bluuebunny/crossref_metadata_2025 huggingface dataset:
Minimising disruption of piglets at weaning
Authors: Wheatley L E
Published: June 2019

Pigs at weaning are usually regrouped to form batches of individuals similar in weight, and consequently of a similar potential for growth. This has the effect of disrupting the social organisation present amongst pigs sucking a sow. Re-establishing social order involves fighting and stress, both antagonistic to a high level of performance. The aim of the study was to observe the effect on performance of group size and of mixing pigs at weaning.
Options at the fundamental level for growth regulation in farm livestock
Authors: Reeds P. J.
Published: June 2019

New developments in immunological techniques and increasing expertise in genetic manipulation, especially by gene transfer, have opened up a wide variety of approaches to the manipulation of the growth and metabolism of farm livestock. However, the most effective use of these techniques and the design of new pharmacological agents for growth promotion and nutrient “repartitioning” might well rest on a greater understanding of the factors and cellular mechanisms that coordinate growth and protein anabolism. It is this coordidnation that must be disturbed if persistent gains are to bke made. This greater understanding may well result from an examination of the mechanisms whereby currently available anabolic agents and techniques exert their effects and this paper will draw on these experiences. Growth is clearly a closely coordinated process and this has hampered many attempts to maintain accelerated protein deposition for long periods. For example forced increases in hormonal concentrations often induce hormonal insensitivity. It is possible that understanding and reducing the constraints on growth for example by reducing the levels of suppressive factors rather than concentrating on the active stimulation of anabolic factors may be more effective.
The effect of antisteroid antibodies upon the mating performance of early lambing mule ewes also treated with progestagen sponges and PMSG
Authors: Logue D.N. , Gill A. , Keeling B.J. , King M.E. , Gunn G.J. , Webster G.M. , Namaghi G.H. Sadeghi , Morris B.A. , Clayton J.
Published: June 2019

The importance of a high lambing percentage in early lambing flocks is well recognised as is the variability of the dose response to PMSG of early lambing ewes. It was hoped that the integration of the immunogen ovandrotone-albumin (Fecundin ® Coopers Animal Health) into such a system would give a reliable increase in ovulation rate without the danger of superovulation caused by higher doses of PMSG. Unfortunately, last year Logue, Gill and McClelland (1986) and Keeling, King and Gunn (1986) independently reported that although Fecundin treatment in early lambing flocks (using progestagen sponges with and without PMSG)gave an increased litter size over controls there was a considerable reduction infertility which negated this advantage. These groups employed a regime of a sensitising injection, a boosting injection 28-30 days later, and ram introduction to an induced oestrus after a further 28 days(i.e. a Boost Tupping Interval (BTI) of 28 days) for the second group and 35 days for the first.
Effect of concentrate to silage ratio and hoof trimming on lameness in dairy cows
Authors: Manson Felicity J , Leaver J D
Published: June 2019

Lameness in dairy cows has both important animal welfare and economic implications. High concentrate to silage ratios may be an important predisposing factor, whilst trimming has been advocated as an effective preventative measure. This trial examined the effects of these two factors on locomotion, incidence of lameness and hoof measurements.
Relationship between ultrasonic fat depth assessments of commercial breeding sows at the p2 and hip bone positions and herd performance
Authors: Simmins P.H.
Published: June 2019

The reproductive performance of the sow may be associated with the amount of fat stored in the body and the rate at which fat may be depleted. As body fat represents the easily mobilisable reserves of energy, an accurate and practical measurement of fat content is crucial. King et al (1986) have shown that linear baekfat measurements are the best single predictors of body fat compared to any other indirect indices of body composition. However practical experience has also suggested that fat measurements over the tuber coxae of the ileum (hip bone) will also provide an assessment of the fat status of a sow although its relationship to back fat depth is uncertain. Furthermore ultrasound techniques have not been tested in commercial conditions and the effectiveness of normal commercial practice in maintaining body fat reserves has not been previously examined.

The object of the investigation was to assess whether the fat status of the sow as determined by ultrasonic fat measurements at the P2 position (6.5 mm from the midline of the backbone at the last rib) and hip bone would give an objective assessment of the condition and performance of the sow. The effectiveness of normal commercial practice in maintaining herd condition was also assessed.
Effect of level of food intake on the reproductive performance of ewes in different levels of body condition at mating, following passive immunisation against testosterone
Authors: Rhind S.M. , Morris B.A. , Clayton Jill
Published: June 2019

In a 2 x 2 x 2 experiment, 296 Scottish Blackface ewes were fed to achieve one of 2 levels of body condition (high : C.S. ⩾ 2.75; low : C.S. ⩽ 2.50). Half of the ewes of each condition group were then fed dried grass pellets ad libitum with 300 g hay/ head/day (high intake); the remainder were fed a liveweight maintenance ration of 750 g pellets and 400 g hay/head/day (low intake) between 14 days before and 8 days after joining. Thereafter, feed levels for both groups were gradually adjusted to 1250 g pellets and 400 g hay/head/day which was fed until mid pregnancy after which they were fed according to foetal load. Mean daily inatkes of dried grass pellets for ewes fed ad libitum were 2.45 and 2.27 kg fresh weight/head/day for ewes in the low and high condition groups respectively. The patterns of liveweight and condition score changes associated with these feeding regimes are summarised in Table 1.
The Demise of Paganism
Authors: O'Donnell James J.
Published: June 2019

