bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of the leading Lyapunov vector in a turbulent channel flow
Authors: Nikitin Nikolay 
Published: June 2018

The values of the highest Lyapunov exponent (HLE)$\unicode[STIX]{x1D706}_{1}$for turbulent flow in a plane channel at Reynolds numbers up to$Re_{\unicode[STIX]{x1D70F}}=586$are determined. The instantaneous and statistical properties of the corresponding leading Lyapunov vector (LLV) are investigated. The LLV is calculated by numerical solution of the Navier–Stokes equations linearized about the non-stationary base solution corresponding to the developed turbulent flow. The base turbulent flow is calculated in parallel with the calculation of the evolution of the perturbations. For arbitrary initial conditions, the regime of exponential growth${\sim}\exp (\unicode[STIX]{x1D706}_{1}t)$which corresponds to the approaching of the perturbation to the LLV is achieved already at$t^{+}<50$. It is found that the HLE increases with increasing Reynolds number from$\unicode[STIX]{x1D706}_{1}^{+}\approx 0.021$at$Re_{\unicode[STIX]{x1D70F}}=180$to$\unicode[STIX]{x1D706}_{1}^{+}\approx 0.026$at$Re_{\unicode[STIX]{x1D70F}}=586$. The LLV structures are concentrated mainly in a region of the buffer layer and are manifested in the form of spots of increased fluctuation intensity localized both in time and space. The root-mean-square (r.m.s.) profiles of the velocity and vorticity intensities in the LLV are qualitatively close to the corresponding profiles in the base flow with artificially removed near-wall streaks. The difference is the larger concentration of LLV perturbations in the vicinity of the buffer layer and a relatively larger (by approximately 80 %) amplitude of the vorticity pulsations. Based on the energy spectra of velocity and vorticity pulsations, the integral spatial scales of the LLV structures are determined. It is found that LLV structures are on average twice narrower and twice shorter than the corresponding structures of the base flow. The contribution of each of the terms entering into the expression for the production of the perturbation kinetic energy is determined. It is shown that the process of perturbation development is essentially dictated by the inhomogeneity of the base flow, as well as by the presence of transversal motion in it. Neglecting of these factors leads to a significant underestimation of the perturbation growth rate. The presence of near-wall streaks in the base flow, on the contrary, does not play a significant role in the development of the LLV perturbations. Artificial removal of streaks from the base flow does not change the character of the perturbation growth.
The strophomenide brachiopodAhtiellaÖpik in the Ordovician of Gondwana and the early history of the plectambonitoids
Authors: Benedetto Juan L. 
Published: June 2018

AbstractThe Precordilleran speciesAhtiella argentinaBenedetto and Herrera, 1986 is redescribed and illustrated andMonorthis coloradoensisBenedetto, 1998b from northwestern Argentina is reassigned to the genusAhtiellaÖpik, 1932.Ahtiella famatiniananew species from volcaniclastic rocks of the Famatina range (western Argentina) andAhtiella tunaensisnew species from the Precordillera basin (Cuyania terrane) are proposed. Paleogeographic and stratigraphic evidence strongly suggests thatAhtiellaoriginated in the Andean region of Gondwana to further migrate to Avalonia, Baltica, and Cuyania. Contrary to previous assumptions, the fossil record from the Famatina volcaniclastic succession suggests that the plectambonitoidAhtiella famatinianan. sp. evolved from the hesperonomiid orthoidMonorthis transversaBenedetto, 2003 that always occurs in the underlying strata. Phylogenetic analysis ofAhtiellaspecies shows thatA. famatinianan. sp. and the PeruvianA. zarelaeVillas in Gutiérrez-Marco and Villas, 2007 are not only the earliest species of the genus but also are morphologically intermediate betweenMonorthisBates, 1968 and the later and more derived species ofAhtiellafrom Baltica and Cuyania. If, as empirical evidence presented here shows,Ahtiellaoriginated fromMonorthisthrough a series of minor transformations, then the impressive morphological gap between orthides and strophomenides was bridged through short-time cladogenesis events, suggesting that it might not have a definite discontinuity between the species level evolution and the origin of higher taxa (macroevolution).UUID:http://zoobank.org/4b8c5442-ea2c-41b2-97f7-4c0a8b0384a2
Production and quality benefits of white clover inclusion into ryegrass swards at different nitrogen fertilizer rates
Authors: Enriquez-Hidalgo D. , Gilliland T. J. , Egan M. , Hennessy D. 
Published: June 2018

