bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the Trusted‐Device Scenario in Continuous‐Variable Quantum Key Distribution
Authors: Laudenbach Fabian , Pacher Christoph
Published: August 2019

The assumption that detection and/or state preparation devices used for continuous‐variable quantum key distribution are beyond influence of potential eavesdroppers leads to a significant performance enhancement in terms of achievable key rate and transmission distance. A detailed and comprehensible derivation of the Holevo bound in this so‐called trusted‐device scenario is provided. Modeling an entangling‐cloner attack and using some basic algebraic matrix transformations, it is shown that the computation of the Holevo bound can be reduced to the solution of a quadratic equation. As an advantage of our derivation, the mathematical complexity of our solution does not increase with the number of trusted‐noise sources. Finally, a numerical evaluation of our results is provided, illustrating the counter‐intuitive fact that an appropriate amount of trusted‐receiver loss and noise can even be beneficial for the key rate.
Operationalizing the allocation of environmental flows: A U.K. perspective on Baxter's Schedule
Authors: Neachell Emma , Petts Geoff
Published: August 2019

Early attempts to gauge streams were used by George Baxter in 1961 to propose a pioneering scheme for deriving and allocating water for what today may be recognized as environmental flows in the United Kingdom, but the approach was not accepted into practice. A fundamental concern was the quality of river flow data. Stream gauging was advanced by the 1963 Water Resources Act, and prior to this, the allocation of water resources to compensation flows below dams was based on the basic principle of one third of the reliable yield, estimated using rainfall data. Despite the increased availability of river flow data since the 1970s, it is suggested that low‐flow data quality has severely constrained the management and allocation of water resources and remains so today. Today, pressures and demands on water resources are increasing, but the accuracy of low‐flow measurement is still hindering the operational determination and implementation of environmentally robust, seasonally variable environmental flows. Successful river regulation and restoration relate to a complex suite of public policy questions and given uncertainty over the quality of low‐flow data, transparent, pragmatic decisions about societal allocations of water need to be made.
Employing SysML to model and explore levels‐of‐service: The case of passenger comfort in railway transportation systems
Authors: Kotronis Christos , Nikolaidou Mara , Kapos George‐Dimitrios , Tsadimas Anargyros , Dalakas Vassilis , Anagnostopoulos Dimosthenis
Published: August 2019

The concept of Level of Service (LoS) is not inherently supported by Systems Modeling Language (SysML), the standard modeling notation for model‐based systems engineering. This paper describes and demonstrates an approach that enhances SysML to enable LoS modeling and evaluation. A SysML profile enables the definition and visual verification of LoS during system operation, via LoS specific requirements, inside the system model, and the association of these requirements with specific system components. Hence, static and dynamic aspects of the system model are used for the LoS verification, while specific design alternatives are automatically proposed, in case the desired LoS is not achieved. As a proof of concept, the proposed approach was applied to explore passenger comfort, a key LoS metric, indicating space available to passenger in Railway Transportation Systems (RTSs). A specific case study on passenger comfort for the Athens Metro was conducted to derive insights regarding the practical aspects of the proposed approach.
What We Must Learn From Children in Immigrant Families
Authors: Compton‐Lilly Catherine , Kim Jieun , Quast Erin , Tran Sarah , Shedrow Stephanie
Published: August 2019

The authors explore the intriguing transnational awareness demonstrated by young students from immigrant families. The authors argue that awareness is an important fund of knowledge and the foundation on which some students build an inclusive view of the world, a view that honors the humanity of people around the world. After exploring the transnational awareness of young students, the authors follow one student from first grade into high school. Adam is Muslim American, bilingual in Arabic and English, and learning French. He is an avid soccer player, but most of all, he has a perspective on the world that is expansive, inclusive, and curious. Adam has lessons to teach not only his peers but also his teachers.
Stereological transformation of pore size distributions with application to soft polymer and FDM‐printed specimens
Authors: Reppel Thomas , Korzeniowski Tim Fabian , Weinberg Kerstin
Published: August 2019

The presence of voids or cavities inside a material plays an important role in several applications. Recently, their investigation has gained attention to understand the effect of such inhomogeneities on 3D‐printed structures. Such structures could be already weakened due to the procedure of additive manufacturing. Voids can be visualized by computed tomography but practically a micrograph obtained by a planar cut through the material is simpler and cheaper. This requires, however, the reconstruction of the three‐dimensional distribution from statistical micrograph analyses. Here the reliability of such reconstruction is studied. To this end, spherical voids are considered whose size distribution can be characterized by one scalar number, e.g. the void radius. The corresponding distributions are typically positive right‐tailed, indicating more small than large voids. Following the work of S. D. Wicksell, the distributions of the observed planar cut are linked to the distribution of the spherical void size in space. The calculation of the stereological transformations is outlined in detail and several examples are provided to point on misleading conclusions. The presented analysis is applied to three typical soft‐polymer materials.
Towards the n-point one-loop superstring amplitude. Part III. One-loop correlators and their double-copy structure
Authors: Mafra Carlos R. , Schlotterer Oliver
Published: August 2019

