bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Alfvén Wave Dynamics on the Large-scale Properties of the Solar Wind: Comparing an MHD Simulation with Parker Solar Probe E1 Data
Authors: Réville Victor , Velli Marco , Panasenco Olga , Tenerani Anna , Shi Chen , Badman Samuel T. , Bale Stuart D. , Kasper J. C. , Stevens Michael L. , Korreck Kelly E. , Bonnell J. W. , Case Anthony W. , de Wit Thierry Dudok , Goetz Keith , Harvey Peter R. , Larson Davin E. , Livi Roberto , Malaspina David M. , MacDowall Robert J. , Pulupa Marc , Whittlesey Phyllis L. 
Published: February 2020

Abstract
During Parker Solar Probe’s first orbit, the solar wind plasma was observed in situ closer than ever before, the perihelion on 2018 November 6 revealing a flow that is constantly permeated by large-amplitude Alfvénic fluctuations. These include radial magnetic field reversals, or switchbacks, that seem to be a persistent feature of the young solar wind. The measurements also reveal a very strong, unexpected, azimuthal velocity component. In this work, we numerically model the solar corona during this first encounter, solving the MHD equations and accounting for Alfvén wave transport and dissipation. We find that the large-scale plasma parameters are well reproduced, allowing the computation of the solar wind sources at Probe with confidence. We try to understand the dynamical nature of the solar wind to explain both the amplitude of the observed radial magnetic field and of the azimuthal velocities.
Solar Energetic Particles Produced by a Slow Coronal Mass Ejection at ∼0.25 au
Authors: Giacalone J. , Mitchell D. G. , Allen R. C. , Hill M. E. , McNutt R. L. , Szalay J. R. , Desai M. I. , Rouillard A. P. , Kouloumvakos A. , McComas D. J. , Christian E. R. , Schwadron N. A. , Wiedenbeck M. E. , Bale S. , Brown L. E. , Case A. , Chen X. , Cohen C. M. S. , Joyce C. , Kasper J. C. , Klein K. G. , Korreck K. , Larson D. E. , Livi R. , Leske R. A. , MacDowall R. J. , Matthaeus W. H. , Mewaldt R. A. , Nieves-Chinchilla T. , Pulupa M. , Roelof E. C. , Stevens M. L. , Szabo A. , Whittlesey P. L. 
Published: February 2020

Abstract
We present an analysis of Parker Solar Probe (PSP) IS⊙IS observations of ∼30–300 keV n−1 ions on 2018 November 11 when PSP was about 0.25 au from the Sun. Five hours before the onset of a solar energetic particle (SEP) event, a coronal mass ejection (CME) was observed by STEREO-A/COR2, which crossed PSP about a day later. No shock was observed locally at PSP, but the CME may have driven a weak shock earlier. The SEP event was dispersive, with higher energy ions arriving before the lower energy ones. Timing suggests the particles originated at the CME when it was at ∼7.4R
⊙. SEP intensities increased gradually from their onset over a few hours, reaching a peak, and then decreased gradually before the CME arrived at PSP. The event was weak, having a very soft energy spectrum (−4 to −5 spectral index). The earliest arriving particles were anisotropic, moving outward from the Sun, but later, the distribution was observed to be more isotropic. We present numerical solutions of the Parker transport equation for the transport of 30–300 keV n−1 ions assuming a source comoving with the CME. Our model agrees well with the observations. The SEP event is consistent with ion acceleration at a weak shock driven briefly by the CME close to the Sun, which later dissipated before arriving at PSP, followed by the transport of ions in the interplanetary magnetic field.
Clustering of Intermittent Magnetic and Flow Structures near Parker Solar Probe’s First Perihelion—A Partial-variance-of-increments Analysis
Authors: Chhiber Rohit , Goldstein M L. , Maruca B. A. , Chasapis A. , Matthaeus W. H. , Ruffolo D. , Bandyopadhyay R. , Parashar T. N. , Qudsi R. , de Wit T. Dudok , Bale S. D. , Bonnell J. W. , Goetz K. , Harvey P. R. , MacDowall R. J. , Malaspina D. , Pulupa M. , Kasper J. C. , Korreck K. E. , Case A. W. , Stevens M. , Whittlesey P. , Larson D. , Livi R. , Velli M. , Raouafi N. 
Published: February 2020

