• 제목/요약/키워드: Asymmetric division

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Control of Asymmetric Cell Divisions during Root Ground Tissue Maturation

  • Choi, Ji Won;Lim, Jun
    • Molecules and Cells
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    • 제39권7호
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    • pp.524-529
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    • 2016
  • Controlling the production of diverse cell/tissue types is essential for the development of multicellular organisms such as animals and plants. The Arabidopsis thaliana root, which contains distinct cells/tissues along longitudinal and radial axes, has served as an elegant model to investigate how genetic programs and environmental signals interact to produce different cell/tissue types. In the root, a series of asymmetric cell divisions (ACDs) give rise to three ground tissue layers at maturity (endodermis, middle cortex, and cortex). Because the middle cortex is formed by a periclinal (parallel to the axis) ACD of the endodermis around 7 to 14 days post-germination, middle cortex formation is used as a parameter to assess maturation of the root ground tissue. Molecular, genetic, and physiological studies have revealed that the control of the timing and extent of middle cortex formation during root maturation relies on the interaction of plant hormones and transcription factors. In particular, abscisic acid and gibberellin act synergistically to regulate the timing and extent of middle cortex formation, unlike their typical antagonism. The SHORT-ROOT, SCARECROW, SCARECROW-LIKE 3, and DELLA transcription factors, all of which belong to the plant-specific GRAS family, play key roles in the regulation of middle cortex formation. Recently, two additional transcription factors, SEUSS and GA- AND ABA-RESPONSIVE ZINC FINGER, have also been characterized during ground tissue maturation. In this review, we provide a detailed account of the regulatory networks that control the timing and extent of middle cortex formation during post-embryonic root development.

대용량 압축 데이터베이스를 위한 비대칭 색인 관리 기법 (Asymmetric Index Management Scheme for High-capacity Compressed Databases)

  • 변시우;장석우
    • 한국산학기술학회논문지
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    • 제17권7호
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    • pp.293-300
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    • 2016
  • 전통적인 기존의 데이터베이스는 높은 성능을 얻기 위하여 느린 하드 디스크에서 관련된 레코드가 연속적으로 저장되어 있는 레코드 기반 모델을 활용한다. 그러나 읽기 집중적인 데이터 분석 시스템을 위해서는 컬럼 기반 압축 데이터베이스가 월등한 판독 성능으로 인하여 더 적합한 모델이 되고 있으며, 최근 플래시 메모리 SSD가 고속 분석용 시스템에 적합한 저장 매체로 선호되고 있다. 본 논문에서는 세로로 저장하는 컬럼 기반 스토리지 모델을 소개하고, 대용량 데이터웨어하우스 시스템을 위한 새로운 인덱스와 데이터 관리 기법을 제안한다. 제안된 인덱스 관리 기법은 두 개의 인덱스를 사용하는 비대칭 인덱스 이중화이며, 갱신용 마스터 인덱스와 판독용 컴팩트 인덱스를 활용하여 특히 읽기가 집중된 빅 데이터베이스에서 우수한 검색 성능을 얻는다. 그리고 본 데이터 관리 기법은 관련된 컬럼 압축과 두 개의 플래시 메모리 SSD를 이중화하여 높은 판독 성능과 처리 안정성에 도움을 준다. 고부하 워크로드 조건의 성능 평가 결과를 기반으로, 본 데이터 관리 기법이 기존 기법보다 검색 처리 및 응답 시간 측면에서 더 우수함을 보이고자 한다.

Comparison of Buttock Pressure and Pelvic Tilting Angle During Typing in Subjects With and Without Unilateral Low Back Pain

