bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent Results on Binary Cepheids
Authors: Evans Nancy Remage 
Published: June 2019

AbstractIUE observations of hot companions of Cepheids have been used to determine the temperatures of the companions. For companions on the ZAMS, the temperatures can be used to determine the luminosity of the Cepheids from the inferred absolute magnitude of the companion. The accuracy of this method is comparable to the accuracy of calibration using Cepheids in clusters. An over-tone pulsator (SU Cas) has been identified by this technique. The luminosity of the double mode pulsator Y Car agrees with that from the PLC, confirming that is a normal Population I Cepheid. The variation of the width of the instability strip (as a function of luminosity) in the HR diagram is confirmed, and overtone and double mode pulsators are shown to be near the blue edge of the instability strip. Comparison between variables and nonvariables in the HR diagram (from IUE and cluster studies) shows very little overlap. The shape of the observed instability region may be determined both by the boundary between the variables and nonvariables and also the location of the tips of the blue loops of evolutionary tracks. Finally, eight Cepheids with hot companions which are evolved beyond the ZAMS have been studied. Half the systems are matched well by evolutionary tracks with little or no core convective overshoot near the main sequence. At least two and possibly four systems, however, cannot be matched by current isochrones.
A Two-Dimensional White-Light Amplitude Interferometer
Authors: Breckinridge James B. 
Published: June 2019

AbstractA review of the applications of a point-symmetric, 180-degree, rotational shearing interferometer is given. Material includes, photographs of the Michelson stellar interferometer fringes from α Lyr, measures of amplitude of phase excursions in the atmosphere, and a measure of the order of interference in speckle patterns. New material includes unpublished double star speckle patterns to illustrate the isoplanatic patch, a measure of the time fluctuations of the earths' atmosphere, and measurements of the properties of a 256 channel linear reticon.
Spatially Resolved Observations of Solar Active Regions in Soft X-Rays and Centimetric Wavelengths
Authors: Pallavicini R. , Tofani G. , Vaiana G.S. 
Published: June 2019

Soft X-ray images of solar active regions obtained by the S-054 experiment on Skylab have been compared with simultaneous interferometric observations at 2.8 cm. The radio data consist of one-dimensional scans with a spatial resolution of 16 arcseconds in the East-West direction. The resolution, although lower than the X-ray telescope resolution, is high enough for a detailed comparison.We have found that there is a general correspondence in position and size between X-ray and radio sources, but relevant differences are also present. In particular, very bright, narrow components at 2.8 cm appear coaligned with regions of very weak X-ray emission. These strong radio components appear to be localized directly above sunspot umbrae.Models of active regions are investigated both for the atmosphere directly over the sunspot umbra and for regions above the adjacent plage. The presence of the magnetic field is taken into account and its effects on the energy dissipation and on propagation of radio waves are discussed.
Theoretical Methods of Treating Line Formation Problems in Steady-State Extended Atmospheres
Authors: Rybicki George B. 
Published: June 2019

AbstractTheoretical methods applicable to the study of line formation in steady-state extended atmospheres are reviewed. The formal solution of the transfer equation is considered, as well as numerical and analytical methods of determining the source function. Topics discussed include: the local frequency transformation, geometrical effects, and the case of large velocity gradients. A new plane-parallel approximation for spherically symmetric moving atmospheres is given that takes account of transverse velocity gradients.
Resonant Scattering and Recombination in CAL 87
Authors: Greiner J. , Iyudin A. , Jimenez-Garate M. , Burwitz V. , Schwarz R. , DiStefano R. , Schulz N. 
Published: June 2019

AbstractThe eclipsing supersoft X-ray binary CAL 87 has been observed with Chandra on August 13/14, 2001 for nearly 100 ksec, covering two full orbital cycles and three eclipses. The shape of the eclipse light curve derived from the zeroth-order photons indicates that the size of the X-ray emission region is about 1.5 R⊙. The ACIS/LETG spectrum is completely dominated by emission lines without any noticeable continuum. The brightest emission lines are significantly redshifted and double-peaked, suggestive of emanating in a 2000 km/s wind. We model the X-ray spectrum by a mixture of recombination and resonant scattering. This allows us to deduce the temperature and luminosity of the ionizing source to be kT ~ 50 — 100 eV and Lx ~ 5 x 1037 erg/s.
Multiwavelength Variability in the Symbiotic Nova V1016 CYG
Authors: Parimucha Š. , Vańko M. 
Published: June 2019