There exists a large, remarkably homogeneous literature on the conflict between paganism and Christianity in the last decades of the fourth century. This study is a preliminary attempt to re-examine that conflict and point out new lines for interpretation of familiar evidence. A redefinition of our conceptions of what paganism was at this period will be followed by a close study of the men and events around whom the traditional narratives of its last revivals have been constructed. A concluding section will outline the ways in which, according to the new definitions proposed here, paganism may be said to have survived its apparent destruction.
Plautus' ‘Trinummus': The Absurdity of Officious Morality
Authors: Anderson William S.
Published: June 2019

Plautus' Trinummus has won much praise from those who seek a strong ethical line in comedy and believe that, in the rare instance of this Plautine play, they have found it. Such critics classify it as an exception from the usual irreverence of the playwright, along with the Captivi. More than 200 years ago, Lessing extolled the Captivi as the finest play, not just of Plautus, but of antiquity. The Trinummus came a close second in his estimation, and he demonstrated his affection for both plays by translating and commenting on the Captivi, and by adapting the Trinummus for the German stage in 1750, at the youthful age of twenty-one. Ritschl chose the Trinummus as the first Plautine work to bring out in a careful critical edition, and his edition elicited one of the finest reviews of Theodor Bergk in 1848. The apparently noble ethics of this play encouraged E. P. Morris to edit it for American school and college students, at the end of the nineteenth century. In this century, affection for pronounced ethics has somewhat declined. Therefore, although critics continue to perceive the same emphasis, they are less willing to extol the play as a masterpiece. E. F. Watling, in his Penguin translation of 1964, rather tepidly summarizes the Trin. as ‘a cool leisurely comedy, which offers an agreeably convincing, if partial, picture of Graeco-Roman family problems.’ A decade later, Erich Segal provocatively labeled it as Plautus' only boring play, precisely because of its unusual ethical contents.
A New Eyewitness Account of the Fourth Lateran Council
Authors: Kuttner Stephan , García Y García Antonio
Published: June 2019

Two years ago we briefly announced the discovery of a new document of great interest for the history of the Fourth Lateran Council. Written in Spring 1216 as a letter from Rome, presumably by a German, it was copied by a thirteenth-century scribe into a manuscript now at the Universitäts-bibliothek of Giessen, where it follows directly after theconstitutionesof the council. With its detailed and vivid description of the three plenary sessions and of many events that took place in between, the anonymous report adds considerably to the information we possess from other sources. But although other portions of the Giessen codex have been known and used by many scholars ever since the eighteenth century, this text has been overlooked to the present day. It is a happy coincidence that we are able to present this eyewitness account of the greatest of the ecumenical councils of the Middle Ages while the Second Vatican Council is in session.
The Accidental Carriage of Insects on Board Aircraft
Authors: Laird Marshall
Published: June 2019

Accidental dispersals of medically and agriculturally undesirable insects by sea and air transport are discussed, with attention to the relative importance of the roles of ships and aircraft. World-wide records of insects found on board aircraft and discovered to have been introduced at airfields are briefly reviewed, and consideration is given to ways of meeting the problem by insecticidal treatment and airport insect control. It is felt that the insecticidal treatment of aircraft, even when provided for by comprehensive international regulations and conscientiously undertaken, does not alone provide sufficient protection against insect introductions, and that greater attention should be paid to the preventive aspects of the problem, with particular regard to the control of insects of both medical and economic significance at international airports.
Archaeology in Cyprus, 1954
Authors: Megaw A. H. S.
Published: June 2019

With the closing down of the Curium expedition and the restriction of operations at Koúklia to study of the results of previous campaigns, it would have been a less active year had it not been for some increase in the scale of the operations of the Antiquities Department, notably at Salamis. I am indebted to all those named in this report for kindly communicating information concerning their excavations and research, and to Dr. P. Dikaios for particulars of Cyprus Museum acquisitions.
Global Power Shifts, Diversity, and Hierarchy in International Politics
Authors: Parmar Inderjeet
Published: June 2019

Liberal internationalism is under the microscope as never before as it faces a world experiencing turbulence and anxiety. The specter of right-wing authoritarianism and even fascism haunt Western societies as struggles for recognition dominate domestic politics, while demands of (re)emerging states for international representation grow more compelling. Simultaneously, there is broader recognition of a growing legitimacy crisis of the American hegemon principally due to the mindsets and failures of its liberal hegemonic elites. Both developments are major advances in the understandings of how the West dominates “diversity regimes” and co-opts discourses universal in origin and character and of how the U.S. foreign policy establishment has brought the world to the current conjuncture. Yet, there are limitations still. Although central, the concepts of diversity, hierarchy, and elites need to be broadened out significantly, and rooted in corporate-class power, to fully comprehend the core crises of the international order today.
The Future Impact of Artificial Intelligence on Humans and Human Rights
Authors: Livingston Steven , Risse Mathias
Published: June 2019

