bluuebunny/crossref_metadata_2025 huggingface dataset:
A Modular Tool for the Evolutionary Synthesis of Stellar Populations
Authors: Maraston Claudia
Published: July 2016

An innovative tool for the construction of Evolutionary Synthesis models of Stellar Populations is presented. It is based on three independent matrices giving respectively 1) the fuel consumption during each evolutionary phase as a function of stellar mass, 2) the typical temperatures and gravities during such phases, and 3) colors and bolometric corrections as a function of gravity and temperature. The first matrix allows to calculate the relative contribution of each phase to the bolometric light of the population, thanks to the so-called Fuel Consumption Theorem (Renzini & Buzzoni 1986, in Spectral Evolution of Galaxies, ed. C. Chiosi and A. Renzini (Dordrecht:Reidel), p.195)). The other two matrices allow to distribute such contributions in the various passbands, and thus to compute the synthetic colors of the population as a function of age. The modular structure of the code allows to easily assess the impact on the synthetic spectral energy distribution of various model ingredients (e.g. uncertainties in the stellar evolutionary models, mixing length, temperature distribution of the horizontal branch (HB) stars, AGB mass loss, color-temperature transformations, etc.) Models have been computed with Y=0.27, Z=0.02 and for three choices of a double-slope IMF (s = 1 + x = 2.35, 3.5, 1.5 for M ≥ 0.6 M⊙ and s' = s − 2.5 for M < 0.6M⊙). Among the main results, it is found that: i) the appearence of an extended AGB has a strong impact on the integrated (V − K)0 color, which increases by ≃ 1.5 mag in Δt ≃ 400 Myr; ii) the inclusion of a blue-HB developing at ages around 10 Gyr produces a hook-shape in the (U − B)0 vs (B − V)0 locus described by aging stellar populations, in agreement with what observed for Magellanic Clouds Clusters.
Optical and IR Properties of Radio Galaxies as a Function of their Radio Power
Authors: Maxfield L. , Djorgovski S.G. , Thompson D. , Pahre M.A. , de Carvalho R.R. , Vigotti M. , Grueff G.
Published: July 2016

We compare optical and infrared photometric and spectroscopic properties of high-redshift radio galaxies from the 3CR and B3 surveys. At a given redshift and a fixed restframe frequency, the two samples differ on average by an order of magnitude in radio power, thus providing a fair baseline in radio powerfor a range of redshifts. We present new optical and IR photometry and spectrosopy for a number of B3 sources. We combine these data with the existing corresponding information on B3 and 3CR sources, in order to explore different correlations of source properties with redshift, and among themselves. B3 sources follow the same trend as 3CR's in the K band Hubble diagram, although they do seem to be slightly fainter on average at a given redshift. This trend is slightly more prominent in the Gunn r band. This suggests that some fraction of the observed light in the r and K bands is contributed by an active nucleus, which also powers the radio lobes. The B3's also tend to have lower emission line luminosities than 3CR's at any given redshift, suggesting that there may be a correlation between line luminosity and radio power. Such a correlation is clearly seen and is followed by both samples. It suggests that the UV emission lines are largely powered by the active nucleus, ostensibly a hidden quasar, which is also responsible for the radio emission. We also examine the behavior of the optical and radio PA alignments for the combined B3+3CR data set. We find that high-power and high-redshift subsamples for both B3's and 3CR's show the alignments more prominently, but we still cannot tell which of these variables dominates this effect. This work was supported in part by the NSF PYI award AST-9157412, and the Bressler Foundation.
A Model for the Globular Cluster Luminosity Function
Authors: McLaughlin Dean E. , Pudritz Ralph E.
Published: July 2016

We develop the idea (Harris & Pudritz 1994, ApJ, 429, 177) that, like currently forming star clusters and associations, globular clusters (mean mass ≃3×105M⊙) were born in the ‘cores’ of much larger (∼108 – 109M⊙) star-forming complexes which we call ‘supergiant molecular clouds,’ or SGMCs. The number N(m) of protoclusters at mass m is then determined by a steady-state balance between their growth by core-core collisions, and their self-destruction via the side effects of star formation. This mass spectrum is ultimately passed on to the globular cluster system (GCS) itself, by virtue of the very high star-formation efficiency required to produce a bound stellar cluster from a gaseous core.
An Automated Search for Low Surface Brightness Dwarf Elliptical Galaxies
Authors: Morshidi Z. , Smith R.M. , Davies J.I.
Published: July 2016

A new automated technique applied to APM scans of UKSTU photographic plates has been used to search for LSBGs in the Fornax cluster. 92 galaxies, almost all of which were classified by Ferguson (1989) as dwarf ellipticals, were found. Fields to the East and West of the cluster were found to have 46 and 13 LSBGs, respectively, as shown in the figure below (□ are LSBGs, ▲ are brighter galaxies).
Bar dissolution and bulge formation
Authors: Norman C.A. , Hasan H. , Sellwood J.A.
Published: July 2016

We discuss the general classification of secular evolution in galaxies into terms of stellar dynamics. We present two-dimensional N-body simulations of a disk galaxy in which a central mass concentration is imposed after the formation of a strong bar. We show that the bar dissolves almost completely if the central mass concentration exceeds approximately 5% of the combined disk and bulge mass. This behavior can be understood in terms of previous work on single particle orbits (Hasan & Norman 1990, Hasan et al. 1993); the sustaining orbits aligned with the bar become stochastic as the Inner Lindblad resonance moves out past the minor axis of the bar. We present arguments that bar formation and subsequent thickening and dissolution will create a bulge-like stellar distribution from the central part of the disk. We discuss the predictions of such a model including the point that barred Scs with sufficient central mass concentrations should be building bulges now. We emphasize that bulges can come from a number of different mechanisms and we discuss the current evidence at both high and low redshift.
Number Counts and Evolving Dwarfs
Authors: Philllipps S. , Driver S.P.
Published: July 2016

