bluuebunny/crossref_metadata_2025 huggingface dataset:
Americanization Now and Then: The “Nation of Immigrants” in the Early Twentieth and Twenty-First Centuries
Authors: LAURET MARIA
Published: March 2016

Whereas in 1915 Theodore Roosevelt could proclaim with great conviction that there was no room in the United States for hyphenated Americans, today it is common for Americans to identify precisely as hyphenated Americans, proud of their ethnic heritage. And whilst in 2015 the debate on undocumented immigration is perceived to have reached crisis point, the US continues to project itself as a “nation of immigrants.” These reversals and contradictions in American political discourse are scrutinized here in a historical survey of the Americanization movement of a hundred years ago and the concept of the “nation of immigrants” that originated with John F. Kennedy in the Cold War sixty years later. In the analysis of primary and key historiographical sources on twentieth-century American immigration, a change from ethnic shame to ethnic pride is tracked down, revealing both the long-term effects of Americanization as a programme of social engineering and the ongoing ideological work that the “nation of immigrants” slogan performs for American national identity.
Electronic Documentation of Central Venous Catheter—Days: Validation Is Essential
Authors: Tejedor Sheri Chernetsky , Garrett Gina , Jacob Jesse T. , Meyer Ellen , Reyes Mary Dent , Robichaux Chad , Steinberg James P.
Published: March 2016

Background.

Measurement of central line-associated bloodstream infection (CLABSI) rates outside of intensive care units is challenged by the difficulty in reliably determining central venous catheter (CVC) use. The National Healthcare Safety Network (NHSN) allows for use of electronic data for determination of CVC-days, but validation of electronic data has not been studied systematically.

Objective.

To design and validate a process to reliably measure CVC-days outside of the intensive care units that leverages electronic documentation.

Methods.

Thirty-four inpatient wards at 2 academic hospitals using a common electronic platform for nursing documentation were studied. Electronic queries were created to capture patient and CVC information, and tools and processes for tracking and reporting errors in documentation were developed. Strategies to validate electronic data included comparisons with manual CVC-day determinations and automated data validation using customized tools. Interventions included redesign of documentation interface, real-time audit with feedback of errors, and education. The primary outcome was patient-level total error rate in electronic CVC-day measurement compared with manually counted CVC-days.

Results.

At baseline, there were a mean (± standard deviation) of 0.32 ± 0.25 electronic CVC-day errors (omission and commission errors summed and counted equally) per manually counted CVC-day. After several process improvement cycles over 7 months, the error rate decreased to <0.05 errors per CVC-day and remained at or below this level for 2 years.

Conclusions.

Baseline electronic CVC-day counts had a high error rate. Stepwise interventions reduced errors to consistently low levels. Validation of electronic calculation of CVC-days is essential to ensure accuracy, particularly if these data will be used for interinstitutional comparison.
Activity of Commonly Used Antimicrobial Prophylaxis Regimens against Pathogens Causing Coronary Artery Bypass Graft and Arthroplasty Surgical Site Infections in the United States, 2006–2009
Authors: Berríos-Torres Sandra I. , Yi Sarah H. , Bratzler Dale W. , Ma Allen , Mu Yi , Zhu Liping , Jernigan John A.
Published: March 2016

Background.

Coronary artery bypass graft (CABG) and primary arthroplasty surgical site infection (SSI) rates are declining slower than other healthcare-associated infection rates. We examined antimicrobial prophylaxis (AMP) regimens used for these operations and compared their spectrum of activity against reported SSI pathogens.

Methods.

Pathogen distributions of CABG and hip/knee arthroplasty complex SSIs (deep and organ/space) reported to the National Healthcare Safety Network (NHSN) from 2006 through 2009 and AMP regimens (same procedures and time period) reported to the Surgical Care Improvement Project (SCIP) were analyzed. Regimens were categorized as standard (cefazolin or cefuroxime),β-lactam allergy (vancomycin or clindamycin with or without an aminoglycoside), and extended spectrum (vancomycin and/or an aminoglycoside with cefazolin or cefuroxime). AMP activity of each regimen was predicted on the basis of pathogen susceptibility reports and published spectra of antimicrobial activity.

Results.

There were 6,263 CABG and arthroplasty complex SSIs reported (680,489 procedures; 880 NHSN hospitals). Among 6,574 pathogens reported, methicillin-sensitiveStaphylococcus aureus(23%), methicillin-resistantS. aureus(18%), coagulase-negative staphylococci (17%), andEnterococcusspecies (7%) were most common. AMP regimens for 2,435,703 CABG and arthroplasty procedures from 3,330 SCIP hospitals were analyzed. The proportion of pathogens predictably susceptible to standard (used in 75% of procedures),β-lactam (12%), and extended-spectrum (8%) regimens was 41%–45%, 47%–96%, and 81%—96%, respectively.

Conclusion.

