bluuebunny/crossref_metadata_2025 huggingface dataset:
Molecular Mechanistic Reasoning: Toward Bridging the Gap Between the Molecular and Cellular Levels in Life Science Education
Authors: van MIL MARC H. W. , POSTMA PAULIEN A. , BOERWINKEL DIRK JAN , KLAASSEN KEES , WAARLO AREND JAN
Published: March 2016

Although learning about DNA, RNA, and proteins is part of the upper secondary biology curriculum in most countries, many studies report that students fail to connect molecular knowledge to phenomena at the higher level of cells, organs, and organisms. As a result, many students use memorization and rote learning as a coping strategy when presented with molecular‐level concepts. This study explores the potential of a new educational approach that aims at facilitating students to interpret animations and graphics of (sub)cellular processes as mechanistic explanations based on molecular interactions so as to bridge the explanatory gap between the molecular and cellular levels. The study presents the theoretical basis for a learning trajectory based on molecular mechanistic reasoning and shows in a small‐scale test of the educational approach that it is within reach for pre‐university students (aged 17–18 years) to interpret the visual models of (sub)cellular processes using a multilevel mechanistic perspective on (sub)cellular events. It is argued that this perspective helps students get to grips with cellular complexity in life science education.
Controlled Drug Release and Chemotherapy Response in a Novel Acoustofluidic 3D Tumor Platform
Authors: Zervantonakis Ioannis K. , Arvanitis Costas D.
Published: March 2016

Overcoming transport barriers to delivery of therapeutic agents in tumors remains a major challenge. Focused ultrasound (FUS), in combination with modern nanomedicine drug formulations, offers the ability to maximize drug transport to tumor tissue while minimizing toxicity to normal tissue. This potential remains unfulfilled due to the limitations of current approaches in accurately assessing and quantifying how FUS modulates drug transport in solid tumors. A novel acoustofluidic platform is developed by integrating a physiologically relevant 3D microfluidic device and a FUS system with a closed‐loop controller to study drug transport and assess the response of cancer cells to chemotherapy in real time using live cell microscopy. FUS‐induced heating triggers local release of the chemotherapeutic agent doxorubicin from a liposomal carrier and results in higher cellular drug uptake in the FUS focal region. This differential drug uptake induces locally confined DNA damage and glioblastoma cell death in the 3D environment. The capabilities of acoustofluidics for accurate control of drug release and monitoring of localized cell response are demonstrated in a 3D in vitro tumor mode. This has important implications for developing novel strategies to deliver therapeutic agents directly to the tumor tissue while sparing healthy tissue.
Superior Sodium Storage in 3D Interconnected Nitrogen and Oxygen Dual‐Doped Carbon Network
Authors: Wang Min , Yang Zhenzhong , Li Weihan , Gu Lin , Yu Yan
Published: March 2016

Carbonaceous materials have attracted immense interest as anode materials for Na‐ion batteries (NIBs) because of their good chemical, thermal stabilities, as well as high Na‐storage capacity. However, the carbonaceous materials as anodes for NIBs still suffer from the lower rate capability and poor cycle life. An N,O‐dual doped carbon (denoted as NOC) network is designed and synthesized, which is greatly favorable for sodium storage. It exhibits high specific capacity and ultralong cycling stability, delivering a capacity of 545 mAh g−1 at 100 mA g−1 after 100 cycles and retaining a capacity of 240 mAh g−1 at 2 A g−1 after 2000 cycles. The NOC composite with 3D well‐defined porosity and N,O‐dual doped induces active sites, contributing to the enhanced sodium storage. In addition, the NOC is synthesized through a facile solution process, which can be easily extended to the preparation of many other N,O‐dual doped carbonaceous materials for wide applications in catalysis, energy storage, and solar cells.
Chloride Ion Mediated Synthesis of Metal/Semiconductor Hybrid Nanocrystals
Authors: Hinrichs Dominik , Galchenko Michael , Kodanek Torben , Naskar Suraj , Bigall Nadja C. , Dorfs Dirk
Published: March 2016

A synthetic route to prepare metal–semiconductor hybrid nanoparticles is presented, along with the possibility to tune the ratio of primary to secondary nucleation and the morphology of the semiconductor material grown on the metal nanoparticle seeds. Gold and cobalt‐platinum nanoparticles are employed as metal seeds, on which CdS or CdSe is grown. Using transmission electron microscopy, absorption spectroscopy (UV–vis), and powder X‐ray diffraction as characterization techniques, a significant influence of chloride ions on the type of nucleation (that is, secondary or primary nucleation) as well as on the shape of the resulting heterostructures is observed. Partially replacing the commonly used cadmium precursor CdO by varying amounts of CdCl2 opens access to rod‐like, multiarmed, flower‐like, and bullet‐like structures. The results suggest that neither pure CdO nor pure CdCl2 as precursors but only a mixture of both make these structures obtainable. In this article, the influence of the chloride ion concentration during semiconductor growth on metal seeds is investigated in depth. The morphology of the resulting heterostructures is characterized carefully, and a growth mechanism is suggested. Furthermore, it is shown that this synthetic approach can be transferred to seeds of various metals such as platinum, gold, and cobalt platinum.
Preparing Teachers for Language Assessment: A Practice‐Based Approach
Authors: Davin Kristin J. , Heineke Amy J.
Published: March 2016

