The extragalactic background light (EBL) is of fundamental importance both for understanding the entire process of galaxy evolution and for γ-ray astronomy, but the overall spectrum of the EBL ...between 0.1 and 1000 μm has never been determined directly from galaxy spectral energy distribution (SED) observations over a wide redshift range. The evolving, overall spectrum of the EBL is derived here utilizing a novel method based on observations only. This is achieved from the observed evolution of the rest-frame K-band galaxy luminosity function up to redshift 4, combined with a determination of galaxy-SED-type fractions. These are based on fitting Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) templates to a multiwavelength sample of about 6000 galaxies in the redshift range from 0.2 to 1 from the All-wavelength Extended Groth Strip International Survey (AEGIS). The changing fractions of quiescent galaxies, star-forming galaxies, starburst galaxies and active galactic nucleus (AGN) galaxies in that redshift range are estimated, and two alternative extrapolations of SED types to higher redshifts are considered. This allows calculation of the evolution of the luminosity densities from the ultraviolet (UV) to the infrared (IR), the evolving star formation rate density of the Universe, the evolving contribution to the bolometric EBL from the different galaxy populations including AGN galaxies and the buildup of the EBL. Our EBL calculations are compared with those from a semi-analytic model, another observationally based model and observational data. The EBL uncertainties in our modelling based directly on the data are quantified, and their consequences for attenuation of very-high-energy γ-rays due to pair production on the EBL are discussed. It is concluded that the EBL is well constrained from the UV to the mid-IR, but independent efforts from IR and γ-ray astronomy are needed in order to reduce the uncertainties in the far-IR.
Carbonaceous particulate matter (PM), comprising black carbon (BC), primary organic aerosol (POA) and secondary organic aerosol (SOA, from atmospheric aging of precursors), is a highly toxic vehicle ...exhaust component. Therefore, understanding vehicle pollution requires knowledge of both primary emissions, and how these emissions age in the atmosphere. We provide a systematic examination of carbonaceous PM emissions and parameterisation of SOA formation from modern diesel and gasoline cars at different temperatures (22, -7 °C) during controlled laboratory experiments. Carbonaceous PM emission and SOA formation is markedly higher from gasoline than diesel particle filter (DPF) and catalyst-equipped diesel cars, more so at -7 °C, contrasting with nitrogen oxides (NO
). Higher SOA formation from gasoline cars and primary emission reductions for diesels implies gasoline cars will increasingly dominate vehicular total carbonaceous PM, though older non-DPF-equipped diesels will continue to dominate the primary fraction for some time. Supported by state-of-the-art source apportionment of ambient fossil fuel derived PM, our results show that whether gasoline or diesel cars are more polluting depends on the pollutant in question, i.e. that diesel cars are not necessarily worse polluters than gasoline cars.
The Human Cell Atlas is a large international collaborative effort to map all cell types of the human body. Single-cell RNA sequencing can generate high-quality data for the delivery of such an ...atlas. However, delays between fresh sample collection and processing may lead to poor data and difficulties in experimental design.
This study assesses the effect of cold storage on fresh healthy spleen, esophagus, and lung from ≥ 5 donors over 72 h. We collect 240,000 high-quality single-cell transcriptomes with detailed cell type annotations and whole genome sequences of donors, enabling future eQTL studies. Our data provide a valuable resource for the study of these 3 organs and will allow cross-organ comparison of cell types. We see little effect of cold ischemic time on cell yield, total number of reads per cell, and other quality control metrics in any of the tissues within the first 24 h. However, we observe a decrease in the proportions of lung T cells at 72 h, higher percentage of mitochondrial reads, and increased contamination by background ambient RNA reads in the 72-h samples in the spleen, which is cell type specific.
In conclusion, we present robust protocols for tissue preservation for up to 24 h prior to scRNA-seq analysis. This greatly facilitates the logistics of sample collection for Human Cell Atlas or clinical studies since it increases the time frames for sample processing.
When deformed beyond their elastic limits, crystalline solids flow plastically via particle rearrangements localized around structural defects. Disordered solids also flow, but without obvious ...structural defects. We link structure to plasticity in disordered solids via a microscopic structural quantity, “softness,” designed by machine learning to be maximally predictive of rearrangements. Experimental results and computations enabled us to measure the spatial correlations and strain response of softness, as well as two measures of plasticity: the size of rearrangements and the yield strain. All four quantities maintained remarkable commonality in their values for disordered packings of objects ranging from atoms to grains, spanning seven orders of magnitude in diameter and 13 orders of magnitude in elastic modulus. These commonalities link the spatial correlations and strain response of softness to rearrangement size and yield strain, respectively.
