bluuebunny/crossref_metadata_2025 huggingface dataset:
Flexural, impact, rheological and physical characterizations of POM reinforced by carbon nanotubes and paraffin oil
Authors: Yousef Samy , Visco Annamaria , Galtieri Giovanna , Njuguna James
Published: March 2016

The paraffin oil dispersion technique innovated in the recent years to synthesize bulk polymer nanocomposite materials has a uniform dispersion. This research work aims to study the effect of added carbon nanotubes (CNTs) on flexural, impact and rheology behaviors of polyoxymethylene (POM) reinforced by 0–0.03 wt% of CNT using paraffin oil dispersion technique. The wettability and lamellar thickness were measured and rheological performance investigated using a parallel plate rheometer. The flexural and impact mechanical properties were also evaluated. The fracture surfaces were then examined by microscopy. The results showed that the energy to break, flexural strength and modulus increased proportionally with the addition of the amount of CNT in the matrix. For the rheology behavior, the viscosity decreased at the low percentage of CNT and then increased with increase in the percentage weight ratio of CNT in the POM matrix. It was also noted that the water contact angle rose with the increase the CNT percentages. Copyright © 2016 John Wiley & Sons, Ltd.
Amphiphilic linear–hyperbranched polymer poly(ethylene glycol)–branched polyethylenimine–poly(ϵ‐caprolactone): synthesis, self‐assembly and application as stabilizer of platinum nanoparticles
Authors: Dai Yu , Zhang Xiaojin , Zhuo Renxi
Published: March 2016

Amphiphilic linear–hyperbranched polymer poly(ethylene glycol)–branched polyethylenimine–poly(ϵ‐caprolactone) (PEG‐PEI‐PCL) was synthesized by progressively conjugating PEG (one chain) and PCL (multi‐chains) to PEI (hyperbranched architecture) with a yield of 87%. PEG‐PEI‐PCL forms nano‐sized uniform spherical micelles by self‐assembly in water. The micelles had an average diameter of 56 nm determined using dynamic light scattering and 35 nm observed from transmission electron microscopy images. PEG‐PEI‐PCL was used as a stabilizer of platinum nanoparticles (PtNPs) for the first time. The particle diameter of PEG‐PEI‐PCL‐stabilized PtNPs was 7.8 ± 1.4 nm. Amphiphilic (hydrophilic–hydrophilic–hydrophobic) and hyperbranched (linear–hyperbranched–grafted) structures enabled PtNPs to effectively stabilize and disperse in liquid‐phase synthesis. The highly disperse PtNPs in PEG‐PEI‐PCL micelles improved the catalytic activity for the reduction of 4‐nitrophenol with a catalytic yield of near 100%. © 2016 Society of Chemical Industry
Classification of MALDI‐MS imaging data of tissue microarrays using canonical correlation analysis‐based variable selection
Authors: Winderbaum Lyron , Koch Inge , Mittal Parul , Hoffmann Peter
Published: March 2016

Applying MALDI‐MS imaging to tissue microarrays (TMAs) provides access to proteomics data from large cohorts of patients in a cost‐ and time‐efficient way, and opens the potential for applying this technology in clinical diagnosis. The complexity of these TMA data—high‐dimensional low sample size—provides challenges for the statistical analysis, as classical methods typically require a nonsingular covariance matrix that cannot be satisfied if the dimension is greater than the sample size. We use TMAs to collect data from endometrial primary carcinomas from 43 patients. Each patient has a lymph node metastasis (LNM) status of positive or negative, which we predict on the basis of the MALDI‐MS imaging TMA data. We propose a variable selection approach based on canonical correlation analysis that explicitly uses the LNM information. We apply LDA to the selected variables only. Our method misclassifies 2.3–20.9% of patients by leave‐one‐out cross‐validation and strongly outperforms LDA after reduction of the original data with principle component analysis.
The advantage of laser‐capture microdissection over whole tissue analysis in proteomic profiling studies
Authors: De Marchi Tommaso , Braakman Rene B. H. , Stingl Christoph , van Duijn Martijn M. , Smid Marcel , Foekens John A. , Luider Theo M. , Martens John W. M. , Umar Arzu
Published: March 2016

Laser‐capture microdissection (LCM) offers a reliable cell population enrichment tool and has been successfully coupled to MS analysis. Despite this, most proteomic studies employ whole tissue lysate (WTL) analysis in the discovery of disease biomarkers and in profiling analyses. Furthermore, the influence of tissue heterogeneity in WTL analysis, nor its impact in biomarker discovery studies have been completely elucidated. In order to address this, we compared previously obtained high resolution MS data from a cohort of 38 breast cancer tissues, of which both LCM enriched tumor epithelial cells and WTL samples were analyzed. Label‐free quantification (LFQ) analysis through MaxQuant software showed a significantly higher number of identified and quantified proteins in LCM enriched samples (3404) compared to WTLs (2837). Furthermore, WTL samples displayed a higher amount of missing data compared to LCM both at peptide and protein levels (p‐value < 0.001). 2D analysis on co‐expressed proteins revealed discrepant expression of immune system and lipid metabolisms related proteins between LCM and WTL samples. We hereby show that LCM better dissected the biology of breast tumor epithelial cells, possibly due to lower interference from surrounding tissues and highly abundant proteins. All data have been deposited in the ProteomeXchange with the dataset identifier PXD002381 (http://proteomecentral.proteomexchange.org/dataset/PXD002381).
Evaluation of Nano‐Co3O4 in HTPB‐Based Composite Propellant Formulations
Authors: Kshirsagar Dhirendra R. , Jain Sunil , Jawalkar Shekhar N. , Naik Nilesh H. , Pawar Suman , Maurya Mehilal
Published: March 2016

