bluuebunny/crossref_metadata_2025 huggingface dataset:
Teaching Astronomy at the University of South Africa
Authors: Wargau W.F. , Cunow B. , Schutte C.J.H.
Published: June 2019

The University of South Africa celebrates its 50th anniversary this year. Over this period it grew, becoming one of the largest tertiary distance education institutions and the largest university on the African continent.

South Africa always had a mixed racial population with each group having its own culture. This difference between people is further aggravated by differences in the level of “westernisation”. Furthermore, South Africa also suffers from an extreme urbanisation problem where on the one hand we find modern cities and on the other tribal groups. All these factors led to a differentiation of the population into a first world and third world component.
British Planetaria and the National Curriculum
Authors: Tidey Steve
Published: June 2019

The UK is experiencing a relative Golden Age for planetaria, thanks in many ways to its national curriculum. In 1991 the British government finally bowed to many years of steady pressure by interest groups and introduced into a new and controversial general curriculum a requirement for pupils to attain knowledge about the Earth-Moon system, solar system objects and basic cosmology. Prior to this there had been no science curriculum for pupils aged under 11. Astronomy formed a small part of nature study. The science education of 11–16 year-olds depended on their GCSE syllabuses.
Current Trends in European Astronomy Education
Authors: West Richard M.
Published: June 2019

Astronomy knows no geographical borders - the sky is the same over all countries. However, while professional astronomers have long established bi- and multilateral collaborations, many of which take place under the auspices of the IAU, few similar schemes exist within astronomy education.

Now, following the establishment in 1995 of the European Association for Astronomy Education (EAAE), this situation is about to change on that continent. This new association offers an efficient platform for astronomy educators at various levels - in particular at the approx. 7000 secondary schools in this geographical area - to interact in all related matters, e.g. curricula, all kinds of teaching materials, student exchanges and other events. Together with the European Commission and some of the professional institutes, EAAE is now planning a major, international event in November 1996.
The Training of Teachers
Authors: Gouguenheim L. , Gerbaldi M.
Published: June 2019

Informal and formal astronomy education is present through many channels: newspapers and TV; amateur associations; clubs and science associations; at school at any level. The teachers are not only the main agents of the educational process at school, but they are also very active in extra-curricular activities: they run clubs, educational projects etc.

These activities are present everywhere in the world, as can be seen from the reading of the National Reports published every 3 years by Commission 46 “Astronomy Teaching” of the International Astronomical Union and published in its Newsletter.
The Use of Terms and Definitions in the Study of Be Stars (Review Paper)
Authors: Collins George W.
Published: June 2019

In this paper I shall examine the use and misuse of some astronomical terminology as it is commonly found in the literature. The incorrect usage of common terms, and sometimes the terms themselves, can lead to confusion by the reader and may well indicate misconceptions by the authors. A basic definition of the Be phenomena is suggested and other stellar characteristics whose interpretation may change when used for non-spherical stars, is discussed. Special attention is paid to a number of terms whose semantic nature is misleading when applied to the phenomena they are intended to represent. The use of model-dependent terms is discussed and some comments are offered which are intended to improve the clarity of communication within the subject.
Rotating Stellar Interiors (Review Paper)
Authors: Smith Robert Connon
Published: June 2019

Rotation has two main qualitative effects on the structure of a star: it distorts the shape and it reduces the total luminosity. The luminosity depends only on the total angular momentum but the shape, and so the observable properties, depends on the internal distribution of angular momentum. The expected distribution, even for main-sequence stars, is an unsolved problem. Redistribution of angular momentum can occur as a result of large-scale circulation currents, instabilities and magnetic stresses and there may be no steady state. If shear instabilities are dominant, then stars may rotate nearly uniformly. Studies of non-radial oscillations might perhaps eventually lead to a direct probing of the internal angular momentum distribution by the methods now being used to study the internal rotation of the Sun. Differential rotation near the surface would probably give rise to turbulent motions, which could generate the mechanical energy flux which seems to be a necessary input to the winds in hot stars.
Narrow Absorption Components in The UV Spectra of HD110432 (B1 IIIe)
Authors: Prinja Raman K. , Henrichs Huib F.
Published: June 2019

We present high resolution IUE ultraviolet observations of multiple narrow absorption components seen in the SiIII, NV, SiIV, and CIV profiles of the B1 IIIe star, HD110432. Spectra taken during March 1986, spanning ∼ 11 days, are modelled using line profile fits. Central velocities and column densities of the discrete features are derived.

The 11 observations obtained during March 1986 (SWP24923–28031) exhibit only minimal line profile variability, but are substantially different from the only other available IUE spectrum of HD110432, taken in April 1981 (fig. 1). This previous image reveals just a single extremely narrow (FWHM ∼ 50 km/s) feature at ∼ 1360 km/s.
Ubiquitous C IV 1550 Variability in B and Be Stars
Authors: Sonneborn G. , Garhart M.P. , Grady C.A.
Published: June 2019