Electrode potential–pH (Pourbaix) diagrams provide a phase map of the most stable compounds of a metal, its corrosion products, and associated ions in solution. The utility of these phase diagrams is ...that they enable the assessment of electrochemical stabilities, for example, of Ni metal and its derived oxides, hydroxides, and oxyhydroxides, against corrosion in aqueous environments. Remarkably, the Ni Pourbaix diagrams reported over the last 50 years are largely inconsistent with various electrochemical observations, which may be attributed to inaccurate experimental free energies of formation (Δf G) for the complex Ni-based compounds used in producing the available diagrams. Here we show that state-of-the-art density-functional theory (DFT) can be used to obtain accurate Δf G values, which lead to Ni Pourbaix diagrams that are more consistent with direct electrochemical experiments: Electrochemical impedance spectroscopy and surface-enhanced Raman spectroscopy are used to characterize the electrochemical stabilities of NiO and Ni(OH)2 formed on Ni, demonstrating the reliability in correction-free first-principles based Pourbaix diagrams. Our results show the importance in applying modern density functionals in combination with experimental advances in aqueous environment compound identification for assessing electrochemical phase stability of materials, which will be useful for the design, synthesis, and selection of corrosion-resistant metals, photoabsorbers, and photocatalytic materials.
Background
Exposure to environmental pollutants promotes Th2 cell responses. Aryl hydrocarbon receptor (AhR) activation aggravates allergic responses. Epithelium‐derived thymic stromal lymphopoietin ...(TSLP), interleukin (IL)‐25, and IL‐33 are implicated in the dysregulation of Th2 immune responses in severe allergic asthma.
Methods
Bronchial biopsies of 28 allergic severe asthma and 6 mild asthma subjects from highly polluted areas were analyzed for AhR nuclear translocation (NT), cytokine expression, and gene activation. Cultured primary epithelial cells were stimulated with diesel exhausted particles (DEP) to determine AhR‐mediated IL‐33, Il‐25, and TSLP synthesis and release.
Results
Primary bronchial epithelial cells exposed to DEP showed upregulation of IL‐33, IL‐25, and TSLP. These effects were abolished by knockdown of AhR by siRNA. Increased AhR/ARNT binding to promoters of IL‐33, IL‐25, and TSLP was found using chromatin immunoprecipitation (ChIP) assay. Allergic severe asthma with high AhR NT had higher bronchial gene and protein expression of IL‐33, IL‐25, and TSLP. These patients derived clinical benefit from anti‐IgE treatment.
Conclusion
Aryl hydrocarbon receptor activation by DEP mediates upregulation of IL‐33, IL‐25, and TSLP with Th2 activation, potentially linking environmental pollution and allergic severe asthma.
Environmental diesel exhaust particles (DEP) exposed to airway epithelium ligate cytoplasmic aryl hydrocarbon receptor (AhR), translocate to the nucleus with aryl hydrocarbon receptor nuclear translocator (ARNT), and then transactivate IL‐33, Il‐25, and TSLP gene expression. Patients with high AhR nucleus translocation overexpressed IL‐33, Il‐25, and TSLP cytokines compared to those with low. Patients with high AhR nucleus translocation are more response to anti‐IgE therapy compared to those with low.
The cost, size and availability of electron accelerators are dominated by the achievable accelerating gradient. Conventional high-brightness radio-frequency accelerating structures operate with 30-50 ...MeV m(-1) gradients. Electron accelerators driven with optical or infrared sources have demonstrated accelerating gradients orders of magnitude above that achievable with conventional radio-frequency structures. However, laser-driven wakefield accelerators require intense femtosecond sources and direct laser-driven accelerators suffer from low bunch charge, sub-micron tolerances and sub-femtosecond timing requirements due to the short wavelength of operation. Here we demonstrate linear acceleration of electrons with keV energy gain using optically generated terahertz pulses. Terahertz-driven accelerating structures enable high-gradient electron/proton accelerators with simple accelerating structures, high repetition rates and significant charge per bunch. These ultra-compact terahertz accelerators with extremely short electron bunches hold great potential to have a transformative impact for free electron lasers, linear colliders, ultrafast electron diffraction, X-ray science and medical therapy with X-rays and electron beams.
The interaction of matter and light is one of the fundamental processes occurring in nature, and its most elementary form is realized when a single atom interacts with a single photon. Reaching this ...regime has been a major focus of research in atomic physics and quantum optics for several decades and has generated the field of cavity quantum electrodynamics. Here we perform an experiment in which a superconducting two-level system, playing the role of an artificial atom, is coupled to an on-chip cavity consisting of a superconducting transmission line resonator. We show that the strong coupling regime can be attained in a solid-state system, and we experimentally observe the coherent interaction of a superconducting two-level system with a single microwave photon. The concept of circuit quantum electrodynamics opens many new possibilities for studying the strong interaction of light and matter. This system can also be exploited for quantum information processing and quantum communication and may lead to new approaches for single photon generation and detection.
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