Soil microbial organic nitrogen uptake is regulated by carbon availability

AbstractPlants and microorganisms intensely compete for nitrogen (N) at many stages of the terrestrial N cycle. In particular, the dissolved organic N (DON) pool, and competition for low molecular weight dissolved organic N (LMWDON) compounds such as amino acids and peptides (and LMW dissolved organic matter; LMWDOM as a whole) has received significant recent research interest. However, as LMWDON compounds contain both N and carbon (C), a question that remains is whether soil microorganisms are primarily taking up LMWDON mainly for the C or the N contained therein. We investigated microbial uptake rates of the model peptide l-trialanine as a rapidly cycling LMWDON compound in temperate grassland soils of differing fertility using 14C labelling to assess how soil fertility status influenced microbial uptake of LMWDON. We then imposed an excess of C as glucose and/or N as NH4Cl to ask whether the uptake of the peptide was affected by C or N excess. Our results demonstrate that l-trialanine is taken up rapidly from the soil solution (t½ < 1.5 min), and that an excess of C, rather than N, resulted in a reduced uptake of the peptide. From this, we conclude that LMWDON is taken up primarily to fulfil the C requirement of soil microorganisms, indicating that they exist in a C-limited state, and are able to respond quickly to a transient influx of an easily metabolisable resource

Early psychological interventions for prevention and treatment of post-traumatic stress disorder (PTSD) and post-traumatic stress symptoms in post-partum women: A systematic review and meta-analysis

Background Pre-term or full-term childbirth can be experienced as physically or psychologically traumatic. Cumulative and trans-generational effects of traumatic stress on both psychological and physical health indicate the ethical requirement to investigate appropriate preventative treatment for stress symptoms in women following a routine traumatic experience such as childbirth. Objective The objective of this review was to investigate the effectiveness of early psychological interventions in reducing or preventing post-traumatic stress symptoms and post-traumatic stress disorder in post-partum women within twelve weeks of a traumatic birth. Methods Randomised controlled trials and pilot studies of psychological interventions preventing or reducing post-traumatic stress symptoms or PTSD, that included women who had experienced a traumatic birth, were identified in a search of Cochrane Central Register of Randomised Controlled Trials, MEDLINE, Embase, Psychinfo, PILOTS, CINAHL and Proquest Dissertations databases. One author performed database searches, verified results with a subject librarian, extracted study details and data. Five authors appraised extracted data and agreed upon risk of bias. Analysis was completed with Rev Man 5 software and quality of findings were rated according to Grading of Recommendation, Assessment, Development, and Evaluation. Results Eleven studies were identified that evaluated the effectiveness of a range of early psychological interventions. There was firm evidence to suggest that midwifery or clinician led early psychological interventions administered within 72 hours following traumatic childbirth are more effective than usual care in reducing traumatic stress symptoms in women at 4–6 weeks. Further studies of high methodological quality that include longer follow up of 6–12 months are required in order to substantiate the evidence of the effectiveness of specific face to face and online early psychological intervention modalities in preventing the effects of stress symptoms and PTSD in women following a traumatic birth before introduction to routine care and practice

Weak Localization Effect in Superconductors by Radiation Damage

Large reductions of the superconducting transition temperature $T_{c}$ and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and Ternary superconductors, and $\rm{NbSe_{2}}$ in the high fluence regime. We examine these behaviors based on the recent theory of weak localization effect in superconductors. We find a good fitting to the experimental data. In particular, weak localization correction to the phonon-mediated interaction is derived from the density correlation function. It is shown that weak localization has a strong influence on both the phonon-mediated interaction and the electron-phonon interaction, which leads to the universal correlation of $T_{c}$ and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information, Plesse see http://www.fen.bilkent.edu.tr/~yjki

The composition and weathering of the continents over geologic time

The composition of continental crust records the balance between construction by tectonics and destruction by physical and chemical erosion. Quantitative constraints on how igneous addition and chemical weathering have modified the continents' bulk composition are essential for understanding the evolution of geodynamics and climate. Using novel data analytic techniques we have extracted temporal trends in sediments' protolith composition and weathering intensity from the largest available compilation of sedimentary major element compositions: ~15,000 samples from 4.0 Ga to the present. We find that the average Archean upper continental crust was silica-rich and had a similar compositional diversity to modern continents. This is consistent with an early Archean, or earlier, onset of plate tectonics. In the Archean, chemical weathering sequestered ~25 % more CO2 per mass eroded for the same weathering intensity than in subsequent time periods, consistent with carbon mass balance despite higher Archean outgassing rates and more limited continental exposure. Since 2.0 Ga, over long (>0.5 Gyr) timescales, crustal weathering intensity has remained relatively constant. Onshorter timescales over the Phanerozoic, weathering intensity is correlated to global climate state, consistent with a weathering feedback acting in response to changes in CO2 sources or sinks.AGL is funded by the Natural Environment Research Council Grantham Institute SSCP DTP (grant number NE/L002515/1). OS acknowledges support from NERC grants NE/T012455/1 and NE/T00696X/1. This work was supported by CAS

Analysis of the authors’ rights collection frontier using PCA-MDEA: an application to the Valencia region

The aim of this paper is to estimate the authors’ rights collection frontier within the collection zones into which the Valencia Region (Spain) has been divided. To be more exact, a nonparametric frontier technique (Modified Data Envelopment Analysis, MDEA) and the Principal Components Analysis (PCA) are jointly employed to map out an initial approach to the potential authors’ rights collection within this region (as divided into collection zones). The analysis has been carried out both jointly and by majority sectors (performing, musical, and audio-visual arts).Publicaciones Econcult: Área de Investigación en Economía de la Cultura y Turismo. Universitat de Valènci

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results