AbstractA 4-year (2010–2013) plot study was undertaken to evaluate the effect of nitrogen (N) fertilizer rate (0, 60, 120, 196 and 240 kg N/ha/year) on seasonal responses and species persistency in frequently and tightly grazed (⩽4 cm) grass-only (GO) and grass white clover swards (GWc). Increasing N application rate increased herbage removed and pre-grazing sward height. Cows frequently grazed the GWc tighter than the GO. Increasing N rate reduced clover content, especially during the warmest months of the year, but less so up to 120 kg N/ha/year. The GWc had greater amounts of herbage removed than GO in the May–September period but the effect was less as N rate increased. Cumulative herbage removed from GWc was greater than GO swards receiving the same N rate and herbage quality was better in GWc than GO. Such effects were reduced as swards aged and with increasing N rate. It was concluded that under frequent and tight grazing management: (1) clover inclusion increased annual herbage removed; (2) herbage removed from GWc swards receiving no N was the same as the GO sward receiving 240 kg N/ha, and greater for the 240 GWc swards than the 240 GO swards; (3) clover inclusion benefits were mainly from summer onwards; (4) the management strategy applied in the current experiment may be capable of alleviating the detrimental effect of N fertilizer on clover, to a point between 60 and 120 kg N/ha.
A process for assessing and prioritizing species conservation needs: going beyond the Red List
Authors: Johnson Kevin , Baker Anne , Buley Kevin , Carrillo Luis , Gibson Richard , Gillespie Graeme R. , Lacy Robert C. , Zippel Kevin 
Published: June 2018

AbstractConservation resources are limited, yet an increasing number of species are under threat. Assessing species for their conservation needs is, therefore, a vital first step in identifying and prioritizing species for both ex situ and in situ conservation actions. Using a transparent, logical and objective method, the Conservation Needs Assessment process developed by Amphibian Ark uses current knowledge of species in the wild to determine those with the most pressing conservation needs, and provides a foundation for the development of holistic conservation action plans that combine in situ and ex situ actions as appropriate. These assessments allow us to maximize the impact of limited conservation resources by identifying which measures could best serve those species requiring help. The Conservation Needs Assessment complements the IUCN Red List assessment, and together they provide a more holistic guide to conservation priorities and actions. Conservation Needs Assessments generate national prioritized lists of species recommended for conservation action. These can subsequently be used to assist in the development of species recovery plans and national action plans, or to inform national conservation priorities better. Additional tools that will evaluate the recommendations for ex situ rescues, to determine the best candidates for conservation breeding programmes, are currently under development.
L2 DEVELOPMENT OF PERCEPTUAL CATEGORIZATION OF DIALECTAL SOUNDS
Authors: Schmidt Lauren B. 
Published: June 2018

AbstractThe present study examined second language (L2) development in the perceptual identification of a dialectal sound of the target language, through an investigation of the role of individual learner experiences in L2 phonological development. A total of 213 English-speaking learners of Spanish across five levels of study and with varying dialect contact experiences completed an identification task, which tested perceptual categorization of Spanish dialectal aspirated-s (e.g.,siesta[ˈsi̯eh-ta]). In accordance with postulates of L2 speech perception models (PAM-L2, SLM, L2LP), findings revealed influence of the first language phonology on categorization at early levels shifting toward nativelike, dialect-specific categorizations of aspirated-s for more experienced learners. Dialect contact factors of prior study abroad location, native speaker social contacts, and metalinguistic training were found to be predictors of the dialectal perceptual targets toward which the L2 learners developed—for those learners past intermediate-level language courses—highlighting how individual experiences shape L2 perceptual abilities.
Institutional complementarities between labour laws and innovation
Authors: BELLOC FILIPPO 
Published: June 2018

