bluuebunny/crossref_metadata_2025 huggingface dataset:
Epidemiology of Eastern Massasauga (Sistrurus catenatus) Snakebites in the Great Lakes States, 1800–2015
Authors: Wasko Dennis K. , Bullard Stephan G. , Beauvais Thomas F.
Published: June 2021

Introduction

The eastern massasauga rattlesnake ( Sistrurus catenatus) has the northernmost distribution of any venomous snake in the United States and presents a potential, but little-studied, risk to humans.

Methods

We quantified the reported incidence of massasauga bites to humans in the Great Lakes states by searching historic and contemporary media reports between 1800 and 2015.

Results

We identified 848 reported massasauga bites across the region, most of which were concentrated along the border of Indiana and Michigan. The number of bites per decade increased into the late 1800s as human population increased; it then declined sharply in the 1900s, likely owing to declining massasauga population and habitat. The majority of bites were to adult males. There was no relationship between victim sex and age or activity when bitten. Most bites resulted from snakes the victims were unaware of, usually when individuals accidentally put their hands or feet near an unseen snake. Many bites, however, resulted from people intentionally interacting with a massasauga, such as attempting to capture or kill it. Fatality rates were lower among men than among women and were lower in adolescents than older or younger victims. No fatalities from massasaugas were reported after 1935.

Conclusions

Fatality rates from massasauga bites reported herein should be interpreted with caution owing to the nature of the data we collected. In the modern era, massasauga bites are generally considered neither common nor life-threatening, although our findings suggest that historically they may have been both more frequent and potentially more dangerous.
Differentiating Sources of Fecal Contamination to Wilderness Waters Using Droplet Digital PCR and Fecal Indicator Bacteria Methods
Authors: Pendergraph Daniel P. , Ranieri John , Ermatinger Lochlin , Baumann Adam , Metcalf Alexander L. , DeLuca Thomas H. , Church Matthew J.
Published: June 2021

Introduction

Human activity in wilderness areas has the potential to affect aquatic ecosystems, including through the introduction of microorganisms associated with fecal contamination. We examined fecal microorganism contamination in water sources (lake outlets, snowmelt streams) in the popular Absaroka Beartooth Wilderness in the United States. Although the region is remote, increasing human visitation has the potential to negatively affect water quality, with particular concern about human-derived microorganism fecal contaminants.

Methods

We used standard fecal indicator bacterial assays that quantified total coliform bacteria and Escherichia coli concentrations, together with more specific polymerase chain reaction-based microbial assays that identified possible human sources of fecal microorganisms in these waters.

Results

Total coliforms were detected at all lake outlets (21 of 21 sites), and E coli was detected at 11 of 21 sites. Droplet digital polymerase chain reaction assays revealed the presence of human feces-derived microorganisms, albeit at abundances below the limit of detection (<10 gene copies per milliliter of water) at all but 1 of the sampling sites.

Conclusions

Our results suggest low prevalence of water-borne pathogens (specifically E coli and human-derived Bacteroides) in this popular wilderness area. However, widespread detection of total coliforms, Bacteroides, and E coli highlight the importance of purifying water sources in wilderness areas before consumption. Specific sources of total coliforms and E coli in these waters remain unknown but could derive from wild or domesticated animals that inhabit or visit the Absaroka Beartooth Wilderness. Hence, although contamination by human fecal microorganisms appears minimal, human visitation could indirectly influence fecal contamination through domesticated animals.
Women and Geography on the Early Modern English Stage
Authors: Pilhuj Katja
Published: June 2021

In a late 1590s atlas proof from cartographer John Speed, Queen Elizabeth appears, crowned and brandishing a ruler as the map's scale-of-miles. Not just a map key, the queen's depiction here presents her as a powerful arbiter of measurement in her kingdom. For Speed, the queen was a formidable female presence, authoritative, ready to measure any place or person. The atlas, finished during James' reign, later omitted her picture. But this disappearance did not mean Elizabeth vanished entirely; her image and her connection to geography appear in multiple plays and maps. Elizabeth becomes, like the ruler she holds, an instrument applied and adapted. Women and Geography on the Early Modern English Stage explores the ways in which mapmakers, playwrights, and audiences in early modern England could, following their queen's example, use the ideas of geography, or 'world-writing', to reshape the symbolic import of the female body and territory to create new identities. The book demonstrates how early modern mapmakers and dramatists - men and women - conceived of and constructed identities within a discourse of fluid ideas about space and gender.
Does single pregnancy hurt birth outcomes among young mothers?
Authors: Kim Young-Il , Lee Jungmin
Published: June 2021

Does single pregnancy adversely affect infant health? This is a challenging research question because there is selection in coresidence during pregnancy. We exploit quasi-natural variation in single pregnancy from the moment of conception to birth, arising from the reform of the marriageable age laws in Korea. The Korean birth certificate data are unique. They provide the information about the coresidence status in addition to the legal marital status. The coresidence start date allows us to identify the intensity of coresidence during pregnancy. We find that coresidence or legal marriage during pregnancy does not significantly affect birth outcomes.
Predicting asymptomatic severe acute respiratory coronavirus virus 2 (SARS-CoV-2) infection rates of inpatients: A time-series analysis
Authors: Rivera Frida , Ahn Kwang Woo , Munoz-Price L. Silvia
Published: June 2021