What are the implications of artificial intelligence (AI) on human rights in the next three decades? Precise answers to this question are made difficult by the rapid rate of innovation in AI research and by the effects of human practices on the adaption of new technologies. Precise answers are also challenged by imprecise usages of the term “AI.” There are several types of research that all fall under this general term. We begin by clarifying what we mean by AI. Most of our attention is then focused on the implications of artificial general intelligence (AGI), which entail that an algorithm or group of algorithms will achieve something like superintelligence. While acknowledging that the feasibility of superintelligence is contested, we consider the moral and ethical implications of such a potential development. What do machines owe humans and what do humans owe superintelligent machines?
Artificial Intelligence: Power to the People
Authors: Roff Heather M.
Published: June 2019

To adequately estimate the beneficial and harmful effects of artificial intelligence (AI), we must first have a clear understanding of what AI is and what it is not. We need to draw important conceptual and definitional boundaries to ensure we accurately estimate and measure the impacts of AI from both empirical and normative standpoints. This essay argues that we should not conflate AI with automation or autonomy but keep them conceptually separate. Moreover, it suggests that once we have a broad understanding of what constitutes AI, we will see that it can be applied to all sectors of the economy and in warfare. However, it cautions that we must be careful where we apply AI, for in some cases there are serious epistemological concerns about whether we have an appropriate level of knowledge to create such systems. Opening the aperture to include such questions allows us to further see that while AI systems will be deployed in a myriad of forms, with greater or lesser cognitive abilities, these systems ought never to be considered moral agents. They cannot possess rights, and they do not have any duties.
Isotopic Determination of Growth and Longevity in Fossil and Modern Invertebrates
Authors: Jones Douglas S.
Published: June 2019

The isotopic composition of fossil invertebrates contains a wealth of information about the physical and chemical environments of the ancient past. The exploitation of this biogeochemical archive by paleontologists began about 50 years ago with the realization that the ratios of oxygen isotopes in the shells and skeletons of marine organisms offered the potential to accurately reconstruct paleoenvironmental conditions, particularly temperature (Urey, 1947; Urey et al., 1951). With the introduction of the oxygen isotope paleotemperature methodology (Epstein et al., 1951, 1953; Epstein and Lowenstam, 1953), the field of “isotope paleontology” was born (Wefer and Berger, 1991).
Recognition and Macroevolutionary Significance of Photosymbiosis in Molluscs, Corals, and Foraminifera
Authors: Norris Richard D.
Published: June 2019

Symbiotic relationships are common between algae and diverse lineages of corals, planktic foraminifera, benthic foraminifera, and bivalves as well as in many other groups that do not leave an extensive fossil record. Ancient photosymbioses can be inferred using various lines of inference including the morphology of the host, its habitat, rates of calcification, (which tend to be high in many photosymbiotic taxa), and the geochemistry of the host's shell. This survey shows that stable isotopes are reliable means of identification of photosymbioses in corals and planktic foraminifera, but are far less reliable in benthic foraminifera and bivalves. Organisms that increase their symbiont density proportionate to their own growth display a steep rise in shell δ13C, while organisms whose own growth exceeds that of their symbiont population display a far smaller effect on shell δ13C.
Science and Religion at the Turn of the Millennium
Authors: Bryan Jonathan R.
Published: June 2019

The categories of conflict, independence, dialogue, and integration have been used to organize the wealth of opinion on the relationship of science and religion (Barbour, 1997). This approach is especially useful in college or high school science courses, or special seminars, because it allows the instructor to locate his or her own opinion, and challenge students to determine their own beliefs. This effectively lays most opinions “on the table” for display in a free market of ideas. Using this approach, students can examine the strengths and shortcomings of major opinions, and it has the advantage of preserving the dignity of all religious views that reside in the science classroom, without compromising any science. The wealth and depth of new ideas that have been forthcoming from both science and theology offer the exciting promise of future wisdom that can serve both religion and science.
The Age of the Earth–A Summary
Authors: Dalrymple G. Brent
Published: June 2019

After two centuries of scientific endeavor, scientists have concluded that the age of the Earth is 4.54 billion years. This value, which is based on the relationships between lead isotopes in meteorites and in the Earth, has an uncertainty of less than 1 percent and is consistent with numerous radiometric age measurements on ancient rocks found on the Earth and Moon as well as on meteorites. In addition, the antiquity of the Earth is consistent with evidence indicating that the Milky Way Galaxy and the universe are of the order of 14-16 billion years (abbreviated Ga) in age.
Problem Concepts in Evolution: Cause, Purpose, Design, and Chance
Authors: Scott Eugenie C.
Published: June 2019

