• Title, Summary, Keyword: heterogeneity

Search Result 1,433, Processing Time 0.048 seconds

An Approach to the Analysis of Landscape Heterogeneity in Seoul Metropolitan Suburbs (서울시 주변지역의 경관이질성 변화 분석기법 개발을 위한 기초연구)

  • 안동만;박은관;김인호;김명수;박소영
    • Journal of the Korean Institute of Landscape Architecture
    • /
    • v.26 no.3
    • /
    • pp.288-296
    • /
    • 1998
  • Natural or human disturbances cause landscape changes, which may be measured by the degree of heterogeneity. In a 16km$\times$19km area, divided into 100m$\times$100m cells, of Seoul city and its suburb, land covers are classified into 6 groups in aerial photos and land use maps. The degree of heterogeneity is defined as the number of cells that surround a central cell but have different land cover from the central cell divided by 8. The value of the degree of heterogeneity is between 0 and 1. Major findings are 1) Both urban and natural areas have low degree of heterogeneity, about 0.15~0.17. 2) Suburban area under heavy pressure of development and urbanization has highest degree of heterogeneity, about 0.25. 3) The peak of the degree of heterogeneity moved about 4.5km outward in 22 years. 4) Outer suburban area has lower degree of heterogeneity as the area is a greenbelt or forest. 5) The results show the areas with higher degree of heterogeneity which may need landscape management plans, and natural areas with lower degree of heterogeneity which may need landscape conservation plans. A landscape change model may be built for a specific city when this technique is applied to multiple sectors of the city, and the model may predict future landscape changes of the city.

  • PDF

A Study on the Method for Solving Data Heterogeneity in the Integrated Information System (통합 정보시스템에서의 데이터 이질성 해결 방안에 관한 연구)

  • Park, Seong-Jin;Park, Sung-Kong;Park, Hwa-Gyoo
    • Journal of Information Technology Services
    • /
    • v.7 no.4
    • /
    • pp.87-99
    • /
    • 2008
  • As the technologies for telecommunication have been evolving, more enhanced information services and integrated information systems have been introduced, which can manage a variety of information from the heterogeneous systems. The major obstacle for the integrated information systems is the integrating heterogeneous databases in the systems and the heterogeneity problems can be classified into the structural and data heterogeneities. However, the previous researches have mainly highlighted into the solving structural heterogeneity problems. This paper identifies the data heterogeneity problems for multi-database schema integrations and proposes a new solving method. We analyze the semantics equivalence in data values based on the functional dependency, primary and candidate keys, and present a procedural solution of data heterogeneity in the perspective of the concept of attribute equivalence, integration key and conceptual integration table.

RELATIONSHIP BETWEEN VIRULENCE, METABOLIC ACID AND GENETIC HETEROGENEITY OF PORPHYROMONAS GINGIVALIS (Porphyromonas gingivalis의 독성, 대사산물 및 유전자이종성과의 관련성)

  • Kim, Kang-Ju;Chung, Chong-Pyoung
    • Journal of Periodontal and Implant Science
    • /
    • v.23 no.1
    • /
    • pp.1-15
    • /
    • 1993
  • P. gingivalis has been implicated as a strong pathogen in periodontal disease and known to have three serotypes of P. gingivalis. The purpose of this study is to investigate on the relationship between virulence, metabolic acids and genetic heterogeneity of P. gingivalis. P. gingivalis W50 standard strain and five strains of P. gingivalis serotype b Korean isolates were used in this study. For in vitro virulence test, lyophilized whole cell P. gingivalis were suspended, and sonicated with ultrasonic dismembranometer. Sonicated samples were applied to cultured cells derived from periodontal ligament, and cell activity was assayed with growth and survival assay. The metabolic acids were also extracted, and determined by High Performance Liquid Chromatography. Pst I-digested bacterial genomic DNA was electrophoresed, and densitometric analysis was performed to study the genetic heterogeneity. All of the P. gingivalis serotype b produced butyric acid. In cell activity study, butyric acid inhibited the cell activity irrespective of its concentration. Densitometric analysis showed restriction fragment length polymorphism. These results suggested that there existed heterogeneity of the metabolic acids and the virulence of P. gingivalis and such heterogeneity might be related to genetic heterogeneity.

