Karst regions represent 7–12% of the Earth's continental area, and about one quarter of the global population is completely or partially dependent on drinking water from karst aquifers. Climate ...simulations project a strong increase in temperature and a decrease of precipitation in many karst regions in the world over the next decades. Despite this potentially bleak future, few studies specifically quantify the impact of climate change on karst water resources. This review provides an introduction to karst, its evolution, and its particular hydrological processes. We explore different conceptual models of karst systems and how they can be translated into numerical models of varying complexity and therefore varying data requirements and depths of process representation. We discuss limitations of current karst models and show that at the present state, we face a challenge in terms of data availability and information content of the available data. We conclude by providing new research directions to develop and evaluate better prediction models to address the most challenging problems of karst water resources management, including opportunities for data collection and for karst model applications at so far unprecedented scales.
Key Points
We elaborate the importance of karst water resourcesWe provide a detailed overview of karst modeling approachWe present new methods and directions for their improvement
The “at risk mental state” for psychosis approach has been a catalytic, highly productive research paradigm over the last 25 years. In this paper we review that paradigm and summarize its key ...lessons, which include the valence of this phenotype for future psychosis outcomes, but also for comorbid, persistent or incident non‐psychotic disorders; and the evidence that onset of psychotic disorder can at least be delayed in ultra high risk (UHR) patients, and that some full‐threshold psychotic disorder may emerge from risk states not captured by UHR criteria. The paradigm has also illuminated risk factors and mechanisms involved in psychosis onset. However, findings from this and related paradigms indicate the need to develop new identification and diagnostic strategies. These findings include the high prevalence and impact of mental disorders in young people, the limitations of current diagnostic systems and risk identification approaches, the diffuse and unstable symptom patterns in early stages, and their pluripotent, transdiagnostic trajectories. The approach we have recently adopted has been guided by the clinical staging model and adapts the original “at risk mental state” approach to encompass a broader range of inputs and output target syndromes. This approach is supported by a number of novel modelling and prediction strategies that acknowledge and reflect the dynamic nature of psychopathology, such as dynamical systems theory, network theory, and joint modelling. Importantly, a broader transdiagnostic approach and enhancing specific prediction (profiling or increasing precision) can be achieved concurrently. A holistic strategy can be developed that applies these new prediction approaches, as well as machine learning and iterative probabilistic multimodal models, to a blend of subjective psychological data, physical disturbances (e.g., EEG measures) and biomarkers (e.g., neuroinflammation, neural network abnormalities) acquired through fine‐grained sequential or longitudinal assessments. This strategy could ultimately enhance our understanding and ability to predict the onset, early course and evolution of mental ill health, further opening pathways for preventive interventions.
The vast majority of the brain's vascular length is composed of capillaries, where our understanding of blood flow control remains incomplete. This review synthesizes current knowledge on the control ...of blood flow across microvascular zones by addressing issues with nomenclature and drawing on new developments from in vivo optical imaging and single-cell transcriptomics. Recent studies have highlighted important distinctions in mural cell morphology, gene expression, and contractile dynamics, which can explain observed differences in response to vasoactive mediators between arteriole, transitional, and capillary zones. Smooth muscle cells of arterioles and ensheathing pericytes of the arteriole-capillary transitional zone control large-scale, rapid changes in blood flow. In contrast, capillary pericytes downstream of the transitional zone act on slower and smaller scales and are involved in establishing resting capillary tone and flow heterogeneity. Many unresolved issues remain, including the vasoactive mediators that activate the different pericyte types in vivo, the role of pericyte-endothelial communication in conducting signals from capillaries to arterioles, and how neurological disease affects these mechanisms.
Ultrafast laser techniques have revealed extraordinary spin dynamics in magnetic materials that equilibrium descriptions of magnetism cannot explain. Particularly important for future applications is ...understanding non-equilibrium spin dynamics following laser excitation on the nanoscale, yet the limited spatial resolution of optical laser techniques has impeded such nanoscale studies. Here we present ultrafast diffraction experiments with an X-ray laser that probes the nanoscale spin dynamics following optical laser excitation in the ferrimagnetic alloy GdFeCo, which exhibits macroscopic all-optical switching. Our study reveals that GdFeCo displays nanoscale chemical and magnetic inhomogeneities that affect the spin dynamics. In particular, we observe Gd spin reversal in Gd-rich nanoregions within the first picosecond driven by the non-local transfer of angular momentum from larger adjacent Fe-rich nanoregions. These results suggest that a magnetic material's microstructure can be engineered to control transient laser-excited spins, potentially allowing faster (~ 1 ps) spin reversal than in present technologies.