Standard AMP, used in three-quarters of CABG and primary arthroplasty procedures, has inadequate activity against more than half of SSI pathogens reported. Alternative strategies may be needed to prevent SSIs caused by pathogens resistant to standard AMP regimens.
Fruit and vegetable intake of US adults estimated by two methods: What We Eat In America, National Health and Nutrition Examination Survey 2009–2012
Authors: Hoy M Katherine , Goldman Joseph D , Sebastian Rhonda S
Published: March 2016

Objective

Estimates of fruit and vegetable (FV) consumption vary depending on intake definition, which may be determined by research purpose. Researchers have used two methods to evaluate intake: epidemiological and behavioural. The present study describes FV intake by adults using epidemiologicalv. behavioural approaches.

Design

One-day dietary intake data from What We Eat In America, National Health and Nutrition Examination Survey 2009–2012 were used. Sample weights were used to produce nationally representative estimates. FV intake (in cup-equivalents (CE)) was estimated using the Food Patterns Equivalents Database. The epidemiological method considered all FV after disaggregating foods and beverages. The behavioural method included foods that provided at least 0·2 CE FV per 100 g, and excluded sources high in fat, added sugar and Na.

Setting

Nationally representative survey of the US population.

Subjects

Adults (n10 563) aged ≥20 years.

Results

For epidemiologicalv. behavioural, fruit intake was 1·1v. 1·0 CE for males and 1·0v. 0·9 CE for females. Vegetable intake was 1·8v. 1·1 CE for males and 1·5v. 1·0 CE for females.

Conclusions

The definition of FV intake affects estimates of consumption by the population and is an important consideration when planning and comparing research studies. The method used should align with research goals to assure accurate interpretation and validity of results.
Abundance of Helium in Stellar Atmospheres
Authors: Cayrel R.
Published: March 2016

Helium abundance in stellar atmospheres has been the subject of several recent investigations, essentially induced by progresses in the computation of non-grey model atmospheres (including line blanketing in the far U.V.), by considerable advances in the theory of Stark broadening of helium lines, by non local thermodynamic equilibrium (LTE) work for the helium spectrum and more fundamentally by the intrinsic importance of the helium over hydrogen ratio in cosmological theories.
Oh as a Constituent of the Interstellar Medium
Authors: Turner B. E.
Published: March 2016

OH is at present the most ubiquitous molecule known in the interstellar medium. It is primarily associated with galactic continuum sources, both thermal and nonthermal. The fraction of all sources showing OH decreases monotonically with galactic longitude away from the Galactic Center region. However, neither the projected density of OH nor the abundance relative to hydrogen or other molecules seems to depend on location within the galactic plane. OH also occurs in many dark dust clouds, where its density is typically 10−5—10−4 cm−3 and its abundance relative to hydrogen is very high. OH is not found in the heavily reddened stellar clusters of Reddish, in Wolf Rayet stars, in planetary nebulae, or in globules. Recent surveys have indicated that OH both in emission and in absorption, is highly correlated with H2CO in direction and in velocity. OH emission, but not absorption, is also highly correlated with anomalous H2O emission. These relationships are important in deciding between various processes for interstellar molecule formation. On present information, it appears that more than one such process is operative in different regions of the interstellar medium.
The Relative Density of H, OH and H2CO in Interstellar Clouds
Authors: Davies R. D.
Published: March 2016

I have attempted to obtain an answer to the question “In which gas (neutral hydrogen) clouds do we find molecules?” By limiting the investigation to those clouds which might be considered normal (i.e. specifically excluding the class of clouds which emit by maser action) it is possible to obtain a definitive answer to the question namely, those clouds which have the highest gas concentration. Further data on the correlation between the distribution of neutral hydrogen and of different molecules can be found.

The clouds which are seen in absorption against background radio sources are most ideally suited for this purpose and I have used the absorption spectra of neutral hydrogen (21 cm wavelength), of the OH radical (18 cm, the 1667 MHz line) and the formaldehyde molecule (6 cm). Only the absorption spectra of the three strongest non-thermal sources (Cas A, Cyg A, and Tau A) were used because only these have unambiguous neutral hydrogen absorption spectra and also because they, unlike the HII regions, do not have 1667 MHz OH spectra which may be confused by anomalous emission. In the absorption spectra of these three sources individual clouds at specific velocities can be recognized on the H, OH and H2CO spectra. We can then investigate the OH and H2CO content of each cloud relative to its neutral hydrogen content.
Molecule Formation on Grain Surfaces
Authors: Salpeter E. E.
Published: March 2016

I will discuss the formation of molecules AB from two atoms or radicals A and B only for cases where the reaction A + B → AB is exothermic. The efficiency of this reaction on the surface of an interstellar dust grain is the product of two factors: (i) the ‘sticking coefficient’ or probability that the first radical hitting the grain surface from the interstellar gas becomes thermalized and sticks to an adsorption site; (ii) the recombination efficiency or probability that the first adsorbed radical will remain adsorbed, rather than evaporating, during the time required for the second radical to hit the grain, be adsorbed and find its partner.
Final Remarks
Authors: Greenstein J. L.
Published: March 2016

It would be very ungracious not to say a few words about this remarkable set of presentations, even though it would be cruel to the audience to try to review them at this late hour. I made sixteen pages of summary notes of the highlights. We have heard about enormous improvements in our knowledge of the behavior of complex molecules in space. May I remind you that the computations of chemical equilibrium presented by Professor Klemperer covered largely the diatomic molecules known many years ago. The radio astronomers, with incredible technical proficiency, have found many polyatomic molecules with molecular weights close to a hundred; in a solid particle that causes continuous absorption we must reach weights near 108.
Atomic Data of Importance for Ultra-Violet and X-Ray Astronomy: A Review of Theory
Authors: Seaton M. J.
Published: March 2016

In the present review I will discuss certain rather general aspects of the theory, and will leave it to other speakers to describe the results of detailed calculations. Further references to recent work are given in the Report of IAU Commission 14.

