Adjacency matrix formulation of energy flow in dendrimeric polymers

Dendrimers are synthetic, highly branched polymers with an unusually high density of chromophores. As a result of their extremely high absorption cross-sections for visible light, they represent some of the most promising new materials for energy harvesting. Although the signature of the bonding structure in dendrimers is an essentially fractal geometry, the three-dimensional molecular folding of most higher generation materials results in a chromophore layout that is more obviously akin to concentric spherical shells. The number of chromophores in each shell is a simple function of the distance from the central core. The energy of throughput optical radiation, on capture by any of the chromophores, passes by a multi-step but highly efficient process to the photoactive core. Modeling this crucial migration process presents a number of challenges. It is far from a simple diffusive random walk; each step is subject to an intricate interplay of geometric and spectroscopic features. In this report, the first results of a new approach to the theory is described, developed and adapted from an adjacency matrix formulation. It is shown how this method offers not only kinetic information but also insights into the typical number of steps and the patterns of internal energy flow

Zhōng Jiè Yǔ Yǔ Yán Xué Duō Wéi Yán Jiū [Multidimensional Studies in Interlanguage Linguistics]

Since the term “interlanguage” was coined by Larry Selinker in 1972 to refer to the systematic knowledge of a second language (L2) that is independent of both a learner’s first or native language (L1) and the target language (TL) (Ellis, 2008), it has received a tremendous amount of attention in the second language acquisition (SLA) research literature. After more than 40 years of study, researchers have reached the consensus that interlanguage is a linguistic system in its own right (Selinker, 2014) such that the interlanguage system has the basic characteristics of natural language and its intrinsic regularity can be identified at all linguistic levels, such as phonology, morphology, syntax, semantics, and pragmatics. In line with new developments in interlanguage research, Professor Lianrui Yang has recently identified a new interlanguage construct, interlanguage linguistics, in this new monograph that is currently only available in Chinese. All of the various strands of interlanguage research are integrated into this new construct, suggesting the formation of this new discipline. Focusing specifically on interlanguage development, the 32 chapters that constitute this new book offer fundamental information about both traditional as well as emerging topics in interlanguage research. The book highlights the interdisciplinary nature of the field in its selection of themes and chapters. Its chapters touch on topics ranging from theoretical constructs to multidimensional studies of interlanguage development. For this review, the chapters have been grouped and organized under five main themes: (1) Interlanguage Phonology (Chapters 1-7), (2) Interlanguage Morphology and Syntax (Chapters 8-11, 14-15, 17-20), (3) Interlanguage Pragmatics (Chapters 12-13, 16), (4) Interlanguage Vocabulary (Chapters 21-28), and (5) Interlanguage Linguistics (Chapters 29-32). These subdivisions offer general and essential information regarding the status of research on interlanguage phonology, syntax, pragmatics, lexicon, etc. The general contents of each of these major thematic areas will be described next, followed by brief chapter-by-chapter summaries as well

Development of Algorithms for the Direct Multi-Configuration Self- Consistent Field (MCSCF) Method