Asymptomatic SARS-CoV-2 infections are often difficult to identify because widespread surveillance has not been the norm. Using time-series analyses, we examined whether COVID-19 rates at the county level could predict positivity rates among asymptomatic patients in a large health system. Asymptomatic positivity rates at the system level and county-level COVID-19 rates were not associated.
Exact simulation of Ornstein–Uhlenbeck tempered stable processes
Authors: Qu Yan , Dassios Angelos , Zhao Hongbiao
Published: June 2021

There are two types of tempered stable (TS) based Ornstein–Uhlenbeck (OU) processes: (i) theOU-TS process, the OU process driven by a TS subordinator, and (ii) theTS-OU process, the OU process with TS marginal law. They have various applications in financial engineering and econometrics. In the literature, only the second type under the stationary assumption has an exact simulation algorithm. In this paper we develop a unified approach to exactly simulate both types without the stationary assumption. It is mainly based on the distributional decomposition of stochastic processes with the aid of an acceptance–rejection scheme. As the inverse Gaussian distribution is an important special case of TS distribution, we also provide tailored algorithms for the corresponding OU processes. Numerical experiments and tests are reported to demonstrate the accuracy and effectiveness of our algorithms, and some further extensions are also discussed.
Weak convergence of stochastic integrals with respect to the state occupation measure of a Markov chain
Authors: Jansen H. M.
Published: June 2021

Our aim is to find sufficient conditions for weak convergence of stochastic integrals with respect to the state occupation measure of a Markov chain. First, we study properties of the state indicator function and the state occupation measure of a Markov chain. In particular, we establish weak convergence of the state occupation measure under a scaling of the generator matrix. Then, relying on the connection between the state occupation measure and the Dynkin martingale, we provide sufficient conditions for weak convergence of stochastic integrals with respect to the state occupation measure. We apply our results to derive diffusion limits for the Markov-modulated Erlang loss model and the regime-switching Cox–Ingersoll–Ross process.
NOWCASTING GDP GROWTH IN A SMALL OPEN ECONOMY
Authors: Marcellino Massimiliano , Sivec Vasja
Published: June 2021

Nowcasting, that is, forecasting the current economic conditions, is a key ingredient for decision making, but it is complex, even more so for a small open economy, due to the higher volatility of its GDP. In this paper, we review the required steps, taking Luxembourg as an example. We consider both standard and alternative indicators, used as inputs in several nowcasting methods, including various factor and machine learning models. Overall, mixed frequency dynamic factor models and neural networks perform well, both in absolute terms and in relative terms with respect to a benchmark autoregressive model. The gains are larger during problematic times, such as the financial crisis and the recent Covid period.
THE DASGUPTA REVIEW: SUPPLEMENTARY NOTES ON INVESTMENT IN CONSERVATION AND RESTORATION, FAMILY PLANNING, AND REPRODUCTIVE HEALTH
Authors: Dasgupta Partha
Published: June 2021

Three broad categories of transformative changes have been recommended in The Economics of Biodiversity: The Dasgupta Review (henceforth Review): (i) The need to address the imbalance between our demands on Nature and its supply. (ii) The need to change our measures of economic success. (iii) The need for institutional change. However, what the private citizen would like to find in the Review differs from what someone in a government department or an international agency or a private company seeks. These notes have been prompted by the many virtual meetings I have had since the Review’s launch and they further explore aspects of the Review’s recommendations.
Constructions of Christian Identity in the Northern Periphery: the Sawley World Map in Twelfth-Century England
Authors: DRAGNEA MIHAI
Published: June 2021

An exploration of the complex relationship between Christian constructions of identity and the idea of sacrality derived from the ancient Greco-Roman world, this article argues that Christian identity developed uniquely in a specific context, often intertwined with theology and mythology. The complex relationship between the two was crucial in the construction of Christian identity in the lands recently converted, and influenced the authors of world maps from the eleventh century onward. This study investigates how the pagan past and Christian present were incorporated in some world maps, such as the twelfth-century English Sawley map. Thus it offers readers a coherent analysis of early history-writing in northern Europe in the first centuries after conversion.
Unpacking the perceived benefits and costs of integrating gender into conservation projects: voices of conservation field practitioners
Authors: Westerman Kame
Published: June 2021

Many in the conservation sphere have noted that robust and gender-equitable stakeholder engagement is crucial in achieving conservation outcomes, ensuring project sustainability and supporting human well-being. However, despite policies, international agreements and increasing requirements of donors, gender is still often viewed as an add-on rather than as a fundamental element of effective conservation. In an effort to overcome this, Conservation International has invested in nearly 20 project sites since 2014 to support targeted gender integration into existing conservation projects. We conducted a survey with practitioners across these sites to examine the barriers to and enablers of gender integration, and practitioners’ perceptions of the benefits and challenges involved in this. Our findings demonstrate the importance of both external drivers (funding requirements) and a supportive environment (capacity building, technical and financial support) in incentivising a focus on gender. Respondents also reported a suite of benefits (e.g. increased participation, higher quality of the project) and costs (mainly financial) related to gender integration. In documenting these efforts to build gender-related capacity, and the associated benefits and challenges, we highlight the importance of gender-responsive conservation initiatives, and evaluate a method of achieving this. As conservation practitioners may be more inclined to listen to each other (given their shared objectives) rather than to gender specialists, this research can help to shift practitioner dialogue and conservation practice to be more open and responsive to gender.
American psychiatry in the new millennium: a critical appraisal
Authors: Scull Andrew
Published: June 2021

