bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cold, Old, and Metal-poor: New Stellar Substructures in the Milky Way’s Dwarf Spheroidals
Authors: Lora V. , Grebel E. K. , Schmeja S. , Koch A. 
Published: June 2019

Abstract
Dwarf spheroidal galaxies (dSph) orbiting the Milky Way are complex objects often with complicated star formation histories and internal dynamics. In this work, we search for stellar substructures in four of the classical dSph satellites of the Milky Way: Sextans, Carina, Leo I, and Leo II. We apply two methods to search for stellar substructure: the minimum spanning tree method, which helps us find and quantify spatially connected structures, and the “brute-force” method, which is able to find elongated stellar substructures. We detected the previously known substructure in Sextans and also found a new stellar substructure within Sextans. Furthermore, we identified a new stellar substructure close to the core radius of the Carina dwarf galaxy. We report a detection of one substructure in Leo I and two in Leo II, but we note that we are dealing with a low number of stars in the samples used. Such old stellar substructures in dSphs could help us shed light on the nature of the dark matter halos, within which such structures form, evolve, and survive.
The Apache Point Observatory Catalog of Optical Diffuse Interstellar Bands
Authors: Fan Haoyu , Hobbs L. M. , Dahlstrom Julie A. , Welty Daniel E. , York Donald G. , Rachford Brian , Snow Theodore P. , Sonnentrucker Paule , Baskes Noah , Zhao Gang 
Published: June 2019

Abstract
Aiming for a new and more comprehensive DIB catalog between 4000 and 9000 Å, we revisited the Atlas Catalog based on the observations of HD 183143 and HD 204827. Twenty-five medium to highly reddened sight lines were selected, sampling a variety of spectral types of the background star and the interstellar environments. The median signal-to-noise ratio (S/N) of these spectra is ∼1300 around 6400 Å. Compared to the Atlas Catalog, 22 new DIBs were found, and the boundaries of 27 (sets of) DIBs were adjusted, resulting in an updated catalog containing 559 DIBs that we refer to as the Apache Point Observatory Catalog of Optical Diffuse Interstellar Bands. Measurements were then made based on this catalog. We found our survey most sensitive between 5500 and 7000 Å, due largely to the local S/N of the spectra, the relative absence of interfering stellar lines, and the weakness of telluric residuals. For our data sample, the number of DIBs detected in a given sight line is mostly dependent on E

B−V
and less on the spectral type of the background star. Some dependence on the molecular fraction f
H2 is observed, but it is less well determined owing to the limited size of the data sample. The variations of the wavelengths of each DIB in different sight lines are generally larger than those of the known interstellar lines CH+, CH, and K i. Those variations could be due to the inherent error in the measurement, or to differences in the velocity components among sight lines.
Radio Emission from Pulsars due to Relativistic Plasma
Authors: Roy Tridib , Gangadhara R. T. 
Published: June 2019

Abstract
Pulsar radio emission is not well understood because of a lack of knowledge about the emission geometry and the plasma process involved. We develop a mechanism for pulsar radio emission that takes into account the detailed viewing geometry of pulsars and the dipolar magnetic field configuration. Using a suitably chosen geometry and plasma parameters, we derive analytical expressions for the Stokes parameters of the radiation field in the frame centered on the neutron star. We have simulated pulse profiles based on our analytical formulation. It seems that we can explain the enhanced radiation and most of the diverse polarization properties of radio pulsars. We have estimated the brightness temperature, which seems to agree with the observations. The polarization angle predicted by the model is in good agreement with the rotating vector model.
NICER Observation of Unusual Burst Oscillations in 4U 1728-34
Authors: Mahmoodifar Simin , Strohmayer Tod E. , Bult Peter , Altamirano Diego , Arzoumanian Zaven , Chakrabarty Deepto , Gendreau Keith C. , Guillot Sebastien , Homan Jeroen , Jaisawal Gaurava K. , Keek Laurens , Wolff Michael T. 
Published: June 2019

