bluuebunny/crossref_metadata_2025 huggingface dataset:
A horse and a zebra: an atypical clinical picture including Guillain-Barré syndrome, recurrent fever and mesenteric lymphadenopathy caused by two concomitant infections
Authors: Amereller Felix , Lottspeich Christian , Buchholz Grete , Dichtl Karl
Published: March 2020

Background

WhileCampylobacter jejunirepresents the most common cause of bacterial gastroenteritis,Yersinia pseudotuberculosisinfections are very rarely diagnosed in adults.

Case

We report on a previously healthy patient who presented several times at our hospital with fever, Guillain-Barré syndrome, recurrent abdominal symptoms and distinct mesenteric lymphadenopathy, respectively. This complicated and diagnostically challenging course of disease was caused by aC. jejuniandY. pseudotuberculosiscoinfection. Antibiotic treatment with doxycycline was effective.

Conclusion

Broad serology testing was crucial to discover that two concomitant infections were causing the symptoms. This case demonstrates that when a clinical picture is not fully explained by one known infection, another infection with the same underlying risk factor has to be considered, hence “a horse and a zebra”.
A Design Approach for a Valve Based on a Magnetic Shape Memory Actuator
Authors: Effner Annabell , Zawada Tobias , Weber Jürgen
Published: March 2020

With the motivation to meet the increasing requirements on fast-switching pneumatic valves, Magnetic Shape Memory alloys (MSM) are considered as a promising alternative to conventional actuators. Regarding the desired strokes, forces and actuation frequencies MSM alloys meet the requirements best among other solid-state transducers for valve applications. However, the hysteresis in the magneto-mechanical behavior is challenging during the sizing process of a component based on an MSM actuator. It has proved to be valuable to apply a system simulation including a lumped element model of the MSM element in the early design phase. In this contribution, a design approach for the valve based on an MSM actuator is shown. A system network model was used to design a functional prototype of the valve to achieve the specifications defined within a requirements analysis. These specifications were derived from characteristic features of conventional established fast-switching pneumatic valve. The analysis of the subsystems was done to exploit the deviations and their influences on the system behavior. Furthermore, the experimental research of the functional prototype of the valve was carried out to check for functionality and to evaluate whether the specifications were met. A nominal volume flow of 120 Nl/min was reached at a supply Voltage $$U$$U of $$48\;{\text{V}}$$48V and current $$i$$i of $$7.6\;{\text{A}}$$7.6A which exceeds the aim of 100 Nl/min. By means of an optimization of the actuators geometry the response time could be reduced to less than $$1\;{\text{ms}}$$1ms. The desired maximum modular dimension of 9 mm was not achieved by the functional prototype due to the available production process, but would be feasible with series production.
Experimental study of road deicing by using the urban groundwater under the climatic condition of Nuremberg city, Germany
Authors: Baumgärtel Sebastian , Rohn Joachim , Luo Jin
Published: March 2020

Traffic accidents caused by heavy icing and snowing kept increasing in Germany in recent years, and many deicing methods were therefore developed. These methods either harm the environment (deicing salt) or damage roads (snowplows). As an alternative, the heating of roads using electricity or heated water has been proposed. This study considers the direct use of groundwater for road deicing in urban centers. The climatic and hydrological setting of Nuremberg city is referenced for a testing setup inside a cooling chamber using concrete slabs to test inlet water temperatures under different ambient temperatures. They were designed with 100 mm and 200 mm coil distance and both with an installation depth of around 40 mm. Additionally, an outside test field in a similar fashion is built to validate the measurements inside a chamber. The experiments indicated that a groundwater temperature of 10 °C is sufficient to keep the surface ice-free in typical winter days in the study area. Furthermore, the snow did not accumulate on the outside test field during snowfall events. The usability of this heating method could, therefore, be recommended for road deicing under such climatic condition.
Theoretical study of the adiponectin receptors: binding site characterization and molecular dynamics of possible ligands for drug design
Authors: Muratore Massimo , Komai Ali M.
Published: March 2020

The two adiponectin receptors (AdipoR1 and AdipoR2) have been implicated in glucose and lipid regulation involved in several metabolic pathologies including type II diabetes. Their exact biochemical functions and mechanisms remain poorly understood. Moreover, these receptors do not yet have data on possible co-crystallized active ligands. In this study, we applied different computational methodologies to address three main unanswered questions: first, the localization and validation of possible binding sites; second, the generation of novel ligands with amenable characteristics to target the receptors; and third, the determination of important chemical interactions between the ligands and the receptors. Computational analysis of the binding site reveals that the residues triad R267, F271, and Y310 could be responsible for changes in the spatial arrangement and geometry of the binding pocket in AdipoR1. Molecular docking results in high docking scores of − 13.6 and − 16.5 kcal/mol for the top best ligands in AdipoR1 and AdipoR2 respectively. Finally, molecular dynamics suggests that hydrolytic activity may be possible with these compounds and that this reaction could be mediated by aspartic acid residues. The two adiponectin receptors have an endogenous protein ligand, adiponectin. However the synthesis is expensive and technically challenging. Although some debatable agonists have been proposed investigations of suitable synthetic ligands are indeed, very much needed for targeting these receptors and their associate pathologies and metabolic pathways. Furthermore, these findings provide a framework for further biochemical investigations of amenable compounds for drug discovery in order to target these receptors and their associated pathologies.
Understanding the first year of novice school counsellors
Authors: Atli Abdullah
Published: March 2020

