bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical modelling of the expansion of a solid obstacle interacting with a radiative shock
Authors: Michel Th. , Falize E. , Albertazzi B. , Rigon G. , Sakawa Y. , Sano T. , Shimogawara H. , Kumar R. , Morita T. , Michaut C. , Casner A. , Barroso P. , Mabey P. , Kuramitsu Y. , Laffite S. , Van Box Som L. , Gregori G. , Kodama R. , Ozaki N. , Tzeferacos P. , Lamb D. , Koenig M.
Published: June 2018

In this paper, we present a model characterizing the interaction of a radiative shock (RS) with a solid material, as described in a recent paper (Koenig et al., Phys. Plasmas, 24, 082707 (2017)), the new model is then related to recent experiments performed on the GEKKO XII laser facility. The RS generated in a xenon gas cell propagates towards a solid obstacle that is ablated by radiation coming from the shock front and the radiative precursor, mimicking processes occurring in astrophysical phenomena. The model presented here calculates the dynamics of the obstacle expansion, which depends on several parameters, notably the geometry and the temperature of the shock. All parameters required for the model have been obtained from experiments. Good agreement between experimental data and the model is found when spherical geometry is taken into account. As a consequence, this model is a useful and easy tool to infer parameters from experimental data (such as the shock temperature), and also to design future experiments.
Flow of buoyant granular materials along a free surface
Authors: Zheng Zhong , Huppert Herbert E. , Vriend Nathalie M. , Neufeld Jerome A. , Linden P. F.
Published: June 2018

We study experimentally the flow of light granular material along the free surface of a liquid of greater density. Despite a rich set of related geophysical and environmental phenomena, such as the spreading of calved ice, volcanic ash, debris and industrial wastes, there are few previous studies on this topic. We conduct a series of lock-release experiments of buoyant spherical beads into a rectangular tank initially filled with either fresh or salt water, and record the time evolution of the interface shape and the front location of the current of beads. We find that following the release of the lock the front location obeys a power-law behaviour during an intermediate time period before the nose of beads reaches a maximum runout distance within a finite time. We investigate the dependence of the scaling exponent and runout distance on the total amount of beads, the initial lock length, and the properties of the liquid that fills the tank in the experiments. Scaling arguments are provided to collapse the experimental data into universal curves, which can be used to describe the front dynamics of buoyant granular flows with different size and buoyancy effects and initial lock aspect ratios.
A taste for art in colonial Queensland
Authors: Heckenberg Kerry
Published: June 2018

This study arose from an encounter with some paintings (still lives, Madonnas and other religious or genre scenes of mainly seventeenth-century Northern European origin) at the Queensland Art Gallery in 2012. They were intriguing because they were part of a bequest by squatter and colonial parliamentarian Thomas Lodge Murray-Prior (1819–92), which formed the nucleus of the original Queensland Art Gallery collection when it opened in 1895. Little is known about them, but they raise questions: What part did they play in the life of the donor? Did he collect them merely to burnish his reputation? Were they hung in a town house or in the bush? How did they enter the collection of the Queensland Art Gallery and what reception did they receive? What subsequent use has been made of them? This article examines the collection and the role it played in Murray-Prior’s life, arguing that it is a coherent collection of Northern European art and more than a status symbol. Furthermore, it has much to say about a period that saw the development of art collecting and exhibiting. As such, it is the perfect foundation for an art gallery in colonial Australia.
'Touching the edges of cyclones'
Authors: Spicer Chrystopher J.
Published: June 2018

Thea Astley once commented that, ‘everybody is living on a cyclonic edge’, and that many of her characters were ‘always touching on the edges of cyclones’. In Queensland literature, cyclones often appear as tropes of apocalypse: new worlds of person and place are revealed out of the destruction of the old. In Astley’s novel A Boat Load of Home Folk (1968), the tempestuous forces of personal cyclones, as well as those of the cyclone destroying the island around them, overtake a group of stranded cruise passengers, and consequently place and person assume unique meanings as the characters try to survive. Although one of her least-known works, A Boat Load of Home Folk is a profound novel of human experience in which Astley uses the elemental cyclone as a trope of apocalypse that is both an instrument of destruction and a catalyst of revelation.
A tale of two parties
Authors: Salisbury Chris
Published: June 2018

Queensland’s 2017 state election resulted in Annastacia Palaszczuk’s Labor government being returned with a slim majority. While not a resounding victory, the result seemingly vindicated the premier’s decision to head to an early election, and reinforced her standing in a succession of opinion polls as ‘preferred premier’ for most voters. The result also halted the short sequence of Queensland governments being voted out of office in no uncertain terms by a supposedly volatile electorate. The extent to which Labor’s recent electoral success in Queensland — and the quelling of that volatility — can be attributed to Palaszczuk’s leadership is still open to debate. It is instructive, though, to note the differences in leadership and campaigning styles between Palaszczuk and her opponents, which saw her drag a decimated Labor Party back to office after a single term in opposition, then saw it returned with a working parliamentary majority. This article highlights those differences over the last term of government, contrasting the performance of the two major parties in Queensland in terms of their leadership and election campaign approaches. The analysis helps to explain some of the reasons for the respective parties’ recent electoral showings.
Investigating the function of prehistoric stone bowls and griddle stones in the Aleutian Islands by lipid residue analysis
Authors: Admiraal Marjolein , Lucquin Alexandre , von Tersch Matthew , Jordan Peter D. , Craig Oliver E.
Published: June 2018