This article casts a critical eye over the development of American psychiatry from 1980 to the present. It notes the rapid decline of psychoanalysis that followed the publication of DSM III; the rising influence of genetics and neuroscience; the re-emphasis on the biology of mental illness; and the collapse of public psychiatry that accompanied deinstitutionalization. It argues that while genetics and neuroscience have made scientific progress, the clinical utility of their findings to date has been very limited. The fifth edition of the DSM was supposed to base itself on this new science but that proved impossible. Diagnosis remains purely phenomenological and controversial. One of the ironies of research on psychiatric genetics is that has failed to find either a Mendelian origin of schizophrenia and depression or to validate the importance of hypothesized candidate genes. Genome-wide association studies have instead uncovered risk factors for major mental illnesses, but these overlap considerably, and the genetic associations are not dispositive. Most of those who carry these genetic variants do not develop mental illness. The status of psychopharmacology since the mid-1950s is scrutinized, as is the influence of the pharmaceutical industry on contemporary psychiatry, and the implications of its recent decision to abandon work in this arena. The paper concludes with an assessment of the crisis that it contends confronts contemporary American psychiatry: its overemphasis on biology; the urgent questions that persist about diagnosis and therapeutics; concerns about the directions of future research; and its inability to reduce the excess mortality that plagues the mentally ill.
Detection and viral RNA shedding of SARS-CoV-2 in respiratory specimens relative to symptom onset among COVID-19 patients in Bavaria, Germany
Authors: Woudenberg Tom , Eberle Ute , Marosevic Durdica , Liebl Bernhard , Ackermann Nikolaus , Katz Katharina , Sing Andreas ,   Bavarian SARS-CoV-2-Group
Published: June 2021

We assessed severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) reverse transcriptase-polymerase chain reaction (RT-PCR) diagnostic sensitivity and cycle threshold (Ct) values relative to symptom onset in symptomatic coronavirus disease-2019 (COVID-19) patients from Bavaria, Germany, of whom a subset was repeatedly tested. Locally weighted scatterplot smoothing method was used to assess the relationship between symptom onset and Ct-values. Kaplan−Meier plots were used to visualise the empirical probability of detecting viral ribonucleic acid (RNA) over time and estimate the time until clearance of viral RNA among the repeatedly tested patients. Among 721 reported COVID-19 cases, the viral RNA was detected in specimens taken between three days before and up to 48 days after symptom onset. The mean Ct-value was 28.6 (95% confidence interval (CI) 28.2–29.0) with the lowest mean Ct-value (26.2) observed two days after symptom onset. Up to 7 days after symptom onset, the diagnostic sensitivity of the RT-PCR among repeatedly sampled patients (n= 208) remained above 90% and decreased to 50% at day 12 (95% CI 10.5–21.5). Our data provide valuable estimates to optimise the timing of sampling of individuals for SARS-CoV-2 detection. A considerable proportion of specimens sampled before symptom onset had Ct-values comparable with Ct-values after symptom onset, suggesting the probability of presymptomatic transmission.
Are Older Adults’ Leisure Patterns Consistent with the Active Ageing Model? The Influence of the Ageist Stereotypes
Authors: Faílde Garrido José María , Dapía Conde María Dolores , Vázquez Vázquez Miguel Ángel , Vázquez Rodríguez Lucía
Published: June 2021

More and more studies indicate that leisure plays a fundamental role in active ageing. Our study describes the current leisure patterns of older adults, comparing them with other age groups. Consequently, 445 adults, stratified by age (young, middle-aged and older adults), were selected and subsequently administered a set of tests. The results indicate that older people claim having more time for their leisure activities; however, the diversity of activities performed is lower, showing a negative gradient based on age. The leisure patterns of older people reflect a predominance of passive leisure, little cultural leisure time and moderate levels of social and physical leisure activities. Older people’s leisure seems to be influenced by ageist stereotypes and attribution biases. Our findings imply that these results could be used to design and implement programs aimed at promoting leisure styles that contribute to increase active ageing.
A Portuguese trial using dignity therapy for adults who have a life-threatening disease: Qualitative analysis of generativity documents
Authors: Julião Miguel , Sobral Maria Ana , Johnston Bridget , Lemos Ana Raquel , Almeida Sara , Antunes Bárbara , Dönmez Çiğdem Fulya , Chochinov Harvey Max
Published: June 2021

Objectives

Dignity therapy (DT) is a brief, individualized intervention, which provides terminally ill patients with an opportunity to convey memories, essential disclosures, and prepare a final generativity document. DT addresses psychosocial and existential issues, enhancing a sense of meaning and purpose. Several studies have considered the legacy topics most frequently discussed by patients near the end of life. To date, no Portuguese study has done that analysis.

Method

We conducted a qualitative analysis of 17 generativity documents derived from a randomized controlled trial (RCT). Inductive content analysis was used to identify emerging themes.

