bluuebunny/crossref_metadata_2025_split huggingface dataset:
Onset of superconductivity and retention of magnetic fields in cooling neutron stars
Authors: Ho Wynn C. G. , Andersson Nils , Graber Vanessa 
Published: June 2018

AbstractA superconductor of paired protons is thought to form in the core of neutron stars soon after their birth. Minimum energy conditions suggest that magnetic flux is expelled from the superconducting region due to the Meissner effect, such that the neutron star core retains or is largely devoid of magnetic fields for some nuclear equation of state and proton pairing models. We show via neutron star cooling simulations that the superconducting region expands faster than flux is expected to be expelled because cooling timescales are much shorter than timescales of magnetic field diffusion. Thus magnetic fields remain in the bulk of the neutron star core for at least 106 − 107yr. We estimate the size of flux free regions at 107yr to be ≲ 100m for a magnetic field of 1011G and possibly smaller for stronger field strengths.
Solar System Ephemerides, Pulsar Timing, Gravitational Waves, & Navigation
Authors: Lazio T. Joseph W. , Bhaskaran S. , Cutler C. , Folkner W. M. , Park R. S. , Ellis J. A. , Ely T. , Taylor S. R. , Vallisneri M. 
Published: June 2018

AbstractIn-spiraling supermassive black holes should emit gravitational waves, which would produce characteristic distortions in the time of arrival residuals from millisecond pulsars. Multiple national and regional consortia have constructed pulsar timing arrays by precise timing of different sets of millisecond pulsars. An essential aspect of precision timing is the transfer of the times of arrival to a (quasi-)inertial frame, conventionally the solar system barycenter. The barycenter is determined from the knowledge of the planetary masses and orbits, which has been refined over the past 50 years by multiple spacecraft. Within the North American Nanohertz Observatory for Gravitational Waves (NANOGrav), uncertainties on the solar system barycenter are emerging as an important element of the NANOGrav noise budget. We describe what is known about the solar system barycenter, touch upon how uncertainties in it affect gravitational wave studies with pulsar timing arrays, and consider future trends in spacecraft navigation.
Solar-System Studies with Pulsar Timing Arrays
Authors: Caballero R. N. ,   Collaborators
Published: June 2018

AbstractHigh-precision pulsar timing is central to a wide range of astrophysics and fundamental physics applications. When timing an ensemble of millisecond pulsars in different sky positions, known as a pulsar timing array (PTA), one can search for ultra-low-frequency gravitational waves (GWs) through the spatial correlations that spacetime deformations by passing GWs are predicted to induce on the pulses’ times-of-arrival (TOAs). A pulsar-timing model, requires the use of a solar-system ephemeris (SSE) to properly predict the position of the solar-system barycentre, the (quasi-)inertial frame where all TOAs are referred. Here, I discuss how while errors in SSEs can introduce correlations in the TOAs that may interfere with GW searches, one can make use of PTAs to study the solar system. I discuss work done within the context of the European Pulsar Timing Array and the International Pulsar Timing Array collaborations. These include new updates on the masses of planets from PTA data, first limits on masses of the most massive asteroids, and comparisons between SSEs from independent groups. Finally, I discuss a new approach in setting limits on the masses of unknown bodies in the solar system and calculate mass sensitivity curves for PTA data.
Optical pulsars and polarimetry
Authors: Shearer Andrew , Connor Eoin O’ 
Published: June 2018

AbstractDespite the early optical detection of the Crab pulsar in 1969, optical pulsars have become the poor cousin of the neutron star family. Only five normal pulsars have been observed to pulse in the optical waveband. A further three magnetars/SGRs have been detected in the optical/near IR. Optical pulsars are intrinsically faint with a first order luminosity, predicted by Pacini, to be proportional to P−10, where P is the pulsar’s period. Consequently they require both large telescopes, generally over-subscribed, and long exposure times, generally difficult to get. However optical observations have the benefit that polarisation and spectral observations are possible compared to X-ray and gamma-ray observations where polarisation measurements are limited. Over the next decade the number of optical pulsars should increase as optical detectors approach 100% quantum efficiency and as we move into the era of extremely large telescopes where limiting fluxes will be 30 to 100 times fainter compared to existing optical telescopes.
Evolution of the low-frequency pulse profile of PSR B2217+47
Authors: Michilli D. , Hessels J. W. T. , Donner J. Y. , Grießmeier J.-M. , Serylak M. , Shaw B. , Stappers B. W. , Verbiest J. P. W. , Deller A. T. , Driessen L. N. , Stinebring D. R. , Bondonneau L. , Geyer M. , Hoeft M. , Karastergiou A. , Kramer M. , Osłowski S. , Pilia M. , Sanidas S. , Weltevrede P. 
Published: June 2018