1. Atomic Wave Functions and Energy Levels

In order to calculate data of importance for ultra-violet and X-ray astronomy - wavelengths, transition probabilities, collision cross-sections, ionization and recombination rates, and line-broadening parameters - it is necessary to begin with the calculation of atomic wave functions. The interest is mainly in highly ionized systems.
New Results on Electron Broadening of Some UV Lines of NII, CII/IV and SiII/III/IV
Authors: Sahal-Brechot S. , Segre E.
Published: March 2016

The electron damping constants of some UV lines of astrophysical interest are calculated within the impact and semiclassical approximations and are compared with experimental results where these are available (NII, UV(1) and CII, UV (1)).
Absolute Magnitudes of RR Lyrae Stars
Authors: Christy Robert F.
Published: March 2016

In discussing the absolute magnitudes of RR Lyrae stars, I concur in the importance of the question but I would, at the outset, like to insert a word of caution: It seems to me most likely that the Mb of RR Lyrae stars is not an immutable constant but depends on the original composition of the star. I will come back to this point later.

The principal point of view which I shall emphasize is rather different from that of most observers. The observer is usually interested in using the RR Lyrae stars as a means to calibrate distances and thereby looks out from the star to the Galaxy and then to the Cosmos. In contrast, the interests of the theorist look inward and he views the RR Lyrae stars as convenient fixed points for the comparison of theory with observation.

At present, the theory of stellar structure is tied to fitting the Sun. We all know the difficulties in the solar neutrino experiment which casts some doubt on whether we even understand the Sun. But we have few if any cases of evolved stars where we know M, L, R, to check our stellar evolution calculations.

We are now in desperate need of new fixed points where we can compare observation and the theory of stellar structure and evolution. The RR Lyrae or Cepheid type variables provide excellent examples for this comparison of observation and calculation. They are in late stages of evolution where tests are needed, they are readily identifiable, and well observed, and already the knowledge of the period provides a very precise mass-radius relationship so that a complete determination of the model will be provided by only a few additional measures.
Review of Observational Data on RR Lyrae Stars
Authors: van Herk G.
Published: March 2016

The data on which my work on the secular parallaxes of RR Lyrae stars is based (Bull. Astron. Inst. Neth.18) were in many respects so incomplete that I have tried to interest astronomers to get a more complete set of data. The number of stars for which I had a proper motion was only 168, and for which a radial velocity was known, was 180, with an overlap of only 138 stars. The accuracy of the proper motions was certainly unsatisfactory for 43% of the total. The greatest trouble in dealing with such insufficient numbers arises when one wants to subdivide the material into groups which are homogeneous from a physical point of view. Many subdivisions, in making up my paper, were not tried at all, simply because the material was inadequate.

In recent years plenty of work has been done by various investigators, of which I will at this point only mention the work on proper motions done at the Leander McCormick Observatory, and the great number of radial velocities determined by Dr. Clube and his associates. I do not, however, believe we are yet in a position to consider the whole subject as finished. Discussions about space motions, as given by Professor Oort in the book Stellar Structures, Volume V, will, at this time, be hardly improved upon. I still feel we should increase the number of stars substantially in order to get a better statistical discussion possible. This means we have to go to fainter stars. Plenty of these stars will be found on the plates which have served to make the Charts of the Carte du Ciel, which means we have at least one old position available for proper motions. At Leiden we are now engaged in the determination or redetermination of the proper motions of 430 RR Lyrae stars.
The Cosmic X-Ray Background
Authors: Weymann R. J.
Published: March 2016

Evidence for a diffuse, isotropic non-terrestrial component of X-ray radiation has been accumulating since the very beginnings of X-ray astronomy. This evidence now seems secure beyond reasonable doubt, especially in the light of recent experiments, e.g. one in which a very clean separation from the cosmic ray and terrestrial background has been achieved (Pounds, 1967), and another in which a counting rate proportional to the solid angle of the sky subtended to three different detectors was found (Matsuoka et al., 1967).