Abstract
During the Parker Solar Probe’s (PSP) first perihelion pass, the spacecraft reached within a heliocentric distance of ∼37 R
⊙ and observed numerous magnetic and flow structures characterized by sharp gradients. To better understand these intermittent structures in the young solar wind, an important property to examine is their degree of correlation in time and space. To this end, we use the well-tested partial variance of increments (PVI) technique to identify intermittent events in FIELDS and SWEAP observations of magnetic and proton-velocity fields (respectively) during PSP’s first solar encounter, when the spacecraft was within 0.25 au from the Sun. We then examine distributions of waiting times (WT) between events with varying separation and PVI thresholds. We find power-law distributions for WT shorter than a characteristic scale comparable to the correlation time of the fluctuations, suggesting a high degree of correlation that may originate in a clustering process. WT longer than this characteristic time are better described by an exponential, suggesting a random memory-less Poisson process at play. These findings are consistent with near-Earth observations of solar wind turbulence. The present study complements the one by Dudok de Wit et al., which focuses on WT between observed “switchbacks” in the radial magnetic field.
Magnetic Field Kinks and Folds in the Solar Wind
Authors: Tenerani Anna , Velli Marco , Matteini Lorenzo , Réville Victor , Shi Chen , Bale Stuart D. , Kasper Justin C. , Bonnell John W. , Case Anthony W. , de Wit Thierry Dudok , Goetz Keith , Harvey Peter R. , Klein Kristopher G. , Korreck Kelly , Larson Davin , Livi Roberto , MacDowall Robert J. , Malaspina David M. , Pulupa Marc , Stevens Michael , Whittlesey Phyllis 
Published: February 2020

Abstract

Parker Solar Probe (PSP) observations during its first encounter at 35.7 R
⊙ have shown the presence of magnetic field lines that are strongly perturbed to the point that they produce local inversions of the radial magnetic field, known as switchbacks. Their counterparts in the solar wind velocity field are local enhancements in the radial speed, or jets, displaying (in all components) the velocity–magnetic field correlation typical of large amplitude Alfvén waves propagating away from the Sun. Switchbacks and radial jets have previously been observed over a wide range of heliocentric distances by Helios, Wind, and Ulysses, although they were prevalent in significantly faster streams than seen at PSP. Here we study via numerical magnetohydrodynamics simulations the evolution of such large amplitude Alfvénic fluctuations by including, in agreement with observations, both a radial magnetic field inversion and an initially constant total magnetic pressure. Despite the extremely large excursion of magnetic and velocity fields, switchbacks are seen to persist for up to hundreds of Alfvén crossing times before eventually decaying due to the parametric decay instability. Our results suggest that such switchback/jet configurations might indeed originate in the lower corona and survive out to PSP distances, provided the background solar wind is sufficiently calm, in the sense of not being pervaded by strong density fluctuations or other gradients, such as stream or magnetic field shears, that might destabilize or destroy them over shorter timescales.
Seed Population Preconditioning and Acceleration Observed by the Parker Solar Probe
Authors: Schwadron N. A. , Bale S. , Bonnell J. , Case A. , Christian E. R. , Cohen C. M. S. , Cummings A. C. , Davis A. J. , Dudok de Wit T. , Wet W. de , Desai M. I. , Joyce C. J. , Goetz K. , Giacalone J. , Gorby M. , Harvey P. , Heber B. , Hill M. E. , Karavolos M. , Kasper J. C. , Korreck K. , Larson D. , Livi R. , Leske R. A. , Malandraki O. , MacDowall R. , Malaspina D. , Matthaeus W. H. , McComas D. J. , McNutt R. L. , Mewaldt R. A. , Mitchell D. G. , Mays L. , Niehof J. T. , Odstrcil D. , Pulupa M. , Poduval B. , Rankin J. S. , Roelof E. C. , Stevens M. , Stone E. C. , Szalay J. R. , Wiedenbeck M. E. , Winslow R. , Whittlesey P. 
Published: February 2020