Studies of line profile variability of the ultraviolet 1550 Angstrom resonance transitions of C IV in Be stars (Sonneborn et al. 1986; Grady, et al. 1986a,b) have prompted an investigation into the short- and long-term behavior of the C IV lines in other types of B stars. We present examples of two well-studied Be stars, Omega Orionis and 66 Ophiuchi, and two non-Be stars, Beta Cephei and the standard star Zeta Cassiopeiae. Zeta Cas is also known to be a 53 Per variable (see Cox 1983). The IUE SWP high-dispersion spectra of Beta Cep and Zeta Cas have been obtained from the IUE archives. It has been known for some years that the C IV line profiles in Beta Cep vary in a time scale of several days (Fishel and Sparks, 1980). However, it came as a surprise to discover C IV variability in Zeta Cas. Available data allow us to set an upper limit of several months for the time scale of Zeta Cas C IV variability. The principal difference between the C IV variability in Be and non-Be stars appears to be the magnitude and velocity range of the effect.
The Be/X-Ray System HDE 245770/A0535+26 in an Active Phase
Authors: Bartolini C. , Burger M. , van Dessel E.L. , Giovannelli F. , Guarnieri A. , de Loore C. , Piccioni A.
Published: June 2019

The principal aim is to report on the sudden appearance and disappearance of (mainly) Fe II emission lines in the Be/X-ray system HDE 24-5770/ A0535+26, about 24 days before an X-ray outburst was observed. The system is characterized as an 09-7 Ille star of mass 20-25 M⊙, accompanied by a neutron star (X-ray pulse period ≃104 s), with orbital period -110 d, eccentricity > 0.3; for a more complete description see Giovannelli et al. (1985) or de Loore et al. (1984). X-ray outbursts have been observed recurrently, obviously connected with periastron passage of the neutron star triggering gas infall onto it. The observed X-ray outbursts are of varied strength, from barely detectabl to 3 Crab units at peak (Nagase et al. (1982), Giovannelli et al. (1984)). A weak X-ray event took place on December 13, 1981.
Emission-Line Stars as Interacting Binaries (Review Paper)
Authors: Harmanec P.
Published: June 2019

A general binary hypothesis of the emission-line phenomenon in early-type stars was published eleven years ago (Kříž & Harmanec 1975, Harmanec & Kříž 1976; for a reformulation see Harmanec 1982). Since then, new observational techniques and theoretical concepts have led to a number of exciting findings which have made the emission-line phenomenon even more puzzling and challenging than before. It is therefore of interest to ask whether the binary hypothesis can withstand all these developments or not.
Magnetic-Loop Model For Be Stars (Review Paper)
Authors: Underhill Anne B.
Published: June 2019

The magnetic-loop model for a stellar mantle is described and it is shown how this model may be used to understand the differences in spectrum and change of spectrum which are observed for main-sequence stars haying effective.temperatures in the range from 2.5 x 104 to 3.0 x 104 K.

It is suggested that the difference in spectrum between a shell star such as Gamma Cas when it is in an active state and a Wolf-Rayet star may be due to a difference in environment.
Consistent Spherical NLTE-Models for BE-Stars
Authors: Peter Höflich
Published: June 2019

Spherical NLTE-model photospheres surrounded by envelopes are calculated in order to interpret classical Be-stars. The existence of the Hll-region can be understood by such models. The dependence of the calculated spectra on parameters corresponds to the observations. Applications to special objects show good agreement between the predicted and observed spectra in the visual and infrared wavelengh range.
Effect of Compact Objects Near Be Stars
Authors: Apparao Krishna M.V. , Tarafdar S.P.
Published: June 2019

Several Be stars are identified with bright X-ray sources. (Rappaport and Van den Heuvel, 1982). The bright X-ray emission and observed periodicities indicate the existence of compact objects (white dwarfs, neutron stars or black holes) near the Be stars. A prime example is the brightest X-ray source A0538-66 in LMC, which contains a neutron star with a rotation period of 59 ms. Apparao (1985) explained the X-ray emission, which occurs in periodic flares, by considering an inclined eccentric orbit for the neutron star around the assumed Be-star. The neutron star when it enters a gas ring (around the Be-star) accreting matter giving out X-rays.

The X-ray emission from the compact objects, when the gas ring from the Be-star envelopes the objects, has interesting consequences. The X-ray emission produces an ionized region (compact object Stromgren sphere or COSS) in the gas surrounding the compact object (CO).
Shell Stars in the Geneva Photometric System
Authors: Hauck B.
Published: June 2019

L. Divan (1979) showed that the Balmer jump is greater in a Be-shell star than in a star of same spectral type and we will consider if this property is also present in A and F-shell stars by studying their data in the Geneva photometric system. Two photometric parameters in this system are correlated with the Balmer jump: d=(U-Bl) -1.430 (B1-B2) and Δ=(U-B2) -0.832 (B2-G). In addition to the Balmer jump, Δ is also sensitive to blanketing. Both parameters are reddening free. A study of the Be stars of luminosity class V or IV classified by Slettebak (1982) shows that, in a d vs Δ diagram, they are in the area of main sequence stars or a little above, while the majority of Be-shell stars are above the Be star sequence. Pleione is well known for presenting a Be phase followed by a shell phase.
Infrared Period-Luminosity Relations of RR Lyraes in M5 and Ml5
Authors: Liu T. , Janes K. A.
Published: June 2019