Different propellant compositions were prepared by incorporating nano‐sized cobalt oxide from 0.25 % to 1 % in HTPB/AP/Al‐based composite propellant formulations with 86 % solid loading. The effects on viscosity build‐up, thermal, mechanical and ballistic properties were studied. The findings revealed that by increasing the percentage of nano‐Co3O4 in the composition, the end of mix viscosity, the modulus and the tensile strength increased, whereas the elongation decreased accordingly. The thermal property data envisaged a reduction in the decomposition temperature of ammonium perchlorate (AP) as well as formulations based on AP. The ballistic property data revealed an enhanced burning rate from 6.11 mm s−1 (reference composition) to 8.99 mm s−1 at 6.86 MPa and a marginal increase in pressure exponent from 0.35 (reference composition) to 0.42 with 1 % nano‐cobalt oxide.
The CeO2/Ag3PO4 photocatalyst with stability and high photocatalytic activity under visible light irradiation
Authors: Song Yanhua , Zhao Haozhu , Chen Zhigang , Wang Weiren , Huang Liying , Xu Hui , Li Huaming
Published: March 2016

The CeO2/Ag3PO4 composite photocatalysts are synthesized by an in situ precipitation method. The XRD, FT‐IR, XPS, TEM, EDS, and DRS are used to characterize the structure of the samples. The photocatalytic performance of the prepared samples is evaluated by the photocatalytic degradation of methylene blue (MB), rhodamine B (RhB), and ciprofloxacin (CIP). The results show that CeO2/Ag3PO4 hybrid materials exhibit much higher photocatalytic activity than the Ag3PO4 alone. The optimal CeO2 content in CeO2/Ag3PO4 composites is found to be molar ratio 1 wt%. Photocurrent response of CeO2/Ag3PO4 (1 wt%) is about 1.5 times as high as that of the pure Ag3PO4. The increase of photocatalytic activity of CeO2/Ag3PO4 composites could be mainly attributed to the heterojunction between CeO2 and Ag3PO4. The trapping experiment has demonstrated that holes serve as the main active species for the degradation of MB under visible light irradiation. A photocatalytic mechanism is also proposed.
Auxetic composites made of 3D textile structure and polyurethane foam
Authors: Zhou Lin , Jiang Lili , Hu Hong
Published: March 2016

Auxetic composites have attracted considerable attention in recent years and have demonstrated a high potential of applications in different areas due to their wonderful properties as compared to non‐auxetic composites. In this study, a three‐dimensional (3D) auxetic textile structure previously developed was used as reinforcement to fabricate auxetic composites with conventional polyurethane (PU) foam. Both the deformation behavior and mechanical properties of the auxetic composites under compression were analyzed and compared with those of the pure PU foam and non‐auxetic composites made with the same materials and structural parameters but with different yarn arrangement. The results show that the negative Poisson's ratio of composites can be obtained when suitable yarn arrangement in a 3D textile structure is adopted. The results also show that the auxetic composites and non‐auxetic composites have different mechanical behaviors due to different yarn arrangements in 3D textile structure. While the auxetic composites behave more like damping material with lower compression stress, the non‐auxetic composite behaves more like stiffer material with higher compression stress. It is expected that this study could pave a way to the development of innovative 3D auxetic textile composites for different potential applications such as impact protection.
Superconductivity of Ta34Nb33Hf8Zr14Ti11 high entropy alloy from first principles calculations
Authors: Jasiewicz K. , Wiendlocha B. , Korbeń P. , Kaprzyk S. , Tobola J.
Published: March 2016

The Korringa–Kohn–Rostoker method with the coherent potental approximation (KKR‐CPA) is applied to study the first superconducting high entropy alloy (HEA) Ta34Nb33Hf8Zr14Ti11 (discovered in 2014 with Tc = 7.3 K), focusing on estimations of the electron–phonon coupling constant λ. The electronic part of λ has been calculated using the rigid muffin‐tin approximation (RMTA), while the phonon part has been approximated using average atomic mass and experimental Debye temperature. The estimated λ = 1.16 is close to the value determined from specific heat measurements, λ = 0.98, and suggests rather strong electron–phonon coupling in this material. (© 2016 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)
Congratulations John Grant!
Authors: Artyushkova Kateryna
Published: March 2016

With this special issue, we are celebrating the outstanding career of John Grant, who is retiring from both his roles as SIA North‐American Editor and his affiliation with the University of Dayton Research Institute and the Air Force Materials Lab.

