Predictability of Delayed Visual Feedback Under Rubber Hand Illusion Modulates Localization but Not Ownership of the Hand

The rubber hand illusion (RHI) is a perceptual illusion, whereby a fake hand is recognized as one’s own hand when a fake hand and felt real hand are stroked synchronously. RHI strength is mainly assessed using a questionnaire rating and proprioceptive drift (PD). PD is characterized by the proprioceptively sensed location of the participant’s own hand shifting toward the location of the fake hand after RHI. However, the relationship between the two measures of hand ownership and location remains controversial due to mixed findings: some studies report correlations between them, while others show that they are independent. Here, we demonstrated significant PD without RHI using delayed visual feedback. In this RHI study, video images of the fake hand were delivered to the subjects, and four delay intervals of visual feedback (80, 280, 480, and 680ms) were introduced. In four of six conditions, the delay interval was fixed throughout the condition. In the other two conditions, four delays were delivered in a predetermined order (i.e., serial condition; higher predictability) or in a pseudo-random order (i.e., random condition; low predictability). For the four conditions with a fixed delay, the questionnaire ratings and PD declined significantly when the delay interval exceeded circa 300ms. In both the serial and random conditions, no illusory ownership of the fake hand was reported in the questionnaire. In contrast, greater PD was found in the random condition but not in the serial condition. Our findings suggest that hand ownership and localization are caused by distinct multisensory integration processes.

Language Shift Effect on Memory Generalization of Chinese-English Bilinguals

Language shift occurs when people learn information in one language but recall it in another language. This mismatch between encoding and retrieval language is found to impair memory accuracy when memory is tested immediately after learning. However, does the observed language shift effect still exist after a certain period of delay? Would it influence other aspects of memory, especially memory generalization? To address these two questions, we performed a memory experiment among unbalanced Chinese-English bilinguals. In the experiment, participants were required to read two stories (one in English, one in Chinese) and to retell the stories in Chinese from their memories afterward. Delay interval was manipulated in the experiment where participants either took memory recall tests immediately after story-reading or after 24 hours' delay. To analyze memory generalization, we coded the generalized words participants used to retell the stories. The results suggest that language shift (encoding in English and retrieving in Chinese) leads to a more generalized description in a memory recall task. However, the observed language shift effect disappears after 24 hours' delay. It can be concluded that language shift impacts bilingual learners' memory generalization in immediate recall tests, but such effect disappears after 24 hours' delay, which indicates the key role of delay interval in modulating language shift effect.

P532 Delay of maintenance infliximab increases the risk of relapse in Crohn’s disease during the COVID-19 pandemic

Background Scheduled maintenance infliximab (IFX) therapies were frequently delayed during the COVID-19 pandemic. The unusual situation allowed us to study the influence of decreased treatment adherence on Crohn’s disease (CD). This retrospective study aimed to evaluate the effect of IFX delay on relapse in Crohn’s disease (CD) patients. Methods 166 CD patients with maintenance IFX between January 25, 2020, and April 25, 2020, were retrospectively enrolled. Demographic and clinical characteristics were recorded. Relapse was defined as clinical disease relapse or biochemical disease relapse (C-reactive protein (CRP) level ≥5 mg/L without other, non-IBD related explanation). Associations between relapse and IFX delay were analyzed. Results A retrospective cohort study was conducted, including 166 CD patients receiving maintenance IFX infusion during the COVID-19 pandemic. Of all, 135 (81.3%) had delayed their IFX infusion. Only 31 (18.7%) followed the schedule infusion during the COVID-19 pandemic. The median time of the IFX delay was 18.6±17.1 days. The relapse rate in the IFX-delay group was significantly higher than the group without delay (25.9% versus 5.5%, P＜0.02). During a median IFX delay interval of 46 days (95% CI 20.9–71.1), the ratio of relapse increased with the increase of IFX delay intervals. Delay interval had a cumulative effect on disease recurrence. We proposed interval prolongation resulted in a significant IFX trough concentration reduction. Conclusion Our study provided real-world evidence of influence on relapse of IFX delay in CD patients undergone maintenance therapy. It might help the IBD specialists arrange reasonable IFX treatment intervals for patients.

On a Discrete SEIR Epidemic Model with Two-Doses Delayed Feedback Vaccination Control on the Susceptible

A new discrete susceptible-exposed-infectious-recovered (SEIR) epidemic model is presented subject to a feedback vaccination effort involving two doses. Both vaccination doses, which are subject to a non-necessarily identical effectiveness, are administrated by respecting a certain mutual delay interval, and their immunity effect is registered after a certain delay since the second dose. The delays and the efficacies of the doses are parameters, which can be fixed in the model for each concrete experimentation. The disease-free equilibrium point is characterized as well as its stability properties, while it is seen that no endemic equilibrium point exists. The exposed subpopulation is supposed to be infective eventually, under a distinct transmission rate of that of the infectious subpopulation. Some simulation examples are presented by using disease parameterizations of the COVID-19 pandemic under vaccination efforts requiring two doses.

Seismic safety of large-scale blasting in natural stone quarries

In actual practice, reduction of seismic impact of blasts down to safe level is based on standard technical documentation as well as on recommendations developed by research institutions and specialized agencies. Chiefly, these regulations are concerned with limitation of explosive mass. In the meanwhile, blasting efficiency is governed by strength of rock, various degrees of rock mass fracturing and watering, as well as by different seismic stability of close-spaced facilities, which requires application of different kinds of explosives. This article presents a case-study of seismically safe blasting design and justification for Mikashevichi granite quarry based on the PPV prediction in the basement of guarded objects. The quarry zoning is accomplished by the criterion of allowable explosive mass per one delay interval. The probabilistic PPV prediction method is described. The residential and industrial facilities within the seismic impact zone of blasting in Mikashevichi quarry can experience adverse effect of seismic waves during mining advance, which requires introduction of differentiated limitation of allowable explosive mass per one delay interval. The probabilistic approach to blasting pattern design with regard to theoretical distribution of seismicity coefficients ensures the seismic safety of blasting. The developed chart of seismically safe explosive charges per delay interval ensures integrated safety of all guarded objects at the natural stone quarry, with allowance for closer spaced blasting operations and subsequent mining advance.

Holding On to the Past: Older Adults Show Lingering Neural Activation of No-Longer-Relevant Items in Working Memory

Goal-relevant information can be maintained in working memory over a brief delay interval to guide an upcoming decision. There is also evidence suggesting the existence of a complementary process: namely, the ability to suppress information that is no longer relevant to ongoing task goals. Moreover, this ability to suppress or inhibit irrelevant information appears to decline with age. In this study, we compared younger and older adults undergoing fMRI on a working memory task designed to address whether the modulation of neural representations of relevant and no-longer-relevant items during a delay interval is related to age and overall task performance. Following from the theoretical predictions of the inhibitory deficit hypothesis of aging, we hypothesized that older adults would show higher activation of no-longer-relevant items during a retention delay compared to young adults and that higher activation of these no-longer-relevant items would predict worse recognition memory accuracy for relevant items. Our results support this prediction and more generally demonstrate the importance of goal-driven modulation of neural activity in successful working memory maintenance. Furthermore, we showed that the largest age differences in the regulation of category-specific pattern activity during working memory maintenance were seen throughout the medial temporal lobe and prominently in the hippocampus, further establishing the importance of “long-term memory” retrieval mechanisms in the context of high-load working memory tasks that place large demands on attentional selection mechanisms.