We have carried out K band photometric observations of RR Lyrae stars in two globular clusters which both have large populations of RR Lyraes but different characteristics: the moderately metal-rich cluster M5 ([Fe/H] = –1.40) and the metal-poor one M15 ([Fe/H] = –2.15). The purpose is to accurately calibrate the linear relationship between RR Lyrae infrared (K) absolute magnitudes and their periods that has been confirmed by recent Baade-Wesselink type studies of RR Lyraes and IR photometry of cluster variables. A total of 47 RR Lyraes in M15 was observed and each has more than 8 measures on the average, which allows the accurate determination of a mean K magnitude for each star. In M5 44 stars have been observed with each RR Lyrae having 4 measurements. Our preliminary results show that the RR Lyrae infrared period-luminosity relations for the two clusters have roughly the same slope, despite the fact that they have a large metallicity difference. This suggests that the metallicity effect on the (MK)-log P relation is indeed small as one would expect. The M5 and M15 RR Lyrae IR photometry gives a reliable determination for the slope of the infrared period-luminosity relation because of the large number of stars measured. A well-calibrated (MK)-log P relation will be very useful in distance determinations to heavily reddened star regions such as the Galactic center and globular clusters in the Galactic bulge.
Search for a Secondary Frequency in the Large-Amplitude δ Scuti Star CY Aqr
Authors: Coates D. , Fernley J. , Sekiguchi K. , Barnes T. G. , Frueh M.
Published: June 2019

The large-amplitude δ Scuti star CY Aqr was observed from sites in the U.S.A., South Africa and Australia during August 1988. Coates et al. (1991) published 48 new times of maximum light derived from these observations and assembled, from the literature, previous times of maximum light. It is clear that the period of the star is changing with the balance of evidence favouring discrete changes in 1951 and 1966, rather than a continuous change.

It has been suggested by Fitch (1973) and Else (1972), from an analysis of the observations of Zissell (1968), that there is a secondary frequency present in CY Aqr. Coates et al. (1992) have analysed both the 1988 observations and those of Zissell. After subtracting the primary frequency and its harmonics, they find no stable secondary frequency above the noise level of two millimagnitudes.
Hydrodynamical Models of Radially Pulsating Hot Extreme Helium Stars
Authors: Fadeyev Yu. A.
Published: June 2019

The blue edge of the instability region of radially pulsating helium stars is located on the H-R diagram nearly vertically at luminosities less than 104L⊙ and corresponds to Teff = 7400K and 1.1 · 104K for stars with mass of 1M⊙ and 0.7M⊙, respectively. The pulsation instability of the stars located along the vertical part of the instability edge is characterised by the increasing order of the pulsation mode with decreasing luminosity. For example, for stars with M = 0.7M⊙ and Tteff = 104K the principal pulsation mode is nearly second overtone for Mbol = –5 mag and is nearly fourth overtone for Mbol = –4 mag. For stars brighter than Mbol = –5 mag the blue edge turns blueward so that the models with Teff as high as 3 · 104K are pulsationally unstable. The sequences of the hydrodynamic models characterized by constant luminosity Mbol < – 5 mag) reveal the decrease of the light amplitude with increasing Teff, whereas the amplitude of the radial velocities of the outer layers is almost independent of Teff. For example, for stars with Teff > 2·104K the light amplitude is less than 0.01 mag, whereas the radial velocity amplitude is in the range from 20 to 50 km/s. The pulsation instability of these stars is driven mainly due to the γ-mechanism. Fourier analysis of the hydrodynamic solution shows that the pulsation motions of the hot helium stars can be represented as a superposition of the running waves (in contrast to Classical cepheids where the pulsation motions are described in the terms of superposition of standing waves). The pulsation constant gradually decreases with increasing Teff, down to Q ≈ 0.012 day at Teff ≈ 3 · 104K.
A Photometric and Spectrographic Study of SX Phœnicis
Authors: Kim Chulhee , McNamara D.H. , Feltz Kent A. , Christensen C.G.
Published: June 2019

New simultaneous photometric (uvbyβ) and spectrographic observations of SX Phe are described. Analysis of the light variation frequency spectrum is performed and the oscillation modes are investigated. After separating the light curves and radial velocity curve, atmospheric and physical parameters corresponding to each different oscillation mode were determined. Intrinsic (b – y), m1, and c1 values used in conjunction with a model-atmosphere grid yield a mean effective temperature < Teff > = 7590K, a mean surface gravity, < logg > = 4.02, and [Fe/H]= -0.47 for the first period. The pulsation theory and stellar model sequences yield bolometric magnitude of mass of 1.4 M⊙ and age of 2.0 Gyrs. It was found that these atmospheric parameters are almost independent upon different oscillation mode. The radial-velocity data indicates a mean radial velocity of -37km/s and a total velocity amplitude range of 38km/s.
New Radial Velocities and the Barnes-Evans Method
Authors: Hindsley Robert , Bell R.A.
Published: June 2019

New radial velocities by Butler are used to recalculate the absolute magnitudes of Eta Aquilae and X Cygni using the Barnes-Evans method. The new velocities have little effect on the result for Eta Aquilae, but the absolute magnitude of X Cygni is found to be 0.40 mag fainter than that obtained earlier.
Moving Through The Instability Strip
Authors: Belserene Emilia Pisani
Published: June 2019

The purpose: To look at period changes in pulsating variables from the point of view of stellar evolution. Is there evidence of systematic, slow changes that might be caused by the changes in mean density during passage across the Instability Strip?

