• Title, Summary, Keyword: growth mixture modeling

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Types of Changes in Overt Aggression and Their Predictors in Early Adolescents : Growth Mixture Modeling (초기 청소년의 외현적 공격성 변화유형과 예측요인 : 성장혼합모형의 적용)

  • Seo, Mi-Jung;Kim, Kyong-Yeon
    • Korean Journal of Child Studies
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    • v.31 no.3
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    • pp.83-97
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    • 2010
  • Growth mixture modeling was used to identify types of changes in overt aggression from Grades 4 to 7 among a sample from the Korean Youth Panel Survey. Three discrete patterns were found to adequately explain changes of overt aggression in both boys and girls : Persistent intermediate aggression; Increasing aggression; and Decreasing aggression. Most boys (93%) fell into the Persistent intermediate aggression group and 49% of girls were found to fall into the Increasing aggression group. This suggests that prevention programs should recognize that girls are at risk of increasing aggression in their early adolescence. Multinomial logistic regression analysis shows that self-control, child abuse, peer support, and involvement with deviant peers at Grades 4 were all strongly associated with trajectory class membership. These associations did not differ by gender. These findings suggest that prevention programs should focus on the multiple risk factors of both boys and girls.

A Short-term Longitudinal Study on Types and Predictors of Trajectories of Adaptation to Child Care Among Infants and Toddlers: Using Growth Mixture Modeling and Latent Classes Analysis (영아의 어린이집 적응 추이의 유형 및 예측 요인에 대한 단기종단연구: 성장혼합모형과 잠재계층분석을 활용하여)

  • Shin, Nary;Jo, Woori
    • Korean Journal of Childcare and Education
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    • v.16 no.1
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    • pp.115-143
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    • 2020
  • Objective: The purpose of this study was to examine underlying types of developmental trajectories of adaptation to child care among infants and toddlers. This study also aimed to identify latent classes in their child care adaptation types in order to find predictors that account for individual differences. Methods: Participants were 420 mothers of infants and toddlers and 123 teachers. The levels of child care adaptation of participating infants and toddlers were rated monthly from early April to June, 2019. The collected data were analyzed using growth mixture modeling, latent class analysis and multinominal logistic analysis. Results: The results of growth trajectories of child care adaptation showed there were two to four latent groups by dimension of child care adaptation. Also, the groups of individual dimensions of child care adaptation were classified into three latent classes, which were 'complying and positive group', 'negative group', and 'individualized group. Multinominal logistic analysis revealed that children's age, gender, and temperament differentiated the three latent classes of adaptation to child care. Conclusion/Implications: The results show individual characteristics that infants and toddlers possess should be prudently considered in order for successful adaptation to child care.

Clustering Asian and North African Countries According to Trend of Colon and Rectum Cancer Mortality Rates: an Application of Growth Mixture Models

  • Zayeri, Farid;Sheidaei, Ali;Mansouri, Anita
    • Asian Pacific Journal of Cancer Prevention
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    • v.16 no.9
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    • pp.4115-4121
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    • 2015
  • Background: Colorectal cancer is the second most common cause of cancer death with half a million deaths per year. Incidence and mortality rates have demonstrated notable changes in Asian and African countries during the last few decades. In this study, we first aimed to determine the trend of colorectal cancer mortality rate in each Institute for Health Metrics and Evaluation (IHME) region, and then re-classify them to find more homogenous classes. Materials and Methods: Our study population consisted of 52 countries of Asia and North Africa in six IHME pre-defined regions for both genders and age-standardized groups from 1990 to 2010.We first applied simple growth models for pre-defined IHME regions to estimate the intercepts and slopes of mortality rate trends. Then, we clustered the 52 described countries using the latent growth mixture modeling approach for classifying them based on their colorectal mortality rates over time. Results: Statistical analysis revealed that males and people in high income Asia pacific and East Asia countries were at greater risk of death from colon and rectum cancer. In addition, South Asia region had the lowest rates of mortality due to this cancer. Simple growth modeling showed that majority of IHME regions had decreasing trend in mortality rate of colorectal cancer. However, re-classification these countries based on their mortality trend using the latent growth mixture model resulted in more homogeneous classes according to colorectal mortality trend. Conclusions: In general, our statistical analyses showed that most Asian and North African countries had upward trend in their colorectal cancer mortality. We therefore urge the health policy makers in these countries to evaluate the causes of growing mortality and study the interventional programs of successful countries in managing the consequences of this cancer.