Abstract

In this final part of a series of three papers, we will assemble supersymmetric expressions for one-loop correlators in pure-spinor superspace that are BRST invariant, local, and single valued. A key driving force in this construction is the generalization of a so far unnoticed property at tree-level; the correlators have the symmetry structure akin to Lie polynomials. One-loop correlators up to seven points are presented in a variety of representations manifesting different subsets of their defining properties. These expressions are related via identities obeyed by the kinematic superfields and worldsheet functions spelled out in the first two parts of this series and reflecting a duality between the two kinds of ingredients. Interestingly, the expression for the eight-point correlator following from our method seems to capture correctly all the dependence on the worldsheet punctures but leaves undetermined the coefficient of the holomorphic Eisenstein series G4. By virtue of chiral splitting, closed-string correlators follow from the double copy of the open-string results.
Two-loop massive quark jet functions in SCET
Authors: Hoang André H. , Lepenik Christopher , Stahlhofen Maximilian
Published: August 2019

Abstract

We calculate the O(

$$ {\alpha}_s^2 $$

α
s
2

) corrections to the primary massive quark jet functions in Soft-Collinear Effective Theory (SCET). They are an important ingredient in factorized predictions for inclusive jet mass cross sections initiated by massive quarks emerging from a hard interaction with smooth quark mass dependence. Due to the effects coming from the secondary production of massive quark-antiquark pairs there are two options to define the SCET jet function, which we call universal and mass mode jet functions. They are related to whether or not a soft mass mode (zero) bin subtraction is applied for the secondary massive quark contributions and differ in particular concerning the infrared behavior for vanishing quark mass. We advocate that a useful alternative to the common zero-bin subtraction concept is to define the SCET jet functions through subtractions related to collinear-soft matrix elements. This avoids the need to impose additional power counting arguments as required for zero-bin subtractions. We demonstrate how the two SCET jet function definitions may be used in the context of two recently developed factorization approaches to treat secondary massive quark effects. We clarify the relation between these approaches and in which way they are equivalent. Our two-loop calculation involves interesting technical subtleties related to spurious rapidity divergences and infrared regularization in the presence of massive quarks.
Lateral Pelvic Lymph Node Metastases in Rectal Cancer: A Systematic Review
Authors: Atef Y. , Koedam T. W. , van Oostendorp S. E. , Bonjer H. J. , Wijsmuller A. R. , Tuynman J. B.
Published: August 2019

Background

Synchronous lateral pelvic lymph node (LPLN) involvement occurs in a significant number of patients with rectal cancer. The aim of this study is to determine the rate of LPLN metastases in rectal cancer patients with LPLN suspicious for metastases (LPLNSM) on pretreatment imaging, treated with neoadjuvant chemoradiotherapy (nCRT). Additionally, the influence of LPLN responsiveness to nCRT as determined by post‐nCRT restaging scan was investigated.

Methods

A systematic review was conducted to identify studies on patients with author‐defined LPLNSM that reported the pathological outcomes after total mesorectal excision (TME) with lateral pelvic lymph node dissection (LPLD). MEDLINE, EMBASE, Web of Science and the Cochrane Library were searched. The primary outcome was the percentage of pathologically confirmed LPLN metastases.

Results

A total of 462 patients from eleven studies were identified. The number of pathologically confirmed LPLN metastases in 361 patients that underwent uni‐ or bilateral LPLD ranged from 21.9 to 61.1%. The LPLD resulted in pathologically confirmed metastases in a range from 0 to 20.4% of patients with responsive LPLNSM and in a range from 25.0 to 83.3% of patients with persistent nodes. However, radiologic cutoff criteria for the evaluation of LPLN differed between studies.

Conclusions

In a large number of patients with LPLNSM on initial imaging, metastatic LPLN are present after nCRT and surgical treatment. Even in LPLN that are considered responsive on restaging, significant rates of pathologically confirmed metastases are reported.
Serum levels of selected cytokines [interleukin (IL)-17A, IL-18, IL-23] and chemokines (RANTES, IP10) in the acute phase of immunoglobulin A vasculitis in children
Authors: Jaszczura Majka , Mizgała-Izworska Elżbieta , Świętochowska Elżbieta , Machura Edyta
Published: August 2019

