bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Calculation of the Nutations
Authors: Vicente R. O. 
Published: March 2016

It is well known that the knowledge of precession and nutation is essential for the computation of astronomical coordinates and the comparison of values obtained at different dates. It is therefore important to compute the nutations from the best available observations.Unfortunately, there are not many long series of reliable observations that can be used for the calculation of the several nutations. Nowadays, we need more accurate values and, therefore, it is fundamental to have observations reduced in an homogeneous way. For this purpose, Commission 19 (Rotation of the Earth) set up a ‘Working Group on Pole Coordinates’, during the last IAU meeting in 1970 (Vicente, 1972), with the objective of reducing the 70 years of variation of latitude observations done by the International Latitude Service (called the International Polar Motion Service at the present time) that constitute a remarkable set of astronomical data. It is expected to obtain more reliable values for the coordinates of the pole and be able to calculate the nutations.The Working Group on Pole Coordinates is transferring to punched cards all the observations registered in the original observation books and that involves nearly 2 million cards. This work has been hampered by financial difficulties, but it should be supported by the international astronomical community in order to obtain the best results from so many years of observations, done by international cooperation.The theoretical researches done in the last decades have shown that the values of the nutations depend on the structure of the Earth (Jeffreys and Vicente, 1957). Lately, the researches done in seismology have resulted in a better knowledge about the structure of the Earth, leading to the setting up of many Earth models due to the availability of computers. This fact has led to the situation where one cannot propose better theoretical values for the nutations because they depend on the model adopted for the structure of the Earth.
The Principle of Least Interaction Action
Authors: Ovenden M. W. 
Published: March 2016

AbstractThe intuitive notion that a satellite system will change its configuration rapidly when the satellites come close together, and slowly when they are far apart, is generalized to ‘The Principle of Least Interaction Action’, viz. that such a system will most often be found in a configuration for which the time-mean of the action associated with the mutual interaction of the satellites is a minimum. The principle has been confirmed by numerical integration of simulated systems with large relative masses. The principle lead to the correct prediction of the preference, in the solar system, for nearly-commensurable periods. Approximate methods for calculating the evolution of an actual satellite system over periods ˜ 109 yr show that the satellite system of Uranus, the five major satellites of Jupiter, and the five planets of Barnard’s star recently discovered, are all found very close to their respective minimum interaction distributions. Applied to the planetary system of the Sun, the principle requires that there was once a planet of mass ˜ 90 Mθ in the asteroid belt, which ‘disappeared’ relatively recently in the history of the solar system.
Supernovae: The Ultimate Instability
Authors: Kirshner Robert P. 
Published: March 2016

Observed properties of supernovae and of very young supernova remnants provide important clues to answer the question, “which stars become supernovae?” There are three general lines of evidence (l) the statistics of supernovae, (2) the physical state of supernovae near maximum light, and (3) the chemistry of young supernova remnants. These lines of evidence appear to be converging on the view that all the supernova explosions we see, whether Type I or Type II, arise from the destruction of young massive stars.It is important to note that supernovae fall into two distinct spectroscopic classes: Type I which does not show strong hydrogen lines, and Type II in which hydrogen emission and absorption is prominent (Oke and Searle, 1974). It is possible that the stellar progenitors of these two types are very different, but recent evidence suggests that the similarities in the properties of the two classes are more important.
Introduction
Authors: van der Laan H. 
Published: March 2016

In the summer of 1977 the IAU General Secretary requested proposals for Joint Discussions at the XVIIth General Assembly more than two years later. As President of Commission 40 I wrote to other Commission Presidents proposing a J.D. on Extragalactic High Energy Astrophysics. The motivation was as follows, and I quote from my July 22, 1977 letter:“With the current advances in radio and optical techniques and the tremendous progress to be expected from the satellites HEAO-A and HEAO-B, to be launched respectively in the summer of 1977 and 1978, there should be a good deal of new material on high energy astrophysical phenomena in the extragalactic domain by the time of the 1979 General Assembly. Some of this will be of great cosmological significance and all of it will be astrophysically interesting. It is clear that the X-ray satellite results will get a lot of optical and radio follow-up and it therefore seems appropriate that a Joint Discussion of that topic be arranged at that time.”
X-Ray Variability in Active Galaxy Nuclei and Quasars in less than One Day
Authors: Elvis M. , Feigelson E. , Griffiths R. E. , Henry J. P. , Tananbaum H. 
Published: March 2016

Active galaxy-X-ray sources are well known to be variable on timescales of days to years (Ricketts, et al. 1977, Mushotzky, et al. 1979, Lawrence 1979). Here we present some new data from the Einstein Observatory which shows that these sources also vary in less than one day, on timescales of hours. Large luminosity changes in such short times promise to allow the investigation of the physics of such sources in several new ways. We shall give some examples of how this can be begun. This is only a preliminary report of this work. A full account will be given elsewhere.The Einstein Observatory (Giacconi, et al. 1979) is capable of exploring this regime of variability because its imaging capability gives it two unique advantages. Firstly, the background rate in one beam area is negligible so that intensity determinations are limited only by Poisson counting statistics. Secondly, the background counts in the remainder of the field can be integrated to give a simultaneous monitor with the same instrument of cosmic ray and background X-ray events. Thus, any peculiarities in detector behaviour, telemetry or software can be traced and separated from real source variations. This is a significant advantage and gives us a great deal more confidence in our results. Many sources do not show variability. For example, in our data, Cen A is constant to ˜ 2% over 1 day.
The Concept of Old Stellar Populations
Authors: Lyngå Gösta 
Published: March 2016

