bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Characteristics of Geomagnetic Storms Observed During the Past 415 Years
Authors: Haritha V. G. , Eapen P. E. , Gopkumar G. , Girish T. E. 
Published: November 2018

AbstractIn this paper we will present our investigations on the characteristics of geomagnetic storms deduced from direct and proxy observations for the years 1601–2016 AD. We show that we could infer epoch of reversal of solar polar magnetic fields from geomagnetic data. Such an inference is done back to the 18th century using geomagnetic and Aurora observations. We could also infer secular changes in the intensity of geomagnetic storms for the past 415 years.
Characteristics of Solar Proton Events Observed Near Earth and Stellar Activity Variations
Authors: Aranya S. , Girish T. E. , Gopkumar G. , Nisha N. G. 
Published: November 2018

AbstractWe could identify three categories of solar proton events (SPE) with distinct solar origin from an analysis of direct and indirect observations during the years 1561-2016 CE spanning 42 sunspot cycles. They are (i) 10 MeV SPE whose number of occurrences closely follow the sunspot cycles (ii) 30 MeV SPE which show secular changes with peaks near Gleissberg solar cycle minima and inferred to be associated with distinct enhancements in the efficiency of the solar dynamo and (iii) those associated with Impulsive and irregular solar activity changes such as the Carrington event of September 1859. The relevance of above results for stars exhibiting cyclic and irregular activity changes will be also discussed.
Prediction of upcoming grand episodes of solar activity
Authors: Jayalekshmi G. L. , Prince P. R. 
Published: November 2018

AbstractSunspots are active regions on the surface of the Sun having strong magnetic fields. Activity level of the Sun shows long-time scale phenomena known as grand episodes-Grand maxima and Grand minima. Present study examines grand episodes shown by sunspot numbers (1090-2017), using methods of wavelet transform and sinusoidal regression. Time interval analysed includes two grand maxima and four grand minima. Interval in between grand episodes are regular oscillations. Phase changes found from periodicity analysis clearly show the presence of upcoming grand episodes. The forthcoming grand episodes are suggested to be two grand minima which are likely to occur between the years 2100-2160 and 2220-2300.
Study of starspots in fully convective stars using three dimensional MHD simulations
Authors: Basak Arnab , Nandy Dibyendu 
Published: November 2018

AbstractConcentrated magnetic structures such as sunspots and starspots play a fundamental role in driving solar and stellar activity. However, as opposed to the sun, observations as well as numerical simulations have shown that stellar spots are usually formed as high-latitude patches extended over wide areas. Using a fully spectral magnetohydrodynamic (MHD) code, we simulate polar starspots produced by self-consistent dynamo action in rapidly rotating convective shells. We carry out high resolution simulations and investigate various properties related to stellar dynamics which lead to starspot formation.
Asymmetry in Solar Torsional Oscillation
Authors: Lekshmi B , Nandy Dibyendu , Antia H M 
Published: November 2018

AbstractSolar torsional oscillations are migrating bands of slower and faster than average rotation, which are thought to be related to the Sun’s magnetic cycle. We perform the first long-term study (16 years) of hemispherical asymmetry in solar torsional oscillation velocity using helioseismic data. We explore the spatial and temporal variation of North-South asymmetry using zonal flow velocities obtained from ring diagram analysis of the Global Oscillation Network Group (GONG) Doppler images. We find a strong correlation between the asymmetries of near-surface torsional oscillation with magnetic flux and sunspot number, with the velocity asymmetry preceding in both the cases. We speculate that the asymmetry in torsional oscillation velocity may help in predicting the hemispherical asymmetry in the sunspot cycle.
The activity evolution of Solar-like stars with age and its planetary impact
Authors: Das Srijan Bharati , Basak Arnab , Nandy Dibyendu 
Published: November 2018

