Heat flow increase following the rise of mantle isotherms and crustal thinning

Heat flow measurements in the western United States define a zone of high heat flow which coincides with the Basin and Range Province where extension has taken place recently. In this region, the average reduced heat flow is approx 30 mW sq. meters higher than in stable continental provinces; locally (e.g., Battle Mountain High), the heat flow anomaly can be more than 100 mW/sq meters above average. Estimates of the amount of extension range between 30% and 100% for the past 30 Ma. In the Colorado Plateau, which has been uplifted without major tectonic deformation, the heat flow is only slightly above average. Analytical calculations show that an abrupt change in heat flow at the base of the lithosphere 30 Ma ago would not affect the surface significantly. Uplift would proceed at a slow rate. A thermal perturbation at the base of a 40 km thick crust, however, would reach the surface faster and, after 30 Ma, the increase in surface heat flow would be about 75% of the amplitude of the heat flow anomaly. The number of volcanic rocks in the Basin and Range suggests that magma intrusions may provide an effective heat transfer mechanism. It can be show that if the source of the intrusions is at the base of the lithosphere, the response time will be much longer than 30 Ma, and most ot the heat transferred from the asthenosphere will be absorbed in the lithosphere

Selection of borehole temperature depth profiles for regional climate reconstructions

International audienceBorehole temperature depth profiles are commonly used to infer time variations in the ground surface temperature on centennial time scales. We compare different procedures to obtain a regional ground surface temperature history (GSTH) from an ensemble of borehole temperature depth profiles. We address in particular the question of selecting profiles that are not contaminated by non climatic surface perturbations and we compare the joint inversion of all the profiles with the average of individual inversions. We show that the resolution and the stability of the inversion of selected profiles are much improved over those for a complete data set. When profiles have been selected, the average GSTH of individual inversions and the GSTH of the joint inversion are almost identical. This is not observed when the entire data set is inverted: the average of individual inversions is different from the joint inversion. We also show that the joint inversion of very noisy data sets does not improve the resolution but, on the contrary, causes strong instabilities in the inversion. When the profiles that are affected by noise can not be eliminated, averaging of the individual inversions yields the most stable result, but with very poor resolution

Cortical distance determines whether flankers cause crowding or the tilt illusion

Differences between target and flanker orientations become exaggerated in the tilt illusion. However, small differences sometimes go unnoticed. This small-angle assimilation shares many similarities with other types of visual crowding but is typically found only with small and/or hard-to-see stimuli. In Experiment 1, we investigated the effect of stimulus visibility on orientation bias using relatively large stimuli. The introduction of visual noise increased the perceived similarity of target and flanker orientations at retinal eccentricities of 4- and 10-; however, small-angle assimilation was found only at 10-. The effects of eccentricity were reduced in Experiment 2, when our stimuli were “M-scaled” for equal cortical coverage. Further support for a cortical substrate was obtained in Experiment 3, in which the effects of target–flanker separation were measured. When biases from all three experiments are expressed as a fraction of the inducing flankers’ angle, and plotted as a function of the approximate cortical separation between the target and its closest flanker, they form a curve like the cross-section of half a Mexican hat. We conclude that the tilt illusion and small-angle assimilation reflect opponent influences on orientation perception. The strength of each influence increases with cortical proximity and stimulus visibility, but the one responsible for assimilation has a lesser extent

Perceived pattern regularity computed as a summary statistic: implications for camouflage

Why do the equally spaced dots in figure 1 appear regularly spaced? The answer ‘because they are’ is naive and ignores the existence of sensory noise, which is known to limit the accuracy of positional localization. Actually, all the dots in figure 1 have been physically perturbed, but in the case of the apparently regular patterns to an extent that is below threshold for reliable detection. Only when retinal pathology causes severe distortions do regular grids appear perturbed. Here, we present evidence that low-level sensory noise does indeed corrupt the encoding of relative spatial position, and limits the accuracy with which observers can detect real distortions. The noise is equivalent to a Gaussian random variable with a standard deviation of approximately 5 per cent of the inter-element spacing. The just-noticeable difference in positional distortion between two patterns is smallest when neither of them is perfectly regular. The computation of variance is statistically inefficient, typically using only five or six of the available dots

Learning in Noisy Classrooms: Children’s Reports of Annoyance and Distraction from Noise are Associated with Individual Differences in Mind-Wandering and Switching skills

