bluuebunny/crossref_metadata_2025 huggingface dataset:
Roxtec sealing technology protects rail infrastructure in Belgium
Authors: Atkinson Simon
Published: June 2018

In the February 2018 issue of Sealing Technology (page 1) we briefly explained how products from Swedish Roxtec Group – a provider of modular-based cable and pipe seals – are being used to prevent water from leaking into a utility tunnel in China. This brief article shows how the firm's technology is also helping to protect rail infrastructure in Belgium.
Computed tomography analyses damage to raw materials under load
Authors: Atkinson Simon
Published: June 2018

Germany's Fraunhofer Institute for Structural Durability and System Reliability LBF recently developed a new method to characterise materials. It provides materials designers, manufacturers and scientists with information that gives them a better understanding of material behaviour and characterisation.
The structure and origin of confined Holmboe waves
Authors: Lefauve Adrien , Partridge J. L. , Zhou Qi , Dalziel S. B. , Caulfield C. P. , Linden P. F.
Published: June 2018

Finite-amplitude manifestations of stratified shear flow instabilities and their spatio-temporal coherent structures are believed to play an important role in turbulent geophysical flows. Such shear flows commonly have layers separated by sharp density interfaces, and are therefore susceptible to the so-called Holmboe instability, and its finite-amplitude manifestation, the Holmboe wave. In this paper, we describe and elucidate the origin of an apparently previously unreported long-lived coherent structure in a sustained stratified shear flow generated in the laboratory by exchange flow through an inclined square duct connecting two reservoirs filled with fluids of different densities. Using a novel measurement technique allowing for time-resolved, near-instantaneous measurements of the three-component velocity and density fields simultaneously over a three-dimensional volume, we describe the three-dimensional geometry and spatio-temporal dynamics of this structure. We identify it as a finite-amplitude, nonlinear, asymmetric confined Holmboe wave (CHW), and highlight the importance of its spanwise (lateral) confinement by the duct boundaries. We pay particular attention to the spanwise vorticity, which exhibits a travelling, near-periodic structure of sheared, distorted, prolate spheroids with a wide ‘body’ and a narrower ‘head’. Using temporal linear stability analysis on the two-dimensional streamwise-averaged experimental flow, we solve for three-dimensional perturbations having two-dimensional, cross-sectionally confined eigenfunctions and a streamwise normal mode. We show that the dispersion relation and the three-dimensional spatial structure of the fastest-growing confined Holmboe instability are in good agreement with those of the observed confined Holmboe wave. We also compare those results with a classical linear analysis of two-dimensional perturbations (i.e. with no spanwise dependence) on a one-dimensional base flow. We conclude that the lateral confinement is an important ingredient of the confined Holmboe instability, which gives rise to the CHW, with implications for many inherently confined geophysical flows such as in valleys, estuaries, straits or deep ocean trenches. Our results suggest that the CHW is an example of an experimentally observed, inherently nonlinear, robust, long-lived coherent structure which has developed from a linear instability. We conjecture that the CHW is a promising candidate for a class of exact coherent states underpinning the dynamics of more disordered, yet continually forced stratified shear flows.
Partially filled pipes: experiments in laminar and turbulent flow
Authors: Ng Henry C.-H. , Cregan Hope L. F. , Dodds Jonathan M. , Poole Robert J. , Dennis David J. C.
Published: June 2018

Pressure-driven laminar and turbulent flow in a horizontal partially filled pipe was investigated using stereoscopic particle imaging velocimetry (S-PIV) in the cross-stream plane. Laminar flow velocity measurements are in excellent agreement with a recent theoretical solution in the literature. For turbulent flow, the flow depth was varied independently of a nominally constant Reynolds number (based on hydraulic diameter, $D_{H}$; bulk velocity, $U_{b}$ and kinematic viscosity $\unicode[STIX]{x1D708}$) of $Re_{H}=U_{b}D_{H}/\unicode[STIX]{x1D708}\approx 30\,000\pm 5\,\%$. When running partially full, the inferred friction factor is no longer a simple function of Reynolds number, but also depends on the Froude number $Fr=U_{b}/\sqrt{gD_{m}}$ where $g$ is gravitational acceleration and $D_{m}$ is hydraulic mean depth. S-PIV measurements in turbulent flow reveal the presence of secondary currents which causes the maximum streamwise velocity to occur below the free surface consistent with results reported in the literature for rectangular cross-section open channel flows. Unlike square duct and rectangular open channel flow the mean secondary motion observed here manifests only as a single pair of vortices mirrored about the vertical bisector and these rollers, which fill the half-width of the pipe, remain at a constant distance from the free surface even with decreasing flow depth for the range of depths tested. Spatial distributions of streamwise Reynolds normal stress and turbulent kinetic energy exhibit preferential arrangement rather than having the same profile around the azimuth of the pipe as in a full pipe flow. Instantaneous fields reveal the signatures of elements of canonical wall-bounded turbulent flows near the pipe wall such as large-scale and very-large-scale motions and associated hairpin packets whilst near the free surface, the signatures of free surface turbulence in the absence of imposed mean shear such as ‘upwellings’, ‘downdrafts’ and ‘whirlpools’ are present. Two-point spatio-temporal correlations of streamwise velocity fluctuation suggest that the large-scale coherent motions present in full pipe flow persist in partially filled pipes but are compressed and distorted by the presence of the free surface and mean secondary motion.
Eulerian modelling of gas–solid flows with triboelectric charging
Authors: Kolehmainen Jari , Ozel Ali , Sundaresan Sankaran
Published: June 2018