The pathogenesis of the immunoglobulin A vasculitis (IgAV) is still unknown. The available data shows that interleukin (IL)-17, IL-18, IL-23, regulated on activation, normal T cell expressed and secreted (CCL 5, RANTES), and interferon (IFN)-γ-inducible protein 10 (IP10) participate in the pathogenesis of IgAV by influencing the recruitment of leukocytes to the site of inflammation. The aim of this study was to analyze the serum concentration of IL-17A, IL-18, IL-23, RANTES, and IP10 in patients with acute IgAV compared to healthy children. Moreover, we wanted to assess the suitability of the levels of tested cytokines to predict the severity of the disease. All children with IgAV hospitalized in our institution between 2012 and 2017 were included in the study. Cytokines levels were determined in a serum sample secured at admission to the hospital. Basic laboratory tests have also been analyzed. IL-17A, IL-18, and IL-23 were significantly higher in whole IgAV group (52.25 pg/ml; 164.1 pg/ml and 700 pg/ml, respectively) than in the control group (27.92 pg/ml; 140.1 pg/ml and 581.5 pg/ml, respectively). The receiver operating characteristic (ROC) curve analysis revealed the largest area under the curve (AUC 0.979, p < 0.001) for the IL-17A with 95.1% sensitivity and 91.7% specificity. There were no significant differences in cytokine levels depending on the severity of the IgAV. Although the serum levels of the IL-17A, IL-18, and IL-23 increase significantly in the acute phase of the IgAV, they cannot be used as indicators of predicting the course of the disease. IL-17A seems to be a good predictor of IgAV occurrences.
Application of hydraulic flow units’ approach for improving reservoir characterization and predicting permeability
Authors: Khalid Mostafa , Desouky Saad El-Din , Rashed Mohammed , Shazly Tarek , Sediek Kadry
Published: August 2019

It is highly essential to characterize the reservoir accurately as possible to implement enhanced oil recovery and development scenarios. Determining complex variations in pore geometry aids in identifying rock types with similar fluid flow properties. Traditional classification of rock types is based on geologic observations and empirical relations between porosity and permeability. However, for a given porosity, permeability can vary by several orders of magnitude. This reveals that porosity only cannot interpret the permeability variation. The proposed approach to define the existence of different rock types in the reservoir is the “hydraulic flow units’ approach.” The approach aims to enhance the reservoir characterization and predict permeability in un-cored wells to reduce the cost of drilling core samples. The approach involves dividing the reservoir into hydraulic flow units (HFUs). It introduces the concept of reservoir quality index and flow zone indicator (FZI) to identify the HFUs. Each unit is imprinted by certain FZI and said to have similar geological and petro-physical properties. Validation of results was done by integrating the HFUs with core description results—particularly samples’ grain sizes—to ascertain the accuracy of the approach. FZI was then integrated with well logs using multiple regression analysis in order to train the logs to recognize the hydraulic flow units in case of absence of core. A regression model was developed for each flow unit, from which FZI can be estimated from logs only. FZI was then correlated with permeability to compute permeability. Results showed that four HFUs exist in the reservoir. Four categories of grain sizes were identified from core analysis. This emphasized the accuracy of the proposed technique. Besides, integration between core data and well-logging ones showed high degree of correlation between well logs and FZI. Expanding this correlation aids in predicting permeability in un-cored well.
Developments and experimental tests on a laboratory-scale drilling automation system
Authors: Khadisov Magomed , Hagen Håkon , Jakobsen Andreas , Sui Dan
Published: August 2019

This paper presents the work that has gone into optimizing drilling performances on a laboratory-scale drilling rig, capable of drilling through rock samples in possible shortest time with preventing damages to devices for the sake of drilling costs and safety. The rig is fully functional, and we conducted successful experiments in both manual and autonomous modes. In this study, we focus on testings on drilling optimizations, failures, advancements of understanding of operational limits, and implementations of these boundaries to create a well-designed and controlled drilling rig. Case studies show that good results have been achieved in terms of optimizing drilling parameters and receiving the possible highest drilling speed when drilling different formations.
One More Twist ~ Knowledge How and Ability
Authors: Mizumoto Masaharu
Published: August 2019

According to Bengson et al.’s (2009) Salchow case, Irina is a novice skater who (1) has a mistaken belief about what amounts to a Salchow, but also (2) has a neurological abnormality which, unknowingly to her, affects both her movement and her sense of it. As a result of this twist, she (3) always ends up succeeding in jumping the Salchow whenever she tries. This story was presented as a counterexample to a variant of anti-intellectualism, and as Bengson and colleagues expected, the vast majority of participants in their survey judged both that Irina is able to do the Salchow and that she does not know how to do it. But the three conditions above leave some ambiguity about the story. That is whether Irina is aware of her own ability, or whether she is aware of what she is doing when she performs it, and therefore the fact that she can reliably perform the Salchow. However, as we report here, disambiguating this point will radically change the responses of people, which rather poses a serious challenge to intellectualism.
HENSELIAN VALUED FIELDS AND inp-MINIMALITY
Authors: CHERNIKOV ARTEM , SIMON PIERRE
Published: August 2019

We prove that every ultraproduct of p-adics is inp-minimal (i.e., of burden 1). More generally, we prove an Ax-Kochen type result on preservation of inp-minimality for Henselian valued fields of equicharacteristic 0 in the RV language.
The Place of the “Cooperative” in the Agrarian History of India, c. 1900–1970
Authors: Kamenov Nikolay
Published: August 2019