We open this issue with a personal note from the Air Force Research Laboratory written by Neil Murphy. This note is followed by an essay by several of John's surface analysis colleagues, highlighting the professionalism that has been one of the hallmarks of John's career. We are all indebted to John for conveying the importance of true professionalism through his teaching, journal editorship and numerous other contributions to the surface analysis community. John's many professional activities and awards are summarized below.
Very high gravity ethanol and fatty acid production of Zymomonas mobilis without amino acid and vitamin
Authors: Wang Haoyong , Cao Shangzhi , Wang William Tianshuo , Wang Kaven Tianyv , Jia Xianhui
Published: March 2016

Very high gravity (VHG) fermentation is the mainstream technology in ethanol industry, which requires the strains be resistant to multiple stresses such as high glucose concentration, high ethanol concentration, high temperature and harsh acidic conditions. To our knowledge, it was not reported previously that any ethanol-producing microbe showed a high performance in VHG fermentations without amino acid and vitamin. Here we demonstrate the engineering of a xylose utilizing recombinant Zymomonas mobilis for VHG ethanol fermentations. The recombinant strain can produce ethanol up to 136 g/L without amino acid and vitamin with a theoretical yield of 90 %, which is significantly superior to that produced by all the reported ethanol-producing strains. The intracellular fatty acids of the bacterial were about 16 % of the bacterial dry biomass, with the ratio of ethanol:fatty acids was about 273:1 (g/g). The recombinant strain was achieved by a multivariate-modular strategy tackles with the multiple stresses which are closely linked to the ethanol productivity of Z. mobilis. The over-expression of metB/yfdZ operon enabled the growth of the recombinant Z. mobilis in a chemically defined medium without amino acid and vitamin; and the fatty acids overproduction significantly increased ethanol tolerance and ethanol production. The coupled production of ethanol with fatty acids of the Z. mobilis without amino acid and vitamin under VHG fermentation conditions may permit a significant reduction of the production cost of ethanol and microbial fatty acids.
Mental health benefits of outdoor adventures: Results from two pilot studies
Authors: Mutz Michael , Müller Johannes
Published: March 2016

This paper investigates potential mental health benefits of outdoor and adventure education programs. It is argued that experiences made in successful programs can increase self‐efficacy, mindfulness and subjective well‐being. Furthermore, programs may reduce feelings of time pressure and mental stress amongst participants. Evidence comes from two pilot studies: In the school project “Crossing the Alps” (Study 1), 14‐year‐old participants reported an increase in life satisfaction, mindfulness and a decrease in the PSQ Subscale ‘demand’ after a successful nine‐day hike through the German, Austrian, and Italian Alps. In the university project “Friluftsliv” (Study 2) participants scored higher in life satisfaction, happiness, mindfulness, and self‐efficacy and lower in perceived stress after having spent eight days in the wilderness of the Norwegian Hardangervidda region, miles away from the next locality. The findings suggest that outdoor education and wilderness programs can foster mental health in youths and young adults.
The writing on the wall? John Ingram’s verse and the dissemination of Catholic prison writing
Authors: Shell Alison
Published: March 2016

The strong association between prison writing and writing on walls, whether by graffiti or carving, is as true of Tudor and Stuart England as of other times and places. Yet even if prison-writers associated themselves with the idea of writing on a wall, they need not have done so in reality. This article considers the topos in the writings and afterlife of the Catholic priest, poet and martyr John Ingram, and asks whether it is to be taken at face value.

Ingram’s verse, composed in Latin and mostly epigrammatic, survives in two contemporary manuscripts. The notion that the author carved his verses with a blunt knife on the walls of the Tower of London while awaiting death derives from a previous editorial interpretation of a prefatory sentence within the more authoritative manuscript of the two, traditionally held to be autograph. However, though several Tudor and Stuart inscriptions survive to this day on the walls of the Tower of London, no portions of Ingram’s verse are among them, nor any inscriptions of similar length and complexity. Ingram might instead have written his verse down in the usual way, using wall-carving as a metaphor for the difficulty of writing verse when undergoing incarceration and torture.1
The Sheffield portrait types, their Catholic purposes, and Mary Queen of Scots’s tomb
Authors: Smith Jeremy L.
Published: March 2016

The tomb of Mary Queen of Scots is widely recognized as one of the most important visual symbols of dynastic power that can still be viewed in Britain today. Although art historians had originally regarded the strongly Catholic depiction of Mary in captivity, the so-called Sheffield portrait, as the model for the effigy, for more than a century the consensus is that it was based on one of Nicholas Hilliard’s miniature portraits. In this essay a study of the images as well as related documents in the exchequer and Hardwick Hall accounts reestablishes that the Sheffield type was indeed the specific model for the tomb. This does more than simply settle a long-standing question. It also opens the way for an exploration of the content of this most popular portrait of Mary, which was fraught with significance not only for King James VI, Mary’s son, but also the crypto-Catholic nobleman Henry Howard, first earl of Northampton, who was in charge of the tomb’s completion.
Limbic Encephalitis Associated With GAD65 Antibodies: Brief Review of the Relevant literature
Authors: Gagnon Maude-Marie , Savard Martin
Published: March 2016

Recently, many cases of autoimmune limbic encephalitis with positive GAD65 (glutamic acid decarboxylase) antibodies have been described in the scientific literature. However, it remains an understudied topic of great relevance to practicing neurologists. Thus, we report here a review of published cases, in English, of autoimmune limbic encephalitis with this type of antibodies, focusing on presenting symptoms and signs, associated conditions, and findings upon investigation. We also report treatment responses. We aim to offer a better description of the clinical spectrum of autoimmune limbic encephalitis associated with GAD65 antibodies as well as to expose its paraclinical features and outcome.
A sensitivity study of annual area change for Greenland ice sheet marine terminating outlet glaciers: 1999–2013
Authors: JENSEN TRINE S. , BOX JASON E. , HVIDBERG CHRISTINE S.
Published: March 2016