  • PDF

Top Management Team Heterogeneity, Interaction and Organizational Performance in Korean Hospitals (최고경영자 팀이 의료기관의 성과에 미치는 영향)

  • Jung, Moung-Suk;Lee, Se-Hoon;Kim, Kwang-Jum
    • Health Policy and Management
    • /
    • v.20 no.1
    • /
    • pp.137-154
    • /
    • 2010
  • This study empirically analyzed the effects of the Top Management Team (TMT) on organizational performance. We verified whether the age heterogeneity, job heterogeneity (core career, core function and major), and process (communication and integration) of the TMT affect organizational performance (management performance and healthcare service quality evaluation level). We collected data about 473 members of the 2006 TMT in 81 medical institutions. We also utilized statistics of organizational performance from the Ministry for Health, Welfare and Family Affairs and the Korean Institute of Hospital Management. Results of the study showed that the age heterogeneity of TMT exerted a negative effect on the healthcare service quality evaluation level, while the process exerted a positive effect. However, the age heterogeneity, job heterogeneity, and process had no influence on management performance. We discussed the implications of such outcome of the investigation in comparison with the former studies on TMT and organizational performance, and presented its restrictions and future plans.

Using Mixed Logit Model and Latent Class Model to Analyze Preference Heterogeneity in Choice Experiment Data (선택실험법 자료에서의 선호이질성 분석을 위한 혼합로짓모형 및 잠재계층모형의 활용)

  • Yoo, Byong Kook
    • Environmental and Resource Economics Review
    • /
    • v.21 no.4
    • /
    • pp.921-945
    • /
    • 2012
  • Conditional Logit (CL) model is widely used since its model estimation and interpretation of results of the model is relatively easy, on the other hand, it has the limit of preference heterogeneity of respondents being not fully considered. In this study we used the two models, Mixed Logit (ML) Model and Latent Class Model (LCM) to explain preference heterogeneity of respondents for protection for Boryeong Dam wetland. As a result of the examination for heterogeneity in Boryeong city and six metropolitan areas, we found there was significant difference between two regions. While there was explicit preference heterogeneity within respondents in Boryeong city, we found little heterogeneity within respondents in six metropolitan areas. Thus in the case of six metropolitan areas, CL model can be used for parameter estimation while in the case of Boryeong city, WTP estimates are based on parameter estimates from ML model to reflect the heterogeneity within respondents. Additionally, ML model with interaction and 2-class LCM for respondents in Boryeong city were used to explain the sources of the heterogeneity. The ML model with interaction has advantage of explaining individual unobserved heterogeneity. However The comarison between these two models reflects the fact that LCM provided added information that was not conveyed in the ML model with interaction. Thus, Preference heterogeneity within respondents in this study may be better explained by class level through LCM rather than indiviual level through ML model.

  • PDF

Inherent Random Heterogeneity Logit Model for Stated Preference Freight Mode Choice (SP 화물수단선택을 위한 Inherent Random Heterogeneity 로짓 모형 연구)

  • KIM, Kang-Soo
    • Journal of Korean Society of Transportation
    • /
    • v.20 no.3
    • /
    • pp.83-92
    • /
    • 2002
  • Freight mode choice models are essential to the analysis of many areas of transport research. However, observations of actual market choices have only been made in a limited number of situations. Therefore, stated preference(SP) techniques have emerged as an alternative source of actual market choices to be used for estimating freight mode choice models. Considerable confidence exists about SP data, but little consideration has been given to the potential for estimation bias. This paper has been motivated by the theoretical side of estimating SP discrete choice models, focusing on a case study of freight mode choice. Recently developed simulation methods are used to construct inherent random heterogeneity legit models, which consider individual heterogeneity, its inheritance to the next choices and overcome the independence from irrelevant alternatives (IIA) property. This Paper contributes to the development of models dealing with heterogeneity and its inheritance, and sheds light on the heterogeneity of freight transport.

Channel Heterogeneity Aware Channel Assignment for IEEE 802.11 Multi-Radio Multi-Rate Wireless Networks (IEEE 802.11 다중 라디오 다중 전송률 무선 네트워크를 위한 채널 이질성 인지 채널 할당)

  • Kim, Sok-Hyong;Kim, Dong-Wook;Suh, Young-Joo
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.36 no.11A
    • /
    • pp.870-877
    • /
    • 2011
  • IEEE 802.11 devices are widely used, and terminals can be equipped with multiple IEEE 802.11 interfaces as low-cost IEEE 802.11 devices are deployed. The off-the-shelf IEEE 802.11 devices provide multiple channels and multiple data rates. In practical multi-channel networks, since there is channel heterogeneity which indicates that channels have different signal characteristics for the same node, channels should be efficiently assigned to improve network capacity. In addition, in multi-rate networks, low-rate links severely degrade the performance of high-rate links on the same channel, which is known as performance anomaly. Therefore, in this paper, we propose a heterogeneity aware channel assignment (HACA) algorithm that improves network performance by reflecting channel heterogeneity and performance anomaly. Through NS-2 simulations, we validate that the HACA algorithm shows improved performance compared with existing channel assignment algorithms that do not reflect channel heterogeneity.