Particles subjected to flow are known to acquire electrostatic charges through repeated contacts with each other and with other surfaces. These charges alter gas–particle flow behaviour at different scales. In this work, we present a continuum framework for analysing the interplay between tribocharging and the flow of a monodisperse assembly of particles characterized by a single effective work function. Specifically, we have derived the continuum, kinetic theory transport equations for gas–particle flow and local-averaged charge on particles directly from the Boltzmann equation. We also derive the auxiliary conditions to capture tribocharging at bounding conducting walls. The resulting two-fluid model with tribocharging and boundary conditions has then been validated against results from discrete element simulations that have been specially designed to probe specific terms in the models.
The merger of geophysical vortices at finite Rossby and Froude number
Authors: Reinaud Jean N. , Dritschel David G.
Published: June 2018

We investigate the merger of two co-rotating geophysical vortices at finite Rossby and Froude number. The initial conditions consist of two uniform potential vorticity vortices in near-equilibrium and in a nearly ‘balanced’ state (i.e. with negligible emission of inertia–gravity wave radiation). We determine the critical merger distance between the two vortices. This distance is found to increase with the magnitude of the Rossby number: intense cyclones or intense anticyclones are able to merge from further apart compared to weaker cyclones and anticyclones. Note that the Froude number is proportional to the Rossby number for the near-equilibrium initial conditions considered. The critical merging distance also depends on the sign of the potential vorticity anomaly, which is positive for ‘cyclones’ and negative for ‘anticyclones’. We show that ageostrophic motions occurring at finite Rossby number tend to draw cyclones together but draw anticyclones apart. On the other hand, we show that anticyclones tend to deform more, in particular when subject to vertical shear (as when the vortices are vertically offset). These two effects compete. Overall, nearly aligned cyclones tend to merge from further apart than their anticyclonic counterparts, while vertically offset anticyclones merge from further apart than cyclones.
Global and Regional Emissions of Radiocarbon from Nuclear Power Plants from 1972 to 2016
Authors: Zazzeri G , Acuña Yeomans E , Graven H D
Published: June 2018

CH4 and CO2 emissions from geologic sources, which are devoid of radiocarbon (14C), dilute the atmospheric 14C/C ratio. Observations of 14C/C can be used to estimate fossil fuel-derived CH4 and CO2. However, the atmospheric 14C/C ratio is perturbed by emissions of 14C from nuclear power plants (NPPs) and fuel reprocessing sites, which may affect such 14C/C-based estimation if they are not correctly quantified. We calculate NPP 14C emissions for CO2 and CH4 from 1972–2016 using standard emission factors (14C emitted per unit of power produced) and analyze trends in global and regional emissions. We use available observations of 14C emissions and power generation in Europe to assess emission factors for different reactor types, as well as potential differences related to the age or manufacturer of the NPPs. Globally, nuclear 14C emissions increase until 2005 and then decrease, mostly because of the closure of gas-cooled reactors in the United Kindom and the shutdown of light water reactors after the Fukushima nuclear accident in March 2011. Observed emission factors in Europe show strong variability, spanning values from 0.003 to 2.521 TBq/GWa for PWR and from 0.007 to 1.732 TBq/GWa for BWR reactors, suggesting more information and more sophisticated models are needed to improve estimates of 14C emissions.
Molecular dynamics calculation of the spectral densities of plasma fluctuations
Authors: Panarese A. , Bruno D. , Tolias P. , Ratynskaia S. , Longo S. , de Angelis U.
Published: June 2018

Spectral densities of plasma fluctuations are calculated for the thermal case using classical molecular dynamics (MD) assuming Coulomb interactions and a short-range cutoff radius. The aim of the calculation is to verify limits and performances of such calculations in the light of possible generalizations, e.g. collisional or non-ideal plasmas. Results are presented for ideal, collisionless, fully ionized thermal plasmas. Comparison with the analytical theory reveals a generally satisfactory agreement with possibility for improvement when more strict numerical parameters are used albeit with a strong increase in computational cost. The largest deviations have been observed in the vicinity of the weakly damped eigenmodes. The agreement is strong in other parts of the spectrum, where Landau damping is prominent, and overcomes the effects stemming from the excess collisionality and coupling as well as from the exclusion of short-range collisions.
Minimal perturbation flows that trigger mean field dynamos in shear flows
Authors: Herreman W.
Published: June 2018

Using a variational optimization method we find the smallest flow perturbations that can trigger kinematic dynamo action in Kolmogorov flow. In comparison to previous work, a second-order mean field dynamo model is used to track down the optimal dynamos in the high magnetic Reynolds number limit ($Rm$). The magnitude of minimal perturbation flows decays inversely proportional to the magnetic Reynolds number. We reveal the asymptotic high-$Rm$ structure of the optimal flow perturbation and the magnetic eigenmode. We identify the optimal dynamo as of $\unicode[STIX]{x1D6FC}{-}\unicode[STIX]{x1D6FA}$ type, with magnetic fluctuations that localize on a critical layer.
An update on sarcocystosis in one-humped camels (Camelus dromedarius)
Authors: Saeed Muhammad A. , Vaughan Jane L. , Jabbar Abdul
Published: June 2018