Recent redshift surveys (eg. Colless et al. 1993) have shown that the excess galaxies seen in faint B band number counts are not evolved giants at high redshift, but low to moderate luminosity objects at modest redshifts. This led to the suggestion (eg. Cowie et al. 1991) that there was once an extra population of dwarfs which has now disappeared, ie. there is nonconservation of galaxy number. We have investigated a picture in which the dwarfs have merely faded to become very low surface brightness galaxies like those now turning up in nearby clusters (eg. Turner et al. 1993).
Search for Emission Line Galaxies Towards nearby Voids
Authors: Popescu C.C. , Hopp U. , Elsässer H.
Published: July 2016

Recent redshift surveys of galaxies (e.g. the Center for Astrophysics Survey (CfA)), revealed that bright galaxies are distributed in sheet-like structures which surround large voids. Still under debate is the question whether all galaxies follow such a distribution or if less luminous galaxies are more equally distributed. Given the limitation of the actual surveys, the observed emptiness of the voids may be a result of observational bias.
Oxygen Abundances in Diffuse Ellipticals and the Metallicity-Luminosity Relation for Dwarf Galaxies
Authors: Richer M. G. , McCall M. L. , Arimoto N.
Published: July 2016

Using theoretical models of the planetary nebula populations in galaxies, we investigate whether the current oxygen abundances in bright planetary nebulae can be used to predict the oxygen abundance that persisted in the interstellar medium when star formation stopped. In all galaxies, these models predict that a gap develops between the abundances observed in bright planetary nebulae and those that persisted in the interstellar medium when star formation stopped. This abundance gap depends primarily upon the oxygen abundance achieved in the interstellar medium when star formation stopped, though it also has some sensitivity to the history of star formation. The gap is always less than 0.5dex in these models. For the Milky Way, the predicted abundance gap, 0.14dex, is identical to that observed. The abundance gap magnifies the abundance-related differences between diffuse ellipticals and dwarf irregulars found by Richer & McCall (1995, ApJ, 445, 642). Diffuse ellipticals are confirmed to have larger oxygen abundances than similarly luminous dwarf irregulars, and to have larger [O/Fe] ratios than dwarf irregulars with the same oxygen abundance. The simplest explanation for both of these observations is that diffuse ellipticals formed on shorter time scales than dwarf irregulars. Given this difference in the history of star formation, diffuse ellipticals cannot be the faded remnants of dwarf irregulars.
The Near Infrared FeH Lines as Indicators of Surface Gravity of M stars
Authors: Schiavon Ricardo Piorno , Barbuy Beatriz
Published: July 2016

We compute synthetic spectra in the region around 1 μm, including the Wing-Ford band (WFB) of Iron Hydride (FeH) in the calculations. This band is known to be a good indicator of surface gravities of M stars. Employing Kurucz model atmospheres, we study the response of the intensity of the WFB to atmospheric parameters and check our results against observations of M dwarfs. This study is part of an ongoing project which aims to investigate the M dwarf-to-giant ratio in galaxies, through a population synthesis method, exploring a number of spectral indicators in the near infrared, such as the WFB, the NaI, CaII and CO near infrared features.
Evolution and State of the Local ISM
Authors: Schmutzler T. , Breitschwerdt D.
Published: July 2016

The most puzzling observations concerning the LISM (distance < 100 pc) can be explained by a fast adiabatically cooled gas in the cavity of an old superbubble. The ultrasoft X-ray background and contributions to the C- and M-bands are due to the continuum emission of delayed recombination [1]. In contrast to collisional ionization equilibrium (CIE) models, but consistent with recent observations [2], our model predicts a lack of emission lines and a low emissivity in the EUV range. In the figure below we compare the emissivities resulting from CIE at T = 106 K and those from our model at T = 4.2 × 104 K. The basic feature of our model is a thermally self-consistent approach of the time-dependent evolution.
Chemical Evolution of Star-Forming Viscous Disks
Authors: Shioya Y. , Chiba M.
Published: July 2016

Star-forming viscous disk model was proposed by Lin & Pringle (1987) as an ubiquitous mechanism to form the exponential stellar disk of spiral galaxies. To clarify whether the viscous evolution models can explain the chemical properties of general spiral galaxies, we have studied the chemical evolution of star-forming viscous disks under the several physical conditions in relation to the possible processes of the disk formation, and compared with the observed gas and metallicity distributions of spiral galaxy disks.
Spectroscopic Study of NGC 6119 - NGC 6120 System
Authors: Surace C. , Hecquet J. , Auriere M.
Published: July 2016

NGC6119 and NGC6120 have been listed in Kiso catalog (Takase et al., 1987) as Sc and Irr galaxies. They have been selected by their clumpy features in order to investigate their nature and star formation history using slit spectroscopy. They have similar systemic velocities (respectively 9215 and 9200 km ·s–1) and seem to be members of a low gravitational interacting system of 4 galaxies (with MCG-6-36-30 and NGC6122).
Formation of Anisotropy in Galaxies
Authors: Theis Christian
Published: July 2016