Results

From the 39 RCT participants receiving DT, 17 gave consent for their generativity document to undergo qualitative analysis. Nine patients were female; mean age of 65 years, with a range from 46 to 79 years. Seven themes emerged: “Significant people and things”; “Remarkable moments”; “Acknowledgments”; “Reflection on the course of life”; “Personal values”; “Messages left to others”; and “Requests and last wishes”.

Significance of results

Generativity document analysis provides useful information for patients nearing death, including their remarkable life moments and memories, core values, concerns, and wishes for their loved ones. Being conscious of these dominant themes may allow health providers to support humanized and personalized care to vulnerable patients and their families, enhancing how professionals perceive and respond to personhood within the clinical setting.
Metallicity Distributions in Extragalactic Globular Cluster Systems: Constraints on Globular Cluster and Galaxy Formation
Authors: Brodie Jean P.
Published: June 2021

The merger model for elliptical galaxy formation has received increasing attention since it was first suggested by Toomre & Toomre (1972). Van den Bergh (1984) pointed out a problem with the idea that elliptical galaxies were formed by simply combining two, or more, spiral galaxies. He noted that the specific frequency (SN, number of globular clusters per unit galaxy light) is systematically lower for spirals than for ellipticals. Schweizer (1987) suggested that globular clusters (GCs) might be expected to form in the merger process, thereby alleviating or possibly eliminating the SN problem. Ashman & Zepf (1992) developed this idea into a merger model for GC formation with testable predictions.

We recently examined this model in the light of new HST and ground-based imaging data on the blue and red sub-populations of GCs in elliptical galaxies (Forbes, Brodie & Grillmair 1997). We concluded that the merger model for GC formation has serious problems, particularly in explaining the characteristics of GCs in giant elliptical galaxies with high SN. A multi-phase collapse scenario was suggested as more consistent with the available evidence.
A Retrospective Introduction
Authors: Lambert David L.
Published: June 2021

“It takes little talent to see clearly what lies under one’s nose, a good deal of it to know in which direction to point that organ.” W. H. Auden

Listening to the sequence of fine talks that have made up this Joint Discussion, I have been impressed by the veritable flood of new observations that bear on the question of the abundance ratios in the oldest stars. The flood is marked by depth and diversity, as ‘noses’ are being pointed in highly profitable directions. As an example of depth, I would note the extensive investigations reviewed by Andy McWilliam of the chemical compositions of very metal-poor stars where [Fe/H] ≃ -3 marks the upper end of the range defining the class. To characterize diversity, I draw attention to the analyses of quasar absorption line systems so ably discssed by Limin Lu who showed that the abundance ratios for the gas in such high z systems resemble ratios found from Galactic metal-poor stars. Of course, to many at this Joint Discussion the wealth and diversity did not come as a surprise. Indeed, I suspect that many of us pursue the topic of the composition of the first generations of stars because of the wealth and diversity of observational constraints that may now spawn a unified interpretation. Hopefully, the marvellous talks given here will pull in a few new minds - young and old - to ponder nucleosynthesis in very young galaxies and in our Galaxy in particular.
Virgo and other Late-Type Dwarfs
Authors: Brosch N. , Heller A. , Almoznino E.
Published: June 2021

We attempt to solve the question of star formation triggers and star formation laws by studying samples of simple objects and defining carefully the possible external effects. Among the star formation (SF) triggers there are some that can operate only in large disk galaxies. These are shear instabilities and density waves, and we can eliminate them if we restrict the sample to diskless objects of low mass. Such galaxies, which do show star formation, are late-type dwarf galaxies (DGs).

Other SF triggers are related to the neighborhood a galaxy finds itself in. Such triggers are galaxy-galaxy collisions and galaxy-intracluster matter interactions (stripping, shocks, etc.). These also can be eliminated by properly choosing the sample to study; one selects galaxies from neigh-borhoods of widely different densities (of galaxies) and compares their SF parameters.

We selected our first samples in a region of relatively high galaxy density, where a complete morphological classification of objects was available, and suitable depth in brightness sampling could readily be achieved. This is the Virgo cluster, where Binggeli, Sandage and Tammann (1985, BST) provide a sample of more than 2000 DGs. Among those, some 25% are of late type and are classified by BST as blue compact dwarfs (BCDs), as Magellanic irregulars (Im) of five possible sub-classes, or as combinations of those two classifications.
Tidal Dwarf Galaxies
Authors: Duc P.-A. , Mirabel I.F. , Brinks E.
Published: June 2021

The life and evolution of galaxies are dramatically affected by environmental effects. Interactions with the intergalactic medium and collisions with companions cause major perturbations in the morphology and contents of galaxies: in particular stars and gas clouds may be gravitationally pulled out from their parent galaxies during tidal encounters, forming rings, tails and bridges. This debris of collisions lies at the origin of a new generation of small galaxies, the so-called “tidal dwarf galaxies” (hereafter TDGs). Such an exotic way of forming galaxies was put forward by Schweizer (1978) and by Mirabel et al. (1992), who clearly observed the genesis of a star-forming object, out of material tidally expelled from the interacting system NGC 4038/39 (“The Antennae”). Recent studies, based on optical and HI observations, have shown that TDGs actually form a class of “recycled” objects with some properties similar to the more classical dwarf irregulars (dIrr) and blue compact dwarf galaxies (BCDs).
Distant Compact Narrow Emission Line Galaxies as Progenitors of Today’s Spheroidal Galaxies
Authors: Koo David C. , Guzmán Rafael
Published: June 2021

