bluuebunny/crossref_metadata_2025_split huggingface dataset:
Naturally Occurring Selection Effects on the Terrestrial Accretion of Interplanetary Dust Particles
Authors: Kortenkamp Stephen J. , Dermott Stanley F. , Liou J.C. 
Published: June 2019

AbstractInterplanetary dust particles deposited in the Earth's atmosphere (IDPs) are an important source of extraterrestrial material. The origin of these particles, whether asteroidal or cometary, is a dispute that can be resolved into two separate questions. What are the fractions of the asteroidal and cometary components of the zodiacal cloud? And what fraction of each component is captured by the Earth? Evidence from the structure of the zodiacal cloud, particularly the dust bands and the Earth's resonant circumsolar ring, indicate that about one third of the cloud is asteroidal while two thirds is cometary. The geometry of capture is such that low eccentricity (e), low inclination (I) particles will be preferentially captured over high e, I particles. Two known abundant sources of low e, I particles are the asteroidal families Themis and Koronis, as witnessed by the associated zodiacal dust bands. We show that capture rates of particles from these two families achieve dominance over every other source. This leads to the result that particles from Themis and Koronis may account for over half of all deposited IDPs and that very few of the IDPs deposited in the Earth's atmosphere are of cometary origin. Furthermore, there are dynamical arguments which suggest that the accretion rate of Themis and Koronis dust particles varies with time. Two perodicities occur, a seasonal variation with a period of six months and a long-term variation with a period near 105 years. The amplitude and period of this long-term variation is supported by measurements of extraterrestrial 3He found in deep-sea sediments.
Sources of 10 micron Interplanetary Dust: The Contribution from the Kuiper Belt
Authors: Flynn G. J. 
Published: June 2019

AbstractTwo major sources are observed to contribute to the Zodiacal Cloud: main-belt asteroids and active comets. However, the discovery of 100 km size objects in trans-Neptunian orbits (Jewitt & Luu 1993) coupled with Pioneer 10 measurements showing an essentially constant flux of 10 μm dust from 4 to 18 AU with indications that dust may be in near-circular orbits (Humes 1980) suggests that collisions in the Kuiper Belt may contribute significantly to the Zodiacal Cloud and to the interplanetary dust collected from the Earth's stratosphere. Kuiper Belt dust collected at Earth could be identified by high densities of solar flare tracks, unusually thick amorphous rims, and high concentrations of spallogenic isotopes.
The Contamination of Iapetus by Phoebe Dust
Authors: Burns J. A. , Hamilton D. P. , Mignard Francois , Soter Steven 
Published: June 2019

AbstractWe examine whether the dark, orbitally-leading hemisphere of Saturn's satellite Iapetus might be coated by debris from low-albedo Phoebe, which orbits retrograde well exterior to Iapetus. Using simplified analytical models along with more complete numerical integrations, we follow the paths of various-sized particles launched gently off Phoebe following collisions with interplanetary and interstellar meteoroids. Micron grains can quickly reach Iapetus since (due to solar radiation) they trace elliptical orbits; larger grains may only hit after their more-circular orbits collapse due to Poynting-Robertson drag; few very large and very small Phoebe grains strike Iapetus. Despite some inconsistencies with observations, we conclude that Phoebe may possibly be the agent that has darkened Iapetus.
Isotopic Anomalies in Interplanetary Dust Particles
Authors: Messenger S. , Walker R. M. 
Published: June 2019

AbstractApproximately 1/3 of interplanetary dust particles (IDPs) and some primitive meteorites have large excesses in D and/or 15N compared to terrestrial materials. Constraints on the nature and origin of the carriers of these isotopic anomalies are reviewed. Special attention is given to a recently discovered extremely D-rich cluster IDP.
Search for the Signature of Interstellar Dust in the COBE Data
Authors: Grogan K. , Dermott S.F , Gustafson B.Å.S. , Jayaraman S. , Xu Y.L. , Hamilton D. 
Published: June 2019