Since observations of elliptical galaxies show only a small fraction of gaseous matter, dissipationless N-body models are mainly used to follow the dynamical evolution of these systems. In order to end up with the observed de Vaucouleurs profile these models must be initially very cold which leads finally to a velocity distribution that is isotropic in the core and has a positive anisotropy A ≡ 1 − (σθ/σr)2 in the outer region (σθ, σr are the velocity dispersions in meridional and radial direction.). Contrary to these models, dissipative N-body simulations based on the idea of protogalaxies consisting of inelastically colliding clouds give negative anisotropics outside the core (see Figure). This dominance of circular orbits is caused by a combination of an orbit-dependent collision rate and a conservation of a negative anisotropy formed during the early collapse phase. Therefore, measurements of the anisotropy in galaxies can provide a tool for the study of the dissipative processes in the early galactic evolution.
Mapping the Total Gravitating Mass in Three Groups of Galaxies
Authors: Thiering I. , Dahlem M.
Published: July 2016

We report on the detection and analysis of hot ionized gas in three groups of galaxies (MKW 4s, AWM5, NGC 6329 group) at distances above 100 Mpc (recession velocities above 8000 km s−1). In all three cases their emission is centered on the dominant member of the group (NGC 4104, NGC 6269, NGC 6329, respectively). The central electron densities of the gas ne,0 are about 0.02 cm−3, decreasing to the outside as: ne = ne,0 [1 + (r/rc)2]-3β/2, with an exponent β=0.40 ‥ 0.77, (see Tab. 1). In each case, the spectra are well-represented by thermal Raymond-Smith spectra with kT ≃ 1.0 to 1.3 keV in the center and a weak increase by ca. 0.5 keV to the outside, indicating a slight cooling flow. The fits suggest that none of the central galaxies hosts an AGN that contributes significantly to the emission in the ROSAT band (0.1 to 2.4 keV). Using the radial temperature and density distributions, the total gravitating mass within a radius r can be derived. This value is 1.7±0.4 1013 M⊙ within 300 kpc for all three cases, as opposed to to 1014‥15 M⊙ for rich clusters.
On the Growth Rate of the Correlation Function of Faint Galaxies
Authors: Valls-Gabaud David , Roukema Boud
Published: July 2016

We constrain the growth rate of structure, as represented by the spatial two-point galaxy auto-correlation function, at redshifts where this has not yet been measured directly by combining recent measurements of the amplitude of the angular two-point galaxy auto-correlation, at magnitudes as faint as Vmedian ≤ 25, with new observations of the redshift distribution of very faint galaxies. We show that ξ for the overall galaxy population (at a fixed proper separation r) grows (1 + z)4±1 times as fast as clustering which is fixed in proper coordinates. Even extreme models where “blue” galaxies have a smaller, IRAS-like, correlation function do not reduce the growth rate below (1 + z)2.5±1 times the clustering fixed in proper coordinates (Roukema, B.F. and Valls–Gabaud, D. (1995) A&A, submitted).
B and R Surface Photometry of Faint Galaxies in the Area of Three Cosmic Voids
Authors: Vennik J. , Kovachev B. , Hopp U. , Kuhn B.
Published: July 2016

We performed B and R surface photometry of 92 faint mostly late type galaxies, selected towards three nearby voids (Hopp et al., 1995 A&AS 109, 537). CCD frames were taken with the Calar Alto 3.5m telescope and with the MPIA/ESO 2.2m telescope. We calculated the azimuthally averaged equivalent profiles, asymtotic total magnitudes and colours, and performed ellipse-fitting of isophotes. Observed light profiles were fitted with a power law μ = μ0 + 1.086αr1/n. About 40% of profiles are pure exponentials (n = 1); 38% of the profiles reveal a bulge/disk or disk/disk composition; 20% of them show central light depression. We classified the nearby galaxies (z ≤ 0.04) as being related either to clusters (11 galaxies), to sheets (23) or to voids (9). The obtained parameters are compared to those of HSB and of LSB field galaxies.
High-Velocity Clouds and Galactic Evolution
Authors: van Woerden H. , Schwarz U.J. , Peletier R.F. , Wakker B.P.
Published: July 2016

High-velocity clouds (HVCs) are HI clouds deviating strongly from the general Galactic rotation. Their distances, and hence origins, have long remained unknown. However, three major complexes are now known to lie at z > 1 kpc, while two smaller clouds are closer to the plane (Wakker et al. 1995). These incomplete results still allow a variety of origins.
Dynamics of Massive Black Holes in the Center of Interacting Galaxies
Authors: Wassmer N. , Bien R. , Wielen R.
Published: July 2016

Our numerical tool is SUPERBOX (Bien et al., 1991) which can treat an arbitrary number of galaxies. Simulations including Black Holes are important to understand recent observations, see e. g. Mediavilla and Arribas (1993).
Morphology of E+A Galaxies in CL0016+16 (z=0.54)
Authors: Wirth Gregory , Belloni Paola
Published: July 2016

We present new results on the morphology of member galaxies in the distant cluster C10016+16 from HST images (WFCl). Based on narrow multiband ground-based photometry and spectra obtained with the Keck 10 m telescope we identify 7 new cluster members which appear to have strong Balmer absorption features but no detectable emission lines, doubling the number of such galaxies previously observed with HST in this cluster. These candidate E+A galaxies have been identified in other distant clusters, but the morphology of this population has appeared bulge-like in AC114 (Couch et al., 1994, ApJ 430, 107) and disk-like or irregular and interacting in C10939+47 and C10016+16 (Wirth et al., 1994 ApJ 435, L105). By means of the image concentration index as a quantitative measure of morphology we show that our enlarged sample of E+A objects in C10016+16 now contains some galaxies resembling bulge systems as well as the previously-identified disk-like objects. The observed heterogeneity suggests that both galaxy mergers (rapidly resulting in an r1/4 profile) and ram-pressure stripping of isolated late-type systems may originate E+A objects.
Measuring the Angular Correlation Function for Faint Galaxies at High Galactic Latitudes
Authors: Woods D. , Fahlman G.G. , Richer H.B.
Published: July 2016