As the number of English language learners in mainstream classrooms increases, so too does the need for teachers skilled in classroom‐based language assessment (CBLA). All teachers must be able to monitor, evaluate, and support the English language development of their students. With a paucity of research on how to prepare teachers to enact ongoing, meaningful assessment of language development, this article describes how teacher candidates’ learning of CBLA was embedded into practice, responding to the question: How can teacher educators embed candidates’ professional learning of CBLA into practice across different course settings? The authors discuss the key elements of a practice‐based approach and describe how these elements were applied to the teaching of CBLA in both a controlled and a designed setting. The article concludes with teacher candidates’ reactions to this approach and recommendations for situating teacher learning of CBLA into practice.
A Critical Praxis: Narrowing the Gap Between Identity, Theory, and Practice
Authors: Waller Laurel , Wethers Kinsey , De Costa Peter I.
Published: March 2016

Praxis is the balance of pedagogical theory and practice. This literature review explores praxis from a critical lens in terms of identity for both students and teachers. The authors center their framework on Hawkins and Norton's (2009) five principles for critical language teaching. The first principle relates to the situated nature of the program and practices, which involves contextualizing the plot and the characters of the classroom. Second, responsiveness to learners encourages teachers to identify students’ multiple identities and allow them to experiment with these. Third, dialogic engagement is the discussion of identity in the classroom. Fourth, reflexivity requires teachers to examine their practices and the ideologies that guide their beliefs about second language acquisition and learning. Fifth, praxis combines all of these elements to create and harmonize a critical classroom. The article ends with a call for teacher training that incorporates these principles to better assist English language learners.
Total reflection X ray fluorescence in environmental and geochemical studies: unveiling solute provenance in streams during a rain episode
Authors: Rodríguez Castro M. C. , Vilches C. , Torremorell A. , Vázquez C. , Giorgi A.
Published: March 2016

Rural population uses water for irrigation, animal watering and for their own consumption, therefore water contamination is a major concern and a priority for its inhabitants. Unveiling the presence and source of contaminants can help to understand the dynamic of pollutants and therefore define management politics to address the issue. One way to elucidate the origin of contaminants in surface water is by studying rain episodes, relating water discharge with changes in solute concentration. Total Reflection x‐ray Fluorescence (TXRF) was used as the main analytical technique. The study was based on the analysis of samples originating from a Pampean stream (Buenos Aires, Argentina). Solutes (As, P, Ca, Fe, K, Zn, Br) were monitored before, during and after a storm event. During the monitoring it was observed that As was diluted at the beginning of the episode and concentration increased slowly after the rain ceased. The pattern of As is consistent with Ca, K and Fe behavior, revealing a groundwater source. Instead, P concentration increased in the early hours, it was diluted later and finally increased. This behavior indicates that the source of this analyte is superficial and sub superficial water, implying a runoff origin. The simultaneous determination of these analytes by TXRF allowed comparing solute behavior under the same episode, allowing reveal their provenance. Copyright © 2016 John Wiley & Sons, Ltd.
A novel conditional gene silencing method using a tumor-specific and heat-inducible siRNA system
Authors: Feng Jing , Wang Xiaoyu , Liao Yi , Feng Jianguo , Tang Liling
Published: March 2016

RNAi technology is an invaluable tool for investigating gene function. However, the non-temporal and non-spatial control is the primary limitation, which leads to siRNA leakiness and off-target effects. In this study, we inserted three kinds of HSE into tumor specific promoter hTERT, which aims to construct a temperature-inducible and tumor-specific RNAi plasmid vector. In our system, the expression of mature siRNA is tightly controlled by the heat shock-inducible and tumor-specific promoters. From the expression level of RNA and protein, we determined the efficiency of the inducible siRNA system by targeting SNCG gene in HepG2 and MCF-7 cells. Results showed that the controllable siRNA system could be induced to initiate siRNA expression by heat-induce. The silencing effect of SNCG is on a relative low level (10 %) at 37 °C, while it is significantly increased to 50 or 60 % after heat inducing at 43 °C. This new conditional siRNA system provides a novel approach to drive the siRNA expression by heat-inducible and tumor-specific promoter.
Professional Issues of International Genetic Counseling Students Educated in the United States
Authors: Akgumus Gozde , Shah Divya , Higgs Lydia , Valverde Kathleen
Published: March 2016

International students have unique personal and academic challenges during their training in genetic counseling programs across the United States (U.S.). Previous research has explored their motivations and experiences; however, there is scant research on how their international status affects the post‐graduate experience. The current study used semi‐structured phone interviews to explore the professional issues that international students face throughout their educational and professional careers. Twenty‐six participants were interviewed including international genetic counseling students in their second years of training and international genetic counselors who graduated from a U.S.‐accredited program. Participants included six, second‐year students, twelve genetic counselors employed in the U.S., six employed in Canada, and one employed in the United Kingdom (U.K.). Qualitative analysis of interviews captured the common experiences and challenges international students faced during their training and post‐graduation. Participants stated that they applied to programs in the U.S. because there is wide transferability of qualifications across the world, and there is limited or no opportunities for masters level genetic counseling training in their home country. Most participants who had applied for jobs in the U.S. experienced difficulties regarding unfamiliarity of human resources (HR) departments and Border Control Officers with international genetic counselors (GCs) and their visa requirements. The results suggest that currently there are insufficient job resources tailored to international genetic counselors, and an inadequate availability of peer support. The results also speak to the need to develop resources for prospective international students and for international GCs seeking jobs, and establishment of a peer support network. These resources may also provide assistance to genetic counseling training programs and employers to address the challenges faced by international genetic counselors.
Exclusive real‐time monitoring during recurrent laryngeal nerve dissection in conventional monitored thyroidectomy
Authors: Liu Xiao‐Li , Wu Che‐Wei , Zhao Yi‐Shen , Wang Tie , Chen Peng , Xin Jing‐Wei , Li Shi‐Jie , Zhang Da‐Qi , Zhang Guang , Fu Yan‐Tao , Zhao Li‐Na , Zhou Le , Dionigi Gianlorenzo , Chiang Feng‐Yu , Sun Hui
Published: March 2016