Abstract
The Neutron Star Interior Composition Explorer has observed seven thermonuclear X-ray bursts from the low-mass X-ray binary neutron star 4U 1728−34 from the start of the mission’s operations until 2019 February. Three of these bursts show oscillations in their decaying tail, with frequencies that are within 1 Hz of the previously detected burst oscillations from this source. Two of these burst oscillations have unusual properties: they have large fractional root mean square (rms) amplitudes of 48% ± 9% and 46% ± 9%, and they are detected only at photon energies above 6 keV. By contrast, the third detected burst oscillation is compatible with previous observations of this source, with a fractional rms amplitude of 7.7% ± 1.5% rms in the 0.3 to 6.2 keV energy band. We discuss the implications of these large-amplitude burst oscillations, finding that they are difficult to explain with the current theoretical models for X-ray burst tail oscillations.
Acceleration of Solar Wind Particles by Traveling Interplanetary Shocks
Authors: Prinsloo P. L. , Strauss R. D. , le Roux J. A. 
Published: June 2019

Abstract
The acceleration of thermal solar wind (SW) protons at spherical interplanetary shocks driven by coronal mass ejections is investigated. The SW velocity distribution is represented using κ-functions, which are transformed in response to simulated shock transitions in the fixed-frame flow speed, plasma number density, and temperature. These heated SW distributions are specified as source spectra at the shock from which particles with sufficient energy can be injected into the diffusive shock acceleration process. It is shown that for shock-accelerated spectra to display the classically expected power-law indices associated with the compression ratio, diffusion length scales must exceed the width of the compression region. The maximum attainable energies of shock-accelerated spectra are found to be limited by the transit times of interplanetary shocks, while spectra may be accelerated to higher energies in the presence of higher levels of magnetic turbulence or at faster-moving shocks. Indeed, simulations suggest that fast-moving shocks are more likely to produce very high energy particles, while strong shocks, associated with harder shock-accelerated spectra, are linked to higher intensities of energetic particles. The prior heating of the SW distribution is found to complement shock acceleration in reproducing the intensities of typical energetic storm particle (ESP) events, especially where injection energies are high. Moreover, simulations of ∼0.2–1 MeV proton intensities are presented that naturally reproduce the observed flat energy spectra prior to shock passages. Energetic particles accelerated from the SW, aided by its prior heating, are shown to contribute substantially to intensities during ESP events.
On the Origin of Star–Gas Counterrotation in Low-mass Galaxies
Authors: Starkenburg Tjitske K. , Sales Laura. V. , Genel Shy , Manzano-King Christina , Canalizo Gabriela , Hernquist Lars 
Published: June 2019

Abstract
Stars in galaxies form from the cold rotationally supported gaseous disks that settle at the center of dark matter halos. In the simplest models, such angular momentum is acquired early on at the time of collapse of the halo and preserved thereafter, implying a well-aligned spin for the stellar and gaseous component. Observations, however, have shown the presence of gaseous disks in counterrotation with the stars. We use the Illustris numerical simulations to study the origin of such counterrotation in low-mass galaxies (M
⋆ = 2 × 109–5 × 1010
M
⊙), a sample where mergers have not played a significant role. Only ∼1% of our sample shows a counterrotating gaseous disk at z = 0. These counterrotating disks arise in galaxies that have had a significant episode of gas removal followed by the acquisition of new gas with misaligned angular momentum. In our simulations, we identify two main channels responsible for the gas loss: a strong feedback burst and gas stripping during a flyby passage through a more massive group environment. Once settled, counterrotation can be long-lived with several galaxies in our sample displaying misaligned components consistently for more than 2 Gyr. As a result, no major correlation with the present-day environment or structural properties might remain, except for a slight preference for early-type morphologies and a lower than average gas content at a given stellar mass.
Black Hole Hyperaccretion in Collapsars. I. MeV Neutrinos
Authors: Wei Yun-Feng , Liu Tong , Song Cui-Ying 
Published: June 2019

Abstract
As the plausible central engine of gamma-ray bursts, a black hole (BH) hyperaccretion disk should be in a state of neutrino-dominated accretion flow (NDAF) if the accretion rate is larger than the ignition rate of an NDAF. A rotating stellar-mass BH surrounded by a hyperaccretion disk might be born in the center of a massive core collapsar. In the initial hundreds of seconds of the accretion process, the mass supply rate of the massive progenitor is generally higher than the ignition accretion rate, but the jets are generally choked in the envelope. Thus, neutrinos can be emitted from the center of a core collapsar. In this paper, we study the effects of the masses and metallicities of progenitor stars on the time-integrated spectra of electron neutrinos from NDAFs. The peak energies of the calculated spectra are approximately 10–20 MeV. The mass of a collapsar has little influence on the neutrino spectrum, and a low metallicity is beneficial to the production of low-energy (≲1 MeV) neutrinos. We also investigate the differences in the electron neutrino spectra between NDAFs and proto-neutron stars. Combining with the electromagnetic counterparts and multimessenger astronomy, one may verify the possible remnants of the core collapse of massive stars with future neutrino detectors.
Proton Perpendicular Heating by Kinetic Alfvén Waves
Authors: Choi Cheong R. , Woo M.-H. , Yoon Peter H. , Shin D.-K. , Lee D.-Y. , Park K. S. 
Published: June 2019