In this very brief review I wish simply to discuss the current ideas on the mechanisms for the production of the background and the extent to which the present observations can discriminate between them and to consider the information obtainable from the very soft X-ray region, which so far has been relatively little exploited.
Lithium Observations in the Sun
Authors: Müller Edith A.
Published: March 2016

The determination of the lithium abundance in the solar atmosphere is essentially based on the LiI resonance doublet at λ 6707·761 and 6707·912 Å. These two lines form a very faint absorption feature, the central depth of the stronger component being of the order of 1% of the continuum. The violet component, which is also the stronger of the two, occurs near the red wing of a faint solar line of unknown origin, and the lines appear to be blended with other faint lines including possibly the doublet of the Li6 isotope (the isotopic shift being 0·160 Å). No other line of LiI has been detected in the Fraunhofer spectum of the undisturbed solar disk. This is nothing surprising, because practically all lithium is expected to be ionized in the photosphere on account of its low ionization potential (Xion = 5·37 e.v.). In sunspot spectra the lower temperature reduces the degree of ionization of lithium and causes a strengthening of the LiI lines. In fact, the LiI resonance lines which appear as a very faint absorption feature on disk spectra are about 50 times stronger in spot spectra. Furthermore, the very weak feature at λ 6103·6 Å was identified by Dubov (1964) and by Schmahl and Schröter (1965) as due to the 2s 2S–3d 2D transition of LiI. Both the resonance doublet and the faint feature at 6103·6 Å have been used by the above-mentioned authors to derive the lithium abundance in spots.
What can We Learn from Li and Be Stellar Observations?
Authors: Reeves H.
Published: March 2016

I want to state a few questions which are raised by the observations of stellar Li and Be, and to see how far we can go in giving answers.

I do not believe that we can, at the present time, give very definite answers to most of these questions and build up a unique model in which all observations are properly understood. We are still faced with different possibilities which can not be excluded, but can only be classified according to their degree of ‘plausibility’. Although we are led to choose one of these possibilities in the light of present data, it seems wise to keep the other possibilities in the back of our mind, and to assess their merit. Considering this, a few alternate models will be described and discussed.
Recent Work on Fundamental Astrometry in the U.S.S.R.
Authors: Zverev M. S.
Published: March 2016

Absolute determinations of star positions using transit and vertical circles according to the methods developed at Pulkovo are being made at Pulkovo, at Nikolaiev, at the Golossejevo Observatory of the Ukraine Academy of Sciences, and at Santiago de Chile. At this latter observatory Soviet and Chilean astronomers have completed a series of observations of both bright and faint fundamental stars with a photographic vertical circle, and these observations are now being reduced at Pulkovo. Absolute determinations of right ascension will be made at the Cerro Calan Observatory using a large transit instrument recently constructed at Pulkovo. Further details of some of the Southern observations are given in the following paper to be presented by Dr. Anguita.
Presentation and Interpretation of High Resolution Infrared Spectra of Late-Type Stars
Authors: Thompson R. I.
Published: March 2016

Current interest in stellar evolution is concentrated on the life of a star after it has left the main sequence. Of particular interest are the red giant or supergiant periods during the hydrogen and helium shell burning phases. Convective mixing during these stages can mix nuclear processed material to the surface where it may be viewed by spectroscopic methods. It is imperative that this rare chance to view processed material be exploited fully to increase our knowledge of stellar evolution.

The observation and interpretation of cool star spectra has its own particular set of problems and advantages. A particular difficulty is the formation of molecules at the low temperatures which occur in the atmospheres of late stars. Not only must the particularly complex spectra of molecules be dealt with but the problem of chemical equilibrium in the atmosphere must be solved accurately before quantitative analysis may be performed. The formation of molecules, however, has one advantage in that it very dramatically separates those stars with carbon to oxygen ratios greater than one from those with ratios less than one. It is the very high dissociation energy of 11.1 eV for the CO molecule which performs this separation. If carbon is less abundant than oxygen all of the carbon is tied up in CO and only oxides are formed in the stellar atmosphere which produce typical M star spectra. If, however, carbon is more abundant than oxygen then carbon compounds such as C2 are formed in place of the oxides and a carbon star spectrum is formed. One of the great advantages of infrared stellar spectra is that it is the only ground based technique for observing CO in stellar atmospheres.
The Movement of Small Particulate Matter in the Early Solar System and the Formation of Satellites
Authors: Gold T.
Published: March 2016

Satellites are a common feature in the solar system, and all planets on which satellite orbits would be stable possess them. (For Mercury the solar perturbation is too large, and the retrograde spin of Venus would cause satellites to spiral in to the planet through tidal friction.) An explanation of the formation of satellites must hence be one which makes the phenomenon exceedingly probable at some stage in the solar system formation processes, and very improbable processes like a capture cannot be the answer in most cases.

Small particulate matter must have been very abundant in the early solar nebula. Such particulate matter must have existed both from the first condensation of the low vapor pressure components of the gas in the first round, and it must also have been composed of material scattered from impacts after some major bodies had begun to form, frequently finding themselves no doubt on collision orbits.
On the Physical Model of Supernovae Close to Light Maximum
Authors: Mustel E. R.
Published: March 2016

One of the principal sources of information about supernovae are the spectra of these stars. Thus we are going to discuss mainly the spectra of type I and type II supernovae around light maximum (tmax).
Globular Cluster X-Ray Sources
Authors: Grindlay Jonathan E.
Published: March 2016