AbstractAn evolution of the low-frequency pulse profile of PSR B2217+47 is observed during a six-year observing campaign with the LOFAR telescope at 150 MHz. The evolution is manifested as a new component in the profile trailing the main peak. The leading part of the profile, including a newly-observed weak component, is steady during the campaign. The transient component is not visible in simultaneous observations at 1500 MHz using the Lovell telescope, implying a chromatic effect. A variation in the dispersion measure of the source is detected in the same timespan. Precession of the pulsar and changes in the magnetosphere are investigated to explain the profile evolution. However, the listed properties favour a model based on turbulence in the interstellar medium (ISM). This interpretation is confirmed by a strong correlation between the intensity of the transient component and main peak in single pulses. Since PSR B2217+47 is the fourth brightest pulsar visible to LOFAR, we speculate that ISM-induced pulse profile evolution might be relatively common but subtle and that SKA-Low will detect many similar examples. In this scenario, similar studies of pulse profile evolution could be used in parallel with scintillation arcs to characterize the properties of the ISM.
LOFAR observations of the mode-switching pulsar B0943+10
Authors: Bilous Anna V. 
Published: June 2018

AbstractPSR B0943+10 is an old non-recycled pulsar which for decades has been mostly known for its rapid and spontaneous radio mode switching. Recently, Hermsen et al. (2013) discovered correlated changes in the thermal X-ray emission from the polar cap, thus demonstrating that radio modes are not just a product of the local changes in the radio emission region, but a sign of some global magnetospheric transformation. At about the same time, owing to the commissioning of the new generation of low-frequency radio arrays, the broadband observations at the lowest edge of ionospheric transparency window became available. At these radio frequencies profile morphology and the single-pulse properties of PSR B0943+10’s emission become very dynamic, providing details not only about the emission itself, but also about the conditions in the polar gap. Here, I will present the recent results of the LOFAR observations of PSR B0943+10 and discuss their contribution to the multiwavelength picture.
A decade of transitional millisecond pulsars
Authors: Jaodand Amruta , Hessels Jason W. T. , Archibald Anne 
Published: June 2018

AbstractTransitional millisecond pulsars (tMSPs), which are systems that harbor a pulsar in the throes of the recycling process, have emerged as a new source class since the discovery of the first such system a decade ago. These systems switch between accretion-powered low-mass X-ray binary (LMXB) and rotation-powered radio millisecond pulsar (RMSP) states, and provide exciting avenues to understand the physical processes that spin-up neutron stars to millisecond periods. During the last decade, three tMSPs, as well as a candidate source, have been extensively probed using systematic, multi-wavelength campaigns. Here we review the observational highlights from these campaigns and our general understanding of tMSPs.
The Future of Pulsar Research and Facilities
Authors: Bailes Matthew 
Published: June 2018

AbstractRadio pulsars have been responsible for many astonishing astrophysical and fundamental physics breakthroughs since their discovery 50 years ago. In this review I will discuss many of the highlights, most of which were only possible because of the provision of large-scale observing facilities. The next 50 years of pulsar astronomy can be very bright, but only if our governments properly plan and fund the infrastructure necessary to enable future discoveries. Being a small sub-field of astronomy places an onus on the pulsar community to have an open-source/open access approach to data, software, and major observing facilities to enable new groups to emerge to keep the field vibrant.
Willingness to pay for improved public health care services in Saudi Arabia: a contingent valuation study among heads of Saudi households
Authors: Al-Hanawi Mohammed K. , Alsharqi Omar , Vaidya Kirit 
Published: June 2018