  • Hwang, Ui-Jae;Kim, Si-Hyun;Choi, Houng-Sik;Kwon, Oh-Yun
    • 한국전문물리치료학회지
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    • 제21권1호
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    • pp.37-46
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    • 2014
  • Asymmetric sitting posture may cause asymmetric buttock pressure and unilateral low back pain (LBP). The purpose of this study was to compare the differences of buttock pressure between both sides, and pelvic angle (sagittal and coronal planes) during typing in a sitting position on a pressure mat (Baltube) in individuals with and without unilateral LBP. Ten subjects with unilateral LBP and ten subjects without unilateral LBP were recruited for this study. Buttock pressure was measured using a pressure mat and pelvic angles were measured using a palpation meter. The subjects performed typing in a sitting posture for 30 minutes. Pressure data were collected and averaged at initial term (from start to first minutes) and final term (last minutes of 30 minutes). Angles of pelvic tilting were measured after 30 minutes typing. Pressure asymmetry values (difference in pressure between both sides) were calculated at the initial and final terms. A two-way analysis of variance was used to compare the differences between the initial and final pressure asymmetry values in subjects with and without unilateral LBP. An independent t-test was applied to compare the pelvic tilt angles between the two groups. To compare the change of pressure from the initial term to the final term between the symptomatic and asymptomatic sides in the unilateral LBP group, a paired t-test was applied. In the unilateral LBP group, the pressure asymmetric value at the final term was significantly greater than that of the initial term (p<.05). The angle of pelvic tilting in coronal plane was significantly greater in the unilateral back pain group compared to the without unilateral LBP group (p<.05), however, there was no significant difference in the angle of pelvic tilting in the sagittal plane between the two groups (p>.05). In the unilateral LBP group, the change of pressure from the initial term to the final term was significantly less in the symptomatic side (-6.90 mmHg) than the asymptomatic side (5.10 mmHg). This asymmetric sitting posture may contribute to unilateral LBP in the sitting position. Further studies are needed to determine if asymmetric weight bearing in sitting causes unilateral LBP or if unilateral back pain causes asymmetric weight bearing, and if the correction of asymmetric weight bearing in sitting can reduce unilateral LBP.

Postero-Anterior Cephalometry를 이용한 안모의 비대칭에 관한 연구 (A RADIOGRAPHIC STUDY ON CRANIOFACIAL ASYMMETRY BY POSTERO-ANTERIOR CEPHALOMETRY)

  • 고재경;김재덕
    • 치과방사선
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    • 제17권1호
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    • pp.249-258
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    • 1987
  • The purpose of this article was to determine the amount of cranio-facial asymmetry in normal subject before the analysis of the cranio-facial asymmetry as the result of internal derangement in T.M.J. dysfunction. The author has conducted analysis using Cephalometric P-A reviews of 54 males and 51 females. Following the Grayson's method of measurement, the standard value of cranio-facial asymmetry in normal subject was obtained. The following results were obtained: 1. Compared with right and left width, asymmetry could be identified in normal subject, although the degree of the difference appears to be small. 2. In male, asymmetric value of contact point of the upper central incisors is 0.76±0.84㎜ that of the lower central incisors is 0.86±0.86㎜, and that of center of genial tubercle is 0.87±1.06㎜. In female, asymmetric value of contact point of the upper central incisors is 1.03±1.29㎜, that of lower incisors is 1.11 ±1.18㎜, and that of center of genial tubercle is 1.45±2.15㎜. 3. Cranio-facial saymmetry in female is somewhat greater than that of male.

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Regulatory Mechanism of Spindle Movements during Oocyte Meiotic Division

  • Ai, Jun-Shu;Li, Mo;Schatten, Heide;Sun, Qing-Yuan
    • Asian-Australasian Journal of Animal Sciences
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    • 제22권11호
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    • pp.1477-1486
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    • 2009
  • Female germ cell meiotic divisions are typically asymmetric, giving rise to two daughter cells with different sizes. Spindle movements including spindle migration from the oocyte center to the cortex and spindle rotation from parallel to perpendicular (typically in the mouse) at the cortex are crucial for these asymmetric divisions and therefore are crucial for gamete production. Different regulatory mechanisms for spindle movements have been determined in different species and a wide variety of different molecular components and processes that are involved in spindle movements have also been identified in different species. Here, we review the current state of knowledge as well as our understanding of mechanisms for spindle movements in different systems with focus on three main aspects: microtubules (MT), microfilaments (MF) and molecules associated with cytoskeletal organization as well as molecules that are not directly related to the cytoskeleton. How they might interact or function independently during female meiotic divisions in different species is discussed in detail.

Annealing Effect on Exchange Bias in NiFe/FeMn/CoFe Trilayer Thin Films

  • Kim, Ki-Yeon;Choi, Hyeok-Cheol;You, Chun-Yeol;Lee, Jeong-Soo
    • Journal of Magnetics
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    • 제13권3호
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    • pp.97-101
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    • 2008
  • We investigated the exchange bias fields at the NiFe/FeMn and FeMn/CoFe interfaces in 18.9-nm NiFe/15.0-nm FeMn/17.6-nm CoFe trilayer thin films as the annealing temperature was varied from room temperature to $250^{\circ}C$ in a vacuum for 1 hour in a magnetic field of 150 Oe. Interestingly, magnetic hysteresis (M-H) measurements showed that NiFe/FeMn/CoFe trilayer thin films exhibited a completely contrasting variation of the exchange bias fields at both the NiFe/FeMn and FeMn/CoFe interfaces with annealing temperatures. High-angle X-ray diffraction (XRD) measurements indicated the absence of any discernible effect of thermal treatment on the NiFe(111) and FeMn(111) peaks. The compositional depth profile obtained from X-ray photoelectron spectroscopy (XPS) results presented the asymmetric compositional depth profiles of the Mn and Fe atoms throughout the FeMn layer. We contend that this asymmetric compositional depth profile and the preferential Mn diffusion into the NiFe layer, compared to that into the CoFe layer, are conclusive experimental evidence of the contrasting variation of the exchange bias fields at two interfaces having a common polycrystalline FeMn(111) layer.

