Understanding the evolution of sediment connectivity associated with different land use and topographic changes is a prerequisite for a better understanding of sediment budgets and sediment transport ...processes. We used the Index of Sediment Connectivity (IC) developed by Cavalli et al. (2013) based on the original approach by Borselli et al. (2008) to study the effects of decadal-scale land use and topographic changes on sediment connectivity in mountain catchments. The input variables of the IC (i.e. land cover and topography) were derived from historical aerial photos using Structure from Motion-Multi View Stereo algorithms (SfM-MVS). The method was applied in different sub-catchments of the Upper River Cinca Catchment (Central Pyrenees), representative of three scenarios: (a) Land cover changes; (b) Topographic changes in agricultural fields (terracing); and (c) Topographic changes associated with infrastructure (road construction). In terms of land cover changes, results show that although connectivity is increased in some areas due to the establishment of new field crops, for most of the study area connectivity decreased due to afforestation caused by rural abandonment. Topographic changes due to the establishment of agricultural terraces affected connectivity to a larger degree than land cover changes. Terracing generally reduced connectivity due to the formation of flat areas in step-slopes, but in certain points, an increase in connectivity caused by the topographic convergence produced by terraces was observed. Finally, topographic changes associated with road construction greatly modified surface flow directions and the drainage network, resulting in changes in connectivity that may affect erosional processes nearby. The methodology used in this paper allows to study the effects of real decadal-scale land use and topographic changes on sediment connectivity and also evaluating and disentangling those changes. Furthermore, this approach can be a useful tool to identify potential risks associated with morphological and land use changes, involving road infrastructures.
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•Land cover changes have a direct effect on sediment connectivity.•Changes caused by terraces are inferred from the recreation of the terrain without these structures.•Terraces had a larger impact on sediment connectivity than land use change.•The Index of Connectivity is a useful tool to map hot spots in areas where roads are constructed.•Changes on historical sediment connectivity may help understanding catchment-scale sediment supply dynamics.
Human glioblastomas harbour a subpopulation of glioblastoma stem cells that drive tumorigenesis. However, the origin of intratumoural functional heterogeneity between glioblastoma cells remains ...poorly understood. Here we study the clonal evolution of barcoded glioblastoma cells in an unbiased way following serial xenotransplantation to define their individual fate behaviours. Independent of an evolving mutational signature, we show that the growth of glioblastoma clones in vivo is consistent with a remarkably neutral process involving a conserved proliferative hierarchy rooted in glioblastoma stem cells. In this model, slow-cycling stem-like cells give rise to a more rapidly cycling progenitor population with extensive self-maintenance capacity, which in turn generates non-proliferative cells. We also identify rare 'outlier' clones that deviate from these dynamics, and further show that chemotherapy facilitates the expansion of pre-existing drug-resistant glioblastoma stem cells. Finally, we show that functionally distinct glioblastoma stem cells can be separately targeted using epigenetic compounds, suggesting new avenues for glioblastoma-targeted therapy.
Study of the origin and development of cerebellar tumours has been hampered by the complexity and heterogeneity of cerebellar cells that change over the course of development. Here we use single-cell ...transcriptomics to study more than 60,000 cells from the developing mouse cerebellum and show that different molecular subgroups of childhood cerebellar tumours mirror the transcription of cells from distinct, temporally restricted cerebellar lineages. The Sonic Hedgehog medulloblastoma subgroup transcriptionally mirrors the granule cell hierarchy as expected, while group 3 medulloblastoma resembles Nestin
stem cells, group 4 medulloblastoma resembles unipolar brush cells, and PFA/PFB ependymoma and cerebellar pilocytic astrocytoma resemble the prenatal gliogenic progenitor cells. Furthermore, single-cell transcriptomics of human childhood cerebellar tumours demonstrates that many bulk tumours contain a mixed population of cells with divergent differentiation. Our data highlight cerebellar tumours as a disorder of early brain development and provide a proximate explanation for the peak incidence of cerebellar tumours in early childhood.
