102 research outputs found
Compared to conventional, ecological intensive management promotes beneficial proteolytic soil microbial communities for agro-ecosystem functioning under climate change-induced rain regimes
Projected climate change and rainfall variability will affect soil microbial communities, biogeochemical cycling and agriculture. Nitrogen (N) is the most limiting nutrient in agroecosystems and its cycling and availability is highly dependent on microbial driven processes. In agroecosystems, hydrolysis of organic nitrogen (N) is an important step in controlling soil N availability. We analyzed the effect of management (ecological intensive vs. conventional intensive) on N-cycling processes and involved microbial communities under climate change-induced rain regimes. Terrestrial model ecosystems originating from agroecosystems across Europe were subjected to four different rain regimes for 263 days. Using structural equation modelling we identified direct impacts of rain regimes on N-cycling processes, whereas N-related microbial communities were more resistant. In addition to rain regimes, management indirectly affected N-cycling processes via modifications of N-related microbial community composition. Ecological intensive management promoted a beneficial N-related microbial community composition involved in N-cycling processes under climate change-induced rain regimes. Exploratory analyses identified phosphorus-associated litter properties as possible drivers for the observed management effects on N-related microbial community composition. This work provides novel insights into mechanisms controlling agro-ecosystem functioning under climate change
Pemetrexed plus Platinum as the First-Line Treatment Option for Advanced Non-Small Cell Lung Cancer: A Meta-Analysis of Randomized Controlled Trials
To compare the efficacy and toxicities of pemetrexed plus platinum with other platinum regimens in patients with previously untreated advanced non-small cell lung cancer (NSCLC). Methods: A meta-analysis was performed using trials identified through PubMed, EMBASE, and Cochrane databases. Two investigators independently assessed the quality of the trials and extracted data. The outcomes included overall survival (OS), progression-free survival (PFS), response rate (RR), and different types of toxicity. Hazard ratios (HRs), odds ratios (ORs) and their 95% confidence intervals (CIs) were pooled using RevMan software. Results: Four trials involving 2,518 patients with previously untreated advanced NSCLC met the inclusion criteria. Pemetrexed plus platinum chemotherapy (PPC) improved survival compared with other platinum-based regimens (PBR) in patients with advanced NSCLC (HR = 0.91, 95% CI: 0.83–1.00, p = 0.04), especially in those with non-squamous histology (HR = 0.87, 95% CI: 0.77–0.98, p = 0.02). No statistically significant improvement in either PFS or RR was found in PPC group as compared with PBR group (HR = 1.03, 95% CI: 0.94–1.13, p = 0.57; OR = 1.15, 95% CI: 0.95–1.39, p = 0.15, respectively). Compared with PBR, PPC led to less grade 3–4 neutropenia and leukopenia but more grade 3–4 nausea. However, hematological toxicity analysis revealed significant heterogeneities. Conclusion: Our results suggest that PPC in the first-line setting leads to a significant survival advantage with acceptable toxicities for advanced NSCLC patients, especially those with non-squamous histology, as compared with other PRB. PPC could be considered as the first-line treatment option for advanced NSCLC patients, especially those with non-squamous histology
Effects of Mowing on Methane Uptake in a Semiarid Grassland in Northern China
Background: Mowing is a widely adopted management practice for the semiarid steppe in China and affects CH4 exchange. However, the magnitude and the underlying mechanisms for CH 4 uptake in response to mowing remain uncertain. Methodology/Principal Findings: In two consecutive growing seasons, we measured the effect of mowing on CH 4 uptake in a steppe community. Vegetation was mowed to 2 cm (M2), 5 cm (M5), 10 cm (M10), 15 cm (M15) above soil surface, respectively, and control was set as non-mowing (NM). Compared with control, CH4 uptake was substantially enhanced at almost all the mowing treatments except for M15 plots of 2009. CH4 uptake was significantly correlated with soil microbial biomass carbon, microbial biomass nitrogen, and soil moisture. Mowing affects CH 4 uptake primarily through its effect on some biotic factors, such as net primary productivity, soil microbial C\N supply and soil microbial activities, while soil temperature and moisture were less important. Conclusions/Significance: This study found that mowing affects the fluxes of CH4 in the semiarid temperate steppe of north China
Modular Mass Spectrometric Tool for Analysis of Composition and Phosphorylation of Protein Complexes
The combination of high accuracy, sensitivity and speed of single and multiple-stage mass spectrometric analyses enables the collection of comprehensive sets of data containing detailed information about complex biological samples. To achieve these properties, we combined two high-performance matrix-assisted laser desorption ionization mass analyzers in one modular mass spectrometric tool, and applied this tool for dissecting the composition and post-translational modifications of protein complexes. As an example of this approach, we here present studies of the Saccharomyces cerevisiae anaphase-promoting complexes (APC) and elucidation of phosphorylation sites on its components. In general, the modular concept we describe could be useful for assembling mass spectrometers operating with both matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) ion sources into powerful mass spectrometric tools for the comprehensive analysis of complex biological samples
Variability and quasi-decadal changes in the methane budget overthe period 2000–2012
Following the recent Global Carbon Project (GCP)
synthesis of the decadal methane (CH4/ budget over 2000–
2012 (Saunois et al., 2016), we analyse here the same dataset
with a focus on quasi-decadal and inter-annual variability in
CH4 emissions. The GCP dataset integrates results from topdown
studies (exploiting atmospheric observations within an
atmospheric inverse-modelling framework) and bottom-up
models (including process-based models for estimating land
surface emissions and atmospheric chemistry), inventories of
anthropogenic emissions, and data-driven approaches.The annual global methane emissions from top-down studies,
which by construction match the observed methane
growth rate within their uncertainties, all show an increase in
total methane emissions over the period 2000–2012, but this
increase is not linear over the 13 years. Despite differences
between individual studies, the mean emission anomaly of the top-down ensemble shows no significant trend in total
methane emissions over the period 2000–2006, during
the plateau of atmospheric methane mole fractions, and also
over the period 2008–2012, during the renewed atmospheric
methane increase. However, the top-down ensemble mean
produces an emission shift between 2006 and 2008, leading
to 22 [16–32] Tg CH4 yr1 higher methane emissions
over the period 2008–2012 compared to 2002–2006. This
emission increase mostly originated from the tropics, with
a smaller contribution from mid-latitudes and no significant
change from boreal regions.