AbstractImpact data from the ULYSSES dust detector at 5 AU from the Sun have been interpreted as a flux of sub-micron interstellar dust particles (Grün et al, 1994) arriving from 252° ecliptic longitude and 2.5° ecliptic latitude. Following the motions of these particles under the influence of solar gravity, radiation pressure and electromagnetic forces, we present results from the modeling of the thermal emission from the resultant particle cloud, and conclude that the chances for the detection of such an interstellar signature in the COBE data are marginal at best.
Clues in Zodiacal Light Observations for a Dust Ring Along the Earth's Orbit
Authors: Renard J.B. , Dumont R , Levasseur-Regourd A.C. , Hadamcik E. 
Published: June 2019

AbstractThe ability of the Earth to trap interplanetary grains into a dust ring lying along the terrestrial orbit was shown by numerical simulations and confirmed by infrared observations (IRAS, COBE). Such a ring could have its signature on the elongation dependence of the zodiacal brightness along the ecliptic, especially near 90° of the Sun. Indeed, the elongation dependence observed at Tenerife by Dumont and Sanchez (1975) shows that the space density of interplanetary dust slightly increases with increasing heliocentric distance, within the 2 or 3 hundredths of AU approaching Earth's orbit.
The Role of Particle Size in Producing the F- Coronal Scattered Brightness
Authors: MacQueen R.M. , Davidson W.C. , Mann I. 
Published: June 2019

AbstractMotivated by new infrared observations, we examine the contribution of various size intervals of interplanetary dust particles to visible and infrared scattered radiances of the solar F-corona, employing Mie theory and particle size distributions based upon differing interpretations of lunar microcrater evidence and interplanetary flux measurements.
A fragmentation model of dust grains in the inner coma of Halley. A possible explanation of the color effect
Authors: Goidet-Devel B. , Clairemidi J. , Moreels G. , Rousselot P. 
Published: June 2019

AbstractA model to describe the intensity of dust scattered light observed by the spectrometer TKS during the Vega/Halley encounter is presented. Good agreement is obtained when using a particle radius dependent mass density. The color effect is reproduced if the refractive index of tholin is adopted.
Polarimetric Measurements of Scattered Light by Dust Grains In Earth and Microgravity Conditions. Tentative Interpretation of the Dichotomy between Comets
Authors: Hadamcik E. , Levasseur-Regourd A.C. , Worms J.C. 
Published: June 2019

AbstractThe evolution of the polarization of light scattered by dust particles (e.g. cometary dust) with the phase angle is an indicator of the physical properties of the particles. For grains large compared to the wavelength, the maximum value of polarization Pmaxincreases with increasing size. A dichotomy is pointed out in the cometary poiarimetric phase curves, showing two ranges of values for Pmax. A comparison between laboratory measurements performed under Earth and microgravity conditions is presented. Pmaxand the corresponding αmaxappear to be smaller in microgravity than for ground based measurements. The comparison between ground based, microgravity and cometary results is then tentatively discussed in term of physical properties of the grains.
Scattering Properties of Cometary Grains
Authors: Vaidya D. B. , Desai J. N. 
Published: June 2019

AbstractHalley probes (Giotto, Vega) have shown that cometary grains can be extremely dark and might have fluffy structures. These probes have also detected submicron sized particles in the coma of the comet. In view of these observations and to interpret the observed data on several other comets we calculate the angular distribution of the scattered intensity, polarization and albedo for porous and compact particles. For these calculations, we apply discrete dipole approximation (DDA) first to the spheroidal particles, assumed to be made of small scattering elements (dipoles). Then we reduce the number of dipoles systematically to model the porous grains. We study the phase function, linear polarization, and albedo as a function of grain size and packing density.
Genetic improvement of meat production in sheep and cattle -current industry schemes and future possibilities
Authors: Simm G , Steane D E 
Published: June 2019