Previous research shows that the first year of a school counsellor’s career is one of the most critical stages. However, despite this importance, there is a limited number of studies that examine what novice school counsellors experience during their first year. The primary purpose of this qualitative study is to examine in detail the common experiences of novice school counsellors who have worked the first year of their professional career and to explore comprehensive themes regarding these experiences. Following a purposive sampling strategy, 33 school counsellors who started their profession in 19 different cities of Turkey were interviewed. As a result of the thematic analysis, five major themes emerged describing the first-year experiences of school counsellors: ‘Introduction’, ‘Fighting against Prejudices’, ‘Organising Counselling Service Room’, ‘Incongruence between Training and Work Definitions’, and ‘Longing for College Years’.
Assessment of academic difficulties in culturally and linguistically diverse school students
Authors: Velasco Leon Azucena , Campbell Marilyn
Published: March 2020

The increasing tendency of immigration and forced migration practices around the world has made countries’ populations culturally and linguistically diverse. Australia is considered one of the most culturally diverse countries in the world. Consequently, the proportion of school-aged children with different culture and language is also increasing. Thus, school psychologists and guidance counsellors face the challenge of designing fair assessment practices and sound interventions for culturally and linguistically diverse (CALD) students who experience difficulties with their learning. Although many multicultural countries have extensive research regarding the assessment of learning difficulties in CALD students, Australia lacks this research. This study explored the most common assessment strategies that school psychologists and guidance counsellors usually implement in their assessment of CALD students. These results were then compared to a best practice model from the literature. In order to understand the current practices of school psychologists and counsellors in Australia who have assessed CALD children, a survey was administered to 34 school psychologists and counsellors. It was found that the reported strategies and protocols were very close to the ones proposed by experts, which was an unexpected outcome of this study. Implications for school psychologists and counsellors are discussed.
A possible Cambrian stem-group gnathiferan-chaetognath from the Weeks Formation (Miaolingian) of Utah
Authors: Conway Morris Simon , Smith Ru D.A. , Cuthill Jennifer F. Hoyal , Bonino Enrico , Lerosey-Aubril Rudy
Published: March 2020

In recent years the plethora of ‘weird wonders,’ the vernacular for the apparently extinct major body plans documented in many of the Cambrian Lagerstätten, has been dramatically trimmed. This is because various taxa have been either assigned to known phyla or accommodated in larger monophyletic assemblages. Nevertheless, a number of Cambrian taxa retain their enigmatic status. To this intriguing roster we add Dakorhachis thambus n. gen. n. sp. from the Miaolingian (Guzhangian) Weeks Formation Konservat-Lagerstätte of Utah. Specimens consist of an elongate body that lacks appendages but is apparently segmented. A prominent feeding apparatus consists of a circlet of triangular teeth, while posteriorly there are three distinct skeletal components. D. thambus is interpreted as an ambush predator and may have been partially infaunal. The wider affinities of this new taxon remain conjectural, but it is suggested that it may represent a stem-group member of the Gnathifera, today represented by the gnathostomulids, micrognathozoans, and rotifers and possibly with links to the chaetognaths.

UUID: http://zoobank.org/22113e6b-f79e-4d06-9483-144618a61327
‘It gives you more to life, it's something new every day’: an Interpretative Phenomenological Analysis of wellbeing in older care home residents who keep a personal pet
Authors: Freedman Shoshanna , Paramova Petia , Senior Victoria
Published: March 2020

There is a substantial amount of literature that suggests that animals, and specifically animals kept as pets, can have a positive effect on wellbeing. Research exploring the impact of animals on wellbeing in care homes mainly concerns visiting animals as well as shared communal pets. In light of the lack of research regarding personal pets in care homes, the aim of this study was to explore what the experience of keeping a personal pet in a care home means for residents’ sense of wellbeing. Semi-structured interviews were conducted with seven care home residents who were currently living with their pet in a care home. Interviews were analysed using Interpretative Phenomenological Analysis (IPA). Analysis revealed four master themes deemed to be relevant to participants’ wellbeing. these were: ‘sense of self and identity’, ‘responsibility and ownership’, ‘motivation and desire to live’ and ‘feeling content in the care home’. The analysis indicated that living with a personal pet in a care home has the potential to enhance residents’ wellbeing. At the same time, it also found that the benefits of keeping a personal pet may be dependent on specific circumstances, such as the attitudes of staff and fellow residents at the care home. This study indicates that it may be advisable for more care homes to accept personal pets.
A NEW MULTILEVEL MODELING APPROACH FOR CLUSTERED SURVIVAL DATA
Authors: Xu Jinfeng , Yue Mu , Zhang Wenyang
Published: March 2020

