bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using the 6dF Galaxy Redshift Survey to Detect Gravitationally-lensed Quasars
Authors: Mortlock Daniel J. , Drinkwater Michael J. 
Published: September 2002

AbstractIt is possible to detect gravitationally-lensed quasars spectroscopically if the spectra obtained during galaxy surveys are searched for the presence of quasar emission lines. The up-coming 6 degree Field (6dF) redshift survey on the United Kingdom Schmidt Telescope will involve obtaining ~105 spectra of near-infrared selected galaxies to a magnitude limit of K = 13. Applying previously developed techniques implies that at least one lens should be discovered in the 6dF survey, but that as many as ten could be found if quasars typically have BJ – K ~ 8. In this model there could be up to fifty lensed quasars in the sample, but most of them could only be detected by infrared spectroscopy.
UBV Photometry of the Massive Eclipsing Binary TT Aur
Authors: Özdemir S. , Ak H. , Tanriver M. , Gülseçen H. , Gülseçen S. , Saygaç A. T. , Budding E. , Demircan O. 
Published: September 2002

AbstractUBV observations of the massive binary system TT Aur were carried out mainly at theTurkish National Observatory (TUG). These observations, together with IUE spectra and times of eclipse minima collected from the literature, were used to study the system parameters.Simultaneous solution of the light curves by the Wilson-Devinney code allows a semi-detached configuration with a slightly larger Roche-lobe filling secondary. This picture is supported by other evidence. The shoulders of the primary minimum suggest some excess absorption, in keeping with circumstellar material in the form of a disk-like structure around the primary component. The deeper primary minimum in the U filter may indicate a hotter region on the secondary-facing hemisphere of the primary.The period variation of the system can also be related to the possible existence of a third component in a circular orbit around the system.An alternative detached representation is also considered using optimal curve-fitting techniques. We appeal for further observations to help resolve some outstanding issues in this interesting massive binary.
Total Magnitudes of Virgo Galaxies. II. An Investigation into the mp Scale of Volume I of Zwicky et al.'s Catalogue of Galaxies and of Clusters of Galaxies
Authors: Ke-shih Young Christopher , Shao Zheng-yi 
Published: September 2002

AbstractWe investigate the photographic-magnitude (mp) scale of Volume I of the Catalogue of Galaxies and of Clusters of Galaxies for galaxies in the Virgo direction. It is found that for 11.5 ≤ Bt < 14.5, the mp values listed correspond very closely (with a scatter of only 0.16 magnitude) to blue magnitudes measured to the B = 24.4 isophote. If mp values need to be used as estimates of total blue magnitude the scatter is 0.27 magnitude over the same range in Bt and the mean offset is mp – Bt = 0.28 magnitude. However, a serious scale error at the bright end causes both the isophotal and total luminosities of galaxies brighter than Bt ~ 11.5 to be severely underestimated. At the faint end there also appears to be a significant scale error. This causes galaxy luminosities to be seriously overestimated faintward of Bt ~ 14.5.We demonstrate that this is a real effect based on a detailed galaxy-by-galaxy study of the catalogue’s completeness down to Bt = 17.0. The catalogue is found only to be complete to Bt ~ 14.7 whilst its degree of incompleteness is found to be relatively constant at the 30% level over the range 14.75 ≤ Bt < 15.75. Most of the missing objects are found to be elliptical galaxies and so late-type objects are over-represented at the faint end.
Galactic Structure and the Cosmic Ray Anisotropy at 1018eV
Authors: Clay R. W. 
Published: September 2002

AbstractCosmic ray arrival directions at energies a little over 1018 eV have been reported to show an excess from directions close to that of the Galactic centre. That result was originally presented by the AGASA group and was later strengthened by an analysis of SUGAR cosmic ray data. We discuss here a second feature of the AGASA data, a deficit in roughly the Galactic anticentre direction.We interpret this as a result of cosmic ray diffusion past us. We find that the most straightforward interpretation of the data then requires that a strong magnetic field exists out of the plane of our Galaxy to distances of at least several kiloparsecs.
Relativistic Jet Flow from a One Dimensional Magnetic Nozzle—Analytic Solutions
Authors: Liffman Kurt 
Published: September 2002