Cooperatives are a promising link that can coalesce subdisciplines such as agrarian, labor, economic, and social history. This article reassesses the significance of cooperatives in the agrarian and social history of South Asia. It provides a broad sketch of the major historical developments—legal, economic, and social—in India up to 1970, emphasizing the continuity between the colonial and postcolonial periods in terms of state engagement with cooperatives. The article goes on to discuss the existing historiography regarding the cooperative movement on the subcontinent, arguing for the substitution of the prevailing notion of failure with a more historically grounded and nuanced approach that takes into consideration the broader economic context, as well as social stratification and inequality. Finally, some promising avenues—including, but not limited to, organizational economics, bottom-up social and cultural history, and global history—are suggested for the future historiography of cooperatives in South Asia.
The future of otology
Authors: Jackler R K , Jan T A
Published: August 2019

Background

The field of otology is increasingly at the forefront of innovation in science and medicine. The inner ear, one of the most challenging systems to study, has been rendered much more open to inquiry by recent developments in research methodology. Promising advances of potential clinical impact have occurred in recent years in biological fields such as auditory genetics, ototoxic chemoprevention and organ of Corti regeneration. The interface of the ear with digital technology to remediate hearing loss, or as a consumer device within an intelligent ecosystem of connected devices, is receiving enormous creative energy. Automation and artificial intelligence can enhance otological medical and surgical practice. Otology is poised to enter a new renaissance period, in which many previously untreatable ear diseases will yield to newly introduced therapies.

Objective

This paper speculates on the direction otology will take in the coming decades.

Conclusion

Making predictions about the future of otology is a risky endeavour. If the predictions are found wanting, it will likely be because of unforeseen revolutionary methods.
Does surgical treatment of nasal airway obstruction improve sexual functions?
Authors: Cayir S , Hizli O , Gul M
Published: August 2019

Objective

To investigate the effects of surgical treatment for nasal obstruction on sexual functions, regardless of the condition causing the nasal obstruction.

Methods

Of 238 patients identified with nasal obstruction, 57 complained of erectile dysfunction and were included in the analysis. Patients underwent septoplasty, functional endoscopic sinus surgery, concha bullosa excision or radiofrequency ablation of the inferior turbinates, depending on their obstruction-causing disease. Pre- and post-operative evaluation of perceived nasal obstruction was performed using the Nasal Obstruction Symptom Evaluation questionnaire. Pre- and post-operative assessment of sexual functions was performed using the International Index of Erectile Function.

Results

Mean post-operative scores for erectile function, orgasmic function, sexual desire, intercourse satisfaction and overall sexual satisfaction were significantly higher compared to the pre-operative scores (p = 0.022, p = 0.036, p = 0.033, p = 0.016 and p = 0.029, respectively).

Conclusion

Surgical treatment of nasal obstruction by septoplasty, endoscopic sinus surgery, concha bullosa excision or radiofrequency can significantly improve sexual performance.
Land-cover change threatens tropical forests and biodiversity in the Littoral Region, Cameroon
Authors: Mahmoud Mahmoud I. , Campbell Mason J. , Sloan Sean , Alamgir Mohammed , Laurance William F.
Published: August 2019

Tropical forest regions in equatorial Africa are threatened with degradation, deforestation and biodiversity loss as a result of land-cover change. We investigated historical land-cover dynamics in unprotected forested areas of the Littoral Region in south-western Cameroon during 1975–2017, to detect changes that may influence this important biodiversity and wildlife area. Processed Landsat imagery was used to map and monitor changes in land use and land cover. From 1975 to 2017 the area of high-value forest landscapes decreased by c. 420,000 ha, and increasing forest fragmentation caused a decline of c. 12% in the largest patch index. Conversely, disturbed vegetation, cleared areas and urban areas all expanded in extent, by 32% (c. 400,000 ha), 5.6% (c. 26,800 ha) and 6.6% (c. 78,631 ha), respectively. The greatest increase was in the area converted to oil palm plantations (c. 26,893 ha), followed by logging and land clearing (c. 34,838 ha), all of which were the major factors driving deforestation in the study area. Our findings highlight the increasing threats facing the wider Littoral Region, which includes Mount Nlonako and Ebo Forest, both of which are critical areas for regional conservation and the latter a proposed National Park and the only sizable area of intact forest in the region. Intact forest in the Littoral Region, and in particular at Ebo, merits urgent protection.
FIRST STEPS–DENTITION, KINSHIP, SOCIAL GROUPS, AND STATUS IN THE UPPER BELIZE RIVER VALLEY: SMALL SAMPLE INSIGHTS INTO CLASSIC MAYA SOCIAL ORGANIZATION IN CENTRAL WESTERN BELIZE
Authors: Blankenship-Sefczek Erin , Ball Joseph W. , Taschek Jennifer
Published: August 2019

Nonmetric (morphological) and metric analyses of dental traits and dentition are an established and effective, but still much underutilized, means of determining biological relationships among the individuals comprising a population over several generations. Combining such dental analyses, a social organizational typology adapted from social psychology, and small sample statistics, this study hazards a trial examination of the evidence for biological affinity within and between three archaeologically perceived social groups represented in the Classic-period Belize Valley community of Buenavista del Cayo. The groups comprise traditional high elite and commoner categories, and a putative middle level of intermediate elites. Findings suggest a dichotomous kinship structure of elites and non-elites, but one within which there had emerged an emically and archaeologically distinct “middle” status group of intermediate elites or subelites that remained affined by blood to the subordinate non-elite commoners and peasantry. The study differs from previous examinations of ancient Maya social organization in employing a truly integrated bioarchaeological approach to the topic rather than what have generally been intrinsically insular archaeological or osteometric approaches.
Probing Galactic Black Holes with Microlensing with Gaia and OGLE
Authors: Wyrzykowski Ł. , Rybicki K. A. , Kruszyńska K. , Gromadzki M. , Zieliski P. , Kostrzewa-Rutkowska Z. , Hodgkin S. T.
Published: August 2019