Dwarf galaxies at high redshifts are important to study for a variety of reasons. By dwarf, we mean galaxies with low-mass, though galaxies with low-luminosities or small sizes are also commonly referred to as dwarfs. Several groups have suggested that such galaxies may be major contributors to faint blue galaxies, whose nature remains unclear. Dwarfs are viable candidates for faint blue galaxies if many undergo strong bursts of star-formation at redshifts z ~ 1 (Babul and Ferguson 1996) or even lower redshifts z ~ 0.3 (Cowie, Songaila, and Hu 1991; Broadhurst et al. 1988) and fade or disappear by today; if they have a much steeper luminosity function (Driver et al. 1994) than generally adopted in faint galaxy models; or if they represent small pre-merger fragments of larger galaxies today (Guiderdoni and Rocca-Volmerange 1990; Broadhurst, Ellis, and Glazebrook 1992), as might be expected in standard cold dark matter models with hierarchical galaxy formation.
Introduction of JD 3 ON ‘PRECESSION, NUTATION AND ASTRONOMICAL CONSTANTS IN THE DAWN OF THE 21ST CENTURY’.
Authors: Dehant V. , Fukushima T.
Published: June 2021

Due to the adoption of the new International Celestial Reference Frame (ICRF), the Earth’s Ori-entation Parameters (EOP) will be revised and their definitions will need to be re-examined and clarified. This implies that precession/nutation formulation will be also revised in the future.

The precession/nutation theories for a non-rigid Earth suffer from a lack of dissipation in the core and from a mismodeling of the ocean and of the atmospheric effects. The scientific community is examining these questions. The IAU community is consequently not yet ready to adopt a new precession/nutation geophysical model but the users may use the International Earth Rotation Service (IERS) empirical series.

In order to review those questions and prepare the future research, the Scientific Organizing Committee (SOC: P. Bretagnon, V.A. Brumberg, N. Capitaine, V. Dehant (Chair), T. Fukushima, E. Groten, H. Kinoshitä, B. Kolaczek, D.D. McCarthy, P.K. Seidelmann and P.T. Wallace) has proposed invited talks on the current situation concerning:

(1)

the formulation of precession/nutation (N. Capitaine, see paper 1),

(2)

the planetary theories and their relation to precession/nutation (P. Bretagnon, see paper 2),

(3)

the precession/nutation for a rigid Earth (J. Souchay and H. Kinoshita, see paper 3),

(4)

the DExxx JPL ephemerides precision and accuracy (E.M. Standish, see paper 4),

(5)

the observations of the Celestial Ephemeris Pole (CEP) and in particular the pole offset from which precession/nutation corrections can be derived (M. Feissel and A.M. Gontier, see paper 5),
Aspects of The Terrestrial Influx of Small Meteoroids
Authors: Taylor A.D. , Elford W.G.
Published: June 2021

This paper briefly summarises the contribution to the understanding of meteoroids and their orbits from recent radar studies of meteors. New data from VHF and UHF observations indicates that some meteoroids are ablating at heights up to 160 km and modelling work suggests that such meteoric ionization can only be deposited by meteoroids that ablate at temperatures below 1000° K. Meteoroids with entry speeds well in excess of 100 km/s are clearly interstellar and some tentative sources have been identified. The distributions of the orbital elements of earlier data have been reanalysed in the light of a new understanding of the selection effects in those radar studies, and the presence of a significant set of retrograde orbits identified. The new technique of observing meteors ‘coming down the radar beam’ has led to very accurate measures of deceleration and detailed analysis of fragmentation events.
Variability of The Oort Cloud Comet Flux: Can It be Manifest in The Cratering Record?
Authors: Matese J.J. , Whitman P.G. , Innanen K.A. , Valtonen M.J.
Published: June 2021

We consider the subject of time dependence of the Oort cloud comet flux. Over long time scales the flux is likely to be dominated by the adiabatic galactic tide. This tide is substantially modulated as the Solar System moves in its galactic orbit. If Shoemaker was correct in his estimate that virtually all terrestrial craters of diameter > 100 km are produced by long period comets, then the phase and plane crossing period of the Solar System about the galactic disk should be consistent. with the ages of accurately dated large craters. A time series analysis of these ages in which the Solar oscillation phase is fixed to be consistent with observations indicates a maximal correlation for a period of 36 ± 2 Myr. This period is well within observational limits. If improvements in stellar velocity dispersion studies continue, it is possible that a sufficiently accurate determination of the Solar oscillation period can be found to unambiguously answer the following questions. Is the Solar oscillation cycle correlated with the time series of ages for large craters? If so, can we reject the hypothesis that the correlation is an artifact that could likely be reproduced by a random distribution of ages? We present evidence which suggests that if it is found that the data requires a plane crossing period in the range 36 ± 2 Myr, the answer to both of these questions will be affirmative.
Maintenance of the ICRS - Statistical Treatment
Authors: Schwan H. , Wielen R.
Published: June 2021

In this paper we briefly describe the influence of astrometric binaries on derived proper motions and we draw some conclusions with respect to the reference systems. For more details the reader is referred to Wielen (1997) and Wielen et al. (1997).