AbstractMagnetohydrodynamic devices that can accelerate plasmas to speeds of the order of hundreds of kilometres per second have been designed and built for nearly forty years. Up to the time of writing, however, the theory for such devices has been exclusively non-relativistic. In this paper we derive the special relativistic magnetohydrodynamic (SRMHD) equations and use them to obtain the relativistic, magnetic nozzle equation which describes the production of jet flows with speeds approaching the speed of light.We obtain analytic solutions to this equation and show that, in principle, magnetic field gradients can accelerate a plasma to highly relativistic speeds. We also show that the exit kinetic energy, EK, of a particle is given by the equation EK = m0C2FR, where m0 is the rest mass of the particle and CFR is the fast magnetosonic speed at the start of the flow.The relativistic nozzle differs in a number of ways from the non-relativistic case.A non-relativistic nozzle has a relatively symmetric converging/diverging shape, while a highly relativistic nozzle converges in the usual manner, but diverges, in an abrupt fashion, at the very end of the nozzle. The gentle divergence of non-relativistic nozzles causes the exit plasma densities and magnetic fields of the flow to have values that are small relative to their values at the start of the nozzle. The abrupt divergence of a highly relativistic nozzle implies that, for a less than perfect nozzle, the exit values of the mass density and the magnetic field strength are comparable to their initial values. This unexpected dichotomy in behaviour may have future application in understanding the ‘radio-loud’ and ‘radio-quiet’ relativistic jets that are produced from astrophysical sources.
On Eagle's Wings: The Parkes Observatory's Support of the Apollo 11 Mission
Authors: Sarkissian John M. 
Published: September 2002

AbstractAt 12:56 p.m., on Monday 21 July 1969 (AEST), six hundred million people witnessed Neil Armstrong's historic first steps on the Moon through television pictures transmitted to Earth from the lunar module, Eagle. Three tracking stations were receiving the signals simultaneously. They were the CSIRO's Parkes Radio Telescope, the Honeysuckle Creek tracking station near Canberra, and NASA's Goldstone station in California. During the first nine minutes of the broadcast, NASA alternated between the signals being received by the three stations. When they switched to the Parkes pictures, they were of such superior quality that NASA remained with them for the rest of the 2-hour moonwalk. The television pictures from Parkes were received under extremely trying and dangerous conditions. A violent squall struck the telescope on the day of the historic moonwalk. The telescope was buffeted by strong winds that swayed the support tower and threatened the integrity of the telescope structure. Fortunately, cool heads prevailed and as Aldrin activated the TV camera, the Moon rose into the field-of-view of the Parkes telescope. This report endeavours to explain the circumstances of the Parkes Observatory's support of the Apollo 11 mission, and how it came to be involved in the historic enterprise.
Equatorial Pulsar Winds
Authors: Kuijpers Jan 
Published: September 2002

AbstractAtraditional problem in pulsar wind physics has been the nature of the pulsar wind.Ontheoretical grounds, the wind is expected to be dominated by Poynting flux associated with the outgoing magnetic field lines anchored on the polar caps of the rotating neutron star, while observations of the Crab Nebula demonstrate that the wind must be dominated by kinetic energy before the termination shock. Here we suggest a new approach to this old problem by studying the distributed currents rather than the singular sheet currents which have been the object of study in most work.We find that, at a distance well in between the light cylinder and the termination shock, current starvation sets in, and electric fields develop along the magnetic field lines which cause the current to dissipate and convert at least half of the Poynting flux into kinetic energy flux in a relatively thin shell. In the shell, at least half of the current closes across the magnetic field lines, the pitch of the spiralling magnetic field lines jumps downward strongly, and the outer pattern of magnetic field lines slips over the inner pattern.
Propagation Effects on Pulsar Radio Emission
Authors: Luo Qinghuan 
Published: September 2002

AbstractPropagation effects on radio emission within the pulsar magnetosphere are discussed. Widely accepted pulsar models assume that a pulsar magnetosphere is populated with relativistic pair plasmas produced through electron–positron cascades by accelerated primary particles above the polar cap. Any radio emission produced well inside the light cylinder (the radius at which the rotation speed equals c) must propagate through the magnetospheric plasma and be subject to plasma dispersion effects such as refraction and absorption. The observed pulse profiles should contain some features that reflect the influence of the intervening plasma. I discuss particularly the absorption effect due to cyclotron resonance and its possible observational consequences.
Mode Conversion and Reflection of Langmuir Waves in an Inhomogeneous Solar Wind
Authors: Willes A. J. , Cairns Iver H. 
Published: September 2002

