6,145 research outputs found
Consistent responses of soil microbial taxonomic and functional attributes to mercury pollution across China
Background: The ecological consequences of mercury (Hg) pollution—one of the major pollutants worldwide—on
microbial taxonomic and functional attributes remain poorly understood and largely unexplored. Using soils from two
typical Hg-impacted regions across China, here, we evaluated the role of Hg pollution in regulating bacterial
abundance, diversity, and co-occurrence network. We also investigated the associations between Hg contents and the
relative abundance of microbial functional genes by analyzing the soil metagenomes from a subset of those sites.
Results: We found that soil Hg largely influenced the taxonomic and functional attributes of microbial communities in
the two studied regions. In general, Hg pollution was negatively related to bacterial abundance, but positively related
to the diversity of bacteria in two separate regions. We also found some consistent associations between soil Hg
contents and the community composition of bacteria. For example, soil total Hg content was positively related to the
relative abundance of Firmicutes and Bacteroidetes in both paddy and upland soils. In contrast, the methylmercury
(MeHg) concentration was negatively correlated to the relative abundance of Nitrospirae in the two types of soils.
Increases in soil Hg pollution correlated with drastic changes in the relative abundance of ecological clusters within the
co-occurrence network of bacterial communities for the two regions. Using metagenomic data, we were also able to
detect the effect of Hg pollution on multiple functional genes relevant to key soil processes such as element cycles
and Hg transformations (e.g., methylation and reduction).
Conclusions: Together, our study provides solid evidence that Hg pollution has predictable and significant effects on
multiple taxonomic and functional attributes including bacterial abundance, diversity, and the relative abundance of
ecological clusters and functional genes. Our results suggest an increase in soil Hg pollution linked to human activities
will lead to predictable shifts in the taxonomic and functional attributes in the Hg-impacted areas, with potential
implications for sustainable management of agricultural ecosystems and elsewhere
Antisymmetric tensor unparticle and the radiative lepton flavor violating decays
We study the contribution of the tensor unparticle mediation to the branching
ratios of the radiative lepton flavor violating decays and predict a
restriction region for free parameters of the scenario by using experimental
upper limits. We observe that the branching ratios of the radiative lepton
flavor violating decays are sensitive to the fundamental mass scales of the
scenario and to the scale dimension of antisymmetric tensor unparticle. We
obtain a more restricted set for the free parameters in the case of the
\mu\rightarrow e \gamma decayComment: 15 pages, 10 figure
Control of sunroof buffeting noise by optimizing the flow field characteristics of a commercial vehicle
When a commercial vehicle is driving with the sunroof open, it is easy for the problem of sunroof buffeting noise to occur. This paper establishes the basis for the design of a commercial vehicle model that solves the problem of sunroof buffeting noise, which is based on computational fluid dynamics (CFD) numerical simulation technology. The large eddy simulation (LES) method was used to analyze the characteristics of the buffeting noise with different speed conditions while the sunroof was open. The simulation results showed that the small vortex generated in the cab forehead merges into a large vortex during the backward movement, and the turbulent vortex causes a resonance response in the cab cavity as the turbulent vortex moves above the sunroof and falls into the cab. Improving the flow field characteristics above the cab can reduce the sunroof buffeting noise. Focusing on the buffeting noise of commercial vehicles, it is proposed that the existing accessories, including sun visors and roof domes, are optimized to deal with the problem of sunroof buffeting noise. The sound pressure level of the sunroof buffeting noise was reduced by 6.7 dB after optimization. At the same time, the local pressure drag of the commercial vehicle was reduced, and the wind resistance coefficient was reduced by 1.55% compared to the original commercial vehicle. These results can be considered as relevant, with high potential applicability, within this field of researchThis work was supported by the National Natural Science Foundation of China (No. 52065013), the Guangxi Youth Science Fund Project (2018GXNSFBA281012), the Innovation-Driven Development Special Fund Project of Guangxi (Guike AA19182004), and the Liuzhou Scientific Research and Planning Development Project (2018AA20301)S
