Gasdiffusion in Böden: Bedeutung räumlicher Variabilität und Anisotropie

In Gashaushaltsmodellen stammen die verwendeten Werte für die Gasdurchlässigkeit meist von gemittelten Messwerten oder aus empirischen Transferfunktionen. Reale Böden können jedoch eine Anisotropie sowie eine deutliche räumliche Heterogenität aufweisen. Inwiefern die Berücksichtigung dieser Eigenschaften in einem zweidimensionalen Modell zur Berechnung einer stationäre Gleichgewichtseinstellung für die Sauerstoffverteilung unter verdichteten Fahrspur-bereichen die Ergebnisse beeinflusst und welche Schlussfolgerungen sich hieraus ableiten lassen, soll anhand einiger Beispiele gezeigt werden

3-D-Rekonstruktion der Wurzelraumbelüftung von Eichen: Nachweis und Wirkung anisotroper Gasdiffusionskoeffizienten

Für eine modellhafte Rekonstruktion der Wurzelraumbelüftung mittels Gasdiffussionskoeffizienten als Kenngröße der Bodenstruktur ist ein Aspekt die Klärung anisotroper Muster, da diese eine erhebliche Relevanz auf die Gasflüsse hätten. Bei einem Vergleich der Luftkapazität sowie der relativen Gasdiffusivitäten (Ds/D0) bei pF 1,8 von vertikal und horizontal entnommenen Stechzylindern weisen die Messwerte in allen Tiefenstufen eine Anisotropie des Ds/D0 um mindestens den Faktor 2 auf. Da dieser Effekte sowohl im Oberboden als auch im Unterboden auftritt, kann dies als unabhängiges, universelles Phänomen angesehen werden

Gastransport im Wurzelraum als 3-D-Phänomen: Eine Fallstudie zur Wurzelverteilung von Eichen

Es ist bekannt, dass ein durch Bodenverdichtung- und verformung gestörter Waldboden geringere Feinwurzeldichten als ein vergleichbarer, aber ungestörter Boden aufweist (Gaertig et al., 2002). Die genauen belüftungsrelevanten Parameter und deren Zusammenspiel sind bislang jedoch nicht eingehend auf kleinräumiger Ebene untersucht worden. Ein 3D- Modell für die Identifizierung und Bewertung der möglichen Belüftungswege zu den Wurzeln und der Zusammenhänge mit anderen Parametern wie z.B. Gasverbrauch und -produktion befindet sich noch in der Entwicklung. Eine vereinfachte 1D-Betrachtungsweise gibt jedoch schon erste Hinweise: Sowohl die lokale Trockenraum-dichte als auch der durchschnittliche vertikale Belüftungsweg sind in einer bestimmten Bodentiefe mit der Feinwurzel-dichte korreliert. Der Einfluss der Durchlässigkeit des Oberbodens allein stellt sich dagegen als geringer dar

Sonderstandort Fahrspur

Fahrspuren sind Sonderstandorte in Wäldern. Durch befahrungsinduzierte Standortveränderungen erfahren Fahrspuren einen ökologischen Wandel und weisen oftmals eine höhere pflanzliche Biodiversität als angrenzende Waldbestände auf. Erschließung verdichteter Böden durch Pflanzenwurzel ist ein wichtiger Prozess der Regeneration von verformten Waldböden. In experimentellen Versuchen soll der Einfluss der pflanzlichen Artenvielfalt auf die Bodenstrukturbildung untersucht werden

Recruitment and Baseline Characteristics of Participants in the AgeWell.de Study: A Pragmatic Cluster-Randomized Controlled Lifestyle Trial against Cognitive Decline