Analysis of the optical and infrared photometry together with UV spectroscopy led to discovery of the 15-years periodicity in the symbiotic system V1016 Cyg. This period could be interpreted as a orbital period in the binary system consisting of the Mira variable and the hot white dwarf.We have analyzed long-term optical photographic and UBV photoelectric photometry of V1016 Cyg. Collected observations cover pre- and post-outburst stages of the system. The light, curve suggests four stages of activity: the pre-out burst flare in 1949, the main nova-like outburst in 1904, and two post-outbursts, decreasing-amplitude flares in 1980 and 1994, respectively. Activity episodes affecting the system repeat with an interval of ~ 15 years. The ephemeris for the activity maxima is (see Parimucha et al., 2000).
Optical Search for High Meteors in Hyperbolic Orbits
Authors: Woodworth S.C. , Hawkes R.L. 
Published: June 2019

AbstractDual-station image intensified television studies have indicated very few meteors at heights greater than 120 km, and few statistically significant hyperbolic orbits. However, the optimum intersection height for these studies was about 95 km, and the relatively small fields of view resulted in a bias against high (and therefore fast) meteors. We have developed height sensitivity correction factors, and found that short baseline television studies resulted in relatively little bias against high meteors, and the absence of meteors above 120 km appears to be real. We report preliminary results from a three-station, image-intensified video meteor detection system sensitive to apparent magnitude about +9.5 with optimum intersection heights 115-125 km. We have detected neither particularly high meteors nor meteors in clearly hyperbolic orbits. We conclude that the proportion of true hyperbolic meteors in the mass range 10-4 to 10-6 kg is less than a few percent, and that optical meteors corresponding to meteoroids in this mass range do not ablate at heights above approximately 120 km. We suggest several ways to reconcile these results with southern hemisphere radar studies.
Space Debris
Authors: Kessler D.J. , Anz-Meador P.D. , Matney M.J. 
Published: June 2019

AbstractMan-made, artificial space debris is of interest to the study of interplanetary dust for two reasons: (1) In many regions of Earth orbital space, the space debris flux is larger than the natural meteoroid flux, complicating the study of interplanetary dust, and (2) models and experiments developed to understand space debris may have application to the study of interplanetary dust. The purpose of this paper is to summarize the space debris environment as it is understood today by characterizing the models used to predict the space debris environment and describing the measurements to test the model predictions.Within the last 5 years, the space debris environment has been measured by a number of experiments. These experiments have revealed significant sources of debris in addition to the assumed major source of satellite explosions. Understanding these sources has required the development of more complex models and additional insight into the design and operation of spacecraft. Increased awareness of space debris issues at an international level has led to measures that have reduced the rate of growth in the environment. However, the number of new debris sources discovered seems to be proportional to the number of new measurements of the environment.
Accuracy of a Velocity/Trajectory Sensor for Charged Dust Particles
Authors: Auer Siegfried 
Published: June 2019

AbstractA VELOCITY/TRAJECTORY cosmic dust sensor of the CHARGE-SENSING type was tested at the Heidelberg dust accelerator facility, using micronsized particles. The full-scale (0.4m x 0.4m x 0.3m) model displayed capabilities for providing accuracies to 0.1% in speed and 0.1° in angle relative to the spacecraft at high signal-to-noise (SNR) ratios. The particle's trajectory within the sensor can be located with an accuracy of 0.3mm.
A Comprehensive Study of Major, Minor, and Light Element Abundances in Over 100 Interplanetary Dust Particles
Authors: Thomas Kathie L. , Keller Lindsay P. , McKay David S. 
Published: June 2019