The American student population is largely religious and a significant minority rejects evolution. Evolution and other scientific theories are restricted to explaining through natural cause (methodological materialism), but because evolution has existential connotations, many students confuse theabilityto explain through natural cause with a conclusion that therefore God does not exist (philosophical materialism). To some, if God does not exist, life has no purpose or meaning, and acceptance of evolution brings on an existential crisis. Differing understandings of four concepts (cause, purpose, design, and chance) commonly used in the teaching of evolution may exacerbate antievolutionism if students conflate their own existential meanings of these terms with the definitions within science.Cause, purpose, anddesignto many students include the notion ofsupernaturalcause, purpose, and design, whereaschanceis often thought to mean “purposeless” or “random” (in the sense of unpredictable.) Professors should teach evolution in a religiously-neutral fashion, thus allowing religious students to find compatibility between their religious views and science.
The Trophic Role of Marine Microorganisms Through Time
Authors: Lipps Jere H. , Culver Stephen J.
Published: June 2019

Microorganisms (prokaryotes and protists) seldom fossilize, but they form much of the trophic structure in marine pelagic and benthic environments, chiefly as primary producers and secondary consumers. The fossil record of unskeletonized groups is meager or non-existent. Skeletonized groups have excellent records but represent a small portion of the total microbial diversity.

The evolution of trophic structures and roles of microorganisms can be reconstructed broadly for most of geologic history. When life first evolved, it had a trophic structure. The first microbial fossils appear to be benthic mats; these are abundant in the Precambrian but sparse later; body fossils are very rare. The Archean saw pelagic and benthic prokaryotes and possibly protists later on. Proterozoic trophic structures became increasingly complex as protists entered pelagic environments. Benthic assemblages likewise became complex, as prokaryotes and protists formed mats and stromatolites in many environments. At the end of the eon, animals appeared; microbial primary producers and predation on microorganisms and among animals fueled these assemblages. The fundamental trophic structures that developed then persisted with modification into modern times. Phanerozoic ecosystems became very complex as skeletonized animals and protists evolved. Among the important trophic developments in the Phanerozoic history of microorganisms were the early diversification of phytoplankton and siliceous micro-zooplankton (Cambrian), algal endosymbiosis with benthic metazoans (Cambrian to Recent) and rock-forming foraminifera (late Paleozoic to Recent), the radiation of pelagic skeletal primary producers and micro-zooplankton (mid-Mesozoic), and radiations in the deep sea, reefs, and shallow areas (Mesozoic and Cenozoic). Each evolutionary change increased trophic complexity by adding more species at each level, while episodic mass extinctions decreased species diversity and trophic complexity.

Marine trophic structures evolved over immense intervals of geologic time, growing complex and then suffering destruction at major extinction events. The effects of human impact on these structures should be examined, for without them, Earth may change dramatically.
Fossil Record of Parasitism on Marine Invertebrates with Special Emphasis on the Platyceratid-Crinoid Interaction
Authors: Baumiller Tomasz K. , Gahn Forest J.
Published: June 2019

The paleontological literature on marine invertebrates is rich in supposed examples of parasitism and our tabulation shows a nearly even distribution of reported cases through the post-Cambrian Phanerozoic. Slightly lower frequencies characterize the Triassic and Jurassic and higher frequencies the Cretaceous and Tertiary, and the pattern roughly mirrors Sepkoski's (1984) marine diversity curve. The total number of parasitic associations for any geologic period rarely exceeds a dozen, yet few of the reported examples provide explicit criteria distinguishing parasitism from predation, commensalism, or mutualism. We evaluated the published examples using the following criteria: (1) evidence of a long-term relationship between two organisms, (2) benefit of interaction to supposed parasite, and (3) detriment of interaction to the host We found that only in exceptional cases were these criteria fulfilled. One example that provides much information on parasitic interactions involves platyceratids and crinoids and we summarize the evidence for the parasitic interaction between these two groups of organisms.
Origins and Early Evolution of Predation
Authors: Bengtson Stefan
Published: June 2019

Predation, in the broad sense of an organism killing another organism for nutritional purposes, is probably as old as life itself and has originated many times during the history of life. Although little of the beginnings is caught in the fossil record, observations in the rock record and theoretical considerations suggest that predation played a crucial role in some of the major transitions in evolution. The origin of eukaryotic cells, poorly constrained to about 2.7 Ga by geochemical evidence, was most likely the ultimate result of predation among prokaryotes. Multicellularity (or syncytiality), as a means of acquiring larger size, is visible in the fossil record soon after 2 Ga and is likely to have been mainly a response to selective pressure from predation among protists. The appearance of mobile predators on bacteria and protists may date back as far as 2 Ga or it may be not much older than the Cambrian explosion, or about 600 Ma. The combined indications from the decline of stromatolites and the diversification of acritarchs, however, suggest that such predation may have begun around 1 Ga. The Cambrian explosion, culminating around 550 Ma, represents the transition from simple, mostly microbial, ecosystems to ones with complex food webs and second- and higher-order consumers. Macrophagous predators were involved from the beginning, but it is not clear whether they originated in the plankton or in the benthos. Although predation was a decisive selective force in the Cambrian explosion, it was a shaper rather than a trigger of this evolutionary event.
Against object agency 2. Continuing the discussion with Sørensen
Authors: Ribeiro Artur
Published: June 2019