Sarcocystis spp. are intracellular coccidian parasites which infect domestic and wild animals and birds, resulting in considerable economic losses in production animals, and public health concerns worldwide. Sarcocystis spp. have an indirect life cycle where wild and/or domestic canine species primarily serve as definitive hosts and several domestic and wild animals (such as camels) act as intermediate hosts. In Northern Africa, the Middle East, Central Asia and China, camel meat is preferred due to cultural and religious traditions as well as its lower cholesterol/fat content than other red meat. However, camel meat quality could be downgraded by the presence of sarcocysts. To date, two Sarcocystis spp. have been reported from camels, including Sarcocystis ippeni (forms microscopic sarcocysts) and Sarcocystis cameli (forms both macroscopic and microscopic sarcocysts). Sarcocystosis is usually asymptomatic, though significant pathogenic effects have also been reported in camels. Despite the high occurrence of sarcocystosis in camels, little is known about various aspects of the disease in these animals. This paper provides a comprehensive review of the existing knowledge on the taxonomy, pathogenesis, epidemiology and diagnosis of Sarcocystis spp. infecting camels and it also highlights areas for further research that could enhance our understanding about sarcocystosis in camels.
Pytheas, Tacitus and Thule
Authors: Breeze David J. , Wilkins Alan
Published: June 2018

The ancient sources for the location of Thule are reviewed.1 It is suggested that the identification of the Shetland Isles as Thule was an error by Agricola. The identification was then accepted by Ptolemy, who moved Thule from the more northerly location implied by Pytheas’ account to the site of the Shetland Isles. This would account for his description of Thule/Shetland as one island. The coincident location of Ptolemy's Thule with Shetland suggests that the Roman fleet did see the islands. The emendations of Wolfson relating to Thule are examined and rejected. There is no evidence that Agricola's fleet landed in Shetland.
Creature Comforts at Vindolanda: Two Unique Wool Mats with Knotted Pile
Authors: Wild John Peter , Walton Rogers Penelope
Published: June 2018

Fragments of two robust wool textiles with an unusual knotted blue pile were recovered from a Period I (late Flavian) fort ditch at Vindolanda. Their knotted structure — unknown hitherto in the western Roman provinces and only partially paralleled in the eastern — is discussed, together with questions about their possible production centre and actual function. The Supplementary Material available online (https://doi.org/10.1017/S0068113X18000259) contains technical details of the textiles, an investigation of the raw materials and a comparison of the wools used.
A TOA/AOA Underwater Acoustic Positioning System Based on the Equivalent Sound Speed
Authors: Xin Mingzhen , Yang Fanlin , Wang Faxing , Shi Bo , Zhang Kai , Liu Hui
Published: June 2018

High-precision underwater positioning must eliminate the influence of refraction artefacts. Since a Time Of Arrival - Global Navigation Satellite System Intelligent Buoys (TOA-GIB) system does not measure incident beam angles, common refraction correction methods cannot be directly used for refraction artefacts. An Equivalent Sound Speed (ESS) iteration method is proposed and is based on the transformation relations between depth, the ESS gradient and the incident beam angle. On this basis, a TOA/AOA-GIB system without a real-time Sound Speed Profile (SSP) is proposed to estimate the target position and the ESS gradient as unknown parameters. The results from a simulation experiment show that the positioning accuracy of a TOA/AOA-GIB system is better than 0·07% of water depth when the accuracy of the incident beam angle is 0·1°.
Seedsvsfungi: an enzymatic battle in the soil seedbank
Authors: Pollard Anne T.
Published: June 2018

Depleting the soil weed seedbank is an important integrated weed management strategy that has the potential to foster lasting weed control. Long-term dormancy and decay resistance of weed seeds pose a challenge to weed eradication efforts. Select soil fungi have been shown to cause significant decay of weed seeds. The physical and chemical mechanisms by which seeds in the seedbank defend themselves against pathogens have been well researched. However, very few studies have purposefully investigated the biochemical defence response of seeds. Enzyme-based biochemical seed defences have been detected in dormant and non-dormant seeds, and research supports their function in pathogen defence. This review summarizes current knowledge of the seed defence enzymes polyphenol oxidase, peroxidase, chitinase and oxalate oxidase. The fungal enzymes chitinase, protease and xylanase that function in pathogenesis of seeds in the soil seedbank are also reviewed. Progress in the development and standardization ofin situenzyme analyses fosters our understanding of actual enzyme activity present in soils, while high-throughput microplate techniques promote efficiency and enable greater scope. Application of genomic, proteomic and transcriptomic techniques to glean a deeper and more holistic understanding of the enzymatic interactions of weed seeds and soil fungi in the soil seedbank will support the development of improved integrated weed management strategies.
Mineralogical Characterization of Hispano-Moresque Glazes: A µ-Raman and Scanning Electron Microscopy with X-Ray Energy Dispersive Spectrometry (SEM-EDS) Study
Authors: Coentro Susana , da Silva Rui C. , Relvas Cátia , Ferreira Teresa , Mirão José , Pleguezuelo Alfonso , Trindade Rui , Muralha Vânia S. F.
Published: June 2018