AbstractOver 100 individual and cluster interplanetary dust particles (IDPs) have been analyzed for bulk abundances of 15 elements (C, O, Na, Mg, Al, Si, P, S, K, Ca, Ti, Cr, Mn, Fe, Ni). In general, IDPs have chondritic major element abundances, within a factor of 2 of the CI chondrites, and have carbon contents which average ~2-3 times higher than that of the most primitive, carbon-rich, carbonaceous meteorites (CI). The C-rich material is largely amorphous and is distributed throughout the particle as a matrix surrounding individual grains. The carbonaceous material has either smooth or vesicular texture; the latter texture suggests that volatiles could have been lost by particle heating which occurs during entry through the Earth's atmosphere.
The Abundance Pattern of Elements Having Low Nebular Condensation Temperatures in Interplanetary Dust Particles: Evidence for a New Chemical Type of Chondritic Material
Authors: Flynn G. J. , Bajt S. , Sutton S. R. , Zolensky M. E. , Thomas K. L. , Keller L. P 
Published: June 2019

AbstractThe abundances of Ni, Fe, Cr, Mn, P, Cu, K, Na, Ga, Ge, Se, Zn, S, Br, and C were measured in interplanetary dust particles (IDPs) collected from the Earth's stratosphere. All elements with nebular condensation temperatures lower than Mn, except S, were enriched relative to the most volatile-rich type of meteorite while the refractory elements Cr and Ni were present at chondritic abundances. This element abundance pattern is consistent with nebular condensation, suggesting the IDPs condensed at either a different location or time in the evolving solar nebula than do the meteorites. The enrichments of the major elements C, Na, P, and K exclude the possibility that the volatile enrichment in IDPs results from a minor amount of contamination.
Infrared Spectroscopic Observations of Neutral Helium During the 1994 Eclipse
Authors: Mann I. , Kuhn J. R. , Penn M. J. 
Published: June 2019

AbstractWe present the detection of a neutral helium line in observations of the solar corona obtained during the 1994 eclipse, and show that a coronal excitation process is unlikely to cause such a significant Hel emission that extends out to a distance of 3 solar radii (R⊙) from the center of the sun. Besides the scattered light of a solar prominence, as well as components of geocoronal helium, the observed emission line may come from the neutral helium components in the interplanetary medium. Recombination of ions on interplanetary dust particles may play a role for the formation of the neutral helium.
Applicability of A1-term Method to the Scattering by Irregularly Shaped Interplanetary Dust Grains
Authors: Okamoto Hajime 
Published: June 2019

AbstractThe first scattering coefficient (a1-term) in Mie theory is introduced to determine the dipole polarizability used in the discrete dipole approximation (DDA) to calculate the scattering properties of the cluster of spheres in order to improve our understanding of interplanetary dust particles. In this method, each sphere in a cluster is replaced by a single dipole. The accuracy of this method is tested for a few spheres in contact. It is confirmed that the a1-term method is superior to other types of DDA and is particularly suitable for the case when the particles are placed randomly. By using this method, it becomes possible to treat large cluster of spheres, i.e., a size parameter of the target X(≡ 2πreq/λ) ∽ 50, where req is a volume equivalent radius of the target, and λ is the wavelength of incident wave.
Voluntary food intake in the young pig
Authors: Fowler V. R. , Gill B. P. 
Published: June 2019

