Search

Burnt rocks usually exhibit magnetic enhancement, which can be used to detect the spontaneous combustion zone of a coal fire or locate the resources in burnt rocks. To elucidate the mechanisms underlying magnetic enhancement, sandstone is heated to high temperatures between 100 and 1200°C. The mass susceptibility of the sandstone is measured after cooling, and the magnetic characteristics are explained based on the changes in colour and porosity, thermogravimetric and differential thermal analysis experiments and the observation of thin sections of rocks and scanning electron microscopy images. The findings are as follows: (1) the magnetic susceptibility of sandstone increases rapidly by two orders of magnitude as the temperature rises above 800°C. (2) The oxidation of iron ions and the formation of magnetite enhance the magnetic susceptibility of sandstone. The formation of magnetite at 800°C significantly enhances the magnetic susceptibility. (3) The highest temperature experienced by a burnt rock can be evaluated by analysing the different responses of the susceptibility of sandstone to temperature. Furthermore, it is possible to use the magnetic anomaly of the burnt rock to locate it and develop and utilise the beneficial resources in the burnt rock.

Hearing a task-irrelevant sound during object encoding can improve visual recognition memory when the sound is object-congruent (e.g., a dog and a bark). However, previous studies have only used binary old/new memory tests, which do not distinguish between recognition based on the recollection of details about the studied event or stimulus familiarity. In the present research, we hypothesized that hearing a task-irrelevant but semantically congruent natural sound at encoding would facilitate the formation of richer memory representations, resulting in increased recollection of details of the encoded event. Experiment 1 replicates previous studies showing that participants were more confident about their memory for items that were initially encoded with a congruent sound compared to an incongruent sound. Experiment 2 suggests that congruent object-sound pairings specifically facilitate recollection and not familiarity-based recognition memory, and Experiment 3 demonstrates that this effect was coupled with more accurate memory for audiovisual congruency of the item and sound from encoding rather than another aspect of the episode. These results suggest that even when congruent sounds are task-irrelevant, they promote formation of multisensory memories and subsequent recollection-based retention. Given the ubiquity of encounters with multisensory objects in our everyday lives, considering their impact on episodic memory is integral to building models of memory that apply to naturalistic settings.

Visual attention is often characterized as being guided by precise memories for target objects. However, real-world search targets have dynamic features that vary over time, meaning that observers must predict how the target

Previous studies have tended to infer that reactive control is intact in aging populations because of evidence that proactive control is impaired and that older participants appear to favor reactive control strategies. However, most of these studies did not compare reactive control in young and older participants directly. In our study, a young (18 to 21 years old) and older (60+ years old) cohort engaged in a task that assesses reactive distractor suppression where participants had to discriminate between an upright and inverted T-shape in the presence of a salient or nonsalient distractor. In previous studies using this paradigm (DiQuattro & Geng, 2011) young participants reactively used the salient distractor as an anticue and performed better (faster reaction time [RT] and higher accuracy) when it was present. It was found that older participants were not able to reactively suppress the salient distractor with a 200-ms display but were able to do so with a 600-ms display. It was concluded that the initiation of reactive suppression is delayed for older participants, but that effective suppression is possible given enough time. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Attention operates as a cognitive gate that selects sensory information for entry into memory and awareness (Driver, 2001, British Journal of Psychology, 92, 53–78). Under many circumstances, the selected information is task-relevant and important to remember, but sometimes perceptually salient nontarget objects will capture attention and enter into awareness despite their irrelevance (Adams & Gaspelin, 2020, Attention, Perception, & Psychophysics, 82[4], 1586–1598). Recent studies have shown that repeated exposures with salient distractor will diminish their ability to capture attention, but the relationship between suppression and later cognitive processes such as memory and awareness remains unclear. If learned attentional suppression (indicated by reduced capture costs) occurs at the sensory level and prevents readout to other cognitive processes, one would expect memory and awareness to dimmish commensurate with improved suppression. Here, we test this hypothesis by measuring memory precision and awareness of salient nontargets over repeated exposures as capture costs decreased. Our results show that stronger learned suppression is accompanied by reductions in memory precision and confidence in having seen a color singleton at all, suggesting that such suppression operates at the sensory level to prevent further processing of the distractor object.

