Association between cerebral blood flow and cerebral small vessel disease: a comparison between ASL and phase-contrast MRI
Linyun XieJiaxin ZhengYao Yu ZhangHui HongShan XuLei CuiShuyue WangJixuan LiLingyun LiuLin MiaoXiao LuoKaicheng LiQingze ZengMinming ZhangRuiting ZhangLi ZhaoPeiyu Huang
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Motivation: Chronic hypoperfusion is a central mechanism of cerebral small vessel disease (CSVD), but studies using different methods have shown different results. Goal(s): To compare the associations between CSVD and CBF measured by phase-contrast MRI and ASL in the same cohort. Approach: 69 subjects were totally recruited in the study. WMH, FW, and tFA were used to reflect the disease severity. The associations between CSVD and CBF measured by two methods were investigated. Results: Compared to CBFPC, CBFASL showed a negative association with FW and a positive association with tFA. The ratio of CBFASL to CBFPC was also correlated with FW and tFA. Impact: Future studies need to consider the differences between CBF measured by ASL and phase-contrast MRI and choose a more appropriate method according to the research purpose.Keywords:
Association (psychology)
Neurophysiological findings and recent theorizing suggest that contrast may influence the ease of attentional selection, with high-contrast stimuli easy to select and hard to ignore. We tested this in four experiments. In Exp 1, subjects searched for a target (an “8” or a “9”) in a display of digits. In separate blocks, subjects searched a display of: (A) low-contrast digits, (B) high-contrast digits, (C) half low- and half high-contrast digits, with the target appearing among the low-contrast digits, or (D) half low- and half high-contrast digits, with the target appearing among the high-contrast digits. In conditions C and D, subjects were told the contrast of the target, potentially allowing them to select based on contrast. Subjects performed significantly better in condition C than in A (and better in condition D than in B), indicating that contrast differences between relevant and irrelevant stimuli improves search even when the irrelevant stimuli are of higher contrast. In Exps 2 and 3, subjects searched for a target among digits within half of the items, which was defined by color (red vs. green) or location, respectively. The contrast of these “relevant” and “irrelevant” sets was independently manipulated. When the relevant subset was defined by color, the search was easier whenever the “relevant” and “irrelevant” items had different contrast levels, even when the distractors were high-contrast. However, when the relevant items were in distinct locations, search was harder when the irrelevant subset was of high-contrast. This was not true, however, when the same experiment was repeated with different contrast levels presented in different blocks (Exp 4). Overall, the results suggest that selective attention to either high- or low-contrast is readily achieved, although this capability is not always utilized. The results challenge the most obvious linkage between attentional function and neurophysiological findings concerning contrast and attention.
Color contrast
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Extract Extended abstract of a paper presented at Microscopy and Microanalysis 2007 in Ft. Lauderdale, Florida, USA, August 5 – August 9, 2007
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Hollingsworth recently showed a posttest contrast for ANOVA situations that, for equal N, had several favorable qualities; the contrast is maximized so that if the overall F test were significant, the contrast would also be significant. The coefficients are chosen such that , which is said to help interpret the resulting contrast. However, for unequal N, the contrast suggested by Hollingsworth fails to achieve status as a maximized contrast; thus the contrast is not insured to be significant when the overall F test is significant, requiring separate testing of the contrast.
Contrast effect
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For these years,besides the contrast of the two language structures,linguists also have made contrast research for the two kinds of cultures.From language contrast to culture contrast, it shows the development of contrast has entered a new stage.It is not difficult to indicate the diffrence between things,but to indicate why it is different is not easy.That is just the aim of contrast research.
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To improve our capability of association helps to strengthen our memory in listening comprehension. There are three principal laws of association to follow: close association, contrary association and similar association. For different listening materials, different ways of association can be used, such as culture and background association, semantic coherence association, orientation association, context's contrary association, image association, sequence and scene association.
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This article established a general theory of equating visibilities based on task contrast and contrast sensitivities. It quantifies the relationship between equivalent contrast of a task and its physical contrast, as well as the relationship between visual CRF (Contrast Rendition Factor) and physical CRF.
