Freeze or Forget? Virtual Attack Effects in an Emotional Sternberg Task

Emotionally salient stimuli have the ability to disrupt cognitive processing. This kind of disruption involves effects on working memory and may be related to mental health problems. To explore the nature of such emotional interference on working memory, a Virtual Attack Emotional Sternberg Task (VAEST) was used. Neutral faces were presented as distractors and warning signals, which were sometimes followed by a virtual attack, created by having the neutral face turn angry while the image was enlarged. The attack was hypothesized to have one of two effects: to disrupt cognitive processing and thereby increase interference effects, or to terminate a state of freezing and thereby reduce interference effects. The task was successfully completed online by a sample of 59 students. Results clearly show that the virtual attack caused a reduction of interference relative to no-attack trials. The apparent cognitive disruption caused by emotional distractors may thus reflect freezing, which can be reversed by a freeze-terminating stimulus

Contesting Collective Representations of the Past: The Politics of Memory in South Korea

Because monuments, memorials and other 'sites of memory' privilege particular collective interpretations of the past over others, they represent inherently contentious and political spaces. Contention over representing the past is particularly resonant in Korea, where sites of memory are imbued with strong, often polarised meanings. By focusing on two such sites in Korea, this thesis seeks to discuss the wider implications of the ongoing conflict over what representations of the past should be privileged. In Gwangju, the area surrounding the former provincial hall (docheong) is being redeveloped, part of the city's attempts to become 'reborn' as a capital city of human rights and democracy in Asia. However, to many citizens in Gwangju, this new image ignores the meaning that the city's dissident past holds for local communal understandings of identity. Conflict arose as citizens protested to keep the symbolism of the docheong intact, thus, helping to maintain local narratives of the past. In Seoul, Myeongdong Cathedral, a key symbol of protest and democracy in the 1970s and 1980s, is now having its meaning re-interpreted, as the Catholic Church de-couples religion from socio-political concerns. The conflicting meanings of Myeongdong Cathedral are representative of a wider divergence in Korean society, as apathy towards Korea's past grows among society at large while other segments appropriate the past to protest contemporary socio-political concerns. Ultimately, these Korean case studies emphasise that the meanings sites of memory convey are not fixed, and that groups are often able to appropriate sites to affirm their own narratives of the past and to emphasise their own collective voice. Therefore, sites that represent particular understandings of the past, while contentious, also provide a space for debate and, thus, help to understand ongoing concerns within wider society

Random pinning limits the size of membrane adhesion domains

Theoretical models describing specific adhesion of membranes predict (for certain parameters) a macroscopic phase separation of bonds into adhesion domains. We show that this behavior is fundamentally altered if the membrane is pinned randomly due to, e.g., proteins that anchor the membrane to the cytoskeleton. Perturbations which locally restrict membrane height fluctuations induce quenched disorder of the random-field type. This rigorously prevents the formation of macroscopic adhesion domains following the Imry-Ma argument [Y. Imry and S. K. Ma, Phys. Rev. Lett. 35, 1399 (1975)]. Our prediction of random-field disorder follows from analytical calculations, and is strikingly confirmed in large-scale Monte Carlo simulations. These simulations are based on an efficient composite Monte Carlo move, whereby membrane height and bond degrees of freedom are updated simultaneously in a single move. The application of this move should prove rewarding for other systems also.Comment: revised and extended versio

Towards a hybrid comfortable passenger cabin interior for the flying V aircraft

The Flying-V is a V-shaped airplane in development, which uses less fuel due its form. Passengers are in the oval cabin in the wing, which asks for an alternative design to the interior. At the same time there is a demand for more comfortable interiors. 80 students were asked to develop interior design ideas for this Flying V concept. A jury of experts selected four aircraft interior concepts and these were developed and a 1:1 scale mockup was made, with a hybrid interior. It included a chaise longue seats, the group space, beds and ‘staggered’ seats for the middle of the Flying V interior. This was shown at a KLM 100 year event. 1692 visitors of the mock-up gave their preference and the chaise longue received most votes. In the discussions valuable comments from potential passengers were collected on the selected concepts giving input for further developments

Techno-economic assessment of the one-step CO₂conversion to dimethyl ether in a membrane-assisted process

This study investigates the impact of the membrane reactor (MR) technology with in-situ removal of water to boost the performance of the one-step DME synthesis via CO2 hydrogenation at process scale. Given the higher efficiency in converting the feedstock, the membrane reactor allows for a remarkable decrease in the main cost drivers of the process, i.e., the catalyst mass and the H2 feed flow, by ca. 39% and 64%, respectively. Furthermore, the MR-assisted process requires 46% less utilities than the conventional process, especially in terms of cooling water and refrigerant, with a corresponding decrease in environmental impact (i.e., 25% less CO2 emissions). Both the conventional and MR-assisted plants were found effective for the mitigation of the CO2 emissions, avoiding ca. 1.4-1.6 tonCO2/tonDME. However, given the higher reactor and process efficiency, the membrane technology contributes to a significant reduction (i.e., 25%) in the operating costs, which is a remarkable improvement in this OPEX intensive process. Nevertheless, the calculated minimum DME selling price (i.e., 1739 €/ton and 1960 €/ton for the MR-assisted and the conventional process, respectively) is over 3 times greater than the current DME market price. Yet, with the predicted decrease of renewable H2 price and a zero-to-negative cost for the CO2 feedstock, the MR-assisted system could become competitive with the benchmark between 2025 and 2050.</p