AbstractBeam-driven Langmuir waves in the solar wind are generated just above the electron plasma frequency, which fluctuates in the inhomogeneous solar wind plasma. Consequently, propagating Langmuir waves encounter regions in which the wave frequency is less than the local plasma frequency, where they can be reflected, mode converted to transverse electromagnetic waves, and trapped in density wells. The aim here is to investigate Langmuir wave reflection and mode conversion at a linear density gradient for typical solar wind parameters. It is shown that higher mode conversion efficiencies are possible than previously calculated, but that mode conversion occurs in a smaller region of parameter space. In addition, the possibility of detecting mode conversion with in situ spacecraft Langmuir wave observations is discussed.
The Relativistic Force-free Equation
Authors: Mestel Leon 
Published: September 2002

AbstractThis paper is a preliminary report on ongoing work, in collaboration with Drs S. P. Goodwyn, A. J. Mestel, and G. A. E. Wright. The non-dissipative force-free condition should be a good approximation to describe the electromagnetic field in much of the pulsar magnetosphere, but we may plausibly expect it to break down in singular domains. The detailed properties of the solutions will be affected critically by the choice of equatorial boundary condition beyond the light-cylinder.
Populations of X-ray Binaries and the Dynamical History of their Host Galaxies
Authors: Wu Kinwah 
Published: September 2002

AbstractThe observed luminosity distributions of X-ray sources indicate the presence of several populations of X-ray binaries in the nearby galaxies. Each population has its formation and evolutionary history, depending on the host environment. The features seen in the log N(>S)–log S curves for different types of galaxies and for different galactic components can be reproduced by a birth–death model, in which the lifespans of the binaries are inversely proportional to their X-ray brightness. Conversely, the dynamical history of a galaxy can be inferred from the luminosity distributions of its X-ray binary populations.
Hydromagnetic Structure of a Neutron Star Accreting at Its Polar Caps
Authors: Melatos A. , Phinney E. S. 
Published: September 2002

AbstractThe hydromagnetic structure of a neutron star accreting symmetrically at both magnetic poles is calculated as a function of accreted mass, Ma, starting from a polytropic sphere plus central magnetic dipole (Ma =0) and evolving the configuration through a quasistatic sequence of twodimensional, Grad–Shafranov equilibria as Ma increases. It is found that the accreted material spreads equatorward under its own weight, compressing the magnetic field into a thin boundary layer and burying it everywhere except in a narrow, equatorial belt. The magnetic dipole moment of the star is given by µ=5.2×1024(B0/1012.5G)1.3(Ma/10−8Mʘ yr−1)0.18(Ma/Mʘ)−1.3Gcm3, and the fractional difference between its principal moments of inertia is given by Є=2.1×10−5(B0/1012.5G)0.27(Ma/10−8Myr−1)0.18(Ma/Mʘ)1.7, for Ma in the range 10−5Ma/Mʘ10−1,where B0 is the pre-accretion magnetic field strength, and Ma is the accretion rate.
Binary Star Observations in Selected Instants of Good Seeing
Authors: Davis John , North Julian R. 
Published: September 2002

AbstractVideo recordings of images of binary stars at the focus of a 0.36m telescope have been used to select images recorded in instants of good seeing. The selected images have been analysed to give separations and position angles for the binary systems which are in good agreement with values predicted from previous observations. In these exploratory observations it has been shown that separations of 0.9 arcseconds can be measured with an accuracy of ~2% and position angles to ~1–2 degrees when the average seeing was ~1.3 arcseconds. These observations demonstrated that the diffraction limit of the telescope could be reached when the seeing was a factor of 2–3 greater than it. A binary with three magnitudes difference in the brightness of its components has been measured with comparable accuracy although difficulties are anticipated for binaries with components closer than ~2 arcseconds with this magnitude difference. The limiting magnitude is determined by the need to limit exposure times of individual frames to be comparable with or less than the atmospheric coherence time.
Filamentary Shell Structures from the AAO/UKST Hα Survey
Authors: Walker A. J. , Zealey W. J. , Parker Q. A. 
Published: September 2002