The mass flux from marine terminating glacier outlets from the Greenland ice sheet is a significant mass budget term. Yet, glacier calving sensitivity to climate parameters is not well understood. In this study, the front area changes of 42 marine terminating Greenland outlet glaciers were measured annually from 1999 to 2013 using optical satellite imagery. Thirty-five glaciers retreated, while seven remained stable. The average front position change was −240 m a−1 and the total rate of front area change was −114 km2 a−1. The yearly average area changes of all measured glaciers are compared with interannual variations in sea surface temperature (SST), sea-ice concentration (SIC), surface melt, Northern Hemisphere (NH) surface air temperatures and the North Atlantic Oscillation (NAO) index. We find: (1) northwestern glaciers area change have a significant correlation with surface melt and NH land temperature variations; (2) southeastern glaciers have a significant correlation with local SST, SIC and NH temperatures; and (3) southwestern glaciers area change correlate significantly with local SST and NAO index. We conclude that a climate sensitivity signal emerges considering a population of glaciers. Further, we find a significant correlation between the date of minimum extent and glacier latitude. Area change data are available from http://GAC.geus.dk.
The Evolution of Self-Gravitating Accretion Discs
Authors: Rice Ken
Published: March 2016

It is quite likely that self-gravity will play an important role in the evolution of accretion discs, in particular, those around young stars, and those around supermassive black holes. We summarise, here, our current understanding of the evolution of such discs, focussing more on discs in young stellar system, than on discs in active galactic nuclei. We consider the conditions under which such discs may fragment to form bound objects, and when they might, instead, be expected to settle into a quasi-steady, self-regulated state. We also discuss how this understanding may depend on the mass of the disc relative to the mass of the central object, and how it might depend on the presence of external irradiation. Additionally, we consider whether or not fragmentation might be stochastic, where we might expect it to occur in an actual protostellar disc, and if there is any evidence for fragmentation actually playing a role in the formation of planetary-mass bodies. Although there are still a number of outstanding issue, such as the convergence of simulations of self-gravitating discs, whether or not there is more than one mode of fragmentation, and quite what role self-gravitating discs may play in the planet-formation process, our general understanding of these systems seems quite robust.
The Undocumented Everyday: Migrant Rights and Visual Strategies in the work of Alex Rivera
Authors: SCHREIBER REBECCA M.
Published: March 2016

This essay focusses on two music videos that filmmaker Alex Rivera directed in conjunction with the #Not1More campaign of the National Day Labor Organizing Network (NDLON). In creating these music videos, Rivera uses visual strategies to portray the “undocumented everyday,” which involves the documentation of the mundane details of existence, such as representation of the indispensability of undocumented Latina/o migrants to everyday economies in the United States.
The effects of familism on intended care arrangements in the process of preparing for future care among one-child parents in urban China
Authors: SONG YAJUN , YAN ELSIE C. W. , SÖRENSEN SILVIA
Published: March 2016

Guided by Sörensen and Pinquart's model of preparation for future care, this study investigated the relationship between familism and intended care arrangements. Ordinal logistic regression was performed on a sample of 516 urban Chinese one-child parents aged 45–65 with an equal gender ratio to examine the associations between five care expectations, familism (filial obligation and child gender) and future care planning constructs (awareness, information gathering and avoidance). Awareness and information gathering were positively associated with service-focused care arrangements. Avoidant planners were more inclined to rely on adult children. Participants with a stronger filial obligation had greater expectations for ageing at home with the aid of a spouse, siblings or helper. Child gender was not significantly associated with intended care arrangements. The model of preparation for future care was useful when predicting service-focused care arrangements. Familism was a powerful predictor of family-focused care arrangements. Females were more likely to rely on children regardless of child gender but less likely to rely on spouses and siblings. The study enriches researchers' understanding of urban Chinese older adults' intended care arrangements in the context of fading familism and single-child families.
Adding Edges to Increase the Chromatic Number of a Graph
Authors: KOSTOCHKA ALEXANDR , NEŠETŘIL JAROSLAV
Published: March 2016

If n ⩾ k + 1 and G is a connected n-vertex graph, then one can add $\binom{k}{2}$ edges to G so that the resulting graph contains the complete graph Kk+1. This yields that for any connected graph G with at least k + 1 vertices, one can add $\binom{k}{2}$ edges to G so that the resulting graph has chromatic number > k. A long time ago, Bollobás suggested that for every k ⩾ 3 there exists a k-chromatic graph Gk such that after adding to it any $\binom{k}{2}$ − 1 edges, the chromatic number of the resulting graph is still k. In this note we prove this conjecture.
The rationale behind the concept of goal
Authors: GOVERNATORI GUIDO , OLIVIERI FRANCESCO , SCANNAPIECO SIMONE , ROTOLO ANTONINO , CRISTANI MATTEO
Published: March 2016

The paper proposes a fresh look at the concept of goal and advances that motivational attitudes like desire, goal and intention are just facets of the broader notion of (acceptable) outcome. We propose to encode the preferences of an agent as sequences of “alternative acceptable outcomes”. We then study how the agent's beliefs and norms can be used to filter the mental attitudes out of the sequences of alternative acceptable outcomes. Finally, we formalise such intuitions in a novel Modal Defeasible Logic and we prove that the resulting formalisation is computationally feasible.
Some Problems Relating to Solar Line Identification
Authors: Gabriel A. H.
Published: March 2016

A review is given of some of the problems of classification and intensity analysis involving unidentified or recently identified lines in the ultraviolet solar spectrum. In particular, attention is drawn to the present position regarding two and three electron spectra in the soft X-ray region, and forbidden transitions within the ground configurations at longer wavelengths.
Computer Programs for Calculating Atomic Data For Ions
Authors: Eissner W.
Published: March 2016

This report is a continuation of the preceding review talk. I shall describe general purpose computer programs that have been developed in Professor Seaton’s group at University College London. Other speakers will present results produced with them.