The angular correlation function (ω(θ)) for faint, magnitude-limited samples is an important test of large scale structure formation scenarios, as well as being a valuable probe of galaxy evolution. By measuring ω(θ) one hopes to better understand the mechanism or galaxy species responsible for the number counts excess (relative to “no-evolution” models of galaxies) typically observed at blue wavelengths. Images of three ‘blank’ fields were obtained at the prime focus of the CFHT with sub-arcsecond seeing in V, R and I, to magnitude limits of 25, 24.5 and 24, respectively. The angular correlation functions calculated for one field, NF1, in V is shown in Figure 1. Clearly the amplitude of ω(θ) is decreasing at fainter magnitude limits. Note the number of objects detected are not sufficient to accurately measure ω(θ) for an individual field, in a given colour, to significantly small angular separations. In order to do this we must combine the data from our three fields and perform a multi-field fit. A full summary of this analysis will be presented in Woods et al. (1995, in prep.) including determinations of ω(θ) using galaxy samples culled from all our fields and selected by magnitude, colour and surface brightness.
The Age of Elliptical Galaxies in Clusters
Authors: Ziegler Bodo , Bender Ralf
Published: July 2016

Nearby cluster ellipticals follow a very tight relation between velocity dispersion σ and Mg absorption (e.g. Bender et al. 1993, ApJ411, 153). The small scatter in Mg implies that the age and metallicity spread at a given σ in ellipticals is smaller than 15% (applying Worthey's population synthesis models 1994, ApJS95, 107). This means that ellipticals cannot have formed continuously over the Hubble time and ongoing merger processes represent only a tail of latecomers.
CO in the Milky Way
Authors: Blitz Leo
Published: July 2016

If the CO distribution of the Milky Way is described as a truncated exponential rather than as a molecular ring with some gas at large radii, it becomes easier to understand the evolution of the disk of stars. The star formation rate per unit molecular gas mass is constant as a function of radius, and the H2 depletion time turns out to be only a few percent of the Hubble time. This very short timescale requires that the atomic gas act as a reservoir for the active star forming gas. Because the HI has such a different radial distribution, there must either be infall from outside the Galaxy, an efficient way for the atomic gas in the disk to lose angular momentum, or both, leading to measurable infall or inflow velocities. The truncation radius of CO is probably due to the recently identified stellar bar.
Inversion Lines of Photospheric Magnetic Fields and Solar Corona
Authors: Axisa F. , Martres M.-J. , Mercier C.
Published: July 2016

(Solar Phys.). Two results were obtained recently at Meudon concerning the metric type III production by flares which both emphasize the importance of the local magnetic configuration involved.
Distribution of Circularly Polarized Emission across the Solar Disk at λ = 4.3 cm
Authors: Kaufmann Pierre , Scalise E.
Published: July 2016

(Solar Phys.). The emission of circularly polarized radiation of reversed senses from the respective solar hemispheres at λ = 4.3 cm is discussed, referring to consistent eclipse results obtained in November 1966 (Figure 1), March 1970, and January 1973 (Figure 2). Further qualitative information were obtained by performing a series of 18 daily solar maps (Figure 3) at the same wavelength, with moderate angular resolution (i.e., 12′). We were not able to resolve individual centers' polarities, but have confirmed that reversed senses of circular polarization occur, tending to be right-handed at southern areas of the solar disk, and left-handed at northern areas. These senses correspond to preceding polarities at the hemispheres for the 20th solar cycle, and a ‘neutral line’ divide the two polarized hemispheres, showing a contour that depends strongly on the presence of active centres and on their displacement with solar rotation. This suggest that the polarized features are strongly controlled, if not completely, by the presence of photospheric underlying magnetic areas.
Boundary Fitting Problems Associated with Coronal Magnetic Models
Authors: Schatten Kenneth H.
Published: July 2016

The calculation of coronal magnetic fields was first suggested by Gold (1958). Altschuler and Newkirk (1969) and Newkirk et al. (1968) used a Legendre polynomial fit to the photospheric observations of magnetic fields whereas Schatten (1968) with Wilcox and Ness (Schatten et al., 1969) use a magnetic monopole fit, first incorporated by Schmidt (1964).
Ground-Based Observations of Type III Bursts
Authors: Stewart R. T.
Published: July 2016

Observations over the past 20 yrs or so are reviewed, with emphasis on recent high spatial resolution observations. The results lend support to earlier ideas on the propagation of type III electron streams through coronal regions of weak magnetic field strength but have not as yet settled the question whether the electrons propagate along the axes of coronal streamers. Several important burst properties appear to be significantly affected by ray scattering on small-scale size density irregularities in the corona.
Synchrotron Radiation in Directions Close to Magnetic-Field Lines
Authors: Westfold K. C.
Published: July 2016