Multi-Scale Heterogeneous Fracture Modeling of Asphalt Mixture Using Microfabric Distinct Element Approach

  • Kim Hyun-Wook;Buttler William G.
    • International Journal of Highway Engineering
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    • v.8 no.1
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    • pp.139-152
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    • 2006
  • Many experimental and numerical approaches have been developed to evaluate paving materials and to predict pavement response and distress. Micromechanical simulation modeling is a technology that can reduce the number of physical tests required in material formulation and design and that can provide more details, e.g., the internal stress and strain state, and energy evolution and dissipation in simulated specimens with realistic microstructural features. A clustered distinct element modeling (DEM) approach was implemented In the two-dimensional particle flow software package (PFC-2D) to study the complex behavior observed in asphalt mixture fracturing. The relationship between continuous and discontinuous material properties was defined based on the potential energy approach. The theoretical relationship was validated with the uniform axial compression and cantilever beam model using two-dimensional plane strain and plane stress models. A bilinear cohesive displacement-softening model was implemented as an intrinsic interface and applied for both homogeneous and heterogeneous fracture modeling in order to simulate behavior in the fracture process zone and to simulate crack propagation. A disk-shaped compact tension test (DC(T)) with heterogeneous microstructure was simulated and compared with the experimental fracture test results to study Mode I fracture. The realistic arbitrary crack propagation including crack deflection, microcracking, crack face sliding, crack branching, and crack tip blunting could be represented in the fracture models. This micromechanical modeling approach represents the early developmental stages towards a 'virtual asphalt laboratory,' where simulations of laboratory tests and eventually field response and distress predictions can be made to enhance our understanding of pavement distress mechanisms, such its thermal fracture, reflective cracking, and fatigue crack growth.

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Exploring Latent Trajectory Classes of Change in Depression Measured Using CES-D (CES-D로 측정한 우울증상 변화궤적의 잠재계층 탐색 -GMM을 활용한 한국복지패널 데이터의 재분석-)

  • Hoe, Maanse
    • Korean Journal of Social Welfare
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    • v.66 no.1
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    • pp.307-331
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    • 2014
  • The purpose of the present study was to explore latent trajectory classes in the longitudinal change of depression measured using CES-D. The study data was extracted from the Korea Welfare Panel Study Data collected from 2006 to 2010. It consisted of 8,900 adults with aged over 19. Growth Mixture Modeling(GMM) was used to explore possible latent trajectory classes in the change of depression over time. The major findings of the present study were as follows. First, there were five latent trajectory classes in the longitudinal change of depression. Second, there were 4 latent trajectory classes of depression for people in a non-poverty group, while there were 3 latent trajectory classes of depression for people in a poverty group. These findings lead to three conclusions. First, 12.1% of the sample shows that their depression level increases over time. Second, the previous research findings of decreased depression over time might be caused by the combination of two latent trajectory classes(a low level depression sustain group and a depression decrease group). Lastly, the latent trajectory classes in the longitudinal change of depression, which are found in the present study, might be caused by interactions among depression, age, and poverty status.

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Trajectories of Mothers' Daily Life Stress and its Association with Early Adolescents' Perceived Neglecting Attitude and Academic Achievements in Multicultural Families: Growth Mixture Modeling (다문화 가정 어머니의 일상생활스트레스 변화 양상에 따른 방임 및 자녀의 학업성취 차이: 성장혼합모형 적용을 중심으로)

  • Yun, Hongju;Choi, Hyo-Sik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.12
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    • pp.348-356
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    • 2019
  • The purpose of this study was to identify latent classes in changes of mothers' daily life stress over six years from multicultural families and to test its relationship with early adolescents' perceived neglecting parental attitudes and their academic achievements. For achieving this purpose, as the study sample 1,039 students were gathered from the 4th grade of elementary school to 3rd grade of middle school, using Growth Mixture Modeling, Multiple Group Analysis, and One-way ANOVA. The results were as follows. First, latent classes of mothers' daily life stress were categorized into three types: high-stable trajectory, moderate-changing trajectory, and low-changing trajectory. Second, these three types showed different characteristics in early adolescents' perceived neglecting parental attitudes and academic achievements. Third, early adolescents' perceived neglecting parental attitude were not significant determinants of the latent classes while academic achievements were. The findings of this study may provide a framework for understanding the relationships among mothers' daily life stress and early adolescents' perceived neglecting parental attitudes and their academic achievements in multicultural families and practical implications for providing social support to overcome daily life stress of mothers in multicultural families.