The earliest durable cooking technologies found in Alaska are stone bowls and griddle stones recovered from the Aleutian Islands. This article aims to identify the function of these artefacts. Molecular and chemical analyses of carbonised residues found on their surfaces confirm that these artefacts were used to process marine resources. Both artefacts have high lipid content and C:N ratios, suggesting they were used to process oily substances. Stable isotope results of individual lipids suggest that they were used to process different sets of resources within the aquatic spectrum as griddle stones have slightly more 13C-depleted lipids than stone bowls, possibly indicating more variable use. Integration of these results with archaeological and ethnographic data leads us to infer that griddle stones were used for cooking a diversity of aquatic resources, possibly with the addition of plant foods, whereas stone bowls were specifically used to render marine mammal fats. We further hypothesize that a sudden peak in stone bowl frequencies at 4000–3000 cal yr BP was connected to a Neoglacial cold spell bringing sea ice conditions to the Aleutian Islands. This may have led to new subsistence strategies in which the rendering of marine mammal fats played a central role.
Global glacier dynamics during 100 ka Pleistocene glacial cycles
Authors: Hughes Philip D. , Gibbard Philip L.
Published: June 2018

Ice volume during the last ten 100 ka glacial cycles was driven by solar radiation flux in the Northern Hemisphere. Early minima in solar radiation combined with critical levels of atmospheric CO2drove initial glacier expansion. Glacial cycles between Marine Isotope Stage (MIS) 24 and MIS 13, whilst at 100 ka periodicity, were irregular in amplitude, and the shift to the largest amplitude 100 ka glacial cycles occurred after MIS 16. Mountain glaciers in the mid-latitudes and Asia reached their maximum extents early in glacial cycles, then retreated as global climate became increasingly arid. In contrast, larger ice masses close to maritime moisture sources continued to build up and dominated global glacial maxima reflected in marine isotope and sea-level records. The effect of this pattern of glaciation on the state of the global atmosphere is evident in dust records from Antarctic ice cores, where pronounced double peaks in dust flux occur in all of the last eight glacial cycles. Glacier growth is strongly modulated by variations in solar radiation, especially in glacial inceptions. This external control accounts for ~50–60% of ice volume change through glacial cycles. Internal global glacier–climate dynamics account for the rest of the change, which is controlled by the geographic distributions of glaciers.
Dietary polyphenol intake and their major food sources in the Mexican Teachers’ Cohort
Authors: Zamora-Ros Raul , Biessy Carine , Rothwell Joseph A. , Monge Adriana , Lajous Martin , Scalbert Augustin , López-Ridaura Ruy , Romieu Isabelle
Published: June 2018

Several descriptive studies on the intake of polyphenols, mostly flavonoids, have been published, especially in Europe and the USA, but insufficient data are still available in Latin-American countries, where different types of foods are consumed and different dietary habits are observed. The goal of this cross-sectional study was to estimate dietary intakes of polyphenols, including grand total, total per classes and subclasses and individual compounds, and to identify their main food sources in Mexican women. The Mexican Teachers’ Cohort includes 115 315 female teachers, 25 years and older, from twelve states of Mexico, including urban and rural areas. Dietary data were collected in the period 2008–2011 using a validated FFQ, and individual polyphenol intake was estimated using food composition data from the Phenol-Explorer database. Median total polyphenol intake was the highest in Baja California (750 mg/d) and the lowest in Yucatan (536 mg/d). The main polyphenols consumed were phenolic acids (56·3–68·5 % total polyphenols), followed by flavonoids (28·8–40·9 %). Intake of other polyphenol subclasses (stilbenes, lignans and others) was insignificant. Coffee and fruits were the most important food sources of phenolic acids and flavonoids, respectively. Intake of a total of 287 different individual polyphenols could be estimated, of which forty-two were consumed in an amount ≥1 mg/d. The most largely consumed polyphenols were several caffeoylquinic acids (ranging from 20 and 460 mg/d), ferulic acid, hesperidin and proanthocyanidins. This study shows a large heterogeneity in intakes of individual polyphenols among Mexican women, but a moderate heterogeneity across Mexican states. Main food sources were also similar in the different states.
WHEN GOOD MEN DO NOTHING: AN EMENDATION IN TACITUS, HISTORIAE 1.38.3
Authors: Mellen Gregory R.
Published: June 2018

In January of the year a.d. 69, Marcus Salvius Otho, disappointed in his attempt to be named Galba's heir and successor, fomented revolt among the praetorian guard. Trading on the praetorians’ own discontent at not receiving the donative, he began to win over the soldiers’ favour. Tacitus relates that, when the attitude of the soldiers seemed ripe (haud dubiae iam in castris omnium mentes, Hist. 1.36.1), Otho himself came forth and began to implore them directly (nec deerat Otho protendens manus adorare uolgum, iacere oscula, et omnia seruiliter pro dominatione, Hist. 1.36.3); and after he accepted the oath of loyalty from the entire classicorum legio (Hist. 1.36.3), he felt ready to hold a speech encouraging the men to complete the deed by ousting Galba.
TRANSGRESSIVE SEGREGATION, HETEROSIS AND HERITABILITY FOR YIELD-RELATED TRAITS IN A SEGREGATING POPULATION OF PISUM SATIVUM L.
Authors: GUINDON M. FERNANDA , MARTIN EUGENIA , CRAVERO VANINA , COINTRY ENRIQUE
Published: June 2018