As shown by recent gravitational wave detections, galaxies harbour an unknown population of black holes at high masses. In our Galaxy such dark objects can be found and studied solely via gravitational microlensing methods. This paper described our search for black-hole lenses both in archived OGLE data and among on-going microlensing events found by OGLE and Gaia. That combination of superb time-domain astrometry and photometry will enable us to derive masses and distances to these dark lenses uniquely, and to describe the demographics of the unseen component of the Milky Way.
Fast Radio Transients: From Pulsars to Fast Radio Bursts
Authors: Stappers B. W. , Caleb M. , Driessen L. N.
Published: August 2019

The radio sky is full of transients, their time-scales ranging from nanoseconds to decades. Recent developments in technology sensitivity and computing capabilities have opened up the short end of that range, and are revealing a plethora of new phenomenologies. Studies of radio transients were previously restricted to analyses of archived data, but are now including real-time analyses. We focus here on Fast Radio Bursts, discuss and compare the properties of the population, and describe what is to date the only known repeating Fast Radio Burst and its host galaxy. We also review what will be possible with the new instrumentation coming online.
Pulsation, Rotation and Flares in A Stars
Authors: Balona L. A.
Published: August 2019

New observations of Kepler δ Scuti stars show that our understanding of pulsation in these stars is incomplete. A large fraction of A and B stars exhibit rotational modulation in light, suggesting that spots exist in stars with radiative envelopes. Flares are seen in some A stars, as may be expected if starspots are present. Differential rotation shear increases from M to F but decreases for A stars; it reaches a maximum among the γ Doradus variables. Current views of stars with radiative envelopes may need to be reviewed in the light of these observations.
The K2 RR Lyrae Survey
Authors: Szabó R.
Published: August 2019

In the framework of this project, the K2 RR Lyrae Survey, we proposed to observe thousands of RR Lyrae stars along the Ecliptic in Kepler’s K2 Mission. The high photometric precision and the 80-to-90-day continuous coverage enabled us to investigate in unprecedented detail the light variations of these variable stars which can trace galactic structure. The survey enabled us to conduct a thorough statistical study of RR Lyrae pulsation dynamics, including both old and more recently discovered dynamical phenomena such as resonances, non-radial modes, period doubling and the Blazhko effect. This talk described the K2 RR Lyrae Survey, and discussed the prospects of combining our endeavour with Gaia, LSST and other surveys in the context of studies of Galactic archeology.
Monitoring Period Variations of Variable Stars using Precise Photometric Surveys
Authors: Mikulášek Z. , Zejda M. , Hümmerich S. , Krtička J. , Bernhard K. , Paunzen E. , Skarka M. , de Villiers S. , Jagelka M. , Bakiş V.
Published: August 2019

The period variations of rotating, pulsating and eclipsing variable stars bear valuable astrophysical information about the presence of companions, evolutionary effects, and the inner structure of the stars. This talk described a universal method for de-trending and re-scaling precise photometric data (Kepler, MOST, CoRoT, OGLE, …) appropriate for period-change diagnostics of periodic variables. We demonstrated the potential of the method by analysing the period variability of one of the newly-identified Kepler magnetic chemically-peculiar (mCP) stars. We showed that, surprisingly, our target star displays near-sinusoidal changes in its observed light-variations, with a period of 2.85(6) years, which is apparently the result of the presence of a nearby stellar companion. The expected long-term changes of the rotational period, as have been observed in several mCP stars, have not been identified among the sample of Kepler mCP stars.
A New Population of Highly Energetic Nuclear Transients
Authors: Kankare E. , Kotak R. , Mattila S. , Lundqvist P.
Published: August 2019

We have identified a new population of luminous, optical, narrow-lined transients (FWHM ∼1000 km s−1) coincident with the nuclear region of Seyfert galaxies. According to extensive spectrophotometric follow-ups of the main event (PS1-10adi), we could exclude both normal active galactic nucleus activity and changing-look quasars as the origin. The integrated energy output and spectral evolution over a time-scale of several years point to two possible paths of origin: a tidal disruption of a star by a supermassive black hole, or an extremely energetic supernova occurring within the Seyfert galaxy’s narrow-line (or broad-line) region. The former model would require invoking a specific variant of a tidal disruption, while the latter would require an extremely efficient conversion of kinetic energy via shock interaction between the supernova ejecta and the dense ambient medium.
The Deeper Wider Faster Programme: Chasing the Fastest Bursts in the Universe
Authors: Andreoni I. , Cooke J.
Published: August 2019