Modeling the compressive strength of cement mortar nano-composites

  • Alavi, Reza;Mirzadeh, Hamed
    • Computers and Concrete
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    • v.10 no.1
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    • pp.49-57
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    • 2012
  • Nano-particle-reinforced cement mortars have been the basis of research in recent years and a significant growth is expected in the future. Therefore, optimization and quantification of the effect of processing parameters and mixture ingredients on the performance of cement mortars are quite important. In this work, the effects of nano-silica, water/binder ratio, sand/binder ratio and aging (curing) time on the compressive strength of cement mortars were modeled by means of artificial neural network (ANN). The developed model can be conveniently used as a rough estimate at the stage of mix design in order to produce high quality and economical cement mortars.

Holographic Polymer-Dispersed Liquid Crystals and Polymeric Photonic Crystals Formed by Holographic Photolithography

  • Kyu Thein;Meng Scott;Duran Hatice;Nanjundiah Kumar;Yandek Gregory R.
    • Macromolecular Research
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    • v.14 no.2
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    • pp.155-165
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    • 2006
  • The present article describes the experimental and theoretical observations on the formation of holographic, polymer-dispersed, liquid crystals and electrically switchable, photonic crystals. A phase diagram of the starting mixture of nematic liquid crystal and photo-reactive triacrylate monomer was established by means of differential scanning calorimetry (DSC) and cloud point measurement. Photolithographic patterns were imprinted on the starting mixture of LC/triacrylate via multi-beam interference. A similar study was extended to a dendrimer/photocurative mixture as well as to a single component system (tetra-acrylate). Theoretical modeling and numerical simulation were carried out based on the combination of Flory-Huggins free energy of mixing and Maier-Saupe free energy of nematic ordering. The combined free energy densities were incorporated into the time-dependent Ginzburg-Landau (Model C) equations coupled with the photopolymerization rate equation to elucidate the spatio-temporal structure growth. The 2-D photonic structures thus simulated were consistent with the experimental observations. Furthermore, 3-D simulation was performed to guide the fabrication of assorted photonic crystals under various beam-geometries. Electro-optical performance such as diffraction efficiency was evaluated during the pattern photopolymerization process and also as a function of driving voltage.

Raman Spectroscopy and Molecular Modeling Study on the CH4 and SF6 Mixture Gas Hydrate Growth Behavior (라만 분광학과 분자모델링을 이용한 메탄 및 육불화황 혼합 가스 하이드레이트 성장 거동 연구)

  • Lim, Jun-Heok;Lee, Ju Dong;Park, Sung Soo;Eom, Ki Heon;Won, Yong Sun
    • Clean Technology
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    • v.19 no.4
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    • pp.476-480
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    • 2013
  • The growth behavior of $CH_4$ and $SF_6$ mixture gas hydrate has been investigated by a combined approach of Raman spectroscopy and molecular modeling. Raman spectroscopy results presented that when $CH_4$ is used only, $CH_4$ guest molecule is inserted first into the large cavity of the host structure built by $H_2O$ molecules and then into the small cavity to stabilize the whole gas hydrate structure. In the other hand, when $SF_6$ is mixed together, $SF_6$ is favored over (or competing with) $CH_4$ in being inserted into the large cavity and the small cavity still prefers $CH_4$ insertion. The calculations of binding energies clearly supported this. While $SF_6$ has a binding energy of -26.9 kcal/mol a little lower than -24.2 kcal/mol of $CH_4$ in the large cavity, $SF_6$ and $CH_4$ has 1.2 kcal/mol and -22.0 kcal/mol, respectively, in the small cavity. It indicates that the sizable $SF_6$ is not preferred in the small cavity but has a relative energetic advantage over $CH_4$ in the large cavity.

Numerical Modeling of Nano-powder Synthesis in a Radio-Frequency Inductively Coupled Plasma Torch

  • Hur, Min Young;Lee, Donggeun;Yang, Sangsun;Lee, Hae June
    • Applied Science and Convergence Technology
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    • v.27 no.1
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    • pp.14-18
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    • 2018
  • In order to understand the mechanism of the synthesis of particles using a plasma torch, it is necessary to understand the reaction mechanisms using a computer simulation. In this study, we have developed a simulation method to combine the Lagrangian scheme to follow microparticles and a nodal method to treat nanoparticles categorized with different particle sizes. The Lagrangian scheme includes the Coulomb force which affects the dynamics of larger particles. In contrast, the nodal method is adequate for the nanoparticles because the charge effect is negligible for nanoparticles but the number of nanoparticles is much larger than that of microparticles. This method is helpful to understand the dynamics and growth mechanism of micro- and nano-powder mixture observed in the experiment.