The programs require a minimum of input. General purpose means; not restricted to one ion or just one isoelectronic sequence. High speed is achieved by using approximations suitable for medium and highly ionized light atoms. The programs allow fully for configuration mixing, which plays an important role in ion calculations. Equations in M. J. Seaton’s review will be referred to as (S.number).
A Data Acquisition System with On-Line Computer
Authors: Høg Erik
Published: March 2016

Nather and Evans (1970) emphasize that merely recording the light curve of an occultation is not enough. The data must be recorded in a form which is convenient for the analysis to be carried out later on. Analog methods of recording merely delay the time at which the record must be measured, usually after it has been digitized in some way. Nather and Evans have used a modified digital multiscaler with 400 storage locations for the observation. The data acquisition to be described here is in principle rather similar to a multiscaler and deserves special attention because it is in practice even more flexible and convenient due to its on-line computer. Our system has been used to measure star occultations (De Vegt and Pansch, 1970) and the Crab pulsar (Høg and Lohsen, 1970) and to sample data from a scanning photometer (Høg, 1969).
Photometric Observations of the Occultations of Stars by the Moon
Authors: Rakos Karl D.
Published: March 2016

The idea of finding the radius of a star from the distortion of the Fresnel pattern caused by diffraction at the edge of the Moon during an occultation, was first proposed by Williams in 1938. In subsequent years this idea was again taken up by a number of investigators: Whitford (1938, 1946,) Diercks and Hunger (1952), Evans et al. (1953), Cousins and Guelke (1953), Rakos (1964, 1967), Nather and Evans (1970). The greatest difficulty in carrying out such measures was the lack of a light detector of sufficiently high quantum efficiency and recording equipment of sufficiently
short time constant. Modern advances in electronics have overcome these difficulties to such an extent that it now appears feasible to determine the apparent diameters of many stars with a minimum expenditure of observing time and equipment.
Surface Composition and Cooling Histories of Neutron Stars
Authors: Cameron A. G. W.
Published: March 2016

One of the major questions which has been raised with the rotating neutron star model of pulsars, is whether cosmic rays can be produced by the pulsar phenomenon through the acceleration of the surface material of neutron stars. It is therefore very instructive to review the calculations which have been made on the surface structure and cooling histories of neutron stars.

Figure 1 shows a diagram of the interior of a neutron star, one of a sequence of models calculated by Cohen et al. (1970). In this diagram the radii of the various parts of the model are to scale. The total radius of the model is 13.7 km. Over a fairly large range of distance downwards from the surface, ions and electrons also put in an appearance, and below that there is a still narrower strip where protons coexist with the ions, electrons, and neutrons. Below this the ions disappear, and at still greater depths mu mesons put in an appearance. Finally, near the center of the star, the calculations indicated that other hyperons probably appear.

The region containing the ions can be expected to form a crystalline solid, except in the outer fringes of the atmosphere, where thermal effects and the relatively small pressure will vaporize any crystals.
Solar and Interplanetary Magnetic Fields and Plasmas
Authors: Wilcox John M.
Published: March 2016

A few recent observations of interplanetary fields and plasmas are discussed, including the evolution over several years of the longitudinal sector pattern, the corotating filamentary structure that exists within the sectors, guiding of solar cosmic rays along such magnetic filaments, a field-aligned thermal anisotropy of the plasma, and a small component of corotating plasma velocity observed at 1 AU. The solar wind plasma streaming past spacecraft near 1 AU contains a large amount of information about the detailed structure of the Sun.
Results from Detailed Studies of X-Ray Sources
Authors: Giacconi R.
Published: March 2016

Since the results of early surveys revealed the existence of cosmic X-ray sources (Giacconi and Gursky, 1965), the major effort of X-ray astronomy has been devoted to the investigation of their nature. With the exception of the X-ray source in the Crab Nebula (Bowyer et al., 1964), an object well known prior to the discovery of its X-ray emission, the galactic X-ray sources which have been observed do not appear to coincide with conspicuous visible or radio objects.

The attempt to study their nature has proceeded along two main directions:

(a) Accurate determinations of celestial coordinates for the X-ray emitters permit the identification of their visible and radio counterparts. When a likely candidate is discovered, the techniques of optical astronomy yield information regarding the spectrum, size, distance, temporal variations and polarization of the radiation emitted by the object.