In multilevel modeling of clustered survival data, to account for the differences among different clusters, a commonly used approach is to introduce cluster effects, either random or fixed, into the model. Modeling with random effects may lead to difficulties in the implementation of the estimation procedure for the unknown parameters of interest because the numerical computation of multiple integrals may become unavoidable when the cluster effects are not scalars. On the other hand, if fixed effects are used, there is a danger of having estimators with large variances because there are too many nuisance parameters involved in the model. In this article, using the idea of the homogeneity pursuit, we propose a new multilevel modeling approach for clustered survival data. The proposed modeling approach does not have the potential computational problem as modeling with random effects, and it also involves far fewer unknown parameters than modeling with fixed effects. We also establish asymptotic properties to show the advantages of the proposed model and conduct intensive simulation studies to demonstrate the performance of the proposed method. Finally, the proposed method is applied to analyze a dataset on the second-birth interval in Bangladesh. The most interesting finding is the impact of some important factors on the length of the second-birth interval variation over clusters and its homogeneous structure.
Humanitarian makerspaces in crisis-affected communities
Authors: Corsini Lucia , Moultrie James
Published: March 2020

There is an increasing demand for humanitarian aid around the world. At the same time, the number of makerspaces has been growing exponentially. Recently, the humanitarian sector has become interested in how these new design spaces can help crisis-affected populations. Despite the emergence of humanitarian makerspaces, there is little research to date that documents their outcomes and impacts. A multi-case study approach is taken to analyze three makerspaces that support migrants, refugees, and asylum seekers in Greece. A maturity grid tool is used to show that humanitarian makerspaces are driving impact in six key areas. The study underlines how these makerspaces support different design activities and have different outcomes. It also considers the challenges which are preventing humanitarian makerspaces from achieving their ultimate goals, drawing attention to the need for an enabling ecosystem in both the local and humanitarian context. This research brings clarity to the poorly understood phenomenon of humanitarian makerspaces and highlights the important role of design in humanitarian interventions. It also reveals practical insights for humanitarian organizations who are considering setting up makerspaces in crisis-affected communities.
A review of the risk margin – Solvency II and beyond
Authors: Pelkiewicz A. J. , Ahmed S. W. , Fulcher P. , Johnson K. L. , Reynolds S. M. , Schneider R. J. , Scott A. J.
Published: March 2020

For life insurers in the United Kingdom (UK), the risk margin is one of the most controversial aspects of the Solvency II regime which came into force in 2016.

The risk margin is the difference between the technical provisions and the best estimate liabilities. The technical provisions are intended to be market-consistent, and so are defined as the amount required to be paid to transfer the business to another undertaking. In practice, the technical provisions cannot be directly calculated, and so the risk margin must be determined using a proxy method; the method chosen for Solvency II is known as the cost-of-capital method.

Following the implementation of Solvency II, the risk margin came under considerable criticism for being too large and too sensitive to interest rate movements. These criticisms are particularly valid for annuity business in the UK – such business is of great significance to the system for retirement provision. A further criticism is that mitigation of the impact of the risk margin has led to an increase in reinsurance of longevity risks, particularly to overseas reinsurers.

This criticism has led to political interest, and the risk margin was a major element of the Treasury Committee inquiry into EU Insurance Regulation.

The working party was set up in response to this criticism. Our brief is to consider both the overall purpose of the risk margin for life insurers and solutions to the current problems, having regard to the possibility of post-Brexit flexibility.

We have concluded that a risk margin in some form is necessary, although its size depends on the level of security desired, and so is primarily a political question.

We have reviewed possible alternatives to the current risk margin, both within the existing cost-of-capital methodology and considering a wide range of alternatives.

We believe that requirements for the risk margin will depend on future circumstances, in particular relating to Brexit, and we have identified a number of possible changes to methodology which should be considered, depending on circumstances.
Families among the Hildas and Trojans
Authors: Vinogradova Tamara A.
Published: March 2020

A search for asteroid families among the Hildas and Jupiter Trojans was performed with the use of a new set of proper elements. The proper elements were calculated by the empirical method. Besides well known families, several new probable families were found in addition.
Observation of 44(Nysa) Asteroid by IST60 Telescope
Authors: Canbay Remziye , Gursoy Fulin
Published: March 2020

In this study, the main belt asteroid (44) Nysa, which is also a known member of the Nysian asteroid family, was observed by IST60 telescope. The orbital elements were compared with MPO(Minor Planet Center) and NASA Horizons Web-Interface results.
Environmental dependence of radio galaxy populations
Authors: Shabala Stanislav S.
Published: March 2020

Sensitive continuum surveys with next-generation interferometers will characterise large samples of radio sources at epochs during which cosmological models predict feedback from radio jets to play an important role in galaxy evolution. Dynamical models of radio sources provide a framework for deriving from observations the radio jet duty cycles and energetics, and hence the energy budget available for feedback. Environment plays a crucial role in determining observable radio source properties, and I briefly summarise recent efforts to combine galaxy formation and jet models in a self-consistent framework. Galaxy clustering estimates from deep optical and NIR observations will provide environment measures needed to interpret the observed radio populations.
Understanding mechanical feedback from HERGs and LERGs
Authors: Whittam Imogen H.
Published: March 2020

