As another important features in VEELS, the plasmon excitations (including the volume plasmon and surface/interfacial plasmon) are also utilized to identify different phases and multi compositions within materials. The microstructure and electronic structure evolution of silicon-rich oxide (SRO) films as a function of the annealing temperature are investigated using TEM and VEELS. The as-deposited SiO film is found to be a single phase with only single volume plasmon presents in VEEL spectrum and almost no interfacial plasmon is observed. After the annealing (Tanneal>400°C), it begins to decomposite into Si and SiO2 and the single phase changed into cluster/matrix nanocomposites where the interfacial plasmon appears. The Si duster size and its concentration increase as the annealing temperature increases. / Firstly, the applications of VEELS in investigating the electronic structures of ZnO nanowires with different diameter and surface shapes are demonstrated. Using the momentum transferred technique, one of the interband transitions with dipole-forbidden nature is identified. Several size dependent features are found on the interband transitions and plasmon oscillations of ZnO nanowires with small diameter and circular cross section, which are mainly due to the large surface to volume ratio and existence of Oxygen dangling bonds on those ZnO wires. / Further explorations on the electronic structure in the vicinity of band gap are carried out for the ZnO nanowires doped with different dopants (Co, Er, Yb) and different dopant concentrations. In order to obtain trustworthy information in the very low energy range of VEELS a narrow zero loss peak and elimination of Cerenkov effect and surface losses are necessary, which can be realized by incorporation of the gun monochromator in the TEM and taking spectrum at a momentum transfer slightly greater than zero. Band tail states (∼2-3.3 eV) are found to be generated in the ZnO nanowires after the ion implantation and their density of states increase with the ion fluence increases. The partially removal of those defect states by the Oxygen annealing is also observed in VEELS. On the other hand, interesting mid-gap state(s), which is dopant-sensitive (as it is only observed in the rare earth (Er and Yb) doped ZnO nanowires, but not in the Co-doped ones), does not show obvious change after the O annealing. The impact of these electronic structure changes on the material properties are also discussed. / In the end of the thesis, some of the practical limitations and contradictories on the energy resolution (DeltaE), spatial resolution (Delta x), and the momentum resolution (Deltaq) when carrying out the various VEELS study are summarized. The compromise made among these resolution limits is also discussed. / In this work, the important experimental parameters and appropriate data processing methods to generate trustworthy data are discussed. Based on that, three material systems, i.e., pure ZnO nanowires, doped ZnO nanowires, and Si/SiO/SiO2 composite films are investigated. Various information on the material microstructure/electronic structure is interpreted using the VEELS data. / The valence-electron energy-loss spectroscopy (VEELS) contains information on the electronic structures of materials, including the band gap the single-electron interband transitions and the plasmon oscillations. When operating in transmission electron microscope (TEM), the excellent spatial resolution enables the VEELS not only exploring the local electronic structures of individual low dimensional nanostructured materials, but also building up correlations between the electronic structure and microstructure. In addition, the capability in carrying out the momentum transfer dependent study in VEELS allows the investigation on the dispersion of plasmons and single electron excitations in the momentum space. The optically forbidden transitions, which are not allowed in conventional optical method, can also be excited at high momentum transfer values using VEELS. / Wang, Juan = 價電子能量損失譜在低維納米材料中的應用 / 王娟. / "September 2007." / Adviser: Li Quan. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1267. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 122-133). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract in English and Chinese. / School code: 1307. / Wang, Juan = Jia dian zi neng liang sun shi pu zai di wei na mi cai liao zhong de ying yong / Wang Juan.

Verb valency plays an important role in the description of behaviour of verbs and connects surface realisation of language with its semantics. Verb itself usually encodes several readings. Complementations of a verb help to identify correct reading of the verb. So far valency verb complementations are mostly studied from morphological and syntactical point of view. The purpose of this thesis is to examine possibilities of automatic identification of semantic preferences for valency complementations of verbs. The thesis discusses performance of system with different levels of available verb valency information in connection with cluster analysis. The thesis contains an evaluation section that compares available methods and their comparision.