Pea is a self-pollinated, diploid (2n = 14), annual crop produced worldwide for human consumption and animal feed. The exploitation of maximum genetic potential from available pea resources implies the knowledge of genetic parameters of yield components. Hence, the present study was conducted in a cross between two pea varieties, namely DDR14 and Explorer, its F2 progeny and F3 families to find out transgressive segregants and to determine the magnitude of narrow sense heritability and heterosis. The high narrow sense heritability values obtained indicated that rapid gain could be achieved through selection for the different traits; however, the presence of genotype x environment interaction could limit the correspondence of these estimated values with the observed ones. The selection of lines through their phenotypic values is influenced by environmental and error effects. Best linear unbiased prediction (BLUP) was used for the prediction of genotypic values using morphological data from different years, allowing the correction for environmental effects. These estimates were used for genetic analysis of the traits. Heterosis was observed for number of pods (27.1%) and number of seeds (23.3%), characters that have a direct effect on yield. The cross also showed high frequency of transgressive segregation for these characters in F3 generation (15.5% and 13.6%, respectively). There were 12.73% families transgressive for two or more characters, with genotypic values of 49.82–64.41 for number of pods and 153.75–189.59 for seed number. The crossing between Explorer and DDR14 provided a base for the selection of superior progeny.
The Determinants of Environmental Migrants' Conflict Perception
Authors: Koubi Vally , Böhmelt Tobias , Spilker Gabriele , Schaffer Lena
Published: June 2018

Migration is likely to be a key factor linking climate change and conflict. However, our understanding of the factors behind and consequences of migration is surprisingly limited. We take this shortcoming as a motivation for our research and study the relationship between environmental migration and conflict at the micro level. In particular, we focus on environmental migrants' conflictperceptions. We contend that variation in migrants' conflict perception can be explained by the type of environmental event people experienced in their former home, whether gradual, and long-term or sudden-onset, short-term environmental changes. We develop this argument before quantitatively analyzing newly collected micro-level data on intra-state migration from five developing countries. The results emphasize that migrants who experienced gradual, long-term environmental events in their former homes are more likely to perceive conflict in their new location than those having experienced sudden, short-term environmental events. These findings are in line with our theoretical argument that environmental migrants who suffer from environmentally induced grievances are ultimately more likely toperceiveconflict and challenges in their new locations.
At-risk studies and clinical antecedents of psychosis, bipolar disorder and depression: a scoping review in the context of clinical staging
Authors: Hartmann Jessica A , Nelson Barnaby , Ratheesh Aswin , Treen Devi , McGorry Patrick D
Published: June 2018

Identifying young people at risk of developing serious mental illness and identifying predictors of onset of illness has been a focus of psychiatric prediction research, particularly in the field of psychosis. Work in this area has facilitated the adoption of the clinical staging model of early clinical phenotypes, ranging from at-risk mental states to chronic and severe mental illness. It has been a topic of debate if these staging models should be conceptualised as disorder-specific or transdiagnostic. In order to inform this debate and facilitate cross-diagnostic discourse, the present scoping review provides a broad overview of the body of literature of (a) longitudinal at-risk approaches and (b) identified antecedents of (homotypic) illness progression across three major mental disorders [psychosis, bipolar disorder (BD) and depression], and places these in the context of clinical staging. Stage 0 at-risk conceptualisations (i.e. familial high-risk approaches) were identified in all three disorders. However, formalised stage 1b conceptualisations (i.e. ultra-high-risk approaches) were only present in psychosis and marginally in BD. The presence of non-specific and overlapping antecedents in the three disorders may support a general staging model, at least in the early stages of severe psychotic or mood disorders.
A simple and visually orientated approach for type synthesis of overconstrained 1T2R parallel mechanisms
Authors: Huang Tian , Dong Chenglin , Liu Haitao , Sun Tao , Chetwynd Derek G.
Published: June 2018

This paper presents a simple and highly visual approach for the type synthesis of a family of overconstrained parallel mechanisms that have one translational and two rotational movement capabilities. It considers, especially, mechanisms offering the accuracy and dynamic response needed for machining applications. This family features a spatial limb plus a member of a class of planar symmetrical linkages, the latter connected by a revolute joint either to the machine frame at its base link or to the platform at its output link. Criteria for selecting suitable structures from among numerous candidates are proposed by considering the realistic practical requirements for reconfigurability, movement capability, rational component design and so on. It concludes that a few can simultaneously fulfil the proposed criteria, even though a variety of structures have been presented in the literature. Exploitation of the proposed structures and evaluation criteria then leads to a novel five degrees of freedom hybrid module named TriMule. A significant potential advantage of the TriMule over the Tricept arises because all the joints connecting the base link and the machine frame can be integrated into one single, compact part, leading to a lightweight, cost effective and flexible design particularly suitable for configuring various robotized manufacturing cells.
Weighting-based semantic similarity measure based on topological parameters in semantic taxonomy
Authors: SAIF ABDULGABBAR , ZAINODIN UMMI ZAKIAH , OMAR NAZLIA , GHAREB ABDULLAH SAEED
Published: June 2018

