bluuebunny/crossref_metadata_2025 huggingface dataset:
V346 Nor: The Post-outburst Life of a Peculiar Young Eruptive Star
Authors: Kóspál Á. , Szabó Zs. M. , Ábrahám P. , Kraus S. , Takami M. , Lucas P. W. , Contreras Peña C. , Udalski A.
Published: February 2020

FU Orionis-type objects (FUors) are young low-mass stars undergoing powerful accretion outbursts. The increased accretion is often accompanied by collimated jets and energetic, large-scale molecular outflows. The extra heating during the outburst may also induce detectable geometrical, chemical, and mineralogical changes in the circumstellar material, affecting possible planet formation around these objects. V346 Nor is a southern FUor with peculiar spectral characteristics. Decades after the beginning of its outburst, it unexpectedly underwent a fading event around 2010 due to a decrease in the mass accretion rate onto the star by at least two orders of magnitude. Here we present optical and near-infrared photometry and spectroscopy obtained after the minimum. Our light curves show a gradual re-brightening of V346 Nor, with its K
s-band brightness only 1.5 mag below the outburst brightness level. Our Very Large Telescope (VLT)/XSHOOTER spectroscopic observations display several strong forbidden emission lines toward the source from various metals and molecular hydrogen, suggesting the launch of a new jet. Our N-band spectrum obtained with VLT/VISIR outlines a deeper silicate absorption feature than before, indicating that the geometry of the circumstellar medium has changed in the post-outburst period compared to peak brightness.
Detecting Gravitational Scattering of Interstellar Objects Using Pulsar Timing
Authors: Jennings Ross J. , Cordes James M. , Chatterjee Shami
Published: February 2020

Gravitational scattering events, in which the path of an interstellar object is deflected by a pulsar or the solar system, give rise to reflex motion that can potentially be detected using pulsar timing. We determine the form of the timing signal expected from a gravitational scattering event, which is ramp-like and resembles the signal produced by a glitch or a gravitational wave burst with memory (BWM), and investigate the prospects for detecting such a signal using a pulsar timing array. The level of timing precision currently achieved for some millisecond pulsars makes it possible to detect objects as small as 10−10
M
☉, less than the mass of the dwarf planet Ceres, at impact parameters as large as

. The signals produced by gravitational scattering could provide independent constraints on models of dark matter involving asteroid-mass objects or subhalos, and should be considered as potential false positives in searches for BWMs.
A Timing Study of MAXI J1820+070 Based on Swift/XRT and NICER Monitoring in 2018/19
Authors: Stiele H. , Kong A. K. H.
Published: February 2020

We present a detailed timing analysis of the bright black hole X-ray binary MAXI J1820+070 (ASASSN-18ey), during its first detected outburst lasting from 2018 March until 2019 October based on Swift/XRT window timing mode observations, corresponding UVOT data and NICER observations. The light curves clearly show four outbursts, with the source remaining in the hard state during its first outburst, while the rise of the second outburst corresponds with the transition to the soft state. A similar double outburst of GX339-4 has been observed in 2004. Here it is followed by two hard-state only outbursts. In many observations the power density spectra showed type-C quasi-periodic oscillations (QPOs) with characteristic frequencies below 1 Hz, which suggests that the source stayed in a state of low effective accretion for large parts of its outburst. The absence of other types of QPOs hinders a precise determination of the state transitions, but from combining NICER and Swift/XRT data, we find that MAXI J1820+070 went from the hard-intermediate to the soft state in less than one day. The covariance ratios derived from NICER data show an increase toward lower energies, which indicate that the source should make a transition to the soft state. This transition finally took place, after MAXI J1820+070 stayed in the hard state at rather constant luminosity for about 116 days. The steepness of the increase of the covariance ratios is not correlated with the amount of rms variability and it does not show a monotonic evolution along the outburst.
A Noncorotating Gas Component in an Extreme Starburst at z = 4.3
Authors: Tadaki Ken-ichi , Iono Daisuke , Yun Min S. , Aretxaga Itziar , Hatsukade Bunyo , Lee Minju M. , Michiyama Tomonari , Nakanishi Kouichiro , Saito Toshiki , Ueda Junko , Umehata Hideki
Published: February 2020