AbstractHere we present the first results of a search for new optical supernova remnant candidates and other filamentary objects on films produced by the Anglo-Australian Observatory/UK Schmidt Telescope Há Survey. Sixty-one fields, or 26% of the Galactic plane survey fields, have been visually examined. This has resulted in the detection of four newlarge diameter filamentary structures, and the discovery of extensive new optical emission in two previously known optical supernova remnant candidates.
NEW MATERIALS USED AS OPTICAL WINDOW IN THIN FILM SOLAR CELLS
Authors: GORDILLO G. 
Published: September 2002

The purpose of this work is to investigate new materials which present good properties to be used as optical window and buffer layer in thin film solar cells based on CdTe and CuInSe 2. As potential candidates for optical windows, two different bilayer systems were studied: ZnO/In x Se y and ZnO/ZnSe. They are planned to be used later in the fabrication of solar cells with structures CuInSe 2/ In x Se y/ ZnO and ZnO/ZnSe/CdTe. The methods used to prepare the different window materials, as well as the technological stages of the solar cell fabrication, will be described. Additionally, the optical and morphological properties of the window systems will be studied through transmittance and atomic force microscopy (AFM) measurements. Preliminary results obtained with Cu(In,Ga)Se 2 solar cells, fabricated using ZnO/In x Se y as optical window, will be reported. They will be compared with those obtained using ZnO/CdS as optical window, which is regularly used in this type of cells.
EFFECT OF THE CdCl2 TREATMENT ON THE MORPHOLOGY AND STRUCTURAL PROPERTIES OF CdTe THIN FILMS DEPOSITED BY THE CSS METHOD
Authors: INFANTE H. , GORDILLO G. 
Published: September 2002

CdTe thin films deposited by the CSS (close spaced sublimation) method, with adequate properties to be used as absorber layer in solar cells, were submitted to a chemical treatment in a saturated CdCl2 solution, followed by thermal annealing in air at 400°C, in order to improve the electronic properties. The effect of chemical and thermal treatments on the morphological and crystallographic properties was studied through atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements. The studies revealed that the CdTe grows in the cubic phase and that the postdeposition treatments affect the morphology as well as the crystallographic properties; the effect on the morphology is significantly stronger. Increase of the grain size and roughness was observed in samples treated chemically and thermally. On the other hand, no effects were identified on the crystalline structure as induced by the treatments, although recrystallization was observed after thermal annealing.
DEPOSITION, OPTICAL AND STRUCTURAL CHARACTERIZATION OF SnO2:F/CdS AND ZnO/CdS STRUCTURES USED AS OPTICAL WINDOWS IN SOLAR CELLS
Authors: CAICEDO L. M. , MORENO L. C. , SANDINO J. W. , GORDILLO G. 
Published: September 2002

The purpose of this work is to find the conditions for fabricating SnO 2: F/CdS and ZnO/CdS bilayer structures with adequate properties to be used as optical windows in solar cells based on CdTe and CuInSe 2 thin films. In both types of structures the CdS layer is deposited by chemical bath deposition (CBD) and by the evaporation method; the SnO 2: F and ZnO layers are deposited by spray pyrolysis and reactive evaporation, respectively. The influence of the preparation methods on the optical and structural properties of each of the layers constituting the bilayer structures, was studied through spectral transmittance and X-ray diffraction (XRD) measurements. The studies revealed that the spectral transmittance of the ZnO/CdS system is significantly greater than that of the SnO 2: F/CdS structure, indicating that the first type of structure is more suitable for using as optical window in solar cell fabrication.
The taxonomy of the family Xyalidae Chitwood, 1951 (Monhysterida: Nematoda): a cladistic analysis
Authors: Trueman John , Nicholas Warwick 
Published: September 2002

AbstractA cladistic analysis of the family Xyalidae has been carried out, with selected Monhysteridae and Sphaerolaimidae as presumptive outgroups. Forty nine characters, taken from published descriptions, were scored for 91 species from 33 genera. The way in which the characters were coded is illustrated by drawings and graphs. Phylogenetic analyses were conducted with the programs PAUP*4.0d65 and PAUP*4.0b2. Neighbour-joining and parsimony trees were constructed and the preferred consensus parsimony tree is presented. The tree has been divided into 15 groups for purposes of discussion. All eight species of Monhysteridae form a separate clade consistent with outgroup status, but the four species of Sphaerolaimidae are not separated from Xyalidae. Several of the Daptonema species, Pseudosteineria plus Steineria, and Rhynchonematinae form three well supported clades. Other groupings are much less well supported and are presumed to be paraphyletic. Many published descriptions do not include sufficient detail to allow relationships to be determined and suggestions are made as to data which should be included in future taxonomic descriptions of Xyalidae.
Variation in entomopathogenic nematode (Steinernematidae and Heterorhabditidae) infective-stage jumping behaviour
Authors: Kaya Harry , Campbell James 
Published: September 2002