Esta dissertação faz uma análise da abordagem do conceito de valência em livros didáticos de química geral para nível superior publicados nos EUA ao longo das primeiras décadas do século XX. Para tanto, foi feito um estudo de caso histórico a respeito do desenvolvimento do conceito de valência no final do século XIX e início do século XX, no qual se observou a influência de duas teorias sobre a combinação dos elementos: a teoria dos tipos e a teoria dos radicais. Outros pontos de destaque no caso histórico foram o envolvimento de vários cientistas, de vários países, e a relação do conceito de valência com os estudos sobre ligação, periodicidade e estrutura química, além de mudanças na nomenclatura e notação utilizadas. Num segundo momento, investigou-se a presença do conceito de valência nos livros didáticos selecionados, buscando uma análise qualitativa do material, tendo como referencial a análise textual discursiva. Os critérios de análise incluem: localização do assunto no livro, a nomenclatura e a notação utilizada, a definição fornecida e se ela está atrelada a alguma determinação histórica, matemática ou experimental, a presença do contexto histórico e do desenvolvimento do conceito ao longo dos anos, quais assuntos se apresentam correlacionados e quais os usos e aplicações dados à valência. Observou-se nos livros: a ausência de discussões mais aprofundadas a respeito da história da ciência; a grande importância dada pelos autores ao conceito de valência; a existência de um período de transição entre o conceito clássico e o eletrônico, ocorrido pouco tempo depois da construção do conceito eletrônico pelos cientistas; e uma mudança no enfoque da ciência química apresentada nos livros, os quais gradativamente deixam de reconhecer a existência de incertezas e lacunas no conhecimento químico. / This dissertation analyzes the approaches to the concept of valence in university-level general chemistry textbooks published in the USA throughout the first decades of the twentieth century. A historical case study about the development of the concept of valence in late nineteenth and early twentieth century is presented. It is shown that the concept of valence emerged from two theories on the combination of elements: the theory of types and the theory of radicals. Other important points from the historical case study were the involvement of several scientists from various countries and the relationship between the concept of valence and studies on chemical bonding, periodicity and chemical structure. Changes in nomenclature and notation for valence were also noted. In a second moment, the presence of the concept of valence in selected textbooks was investigated, by means of a qualitative analysis based on discursive textual analysis. The criteria for analysis included: location of the subject in the textbook; nomenclature and notation used; definition provided and whether it is linked to some historical, mathematical or experimental method of determination; presence of the historical context and the development of the concept over the years; which subjects are related to valence; and which uses and applications were given to valence in the textbooks. The main results of such analysis include: the absence of in-depth discussions about the history of science; the importance given to the concept of valence by the authors; the existence of a transition period from the classical to the electronic concept of valence, which occurred shortly after the construction of the electronic concept by scientists; and a shift in the focus of chemical science presented in the textbooks, which gradually fail to recognize the existence of uncertainties and gaps in chemical knowledge.

Nesta dissertação estudamos sistemas de spins em redes de baixa dimensionalidade e em temperatura nula, analisando suas transições de fases quânticas. Mais precisamente, estu- damos as propriedades do estado fundamental e as possíveis transições de fase do modelo de Heisenberg quântico antiferromagnético de spin-1/2, com interações entre os primeiros e segundos vizinhos, em diversas redes, e em particular na rede triangular, que é o foco de nosso estudo. Para a obtenção do estado fundamental aproximado, usamos um método variacional em que a rede é particionada num conjunto de plaquetas de sítios. O estado fundamental é escrito como um produto tensorial dos estados das plaquetas. Para a rede triangular, escolhemos um triângulo como uma plaqueta. Quatro fases foram encontra- das: a fase antiferromagnética de Néel, a colinear, a fase de Néel modificada e aquela que denominamos de ligação covalente ressonante. Obtivemos as energias e as magnetizações de subrede em função da razão entre as interações de primeiros e segundos vizinhos. En- tre as fases de Néel e a colinear, podemos observar a fase de ligação covalente ressonante caracterizada como um singleto quanto ao spin de cada plaqueta. / In this thesis we study spin systems in low-dimensional lattices at zero temperature, analyzing their quantum phase transitions. More precisely, we study the properties of the ground state and the possible phase transitions in the antiferromagnetic spin-1/2 quan- tum Heisenberg model with interaction between the first and second neighbors, in several lattices, and in particular in the triangular lattice, which is the focus of our study. To obtain the approximate ground state, we use a variational method in which the lattice is partitioned into a set of plates of sites. The ground state is written as a tensor product of the states of plates. For the triangular lattice, we choose a triangle as a plate. Four phases were found: the antiferromagnetic Néel phase, the collinear, the modified Néel phase and that we call resonating valence bond. We obtained the energy and the magnetization as a function of the ratio of the interactions between the first and second neighbor sites. Between the Néel and collinear phases, we can observe the spin resonating valence bond phase, characterized as a singlet with respect to the spin of each plate.

Worker motivation is relevant to public sector leaders because motivated workers are more efficient and productive, demonstrate positive behaviors, and are happier. Scholars have focused on differing approaches on how to incentivise public service employees using extrinsic or intrinsic incentives. The purpose of this qualitative phenomenological study was to explore the value and effectiveness of mission valence and other intrinsic means used to influence employee motivation and productivity. Using Festinger'€™s cognitive dissonance theory as a guide, a homogeneous group of key participants was interviewed with the intent of answering research questions. The research questions focused on mission valence deployment and on the incentive preferences of 11 purposely selected members of a public sector executive management team. The study incorporated the Giorgi method of data analysis. Following inductive coding procedures, the findings were synthesised into five themes. Findings suggested that mission valence has theoretical appeal to public service leaders, but the antecedent conditions, such as current mission statements have not been implemented. Thus, mission valence within PSGD is a conceptual intrinsic incentive at this point in time. Public service leaders prefer fluidity in crafting blended extrinsic and intrinsic incentive models that are unique to each employee. Consequently, opportunities exist for development of targeted skills development training to supplement existing leadership skills. This aligns with the implications for positive social change because the findings of this study yielded information concerning social, psychological, and motivational nuances and learning that may shape the next generation of public service leaders.