This work explores the combination of µ-Raman spectroscopy and scanning electron microscopy with X-ray energy dispersive spectrometry (SEM-EDS) for the study of the glazes in 15th–16th century Hispano-Moresque architectural tiles. These are high lead glazes that can be tin-opacified or transparent, and present five colors: tin-white, cobalt-blue, copper-green, iron-amber, and manganese-brown. They are generally homogenous and mineral inclusions are mostly concentrated in the glaze-ceramic interface. Through SEM-EDS, these inclusions were observed and chemically analyzed, whereas µ-Raman allowed their identification on a molecular level. K-feldspars, wollastonite and diopside were the most common compounds, as well as cassiterite agglomerates that render the glaze opaque. Malayaite was identified in green glazes, and andradite and magnesioferrite in amber glazes. Co–Ni–ferrites were identified in blue glazes, as well as Ni–Fe–olivines. Manganese-brown is the color where most compounds were identified: bustamite, jacobsite, hausmannite, braunite, and kentrolite. Through the µ-Raman analysis of different areas in large inclusions previously observed by SEM, it was possible to identify intermediate phases that illustrate the reaction process that occurs between the color-conferring compounds and the surrounding lead glaze. Furthermore, the obtained results allowed inference of the raw materials and firing temperatures used on the manufacture of these tiles.
The Influence of Environmental Factors on Germination of Burcucumber (Sicyos angulatus) Seeds: Implications for Range Expansion and Management
Authors: Önen Huseyin , Farooq Shahid , Tad Sonnur , Özaslan Cumali , Gunal Hikmet , Chauhan Bhagirath S
Published: June 2018

Burcucumber (Sicyos angulatusL.) is a highly invasive vine that has become naturalized in the humid Black Sea region of Turkey, but previous to this study there was no information on the germination biology of this weed. The germination biology of three naturalized populations ofS. angulatusfrom the Black Sea region was studied in laboratory and greenhouse experiments. The germination of nondormant seeds was observed under different photoperiods, constant temperatures, and varying levels of pH, salinity, and osmotic potential. Furthermore, seedling emergence from various soil depths was investigated. The seeds of all populations proved nonphotoblastic (82% to 90%, 55% to 66%, and 48% to 56% germination under 12-, 24-, and 0-h photoperiod, respectively) and germinated over a wide range of temperatures (5 to 40 C). Seedlings emerged from all seed burial depths (0 to 15 cm); however, germination was drastically reduced (>90% reduction) beyond 6 to 8 cm. Seed germination was 30% to 38% for seeds placed on the surface and increased to 78% to 88% for seeds buried 2 cm deep, while germination was severely reduced for seeds buried 10 and 15 cm deep (8 to 12% and 0 to 6%, respectively). Seeds of all populations were found to be sensitive to osmotic and salinity stress and to highly acidic and alkaline pH levels. All populations had similar requirements for germination that are directly related to their area of naturalization. These results indicate that the species has limited potential for range expansion to arid, semiarid (nonirrigated), and relatively saline areas. However, humid, salinity-free, and frequently irrigated areas of the country are at high risk of invasion. In arable lands, deep tillage followed by shallow tillage and effective management of emerging seedlings could deplete the soil seedbank in the long run. However, there is an urgent need for effective strategies to manage the species in other nonarable areas.
Crustal Formation on a Spreading Ridge Above a Mantle Plume: Receiver Function Imaging of the Icelandic Crust
Authors: Jenkins J. , Maclennan J. , Green R. G. , Cottaar S. , Deuss A. F. , White R. S.
Published: June 2018

Iceland sits astride a mid‐ocean ridge underlain by a mantle hot spot. The interplay of these two geological processes has the potential to generate a complex and laterally variable crustal structure. The thickness of the Icelandic crust is a long running and controversial debate, with estimates ranging from a thin 20‐km crust to a thick 40‐km crust. We present new images of the first‐order seismic discontinuity structure of the Icelandic crust based on a joint inversion of receiver function and ambient noise‐derived surface wave dispersion data. Inversion results are validated through comparison to receiver functions multiphase common conversion point stacks across the densely instrumented Northern Volcanic Zone. We find a multilayered crustal structure consisting of a 6‐ to 10‐km‐thick upper crust underlain by either one or two discontinuities. The shallower discontinuity is found at depths of ≈20 km throughout Iceland. The deeper discontinuity is only present in some regions, defining the base of a lens‐like lower layer with maximum depths of 44 km above the center of the mantle plume. Either of these two discontinuities could be interpreted as the seismic Moho, providing an explanation why previous estimates of crustal thickness have diverged. Such structure may form via underplating of a preexisting oceanic crust as has been hypothesized in other ocean island plume settings. However, we demonstrate with a simple petrological model that variability in seismic discontinuity structure can also be understood as a consequence of compositional variation in melts generated with distance from the plume center.
P Wave Arrival Picking and First‐Motion Polarity Determination With Deep Learning
Authors: Ross Zachary E. , Meier Men‐Andrin , Hauksson Egill
Published: June 2018

Determining earthquake hypocenters and focal mechanisms requires precisely measured P wave arrival times and first‐motion polarities. Automated algorithms for estimating these quantities have been less accurate than estimates by human experts, which are problematic for processing large data volumes. Here we train convolutional neural networks to measure both quantities, which learn directly from seismograms without the need for feature extraction. The networks are trained on 18.2 million manually picked seismograms for the Southern California region. Through cross validation on 1.2 million independent seismograms, the differences between the automated and manual picks have a standard deviation of 0.023 s. The polarities determined by the classifier have a precision of 95% when compared with analyst‐determined polarities. We show that the classifier picks more polarities overall than the analysts, without sacrificing quality, resulting in almost double the number of focal mechanisms. The remarkable precision of the trained networks indicates that they can perform as well, or better, than expert seismologists.
Along‐Arc Heterogeneity of the Seismic Structure Around a Large Coseismic Shallow Slip Area of the 2011 Tohoku‐Oki Earthquake: 2‐D Vp Structural Estimation Through an Air Gun‐Ocean Bottom Seismometer Experiment in the Japan Trench Subduction Zone
Authors: Azuma R. , Hino R. , Ohta Y. , Ito Y. , Mochizuki K. , Uehira K. , Murai Y. , Sato T. , Takanami T. , Shinohara M. , Kanazawa T.
Published: June 2018