AbstractDuring the 1st week of life the energy contained in the body of the average piglet increases by a factor between four and five. To achieve this increase the piglet must ingest metabolizable energy (ME) at a rate which is about four times its maintenance requirement. Well over half the ME supplied in the milk of the sow is in the form of emulsified fat. Whilst the piglet is being suckled, its intake is controlled by litter size, availability of teats and productiveness of the mammary gland. At 3 weeks of age the normal piglet requires about 7.8 MJ digestible energy to sustain a live growth rate of 280 g/day. At this stage the growth comprises about 40 g protein and about 68 g fat. This means that the required intake for a newly weaned piglet on a typical starter diet should be about 475 g/day. In practice such intakes are rarely achieved for several days, therefore weaning causes severe disruption of intake and of the growth curve and there are other factors involved including social disturbance and stress. Further problems are caused by the provision of diets which are unsuited to the physiology of the piglet's immature digestive tract. The sudden loss of the IgA component and indeed other protective factors contained in the dam's milk can be extremely serious, and the reduction in food intake is effectively a defence strategy by the piglet to cope with its new circumstances and try to maintain physiological homoeostasis. In some circumstances the use of antibacterial agents, organic acids or probiotics may be beneficial, but the approach is less reliable than careful formulation of the diet to avoid provocative ingredients such as soya-bean and rapeseed meal.
Integration of transgenes in breeding programs
Authors: Smith Charles 
Published: June 2019

ABSTRACTConventional animal breeding is in a healthy state, with good rates of genetic change possible, and economic efficiency being continually improved in the different livestock species. New reproductive techniques offer faster rates of change, as with the use of embryo transfer in sheep and cattle breeding. It is now possible to introduce foreign DNA, transgenes, into the germ line of farm animals and this offers new opportunities in the genetic improvement of economic merit. The transgenes should be directed at traits of high economic value, and be made in elite breeding stocks to benefit from past genetic improvements. Much still needs to be learned about engineering transgenes and about the basic biochemical-physiological processes they are designed to affect. However many transgenes will be produced over the next decade, and some may be useful in animal improvement. Founder transgene individuals are unique for incorporation site, copy number and expression, and will require screening, multiplication, testing and evaluation, in both hemizygous (TO) and homozygous (TT) form, for all economic traits. For a transgene with a large useful net effect on economic merit, the most rapid genetic response will come from fixing it in the elite breeding stock. An effect of 5-10 percent in economic merit will be needed to offset the normal genetic improvement displaced. Current experience with transgenes is of very large effects on the target trait, but with deleterious effects on fitness and economic merit. Control of the level, tissue and time of expression are crucial to the practical use of transgenes. With uncertainty in the results of a transgenic program, conventional programs will have to be maintained, so extra investment will be required. Patent rights may bring extra benefits to breeders, but there are also risks if the stock prove defective. Breeding strategies and organization may also change. Despite initial problems and uncertainties, the power of the transgenic methods is so great that the development of transgenic stocks is likely to become a very important tool in genetic improvement of livestock in the future.
Feeding and milk fat production
Authors: Sutton J. D. 
Published: June 2019

Decreasing the proportion of long forage in mixed diets from 400 to 100 g/kg at constant digestible energy intakes reduces milk fat content by approximately 5 g/kg for every 100 g/kg decrease in hay. This response varies widely and a safe minimum diet composition to maintain approximately 40 g fat/kg milk from Friesian cows in mid-lactation is approximately 450 g long forage/kg or 220 g acid-detergent fibre/kg dry matter. This, however, would reduce milk yields. With barley-based concentrates, milk yield increases as the proportion of hay in the diet is reduced, with the result that the reduction in the yield of fat is less than the fall in its concentration. Milk fat content is higher when ground maize, which is a slowly fermented starch source, or fodder beet or fibrous by-products replace rapidly fermented starch sources such as barley in low-roughage diets. Milk yield, however, is lower. Supplementary fats and oils generally increase milk yield but their effects on milk fat content and yield vary widely.Increasing the intake of high-concentrate diets of fixed composition increases the yield of milk but reduces its fat content. Increasing the number of meals per 24 h reduces this milk fat depression without affecting milk yield. Thus, advice on milk fat production must take account of the level of intake, the pattern of feeding and the diet composition.In most situations, the avoidance of low milk fat content requires control of rumen fermentation to prevent high proportions of propionic acid. However, with frequent feeding during the 24 h, high propionic acid in the rumen has less effect on milk fat. It appears that high plasma insulin concentration is the main factor reducing milk fat production.The release of insulin is stimulated by the peaks of propionate, which are produced after large meals of concentrates but not by the steady supply of propionate associated with frequent feeding.Available knowledge can permit wide variation in milk fat production by dietary manipulation with reasonable accuracy but the future aim should be for more direct intervention at metabolic control points.
6.16 Some Advances in Clinical Biochemistry Relating to Trace Metals
Authors: McMurray C. H. , Blanchflower W. J. , McParland P. J. , O'Neill D. G. , Rice D. A. 
Published: June 2019

