Potential drought stress in a Swiss mountain catchment-Ensemble forecasting of high mountain soil moisture reveals a drastic decrease, despite major uncertainties

Climate change is expected to profoundly influence the hydrosphere of mountain ecosystems. The focus of current process-based research is centered on the reaction of glaciers and runoff to climate change; spatially explicit impacts on soil moisture remain widely neglected. We spatio-temporally analyzed the impact of the climate on soil moisture in a mesoscale high mountain catchment to facilitate the development of mitigation and adaptation strategies at the level of vegetation patterns. Two regional climate models were downscaled using three different approaches (statistical downscaling, delta change, and direct use) to drive a hydrological model (WaSiM-ETH) for reference and scenario period (1960–1990 and 2070–2100), resulting in an ensemble forecast of six members. For all ensembles members we found large changes in temperature, resulting in decreasing snow and ice storage and earlier runoff, but only small changes in evapotranspiration. The occurrence of downscaled dry spells was found to fluctuate greatly, causing soil moisture depletion and drought stress potential to show high variability in both space and time. In general, the choice of the downscaling approach had a stronger influence on the results than the applied regional climate model. All of the results indicate that summer soil moisture decreases, which leads to more frequent declines below a critical soil moisture level and an advanced evapotranspiration deficit. Forests up to an elevation of 1800 m a.s.l. are likely to be threatened the most, while alpine areas and most pastures remain nearly unaffected. Nevertheless, the ensemble variability was found to be extremely high and should be interpreted as a bandwidth of possible future drought stress situations.

Rapid responses of high-mountain vegetation to early Holocene environmental changes in the Swiss Alps

1 The Early Holocene sediment of a lake at tree line (Gouillé Rion, 2343 m a.s.l.) in the Swiss Central Alps was sampled for plant macrofossils. Thin (0.5 cm) slices, representing time intervals of c. 50 years each from 11 800 to 7800 cal. year bp, were analysed and the data compared with independent palaeoclimatic proxies to study vegetational responses to environmental change. 2 Alpine plant communities (e.g. with Salix herbacea) were established at 11 600–11 500 cal. year bp, when oxygen-isotope records showed that temperatures increased by c. 3–4 °C within decades. Larix decidua trees reached the site at c. 11 350 cal. year bp, probably in response to further warming by 1–2 °C. Forests dominated by L. decidua persisted until 9600 cal. year bp, when Pinus cembra became more important. 3 The dominance of Larix decidua for two millennia is explained by dry summer conditions, and possibly low winter temperatures, which favoured it over the late-successional Pinus cembra. Environmental conditions were a result of variations in the earth's orbit, leading to a maximum of summer and a minimum of winter solar radiation. Other heliophilous and drought-adapted species, such as Dryas octopetala and Juniperus nana, could persist in the open L. decidua forests, but were out-competed when the shade-tolerant P. cembra expanded. 4 The relative importance of Larix decidua decreased during periods of diminished solar radiation at 11 100, 10 100 and 9400 cal. year bp. Stable concentrations of L. decidua indicate that these percentage oscillations were caused by temporary increases of Pinus cembra, Dryas octopetala and Juniperus nana that can be explained by increases in moisture and/or decreases in summer temperature. 5 The final collapse of Larix decidua at 8400 cal. year bp was possibly related to abrupt climatic cooling as a consequence of a large meltwater input to the North Atlantic. Similarly, the temporary exclusion of Pinus cembra from tree line at 10 600–10 200 cal. year bp may be related to slowing down of thermohaline circulation at 10 700–10 300 cal. year bp. 6 Our results show that tree line vegetation was in dynamic equilibrium with climate, even during periods of extraordinarily rapid climatic change. They also imply that forecasted global warming may trigger rapid upslope movements of the tree line of up to 800 m within a few decades or centuries at most, probably inducing large-scale displacements of plant species as well as irrecoverable biodiversity losses.

The evolution of high-temperature mylonitic microfabrics: evidence from simple shearing of a quartz analogue (norcamphor)

Plane strain simple shearing of norcamphor (C7H10O) in a see-through deformation rig to a shear strain of γ = 10.5 at a homologous temperature of Th = 0.81 yields a microfabric similar to that of quartz in amphibolite facies mylonite. Synkinematic analysis of the norcamphor microfabric reveals that the development of a steady-state texture is linked to changes in the relative activities of several grain-scale mechanisms. Three stages of textural and microstructural evolution are distinguished: (1) rotation and shearing of the intracrystalline glide planes are accommodated by localized deformation along three sets of anastomozing microshears. A symmetrical c-axis girdle reflects localized pure shear extension along the main microshear set (Sa) oblique to the bulk shear zone boundary (abbreviated as SZB); (2) progressive rotation of the microshears into parallelism with the SZB increases the component of simple shear on the Sa microshears. Grain-boundary migration recrystallization favours the survival of grains with slip systems oriented for easy glide. This is associated with a textural transition towards two stable c-axis point maxima whose skeletal outline is oblique with respect to the Sa microshears and the SZB; and (3) at high shear strains (γ > 8), the microstructure, texture and mechanism assemblage are strain invariant, but strain continues to partition into rotating sets of microshears. Steady state is therefore a dynamic, heterogeneous condition involving the cyclic nucleation, growth and consumption of grains.

Peri-ictal correlation dynamics of high-frequency (80-200 Hz) intracranial EEG

To assess (1) how large-scale correlation of intracranial EEG signals in the high-frequency range (80-200Hz) evolves from the pre-ictal, through the ictal into the postictal state and (2) whether the contribution of local neuronal activity to large-scale EEG correlation differentiates epileptogenic from non-epileptogenic brain tissue.