AbstractThe bulk of health care service provision in Saudi Arabia is undertaken by the public health care sector through the Ministry of Health, which is funded annually by the total government budget, which, in turn, is derived primarily from oil revenue. Public health care services in Saudi Arabia are characterised by an overload, overuse, and shortage of medical personnel, which can result in dissatisfaction with the quality of the current public health care services. This study uses a contingent valuation method to investigate the willingness of Saudi people to pay for improvements to the quality of public health care services. This study also determines the association between the willingness to pay for quality improvements and respondents’ demographic and socioeconomic characteristics. A pre-tested interviewer-administered questionnaire was used to collect data from 1187 heads of household in Jeddah Province over a five-month period. Multi-stage sampling was employed to recruit participants. Partial Tobit regression and corresponding marginal effects analyses were used to analyse the data. These empirical analyses show that the majority of the sample was willing to pay for quality improvements in the public health care services. The results of this study might be of use to policymakers to help with both priority setting and fund allocation.
A Comparative Study of ULF Waves' Role in the Dynamics of Charged Particles in the Plasmasphere: Van Allen Probes Observation
Authors: Ren Jie , Zong Q. G. , Miyoshi Y. , Rankin R. , Spence H. E. , Funsten H. O. , Wygant J. R. , Kletzing C. A. 
Published: June 2018

AbstractBy analyzing observations from Van Allen Probes in its inbound and outbound orbits, we present evidence of coherent enhancement of cold plasmaspheric electrons and ions due to drift‐bounce resonance with ultralow frequency (ULF) waves. From 18:00 UT on 28 May 2017 to 10:00 UT on 29 May 2017, newly formed poloidal mode standing ULF waves with significant electric field oscillations were observed in two consecutive orbits when Probe B was traveling inbound. In contrast to observations during outbound orbits, the cold (<150 eV) electrons measured by the HOPE instrument were characterized by flux enhancements several times larger and bidirectional pitch angle distributions during inbound orbits. The electron number density inferred from upper hybrid waves is twice as larger as during inbound orbits, which were also confirmed by an increase of spacecraft potential. The observed ULF waves are identified as second harmonic modes that satisfy the drift‐bounce resonant condition of N = 1 with cold electrons. An enhancement of the plasmaspheric ion number density to restore charge neutrality of plasmas in inbound orbits is observed, which is associated with an increase of ULF wave periods. The observations suggest that the dynamics of plasmaspheric electrons is modified by ULF waves through drift‐bounce resonance and that plasmaspheric ions are indirectly impacted.
The Martian Magnetosphere: Areas of Unsettled Terminology
Authors: Espley Jared R. 
Published: June 2018

AbstractThe near‐Mars space environment has a number of regions and boundaries that have numerous and confusing labels. The whole region is sometimes referred to as the induced Martian magnetosphere and sometimes as the solar wind interaction with Mars. The middle boundary where the shocked solar wind plasma gives way to predominately planetary‐derived plasma has a variety of names. The region below that middle boundary and the top of the ionosphere also does not have a uniformly used name. There are several other regions and boundaries that also have naming confusion. The various terms that are currently used in the literature for these subjects are identified and discussed; regions and boundaries that have well‐settled names are not discussed nor are the details of the physics involved.
EISCAT Observation of Wave‐Like Fluctuations in Vertical Velocity of Polar Mesospheric Summer Echoes Associated With a Geomagnetic Disturbance
Authors: Lee Young‐Sook , Kim Yong Ha , Kim Kyung‐Chan , Kwak Young‐Sil , Sergienko Timothy , Kirkwood Sheila , Johnsen Magnar G. 
Published: June 2018

AbstractBy analyzing a data set from the European Incoherent SCATter (EISCAT) Very High Frequency (VHF) radar at Tromsø, we find that both radar reflectivity and upward ion velocity in a polar mesospheric summer echo (PMSE) layer simultaneously increased at the commencement of a local geomagnetic disturbance, which occurred at midnight on 9 July 2013. The onset of the upward velocity was followed by periodic repetition of ~5 min during the initial 30‐min stage, and then at later stage the vertical velocity oscillated with ~7‐ and ~20‐min periodicities at 85‐ to 90‐km altitudes. The ~5‐min periodicity is close to the buoyancy period, and the ~7‐ and ~20 min periodicities are consistent with gravity waves, thus suggesting that gravity waves can be generated by the effects of the geomagnetic disturbance. On the other hand, the variation of PMSE intensity (85–90 km) was in phase with fluctuations of electron densities (90–110 km) with ~12‐ and ~13‐min periodicities at the initial and later stages, respectively. The initial creation of PMSE can be attributed to both the sudden onset of particle precipitation and ice particles produced by adiabatic cooling during the rapid updraft, as detected by large upward velocity. Our periodogram analysis suggests that variations of PMSE intensity seem to follow the same periods with E region electron density, which is moduled by energetic electron precipitation, while vertical velocity oscillates at atmospheric gravity wave periods.
Control of PD-L1 expression by miR-140/142/340/383 and oncogenic activation of the OCT4–miR-18a pathway in cervical cancer
Authors: Dong Peixin , Xiong Ying , Yu Jiehai , Chen Lin , Tao Tang , Yi Song , Hanley Sharon J. B. , Yue Junming , Watari Hidemichi , Sakuragi Noriaki 
Published: May 2018

