799 research outputs found

    Plot and field scale soil moisture dynamics and subsurface wetness control on runoff generation in a headwater in the Ore Mountains

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    This study presents an application of an innovative sampling strategy to assess soil moisture dynamics in a headwater of the Weißeritz in the German eastern Ore Mountains. A grassland site and a forested site were instrumented with two Spatial TDR clusters (STDR) that consist of 39 and 32 coated TDR probes of 60 cm length. Distributed time series of vertically averaged soil moisture data from both sites/ensembles were analyzed by statistical and geostatistical methods. Spatial variability and the spatial mean at the forested site were larger than at the grassland site. Furthermore, clustering of TDR probes in combination with long-term monitoring allowed identification of average spatial covariance structures at the small field scale for different wetness states. The correlation length of soil water content as well as the sill to nugget ratio at the grassland site increased with increasing average wetness and but, in contrast, were constant at the forested site. As soil properties at both the forested and grassland sites are extremely variable, this suggests that the correlation structure at the forested site is dominated by the pattern of throughfall and interception. We also found a very strong correlation between antecedent soil moisture at the forested site and runoff coefficients of rainfall-runoff events observed at gauge Rehefeld. Antecedent soil moisture at the forest site explains 92% of the variability in the runoff coefficients. By combining these results with a recession analysis we derived a first conceptual model of the dominant runoff mechanisms operating in this catchment. Finally, we employed a physically based hydrological model to shed light on the controls of soil- and plant morphological parameters on soil average soil moisture at the forested site and the grassland site, respectively. A homogeneous soil setup allowed, after fine tuning of plant morphological parameters, most of the time unbiased predictions of the observed average soil conditions observed at both field sites. We conclude that the proposed sampling strategy of clustering TDR probes is suitable to assess unbiased average soil moisture dynamics in critical functional units, in this case the forested site, which is a much better predictor for event scale runoff formation than pre-event discharge. Long term monitoring of such critical landscape elements could maybe yield valuable information for flood warning in headwaters. We thus think that STDR provides a good intersect of the advantages of permanent sampling and spatially highly resolved soil moisture sampling using mobile rods

    Laue photography of fine crystalline particles

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    Screening Breakdown on the Route toward the Metal-Insulator Transition in Modulation Doped Si/SiGe Quantum Wells

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    Exploiting the spin resonance of two-dimensional (2D) electrons in SiGe/Si quantum wells we determine the carrier-density-dependence of the magnetic susceptibility. Assuming weak interaction we evaluate the density of states at the Fermi level D(E_F), and the screening wave vector, q_TF. Both are constant at higher carrier densities n, as for an ideal 2D carrier gas. For n < 3e11 cm-2, they decrease and extrapolate to zero at n = 7e10 cm-2. Calculating the mobility from q_TF yields good agreement with experimental values justifying the approach. The decrease in D(E_F) is explained by potential fluctuations which lead to tail states that make screening less efficient and - in a positive feedback - cause an increase of the potential fluctuations. Even in our high mobility samples the fluctuations exceed the electron-electron interaction leading to the formation of puddles of mobile carriers with at least 1 micrometer diameter.Comment: 4 pages, 3 figure

    A quality assessment of Spatial TDR soil moisture measurements in homogenous and heterogeneous media with laboratory experiments

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    Investigation of transient soil moisture profiles yields valuable information of near- surface processes. A recently developed reconstruction algorithm based on the telegraph equation allows the inverse estimation of soil moisture profiles along coated, three rod TDR probes. Laboratory experiments were carried out to prove the results of the inversion and to understand the influence of probe rod deformation and solid objects close to the probe in heterogeneous media. Differences in rod geometry can lead to serious misinterpretations in the soil moisture profile, but have small influence on the average soil moisture along the probe. Solids in the integration volume have almost no effect on average soil moisture, but result in locally slightly decreased moisture values. Inverted profiles obtained in a loamy soil with a clay content of about 16% were in good agreement with independent measurements

    Pennsylvania Folklife Vol. 31, No. 1

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    • The Pennsylvania Copper Tea Kettle • Our Camp and Soldiers Life (1861-65) • The Surprising Come Back of the Pennsylvania Rifle • Folk Songs • Port Royal and Philadelphia • Pennsylvania Dutch Life Along Switzer Run and Penn\u27s Creek • Aldes un Neies / Old and Newhttps://digitalcommons.ursinus.edu/pafolklifemag/1093/thumbnail.jp

    Pennsylvania Folklife Vol. 31, No. 1

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    • The Pennsylvania Copper Tea Kettle • Our Camp and Soldiers Life (1861-65) • The Surprising Come Back of the Pennsylvania Rifle • Folk Songs • Port Royal and Philadelphia • Pennsylvania Dutch Life Along Switzer Run and Penn\u27s Creek • Aldes un Neies / Old and Newhttps://digitalcommons.ursinus.edu/pafolklifemag/1093/thumbnail.jp

    When opposites attract? Exploring the existence of complementarity in self-brand congruence processes

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    In the psychology of human interpersonal attraction, complementarity is a well-recognized phenomenon, where individuals are attracted to partners with different but complementary traits to their own. Although scholarship in human-brand relations draws heavily from interpersonal attraction theory, preferred techniques for measuring self-brand congruence tend to capture it in only one form: the similarity configuration, which expresses the extent to which brand traits essentially resemble or mirror a consumer’s own. Hence, the aim of this study is to explore, for the first time, the existence of complementarity in self-brand congruence. From a canonical correlation analysis of survey data in which respondents rated their own personality traits and those of their favorite brand, the existence of both similarity and complementarity configurations is indeed revealed. Based on this, the study then derives a measure of self-brand congruence that captures both configurations, and tests its predictive power for a range of brand-related outcomes. The new measure is found to perform well against existing measures of self-brand congruence based purely on a similarity configuration, particularly for emotionally based brand-related outcomes

    Outcomes of surgical treatment of non-metastatic gastric cancer in patients aged 70 and older:A systematic review and meta-analysis

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    The optimal surgical treatment strategy for gastric cancer in older patients needs to be carefully evaluated due to increased vulnerability of older patients. We performed a database search for randomized controlled trials (RCTs) and cohort studies that included patients ≥70 years with potentially resectable stage I-III gastric cancer. Postoperative and survival outcomes were compared between groups undergoing 1) gastrectomy vs conservative treatment (best supportive care or non-operative treatment), 2) minimally invasive (MIG) vs open gastrectomy (OG), or 3) extended vs limited lymphadenectomy. When possible, results were pooled using risk ratios (RR). Thirty-one studies were included. Six retrospective studies compared overall survival (OS) between gastrectomy (N = 2332) and conservative treatment (N = 246). Longer OS was reported in the gastrectomy group in all studies, but study quality was low and meta-analysis was not feasible. Eighteen cohort studies compared MIG (N = 3626) and OG (N = 5193). MIG was associated with fewer complications (pooled RR 0.68, 95% confidence interval 0.54–0.84). OS was not different between the groups. Two RCTs and five cohort studies compared outcomes between extended (N = 709) and limited lymphadenectomy (N = 1323). Complication rates were comparable between the groups. Two cohort studies found longer OS or cancer-specific survival after extended lymphadenectomy. No quality of life (QoL) or functional outcomes were reported. In older patients with gastric cancer, there is low-quality evidence for better OS after gastrectomy vs conservative treatment. Compared to OG, MIG was associated with less postoperative morbidity. The evidence to support extended lymphadenectomy is limited. QoL and functional outcomes should be addressed in future studies
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