AbstractThe age-dependent activity of a star dictates the extent of its planetary impact. We study the interaction of the stellar wind produced by Solar-like stars with the magnetosphere of Earth-like planets using three dimensional (3D) magnetohydrodynamic (MHD) simulations. The numerical simulations reveal important features of star-planet interaction e.g. bow-shock, magnetopause, magnetotail, etc. Interesting phenomena such as particle injection into the planetary atmosphere as well as atmospheric mass loss are also observed which are instrumental in determining the atmospheric retention by the planet.
Association of calcium network brightness with polar magnetic fields
Authors: Narang Nancy , Chandrashekhar Kalugodu , Pant Vaibhav , Banerjee Dipankar 
Published: November 2018

AbstractRecent dedicated HINODE polar region campaign revealed the presence of concentrated kilogauss patches of magnetic field in the polar regions of Sun which are also shown to be correlated with facular bright points at the photospheric level. In this work, we demonstrate that this spatial intermittency of the magnetic field persists even up to the chromospheric heights. Polar network bright points are the ones which are present in the polar regions of the Sun (above 70° latitudes). We use special HINODE campaigns devoted to observe polar regions of the Sun to study the polar network bright points during the phase of last extended solar minimum. We are able to find a considerable association between the polar network bright points and magnetic field concentrations which led us to conclude that these bright points can serve as a good proxy for polar magnetic fields where the direct and regular measurements of polar magnetic fields are not available (before 1970).
Search for Correlation between Solar Flare Count and Mean Solar Magnetic Field
Authors: Joshi Chandan , Sobha B. , Joshi Vishwas Deep 
Published: November 2018

AbstractAn investigation for search of correlation between the daily observations of mean magnetic field and daily flare count number in different class is studied here. The daily observations for mean magnetic field presented here are taken by Wilcox Solar observatory and daily flare count in different X-ray class is provided by National Centers For Environmental Information.
Connection between Active region complexity and Solar Flare strength
Authors: Amareswari K. , Padinhatteeri Sreejith , Sankarasubramanian K. 
Published: November 2018

AbstractHale (1908) discovered the existence of magnetic fields in sunspots, and since then a consensus has been reached that magnetic fields play an important role in various forms of solar activities, such as solar flares . Modified Mount-Wilson scheme is one of the methodology to classify active regions based on their complexity . As per this scheme, sunspots are classified as α, β, γ, and δ with the complexity of the magnetic topology increasing from α to δ. The δ sunspots are known to be highly flare-productive. An existing automated algorithm (SMART-DF) is modified and used to identify δ-spots for the existing full disk SOHO/MDI data. The automatically identified δ-spots is compared with the NOAA-SRS database and found to be reproducing almost all the identified δ-spots. In thisstudy, the connection between formation of δ-spot and flares is also carried out using GOES flare flux and NOAA-SRS sunspot classification.
Long-term variation of sunspot penumbra to umbra area ratio
Authors: Jha Bibhuti Kumar , Mandal Sudip , Banerjee Dipankar 
Published: November 2018

AbstractA typical sunspot, as seen in white-light intensity images, has a two part structure: a dark umbra and a lighter penumbra. Such distinction primarily arises due to the different orientations of magnetic fields in these two regions. In this study, we use the Kodaikanal white-light digitized data archive to analyze the long-term evolution of umbral and penumbal area. We used an ‘automated algorithm’ to uniquely identify the sunspot umbra (including the calculation of penumbra to umbra ratio) from these digitized intensity images. Our analysis reveals that the ratio increases slightly with the increase of sunspot area upto 100 μHem but eventually settles down to a constant value after that. This study, not only allows us to better understand the evolution of an individual spot and its corresponding magnetic field but this is also beneficial for solar dynamo studies which aim to reproduce such structures using a MHD theory.
Nonlinear Autoregressive Model (NARX) of Stationary Forbush Decrease Indices Based on Levenberg-Marquardt Feedback Algorithm
Authors: Patra Sankar Narayan , Panja Subhash Chandra , Prasad Amrita , Roy Soumya , Ghosh Koushik 
Published: November 2018