The discoveries of both steady and bursting X-ray sources in globular clusters have made them as interesting for high energy astrophysics and X-ray astronomy as they were for unlocking galactic structure in Shapley’ s day. Globular clusters are massive (˜ 105M⊙) spherical clusters of primarily low mass (⋞0.8 M⊙) evolved stars and may be the oldest systems in the Galaxy. Thus when several globular clusters were tentatively identified as containing X-ray sources (Giacconiet al. 1974), it was apparent that either dynamical or evolutionary processes must be occurring among the ancient stars in globular clusters to produce the relatively short-lived X-ray sources. The existence of these X-ray sources has prompted considerable discussion as to their origin, since they exist with ˜100 times the probability per unit mass in globular clusters as in the Galaxy as a whole (Katz 1975; Clark 1975). They may be yet another example of X-ray binaries (e. g., Clark 1975; Fabianet al. 1975) or be due to accretion onto a single collapsed object (black hole) at the center of the cluster (Bahcall and Ostrlker 1975; Silk and Arons 1975). At present both of these classes of models are possible and generally consistent with the data, though each has its particular difficulties. We shall review the observational data and then the models in an effort to point out the present balance of evidence for the binaryvs.black hole models as well as the most promising directions for future work. Given the possibly high incidence of X-ray bursters in globular clusters, our discussion will refer to both observations and recent models for bursters. While this review will primarily address the X-ray sources in globular clusters, it is obvious that their eventual understanding will contribute much to studies of globular clusters in general and will prompt future studies in particular areas.
X-Ray Bursts of Nuclear Origin?
Authors: Maraschi L. , Cavaliere A.
Published: March 2016

The fate of nuclear energy carried by matter accreted onto a neutron star was considered e.g. by Rosenbluth et al. (1973). They examined pycnonuclear reactions on an originally cold star, and found that the whole star is thereby heated up to 106−107 °K. The thermonuclear reactions that can be ignited then, have been studied by Hansen and Van Horn (1975), who computed stationary burning shells, finding, however, that in most cases the shells are thermally unstable.

We consider here the possibility that X-ray bursts are due to instabilities of this type. The observational constraints fix the parameters uniquely.
Studies of a and F Stars in the Region of the North Galactic Pole
Authors: Hilditch R. W. , Hill Graham
Published: March 2016

A short account was given of results recently published (Hill et al. 1976; Hilditch et al. 1976a, b) of a spectroscopic and photometric study of 310 A0-F8 stars within 15° of the north galactic pole. Using these data, it has been found that δmo for the programme stars is constant out to 250 pc and corresponds, via Crawford’s (1975) calibration, to the solar value of [Fe/H]. The distribution of radial velocities of A0-F8 stars is asymmetric and may be interpreted as showing a broad distribution of mean −7 kms−1 and dispersion σ ~ 11 kms−1 together with a superposed narrow distribution of mean 0 kms-1 and dispersion σ ~ 3 kms-1. The narrow component originates from a group of 37 stars which appear to be kinematically and spatially associated with the Coma cluster. Only 14 of these 37 stars are recognised members of the Coma cluster. Removal of these 37 stars from the sample results in a distribution which matches closely the W component distribution of A0-F8 stars in Gliese’s (1969) catalogue. Thus Oort’s “well-mixed” hypothesis seems to be confirmed out to 250 pc. Much additional work on the space motions is required before the hypothesis of the ‘Coma group’ can be thoroughly tested. Results of this analysis and a preliminary value for the total mass density in the solar neighbourhood is expected to be completed during the next few months.
The Distribution of Field Horizontal–Branch Stars in the Galactic Halo
Authors: Philip A. G. Davis
Published: March 2016

Since the time allowed per paper at this joint discussion is short only one aspect of the stellar distribution at high galactic latitudes will be presented here, namely the distribution of field horizontal-branch stars (FHB) in the galactic halo. First, the method by which FHB stars are found will be described. Second, the density distribution of FHB stars will be compared with that of the RR Lyrae stars.

As part of a general program to study the stellar density distribution perpendicular to the galactic plane a number of possible FHB stars has been discovered. In each survey area objective prism plates (at a dispersion of 280 Å/mm. to a limiting magnitude of V = 14) are taken with the Michigan Curtis Schmidt telescope at Cerro Tololo Inter-American Observatory or the Schmidt telescope at the Warner and Swasey Observatory. A set of direct plates are taken also to obtain photographic magnitudes for the stars with spectral classifications.
Discussion of the Calculation of the Density Law (Dz)
Authors: Lacarrieu C. Turon
Published: March 2016

A matrix method involving eigenvector expansion is used to solve the “fundamental equation” of stellar statistics. This method is applied to M dwarfs and K giants.
Current Results and Suggestions for Future Work
Authors: McCarthy M. , Philip A. G. D. , King I. , Steinlin U.
Published: March 2016

In the days following our Joint Discussion the Co-editors were joined by two of the participants, Dr. Ivan King and Dr. Uli Steinlin, in an effort to evaluate results reported as well as the problems posed for future work. As a result of these discussions at Grenoble the present listing was made. This list was presented to members of the Organizing Committee but since it was impossible in the last days at Grenoble to convene this group or to speak collegially with all participants it must remain the responsibility of the above-named authors. It cannot be a complete resumé nor can it presume to represent adequately the varied opinions expressed at Grenoble on 25 August. We hope here only to attempt a synthesis of certain evident results and to outline certain prospects for exploring further the exciting problems of structure and evolution in the galactic polar caps.
Observational Evidence for Atmospheric Physical Characteristics Relevant to Stellar Evolution
Authors: Cayrel R. and G.
Published: March 2016