Abstract
A series of solar energetic particle (SEP) events was observed by the Integrated Science Investigation of the Sun (IS⊙IS) on the Parker Solar Probe (PSP) during the period from 2019 April 18 through 24. The PSP spacecraft was located near 0.48 au from the Sun on Parker spiral field lines that projected out to 1 au within ∼25° of the near-Earth spacecraft. These SEP events, though small compared to historically large SEP events, were among the largest observed thus far in the PSP mission and provide critical information about the space environment inside 1 au during SEP events. During this period, the Sun released multiple coronal mass ejections (CMEs). One of these CMEs observed was initiated on 2019 April 20 at 01:25 UTC, and the interplanetary CME (ICME) propagated out and passed over the PSP spacecraft. Observations by the Electromagnetic Fields Investigation show that the magnetic field structure was mostly radial throughout the passage of the compression region and the plasma that followed, indicating that PSP did not directly observe a flux rope internal to the ICME, consistent with the location of PSP on the ICME flank. Analysis using relativistic electrons observed near Earth by the Electron, Proton and Alpha Monitor on the Advanced Composition Explorer demonstrates the presence of electron seed populations (40–300 keV) during the events observed. The energy spectrum of the IS⊙IS-observed proton seed population below 1 MeV is close to the limit of possible stationary-state plasma distributions out of equilibrium. IS⊙IS observations reveal the enhancement of seed populations during the passage of the ICME, which likely indicates a key part of the preacceleration process that occurs close to the Sun.
Switchbacks in the Near-Sun Magnetic Field: Long Memory and Impact on the Turbulence Cascade
Authors: Dudok de Wit Thierry , Krasnoselskikh Vladimir V. , Bale Stuart D. , Bonnell John W. , Bowen Trevor A. , Chen Christopher H. K. , Froment Clara , Goetz Keith , Harvey Peter R. , Jagarlamudi Vamsee Krishna , Larosa Andrea , MacDowall Robert J. , Malaspina David M. , Matthaeus William H. , Pulupa Marc , Velli Marco , Whittlesey Phyllis L. 
Published: February 2020

Abstract
One of the most striking observations made by Parker Solar Probe during its first solar encounter is the omnipresence of rapid polarity reversals in a magnetic field that is otherwise mostly radial. These so-called switchbacks strongly affect the dynamics of the magnetic field. We concentrate here on their macroscopic properties. First, we find that these structures are self-similar, and have neither a characteristic magnitude, nor a characteristic duration. Their waiting time statistics show evidence of aggregation. The associated long memory resides in their occurrence rate, and is not inherent to the background fluctuations. Interestingly, the spectral properties of inertial range turbulence differ inside and outside of switchback structures; in the latter the 1/f range extends to higher frequencies. These results suggest that outside of these structures we are in the presence of lower-amplitude fluctuations with a shorter turbulent inertial range. We conjecture that these correspond to a pristine solar wind.
Enhanced Energy Transfer Rate in Solar Wind Turbulence Observed near the Sun from Parker Solar Probe
Authors: Bandyopadhyay Riddhi , Goldstein M. L. , Maruca B. A. , Matthaeus W. H. , Parashar T. N. , Ruffolo D. , Chhiber R. , Usmanov A. , Chasapis A. , Qudsi R. , Bale Stuart D. , Bonnell J. W. , Dudok de Wit Thierry , Goetz Keith , Harvey Peter R. , MacDowall Robert J. , Malaspina David M. , Pulupa Marc , Kasper J. C. , Korreck K. E. , Case A. W. , Stevens M. , Whittlesey P. , Larson D. , Livi R. , Klein K. G. , Velli M. , Raouafi N. 
Published: February 2020

Abstract
Direct evidence of an inertial-range turbulent energy cascade has been provided by spacecraft observations in heliospheric plasmas. In the solar wind, the average value of the derived heating rate near 1 au is

, an amount sufficient to account for observed departures from adiabatic expansion. Parker Solar Probe, even during its first solar encounter, offers the first opportunity to compute, in a similar fashion, a fluid-scale energy decay rate, much closer to the solar corona than any prior in situ observations. Using the Politano–Pouquet third-order law and the von Kármán decay law, we estimate the fluid-range energy transfer rate in the inner heliosphere, at heliocentric distance R ranging from 54 R
⊙ (0.25 au) to 36 R
⊙ (0.17 au). The energy transfer rate obtained near the first perihelion is about 100 times higher than the average value at 1 au, which is in agreement with estimates based on a heliospheric turbulence transport model. This dramatic increase in the heating rate is unprecedented in previous solar wind observations, including those from Helios, and the values are close to those obtained in the shocked plasma inside the terrestrial magnetosheath.
Analysis of the Internal Structure of the Streamer Blowout Observed by the Parker Solar Probe During the First Solar Encounter
Authors: Nieves-Chinchilla Teresa , Szabo Adam , Korreck Kelly E. , Alzate Nathalia , Balmaceda Laura A. , Lavraud Benoit , Paulson Kristoff , Narock Ayris A. , Wallace Samantha , Jian Lan K. , Luhmann Janet G. , Morgan Huw , Higginson Aleida , Arge Charles N. , Bale Stuart D. , Case Anthony W. , Wit Thierry Dudok de , Giacalone Joe , Goetz Keith , Harvey Peter R. , Jones-Melosky Shaela I. , Kasper J. C. , Larson Davin E. , Livi Roberto , McComas David J. , MacDowall Robert J. , Malaspina David M. , Pulupa Marc , Raouafi Nour E. , Schwadron Nathan , Stevens Michael Louis , Whittlesey Phyllis L. 
Published: February 2020