The Deeper Wider Faster programme (DWF) is a project that coordinates more than 30 multi-wavelength and multi-messenger facilities worldwide and in space, in order to detect and study fast transients (durations of milliseconds to hours). DWF has four main components: (1) simultaneous observations, where ∼10 major facilities, from radio to gamma-ray, are coordinated to perform short-cadence, deep, wide-field observations of the same field at the same time. Radio telescopes search for fast radio bursts, while optical imagers and high-energy instruments search for transient events whose time-scales are seconds to hours, (2) supercomputer data processing and candidate identification in real time (seconds to minutes), along with human inspection of candidates, also in real time (minutes), using sophisticated visualisation technology, (3) rapid-response (minutes) follow-up spectroscopy and imaging, and conventional ToO observations, and (4) long-term follow up by a global network of 1-m to 4-m telescopes. The principal goals of DWF are to discover and study counterparts to fast radio bursts and gravitational-wave events, as well as transients at all wavelengths that have durations of milliseconds to hours.
X-Ray Transients Observed with MAXI
Authors: Kawai N.
Published: August 2019

MAXI (Monitor of All-sky X-ray Image) is an astronomical mission onboard the International Space Station. It started observations in August 2009. The Gas Slit Camera of MAXI is sensitive to X-rays in the energy range 2–30 keV. Most of the sky is scanned every 90 min with the orbital revolution of the ISS. With this unbiased monitoring, MAXI has detected numerous outbursts from known and unknown X-ray sources. MAXI discovered 18 X-ray novæ in seven years, including seven neutron star binaries, six black hole binaries (+candidates) and four unidentified sources. Other results include detections of superluminous stellar flares, a super-Eddington luminous flare from a white dwarf+Be Star binary near the SMC, and monitoring of recurrent outbursts from Be neutron-star binaries. Variations in X-ray-bright AGNs such as Cen A and Mrk 421 have been also monitored. This talk presented the highlights of the MAXI observations of variable sources, including the search for X-ray counterparts of gravitational-wave events.
LMC X–4: Different Types of Long-Term Variability
Authors: Molkov S.
Published: August 2019

This talk presented a summary of our study of different types of long-term variability in the high-mass X-ray binary LMC X-4, by taking advantage of more than 43 years of measurements in the X-ray domain. In particular, we investigated the 30-day cycle of modulation of the X-ray emission from the source (super-orbital or precessional variability), and refined the orbital period and its first derivative. We showed that the precession period in the time-interval 1991–2015 is near its equilibrium value of Psup = 30.370 days, while the observed historical changes in the phase of this variability can be interpreted in terms of the ‘red noise’ model. We obtained an analytical law from which the precession phase can be determined to within 5% throughout the entire time-interval under consideration. Our analysis revealed for the first time that the source is displaying near-periodic variations of its spin period, on a time-scale of roughly 6.8 years, thus making LMC X-4 one of the (few) known binary systems that show remarkable long-term spin–torque reversals.
Time-Domain Instrumentation at ESO
Authors: Ivanov V. D.
Published: August 2019

Over the years the European Southern Observatory (ESO) has offered a number of time-domain instruments that enable the user to achieve time resolution as small as milliseconds. They have been used for a wide range of applications, from binary studies with Lunar occultations, characterisation of X-ray binaries and exoplanet transits, to quasar variability. Furthermore, ESO provides a target-of-opportunity (ToO) rapid-response-mode (RRM) channel to trigger quick follow-up observations within as little delay as minutes after a transient has been detected. This talk reviewed the available time-domain observing modes and instruments at ESO, giving priority to FORS2, HAWKI and UltraCam. It described the ToO and RRM, and gave examples of the most common science cases that take advantage of those channels and capabilities.
The SALT Transient Programme
Authors: Buckley D. A. H.
Published: August 2019

The SALT transient follow-up programme began in 2016 and will continue for 5 semesters (until 31 Oct 2018), with an expectation of renewal thereafter. It is currently the only SALT Large Science Programme, and was awarded ~250 ksec. per semester, with a significant fraction (60%) given for the highest priority target-of-opportunity time. The aim is to characterise and study transients across a wide range of classes, currently including (from closest to most distant) cataclysmic variables, novæ and other associated eruptive variables, low- and high-mass X-ray binaries, OGLE and Gaia transients (including tidal disruption events), super-luminous and unusual core-collapse supernovæ, kilonovæ and other candidate optical counterparts to gravitational-wave events, flaring blazars and AGN, and gamma-ray bursts. This programme currently involves four SALT partners, of which South Africa is the major contributor of time (74%) and resources and includes five institutions with over 30 co-investigators. This talk reviewed the nature of the programme and highlighted some of the results to date.
High-Time-Resolution Astrophysics using the Thai 2.4-m Telescope with Ultraspec
Authors: Irawati P.
Published: August 2019