Oncocytic ependymoma: a new morphological variant of high-grade ependymal neoplasm composed of mitochondrion-rich epithelioid cells

Oncocytomas are defined as tumors containing in excess of 50% large mitochondrion-rich cells, irrespective of histogenesis and dignity. Along the central neuraxis, oncocytomas are distinctly uncommon but relevant to the differential diagnosis of neoplasia marked by prominent cytoplasmic granularity. We describe an anaplastic ependymoma (WHO grade III) with a prevailing oncocytic component that was surgically resected from the right fronto-insular region of a 43-year-old female. Preoperative imaging showed a fairly circumscribed, partly cystic, contrast-enhancing mass of 2 cm × 2 cm × 1.7 cm. Histology revealed a biphasic neoplasm wherein conventional ependymal features coexisted with plump epithelioid cells replete with brightly eosinophilic granules. Whereas both components displayed an overtly ependymal immunophenotype, including positivity for S100 protein and GFAP, as well as "dot-like" staining for EMA, the oncocytic population also tended to intensely react with the antimitochondrial antibody 113-1. Conversely, failure to bind CD68 indicated absence of significant lysosomal storage. Negative reactions for both pan-cytokeratin (MNF 116) and low molecular weight cytokeratin (CAM 5.2), as well as synaptophysin and thyroglobulin, further assisted in ruling out metastatic carcinoma. In addition to confirming the presence of "zipper-like" intercellular junctions and microvillus-bearing cytoplasmic microlumina, electron microscopy allowed for the pervasive accumulation of mitochondria in tumor cells to be directly visualized. A previously not documented variant, oncocytic ependymoma, is felt to add a reasonably relevant novel item to the differential diagnosis of granule-bearing central nervous system neoplasia, in particular oncocytic meningioma, granular cell astrocytoma, as well as metastatic deposits by oncocytic malignancies from extracranial sites.

The effect of high-energy extracorporeal shock waves on hyaline cartilage of adult rats in vivo

The aim of this study was to determine if extracorporeal shock wave therapy (ESWT) in vivo affects the structural integrity of articular cartilage. A single bout of ESWT (1500 shock waves of 0.5 mJ/mm(2)) was applied to femoral heads of 18 adult Sprague-Dawley rats. Two sham-treated animals served as controls. Cartilage of each femoral head was harvested at 1, 4, or 10 weeks after ESWT (n = 6 per treatment group) and scored on safranin-O-stained sections. Expression of tenascin-C and chitinase 3-like protein 1 (Chi3L1) was analyzed by immunohistochemistry. Quantitative real-time polymerase chain reaction (PCR) was used to examine collagen (II)alpha(1) (COL2A1) expression and chondrocyte morphology was investigated by transmission electron microscopy no changes in Mankin scores were observed after ESWT. Positive immunostaining for tenascin-C and Chi3L1 was found up to 10 weeks after ESWT in experimental but not in control cartilage. COL2A1 mRNA was increased in samples 1 and 4 weeks after ESWT. Alterations found on the ultrastructural level showed expansion of the rough-surfaced endoplasmatic reticulum, detachment of the cell membrane and necrotic chondrocytes. Extracorporeal shock waves caused alterations of hyaline cartilage on a molecular and ultrastructural level that were distinctly different from control. Similar changes were described before in the very early phase of osteoarthritis (OA). High-energy ESWT might therefore cause degenerative changes in hyaline cartilage as they are found in initial OA.

Detection of degenerative cartilage disease: comparison of high-resolution morphological MR and quantitative T2 mapping at 3.0 Tesla

The aim of the study was to investigate the association of T2 relaxation times of the knee with early degenerative cartilage changes. Furthermore the impact of unloading the knee on T2 values was evaluated.

New insights in the pathogenesis of high-altitude pulmonary edema

High-altitude pulmonary edema is a life-threatening condition occurring in predisposed but otherwise healthy individuals. It therefore permits the study of underlying mechanisms of pulmonary edema in the absence of confounding factors such as coexisting cardiovascular or pulmonary disease, and/or drug therapy. There is evidence that some degree of asymptomatic alveolar fluid accumulation may represent a normal phenomenon in healthy humans shortly after arrival at high altitude. Two fundamental mechanisms then determine whether this fluid accumulation is cleared or whether it progresses to HAPE: the quantity of liquid escaping from the pulmonary vasculature and the rate of its clearance by the alveolar respiratory epithelium. The former is directly related to the degree of hypoxia-induced pulmonary hypertension, whereas the latter is determined by the alveolar epithelial sodium transport. Here, we will review evidence that, in HAPE-prone subjects, impaired pulmonary endothelial and epithelial NO synthesis and/or bioavailability may represent a central underlying defect predisposing to exaggerated hypoxic pulmonary vasoconstriction and, in turn, capillary stress failure and alveolar fluid flooding. We will then demonstrate that exaggerated pulmonary hypertension, although possibly a conditio sine qua non, may not always be sufficient to induce HAPE and how defective alveolar fluid clearance may represent a second important pathogenic mechanism.

Combinations of prognostic tools for identification of high-risk normotensive patients with acute symptomatic pulmonary embolism

In haemodynamically stable patients with acute symptomatic pulmonary embolism (PE), studies have not evaluated the usefulness of combining the measurement of cardiac troponin, transthoracic echocardiogram (TTE), and lower extremity complete compression ultrasound (CCUS) testing for predicting the risk of PE-related death.