As a star burns its nuclear fuel, its radius R and its luminosity L are modified. Its mass may as well be affected if the mass loss rate has a time scale comparable to the nuclear time scale; this is likely to occur for stars of very high luminosity. Currently, the change in radius R and luminosity L of an evolving star is described in the socalled theoretical Herzsprung-Russel diagramme with in abscissa the logarithm of the effective temperature defined by:
Small Scale Solar Magnetic Fields: Theory
Authors: Weiss N. O.
Published: March 2016

One of the most exciting developments in solar physics over the past eight years has been the success of ground based observers in resolving features with a scale smaller than the solar granulation. In particular, they have demonstrated the existence of intense magnetic fields, with strengths of up to about 1600G. Harvey (1976) has just given an excellent summary of these results.

In solar physics, theory generally follows observations. Inter-granular magnetic fields had indeed been expected but their magnitude came as a surprise. Some problems have been discussed in previous reviews (Schmidt, 1968, 1974; Weiss, 1969; Parker, 1976d; Stenflo, 1976) and the new observations have stimulated a flurry of theoretical papers. This review will be limited to the principal problems raised by these filamentary magnetic fields. I shall discuss the interaction of magnetic fields with convection in the sun and attempt to answer such questions as: what is the nature of the equilibrium in a flux tube? how are the fields contained? what determines their stability? how are such strong fields formed and maintained? and what limits the maximum field strength?
Line Profiles of Faculae and Pores
Authors: Frazier Edward N.
Published: March 2016

Historically, attempts to model the temperature structure of faculae have generally suffered from a rather basic contradiction. Models which were based on center to limb measurements of the continuum contrast of faculae disagree with models that are based on measurements of line profiles in faculae. The “continuum” models predict line weakenings which are of larger amplitude than what is observed, and the “line profile” models predict a continuum contrast that is less than what is observed. Chapman (1976) discusses this problem in some detail. It is the purpose of this paper to show that there is a fundamental reason for this historical contradiction between line profile measurements and continuum contrast measurements: The line profile and the continuum contrast of a given facular are both a function (the two functions are different) of the size of that facula. The first indication of this fact was given by Frazier (1971). Figure 1 shows the contrast of faculae in the core of the line Fe Iλ 525. 0 nm, and in the continuum, as a function of the observed magnetic flux. One can see immediately that the contrast in each channel depends on φ in a much different manner. Therefore, one can conclude that the shape of the entire line profile will vary as a function of φ. On the basis of Figure 1, we must expect that this variation of the line profile will be continuous from infinitesimally small faculae up through very large faculae, and indeed, all the way up to pores.
[no title]
Authors: Houziaux L.
Published: March 2016

The idea of organizing a joint discussion on the impact of ultraviolet observations on spectral classification arose during the IAU symposium n»72 held at Lausanne, in the honour of W.W. Morgan. It became evident at that time that the wealth of spectroscopic and spectrometric data already obtained from various orbiting telescopes should shed some new light on the problem of spectral classification. I whish to thank here the members of the Organizing Committee who planned this Joint Discussion: W.P. Bidelman, A.D. Code, C. Jaschek, and K. Nandy. I also thank the authors of invited reports and contributed papers, as well as those who participated in the discussions.
Spectral Classification of Early Type Stars from the Low Dispersion Ultraviolet Spectra
Authors: Nandy K.
Published: March 2016

The methods of spectral classification from the low dispersion ultraviolet spectra obtained with the S2/68 experiment in the TD1 satellite have been described. The bright stars, the spectra of which are photometrically accurate, can be divided into natural groups according to the spectral appearance of the features. These features vary in strength with spectral type and luminosity, and enable separation between main sequence and luminous stars. The limits for these stars areat BO toat AO. For fainter stars the spectral data have been combined to obtain narrow band magnitudes at several wavelengths. These photometric bands have an effective width of 100 A. An ultraviolet photometric system which enables determinations of spectral type and luminosity of early type stars is described and the results for about 3000 stars is presented. The photometric system considered here consists of the ultraviolet colour indices (m2740−V,) (m2190−V) and (m1490−V).
Introductory Remarks to the Joint Discussion on Nuclei of Normal Galaxies
Authors: Burton W. B.
Published: March 2016

The papers which follow here were given at the Joint Discussion on Nuclei of Normal Galaxies, held in Montreal on August 21, 1979, at the XVIIth General Assembly of the International Astronomical Union. This Joint Discussion was jointly sponsored by IAU Commission 28 on Galaxies, by Commission 33 on Structure and Dynamics of the Galactic System, by Commission 34 on Interstellar Matter and Planetary Nebulae, and by Commission 40 on Radio Astronomy. The scientific organizing committee consisted of W. B. Burton (Minnesota), chairman, R. D. Ekers (Groningen), H. Okuda (Kyoto), D. E. Osterbrock (Lick), V. I. Pronik (Crimea), and D. W. Weedman (Pennsylvania).