This paper expands upon some of the arguments and issues surrounding object agency that have been discussed in this journal (Lindstrøm 2015; 2017; Ribeiro 2016a; 2016b; Sørensen 2016; 2018). More specifically, it challenges Sørensen’s support of object agency in his latest discussion on the topic (2018). The paper is divided into three parts: first, it questions the relevance of replacing the conventional usage of ‘agency’, generally attached to sociological studies and reserved to describe human action, with one supported by the New Materialists; second, it identifies a series of contradictions in how agency is defined according to the New Materialisms, namely how it can be very labile and scalable yet simultaneously universal and applicable across all cultures and time periods; and lastly, it questions the quality of the philosophical ideas supporting the New Materialist conception of agency, and its disadvantages in light of the current re-emergence and repopularization of processual archaeology.
Environmental determinism and archaeology. Red flag, red herring
Authors: Riede Felix
Published: June 2019

When first asked to comment upon the contribution of Arponen et al. on environmental determinism in archaeology – a red flag to many – I became excited that the topic is receiving attention again and, not least, that this attention is translating into printed debate. I commend the authors on their effort, also for bringing together multiple voices in their article. All too rarely do theoretical contributions translate into multiple authorship. I cannot in any way disagree with their key conclusions, namely that investigations of deep-time relations between humans and the environment are not just timely but important, and that archaeology should make full use of its rich array of data, cases and dissemination possibilities to investigate them and make them relevant in the present.
Two cultures in the times of interdisciplinary archaeology. A response to commentators
Authors: Arponen V. P. J. , Dörfler Walter , Feeser Ingo , Grimm Sonja , Groß Daniel , Hinz Martin , Knitter Daniel , Müller-Scheeßel Nils , Ott Konrad , Ribeiro Artur
Published: June 2019

We would like to begin by thanking the journal and the commentators for their time and attention.
Linear and threshold model genetic parameters for disease, fertility and milk production in dairy cattle
Authors: Kadarmideen H. N. , Thompson R. , Simm G.
Published: June 2019

A combination of better management and genetic selection for good health and fertility would provide a more effective long term solution for economic loss due to diseases and poor fertility. This would also help to address public concerns about the use of medical treatment in milk production. A balance in the genetic improvement of health and fertility together with milk production could be achieved through their inclusion in national genetic selection indices, for which genetic parameters are needed. One of the main objectives of this study was to estimate genetic parameters for various disease and fertility traits in the UK dairy cattle population, using records from a national recording scheme run by Livestock Services UK Ltd. Genetic analysis of traits recorded as present or absent (binary traits; e.g. diseases) requires the use of non-linear threshold models, because linear models require normality assumptions (e.g., Gianola 1982). The other objective of this study was to estimate genetic parameters for binary disease and fertility traits based on threshold animal models and to compare results with those from linear animal models.
Livestock, land use change, and environmental outcomes in the developing world
Authors: Blake R.W. , Nicholson C.F.
Published: June 2019

Rapid predicted worldwide growth in demand for animal products to 2020, the so-called “next food revolution” in animal agriculture, portends complex interactions among people, biological and geophysical resources, and economic objectives. Consumer demand for beef and pork is expected to increase by 2.8% per year, somewhat slower than demand growth for poultry meat (3.1%/yr). Demand for dairy products is predicted to grow fastest, at 3.3%/yr (Delgado et al., 1999).
Demand-driven crop-ruminant intensification: trans-regional analysis to understand patterns of change using village level data from three continents
Authors: Baltenweck I. , Staal S. , Ibrahim M.N.M.
Published: June 2019

The growing demand for livestock products in the developing world is expected to drive livestock production in these countries. Delgado et al. (1999) predict that by 2020, developing countries will produce on average 38% more meat and 54% more milk per capita than in the early 1990s. The livestock revolution could then translate into opportunities for smallholder livestock producers. In the case of ruminants, much of this increase may occur in mixed farming systems, rather than through industrial production. In 1991–93, mixed systems produced 92% of the world's milk, and 54% of the world's meat (de Haan et al., 1997).
Effect of intensification on feed management of dairy cows in the Central Highlands of Kenya
Authors: Romney D. , Utiger C. , Kaitho R. , Thorne P. , Wokabi A. , Njoroge L. , Chege L , Kirui J , Kamotho D. , Staal S.
Published: June 2019

In sub-Saharan Africa mixed crop-livestock systems predominate in the semi-arid, sub-humid and cool highland zones. In these areas, systems intensify and crops and livestock become increasingly integrated as the human population increases and land becomes a more important constraint than labour (Boserup, 1965; McIntireet al., 1992). As intensification progresses, use of crop residues moves from open access to crop fields, following harvest, to labour intensive management of cereals as dual-purpose crops.
GM technologies – opportunities and threats of applying GM technology in less developed and developed countries. ‘Aladdin's Cave or Pandora's Box?’
Authors: Bennett A.
Published: June 2019

Globalization describes the many processes by which society is becoming more interconnected and interdependent. It has many dimensions, trade, finance, information, culture, tourism, the spread of pests and diseases, migration, corruption, environmental change and the supply of food. It is here to stay and offers many opportunities for growth and change. The challenge must be, ‘can it be made to work for the reduction of poverty, instability and hunger?’