The data: O – C diagrams for 67 RR Lyrae stars and Cepheids by student assistants at the Maria Mitchell Observatory, and for 88 northern Cepheids by L. Szabados

The method: Least-squares lines and parabolae (unless the O – C diagram shows that the period has changed in both directions). The rate of change of period comes from the coefficient of the square term in the parabola. The principal feature of these analyses is that the rate is taken to be non-zero only if the parabola is significantly better than the linear fit, at the 2-sigma level.
Observed Interstellar Extinction in the Ultraviolet
Authors: Stecher T. P.
Published: June 2019

An Observational Program to measure stellar energy distributions - in the ultraviolet between 3000 Å and 1200 Å has recently been completed. The instrumentation used was similar to that reported in reference 1. A necessary preliminary for discussion of this material is some knowledge of the extinction due to interstellar absorption. The trend of this extinction was first reported in 1964. (See ref. 2.) Additional observational material has since been obtained and is presented herein.

Five pairs of stars with similar Morgan-Keenan (MK) spectral classifications have been observed that are suitable for obtaining extinction: ζ Per and ρ Leo; ξ Per and ζ Pup; o Per and β Can Maj; σ Sco and π SCO; and δ Sco and τ SCO. The telemetry records were hand reduced by the author, each star was multiplied by the absolute calibration curve for the appropriate instrument, and the resulting flux curve was placed on a magnitude scale.
Graphite and Interstellar Extinction
Authors: Stecher T. P. , Donn Bertram
Published: June 2019

The Theory That Graphite Particles could be responsible for interstellar extinction is presented in references 1 and 2, and this paper will present evidence that further supports this contention. The complex dielectric constant (m = n(l — ik) for graphite has been measured as a function of energy by the authors of reference 3, and the optical constants as function of wavelength λ have been obtained from this measurement. A large variation occurs in both n and k at wavelengths below 3000 Å.

The results reported in the preceding paper indicated the desirability of performing Mie scattering calculations on graphite. The measured values of the complex index of refraction corresponding to 17 wavelengths were used in the calculation for spherical particles. The IBM 7094 computer program for Mie scattering follows that of van de Hulst. (See ref. 4.) The Oort-van de Hulst size distribution (ref. 5), which may not be applicable to the type of particle discussed herein, has been used to obtain an integrated cross section for extinction.
A Prototype 11 Metre Modern Michelson Stellar Interferometer
Authors: Davis John
Published: June 2019

The Astronomy Department of the University of Sydney is currently exploring the feasibility of building a Micheson stellar interferometer using modern techniques and detectors to surmount the atmospheric and stability problems that limited the development of the original Michelson interferometers. The main part of this programme is the design and construction of an 11 m fixed baseline prototype instrument to establish whether fringe visibility can be measured with an accuracy better than ±2% over a range of atmospheric seeing conditions and instrumental parameters. The design of the prototype instrument, its status and prospects are discussed.
Speckle Interferometry in the Near Infrared
Authors: Wade R. , Selby M.J.
Published: June 2019

The use of Stellar Speckle Interferometry has been extended to the near infrared using a single element detector. Preliminary measurements indicate that diffraction limited information is available in this wavelength region.
A Direct Measurement of the Collisional Population and Depopulation Rates for the N = 2 State of Atomic Hydrogen
Authors: Burgess D.D. , Kolbe G. , Ward J.M.
Published: June 2019

A technique is described in which a plasma is prepared using a tunable laser such that the population of only a single atomic bound state differs significantly from its equilibrium value. Subsequent observation of the relaxation of this single state in the absence of laser irradiation and with all other levels close to their equilibrium populations then yields unambiguous values for the collisional depopulation and re-population rates for the level, free from uncertainties present e.g. in laser-induced fluorescence experiments.

Results will be presented for the n = 2 state of hydrogen, but the technique is applicable to many first excited states in plasmas which need not be in either LTE or pure coronal equilibrium.
Large Scale Variations in Solar Coronal Density and Magnetic Fields
Authors: McQueen R. M.
Published: June 2019

Observations of the solar equatorial electron scattered coronal radiance made during the Skylab mission show characteristics which dramatically differ with time. The results may be interpreted as indicating a general simplification of the coronal magnetic field, and, in comparison with harmonic analysis of observed solar surface magnetic fields, as indicating a rapid response of outer coronal structures to abrupt changes in the global solar surface field structure.
Hertzsprung's Luminosity-Colour Relation for Visual Binaries
Authors: Finsen W. S. , Wisse P. N. J.
Published: June 2019

The number of visual binaries for which orbits have been computed now exceeds 600, but this laboriously accumulated wealth of data remains relatively sterile owing to the paucity of reliable parallaxes. Hertzsprung (1964) had this in mind when he revived the idea he first voiced in 1911 and proposed a new luminosity parameter defined as the absolute magnitude of a star reduced to unit mass without changing its density or surface brightness. The great advantage of this parameter is the fact that it is readily derived from the period and semi-major axis of a visual binary without recourse to the parallax. It therefore permits immediate use of most of the computed orbits for the construction of a luminosity-colour diagram analogous to the classical H-R diagram but entirely free of the scatter resulting from errors in the parallaxes.
Hydrodynamic Modelling of Accretion Flows
Authors: Murray J. R. , Truss M. R. , Foulkes S. B. , Haswell C. A. , Manson K. J.
Published: June 2019