The regional contributions remain uncertain in top-down
studies. Tropical South America and South and East Asia
seem to contribute the most to the emission increase in the
tropics. However, these two regions have only limited atmospheric
measurements and remain therefore poorly constrained.
The sectorial partitioning of this emission increase between
the periods 2002–2006 and 2008–2012 differs from
one atmospheric inversion study to another. However, all topdown
studies suggest smaller changes in fossil fuel emissions
(from oil, gas, and coal industries) compared to the
mean of the bottom-up inventories included in this study.
This difference is partly driven by a smaller emission change
in China from the top-down studies compared to the estimate
in the Emission Database for Global Atmospheric Research
(EDGARv4.2) inventory, which should be revised to smaller
values in a near future. We apply isotopic signatures to the
emission changes estimated for individual studies based on
five emission sectors and find that for six individual top-down
studies (out of eight) the average isotopic signature of the
emission changes is not consistent with the observed change
in atmospheric 13CH4. However, the partitioning in emission
change derived from the ensemble mean is consistent with
this isotopic constraint. At the global scale, the top-down ensemble
mean suggests that the dominant contribution to the
resumed atmospheric CH4 growth after 2006 comes from microbial
sources (more from agriculture and waste sectors than
from natural wetlands), with an uncertain but smaller contribution
from fossil CH4 emissions. In addition, a decrease in
biomass burning emissions (in agreement with the biomass
burning emission databases) makes the balance of sources
consistent with atmospheric 13CH4 observations.
In most of the top-down studies included here, OH concentrations
are considered constant over the years (seasonal variations
but without any inter-annual variability). As a result,
the methane loss (in particular through OH oxidation) varies
mainly through the change in methane concentrations and not
its oxidants. For these reasons, changes in the methane loss
could not be properly investigated in this study, although it
may play a significant role in the recent atmospheric methane
changes as briefly discussed at the end of the paper.Published11135–111616A. Geochimica per l'ambienteJCR Journa
Recommended from our members
Global satellite monitoring of climate-induced vegetation disturbances
Terrestrial disturbances are accelerating globally, but their full impact is not quantified because we lack an adequate monitoring system. Remote sensing offers a means to quantify the frequency and extent of disturbances globally. Here, we review the current application of remote sensing to this problem and offer a framework for more systematic analysis in the future. We recommend that any proposed monitoring system should not only detect disturbances, but also be able to: identify the proximate cause(s); integrate a range of spatial scales; and, ideally, incorporate process models to explain the observed patterns and predicted trends in the future. Significant remaining challenges are tied to the ecology of disturbances. To meet these challenges, more effort is required to incorporate ecological principles and understanding into the assessments of disturbance worldwide
Chloride transport and the resulting corrosion of steel bars in alkali activated slag concretes
As the relative performance of alkali activated slag (AAS) concretes in comparison to portland cement (PC) counterparts for chloride transport and resulting corrosion of steel bars is not clear, an investigation was carried out and the results are reported in this paper. The effect of alkali concentration and modulus of sodium silicate solution used in AAS was studied. Chloride transport and corrosion properties were assessed with the help of electrical resistivity, non-steady state chloride diffusivity, onset of corrosion, rate of corrosion and pore solution chemistry. It was found that: (i) although chloride content at surface was higher for the AAS concretes, they had lower chloride diffusivity than PC concrete; (ii) pore structure, ionic exchange and interaction effect of hydrates strongly influenced the chloride transport in the AAS concretes; (iii) steel corrosion resistance of the AAS concretes was comparable to that of PC concrete under intermittent chloride ponding regime, with the exception of 6 % Na2O and Ms of 1.5; (iv) the corrosion behaviour of the AAS concretes was significantly influenced by ionic exchange, carbonation and sulphide concentration; (v) the increase of alkali concentration of the activator generally increased the resistance of AAS concretes to chloride transport and reduced its resulting corrosion, and a value of 1.5 was found to be an optimum modulus for the activator for improving the chloride transport and the corrosion resistance
Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire : an expert assessment
As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.Peer reviewe
- …