The properties of ∼ 1000 high-excitation and low-excitation radio galaxies (HERGs and LERGs) selected from the Heywood et al. (2016) 1 – 2 GHz VLA survey of Stripe 82 are investigated. The HERGs in this sample are generally found in host galaxies with younger stellar populations than LERGs, consistent with other work. The HERGs tend to accrete at a faster rate than the LERGs, but there is more overlap in the accretion rates of the two classes than has been found previously. We find evidence that mechanical feedback may be significantly underestimated in hydrodynamical simulations of galaxy evolution; 84 % of this sample release more than 10 % of their energy in mechanical form. Mechanical feedback is significant for many of the HERGs in this sample as well as the LERGs; nearly 50 % of the HERGs release more than 10 % of their energy in their radio jets.
Magnetic field structures in star-forming regions revealed by imaging polarimetry at multi-wavelengths
Authors: Kwon Jungmi
Published: March 2020

Magnetic fields are ubiquitous in various scales of astronomical objects, and they are considered as playing significant roles from star to galaxy formations. However, the role of the magnetic fields in star forming regions is less well understood because conventional optical polarimetry is hampered by heavy extinction by dust. We have been conducting extensive near-infrared polarization survey of various star-forming regions from low- and intermediate-mass to high-mass star-forming regions, using IRSF/SIRPOL in South Africa. Not only linear but also circular polarizations have been measured for more than a dozen of regions. Both linear and circular polarimetric observations at near-infrared wavelengths are useful tools to study the magnetic fields in star forming regions, although infrared circular polarimetry has been less explored so far. In this presentation, we summarize our results of the near-infrared polarization survey of star forming regions and its comparison with recent submillimeter polarimetry results. Such multi-wavelength approaches can be extended to the polarimetry using ALMA, SPICA in future, and others. We also present our recent results of the first near-infrared imaging polarimetry of young stellar objects in the Circinus molecular cloud, which has been less studied but a very intriguing cluster containing numerous signs of active low-mass star formation.
The role of magnetic fields in the early stages of star formation
Authors: Galametz Maud , Maury Anaëlle , Valdivia Valeska
Published: March 2020

Magnetic fields are believed to redistribute part of the angular momentum during the collapse and could explain the order-of-magnitude difference between the angular momentum observed in protostellar envelopes and that of a typical main sequence star. The Class 0 phase is the main accretion phase during which most of the final stellar material is collected on the central embryo. To study the structure of the magnetic fields on 50-2000 au scales during that key stage, we acquired SMA polarization observations (870μm) of 12 low-mass Class 0 protostars. In spite of their low luminosity, we detect dust polarized emission in all of them. We observe depolarization effects toward high-density regions potentially due to variations in alignment efficiency or in the dust itself or geometrical effects. By comparing the misalignment between the magnetic field and the outflow orientation, we show that the B is either aligned or perpendicular to the outflow direction. We observe a coincidence between the misalignment and the presence of large perpendicular velocity gradients and fragmentation in the protostar (Galametz et al. 2018). Our team is using MHD simulations combined with the radiative transfer code POLARIS to produce synthetic maps of the polarized emission. This work is helping us understand how the magnetic field varies from the large-scale to the small-scales, quantify beam-averaging biases and study the variations of the polarization angles as a function of wavelength or the assumption made on the grain alignment (see poster by Valdivia).
The impact of non-ideal effects on the circumstellar disk evolution and their observational signatures
Authors: Tsukamoto Y. , Okuzumi S. , Iwasaki K. , Machida M. N. , Inutsuka S.
Published: March 2020

It has been recognized that non-ideal MHD effects (Ohmic diffusion, Hall effect, ambipolar diffusion) play crucial roles for the circumstellar disk formation and evolution. Ohmic and ambipolar diffusion decouple the gas and the magnetic field, and significantly reduces the magnetic torque in the disk, which enables the formation of the circumstellar disk (e.g., Tsukamoto et al. 2015b). They set an upper limit to the magnetic field strength of ∼ 0.1 G around the disk (Masson et al. 2016). The Hall effect notably changes the magnetic torques in the envelope around the disk, and strengthens or weakens the magnetic braking depending on the relative orientation of magnetic field and angular momentum. This suggests that the bimodal evolution of the disk size possibly occurs in the early disk evolutionary phase (Tsukamoto et al. 2015a, Tsukamoto et al. 2017). Hall effect and ambipolar diffusion imprint the possibly observable characteristic velocity structures in the envelope of Class 0/I YSOs. Hall effect forms a counter-rotating envelope around the disk. Our simulations show that counter rotating envelope has the size of 100–1000 au and a recent observation actually infers such a structure (Takakuwaet al. 2018). Ambipolar diffusion causes the significant ion-neutral drift in the envelopes. Our simulations show that the drift velocity of ion could become 100-1000 ms–1.
Magnetically regulated collapse in the B335 protostar ?
Authors: Maury A. J. , Girart J. M. , Zhang Q.
Published: March 2020