Abstract
The preferential heating of protons in the perpendicular direction with respect to the ambient magnetic field is a well-known phenomenon in the solar corona. One of the physical mechanisms proposed to explain such a feature is the nonresonant wave–particle interaction between protons and kinetic Alfvén waves. The present paper examines this mechanism by employing a novel analytical method based upon the Hamiltonian dynamical test particle approach. The analytical nature of the present method reveals an interesting fact that the pure inductive component of parallel electric field associated with the kinetic Alfvén wave in the limit Ti/Te
≪ 1 has little contribution. The parallel and perpendicular diffusion of protons by kinetic Alfvén waves is investigated through computing the autocorrelation function. The calculations unambiguously demonstrate that the proton heating is achieved mainly by nonresonant wave–particle interaction involving the wave magnetic field, and that the effects of the parallel electric field are minimal. It is also found that the perpendicular diffusion is orders of magnitude stronger than parallel diffusion, implying effective perpendicular heating.
Inverse Compton Scattering of Starlight in the Kiloparsec-scale Jet in Centaurus A: The Origin of Excess TeV γ-Ray Emission
Authors: Tanada K. , Kataoka J. , Inoue Y. 
Published: June 2019

Abstract
Centaurus A (Cen A) is the nearest active radio galaxy, which has kiloparsec-scale jets and giant lobes detected by various instruments in radio and X-ray frequency ranges. The Fermi-Large Area Telescope and High Energy Stereoscopic System (HESS) confirmed that Cen A is a very high-energy (VHE; >0.1 TeV) γ-ray emitter with a known spectral softening in the energy range from a few GeV to TeV. In this work, we consider a synchrotron self-Compton model in the nucleus for the broadband spectrum below the break energy and an external Compton model in kiloparsec-scale jets for the γ-ray excess. Our results show that the observed γ-ray excess can be suitably described by the inverse Compton scattering of the starlight photons in the kiloparsec-scale jets, which is consistent with the recent tentative report by HESS on the spatial extension of the TeV emission along the jets. Considering the spectral fitting results, the excess can only be seen in Cen A, which is probably due to two factors: (1) the host galaxy is approximately 50 times more luminous than other typical radio galaxies and (2) the core γ-ray spectrum quickly decays above a few MeV due to the low maximum electron Lorentz factor of γ
c = 2.8 × 103 resulting from the large magnetic field of 3.8 G in the core. By the comparison with other γ-ray detected radio galaxies, we found that the magnetic field strength of relativistic jets scales with the distance from the central black holes d with B(d) ∝ d
−0.88 ± 0.14.
State Resolved Data for Quadrupole Radiative Association of H+H and Dissociation of H2 through Orbiting Resonances
Authors: Pérez K. D. , Arce J. C. , López J. G. 
Published: June 2019

Abstract
We propose a reassessment of quadrupole radiative association and dissociation for the formation, destruction, and detection of molecular hydrogen in the early universe and in very cold molecular clouds by taking into account orbiting (shape) resonances. We provide accurate data needed for the modeling of this mechanism—namely, the energies and lifetimes of all the orbiting resonances up to J = 30 in the ground electronic state (

) and the energies and quadrupole matrix elements for all the associated resonance–resonance and resonance-bound rovibrational transitions.
Vitreous Biopsy Under Air: Technique, Complications, and Volume Outcomes
Authors: Zhao Meng , Yu Yajie , Liu Wu 
Published: June 2019

BACKGROUND AND OBJECTIVE:
Classic vitreous biopsy, which targets the vitreous with an undiluted sample of 1 mL to 2 mL, has been used as a diagnostic analysis. Vitrectomy under air infusions have been reported to be able to extract more vitreous sample. In this study, the authors introduce a way of obtaining vitreous sample under air irrigation using 23-gauge vitrectomy and discuss the benefits and potential risks of this procedure.

