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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Age Related Changes In Recognition Memory For Emotional Stimuli

Kilic, Asli 01 July 2007 (has links) (PDF)
Recognition memory - a type of episodic memory in long term memory - is known in the literature to be affected by emotion, aging and the modality of the presented stimuli. The major aim of this study was to investigate whether emotional stimuli enhances recognition memory. Another goal was to observe whether modality and aging effects are present and differentiable in a non-Western subject sample. In literature, emotion studies were based on mainly two dimensions of emotions: valence and arousal. However, the contribution of these two dimensions to the enhancement of recognition memory still needs clarification. The present study investigated specifically the effect of valence on recognition memory. Moreover, the experimental manipulations of this study allowed observing the effect of valence on recognition memory due to normal aging. Since modality of the presented stimuli is a major confounding factor on recognition, separate experiments involving visual and verbal stimuli were designed. Pictures and words were selected on the basis of valence and arousal ratings. The stimulus set of the visual recognition memory task consisted of the pictures selected from the International Affective Picture System (IAPS) (Lang et al., 2005). The stimulus set of the verbal recognition memory task was constructed from partially standardized material for affective norms of Turkish emotional words (METU TEW), which was developed as a part of this study. METU TEW allowed selecting words with positive, neutral and negative valence while controlling arousal. The results replicated two findings reported in the literature: (1) younger adults recognized more accurately than older adults / (2) recognition memory was enhanced for visual items regardless of age and valence. Interestingly, this study revealed that recognition memory was not enhanced for emotional stimuli varying only on the valence dimension. More specifically, there was a decline in recognition memory for positive items and no change was observed for negative items, regardless of age. Further analysis also revealed that there may be differential effects of abstractness and concreteness on verbal recognition memory in aging.
92

Electronic localization versus delocalization: a dimetal approach

Liu, Chun Yuan 16 August 2006 (has links)
A series of dimolybdenum compounds having a Mo2 4+ core coordinated by various ligands, including formamidinate (e.g. DAniF = N, NN-di-p-ansisylformamidinate ), acetate and/or acetonitrile molecules, have been synthesized as building blocks for the construction of Mo2-containing supramolecular arrays. Compound Mo2(DAniF)3(O2CCH3) was specifically designed for the preparation of dimolybdenum pairs, whereas the others meet the needs of Mo2 4+ units for different geometry settings. Compounds described by a general formula [Mo2]L[Mo2], where [Mo2] = [Mo2(DAniF)3]+, have two dimetal units electronically coupled by the central unit L , which consequently engender significant impact on the redox property and electronic structure of the molecule. It is found that in the weakly coupled complex system, [Mo2]M(OCH3)4[Mo2] (M = Zn and Co), the mixed-valence complexes present asymmetric molecular structures with two distinct [Mo2] units corresponding to be a bond order 4.0 (F2B4*2) and 3.5 (F2B4*1), respectively. EPR and magnetic susceptibility measurements for the doubly oxidized species show that there is no significant antifferromagnetic spin coupling. Electron delocalization occurs in the complex system where a N, N'-dimethyloxamidate binds two [Mo2] units within two fused six-membered rings. In this case, the mixed-valence complex has a symmetric molecular structure, implying that the odd electron is fully delocalized over two [Mo2]units. Strong metal-metal interaction is also evidenced by intervalence charge transfer of the mixed-valence species and the diamanetism of the doubly oxidized complex. Remarkably, two isomers varying in linkage conformation, namely, alpha and beta, have been isolated as diaryloxamidate ligands are used as the linker. Studies on the neutral and the oxidized compounds of the two isomers by employing various techniques consistently show that in the alpha form intramolecular electron transfer is blocked , while in the beta form, the electrons are delocalized over the two [Mo2] units. Thus, the mixed-valence complexes of the two isomers are appropriately described by alpha-[Mo2]0(oxamidate)[Mo2]1+ and beta- [Mo2]0.5+(oxamidate)[Mo2]0.5+ respectively.
93

Preparation of C60-donor systems displaying original properties

Figueira-Duarte, Teresa Marina Gary, Anne-Marie. Nierengarten, Jean-François. January 2007 (has links) (PDF)
Thèse doctorat : Chimie Organique Moléculaire et Chimie des Matériaux : Strasbourg 1 : 2006. / Thèse soutenue sur un ensemble de travaux. Titre provenant de l'écran-titre. Notes bibliogr.
94

Effets de valence dans les composés base manganèse isotypes de HfFe6Ge6 ou ses variantes Matériaux magnétoréfrigérants /