While preparing for this Joint Discussion, the organizing committee struggled with the problem of finding a suitable definition for the notorious word “normal” as applied to the enormously complicated phenomena of galaxies. What has become clear is that galactic nuclei of all sorts share an involvement in a continuous hierarchy. Thus the lower extent of the energy range exhibited by nuclei of Seyfert galaxies overlaps the upper extent of the energy range of galactic nuclei which most of us would classify as normal. Likewise, many agreeably-normal nuclei show signs of disruptive activity, high velocity dispersions, morphological asymmetries, and ejection. It has also become clear that study of nuclear phenomena must extend to include study of the entire bulge or core region. These matters are reflected in the papers which follow. These papers also collectively emphasize that galactic nuclei reveal different properties at different wave-lengths; presented at the Joint Discussion were results derived from optical and infrared data, as well as from millimeter and longer wavelength radio data. The papers also serve to put work on the nucleus of our own galaxy, which shows many of the same puzzling properties found in other normal galactic nuclei, into a pleasantly wider perspective.
Tri-Axial Dynamics in the Core of Normal Galaxies
Authors: Schwarzschild M.
Published: March 2016

Please let me for fifteen minutes completely ignore all gas in the cores of galaxies. Clearly the core gas exhibits fascinating, varied and consequential phenomena. Still it would seem to me a plausible assumption that while the gas might be decisively affected by the stars, this gas might not have major effects on the stars, at least in their dynamical behavior. Accordingly I shall here consider purely stellar systems.

Obviously in the core of a galaxy, for dynamical consideration we have to distinguish sharply between the nucleus of a galaxy and the larger components of the galaxy co-occupying the core. Following Baade’s usage the nucleus is a stellar system of at most a few parsecs in radius and of a density substantially higher than the central densities of the other components. That the nucleus of a galaxy, at least in its equilibrium state -though not necessarily in its origin- is a distinct, self-contained stellar system seems to me strongly indicated by the rotation velocity measurements in the nucleus of the Andromeda Nebula (Lallemand et al. 1960; Walker, 1974) as well as by the photometric profile determination of the same nucleus (Light et al. 1974). For a nucleus of 108 stars the relaxation time for stellar encounters is, according to Spitzer (1971), comparable to a Hubble time while stellar collisions are ignorable. On the other hand, for a nucleus containing 1010 stars, which may be the right order of magnitude for more pronounced nuclei, the relaxation time may be comfortably long enough so that encounters may be ignored, but the frequency of collisions is not ignorable. In both cases therefore it would seem that in the centermost portions of nuclei of galaxies either encounters or collisions play a decisive dynamical role but the same may not be true in the outer portions of these nuclei. For the larger subsystems occupying the core of a galaxy, obviously neither encounters nor collisions play a significant role. To stay within the limits of my knowledge, I shall limit myself here to encounterless and collisionless stellar systems, a marginal approximation for the nuclei proper.
Very Hot Plasmas in the Solar System
Authors: Axford W. I.
Published: March 2016

In contrast to most astrophysical situations where information about hot plasmas can be obtained only from emission and absorption spectra, often without spatial resolution, plasmas in the solar system in many cases provide us with the opportunity to make direct, in situ measurements. Such plasmas, notably the solar wind and the plasmas contained in the magnetosphere of the earth, Jupiter, and other planets, must be heated by processes which are in many cases similar to those occurring in astrophysical plasmas and their behaviour should also be to some extent similar. It is therefore interesting and instructive to be able to compare our observations and understanding of these accessible solar system plasmas with those found elsewhere in the universe which are not so easy to observe in detail. This might provide us with some new ideas and perspectives on the nature and behaviour of hot plasmas in general and also an opportunity to test some of our ideas against “ground truth”.
The Hot Component of the Interstellar Medium
Authors: Jenkins E. B.
Published: March 2016

Revolutionary changes in our awareness of the physical state of gases in interstellar space have been precipitated by new theoretical realizations and observational evidence. Mechanical energy released by supernovae and early-type stars is now thought to be an important source of heating and agitation for the interstellar medium (McCray and Snow 1979). The propagation and dissipation of this energy gives rise to a broadly distributed network of gas at low densities and high temperatures, revealed to us by its emission of soft x-rays (Cox 1977, Tanaka and Bleeker 1977) and the pervasiveness of highly ionized atoms (with 0 VI being the most conspicuous tracer, see York 1974, Jenkins and Meloy 1974, review by Jenkins 1977).
Nova Modeling
Authors: Sparks Warren M. , Kutter G. Siegfried , Starrfield Sumner , Truran James W.
Published: March 2016

The mass and energy of nova ejecta are 10-5 - 10-4M⊚ and 1044 - 1045 ergs, respectively (Payne-Gaposchkin 1957). Comparison of these quantities with the mass (1 M⊚) and binding energy (1051 erg) of the erupting white dwarf implies that the nova outburst is a surface event. From an average of two or three novae detected each year, it is estimated that the rate of novae is 40-50 per year in our galaxy (Payne-Gaposchkin 1954) . Comparing this rate with a white dwarf birth rate of 2 per year in our galaxy (Weidemann 1968), we conclude that the nova outburst is a recurrent phenomenon (cf. Ford 1978). The recurrent nature also implies that the white dwarf cannot be drastically altered from event to event, thus giving further evidence for a surface event. The argument of recurrency become even stronger when it is realized that observations strongly indicate a close binary structure for the nova candidates—the white dwarf and a red companion (Kraft 1964).