We report the detection of a noncorotating gas component in a bright unlensed submillimeter galaxy at z = 4.3, hosting a compact starburst. Atacama Large Millimeter/submillimeter Array 0.″17 and 0.″09 resolution observations of [C ii] emission clearly demonstrate that the gas kinematics are characterized by an ordered rotation. After subtracting the best-fit model of a rotating disk, we kinematically identify two residual components in the channel maps. Both observing simulations and analysis of dirty images confirm that these two subcomponents are not artificially created by noise fluctuations and beam deconvolution. One of the two has a velocity offset of 200 km s−1 and a physical separation of 2 kpc from the primary disk and is located along the kinematic minor axis of disk rotation. We conclude that this gas component is falling into the galaxy from a direction perpendicular to the disk rotation. The accretion of such small noncorotating gas components could stimulate violent disk instability, driving radial gas inflows into the center of galaxies and leading to formation of in situ clumps such as identified in dust continuum and CO. We require more theoretical studies on high gas fraction mergers with mass ratio of 1: > 10 to verify this process.
High-resolution Near-infrared Polarimetry and Submillimeter Imaging of FS Tau A: Possible Streamers in Misaligned Circumbinary Disk System
Authors: Yang Yi , Akiyama Eiji , Currie Thayne , Dong Ruobing , Hashimoto Jun , Hayashi Saeko S. , Grady Carol A. , Janson Markus , Jovanovic Nemanja , Uyama Taichi , Nakagawa Takao , Kudo Tomoyuki , Kusakabe Nobuhiko , Kuzuhara Masayuki , Abe Lyu , Brandner Wolfgang , Brandt Timothy D. , Bonnefoy Michael , Carson Joseph C. , Chilcote Jeffrey , Rich Evan A. , Feldt Markus , Goto Miwa , Groff Tyler D. , Guyon Olivier , Hayano Yutaka , Hayashi Masahiko , Henning Thomas , Hodapp Klaus W. , Ishii Miki , Iye Masanori , Kandori Ryo , Kasdin Jeremy , Knapp Gillian R. , Kwon Jungmi , Lozi Julien , Martinache Frantz , Matsuo Taro , Mayama Satoshi , Mcelwain Michael W. , Miyama Shoken , Morino Jun-Ichi , Moro-Martin Amaya , Nishimura Tetsuo , Pyo Tae-Soo , Serabyn Eugene , Suto Hiroshi , Suzuki Ryuji , Takami Michihiro , Takato Naruhisa , Terada Hiroshi , Thalmann Christian , Turner Edwin L. , Watanabe Makoto , Wisniewski John P. , Yamada Toru , Takami Hideki , Usuda Tomonori , Tamura Motohide
Published: February 2020

We analyzed the young (2.8 Myr-old) binary system FS Tau A using near-infrared (H-band) high-contrast polarimetry data from Subaru/HiCIAO and submillimeter CO (J = 2–1) line emission data from Atacama Large Millimeter/submillimeter Array (ALMA). Both the near-infrared and submillimeter observations reveal several clear structures extending to ∼240 au from the stars. Based on these observations at different wavelengths, we report the following discoveries. One arm-like structure detected in the near-infrared band initially extends from the south of the binary with a subsequent turn to the northeast, corresponding to two bar-like structures detected in ALMA observations with an local standard of rest kinematic (LSRK) velocity of 1.19–5.64 km s−1. Another feature detected in the near-infrared band extends initially from the north of the binary, relating to an arm-like structure detected in ALMA observations with an LSRK velocity of 8.17–16.43 km s−1. From their shapes and velocities, we suggest that these structures can mostly be explained by two streamers that connect the outer circumbinary disk and the central binary components. These discoveries will be helpful for understanding the evolution of streamers and circumstellar disks in young binary systems.
Two Quasi-periodic Fast-propagating Magnetosonic Wave Events Observed in Active Region NOAA 11167
Authors: Miao Yuhu , Liu Yu , Elmhamdi A. , Kordi A. S. , Shen Y. D. , Al-Shammari Rehab , Al-Mosabeh Khaled , Jiang Chaowei , Yuan Ding
Published: February 2020