The Food and Agriculture Organisation (FAO) and the Consultative Group on International Agricultural Research (CGIAR) confidently predict that the demand for meat and animal products will increase by 50% between 2000 and 2020 and for eggs by 25% over the same period.
Ephemerides and Celestial Mechanics
Authors: Abalakin Victor K.
Published: June 2019

When solving some abstract problems in mechanics related to the dynamics of bodies and systems, the notion of an inertial frame of reference is introduced in an apparently clear and natural way by simply drawing its coordinate axes and then paying no further attention to the system of reference which is then taken for granted. If we turn, however, towards investigations of the real stellar and planetary world, or as Sir James Jeans put it, “… to the Universe around us,” we immediately face the question of how to practically construct a useful and obvious model of the inertial frame of reference sufficiently close to reality.
Hipparcos and Celestial Reference Frame
Authors: Kovalevsky J.
Published: June 2019

A discussion of four methods that can be used to link HIPPARCOS to an absolute reference system shows that the best method is to refer it to extragalactic objects. This would free the resulting frame from any parameter describing Earth’s motion.
Related Binaries, Including Symbiotic Stars
Authors: Sahade Jorge
Published: June 2019

In the context of the Joint Discussion, it is clear that by “long period binaries” we understand the system of ∊ Aurigae and theζAurigae systems. The question is, then, how to determine which systems could be considered “related” to those long period ones.
Nonradial and radial oscillations observed in non-emission line OB dwarfs and giants
Authors: Baade Dietrich
Published: June 2019

Only a decade ago, this talk could have concerned only the β Cephei stars which however populate a much more precisely defined strip in the Hertzsprung-Russel diagram (MED). But recent reconnaissance surveys (Smith 1977; Smith and Penrod 1984; Waelkens and Rufener 1985; Baade, in preparation) show that perhaps only one, if any, sizeable region of the upper HRD is devoid of nonradially pulsating stars. The identification of the driving mechanism is still pending (cf. the parallel talk by Osaki), and apparently our knowledge about the internal structure of OB stars is incomplete. But, turning that argument around, it also is indicative of how much may be learned about OB stars from and through the solution of that fundamental problem. This seismologial potential, the ubiquity of the phenomenon, and the effect, as suggested by recent observations of some stars, of the pulsations on the mass loss of OB stars make the oscillations of OB stars one of the most important problems of current astrophysics. On the observational side, rotationally broadened spectral lines, large amplitudes, comparatively long periods, and high luminosities permit information to be gathered which otherwise is accessible only for the sun.
Nlte-Effects in Supernovae Type II Photospheres
Authors: Höflich P. , Wehrse R. , Shaviv G.
Published: June 2019

In order to provide accurate fluxes of supernovae Type II as needed for the application of the Baade-Wesselink method we have constructed spherical model photospheres for these objects under the assumption that hydrogen and helium are in statistical equilibrium. Although the densities are very low it is found that NLTE effects on the continuum radiation are small, because the temperature stratification is sufficiently flat and the strong scattering makes the radiation field rather local.
Hipparcos – Tycho: Photometry & Astrometry for more than 500 000 Stars
Authors: Grewing M. , Høg E.
Published: June 2019

The Hipparcos star mapper will be used to determine magnitudes in two colours and the positions for about 500 000 stars. The typical accuracy for the mean values is about 0.03 mag and 0.03 arcsec respectively for a star of B = 11.0 mag and B-V = 0.7 mag. The photometric system and part of the data analysis are outlined.
Coronal Holes and Flare Related Phenomena
Authors: Shelke Rajendra N. , Pande M. C.
Published: June 2019

We conclude that coronal holes exhibit differential rotation and they do not follow a specific polarity rule. Further, proximity of holes to type II burst rich active regions (ARs) indicates that shock waves propagate almost along the magenetic field of the holes.
Synthetic Photometry and the Calibration of the Hubble Space Telescope
Authors: Koornneef J. , Bohlin R. , Buser R. , Horne K. , Turnshek D.
Published: June 2019

The combined Scientific Instruments (SIs) on the Hubble Space Telescope (HST) feature an extensive wavelength coverage in both photometric and spectrophotometric modes with an overall dynamic range of more than twenty-five magnitudes. We demonstrate how synthetic photometry techniques are to be used to establish and maintain their calibration. This approach makes efficient use of limited HST observing time by taking full advantage of pre-launch knowledge on the SI sensitivity functions and calibration targets.
Millisecond Pulsars
Authors: Krolik J.H.
Published: June 2019