AbstractArtificial Neural Network based Nonlinear Autoregressive Model is designed to reconstruct and predict Forbush Decrease (FD) Data obtained from Izmiran, Russia. Result indicates that the model seems adequate for short term prediction of the FD data.
Influence of Planets on the Magnetic Activity of Sun-Like Stars
Authors: Gurumath Shashanka R. , Hiremath K. M. , Ramasubramanian V. 
Published: November 2018

AbstractBy considering the physical properties of Sun-like G stars and their exoplanets, present study examines whether presence of planets near the host stars enhances their stellar activity. In order to attain this goal, chromospheric RHK index data-a proxy for the magnetic activity-for the stars with and without planets is considered. With the reasonable constraints on the exoplanetary data, we obtained a power law decay relationship between the magnetic activity of host stars and their ages, for stars with and without planets. Both these results strongly suggest that there is no difference in magnetic activity of the sun-like stars with and without presence of planets. In order to confirm this result, further we also examine an association between the host stars RHK index that have exoplanets and their respective exoplanetary masses. We find that magnitude of RHK (hence magnetic activity) of the host stars is independent of presence of planetary mass in its vicinity.
Fault‐Tolerant b‐Values and Aftershock Productivity
Authors: Page M. T. , van der Elst N. J. 
Published: November 2018

AbstractWhen it comes to smaller earthquakes, are major faults special? Page et al., (2011,https://doi.org/10.1029/2010JB007933) showed that earthquakes near the faults that compose version 3.0 of the Southern California Earthquake Center Community Fault Model (CFM) have a lower Gutenberg‐Richter b‐value than earthquakes elsewhere in Southern California. Here we revisit their result, using newer earthquake data recorded after version 3.0 of the CFM was completed. We find that the correlation between earthquake size and proximity to major faults is not present in the newer seismicity data. This indicates that to some degree, the CFM is overtuned to past seismicity, with some structures related to transient features in seismicity rather than persistent geologic features. We also search for differences in aftershock productivity and foreshock statistics near faults and find that they are also “fault‐tolerant”—that is, insensitive to distance from major faults. Our results suggest that the fault system in Southern California is highly connected, since the chance of an earthquake nucleating on or near a major fault versus on a secondary structure is independent of its final size.
A New Global Database of Lunar Impact Craters >1–2 km: 1. Crater Locations and Sizes, Comparisons With Published Databases, and Global Analysis
Authors: Robbins Stuart J. 
Published: November 2018

AbstractThis paper presents a new, global database of lunar impact craters, estimated to be a complete census of all craters with diameters larger than 1–2 km. The database contains over 2 million craters, making it larger in number than any previously published lunar effort by more than a factor of 10. Of those craters, 1.3 million have diameters ≥1 km, approximately 83,000 are ≥5 km, and 6,972 craters are ≥20 km. How the database was constructed along with the reliability of features is described in detail. Comparisons are made with past published databases, demonstrating good agreement for crater size and location. An ellipticity analysis is conducted, illustrating there is no dominant direction for elliptical crater orientation based on location, diameter range, or ellipticity amount, consistent with randomness for craters ≥10 km. A spatial density analysis is described, comparing the spatial density of small versus large craters, and numerous observations about the nonuniformity of the size distributions of craters across the Moon are made. The spatial density is also used in a discussion about kilometer‐scale secondary impact craters and clearly shows that they dominate the crater population in some areas of the lunar surface. This paper presents just a tiny sample of the scientific investigations that could be done with this new crater database.
Using Emulators to Understand the Sensitivity of Deep Convective Clouds and Hail to Environmental Conditions
Authors: Wellmann C. , Barrett A. I. , Johnson J. S. , Kunz M. , Vogel B. , Carslaw K. S. , Hoose C. 
Published: November 2018