(Astrophys. Space Sci.). It is characteristic of the radiation from a particle of mass m bearing a charge e moving with ultrarelativistic velocity βc in a magnetic field of induction B0 that the bulk of the emission is confined to a small cone of directions within O(ξ) of the direction of motion τ which makes a constant angle α with B0, and that for any direction n at an angle θ with B0 such emission is observed as harmonics of the fundamental frequency fB0ξ/a, where fB0 is the nonrelativistic cyclotron frequency and
Shock Waves and the Ejection of Matter from the Sun: Radio Evidence
Authors: McLean D. J.
Published: July 2016

The passage of shock waves and ejected matter through the solar corona can produce type II and type IV radio bursts. This paper reviews the observations of these types of bursts and their interpretation, with particular emphasis on recent work.
Interplanetary Shock Waves from McMath Region 11976 During Its Passage in August 1972
Authors: Dryer M. , Eviatar A. , Frohlich A. , Jacobs A. , Joseph J. H. , Weber E. J.
Published: July 2016

(J. Geophys. Res.). The August 1972 events provided an excellent opportunity for synthesizing a variety of observations in a coordinated fashion for the purpose of improving flare-shock associations, and our understanding of interplanetary shock propagation and solar wind interaction with planets and comets. These observations included the usual sudden commencements of magnetic storms at Earth; preliminary shock data from Heos-2, Prognoz-1 and Prognoz-2 (at Earth) and the radially-aligned Pioneers 9 (0.77 AU) and 10 (2.2 AU) located about 45° east of the Sun–Earth axis; solar radio types II and IV (as reported in World Data Center A's UAG Report 28, 1973, and this Symposium); discrete radio source scintillations in the solar wind; and the more speculative ideas regarding the solar wind's interaction with planets and comets. In the last case, Jupiter and Comet P/Schwassmann-Wachmann I exhibited non-Io-associated radio emission and a brightness increase, respectively, as a possible result of shock waves from the flare and/or coronal ejection activity initiated on 1972 June 15. During the August events, Comet P/Giacobini-Zinner exhibited statistically-significant sudden brightness decrease following its perihelion on 1972 August 4 at 1 AU approximately 57° west of the Sun–Earth axis.
On the Theory of Moving Type IV Radio Bursts
Authors: Mangeney A.
Published: July 2016

(Astron. Astrophys.). In this paper it is shown that the Alfvén wave turbulence created behind a shock wave propagating along the ambiant magnetic field in a collision-less plasma, accelerates electrons of the high energy tail of the distribution up to mildly relativistic energies. The efficiency of the process depends upon the ratio of the acceleration time by the turbulence to the scattering time of the same turbulence. At high energies the accelerated particles have a power law spectrum, the steepness of which depends upon the turbulent energy.
The Gyro-Synchrotron Radiation from Moving Type IV Sources in the Solar Corona
Authors: Dulk G. A.
Published: July 2016

(Solar Phys.). Calculations of the gyro-synchrotron emission are made for conditions which might be expected in moving type IV sources in the solar corona. Two simple models for an evolving source are treated: a uniform cube and an inhomogeneous sphere. The results suggest that most moving sources have the following features: (1) A rather strong magnetic field, ≈ 10 G, is carried out within the source. This is required to achieve the high degree of circular polarization often observed. (2) Synchrotron self-absorption causes the source to be optically thick at frequencies less than about 100 MHz, thus restricting the bandwidth of the radiation. The self-absorption decreases as the source moves outward and expands. The turnover frequency, which separates the optically thick and thin spectral regimes, moves rapidly to lower frequencies, accompanied by a change from low to high circular polarization. In the case of an inhomogeneous source, the source appears to be larger at the lower frequencies. (3) Razin-Tsytovich suppression cannot be an important factor in determining the characteristics of most sources.
6. Magneto-hydrodynamic experiments
Authors: Lehnert B.
Published: July 2016

Comparisons are made between magneto-hydrodynamics on cosmical and on laboratory scale. Magneto-hydrodynamic waves, turbulence, the generation of magnetic fields and thermal convection are discussed and a review is given of earlier experimental investigations. The possibilities are examined of realizing cosmical phenomena of this type in the laboratory.
9. Waves in a hot ionized gas in a magnetic field
Authors: åström Ernst
Published: July 2016

The electromagnetic state of vacuum is characterized by two vector quantities, namely E and B. They are related to current and charge density by the equations

Sometimes it is suitable and possible to introduce two new quantities, H and D, so defined that the equations (1) and (2) appear in the new form (Strattonm)
and with a linear relation between E and D and also between B and H. This formalism is common when dealing with fluid and solid media, and has also been introduced to ionized media of zero temperature (Nichols and Schelleng[2], Alfven[3], p. 85, Astrom[4]). Here we shall say a few words about this matter for ionized media of non-zero temperature. In this connexion we also get an opportunity to discuss the meaning of the conception of diamagnetism.
10. Experimental study of plasmoids
Authors: Bostick Winston H.
Published: July 2016

A plasma source can be used to project ionized matter across a magnetic field. The configuration of plasma observed when an electromagnetic braking action is produced by the presence of low-pressure gas (about 1 μ) in the vacuum chamber provides an insight into the manner in which magnetic-field lines can be dragged and twisted. By firing several sources simultaneously, it is possible to simulate the production of spiral galaxies and barred spirals. The paper presented here forms an extension of earlier experiments performed by the author on plasmoids[1].
13. The processes in active regions on the sun and electromagnetics
Authors: Severny A. B.
Published: July 2016

1. Brief summary of the dynamics of flare development, based on the analysis of moving picture and spectroscopic data. Some new spectroscopic data on the fine structure of emission in active regions, evidencing the peculiar character of motions in them: outbursts of corpuscules, ascending grains of continuous emission, explosive processes and shock-waves.