Abstract
PD-L1, a key inhibitory immune receptor, has crucial functions in cancer immune evasion, but whether PD-L1 promotes the malignant properties of cervical cancer (CC) cells and the mechanism by which PD-L1 is regulated in CC remains unclear. We report that PD-L1 is overexpressed in CC, and shRNA-mediated PD-L1 depletion suppresses the proliferation, invasion, and tumorigenesis of CC cells. Loss of miR-140/142/340/383 contributes to PD-L1 upregulation. miR-18a enhances PD-L1 levels by targeting PTEN, WNK2 (ERK1/2 pathway inhibitor), and SOX6 (Wnt/β-catenin pathway inhibitor and p53 pathway activator) to activate the PI3K/AKT, MEK/ERK, and Wnt/β-catenin pathways and inhibit the p53 pathway, and miR-18a also directly suppresses the expression of the tumor suppressors BTG3 and RBSP3 (CTDSPL). miR-18a overexpression in CC cells is triggered by OCT4 overexpression. Our data implicate PD-L1 as a novel oncoprotein and indicate that miR-140/142/340/383 and miR-18a are key upstream regulators of PD-L1 and potential targets for CC treatment.
Prognostic role of carcinoembryonic antigen and carbohydrate antigen 19-9 in metastatic colorectal cancer: a BRAF-mutant subset with high CA 19-9 level and poor outcome
Authors: Thomsen Maria , Skovlund Eva , Sorbye Halfdan , Bolstad Nils , Nustad Kjell Johannes , Glimelius Bengt , Pfeiffer Per , Kure Elin H. , Johansen Julia S. , Tveit Kjell Magne , Christoffersen Thoralf , Guren Tormod Kyrre 
Published: June 2018

Abstract

Background
Mutation status of RAS and BRAF, as well as serum levels of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA 19-9), are biomarkers used in clinical management of patients with gastrointestinal cancers. This study aimed to examine the prognostic role of these biomarkers in a patient population that started first-line chemotherapy for unresectable metastatic colorectal cancer (mCRC) in the NORDIC-VII study.

Methods
CEA and CA 19-9 were measured in serum samples from 545 patients obtained before the start of chemotherapy. Four hundred and ninety-four patients had detectable levels of carbohydrate antigen 19-9 (CA 19-9). RAS (exons 2–4) and BRAF (V600E) mutation status were available from 440 patients. Overall survival (OS) was estimated in patient groups defined by serum CEA or CA 19-9 levels using cut-off values of 5 µg/L and 35 kU/L, respectively, in the total population and in subgroups according to RAS and BRAF mutation status.

Results
For both CEA and CA 19-9, elevated serum levels were associated with reduced OS in adjusted analyses which included RAS and BRAF mutation status, baseline World Health Organization performance status, and levels of alkaline phosphatase and C-reactive protein. The negative prognostic information provided by an elevated CA 19-9 level was particularly marked in patients with BRAF mutation (hazard ratio = 4.35, interaction P = 0.003, in an adjusted model for OS).

Conclusions
High baseline serum concentrations of CEA and CA 19-9 provide independent information of impaired prognosis in mCRC. In patients with BRAF-mutant tumours, elevated serum CA 19-9 may identify a subgroup with highly aggressive disease and could contribute to improving therapeutic decisions.
Programming for increased expression of hippocampal GAD67 mediated the hypersensitivity of the hypothalamic–pituitary–adrenal axis in male offspring rats with prenatal ethanol exposure
Authors: Lu Juan , Jiao Zhexiao , Yu Ying , Zhang Chong , He Xia , Li Qiang , Xu Dan , Wang Hui 
Published: May 2018