During conventional intermittent intraoperative neuromonitoring (IONM) in thyroidectomy, recurrent laryngeal nerve (RLN) injury is detected by an electromyographic (EMG) loss of signal (LOS) after the nerve dissection. Exclusive continuous monitoring during the phase of RLN dissection may be helpful in detecting adverse EMG changes earlier. A total of 208 RLNs at risk were enrolled in this study. Standardized IONM procedures were followed. We continuously stimulated the RLN at the lower exposed end with a stimulator to exclusively monitor the real‐time quantitative EMG change during RLN dissection. Once the amplitude decreased by more than 50% of the initial signal, the surgical maneuver was paused and the RLN was retested every minute for 10 minutes to determine amplitude recovery before restarting the dissection. The procedure was feasible in all patients. No LOS was encountered in this study. Nineteen RLNs had an amplitude reduction of more than 50%. Eighteen nerves showed gradual amplitude recovery (16 nerves had a traction injury and two nerves had a compression injury). After 10 minutes, the recovery was complete (i.e., >90%) in eight nerves, 70–90% in seven nerves, and 50–70% in three nerves. Among these 18 nerves, only one nerve developed temporary vocal palsy because it was exposed to unavoidable repeated nerve traction after restarting the dissection. Another nerve showed no gradual recovery from thermal injury, and developed temporary vocal palsy. The temporary and permanent palsy rates were 1% and 0%, respectively. During intermittent IONM, exclusive real‐time monitoring of the RLN during dissection is an effective procedure to detect an adverse EMG change, and prevent severe RLN injuries that cause LOS.
Review of heavy-ion inertial fusion physics
Authors: Kawata S. , Karino T. , Ogoyski A. I.
Published: March 2016

In this review paper on heavy ion inertial fusion (HIF), the state-of-the-art scientific results are presented and discussed on the HIF physics, including physics of the heavy ion beam (HIB) transport in a fusion reactor, the HIBs-ion illumination on a direct-drive fuel target, the fuel target physics, the uniformity of the HIF target implosion, the smoothing mechanisms of the target implosion non-uniformity and the robust target implosion. The HIB has remarkable preferable features to release the fusion energy in inertial fusion: in particle accelerators HIBs are generated with a high driver efficiency of ∼30%–40%, and the HIB ions deposit their energy inside of materials. Therefore, a requirement for the fusion target energy gain is relatively low, that would be ∼50–70 to operate a HIF fusion reactor with the standard energy output of 1 GW of electricity. The HIF reactor operation frequency would be ∼10–15 Hz or so. Several-MJ HIBs illuminate a fusion fuel target, and the fuel target is imploded to about a thousand times of the solid density. Then the DT fuel is ignited and burned. The HIB ion deposition range is defined by the HIB ions stopping length, which would be ∼1 mm or so depending on the material. Therefore, a relatively large density-scale length appears in the fuel target material. One of the critical issues in inertial fusion would be a spherically uniform target compression, which would be degraded by a non-uniform implosion. The implosion non-uniformity would be introduced by the Rayleigh-Taylor (R-T) instability, and the large density-gradient-scale length helps to reduce the R-T growth rate. On the other hand, the large scale length of the HIB ions stopping range suggests that the temperature at the energy deposition layer in a HIF target does not reach a very-high temperature: normally about 300 eV or so is realized in the energy absorption region, and that a direct-drive target would be appropriate in HIF. In addition, the HIB accelerators are operated repetitively and stably. The precise control of the HIB axis manipulation is also realized in the HIF accelerator, and the HIB wobbling motion may give another tool to smooth the HIB illumination non-uniformity. The key issues in HIF physics are also discussed and presented in the paper.
Circle of Willis Collateral During Temporary Internal Carotid Artery Occlusion II: Observations From Computed Tomography Angiography
Authors: Wang Bill Hao , Leung Andrew , Lownie Stephen P.
Published: March 2016