We report a detailed observational study of two quasi-periodic fast-propagating (QFP) magnetosonic wave events that occurred on 2011 March 9 and 10, respectively. Interestingly, both the events have two wave trains (WTs): a strong main one (WT-1) and a small and weak secondary one (WT-2). Peculiar and common characteristics of the two events are observed, namely, (1) the two QFP waves are accompanied with brightenings during the whole stage of the eruptions; (2) both the two main WTs are nearly propagating along the same direction; (3) extreme-ultraviolet (EUV) waves are found to be associated with the two events. Investigating various aspects of the target events, we argue that (1) the second event is accompanied with a flux rope eruption during the whole stage; (2) the second event eruption produces a new filament-like dark feature; (3) the ripples of the two WT-2 QFP waves seem to result from different triggering mechanisms. Based on the obtained observational results, we propose that the funnel-like coronal loop system is indeed playing an important role in the two WT-1 QFP waves. The development of the second WT-2 QFP wave can be explained as due to the dispersion of the main EUV front. The coexistence of the two events offers thereby a significant opportunity to reveal what driving mechanisms and structures are tightly related to the waves.
Balmer Break Galaxy Candidates at z ∼ 6: A Potential View on the Star Formation Activity at z ≳ 14
Authors: Mawatari Ken , Inoue Akio K. , Hashimoto Takuya , Silverman John , Kajisawa Masaru , Yamanaka Satoshi , Yamada Toru , Davidzon Iary , Capak Peter , Lin Lihwai , Hsieh Bau-Ching , Taniguchi Yoshiaki , Tanaka Masayuki , Ono Yoshiaki , Harikane Yuichi , Sugahara Yuma , Fujimoto Seiji , Nagao Tohru
Published: February 2020

We search for galaxies with a strong Balmer break (Balmer break galaxies; BBGs) at z ∼ 6 over a 0.41 deg2 effective area in the COSMOS field. Based on rich imaging data, including data obtained with the Atacama Large Millimeter/submillimeter Array (ALMA), three candidates are identified by their extremely red K–[3.6] colors, as well as by nondetection in the X-ray, optical, far-infrared, and radio bands. The nondetection in the deep ALMA observations suggests that they are not dusty galaxies but BBGs at z ∼ 6, although contamination from active galactic nuclei at z ∼ 0 cannot be completely ruled out for the moment. Our spectral energy distribution analyses reveal that the BBG candidates at z ∼ 6 have stellar masses of ≈5 × 1010
M
⊙ dominated by old stellar populations with ages of ≳ 700 Myr. Assuming that all three candidates are real BBGs at z ∼ 6, we estimate the stellar mass density to be

Mpc−3. This is consistent with an extrapolation from the lower-redshift measurements. The onset of star formation in the three BBG candidates is expected to be several hundred million yr before the observed epoch of z ∼ 6. We estimate the star formation rate density (SFRD) contributed by progenitors of the BBGs to be 2.4–12 × 10−5
M
⊙ yr−1 Mpc−3 at z > 14 (99.7% confidence range). Our result suggests a smooth evolution of the SFRD beyond z = 8.
Modeling the Upper kHz QPOs of 4U 1728-34 with X-Ray Reverberation
Authors: Coughenour Benjamin M. , Cackett Edward M. , Peille Philippe , Troyer Jon S.
Published: February 2020