AbstractAn imbalance of excitatory and inhibitory signals in the brain has been proposed to be one of the main pathological features of various diseases related to hypothalamic–pituitary–adrenal axis (HPAA) dysfunction. Excessive glutamate release induces neuronal excitotoxicity, while glutamic acid decarboxylase (GAD) 67 promotes the transformation of excessive glutamate to γ-aminobutyric acid (GABA). Our previous studies demonstrated that prenatal ethanol exposure (PEE) causes foetal over-exposure to maternal corticosterone and hypersensitivity of the HPAA after birth, but its intrauterine programming mechanism is unknown. In this study, PEE was shown to lead to an enhanced potential excitatory ability of the hypothalamus and hypersensitivity of the HPAA, as well as mild abnormal hippocampal morphology, demethylation of the -1019 to -691-bp region in the hippocampal GAD67 promoter and upregulation of GAD67 expression accompanied by a reduction in glutamatergic neurons and increase in GABAergic neurons in PEE male offspring. Similar changes were also found in PEE male foetal rats. Furthermore, corticosterone increased the expression of the glucocorticoid receptor (GR) and GAD67 in foetal hippocampal H19-7 cells in a concentration-dependent manner, accompanied by demethylation of the GAD67 promoter, a decrease in glutamatergic neurons and increase in GABAergic neurons. The GR inhibitor, mifepristone, reversed the effects of corticosterone on H19-7 cells. These results suggested that PEE-induced excessive corticosterone can lead to upregulation of GAD67 through epigenetic modification mediated by the GR in the male foetal hippocampus, thereby weakening the negative regulation of the HPAA by the hippocampus and increasing the potential excitatory ability of the hypothalamus. These changes persisted until after birth, resulting in hypersensitivity of the HPAA. However, gender differences were observed in the hippocampal development, morphology and GAD67 expression associated with PEE. Programming for the increased expression of hippocampal GAD67 is a potential mechanism responsible for the hypersensitivity of the HPAA in PEE male rats.
RAGE-dependent mitochondria pathway: a novel target of silibinin against apoptosis of osteoblastic cells induced by advanced glycation end products
Authors: Mao Y. X. , Cai W. J. , Sun X. Y. , Dai P. P. , Li X. M. , Wang Q. , Huang X. L. , He B. , Wang P. P. , Wu G. , Ma J. F. , Huang S. B. 
Published: June 2018

AbstractAdvanced glycation end products (AGEs) can stimulate osteoblast apoptosis and have a critical role in the pathophysiology of diabetic osteoporosis. Mitochondrial abnormalities are closely related to osteoblast dysfunction. However, it remains unclear whether mitochondrial abnormalities are involved in AGE-induced osteoblastic cell apoptosis. Silibinin, a major flavonolignan compound of silimarin, has strong antioxidant and mitochondria-protective properties. In the present study, we explored the possible mitochondrial mechanisms underlying AGE-induced apoptosis of osteoblastic cells and the effect of silibinin on osteoblastic cell apoptosis. We demonstrated that mitochondrial abnormalities largely contributed to AGE-induced apoptosis of osteoblastic cells, as evidenced by enhanced mitochondrial oxidative stress, conspicuous reduction in mitochondrial membrane potential and adenosine triphosphate production, abnormal mitochondrial morphology, and altered mitochondrial dynamics. These AGE-induced mitochondrial abnormalities were mainly mediated by the receptor of AGEs (RAGE). In addition, we found that silibinin directly downregulated the expression of RAGE and modulated RAGE-mediated mitochondrial pathways, thereby preventing AGE-induced apoptosis of osteoblastic cells. This study not only provides a new insight into the mitochondrial mechanisms underlying AGE-induced osteoblastic cell apoptosis, but also lays a foundation for the clinical use of silibinin for the prevention or treatment of diabetic osteoporosis.
Manipulating type-I and type-II Dirac polaritons in cavity-embedded honeycomb metasurfaces
Authors: Mann Charlie-Ray , Sturges Thomas J. , Weick Guillaume , Barnes William L. , Mariani Eros 
Published: May 2018

AbstractPseudorelativistic Dirac quasiparticles have emerged in a plethora of artificial graphene systems that mimic the underlying honeycomb symmetry of graphene. However, it is notoriously difficult to manipulate their properties without modifying the lattice structure. Here we theoretically investigate polaritons supported by honeycomb metasurfaces and, despite the trivial nature of the resonant elements, we unveil rich Dirac physics stemming from a non-trivial winding in the light–matter interaction. The metasurfaces simultaneously exhibit two distinct species of massless Dirac polaritons, namely type-I and type-II. By modifying only the photonic environment via an enclosing cavity, one can manipulate the location of the type-II Dirac points, leading to qualitatively different polariton phases. This enables one to alter the fundamental properties of the emergent Dirac polaritons while preserving the lattice structure—a unique scenario which has no analog in real or artificial graphene systems. Exploiting the photonic environment will thus give rise to unexplored Dirac physics at the subwavelength scale.