Increased measurement accuracy determines not only the derived parameters with much more precision, but it may even allow one to describe new phenomena, which were of no importance before. This happened in the case of the highly precise Hipparcos measurements (ESA, 1997) which were able to determine stellar proper motions within less than four years with an accuracy comparable with the best proper motions available from ground-based observations as given in the FK5 (Fricke et al. 1988). The basic difference between the Hipparcos and the FK5 proper motions showed up within our task of validating the Hipparcos proper motions during the reduction process. Our main result was that the dispersion of the residual differences between both proper motions was about three times as large compared with the error estimates expected from the data given in the catalogues. Since it was rather unlikely that one of the two catalogues had so strongly underestimated its errors, we looked for other reasons to explain the discrepancy. For many of the stars with the largest differences between the Hipparcos and FK5 proper motions, information on their duplicity was found in the literature. We thus suspected that the influence of astrometric binaries to be responsible for the discrepancy.
Evolutionary Changes in LUMINOUS STARS
Authors: Zsldos E.
Published: June 2021

The light curves of luminous stars often show spectacular secular changes which can be connected to stellar evolution. Such events are, e.g. the outbursts of P Cygni in the 17th century and 77 Carinae in the last century. Both stars belong to the Luminous Blue Variables, but these changes are not restricted to blue stars. The light curve of HR 8752 (V509 Cassiopeiae) shows a certain similarity to that of the former two stars. When it was first catalogued in the middle of the 19th century, it had been a 6m star. During 100 years the star showed a secular brightening of lm. A similar yellow hypergiant, p Cassiopeiae produced at least two outbursts this century, though both
have smaller amplitudes than it is in the case of the LBVs. Moreover, these yellow variables also have an apparently secular colour change: the B − V colour of HR 8752 is decreasing while that of ρ Cassiopeiae is increasing. In both cases evolutionary changes are possible but one cannot exclude other causes.

Besides these well studied stars there are several other yellow hypergiants with promising light curves. One of the most interesting cases seems to be R Puppis, which was discovered to be variable in the last century, but then did not show any appreciable change in the following 70-80 years. In the late 1970s, however, it began to vary once more.
Sakurai’s Object, a Late He-Flash
Authors: Kerber F. , Gratl H. , Kimeswenger S. , Roth M.
Published: June 2021

We report on dramatic change in Sakurai’s object (RA: 17h52m32.7s, DEC: −17d41’07”, J2000.0). Discovered by the Japanese amateur astronomer Y. Sakurai in Feb. 1996, this object was first classified as a slow nova (Nakano S., Sakurai Y., Hazen M., McNaught R.H., Benetti S., Duerbeck H.W., Leibundgut B., 1996, IAU Circ. 6322). Further study revealed a spectrum rich in C, N and O-lines, but poor in hydrogen, as well as an old planetary nebula surrounding the star; it was then realized that this might be a star undergoing a late He-flash (Benetti, S. et al. 1996, IAU Circ. 6325). Despite the fact that 10 to 20% of all low mass stars will experience a late He-flash (Iben I. Jr., MacDonald J., 1996), it is an extremely rare observational event, due to its short duration. The most recent example is V605 Aql/A58 in 1919 (Eitter W.C., 1987, ESO Messenger, 14: see also Clayton C.G., De Marco O., 1997, AJ for a review).

In March 1997 we discovered dramatic change in the optical spectrum of Sakurai’s object using the 2.5 m Du Pont telescope at Las Campanas, Chile. The dominating features now are the prominent bands of CN (bandheads at 388.8 and 421.6 nm) and C2 (Swan-Bands at 439.2, 473.7, 516.5, 558.5 and 565.5 nm)(Kerber F., Gratl, H., Roth, M., 1997, IAU Circ. 6601) that were not evident a year ago (Duerbeck, H.W., Benetti, S., 1996, ApJ 468, L111).
Stellar Properties of the Classical LBV R127 - Implications for Massive Stellar Evolution
Authors: Crowther P.A. , Smith L.J.
Published: June 2021

We present a new analysis of R127 (HDE 269858) - the classical Luminous Blue Variable in the LMC - during various phases of its spectral evolution over the past two decades, ranging from 9,000K to 28.000K. High quality CTIO, ESO and AAT spectroscopy are utilised to trace the variation in stellar properties for R127 with spectroscopic phase. R127 is found to possess almost identical stellar properties to AG Carinae during each stage, with a comparable helium enriched surface composition (H/He=2 by number). Results obtained from recent HST/FOS spectroscopy also indicate near identical nebular conditions to AG Carinae, with comparable electron densities and temperatures. In contrast with expectations, nebulae represent lightly processed material, suggestive of H-rich red supergiant envelopes. We discuss the importance of our results for LBVs, and the wider picture of massive stellar evolution within different environments.
The Unusual Short Period Binary V342 Aquilae; Does it Break the Evolutionary Theory Mold?
Authors: Hartman N. , Polidan R.S. , Welty A.D. , Wade R. , Etzel P.B. , Bruhweiler F.C.
Published: June 2021