Kraft (1963) proposed the following hypothesis. The red companion overflows its Roche lobe and supplies hydrogen-rich material to an accretion disk around the white dwarf. This material eventually accretes onto the white dwarf, forming an hydrogen-rich envelope whose base is electron-degenerate. As the accretion proceeds, the temperature at the base of this envelope increases. This has little effect on the pressure, but greatly increases the thermonuclear energy generation. The thermonuclear energy generation, in turn, increases the temperature. This positive feedback loop leads to a thermonuclear runaway, which Kraft proposed as the cause of the nova outburst. A large number of theoretical studies based on this model have been carried out. These studies are presented in order of increasing realism and complexity in the following sections.
Chromospheres, Coronae, and Mass Loss in Stars Hotter than the Sun
Authors: Snow Theodore P.
Published: March 2016

Reviews of the mass-loss characteristics of OB stars have been published recently, and the present review therefore emphasizes the A and F stars and very recent results on O and B stars. For the F stars, chromospheric indicators are present in the form of emission lines, seen in visible and ultraviolet wavelengths. Winds are present in A supergiants, but not in main sequence stars, although at least a few of the latter are X-ray sources, indicating the possible existence of coronae. Most OB supergiants are X-ray sources as well, indicating, along with the presence of super-ionization, that these stars have coronae. On the main sequence, the O stars and some B stars (including Be stars in many cases) have mass loss with highly-ionized species in the wind. The winds in the O and B stars are commonly variable. The mass-loss rates do not show a simple dependence on luminosity, contrary to the predictions for radiatively-driven winds.
Small-Scale Dissipative Processes in Stellar Atmospheres
Authors: Leibacher J. W. , Stein R. F.
Published: March 2016

The outer atmospheres of stars must be heated by some non-thermal energy flux to produce chromospheres and coronae. We discuss processes which convert the non-thermal energy flux of organized, macroscopic motions into random, microscopic (thermal) motions. Recent advances in our description of the chromosphere velocity field suggest that the acoustic waves observed there transmit very little energy, and hence are probably incapable of heating the upper chromosphere and corona. The apparent failure of this long held mechanism and the growing appreciation of the importance of strong magnetic fields in the chromosphere and corona have led to hypotheses of heating by the dissipation of currents (both oscillatory and quasi-steady). This follows discoveries in laboratory and ionospheric plasmas and work on solar flares, that instabilities can concentrate currents into thin high current density filaments where they dissipate rapidly.
Spectroscopy-What are The Needs Once Space Astrometry has Given us a New Data Base
Authors: Jaschek C.
Published: March 2016

I think the best way to start my talk is to recall what kind of spectroscopic, information is available at present. Spectroscopic information can be of various kinds; starting from the simplest it may be:

a- a spectral type (unidimensional)

b- a spectral type plus a luminosity class (bi-dimensional type)

c- a description-more or less detailed

d- a quantitative analysis, which can be more or less sophisticated
Star Formation History of Nearby Dwarf Galaxies
Authors: Mould J. R.
Published: March 2016

This review will take the linear view of the history of stellar systems. Thus the last billion years of a dwarf galaxy’s development receives no special attention. A considerable amount of information has recently come to light on the intermediate age populations of dwarf galaxies.
Cepheids in External Galaxies
Authors: Madore Barry F.
Published: March 2016

The study of Cepheids in external galaxies has been a continuous probing of the near-by distance scale accompanied by a refining and redefining of the Period-Luminosity relation itself. For example, the nearest two late-type galaxies of the Local Group, the Magellanic Clouds have always been the testbed for calibrations, from the pioneering optical studies of Leavitt (1907) to the recent infrared calibration of McGonegal et al. (1982) three quarters of a century later.

With time the data have improved in quality and in quantity but the methods of analysis and interpretation have so proliferated that the field might appear to be less well defined than it was at the turn of the century. Discussions of the problems have been so open that many have been driven to the conclusion that it is perhaps better to gauge the distances to galaxies using a variety of indicators, of secondary quality, rather than risk systematic errors at the start, through a complete reliance on one primary distance indicator. That situation, I believe, now has the potential for reversing itself.
Corrections for Velocity Dispersion in the Tully-Fisher Relation
Authors: Bottinelli L. , Gouguenheim L. , Paturel G. , de Vaucouleurs G.
Published: March 2016

The 21-cm line width is a good indication of the maximum rotational velocity in a galaxy. However, the turbulent motions affect the observed line width and must be corrected. Not taking them into account introduces both accidental and systematic errors.

A first example of this effect is the dependence of the slope a of the Tully-Fisher relation:

on the level at which the line width ΔVobs. is measured. In their 1977 paper, Tully and Fisher find the following values:

A second example is the departure from linearity in the H-band Tully-Fisher relation obtained by Aaronson et al. (1982) (their figure 2): the narrow lines are more strongly affected by these turbulent motions.