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Whether contrast adaptation may enhance contrast discrimination is a question that has remained largely unresolved because of conflicting empirical evidence. Greenlee and Heitger (1988), for example, reported that contrast discrimination may be enhanced after contrast adaptation, while Maattanen and Koenderink (1991) did not. This paper aimed to account for the different conclusions reached by these independent researchers by manipulations of key differences that exist between the two studies. It is shown that contrast discrimination may be enhanced after adaptation, but that these effects can vary markedly across subjects and test conditions. Enhancements in contrast discrimination are reported to be significant when adapting and testing at low levels of contrast, but just significant at higher levels of contrast. For high contrast signals; enhancements are shown to be independent of temporal frequency but dependent upon viewing conditions. Under binocular viewing conditions, enhancements in contrast discrimination thresholds are shown to be significantly higher than under monocular viewing conditions. It is suggested that the different conclusions reached by Greenlee and Heitger and by Maattanen and Koenderink may be explained by their respective differences in viewing conditions. The former study used binocular, while the latter study used monocular viewing with an occluding eyepatch.
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The aim of this paper is to rationalize the idea of constructing a contrast category as one of the semantic categories in Chinese Language,as well as to classify it from different perspectives.There are theoretical supports from cognitive psychology and linguistic that contrast as a semantic category in modern Chinese is the reflection of contrast as part of humankinds' cognitive mechanism.As a semantic category revises a certain relationship,contrast is characterized by highlighting difference.From different perspectives we can classify contrast category into different sub-categories as follows:marked contrast and unmarked contrast,antithetical contrast and non-antithetical contrast,two-thing contrast and two-profile contrast,linear contrast and non-linear contrast,overt contrast and implied contrast,unitary contrast and multiple contrast and etc.
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Floral design에서 contrast는 작품의 개성이 뚜렷해지고 시각적 효과를 강하게 나타낼 수 있다. 본고에서는 Floral design의 예술적 조형성과 독창성을 발전시킬 수 있는 디자인원리로써 contrast를 논제로 삼아 이론적 근거를 제시하고자 하였다. Floral design에서 나타난 contrast의 표현양상들을 형태의 contrast, 면적의 contrast, 색채의 contrast 그리고 질감의 contrast로 분류하여 미적특성을 살펴보았다. Contrast의 표현 양상들을 살려봄으로써 contrast를 구체적으로 시각화하는 방안을 제시하고자 세계 유명 플로리스트들의 작품(10점) 속에 나타난 contrast와 본 연구자 개인전 및 데몬스트레이션 작품(10점)에서 contrast가 잘 표현된 작품들을 제시하여 contrast의 표현양상을 비교분석하였다. 형태의 contrast는 작품의 조형성을 중시하며 기하형태 또는 양감위주의 형태표현을 볼 수 있는 반면 본 연구자는 자연의 생태성을 고려한 자연형태 내지 유기형태 그리고 자연그대로의 선 흐름과 연결된 형태와 공간의 미를 표현하였다. 면적의 contrast는 소재의 grouping에 의한 면적 내지 소재를 다양한 기법으로 재구성한 면적으로 작품에 표현하는 반면 본 연구자는 소재 자체가 지닌 면적 또는 소재의 재구성에 의한 면적으로 contrast를 표현하였다. 질감의 contrast는 규칙적으로 붙이거나 다양한 basketry 기법에 의한 질감 표현 위주임에 반해 본 연구자는 자연소재가 지닌 자체질감 그대로를 표현하였다. Contrast의 표현에서 있어서 이상 열거한 상이점도 있으나 많은 작품에서 표현기법이나 작가의 조형 성향에 따라 공통점도 많이 볼 수 있었다. 색채의 contrast는 유명 플로리스트의 작품과 본 연구자의 작품에서 공통적인 부분을 많이 찾아 볼 수 있었다. Floral design의 원리 중 contrast가 시각적 독창성과 조형성을 유도할 수 있는 원리임을 밝혀 현대 Floral design 창작활동의 발전과 심층적 연구를 위한 방향을 제시하고자 한다.
Color contrast
High contrast
Contrast effect
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