AbstractWe analyse how institutional complementarities between employee representation laws and dismissal restrictions influence aggregate innovation outcomes. We argue that greater employee voice, due to improved employee representation legislations, may spur innovative effort by employees only when shareholders cannot renegotiate ex-ante agreements with workers over revenue sharing, by threatening dismissal. We perform a panel regression analysis, exploiting country-sector panel data over the 1977–2005 period, and find that stronger employee representation laws in the presence of stricter firing restrictions are in fact associated with higher patenting activity. Consistently with our theoretical argument, the magnitude of this empirical relationship is seen to be relatively larger in those sectors where the human capital contribution to production is higher. Implications for the analysis of economic institutions and for legal policy making are proposed.
CPW slot antenna with Y-shaped central monopole and matching arms
Authors: Inserra Daniele , Fang Xiaochuan , Huang Yongjun , Wen Guangjun 
Published: June 2018

AbstractA coplanar waveguide slot antenna is herein presented. A rectangular slot is excited by a Y-shaped monopole etched on a single FR4 substrate. This structure exhibits two resonances due to the presence of the slot and the central monopole which can be used to design a dual-band or a wideband antenna. A parametric analysis is presented to describe the impedance matching mechanism for the two impedance bandwidths (BWs), as well as for the wideband antenna. The latter is fabricated and provides a measured impedance BW from 2.28 to 3.6 GHz, and gain larger than 2 dBi, yielding an outstanding BW/size trade-off. Finally, a 60 mm × 60 mm back metallic reflector is used to achieve a directive antenna with 6 dBi of measured gain, and an impedance BW from 2.16 to 3.59 GHz.
Influence of Plant Growth Stage and Temperature on Glyphosate Efficacy in Common Lambsquarters (Chenopodium album)
Authors: DeGreeff Randy D. , Varanasi Aruna V. , Dille J. Anita , Peterson Dallas E. , Jugulam Mithila 
Published: June 2018

AbstractPlant growth stage and temperature influence the activity of glyphosate on common lambsquarters. A biotype of common lambsquarters in Dickinson County, KS (DK) was not controlled upon treatment with glyphosate in the field. In a greenhouse dose–response study, the DK biotype expressed 1.5-fold less sensitivity to glyphosate compared to a known susceptible biotype from Riley County, KS (RL). Common lambsquarters plants were treated at different growth stages (5 to 7, 10 to 12, 15 to 17, or 19 to 21 cm tall) with glyphosate at a field rate (840 g ae ha–1), and, regardless of the biotype, plants were more susceptible to glyphosate when they were 5 to 7 cm tall. Common lambsquarters plants were treated with glyphosate (840 g ae ha–1) after growing at different temperatures (25/15, 32.5/22.5, or 40/30 C day/night), and regardless of the biotype, plants were more susceptible to glyphosate when grown at 25/15 C. The results suggest that the DK biotype exhibits reduced sensitivity to glyphosate compared to the RL biotype, and glyphosate applied at field rate would be more effective on smaller common lambsquarters plants and at cooler temperatures. Common lambsquarters seedlings tend to emerge when temperatures are cooler, early in the spring relative to other summer annual weeds. Therefore, plants should be identified and treated earlier in the growing season for best efficacy with glyphosate.
Spatiotemporal Features of Intraseasonal Oceanic Variability in the Philippine Sea From Mooring Observations and Numerical Simulations
Authors: Hu Shijian , Sprintall Janet , Guan Cong , Sun Bowen , Wang Fan , Yang Guang , Jia Fan , Wang Jianing , Hu Dunxin , Chai Fei 
Published: June 2018

AbstractThe Philippine Sea is located within the pathway of the propagating Madden‐Julian Oscillation system and is also the destination for the North Pacific mesoscale oceanic eddies and waves. As such, the Philippine Sea is characterized by striking intraseasonal variability (ISV; 20–90 days) that plays a key role in bridging weather and climate. Spatial patterns and temporal features of intraseasonal oceanic variability along the Philippine coast are investigated using mooring observations and outputs from an eddy‐resolving general circulation model. The amplitude of ISV determined from sea level anomaly is found to decrease from the northern and coastal Philippine Sea to the south and interior Pacific Ocean. In contrast, eddy kinetic energy features a northward decreasing gradient with a maximum at about 6°N. The meridional distribution of sea level anomaly and eddy kinetic energy spectra indicates that the ISV period increases with latitude and is symmetrical about the equator. Mesoscale eddies in the upper layer are tracked to explore the statistical distribution. Westward propagating mesoscale eddies and intraseasonal Rossby waves related to dynamic instabilities are an important source of the oceanic ISV in the Philippine Sea. Clear coastal propagation of ISVs related to coastal Kelvin waves is detected the south of about 14°N. Composite analysis shows that the Madden‐Julian Oscillation is another important forcing shaping the spatial features of Philippine ISV intensity and contributes close to half of the observed total ISV.
Evaluation and Intercomparison of Five North American Dry Deposition Algorithms at a Mixed Forest Site
Authors: Wu Zhiyong , Schwede Donna B. , Vet Robert , Walker John T. , Shaw Mike , Staebler Ralf , Zhang Leiming 
Published: June 2018