Abstract
In this paper, we present an analysis of the internal structure of a coronal mass ejection (CME) detected by in situ instruments on board the Parker Solar Probe (PSP) spacecraft during its first solar encounter. On 2018 November 11 at 23:53 UT, the FIELDS magnetometer measured an increase in strength of the magnetic field as well as a coherent change in the field direction. The SWEAP instrument simultaneously detected a low proton temperature and signatures of bidirectionality in the electron pitch angle distribution (PAD). These signatures are indicative of a CME embedded in the slow solar wind. Operating in conjunction with PSP was the STEREO A spacecraft, which enabled the remote observation of a streamer blowout by the SECCHI suite of instruments. The source at the Sun of the slow and well-structured flux rope was identified in an overlying streamer, the details of which are described in Korreck et al. Our detailed inspection of the internal transient structure magnetic properties suggests high complexity in deviations from an ideal flux rope 3D topology. Reconstructions of the magnetic field configuration reveal a highly distorted structure consistent with the highly elongated “bubble” observed remotely. A double-ring substructure observed in the SECCHI-COR2 field of view (FOV) is suggestive of a double internal flux rope. Furthermore, we describe a scenario in which mixed topology of a closed flux rope is combined with the magnetically open structure, which helps explain the flux dropout observed in the measurements of the electron PAD. Our justification for this is the plethora of structures observed by the EUV imager (SECCHI-EUVI) in the hours preceding the streamer blowout evacuation. Finally, taking advantage of the unique observations from PSP, we explore the first stages of the effects of coupling with the solar wind and the evolutionary processes in the magnetic structure. We found evidence of bifurcated current sheets in the structure boundaries, suggestive of magnetic reconnection. Our analysis of the internal force imbalance indicates that internal Lorentz forces continue to dominate the evolution of the structure in the COR2 FOV and serve as the main driver of the internal flux rope distortion detected in situ at PSP solar distance.
The Radial Dependence of Proton-scale Magnetic Spectral Break in Slow Solar Wind during PSP Encounter 2
Authors: Duan Die , Bowen Trevor A. , Chen Christopher H. K. , Mallet Alfred , He Jiansen , Bale Stuart D. , Vech Daniel , Kasper J. C. , Pulupa Marc , Bonnell John W. , Case Anthony W. , de Wit Thierry Dudok , Goetz Keith , Harvey Peter R. , Korreck Kelly E. , Larson Davin , Livi Roberto , MacDowall Robert J. , Malaspina David M. , Stevens Michael , Whittlesey Phyllis 
Published: February 2020

Abstract
Magnetic field fluctuations in the solar wind are commonly observed to follow a power-law spectrum. Near proton-kinetic scales, a spectral break occurs that is commonly interpreted as a transition to kinetic turbulence. However, this transition is not yet entirely understood. By studying the scaling of the break with various plasma properties, it may be possible to constrain the processes leading to the onset of kinetic turbulence. Using data from the Parker Solar Probe, we measure the proton-scale break over a range of heliocentric distances, enabling a measurement of the transition from inertial to kinetic-scale turbulence under various plasma conditions. We find that the break frequency f

b
increases as the heliocentric distance r decreases in the slow solar wind following a power law of f

b
∼ r
−1.11. We also compare this to the characteristic plasma ion scales to relate the break to the possible physical mechanisms occurring at this scale. The ratio f

b
/f

c
(f

c
for Doppler-shifted ion cyclotron resonance scale) is close to unity and almost independent of plasma β

p
. While f

b
/f

ρ
(f

ρ
for Doppler-shifted proton thermal gyroradius) increases with β

p
approaching to unity at larger β

p
, f

b
/f

d
(f

d
for Doppler-shifted proton inertial length) decreases with β

p
from unity at small β

p
. Due to the large comparable Alfvén and solar wind speeds, we analyze these results using both the standard and modified Taylor hypotheses, demonstrating the robust statistical results.
La relación longitudinal de la participación política online y offline en el contexto de una campaña presidencial
Authors: Rodríguez-Estrada Alejandra , Muñiz Carlos , Echeverría Victoria Martín 
Published: February 2020