Smooth muscle cells and pericytes, together called mural cells, coordinate many distinct vascular functions. Canonically, smooth muscle cells are ring-shaped and cover arterioles with circumferential ...processes, whereas pericytes extend thin processes that run longitudinally along capillaries. In between these canonical mural cell types are cells with features of both smooth muscle cells and pericytes. Recent studies suggest that these transitional cells are critical for controlling blood flow to the capillary bed during health and disease, but there remains confusion on how to identify them and where they are located in the brain microvasculature. To address this issue, we measured the morphology, vascular territory, and α-smooth muscle actin content of structurally diverse mural cells in adult mouse cortex. We first imaged intact 3D vascular networks to establish the locations of major gradations in mural cell appearance as arterioles branched into capillaries. We then imaged individual mural cells occupying the regions within these gradations. This revealed two transitional cells that were often similar in appearance, but with sharply contrasting levels of α-smooth muscle actin. Our findings highlight the diversity of mural cell morphologies in brain microvasculature, and provide guidance for identification and categorization of mural cell types.
Integration of the abundant information derived from different sources, characterizing techniques and modeling methodologies, is crucial for extending our knowledge of karst aquifers and their ...available water resources. In this work, a numerically based approach derived from an improved version of the lumped VarKarst model is proposed, which jointly considers spring discharge and dye test results in calibration routine, to assess independently the contribution of the allogenic and autogenic components to the total recharge of a complex karst system with proved duality in its recharge mechanisms. A newly developed parameter estimation procedure based on rather soft performance rules is employed to confine the uncertainty of the water budget previously obtained with two other independent methods (Soil Water Balance and APLIS). Unlike other methodologies that lead to semiquantitative estimations of input sources, results from our approach display reliable ranges of calibrated values for recharge rate, recharge area, and, to a lesser extent, for water runoff infiltration coming from the streamflow. The integration of all these quantitative results with data (qualitative) previously derived from other experimental methodologies has meant a significant advance in understanding the behavior of the pilot system, allowing a more realistic and robust conceptual model to be developed. We conclude by emphasizing that a continuous transfer of improvements from conceptual to numerical modeling approaches, and vice versa, is necessary to enhance knowledge of carbonate aquifer functioning and ultimately achieve better evaluation and management of water resources. During this process, frequent mutual evaluation between the modeling approaches must be performed.
Key Points
The lumped VarKarst model is used to assess allogenic and autogenic contributions to the recharge of karst systems
Coupling field data by a new estimation parameter procedure serves to confine ambiguity of the water budget estimated with two other methods
Mutual evaluation between conceptual and numerical modeling approaches must be constantly conducted to enhance knowledge of karst systems
•U-Pb dating of Tonian zircon from albitites in the Brasiliano Orogen.•Positive εHf, Hf TDM and 176Hf/177Hf of zircon indicate magma provenance from a depleted mantle.•Composition of zircon cores and ...rims display different REE including Lu.•New metamorphic zircon grew with different Lu/Hf.
U-Pb and Lu-Hf isotopic analyses of zircon from albitites, southern Brasiliano Orogen, indicate Neoproterozoic ages for two ophiolites. The difficulty of dating ophiolites is overcome by finding zircon in albitites contained in serpentinite. Two key areas were selected for the study, the Cerro Mantiqueiras and the Ibaré ophiolites, both in the juvenile São Gabriel terrane, Rio Grande do Sul, Brazil. Two distinct U-Pb SHRIMP ages are registered in the Cerro Mantiqueiras ophiolite zircons, respectively 923±3Ma in the cores and 786±13Ma in the rims. In the Ibaré ophiolite, the dating of zircon grains resulted in a single age of 892±3Ma. Distinctive depleted mantle Hf isotope signatures characterize the zircons; in the Cerro Mantiqueiras sample, εHf=+8 to +13 and Hf TDM=0.91–1.23Ga, whereas the Ibaré sample displays εHf=+13 to +15 and Hf TDM=0.75–0.93Ga. Ophiolite accretion in the São Gabriel terrane of the southern Brasiliano Orogen occurred in the Tonian, which establishes the age of a significant event in the tectonic evolution of the continent. The Hf data indicate that the ophiolites were derived from juvenile depleted mantle. This first direct dating of ophiolites sets new limits to the evolution of the Brasiliano Orogen.
Distributions of the size of the largest component, in particular the large-deviation tail, are studied numerically for two graph ensembles, for Erdös-Rényi random graphs with finite connectivity and ...for two-dimensional bond percolation. Probabilities as small as 10
-180
are accessed using an artificial finite-temperature (Boltzmann) ensemble. The distributions for the Erdös-Rényi ensemble agree well with previously obtained analytical results. The results for the percolation problem, where no analytical results are available, are qualitatively similar, but the shapes of the distributions are somehow different and the finite-size corrections are sometimes much larger. Furthermore, for both problems, a first-order phase transition at low temperatures
T
within the artificial ensemble is found in the percolating regime, respectively.
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