The role of the magnetic field during protostellar collapse is still poorly constrained from an observational point of view, and only few constraints exist that shed light on the magnetic braking efficiency during the main accretion phase. I presented our ALMA polarimetric observations of the thermal dust continuum emission at 1.3 mm, towards the B335 Class 0 protostar (Maury et al. 2018a). Linearly polarized dust emission is detected at all scales probed by our observations (50 to 1000 au). The magnetic field structure has a very ordered topology in the inner envelope, with a transition from a large-scale poloidal magnetic field, in the outflow direction, to strongly pinched in the equatorial direction. We compared our data to a family of magnetized protostellar collapse models. We show that only models with an initial core mass-to-flux ratio μ∼5-6 are able to reproduce the observed properties of B335, especially the upper-limits on its disk size, its large-scale envelope rotation β and the pronounced magnetic field lines pinching observed in our ALMA data. In these MHD models, the magnetic field is dynamically relevant to regulate the typical outcome of protostellar collapse, suggesting a magnetically-regulated disk formation scenarios is at work in B335.
Twinkle little stars: Massive stars are quenched in strong magnetic fields
Authors: Tabatabaei Fatemeh S. , Almudena Prieto M. , Fernández-Ontiveros Juan A.
Published: March 2020

The role of the magnetic fields in the formation and quenching of stars with different mass is unknown. We studied the energy balance and the star formation efficiency in a sample of molecular clouds in the central kpc region of NGC 1097, known to be highly magnetized. Combining the full polarization VLA/radio continuum observations with the HST/Hα, Paα and the SMA/CO lines observations, we separated the thermal and non-thermal synchrotron emission and compared the magnetic, turbulent, and thermal pressures. Most of the molecular clouds are magnetically supported against gravitational collapse needed to form cores of massive stars. The massive star formation efficiency of the clouds also drops with the magnetic field strength, while it is uncorrelated with turbulence (Tabatabaei et al. 2018). The inefficiency of the massive star formation and the low-mass stellar population in the center of NGC 1097 can be explained in the following steps: I) Magnetic fields supporting the molecular clouds prevent the collapse of gas to densities needed to form massive stars. II) These clouds can then be fragmented into smaller pieces due to e.g., stellar feedback, non-linear perturbations and instabilities leading to local, small-scale diffusion of the magnetic fields. III) Self-gravity overcomes and the smaller clouds seed the cores of the low-mass stars.
Magnetic field detections in Herbig Ae SB2 systems
Authors: Järvinen S. P. , Hubrig S. , Carroll T. A. , Schöller M. , Ilyin I.
Published: March 2020

Studies of the presence of magnetic fields in Herbig Ae/Be stars are extremely important because they enable us to improve our insight into how the magnetic fields of these stars are generated and how they interact with their environment, including their impact on the planet formation process and the planet-disk interaction. We report new detections of weak mean longitudinal magnetic fields in the close Herbig Ae double-lined spectroscopic binary AK Sco and in the presumed spectroscopic Herbig Ae binary HD 95881 (Järvinen et al. 2018) based on observations obtained with HARPSpol attached to ESO’s 3.6 m telescope. Such studies are important because only very few close spectroscopic binaries with orbital periods below 20 d are known among Herbig Ae stars. Our detections favour the conclusion that the previously suggested low incidence (5-10%) of magnetic Herbig Ae stars can be explained by the weakness of these fields and the limited accuracy of the published measurements. The search for magnetic fields and the determination of their geometries in close binary systems will play an important role for understanding the mechanisms that are responsible for the magnetic field generation.
How to identify magnetic field activity in young circumstellar disks
Authors: Flock Mario , Bertrang Gesa H.-M.
Published: March 2020

Recent advanced simulations of protoplanetary disks allow us to search for observational constraints to identify the magnetic field activity in protoplanetary disks. With our 3D radiation non-ideal magneto-hydrodynamical (MHD) models including irradiation from an Herbig type star we are able to model the thermal and dynamical evolution in a so far never reached detail (Flock et al. 2017). The activity of the magneto-rotational instability in the inner hot ionized regions comes along with a magnetic dynamo. The oscillations in the mean toroidal magnetic field with a timescale of 10 local orbits can slightly bend the inner dust rim and so the irradiation surface. This causes a clear variability pattern in the near infrared (NIR) emission at the dust inner rim surface. Another way to identify the presence of magnetic fields are to search for polarization signatures. Using 3D non-ideal MHD simulations of the outer disk regions (Flock et al. 2015) we calculate synthetic images of the intrinsically polarized continuum emitted by aspherical grain aligned with the dominantly toroidal magnetic field (Bertrang et al. 2017). Our results show a clear radial polarization pattern for face-on observed disk, similar to recent observations by Ohashi et al. (2018). Additionally, we are even able to see the change of the polarization pattern inside the vortex as the poloidal magnetic field dominates therein.
An abundance analysis of AK Sco, a Herbig Ae SB2 system with a magnetic component
Authors: Hubrig Swetlana , Castelli Fiorella , Järvinen Silva P.
Published: March 2020