The Thai National Observatory (TNO) is equipped with a 2.4-m Ritchey-Chretien telescope and the high-speed versatile Ultraspec camera. The instrument employs a low-noise frame-transfer EMCCD, suitable for the observation of faint objects and for high-time-resolution astrophysics. We present some of the results obtained in the first four years of operation, focusing particularly on fast photometry of lunar and stellar occultations, and follow-up efforts on a few white-dwarf binaries. Among the latter is the polar cataclysmic variable UZ For. This system displays period changes and is suspected of hosting circumbinary planets. Our high-speed photometry data show a decreasing trend in the O–C diagram of UZ For. Using our new data set, we will investigate whether the period change in this binary is due to a possible third body, or to other mechanism(s).
The Trans-Neptunian Automated Occultation Survey (TAOS II)
Authors: Lehner M. J. , Wang S-Y. , Reyes-Ruiz M. , Zhang Z-W. , Figueroa L. , Huang C-K. , Yen W-L. , Alcock C. , Alvarez Santana F. , Castro-Chacón J. , Chen W-P. , Chu Y-H. , Cook K. H. , Geary J. C. , Hernández B. , Karr J. , Kavelaars J. J. , Norton T. , Szentgyorgyi A.
Published: August 2019

TAOS II is a next-generation occultation survey with the goal of measuring the size distribution of the small end of the Kuiper Belt (objects with diameters 0.5–30 km). Such objects have magnitudes r > 30, and are thus undetectable by direct imaging. The project will operate three telescopes at San Pedro Mártir Observatory in Baja California, México. Each telescope will be equipped with a custom-built camera comprised of a focal-plane array of CMOS imagers. The cameras will be capable of reading out image data from 10,000 stars at a cadence of 20 Hz. The telescopes will monitor the same set of stars simultaneously to search for coincident occultation detections, thus minimising the false-positive rate. This talk described the project, and reported on the progress of the development of the survey infrastructure.
Unlocking the Universe with Astroinformatics
Authors: Lochner M.
Published: August 2019

In the last decade Astronomy has been transformed by a deluge of data that will grow exponentially when near-future telescopes such as LSST and the SKA begin routine observing. Astroinformatics, a broad field encompassing many techniques in statistics, machine learning and data mining, is the key to extracting meaningful information from large amounts of data. This talk outlined Astroinformatics as a field, and gave a few examples of the use of machine learning and Bayesian statistics from my own work in survey Astronomy. The era of massive surveys in which we now find ourselves has the potential to revolutionise completely many fields, including time-domain Astronomy, but only if coupled with the powerful tools of Astroinformatics.
Stellar Variability: from Citizen Science to Citizen Astronomy
Authors: Kafka S. , Griffin E.
Published: August 2019

The contribution of citizens to research is irrefutable. Especially this century with the outburst of all-sky surveys, professional astronomers use citizen-science projects to engage the public in analysing and sorting large quantities of data, often leading to noteworthy discoveries. From crowdsourcing to acquiring data, citizens are leaving a significant mark in the science landscape, assisting professional astronomers with their work. In turn, citizen science is a means of increasing science literacy and public understanding of science. At the same time, the time domain enables a more active engagement of backyard observers in research. Citizen astronomers not only take data, but also reduce and analyse them, and participate in preparing scientific manuscripts.
A-Type Stars as a Unique Challenge in Time-Domain Studies
Authors: Lynas-Gray A. E. , Mathys G.
Published: August 2019

As photometric standards, A-Type stars have proved to be extremely useful; this is particularly true of Vega, the fundamental photometric standard. However, the identification of at least some main-sequence A-type stars as small-amplitude variables, while of interest as an issue of fundamental astrophysics, needs to be understood if they are to continue to be used as photometric standards. Flaring and Rossby waves are proposed in the literature as possible explanations, as was discussed during a well-attended Workshop debate. This report summarises the discussion, and suggests future investigations.
X-ray Binary Transients in the Magellanic Clouds and the Milky Way
Authors: Charles P. , Anderson G. , Coppejans D. , Motsoaledi M.
Published: August 2019

The X-ray sky is dominated by luminous galactic sources, variable on time-scales from milliseconds to years. Their eruptive behaviour is now under continuous monitoring by MAXI, Swift, INTEGRAL and other high-energy missions, and representing a superb exemplar of time-domain astronomy. Understanding the astrophysics of such variability requires multi-wavelength follow-up studies from a suite of ground- and space-based facilities. As SALT is a 100% Q-scheduled telescope, one of its key scientific capabilities is related to Target-of-Opportunity (ToO) programmes, and there has been a dedicated SALT Large Programme on Transients in place since 2016, a significant fraction of which has been devoted to the follow-up of X-ray binary transients. This Workshop addressed questions of how such programmes should evolve once the era of MeerKAT and MeerLICHT begins in ∼2018-9 (as well as other huge surveys at optical wavelengths), identifying the range of facilities that would be needed, and the key science topics. There is a clear and growing need for responses to transients to be faster (within minutes if possible), and to be multi-wavelength (particularly in radio and X-ray). Furthermore, extended ongoing coverage of such events (days to weeks for the next ‘V404 Cyg’-type outburst) will be needed for maximum astrophysical return. That would require careful management and coordination of a wide range of ground- and space-based facilities, and optimising coverage against logistical constraints that are often conflicting.
Machine Learning for Transient Classification
Authors: Lochner M. , Bassett B.
Published: August 2019

We organized Workshop 13, Machine learning for transient classification, into two distinct question-and-answer parts. The first was a so-called ‘idiot session’, in which basic questions about machine learning and artificial intelligence were elicited from the audience. The second focussed discussions on the application of artificial intelligence to transient astronomy.

