The precise determination of evapotranspiration rate is challenging because it is a quantity that is difficult to measure and to parametrize. Direct estimates include the determination of the change ...of mass of a volume of soil and vegetation that evapotranspirates using lysimeters, or direct measurements of turbulent water vapour fluxes by eddy-covariance systems. Parametrized estimates that make use of the Monin–Obukhov similarity theory use vertical gradient measurements of temperature and moisture at one point, and line or area averages by means of scintillometers operating at high frequency. A relation for the evapotranspiration from well-watered surfaces was initially developed by Penman and later expanded for vegetated surfaces and for heterogeneous croplands. A popular simplified expression was obtained by Priestley and Taylor. The current challenge is to find expressions for the evapotranspiration in non-saturated conditions, which are common in arid and semi-arid climates, and for heterogeneous terrain. In numerical models, the estimated actual evapotranspiration over land is obtained as the result of the explicit representation of the different involved sub-processes taking place in the soil and the canopy, using so-called land-surface models. Usually these mechanisms are described in a simplified manner and rely on a number of adjustable parameters. The improvement of such descriptions relies in the availability of experimental measurements to make the physical models more complete and robust.
The formation of neutrophil extracellular traps (NETs), known as NETosis, was first observed as a novel immune response to bacterial infection, but has since been found to occur abnormally in a ...variety of other inflammatory disease states including cancer. Breast cancer is the most commonly diagnosed malignancy in women. In breast cancer, NETosis has been linked to increased disease progression, metastasis, and complications such as venous thromboembolism. NET-targeted therapies have shown success in preclinical cancer models and may prove valuable clinical targets in slowing or halting tumor progression in breast cancer patients. We will briefly outline the mechanisms by which NETs may form in the tumor microenvironment and circulation, including the crosstalk between neutrophils, tumor cells, endothelial cells, and platelets as well as the role of cancer-associated extracellular vesicles in modulating neutrophil behavior and NET extrusion. The prognostic implications of cancer-associated NETosis will be explored in addition to development of novel therapeutics aimed at targeting NET interactions to improve outcomes in patients with breast cancer.
•State of the art in fast laboratory-based X-ray micro-computed tomography is outlined.•Real-time, pore-scale visualization of drainage in Bentheimer with lab-based scanner.•Solute transport is ...imaged at the pore scale in a limestone at 12 s per scan.
Over the past decade, the wide-spread implementation of laboratory-based X-ray micro-computed tomography (micro-CT) scanners has revolutionized both the experimental and numerical research on pore-scale transport in geological materials. The availability of these scanners has opened up the possibility to image a rock's pore space in 3D almost routinely to many researchers. While challenges do persist in this field, we treat the next frontier in laboratory-based micro-CT scanning: in-situ, time-resolved imaging of dynamic processes. Extremely fast (even sub-second) micro-CT imaging has become possible at synchrotron facilities over the last few years, however, the restricted accessibility of synchrotrons limits the amount of experiments which can be performed. The much smaller X-ray flux in laboratory-based systems bounds the time resolution which can be attained at these facilities. Nevertheless, progress is being made to improve the quality of measurements performed on the sub-minute time scale. We illustrate this by presenting cutting-edge pore scale experiments visualizing two-phase flow and solute transport in real-time with a lab-based environmental micro-CT set-up. To outline the current state of this young field and its relevance to pore-scale transport research, we critically examine its current bottlenecks and their possible solutions, both on the hardware and the software level. Further developments in laboratory-based, time-resolved imaging could prove greatly beneficial to our understanding of transport behavior in geological materials and to the improvement of pore-scale modeling by providing valuable validation.
Gastric adenocarcinoma (GC) is a devastating disease and is the third leading cause of cancer deaths worldwide. This heterogeneous disease has several different classification systems that consider ...histological appearance and genomic alterations. Understanding the etiology of GC, including infection, hereditary conditions, and environmental factors, is of particular importance and is discussed in this review. To improve survival in GC, we also must improve our therapeutic strategies. Here, we discuss new targets that warrant further exploration.
Freeze-thaw cycling stresses many environments which include porous media such as soil, rock and concrete. Climate change can expose new regions and subject others to a changing freeze-thaw ...frequency. Therefore, understanding and predicting the effect of freeze-thaw cycles is important in environmental science, the built environment and cultural heritage preservation. In this paper, we explore the possibilities of state-of-the-art micro-CT in studying the pore scale dynamics related to freezing and thawing. The experiments show the development of a fracture network in a porous limestone when cooling to -9.7 °C, at which an exothermal temperature peak is a proxy for ice crystallization. The dynamics of the fracture network are visualized with a time frame of 80 s. Theoretical assumptions predict that crystallization in these experiments occurs in pores of 6-20.1 nm under transient conditions. Here, the crystallization-induced stress exceeds rock strength when the local crystal fraction in the pores is 4.3%. The location of fractures is strongly related to preferential water uptake paths and rock texture, which are visually identified. Laboratory, continuous X-ray micro-CT scanning opens new perspectives for the pore-scale study of ice crystallization in porous media as well as for environmental processes related to freeze-thaw fracturing.
