold voltages and parasitic resistances. The nanowire FETs with relatively-larger diameters and longer junction gradients without degrading short channel characteristics are suggested to minimize the relative variations and the mismatch of the drain currents. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).1163Ysciescopu
Erratum: Solar Cell Using Hourglass-Shaped Silicon Nanowires for Increased Light-Trapping Path (IEEE J. Photovolt. (2020) 10: 2 475-479) DOI: 10.1109/JPHOTOV.2020.2964329)
No full textIn the above article [1], the author Kihyun Kim's affiliation is modified from the Future IT Innovation Laboratory, Department of Creative IT Engineering, Pohang University of Science and Technology, Pohang 37673, South Korea ([email protected]).to Division of Electronic Engineering, Jeonbuk National University, Jeonju 54896, South Korea (e-mail: [email protected]).. © 2020 IEEE.11Nsciescopu
An extension of the weighted sum of gray gases non-gray gas radiation model to a two phase mixture of non-gray gas with particles
No full textA great deal of efforts has been exercised to date to accurately model the non-gray behavior of the gases. Among others, the weighted sum of gray gases model (WSGGM), which replaces the non-gray gas behavior by an equivalent finite number of gray gases, is a simplified model yielding reasonable results. However, a discussion on the weighting factors required for an estimation of radiation in a mixture of non-gray gas/gray particulate is not yet established for WSGGM, since they are dependent on the particle number density, particle size distribution: local temperature and partial pressure. Consequently, the relation between the weighting factors used in the WSGGM for a mixture of non-gray gas and gray particles with scattering in the thermal non-equilibrium has been discussed here, which has not been done before to the author's best knowledge. Weighting factors for the particles, of which temperature is different from that of the gas, were evaluated analytically for the WSGGM. The results were, then, validated for the problem of isothermal gas containing soot particulates between two parallel slab walls. For further application, the approach derived here was implemented to examine the non-gray radiative effects of the two phase mixture in an axisymmetric cylinder by changing such various parameters as the particle temperature, non-gray gas composition and particle concentration. The effects of thermal non-equilibrium in a mixture of gas and particles were also discussed in parallel with scattering effects by particles. Parametric study showed that a variation in the gas concentration yielded a noticeable change in the radiative heat transfer when the suspended particle temperature was different from the gas temperature. New contribution of this study consisted in an extension of applicability of the WSGGM non-gray model to two phase radiation. (C) 2000 Elsevier Science Ltd. All rights reserved.The authors wish to acknowledge the financial support of the Korea Research Foundation made in the program year of 1998 under the contract 1998-018-E00016
Mechanisms of RNA and Protein Quality Control and Their Roles in Cellular Senescence and Age-Related Diseases
No full textCellular senescence, a hallmark of aging, is defined as irreversible cell cycle arrest in response to various stimuli. It plays both beneficial and detrimental roles in cellular homeostasis and diseases. Quality control (QC) is important for the proper maintenance of cellular homeostasis. The QC machineries regulate the integrity of RNA and protein by repairing or degrading them, and are dysregulated during cellular senescence. QC dysfunction also contributes to multiple age-related diseases, including cancers and neurodegenerative, muscle, and cardiovascular diseases. In this review, we describe the characters of cellular senescence, discuss the major mechanisms of RNA and protein QC in cellular senescence and aging, and comprehensively describe the involvement of these QC machineries in age-related diseases. There are many open questions regarding RNA and protein QC in cellular senescence and aging. We believe that a better understanding of these topics could propel the development of new strategies for addressing age-related diseases
High-Throughput and Computational Study of Leaf Senescence through a Phenomic Approach
No full textLeaf senescence is influenced by its life history, comprising a series of developmental and physiological experiences. Exploration of the biological principles underlying leaf lifespan and senescence requires a schema to trace leaf phenotypes, based on the interaction of genetic and environmental factors. We developed a new approach and concept that will facilitate systemic biological understanding of leaf lifespan and senescence, utilizing the phenome high-throughput investigator (PHI) with a single-leaf-basis phenotyping platform. Our pilot tests showed empirical evidence for the feasibility of PHI for quantitative measurement of leaf senescence responses and improved performance in order to dissect the progression of senescence triggered by different senescence-inducing factors as well as genetic mutations. Such an establishment enables new perspectives to be proposed, which will be challenged for enhancing our fundamental understanding on the complex process of leaf senescence. We further envision that integration of phenomic data with other multi-omics data obtained from transcriptomic, proteomic, and metabolic studies will enable us to address the underlying principles of senescence, passing through different layers of information from molecule to organism.
© 2017 Lyu, Baek, Jung, Chu, Nam, Kim and Lim. This is an open-access
article distributed under the terms of the Creative Commons Attribution License
(CC BY). The use, distribution or reproduction in other forums is permitted, provided
the original author(s) or licensor are credited and that the original publication in this
journal is cited, in accordance with accepted academic practice. No use, distribution
or reproduction is permitted which does not comply with these terms. © 2017 Lyu, Baek, Jung, Chu, Nam, Kim and Lim. This is an open-access
article distributed under the terms of the Creative Commons Attribution License
(CC BY). The use, distribution or reproduction in other forums is permitted, provided
the original author(s) or licensor are credited and that the original publication in this
journal is cited, in accordance with accepted academic practice. No use, distribution
or reproduction is permitted which does not comply with these terms.
© 2017 Lyu, Baek, Jung, Chu, Nam, Kim and Lim. This is an open-access
article distributed under the terms of the Creative Commons Attribution License
(CC BY). The use, distribution or reproduction in other forums is permitted, provided
the original author(s) or licensor are credited and that the original publication in this
journal is cited, in accordance with accepted academic practice. No use, distribution
or reproduction is permitted which does not comply with these terms.2
ツングース諸語のWH相関構文の分布に対する類型的考察
No full text資料・研究ノートAs shown in Baek (2011), Udihe WH correlatives have both characteristics of Chinese WH correlatives (WH-WH type) and Russian WH correlatives (WH-DEM type). Extending the scope of study to the whole Tungusic languages, this paper aims to contemplate on the distribution of WH correlative in the Tungusic languages from a typological view. Referring to the grammatical and textual materials of the Tungusic languages, the author attempts to classify WH correlative of the Tungusic languages in two types (WH-WH type, WH-DEM type). In addition, second focus is placed on syntactic construction of the first correlative clause to verify whether it could complete a sentence on its own or not. In conclusion, depending on the location of each language, the Tungusic languages could be arranged in a hierarchy as below. Chinese type Russian type WH-WH, Non-finite WH-DEM, Finite C R1 R2 R3 Manchu Ulcha Uilta Evenki Sibe Nanay Evenki Hezhe Udihe Negidal Solon Orochi Fig. The hierarchy of Tungusic correlative
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