Ihou-Mouko, Hilaire Malaman, Bernard. January 2006 (has links) (PDF)
Thèse doctorat : Physique et Chimie de la Matière condensée : Nancy 1 : 2006. / Titre provenant de l'écran-titre.
95

Perceptual Responses to High-Intensity Interval Training in Overweight and Sedentary Individuals

Martinez, Nicholas 01 January 2013 (has links)
Contemporary aerobic exercise guidelines comprised of continuous durations and higher intensities have been shown to be effective in the prevention and treatment of risk factors associated with obesity and cardiovascular disease (CVD). However, high-intensity interval training (HIIT) has recently been examined as an advantageous protocol for producing more favorable physiological and psychological benefits in comparison to traditional continuous exercise guidelines. The dual-mode model, which examines the dose response relationship between exercise intensity and affective valence, would suggest that exercise performed well above the ventilatory threshold (VT) in the severe domain should result in negative affective valence. Numerous investigations have confirmed the reliability of the dual-mode models ability to predict compromised affective valence in the presence of heavy to severe exercise intensities, but only a small amount of research has examined the efficacy of the dual-mode model during HIIT. However, no research to date has combined HIIT with the dual-mode model's efficacy to predict affective valence in target populations challenged by exercise adherence, such as overweight and sedentary individuals. Therefore, the purpose of this study was to examine the dual-mode model's reliability to predict affective valence for overweight and sedentary individuals performing HIIT. A total of 14 participants (7 male, 7 female) with a mean age of 23 ±; 4 (range = 18-33) and mean BMI of 29 ±; 3 (range = 25-33) completed the study. Each participant completed a ramp maximal exercise test to determine VT and peak power data, which allowed for specific exercise intensities of delta (DT) to be prescribed for experimental trials. Participants were low to moderate risk. The four experimental conditions were all matched for total work: 1) continuous at 10% DT (Continuous-Heavy - CH), 2) 24 times 30-second intervals at 60% DT (Interval-Severe 30 Second - IS30), 3) 12 times 60-second intervals at 60% DT (Interval-Severe 60 Second - IS60), 4) 6 times 120-second intervals at 60% DT (Interval-Severe 120 Second - IS120). The continuous exercise condition was 20 minutes in duration, whereas all interval exercise conditions were 24 minutes in duration. Results indicated that in-task perceptual responses defined, as affective valence and perceived enjoyment were overall more favorable during IS30 and IS60 in comparison to CH and IS120. IS30 was the only experimental condition in which affective valence did not decline significantly (p > 0.05). Ratings of perceived enjoyment were greater at all measured time points during IS60 (p < 0.05) in comparison to CH. The findings of this study suggest that HIIT comprised of 30 and or 60 seconds help to facilitate more favorable perceptual responses of affective valence and perceived enjoyment than continuous exercise and intervals of longer than 60 seconds duration.
96

Effect of varied music applications in cycle ergometry

Lim, Harry January 2012 (has links)
The aim of this research programme was to investigate the effects of different music applications: The differentiated exposure of music and the synchronous application of music. In Study 1, participants completed a series of 10-km cycling time trials under four single-blinded conditions: No-music control, music 0-10 km (M1), music 0-5 km (M2), and music 5-10 km (M3). The largest performance gains were noticed under M1, followed by M3, when compared to control, while the most positive psychological response was observed only in M3. Study 2 further examined the notion of differentiated music exposure by incorporating both quantitative and qualitative modes of inquiry. In addition, participants were given foreknowledge of the experimental conditions. Although no performance gains were found across conditions, M3 significantly reduced perceived exertion and prevented affective decline. Qualitative findings suggest that prolonged exposure to music may have negative psychological and psychophysical consequences. The last study contrasted the effects of synchronous and asynchronous application of music in a 6-min submaximal cycling task. Synchronous music was more effective than asynchronous music in terms of reducing perceptions of exertion and increasing subjective arousal. Although no changes in oxygen uptake were found across conditions, auditory-motor synchronisation appeared to reduce heart rate. The contribution of this thesis is twofold. Firstly, the provision of music in the latter stages of a task appears to have significant psychological and psychophysical benefits when compared against constant music exposure. Secondly, more positive effects, in terms of perceived exertion and subjective arousal, are observed when music is applied synchronously compared to asynchronously; this suggests a need for a separate conceptual framework for the application of synchronous music.
97

Synthesis, Characterization, and Mixed-Valence Studies of Conformationally Constrained Bisferrocenyl Complexes for the Study of Through-Space S***π; Interactions