The 2011 Tohoku‐oki earthquake occurred with a rupture length of 500 km along the Japan Trench, causing a large slip (>30 m) at the shallowest portion of the plate boundary fault south of 39°N off Miyagi and a smaller slip (~10 m) north of 39°N off Sanriku, the northern part of the source area. We estimated the P wave velocity (Vp) structure around the shallowest portion of the plate boundary along the trench to investigate the spatial correlation between the structural variation and coseismic shallow slip distribution of the 2011 earthquake. For this purpose, we analyzed data from an air gun‐ocean bottom seismometer survey on an along‐arc line on the lower part of the landward slope of the Japan Trench. We detected a high Vp zone in the hanging wall of the plate interface off Miyagi, which corresponds to the Cretaceous backstop. The Vp model also showed the absence of the high Vp zone off Sanriku. This suggests that the low‐Vp deformed prism is wider off Sanriku than off Miyagi. Therefore, the backstop is close to the trench particularly off Miyagi. We suggest a correlation between this along‐arc variation of the hanging wall side structure and the extent of the coseismic shallow slip in the trench axial region; the large slip reached the trench off Miyagi but not off Sanriku.
Chinese Provinces' CO2 Emissions Embodied in Imports and Exports
Authors: Wu Sanmang , Wu Yanrui , Lei Yalin , Li Shantong , Li Li
Published: June 2018

In this study, we use input‐output analysis to measure CO2 emissions (CEs) embodied in Chinese provinces' exports and imports and explore the interprovincial spillover of CEs induced by exports through the domestic supply chains. The findings of this paper are as follows: Eastern provinces were the main production locations of CO2 emissions embodied in exports (EEE) and the major demand locations of CO2 emissions embodied in imports (EEI) in China. The sum of the Eastern provinces' EEE accounted for approximately 60% of the national EEE, and the sum of the Eastern provinces' EEI accounted for approximately 80% of the national EEI in 2012. However, the central and western provinces were the primary source locations of China's balance of CO2 emissions embodied in international trade (BEET). In 2012, the proportion of the central and western provinces' BEET in the national BEET was more than 90%. The exports of eastern provinces have an important spillover effect on CEs in the central and western provinces. The proportion of CEs of central provinces caused by eastern provinces' exports in central provinces' EEE was 70.21%, and the corresponding proportion in western provinces was 69.65% in 2012. The reason for this is that the central and western provinces were the primary providers of highly energy‐intensive intermediate products for eastern provinces' exports, and the central and western provinces' large amounts of CEs were caused by the eastern provinces' exports through the domestic supply chains. According to the empirical results of the study, some policy recommendations are given.
Highly Oblique Lower‐Band Chorus Statistics: Dependencies of Wave Power on Refractive Index and Geomagnetic Activity
Authors: Shi R. , Mourenas D. , Artemyev A. , Li W. , Ma Q.
Published: June 2018

We use 3 years of Van Allen Probes observations of highly oblique lower‐band chorus waves at low latitudes over L = 4–6 to provide a comprehensive statistics of the distribution of their magnetic and electric powers and full energy density as a function of wave refractive index N, L shell, and geomagnetic activity AE. We use the refractive index calculated either in the cold plasma approximation or in the quasi‐electrostatic (hot plasma) approximation and either observed wave electric fields or corrected wave electric fields accounting for the formation of a plasma sheath around antenna probes in a low‐density plasma. Approximate fits to the maximum refractive index and to the magnetic wave power profile of highly oblique waves are provided as a function of AE and L. Such fits should be useful for simulations of quasi‐linear electron diffusion induced by very oblique chorus waves. The magnetic wave power of these oblique waves remains elevated and roughly constant up to higher N values at lower L < 5 and during less disturbed periods AE∗<200 nT, likely due to the corresponding lower temperature of hot electrons injected from the plasma sheet, which leads to weaker thermal effects and Landau damping of these very oblique waves. The average energy density of lower‐band chorus waves is mainly distributed from N = 30–50 up to N = 150–300, mostly corresponding to highly oblique waves even at low magnetic latitudes.
Complex Near‐Surface Rheology Inferred From the Response of Greater Tokyo to Strong Ground Motions
Authors: Viens Loïc , Denolle Marine A. , Hirata Naoshi , Nakagawa Shigeki
Published: June 2018

Strong ground motion can induce dynamic strains large enough for the Earth's subsurface to respond nonlinearly and to cause permanent, or plastic, damage. The 2011Mw9.0 Tohoku‐Oki earthquake, Japan, generated exceptional and well‐recorded ground motions in the greater Tokyo area. We use continuous records from 234 stations of the dense MeSO‐net seismic network to monitor the temporal evolution of the material properties of the shallow subsurface (upper ∼100 m). We apply the single‐station cross‐correlation method to reconstruct the near‐surface reflectivity response through time. We find that the strong ground motions from the mainshock caused large perturbations in the near‐surface structure, with significant drops in seismic velocities up to 11%. For most sites, we observe a logarithmic and complete recovery of the seismic wave speed, suggesting a relaxation process that can be explained by a viscoelastic rheology. Some sites exhibit an instantaneous and permanent change, which suggests a plastic rheology. Finally, dense seismic measurements allow for statistical inference between seismic velocity drops, recovery time scales, and permanent perturbations and ground motion strength and site conditions. This study highlights the potential for seismic interferometry to assess near‐surface rheology with dense seismic arrays.
The Regional Impact of Urban Heat Mitigation Strategies on Planetary Boundary Layer Dynamics Over a Semiarid City
Authors: Song Jiyun , Wang Zhi‐Hua , Wang Chenghao
Published: June 2018

