678 research outputs found

    Role of the Built Environment in the Recovery From COVID-19: Evidence From a GIS-Based Natural Experiment on the City Blocks in Wuhan, China

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    The built environment closely relates to the development of COVID-19 and post-disaster recovery. Nevertheless, few studies examine its impacts on the recovery stage and corresponding urban development strategies. This study examines the built environment’s role in Wuhan’s recovery at the city block level through a natural experiment. We first aggregated eight built environmental characteristics (BECs) of 192 city blocks from the perspectives of density, infrastructure supply, and socioeconomic environment; then, the BECs were associated with the recovery rates at the same city blocks, based on the public “COVID-19-free” reports of about 7,100 communities over the recovery stages. The results showed that three BECs, i.e., “number of nearby designated hospitals,” “green ratio,” and “housing price” had significant associations with Wuhan’s recovery when the strict control measures were implemented. At the first time of reporting, more significant associations were also found with “average building age,” “neighborhood facility development level,” and “facility management level.” In contrast, no associations were found for “controlled residential land-use intensity” and “plot ratio” throughout the stages. The findings from Wuhan’s recovery pinpointing evidence with implications in future smart and resilient urban development are as follows: the accessibility of hospitals should be comprehensive in general; and the average housing price of a city block can reflect its post-disaster recoverability compared to that of the other blocks

    Multiple Functionality in Nanotube Transistors

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    Calculations of quantum transport in a carbon nanotube transistor show that such a device offers unique functionality. It can operate as a ballistic field-effect transistor, with excellent characteristics even when scaled to 10 nm dimensions. At larger gate voltages, channel inversion leads to resonant tunneling through an electrostatically defined nanoscale quantum dot. Thus the transistor becomes a gated resonant tunelling device, with negative differential resistance at a tunable threshold. For the dimensions considered here, the device operates in the Coulomb blockade regime, even at room temperature.Comment: To appear in Phys. Rev. Let

    Emerging Trade Patterns in a 3-Region Linear NEG Model: Three Examples

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    This chapter draws attention to a specific feature of a NEG model that uses linear (and not iso-elastic) demand functions, namely its ability to account for zero trade. Thus, it represents a suitable framework to study how changes in parameters that are typical for NEG models, such as trade costs and regional market size, not only shape the regional distribution of economic activity, but at the same time determine the emergence of additional trade links between formerly autarkic regions. We survey some related papers and present a three-region framework that potentially nests many possible trade patterns. To focus the analysis, we study in more detail three specific trade patterns frequently found in the EU trade network. We start with three autarkic regions; then we introduce the possibility that two regions trade with each other; and, finally, we allow for one region trading with the other two, but the latter are still not trading with each other. We find a surprising plethora of long-run equilibria each involving a specific regional distribution of economic activity and a specific pattern of trade links. We show how a reduction in trade costs shapes simultaneously industry location and the configuration of the trade network

    KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra

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    We announce the discovery of a highly inflated transiting hot Jupiter discovered by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with Teff=5754−55+54T_{\rm eff} = 5754_{-55}^{+54} K, log⁥g=4.078−0.054+0.049\log{g} = 4.078_{-0.054}^{+0.049}, [Fe/H]=0.272±0.038[Fe/H] = 0.272\pm0.038, an inferred mass M∗=1.211−0.066+0.078M_{*}=1.211_{-0.066}^{+0.078} M⊙_{\odot}, and radius R∗=1.67−0.12+0.14R_{*}=1.67_{-0.12}^{+0.14} R⊙_{\odot}. The planetary companion has mass MP=0.867−0.061+0.065M_P = 0.867_{-0.061}^{+0.065} MJM_{J}, radius RP=1.86−0.16+0.18R_P = 1.86_{-0.16}^{+0.18} RJR_{J}, surface gravity log⁥gP=2.793−0.075+0.072\log{g_{P}} = 2.793_{-0.075}^{+0.072}, and density ρP=0.167−0.038+0.047\rho_P = 0.167_{-0.038}^{+0.047} g cm−3^{-3}. The planet is on a roughly circular orbit with semimajor axis a=0.04571−0.00084+0.00096a = 0.04571_{-0.00084}^{+0.00096} AU and eccentricity e=0.035−0.025+0.050e = 0.035_{-0.025}^{+0.050}. The best-fit linear ephemeris is T0=2456883.4803±0.0007T_0 = 2456883.4803 \pm 0.0007 BJDTDB_{\rm TDB} and P=3.24406±0.00016P = 3.24406 \pm 0.00016 days. This planet is one of the most inflated of all known transiting exoplanets, making it one of the few members of a class of extremely low density, highly-irradiated gas giants. The low stellar log⁥g\log{g} and large implied radius are supported by stellar density constraints from follow-up light curves, plus an evolutionary and space motion analysis. We also develop a new technique to extract high precision radial velocities from noisy spectra that reduces the observing time needed to confirm transiting planet candidates. This planet boasts deep transits of a bright star, a large inferred atmospheric scale height, and a high equilibrium temperature of Teq=1675−55+61T_{eq}=1675^{+61}_{-55} K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies.Comment: Submitted to ApJ, feedback is welcom

