For precision cosmological studies it is important to know the local properties of the reference point from which we observe the Universe. Particularly for the determination of the Hubble constant ...with low-redshift distance indicators, the values observed depend on the average matter density within the distance range covered. In this study we used the spatial distribution of galaxy clusters to map the matter density distribution in the local Universe. The study is based on our CLASSIX galaxy cluster survey, which is highly complete and well characterised, where galaxy clusters are detected by their X-ray emission. In total, 1653 galaxy clusters outside the “zone of avoidance” fulfil the selection criteria and are involved in this study. We find a local underdensity in the cluster distribution of about 30–60% which extends about 85 Mpc to the north and ∼170 Mpc to the south. We study the density distribution as a function of redshift in detail in several regions in the sky. For three regions for which the galaxy density distribution has previously been studied, we find good agreement between the density distribution of clusters and galaxies. Correcting for the bias in the cluster distribution we infer an underdensity in the matter distribution of about −30 ± 15% (−20 ± 10%) in a region with a radius of about 100 (∼140) Mpc. Calculating the probability of finding such an underdensity through structure formation theory in a ΛCDM universe with concordance cosmological parameters, we find a probability characterised by
σ
-values of 1.3 − 3.7. This indicates low probabilities, but with values of around 10% at the lower uncertainty limit, the existence of an underdensity cannot be ruled out. Inside this underdensity, the observed Hubble parameter will be larger by about 5.5
+2.1
−2.8
%, which explains part of the discrepancy between the locally measured value of
H
0
compared to the value of the Hubble parameter inferred from the Planck observations of cosmic microwave background anisotropies. If distance indicators outside the local underdensity are included, as in many modern analyses, this effect is diluted.
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•Surfactants were used to wash an oil-water separator sludge.•Surfactant type, concentration and application ratio to sludge were analysed.•Surface activity and micelle size could ...predict the oil recovery performance.•Triton X100, X114, rhamnolipid had higher oil recovery rates than Tween 80 and SDS.•The highest oil recovery rates were found at low surfactant application ratios.
Worldwide the generation of oil sludges is approximately 160 million metric tonnes per annum. The washing of oil sludge with surfactant solutions can be used to recover the oil and reused as a feedstock for fuel production. There is a need to establish the influence of the surfactant type, concentration, and application (surfactant to oil sludge, S/OS) ratio to oil sludge for the maximisation of oil recovery. This study presented the oil recovery rates from the washing of an oil-water separator sludge using surfactants, Triton X-100, sodium dodecyl sulphate (SDS), Tween 80, rhamnolipid, and Triton X-114. The surfactants were characterised by critical micelle concentration (CMC), micelle size, and surface activity. A Taguchi experimental design was applied to reduce the number of experimental runs. In general, Triton X-100 and X-114, and rhamnolipid had higher micelle sizes and surfactant activities which resulted in higher oil recoveries. The key role of the surfactants in the washing was evidenced because the ORR values with the surfactants were significantly higher than the value with the control with no surfactant solution. The S/OS ratio was the factor with the largest effect on the Taguchi signal-to-noise ratio (an indicator of variation) of the oil recovery rate. The levels with the maximum recovery rate were 1:1 S/OS, 2CMC of surfactant concentration and Triton X-100 (32% ± 5), Triton X-114 (30% ± 7), and rhamnolipid (29% ± 8). In conclusion, less surfactant solution (1:1 S/OS) and low surfactant concentration (≤2CMC) provided the maximum oil recovery from this type of oil sludge. To our knowledge, no previous study with surfactants has reported low oil recovery values at high S/OS ratios in the oil sludge washing.
This paper analyzes the syntax and compositional semantics of scalar modifiers of quantifier phrases in expressions like almost every student, absolutely every student and nowhere near every student. ...The semantics is based on scales (positive and negative) of generalized quantifiers.