While kilohertz quasi-periodic oscillations (kHz QPOs) have been well studied for decades since their initial discovery, the cause of these signals remains unknown, as no model has been able to accurately predict all of their spectral and timing properties. Separately, X-ray reverberation lags have been detected in active galactic nuclei and stellar-mass black hole binaries, and reverberation may be expected to occur in neutron star systems as well, producing lags of the same amplitude as the lags measured of the kHz QPOs. Furthermore, the detection of a relativistically reflected Fe K line in the time-averaged spectra of many neutron star systems provides an additional motivation for testing reverberation. While it has been shown that the lag-energy properties of the lower kHz QPOs are unlikely to be produced by X-ray reverberation, the upper kHz QPOs have not yet been explored. We therefore model the upper kHz QPO lag-energy spectra using relativistic ray-tracing functions and apply them to archival Rossi X-Ray Timing Explorer data on 4U 1728–34 where upper kHz QPOs have been detected. By modeling the time-averaged spectra in which upper kHz QPOs had been significantly detected, we determine the reflected flux fraction across all energies and produce a model for the lag-energy spectra from X-ray reverberation. We explore the dependence of the modeled lag properties on several different types of reflection models but are unable to successfully reproduce the measured lags of 4U 1728–34. We conclude that reverberation alone does not explain the measured time lags detected in upper kHz QPOs.
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

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

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

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

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

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

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

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

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

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.
A Diagnostic Roadmap for Polycythemia
Authors: Sung Hwa Jung
Published: February 2020

Polycythemia could be defined as an elevation in hemoglobin or hematocrit levels above normal. To figure out what induces polycythemia is very important since the causes of polycythemia are very variable and the approaches for the treatments are basically different. Polycythemia can be primary or secondary in origin. The secondary causes are all associated with increase in erythropoietin (EPO) levels. If serum EPO levels are elevated, one try to differentiate whether the elevation is a physiologic response to hypoxemia or is related to autonomous production. Patients with low arterial O2 saturation (< 92%) should be further evaluated for the presence of heart or lung disease. Patients without hypoxemia who are smokers may have elevated EPO levels because of CO displacement of O2. If carboxyhemoglobin levels are elevated, the diagnosis is smoker’s polycythemia. Patients without hypoxemia who do not smoke, either could be diagnosed as high oxygen affinity hemoglobinopathy or have EPO producing tumors. If EPO levels are low, the patients most likely have polycythemia vera which has almost JAK2 mutation.
Pancreatic Cancer in a Young Male in His Twenties
Authors: Baek Seung-Ho , Lee Seung Soo , Kim Ji Hoon , Kim So Hyun , Lim Jihye , Lee Joune Seup , Kim Myung-Hwan
Published: February 2020

Pancreatic cancer is one of the most lethal malignancies worldwide. The risk of developing pancreatic cancer increases with age. Pancreatic cancer is seen mostly in the elderly; patients under the age of 30 years are rare. Known risk factors for pancreatic cancer include genetic mutations, smoking, chronic pancreatitis, and diabetes mellitus. We report a case of pancreatic cancer in a 27-year-old man without the PRSS1 mutation. Chronic pancreatitis and smoking may have contributed to the development of pancreatic cancer in this patient. We also conducted a literature review on early onset pancreatic cancer.
Informational Channels of Financial Contagion
Authors: Trevino Isabel
Published: February 2020

Two main classes of channels are studied as informational sources of financial contagion. One is a fundamental channel that is based on real and financial links between economies, and the second is a social learning channel that arises when agents base their decisions on noisy observations about the actions of others in foreign markets. Using global games, I present a two‐country model of financial contagion in which both channels can operate and I test its predictions experimentally. The experimental results show that subjects do not extract information optimally, which leads to two systematic biases that affect these channels directly. Base‐rate neglect leads subjects to underweight their prior, and thus weakens the fundamental channel. An overreaction bias strengthens the social learning channel, since subjects rely on information about the behavior of others, even when this information is irrelevant. These results have significant welfare effects rooted in the specific way in which these biases alter behavior.
Investigation of the association between metabolic syndrome and breast cancer patients
Authors: Eskandari Delaram , Khodabandehloo Niloofar , Gholami Abbas , Samadanifard Hosein , Hejrati Alireza
Published: February 2020