The ability to suppress distractions is essential to successful completion of goal-directed behaviors. Several behavioral studies have recently provided strong evidence that learned suppression may be particularly efficient in reducing distractor interference. Expectations about a distractor's repeated location, color, or even presence are rapidly learned and used to attenuate interference. In this study, we use a visual search paradigm in which a color singleton, which is known to capture attention, occurs within blocks with high or low frequency. The behavioral results show reduced singleton interference during the high compared to the low frequency block (Won et al., 2019). The fMRI results provide evidence that the attenuation of distractor interference is supported by changes in singleton, target, and non-salient distractor representations within retinotopic visual cortex. These changes in visual cortex are accompanied by findings that singleton-present trials compared to non-singleton trials produce greater activation in bilateral parietal cortex, indicative of attentional capture, in low frequency, but not high frequency blocks. Together, these results suggest that the readout of saliency signals associated with an expected color singleton from visual cortex is suppressed, resulting in less competition for attentional priority in frontoparietal attentional control regions.

Although schizophrenia is classically thought to involve impaired attentional filtering, people with schizophrenia (PSZ) exhibit a more intense and more exclusive attentional focus than healthy control subjects (HCS) in many tasks. To resolve this contradiction, this functional magnetic resonance imaging study tested the impact of attentional control demands on the modulation of stimulus-induced activation in the fusiform face area and parahippocampal place area when participants (43 PSZ and 43 HCS) were looking for a target face versus house. Stimuli were presented individually, or as face-house overlays that challenged attentional control. Responses were slower for house than face stimuli and when prioritizing houses over faces in overlays, suggesting a difference in salience. Blood-oxygen-level-dependent activity reflected poorer attentional selectivity in PSZ than HCS when attentional control was challenged most, that is, when stimuli were overlaid and the task required detecting the lower-salience house target. By contrast, attentional selectivity was exaggerated in PSZ when control was challenged least, that is, when stimuli were presented sequentially and the task required detecting the higher-salience face target. These findings are consistent with 2 distinct attentional abnormalities in schizophrenia leading to impaired and exaggerated selection under different conditions: attentional control deficits, and hyperfocusing once attention has been directed toward a stimulus.

Unlike long bones, jawbone development is mainly accomplished by intramembranous ossification resulting from the differentiation of periosteal progenitor cells. However, the spatiotemporal ontogeny of periosteal progenitor cells during jawbone development and repair remains elusive. In this study, we mapped the transcriptional landscape of the human jawbone periosteum at single-cell resolution and identified a cathepsin K (Ctsk)+ periosteal subset. Lineage tracing analysis indicated that Ctsk-Cre–labeled periosteal cells could make contributions to jawbone development. However, different from the periosteal-specific location of Ctsk+ cells in long bone, we also identified Ctsk+ stromal cells in jawbone marrow and implied the heterogeneity of jawbone Ctsk+ hierarchy. In further analysis of the periosteal progenitor cell subset of heterogeneous Ctsk+ hierarchy, we identified a unique Ctsk+Ly6a+ subset of cells. The additional marker Ly6a helped to further confine the progenitor subset to the jawbone periosteum and was nearly undetectable in the bone marrow. Defects in the jawbone could activate the migration and osteogenic differentiation of Ctsk+Ly6a+ cells. Local ablation of Ctsk+ cells by diphtheria reduced the number of Ctsk+Ly6a+ cells and delayed the repair of the bone defect. Taken together, we identify a novel periosteal osteogenic progenitor subset that is active in jawbone osteogenesis and healing.