Introduction: The Circle of Willis (CoW) is the most effective collateral circulation to the brain during internal carotid artery (ICA) occlusion. Carotid stump pressure (CSP) is an established surrogate measure of the cerebral collateral circulation. This study aims to use hemodynamic and computed tomography angiography measurements to determine the strongest influences upon the dependent variable, CSP. These findings could help clinicians noninvasively assess the adequacy of the collateral circulation and facilitate surgical risk assessment in an outpatient setting. Methods: CSP and mean arterial pressure were measured during carotid endarterectomy or during carotid balloon test occlusion in 92 patients. Intracranial arterial diameters were measured on computed tomography angiography at 16 different locations. Univariate and multivariate analyses were used to determine the key factors associated with CSP. In a subgroup of individuals (n=27) with severe (>70% North American Symptomatic Carotid Endarterectomy Trial) contralateral stenosis or occlusion, the same analysis was performed. Results: The contralateral anterior cerebral artery proximal to anterior communicating artery (A1) of the CoW had the strongest influence upon CSP, followed by the mean arterial pressure, the contralateral ICA diameter, and the anterior communicating artery diameter (R2=0.364). In the subgroup with high-grade contralateral ICA stenosis, the ipsilateral posterior communicating artery exerted the strongest influence (R2=0.620). Conclusions: During ICA occlusion, the anterior CoW dominates in preserving collateral flow, especially the contralateral A1 segment. In individuals with high-grade contralateral carotid stenosis, the posterior communicating artery calibre becomes a dominant influence. The most favourable anatomy consists of large contralateral A1 and anterior communicating arteries, and no contralateral carotid stenosis.
Does the Movement Need a King?
Authors: LING PETER J.
Published: March 2016

Not every book sent for review comes with two pages of endorsements from the great and the good. Stokely is accompanied by glowing approval from such familiar names as Henry Louis Gates, Cornel West, Robin D. G. Kelley, Michael Eric Dyson, Gerald Horne, Charles Oglethorpe, and David Levering Lewis. Even without the para-textual apparatus to guide one's judgement, however, there is enough in this biography of Stokely Carmichael for any scholar of the civil rights movement to relish. This may not be the “definitive biography” that John Stauffer declares it to be, but it is indisputably important. In essence, Joseph argues that Stokely is the missing panel in a triptych of heroes, flanked on either side by the already canonized Malcolm X and Martin Luther King. In key respects, he insists, Stokely was the synthesis of Malcolm and Martin.
Subfields of R with arbitrary Hausdorff dimension
Authors: MAULDIN R. DANIEL
Published: March 2016

Assuming CH, the continuum hypothesis, holds we show, by completing an attack first discovered by Roy Davies, that for each α between 0 and 1 there is a subring, in fact a subfield, of R with Hausdorff dimension α.
A Convexity Property of Discrete Random Walks
Authors: NAGY GÁBOR V. , TOTIK VILMOS
Published: March 2016

We establish a convexity property for the hitting probabilities of discrete random walks in ${\mathbb Z}^d$ (discrete harmonic measures). For d = 2 this implies a recent result on the convexity of the density of certain harmonic measures.
Saturation in the Hypercube and Bootstrap Percolation
Authors: MORRISON NATASHA , NOEL JONATHAN A. , SCOTT ALEX
Published: March 2016

LetQddenote the hypercube of dimensiond. Givend⩾m, a spanning subgraphGofQdis said to be (Qd,Qm)-saturated if it does not containQmas a subgraph but adding any edge ofE(Qd)\E(G) creates a copy ofQminG. Answering a question of Johnson and Pinto [27], we show that for every fixedm⩾ 2 the minimum number of edges in a (Qd,Qm)-saturated graph is Θ(2d).

We also study weak saturation, which is a form of bootstrap percolation. A spanning subgraph ofQdis said to beweakly(Qd,Qm)-saturated if the edges ofE(Qd)\E(G) can be added toGone at a time so that each added edge creates a new copy ofQm. Answering another question of Johnson and Pinto [27], we determine the minimum number of edges in a weakly (Qd,Qm)-saturated graph for alld⩾m⩾ 1. More generally, we determine the minimum number of edges in a subgraph of thed-dimensional gridPkdwhich is weakly saturated with respect to ‘axis aligned’ copies of a smaller gridPrm. We also study weak saturation of cycles in the grid.
Neuropsychological Criteria for Mild Cognitive Impairment and Dementia Risk in the Framingham Heart Study
Authors: Jak Amy J. , Preis Sarah R. , Beiser Alexa S. , Seshadri Sudha , Wolf Philip A. , Bondi Mark W. , Au Rhoda
Published: March 2016

Objectives: To refine mild cognitive impairment (MCI) diagnostic criteria, we examined progression to dementia using two approaches to identifying MCI. Methods: A total of 1203 Framingham Heart Study participants were classified at baseline as cognitively normal or MCI (overall and four MCI subtypes) via conventional Petersen/Winblad criteria (single cognitive test impaired per domain, >1.5 SD below expectations) or Jak/Bondi criteria (two tests impaired per domain, >1 SD below norms). Cox proportional hazards models were constructed to examine the association between each MCI definition and incident dementia. Results: The Petersen/Winblad criteria classified 34% of participants as having MCI while the Jak/Bondi criteria classified 24% as MCI. Over a mean follow-up of 9.7 years, 58 participants (5%) developed incident dementia. Both MCI criteria were associated with incident dementia [Petersen/Winblad: hazards ratio (HR) = 2.64; p-value=.0002; Jak/Bondi: HR=3.30; p-value <.0001]. When both MCI definitions were included in the same model, only the Jak/Bondi definition remained statistically significantly associated with incident dementia (HR=2.47; p-value=.008). Multi-domain amnestic and single domain non-amnestic MCI subtypes were significantly associated with incident dementia for both diagnostic approaches (all p-values <.01). Conclusions: The Jak/Bondi MCI criteria had a similar association with dementia as the conventional Petersen/Winblad MCI criteria, despite classifying ~30% fewer participants as having MCI. Further exploration of alternative methods to conventional MCI diagnostic criteria is warranted. (JINS, 2016, 22, 937–943)
Radio Emission from Interstellar Hydrogen Cyanide and X-ogen
Authors: Snyder Lewis E. , Buhl David
Published: March 2016