ABSTRACTOverfatness of lamb and beef carcasses is a problem in many countries. Genetic improvement of carcass composition, particularly in specialised terminal sire (meat) breeds, should lead to permanent, cumulative, and cost-effective improvements. In the past, selection in these breeds has been mainly on liveweight. However, the use of in vivo estimates of carcass composition is expected to lead to higher rates of progress. In ruminants index selection is likely to be most useful, and early results from selection experiments are encouraging. Although schemes for recording performance and estimating breeding values are in operation in many countries, structural problems such as small herd or flock sizes, and lack of comparisons between herds or flocks impede progress. To some extent, these problems could be overcome by cooperation amongst breeders and wider use of new statistical techniques. Genetic improvement of meat production could be further enhanced by improved techniques for in vivo estimation of carcass composition, and by use of embryo transfer to increase “annual selection intensity” of females.
Collection, storage and distribution of information on the value of by-products and wastes in animal feeding
Authors: Haendler H. 
Published: June 2019

To use information means to use the experiences of others to make decisions. In fields where experience is lacking it can be gained by conducting experiments. People who have available experience in a special field are called experts. In each field of economics production is subject to changes of several factors such as price and availability of the raw material needed for the special type of production. Animal production depends mainly on the availability and prices of useful feeds, and should be regarded as one type of production among others, the different types being more or less correlated.From time to time changes in industrial or other types of production occur. New materials, often regarded at first as worthless wastes, may be found to be suitable as feeds, but thousands of tonnes of such a new material may have been destroyed before its feed value was established. In other cases the new material may have been given to animals but without success, causing illness or reducing efficiency. The reason for the failure may be that no previous experience was available, no experiments had been made previously or were known and no expert could be asked. In other words, no information was available about the nutritional value of the specific material.The situation of deficiency of information is comparable to the situation of deficiency of feeds. If regular feeds are not available in adequate quantum or at acceptable prices, then interest in the use of by-products and wastes increases. If no results from research in that specific field are published and no experience is available, one has to look for ‘by-products’ of knowledge. Anybody anywhere in the world may have analysed a sample of a feed for a specific purpose. The result may have been forgotten after the particular question had been answered. But perhaps some years later this piece of knowledge could be used for a quite different purpose. The experience of others then becomes valuable.
4.2 Parenteral Methods of Trace Element Supplementation
Authors: Allen W. M. , Moore P. R. 
Published: June 2019

Dietary manipulations or other oral treatments are, in many cases, the most efficient solution to the problem of trace element deficiency diseases in farm animals. Such approaches are particularly effective against chronic primary deficiencies where there is simply not enough of the required element in the diet to satisfy the animal's needs.In some situations, however, notably severe and acute deficiencies, parenteral injections of a supplement provide the best methods of restoring normal mineral concentrations in the deficient animal's tissues. Parenteral supplements are also particularly effective against many secondary deficiences in which factors in the diet convert apparently adequate dietary concentrations of the required element into an unavailable form: their effectiveness arises because absorption from the alimentary canal is bypassed. Injectable trace element supplements have also proved particularly useful for short term supplementation during periods when there is a great demand for the element, for instance during pregnancy. One further advantage of the parenteral route of supplementation is that a known amount of the element is introduced into the animal's system.
Land use in the hills and uplands
Authors: Thomas T. H. , Harding D. , Hattey R. , Martin W. D. 
Published: June 2019

AbstractThe paper summarises briefly the current status of the major land using activities in the hills and uplands. The dominant land use roles of agriculture and forestry arc explained, as are other uses of recreation, water provision and wild life and landscape conservation. Land use competition in the hills and uplands is seen as the end result of conflicting policy objectives pursued by the major rural resource planning agencies over the past 50 years. The role of these agencies is analysed, as is their ability to meet their objectives in competition with each other. Finally, an attempt is made to establish a quantitative framework within which the interests of the various groups are recognised and priorities in land use can be determined.
Genotype by environment interactions: experience from Langhill
Authors: Veerkamp R. F. , Simm G. , Oldham J. D. 
Published: June 2019