In the proceedings of this, and of several recent close binary conferences, there have been several contributions describing smoothed particle hydrodynamics simulations of accretion disks. It is opposite therefore to review the numerical scheme itself with emphasis on its advantages for disk modelling, and the methods used for modelling viscous processes.
X-Ray Spectroscopy of the High-Mass X-Ray Binary 4U 1700-37
Authors: van der Meer A. , Kaper L. , Di Salvo T. , Méndez M. , van der Klis M.
Published: June 2019

We present the first results of a monitoring campaign of the high-mass X-ray binary system 4U 1700-37/HD 153919, carried out with XMM-Newton.

We have observed the high-mass X-ray binary (HMXB) 4U 1700-37 with XMM-Newton at four orbital phases in February 2001. 4U 1700-37 is powered by the dense stellar wind of the O supergiant HD 153919. Numerous X-ray flares are observed with a typical duration, of the order of half an hour. We focus on three intervals in which the data are not affected by pile up: the eclipse, the eclipse egress and a low-flux part around orbital phase ϕ ~ 0.28.
Measuring the Masses of Compact Objects in Low-Mass X-Ray Binaries
Authors: Gelino Dawn M.
Published: June 2019

Low-mass X-ray binaries (LMXBs) contain compact, black hole (BH) or neutron star (NS) primaries, and cool, low-mass secondary stars. We measure the orbital inclination of the system in quiescence by modeling infrared (IR) ellipsoidal variations from the secondary star in order to determine the compact object mass. I present our results for a few LMXBs, including the first BH that appears to conclusively fall in the 3-5 M⊙ range.
Cygnus X-3: Orbital Modulation in X-Rays and Radio
Authors: Hjalmarsdotter L. , Hakala P. J. , Vilhu O. , Hannikainen D. C. , McCollough M. , Pooley G. G.
Published: June 2019

The orbital modulation of the X-ray and radio emission of Cyg X-3 was studied using monitoring data from CGRO/BATSE, RXTE/ASM, GBI and the Ryle telescope as well as recent INTEGRAL observations. The depth of the X-ray modulation was found to be the same at X-ray energies ranging from 1.5 up to at least 20 keV, but the shape of the lightcurves changes gradually with energy. No modulation was found in radio.
Long-Term Photometric and Spectroscopic Behaviour of Symbiotic System AG Dra
Authors: Gális R. , Hric L. , Petrík K.
Published: June 2019

The general behaviour of AG DRA was studied in the context of the long-term photometry and radial velocity analysis.

AG DRA is a symbiotic binary with quiescent and active stages; the latter may be explainable by increased thermonuclear burning of a white dwarf accreting from the wind of the cool component.

In our previous studies a second period in addition to the orbital period of 549.7 days has been found for AG DRA. Such a period of about 350 days was indicated in our study using photometry (Friedjung et al. 1998, Petrík et al. 1998)as well as radial velocities (Gális et al. 1999 Friedjung et al. 2003).
Interstellar Grain Flow through the Solar Wind Cavity around 1992
Authors: Gustafson Bo Å. S. , Lederer Susan M.
Published: June 2019

The local cloud in which the Sun is embedded participates in a general flow from the direction of the Sco-Cen association (Weaver, 1979) while the Sun is moving in the direction of Hercules. The relative motion is well determined by the neutral gas flow (Cox and Reynolds, 1987). A prominent cone of gravitationally focused neutral helium indicates the downwind direction to within ±3°. The average flow speed outside the solar system, 26 km/s, is determined to within ±1 km/s. Measurements from the Ulysses spacecraft (Witte et al., 1993) confirmed this flow. Since interstellar matter contains dust as well as gas, efforts have been made to detect the dust flow through the solar system. However, until recently these efforts have been unsuccessful and modeling of the flow has been controversial.
Martian Self-Sustaining Dust Torus
Authors: Sasaki Sho
Published: June 2019

Recent theoretical studies show that orbits of circummartian dust particles are controlled by solar radiation pressure and the Martian oblateness. Smaller dust particles (< 22μm) with enhanced orbital eccentricity are quickly captured by Mars. We find that the collisions of ring particles with Phobos and Deimos are the most important dust sources. Erosion of Phobos should set the upper limit on the dust production efficiency controlling this self-sustaining mechanism, and then the ring dust abundance.
A Collector for Interplanetary Dust Particles and Space Debris
Authors: Yin-Lin Xu , He-Qi Zhang , Nan Zhang , Min Yu , Ping Xie , Fan C. Y.
Published: June 2019

We are constructing a collector for capturing Interplanetary Dust Particles (IDPs) and space debris on space shuttle. The unit consists of three pieces of thin polyester film, equally spaced 7 cm apart, and an aerogel disk of 3 cm thickness. For each particle captured in the aerogel disk, we determine its direction of impact and its speed, from which we can trace its trajectory. The purpose of the experiment is to study the compositions of IDPs from different origins.
Optical Properties of Dust from Laboratory Scattering Measurements
Authors: Gustafson Bo Å. S.
Published: June 2019