Semantic measures are used in handling different issues in several research areas, such as artificial intelligence, natural language processing, knowledge engineering, bioinformatics, and information retrieval. Hierarchical feature-based semantic measures have been proposed to estimate the semantic similarity between two concepts/words depending on the features extracted from a semantic taxonomy (hierarchy) of a given lexical source. The central issue in these measures is the constant weighting assumption that all elements in the semantic representation of the concept possess the same relevance. In this paper, a new weighting-based semantic similarity measure is proposed to address the issues in hierarchical feature-based measures. Four mechanisms are introduced to weigh the degree of relevance of features in the semantic representation of a concept by using topological parameters (edge, depth, descendants, and density) in a semantic taxonomy. With the semantic taxonomy of WordNet, the proposed semantic measure is evaluated for word semantic similarity in four gold-standard datasets. Experimental results show that the proposed measure outperforms hierarchical feature-based semantic measures in all the datasets. Comparison results also imply that the proposed measure is more effective than information-content measures in measuring semantic similarity.
A Novel Method to Reconstruct the Force Curve by Higher Harmonics of the First Two Flexural Modes in Frequency Modulation Atomic Force Microscope (FM-AFM)
Authors: Zhang Suoxin , Qian Jianqiang , Li Yingzi , Zhang Yingxu , Wang Zhenyu
Published: June 2018

Atomic force microscope (AFM) is an idealized tool to measure the physical and chemical properties of the sample surfaces by reconstructing the force curve, which is of great significance to materials science, biology, and medicine science. Frequency modulation atomic force microscope (FM-AFM) collects the frequency shift as feedback thus having high force sensitivity and it accomplishes a true noncontact mode, which means great potential in biological sample detection field. However, it is a challenge to establish the relationship between the cantilever properties observed in practice and the tip–sample interaction theoretically. Moreover, there is no existing method to reconstruct the force curve in FM-AFM combining the higher harmonics and the higher flexural modes. This paper proposes a novel method that a full force curve can be reconstructed by any order higher harmonics of the first two flexural modes under any vibration amplitude in FM-AFM. Moreover, in the small amplitude regime, short range forces are reconstructed more accurately by higher harmonics analysis compared with fundamental harmonics using the Sader–Jarvis formula.
Domestic Devotion and the Georgian Church
Authors: Braddock Andrew
Published: June 2018

This article explores the development of domestic devotion in the Georgian Church of England through an examination of the manuals of prayer produced and circulated for both personal and family use throughout the eighteenth century. Alongside more well-known works, including Edmund Gibson’s Family Devotion and Robert Nelson’s Companion for the Festivals and Fasts, it pays attention to the diverse material provided for private and household devotion and its relationship to The Book of Common Prayer. The article highlights the key themes that were expressed through this literature, the spirituality that it fostered, and the sources on which it drew. It reveals how greater awareness of this material can deepen our understanding of how Georgian Anglicans prayed and what they were encouraged to pray for.
Fifty Years of Candidate Pulsar Selection - What next?
Authors: Lyon R. J.
Published: June 2018

For fifty years astronomers have been searching for pulsar signals in observational data. Throughout this time the process of choosing detections worthy of investigation, so called ‘candidate selection’, has been effective, yielding thousands of pulsar discoveries. Yet in recent years technological advances have permitted the proliferation of pulsar-like candidates, straining our candidate selection capabilities, and ultimately reducing selection accuracy. To overcome such problems, we now apply ‘intelligent’ machine learning tools. Whilst these have achieved success, candidate volumes continue to increase, and our methods have to evolve to keep pace with the change. This talk considers how to meet this challenge as a community.
Spectral Flattening of Crab Giant Pulses at Low Frequencies
Authors: Meyers Bradley W. , Tremblay Steven E. , Ramesh Bhat N. D. , Shannon Ryan M.
Published: June 2018

The frequency dependence of normal pulsar radio emission is typically observed to be a power law, with some indications of a flattening or turnover at low frequencies (≲ 100 MHz). The spectrum of the Crab pulsar’s giant pulse emission has not been examined as closely. We conducted simultaneous wideband observations of the Crab pulsar, with the Parkes radio telescope and the Murchison Widefield Array, to study the spectral behaviour of its giant pulses. Our analysis shows that the mean spectral index of Crab giant pulses flattens at low frequencies, from −2.6 ± 0.5 between the Parkes bands, to −0.7 ± 1.4 between the lowest MWA subbands.
Magnetar nebulae can be rotationally powered
Authors: Torres Diego F.
Published: June 2018