(b) The properties of the X-ray emitter are investigated by careful measurement of the angular size of the X-ray emitting region, its detailed spectrum and its polarization and variability.
Evidence for Lithium Destruction and Synthesis in Main-Sequence and Subgiant Stars of about Solar Mass
Authors: Feast M. W.
Published: March 2016

Herbig’s extensive work on lithium abundances in solar-type stars on and near the main sequence, suggested to him that for these stars the lithium abundance might be some simple, decreasing function of age. If this were the full story we should expect a low lithium abundance in subgiants of about solar mass. However, already in Herbig’s work there were one or two stars with lithium abundance about 10 times the Greenstein-Richardson solar value whose trigonometrical parallaxes showed them to be possible subgiants. Other subgiants with high lithium abundances have been found by Wallerstein and at Pretoria. These results suggest that solar-mass stars are able to synthesise fresh lithium in or just prior to their subgiant phase.
Meridian Observations at Santiago, Chile
Authors: Anguita C. , Carrasco G. , Loyola P. , Šiškina V.N. , Zverev M.S.
Published: March 2016

Observations of the Southern Reference Star (SRS) and Bright Star (BS) programmes were started in January 1963 with the Repsold meridian circle of the Santiago Observatory. Up to July 1, 1967, a total of 86725 star observations arranged in 1520 series had been observed.

In order to investigate the instrumental system, series of fundamental stars between +41° and −69° SP were included in the observing programme. A total of 214 such series were observed, 123 being with ‘clamp East’ and 91 with ‘clamp West’. The number of individual star observations in these 214 series was 7344. These observations were reduced using Bessel’s formula

α = T + (u + m) + n tan δ + c′ sec δ,

where u denotes the clock correction and c′ includes the collimation error, diurnal aberration and the contact width.
Theories Proposed to Explain Quasi-Stellar Objects and Radio Galaxies
Authors: Burbidge Geoffrey
Published: March 2016

In this paper I shall consider briefly two major questions. The first is concerned with whether the QSO’s are at cosmological distances or not. The second is concerned with the theoretical models proposed to explain the observed properties of radio galaxies and quasi-stellar objects.

In the Invited Discourses Dr. Sandage and Sir Martin Ryle gave arguments which lead them to believe that the QSO’s lie at cosmological distances. They both have strong convictions in this matter. However, Dr. Sandage did remark that he was only giving one side of a ‘great debate’. It is presumably up to me to give the other side of this argument. I have no strong beliefs in this matter but it appears that on the basis of the evidence as it is today we cannot reasonably assert that the QSO’s are at cosmological distances.
High Resolution Interferometry of Cool Stars
Authors: Lambert D. L.
Published: March 2016

This paper reviews results obtained in a program of high resolution infrared spectroscopy of K and M giants. The reported results include (i) a preliminary analysis of the C, N and O abundances for α Ori, (ii) determinations of the 12C/13C and 16O/18O ratios for α Ori (12C/13C ~ 6 and 16O/18 ~ 500), (iii) the derivation of a lower limit, 16O/18O≳ 300, for the 160/18O ratio in α Boo, (iv) a discussion of observations of the SiO first-overtone vibration-rotation bands in M stars, and (v) a search for the fundamental quadrupole vibration-rotation lines of H2.
Spectrophotometry of Supernovae
Authors: Kirshner R. P.
Published: March 2016

Absolute spectral energy distributions for supernovae of both types I and II have been obtained. These observations demonstrate three facets of supernova spectra. First, both SN I’s and SN II’s have a continuum that varies slowly and uniformly with time, and which carries the bulk of the radiated flux at early epochs. Second, some lines in both SN I’s and SN II’s have P Cygni profiles: broad emissions flanked on their violet edges by broad absorptions. Third, some lines are common to SN I’s and SN II’s and persist throughout the evolution of the spectrum. The continuum temperatures for both SN I’s and SN II’s are about 10000 K at the earliest times of observation and drop in one month’s time to about 6000 K for SN II’s and about 7000 K for SN I’s. After several months, the continuum may cease to carry the bulk of the flux, which might be in emission lines, but continues to exist, as shown by the presence of absorption lines. The P Cygni line profiles indicate expansion velocities of 15000 km s-1 in SN II’s and 20000 km s-11 in the SN I 1972e in NGC 5253. Line identifications for SN II’s include Hα, Hβ, H and K of Ca II, the Ca II infrared triplet at λ8600, the Na I D-lines, the Mg I b-lines at λ5174, and perhaps Fe II. The [O I] lines λλ6300, 6363 and [Ca II] lines λλ7291, 7323 appear after eight months. For SN I’s, the lines identified are H and K of Ca II, the infrared Ca II lines, the Na I D-lines, and the Mg I b-lines. There is some evidence that Balmer lines are present two weeks after maximum. The strong and puzzling λ4600 features drifts with time from λ4600 near maximum light to λ4750 after 400 days.
Periods in X-Ray Sources
Authors: Davison P. J. N.
Published: March 2016

Known periodicities in X-ray sources cover a wide range of values - a factor of 108or 109from the 33 mS of the Crab pulsar up to 35 days for the Her X-1 repeat of its up state, or even years if one believes in the not inconceivable idea that at least one “transient” (perhaps not yet even discovered!) is exhibiting some form of repetitive behaviour. These periodicities are not just astronomical curiosities to keep theoreticians busy speculating. They do have several solid uses which the mere experimenter can take advantage of. These uses do, inevitably overlap, and vary in importance according to whom one is speaking. In the short space available I will concentrate on recent measurements on X-ray sources showing Doppler modulated periodicities, and on sources which may well show such changes when they are studied more closely.
OSO-8 Observations of Cygnus XR-1
Authors: Dolan J.F. , Dennis B.R. , Crannell C.J. , Frost K.J. , Orwig L.E.
Published: March 2016