AbstractSpecies and strains of entomopathogenic nematodes (Heterorhabditidae and Steinernematidae) were assessed for the expression of standing and jumping behaviour. Jumping occurred in 11 species of Steinernema, but the rate of jumping varied considerably among the species. Variation in the duration of crawling bouts, the tendency to body wave, the rate of standing, the duration of standing bouts, and the tendency to jump after standing contributed to the differences in frequency of jumping among species. Within a species, nematodes that jumped were similar in size, infectivity and sex ratio to those that did not jump, but jumpers tended to be more infective and to have lost their sheath (i.e., the second stage cuticle). This comparison of species is an important first step in assessing the adaptive value of jumping behaviour as part of the foraging strategies of entomopathogenic nematodes.
Does osmoregulatory behaviour in entomopathogenic nematodes predispose desiccation tolerance?
Authors: Liu Qhi-Zhi , Glazer Itamar , Wright Denis , Piggott Simon 
Published: September 2002

AbstractInfective juveniles of four isolates of entomopathogenic nematodes placed into balanced (mixed) salt solutions displayed varying levels of ability to osmoregulate under hyperosmotic conditions. The isolate with the greatest desiccation tolerance (Steinernema carpocapsae SCB-L1) showed the greatest osmoregulatory ability. However, the isolate with the poorest desiccation tolerance (Heterorhabditis sp. HIS-33) could also osmoregulate. One isolate with moderate desiccation tolerance (H. bacteriophora HP88) had the poorest osmoregulatory ability while another (HIS-28) showed good osmoregulatory ability. This shows that there is not necessarily a close link between hypo-osmotic regulation and desiccation tolerance. The need for separate screens for these different survival attributes is, therefore, indicated. Assessment of Heterorhabditis sp. isolate HIS-28 found that osmoregulatory ability and percent survival was greater in balanced salt solutions compared with single salt solutions, providing indirect evidence for a specific ionic regulation mechanism.
Speciation in the Acugutturidae (Nematoda: Aphelenchida)
Authors: Adams Byron , Silvain Jean-François , Marti Orville 
Published: September 2002

AbstractEctoparasitic nematodes (Acugutturus, Vampyronema and Noctuidonema) of the family Acugutturidae from 13 species of Lepidoptera (moths) and one species of Blattodea (cockroaches) were collected, measured and analysed by discriminant analysis in order to identify conspecifics and to determine which morphological characters were useful in defining differences between nematodes on different host species. The position of the excretory pore posterior to the metacorpus clearly differentiates Acugutturus parasiticus from Noctuidonema and Vampyronema. Two populations of A. parasiticus on Periplaneta americana from the West Indian islands of St Lucia and Guadeloupe are conspecific. Nematodes resembling Vampyronema, collected from two genera of Sphingidae in Guadeloupe are characterised by extremely long stylets, equal to ca 37% of the body length, and may represent a new genus. Noctuidonema from four species of Spodoptera (Noctuidae) are conspecific. However, a somewhat different Noctuidonema from the noctuid Pseudaletia unipuncta may represent a new species, based primarily on its shorter stylet length. Simple spicule structure, a smaller V percentage, and a shorter stylet in Vampyronema are characters that best define its differences from Noctuidonema. Nematodes on the noctuids Anicla infecta and Eulepidotis addens probably represent two new species of Vampyronema. There was no clear differentiation between nematodes on the noctuids Mocis disseverans, M. latipes, Agrapha oxygramma and Orthodes crenulata, and they are all probably conspecific with V.dibolia. Thus far, Noctuidonema has been found only on the trifine noctuids Spodoptera and Pseudaletia, whereas Vampyronema has been found on both trifine and quadrifine noctuids. We found evidence for sequential evolution, but not co-evolution, between these ectoparasitic nematodes and their lepidopteran hosts.