Targeting dementia prevention, first trials addressing multiple modifiable risk factors showed promising results in at-risk populations. In Germany, AgeWell.de is the first large-scale initiative investigating the effectiveness of a multi-component lifestyle intervention against cognitive decline. We aimed to investigate the recruitment process and baseline characteristics of the AgeWell.de participants to gain an understanding of the at-risk population and who engages in the intervention. General practitioners across five study sites recruited participants (aged 60-77 years, Cardiovascular Risk Factors, Aging, and Incidence of Dementia/CAIDE dementia risk score ≥ 9). Structured face-to-face interviews were conducted with eligible participants, including neuropsychological assessments. We analyzed group differences between (1) eligible vs. non-eligible participants, (2) participants vs. non-participants, and (3) between intervention groups. Of 1176 eligible participants, 146 (12.5%) dropped out before baseline; the study population was thus 1030 individuals. Non-participants did not differ from participants in key sociodemographic factors and dementia risk. Study participants were M = 69.0 (SD = 4.9) years old, and 52.1% were women. The average Montreal Cognitive Assessment/MoCA score was 24.5 (SD = 3.1), indicating a rather mildly cognitively impaired study population; however, 39.4% scored ≥ 26, thus being cognitively unimpaired. The bandwidth of cognitive states bears the interesting potential for differential trial outcome analyses. However, trial conduction is impacted by the COVID-19 pandemic, requiring adjustments to the study protocol with yet unclear methodological consequences

Profiling Trait Anxiety: Transcriptome Analysis Reveals Cathepsin B (Ctsb) as a Novel Candidate Gene for Emotionality in Mice

Behavioral endophenotypes are determined by a multitude of counteracting but precisely balanced molecular and physiological mechanisms. In this study, we aim to identify potential novel molecular targets that contribute to the multigenic trait “anxiety”. We used microarrays to investigate the gene expression profiles of different brain regions within the limbic system of mice which were selectively bred for either high (HAB) or low (LAB) anxiety-related behavior, and also show signs of comorbid depression-like behavior

Ambient-noise tomography of the wider Vienna Basin region

We present a new 3-D shear-velocity model for the top 30 km of the crust in the wider Vienna Basin region based on surface waves extracted from ambient-noise cross-correlations. We use continuous seismic records of 63 broad-band stations of the AlpArray project to retrieve interstation Green’s functions from ambient-noise cross-correlations in the period range from 5 to 25 s. From these Green’s functions, we measure Rayleigh group traveltimes, utilizing all four components of the cross-correlation tensor, which are associated with Rayleigh waves (ZZ, RR, RZ and ZR), to exploit multiple measurements per station pair. A set of selection criteria is applied to ensure that we use high-quality recordings of fundamental Rayleigh modes. We regionalize the interstation group velocities in a 5 km × 5 km grid with an average path density of ∼20 paths per cell. From the resulting group-velocity maps, we extract local 1-D dispersion curves for each cell and invert all cells independently to retrieve the crustal shear-velocity structure of the study area. The resulting model provides a previously unachieved lateral resolution of seismic velocities in the region of ∼15 km. As major features, we image the Vienna Basin and Little Hungarian Plain as low-velocity anomalies, and the Bohemian Massif with high velocities. The edges of these features are marked with prominent velocity contrasts correlated with faults, such as the Alpine Front and Vienna Basin transfer fault system. The observed structures correlate well with surface geology, gravitational anomalies and the few known crystalline basement depths from boreholes. For depths larger than those reached by boreholes, the new model allows new insight into the complex structure of the Vienna Basin and surrounding areas, including deep low-velocity zones, which we image with previously unachieved detail. This model may be used in the future to interpret the deeper structures and tectonic evolution of the wider Vienna Basin region, evaluate natural resources, model wave propagation and improve earthquake locations, among others

Shear-wave velocity structure beneath the Dinarides from the inversion of Rayleigh-wave dispersion