PATIENTS AND METHODS:
In this retrospective case series study, a total of 65 eyes of 65 patients with macular epiretinal membrane (ERM) or macular hole (MH) were enrolled. A vitreous biopsy was carried out with air infusion. Vitrectomy with fluid infusion was then carried out to remove the residual vitreous. Medical records of patients with macular ERM or MH were reviewed and analyzed. Clinical data, including age, sex, best-corrected visual acuity (BCVA), optical coherence tomography (OCT), axial length, presence of posterior vitreous detachment (PVD), presence of liquefication of vitreous, and refraction, were recorded and investigated. The volume of vitreous sample, visual outcome, and complications related to vitreous biopsy at 1-month follow-up were recorded and analyzed.

RESULTS:
The mean of undiluted vitreous sample volume was 2.1 mL ± 0.2 mL. There were seven patients whose vitreous samples were less than 2 mL during the vitreous biopsy. The mean age of patients was 62.9 years ± 8.4 years (range: 35 years to 85 years) at diagnosis. There were 18 male and 47 female patients. At 1-month follow-up, no patient had decreased visual acuity. There was one patient who had a peripheral retinal break and was treated with photocoagulation during the operation (1.5%). The insufficient vitreous sample that may occur during the vitreous biopsy under air infusion was related to liquefication of vitreous (28.8%).

CONCLUSION:
In summary, vitreous biopsy with air infusion is a safe and effective maneuver to harvest undiluted vitreous in patients without significant vitreous inflammation.

[
Ophthalmic Surg Lasers Imaging Retina
. 2019;50:365–370.]
‘Nós’ e ‘a gente’: diferenças de uso nas variedades de português
Authors: Silva Josany Maria de Jesus , Namiuti Cristiane 
Published: June 2019

A primeira pessoa plural (1PP) no paradigma pronominal do Português Brasileiro (PB) e do Português Europeu (PE) pode ser realizada como a forma pronominal ‘nós’ ou como a forma pronominal ‘a gente’. Esta variação tem sido um lugar de investigação para buscar identificar as convergências e divergências das variedades da língua portuguesa. Apresentaremos, neste artigo, um recorte da investigação sobre o uso dos pronomes em amostras de fala de PB e de PE. Observamos que, no PE, o uso de ‘nós’ acontece junto de verbos flexionados na primeira pessoa do plural, quarta pessoa do discurso (P4), já em variedades do PB, o uso do mesmo pronome acontece também, e preferencialmente, com verbos na terceira pessoa do singular, terceira pessoa do discurso (P3) e é utilizado na função de objeto direto e indireto, função não desempenhada pelo pronome no PE que utiliza o pronome clítico ‘nos’ para realizar as funções acusativas e dativas. Outra diferença está no uso do pronome ‘a gente’ com verbos em P4, que foi de 24% no PE, enquanto no PB foi atestado uso apenas de 4%. Verificamos também que o tempo verbal mostrou ser um fator importante na preservação da morfologia P4 em PB, comprovando a hipótese de Vieira (2014) de que o presente e o pretérito perfeito do modo indicativo favorecem a presença do morfema de primeira pessoa plural (MOS) no PB, por possuir um paradigma flexional que amalgama as noções de tempo, modo, aspecto, pessoa e número.
TCR Affinity for In Vivo Peptide-Induced Thymic Positive Selection Fine-Tunes TCR Responsiveness of Peripheral CD8+ T Cells
Authors: Khanom Umme Shahina , Ohigashi Izumi , Fujimori Sayumi , Kondo Kenta , Takada Kensuke , Takahama Yousuke 
Published: June 2019