AK Sco is an SB2 system formed by two nearly identical Herbig Ae stars, with Teff = 6500K and log g = 4.5, surrounded by a circumbinary disk. This actively accreting system is of special interest among the pre-main-sequence binaries because of its prominent ultraviolet excess and the high eccentricity of its orbit. Moreover, recent spectropolarimetric observations using HARPSpol indicate the presence of a weak magnetic field in the secondary component (Järvinen et al. 2018). An abundance analysis of both components has shown that all elements have a solar abundance in the two stars, except for Li and Ba. These elements are enhanced by 2.2 and 0.5 dex, respectively, in the A component and by 2.4 and 0.5 dex, respectively, in the B component.
Two Different Grain Distributions within the Protoplanetary Disk around HD 142527
Authors: Ohashi Satoshi , Kataoka Akimasa , Nagai Hiroshi
Published: March 2020

The origin of polarized emission from protoplanetary disks is uncertain. Three mechanisms have been proposed for such polarized emission so far, (1) grain alignment with magnetic fields, (2) grain alignment with radiation gradients, and (3) self-scattering of thermal dust emission. Aiming to observationally identify the polarization mechanisms, we present ALMA polarization observations of the 0.87 mm dust continuum emission toward the circumstellar disk around HD 142527 with a spatial resolution of ∼0.2 arcsec as shown in Ohashi et al. (2018). We confirm that the polarization vectors in the northern region are consistent with self-scattering because of a flip of the polarization vectors. Furthermore, we show that the polarization vectors in the southern region are consistent with grain alignment by magnetic fields, although self-scattering cannot be ruled out. To understand these differences between the polarization mechanisms, we propose a simple grain size segregation model: small dust grains (
$\mathbin{\lower.3ex\hbox{$\buildrel<\over {\smash{\scriptstyle\sim}\vphantom{_x}}$}} $
100 microns) are dominant and aligned with magnetic fields in the southern region, and middle-sized (∼100 microns) grains in the upper layer emit self-scattered polarized emission in the northern region. The grain size near the middle plane in the northern region cannot be measured because the emission at 0.87 mm is optically thick. However, it can be speculated that larger dust grains (
$\mathbin{\lower.3ex\hbox{$\buildrel>\over {\smash{\scriptstyle\sim}\vphantom{_x}}$}} $
cm) may accumulate near this plane. These results are consistent with those of a previous analysis of the disk, in which large grain accumulation and optically thick emission from the northern region were found. This model is also consistent with theories where smaller dust grains are aligned with magnetic fields. We find that the magnetic fields are toroidal, at least in the southern region.
3D simulations of accretion onto a star: Fast funnel-wall accretion
Authors: Takasao Shinsuke , Tomida Kengo , Iwasaki Kazunari , Suzuki Takeru K.
Published: March 2020

We show the results of global 3D magnetohydrodynamics simulations of an accretion disk with a rotating, weakly magnetized central star (Takasao et al. 2018). The disk is threaded by a weak large-scale poloidal magnetic field. The central star has no strong stellar magnetosphere initially and is only weakly magnetized. We investigate the structure of the accretion flows from a turbulent accretion disk onto the star. Our simulations reveal that fast accretion onto the star at high latitudes is established even without a stellar magnetosphere. We find that the failed disk wind becomes the fast, high-latitude accretion as a result of angular momentum exchange mediated by magnetic fields. The rapid angular momentum exchange occurs well above the disk, where the Lorentz force that decelerates the rotational motion of gas can be comparable to the centrifugal force. Unlike the classical magnetospheric accretion model, fast accretion streams are not guided by magnetic fields of the stellar magnetosphere. Nevertheless, the accretion velocity reaches the free-fall velocity at the stellar surface owing to the efficient angular momentum loss at a distant place from the star. Our model can be applied to Herbig Ae/Be stars whose magnetic fields are generally not strong enough to form magnetospheres, and also provides a possible explanation why Herbig Ae/Be stars show indications of fast accretion.
Role of magnetic field in star formation
Authors: Kumssa Gemechu Muleta , Tessema Solomon Belay
Published: March 2020

Magnetic fields are a key component in star formation theories. Nevertheless, their exact role in the formation of stars is still a matter of debate. The process of angular momentum transportation by the disturbance caused during magnetic field reconnection still needs theoretical formulation in terms of the collapsing cloud’s parameters. The purposes of this study are: to model the critical mass of a magnetized, gravitating and turbulent star forming molecular cloud (MC) and to formulate the momentum carried out by a magnetic field through magnetic field reconnection in terms of the MC’s parameters. By applying theoretical modeling, we show how angular momentum transported via an Alfvén wave can be described in terms of mass, radius and dispersion velocity of a collapsing cloud core and a model equation of the critical mass for a gravitating, turbulent, and magnetized molecular cloud core. The outflow of angular momentum by magnetic fields facilitates the inflow of mass. On the other side, magnetic pressure prevents collapse. Therefore, magnetic fields have a dual purpose in the process of star formation. This momentum outflow triggers the inflow of mass to conserve angular momentum. The results show that Alfvén waves are like a machine that extracts angular momentum from a magnetized collapsing cloud core. Thus the total angular momentum transported by magnetic field at a distance R from the core’s center depends on the size, mass and turbulent velocity dispersion of the collapsing cloud core.
Zeeman Effect Observations in Class I Methanol Masers
Authors: Momjian Emmanuel , Sarma Anuj P.
Published: March 2020