Spatial anticipatory attentional bias for threat: reliable individual differences with RT-based online measurement

Cues that predict the future location of emotional stimuli may evoke an anticipatory form of automatic attentional bias. The reliability of this bias towards threat is uncertain: experimental design may need to be optimized or individual differences may simply be relatively noisy in the general population. The current study therefore aimed to determine the split-half reliability of the bias, in a design with fewer factors and more trials than in previous work. A sample of 63 participants was used for analysis, who performed the cued Visual Probe Task online, which aims to measure an anticipatory attentional bias. The overall bias towards threat was tested and split-half reliability was calculated over even and odd blocks. Results showed a significant bias towards threat and a reliability of around 0.7. The results support systematic individual differences in anticipatory attentional bias and demonstrate that RT-based bias scores, with online data collection, can be reliable

Anticipated attack slows responses in a cued virtual attack emotional sternberg task

Threatening stimuli have varying effects, including reaction time increase in working memory tasks. This could reflect disruption of working memory or, alternatively, a reversible state of freezing. In the current series of experiments, reversible slowing due to anticipated threat was studied using the cued Virtual Attack Emotional Sternberg Task (cVAEST). In this task visually neutral cues indicate whether a future virtual attack could or could not occur during the maintenance period of a Sternberg task. Three studies (N = 47, 40, and 40, respectively) were performed by healthy adult participants online. The primary hypothesis was that the cVAEST would evoke anticipatory slowing. Further, the studies aimed to explore details of this novel task, in particular the interval between the cue and probe stimuli and the memory set size. In all studies it was found that threat anticipation slowed RTs on the working memory task. Further, Study 1 (memory set size 3) showed a decrease in RT when the attack occurred over all CSIs. In Study 2 a minimal memory set of one item was used, under which circumstances RTs following attacks were only faster shortly after cue presentation (CSI 200 and 500 ms), when RTs were high for both threat and safe cues. Study 3 replicated results of Study 2 with more fine-grained time intervals. The results confirm that anticipation of attack stimuli can reversibly slow responses on an independent working memory task. The cVAEST may provide a useful method to study such threat-induced response slowing

Alcohol-related attentional bias variability and conflicting automatic associations

Attentional bias variability is related to alcohol abuse. Of potential use for studying variability is the anticipatory attentional bias: Bias due to the locations of predictively-cued rather than already-presented stimuli. The hypothesis was tested that conflicting automatic associations are related to attentional bias variability. Further, relationships were explored between anticipatory biases and individual differences related to alcohol use. 74 social drinkers performed a cued Visual Probe Task and univalent Single-Target Implicit Associations Tasks. Questionnaires were completed on risky drinking, craving, and motivations to drink or refrain from drinking. Ambiguity was related to attentional bias variability at the 800 ms Cue-Stimulus Interval. Further, a bias related to craving and risky drinking was found at the 400 ms Cue-Stimulus Interval. Thus, the selection of attentional responses was biased by predicted locations of expected salient stimuli. The results support a role of conflicting associations in attentional bias variability

Experimental control of conflict in a predictive visual probe task: Highly reliable bias scores related to anxiety

Concerns have been raised about the low reliability of measurements of spatial attentional bias via RT differences in dot-probe tasks. The anticipatory form of the bias, directed towards predicted future stimuli, appears to have relatively good reliability, reaching around 0.70. However, studies thus far have not attempted to experimentally control task-related influence on bias, which could further improve reliability. Evoking top-down versus bottom-up conflict may furthermore reveal associations with individual differences related to mental health. In the current study, a sample of 143 participants performed a predictive Visual Probe Task (predVPT) with angry and neutral face stimuli online. In this task, an automatic bias is induced via visually neutral cues that predict the location of an upcoming angry face. A task-relevant bias was induced via blockwise shifts in the likely location of target stimuli. The bias score resulting from these factors was calculated as RTs to target stimuli at locations of predicted but not actually presented angry versus neutral faces. Correlations were tested with anxiety, depression, self-esteem and aggression scales. An overall bias towards threat was found with a split-half reliability of 0.90, and 0.89 after outlier removal. Avoidance of threat in blocks with a task-relevant bias away from threat was correlated with anxiety, with correction for multiple testing. The same relationship was nominally significant for depression and low self-esteem. In conclusion, we showed high reliability of spatial attentional bias that was related to anxiety

Idealized Multigrid Algorithm for Staggered Fermions

An idealized multigrid algorithm for the computation of propagators of staggered fermions is investigated. Exemplified in four-dimensional $SU(2)$ gauge fields, it is shown that the idealized algorithm preserves criticality under coarsening. The same is not true when the coarse grid operator is defined by the Galerkin prescription. Relaxation times in computations of propagators are small, and critical slowing is strongly reduced (or eliminated) in the idealized algorithm. Unfortunately, this algorithm is not practical for production runs, but the investigations presented here answer important questions of principle.Comment: 11 pages, no figures, DESY 93-046; can be formatted with plain LaTeX article styl