The clinical signs of copper (Cu) deficiency are largely non-specific and a number of laboratory tests have been used extensively to assist in diagnosis. Among these are whole blood, plasma and serum Cu and caeruloplasmin (McMurray, 1980). However, for any marker to be useful diagnostically, it is necessary to identify any factors which can affect it. Plasma and serum Cu are not equivalent but are related by the equation:Serum Cu (mg/l) = 11.7 + 0.66 plasma Cu (mg/l). The regression was obtained from the means of 24 groups of suckler cows and calves (> 10 animals/group). The equivalent relationship between serum and plasma caeruloplasmin is:Serum caeruloplasmin = 0.0018+ 0.59 plasma caeruloplasmin.Units of caeruloplasmin are absorbance units in the phenylene diamine assay.Thus, the range of normality will depend on the sample being used for the assay. The reduction in serum values is due to the loss of caeruloplasmin during blood clotting.
9.6 Grass Silages Ensiled with Either Formic Acid or a Lactobacillus Preparation and their Digestion by Jersey Cattle
Authors: Rooke J. A. , Brookes I. M. , Armstrong D. G. 
Published: June 2019

The use of silage additives containing lactic acid bacteria and enzymes to promote a rapid homolactic type fermentation has met with some success in the United States but the little evidence available (see Burghardi, Goodrich and Meiske, 1980) suggests that, for grass silages, the value of this type of additive is limited. However, in laboratory silos, inoculation with lactic acid bacteria has been shown to be effective in reducing proteolysis (Carpintero, Henderson and McDonald, 1979).The recent availability in the UK of a commercial product containing a lactic acid bacteria inoculum and the non-toxicity and ease of application of this product prompted this investigation, which describes the assessment of a silage prepared with this type of additive in comparison with a well characterized additive, formic acid.
Bioturbation, microbial activity and sediment properties in an estuarine ecosystem
Authors: Meadows P. S. , Tufail A. 
Published: June 2019

SynopsisMacrobenthic bioturbation and microbial activity can have major ecological effects on present day marine sediments some of which are also seen in the fossil record. The coastal and estuarine sediments in the Clyde Estuary area are described. They contain very high densities of benthic macroorganisms and microorganisms. These organisms have dramatic effects on the physical and chemical properties of sediments, and field and laboratory studies have shown that many geotechnical and geochemical properties of sediments are dictated by them. The effects can be on a microscale of a few millimetres horizontally or vertically (micro-spatial variation), or can have large scale consequences over hundreds of metres (macro-spatial variation).Sediment stability (shear strength and critical erosion velocity), permeability and particle sedimentation are all altered by macro-invertebrate bioturbation or microbial activity, and many chemical properties such as Eh and pH may be influenced in a similar manner.Biological activity may therefore play a major role in modifying sediment geotechnics and early sediment diagenesis. It also has direct relevance to the siting of man-made structures on the sea-bed and to sediment stability and transport in estuaries.In situseeding experiments may lead to biological control and manipulation of these most important field phenomena.
Population dynamics of seabirds in the Firth of Clyde
Authors: Monaghan P. , Zonfrillo B. 
Published: June 2019

SynopsisMarked interspecific differences in recent population trends have been recorded for seabirds breeding in the Firth of Clyde. Auk populations have remained comparatively stable, while considerable reductions have taken place in tern and kittiwake numbers. Shags, cormorants, gannets and great black-backed gulls have all increased, as have fulmars and herring gulls. The striking increases in the latter two species are considered in detail. To some extent, these population changes can be related to differences in the feeding ecology of the various seabirds; in particular the variation in the number of breeding terns is related to variation in food availability.