Classrooms are noisy, yet little is known about pupils’ subjective reactions to noise. We surveyed 112 children between 8.70 and 11.38 years of age and extracted five dimensions in their reactions to noise by factorial analyses: (1) perceived classroom loudness, (2) hearing difficulties, (3) attention capture, (4) interference, (5) annoyance from noise. Structural Equation Models were run to better understand interindividual differences in noise interference and annoyance. Children reporting hearing and switching difficulties experienced more interference and annoyance from noise. Children who had a greater propensity for mind-wandering also experienced more interference from noise, but were annoyed by noise only to the extent that it produced interference—the relationship between mind-wandering and noise annoyance was indirect, and not direct, as was the case for reported hearing and switching difficulties. We suggest that the distinction between annoyance and interference has theoretical, empirical, and practical relevance for educational research

Cognitive control of sequential knowledge in 2-year-olds: evidence from an incidental sequence-learning and generation-task

Thirty-eight two-year-olds were trained under incidental instructions on a six element deterministic sequence of spatial locations. Following training, participants were informed of the presence of a sequence and asked to either reproduce or suppress the learned material. Children's production of the trained sequence was modulated by these instructions. When asked to suppress the trained sequence they were able to increase generation of paths that were not from the training sequence. Their performance was thus dependent on active suppresion of knowledge rather than a random generation strategy. This degree of control in two-year-olds stands in stark contrast to 3-year-olds' failure to control explicitly instructed rule-based knowledge (as measured the Dimensional Change Card Sort Task). We suggest that this is because the incidental nature of the learning enables the acquisition of a more procedural form of knowledge with which this age-group have more experience prior to the onset of fluent language

Crustal heat production in the Superior Province, Canadian Shield, and in North America inferred from heat flow data

International audienceMeasurements of heat flow and U, Th, K concentrations are used to determine the amount of heat generated in various belts of the Superior Province, the largest Archean craton on Earth. These data allow estimates of the average crustal heat production and indicate compositional differences between upper and lower crustal assemblages. The bulk average heat production of the Superior Province crust is 0.64 µW m-3 and is almost the same in different belts of slightly different ages, illustrating the remarkable uniformity of crust-building mechanisms. In the wider context of the North American continent, the bulk crustal heat production decreases from 1.0 µW m-3 in the oldest Slave Province to a minimum of 0.55 µW m-3 in the Paleo-Proterozoic Trans-Hudson Orogen. It increases in younger provinces, culminating with a high value of 1.05 µW m-3 in the Phanerozoic Appalachian Province. In all provinces, U and Th enrichment is systematically associated with sedimentary accumulations. A crustal differentiation index is obtained by calculating the ratio between the average values of heat production at the surface and in the bulk crust. The differentiation index is correlated with the bulk average heat production, which suggests that crustal differentiation processes are largely driven by internal radiogenic heat

Facial emotion recognition in refugee children with a history of war trauma.

Over 36 million children are currently displaced due to war, yet we know little about how these experiences of war and displacement affect their socioemotional development-notably how they perceive facial expressions. Across three different experiments, we investigated the effects of war trauma exposure on facial emotion recognition in Syrian refugee (n = 130, Mage = 9.3 years, 63 female) and Jordanian nonrefugee children (n = 148, Mage = 9.4 years, 66 female) living in Jordan (data collected 2019-2020). Children in the two groups differed in trauma exposure, but not on any of our measures of mental health. In Experiment 1, we measured children's biases to perceive an emotion using morphed facial expressions and found no evidence that biases differed between refugees and nonrefugees. In Experiment 2, we adapted a novel perceptual scaling task that bypasses semantic knowledge, and again found no differences between the two group's discrimination of facial expressions. Finally, in Experiment 3, we recorded children's eye movements as they identified Middle Eastern actors' facial expressions, and again found no differences between the groups in either their identification accuracies or scanning strategies. Taken together, our results suggest that exposure to war-related trauma and displacement during early development, when reported by the caregiver but not always recollected by the child, does not appear to alter emotion recognition of facial expressions. (PsycInfo Database Record (c) 2023 APA, all rights reserved)

A tilt after-effect for images of buildings: Evidence of selectivity for the orientation of everyday scenes

The tilt after-effect (TAE) is thought to be a manifestation of gain control in mechanisms selective for spatial orientation in visual stimuli. It has been demonstrated with luminance-defined stripes, contrast-defined stripes, orientation-defined stripes, and even with natural images. Of course, all images can be decomposed into a sum of stripes, so it should not be surprising to find a TAE when adapting and test images contain stripes that differ by 15° or so. We show this latter condition is not necessary for the TAE with natural images: adaptation to slightly tilted and vertically filtered houses produced a “repulsive” bias in the perceived orientation of horizontally filtered houses. These results suggest gain control in mechanisms selective for spatial orientation in natural images