One of the most serious cancers among women is breast cancer. This disease is the first reason for the death of women due to cancer. Increasing breast cancer risk may associate with many factors including genetic, reproductive factors, people's lifestyle, metabolic syndrome (MS) and hormones. MS has been known as a risk factor for prostate, pancreatic, breast and colorectal cancers. The purpose of this review is to identify the relationship between MS components and breast cancer individually. This study was performed by researching electronic database references including PubMed, Google Scholar, CINAHL ProQuest, and web of science through 2019. The effect of MS with its components and breast cancer was reported in many studies.Nevertheless, a thorough understanding of the mechanisms involved remains a challenge.However, one can take several preventive measures, including a proper diet, which is one of the most important determinants of metabolic status. Also, general preventive recommendations are including reducing alcohol consumption, red meat and total fat in the diet. Moreover, increasing the consumption of vegetable and fruit reduce the proportion of MS patients to improve the outcome of breast cancer patients.
A framework to benchmark the quality of clinical assessment in a South African undergraduate medical programme
Authors: Brits Hanneke , Bezuidenhout Johan , Van der Merwe Lynette J.
Published: February 2020

Background: The outcome of the undergraduate medical programme is to produce clinically competent health care providers relevant for the South African context. Educational institutions find it hard to ensure the quality of assessments where competency must be assessed. This study aimed to compile an assessment framework that can be used to benchmark current assessment practices in the clinical phase of the undergraduate medical programme where competency must be certified.Methods: In this observational, descriptive study, qualitative data were gathered using the steps described by the World Health Organization for rapid reviews. Literature was searched, screened and selected before data were analysed and a framework was constructed.Results: Twenty-five official documents were included in the study. The framework addressed the three components of quality assessment, namely, accreditation, assessment and quality assurance. Assessors should attend to the principles of assessment, namely, validity, reliability, fairness, feasibility, educational effect and acceptability, but realise that no assessment meets all these criteria. The first step to ensure quality assessment is to identify a clear outcome. Assessment should be planned and aligned with this outcome.Conclusion: It is clear that clinical assessment is multidimensional and that no assessment is perfect. Programme accreditation, assessment practices and psychometrics can assist to improve the quality of assessment but cannot judge clinical competence. Using experienced assessors with a variety of assessment methods on a continuous basis is the proposed way to assess clinical competence. An assessment framework can assist to improve assessment, but it cannot guarantee quality assessment.
Linear independence of values of $G$-functions
Authors: Fischler Stéphane , Rivoal Tanguy
Published: February 2020

Given any non-polynomial

G

-function

F(z)=\sum_{k=0}^\infty A_kz^k

of radius of convergence

R

, we consider the

G

-functions

F_n^{[s]}(z)=\sum_{k=0}^\infty \frac{A_k}{(k+n)^s}z^k

for any integers

s\ge 0

and

n\ge 1

. For any fixed algebraic number

\alpha

such that

0 < \vert \alpha\vert < R

and any number field

\mathbb K

containing

\alpha

and the

A_k

's, we define

\Phi_{\alpha, S}

as the

\mathbb K

-vector space generated by the values

F_n^{[s]}(\alpha)

,

n\ge 1

and

0\le s\le S

. We prove that

u_{\mathbb K,F}\log(S)\le \dim_\mathbb K(\Phi_{\alpha, S })\le v_FS

for any

S

, with effective constants

u_{\mathbb K,F} > 0

and

v_F > 0

, and that the family

\big(F_n^{[s]}(\alpha)\big)_{1\le n \le v_F, s\ge 0}

contains infinitely many irrational numbers. This theorem applies in particular when