En la literatura se discute tradicionalmente el papel que tiene la participación política (PP) para la toma de decisiones democráticas de un país, casi siempre desde la dicotomía de PP formal o no formal. La hiperconexión de hoy en día, permite nuevas expresiones de PP que deben considerarse a la hora de entender el concepto en sí mismo. Y para hacerlo se sugiere entender la relación entre la PP offline y la online, sobre todo en tiempos que detonen dicha interacción, como ocurre en tiempos electorales.
Se aplicó una encuesta panel digital a nivel nacional con la finalidad de comparar la relación entre el reporte de la PP online con la offline. Se encontró que, sólo en el tiempo cercano a la elección y posterior a esta, se da un efecto spillover, en el que se puede hablar de que la PP offline influye en la online.
Fluid-Mineral Equilibria in Hydrothermal Systems
Authors: Henley R. W. , Truesdell A. H. , Barton P. B. , Whitney J. A. 
Published: February 2020

Abstract
This text is designed to introduce you to the practical concepts and calculations involved in interpreting the chemistry of high-temperature fluids in geothermal systems and hydrothermal ore-forming environments. It is intended that the energetic reader will learn to understand chemical principles, handle routine calculations and follow specialized chemical studies involved in geothermal exploration and exploitation and in ore genesis.
Although the emphasis of the text is on the interpretation of the chemistry of active geothermal systems, the principles involved are equally relevant to the interpretation of fossil hydrothermal ore-forming environments. Many gold-silver ore deposits, for example, have been shown to have formed in the near-surface region of hydrothermal systems similar in fluid chemistry and setting to those active today (White, 1981; Henley and Ellis, 1983). Combination of a knowledge of the principle processes within the active geothermal systems, the thermodynamics of complex ion formation, mineral-fluid equilibria and stable isotope systematics provide a framework which may assist in reconstruction of the hydrological regime within a fossil hydrothermal system where ore deposition occurred. This in turn may become useful in ore search. A chapter dealing with the hydrothermal chemistry of magmatic systems is included later in order to encompass a wider range of ore depositing environments and perhaps the root zones of the active geothermal systems.
After a short introduction to the types of geothermal fluids and chemical calculations, successive chapters will address the interpretation of water and gas analyses from geothermal wells. When we understand the reservoir compositions of some geothermal fluids and their relations to rock chemistry and temperature, we will consider the chemical and isotopic changes that occur in the natural transport of this fluid to the surface, derive and use chemical geothermometers and mixing relations, and map the surface chemistry of a hot spring system. After these studies of natural fluids at depth and at the surface, we will study chemical changes that occur during the exploitation of geothermal fluids and how to anticipate and avoid some of the problems of scaling and corrosion.
General Aspects of Aquatic Colloids in Environmental Geochemistry
Authors: Ranville J.F. , Schmiermund R.L. 
Published: February 2020

Abstract
A recent emphasis in society is on conducting mining activities with the least environmental impact possible. A manifestation of this is the costonitoring of contaminant levels in surface and ground waters, usually in order to meet specific environmental regulations. However the simple collection of monitoring data may not provide understanding of either the actual impact of mining on the environment or suggest the most appropriate treatment processes for specific mining wastes. More detailed information on the chemical and physical forms of contaminants is needed. One aspect of this is that the occurrence and distribution of natural and anthropogenic chemicals in natural water systems is strongly influenced by their partitioning between solid and aqueous phases (Allan, 1986). Therefore contaminant behavior is generally defined in terms of “two-phase” water-rock interactions where metals, for example, are present either in the stationary solid phases of the country rock, ore pad, waste rock pile, tailings empound- ment, or slag heap or they are present as mobile, aqueous phase solutes. For groundwater the solid phase is considered to be the stationary aquifer material. In surface waters the solid phases generally considered are the sediments in the stream, pond, or lake bottom. Accordingly, computer models have been developed that address dissolution, precipitation, adsorption, and desorption between the solid and aqueous phases as well as the formation of various solute species and complexes.
Bioavailability of Metals in the Environment
Authors: Krieger G.R. , Hattemer-Frey H.A. , Kester J.E. 
Published: February 2020

Abstract
The bioavailability of environmental contaminants, including heavy metals, is an important issue in assessing exposure and resultant risk to human and ecological receptors that contact these chemicals in the environment. Risk assessment at hazardous waste sites consists of two major elements: exposure assessment (estimation of chemical intake) and toxicity assessment (estimation of the chemical dose-response relationship). These two elements are combined in the process of risk characterization to provide risk managers with as complete and accurate a projection of site risks, including uncertainties, as possible. Chemical exposure is estimated by use of standard intake equations. For example, chemical intake via contaminated soil is modeled as (U.S. EPA, 1989):