Abstract
The affinity for TCR interactions with self-peptide/MHC complexes (pMHC) in the thymus critically affects immature thymocytes that newly express TCRs. Previous fetal thymus organ culture experiments have indicated that difference in the affinity for thymic TCR/pMHC interactions not only determines thymocyte fate between positive and negative selection, but also affects Ag responsiveness of positively selected thymocytes. In the current study, we examined whether TCR/pMHC affinity during positive selection in the thymus would further affect Ag responsiveness of mature T cells in the periphery. To do so, OVA peptide variants were in vivo administered to TAP1-deficient OT-I/TCR-transgenic mice in which T cell development was otherwise arrested at CD4+CD8+ thymocytes because of the lack of self-pMHC presentation in thymic APCs. We found that a group of peptide variants induced the transient generation of OT-I CD8+ T cells in the thymus and the periphery. We also noticed that the affinity threshold for positive and negative selection detected in adult mice in vivo was higher than that measured in fetal thymus organ culture experiments in vitro. Interestingly, we further found that the affinity for positively selecting peptides proportionally affected TCR responsiveness of peripheral naive CD8+ T cells. These results indicate that in vivo administration of a peptide can promote T cell selection in the thymus and the affinity for TCR/pMHC interaction during positive selection fine-tunes Ag responsiveness of peripheral T cells.
Expanding healthcare coverage
Authors: Khetrapal Sonalini , Acharya Arnab 
Published: June 2019

Background & objectives:
Given that Ayushman Bharat Yojna was launched in 2018 in India, analysis of Rashtriya Swasthya Bima Yojna (RSBY) become relevant. The objective of this study was to examine the scheme design and the incentive structure under RSBY.

Methods:
The study was conducted in the districts of Patiala and Yamunanagar in the States of Punjab and Haryana, respectively (2011-2013). The mixed method study involved review of key documents; 20 in-depth interviews of key stakeholders; 399 exit interviews of RSBY and non-RSBY beneficiaries in Patiala and 353 in Yamunanagar from 12 selected RSBY empanelled hospitals; and analysis of secondary databases from State nodal agencies and district medical officers.

Results:
Insurance companies had considerable implementation responsibilities which led to conflict of interest in enrolment and empanelment. Enrolment was 15 per cent in Patiala and 42 per cent in Yamunanagar. Empanelment of health facilities was 17 (15%) in Patiala and 37 (30%) in Yamunanagar. Private-empanelled facilities were geographically clustered in the urban parts of the sub-districts. Monitoring was weak and led to breach of contracts. RSBY beneficiaries incurred out-of-pocket (OOP) expenditures (5748); however, it was lower than that for non-RSBY (10667). The scheme had in-built incentives for Centre, State, insurance companies and health providers (both public and private). There were no incentives for health staff for additional RSBY activities.

Interpretation & conclusions:
RSBY has in-built incentives for all stakeholders. Some of the gaps identified in the scheme design pertained to poor enrolment practices, distribution of roles and responsibilities, fixed package rates, weak monitoring and supervision, and incurring OOP expenditure.
Racial disparities in incidence & survival of Kaposi's sarcoma in the United States
Authors: Kumar Vivek , Soni Parita , Garg Mohit , Hashmi Arsalan Talib , Chandra Abhinav Binod 
Published: June 2019

Background & objectives:
In the United States (US), Kaposi's sarcoma (KS) is usually seen in the patients affected by human immunodeficiency virus (HIV). The racial differences in the incidence rates and survival of patients with KS have been reported in the US. We undertook this study to analyse the disparities in the race-specific incidence rate and survival of KS patients of two different races in the US based on SEER (Surveillance, Epidemiology and End Results) database.

Methods:
Data on KS patients of African-American (AA) and non-Hispanic White (NHW) races who were diagnosed during 1973-2013 were extracted from SEER database to estimate the incidence rates and survival of KS patients.

Results:
A total of 18,388 NHWs and 3,455 AAs were diagnosed with KS. The age-adjusted incidence rate (AAIR) of KS in patients aged 20-44 yr was 3.8 times higher in AAs than in NHWs. The decline in AAIR of KS among NHWs started during 1989-1994 and preceded decline in the AAIR of AAs. After introduction of highly active antiretroviral therapy (HAART), the incidence continued to decline, but the decrease in the AAIR in AAs [annual percentage change (APC): −6.2; 95% confidence interval (CI): −8.8 to −3.5] was slower than that in NHWs (APC: −10.9; 95% CI: −12.6 to −9.1). The hazard ratio for all-cause mortality in KS patients of the AA race increased from 1.1 (95% CI: 1-1.2) in 1981-1995 to 1.55 (95% CI: 1.4-1.7) in 1996-2013 as compared to those of the NHW race.

Interpretation & conclusions:
Several significant racial disparities that emerged after HAART introduction in the incidence and survival of KS patients continued to persist, despite improvement in care of patients with HIV. Further studies need to be done to find out the underlying factors leading to these disparities.