In order to improve the performance of the current parallelized direct multi-configuration self-consistent field (MCSCF) implementations of the program package Gaussian [42], consisting of the complete active space (CAS) SCF method [43] and the restricted active space (RAS) SCF method [44], this thesis introduces a matrix multiplication scheme as part of the CI eigenvalue evaluation of these methods. Thus highly optimized linear algebra routines, which are able to use data in a sequential and predictable way, can be used in our method, resulting in a much better performance overall than the current methods. The side effect of this matrix multiplication scheme is that it requires some extra memory to store the additional intermediate matrices. Several chemical systems are used to demonstrate that the new CAS and RAS methods are faster than the current CAS and RAS methods respectively. This thesis is structured into four chapters. Chapter One is the general introduction, which describes the background of the CASSCF/RASSCF methods. Then the efficiency of the current CASSCF/RASSCF code is discussed, which serves as the motivation for this thesis, followed by a brief introduction to our method. Chapter Two describes applying the matrix multiplication scheme to accelerate the current direct CASSCF method, by reorganizing the summation order in the equation that generates non-zero Hamiltonian matrix elements. It is demonstrated that the new method can perform much faster than the current CASSCF method by carrying out single point energy calculations on pyracylene and pyrene molecules, and geometry optimization calculations on anthracene+ / phenanthrene+ molecules. However, in the RASSCF method, because an arbitrary number of doubly-occupied or unoccupied orbitals are introduced into the CASSCF reference space, many new orbital integral cases arise. Some cases are suitable for the matrix multiplication scheme, while others are not. Chapter Three applies the scheme to those suitable integral cases that are also the most time-consuming cases for the RASSCF calculation. The coronene molecule - with different sizes of orbital active space - has been used to demonstrate that the new RASSCF method can perform significantly faster than the current Gaussian method. Chapter Four describes an attempt to modify the other integral cases, based on a review of the method developed by Saunders and Van Lenthe [95]. Calculations on coronene molecule are used again to test whether this implementation can further improve the performance of the RASSCF method developed in Chapter Three

Composition of 'fast-slow' traits drives avian community stability over North America

1. Rapid biodiversity loss has triggered decades of research on the relationships between biodiversity and community stability. Recent studies highlighted the importance of species traits for understanding biodiversity-stability relationships. The species with high growth rates ('fast' species) are expected to be less resistant to environmental stress but recover faster if disturbed; in contrast, the species with slow growth rates ('slow' species) can be more resistant but recover more slowly if disturbed. Such a 'fast-slow' trait continuum provides a new perspective for understanding community stability, but its validity has mainly been examined in plant communities. Here, we investigate how 'fast-slow' trait composition, together with species richness and environmental factors, regulate avian community stability at a continental scale. 2. We used bird population records from the North American Breeding Bird Survey during 1988-2017 and defined avian community stability as the temporal invariability of total community biomass. We calculated species richness and the community-weighted mean (CWM) and functional diversity (FD) of four key life-history traits, including body size, nestling period (i.e. period of egg incubation and young bird fledging), life span and clutch size (i.e. annual total number of eggs). Environmental factors included temperature, precipitation and leaf area index (LAI). 3. Our analyses showed that avian community stability was mainly driven by the CWM of the 'fast-slow' trait. Communities dominated by 'fast' species (i.e. species with small body size, short nestling period and life span and large clutch size) were more stable than those dominated by 'slow' species (i.e. species with large body size, long nestling period and life span and small clutch size). Species richness and the FD of the 'fast-slow' trait explained much smaller proportions of variation in avian community stability. Temperature had direct positive effects on avian community stability, while precipitation and leaf area index affected community stability indirectly by influencing species richness and trait composition. 4. Our study demonstrates that composition of 'fast-slow' traits is the major biotic driver of avian community stability over North America. Temperature is the most important abiotic factor, but its effect is weaker than that of the 'fast-slow' trait. An integrated framework combining 'fast-slow' trait composition and temperature is needed to understand the response of avian communities in a changing environment.Peer reviewe

Topic prominence in Chinese EFL learners’ interlanguage

The present study aims to investigate the general characteristics of topic-prominent typological interlanguage development of Chinese learners of English in terms of acquiring subject-prominent English structures from a discourse perspec- tive. Topic structures mainly appear in Chinese discourse in the form of topic chains (Wang, 2002; 2004). The research target are the topic chain, which is the main topic-prominent structure in Chinese discourse, and zero anaphora, which is the most common topic anaphora in the topic chain. Two important findings emerged from the present study. First, the characteristics of Chinese topic chains are transferrable to the interlanguage of Chinese EFL learners, thus resulting in overgeneralization of the zero anaphora. Second, the interlanguage discourse of Chinese EFL learners reflects a change of the second language acquisition process from topic-prominence to subject-prominence, thus lending support to the dis- course transfer hypothesis.411091256Studies in Second Language Learning and Teachin