Understanding the interactions between the anthroposphere and the geosphere, such as natural hazards, land degradation, quantitative and qualitative impacts on ground and surface waters, is a ...challenging task. The monitoring and modelling of these interactions can be characterized by high uncertainties in data and models, especially when considering urban areas or locations near engineering infrastructures. Technological and scientific advancements, including remote sensing, geophysical prospecting, drilling equipment, and information technology, have contributed to enhancing our current understanding of these interconnected dynamics. The availability of increasingly large datasets provides better insights into the mechanisms that govern these interactions, but it also adds complexity to monitoring, modeling, and forecasting procedures. From this viewpoint, the utilization of advanced geocomputational methodologies, such as machine learning, geostatistics, pattern recognition, geomorphometry, and other computational-based approaches, plays a pivotal role.
Research suggests emotion dysregulation is a transdiagnostic risk factor for substance use and addiction and that stress may lead to problematic cannabis use. Thus, the current study examines how ...emotion dysregulation moderates the associations between stress (stressful life events and perceived stress) and problematic cannabis use.
Eight hundred and fifty-two adults reporting any lifetime cannabis use completed an anonymous online survey. Participants completed a brief demographic questionnaire and were asked to report their past 30-day use of cannabis, alcohol, nicotine, and illicit substances. Problematic cannabis use (
the Marijuana Problem Scale), emotion dysregulation (
the Difficulties in Emotion Regulation Scale), perceived stress (
the Perceived Stress Scale), and stressful life events (
the Holmes-Rahe Life Stress Inventory) were assessed. Hierarchical multiple linear regressions were conducted.
Findings indicate that when examining the moderating role of emotion dysregulation, more stressful life events and less perceived stress were associated with more severe problematic cannabis use, and these associations were stronger at higher levels of emotion dysregulation.
These results demonstrate a strong step toward understanding how emotion dysregulation moderates the relationship between stress and problematic cannabis use; however, longitudinal studies are needed to determine directionality of effects. Overall, these results suggest the importance of examining emotion dysregulation as a moderator of both stressful life events and stress perception as they relate to problematic cannabis use.
Through hyperacetylation of histone H4 lysine 16 (H4K16), the male-specific lethal (MSL) complex in Drosophila approximately doubles transcription from the single male X chromosome in order to match ...X-linked expression in females and expression from diploid autosomes. By obtaining accurate measurements of RNA polymerase II (Pol II) occupancies and short promoter-proximal RNA production, we detected a consistent, genome-scale increase in Pol II activity at the promoters of male X-linked genes. Moreover, we found that enhanced Pol II recruitment to male X-linked promoters is largely dependent on the MSL complex. These observations provide insights into how global modulation of chromatin structure by histone acetylation contributes to the precise control of Pol II function.
Research on factors affecting sediment regime in glacierized catchments under warming climates is still scarce despite its societal relevance. In particular, coarse bedload transport has never been ...quantitatively related to water runoff origin (snowmelt vs glacier melt), which provides important information on the role of different sediment sources (glaciers vs hillslopes and channel bed). Drawing on data from multiple spatial and temporal scales in a paradigmatic Alpine glacierized catchment, we show that glacier melt flows play a key role in coarse sediment transport dynamics. Bedload concentration measured during glacier melt flows is up to 6 orders of magnitude larger than during snowmelt. At the catchment scale and within the channel, however, minimal aggradation and degradation was detected over almost a decade. In addition, sedimentation rates at a hydropower weir, inferred from flushing frequency during the last four decades, are tightly associated to summer air temperature and not to precipitation trends, and most of sediment export occurred in July-August. However, sediment flushing frequency has been decreasing since the late 1990s despite very warm summers in the following decades. Collectively, these findings indicate that sediment is dominantly sourced from within glacier-covered areas and that transport rates are thus dictated by seasonal and multi-annual glacial dynamics. As glacier melt flows decrease due to ice mass loss, our results suggest that, for similar basins, a progressive shift from supply-limited (driven by glacier activity) to transport-limited (during rainfall-induced events) sediment transport will occur, disrupting the current near-equilibrium channel conditions.
•Hydrograph separation coupled to bedload measurements in a glacierized catchment.•Bedload during glacier melt up to 6 orders of magnitude larger than during snowmelt.•Decadal channel bed equilibrium despite large bedload yields from glaciers.•Sediment export statistically related to summer air temperatures and not to precipitation.•Sediment export peaked in late 1990s despite rising temperatures in 21st century.
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