Analysis of the eclipsing (period=3.39 days) binary V342 Aquilae at visible wavelengths reveals that the system is heavily enshrouded with gas, masking the identity of the underlying stars. In the ultraviolet V342 Aquilae shows six times more attenuation at phases outside of eclipse than most Algols. It is likely, then, that V342 Aquilae is the most enshrouded short period Algol system known. Our ultraviolet spectra show very pronounced Fe II absorption lines arising from ground and metastable levels, indicating an extensive circumstellar gas envelope. The strength of this absorption shows both an orbital and a cycle-to-cycle variability. The eclipse spectra display very strong emission from lines such as C II, Si IV, and C IV, with a striking similarity to the interacting binary TT Hydrae (B9.5V+K0III). We have deduced that the system consists of a late B star with a late GIII-IV companion and a mass ratio on the order of 0.5. A detailed descriptionof the observations, as well as deduced geometrical and physical properties of the system are presented. The apparent conflict of these observations with presently understood theory of binary evolution will be discussed.
Optical and Near Infrared Observations of Post-AGB Stars
Authors: Fujii T. , Ono T. , Nakada Y. , Parthasarathy M.
Published: June 2021

The post-AGB stars rapidly change their spectral energy distribution on their way from the asymptotic giant branch(AGB) to planetary nebula stage. They are generally surrounded by cool and extended dust shells emitting largely in the infrared wavelengths.

A selected sample of the post-AGB candidates were observed using the CCDand IR camera at Kiso and Nishi-Harima Astronomical Observatory. They were classified based on their broad band spectra from B to K’ band and their evolutionary stages have been discussed using the simple model of the dust shell around a star.

The light variation of some of these objects were monitored and their light curves are also presented.
Detection of Superhumps During the Outburst of BC UMA
Authors: Kunjaya Chatief , Kato Taichi , Hirata Ryuko
Published: June 2021

BC UMa was observed during its rare outburst in 1994. The superhumps with period 0.0619 day are clearly apparent, accompanied by secondary superhumps. This confirms the classification of BC UMa as an SU UMa type dwarf nova. The maximum brightness is 12.5 mag, which is about six magnitude brighterthan quiescence phase, and it makes BC UMa be classified as a TOAD (Tremendous Outburst Amplitude Dwarf-nova). The superoutburst’s magnitude was fainter than the preceeding normal outburst in September 1990. This faint superoutburst is uncommon among SU UMa stars and also among TOADs. The period analysis of the lightcurve taken after the end of the outburst yields the period of 0.0618 day which is shows that late superhumps is in operation.
The Chemical Evolution of the Main Component of the Binary System v Sagitarrii
Authors: Leushin V. , Chuvenkov V. , Snezhko L.
Published: June 2021

A model of internal structure and evolution of the peculiar binary system v Sgr is presented. The model corresponds well to the observed chemical composition of the main component atmosphere (10-4 H, 0.844 He, 0.013 C, 0.042 N by mass). It is supposed that about 5 million years ago the main component passed the stage of hydrogen nuclear burning in the shell over the helium core where the helium-carbon reactions took place. Because of convective mixing, the synthesized carbon diffusing into the hydrogen burning zone was catalyzing the reactions of the CN - cycle. This has resulted in anomalies in the chemical composition, particularly high nitrogen abundance in the layer observed now as the atmosphere of the main component since external layers were thrown off during the evolution. Following the calculated results, the quantitative restrictions of temperature and density in the layers and values of mixing parameters are obtained. It is shown that the best agreement with observations exists if the mass of the matter penetrating from the zone of helium-carbon reactions into the helium layer is 0.25 of the helium-carbon core mass. Moreover, the ratio of mass concentration He/C in this matter should equal 2, and the mass share diffusing into the layer of hydrogen burning should be in the range 0.25 - 0.30 of the layer mass.
New CCD Observations of Eclipsing Binary VW Cephei
Authors: Malawi Adbdulrahman Ali S.
Published: June 2021

New CCD observations of the eclipsing binary VW Cephei were made on the 9th and 10th of October 1996 and on the 11th of Nov. 1996. The light curves and short time-scale variations are discussed. Photometric elements were determined from analyses of the light curves. These new solutions are also discussed.
Modelling of Light Curves of Algol-Type Systems with Accretion Disks: WW and
Authors: Zola S.
Published: June 2021

Olson’s light curves of the Algol-type binary WW And, showing evidence of harbouring an accretion disk, were re-analysed. Two approaches were attempted to find a solution: the first one, the Roche geometry model assuming the system consisting of two stars, and the second one, including also the existence of an accretion disk around the hotter component. In both cases the Monte Carlo method was employed to search for the best solution. We found that adding an additional parameter, namely the third light, the data can be satisfactorily reproduced with only a marginal underfilling of the Roche lobe of the cool star, for the Roche geometry. A thorough search within the semidetached configuration, incuding an accretion disk around the hotter component, was performed. Although such a fit is slightly worse (as measured by the rms error) than that for the Roche geometry, it can explain the observed spectroscopic features. Absolute parameters of the components of this interacting binary are presented for both models.
The Oort Limit
Authors: Binney J.J.
Published: June 2021

During galaxy formation non-baryonic dark matter is not expected to pack down into a thin disk. Hence the mass-to-light ratio ϒd of the Galactic disk is a key number as the mass-to-light ratio of a purely baryonic system. If ϒd proves to be large, it suggests that the large values of ϒ that are detected elsewhere in the Universe are due to dark baryonic matter rather than some exotic form of matter. Conversely, a small value ϒd lends credence to the idea that most of the mass in the Universe is non-baryonic by suggesting that baryonic systems are well endowed with luminous stars.
Low-Luminosity Stars: Past and Future
Authors: Reid I.N.
Published: June 2021