When searching for an object, we use a target template in memory that contains task-relevant information to guide visual attention to potential targets and to determine the identity of attended objects. These processes in visual search have typically been assumed to rely on a common source of template information. However, our recent work (Yu et al., 2022) argued that attentional guidance and target-match decisions rely on different information during search, with guidance using a “fuzzier” version of the template compared with target decisions. However, that work was based on the special case of search for a target amongst linearly separable distractors (e.g., search for an orange target amongst yellower distractors). Real-world search targets, however, are infrequently linearly separable from distractors, and it remains unclear whether the differences between the precision of template information used for guidance compared with target decisions also applies under more typical conditions. In four experiments, we tested this question by varying distractor similarity during visual search and measuring the likelihood of attentional guidance to distractors and target misidentifications. We found that early attentional guidance is indeed less precise than that of subsequent match decisions under varying exposure durations and distractor set sizes. These results suggest that attentional guidance operates on a coarser code than decisions, perhaps because guidance is constrained by lower acuity in peripheral vision or the need to rapidly explore a wide region of space while decisions about selected objects are more precise to optimize decision accuracy.

Theories of visual attention hypothesize that target selection depends upon matching visual inputs to a memory representation of the target - i.e., the target or attentional template. Most theories assume that the template contains a veridical copy of target features, but recent studies suggest that target representations may shift “off veridical” from actual target features to increase target-to-distractor distinctiveness. However, these studies have been limited to simple visual features (e.g., orientation, color), which leaves open the question if similar principles apply to complex stimuli, such as a face depicting an emotion, the perception of which is known to be shaped by conceptual knowledge (Gendron & Barrett, 2018; Lindquist, Satpute, & Gendron, 2015). In three studies, we find confirmatory evidence for the hypothesis that attention modulates the representation of an emotional face to increase target-to-distractor distinctiveness. This occurs over-and-above strong pre-existing conceptual and perceptual biases in the representation of individual faces. The results are consistent with the view that visual search accuracy is determined by the representational distance between the target template in memory and distractor information in the environment, not the veridical target and distractor features (Geng & Witkowski, 2019).

This paper presents experimental and modelling results of an ultra-compact self-rectifier flux pump energizing a superconducting coil. The device fits inside a volume of 65x65x50~mm and generates up to 320~A dc through the coil and a peak output voltage up to 60~mV. We also develop and present a full electromagnetic effective circuit model of the flux pump and compare its predictions to the experimental results. We show that our model can reproduce accurately the charging of the load coil and that it reproduces the systematic dependence of the maximum load coil current on the input current waveform. The experiments and modelling together show also the importance of dc-flux offsets in the transformer core on the final achievable current through the coil. The miniaturization possible for this class of flux pump and their minimal heat-leak into the cryogenic environment from thermal conduction make them attractive for applications with demanding size, weight and power limitations. Our effective circuit model is a useful tool in the understanding, design and optimization of such flux pumps which will accelerate their progression from research devices to their application., Comment: 9 pages, 8 figures

A Volumetric Method of Moments accelerated by means of iterative solvers combined with FFT matrix-vector products has been presented. The method allows analyzing small lens antennas with their integrated feeds efficiently since different structures and geometries can be studied with the same discretization, just by adding the material characteristics in post-processing.

Models of attention posit that attentional priority is established by summing the saliency and relevancy signals from feature-selective maps. The dimension-weighting account further hypothesizes that information from each feature-selective map is weighted based on expectations of how informative each dimension will be. In the current studies, we investigated the question of whether attentional biases to the features of a conjunction target (color and orientation) differ when one dimension is expected to be more diagnostic of the target. In a series of color-orientation conjunction search tasks, observers saw an exact cue for the upcoming target, while the probability of distractors sharing a target feature in each dimension was manipulated. In one context, distractors were more likely to share the target color, and in another, distractors were more likely to share the target orientation. The results indicated that despite an overall bias toward color, attentional priority to each target feature was flexibly adjusted according to distractor context: RT and accuracy performance was better when the diagnostic feature was expected than unexpected. This occurred both when the distractor context was learned implicitly and explicitly. These results suggest that feature-based enhancement can occur selectively for the dimension expected to be most informative in distinguishing the target from distractors.