A wind nebula generating extended X-ray emission was recently detected surrounding Swift 1834.9-0846. This is the first magnetar for which such a (pulsar) wind nebula (PWN) was found. I demonstrate that Swift 1834.9-0846’s nebula can be rotationally-powered if it is being compressed by the environment. The physical reason behind this is the dominance of adiabatic heating over all other cooling and escape processes. This effect can happen only for pulsars of relatively low spin-down power and can make for very efficient nebulae. This contribution is based on previous work published in ApJ 835, article id. 54, 13 pp. (2017).
Searching for X-ray Pulsations from Neutron Stars Using NICER
Authors: Ray Paul S. , Arzoumanian Zaven , Gendreau Keith C. ,   for the NICER Working Group on Pulsation Searches and Multiwavelength Coordination
Published: June 2018

The Neutron Star Interior Composition Explorer (NICER) presents an exciting new capability for exploring the modulation properties of X-ray emitting neutron stars, including large area, low background, extremely precise absolute event time stamps, superb low-energy response and flexible scheduling. The Pulsation Searches and Multiwavelength Coordination working group has designed a 2.5 Ms observing program to search for emission and characterize the modulation properties of about 30 known or suspected neutron star sources across a number of source categories. A key early goal will be to search for pulsations from millisecond pulsars that might exhibit thermal pulsations from the surface suitable for pulse profile modeling to constrain the neutron star equation of state. In addition, we will search for pulsations from transitional millisecond pulsars, isolated neutron stars, low-mass X-ray binaries (LMXBs), accretion-powered millisecond pulsars, central compact objects and other sources. We present our science plan and initial results from the first months of the NICER mission, including the discovery of pulsations from the millisecond pulsar J1231–1411.
Coherent origin of peculiar polarization in radio pulsars
Authors: Dyks Jarosław
Published: June 2018

The observed polarization of radio pulsars involves several peculiar effects, such as comparable amount of orthogonal polarization modes (OPMs) which often bear the same handedness of circular polarisation V. In the average profiles of B1913+16 and B1933+16, orthogonal jumps of polarization angle (PA) are observed to occur at the maximum V, instead of V = 0. High levels of V are also observed in core components (eg. in B1237+25), where they are accompanied by strong distortions of PA from the rotating vector model. In weakly polarized emission, PA jumps by 45° are observed in B1919+21 and B0823+26. It is shown that all these peculiarities can be interpreted in a model which assumes coherent addition of waves in natural propagation modes.
Inhomogeneous Chiral and Coulomb Crystal in Neutron Stars
Authors: Yasutake Nobutoshi , Lee Tong-Gyu , Maruyama Toshiki , Tatsumi Toshitaka
Published: June 2018

We study the possibility of two types of inhomogeneous phases in core of neutron stars: one is the Coulomb crystal, which is known as quark-hadron pasta structures, and another one is chiral crystal. In the Coulomb crystal, the inhomogeneous phase appears as the result of the balance between the surface tension and the Coulomb interaction. In chiral crystal, we study the inhomogeneous chiral condensate, which has spatial modulation. In the simple model in 1+1 dimensions, this condensate has the same feature with the FFLO state, which is well known in the condensed matter physics.
Luminosity of synchrotron radiation from outer magnetosphere of pulsars
Authors: Kisaka Shota , Tanaka Shuta J.
Published: June 2018

We calculate the luminosity of the synchrotron radiation from the vicinity of the light cylinder. We find that even if the thermal emission from the entire surface is included as the seed photon, the γ-ray to X-ray flux ratio for young pulsars is significantly higher than the observations. For these pulsars, most of γ-ray photons may be absorbed in the magnetosphere.
Radio spectra of millisecond pulsars
Authors: Kondratiev Vladislav , Bilous Anna ,   LOFAR PWG
Published: June 2018

Both the physics of the pulsar emission mechanism and free-free absorption in the intervening interstellar medium can be tested with the pulsar radio spectra. We have built on our previous work on describing LOFAR population of millisecond pulsars (MSPs; Kondratiev et al. 2016) and HBA census of slow pulsars (Bilous et al. 2016) and present the study of radio spectra of the MSPs with a special attention on the low-frequency turnover. Using LOFAR timing data allowed us to measure flux densities of many MSPs over time span of up to three years in the frequency range 110–188 MHz. This provided more reliable estimates of mean flux densities and spectra reducing the influence of refractive scintillation, ionosphere and other factors on a single flux measurement. Together with published data at other radio frequencies we constructed pulsars’ spectra and fitted them with single or broken power-laws. We discuss the obtained spectra and their fits, paying special attention to the low-frequency turnover, and compare broadband radio spectra of MSPs to those of normal pulsars.
Search for FRB and FRB-like single pulses in Parkes magnetar data
Authors: Burgay M. , Esposito P. , Israel G.L. , Rea N. , Possenti A. , Sarkissian J.
Published: June 2018

We present the results of a search for strong single radio pulses emitted by magnetars and for FRB signals in the fields of magnetars observed at the Parkes radio telescope within the NAPA project P626. Unsurprisingly, given the short total observing time, no extragalacic FRB signal was found up to a DM of 3000 pc/cm3. Two strong pulses dispersed at the DM of the known radio magnetar J1550–5418 where found, one occurring at the same time of an X-ray burst. This result is potentially interesting in the framework of magnetar models for FRBs.
Status of the Thai 40-m Radio Telescope
Authors: Jaroenjittichai Phrudth
Published: June 2018

