bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zonally Elongated Transient Flows: Phenomenology and Sensitivity Analysis
Authors: Rudko M. V. , Kamenkovich I. V. , Iskadarani M. , Mariano A. J. 
Published: April 2018

AbstractThis study explores the phenomenology of zonally elongated transients (ZELTs) in the ocean and the sensitivity of their properties to changes in several environmental factors. ZELTs explain a major part of anisotropy in mesoscale turbulent flow. Calculations are performed in a two‐layer, quasi‐geostrophic model. Empirical Orthogonal Functions (EOF) decomposition allows for the separation of ZELTs from the background turbulent flow as several leading EOF modes. The leading Extended EOF reveals that ZELTs propagate westward at the speed of
cm s−1. The decrease in the planetary vorticity gradient and increase in the bottom drag coefficient each leads to flattening of the variance spectrum, isotropization of the leading EOF, and fast decay of the autocorrelation function of its corresponding Principal Component.
Estimating Oxygen in the Southern Ocean Using Argo Temperature and Salinity
Authors: Giglio D. , Lyubchich V. , Mazloff M. R. 
Published: April 2018

AbstractAn Argo‐based estimate of oxygen (O2) at 150 m is presented for the Southern Ocean (SO) from temperature (T), salinity (S), and O2 Argo profiles collected during 2008–2012. The method is based on a supervised machine learning algorithm known as random forest (RF) regression and provides an estimate for O2 given T, S, location, and time information. The method is validated by attempting to reproduce the Southern Ocean State Estimate (SOSE) O2 field using synthetic data sampled from SOSE. The RF mapping shows skill in the majority of the domain but is problematic in some of the boundary regions. Maps of O2 at 150 m derived from observed profiles suggest that SOSE and the World Ocean Atlas 2013 climatology may overestimate annual mean O2 in the SO, both on a global and basin scale. A large regional bias is found east of Argentina, where high O2 values in the Argo‐based estimate are confined closer to the coast compared to other products. SOSE may also underestimate the annual cycle of O2. Evaluation of the RF‐based method demonstrates its potential to improve understanding of O2 annual mean fields and variability from sparse O2 measurements. This implies the algorithm will also be effective for mapping other biogeochemical variables (e.g., nutrients and carbon). Furthermore, our RF evaluation results can be used to inform the design of future enhancements to the current array of O2 profiling floats.
Light Availability and Phytoplankton Growth Beneath Arctic Sea Ice: Integrating Observations and Modeling
Authors: Hill Victoria J. , Light Bonnie , Steele Michael , Zimmerman Richard C. 
Published: April 2018

AbstractObservations of the seasonal light field in the upper Arctic Ocean are critical to understanding the impacts of changing Arctic ice conditions on phytoplankton growth in the water column. Here we discuss data from a new sensor system, deployed in seasonal ice cover north‐east of Utqiaġvik, Alaska in March 2014. The system was designed to provide observations of light and phytoplankton biomass in the water column during the formation of surface melt ponds and the transition from ice to open water. Hourly observations of downwelling irradiance beneath the ice (at 2.9, 6.9, and 17.9 m depths) and phytoplankton biomass (at 2.9 m depth) were transmitted via Iridium satellite from 9 March to 10 November 2014. Evidence of an under‐ice phytoplankton bloom (Chl a ∼8 mg m−3) was seen in June and July. Increases in light intensity observed by the buoy likely resulted from the loss of snow cover and development of surface melt ponds. A bio‐optical model of phytoplankton production supported this probable trigger for the rapid onset of under‐ice phytoplankton growth. Once under‐ice light was no longer a limiting factor for photosynthesis, open water exposure almost marginally increased daily phytoplankton production compared to populations that remained under the adjacent ice. As strong effects of climate change continue to be documented in the Arctic, the insight derived from autonomous buoys will play an increasing role in understanding the dynamics of primary productivity where ice and cloud cover limit the utility of ocean color satellite observations.
Observations of Kelvin‐Helmholtz Waves in the Earth's Magnetotail Near the Lunar Orbit
Authors: Ling Yiming , Shi Quanqi , Shen Xiao‐Chen , Tian Anmin , Li Wenya , Tang Binbin , Degeling A. W. , Hasegawa Hiroshi , Nowada Motoharu , Zhang Hui , Rae I. J. , Zong Qiu‐Gang , Fu Suiyan , Fazakerley A. N. , Pu Zuyin 
Published: April 2018