2. Summary of the observational data on the motions in prominences. Regular electromagnetic and turbulent motions, ‘explosive’ motions and their admissible interpretation. Some data on the coronal forms above active regions and on the possible role of hydromagnetics in their formation.

3. Some remarks on the role of hydromagnetics, admissible, from the observational aspect.
17. Some considerations on thermal conduction and magnetic fields in prominences
Authors: Rosseland S. , Jensen E. , Tandberg-Hanssen E.
Published: July 2016

Prominences which extend into the million degree temperature region of the corona will, in the absence of magnetic fields, be heated up to temperatures of the same order of magnitude in the course of at most a few hours. A magnetic field of reasonable magnitude inside the prominence, will, however, be sufficient to cut down thermal conduction and turbulence to such an extent that the long life of some prominences seems understandable.
20. Theoretical problems of stellar magnetism
Authors: Spitzer Lyman
Published: July 2016

Relatively complete summaries of recent theoretical work in the field of stellar magnetism have been given by Cowling[1] and Elsasser[2, 3, 4]. For this reason the present survey does not aim at completeness, but is devoted instead to the following three outstanding problems in the field: (1) the formation of stars in the presence of an interstellar magnetic field; (2) the influence of convection currents on a stellar magnetic field; (3) the nature of magnetic variable stars. Study of these problems illustrates the type of difficulties encountered in theories of stellar magnetism.
21. On the magnetic fields in interstellar space and in nebulae
Authors: Shajn G. A.
Published: July 2016

Some aspects of the problem of magnetic fields in the interstellar space and in the nebulae are discussed in this paper. Our observational basis are the numerous photographs of the nebulae in Hα and other rays, taken with high-speed 450 and 640 mm cameras.

The greatly elongated shape of many emission nebulae is interpreted as a result of three factors, the effect of the magnetic field, the macroscopic motions in these nebulae (including the tendency to expand) and the high electrical conductivity of matter. The expansion of nebulae is to be generally accompanied by the considerable decrease in brightness (roughly about d–5), but if the expansion is only in one direction, owing to the presence of a regular magnetic field, the brightness decreases much more slowly (roughly about d–2) and the nebulae remain visible for a longer time. The filamentary structure, which is very often inherent to the elongated nebulae, is, probably, an additional factor of a longer visibility of the nebulae under consideration. The great lengthening of nebulae may be reached in the period of the order of 106 years.

In the dark nebulae the matter seems to be electrically conductive and the macroscopic motions of the order of 1–2 km/sec are present there, so that there are reasons to suggest that the magnetic field is also responsible for the elongated shape of many dark nebulae. One may prove that the observed elongated shape of dark and emission nebulae could not be caused by differential galactic rotation.
27. On meridional circulations in stellar convective zones
Authors: Biermann L.
Published: July 2016

It is shown in outline by a discussion of the equation of motion in all its components and by taking regard of the geometrical properties of turbulent exchange, that in general the state of pure rotation (without meridional circulations) is not a possible stationary state of motion for convective zones of stars.
46. The störmertron
Authors: Bennett Willard H.
Published: July 2016

A tube has been developed in which the shapes of streams of charged particles moving in the earth's magnetic field can be produced accurately to scale. The tube has been named the Störmertron in honor of Carl Störmer who calculated many such orbits. New developments which have made this tube possible include a method for coating the inside of large glass tubes with a transparent electrically conducting film, and an electron gun producing gas-focused streams in less than ½ micron of mercury vapor, a nearly vapor-free grease joint, and a nearly vapor-free carbon black. The magnetic dipole field of the earth is simulated with an Alnico magnet capped with properly shaped soft iron caps. The stream is deflected using two pairs of yoke coils near the gun.
51. Theory of isotropic magnetic turbulence in gases
Authors: Kaplan S. A.
Published: July 2016

A system of spectral equations of magnetic turbulence in gases differing from that given by Chandrasekhar is suggested. The solution of this system is examined. Correlation and structure functions of the turbulence of interstellar gases, determined according to the data on radial velocities of interstellar clouds from Adams's catalogue, are given. For motions of a scale less than the fundamental one (l less than 80 pc) the spectral function F(k) is about k–1·71, which agrees with the theoretical conclusions.
Adaptive Two-stage Kalman Filter for SINS/Odometer Integrated Navigation Systems
Authors: Zhao Hongsong , Miao Lingjuan , Shao Haijun
Published: July 2016

In Strapdown Inertial Navigation System (SINS)/Odometer (OD) integrated navigation systems, OD scale factor errors change with roadways and vehicle loads. In addition, the random noises of gyros and accelerometers tend to vary with time. These factors may cause the Kalman filter to be degraded or even diverge. To address this problem and reduce the computation load, an Adaptive Two-stage Kalman Filter (ATKF) for SINS/OD integrated navigation systems is proposed. In the Two-stage Kalman Filter (TKF), only the innovation in the bias estimator is a white noise sequence with zero-mean while the innovation in the bias-free estimator is not zero-mean. Based on this fact, a novel algorithm for computing adaptive factors is presented. The proposed ATKF is evaluated in a SINS/OD integrated navigation system, and the simulation results show that it is effective in estimating the change of the OD scale factor error and robust to the varying process noises. A real experiment is carried out to further validate the performance of the proposed algorithm.
Rabies outbreak in Greece during 2012–2014: use of Geographical Information System for analysis, risk assessment and control
Authors: GIANNAKOPOULOS A. , VALIAKOS G. , PAPASPYROPOULOS K. , DOUGAS G. , KOROU L. M. , TASIOUDI K. E. , FTHENAKIS G. C. , HUTCHINGS M. R. , KAIMARAS D. , TSOKANA C. N. , ILIADOU P. , SPYROU V. , TZANI M. , BIRTSAS P. , KOSTOGLOU P. , SOKOS C. , DOUDOUNAKIS S. , YON L. , HANNANT D. , ARTOIS M. , TSIODRAS S. , HADJICHRISTODOULOU C. , BILLINIS C.
Published: July 2016

