Browsing by Author "Wang, Zhe"

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    A Behavioral Genetic Study of the Links Between Working Memory and Aspects of Attention in Middle Childhood
    Wang, Zhe (Virginia Tech, 2010-11-05)
    The purpose of the current study was to explore the genetic and environmental association between working memory and different behavioral aspects of the attention network (i.e., executive attention, alerting attention, and orienting attention), using a twin design. Data were from 131 monozygotic (39% male) and 173 same-sex dizygotic (44% male) twins. Individual differences in working memory performance and behavioral measures of executive attention, alerting attention, and orienting attention were found to be moderately heritable. A modest nonshared environmental effect was found for all variables. Individual differences in working memory were significantly correlated with variability in executive and alerting attention, but not orienting attention. All of the association between working memory and executive as well as alerting attention was statistically mediated by genetic influences, indicating a common genetic mechanism or mechanisms underlying the links between working memory and certain behavioral indicators of attention.
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    Investigation of real-time coupled cluster methods for the efficient calculation of optical molecular properties in the time domain
    Wang, Zhe (Virginia Tech, 2023-10-10)
    Optical and spectroscopic molecular properties are key to characterizing the behavior of molecules interacting with an applied electromagnetic field of light. Response theory has been used for a long time to calculate such properties in the frequency domain. Real-time (RT) methods solve for the frequency-dependent properties in the time domain by explicitly propagating the time-dependent wave function. Various quantum chemical methods can be incorporated with the RT formalism, including Hartree-Fock, density functional theory, configurational interaction, coupled cluster, etc. Among these, coupled cluster (CC) methods provide high accuracy for systems with strong electron correlation, making RT-CC implementations intriguing. All applications of CC methods face a substantial challenge due to their high-order polynomial scaling. For RT-CC methods, two aspects may be explored to improve the efficiency, the numerical techniques regarding the RT propagation and the reduced-scaling methods regarding CC itself. In this work, we start with the exploration of the hardware used for the calculations and the numerical integration methods for propagating the wave function parameters. Firstly, a GPU-enabled Python implementation has been developed by conducting the tensor contractions on GPUs utilizing PyTorch, a machine learning package, that has similar syntax as NumPy for tensor operations. A speedup of a factor of 14 is obtained for the RT-CCSD/cc-pVDZ absorption spectrum calculation of the water tetramer. Furthermore, to optimize the performance on GPUs, single-precision arithmetic is added to the implementation to achieve an additional speedup of a factor of two. Lastly, a group of integrators for solving differential equations are introduced to the RT framework, including regular explicit integrators, adaptive integrators, and a mixed-step-size approach customized for strong-field simulations. The optimal choice of the integrator depends on the requiring accuracy, stability and efficiency. In addition to being highly accurate, CC methods are also systematically improvable and provide a hierarchy of accuracy. Based upon the RT-CCSD implementation, the coupled cluster singles, doubles and approximate triples (CC3) method, favorable for calculating frequency-dependent properties, is tailored to the RT framework for high excitation and approximate orbital relaxation. The calculation is tested on both CPUs and GPUs, with a significant speedup gained from GPUs for the water cluster test cases. To further expand the range of applications of our RT-CC implementation, dynamic polarizabilities, first hyperpolarizabilities, and the G' tensor are calculated from induced electric and magnetic dipole moments using finite-difference methods. A discussion has also been conducted to compare RT-CC3 with RT-CCSD, and time-dependent nonorthogonal orbital-optimized coupled cluster doubles (TDNOCCD) method. Additionally, electron dynamics, including the Rabi oscillation and exited state to excited state transitions, have also been explored utilizing the well-developed RT-CC framework.
