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A recent global meta‐analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns with the meta‐analysis and suggest that these account for the discrepancy with the declines reported elsewhere. First, total abundance and biomass alone are poor indicators of the status of freshwater insect assemblages, and the observed differences may well have been driven by the replacement of sensitive species with tolerant ones. Second, many of the datasets poorly represent global trends and reflect responses to local conditions or nonrandom site selection. We conclude that the results of the meta‐analysis should not be considered indicative of an overall improvement in the condition of freshwater ecosystems.
ISOE-Newsletter 01/2021
(2021)
Background: The aim of this study was to evaluate post‐irradiation changes in the central nervous system (CNS) detected using magnetic resonance (MR) imaging.
Methods: Magnetic resonance images of 15 children with CNS tumors treated through whole‐brain irradiation over 10 years were reviewed retrospectively. Variables such as age at the time of irradiation, total radiation dose, treatment length, and time interval between irradiation and MR changes, were evaluated.
Results: All patients included in the study had imaging abnormalities of the CNS. Eight patients (53%) developed CNS abnormalities within a short period of time – only a few months after irradiation (mean 4.8 months). Seven patients (47%) developed CNS abnormalities within a long time interval after treatment (mean 4.6 years). In almost all patients, a T2 increase in supra‐ and infratentorial white matter was observed. Follow‐up examinations showed nine patients (60%) with cerebellar atrophy.
Conclusions: In this sample of pediatric patients who underwent whole‐brain irradiation, the time receiving irradiation was not related to the severity of the MR changes. A correlation between the age of the child or the length of the radiotherapy and the extent of the changes could not be confirmed. However, we observed a trend towards stronger brain parenchymal degeneration with cystic changes in the younger age group of children in our sample. Older children who received irradiation seem to be more susceptible to vascular dysplasia with cavernous hemangiomas and microbleeding.
Abstract
The mineralogy, chemical composition, and physical properties of cratonic mantle eclogites with oceanic crustal protoliths can be modified by secondary processes involving interaction with fluids and melts, generated in various slab lithologies upon subduction (auto‐metasomatism) or mantle metasomatism after emplacement into the cratonic lithosphere. Here we combine new and published data to isolate these signatures and evaluate their effects on the chemical and physical properties of eclogite. Mantle metasomatism involving kimberlite‐like, ultramafic carbonated melts (UM carbonated melts) is ubiquitous though not pervasive, and affected between ~20% and 40% of the eclogite population at the various localities investigated here, predominantly at ~60–150 km depth, overlapping cratonic midlithospheric seismic discontinuities. Its hallmarks include lower jadeite component in clinopyroxene and grossular component in garnet, an increase in bulk‐rock MgO ± SiO2, and decrease in FeO and Al2O3 contents, and LREE‐enrichment accompanied by higher Sr, Pb, Th, U, and in part Zr and Nb, as well as lower Li, Cu ± Zn. This is mediated by addition of a high‐temperature pyroxene from a UM carbonated melt, followed by redistribution of this component into garnet and clinopyroxene. As clinopyroxene‐garnet trace‐element distribution coefficients increase with decreasing garnet grossular component, clinopyroxene is the main carrier of the metasomatic signatures. UM carbonated melt‐metasomatism at >130–150 km has destroyed the diamond inventory at some localities. These mineralogical and chemical changes contribute to low densities, with implications for eclogite gravitational stability, but negligible changes in shear‐wave velocities, and, if accompanied by H2O‐enrichment, will enhance electrical conductivities compared to unenriched eclogites.
Plain Language Summary
Oceanic crust formed at spreading ridges is recycled in subduction zones and undergoes metamorphism to eclogite. Some of this material is captured in the overlying lithospheric mantle, where it is exhumed by passing magmas. Having formed in spreading ridges, these eclogites have proven invaluable archives for the onset of plate tectonics, for the construction of cratons during subduction/collision, as probes of the convecting mantle from which their precursors formed, and as generators of heterogeneity upon recycling into Earth's convecting mantle. During subduction and until exhumation, interaction with fluids and melts (called metasomatism) can change the mineralogy, chemical composition, and physical properties of mantle eclogites, complicating their interpretation, but a comprehensive study of these effects is lacking so far. We investigated mantle eclogites from ancient continents (cratons) around the globe in order to define hallmarks of metasomatism by subduction‐related fluids and small‐volume ultramafic carbonated mantle melts. We find that the latter is pervasive and occurs predominantly at midlithospheric depths where seismic discontinuities are detected, typically causing diamond destruction and a reduction in density. This has consequences for their gravitational stability and for the interpretation of shearwave velocities in cratons.