The objectives of this work were (i) geographical analysis of the 2012–2014 outbreak of rabies in Greece using GIS and (ii) comparative analysis of animal cases with data of potential human exposure to rabies together with environmental data, in order to provide information for risk assessment, effective monitoring and control. Most animal cases (40/48) involved red foxes, while domestic animals were also diagnosed with rabies. Overall, 80% of the cases were diagnosed in central northern Greece; 75% of the cases were diagnosed in low altitudes (<343·5 m), within a distance of 1 km from human settlements. Median distance from livestock farms was 201·25 m. Most people potentially exposed to rabies (889/1060) presented with dog bite injuries. Maximum entropy analysis revealed that distance from farms contributed the highest percentage in defining environmental niche profiles for rabid foxes. Oral vaccination programmes were implemented in 24 administrative units of the country during 2013 and 2014, covering a total surface area of ~60 000 km2. Rabies re-occurrence in Greece emphasizes the need for ongoing surveillance in cross-border areas and in areas with intense human activity.
University of Saskatchewan Radiocarbon Dates II
Authors: McCallum K. J. , Dyck W.
Published: July 2016

This paper is a list of radiocarbon dates obtained at the University of Saskatchewan since the last report was issued (McCallum, 1955). The method used is essentially that of Suess (1954), in which the sample is counted as acetylene gas. The proportional counter has a sensitive volume of one liter and is filled with acetylene to a pressure of one atmosphere. Each sample is counted for at least two 20-hour periods. The modern standards used were obtained from softwood logs grown in Northern Saskatchewan and were either 50 or 100 years old as obtained from ring counts.
Uppsala Natural Radiocarbon Measurements II
Authors: Olsson Ingrid
Published: July 2016

The following list covers the samples measured at the Uppsala radiocarbon laboratory during 1959.
U. S. Geological Survey Radiocarbon Dates V
Authors: Rubin Meyer , Alexander Corrinne
Published: July 2016

The dates listed herein have been determined at the U. S. Geological Survey radiocarbon laboratory at Washington since our last date list (USGS IV) and up to the end of 1959. Acetylene continues to be the gas of our choice. Each sample is run for a period of two days in two separate counters with separate electronics. The modern standard used is wood grown in the 19th century, and the ages and errors have been computed in the same manner as before. Pretreatment of wood, charcoal, and peat samples by boiling in acid, alkali, and acid again, is standard procedure.
The Genetic and Environmental Association Between Parental Monitoring and Risk of Cannabis, Stimulants, and Cocaine Initiation in a Sample of Male Twins: Does Parenting Matter?
Authors: Olivares Emily L. , Kendler Kenneth S. , Neale Michael C. , Gillespie Nathan A.
Published: July 2016

Our aim was to test the direction of causation between self-report parental monitoring (PM) and the liability to illicit drug initiation (DI) as indicated by cannabis, cocaine, and stimulants. We fitted a multiple indicator model to test causal and non-causal models based on a large, genetically informative cross-sectional sample of male twins. The sample comprised 1,778 males aged 24–62 years from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders. Data came from self-report measures of lifetime cannabis, stimulants, and cocaine initiation, and retrospective assessment of PM between ages 8–17 years. Multivariate modeling showed that familial aggregation in PM and DI were both explained by a combination of additive genetic and shared environmental effects. Moreover, the significant association between PM and DI was best explained by a correlated liability model versus causal models. PM has typically been assumed to be an environmental, causal risk factor for drug use and has been shown to be among the more salient environmental risk factors for illicit DI. Our data were not consistent with this causal hypothesis. Instead, a correlated liability model in which PM and risk of DI share common genetic and environmental risks provided a better fit to the data.
Regulation of post-Golgi LH3 trafficking is essential for collagen homeostasis
Authors: Banushi Blerida , Forneris Federico , Straatman-Iwanowska Anna , Strange Adam , Lyne Anne-Marie , Rogerson Clare , Burden Jemima J. , Heywood Wendy E. , Hanley Joanna , Doykov Ivan , Straatman Kornelis R. , Smith Holly , Bem Danai , Kriston-Vizi Janos , Ariceta Gema , Risteli Maija , Wang Chunguang , Ardill Rosalyn E. , Zaniew Marcin , Latka-Grot Julita , Waddington Simon N. , Howe S. J. , Ferraro Francesco , Gjinovci Asllan , Lawrence Scott , Marsh Mark , Girolami Mark , Bozec Laurent , Mills Kevin , Gissen Paul
Published: July 2016