AbstractTo quantify differences between dry deposition algorithms commonly used in North America, five models were selected to calculate dry deposition velocity (Vd) for O3 and SO2 over a temperate mixed forest in southern Ontario, Canada, where a 5‐year flux database had previously been developed. The models performed better in summer than in winter with correlation coefficients for hourly Vd between models and measurements being approximately 0.6 and 0.3, respectively. Differences in mean Vd values between models were on the order of a factor of 2 in both summer and winter. All models produced lower Vd values than the measurements of O3 in summer and SO2 in summer and winter, although the measured Vd may be biased. There was not a consistent tendency in the models to overpredict or underpredict for O3 in winter. Several models produced magnitudes of the diel variation of Vd (O3) comparable to the measurements, while all models produced slightly smaller diel variations than the measurements of Vd (SO2) in summer. A few models produced larger diel variations than the measurements of Vd for O3 and SO2 in winter. Model differences were mainly due to different surface resistance parameterizations for stomatal and nonstomatal uptake pathways, while differences in aerodynamic and quasi‐laminar resistances played only a minor role. It is recommended to use ensemble modeling results for ecosystem impact assessment studies, which provides mean values of all the used models and thus can avoid too much overestimations or underestimations.
Evidence Connecting Mercury's Magnesium Exosphere to Its Magnesium‐Rich Surface Terrane
Authors: Merkel Aimee W. , Vervack Ronald J. , Killen Rosemary M. , Cassidy Timothy A. , McClintock William E. , Nittler Larry R. , Burger Matthew H. 
Published: June 2018

AbstractMercury is surrounded by a tenuous, collisionless exosphere where the surface of the planet is directly exposed to the space environment. As a consequence, impacts and space weathering processes are expected to eject atoms and molecules from the surface into the exosphere, implying a direct link between the exospheric composition and the planet's regolith material. However, observational evidence demonstrating this link has been elusive. Here we report that exospheric magnesium, a species recently discovered and systematically measured by the Mercury Surface, Space ENvironment, GEochemistry, and Ranging mission, is enhanced when observed over a portion of the planet's surface regolith rich in magnesium. These observations confirm a direct link between Mercury's magnesium exosphere and the underlying crustal surface composition, providing strong evidence supporting theoretical arguments that impact vaporization can directly supply material to the exosphere from the regolith of a rocky, airless body.
Response of Mesospheric HO2and O3to Large Solar Proton Events
Authors: Zou Zicheng , Xue Xianghui , Shen Chenglong , Yi Wen , Wu Jianfei , Chen Tingdi , Dou Xiankang 
Published: June 2018

AbstractA lot of solar proton events (SPEs) have happened during the ongoing solar cycle 24 including extremely large events. Seven large SPEs from 2012 to 2017 were chosen to find the response of polar atmosphere to them. Three SPEs happened in 2012, and the other four SPEs happened in 2013, 2014, 2015, and 2017, respectively. The National Oceanic and Atmospheric Administration Geostationary Operational Environmental Satellites 13 proton observations were used to illustrate the proton flux toward the Earth during each SPE. These energetic protons are deposited in the middle and upper atmosphere and ionize the neutral atmosphere constituents and create radicals HOx(H, OH, and HO2). Enhancements in the upper atmospheric hydroperoxyl radical (HO2) of both polar regions of over 1 ppbv are found in the Aura Microwave Limb Sounder measurements immediately after some SPEs happened. The Microwave Limb Sounder observations of ozone (O3) show decreases of >10% in both polar middle and upper atmosphere for a few days with a peak value of >20–60% over 1–3 days. The compositions of HO2and ozone for all the selected SPEs indicate that the polar ozone depletions during the SPEs in a way are the result of the HO2enhancements.
South Atlantic Subtropical Gyre Late Twentieth Century Changes
Authors: Marcello Fernanda , Wainer Ilana , Rodrigues Regina R. 
Published: June 2018

