753 research outputs found
Interaction of the solar wind with Venus
Two topics related to the interaction of the solar wind with Venus are considered. First, a short review of the experimental evidence with particular attention to plasma measurements carried out on Mariner-5 and Mariner-10 is given. Secondly, the results of some recent theoretical work on the interaction of the solar wind with the ionosphere of Venus are summarized
Reduced tillage, but not organic matter input, increased nematode diversity and food web stability in European longâterm field experiments
Soil nematode communities and food web indices can inform about the complexity, nutrient flows and decomposition pathways of soil food webs, reflecting soil quality. Relative abundance of nematode feeding and lifeâhistory groups are used for calculating food web indices, i.e., maturity index (MI), enrichment index (EI), structure index (SI) and channel index (CI). Molecular methods to study nematode communities potentially offer advantages compared to traditional methods in terms of resolution, throughput, cost and time. In spite of such advantages, molecular data have not often been adopted so far to assess the effects of soil management on nematode communities and to calculate these food web indices. Here, we used highâthroughput amplicon sequencing to investigate the effects of tillage (conventional vs. reduced) and organic matter addition (low vs. high) on nematode communities and food web indices in 10 European longâterm field experiments and we assessed the relationship between nematode communities and soil parameters. We found that nematode communities were more strongly affected by tillage than by organic matter addition. Compared to conventional tillage, reduced tillage increased nematode diversity (23% higher Shannon diversity index), nematode community stability (12% higher MI), structure (24% higher SI), and the fungal decomposition channel (59% higher CI), and also the number of herbivorous nematodes (70% higher). Total and labile organic carbon, available K and microbial parameters explained nematode community structure. Our findings show that nematode communities are sensitive indicators of soil quality and that molecular profiling of nematode communities has the potential to reveal the effects of soil management on soil quality
Recommended from our members
Effect of water-soluble polymers, polyethylene glycol and poly(vinylpyrrolidone),on the gelation of aqueous micellar solutions of Pluronic copolymer F127
The micellization of F127 (E98P67E98) in dilute aqueous solutions of polyethylene glycol (PEG6000 and
PEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamic
radius (rh,app) obtained from the dynamic light scattering technique increased with increase in PEG concentration
but decreased on addition of PVP, results which are consistent with interaction of the micelles
with PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversion
was used to determine the onset of gelation. The critical concentration of F127 for gelation increased on
addition of PEG and of PVP K30 but decreased on addition of PVP K90. Small-angle X-ray scattering
(SAXS) was used to show that the 30 wt% F127 gel structure (fcc) was independent of polymer type
and concentration, as was the d-spacing and so the micelle hard-sphere radius. The maximum elastic
modulus (G0
max) of 30 wt% F127 decreased from its value for water alone as PEG was added, but was little
changed by adding PVP. These results are consistent with the packed-micelles in the 30 wt% F127 gel
being effectively isolated from the polymer solution on the microscale while, especially for the PEG, being
mixed on the macroscale
Hurricane Sandy Effects on Coastal Marsh Elevation Change
High-magnitude storm events such as Hurricane Sandy are powerful agents of geomorphic change in coastal marshes, potentially altering their surface elevation trajectories. But how do a stormâs impacts vary across a large region spanning a variety of wetland settings and storm exposures and intensities. We determined the short-term impacts of Hurricane Sandy at 223 surface elevation tableâmarker horizon stations in estuarine marshes located across the northeast region of the United States by comparing post- storm surface elevation change with pre-storm elevation trends. We hypothesized that the stormâs effect on marsh elevation trends would be influenced by position relative to landfall (right or left) and distance from landfall. The structural equation model presented predicts that marshes located to the left of landfall were more likely to experience an elevation gain greater than expected, and this positive deviation from pre-storm elevation trends tended to have a greater magnitude than those experiencing negative deviations (elevation loss), potentially due to greater sediment deposition. The magnitude of negative deviations from elevation change in marshes to the right of landfall was greater than for positive deviations, with a greater effect in marshes within 200 km of landfall, potentially from the extent and magnitude of storm surge. Overall, results provide an integrated picture of how storm characteristics combined with the local wetland setting are important to a stormâs impact on surface elevation, and that the surface elevation response can vary widely among sites across a region impacted by the same storm
'Sending Dollars Shows Feeling' - Emotions and Economies in Filipino Migration
This paper analyses the conceptualization of gender, relationships, and emotions that underpin âcare chainsâ approaches to Filipino labour migration. In a case study of longâdistance intimacy and economic transfers in an extended Filipino family, I show how contextualizing migration within local understandings of emotion fractures expectations created by care chains accounts. This case instead reveals agency, diversity, and new forms of global subjectivity emerging through longâdistance emotional connections within the translocal field shaped by labour mobility
An orthogonal C-H borylation - cross-coupling strategy for the preparation of tetrasubstituted "A(2)B(2)''-chrysene derivatives with tuneable photophysical properties
Cl-substituents serve as a functionalisable regiocontrol element for the orthogonal functionalisation of chrysene.</p
The pulsating DA white dwarf star EC 14012-1446: results from four epochs of time-resolved photometry
The pulsating DA white dwarfs are the coolest degenerate stars that undergo
self-driven oscillations. Understanding their interior structure will help to
understand the previous evolution of the star. To this end, we report the
analysis of more than 200 h of time-resolved CCD photometry of the pulsating DA
white dwarf star EC 14012-1446 acquired during four observing epochs in three
different years, including a coordinated three-site campaign. A total of 19
independent frequencies in the star's light variations together with 148
combination signals up to fifth order could be detected. We are unable to
obtain the period spacing of the normal modes and therefore a mass estimate of
the star, but we infer a fairly short rotation period of 0.61 +/- 0.03 d,
assuming the rotationally split modes are l=1. The pulsation modes of the star
undergo amplitude and frequency variations, in the sense that modes with higher
radial overtone show more pronounced variability and that amplitude changes are
always accompanied by frequency variations. Most of the second-order
combination frequencies detected have amplitudes that are a function of their
parent mode amplitudes, but we found a few cases of possible resonantly excited
modes. We point out the complications in the analysis and interpretation of
data sets of pulsating white dwarfs that are affected by combination
frequencies of the form f_A+f_B-f_C intruding into the frequency range of the
independent modes.Comment: 14 pages, 6 figures, 6 tables. MNRAS, in pres
- âŠ