This is a description of the beginning of a systematic investigation into the optical properties of dust structures that are likely to be representative of interplanetary dust. I delineate the development of a physical dust model to parameterize the optically important characteristics of the dust. The result is a system with two refractive indexes in an aggregate structure of varying porosity - a challenging model for most current light scattering theories. Experimental data is needed to investigate the scattering by these structures and to test new theoretical solutions (e.g., Xu 1995) as they develop. I give a brief description of the new microwave analog scattering laboratory that has been developed for this purpose at the Laboratory for Astrophysics of the University of Florida's Astronomy Department. Finally, laboratory data is shown in support of dense aggregate models for interplanetary dust.
Scattering Properties of Dust Particles in Weightlessness
Authors: Worms J. C. , Levasseur-Regourd A.C. , Hadamcik E. , Bourras D.
Published: June 2019

Polarimetric measurements of the light scattered by irregular dust particles are essential to interpret observations of solar system dust in terms of its physical properties. We developed a iight scattering unit to retrieve polarimetric phase curves of dust samples in microgravity conditions. Preliminary results suggest that the values for the maximum polarization are higher under 1 “ g ” than under 0 “ g ” This can be compared to ground-based measurements which exhibit higher values for packed dust than for sifted dust. The unit is operational and is used to help design a related orbital experiment.
Modelling the Temperature of Cometary Particles
Authors: Xing Zhangfan , Hanner Martha S.
Published: June 2019

We use the DDA method to study scattering properties of aggregates. Based on this aggregate model, the temperatures of cometary dust particles will be close to those of the equivalent total volume sphere when the aggregate porosity is ≤ 0.64.
Free Molecular Gas Drag on Fluffy Aggregates
Authors: Nakamura R.
Published: June 2019

Computer simulations of the collisions of gas molecules with fluffy aggregates have been carried out to estimate gas drag forces in the free molecular flow limit. It is found that the gas drag force on fluffy aggregates can be approximated by that on an area-equivalent sphere in a wide range of relative velocities of the aggregate through ambient gas. The deviation from this approximation is weakly dependent on the relative velocity. This result leads to a significant increase of gas drag forces on fluffy aggregates compared to that on a mass-equivalent sphere.
From research-as-practice to exploratory practice-as-research in language teaching and beyond
Authors: Hanks Judith
Published: June 2019

Practitioner research is a flourishing area with a significant body of theoretical and empirical research, but often researchers remain isolated, unaware of impactful work by colleagues in related fields. Exploratory Practice (EP) is one innovative form, uniting creative pedagogy and research methods. The potential contributions have hitherto been neglected. EP's emphasis on puzzling and understanding is a means of demystifying occluded practices which place learners, teachers and researchers as co-investigators at the heart of the research-practice nexus. EP's radical positioning of learners as co-researchers, alongside teachers, teacher educators and others, means crossing boundaries – (re-)negotiating identities, in language learning/teaching/researching – thus raising epistemological challenges for the field. The contribution of this state-of-the-art article is to provide a meta-analysis of these themes and challenges, critically analysing the complexities involved as the paradigms of research, practice and practitioner research shift from research-as-practice towards practice-as-research.
Developments in methods for breeding value and parameter estimation in livestock
Authors: Hill William G. , Meyer Karin
Published: June 2019

In an effective animal breeding programme the objectives are appropriate, the population structure is good, suitable records are collected, and these records are used in an optimal way so that animals likely to have the best offspring are chosen.

Estimates of genetic parameters such as heritabilities and correlations influence the design of the programme: for example, the optimal number of daughters to progeny test per dairy sire or, more fundamentally, whether to adopt performance or progeny testing, whether to record food conversion efficiency or simply growth rate, and whether or not to collect records on some indicator trait such as blood urea nitrogen level. The estimates of parameters also influence the weightings given to different traits and to individuals and relatives' performance in breeding value estimation and selection. Methods for estimating parameters have become much more sophisticated as a result of advances in theory, particularly, restricted maximum likelihood (REML), in computer power, and in development of special computer programs.
Genetic components of potential and actual growth
Authors: Emmans G C
Published: June 2019

1. It is shown how the growth of an animal in non-limiting conditions can be predicted from the values of a small set of animal variables. The functions used are derived from a small set of simple, and reasonable, assumptions.

2. Growth may be limited by intakes of nutrients and energy which are less than those needed. The prediction of growth where such limitation occurs calls for the prediction of the intakes. There may be genetic variation in the abilities of animals to deal with the relevant constraints which are, commonly, feed bulk or hot environments.

3. Breeders need to pay more attention to giving sufficient descriptions of their stocks.
Feeding the young ruminant
Authors: Williams P. E. V. , Frost A. I.
Published: June 2019

Young calves and lambs are weaned early to reduce the amount of milk products consumed and potentially improve the profitability of rearing enterprises. At weaning the pre-ruminant must make a number of adjustments to cope with the change in dietary substrate. The microbial population in the rumen must develop and metabolic changes are required in order for the young ruminant to metabolize the end products of microbial digestion. It is recognized that early weaning poses a stress to the calf but it is generally considered that the calf rapidly adjusts to the change in diet composition. A number of factors indicate that considerable advantage would be gained from delaying the weaning of calves and indeed that the calf is not physiologically capable of adapting to an early-weaning regime. Work has indicated that a diverse anaerobic microbial population can be identified in the developing rumen of the calf. More recent results show that the presence of a faculative anaerobic population, which exists for a considerable period of time, has an adverse effect on the development of a mature anaerobic population. Low rumen pH is a problem in the young calf. The level of rumen pH verges on that which would be described as acidosis in the adult ruminant. The young calf is unable to stabilize rumen pH and increasing the level of dry food intake at weaning may further depress rumen pH if the salivary buffering capacity of the calf is not adequately developed. Results indicate that the ability to utilize volatile fatty acids is not fully developed in the young calf and that early weaning can result in high levels of VFAs in the circulation.

