인지적 갈등 과제에서 자극의 정서적 상태에 기저하는 뇌활성화 차이

Dept. of Medical Science/박사Cognitive conflict occurs in various situations and individuals make an effort in order to resolve the conflict. Cognitive conflict can be induced by emotional dimension of the stimulus in the interference task including the Simon task. Emotional inconsistency between current and previous trials would interfere with response and induce conflict. In this study, the author investigated the brain activity underlying the emotional states of stimuli during a cognitive conflict task using the Simon task. The sample included 16 participants (8 men) who were recruited and right-handed. The emotional state was defined as emotional variation and emotional valence in the current study. Therefore, there were positive consistent condition, positive inconsistent condition, negative consistent condition and negative inconsistent condition with cognitive conflict condition. All emotional pictures were presented twice as both congruence and incongruence trials during each session.In the behavioral results, the participants showed higher response accuracy for the positive picture than for the negative picture under the previous congruence trial. Also, the participants showed a slower reaction time for the negative picture than the positive picture under the emotional consistency condition but not under the emotional inconsistency condition.In the imaging results, percent signal changes in response to emotional inconsistency under each emotional valence increased on the left pre supplementary motor area (pre-SMA) extending the anterior cingulate cortex (ACC). During the positive picture condition, compared to the negative condition, the precuneus and the caudal supplementary motor area (SMA-proper) and the inferior occipital gyrus were activated. However, during the negative condition compared to the positive condition, various frontal regions and the insula were activated. In the positive condition compared to the negative condition, the participants could react fast because they concentrated on the visual processing of the stimulus and motor execution during the Simon task.In this study, emotional inconsistency of stimuli induced response conflict during the Simon task and in particularly, positive inconsistent condition showed not only activation related to cognitive conflict, but also brain activation for emotional stimuli.restrictio

ppGpp metabolism in the point-mutated relA mutant of Streptomyces coelicolor

학위논문(석사) --서울대학교 대학원 :생명과학부,2007.Maste

Effect of magnetite concentrate on the assimilation behavior of quasi-particle

DoctorThe global issues on increased price of resources and depletion of high quality iron ore have been encountered in ironmaking industry. Under these circumstances, the utilization of alternative iron source is strongly required for economical ironmaking. In particular, magnetite concentrates are attractive with its large feedstock and reasonable prices as well as high iron content and low impurities. To meet the demands on utilization of low quality resources, the present research aims to find out effective methods of utilizing magnetite concentrate as an alternative iron ore resource in sintering process. In Chapter I, background information and important concepts of present work were introduced. General features of magnetite sintering were surveyed with some detrimental effects of magnetite in conventional sintering process as well as some beneficial potentials of magnetite to be utilized. In addition, the concept of quasi-particle structure and its assimilation theory were reviewed, which is considered as a key principle in the present work to utilize magnetite concentrate in sintering process. In Chapter II, the magnetite concentrate was utilized as an additive in adhering fines of quasi-particle and the effect of magnetite addition on assimilation behavior was investigated. As a basic study, synthetic mixture of typical sinter composition was prepared by using analytical grade of chemical reagents and experiments were performed focusing on the phase formation behavior of sinter. Then, as a case study, the research was further extended by adopting quasi-particle concept using actual iron ores. Samples of coupled ore tablets simulating quasi-particle were prepared and experiments were carried out to investigate how magnetite addition affects the assimilation behavior of quasi-particle. Based on the experimental results and analysis, it was found that the small amount of magnetite addition, more specifically the Fe2+ in magnetite, significantly influenced the physicochemical properties of melt as well as the structure of SFCA. As a result, it was concluded that the assimilation behavior was improved with proper amount of magnetite addition in adhering fines of quasi-particle. In Chapter III, the magnetite was employed as a main constituent of adhering fines of quasi-particle comprising nuclei of high Al2O3 pisolitic ore which is one of the low quality iron ore resources to be utilized in future. In this case, the assimilation of quasi-particle should be suppressed because the high Al2O3 content deteriorates the sinter quality. Compared to Chapter II, more practical experiments of assimilation degree analysis were carried out by using actual quasi-particle sample. In addition, small scale sintering test was performed to correlate the assimilation behavior of quasi-particle with sinter quality. As a result, the adhering fines of magnetite concentrate effectively controlled the assimilation behavior, and then the localization of Al2O3 was obtained by the formation of 3CaO∙Fe2O3∙3SiO2 melt with high viscosity at the interface between adhering fines and nuclei of quasi-particle. Furthermore, the quasi-particle sample comprising magnetite concentrate and high Al2O3 pisolitic ore showed competitive strength and reducibility. From the above experimental results and analyses, it was found that magnetite concentrate can be act as a controller of assimilation behavior of quasi-particle. In conclusion, the proper design of quasi-particle utilizing magnetite concentrate can be applicable in the actual sintering process with improved sinter quality