Cygnus XR-1 was observed Nov. 11 to 18, 1975, in the energy range 20 to 400 keV with a Cgl scintillation crystal spectrometer on board the OSO-8 satellite. A drop in the count rate of ˜45% between 23 and 153 keV was observed to occur gradually over a full day on Nov. 16. Comparison with 2 to 7 keV proportional counter data taken simultaneously on OSO-8 by P. Serlemitsos et al. (private communication), the count rate of which rose ˜40% on Nov. 16, shows the 23 to 153 count rate to be generally anti-correlated with the 2 to 7 keV count rate over the entire 8 days of observation (Fig. 1). The observations are in agreement with the predictions of the two-temperature accretion disk model of Shapiro, Lightman and Eardley (Astrophys. J., 204, 187, 1976).
On the Magnetospheres of Jupiter, Saturn, and Uranus
Authors: van Allen James A.
Published: March 2016

A brief descriptive summary of Jupiter’s magnetosphere is based on in situ observations with the spacecraft Pioneer 10 and Pioneer 11 in November-December 1973 and November-December 1974, respectively. Current interpretative work emphasizes particle acceleration and loss mechanisms, the determination of diffusion coefficients by satellite effects, the topology of the outer magnetosphere, the possible recirculation of energetic particles, and the controversial evidence for an extended magnetotail.

Available evidence on non-thermal radio emissions of the planet and on the solar wind flow at 10 AU is invoked to suggest that Saturn very likely has a large, well developed magnetosphere resembling that of Jupiter but with the important difference that a radiation belt can not exist interior to the outer edge of the A ring of particulate matter. The first in situ observations will be made by Pioneer 11 in August-September 1979.
X-Ray Clusters of Galaxies: What to Plot Against X-Ray Luminosities?
Authors: Vidal N.V.
Published: March 2016

A new updated list of clusters of galaxies found within x-ray error boxes is presented. Since the last published list (Vidal 1975) four new clusters A478, A2142, A2255 and an anonymous cluster were found within 3U0405+10, 3U1555+27, 3U1639+40 and MX1329−31, respectively. This extensive list is used to look for phenomenological correlations between x-ray luminosities and other physical cluster parameters. We analysed 3 such correlations: (a) The x-ray luminosity-velocity dispersion diagram is presented using newly determined velocity dispersions in the clusters A1060 (Vidal & Peterson 1975), A1367 (Tifft & Tarenghi 1975) and the Centaurus cluster (Vidal & Wickramasinghe 1976). First, it is shown (Yahil & Vidal 1976) that the observed velocity distribution of galaxies in clusters in general is consistent with a gaussian and, therefore, the standard deviation of the distribution can be used as a good statistical measure for the velocity dispersion. But, inspecting the Lx-∆V diagram, it is shown that a linear relationship between these parameters is not compelling yet. Furthermore the slope of such an assumed linear relationship is relying too much on the isolated Perseus point. Consequently the velocity distribution in the Perseus cluster is critically analysed.
Small Magnetostatic Flux Tubes
Authors: Spruit H. C.
Published: March 2016

In an attempt to interpret the observed properties of small scale magnetic fields at the solar surface, a set of models has been calculated based on the assumption of a magnetostatic equilibrium. The basic assumptions made are:

i.

The observed magnetic elements are magnetostatic flux tubes.

ii.

The efficiency of convective heat transport inside the tube is reduced with respect to that in the normal convection zone; the horizontal convective heat transport in the tube is suppressed completely by the magnetic field.

iii.

Close to the tube, horizontal convective heat transport is reduced due to the proximity of the magnetic field.
Present Status of Spectral Classification in the Conventional Wavelength Range with Emphasis Upon Early-Type Stars
Authors: Jaschek C.
Published: March 2016

A spectral classification system is a morphological device for arranging in order a finite series of observations of individual objects, One has thus three elements: an “order”, i.e. an abstract discontinuous scheme, a series of objects and a certain type of observation (spectrogram) that is performed on all objects of the sample. The “order” is in principle arbitrary; one could think for instance of an order based on richness of lines, or on the presence of hydrogen lines, etc. However such an idealization is clearly simplistic, because it would imply that the classifier is completely unaware of theory -but he is not, if for no other reason than simply that he would never get his PhD. Thus one should add the constraint that the scheme one adopts be physically sound.
Direct Observations of the Heterogeneity of Supergiant Disks
Authors: Harvey J. W. , Lynds C. R. , Worden S. P.
Published: March 2016

Resolved images of the disks of the largest stars observed with the largest telescopes can be constructed using the class of techniques called speckle imaging. The observations must be made with narrow passbands (~ 10 nm), short exposures (~ 20 ms) compensation for atmospheric dispersion, high magnification and good signal-to-noise ratio. One specific technique applied to a Ori (Lynds et al., 1976) shows slight but apparently real differences in the images of the disk corresponding to low and high opacity in the stellar atmosphere which we interpret as due to temperature differences. There are also significant differences in the star’s diameter and/or limb darkening at the two different opacity wavelengths.
Ultraviolet Observations of Normal Galaxies
Authors: Bertola Francesco
Published: March 2016

The UV spectrum of galaxies provide us with the unique chance to detect those hot stellar components, which normally do not appear in the visible spectrum. Such components, interpreted as possibly due to horizontal-branch stars, have been found in spectra of early-type galaxies. All these spectra exhibit an UV excess shortward of 3000 A with respect to the energy distribution of a K-type star. UV excess is present in different amount also in spectra of late-type galaxies, but the data are fragmentary.