The workshop proved highly successful. The room was packed, and the many interesting questions and discussions were good preparation for the presentation to be made on ‘machine learning’ during the plenary session the following day.

The workshop clearly reflected the general awareness and excitement in the community for the potential of machine learning in regard to transient detections in astronomy in the era of ZTF, LSST, LIGO and the SKA. Several of the presentations at this Symposium had already been exhibiting specific attention to the roles of machine-learning techniques and products. The extent to which the younger generations were being involved was clearly noticeable, and that augured well for research into workable solutions for astronomy’s ‘Big Data’ problems which – as stated frequently at this conference – are only just around the corner.
Calibration and Standardisation
Authors: Sterken C.
Published: August 2019

One of the great challenges in time-domain astronomy is the problem of combining data obtained at various epochs with very different instruments. These problems are mostly discussed from within a specific observational mode, for example photometry, spectroscopy or imaging. This Workshop explored by example diverse pitfalls of time-domain calibration by discussing calibration and standardisation problems across various types of variables.
Symbiotic Stars in the Local Group of Galaxies: POINT-AGAPE Catalogue Revisited
Authors: Drozd K. , Mikołajewska J. , Darnley M. , Iłkiewicz K. , Caldwell N. , Shara M.
Published: August 2019

This research was prompted by the discovery of 35 new or candidate symbiotic stars during a targeted search in the Local Group of Galaxies. A catalogue of a further 200 or so such objects has now been compiled. Many of them could be identified with counterparts in the POINT-AGAPE Catalogue. However, information in the Catalogue is limited to position, brightness and possible period, and light-curves are not available. The poster presented an example of a light-curve of a symbiotic star retrieved from original Point-Agape Catalogue data.
Kepler-410Ab and Transit Timing Variations
Authors: Gajdoš P. , Parimucha Š. , Fedurco M.
Published: August 2019

Our poster presented a new analysis of the transit-time variations displayed by the extrasolar planet Kepler-410Ab. We assumed that the observed changes in the transit times are caused by the gravitational influence of another body in the system. To determine the mass of that perturbing body, we considered the light-time effect and an analytical approximation of the perturbation model. The solutions resulting from both methods gave comparable results, with an orbital period of 970 days and a slightly eccentric orbit for the third body. We proposed two possible models of a perturbing body orbiting a common barycentre with Kepler-410A: a single star with mass of at least 0.906 M⊙, or a binary star with a total component mass of at least 2.15 M⊙.
Statistical research into correlation 2 between solar filaments and flare activities
Authors: Lin G.
Published: August 2019

There is a strong correlation between coronal mass ejection transients and chromospheric H-α activity. Solar physicists hope to ascertain what causes coronal disturbances, and in our current investigation we are trying to address that problem by assessing the likelihood that a coronal disturbance is associated with other manifestations of the same abrupt, perturbing event such as a flare. The correlation, if any, between filament and flare can be derived by a method of image processing. Our next approach is to give the results of statistical research by studying a century of chromospheric Hα observations. This poster describes the concept and preliminary experiences of deriving the characteristics of a filament and a flare.
A CoRoT View of the ζ Aur binary HR 6902
Authors: Maceroni C. , Montalbán J. , Da Silva R. , Semaan T. , Mosser B. , Rainer M. , Poretti E. , Griffin E.
Published: August 2019

HR 6902 was the first target of a systematic study by Griffin (1986, JApA, 7, 195) of binaries showing composite spectra. It is also a well-studied member of the ζ Aur class. ζ Aur systems are long-period eclipsing binaries that are comprised of an evolved giant primary and a hot dwarf companion. Although those component stars have very different effective temperatures they have similar luminosities in the blue and near-UV regions, and hence display a composite spectrum at those wavelengths. In principle the ζ Aur systems are excellent tests of evolutionary and structural stellar models. In recent years the somewhat fragmentary eclipse photometry of HR 6902 has been out-classed by the high-precision continuous monitoring by the space mission CoRoT. HR 6902 was selected as a primary target of its seismology field, because the possible detection of solar-like pulsations in a giant component of a double-lined eclipsing binary could help to calibrate the scaling relation of giant pulsators. Our poster reported the results of a new analysis based on the CoRoT observations and follow-up spectroscopy with HARPS at the ESO 3.6-m telescope at La Silla.

The unprecedented accuracy of the CoRoT photometry enabled us to:

improve drastically the accuracy of the binary orbit and stellar parameters (by a factor ~10 for the radii)

extend the test of validity/calibration of the scaling relations to high stellar mass and radius, and put constraints on the evolutionary state (particularly since this binary is certainly free from tidal effects).