The rapid urbanization and associated landscape changes strongly modulate heat and moisture transfer processes on the urban surface as well as in the planetary boundary layer (PBL) via urban land‐atmosphere interactions. In this study, we employed the mesoscale Weather Research and Forecasting (WRF) model with realistic urban dynamics to assess the effects of two urban landscaping strategies for urban heat mitigation (viz., green roofs and white roofs) on the PBL dynamics for hot summer periods over a semiarid city, Phoenix of Arizona. Our results show that the effects of green roofs and white roofs on PBL dynamics are markedly different at daytime and nighttime. At daytime, both roofing systems reduce the sensible heat flux significantly by ~150 W/m2, lower the PBL height by ~700 m, and decrease the maximum convective available potential energy (CAPE) by ~40 J/kg over the built terrain. At nighttime, both sensible and latent heat fluxes increase with green roofs by ~4 and ~6 W/m2, respectively. In contrast, with white roofs, a marginal reduction of sensible heat flux by ~4 W/m2 was observed, owing to the remnant effect of daytime cooling. In addition, both roofing systems reduce the CAPE over the urban core but increase the CAPE over the rural surrounding, implying that the use of green or white roofs may potentially enhance the probability of precipitation toward the outskirt of the city.
Room-temperature continuous-wave electrically pumped InGaN/GaN quantum well blue laser diode directly grown on Si
Authors: Sun Yi , Zhou Kun , Feng Meixin , Li Zengcheng , Zhou Yu , Sun Qian , Liu Jianping , Zhang Liqun , Li Deyao , Sun Xiaojuan , Li Dabing , Zhang Shuming , Ikeda Masao , Yang Hui
Published: June 2018

Current laser-based display and lighting applications are invariably using blue laser diodes (LDs) grown on free-standing GaN substrates, which are costly and smaller in size compared with other substrate materials.1–3 Utilizing less expensive and large-diameter Si substrates for hetero-epitaxial growth of indium gallium nitride/gallium nitride (InGaN/GaN) multiple quantum well (MQW) structure can substantially reduce the cost of blue LDs and boost their applications. To obtain a high crystalline quality crack-free GaN thin film on Si for the subsequent growth of a blue laser structure, a hand-shaking structure was formed by inserting Al-composition step down-graded AlN/AlxGa1−xN buffer layers between GaN and Si substrate. Thermal degradation in InGaN/GaN blue MQWs was successfully suppressed with indium-rich clusters eliminated by introducing hydrogen during the growth of GaN quantum barriers (QBs) and lowering the growth temperature for the p-type AlGaN/GaN superlattice optical cladding layer. A continuous-wave (CW) electrically pumped InGaN/GaN quantum well (QW) blue (450 nm) LD grown on Si was successfully demonstrated at room temperature (RT) with a threshold current density of 7.8 kA/cm2.
Top-down feedback controls spatial summation and response amplitude in primate visual cortex
Authors: Nurminen Lauri , Merlin Sam , Bijanzadeh Maryam , Federer Frederick , Angelucci Alessandra
Published: June 2018

Sensory information travels along feedforward connections through a hierarchy of cortical areas, which, in turn, send feedback connections to lower-order areas. Feedback has been implicated in attention, expectation, and sensory context, but the mechanisms underlying these diverse feedback functions are unknown. Using specific optogenetic inactivation of feedback connections from the secondary visual area (V2), we show how feedback affects neural responses in the primate primary visual cortex (V1). Reducing feedback activity increases V1 cells’ receptive field (RF) size, decreases their responses to stimuli confined to the RF, and increases their responses to stimuli extending into the proximal surround, therefore reducing surround suppression. Moreover, stronger reduction of V2 feedback activity leads to progressive increase in RF size and decrease in response amplitude, an effect predicted by a recurrent network model. Our results indicate that feedback modulates RF size, surround suppression and response amplitude, similar to the modulatory effects of visual spatial attention.
Author Correction: RNA cytosine methylation and methyltransferases mediate chromatin organization and 5-azacytidine response and resistance in leukaemia
Authors: Cheng Jason X. , Chen Li , Li Yuan , Cloe Adam , Yue Ming , Wei Jiangbo , Watanabe Kenneth A. , Shammo Jamile M. , Anastasi John , Shen Qingxi J. , Larson Richard A. , He Chuan , Le Beau Michelle M. , Vardiman James W.
Published: June 2018

In the originally published version of this Article, the GAPDH loading control blot in Fig. 1a was inadvertently replaced with a duplicate of the DNMT2 blot in the same panel during assembly of the figure. This has now been corrected in both the PDF and HTML versions of the Article.
Expansion of a superconducting vortex core into a diffusive metal
Authors: Stolyarov Vasily S. , Cren Tristan , Brun Christophe , Golovchanskiy Igor A. , Skryabina Olga V. , Kasatonov Daniil I. , Khapaev Mikhail M. , Kupriyanov Mikhail Yu. , Golubov Alexander A. , Roditchev Dimitri
Published: June 2018