AbstractThis study builds upon existing research suggesting recent changes in the circulation of global subtropical gyres with respect to the South Atlantic Ocean using simulation results from the ocean component of the Community Earth System Model version 1—the Parallel Ocean Program version 2. The results point to an intensification of the total anticyclonic circulation of the subtropical gyre and a southward displacement of the system, as revealed by the wind stress curl, sea surface height, and barotropic stream function fields. Increased values of these variables were found within the dynamical limits of the South Atlantic Subtropical Gyre (SASG), while their basin‐scale structure seemed to be concurrently drifting poleward. The southern branch of the South Equatorial Current (sSEC) marks the northern boundary of the SASG. When reaching the South American coast, it bifurcates into the North Brazil Undercurrent to the north and the Brazil Current to the south. The sSEC bifurcation latitude (SBL) dictates the partition between the waters flowing poleward to recirculate within the SASG and those flowing toward the equatorial region and the Northern Hemisphere. A southward migration of the SBL at a rate of −0.11°± 0.03°/year was observed, associated with a substantial increase in the equatorward advection of waters within the sSEC‐SBL‐North Brazil Undercurrent system.
Drivers of Interannual Variability of Summer Mixed Layer Depth in the Southern Ocean Between 2002 and 2011
Authors: Panassa E. , Völker C. , Wolf‐Gladrow D. , Hauck J. 
Published: June 2018

AbstractClimate change projections indicate that there will be warming and an intensification of westerly winds in the Southern Ocean (SO) in the future. These two forcings potentially have opposing effects on the depth of the surface mixed layer. Here we investigate how interannual to decadal variability of atmospheric surface air temperature (SAT) and zonal wind speed (uwind) impact mixed layer depth (MLD) in the SO (south of 30°S) during summer, the season of main biological activity. We use gridded MLD data from observations and atmospheric reanalysis data of uwind and SAT in the SO to assess summer MLD variability and its potential drivers. With a model‐based sensitivity experiment, we quantify the relative contributions of uwind versus SAT forcing on the summer MLD in the decade 2002–2011. Wind‐induced changes dominate over temperature‐induced changes of the MLD between 2002 and 2011. We find a positive trend of summer MLD in the Antarctic Zone of the Atlantic and Indian Ocean sectors. Our model‐based sensitivity study suggests that the summer MLD shows a zonally asymmetric response to recent atmospheric forcing. In the Pacific and Australian sectors, cooling and intensification of uwind jointly result in a deepening of the mixed layer. In the Atlantic and Indian sectors, the MLD responds differently north and south of the Antarctic Polar Front (APF). A deepening south of the APF is caused by the increase in uwind, whereas the decrease in uwind and warming act in concert to result in a shoaling of the MLD north of the APF.
Temporal Variability in Surface Water pCO2 in Adventfjorden (West Spitsbergen) With Emphasis on Physical and Biogeochemical Drivers
Authors: Ericson Y. , Falck E. , Chierici M. , Fransson A. , Kristiansen S. , Platt S. M. , Hermansen O. , Myhre C. L. 
Published: June 2018

AbstractSeasonal and interannual variability in surface water partial pressure of CO2 (pCO2) and air‐sea CO2 fluxes from a West Spitsbergen fjord (IsA Station, Adventfjorden) are presented, and the associated driving forces are evaluated. Marine CO2 system data together with temperature, salinity, and nutrients, were collected at the IsA Station between March 2015 and June 2017. The surface waters were undersaturated in pCO2 with respect to atmospheric pCO2 all year round. The effects of biological activity (primary production/respiration) followed by thermal forcing on pCO2 were the most important drivers on a seasonal scale. The ocean was a sink for atmospheric CO2 with annual air‐sea CO2 fluxes of −36 ± 2 and −31 ± 2 g C·m−2·year−1 for 2015–2016 and 2016–2017, respectively, as estimated from the month of April. Waters of an Arctic origin dominated in 2015 and were replaced in 2016 by waters of a transformed Atlantic source. The CO2 uptake rates over the period of Arctic origin waters were significantly higher (2 mmol C·m−2·day−1) than the rates of the Atlantic origin waters of the following year.