    Mesoporous Carbon Microfibers for Electroactive Materials Derived from Lignocellulose Nanofibrils

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    The growing adoption of biobased materials for electronic, energy conversion, and storage devices has relied on high-grade or refined cellulosic compositions. Herein, lignocellulose nanofibrils (LCNF), obtained from simple mechanical fibrillation of wood, are proposed as a source of continuous carbon microfibers obtained by wet spinning followed by single-step carbonization at 900 °C. The high lignin content of LCNF (∌28% based on dry mass), similar to that of the original wood, allowed the synthesis of carbon microfibers with a high carbon yield (29%) and electrical conductivity (66 S cm–1). The incorporation of anionic cellulose nanofibrils (TOCNF) enhanced the spinnability and the porous morphology of the carbon microfibers, making them suitable platforms for electrochemical double layer capacitance (EDLC). The increased loading of LCNF in the spinning dope resulted in carbon microfibers of enhanced carbon yield and conductivity. Meanwhile, TOCNF influenced the pore evolution and specific surface area after carbonization, which significantly improved the electrochemical double layer capacitance. When the carbon microfibers were directly applied as fiber-shaped supercapacitors (25 F cm–3), they displayed a remarkably long-term electrochemical stability (>93% of the initial capacitance after 10 000 cycles). Solid-state symmetric fiber supercapacitors were assembled using a PVA/H2SO4 gel electrolyte and resulted in an energy and power density of 0.25 mW h cm–3 and 65.1 mW cm–3, respectively. Overall, the results indicate a green and facile route to convert wood into carbon microfibers suitable for integration in wearables and energy storage devices and for potential applications in the field of bioelectronics.</p

    Nanodiamond photocathodes for MPGD-based single photon detectors at future EIC

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    We are developing gaseous photon detectors for Cherenkov imaging applications in the experiments at the future Electron Ion Collider. CsI, converting photons in the far ultraviolet range, is, so far, the only photoconverter compatible with the operation of gaseous detectors. It is very delicate to handle due to its hygroscopic nature: the absorbed water vapour decomposes the CsI molecule. In addition, its quantum efficiency degrades under ion bombardment. These are the key reasons to quest for novel, less delicate materials for photocathodes adequate for gaseous photon detectors. Layers of hydrogenated nanodiamond particles have recently been proposed as an alternative material and have shown promising characteristics. The performance of nanodiamond photocathodes coupled to thick GEM-based detectors is the object of our ongoing R\&D. The first phase of these studies includes the characterization of thick GEM coated with nanodiamond layers and the robustness of its photoconverting properties with respect to the bombardment by ions from the multiplication process in the gaseous detector. The approach is described in detail as well as all the results obtained so far within these exploratory studies

    <i>Spitzer</i> microlens measurement of a massive remnant in a well-separated binary