We report the detection of the Zeeman effect in the 44 GHz Class I methanol maser line toward the star forming region DR21W. The 44 GHz methanol masers in this source occur in a ∼3” linear structure that runs from northwest to southeast, with the two dominant components at each end, and several weaker maser components in between. Toward a 93 Jy maser in the dominant northwestern component, we find a significant Zeeman detection of −23.4 ± 3.2 Hz. If we use the recently published result of Lankhaar et al. (2018) that the F=5-4 hyperfine transition is responsible for the 44 GHz methanol maser line, then their value of z = −0.92 Hz mG−1 yields a line-of-sight magnetic field of Blos =25.4 ± 3.5 mG. If Class I methanol masers are pumped in high density regions with n∼107–8 cm−3, then magnetic fields in these maser regions should be a few to several tens of mG. Therefore, our result in DR21W is certainly consistent with the expected values.

Using the above noted splitting factor in past Zeeman effect detections in Class I methanol masers reported by Sarma & Momjian (2011) and Momjian & Sarma (2017) in the star forming regions OMC-2 and DR21(OH) result in Blos values of 20.0 ± 1.2 mG and 58.2 ± 2.9 mG, respectively. These are also consistent with the expected values.
Terra-Astronomy – Understanding historical observations to study transient phenomena
Authors: Neuhäuser Ralph , Neuhäuser Dagmar L. , Posch Thomas
Published: March 2020

We give an overview of Focus Meeting 5 on the new field of Terra-Astronomy.
Cuneiform Descriptions of Transient Phenomena
Authors: Hunger H.
Published: March 2020

Sources from Ancient Mesopotamia contain mention of transient astronomical phenomena in two contexts: in records of observations, many of which can be dated, and in collections of omens, which use the appearance of such phenomena to predict future events. These omens consider quite a range of phenomena, but only rarely can they be dated in a precise way. This paper describes how transient phenomena were handled in both kinds of context.
Stellar metallicity gradients of the Milky Way disc from LAMOST
Authors: Xiang Maosheng
Published: March 2020

Stellar metallicity gradients set important constraints on the formation and evolution history of the Milky Way. We present radial and vertical metallicity gradients of the Galactic disc for mono-age stellar populations from the LAMOST Galactic Surveys, and discuss their constraints on the disc assemblage history.
The evolution of the Milky Way’s radial metallicity gradient as seen by APOGEE, CoRoT, and Gaia
Authors: Anders Friedrich , Minchev Ivan , Chiappini Cristina
Published: March 2020

The time evolution of the radial metallicity gradient is one of the most important constraints for Milky Way chemical and chemo-dynamical models. In this talk we reviewed the status of the observational debate and presented a new measurement of the age dependence of the radial abundance gradients, using combined asteroseismic and spectroscopic observations of red giant stars. We compared our results to state-of-the-art chemo-dynamical Milky Way models and recent literature results obtained with open clusters and planetary nebulae, and propose a new method to infer the past history of the Galactic radial abundance profile.
Metallicity gradients in intermediate-redshift absorption-selected galaxies
Authors: Christensen Lise , Rhodin Henrik , Møller Palle
Published: March 2020

. Metallicity gradients are most frequently investigated directly from galaxies observed in emission. We have shown that galaxies detected via strong quasar absorption lines also exhibits a metallicity gradient in the outskirts and circumgalactic medium out to ~40 kpc distance. We infer a metallicity gradient of −0.022 dex kpc−1 for absorption-selected systems at redshifts 0.1 z 3. Applying this metallicity gradient and a flattening of the gradient beyond 12 kpc, we demonstrate that absorption-selected galaxies obey the same mass-metallicity relation (MZR) as observed for luminosity-selected galaxies.
Capabilities of next generation telescopes for cosmic magnetism
Authors: Stil Jeroen M.
Published: March 2020

The next generation of radio telescopes offer significant improvement in bandwidth and survey speed. We examine the ability to resolve Faraday thick objects in Faraday space as a function of survey parameters. The necessary combination of λmax and λmin to resolve objects with modest Faraday thick components requires one or two surveys with instantaneous bandwidth 300 MHz to 750 MHz offered by next generation telescopes. For spiral galaxies, bandwidths in excess of 1.5 GHz are required. Correction for Galactic Faraday rotation must account for common gradients of order 10 rad m−2 per degree. How effective a new rotation measure grid is in probing the foreground depends on off-axis polarization calibration.
The Magnetized Disk-Halo Transition Region of M51
Authors: Kierdorf M. , Mao S. A. , Fletcher A. , Beck R. , Haverkorn M. , Basu A. , Tabatabaei F. , Ott J.
Published: March 2020