L'utilisation de différents niveaux de complexité dans les méthodes de la chimie théorique permet de discuter de la validité des modèles de reconstruction de la surface Si(100) et de créer des modèles de sous-oxydes. Notre étude ab-initio Hartree-Fock périodique est en faveur d'une reconstruction symétrique combinée à un arrangement anti-ferromagnétique 2x2 des spins des électrons des liaisons pendantes. Néanmoins la reconstruction asymétrique est quasi isoénergétique. Le traitement d'un large modèle moléculaire de sous-oxydes pseudo-périodique, permet de rendre compte des contraintes de la surface. L'importante relaxation trouvée dans cette étude est la combinaison d'une translation verticale et d'une rotation. Le réseau, la valence des espèces présentes peut influencer la cinétique de la relaxation. Le premier site d'oxydation est la liaison du dimère. Les atomes de silicium sont ensuite oxydés un par un.

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It has long been held that processing at the single word level during reading is automatic. However, research has recently begun to emerge that challenges this view. The literature surrounding the processing of emotion while recognizing printed words is limited, but some findings in the processing of emotion in faces suggest that negative stimuli (especially threat stimuli) promote quick and accurate processing. The purpose of the present experiments is to investigate whether negative emotionally-laden words are afforded priority processing in visual word recognition compared to positive emotionally-laden words. Two experiments are reported that manipulated the lexicality and valence of the target and distractor stimuli (Experiments 1 & 2), the validity of a spatial pre-cue (Experiments 1 & 2), and the presence of a distractor item (Experiment 2). Participants were asked to determine whether the target stimulus spelled a word or not. Response times on valid trials were faster compared to invalid trials, response times to negative emotionally-laden words were slower compared to positive emotionally-laden words, and the presence of a distractor item encouraged better focus on the target stimuli in the absence of any evidence that the valence of the distractor itself was processed. These results are consistent with the hypothesis that visual word recognition is not automatic given that processing benefited from the accurate direction of spatial attention. Furthermore, negative emotionally-laden words benefited equally compared to positive emotionally-laden words and therefore provide no evidence of automatic processing.

Early-latency theories of emotional processing state that at least coarse monitoring of the emotional valence (a pleasure-displeasure continuum) of facial expressions should be both rapid and highly automated (LeDoux, 1995; Russell, 1980). Research has largely substantiated early-latency differential processing of emotional versus non-emotional facial expressions; however, the effect of valence on early-latency processing of emotional facial expression remains unclear. In an effort to delineate the effects of valence on early-latency emotional facial expression processing, the current investigation compared ERP responses to positive (happy and surprise), neutral, and negative (afraid and sad) basic facial expression photographs as well as to positive (happy-surprise), neutral (afraid-surprise, happy-afraid, happy-sad, sad-surprise), and negative (sad-afraid) morph facial expression photographs during a valence-rating task. Morphing manipulations have been shown to decrease the familiarity of facial patterns and thus preclude any overlearned responses to specific facial codes. Accordingly, it was proposed that morph stimuli would disrupt more detailed emotional identification to reveal a valence response independent of a specific identifiable emotion (Balconi & Lucchiari, 2005; Schweinberger, Burton & Kelly, 1999). ERP results revealed early-latency differentiation between positive, neutral, and negative morph facial expressions approximately 108 milliseconds post-stimulus (P1) within the right electrode cluster; negative morph facial expressions continued to elicit significantly smaller ERP amplitudes than other valence categories approximately 164 milliseconds post-stimulus (N170). Consistent with previous imaging research on emotional facial expression processing, source localization revealed substantial dipole activation within regions of the mesolimbic dopamine system. Thus, these findings confirm rapid valence processing of facial expressions and suggest that negative valence processing may continue to modulate subsequent structural facial processing.

A large variety of diferrocenyl compounds bridged by an organic wire fragment in a generic form of -CH=CH-X-CH=CH- were first synthesized, in which the X unit is a functional group/atom. These compounds were studied by structural analysis, electrochemistry, intervalence NIR absorption and other spectroscopic techniques. The results indicated that metal-ligand redox matching is most essential in facilitating long-range electron transfer in the mixed-valence complexes. A series of doubly-bridged diferrocenyl compounds and wire-linked triferrocenes were also synthesized and studied. All doubly-bridged diferrocenyl compounds demonstrated nearly doubled electronic coupling in comparison to their singly-bridged analogues. Thus the use of parallel wires in such systems represents a facile approach to improve communication in molecular electronics. For triferrocenes linked by symmetric wires, the electronic interaction between the redox-active centers was rather dynamic when the bridging component was short or the charge was delocalized among the ligand and metal centers. For triferrocenes bridged by asymmetric wires, depending on the direction of the polar linking chain, the central ferrocene becomes a molecular switch, turning on or off the communication between the two end ferrocenes. Finally, to eliminate the metal-ligand orbital mixing problem, we also bound the wires with two redox-active styrylpyrrole termini, for which the molecules are purely organic. It was found that when the ð-conjugation was maintained, the oligomers were fully delocalized systems.