Millisecond pulsars are intrinsically interesting because they illustrate some of the most extreme physical conditions to be found anywhere in the Universe, and because their evolution exhibits several stages of great drama. It had been widely believed for several years that spin-up of an old neutron star by accretion from a close stellar companion explained their fast rotation, but the absence of companions in several cases cast doubt on that picture. This spring a millisecond pulsar in a close binary was discovered in which the companion appears to be evaporating, thus reconciling the existence of lone millisecond pulsars with the standard picture. Ongoing observations of this new system, and complementary calculations, promise to answer many of the questions remaining about this dramatic phase in stellar evolution.
Spatially Varying Optical Properties of the Zodiacal Dust
Authors: Hong S. S. , Kwon S. M.
Published: June 2019

Analyses of both the zodiacal light in the visible and the zodiacal emission in the infrared have provided us with ample evidence to claim that the interplanetary dust particles are mixtures or coagulations of more than one constituents and their mixing ratios vary with the distance from the sun.
Some Salient Features of Evolving Models of Interstellar Clouds
Authors: Tarafdar S. P. , Ghosh S. K. , Heere K. R. , Prasad S. S.
Published: June 2019

Difficulties faced by various models of interstellar clouds have been discussed. A new evolutionary model which uses energy equation instead of empirical temperature-density relation used in earlier models has been presented. This calculation shows that for a given initial density, the collapsing cloud has a minimum mass which is significantly smaller than the Jean's mass. The clouds with larger mass than the critical mass continue collapsing and physical and chemical evolution remain similar to earlier evolving models. Clouds with mass smaller than the critical mass initially collapse but ultimately bounce back, producing physically similar clouds in collapsing and expanding phases. The chemical evolution in these two physically similar clouds is different mainly due to differences in their lifetime. The lifetime of this oscillating cloud is also longer than the collapsing cloud.
Large Scale Jets in Class I and Class II Radio Sources and Quasars
Authors: Bicknell G.V.
Published: June 2019

The physics of large scale jets in class I and class II extragalactic radio sources and quasars is discussed. Class I jets appear to be turbulent, transonic jets which entrain the interstellar medium. The related jet deceleration causes a slow surface brightness decline which is usually observed. Class II jets are supersonic and terminate in an advancing shock against the external medium. Both types of jet are initially light but the ratio of jet density to external density of class I jets increases owing to entrainment. It is quite plausible that quasar jets are hypersonic and light and this may solve problems of confinement. The velocities of class I jets are of the order of a few thousand kilometers per second. Class II and quasar jets may be at least mildly relativistic. However, it is not clear whether the velocities of large scale jets in powerful sources are close to the speed of light. Recent depolarization measurements provide an interesting focus for discussion of this question.
The Science Program of the Hubble Space Telescope
Authors: Bahcall Neta A.
Published: June 2019

Highlights of the science program to be carried out by the Hubble Space Telescope are reviewed. Some of the main scientific projects to be carried out by the General Observers (GOs) and the Guaranteed Time Observers (GTOs) during the early phases of the Space Telescope are discussed. The method and criteria for selecting science projects are also discussed.
The Space Telescope Imaging Spectrograph
Authors: Woodgate Bruce E
Published: June 2019

The Space Telescope Imaging Spectrograph (STIS) is a second generation instrument to be installed into the Hubble Space Telescope (HST) in-orbit 5–9 years after the first launch. Together with the infra-red instrument, it will provide a large increase in capability of the observatory, and be able to replace a first generation that had failed or degraded.
“For Milliarcsecond or Better Accuracy”
Authors: Seidelmann P. K.
Published: June 2019

The accuracies being achieved in astrometry, celestial mechanics, Earth Orientation, ephemerides and time have been improving significantly in recent years.

The introduction of the improved astronomical constants, ephemerides, time scales and nutation as adopted from 1976 to 1984 has had the desired effect of permitting the investigation of systematic effects at precisions of an order of magnitude better than previously possible.

Therefore, there have been many developments in observational data, in theories, and in astronomical computations that have promised, or claimed, to deliver accuracies of a milliarcsecond or better.

Working Groups had been established with interrelationships in their scopes of activities. It did not appear that any of the working groups were prepared to present final recommendations that would be generally accepted.
Solar and stellar Winds
Authors: Withbroe G. L.
Published: June 2019

This review discusses winds from stars with hot outer atmospheres, stars with coronae similar to the sun. It illustrates how solar observations can be used to test a theoretical model for solar-stellar winds, and thereby provide some insights concerning applications to studying winds from stars other than the sun.
Introduction to the Joint Commission Meeting on High Resolution Imaging from the Ground
Authors: Davis John
Published: June 2019

As a result of advances in instrumentation and techniques, from radio through to optical wavelengths, we have before us the prospect of producing very high resolution images of a wide range of objects across this entire spectral range. This prospect, and the new knowledge and discoveries that may be anticipated from it, lie behind an upsurge in interest in high resolution imaging from the ground. Several new high angular resolution instruments for radio, infrared, and optical wavelengths are expected to come into operation before the 1991 IAU General Assembly.
Is The Imaging Problem Identical in All Wave Bands?
Authors: Baldwin J.E.
Published: June 2019