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    We report the detection and mass measurement of a binary lens OGLE-2015-BLG-1285La,b, with the more massive component having M1 > 1.35 M⊙ (80% probability). A main-sequence star in this mass range is ruled out by limits on blue light, meaning that a primary in this mass range must be a neutron star (NS) or black hole (BH). The system has a projected separation r⊄ = 6.1 ± 0.4 AU and lies in the Galactic bulge. These measurements are based on the "microlens parallax" effect, i.e., comparing the microlensing light curve as seen from Spitzer, which lay at 1.25 AU projected from Earth, to the light curves from four ground-based surveys, three in the optical and one in the near-infrared. Future adaptive optics imaging of the companion by 30 m class telescopes will yield a much more accurate measurement of the primary mass. This discovery both opens the path and defines the challenges to detecting and characterizing BHs and NSs in wide binaries, with either dark or luminous companions. In particular, we discuss lessons that can be applied to future Spitzer and Kepler K2 microlensing parallax observations

    Transmission electron microscopic observations of nanobubbles and their capture of impurities in wastewater

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    Unique properties of micro- and nanobubbles (MNBs), such as a high adsorption of impurities on their surface, are difficult to verify because MNBs are too small to observe directly. We thus used a transmission electron microscope (TEM) with the freeze-fractured replica method to observe oxygen (O2) MNBs in solutions. MNBs in pure water and in 1% NaCl solutions were spherical or oval. Their size distribution estimated from TEM images close to that of the original solution is measured by light-scattered methods. When we applied this technique to the observation of O2 MNBs formed in the wastewater of a sewage plant, we found the characteristic features of spherical MNBs that adsorbed surrounding impurity particles on their surface

    Carbon nanotubes and hydrogen production from the pyrolysis catalysis or catalytic-steam reforming of waste tyres

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    A range of process conditions have been investigated to maximise the production of carbon nanotubes (CNTs) and/or hydrogen from waste tyres. A two-stage pyrolysis-catalytic reactor system was used and the influence of catalyst temperature (700, 800 and 900 °C), tyre: catalyst ratio (1:0.5, 1:1 and 1:2) and steam input (water injection 0, 2 and 5 ml h−1) to the second catalyst stage were investigated. The catalyst used was a Ni/Al2O3 catalyst prepared by a wetness impregnation technique. Carbon was deposited on the catalyst surface during pyrolysis-catalysis increasing with increasing catalyst temperature and also increasing as the tyre: catalyst ratio was raised. Examination of the carbon showed it to be composed of largely filamentous type carbons, producing 253.7 mg g−1 tyre of filamentous carbons at a tyre: catalyst ratio of 1:1 and catalyst temperature of 900 °C. A significant proportion of the deposited filamentous carbons were multi-walled carbon nanotubes as shown by transmission electron microscopy characterisation. The introduction of steam to the process enhanced hydrogen production, producing a maximum of 34.69 mmol g−1 tyre at a water injection rate of 5 ml h−1

    Quality and reporting of clinical guidelines for breast cancer treatment: A systematic review

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    Background: High-quality, well-reported clinical practice guidelines (CPGs) and consensus statements (CSs) underpinned by systematic reviews are needed. We appraised the quality and reporting of CPGs and CSs for breast cancer (BC) treatment. Methods: Following protocol registration (Prospero no: CRD42020164801), CPGs and CSs on BC treatment were identified, without language restrictions, through a systematic search of bibliographic databases (MEDLINE, EMBASE, Web of Science, Scopus, CDSR) and online sources (12 guideline databases and 51 professional society websites) from January 2017 to June 2020. Data were extracted in duplicate assessing overall quality using AGREE II (% of maximum score) and reporting compliance using RIGHT (% of total 35 items); reviewer agreement was 98% and 96% respectively. Results: There were 59 relevant guidance documents (43 CPGs, 16 CSs), of which 20 used systematic reviews for evidence synthesis. The median overall quality was 54.0% (IQR 35.9e74.3) and the median overall reporting compliance was 60.9% (IQR 44.5e84.4). The correlation between quality and reporting was 0.9. Compared to CSs, CPGs had better quality (55.4% vs 44.2%; p Π0.032) and reporting (67.18% vs 44.5%; p Π0.005). Compared to subjective methods of evidence analysis, guidance documents that used systematic reviews had better quality (76.3% vs 51.4%; p Π0.001) and reporting (87.1% vs 59.4%; p Π0.001). Conclusion: The quality and reporting of CPGs and CSs in BC treatment were moderately strong. Systematic reviews should be used to improve the quality and reporting of CPGs and CSs.Beatriz Galindo (senor modality) Program by the Ministry of Science, Innovation, and Universities of the Spanish Governmen
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