Excitation spectrum and ground state properties of the S=1/2 Heisenberg ladder with staggered dimerization
We have studied the excitation spectrum of the quantum spin ladder
with staggered dimerization by dimer series expansions, diagrammatic analysis
of an effective interacting Bose gas of local triplets, and exact
diagonalization of small clusters. We find that the model has two massive
phases, with predominant inter-chain (rung) or intra-chain correlations. The
transition from the rung dimer into the intra-chain dimer phase is
characterized by softening of the triplet spectrum at . The excitation
spectrum as well as the spin correlations away from and close to the critical
line are calculated. The location of the phase boundary is also determined.Comment: 13 pages, 7 figure
Therapeutic Efficacy of Stable Analogues of Vasoactive Intestinal Peptide against Pathogens
Vasoactive intestinal peptide (VIP) is an anti-inflammatory neuropeptide recently identified as a potential antimicrobial peptide. To overcome the metabolic limitations of VIP, we modified the native peptide sequence and generated two stable synthetic analogues (VIP51 and VIP51(6–30)) with better antimicrobial profiles. Herein we investigate the effects of both VIP analogues on cell viability, membrane integrity, and ultrastructure of various bacterial strains and Leishmania species. We found that the two VIP derivatives kill various non-pathogenic and pathogenic Gram-positive and Gram-negative bacteria as well as the parasite Leishmania major through a mechanism that depends on the interaction with certain components of the microbial surface, the formation of pores, and the disruption of the surface membrane. The cytotoxicity of the VIP derivatives is specific for pathogens, because they do not affect the viability of mammalian cells. Docking simulations indicate that the chemical changes made in the analogues are critical to increase their antimicrobial activities. Consequently, we found that the native VIP is less potent as an antibacterial and fails as a leishmanicidal. Noteworthy from a therapeutic point of view is that treatment with both derivatives increases the survival and reduces bacterial load and inflammation in mice with polymicrobial sepsis. Moreover, treatment with VIP51(6–30) is very effective at reducing lesion size and parasite burden in a model of cutaneous leishmaniasis. These results indicate that the VIP analogues emerge as attractive alternatives for treating drug-resistant infectious diseases and provide key insights into a rational design of novel agents against these pathogens.This work was supported, in whole or in part, by National Institutes of Health Grant RO1 AI031078 (to S. M. B.). This work was also supported by Excellence Grants from Junta de Andalucia (P09/CTS-4705) (to E. G.-R.) and European Cost Action (BM0802) (to E. G.-R.).Peer reviewe
Strong tree level unitarity violations in the extra dimensional Standard Model with scalars in the bulk
We show how the tree level unitarity violations of compactified extra
dimensional extensions of the Standard Model become much stronger when the
scalar sector is included in the bulk. This effect occurs when the couplings
are not suppressed for larger Kaluza-Klein levels, and could have relevant
consequences for the phenomenology of the next generation of colliders. We also
introduce a simple and generic formalism to obtain unitarity bounds for finite
energies, taking into account coupled channels including the towers of
Kaluza-Klein excitations.Comment: Version to appear in Phys. Rev. D Typos corrected and remarks added
to clarify figure
Elliptical Galaxies with Emission Lines from the Sloan Digital Sky Survey
We present the results of 11 elliptical galaxies with strong nebular emission
lines during our study of star formation history along the Hubble sequence.