Vortices in quantum condensates exist owing to a macroscopic phase coherence. Here we show, both experimentally and theoretically, that a quantum vortex with a well-defined core can exist in a rather thick normal metal, proximized with a superconductor. Using scanning tunneling spectroscopy we reveal a proximity vortex lattice at the surface of 50 nm—thick Cu-layer deposited on Nb. We demonstrate that these vortices have regular round cores in the centers of which the proximity minigap vanishes. The cores are found to be significantly larger than the Abrikosov vortex cores in Nb, which is related to the effective coherence length in the proximity region. We develop a theoretical approach that provides a fully self-consistent picture of the evolution of the vortex with the distance from Cu/Nb interface, the interface impedance, applied magnetic field, and temperature. Our work opens a way for the accurate tuning of the superconducting properties of quantum hybrids.
Author Correction: ID3 regulates the MDC1-mediated DNA damage response in order to maintain genome stability
Authors: Lee Jung-Hee , Park Seon-Joo , Hariharasudhan Gurusamy , Kim Min-Ji , Jung Sung Mi , Jeong Seo-Yeon , Chang In-Youb , Kim Cheolhee , Kim Eunae , Yu Jihyeon , Bae Sangsu , You Ho Jin
Published: June 2018

This Article contains errors in Fig. 3, Fig. 4 and Fig. 7, for which we apologize. In Fig. 3, panel ‘b’, the 0.5 hour time point after Ku55933 treatment images were inadvertently replaced with duplicates of the 3 hour time point after Ku55933 treatment images in Fig. 3b. Additionally, in panel ‘b’, the 0.5 hour time point after Nu7026 treatment images were inadvertently replaced with duplicates of the 180 min time point after siMDC1 treatment images in Fig. 3d. In Fig. 4, panel ‘g’, RNF168 foci in U2OS cell images were inadvertently replaced with duplicates of RNF168 foci in HeLa cell images in Fig. 4f. In Fig. 7, panel ‘b’, the DAPI images 0.5 hours after IR under siID3 treatment were inadvertently replaced with DAPI images of a different field of view from the same experiment. Additionally, in panel ‘i’, the shID3 mock-treated GFP-ID3 cells image was inadvertently replace with duplications of the shID3 mock-treated GFP-ID3 cells image in Fig. 7g.
In situ atomistic insight into the growth mechanisms of single layer 2D transition metal carbides
Authors: Sang Xiahan , Xie Yu , Yilmaz Dundar E. , Lotfi Roghayyeh , Alhabeb Mohamed , Ostadhossein Alireza , Anasori Babak , Sun Weiwei , Li Xufan , Xiao Kai , Kent Paul R. C. , van Duin Adri C. T. , Gogotsi Yury , Unocic Raymond R.
Published: June 2018

Developing strategies for atomic-scale controlled synthesis of new two-dimensional (2D) functional materials will directly impact their applications. Here, using in situ aberration-corrected scanning transmission electron microscopy, we obtain direct insight into the homoepitaxial Frank–van der Merwe atomic layer growth mechanism of TiC single adlayers synthesized on surfaces of Ti3C2 MXene substrates with the substrate being the source material. Activated by thermal exposure and electron-beam irradiation, hexagonal TiC single adlayers form on defunctionalized surfaces of Ti3C2 MXene at temperatures above 500 °C, generating new 2D materials Ti4C3 and Ti5C4. The growth mechanism for a single TiC adlayer and the energies that govern atom migration and diffusion are elucidated by comprehensive density functional theory and force-bias Monte Carlo/molecular dynamics simulations. This work could lead to the development of bottom-up synthesis methods using substrates terminated with similar hexagonal-metal surfaces, for controllable synthesis of larger-scale and higher quality single-layer transition metal carbides.
Drivers of woody plant encroachment over Africa
Authors: Venter Z. S. , Cramer M. D. , Hawkins H.-J.
Published: June 2018

While global deforestation induced by human land use has been quantified, the drivers and extent of simultaneous woody plant encroachment (WPE) into open areas are only regionally known. WPE has important consequences for ecosystem functioning, global carbon balances and human economies. Here we report, using high-resolution satellite imagery, that woody vegetation cover over sub-Saharan Africa increased by 8% over the past three decades and that a diversity of drivers, other than CO2, were able to explain 78% of the spatial variation in this trend. A decline in burned area along with warmer, wetter climates drove WPE, although this has been mitigated in areas with high population growth rates, and high and low extremes of herbivory, specifically browsers. These results confirm global greening trends, thereby bringing into question widely held theories about declining terrestrial carbon balances and desert expansion. Importantly, while global drivers such as climate and CO2 may enhance the risk of WPE, managing fire and herbivory at the local scale provides tools to mitigate continental WPE.
SKP2- and OTUD1-regulated non-proteolytic ubiquitination of YAP promotes YAP nuclear localization and activity
Authors: Yao Fan , Zhou Zhicheng , Kim Jongchan , Hang Qinglei , Xiao Zhenna , Ton Baochau N. , Chang Liang , Liu Na , Zeng Liyong , Wang Wenqi , Wang Yumeng , Zhang Peijing , Hu Xiaoyu , Su Xiaohua , Liang Han , Sun Yutong , Ma Li
Published: June 2018

