1,378 research outputs found

    Transition from Townsend to glow discharge: subcritical, mixed or supercritical

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    The full parameter space of the transition from Townsend to glow discharge is investigated numerically in one space dimension in the classical model: with electrons and positive ions drifting in the local electric field, impact ionization by electrons (α\alpha process), secondary electron emission from the cathode (γ\gamma process) and space charge effects. We also perform a systematic analytical small current expansion about the Townsend limit up to third order in the total current that fits our numerical data very well. Depending on γ\gamma and system size pd, the transition from Townsend to glow discharge can show the textbook subcritical behavior, but for smaller values of pd, we also find supercritical or some intermediate ``mixed'' behavior. The analysis in particular lays the basis for understanding the complex spatio-temporal patterns in planar barrier discharge systems.Comment: 12 pages, 10 figures, submitted to Phys. Rev.

    Shift of microbial communities and reduced enzymatic activity in soil under plastic mulching system in strawberry cultivation

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    The use of plastic mulching (PM) in agriculture has strongly increased in the last years. Improved water saving and higher soil temperature are some advantages of this management. Yet, an intensive use of PM has been recently linked to negative effects on soil quality. The aim of this study is thus to assess the effects of long-term plastic mulching (PM) on soil microbial indicators. PM was compared with the use of wheat straw mulching (SM), an also widely used mulch material. Samples were collected at two depths (0-5 and 5-10 cm) from strawberry fields, after 4-year management. Cultivation in PM and SM was done in a ridge-furrow system with subsurface irrigation. Soil characterization comprised soil texture and aggregate stability, soil organic carbon, pH and water content. Soil microbial analysis included: Soil microbial biomass (Cmic), a fraction of soil cultivable fungi (CFU values), soil bacteria (16S rRNA), denitrifying community (nirK, nirS, narG, napA genes), soil enzyme activity (C-Chitinase, P-Phosphatase and N Leucine-aminopeptidase), deoxynivalenol (DON) content and Cmic:Corg ratio. Positive effects on soil physicochemical properties were observed under PM as compared to SM, reflected by a higher soil carbon content and better aggregate stability (p>0.05). Yet, soil microbial analysis revealed some differences between managements. Cmic values were comparable in both systems, showing no differences in soil microbial biomass. In the same way, the analysis of functional genes of the N cycle and the activity of the enzymes P-Phosphatase and N Leucine-aminopeptidase was not affected by the mulching treatment. But, the abundance of bacteria (18%) and a fraction of soil cultivable fungi were reduced by respectively 18 and 62% under PM. Since the Cmic values remained similar between treatments, this accounts for a shift of microbial communities under PM. Additionally, C-Chitinase activity declined under PM. Interestingly, this enzyme correlated positively with CFU values (r=0.781, p=0.001), suggesting that a reduction of the activity is a consequence of the reduction of the fungal biomass. Additionally, a higher deoxynivalenol concentration (2.2 ± 2.4 µg kg-1) and a reduced Cmic:Corg ratio (1.3±0.3%) were observed under PM, indicative of less appropriate soil conditions after long-term PM management

    The effect of social media communication on consumer perceptions of brands

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    Researchers and brand managers have limited understanding of the effects social media communication has on how consumers perceive brands. We investigated 504 Facebook users in order to observe the impact of firm-created and user-generated social media communication on brand equity, brand attitude and purchase intention by using a standardized online survey throughout Poland. To test the conceptual model, we analyzed 60 brands across three different industries: non-alcoholic beverages, clothing and mobile network operators. When analyzing the data, we applied the structural equation modeling technique to both investigate the interplay of firm-created and user-generated social media communication and examine industry-specific differences. The results of the empirical studies showed that user-generated social media communication had a positive influence on both brand equity and brand attitude, whereas firm-created social media communication affected only brand attitude. Both brand equity and brand attitude were shown to have a positive influence on purchase intention. In addition, we assessed measurement invariance using a multi-group structural modeling equation. The findings revealed that the proposed measurement model was invariant across the researched industries. However, structural path differences were detected across the models

    Improved ventricular function during inhalation of PGI(2) aerosol partly relies on enhanced myocardial contractility