Theories of attention hypothesize the existence of an “attentional” or “target” template that contains task-relevant information in memory when searching for an object. The target template contributes to visual search by directing visual attention towards potential targets and serving as a decisional boundary for target identification. However, debate still exists regarding how template information is stored in the human brain. Here, we conducted a pattern-based fMRI study to assess how template information is encoded to optimize target-match decisions during visual search. To ensure that match decisions reflect visual search demands, we used a visual search paradigm in which all distractors were linearly separable but highly similar to the target and were known to shift the target representation away from the distractor features (Yu & Geng, 2019). In a separate match-to-sample probe task, we measured the target representation used for match decisions across two resting state networks that have long been hypothesized to maintain and control target information: the frontoparietal control network (FPCN) and the visual network (VisN). Our results showed that lateral prefrontal cortex in FPCN maintained the context-dependent “off-veridical” template; in contrast, VisN encoded a veridical copy of the target feature during match decisions. By using behavioral drift diffusion modeling, we verified that the decision criterion during visual search and the probe task relied on a common biased target template. Taken together, our results suggest that sensory-veridical information is transformed in lateral prefrontal cortex into an adaptive code of target-relevant information that optimizes decision processes during visual search.

Background Cardiac stromal cells (CSCs) contain a pool of cells with supportive and paracrine functions. Various types of mesenchymal stromal cells (MSCs) can influence CSCs in the cardiac niche through their paracrine activity. Ischemia/reperfusion (I/R) leads to cell death and reduction of the paracrine activity of CSCs. The forced coexpression of telomerase reverse transcriptase (TERT) and myocardin (MYOCD), known to potentiate anti-apoptotic, pro-survival and pro-angiogenic activities of MSCs isolated from the adipose tissue (AT-MSCs), may increase CSC survival, favoring their paracrine activities. Aim To investigate the hypothesis that CSCs feature improved resistance to simulated I/R (SI/R) and increased commitment toward the cardiovascular lineage when preconditioned with conditioned media (CM) or extracellular vesicles (EV) released from AT-MSCs overexpressing TERT and MYOCD (T/M AT-MSCs). Methods and results Murine CSCs were isolated with the cardiosphere (CSps) isolation technique. T/M AT-MSCs and their secretome improved spontaneous intracellular calcium changes and ryanodine receptor expression in aged CSps. The cytoprotective effect of AT-MSCs was tested in CSCs subjected to SI/R. SI/R induced cell death as compared to normoxia (28±4 vs 10±3%, p=0.02). Pretreatment with CM (15±2, p=0.02) or with the EV-enriched fraction (10±1%, p=0.02) obtained from mock-transduced AT-MSCs in normoxia reduced cell death after SI/R. The effect was more prononunced with CM (7±1%, p=0.01) or the EV-enriched fraction (2±1%, p=0.01) obtained from T/M AT-MSCs subjected to SI/R. In parallel, we observed lower expression of the apoptosis marker cleaved caspase-3 and higher expression of cardiac and vascular markers eNOS, sarcomeric α-actinin and cardiac actin. Conclusions The T/M AT-MSCs secretome exerts a cytoprotective effect and promotes development of CSCs undergoing SI/R towards a cardiovascular phenotype. Funding Acknowledgement Type of funding sources: None.

We have searched for weak fast radio burst (FRB) events using a database containing 568,736,756 transient events detected using the Parkes radio telescope between 1997 and 2001. In order to classify these pulses, and to identify likely FRB candidates, we used a machine learning algorithm based on ResNet. We identified 81 new candidate FRBs and provide details of their positions, event times, and dispersion measures. These events were detected in only one beam of the Parkes multibeam receiver. We used a relatively low S/N cutoff threshold when selecting these bursts and some have dispersion measures only slightly exceeding the expected Galactic contribution. We therefore present these candidate FRBs as a guide for follow-up observations in the search for repeating FRBs., 8 pages, 5 figures, 2 tables, accepted by MNRAS