F

is a hypergeometric series with rational parameters or a multiple polylogarithm, and it encompasses a previous result by the second author and Marcovecchio in the case of polylogarithms. The proof relies on an explicit construction of Padé-type approximants. It makes use of results of André, Chudnovsky and Katz on

G

-operators, of a new linear independence criterion à la Nesterenko over number fields, of singularity analysis as well as of the saddle point method.
التخطيط الاستراتيجي لهيكلة مشروعات طبية عربية مشتركة
Authors: سعيد على حسن القليطى سعيد على حسن القليطى
Published: February 2020

هذا البحث محاولة لتلمس أوجه التعاون العربي المشترك في المجال الطبي، واستجلاء الموارد العلمية والبشرية والمؤسساتية التي تتمتع بها دول العالم العربي، وتوضيح العقبات التي تحول دون تحقيق هذا التعاون المشترك. وهو محاولة للاستفادة من المقومات والإيجابيات الموجودة فعلا ولمواجهة التحديات والسلبيات التي تواجه العمل العربي المشترك، عبر اقتراح هيكل تنظيمي لمنظمة للصحة العربية تعتمد وتقود مشروعات طبية عربية مشتركة وتشرف عليها، وتعمل على التقدم بالعمل العلمي والبحثي الطبي في كافة الأقطار العربية، واعتماد التخطيط الاستراتيجي كوسيلة للوصول لمثل هذه الغايات الجليلة.
Advanced Power Transmission System
Authors: Rafea M. Abd El-Maksoud Rafea M. Abd El-Maksoud
Published: February 2020

Different researches are adopted to modify and enhance
automatic transmission by every means. Whereas, torque converter
that represents the most important component in such transmission
suffers from some problems that are not completely solved. In this
paper, power transmission system is herein introduced as a unique
power transmission system that is not affected by torque converter
problems. This power transmission operates with power splitting
concept and is composed of conventional torque converter connected
to planetary sets. Three clutches are used to shift the operating modes
and unique positive displacement hydraulic couplings are utilized to
regulate performance in power paths. Also, a modified model used to
predict torque converter performance is utilized with planetary gear
kinetics to assess the transmission performance. Moreover, the present
system operates with high performance. Unlike the automatic
transmission that operates in line, the present system operates with
infinity number of operational bands for each engine speed.
[Technical Note]
Purely-Algebraic versus VEKM Methods for Solving Big
Boolean Equations
Authors: Ali Muhammad Ali Rushdi Ali Muhammad Ali Rushdi
Published: February 2020

Manual methods of solving big Boolean equations include
purely-algebraic methods and methods utilizing the variable-entered
Karnaugh map (VEKM). The VEKM techniques are demonstrated to
be at least competitive with (and occasionally superior to) purelyalgebraic techniques, since the VEKM techniques (a) include purelyalgebraic methods as special cases, and (b) have a better control on the
minimality of the pertinent function representations, and hence are
more capable of producing more compact general solutions.
Comparative Study of Change Detection and Urban
Expansion Using Multi-Date Multi-Source Data: A Case
Study of Greater Khartoum
Authors: Abdullah Salman Alsalman Abdullah Salman Alsalman
Published: February 2020

Noting that Khartoum represents the most rapidly expanding
city in the Sudan and taking into account that change detection
operations are seldom , the present study has been initiated to
attempt to produce work that synthesizes land use/land cover (LULC)
to investigate change detection using GIS, remote sensing data and
digital image processing techniques; estimate, evaluate and map
changes that took place in the city from 1975 to 2003. The experiment
used the techniques of visual inspection, write-function-memoryinsertion, image differencing, image transformation i.e. normalized
difference vegetation index (NDVI), tasseled cap, principal
component analysis (PCA), post-classification comparison and GIS.
The results of all these various techniques were used by the authors to
study change detection of the geographic locale of the test area. Image
processing and GIS techniques were performed using Intergraph
Image analyst 8.4 and GeoMedia professional version 6, ERDAS
Imagine 8.7, and ArcGIS 9.2. Results obtained were discussed and
analyzed in a comparative manner and a conclusion regarding the best
method for change detection of the test area was derived.
A Survey of Access Control and Data Encryption for Database Security
Authors: Emad F. Khalaf Emad F. Khalaf
Published: February 2020