Radio emission spectra from the J = 1−0 transition of H12C14N and H13C14N, two molecular isotopes of hydrogen cyanide, have been detected at 88.6 and 86.3 GHz, respectively. In addition, an emission signal from a new and unidentified interstellar molecule was detected at 89.2 GHz. The new molecule temporarily has been named ‘X-ogen’ until its chemical identity can be determined. X-ogen has been detected in several regions and may be as common as hydrogen cyanide in the Galaxy.
Magnetic Multipole Transition Probabilities
Authors: Garstang R. H.
Published: March 2016

A review is given of the occurrence and transition probabilities of spectrum lines arising from magnetic quadrupole radiation. Magnetic dipole radiation in relativistic quantum mechanics is also discussed.
Some Astrophysical Aspects of Pulsars
Authors: Woltjer L.
Published: March 2016

In principle the formation rate can be obtained on the basis of a knowledge of a spatial densities and lifetimes. Extreme care is needed, however because of the incompleteness of the available sample because of luminosity effects. Since luminosity and age are correlated it is essential that densities and lifetimes be evaluated for the same sample. Incompleteness affects the very faint pulsars most strongly, but because of their long lifetime the effect on the formation rate is comparatively small. We shall assume that the lifetime of a pulsar in our sample is on the average equal to twice its age. Further we estimate distances (r) from dispersion measures on the basis of a mean electron density ne of 0.05 cm−3 near the Sun. The fluctuations in ne again may cause systematic errors, but no information is available for an estimate of the magnitude of these.

There are 5 pulsars known with r cosb (b galactic latitude) less than 100 pc. For three of these ages are available from which a harmonic mean life time T of 2.5 × 107 yr is found. Of 19 pulsars with r cos b < 300 pc, eight have ages from which T= 1.1 × 107 yr. Samples with larger r cos b appear to be too incomplete for our purpose. Taking the Galaxy to be a uniform disk with a radius of 14 kpc, we obtain from both samples a formation rate of about one pulsar per 250 yr. It should be stressed that this is the rate for ‘visible’ pulsars. If beaming effects cause only a fraction η to be in principle observable, the formation rate is to be multiplied by η−1.
The Cosmic Background Radiation: Some Recent Developments
Authors: Rees M. J.
Published: March 2016

Diffuse background radiation has been detected over 16 decades of frequency - from a few MHz up to ~3 × 1016 MHz (100 MeV) - and there are upper limits over an even wider range. Generally an important contribution comes from the galactic disc, but in some wavebands it has proved possible to isolate a truly cosmic isotropic component originating beyond our own Galaxy. A simple Olbers-type argument shows that the bulk of any extragalactic radiation field originates at cosmological distances. This is true whether the radiation is emitted by discrete sources, or comes from extragalactic (or pregalactic) space. Thus studies of the isotropie background radiation, or even upper limits to its intensity, yield data that are vital for cosmology, as well as telling us something about the properties of diffuse intergalactic matter, and about intrinsically faint extragalactic objects which cannot be observed individually.

In this talk I shall not attempt a systematic review of this extensive subject, but will merely discuss a few recent developments. I shall give special attention to the microwave and X-ray regions of the spectrum, as these are the two bands in which the cosmic background is so strong that it swamps the emission from the Galaxy.
Absolute Magnitudes of RR Lyrae Variables
Authors: Clube S. V. M.
Published: March 2016

My remarks concern the kinematics of a-type RR Lyrae variables with large ∆s(≥5), supposedly halo members, which have relatively well determined proper motions (μ) and radial velocities (ϱ) as well as accurate photoelectric photometry (m). The number of variables fulfilling these criteria is about 60. Using procedures which need not be discussed in detail here, it is possible to determine the statistical kinematic properties of these stars - that is, their solar motion (υ) and velocity dispersion (σ) - in two different ways:
Optical and Radio Information
Authors: Johnson Hugh M.
Published: March 2016

The six or eight optically identified X-ray sources comprise starlike objects and extended supernova remnants in the Galaxy, well as as a radio galaxy and a quasar. Both X-ray and radiofrequency radiation penetrate the entire galactic plane, but only two or three galactic radio sources have been identified with X-ray sources. This has led Hayakawa et al. to postulate that detectable X-ray sources are not farther than 1 kpc. However, other studies suggest that there is a cluster of a few intrinsically bright sources actually near the galactic nucleus and a scattering of weaker sources near the sun.

The distances of X-ray sources can be estimated from extinction by interstellar gas or intergalactic gas on spectra above 10 Å, but the method ultimately depends on the radio and optical data of the gas. Conversely, interstellar densities of certain elements with large photo-ionization cross-sections may be determined from the absorption of X-rays, after calibration of source distances by the methods of optical astronomy.
The Formation of Li, Be, B Isotopes by the Spallation of CNO
Authors: Gradsztajn E.
Published: March 2016

In 1955 Fowler et al. (1955) suggested that the elements Li, Be and B could be produced at the surface of some stars by the spallation of CNO induced by electromagnetically accelerated particles.