Hierarchical assembly within clusters of galaxies is tied directly to the evolution of the brightest cluster galaxies (BCGs), which dominate the stellar light in the centres of rich clusters. In this ...paper, we investigate the number of mergers on to BCGs in 14 X-ray-selected clusters over the redshift range 0.8 < z < 1.4 using HST imaging data. We find significant differences in the numbers of companion galaxies to BCGs between the clusters in our sample, indicating that BCGs in similar mass clusters can have very different merging histories. Within a 50 kpc radius around the BCGs we find an average of 6.45 ± 1.15 companion galaxies with mass ratios (companion:BCG) between 1 : 1 and 1 : 20. The infalling companions show a 50/50 split between major (1 : 1-1 : 2) and minor (1 : 3-1 : 20) mergers. When compared to similar work using lower redshift clusters, these results demonstrate that both major and minor merging were more common in the past. Since the dynamical time-scales for merging on to the BCG are relatively short compared with the look-back time to z ∼ 1, our results suggest that the BCG stellar mass may increase by as much as 1.8 times since z = 1. However, the growth rate of BCGs will be substantially less if stripped material from nearby companions ends up in the diffuse intracluster light.
Indoor dust has been acknowledged as a major source of flame retardants (FRs) and dust ingestion is considered a major route of exposure for humans. In the present study, we investigated the presence ...of PBDEs and alternative FRs such as emerging halogenated FRs (EHFRs) and organophosphate flame retardants (PFRs) in indoor dust samples from British and Norwegian houses as well as British stores and offices. BDE209 was the most abundant PBDE congener with median concentrations of 4700ngg−1 and 3400ngg−1 in UK occupational and house dust, respectively, 30 and 20 fold higher than in Norwegian house dust. Monomeric PFRs (m-PFRs), including triphenyl phosphate (TPHP), tris(chloropropyl) phosphate (TCPP) and tris(2-chloroethyl) phosphate (TCEP) dominated all the studied environments. To the best of our knowledge, this is the first report of isodecyldiphenyl phosphate (iDPP) and trixylenyl phosphate (TXP) in indoor environments. iDPP was the most abundant oligomeric PFR (o-PFR) in all dust samples, with median concentrations one order of magnitude higher than TXP and bisphenol A bis(diphenyl phosphate (BDP). iDPP and TXP worst-case scenario exposures for British workers during an 8h exposure in the occupational environment were equal to 34 and 1.4ngkgbw−1day−1, respectively. The worst-case scenario for BDE209 estimated exposure for British toddlers (820ngkgbw−1day−1) did not exceeded the proposed reference dose (RfD) (7000ngkgbw−1day−1), while exposures for sum of m-PFRs (Σm-PFRs) in British toddlers and adults (17,900 and 785ngkgbw−1day−1 respectively) were an order of magnitude higher than for Norwegian toddlers and adults (1600 and 70ngkgbw−1day−1).
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•PBDEs, EHFRs and PFRs were analysed in Norwegian and UK house, store & office dust.•First report of iDPP and TXP in indoor dust with several o-PFRs also detected.•m-PFRs dominated all indoor environments, followed by EHFRs, PBDEs, and o-PFRs.•BDE209 levels were significantly higher in British than Norwegian house dust.•iDPP is commonly added in toys and culinary products, while TXP is used in IT products.
Heavy metal accumulation in agriculture soils is of particular concern in China, while the status and probabilistic health risks of metal contamination in Chinese agriculture soils have been rarely ...studied at the national scale. In this study, we compiled a database of heavy metal concentrations in Chinese agriculture soils and selected six heavy metals for pollution assessment and risk screening: arsenic (As), cadmium (Cd), chromium (Cr), nickel (Ni), lead (Pb) and Zinc (Zn). Monte Carlo simulation was employed to assess the probabilistic health risks, the associated uncertainties, as well as variations in toxicity parameters, ingestion rate and body weight. Results indicated that the concentrations of Cd were elevated above their reference standard and Cd had the highest mean geo-accumulation index (Igeo) of 1.79. Moreover, the mean hazard index (HI) through exposure to six heavy metals was 1.85E−01 and 2.87E−02 for children and adults, respectively, with 2.2% of non-cancer risks for children that exceeded the guideline value of 1. In contrast, 95.0% and 90.0% of the total cancer risks (TCR) through exposure to six heavy metals for children and adults, respectively, exceeded the guideline value of 1E−06. Six metals were ranked based on their percent of risk outputs exceeding the guideline values. Arsenic had the high exceedance of both cancer and non-cancer risks, while both Cr and Cd were metals with high concern that had high exceedance of cancer risk. Sensitivity analyses indicated that metal concentrations and ingestion rate of soil were the predominant contributors to total risk variance. Overall, the adverse health risks induced by exposure to heavy metals contaminated farmland were elevated. Results from this study may provide valuable implications for public health professionals and policy-makers to design effective strategy to manage nation-wide farmland and reduce heavy metal exposure.