AbstractKelvin‐Helmholtz waves (KHWs), which have been widely observed at the magnetopause in the region near the Earth, play an essential role in the transport of solar wind plasma and energy into the magnetosphere under dominantly northward interplanetary magnetic field (IMF) conditions. In this study, we present simultaneous observations of KHWs under the northward IMF observed by both the Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) spacecraft in the Earth's magnetotail around the lunar orbit (at X ~ −50RE, Y ~ 30RE, dusk side) and the Geotail in the near‐Earth space (at X ~ −5RE, Y ~ −10RE, dawn side). The KHWs are quantitatively characterized by their dominant period, phase velocity, and wavelength, utilizing wavelet analysis and an approximation of their center‐of‐mass velocity. Our results suggest that the phase velocity and spatial scale of KHWs may increase as they propagate along the boundary layer toward the tail. Alternatively, the differences between the ARTEMIS and Geotail observations may indicate the possibility of dawn‐dusk asymmetry in the excited KHWs in this study. Our results strongly evidence the existence of the development of KHWs in terms of their wave frequency and scale size in the magnetotail and provide insight to the time evolution of KHWs along the magnetopause.
Spatial Distribution of Io's Neutral Oxygen Cloud Observed by Hisaki
Authors: Koga Ryoichi , Tsuchiya Fuminori , Kagitani Masato , Sakanoi Takeshi , Yoneda Mizuki , Yoshioka Kazuo , Yoshikawa Ichiro , Kimura Tomoki , Murakami Go , Yamazaki Atsushi , Smith H. Todd , Bagenal Fran 
Published: April 2018

AbstractWe report on the spatial distribution of a neutral oxygen cloud surrounding Jupiter's moon Io and along Io's orbit observed by the Hisaki satellite. Atomic oxygen and sulfur in Io's atmosphere escape from the exosphere mainly through atmospheric sputtering. Some of the neutral atoms escape from Io's gravitational sphere and form neutral clouds around Jupiter. The extreme ultraviolet spectrograph called EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) installed on the Japan Aerospace Exploration Agency's Hisaki satellite observed the Io plasma torus continuously in 2014–2015, and we derived the spatial distribution of atomic oxygen emissions at 130.4 nm. The results show that Io's oxygen cloud is composed of two regions, namely, a dense region near Io and a diffuse region with a longitudinally homogeneous distribution along Io's orbit. The dense region mainly extends on the leading side of Io and inside of Io's orbit. The emissions spread out to 7.6 Jupiter radii (RJ). Based on Hisaki observations, we estimated the radial distribution of the atomic oxygen number density and oxygen ion source rate. The peak atomic oxygen number density is 80 cm−3, which is spread 1.2 RJ in the north‐south direction. We found more oxygen atoms inside Io's orbit than a previous study. We estimated the total oxygen ion source rate to be 410 kg/s, which is consistent with the value derived from a previous study that used a physical chemistry model based on Hisaki observations of ultraviolet emission ions in the Io plasma torus.
Flutter to tumble transition of buoyant spheres triggered by rotational inertia changes
Authors: Mathai Varghese , Zhu Xiaojue , Sun Chao , Lohse Detlef 
Published: April 2018