Since that time many observational data were gathered, not only on the lithium elemental abundance (Hunger, 1957; Bonsack and Greenstein, 1960), but also concerning the isotopic ratio 7Li/6Li (Herbig, 1964; Wallerstein, 1965). Then, the abundance of beryllium in many stars was measured (Bonsack, 1960; Conti and Danziger, 1966; Merchant, 1966) and the problem was, and still is to explain both 7Li/6Li and Li/Be ratios. In addition to spallation, different possibilities may be invoked, such as the inheritance from galactic gas enriched with matter remaining from a previous generation of stars, or from the big bang; but which can be checked most easily at the present time is the spallation assumption. Indeed, simultaneously with the development of the observations on stars, a program for measuring and calculating the production rates of the light elements has been in progress at Orsay. In 1960 the first experimental result concerning the production of 6Li in 16O by 156 MeV protons was obtained. But it was only in 1965 that the number of experimental and theoretical data on spallation was sufficient to make a valid comparison with abundances observed on the stars as well as in the solar system or in cosmic rays.
The Evolution of Close Binaries and the Formation of the Wolf-Rayet Stars
Authors: Paczyński Bohdan
Published: March 2016

I shall discuss here the evolution of massive binaries in the case B. In this case the initially more massive component fills up the Roche lobe after the exhaustion of hydrogen in the core. By a massive binary I understand the binary in which the phase of a rapid mass exchange is terminated by helium ignition in the core of the initially more massive star. The helium ignition stops the contraction of the core and the expansion of the envelope of that component. In a small mass star the degeneracy plays the role of helium ignition in this respect. The last case will be discussed by Dr. A. Weigert in his lecture.
Investigation of Possible Abundance Anomalies in Close Binaries of Spectral Types A0-A2 & F5-F6
Authors: Kondo Yoji
Published: March 2016

This investigation was originally conceived as a follow-up on a work by Abt (1965), in which he finds the close binaries, with periods of about 1–100 days, and with spectral types of about A4-F2 (IV-V), to be all Am stars. The stars to be observed were chosen from the ‘Fifth Catalogue of the Orbital Elements of Spectroscopic Binary Stars’ (Moore and Neubauer, 1948). The criteria in making the selection were that the spectral types are A0-A2 and F5-F6 (IV-V) and that the periods are between about 1–100 days.

Spectra of 11 binary systems were obtained at the Coude focus of the 84-inch reflector of the Kitt Peak National Observatory during three nights in May 1967. In addition to the binary stars, 5 standard spectrum stars, i.e. α Lyr (A0V), θ Leo (A2V), σ Boo (F2 V), ι Peg (F5 V) and 110 Her (F6 V), were observed to provide comparisons. The dispersion used was 13·5 Å/mm. Typically 2 or 3 spectra were obtained for each object. A spot densitometer was employed to furnish calibrations for the plates.
The Evolution of Close Binaries and the Am Stars
Authors: Conti Peter S.
Published: March 2016

In this paper, I shall be concerned with three related questions: (a) what is the evolutionary fate of close binary systems, (b) is this concept consistent with the number of evolved close binary systems, and (c) are these evolved systems the Am stars?
The Coordination of Ground-Based and Space Observations: Summary
Authors: de Jager C.
Published: March 2016

We briefly summarize the main contents of the papers presented by the contributors to the present Joint Discussion. Partly the remarks refer to the spacecraft payload, partly they aim at improving the ground observing facilities.
The Next Decade in Stellar Atmospheres Theory
Authors: Delache P.
Published: March 2016

It is a pity for all of us that Dimitri Mihalas was unable to come to Sydney, and I wish, in the first place, to thank him for suggesting this discussion, devoted to a prospective study of our research field. There falls to me the task of trying to sketch what might be the axis of progress in stellar atmosphere theory. This subject is preeminently one which belongs to D. Mihalas; I am afraid that we are going to miss him now more than ever. Furthermore, I feel myself in a bad position for talking on such a large subject, in front of specialists, while I know so little on it. However, I have accepted the task, at the request of the President of Commission 36, with the goal of giving some physical considerations that may initiate reflections and discussions.

I am not going, in principle, to give a set of topics whose study should be desirable, or possible, arranged according to the internal logic of a specialist of stellar atmospheres, neither shall I look for bibliographical signs allowing the prediction of active zones or flares in our next cycle of activity!
The Space Density of Faint M-Dwarfs
Authors: Oort J. H.
Published: March 2016

Donna Weistrop, a student of Maarten Schmidt’s, has found evidence for an unexpectedly high space density of very faint M-dwarfs. This was confirmed by Murray and Sanduleak. The space density inferred from these investigations is comparable to, or possibly higher than, the local gas density. Because there is evidence that the stars concerned are young this appears to present a problem.