Dysregulation of YAP localization and activity is associated with pathological conditions such as cancer. Although activation of the Hippo phosphorylation cascade is known to cause cytoplasmic retention and inactivation of YAP, emerging evidence suggests that YAP can be regulated in a Hippo-independent manner. Here, we report that YAP is subject to non-proteolytic, K63-linked polyubiquitination by the SCFSKP2 E3 ligase complex (SKP2), which is reversed by the deubiquitinase OTUD1. The non-proteolytic ubiquitination of YAP enhances its interaction with its nuclear binding partner TEAD, thereby inducing YAP’s nuclear localization, transcriptional activity, and growth-promoting function. Independently of Hippo signaling, mutation of YAP’s K63-linkage specific ubiquitination sites K321 and K497, depletion of SKP2, or overexpression of OTUD1 retains YAP in the cytoplasm and inhibits its activity. Conversely, overexpression of SKP2 or loss of OTUD1 leads to nuclear localization and activation of YAP. Altogether, our study sheds light on the ubiquitination-mediated, Hippo-independent regulation of YAP.
Map of synthetic rescue interactions for the Fanconi anemia DNA repair pathway identifies USP48
Authors: Velimezi Georgia , Robinson-Garcia Lydia , Muñoz-Martínez Francisco , Wiegant Wouter W. , Ferreira da Silva Joana , Owusu Michel , Moder Martin , Wiedner Marc , Rosenthal Sara Brin , Fisch Kathleen M. , Moffat Jason , Menche Jörg , van Attikum Haico , Jackson Stephen P. , Loizou Joanna I.
Published: June 2018

Defects in DNA repair can cause various genetic diseases with severe pathological phenotypes. Fanconi anemia (FA) is a rare disease characterized by bone marrow failure, developmental abnormalities, and increased cancer risk that is caused by defective repair of DNA interstrand crosslinks (ICLs). Here, we identify the deubiquitylating enzyme USP48 as synthetic viable for FA-gene deficiencies by performing genome-wide loss-of-function screens across a panel of human haploid isogenic FA-defective cells (FANCA, FANCC, FANCG, FANCI, FANCD2). Thus, as compared to FA-defective cells alone, FA-deficient cells additionally lacking USP48 are less sensitive to genotoxic stress induced by ICL agents and display enhanced, BRCA1-dependent, clearance of DNA damage. Consequently, USP48 inactivation reduces chromosomal instability of FA-defective cells. Our results highlight a role for USP48 in controlling DNA repair and suggest it as a potential target that could be therapeutically exploited for FA.
Transport regimes of a split gate superconducting quantum point contact in the two-dimensional LaAlO3/SrTiO3 superfluid
Authors: Thierschmann Holger , Mulazimoglu Emre , Manca Nicola , Goswami Srijit , Klapwijk Teun M. , Caviglia Andrea D.
Published: June 2018

One of the hallmark experiments of quantum transport is the observation of the quantized resistance in a point contact in GaAs/AlGaAs heterostructures. Being formed with split gate technology, these structures represent in an ideal manner equilibrium reservoirs which are connected only through a few electron mode channel. It has been a long standing goal to achieve similar experimental conditions also in superconductors. Here we demonstrate the formation of a superconducting quantum point contact (SQPC) with split gate technology in a two-dimensional superconductor, utilizing the unique gate tunability of the superfluid at the LaAlO3/SrTiO3 interface. When the constriction is tuned through the action of metallic split gates we identify three regimes of transport: First, SQPC for which the supercurrent is carried only by a few quantum transport channels. Second, superconducting island strongly coupled to the equilibrium reservoirs. Third, charge island with a discrete spectrum weakly coupled to the reservoirs.
Postsynaptic RIM1 modulates synaptic function by facilitating membrane delivery of recycling NMDARs in hippocampal neurons
Authors: Wang Jiejie , Lv Xinyou , Wu Yu , Xu Tao , Jiao Mingfei , Yang Risheng , Li Xia , Chen Ming , Yan Yinggang , Chen Changwan , Dong Weifan , Yang Wei , Zhuo Min , Chen Tao , Luo Jianhong , Qiu Shuang
Published: June 2018

NMDA receptors (NMDARs) are crucial for excitatory synaptic transmission and synaptic plasticity. The number and subunit composition of synaptic NMDARs are tightly controlled by neuronal activity and sensory experience, but the molecular mechanism mediating NMDAR trafficking remains poorly understood. Here, we report that RIM1, with a well-established role in presynaptic vesicle release, also localizes postsynaptically in the mouse hippocampus. Postsynaptic RIM1 in hippocampal CA1 region is required for basal NMDAR-, but not AMPA receptor (AMPAR)-, mediated synaptic responses, and contributes to synaptic plasticity and hippocampus-dependent memory. Moreover, RIM1 levels in hippocampal neurons influence both the constitutive and regulated NMDAR trafficking, without affecting constitutive AMPAR trafficking. We further demonstrate that RIM1 binds to Rab11 via its N terminus, and knockdown of RIM1 impairs membrane insertion of Rab11-positive recycling endosomes containing NMDARs. Together, these results identify a RIM1-dependent mechanism critical for modulating synaptic function by facilitating membrane delivery of recycling NMDARs.
Chronic hepatitis C virus infection irreversibly impacts human natural killer cell repertoire diversity
Authors: Strunz Benedikt , Hengst Julia , Deterding Katja , Manns Michael P. , Cornberg Markus , Ljunggren Hans-Gustaf , Wedemeyer Heiner , Björkström Niklas K.
Published: June 2018

Diversity is a central requirement for the immune system’s capacity to adequately clear a variety of different infections. As such, natural killer (NK) cells represent a highly diverse population of innate lymphocytes important in the early response against viruses. Yet, the extent to which a chronic pathogen affects NK cell diversity is largely unknown. Here we study NK cell functional diversification in chronic hepatitis C virus (HCV) infection. High-dimensional flow cytometer assays combined with stochastic neighbor embedding analysis reveal that chronic HCV infection induces functional imprinting on human NK cells that is largely irreversible and persists long after successful interventional clearance of the virus. Furthermore, HCV infection increases inter-individual, but decreases intra-individual, NK cell diversity. Taken together, our results provide insights into how the history of infections affects human NK cell diversity.