The composition of the dry diet has a major effect on the response of the calf to weaning. Choice of the ingredients can affect the buffering capacity of the rumen and the physiological development of the digestive tract. Strategies to limit the nutrient intake from dry food to levels commensurate with the developing physiology of the calf may result in a more uniform transition to full ruminant status with consequent benefits in growth rate and health.
Development of the small intestine and pancreas of the pig weaned at 21 days of age and the effects of exogenous glucocorticoids before weaning
Authors: Needham D. , Fletcher J. M.
Published: June 2019

Although natural weaning in the pig occurs at 6 to 8 weeks of age it is common commercial practice to wean at 3 to 4 weeks. This abrupt and early weaning is often associated with a more or less prolonged check in growth, frequent occurrence of gastrointestinal disease and a significant mortality. The transition from a milk diet to a solid diet in the post-weaning period necessitates complex digestive and metabolic adaptations in the piglet. Experiments in small animals have shown that some of the changes brought about by weaning are at least partially controlled by hormones from the adrenal cortex (Henning, 1981).

We have investigated the changes that occur in the mucosa of the small intestine and in the pancreas of pigs weaned at 21 days of age. In addition we have investigated the effects of an orally administered synthetic glucocorticoid (dexamethasone; DEX) given before weaning, on the development of the intestine and pancreas.

Two pigs from each of six litters were killed at 18 days of age, half of the remaining pigs were given DEX (0.4mg/kg ) suspended in agar (0.5%). This dose was divided into four equal aliquots and given by stomach tube on days 19 and 20. Controls received an equivalent volume of agar. Pigs were weaned at 21 days, two control and two DEX treated pigs were killed on the day of weaning and at 28, 35 and 42 days. After weaning pigs were allowed ad libitum access to a commercial starter diet.
6.2 Selenium Deficiency in Farm Livestock in Britain
Authors: Anderson P. H.
Published: June 2019

Until the early 1970s, selenium (Se) status in livestock had been assessed by the chemical measurement of the element Se. For example, the Watkinson (1966) method requires solubilizing Se by inorganic acids, forming a chemical complex, solvent extraction and fluorimetric detection. By contrast, erythrocyte glutathione peroxidase (GSH-Px), a Se-containing enzyme, is readily assayed in blood haemolysates on automated enzyme analyzers. This enzyme activity is usually related to dietary Se intake during preceding months. For both cattle and sheep, a correlation between erythrocyte GSH-Px and whole blood Se was shown (Anderson, Berrett and Patterson, 1978).
6.3 The Development and Effects of Selenium Deficiency
Authors: Arthur J. R. , Boyne R.
Published: June 2019

Deficiencies of selenium (Se) and vitamin E can result in myopathies in cattle and sheep but the mechanics have not been clearly described. Both Se, as a component of the enzyme glutathione peroxidase, and vitamin E as a radicle scavenger, are involved in the protection of cells against the toxic effects of oxygen. In young calves, Se/vitamin E deficiency can result in the death of the animals due to a focal myopathy occurring in heart muscle; focal lesions are also found in skeletal muscle. In older calves, a more diffuse myopathy is usually confined to skeletal muscle and usually occurs when cattle are turned out from winter housing to spring pasture. However, low Se/vitamin E status will not invariably result in clinical symptoms of myopathy and other factors may be involved. This report describes some of the biochemical changes which can occur during the onset of clinical myopathy in Se/vitamin E-deficient cattle.
8.2 Interactions Between Protein and Energy Metabolism in Forage-Fed Calves
Authors: Gill M. , Beever D. E. , Thomson D. J.
Published: June 2019

Glucose and acetate are two of the most important metabolites which supply energy to ruminant tissues. Minimal quantities of glucose are absorbed from the alimentary tract and thus glucose requirements must be met through synthesis from gluconeogenic precursors. One such precursor is protein and, in the two experiments to be reported, the effect of varying protein supply on both glucose and acetate metabolism was studied. In experiment 1, protein supply was varied by the addition of two levels of fishmeal to a grass silage diet while in experiment 2, two diets (perennial ryegrass and white clover) known to supply widely different amounts of absorbed protein were compared.
9.4 Voluntary Intake in Ruminants Affected by Silage Extracts and Amines in Particular
Authors: Buchanan-Smith J. G.
Published: June 2019

Gamma amino butyric acid (GABA) is a food intake depressant (Morley, 1980) and is quantitatively a significant nitrogenous constituent in silage (Oshima and McDonald, 1978). When maize silage extracts were infused into the rumen of sheep, it was shown that short-term feed intake could be depressed but this effect was attributed to high rumen osmolality (Phillip, Buchanan-Smith and Grovum, 1981) The purpose of the present experiments was to determine whether GABA and low dry matter lucerne silage extracts could depress food intake in sheep.
Nutritional needs of sheep in the hills and uplands
Authors: Milne J. A.
Published: June 2019

Current knowledge of the potential nutrient supply that can be derived from indigenous and sown pasture is described and related to classically derived nutrient requirements. From this information, nutrient deficits can be identified for specific times in the ewe's cycle of production. Whilst nutrient deficits have been clearly identified in late pregnancy and early lactation, responses to nutrients and nutrient supply from autumn pasture have not yet been adequately described for the ewe over the mating period.