Since the first light of the 2.4-m Thai National Telescope in 2013, Thailand foresees another great leap forward in astronomy. A project known as “Radio Astronomy Network and Geodesy for Development” (RANGD) by National Astronomical Research Institute of Thailand (NARIT) has been approved for year 2017-2021. A 40-m radio telescope has been planned to operate up to 115-GHz observation with prime-focus capability for low frequency and phased array feed receivers. The telescope’s first light is expected in late 2019 with a cryogenics K-band and L-band receivers. RFI environment at the site has been investigated and shown to be at reasonable level. A 13-m VGOS telescope is also included for geodetic applications. Early single-dish science will focus on time domain observations, such as pulsars and transients, outbursts and variability of maser and AGN sources.
On the Radio Emitting Particles of the Crab Nebula: Stochastic Acceleration Model
Authors: Tanaka Shuta J.
Published: June 2018

The standard shock acceleration model of pulsar wind nebulae (PWNe) does not account for the hard spectrum in radio wavelengths. The origin of the radio-emitting particles is also important to determine the pair production efficiency in the pulsar magnetosphere. Here, we propose a possible resolution for the particle energy distribution in PWNe; the radio-emitting particles are not accelerated at the pulsar wind termination shock but are stochastically accelerated by turbulence inside PWNe. We upgrade our past one-zone spectral evolution model including the energy diffusion, i.e., the stochastic acceleration, and apply to the Crab Nebula. For a particle injection to the stochastic acceleration process, we consider the continuous injection from the supernova ejecta or the impulsive injection associated with supernova explosion. The observed broadband spectrum and the decay of the radio flux are reproduced by tuning the amount of the particle injected to the stochastic acceleration process. Our results imply that some unveiled mechanisms, such as back reaction to the turbulence, are required to make the energies of stochastically and shock accelerated particles comparable.
Systematic analysis about the polarization in thermal radiations of magnetars
Authors: Yatabe Akihiro , Yamada Shoichi
Published: June 2018

We calculated the polarization in soft X-ray emitted from magnetars, which are expected to be observed by the next-generation X-ray satellites. We consider possible conversions of photon’s polarization modes in the atmosphere and it cannot be ignored when the magnetic field is relatively weak B ≲ 1013G.
The LOFAR Tied-Array All-Sky Survey for Pulsars and Fast Transients
Authors: Tan C. M. ,   the LOTAAS Group
Published: June 2018

The LOFAR Tied Array All-Sky Survey (LOTAAS) is an ongoing all northern sky survey for pulsars and transients. It is one of the first large scale pulsar surveys conducted at an observing frequency below 200 MHz. The unique set-up of the survey is the simultaneous formation of 222 beams for each survey pointing by coherently adding signals from the central 6 LOFAR stations. This represents the first SKA-like pulsar survey. As of 12 September 2017, the survey has completed 1456 pointings, more than two-thirds of the total. The survey has discovered 61 new pulsars via Fourier-based periodicity searches and a further 5 via single pulse searches. I present the survey approach and distinctive features including a discussion of an improved machine learning classifier used to identify the best candidates produced by the pipeline for further investigation. I present a summary of the discoveries so far including the first binary pulsar and the pulsar with the longest spin period of 23.5 s.
Pulsar Observations at the Ghana Radio Astronomy Observatory
Authors: Scragg T. W. , Stappers B. W. , Breton R. P. , Smith J. N. , Adomako D. , Asabere B. Duah , Chibueze J. O. , Cloete K.
Published: June 2018

In August 2017 a new radio telescope, the Ghana Radio Astronomy Observatory (GRAO), was officially inaugurated at Kuntunse, Ghana. The GRAO is a former satellite Earth station and now the first operational station in the African VLBI Network (AVN). The Jodrell Bank Centre for Astrophysics (JBCA), supported by the UK’s STFC/Newton Fund, has developed a new pulsar timing system (Hebe) for the GRAO. We present some aspects of the design of Hebe and an outline of the first pulsar detection at GRAO.
Pulsar Science with the SKA
Authors: Keane Evan F.
Published: June 2018

The Square Kilometre Array (SKA) will be sensitive enough to discover all of the pulsars in the Milky Way that are beamed towards Earth. Already in the initial deployment, SKA Phase 1, it will make significant advances in pulsar science. In these proceedings I briefly overview what the SKA is, and describe its pulsar search and timing capabilities.
1,000,000 Giant Pulses from the Crab Pulsar
Authors: Mickaliger Mitchell B. , Stappers Ben W. , Bassa Cees G. , Fletcher Aldus G.
Published: June 2018

The Crab pulsar was first detected soon after the discovery of pulsars, and has long been studied for its unique traits. One of these traits, giant pulses that can be upwards of 1000 times brighter than the average pulse, was key to the Crab’s initial detection. Giant pulses are only seen in a few pulsars, and their energy distributions distinguish them from normal pulsed emission. There have been many studies over a period of decades to measure the power-law slope of these energy distributions, which provide insight into the possible emission mechanism of these giant pulses.