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•Pollution status and probabilistic health risk of heavy metal in agriculture soils across China was determined.•Chinese population face severe cancer risks of heavy metal exposure as their risk value exceeded the benchmark.•The spatial distribution of high-risk areas and that of cancer villages were correlated.•Priority metals and critical exposure factors for further risk control were identified.
We examine the stellar mass assembly in galaxy cluster cores using data from the Cluster Lensing And Supernova survey with Hubble (CLASH). We measure the growth of brightest cluster galaxy (BCG) ...stellar mass, the fraction of the total cluster light which is in the intracluster light (ICL) and the numbers of mergers that occur in the BCG over the redshift range of the sample, 0.18 < z < 0.90. We find that BCGs grow in stellar mass by a factor of 1.4 on average from accretion of their companions, and this growth is reduced to a factor of 1.2 assuming 50 per cent of the accreted stellar mass becomes ICL, in line with the predictions of simulations. We find that the ICL shows significant growth over this same redshift range, growing by a factor of 4–5 in its contribution to the total cluster light. This result is in line with our previous findings for ICL at higher redshifts, however, our measured growth is somewhat steeper than is predicted by simulations of ICL assembly. We find high-mass companions and hence major merging (mergers with objects of masses ≥1/2 of the BCG) to be very rare for our sample. We conclude that minor mergers (mergers with objects with masses <1/2 of the BCG) are the dominant process for stellar mass assembly at low redshifts, with the majority of the stellar mass from interactions ending up contributing to the ICL rather than building up the BCG. From a rough estimate of the stellar mass growth of the ICL we also conclude that the majority of the ICL stars must come from galaxies which fall from outside of the core of the cluster, as predicted by simulations. It appears that the growth of the ICL is the major evolution event in galaxy cluster cores during the second half of the lifetime of the Universe.
. I propose a theory of the passive that combines aspects of the principles and parameters analysis (no specific rules, no downward movement) and Chomsky's (1957) Syntactic Structures analysis (the ...arguments in the passive are generated in the same positions as they are in the active).
Great potential exists to harness plant traits at the root–soil interface, mainly rhizodeposition and root hairs, to ‘build’ soils with better structure that can trap more carbon and resources, ...resist climate stresses, and promote a healthy microbiome. These traits appear to have been preserved in modern crop varieties, but scope exists to improve them further because they vary considerably between genotypes and respond to environmental conditions. From emerging evidence, rhizodeposition can act as a disperser, aggregator, and/or hydrogel in soil, and root hairs expand rhizosheath size. Future research should explore impacts of selecting these traits on plants and soils concurrently, expanding from model plants to commercial genotypes, and observing whether impacts currently limited to glasshouse studies occur in the field.
Root hairs and rhizodeposits are root traits that vary between plant species and crop genotypes and have a large impact on both plants and soils.Targeting these traits may benefit both plants and soil, improving food and environmental security at the same time. Soils may store more carbon (greenhouse gas mitigation), trap more water (drought tolerance) and nutrients, and resist erosion.From limited research, rhizosheath size has been maintained or improved in modern crop varieties, but potential exists to increase it further. Whether this will lead to improved yield or soil properties, however, requires greater field testing to verify.Laboratory and glasshouse research using root trait ideotypes has found marked impacts on soil biophysical properties. Rhizodeposits vary in behaviour between species from hydrogels to surfactants, and as soil dispersers (miners) or aggregators (builders).
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