The expression “low luminosity stars” is a descriptive category which spans a wide range of objects, from the oldest stellar remnants in the Galaxy (Wood) through failed stars (Jones, Gould) to the enigmatic MACHOs, discernible not in themselves but only through their effects on others (Bennet). All of these have attracted considerable attention in recent years, and significant progress has been achieved in each case, even if our understanding has failed to keep up with observations. However, it is in the area of brown dwarfs where the most dramatic results have been obtained. The existence of such objects has been predicted theoretically for well over thirty years, but predictions can fail. Thus the discovery of G1229B (Nakajima et al, 1995), an unambiguous substellar-mass object, followed by the detection of lithium in Teide 1 and Calar 3 in the Pleiades (Rebolo et al, 1996) mark a turning point in studies of brown dwarfs. The issue now is not whether they exist, but what are their properties as a class. With that in mind, a number of obvious questions arise.

First, what is the most effective method of finding brown dwarfs? Both brown dwarfs and VLM stars have effective temperatures below 2500K. Hence, many surveys concentrated on searching for objects which were very red at near-infrared wavelengths, and the blue JHK colours exhibited by Gl 229B cameas something of a surprise. This should not have been the case, of course, since Tsuji (1964) predicted the presence of methane in such cool atmospheres well before the term ’brown dwarf’ was invented. Current theory, as summarised in these sessions by Tsuji and Burrows, predicts that, as one moves to lower temperatures, grain formation initially drives (J-K) redward, before grains settle below τ ~ 1 and CH4 absorption sets in. Throughout, however, the optical-to-IR colours, straddling the peak in the emergent flux distribution, become progressively redder (Reid, 1994). Those colours therefore offer the most effective means of identifying both GD 165B-like and Gl 229B-like sources - an argument reinforced by the first results from the IJK DENIS survey (Delfosse et al, 1997).
A Deep Large area Search for Low Luminosity Stars
Authors: Jones Hugh R.A. , Hawkins Mike R.S.
Published: June 2021

In a recent survey for faint red stars from a digital stack of Schmidt plates a number of candidate objects were identified. Parallax’s for three of these objects have been reported showing them to have luminosities which interpreted within the available evolutionary models indicate them to be good brown dwarf candidates. Here we examine spectra of these objects and others from the plate stack. Using standard spectral indices we find that for a given spectral type their spectra are more consistent with the Pleiades brown dwarfs (PPL 15, Teide 1 and Calar 3) than with standard late-type M dwarfs. Our interpretation is that this is due to their selection by RF IN colours which at values > 3 preferentially selects objects with relatively low gravities. For late-type M dwarfs and brown dwarfs low gravities are expected to be a reliable indication of youth. We also notice that the stack objects generally have strong FeH absorption for their spectral type. Current model atmospheres suggest that FeH strongly increases in strength toward lower metallicities and lower temperatures. We believe that this is not consistent with the available observational evidence from late-type M dwarfs. It is possible that solid Fe is forming inthe low temperature atmospheres relatively depleting FeH strengths toward lower temperatures. We find some evidence that for dwarfs at low temperatures dust formation is less prevalent in lower gravity objects suggesting that dwarfs at low temperatures stronger FeH may be an indication of youth. In addition to the spectral evidence the three stack objects whose parallax’s have been measured show small tangential velocities which is a further indication of youth.
Spectra of M Dwarfs - Dimmed by Dust
Authors: Tsuji T. , Ohnaka K. , Aoki W. , Jones H.R.A.
Published: June 2021

Spectra of M dwarfs are rich in atomic and molecular lines. These spectra provide such basic information as Teff (or radius), log g (or mass), surface chemical composition, and something more (e.g. activity) if properly interpreted. It is recognized, however, that spectra of M dwarfs are already dimmed by the dust formed in their photospheres (Tsuji et al. 1996a) and this effect, which has been overlooked until recently, should be taken into account in any interpretation and analysis of the spectra of very low mass objects (VLMOs) including late M dwarfs and brown dwarfs.
The CNOC2 Field Galaxy Redshipt Survey
Authors: Yee H.K.C. , Sawicki M.J. , Carlberg R.G. , Lin H. , Morris S.L. , Patton D.R. , Wirth G.D. , Shepherd C.W. , Ellingson E. , Schade D. , Marzke R.
Published: June 2021

Fundamental to our understanding of the universe is the evolution of structures, from galaxies to clusters of galaxies to large-scale sheets and filaments of galaxies and voids. The investigation of the evolution of large-scale structure not only provides us with the key test of theories of structure formation, but also allows us to measure fundamental cosmological parameters. The CNOC2 (Canadian Network for Observational Cosmology) Field Galaxy Redshift Survey is the first large redshift survey of faint galaxies carried out with the explicit goal of investigating the evolution of large scale structure. This survey also provides the largest redshift and photometric data set currently available for the study of galaxy population and evolution at the moderate redshift range between 0.1 and 0.6. In this paper we describe the scope and technique of the survey, its status, and some preliminary results.