An excellent laboratory for studying large scale magnetic fields is the grand design face-on spiral galaxy M51. Due to wavelength-dependent Faraday depolarization, linearly polarized synchrotron emission at different radio frequencies gives a picture of the galaxy at different depths: Observations at L-band (1 – 2 GHz) probe the halo region while at C- and X-band (4 – 8 GHz) the linearly polarized emission probe the disk region of M51. We present new observations of M51 using the Karl G. Jansky Very Large Array (VLA) at S-band (2 – 4 GHz), where previously no polarization observations existed, to shed new light on the transition region between the disk and the halo. We discuss a model of the depolarization of synchrotron radiation in a multilayer magneto-ionic medium and compare the model predictions to the multi-frequency polarization data of M51 between 1 – 8 GHz. The new S-band data are essential to distinguish between different models. Our study shows that the initial model parameters, i.e. the total regular and turbulent magnetic field strengths in the disk and halo of M51, need to be adjusted to successfully fit the models to the data.
Recent progresses in the use of 3D MHD simulations for solar irradiance reconstructions
Authors: Criscuoli Serena
Published: March 2020

The use of 3D magneto-hydrodynamic simulations of the solar atmosphere in modeling irradiance variations seems a natural evolution of the current irradiance reconstruction techniques making use of one-dimensional, static, atmosphere models. Nevertheless, the development of such new models poses serious computational challenges. This contribution focuses on recent progresses made in the development of novel irradiance reconstruction models making use of 3D MHD simulations and discusses current and future challenges.
Solar irradiance: from multiple observations to a single composite
Authors: Dudok de Wit Thierry , Kopp Greg
Published: March 2020

We review recent developments in combining solar irradiance datasets from different instruments to obtain one single composite, which is the key to understanding how irradiance varies on decadal timescales and beyond.
Cycle-dependent and cycle-independent surface tracers of solar magnetic activity
Authors: Sokoloff D. D. , V. N.  , Obridko  , I. M.  , Livshits  , Shibalova A. S.
Published: March 2020

We consider several tracers of magnetic activity that separate cycle-dependent contributions to the background solar magnetic field from those that are independent of the cycle. The main message is that background fields include two relative separate populations. The background fields with a strength up to 100 Mx cm−2 are very poorly correlated with the sunspot numbers and vary little with the phase of the cycle. In contrast, stronger magnetic fields demonstrate pronounced cyclic behaviour. Small-scale solar magnetic fields demonstrate features of fractal intermittent behaviour, which requires quantification. We investigate how the observational estimate of the solar magnetic flux density B depends on resolution D in order to obtain the scaling In BD = −k In D + a in a reasonably wide range. The quantity k demonstrates cyclic variations typical of a solar activity cycle. k depends on the magnetic flux density, i.e. the ratio of the magnetic flux to the area over which the flux is calculated, at a given instant. The quantity a demonstrates some cyclic variation, but it is much weaker than in the case of k. The scaling is typical of fractal structures. The results obtained trace small-scale action in the solar convective zone and its coexistence with the conventional large-scale solar dynamo based on differential rotation and mirror-asymmetric convection. Here we discuss the message for solar dynamo studies hidden in the above results.
Nano dust in space and astrophysics
Authors: Mann Ingrid , Li Aigen , Tanaka Kyoko K.
Published: March 2020

The theme of this focus meeting is related to the detection, characterization and modeling of nano particles — cosmic dust of sizes of roughly 1 to 100 nm — in space environments like the interstellar medium, planetary debris disks, the heliosphere, the vicinity of the Sun and planetary atmospheres, and the space near Earth. Discussions focus on nano dust that forms from condensations and collisions and from planetary objects, as well as its interactions with space plasmas like the solar and stellar winds, atmospheres and magnetospheres. A particular goal is to bring together space scientists, astronomers, astrophysicists, and laboratory experimentalists and combine their knowledge to reach cross fertilization of different disciplines.
Standardization in the UV with Astrosat and its issues related to star cluster studies
Authors: Shah Priya
Published: March 2020

The Ultra-Violet Imaging Telescope (UVIT) is one of the payloads in Astrosat, the first Indian Space Observatory. The UVIT instrument has two 375 mm telescopes: one for the far-ultraviolet (FUV) channel (1300-1800 Å), and the other for the near-ultraviolet (NUV) channel (2000-3000 Å) and the visible (VIS) channel (3200-5500 Å). We shall discuss the issues with standardization in the UV with reference to Astrosat Observations (Cycle A04). I shall discuss the problems faced in data-analysis and how these in turn lead to serious issues dealing with the color-magnitude diagarms, membership and age of the young embedded clusters studied.
SCALA: Towards a physical calibration of CALSPEC standard stars based on a NIST-traceable reference for SNIFS
Authors: Küsters D. , Lombardo S. , Kowalski M. , Aldering G. , Boone K. , Copin Y. , Nordin J. , Rubin D.
Published: March 2020

SCALA is a physical calibration device for the SuperNova Integral Field Spectrograph (SNIFS), mounted to the University Hawaii 2.2m telescope on Mauna Kea. For type Ia supernova (SN Ia) cosmology programs, an improved fundamental calibration directly translates into improved cosmological constraints. The aim of SCALA is to perform a fundamental calibration of the CALSPEC (Bohlin 2014) standard stars, which are currently calibrated relative to white dwarf model atmospheres.