안면비대칭 환자의 악교정술 후 안면비대칭의 개선에 따른 악관절장애 증상의 변화 (CHANGES OF TEMPOROMANDIULAR JOINT SYMPTOMS AFTER ORTHOGNATHIC SURGERY IN THE ASYMMETRIC PROGNATHISM PATIENTS)

  • 김영삼;류동목
    • Journal of the Korean Association of Oral and Maxillofacial Surgeons
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    • 제33권5호
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    • pp.518-523
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    • 2007
  • Purpose: The purpose of this study is to prove that orthognatic surgery on asymmetric prognathism patients improve the temporomandibular dysfunction. Materials and methods: All 30 patients underwent mandibular setback with B-SSRO including 22 patients Le Fort I surgery in KyungHee medical center. Preoperative and postoperative PA cephalograms & transcranial radiographs were measured midline deviation in Mx and Mn, occlusal canting change, condyle position, the temporomandibular dysfunction were checked before surgery, within 1 month after surgery, $3{\sim}6$ months, 12-24 months after surgery respectively. Results: The temporomandibular dysfunction were relieved after surgery in 17 patients of 25 patients. Conclusion: Orthognatic surgery may benefit the temporomandibular joint dysfunction in facial asymmetry patients by obtaining a postoperative stable occlusion and better physiologic neuromuscular function. Specially impovement of occlusal canting may reduce condyle displacement of midline deviation side and the temporomandibular joint dysfunction.

Wide-Bandwidth Wilkinson Power Divider for Three-Way Output Ports Integrated with Defected Ground Structure

  • Sreyrong Chhit;Jae Bok Lee;Dal Ahn;Youna Jang
    • Journal of information and communication convergence engineering
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    • 제22권1호
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    • pp.14-22
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    • 2024
  • This study presents the design of a Wilkinson power divider for three-way output ports (WPD3OP), which incorporates a defected ground structure (DGS). An asymmetric power divider is integrated into the output ports of the conventional Wilkinson power divider (WPD), establishing a three-way output port configuration. The DGS introduces periodic or irregular patterns into the ground plane to suppress unwanted electromagnetic wave propagation, and its incorporation can enhance the performance of the power divider, in terms of the power-division ratio, isolation, and bandwidth, by reducing spurious resonances. The proposed design algorithm for an asymmetric power divider for three-way output ports is analyzed via circuit simulations using High-Frequency Simulation Software (HFSS). The results verify the validity of the proposed method. The analysis of the WPD3OP integrated with DGS certifies the achievement of a center frequency of 2 GHz. This confirmation is supported by schematic ideal design simulation results and measurements encompassing insertion losses, return losses, and isolation.

중계 구간의 개수가 다르고 RDPS가 비대칭인 분산 제어 링크 (Dispersion-Managed Link with Different Numbers of Fiber Spans and Asymmetric Distribution of RDPS)

  • 홍성화;이성렬
    • 한국항행학회논문지
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    • 제23권6호
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    • pp.570-576
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    • 2019
  • 광 네트워크의 융통적 구성을 위해 전체 전송로 중간이 아닌 위치에 존재하는 광 위상 공액기를 갖는 분산 제어 링크를 제안하였다. 제안하는 분산 제어 링크에서 광 위상 공액기는 6개 중계 구간으로 구성되는 전반 전송 구획과 14개로 구성되는 후반 전송 구획 사이에 존재하고, 각 전송 반 구획에서의 평균 중계 구간 당 잉여 분산 (RDPS; residual dispersion per span)이 서로 다른 비대칭 구조이다. 또한 파장 분할 다중 채널의 왜곡 보상을 위하여 각 중계 구간마다 실제 RDPS를 점진적으로 증가/감소시키는 인위적 분포 구조를 채택하였다. 시뮬레이션 결과 제안된 16개의 비대칭 분포 제어 링크 구조 중 인접한 중계 구간 간 RDPS 편차를 적게 하여 전반 전송 구획에서는 중계 구간의 실제 RDPS를 점진적으로 감소시키고 후반 전송 구획에서는 중계 구간의 실제 RDPS를 점진적으로 증가시키는 구조가 왜곡된 파장 분할 다중 채널의 보상에 적합한 것을 확인하였다.