Weathering processes have been studied in detail for many natural building stones. The most commonly used analytical techniques in these studies are thin-section petrography, SEM, XRD and XRF. Most ...of these techniques are valuable for chemical and mineralogical analysis of the weathering patterns. However, to obtain crucial quantitative information on structural evolutions like porosity changes and growth of weathering crusts in function of time, non-destructive techniques become necessary. In this study, a Belgian historical calcareous sandstone, the Lede stone, was exposed to gaseous SO2 under wet surface conditions according to the European Standard NBN EN 13919 (2003). Before, during and after the strong acid test, high resolution X-ray tomography has been performed to visualize gypsum crust formation to yield a better insight into the effects of gaseous SO2 on the pore modification in 3D. The tomographic scans were taken at the Centre for X-ray Tomography at Ghent University (UGCT). With the aid of image analysis, partial porosity changes were calculated in different stadia of the process. Increasing porosity has been observed visually and quantitatively below the new superficial formed layer of gypsum crystals. In some cases micro-cracks and dissolution zones were detected on the grain boundaries of quartz. By using Morpho+, an in-house developed image analysis program, radial porosity, partial porosity, ratio of open and closed porosity and equivalent diameter of individual pore structures have been calculated. The results obtained in this study are promising for a better understanding of gypsum weathering mechanisms, porosity changes and patterns on natural building stones in four dimensions.
► We examine structural 3D differences inside building stones as a function of time. ► Gypsum crust formation is quantified with X-ray CT in combination with image analysis. ► The amount of pores smaller than 100μm increases after weathering with SO2. ► A dissolution zone does appear 200μm below the crust.
The Surface Monitoring Of the Soil Reservoir Experiment (SMOSREX) site is used in this study to evaluate the performance of the Interaction between Soil Biosphere Atmosphere soil multilayer diffusion ...scheme (ISBA‐DF) in reproducing short‐term and long‐term evolution of soil moisture and temperature profiles, surface energy fluxes, and drainage rate using both the Brooks and Corey and the van Genuchten models describing soil‐water retention and conductivity curves. The site consists of a fallow field in southwestern France where intensive measurements were made during the 2001–2007 period. Two sets of four simulations describing homogeneous and heterogeneous soil properties are performed using four continuous pedotransfer functions. ISBA‐DF is also compared with the ISBA “force‐restore” soil scheme (ISBA‐FR) since this version is currently used in several meteorological, hydrological, and/or climate applications. ISBA‐DF exhibits a good performance in terms of simulating the soil moisture profile and the surface energy fluxes, especially when heterogeneous soil properties are considered. Its soil moisture dynamic does not depend on the field capacity, which is a clear advantage compared with ISBA‐FR. However, it shows some drawbacks in simulating the surface temperature. The Brooks and Corey model exhibits the best skill scores in simulating the soil moisture profile and the surface fluxes compared with the van Genuchten model. Nevertheless, the differences are not significant, and the results on a single site reduce the generality of this intercomparison. Finally, two additional sets of experiments are performed to assess the scheme sensitivity to increasing soil depth and to the soil vertical discretization.
Key Points
Soil diffusion scheme
Pedotransfer function sensitivity
Soil vertical configurations sensitivity
Detailed studies of snow cover processes require models that offer a fine description of the snow cover properties. The detailed snowpack model Crocus is such a scheme, and has been run operationally ...for avalanche forecasting over the French mountains for 20 yr. It is also used for climate or hydrological studies. To extend its potential applications, Crocus has been recently integrated within the framework of the externalized surface module SURFEX. SURFEX computes the exchanges of energy and mass between different types of surface and the atmosphere. It includes in particular the land surface scheme ISBA (Interactions between Soil, Biosphere, and Atmosphere). It allows Crocus to be run either in stand-alone mode, using a time series of forcing meteorological data or in fully coupled mode (explicit or fully implicit numerics) with atmospheric models ranging from meso-scale models to general circulation models. This approach also ensures a full coupling between the snow cover and the soil beneath. Several applications of this new simulation platform are presented. They range from a 1-D stand-alone simulation (Col de Porte, France) to fully-distributed simulations in complex terrain over a whole mountain range (Massif des Grandes Rousses, France), or in coupled mode such as a surface energy balance and boundary layer simulation over the East Antarctic Ice Sheet (Dome C).
Neutrophil extracellular traps (NETs) are formed when neutrophils expel their DNA, histones and intracellular proteins into the extracellular space or circulation. NET formation is dependent on ...autophagy and is mediated by citrullination of histones to allow for the unwinding and subsequent expulsion of DNA. NETs have an important role in the pathogenesis of several sterile inflammatory diseases, including malignancy, therefore we investigated the role of NETs in the setting of pancreatic ductal adenocarcinoma (PDA). Neutrophils isolated from two distinct animal models of PDA had an increased propensity to form NETs following stimulation with platelet activating factor (PAF). Serum DNA, a marker of circulating NET formation, was elevated in tumor bearing animals as well as in patients with PDA. Citrullinated histone H3 expression, a marker of NET formation, was observed in pancreatic tumors obtained from murine models and patients with PDA. Inhibition of autophagy with chloroquine or genetic ablation of receptor for advanced glycation end products (RAGE) resulted in decreased propensity for NET formation, decreased serum DNA and decreased citrullinated histone H3 expression in the pancreatic tumor microenvironment. We conclude that NETs are upregulated in pancreatic cancer through RAGE-dependent/autophagy mediated pathways.
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