AbstractThis study aims to identify model parameters describing atmospheric conditions such as wind shear and cloud condensation nuclei (CCN) concentration, which lead to large uncertainties in the prediction of deep convective clouds. In an idealized setup of a cloud‐resolving model including a two‐moment microphysics scheme we use the approach of statistical emulation to allow for a Monte Carlo sampling of the parameter space, which enables a comprehensive sensitivity analysis. We analyze the impact of six uncertain input parameters on cloud properties (vertically integrated content of six hydrometeor classes), precipitation, and the size distribution of hail. Furthermore, we investigate whether the sensitivities are robust for different trigger mechanisms of convection. We find that the uncertainties of most cloud and precipitation outputs are dominated by the uncertainty in the temperature profile and the CCN concentration while the contributions of other input parameters to the uncertainties may vary. The temperature profile is also an important factor in determining the size distribution of surface hail. We also notice that the sensitivities of cloud water and hail to the CCN concentration depend on environmental conditions. Our results show that depending on the choice of the trigger mechanism, the contribution of the input parameters to the uncertainty varies, which means that studies with different trigger mechanisms might not be comparable. Overall, the emulator approach appears to be a powerful tool for the analysis of complex weather prediction models in an idealized setup.
A simple and robust approach to reducing contact resistance in organic transistors
Authors: Lamport Zachary A. , Barth Katrina J. , Lee Hyunsu , Gann Eliot , Engmann Sebastian , Chen Hu , Guthold Martin , McCulloch Iain , Anthony John E. , Richter Lee J. , DeLongchamp Dean M. , Jurchescu Oana D. 
Published: November 2018

AbstractEfficient injection of charge carriers from the contacts into the semiconductor layer is crucial for achieving high-performance organic devices. The potential drop necessary to accomplish this process yields a resistance associated with the contacts, namely the contact resistance. A large contact resistance can limit the operation of devices and even lead to inaccuracies in the extraction of the device parameters. Here, we demonstrate a simple and efficient strategy for reducing the contact resistance in organic thin-film transistors by more than an order of magnitude by creating high work function domains at the surface of the injecting electrodes to promote channels of enhanced injection. We find that the method is effective for both organic small molecule and polymer semiconductors, where we achieved a contact resistance as low as 200 Ωcm and device charge carrier mobilities as high as 20 cm2V−1s−1, independent of the applied gate voltage.
Islr regulates canonical Wnt signaling-mediated skeletal muscle regeneration by stabilizing Dishevelled-2 and preventing autophagy
Authors: Zhang Kuo , Zhang Yuying , Gu Lijie , Lan Miaomiao , Liu Chuncheng , Wang Meng , Su Yang , Ge Mengxu , Wang Tongtong , Yu Yingying , Liu Chang , Li Lei , Li Qiuyan , Zhao Yaofeng , Yu Zhengquan , Wang Fudi , Li Ning , Meng Qingyong 
Published: November 2018

AbstractSatellite cells are crucial for skeletal muscle regeneration, but the molecular mechanisms regulating satellite cells are not entirely understood. Here, we show that the immunoglobulin superfamily containing leucine-rich repeat (Islr), a newly identified marker for mesenchymal stem cells, stabilizes canonical Wnt signaling and promote skeletal muscle regeneration. Loss of Islr delays skeletal muscle regeneration in adult mice. In the absence of Islr, myoblasts fail to develop into mature myotubes due to defective differentiation. Islr interacts with Dishevelled-2 (Dvl2) to activate canonical Wnt signaling, consequently regulating the myogenic factor myogenin (MyoG). Furthermore, Islr stabilizes Dvl2 by reducing the level of LC3-labeled Dvl2 and preventing cells from undergoing autophagy. Together, our findings identify Islr as an important regulator for skeletal muscle regeneration.
Soil management is key to maintaining soil moisture in urban gardens facing changing climatic conditions
Authors: Lin Brenda B. , Egerer Monika H. , Liere Heidi , Jha Shalene , Philpott Stacy M. 
Published: November 2018