AbstractHeavy particles sink straight in water, while buoyant bubbles and spheres may zigzag or spiral as they rise. The precise conditions that trigger such path-instabilities are still not completely understood. For a buoyant rising sphere, two parameters are believed to govern the development of unsteady dynamics: the particle’s density relative to the fluid, and its Galileo number. Consequently, with these parameters specified, the opportunities for variation in particle dynamics appear limited. In contrast to this picture, here we demonstrate that vigorous path-oscillations can be triggered by modulating a spherical particle’s moment of inertia (MoI). For a buoyant sphere rising in a turbulent flow, MoI reduction triggers a tumble–flutter transition, while in quiescent liquid, it induces a modification of the sphere wake resulting in large-amplitude path-oscillations. The present finding opens the door for control of particle path- and wake-instabilities, with potential for enhanced mixing and heat transfer in particle-laden and dispersed multiphase environments.
PKC Dependent p14ARF Phosphorylation on Threonine 8 Drives Cell Proliferation
Authors: Fontana Rosa , Guidone Daniela , Sangermano Felicia , Calabrò Viola , Pollice Alessandra , La Mantia Girolama , Vivo Maria 
Published: April 2018

AbstractARF role as tumor suppressor has been challenged in the last years by several findings of different groups ultimately showing that its functions can be strictly context dependent. We previously showed that ARF loss in HeLa cells induces spreading defects, evident as rounded morphology of depleted cells, accompanied by a decrease of phosphorylated Focal Adhesion Kinase (FAK) protein levels and anoikis. These data, together with previous finding that a PKC dependent signalling pathway can lead to ARF stabilization, led us to the hypothesis that ARF functions in cell proliferation might be regulated by phosphorylation. In line with this, we show here that upon spreading ARF is induced through PKC activation. A constitutive-phosphorylated ARF mutant on the conserved threonine 8 (T8D) is able to mediate both cell spreading and FAK activation. Finally, ARF-T8D expression confers growth advantage to cells thus leading to the intriguing hypothesis that ARF phosphorylation could be a mechanism through which pro-proliferative or anti proliferative signals could be transduced inside the cells in both physiological and pathological conditions.
Tunneling explains efficient electron transport via protein junctions
Authors: Fereiro Jerry A. , Yu Xi , Pecht Israel , Sheves Mordechai , Cuevas Juan Carlos , Cahen David 
Published: April 2018

Significance
Investigation of the charge transport mechanism across a monolayer of a redox active protein is important for the fundamental understanding of the naturally occurring electron transfer processes, such as those in photosynthesis or respiration. Inelastic electron tunneling spectroscopy measurements of a redox active protein may provide direct experimental evidence that the tunneling charges are, in fact, passing through the protein molecules. Results of our study of conductance via well-controlled azurin monolayer solid-state junctions show the direct involvement of the Cu(II) site in assisting electron transport, underscoring this site’s vibronic characteristics associated with the charge transport mechanism. Our study widens the scope of currently available methodologies and also adds to the potential of using proteins in bioelectronics.
Symbiont switching and alternative resource acquisition strategies drive mutualism breakdown
Authors: Werner Gijsbert D. A. , Cornelissen Johannes H. C. , Cornwell William K. , Soudzilovskaia Nadejda A. , Kattge Jens , West Stuart A. , Kiers E. Toby 
Published: April 2018

Significance
Cooperative interactions among species—mutualisms—are major sources of evolutionary innovation. However, despite their importance, two species that formerly cooperated sometimes cease their partnership. Why do mutualisms break down? We asked this question in the partnership between arbuscular mycorrhizal (AM) fungi and their plant hosts, one of the most ancient mutualisms. We analyze two potential trajectories toward evolutionary breakdown of their cooperation, symbiont switching and mutualism abandonment. We find evidence that plants stop interacting with AM fungi when they switch to other microbial mutualists or when they evolve alternative strategies to extract nutrients from the environment. Our results show vital cooperative interactions can be lost, but only if successful alternatives evolve.
Structural homo- and heterosynaptic plasticity in mature and adult newborn rat hippocampal granule cells
Authors: Jungenitz Tassilo , Beining Marcel , Radic Tijana , Deller Thomas , Cuntz Hermann , Jedlicka Peter , Schwarzacher Stephan W. 
Published: April 2018