Nutrient deficits can be met by a combination of tissue catabolism and the provision of supplementary feeding. The dearth of knowledge of the factors influencing tissue catabolism and of the effects of supplementary feeding on herbage intake limits quantification of the amount and type of supplementary feeding to offer.

The principles concerning supplementary feeding in late pregnancy in some circumstances still require elucidation because of the interactions between mid- and late-pregnancy nutrition and this will be illustrated with reference to sheep grazing a predominantly heather hill. However, the principles governing supplementary feeding in early lactation are relatively well understood in relation to sown pastures below 4 cm in sward surface height and these are outlined. Information on the relative importance of milk and herbage in the diet of the lamb to weaning is discussed. The dependence of one part of the annual cycle on the nutrition in other parts of the cycle is stressed.
The effect of head-space pressure on gas production profiles
Authors: Lowman R. S. , Brooks A. E. , Theodorou M. K. , Dhanoa M. S. , Cuddeford D.
Published: June 2019

In vitro gas production techniques are becoming increasingly popular as tools to investigate the food quality for ruminant and monogastric herbivores. They are attractive due to their ability to measure the kinetics of digestion associated with the gut microbial fermentation of foodstuffs. It is therefore important to know and understand what factors affect the volume of gas produced, particularly as they relate to repeatability within or between laboratories. In studies involving gas pressure and volume measurement, the chemical composition of the culture medium, the nature of the microbial population and the type and amount of substrate available for fermentation all have a significant influence on gas accumulation. In this study, the manual pressure transducer technique (PTT) of Theodorou et al. (1994) was used to investigate the effect of head-space pressure on the resultant gas production profiles.
Welfare in livestock markets
Authors: Pack B. S.
Published: June 2019

Livestock markets are under constant pressure from a variety of sources as regards animal welfare. Their openness to the public helps to ensure that only acceptable welfare practices are operated. These practices are set out in the Welfare of Animals at Markets Order 1990, supplemented by a Code of Practice for the Welfare of Animals in Livestock Markets. These ‘rules’ represent minimum standards and there is a continuing pressure to further improve welfare in auction marts. This comes from the market operators themselves, from consumers via the large retail outlets, and from a small but vociferous minority who oppose the production of livestock for food. All concerned with any part of the food chain have a rôle to play in ensuring a continuing improvement in animal welfare.
Current developments in pig welfare
Authors: Edwards S.A.
Published: June 2019

Public concern about the welfare of farm animals has resulted in an increasing body of legislation regulating livestock production systems. In 2003, the UK implemented two new EU Directives on Pig Welfare (Directives 2001/93/EC and 2001/99/EC), and issued revised Welfare Codes for Pigs. New Council of Europe Recommendations are also at the consultation stage. The welfare issues highlighted for current consideration within the pig sector include space allowance and floor type, environmental enrichment, tail docking, weaning age and the use of the farrowing crate. With present scientific and practical knowledge, not all of these issues have a simple resolution. From an industry perspective, the major welfare issue is the level of endemic disease and, in particular, the dramatic influence of PMWS. There are also concerns regarding potential conflicts between the different policy objectives of animal welfare, environmental protection, food safety, staff health and safety, and financial sustainability that will need to be resolved.
An investigation into whether a significant correlation exists between feed pH and faecal pH of horses fed a variety of different diets
Authors: Wheeler R
Published: June 2019

Previous work has shown that an increase in readily fermentable carbohydrates (CHO) in the diet of pigs is reflected by a decrease in faecal pH (Canh et al., 1998). It is well documented that a similar increase in CHO in the diet of equids is reflected by a decrease in caecal pH (McLean et al., 2000). Little work has been undertaken to determine if such a relationship exists in equids or indeed if there is a correlation between dietary pH and faecal pH.

The feed pH and faecal pH of six groups, each of 8 horses, receiving a variety of diets were examined. The dietary groups covered a wide range of feeds from purely forage based to predominantly concentrate based. Diet 1 consisted of 100% Hay (Hy), diet 2 of 100% grass (Gr), diet 3 of a 70:30 mix of Haylage (Hg) and grass (Gr): stud nuts, diet 4 of a 50:50 mix of haylage and competition mix, diet 5 a 30:70 mix of haylage to race mix and diet 6 a 60:40 mix of haylage, alfalfa and sugar beet pulp: rolled oats.
Fresh water inflows to the Firth of Clyde
Authors: Poodle T.
Published: June 2019

Synopsis

Rainfall and river flow data have been used to calculate the fresh water input to the Firth of Clyde at key locations. The importance of seasonal variation and the recurrence of period of low flow is illustrated. Long term flow frequency is also analysed and related to recent events.