AbstractUrban gardens are vital green spaces, providing food for residents and space for engaged citizenry and community development. In California, climate change conditions (heat and drought) are becoming more extreme, threatening the resilience of urban gardens. Water use restrictions limit the timing and amount of water that gardeners can access, exacerbating these climate challenges for urban food production. Together with volunteer gardeners, we examined how ambient temperature, water use, vegetation, ground cover, and soil management affect rates of soil moisture gain and loss in urban gardens for a six-week period in the summer of 2017, during the hottest part of the growing season. We found that plot-level management of soils is essential for creating urban garden plots that maintain stable levels of water within garden soils. Although plots with better soil quality (i.e. water holding capacity) experienced slower rates of soil moisture gain after a watering event, they also experienced slower rates of soil moisture loss after the event, leading to soils with more stable, less fluctuating moisture profiles over time. This may benefit gardeners because under extreme climates (such as heat and drought) and water use restrictions, maintaining more stable soils for their plants means that the soils will retain water over a longer period after each watering event. Overall, such results highlight that better soil management that improves soil quality measures such as water holding capacity are potential solutions for maintaining soil moisture and reducing water use under changing climate conditions.
Engineered K1F bacteriophages kill intracellular Escherichia coli K1 in human epithelial cells
Authors: Møller-Olsen Christian , Ho Siu Fung Stanley , Shukla Ranti Dev , Feher Tamas , Sagona Antonia P. 
Published: November 2018

AbstractBacterial infections can be treated with bacteriophages that show great specificity towards their bacterial host and can be genetically modified for different applications. However, whether and how bacteriophages can kill intracellular bacteria in human cells remains elusive. Here, using CRISPR/Cas selection, we have engineered a fluorescent bacteriophage specific forE. coliK1, a nosocomial pathogen responsible for urinary tract infections, neonatal meningitis and sepsis. By confocal and live microscopy, we show that engineered bacteriophages K1F-GFP andE. coliEV36-RFP bacteria displaying the K1 capsule, enter human cells via phagocytosis. Importantly, we show that bacteriophage K1F-GFP efficiently kills intracellularE. coliEV36-RFP in T24 human urinary bladder epithelial cells. Finally, we provide evidence that bacteria and bacteriophages are degraded by LC3-associated phagocytosis and xenophagy.
SIRT3 deficiency-induced mitochondrial dysfunction and inflammasome formation in the brain
Authors: Tyagi Alpna , Nguyen Christy U , Chong Thomas , Michel Cole R , Fritz Kristofer S. , Reisdorph Nichole , Knaub Leslie , Reusch Jane E. B. , Pugazhenthi Subbiah 
Published: November 2018

AbstractSIRT3, the primary mitochondrial deacetylase, plays a significant role in enhancing the function of mitochondrial proteins. Downregulation of SIRT3 is a key component of metabolic syndrome, a precondition for obesity, diabetes and cardiovascular diseases. In this study, we examined the effects of brain mitochondrial protein hyperacetylation in western diet-fed Sirt3−/− mice, a model for metabolic syndrome. Brain mitochondrial proteins were hyperacetylated, following western diet feeding and Sirt3 deletion. To identity these hyperacetylated proteins, we performed a comprehensive acetylome analysis by label-free tandem mass spectrometry. Gene ontology pathway analysis revealed Sirt3 deletion-mediated downregulation of enzymes in several metabolic pathways, including fatty acid oxidation and tricarboxylic acid cycle. Mitochondrial respiration was impaired at multiple states, along with lower levels of mitochondrial fission proteins Mfn1 and Mfn2. Cleavage of procaspase-1 suggested inflammasome formation. Assembly of inflammasomes with caspase-1 and NLRP3 was detected as shown by proximity ligation assay. Markers of neuroinflammation including microgliosis and elevated brain IL-1β expression were also observed. Importantly, these findings were further exacerbated in Sirt3−/− mice when fed a calorie-rich western diet. The observations of this study suggest that SIRT3 deficiency-induced brain mitochondrial dysfunction and neuroinflammation in metabolic syndrome may play a role in late-life cognitive decline.