Significance
The lifelong genesis of hippocampal granule cells (abGCs) enables specific forms of spatial learning. We analyzed which forms of synaptic plasticity are present in abGCs in comparison with mature granule cells (mGCs). We found structural equivalents of homosynaptic long-term potentiation and heterosynaptic long-term depression, two fundamental forms of cellular learning. abGCs and mGCs showed spine enlargement on stimulated segments and spine shrinkage on nonstimulated segments concurrently present on dendrites of individual cells, indicating a sharpening and a homeostatic regulation of synaptic efficacy. abGCs expressed homo- and heterosynaptic spine plasticity with a clear onset between 4–5 wk of cell age, demonstrating increasing synaptic plasticity during the phase of abGC integration on the structural level.
High-order fractal states in graphene superlattices
Authors: Krishna Kumar R. , Mishchenko A. , Chen X. , Pezzini S. , Auton G. H. , Ponomarenko L. A. , Zeitler U. , Eaves L. , Fal’ko V. I. , Geim A. K. 
Published: April 2018

Significance
Electronic spectra of crystals in ultrahigh magnetic fields are expected to be fractal as symbolized by the theoretical plots called Hofstadter butterflies. Despite decades-long interest, their origin is often misconstrued. In fact, the fractal spectra can be understood as recurrence of delocalized Bloch states that appear each time the magnetic length becomes commensurate with the lattice periodicity. In this case, new quasiparticles emerge, moving through the crystal as if no magnetic field is applied. Their Landau quantization in noncommensurate fields generates the whole intricacy of Hofstadter spectra. Here, we study electron transport in graphene superlattices and report numerous self-similar features in their conductivity. This is a direct observation of the complete fractal pattern that underpins Hofstadter butterflies.
Quasi–Monte Carlo integration with product weights for elliptic PDEs with log-normal coefficients
Authors: Kazashi Yoshihito 
Published: April 2018

Abstract
Quasi–Monte Carlo (QMC) integration of output functionals of solutions of the diffusion problem with a log-normal random coefficient is considered. The random coefficient is assumed to be given by an exponential of a Gaussian random field that is represented by a series expansion of some system of functions. Graham et al. (2015, Quasi-Monte Carlo finite element methods for elliptic PDEs with lognormal random coefficients. Numer. Math., 131, 329–368) developed a lattice-based QMC theory for this problem and established a quadrature error decay rate ≈ 1 with respect to the number of quadrature points. The key assumption there was a suitable summability condition on the aforementioned system of functions. As a consequence, product-order-dependent weights were used to construct the lattice rule. In this paper, a different assumption on the system is considered. This assumption, originally considered by Bachmayr et al. (2017c, Sparse polynomial approximation of parametric elliptic PDEs. Part I: affine coefficients. ESAIM Math. Model. Numer. Anal., 51, 321–339) to utilise the locality of support of basis functions in the context of polynomial approximations applied to the same type of the diffusion problem, is shown to work well in the same lattice-based QMC method considered by Graham et al.: the assumption leads us to product weights, which enables the construction of the QMC method with a smaller computational cost than Graham et al. A quadrature error decay rate ≈ 1 is established, and the theory developed here is applied to a wavelet stochastic model. By a characterisation of the Besov smoothness, it is shown that a wide class of path smoothness can be treated with this framework.
Identification and period investigation of pulsation variable star UY Camelopardalis, an RR Lyrae star in binary system
Authors: Li Lin-Jia , Qian Sheng-Bang , Voloshina Irina , Metlov Vladimir G , Zhu Li-Ying , Liao Wen-Ping 
Published: April 2018