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    Inhaled prostacyclin (PGI(2)) aerosol induces selective pulmonary vasodilation. Further, it improves right ventricular ( RV) function, which may largely rely on pulmonary vasodilation, but also on enhanced myocardial contractility. We investigated the effects of the inhaled PGI(2) analogs epoprostenol (EPO) and iloprost (ILO) on RV function and myocardial contractility in 9 anesthetized pigs receiving aerosolized EPO (25 and 50 ng center dot kg(-1) center dot min(-1)) and, consecutively, ILO (60 ng center dot kg(-1) center dot min(-1)) for 20 min each. We measured pulmonary artery pressure ( PAP), RV ejection fraction (RVEF) and RV end-diastolic-volume (RV-EDV), and left ventricular end-systolic pressure-volume-relation (end-systolic elastance, E-es). EPO and ILO reduced PAP, increased RVEF and reduced RVEDV. E-es was enhanced during all doses tested, which reached statistical significance during EPO25ng and ILO, but not during EPO50ng. PGI(2) aerosol enhances myocardial contractility in healthy pigs, contributing to improve RV function. Copyright (C) 2005 S. Karger AG, Basel

    Epigenetic alterations in skin homing CD4+CLA+ T cells of atopic dermatitis patients

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    T cells expressing the cutaneous lymphocyte antigen (CLA) mediate pathogenic inflammation in atopic dermatitis (AD). The molecular alterations contributing to their dysregulation remain unclear. With the aim to elucidate putative altered pathways in AD we profiled DNA methylation levels and miRNA expression in sorted T cell populations (CD4+, CD4+CD45RA+ naïve, CD4+CLA+, and CD8+) from adult AD patients and healthy controls (HC). Skin homing CD4+CLA+ T cells from AD patients showed significant differences in DNA methylation in 40 genes compared to HC (p < 0.05). Reduced DNA methylation levels in the upstream region of the interleukin-13 gene (IL13) in CD4+CLA+ T cells from AD patients correlated with increased IL13 mRNA expression in these cells. Sixteen miRNAs showed differential expression in CD4+CLA+ T cells from AD patients targeting genes in 202 biological processes (p < 0.05). An integrated network analysis of miRNAs and CpG sites identified two communities of strongly interconnected regulatory elements with strong antagonistic behaviours that recapitulated the differences between AD patients and HC. Functional analysis of the genes linked to these communities revealed their association with key cytokine signaling pathways, MAP kinase signaling and protein ubiquitination. Our findings support that epigenetic mechanisms play a role in the pathogenesis of AD by affecting inflammatory signaling molecules in skin homing CD4+CLA+ T cells and uncover putative molecules participating in AD pathways. © 2020, The Author(s).Peer reviewe

    Complexity of multi-dimensional spontaneous EEG decreases during propofol induced general anaesthesia

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    Emerging neural theories of consciousness suggest a correlation between a specific type of neural dynamical complexity and the level of consciousness: When awake and aware, causal interactions between brain regions are both integrated (all regions are to a certain extent connected) and differentiated (there is inhomogeneity and variety in the interactions). In support of this, recent work by Casali et al (2013) has shown that Lempel-Ziv complexity correlates strongly with conscious level, when computed on the EEG response to transcranial magnetic stimulation. Here we investigated complexity of spontaneous high-density EEG data during propofol-induced general anaesthesia. We consider three distinct measures: (i) Lempel-Ziv complexity, which is derived from how compressible the data are; (ii) amplitude coalition entropy, which measures the variability in the constitution of the set of active channels; and (iii) the novel synchrony coalition entropy (SCE), which measures the variability in the constitution of the set of synchronous channels. After some simulations on Kuramoto oscillator models which demonstrate that these measures capture distinct ‘flavours’ of complexity, we show that there is a robustly measurable decrease in the complexity of spontaneous EEG during general anaesthesia

    Biodiversity in Marine Ecosystems—European Developments toward Robust Assessments

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    Sustainability of marine ecosystems and their services are dependent on marine biodiversity, which is threatened worldwide. Biodiversity protection is a major target of the EU Marine Strategy Framework Directive, requiring assessment of the status of biodiversity on the level of species, habitats, and ecosystems including genetic diversity and the role of biodiversity in food web functioning and structure. This paper provides a summary of the development of new indicators and refinement of existing ones in order to address some of the observed gaps in indicator availability for marine biodiversity assessments considering genetic, species, habitat, and ecosystem levels. Promising new indicators are available addressing genetic diversity of microbial and benthic communities. Novel indicators to assess biodiversity and food webs associated with habitats formed by keystone species (such as macroalgae) as well as to map benthic habitats (such as biogenic reefs) using high resolution habitat characterization were developed. We also discuss the advances made on indicators for detecting impacts of non-native invasive species and assessing the structure and functioning of marine food-webs. The latter are based on indicators showing the effects of fishing on trophic level and size distribution of fish and elasmobranch communities well as phytoplankton and zooplankton community structure as food web indicators. New and refined indicators are ranked based on quality criteria). Their applicability for various EU and global biodiversity assessments and the need for further development of new indicators and refinement of the existing ones is discussed
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