Primary determinants of communities in deadwood vary among taxa but are regionally consistent
(2020)
The evolutionary split between gymnosperms and angiosperms has far‐reaching implications for the current communities colonizing trees. The inherent characteristics of dead wood include its role as a spatially scattered habitat of plant tissue, transient in time. Thus, local assemblages in deadwood forming a food web in a necrobiome should be affected not only by dispersal ability but also by host tree identity, the decay stage and local abiotic conditions. However, experiments simultaneously manipulating these potential community drivers in deadwood are lacking. To disentangle the importance of spatial distance and microclimate, as well as host identity and decay stage as drivers of local assemblages, we conducted two consecutive experiments, a 2‐tree species and 6‐tree species experiment with 80 and 72 tree logs, respectively, located in canopy openings and under closed canopies of a montane and a lowland forest. We sampled saproxylic beetles, spiders, fungi and bacterial assemblages from logs. Variation partitioning for community metrics based on a unified framework of Hill numbers showed consistent results for both studies: host identity was most important for sporocarp‐detected fungal assemblages, decay stage and host tree for DNA‐detected fungal assemblages, microclimate and decay stage for beetles and spiders and decay stage for bacteria. Spatial distance was of minor importance for most taxa but showed the strongest effects for arthropods. The contrasting patterns among the taxa highlight the need for multi‐taxon analyses in identifying the importance of abiotic and biotic drivers of community composition. Moreover, the consistent finding of microclimate as the primary driver for saproxylic beetles compared to host identity shows, for the first time that existing evolutionary host adaptions can be outcompeted by local climate conditions in deadwood.
Background: Conditions during blood product storage and transportation should maintain quality. The aim of this in vitro study was to investigate the effect of interruption of agitation, temporary cooling (TC), and pneumatic tube system transportation (PTST) on the aggregation ability (AA) and mitochondrial function (MF) of platelet concentrates (PC).
Study Design and Methods: A PC was divided equally into four subunits and then allocated to four test groups. The control group (I) was stored as recommended (continuous agitation, 22 ± 2°C) for 4 days. The test groups were stored without agitation (II), stored as recommended, albeit 4°C for 60 minutes on day (d)2 (III) and PTST (IV). Aggregometry was measured using Multiplate (RocheAG; ADPtest, ASPItest, TRAPtest, COLtest) and MF using Oxygraph‐2k (Oroboros Instruments). The basal and maximum mitochondrial respiratory rate (MMRR) were determined. AA and MF were measured daily in I and II and AA in III and IV on d2 after TC/PTST. Statistical analysis was performed using tests for matched observations.
Results: Eleven PCs were used. TRAP‐6 induced AA was significantly lower in II when compared to I on d4 (P = 0.015*). In III the ASPItest was significantly lower (P = 0.032*). IV showed no significant differences. The basal and MMRR were significantly reduced over 4 days in I and II (for both rates in both groups: P = <0.0001*). No significant differences occurred on d4 (P = 0.495).
Conclusion: Our results indicate that ex vivo AA and MF of PCs are unaffected, even in no‐ideal storage and transport circumstances with respect to agitation, temperature, and force.
We analyze limit order book resiliency following liquidity shocks initiated by large market orders. Based on a unique data set, we investigate whether high‐frequency traders are involved in replenishing the order book. Therefore, we relate the net liquidity provision of high‐frequency traders, algorithmic traders, and human traders around these market impact events to order book resiliency. Although all groups of traders react, our results show that only high‐frequency traders reduce the spread within the first seconds after the market impact event. Order book depth replenishment, however, takes significantly longer and is mainly accomplished by human traders’ liquidity provision.
Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that is accompanied by neurodevelopmental differences in regional cortical volume (CV), and a potential layer‐specific pathology. Conventional measures of CV, however, do not indicate how volume is distributed across cortical layers. In a sample of 92 typically developing (TD) controls and 92 adult individuals with ASD (aged 18–52 years), we examined volumetric gradients by quantifying the degree to which CV is weighted from the pial to the white surface of the brain. Overall, the spatial distribution of Frustum Surface Ratio (FSR) followed the gyral and sulcal pattern of the cortex and approximated a bimodal Gaussian distribution caused by a linear mixture of vertices on gyri and sulci. Measures of FSR were highly correlated with vertex‐wise estimates of mean curvature, sulcal depth, and pial surface area, although none of these features explained more than 76% variability in FSR on their own. Moreover, in ASD, we observed a pattern of predominant increases in the degree of FSR relative to TD controls, with an atypical neurodevelopmental trajectory. Our findings suggest a more outward‐weighted gradient of CV in ASD, which may indicate a larger contribution of supragranular layers to regional differences in CV.