Formation of dicalcium ferrite at 1273K : effect of pO2 and Al2O3 content

MasterAs a fundamental study for clarifying the reactions occurring during the early stage of sintering process, formation of dicalcium ferrite in solid state between different kinds of iron oxides and CaO under various P_(O_2 ) at 1273K have been investigated. Additionally, the effect of Al2O3 content on the formation of dicalcium ferrite is also discussed. The dicalcium ferrite formation rates are evaluated by using thermogravimetric methods and the phase identification and quantification of calcium ferrites in the experiment have been carried out by using X-ray diffraction method (the Rietveld method). It has been found that intermediate calcium ferrite phases of CaFe2O4 and CaFe3O5 are formed prior to the Ca2Fe2O5 formation when Fe2O3 and Fe3O4 are used as an initial iron oxide, respectively. When starting from w？stite, intermediate calcium ferrite phases are not formed. The amount of converted Ca2Fe2O5 and its formation rates are found to be different depending on the reactant iron oxide phases and are increased in the order of reactants w？stite > Fe3O4 > Fe2O3. It is also found that the Ca2Fe2O5 formation rate starting from Fe3O4 decreases with increasing P_(O_2 ), but that starting from w？stite is independent of P_(O_2 ). Furthermore, the amount of converted Ca2Fe2O5 and its formation rates are found to be varied with different Al2O3 content

Formation of dicalcium ferrite at 1273K; the effect of pO2 and Al2O3

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Formation of calcium ferrites under controlled atmospheres

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Assimilation Behavior of Quasi-particles Comprising High Alumina Pisolitic Ore

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Neuroanatomical correlates of trait anhedonia in patients with schizophrenia: a voxel-based morphometric study

The aim of this study was to characterize the association between trait anhedonia and regional gray matter volume in patients with schizophrenia. Forty-six patients with schizophrenia and 56 healthy controls underwent magnetic resonance imaging (MRI) to acquire high-resolution T1-weighted images. Trait anhedonia was measured using the Chapman Revised Physical Anhedonia Scale (PAS). Voxel-based morphometry was performed to investigate brain volume correlates of trait anhedonia. Several brain regions in the patient group, including the left precuneus and right posterior cingulate (PCC), were found to show significantly less correlation with PAS scores than those of the control group. Post-hoc analysis revealed that negative correlations between the regional gray matter volume and the PAS scores in the patient group were found at a trend level in the left precuneus and the right PCC. In conclusion, these findings suggest that trait anhedonia in patients with schizophrenia could possibly be associated with a volume deficit in brain regions related to default-mode, which reflects the impairment of self-referential processing and reward anticipationope

Activation of the Occipital Cortex and Deactivation of the Default Mode Network During Working Memory in the Early Blind.

Although blind people heavily depend on working memory to manage daily life without visual information, it is not clear yet whether their working memory processing involves functional reorganization of the memory-related cortical network. To explore functional reorganization of the cortical network that supports various types of working memory processes in the early blind, we investigated activation differences between 2-back tasks and 0-back tasks using fMRI in 10 congenitally blind subjects and 10 sighted subjects. We used three types of stimulus sequences: words for a verbal task, pitches for a non-verbal task, and sound locations for a spatial task. When compared to the sighted, the blind showed additional activations in the occipital lobe for all types of stimulus sequences for working memory and more significant deactivation in the posterior cingulate cortex of the default mode network. The blind had increased effective connectivity from the default mode network to the left parieto-frontal network and from the occipital cortex to the right parieto-frontal network during the 2-back tasks than the 0-back tasks. These findings suggest not only cortical plasticity of the occipital cortex but also reorganization of the cortical network for the executive control of working memory. (JINS, 2011, 17, 1-16).ope