One aim of this meeting is to tempt us to study methods of imaging in wavebands outside our own. This might seem perverse since the imaging problems in the radio and optical/IR regions appear at first sight to differ profoundly in several ways: the rapid evolution of radio imaging over the last forty years has been largely ignored in optical imaging whilst the well developed theory and measurements of atmospheric fluctuations for the optical regime have been disregarded by radio astronomers; there have been long and exacting searches for the best sites for optical telescopes, but rarely for radio telescopes; the instrumental techniques appear to differ in many and complicated ways.
Gravitational Lensing
Authors: Refsdal Sjur , Surdej Jean
Published: June 2019

Atmospheric lensing effects deform our view of distant objects; similarly, without any doubt, gravitational lensing perturbs our view of the distant Universe and affects our physical understanding of various classes of extragalactic objects. We summarize here part of the theoretical and observational evidences supporting these claims.

After briefly reviewing the history of gravitational lenses, we recall the basic principles underlying the formation of gravitationally lensed images of distant cosmic sources. We describe a simple optical lens experiment, which was actually shown during the oral discourse, and which accounts for all types of presently known gravitational lens systems.

The various optical and radio searches for new gravitational lens systems that are being carried out at major observatories are reviewed. State-of-the-art observations of selected gravitational lens systems, obtained with highly performing ground-based telescopes, are then presented. These include several examples of multiply imaged QSO images, radio rings and giant luminous arcs.

Through the modeling of these enigmatic objects, we show how it is possible to weigh the mass of distant lensing galaxies as well as to probe the distribution of luminous and dark matter in the Universe. Among the astrophysical and cosmological interests of observing and studying gravitational lenses, we also discuss the possibility of deriving the value of the Hubble parameter Ho from the measurement of a time delay, and how to determine the size and structure of distant quasars via the observational study of micro-lensing effects.

At the end of this paper, we conclude on how to possibly achieve major astro-physical and cosmological goals in the near future by dedicating, on a site with good atmospheric seeing conditions, a medium size (2-3 m) telescope to the photometric monitoring of the multiple images of known and suspected gravitational lens systems.
Presentation of WGRS Recommendations I to V
Authors: Guinot B.
Published: June 2019

I start by general remarks on the background of the recommendations on space-time references which are submitted to you.

The need to consider time scales in a relativistic framework appeared more than 20 years age following the progress of atomic time standards. After long discussions, this led the IAU to define, In 1976, time scales which were designated, In 1979, as Terrestrial Dynamical Time (TDT) and Barycentric Dynamical Time (TDB). But soon afterwards difficulties in the interpretation of the definitions of TDT and TDB arose. It appeared that the source of these difficulties was the lack of a global approach to space-time reference systems. This point of view, first voiced by J. Lieske, gained acceptance. At the very beginning of the work of the WGRS Sub-Groups on Frames and Origins (SGFO) and on Time (SGT), It became clear the the primary mission of the SGFO and SGT was to jointly prepare general recommendations on space-time references on which they could base their specific recommendations.
IERS Standards
Authors: McCarthy D.
Published: June 2019

Due to weather-related travel delays Dr. McCarthy was unable to present his scheduled paper. In his absence, however, Dr. K. Yokoyama, Chairman of the International Earth Rotation Service (IERS), reported on the status of the revision of the IERS Standards carried out by McCarthy who provided the following precis.

These standards are meant to be used in the reduction of observations contributed to the IERS and by those who require IERS estimates of polar motion, Universal Time and nutation to establish the most precise celestial and terrestrial reference systems. The goal of the IERS is to publish the document, an update of the previous version (McCarthy, 1989), in the beginning of 1992.
BBXRT Observations of Supernova Remnants
Authors: Petre R. , Serlemitsos P. J. , Marshall F. E. , Jahoda K. , Boldt E. A. , Holt S. S. , Mushotzky R. F. , Swank J. , Szymkowiak A.E. , Kelley R. , Smale A. , Arnaud K. , Weaver K.
Published: June 2019

The BBXRT observed nine supernova remnants during its nine-day flight. We present preliminary results from some of these observations, emphasizing the ability of BBXRT to perform spatially resolved spectroscopy. The improved spectral resolution and efficiency over previous instruments makes possible measurements of previously undetectable lines, and the broad bandpass allows simultaneous measurement of lines from oxygen through iron.
Assessment of the Quality of the IDT Elemental Observations
Authors: Perryman M.A.C.
Published: June 2019

The quasi-simultaneous measurement of the one-dimensional angular separation of stars on the sky, on both small and large angular scales, rely on the measurements made by the IDT detector, as well as on inputs from the star mapper and attitude control system. This presentation will concentrate on the results of a comparison of the results of the IDT data processing carried out by the FAST and NDAC data analysis teams. The extent to which the intensity and phase measurements agree between the two reductions, and the extent to which the differences are consistent with expected photon noise errors, will be illustrated.