As the investigation by Murray and Sanduleak is the simpler and more direct of the two I confine my discussion to this. The authors determined proper motions for 21 M dwarfs down to 17m found in an objective-prism survey at the Warner and Swasey Observatory in regions close to the North Galactic Pole. The distance of the stars can be inferred from the reflection of the solar motion. Assuming the ‘basic’ solar motion they found and a space density of 0.23 pc-3 for these stars, corresponding with a mass density of about 0.04 M⊚ pc-3. This is exceedingly high, in view of the fact that the average gas density near z = 0 is only 0.03 M⊚ pc-3. The problem is aggravated by the fact that the stars have low velocities, the dispersion in velocity in one coordinate coming out ± 10kms-1. This is considerably lower than the velocity dispersion of A-type stars, and shows that the stars are young, perhaps about 108 yr. How is it then that the gas has not been completely used up long ago?
On the Growth of the Earth-Moon System
Authors: Whipple F. L.
Published: March 2016

This paper elaborates the postulate that the Earth and Moon became a binary system during their accretional development and that the Moon’s growth was essentially completed before the assumed solar nebula dissipated. The solar nebula was still hot enough at the formation of the two bodies that both consisted largely of the refractory and relatively low-density minerals now characteristic of the Moon. During the subsequent condensation, agglomeration and accretion of siderophile and more volatile higher density minerals, the Earth grew very much faster than the Moon because of (a) its much greater gravitational capture area coupled with retention by a sizeable atmosphere and (t>) the Moon’s velocity, with respect to the solar nebula, which produced a wind that aerodynamically blew away volatiles and smaller debris resulting from hypervelocity impacts of larger planetesimals. This ‘impact differentiation’ process favored the retention of the refractory minerals on the Moon (Figure 1). The Moon’s surprisingly high moment of inertia follows naturally from the basic postulate.
Evidence for Lunar-Type Objects in the Early Solar System
Authors: Urey H. C.
Published: March 2016

Objects of the solar system, in addition to the Sun, can be classified into four groups -the planets, objects of lunar mass, smaller objects of variable mass and the comets.

If the solar proportion of gases relative to non-volatile compounds of the variety in the terrestrial planets, namely about 300 times the mass of these elements, were added to the terrestrial planets, they would have masses comparable to those of the major planets. Mercury is low in mass but has a high density, indicating that it has lost several times its mass of silicate materials relative to high density metallic iron. If this were restored and then the component of gases were added, it would also fall into the group rather naturally. Mars appears to be rather small. Uranus and Neptune have rather high densities indicating some loss of gases, probably hydrogen and helium. When we attempt to estimate the mass of primitive solar material from which the planets were evolved, we conclude that they evolved from very similar masses. Later, I shall argue that the process was a very inefficient one.
Soft X-Ray Observations of Supernova Remnants
Authors: Zarnecki J. C. , Culhane J. L. , Fabian A. C. , Rapley C. G. , Boyd R.L.F. , Parkinson J. H. , Silk R.
Published: March 2016

Observations of a number of supernova remnants have been carried out with the low energy X-ray telescope on the Copernicus satellite. Data are presented on the X-ray structure of the remnants Cassiopeia A and Puppis-A. Marginal detections or new upper limits are reported for the remnants IC443, DR4, MSH15-52A, Downes 83, Downes 84 and 3C392.
L’astronomie Infrarouge et les Poussieres Galactiques.
Authors: Pecker Jean-Claude
Published: March 2016

The existence, in the Galaxy, of small absorbing dust grains has been known for a long time, as they redden the light of stars located behind them, and obscure by amounts which can often even be several magnitudes… In the infrared, where absorption is smaller, one can see through the dust, while at the same time, one can observe the emission of cold dust clouds. After a brief review of technical developments, the reasons for studying the infrared, and the principles of diagnostics, are given. The analysis of the spectral features leads to identification of ice, graphite, and various silicates, as main constituents of the dust. In the fifth section, examples are given of the various sources that one meets when travelling in the Galaxy: protostars, cold and dilute, dense envelopes of young stars (cold or hot), dilute envelopes of not so young stars, and ejected clouds surrounding evolved objects… The simultaneous observation of dust, molecules and atoms, in the same regions, shows that the knowledge of the circumstellar dense regions might be of a great interest, in the study of the origin of life, and of the evolution of the Universe.
The Dynamical Evolution of Clusters of Galaxies
Authors: White Simon D.M.
Published: March 2016

Typical orbital periods for galaxies in rich clusters are observed to be several billion years. Consequently these large systems have had little time to come to equilibrium, and indeed if they formed from small initial density perturbations they must have taken a substantial fraction of the age of the Universe to separate from the Hubble flow and recollapse (Gunn and Gott 1972). Despite the relatively short time available, dynamical effects can cause appreciable evolution both in the distribution of galaxies within clusters and in the observable features of individual galaxies. The overall aspect of a cluster changes as violent relaxation irons out in homogeneities and establishes a relaxed core-halo structure. At the same time collisional relaxation causes massive galaxies to lose energy to lighter objects in an attempt to reach equipartition of kinetic energy, and to spiral towards the cluster centre. These processes are relatively easy to analyse in any particular scheme for cluster formation, and below we concentrate on comparing their predicted effects with observation.
Density Law, Vertical Distribution and Vertical Gradient of Metal Abundances for G and K Giants
Authors: Grenon M.
Published: March 2016