AbstractGenotype by environment interaction was investigated for a range of traits. Selection (S) and control line (C) cows, housed and managed at the Langhill Dairy Cattle Research Centre, were offered ad libitum complete mixed diets, with proportions (in total dry matter) of concentrates, silage, brewers’ grains of either 20:5:75 (LC; 1.0 t concentrate per annum) or 45 :5 :50 (HC; 2.5 t concentrate), over a full lactation. No diet X genetic line interactions were observed for a range of traits (production, food intake, live weight and condition score) when compared as means. However, regression coefficients of protein yield (P < 0.05), milk yield (P < 0.10) and protein percentage (P < 0.10) on pedigree index for fat plus protein yield were different between LC and HC. Genetic correlations between HC and LC were high for most traits, and only for fat yield was the value below 0-80. Because the rate of increase in energy output from selection is unlikely to be matched by the rate of increase in intake during the first part of the lactation, it was expected that intake capacity is likely to become more important in the future, regardless of the feeding system. For this reason, it is suggested that selecting for a lower live weight whilst simultaneously selecting for increased yield (an approach which has been advocated in some countries) should be treated cautiously. Especially on low input diets increases in yield as a result of continued selection (on higher input diets) may be limited by the rate, or extent of tissue mobilization; under these circumstances health and fertility problems might be the first indicators of such limits being approached.
Summary policy recommended for eastern and southern Africa: Mbabane, Swaziland, 28 July to 1 August, 1997
Authors: Bunoti C. W. 
Published: June 2019

AbstractThe seminar, the aim of which was to develop policy recommendations to improve the livestock sector in eastern and southern Africa, was held from 28 July to 1 August 1997 in Mbabane, Swaziland. All countries were represented and a wide range of topics were discussed. These included livestock development in Africa, relative to the rest of the world, and meeting the food security needs of each country, for which production must increase at 4% per annum, rather than 2% as at present.Topics considered included: constraints to livestock development, current status, global and African trends in the livestock sector, human resource needs, animal genetic resources, animal health constraints, data and information, research and extension, private sector contribution, participation and contribution by donors or international organizations and interactions between livestock, environment and wildlife.Recommendations were made on: livestock, environment and wildlife interactions for extensive production systems and mixed crop and livestock interactions for intensive production systems, animal health and genetic resource constraints and policy information management and communication.The region under discussion has a tremendous potential for livestock production, which has not been fully realized, and potential internal markets for livestock and livestock products. At present it lacks cohesive livestock development policies at both national and regional levels. The region carries more than 37%, 72%, 63%, 55%, 33% and 39% of Africa's human, cattle, sheep, goat, pig and chicken populations respectively (FAO, 1988).The purpose of this paper is an attempt to summarize the proceedings of the seminar, highlighting the issues raised and recommendations made.
The hydrography of Irvine Bay and its relation to the Clyde Sea Area
Authors: Lewis R. E. 
Published: June 2019

SynopsisOver the period 1973–75, detailed studies were made of the water density structure and circulation of Irvine Bay. Observations showed that offshore waters were influenced by water originating in the Clyde Estuary and the inshore waters were affected by brackish outflow from the Irvine-Garnock Estuary. Long period current records indicated that the movement of water in Irvine Bay and the eastern Clyde Sea Area was particularly responsive to meteorological forcing. Based on data for 1974, the estimated annual mean longshore drift was about 5·0cm/s and directed towards the northwest. Studies of a tracer dye patch over a 1·5 day period showed that horizontal dispersion was influenced by vertical shears in the mean current and that vertical mixing was inhibited by a density interface at less than 4 m depth. The average longitudinal and transverse dispersion coefficients were 2·17m2/s and 0·25 m2/s respectively.
The demersal fishery in the Clyde Sea Area
Authors: Hislop J. R. G. 
Published: June 2019