Meyer, Gordon Joel January 2014 (has links)
A series of conformationally constrained 2,6-bisferrocenylphenyl thioethers were synthesized via Suzuki-Miyaura cross coupling reactions. Structural information was obtained using X-ray crystallography and dynamic ¹H NMR spectroscopic studies, showing highly constrained m-terphenyl systems. Interaction of the ferrocene moieties through space mediated by the sulfur were studied by ultra-violet photoelectron spectroscopy (UPS), cyclic voltammetry, differential pulse voltammetry, UV-Vis-NIR spectroscopy and DFT computations. Electrochemical results show two, fully reversible 1e⁻ redox processes for the ferrocenes where the separation of peaks is affected by both solvent and supporting electrolyte, suggesting significant electrostatic interaction which is further confirmed in the gas phase by UPS studies. To determine if these interactions could be observed at greater distances, extended m-terphenyl complexes were shown in which 2-sulfur and 3-aromatic moieties were synthesized using a developed selective Suzuki-Miyaura monocoupling procedure in good yields. In these systems, interaction was not observed by electrochemistry or UPS. This suggests the distance between redox centers (~16 Å) is too great for electrostatic interaction, even though there is enhanced interactions observed in the truncated systems. Two new bisferrocenylphenylsulfoxides were also synthesized and studied to determine the effect of the polar sulfoxide bond on through space interaction between the ferrocene moieties. The electronic and redox properties of these compounds were studied by ultra-violet photoelectron spectroscopy, cyclic voltammetry, differential pulse voltammetry, and DFT computations. Electrochemical results for 2,6-bis(ferrocenyl) thioanisole S-oxide show two, fully reversible one electron redox processes. The initial oxidation shows a 62 mV negative shift compared to the sulfide analog 2,6-bis(ferrocenyl)thioanisole, and an increased peak separation for the oxidations of 160 mV. No peak separation is observed in the extended sulfoxide system. No intervalence charge transfer band was observed in the truncated sulfoxide complex by monitoring the UV-Vis/NIR spectroscopy of the mixed valence complex, ruling out electronic communication. Thus, the through space electrostatic interactions of the sulfoxide causes the non-equivalent ferrocenes in the truncated system to have different oxidation potentials. Synthesis was developed towards the synthesis of 1,8-bisferrocenyl-9-(alkylthio) anthracene complexes. It was observed that due to steric congestion at the C9 position of the anthracene scaffold, standard thionation reactions did not proceed as expected. Instead, the reaction of 1,8-dibromo-9-anthrone with Lawesson reagent afforded the intramolecular nucleophilic aromatic substitution cyclization product in quantitative yields. The reaction of the same anthrone under studied dithioketal formation conditions led to sulfur-rearrangement, giving the undesired 1,8-bisferrocenyl-10-(ethylthio)anthracene derivative, as confirmed by X-ray crystallography. Attempted Newman-Kwart rearrangement of 1, 8-dibromoanthracen-9-yl) dimethylcarbamothioate afforded no significant observed product formation, and decomposition of starting materials when heated for extended times. 1,8-bisferrocenyl-9-(methoxy)anthracene was synthesized and structurally characterized by dynamic X-ray crystallography to confirm connectivity. Electrochemical experiments show 2 reversible redox processes separated by 115 mV. Chemical oxidation experiments show unexpected, strong electronic coupling in the mixed valence complex. This coupling was characterized by near-IR absorption at 941 nm, indicating intervalence charge transfer (IVCT). Single electron reduction of 1,8-bisferrocenyl-9-(methoxy)anthracene, followed by quenching with various electrophiles afforded an inseparable mixture of products, one of which was identified by mass spectrometry as the desired 1,8-bisferrocenyl-9-(methylthio)anthracene product. However, this complex was not separable from the mixture and further characterization was not possible. All other routes attempted to incorporate sulfur into the system afforded no conversion of starting materials or decomposition of the reaction mixture.
98

A generalized valence bond basis for the half-filled Hubbard model

Graves, Christopher Unknown Date
No description available.
99

Valence losses at interfaces in aluminium alloys

Maclean, Ewan Douglas William. January 2002 (has links)
Thesis (Ph.D.) -- University of Glasgow, 2002. / Ph.D. thesis submitted to the Department of Physics and Astronomy and the Department of Chemistry, University of Glasgow, 2002. Includes bibliographical references. Print version also available.
100

Bonding and spectra of coordination compounds

Feltham, Robert Dean. January 1957 (has links)
Thesis (Ph. D. in Chemistry)--University of California, Berkeley, Sept. 1957. / Includes bibliographical references (leaves 107-109).

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