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    A moderated transactional link between child behavioral problems and parenting: A longitudinal- and behavioral- genetic study
    Wang, Zhe (Virginia Tech, 2013-05-16)
    Parenting behaviors and a variety of behavioral problems in children covary. The current study first aimed to examine how and why parenting and child behavioral problems are linked in middle childhood. In particular, a longitudinal design (1364 children assessed from 54 months to 5th grade) was used to examine whether the developmental link between parenting and child behavioral problems were reciprocal. A twin design (131 pairs of monozygotic and 173 pairs of dizygotic twins assessed from 6 to 8 years of age on average) was used to examine the underlying genetic and nongenetic etiology of this link. In addition, using these two samples, the current study also aimed to examine whether parental attributes, including negative affect, executive function, and social cognitive factors, modulate the link between parenting and child behavioral problems. Results across these two studies suggested that parenting and child behavioral problems mutually influenced the development of each other over time, potentially through both evocative and passive gene-environment correlation processes and environmental transmissions. In addition, maternal dispositional anger modulated the effects of child behavioral problems on changes in maternal parenting quality over time. Finally, implications of the current study were also discussed.
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    Reading Self-Perceived Ability, Enjoyment and Achievement: A Genetically Informative Study of Their Reciprocal Links Over Time
    Malanchini, Margherita; Wang, Zhe; Voronin, Ivan; Schenker, Victoria J.; Plomin, Robert; Petrill, Stephen A.; Kovas, Yulia (2017-04)
    Extant literature has established a consistent association between aspects of reading motivation, such as enjoyment and self-perceived ability, and reading achievement, in that more motivated readers are generally more skilled readers. However, the developmental etiology of this relation is yet to be investigated. The present study explores the development of the motivation-achievement association and its genetic and environmental underpinnings. Applying cross-lagged design in a sample of 13,825 twins, we examined the relative contribution of genetic and environmental factors to the association between reading enjoyment and self-perceived ability and reading achievement. Children completed a reading comprehension task and self-reported their reading enjoyment and perceived ability twice in middle childhood: when they were 9-10 and 12 years old. Results showed a modest reciprocal association over time between reading motivation (enjoyment and perceived ability) and reading achievement. Reading motivation at age 9-10 statistically predicted the development of later achievement, and similarly, reading achievement at age 9-10 predicted the development of later motivation. This reciprocal association was observed beyond the stability of the variables and their contemporaneous correlation and was largely explained by genetic factors.
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    Study of VOCs release during drying of plantation-grown Pinus sylvestris and naturally grown Russian Pinus sylvestris
    Shen, Yulin; Zhang, Xiaotao; He, Qin; Wang, Xia; Wang, Zhe; Yang, Junli; Chen, Zhangjing; Yu, Jianfang; Duo, Huaqiong; Wang, Ximing (2020-05-12)
    A study was carried out to investigate the release of volatile organic compounds (VOCs) during drying of plantation Pinus sylvestris grown in China and naturally grown Pinus sylvestris from Russia. Our purpose was to provide basic information that can help wood processing mills set their VOCs emission limits and control the exhaust gas within such limits. During conventional drying of the plantation Pinus sylvestris, a total of 22 chemical compounds were detected in the exhaust gas: 9 aldehydes including formaldehyde, 8 terpenes including α-pinene, and 3 additional compounds including alkane, and propylbenzene. The VOCs released during both conventional drying and high-temperature drying were the same. However, large amounts of benzene were detected during the high-temperature drying process. During conventional drying of the Russian Pinus sylvestris material, a total of 17 chemical compounds were detected: 7 aldehydes including formaldehyde, 6 terpenes including α-pinene, and 2 additional compounds. The VOCs released during conventional drying and high-temperature drying were the same. However, large amounts of camphene were detected during high-temperature drying. For plantation Pinus sylvestris, the release of VOCs primarily took place at the later stage of conventional drying, and at the earlier stage of high-temperature drying. For Russian Pinus sylvestris, the amount and the release rate of VOCs during conventional drying were extremely low, and the VOCs during high-temperature drying were primarily released at the later stage. The total amount of VOCs released during drying was much higher from the plantation Pinus sylvestris than from Russian Pinus sylvestris material.