SynopsisData from the Clyde demersal fishery during the period 1960 to 1984 are presented. Annual landings of demersal species at Chde ports in recent years have ranged from 4000 to 10,000 tonnes, with a first sale value of £2–5 million. In the 1960s the fishery was undertaken mainly by seine-net vessels, but the present fleet consists largely of dual-purpose light/Nephrops trawlers. The demersal fishery is seasonal and during the winter and spring there is an influx of ‘stranger’ vessels. Five species (cod, whiting, saithe, hake and haddock) make up more than 80% of the demersal landings from the Clyde. The landings of saithe have fluctuated very considerably during the period under review. Other relatively important species are dogfish, plaice, skate and ray and angler fish. In general the Clyde fishery represents only a small proportion of the total Scottish landings but in recent years landings of hake from the Clyde grounds have averaged approximately 40% of the Scottish hake total. The Clyde demersal fishery depends to a large extent on young fish and both the total annual landings and the relative importance of the principal species fluctuate from year to year in response to variations in the strength of the recruiting year classes. The catch rates of the principal species vary greatly throughout the year. Although there is no conclusive evidence that the Clyde populations are self-contained, all the major species are known to spawn within or close to the area and tagging experiments have suggested that there may not be much mixing between Clyde fish and those from surrounding areas. This may in part, however, reflect the fact that fishing intensity within the Clyde is high and fish are recaptured before they have had time to leave the area. For management purposes, the Clyde demersal stocks are included in ICES Sub-area VI.
The saltmarshes of the Firth of Clyde
Authors: Doody J. P. 
Published: June 2019

SynopsisThe saltmarshes of the Firth of Clyde are restricted both in area and number. Despite this they exhibit considerable variation in terms of their physical environment, floristic composition and range of plant communities. The absence of grazing at most of the sites has resulted in their exhibiting plant communities atypical of most of the other saltmarshes of western Scotland. Like many other saltmarsh areas they have suffered from reclamation of the older, upper marsh. However, despite this, there are still important transitional communities to non-tidal vegetation. The prevention of further incursions into the sites for roads, industrial development, caravans and the like, is important if these sites are to remain as examples of natural habitats.
Digestible and metabolisable energy values of coconut meals of different oil contents in the diets of pigs
Authors: Thorne P.J. , Wiseman J. , Cole D.J.A. 
Published: June 2019

Coconut meal is a by-product of oil extraction from dried coconut kernel or copra. It is a highly variable material which, in practice, may contain from almost 0% ether extract (EE) when the oil has been solvent extracted to around 20% EE when the least efficient mechanical extraction methods are used. The trial reported here examined the effect of processing which produced meals of varying levels of residual oil, on subsequent dietary energy values.Five coconut meals (A-E) and one sample of unprocessed copra (F) were used as a basis of the dietary treatments. Sample A was a solvent extracted meal and samples B-E were all extracted by mechanical means. Analysis of the samples is shown in Table 1.
The use of pedometers to detect oestrus in dairy cows
Authors: Schofield S.A. , Phillips C.J.C. 
Published: June 2019

Poor oestrous detection is considered by many the most important management problem in the UK dairy herds. Various detection aids are available to the farmer, but in spite of these the average oestrous detection rate in Britain is low, only about 40 - 60% (Poole and Mabey, 1986).Cows in oestrus tend to be more active than non-oestrous cows and results from various workers indicate that activity is a good indicator of oestrus (Kiddy 1976, Lewis and Newman, 1984). Three experiments were conducted to investigate the relationship between the distance walked and oestrous state of cows.Pedometers designed to measure human walking activity were used to measure the physical activity of the dairy cow. These were attached to the hind leg of the cow. In experiment 1 distance walked (miles/day) was recorded twice daily for 20 cows in a cubicle shed on the day of oestrus and 5 days pre - or post - oestrus. In experiment2 pedometers were evaluated in two environments for oestrous detection with 20 cows allocated to a cubicle shed or a straw yard. In a third experiment behavioural observations of 20 cows were recorded four times daily with pedometer readings.