A systematic photometric investigation on stars of spectral type G4toK4is performed in both polar caps insymmetric coaxialcones. According to a calibration of the Geneva system, Mv, Teff and [M/H] ratio have been now derived for about 4OO stars. For the computation of density law, a special care has been taken to avoid selection biaises related to variations of mean age or metal abundance. A change of luminosity function for evolved stars in function of z has been detected. Using the geometrical properties of the cones and direct counts in the solar vicinity, we derive the following density law for stars with Mv ∊ [0.0, 1.3] and (B-V) ∊ [0.7, 1.3]
Parallaxes of Selected Stars Near the North Galactic Pole
Authors: Strand K. Aa. , Dahn C. C. , Harrington R. S.
Published: March 2016

As a contribution toward settling the question of the distances of Murray-Sanduleak (M-S) stars (Murray and Sanduleak, 1972), two of these stars were added to the U. S. Naval Observatory (USNO) program in 1973. After the initial plates had been taken, it appeared that parallax for an additional star could be measured on one series, while parallaxes for two additional stars were possible from the second. As a result provisional parallaxes are now available, Table I.

In terms of USNO parallaxes, these are considered provisional because they are based on half the number of plates on which the final parallaxes are ordinarily determined; only small changes are expected when additional material is added beyond the present.
Swedish Programmes Concerning the Z Distribution of Stars
Authors: Oja Tarmo
Published: March 2016

Swedish investigations on stellar space distribution generally are based on the Uppsala - Stockholm spectral classification system. In this system the properties of the stars are derived from objective prism spectra by means of narrow-band photometry. The main criteria are the hydrogen-line intensities, the intensity of the K line, the intensity of the G band, the break at the G band, and the intensity of the blue cyanogen band (for a description of the system see e.g. Ljunggren and Oja, 1961), when possible supplemented by a measure of the Balmer discontinuity (Rydström, 1976). The method yields absolute magnitudes with a dispersion of about and intrinsic colours (B-V)° with a mean error below for most kinds of stars.

Three investigations are relevant to the subject of this Joint Discussion.
The Heterogeneity of Surfaces of Magnetic AP Stars
Authors: Hack M.
Published: March 2016

The observations of spectrum-variability and light-variability of Ap stars are reviewed. It is shown that these variations are interpretable as due to the changing aspect of the spotted surface as the star rotates. It is stressed that we understand fairly well the geometry of the phenomenon but the physics is very far from being understood.

Magnetic Ap stars are probably those where the presence of a spotted surface is very evident. Their spectrum-variability (profiles, line-intensity and radial velocity), light-variability and magnetic field variability, all occurring with the same period, are explained in a simple way if we assume that these variations are due to the changing aspect of the spotted surface as the star rotates. The oblique rotator model was proposed by Babcock in 1949 and by Stibbs in 1950 and was worked out in great detail by Deutsch (1954). This model allows us to explain the magnetic field variation from some + 1000 to some - 1000 gauss in a few days; it explains the crossover effect, the line-width versus period relations, the line - intensity and radial velocity variation, and in part also the light curves. The main objection against the oblique rotator hypothesis was the supposed existence of many irregularly variable magnetic stars. However, the large number of observations accumulated in the last twenty years indicates that probably all magnetic Ap spectrum-variables are regular variables with periods which are generally of a few days, but includes a small group of long period variables (100 days up to 23 years for HD 9996). The light variability, which is the quantity measurable with the highest precision, has often remained undetected, because the amplitude is always small, in many cases few hundreths of magnitude.
Starspots on by Dra-Type Stars
Authors: Evans D. S.
Published: March 2016

The first detection of spots on dwarf M stars was by Kron on YY Geminorum in 1948. Since then phenomena attributable to starspots have been found by numerous authors beginning with Kraft and Krzeminski on the star now known as BY Draconis and on CC Eridani by Evans. There is a close correlation between spottedness, Balmer emission and flaring in dwarf M stars. Evans appears to have been the first to attempt to analyse the small range light variations on spotted stars in terms of modulation caused by axial rotation. In comparison with the solar case one must assume that the spots are very large and long lived. There is also an ambiguity in dealing with very large dark spots as between a star with a dark area or a cool star with a bright area (the zebra effect— is a zebra a black animal with white stripes or a white animal with black stripes?). It is difficult to arrive at a solution for the spot parameters which is unique. In particular several analyses which have appeared have assumed that maximum light corresponds to the immaculate star whereas in fact the maximum light in the variation corresponds to the immaculate star dimmed by the light of any constant star abstraction.
Optical Spectra of Nuclei of Early Type Galaxies
Authors: Schnur Gerhard F. O. , Sherwood W. A.
Published: March 2016

Early type galaxies classified as SO by Sandage or lenticulars and SO/a appearing in RCBG have been observed with the IDS on the ESO 3.6 m telescope. The slit was 1” × 4” and the spectral resolution was 9 Å from 3900 Å to 7000 Å. Statistics for the first 50 galaxies observed are given.

18% of the sample show the [OIII] doublet stronger than Hß; 32% have spectra dominated by the Balmer series progressing from mainly emission through strong absorption series to weak absorption; 20% have only [NII] or [SII] in emission while 30% show absorption lines and bands. That is, 70% show emission lines toward the nuclear region. Among the 50 galaxies, HI at 21 cm has been detected in 21 galaxies: 16 of these show ionized gas to be present. NGC5273 has Seyfert characteristics with strong [OIII]; Hß has a width of ˜1000 kms-1. The low luminosity end of the Seyfert distribution may be found among normal galaxies.