After removing the dilution from the underlying old stellar populations by use
of stellar population synthesis model, we derive the accurate fluxes of all
emission lines for these objects, which are later classified with emission line
ratios into one Seyfert 2, six LINERs and four HII galaxies. We also identify
one HII galaxy (A1216+04) as a hitherto unknown Wolf-Rayet galaxy from the
presence of the Wolf-Rayet broad bump at 4650 \AA. We propose that the
star-forming activities in elliptical galaxies are triggered by either
galaxy-galaxy interaction or the merging of a small satellite/a massive star
cluster, as already suggested by recent numerical simulations
Experimental study on dielectric relaxation of SiO2 nano-particle suspensions for developing a particle characterization method based on electrical impedance spectroscopy
In this paper, the dielectric relaxation of SiO2 nano-particle suspensions is studied by electrical impedance spectroscopy method. The case of suspension composed of particles with thick double layer is concerned. The objective of this study is to find out the relationship between particle properties (size and concentration) and electrical impedance spectroscopy for developing a particle characterization method based on electrical impedance spectroscopy/tomography. The influences of particle size on electrical impedance spectroscopy (EIS) and relaxation frequency are investigated and analyzed. The experimental results indicate that impedance phase angle and α relaxation frequency are functions of particle size. α relaxation frequency is proportionally changing with (a+ κ-1)-n (a is particle radius, κ-1 is double layer thickness, n equals 0.344 for 4.76% suspension and 0.308 for 2.38% suspension). The exponent term, n, is smaller than the one in dilute suspensions (n=2), which is possibly due to decreasing of diffusion distance of ions around the particles in concentrated suspensions with thick double layer. The impedance parameters, including conductivity increment, δK', and α relaxation frequency are influenced by particle volume fraction. The conductivity increment, δK' becomes less negative with increasing particle volume fraction due to the positive contribution of double layer charge on the conductivity increment. The α relaxation frequency increases with increasing particle volume fraction and the small particles show a more significant increase than large particles. The experimental result on the differential electrical impedance tomographic images between the silica suspension and water (with same conductivity value) shows that small differences on the values of impedance imaginary part and phase can be observed at the upper right corner in the EIT images, which represent a small differentiation on the dielectric property caused by the electrical polarization of double layer on the particle surface
Transition between child and adult services for young people with ADHD: findings from a British national surveillance study
This is the author accepted manuscript. The final version is available from Cambridge University Press via the DOI in this record.Data Availability: Data is currently stored securely by the University of Exeter Medical School, under embargo until the end of the CATCh-uS project (2019).Background: Optimal transition involves continuity, joint care, planning meetings and information transfer. To plan services, commissioners and service providers need data on how many people require that service. Although Attention-Deficit/Hyperactivity Disorder (ADHD) frequently persists into adulthood, evidence is limited on transitions between child and adult services.
Aims: To estimate the national incidence of young people taking medication for ADHD that require and complete transition, and describe the proportion that experienced optimal transition.
Methods: Surveillance over twelve months using the British Paediatric Surveillance Unit and the Child and Adolescent Psychiatry Surveillance System, including baseline notification and follow up questionnaires.
Results: Questionnaire response was 79% at baseline and 82% at follow up. For cases aged 17-19, incident rate (range adjusted for non-response) of transition need was 202-511 per 100,000 people aged 17-19 per year, with successful transition of 38-96 per 100,000 people aged 17-19 per year. Cases were mostly male (77%) with a comorbid condition (62%). Half were referred to specialist adult ADHD and 25% to general adult mental health services; 64% had referral accepted but only 22% attended a first appointment. Only 6% met optimal transition criteria.
Conclusions: As inclusion criteria required eligible cases to be on medication, these estimates will represent the lower limit of the need for transition. Two critical points were apparent; referral acceptance and first appointment attendance. The low rate of successful transition and limited guideline adherence indicates significant need for commissioners and service providers to improve service transition experiences.National Institute for Health Research (NIHR
Measuring the Behavioural Component of the S&P 500 and its Relationship to Financial Stress and Aggregated Earnings Surprises
Scholars in management and economics have shown increasing interest in isolating the
behavioural dimension of market evolution. Indeed, by improving forecast accuracy and
precision, this exercise would certainly help firms to anticipate economic fluctuations,
thus leading to more profitable business and investment strategies. Yet, how to extract
the behavioural component from real market data remains an open question. By using
monthly data on the returns of the constituents of the S&P 500 index, we propose a
Bayesian methodology to measure the extent to which market data conform to what is
predicted by prospect theory (the behavioural perspective), relative to the (standard) subjective
expected utility theory baseline.We document a significant behavioural component
that reaches its peaks during recession periods and is correlated to measures of financial
volatility, market sentiment and financial stress with expected sign. Moreover, the behavioural
component decreases around macroeconomic corporate earnings news, while it
reacts positively to the number of surprising announcements
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