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Permafrost in High Mountain Asia (HMA) is becoming increasingly vulnerable to thaw due to climate change. However, the lack of either in situ ground surface or borehole temperature data beyond the Tibetan Plateau prevents comprehensive assessments of its impact on the regional hydrologic cycle and local cascading hazards. Although past studies have generated estimates of permafrost extent in Central Asia, many are limited to the Tibetan Plateau, excluding the more remote reaches of the Tien Shan, Pamirs, and Himalayas. By leveraging surface temperatures from both the Moderate Resolution Imaging Spectroradiometer (MODIS) and Atmospheric Infra-Red Sounder (AIRS), this study advances further understanding of remotely sensed permafrost occurrence at high altitudes, which are prone to error due to frequent cloud cover. We demonstrate that the fusion of MODIS and AIRS products can accurately estimate long-term thermal regimes of the subsurface, with reported correlation coefficients of 0.773 and 0.560, RMSEs of 0.890 °C and 0.680 °C, and biases of 0.003 °C and 0.462 °C, respectively, for the ground surface and the depth of zero annual amplitude, during a reference period of 2003–2016. Furthermore, we provide a range of possible permafrost extents based on established equations for calculating the temperature at the top of the permafrost to demonstrate temperature sensitivity to soil moisture and snow cover. The MODIS-AIRS product is recommended to be a robust source of ground temperature estimates, which may be sufficient for inferring mountain permafrost presence in HMA. Incorporating the influence of soil moisture and snow depth, although limited by biased estimates, also produces estimates of permafrost regional areas comparable to previously reported permafrost indices. A total permafrost area of 1.69 (± 0.32) million km2 is estimated for the entire HMA, across 15 mountain subregions. 

We provide some evidence for nonzero electron velocity at the tunnel exit in strong-field atomic ionization. Our investigation is based on the analysis of a suitably chosen correlation function which describes correlations between the two observables: the longitudinal electron velocity and the appearance of the photoelectron in the continuum at the end of the laser pulse. The results of the correlation function analysis that we perform are confirmed by the calculations using the quantum orbits method. Published by the American Physical Society2024 

This experimental investigation seeks to confirm and extend previous investigations that resource interdependence vs. independence during problem-solving relatively extends the problem representation phase before convergence on a solution. In this current investigation, ninth-grade Korean native language participants (n = 240) worked online to complete either a well-structured or an ill-structured problem in either independent triads where all of the members were provided with all of the information needed to solve the problem, or in interdependent triads where members were each provided with different portions of the information needed. The discussions were analyzed using a content analysis rubric from Engelmann and Hesse (JAMA 5:299–319, 2010), and knowledge structures were elicited as concept maps and essays and then analyzed using a graph-theoretic psychometric network scaling approach. Analysis of transcripts of the triad interactions showed a similar pattern of divergence and then convergence for the well-structured and the ill-structured problems that confirmed the previous investigations. As anticipated, interdependent triads performed relatively better on the ill-structured problem perhaps due to the extended divergence phase, while independent triads were better on the well-structured problem perhaps due to a rapid transition to the convergence phase. Knowledge structure analysis of group maps shows that the interdependent triad maps resembled the fully explicated problem space, while the independent triad maps most resembled the narrow problem solution space. Suggestions for practice include first increasing students’ awareness of divergent and convergent thinking, allowing enough time for the activity, and also requiring teams to submit a problem space artifact before working on a solution. Such skills are a basis for learning in school, but more importantly, will prepare students for a world where change is a constant and learning never stops. 

Droughts are projected to increase in intensity and frequency with the rise of global mean temperatures. However, not all drought indices equally capture the variety of influences that each hydrologic component has on the duration and magnitude of a period of water deficit. While such indices often agree with one another due to precipitation being the major input, heterogeneous responses caused by groundwater recharge, soil moisture memory, and vegetation dynamics may lead to a decoupling of identifiable drought conditions. As a semi-arid basin, the Limpopo River Basin (LRB) is a severely water-stressed region associated with unique climate patterns that regularly affect hydrological extremes. In this study, we find that vegetation indices show no significant long-term trends (S-statistic 9; p-value 0.779), opposing that of the modeled groundwater anomalies (S-statistic -57; p-value 0.05) in the growing season for a period of 18 years (2004–2022). Although the Mann-Kendall time series statistics for NDVI and drought indices are non-significant when basin-averaged, spatial heterogeneity further reveals that such a decoupling trend between vegetation and groundwater anomalies is indeed significant (p-value < 0.05) in colluvial, low-land aquifers to the southeast, while they remain more coupled in the central-west LRB, where more bedrock aquifers dominate. The conclusions of this study highlight the importance of ecological conditions with respect to water availability and suggest that water management must be informed by local vegetation species, especially in the face of depleting groundwater resources. 

Flexoelectricity in multilayer graphene (MLG) buckling can stimulate kink-shaped crinkle formation. In the process, the bifurcation becomes subcritical and the suspended-MLG’s crinkle curvature is localized to a narrow band of ∼2𝑛𝑚 width. We extend the study to flexoelectric layers bonded to a soft elastic substrate. Elastic substrates can guide the morphology of MLG and produce periodic patterns. We show that MLG’s flexoelectricity together with substrate elasticity can produce periodic crinkles, which qualitatively explains the grade-dependent mosaic spreading in highly oriented pyrolytic graphite (HOPG). Experimental measurements of HOPG’s surface-slope variations indeed confirm curvature localization at the crinkle valleys and ridges.