The 42-foot telescope at Jodrell Bank Observatory monitors the Crab pulsar on a daily basis. We have single-pulse data dating back to 2012, containing roughly 1,000,000 giant pulses, the largest sample of Crab giant pulses to date. This large set of giant pulses allows us to do a range of science, including pulse-width studies and in-depth studies of giant-pulse energy distributions. The latter are particularly interesting, as close inspection of the high-energy tail of the energy distribution allows us to investigate the detectability of extragalactic giant-pulsing pulsars. Also, by calculating rates from these energy distributions, we may be able to shed light on a possible link between Fast Radio Bursts and giant pulses.
Pulsar Searches with the SKA
Authors: Levin L. , Armour W. , Baffa C. , Barr E. , Cooper S. , Eatough R. , Ensor A. , Giani E. , Karastergiou A. , Karuppusamy R. , Keith M. , Kramer M. , Lyon R. , Mackintosh M. , Mickaliger M. , van Nieuwpoort R , Pearson M. , Prabu T. , Roy J. , Sinnen O. , Spitler L. , Spreeuw H. , Stappers B. W. , van Straten W. , Williams C. , Wang H. , Wiesner K. ,   the SKA TDT team
Published: June 2018

The Square Kilometre Array will be an amazing instrument for pulsar astronomy. While the full SKA will be sensitive enough to detect all pulsars in the Galaxy visible from Earth, already with SKA1, pulsar searches will discover enough pulsars to increase the currently known population by a factor of four, no doubt including a range of amazing unknown sources. Real time processing is needed to deal with the 60 PB of pulsar search data collected per day, using a signal processing pipeline required to perform more than 10 POps. Here we present the suggested design of the pulsar search engine for the SKA and discuss challenges and solutions to the pulsar search venture.
The glitch activity of rotation-powered pulsars
Authors: Fuentes J. R. , Espinoza C. M. , Reisenegger A.
Published: June 2018

A statistical study of the glitch population and the behavior of the glitch activity across the known population of neutron stars is presented. A constant ratio between the glitch activity and the spin-down rate $\dot{\nu }_{\rm {g}}$/|$\dot{\nu }$| = 0.010 ± 0.001 is consistent with the behavior of all rotation-powered pulsars and magnetars. This relation is dominated by large glitches (Δν ≳ 10 μ Hz), which occur at a rate directly proportional to |$\dot{\nu }$|. The only exception are the rotation-powered pulsars with the highest values of |$\dot{\nu }$|, such as the Crab pulsar and PSR B0540–69, which exhibit a much smaller glitch activity, intrinsically different from each other and from the rest of the population. This contribution is based on the work done by Fuentes et al. (2017) “The glitch activity of neutron stars”, accepted for publication in A&A.
On the patchiness of the individual pulse spectra at the very low radio frequencies
Authors: Song Xiaoxi , Kondratiev Vladislav , Bilous Anna
Published: June 2018

We have used sensitive LOw Frequency ARray (LOFAR) observations of PSR B0809+74 at 15–62 MHz to study the anomalously intensive pulses, first reported by Ulyanov et al. (2006) at 18–30 MHz. Similarly to Ulyanov et al., we found that the spectra of strong pulses consist of distinct bright patches. Moreover, these spectral patches were spotted to drift upwards in frequency over the course of several pulse sequences. We established that this drift is not pulsar-intrinsic, but is caused by the broadband ~20 second-long enhancements of recorded signal, which influenced the dispersed tracks of several pulses at once. We speculate on the cause of such enhancements (i.e. propagation or telescope-related) and the ramifications they bring to the single-pulse studies at the very low radio frequencies. Depending on the origin, the phenomenon may also affect the analysis of highly dispersed single pulses at higher radio frequencies, e.g. Fast Radio Bursts.
Equation of state and pulsar death line
Authors: Zhou Xia
Published: June 2018

In this proceeding, we are going to introduce our recent work about the dependence of pulsar death line on the equation of state (Zhou et al. 2017). The results show that the equation of state affects the location of the pulsar death line in the P-Ṗ diagram. We offer another point of view to understand the pulsar death line and multiple observational facts would help us to reveal the nature of pulsars.
Testing the Universality of Free Fall with the Triple System J0337+1715
Authors: Archibald A. M. , Gusinskaia N. V. , Hessels J. W. T. , Lorimer D. R. , Lynch R. S. , Ransom S. M. , Stairs I. H.
Published: June 2018

The millisecond pulsar PSR J0337+1715 is in a mildly relativistic hierarchical triple system with two white dwarfs. This offers the possibility of testing the universality of free fall: does the neutron star fall with the same acceleration as the inner white dwarf in the gravity of the outer white dwarf? We have carried out an intensive pulsar timing campaign, yielding some 27000 pulse time-of-arrival (TOA) measurements with a median uncertainty of 1.2 μs. Here we describe our analysis procedure and timing model.
Organised polarisation variability in radio pulsars and consequences for emission theory
Authors: Ilie Cristina-Diana , Weltevrede Patrick
Published: June 2018

The aim of this work is to explore the connection between variability in single pulse intensity and periodic switching of the position angle (PA) of the linear polarisation and how this relates to the radio emission mechanism. There are five pulsars reported in the literature for which the PA is seen to periodically change in tandem with the variability in their pulse shapes. This behaviour is seemingly incompatible with two well established models of the radio emission mechanism. The purpose of this study is to investigate in a systematic way whether this phenomenon is common or if only happens in special cases, using a high-quality sample of pulsar data observed with the Parkes telescope. We show that the connection between polarisation variability and intensity variability is more common than previously expected.
Multi-frequency scatter-broadening evolution of pulsars
Authors: Krishnakumar M. A. , Joshi Bhal Chandra , Manoharan P. K.
Published: June 2018