The AURKA Gene rs2273535 Polymorphism Contributes to Breast Carcinoma Risk - Meta-analysis of Eleven Studies

  • Guo, Xu-Guang;Zheng, Lei;Feng, Wei-Bo;Xia, Yong
    • Asian Pacific Journal of Cancer Prevention
    • /
    • v.15 no.16
    • /
    • pp.6709-6714
    • /
    • 2014
  • The rs2273535 polymorphism in the AURKA gene had proven to be associated with breast carcinoma susceptibility. Nevertheless, the results of different studies remain contradictory. A meta-analysis covering 28, 789 subjects from eleven different studies was here carried out in order to investigate the association in detail. The random effects model was used to analyze the pooled odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs). A significant relationship between the rs2273535 polymorphism and breast tumors was found in an allelic genetic model (OR: 1.076, 95% CI: 1.004-1.153, p=0.040, $P_{heterogeneity}$=0.002). No significant association was detected in a homozygote model (OR: 1.186, 95% CI: 0.990-1.423, P=0.065, $P_{heterogeneity}$=0.002), a heterozygote model (OR: 1.016, 95% CI: 0.959-1.076, p=0.064, $P_{heterogeneity}$=0.000), a dominant genetic model (OR: 1.147, 95% CI: 0.992-1.325, p=0.217, $P_{heterogeneity}$=0.294) and a recessive genetic model (OR: 1.093, 95% CI: 0.878-1.361, p=0.425, $P_{heterogeneity}$=0.707). A significant relationship between the rs2273535 polymorphism in the AURKA gene and breast tumor in Asian group was found in an allelic genetic model (OR: 1.124, 95% CI: 1.003-1.29, p=0.044, $P_{heterogeneity}$=0.034), a homozygote model (OR: 1.229, 95% CI: 1.038-1.455, p=0.016, $P_{heterogeneity}$=0.266) and a recessive genetic model (OR: 1.227, 95% CI: 1.001-1.504, p=0.049, $P_{heterogeneity}$=0.006). A significant association was thus observed between the rs2273535 polymorphism in the AURKA gene and breast cancer risk. Individuals with the rs2273535 polymorphism in the AURKA gene have a higher risk of breast cancer in Asian populations, but not in Caucasians.

Impact of rock microstructures on failure processes - Numerical study based on DIP technique

  • Yu, Qinglei;Zhu, Wancheng;Tang, Chun'an;Yang, Tianhong
    • Geomechanics and Engineering
    • /
    • v.7 no.4
    • /
    • pp.375-401
    • /
    • 2014
  • It is generally accepted that material heterogeneity has a great influence on the deformation, strength, damage and failure modes of rock. This paper presents numerical simulation on rock failure process based on the characterization of rock heterogeneity by using a digital image processing (DIP) technique. The actual heterogeneity of rock at mesoscopic scale (characterized as minerals) is retrieved by using a vectorization transformation method based on the digital image of rock surface, and it is imported into a well-established numerical code Rock Failure Process Analysis (RFPA), in order to examine the effect of rock heterogeneity on the rock failure process. In this regard, the numerical model of rock could be built based on the actual characterization of the heterogeneity of rock at the meso-scale. Then, the images of granite are taken as an example to illustrate the implementation of DIP technique in simulating the rock failure process. Three numerical examples are presented to demonstrate the impact of actual rock heterogeneity due to spatial distribution of constituent mineral grains (e.g., feldspar, quartz and mica) on the macro-scale mechanical response, and the associated rock failure mechanism at the meso-scale level is clarified. The numerical results indicate that the shape and distribution of constituent mineral grains have a pronounced impact on stress distribution and concentration, which may further control the failure process of granite. The proposed method provides an efficient tool for studying the mechanical behaviors of heterogeneous rock and rock-like materials whose failure processes are strongly influenced by material heterogeneity.

Dissecting Cellular Heterogeneity Using Single-Cell RNA Sequencing

  • Choi, Yoon Ha;Kim, Jong Kyoung
    • Molecules and Cells
    • /
    • v.42 no.3
    • /
    • pp.189-199
    • /
    • 2019
  • Cell-to-cell variability in gene expression exists even in a homogeneous population of cells. Dissecting such cellular heterogeneity within a biological system is a prerequisite for understanding how a biological system is developed, homeostatically regulated, and responds to external perturbations. Single-cell RNA sequencing (scRNA-seq) allows the quantitative and unbiased characterization of cellular heterogeneity by providing genome-wide molecular profiles from tens of thousands of individual cells. A major question in analyzing scRNA-seq data is how to account for the observed cell-to-cell variability. In this review, we provide an overview of scRNA-seq protocols, computational approaches for dissecting cellular heterogeneity, and future directions of single-cell transcriptomic analysis.