With the vast amount of data generated nowadays, organizing and managing of these data are very important to allow the
users to access, retrieve, and update their data by using database systems (DBS). Most of the current organizations use DBS to
increase the efficiency and the productivity of their organizations, but the security threats are becoming more dangerous to the DB.
So, protection of data by keeping it integrated and secured from any undesirable intrusion became the highest priority for these
organizations. DB security provides various techniques to protect data from any threats. This paper discusses two techniques used in
the DB field to achieve integrity and confidentiality of the data, by using access control policies and data encryption.
An Application of Lean Manufacturing Techniques in Paint Manufacturing
Company: A Case Study
Authors: Ahmed M. Badeeb Ahmed M. Badeeb
Published: February 2020

As a result of the recession in Saudi Arabia, the manufacturing companies start thinking
to reduce the operational cost and increasing the productivity through lean manufacturing
principles. This paper is focused on increasing the productivity of a paint manufacturing company
through implementing some of the lean manufacturing techniques. First, Value stream mapping
analysis carried on throughout the manufacturing process and the areas of improvements in the
company has been identified using fishbone diagram. Second, Work Place Organization (5S),
Single Minute Exchange of Dies (SMED), Work Standardization and Kanban are the lean
manufacturing techniques selected to solve different problems facing the company in these areas
of improvements. A systematic approach of each technique implemented to measure its effect on
the company productivity. It is observed that, applying (5S) and (SMED) techniques in the filling
process decreased the changeover time by 59% and increased the daily productivity. Pareto chart
recommended using work standardization in the charging process led to reduce the defects
batches by 57%. Kanban system eliminated the shortages of semi-finish product and increased the
output of the pre-weighing batches by 57%. In addition, overtime hours reduced by 77% and
waste handling reduced by 85% and 53% for the non-hazardous and hazardous waste
respectively
Simultaneous Measurement of Urban and Rural Particles in Beijing, Part II: Case Studies of Haze Events and Regional Transport
Authors: Chen Yang , Shi Guangming , Cai Jing , Shi Zongbo , Wang Zhichao , Yao Xiaojiang , Tian Mi , Peng Chao , Han Yiqun , Zhu Tong , Liu Yue , Yang Xi , Zheng Mei , Yang Fumo , He Kebin
Published: February 2020

Abstract. Two parallel field studies were conducted simultaneously at both urban and rural sites in Beijing from 11/01/2016 to 11/29/2016. Online single-particle chemical composition analysis was used as a tracer system to investigate the impact of heating activities and the formation of haze events. Central heating elevated EC-Nit, EC-Nit-Sul, and ECOC-Nit levels by 1.5–2.0 times due to the increased use of coal in the urban areas. However, in the rural areas, residential heating which mainly consumes low-quality coal and biomass burning elevated ECOC-Nit-Sul, Nak-Nit, and OC-Sul levels by 1.2–1.5 times. Four severe haze events (hourly PM2.5 > 200 µg m−3) occurred at both sites during the studies. In each event, a pattern of transport and accumulation was found. In the first stage, particles were regionally transported from the south or southwest and accumulated under air stagnations, creating the significant secondary formation. Consequently, the boosting of PM2.5 led to severe haze. At both sites, the severe haze occurred due to different patterns of local emission, transport, and secondary processes. At PG, the sulfate-rich residential coal burning particles were dominant. The regional transport between PG and PKU was simulated using the WRF-HYSPLIT model, confirming that the transport from PG to PKU was significant, but PKU to PG occurred occasionally. These cases can explain the serious air pollution in the urban areas of Beijing and the interaction between urban and rural areas. This study can provide references for enhancing our understanding of haze formation in Beijing.