Highlights • Rayleigh-wave phase velocity in the wider Dinarides region using the two-station method. • Uppermost mantle shear-wave velocity model of the Dinarides-Adriatic Sea region. • Velocity model reveals a robust high-velocity anomaly present under the whole Dinarides. • High-velocity anomaly reaches depth of 160 km in the northern Dinarides to more than 200 km under southern Dinarides. • New structural model incorporating delamination as one of the processes controlling the continental collision in the Dinarides. The interaction between the Adriatic microplate (Adria) and Eurasia is the main driving factor in the central Mediterranean tectonics. Their interplay has shaped the geodynamics of the whole region and formed several mountain belts including Alps, Dinarides and Apennines. Among these, Dinarides are the least investigated and little is known about the underlying geodynamic processes. There are numerous open questions about the current state of interaction between Adria and Eurasia under the Dinaric domain. One of the most interesting is the nature of lithospheric underthrusting of Adriatic plate, e.g. length of the slab or varying slab disposition along the orogen. Previous investigations have found a low-velocity zone in the uppermost mantle under the northern-central Dinarides which was interpreted as a slab gap. Conversely, several newer studies have indicated the presence of the continuous slab under the Dinarides with no trace of the low velocity zone. Thus, to investigate the Dinaric mantle structure further, we use regional-to-teleseismic surface-wave records from 98 seismic stations in the wider Dinarides region to create a 3D shear-wave velocity model. More precisely, a two-station method is used to extract Rayleigh-wave phase velocity while tomography and 1D inversion of the phase velocity are employed to map the depth dependent shear-wave velocity. Resulting velocity model reveals a robust high-velocity anomaly present under the whole Dinarides, reaching the depths of 160 km in the north to more than 200 km under southern Dinarides. These results do not agree with most of the previous investigations and show continuous underthrusting of the Adriatic lithosphere under Europe along the whole Dinaric region. The geometry of the down-going slab varies from the deeper slab in the north and south to the shallower underthrusting in the center. On-top of both north and south slabs there is a low-velocity wedge indicating lithospheric delamination which could explain the 200 km deep high-velocity body existing under the southern Dinarides

Crustal Thinning From Orogen to Back-Arc Basin: The Structure of the Pannonian Basin Region Revealed by P-to-S Converted Seismic Waves

We present the results of P-to-S receiver function analysis to improve the 3D image of the sedimentary layer, the upper crust, and lower crust in the Pannonian Basin area. The Pannonian Basin hosts deep sedimentary depocentres superimposed on a complex basement structure and it is surrounded by mountain belts. We processed waveforms from 221 three-component broadband seismological stations. As a result of the dense station coverage, we were able to achieve so far unprecedented spatial resolution in determining the velocity structure of the crust. We applied a three-fold quality control process; the first two being applied to the observed waveforms and the third to the calculated radial receiver functions. This work is the first comprehensive receiver function study of the entire region. To prepare the inversions, we performed station-wise H-Vp/Vs grid search, as well as Common Conversion Point migration. Our main focus was then the S-wave velocity structure of the area, which we determined by the Neighborhood Algorithm inversion method at each station, where data were sub-divided into back-azimuthal bundles based on similar Ps delay times. The 1D, nonlinear inversions provided the depth of the discontinuities, shear-wave velocities and Vp/Vs ratios of each layer per bundle, and we calculated uncertainty values for each of these parameters. We then developed a 3D interpolation method based on natural neighbor interpolation to obtain the 3D crustal structure from the local inversion results. We present the sedimentary thickness map, the first Conrad depth map and an improved, detailed Moho map, as well as the first upper and lower crustal thickness maps obtained from receiver function analysis. The velocity jump across the Conrad discontinuity is estimated at less than 0.2 km/s over most of the investigated area. We also compare the new Moho map from our approach to simple grid search results and prior knowledge from other techniques. Our Moho depth map presents local variations in the investigated area: the crust-mantle boundary is at 20–26 km beneath the sedimentary basins, while it is situated deeper below the Apuseni Mountains, Transdanubian and North Hungarian Ranges (28–33 km), and it is the deepest beneath the Eastern Alps and the Southern Carpathians (40–45 km). These values reflect well the Neogene evolution of the region, such as crustal thinning of the Pannonian Basin and orogenic thickening in the neighboring mountain belts