Post-translational modifications are necessary for collagen precursor molecules (procollagens) to acquire final shape and function. However, the mechanism and contribution of collagen modifications that occur outside the endoplasmic reticulum and Golgi are not understood. We discovered that VIPAR, with its partner proteins, regulate sorting of lysyl hydroxylase 3 (LH3, also known as PLOD3) into newly identified post-Golgi collagen IV carriers and that VIPAR-dependent sorting is essential for modification of lysines in multiple collagen types. Identification of structural and functional collagen abnormalities in cells and tissues from patients and murine models of the autosomal recessive multisystem disorder Arthrogryposis, Renal dysfunction and Cholestasis syndrome caused by VIPAR and VPS33B deficiencies confirmed our findings. Thus, regulation of post-Golgi LH3 trafficking is essential for collagen homeostasis and for the development and function of multiple organs and tissues.
Zero-bias photocurrent in ferromagnetic topological insulator
Authors: Ogawa N. , Yoshimi R. , Yasuda K. , Tsukazaki A. , Kawasaki M. , Tokura Y.
Published: July 2016

Magnetic interactions in topological insulators cause essential modifications in the originally mass-less surface states. They offer a mass gap at the Dirac point and/or largely deform the energy dispersion, providing a new path towards exotic physics and applications to realize dissipation-less electronics. The nonequilibrium electron dynamics at these modified Dirac states unveil additional functions, such as highly efficient photon to spin-current conversion. Here we demonstrate the generation of large zero-bias photocurrent in magnetic topological insulator thin films on mid-infrared photoexcitation, pointing to the controllable band asymmetry in the momentum space. The photocurrent spectra with a maximal response to the intra-Dirac-band excitations can be a sensitive measure for the correlation between Dirac electrons and magnetic moments.
Correction: Corrigendum: Highly Efficient and Scalable Separation of Semiconducting Carbon Nanotubes via Weak Field Centrifugation
Authors: Reis Wieland G. , Weitz R. Thomas , Kettner Michel , Kraus Alexander , Schwab Matthias Georg , Tomović Željko , Krupke Ralph , Mikhael Jules
Published: July 2016

Scientific Reports 6: Article number: 26259; published online: 18 May 2016; updated: 20 July 2016 In this Article, there are typographical errors in Figure 1b. In test tube 2, ‘pH 1.8’ is incorrectly given as ‘pH 7.0’. The correct Figure 1 appears below.
Historical rise of waterpower initiated the collapse of salmon stocks
Authors: Lenders H. J. R. , Chamuleau T. P. M. , Hendriks A. J. , Lauwerier R. C. G. M. , Leuven R. S. E. W. , Verberk W. C. E. P.
Published: July 2016

The collapse of Atlantic salmon (Salmo salar) stocks throughout North-Western Europe is generally ascribed to large-scale river regulation, water pollution and over-fishing in the 19thand 20thcentury. However, other causes have rarely been quantified, especially those acting before the 19thcentury. By analysing historical fishery, market and tax statistics, independently confirmed by archaeozoological records, we demonstrate that populations declined by up to 90% during the transitional period between the Early Middle Ages (c. 450–900 AD) and Early Modern Times (c. 1600 AD). These dramatic declines coincided with improvements in watermill technology and their geographical expansion across Europe. Our extrapolations suggest that historical Atlantic salmon runs must have once been very abundant indeed. The historical perspective presented here contributes to a better understanding of the primary factors that led to major declines in salmon populations. Such understanding provides an essential basis for the effective ecological rehabilitation of freshwater ecosystems.
The bacterial DNA repair protein Mfd confers resistance to the host nitrogen immune response
Authors: Guillemet Elisabeth , Leréec Alain , Tran Seav-Ly , Royer Corinne , Barbosa Isabelle , Sansonetti Philippe , Lereclus Didier , Ramarao Nalini
Published: July 2016

Production of reactive nitrogen species (NO) is a key step in the immune response following infections. NO induces lesions to bacterial DNA, thus limiting bacterial growth within hosts. Using two pathogenic bacteria, Bacillus cereus and Shigella flexneri, we show that the DNA-repair protein Mfd (Mutation-Frequency-Decline) is required for bacterial resistance to the host-NO-response. In both species, a mutant deficient for mfd does not survive to NO, produced in vitro or by phagocytic cells. In vivo, the ∆mfd mutant is avirulent and unable to survive the NO-stress. Moreover, NO induces DNA-double-strand-breaks and point mutations in the Δmfd mutant. In overall, these observations demonstrate that NO damages bacterial DNA and that Mfd is required to maintain bacterial genomic integrity. This unexpected discovery reveals that Mfd, a typical housekeeping gene, turns out to be a true virulence factor allowing survival and growth of the pathogen in its host, due to its capacity to protect the bacterium against NO, a key molecule of the innate immune defense. As Mfd is widely conserved in the bacterial kingdom, these data highlight a mechanism that may be used by a large spectrum of bacteria to overcome the host immune response and especially the mutagenic properties of NO.
Anomalous behaviors of Wyrtki Jets in the equatorial Indian Ocean during 2013
Authors: Duan Yongliang , Liu Lin , Han Guoqing , Liu Hongwei , Yu Weidong , Yang Guang , Wang Huiwu , Wang Haiyuan , Liu Yanliang , Zahid  , Waheed Hussain
Published: July 2016

In-situ measurement of the upper ocean velocity discloses significant abnormal behaviors of two Wyrtki Jets (WJs) respectively in boreal spring and fall, over the tropical Indian Ocean in 2013. The two WJs both occurred within upper 130 m depth and persisted more than one month. The exceptional spring jet in May was unusually stronger than its counterpart in fall, which is clearly against the previous understanding. Furthermore, the fall WJ in 2013 unexpectedly peaked in December, one month later than its climatology. Data analysis and numerical experiments illustrate that the anomalous changes in the equatorial zonal wind, associated with the strong intra-seasonal oscillation events, are most likely the primary reason for such anomalous WJs activities.