Abstract
We present photometric measurements of the short period variable star UY Cam, which has been classified as a δ Scuti or c-type RR Lyrae (RRc) variable in different catalogs. Based on the analyses on Fourier coefficients and (NUV − V)0, we find that UY Cam is probably an RRc star. We obtain 58 new times of light maximum for UY Cam based on several sky surveys and our observations. Combining these with the times of light maximum in literature, a total of 154 times of light maximum are used to analyze the O − C diagram of UY Cam. The results show that the O − C pattern can be described by a downward parabolic component with a rate of −6.86 ± 0.47 × 10−11 d d−1, and a cyclic variation with a period of 65.7 ± 2.4 yr. We suppose these components are caused by the stellar evolution and the light travel time effect (LiTE) of a companion in elliptical orbit, respectively. By calculation, the minimum mass of the potential companion is about 0.17 M⊙, and its mass should be less than or equal to the pulsation primary star when the inclination $i &gt; {22{^{\circ}_{.}}5}$. Therefore, the companion should be a low-mass star, like a late-type main-sequence star or a white dwarf. Due to the unique property of UY Cam, we suggest that more observations and studies on UY Cam and other RRc stars are needed to check the nature of these stars, including the pulsations and binarities.
Genomic, Proteomic and Phenotypic Heterogeneity in HeLa Cells across Laboratories: Implications for Reproducibility of Research Results
Authors: Liu Yansheng , Mi Yang , Mueller Torsten , Kreibich Saskia , Williams Evan G. , Van Drogen Audrey , Borel Christelle , Germain Pierre-Luc , Frank Max , Bludau Isabell , Mehnert Martin , Seifert Michael , Emmenlauer Mario , Sorg Isabel , Bezrukov Fedor , Sloan Bena Frederique , Zhou Hu , Dehio Christoph , Testa Giuseppe , Saez-Rodriguez Julio , Antonarakis Stylianos E. , Hardt Wolf-Dietrich , Aebersold Ruedi 
Published: April 2018

AbstractThe independent reproduction of research results is a cornerstone of experimental research, yet it is beset by numerous challenges, including the quality and veracity of reagents and materials. Much of life science research depends on life materials, including human tissue culture cells. In this study we aimed at determining the degree of variability in the molecular makeup and the ensuing phenotypic consequences in commonly used human tissue culture cells. We collected 14 stock HeLa aliquots from 13 different laboratories across the globe, cultured them in uniform conditions and profiled the genome-wide copy numbers, mRNAs, proteins and protein turnover rates via genomic techniques and SWATH mass spectrometry, respectively. We also phenotyped each cell line with respect to the ability of transfected Let7 mimics to modulate Salmonella infection.We discovered significant heterogeneity between HeLa variants, especially between lines of the CCL2 and Kyoto variety. We also observed progressive divergence within a specific cell line over 50 successive passages. From the aggregate multi-omic datasets we quantified the response of the cells to genomic variability across the transcriptome and proteome. We discovered organelle-specific proteome remodeling and buffering of protein abundance by protein complex stoichiometry, mediated by the adaptation of protein turnover rates. By associating quantitative proteotype and phenotype measurements we identified protein patterns that explained the varying response of the different cell lines to Salmonella infection.Altogether the results indicate a striking degree of genomic variability, the rapid evolution of genomic variability in culture and its complex translation into distinctive expressed molecular and phenotypic patterns. The results have broad implications for the interpretation and reproducibility of research results obtained from HeLa cells and provide important basis for a general discussion of the value and requirements for communicating research results obtained from human tissue culture cells.
A cell separation checkpoint that enforces the proper order of late cytokinetic events
Authors: Brace Jennifer L. , Doerfler Matthew D. , Weiss Eric L. 
Published: April 2018

SummaryEukaryotic cell division requires sequence dependency relationships in which late processes commence only after early ones are appropriately completed. We have discovered a system that blocks late events of cytokinesis until early ones are successfully accomplished. In budding yeast, cytokinetic actomyosin ring contraction and membrane ingression are coupled with deposition of an extracellular septum that is destroyed immediately after its completion by secreted enzymes. We find this secretion event is linked to septum completion and forestalled when the process is slowed. Delay of septum destruction requires Fir1, an intrinsically disordered protein localized to the cytokinesis site that is degraded upon septum completion but stabilized when septation is aberrant. Fir1 appears to protect cytokinesis in part by inhibiting a separation-specific exocytosis function of the NDR/LATS kinase Cbk1, a key component of a “hippo” signaling pathway that induces mother-daughter separation. We term this system “enforcement of cytokinesis order” (ECO), a checkpoint ensuring proper temporal sequence of mechanistically incompatible processes of cytokinesis.