There is hope to define a standard UV spectrum of nearby elliptical galaxies to compare with that observed in the visible region in distant galaxies. This would allow the determination of the evolutionary effect.

The emission lines in elliptical galaxies are found much stronger than one would expect if the physical conditions are similar to those of HII regions.

Direct images of galaxies allow to trace the spiral structure defined by hot stars and to study the UV luminosity profile in the nuclear region.
Stellar Wind Theories
Authors: Hearn A. G.
Published: March 2016

The term stellar wind is used nowadays to describe any more or less continuous mass loss from a star. With the observations made with satellites in recent years it is becoming clear that most stars are undergoing this form of mass loss, though its magnitude can be very different from one star to another. The term stellar wind does not include the more eruptive forms of mass loss such as novae, the ejection of mass in shells or mass loss as a result of flares.

Stellar winds are maintained by energy and momentum deposited in the outer layers of a stellar atmosphere. The deposition of energy causes the heating of a chromosphere and corona, so that the theory of stellar winds cannot really be separated from the theory of coronal heating. Energy and momentum can both be deposited by the same mechanism. For example if a corona is heated by the dissipation of a wave which deposits energy, the same wave can change the momentum of the mean flow through wave pressure and this can happen even in the extreme case of no dissipation of the wave.

The foundation of the theory of stellar winds was laid by Parker (1958) in his theory of the solar wind. A useful review of this work has been given by Parker (1965). The theory of the solar wind in its simplest form is deduced from the equation of motion combined with the equations of continuity and state.
Mass-Loss From Spinning Stars
Authors: Sreenivasan S. R.
Published: March 2016

The effects of mass-loss and angular momentum loss on the evolution of massive stars are discussed bringing out the main results as well as the limitations of recent studies. It is pointed out that an acceptable theory of stellar winds in early as well as late type stars is needed as well as a satisfactory assessment of a number of instabilities in these contexts for an adequate understanding of the evolutionary consequences for a wide variety of population I and polulation II stars, which are affected by mass-loss.
By Draconis and RS Canum Venaticorum Stars: The Discoveries of Classical Photometry and Spectroscopy
Authors: Bopp Bernard W.
Published: March 2016

Physically quite dissimilar, the BY Dra and RS CVn stars have the common characteristic of extraordinarily high levels of stellar surface activity.

The RS CVn group, as defined by Hall, consists of detached binaries both components of types F, G, or K. The orbital periods are from a few days to a few weeks, and the mass ratios are generally near unity. Spectroscopically, the stars are remarkable in that they show very strong Ca II H and K emission outside eclipse. Masses and radii are known for many of these systems; physical parameters indicate these systems contain a moderately evolved subgiant, with mass slightly greater than 1 M⊚. The ages (which may be verified by data on visual companions) are a few 10 years.

In contrast, the BY Dra variables are late-type dwarfs, with spectral types ranging from dK5e to dM4e. The e designation indicates the presence of Balmer emission, which is generally visible in moderate strength at Ha and only very weakly present in the blue. The BY Dra stars do exhibit strong emission at H and K, however, and also show UV Ceti-type flares. Approximately 75% of the BY Dra variables are known as double-line spectroscopic binaries.
Radio Aspects of Stellar Activity in Close Binaries
Authors: Hjellming R. M.
Published: March 2016

Excluding single stars, star systems with very strong X-ray sources, thermally radiating winds and circumstellar envelopes, marginal detections, and binary systems that are far from “normal”, there are about 21 close binary systems that show clear signs of stellar activity in the form of variable radio emission. Sixteen of these are RS CVn binaries. Typical events are smoothly varying with time scales of from a few hours to a few days. In the RS CVn binaries UX Ari and V711 Tau variable circular polarization is sometimes observed, with occasional appearence of components with only one frequency and one circular polarization, part of which shows “oscillations” with “periods” of about 4 minutes. Different stars and different events typically have inferred electron energies of about 5 MeV and inferred magnetic fields of 1 - 30 Gauss. The radiation mechanisms are usually assumed to be synchrotron or gyro-synchrotron; however, radiation from plasma processes cannot be ruled out in some cases, and it will be very important to establish or rule out this possibility. Most radio binary events show clear signs of self-absorption, so the variations appear most strongly at the higher frequencies. Typical rise times of events are about 30% of decay times. Maximum radio luminosities range from 1013 to a few times 1017 ergs s-1 Hz-1. Most radio flares are mainly at cm-wavelenghts and have observable and inferred energies 104 - 106 times those for the largest solar events, a scaling which is similar to that for X-ray emission measures of these stars when compared to solar coronal loop emission measures. Most importantly, VLBI measurements of Algol indicate that the sizes of the radio emitting regions for very strong events are of the order of 2 - 3 stellar radii. Single stars appear to be active at radio wavelengths much less commonly than close binary systems. In many cases this may be due to the way dynamo action and convection near the surface are affected by increased rotation forced by the synchronization induced by the binary system.