In this paper, we present our study on multi-frequency scatter-broadening observations of a large sample of pulsars, made using the Ooty Radio Telescope (ORT) and the Giant Metrewave Radio Telescope (GMRT). For each pulsar, the scatter-broadening time scales (τsc) have been estimated at different observing frequencies and the dependence of τsc with the observing frequency, i.e., the frequency scaling index (α) has been obtained. We report estimates of α for a set of 39 pulsars, of which 31 are completely new and provide the first-time measurement on about 50% of the sample. This enhanced sample suggests that almost 65% of the pulsars have an α much lower than the conventional value of 4.4 for a Kolmogorov type turbulence spectrum, and a considerably large scattering strength. An increase in scattering strength is observed with the distance to the pulsar in the Galaxy.
The Magnetoionic Universe: Timing, Bursts, and SETI
Authors: Cordes James M.
Published: June 2018

Propagation effects have been central to pulsar research and indeed were an integral part of the pulsar discovery and its prologue. I will summarize the early deduction process for establishing pulsar distances and refinements to the distance scale and modeling of the Galaxy in electron density and magnetic field. This will lead to the analogous current situation of understanding distances and media for extragalactic radio bursts. The role of magnetoionic media in precision pulsar timing and surveys for transients will be summarized. Finally, going full circle, searches for extraterrestrial intelligence (LGMs) also require attention to propagation effects.
Scintillation Arcs Shed Light on Scattering from Planar Plasma Sheets
Authors: Stinebring Daniel R.
Published: June 2018

Scintillation arcs provide an unprecedented degree of detail into the scattering of radio waves from pulsars. We review evidence that has emerged over the last fifteen years that: a) the scattering of many nearby pulsars is dominated by one or several relatively thin “screens” of material, b) the resulting image on the sky is highly linear, with axial ratios at least as high as 10:1, and c) this arrangement is persistent for at least one source (B1133+16) for at least 25 years. We expand on the idea of Pen and Levin (2014) and previous authors that such scattering may be caused by linear sheets of plasma seen nearly edge-on. Further analysis of such scintillation arcs, including new work on multi-frequency, multi-epoch observations, should help elucidate the astrophysical nature of these ubiquitous scattering entities, which are currently not convincingly linked with any known structures.
X-Ray and Optical Properties of Black Widows and Redbacks
Authors: Roberts Mallory S.E. , Al Noori Hind , Torres Rodrigo A. , McLaughlin Maura A. , Gentile Peter A. , Hessels Jason W.T. , Ransom Scott M. , Ray Paul S. , Kerr Matthew , Breton Rene P.
Published: June 2018

Black widows and redbacks are binary systems consisting of a millisecond pulsar in a close binary with a companion having matter driven off of its surface by the pulsar wind. X-rays due to an intrabinary shock have been observed from many of these systems, as well as orbital variations in the optical emission from the companion due to heating and tidal distortion. We have been systematically studying these systems in radio, optical and X-rays. Here we will present an overview of X-ray and optical studies of these systems, including new XMM-Newton and NuStar data obtained from several of them, along with new optical photometry.
Effects of the Crustal Magnetic Fields and Changes in the IMF Orientation on the Magnetosphere of Mars: MAVEN Observations and LatHyS Results
Authors: Romanelli N. , Modolo R. , Leblanc F. , Chaufray J‐Y. , Hess S. , Brain D. , Connerney J. , Halekas J. , Mcfadden J. , Jakosky B.
Published: June 2018

The Mars Atmosphere and Volatile EvolutioN Mission (MAVEN) is currently probing the complex Martian environment. Although main structures arising from the interaction between the solar wind (SW) and the induced magnetosphere of Mars can be described using a steady state picture, time‐dependent physical processes modify the response of this obstacle. These processes result from temporal variabilities in the internal and/or external electromagnetic fields and plasma properties. Indeed, the crustal magnetic fields (CF) rotation constantly modifies the intrinsic magnetic field topology relative to the SW. Moreover, the magnetosphere's state is also modified by changes in the interplanetary magnetic field (IMF). In this work we analyze MAVEN magnetic field and plasma measurements obtained on 23 December 2014, between 06:00 UT and 14:15 UT. These measurements suggest that the external conditions remained approximately constant when MAVEN was inside the magnetosphere during the first orbit. In contrast, MAVEN observed changes in the IMF orientation before visiting the magnetosphere during the second orbit. To investigate the response of the Martian plasma environment to the CF rotation and IMF variability, we also perform hybrid simulations, using MAVEN observations to set SW external conditions. Simulation results are compared with the MAVEN measurements and show good agreement. Associated recovery timescales of different magnetospheric regions are found to range between ∼ 10 s and ∼ 10 min. Finally, we do not observe large variability in the total planetary H+ and O+ escape rates at different times during this event, although a correlation between the latter and the CF location is identified.