Almost 25 years ago Walter Baade told the Vatican conference about the meaning of stellar populations:“We also understand now why the two stellar populations, either singly or combined, are such conspicuous features in most galaxies. They are age groups which represent two significant phases of the star formation in galaxies.”There appeared a straight-forward picture with an old, metal-poor halo containing stars in elongated galactic orbits and a younger disk population, where the stars have near solar abundances and near circular orbits. The central bulge of the galaxy was considered part of the older system.New observations have made the picture more complex and also more controversial, indicating that it still might not be fully understood. Stars in the bulge of our spiral galaxy have been shown to have rather high contents of heavy elements. The gas and perhaps also the stars of the disk show a metal content that is decreasing outwards in the disk. The abundances in globular clusters differ widely between individual clusters and even between individual stars of the same cluster. It has become clear that one must discuss separately the different heavy elements; that some abundances may be considered primordial and thus characteristic of the evolution of the stellar population, whereas other abundance differences may be caused by mixing into the stellar envelopes.
Women-Astronomers of Former Ussr
Authors: Rykhlova L.V. 
Published: March 2016

Astronomy is a very popular science in Russia, but officially it is considered rather a man’s speciality because of night observations, laborious measurements, developments of new facilities, etc.At present there are about 35% women among specialists with higher astronomical education. The indicator of professional level is for women often higher then for men at this stage of career. Unfortunately this level remains the limit for most women-astronomers, because the possibility of farther promotion and higher position depends on family-status, home-life, having children, etc. That is why only 30% women have the first scientific degree, about 5%, the second scientific degree, and only a few individuals, the title of Professor.As a consequence the most difficult part of this exciting science falls on women-astronomers: monotonous observations and calculations for astrometrical catalogues, processing of spectral information reduction of data, data bank management, and others. This is the most labour - intensive and ungrateful part of astronomical research that can not produce results ready for publication at relatively short times.
Opacities in Strong Magnetic Helds
Authors: Wickramasinghe Dayal T. 
Published: March 2016

White dwarfs are one of the most readily studied end products of stellarevolution. Their observed properties have provided and continue to provide important constraints for the theory of stellar evolution. Likewise, a study of magnetism in white dwarfs provides unique insights into the origin and evolution of magnetic fields in stars.Spectacular progress has been made on the specific problem of the structure of the hydrogen atom in strong fields. Energy levels and transition probabilities are now known for all low lying states of hydrogen for the entire range of field strengths appropriate to white dwarfs and neutron stars (104-1013G) (Rosner et al 1984, Forster et al 1984 and Henry and O’Connell 1984). These calculations resulted in the identification of spectral features in the magnetic white dwarf Grw+70°8247 which had remained unidentified for over 50 years (Minkowski 1938), with Zeeman shifted hydrogen lines in a magnetic field of 100 -320 MG ((eg Wickamasinghe and Ferrano 1989). Several other strong field magnetic white dwarfs have since been discovered through hydrogen Zeeman spectroscopy. The data presently at hand show that most hydrogen rich magnetic white dwarfs have complex non-dipolar field structures with strong evidence for higher order multipole components.
Analysis of the Secular Variations of Longitudes of the Sun, Mercury and Venus from Optical Observations
Authors: Kolesnik Y.B. 
Published: March 2016

AbstractAbout 240 000 optical observations of the Sun, Mercury and Venus, accumulated during the era of classical astrometry from Bradley up to our days, are incorporated to analyse the secular variation of the longitudes of innermost planets. A significant discrepancy between modern ephemerides and optical observations is discovered. The possible sources of discrepancy are discussed. The tidal acceleration of the Moon has been revised to conform the lunar theory with the ephemerides of the planets. The offset and residual rotation of Hipparcos-based system with respect to the dynamical equinox is determined. Interpretation of this rotation is given.
Radio Observations of High Energy Solar Flares
Authors: Kundu Mukul R. 
Published: March 2016

AbstractIn this paper we discuss some recent observations of radio emission produced by high energy electrons resulting from solar flares. We discuss the spatial structure of simple weak spiky burst emissions observed simultaneously, at 17 and 34 GHz with the Nobeyama Radio Heliograph (NoRH). Using simultaneous imaging observations obtained by Yohkoh/HXT and SXT along with NoRH17 & 34 GHz observations, we attempt to model a relatively stronger and longer flare using gyrosynchrotron mechanism for the flaring radio emission.
The Magnetic Field of the Milky Way
Authors: Reid Mark J. 
Published: March 2016

AbstractModels of the magnetic field configuration of the Milky Way are reviewed. Current analyses of rotation measure data suggest that the Milky Way possesses a bisymmetric-like spiral magnetic field, that field reversals among spiral arms exist, and that the magnetic spiral may not closely match the mass spiral structure. Zeeman measurements of OH masers may provide alternative magnetic field information.
Formation and Evolution of Massive Black Holes in Star Clusters
Authors: Baumgardt Holger , Makino Junichiro , Zwart Simon Portegies 
Published: March 2016

AbstractWe present results of N-body simulations on the formation of massive black holes by run-away merging in young star clusters and the later dynamical evolution of star clusters containing massive black holes. We determine the initial conditions necessary for run-away merging to form a massive black hole and study the equilibrium profile that is established in the cluster center as a result of the interaction of stars with the central black hole. Our results show that star clusters which contain black holes have projected luminosity profiles that can be fitted by standard King models. The presence of massive black holes in (post-)core collapse clusters is therefore ruled out by our simulations.
Solar Composition of Icy Planetesimals: A New Source For Comet Nuclei?
Authors: Owen Tobias 
Published: March 2016

The enrichment of heavy elements on Jupiter appears to require the existence of a new class of icy planetesimal that exhibits solar relative abundances.Prior to the Galileo probe mission, observations of methane in Jupiter’s atmosphere had revealed that C/H was approximately three times the solar ratio. This enrichment was thought to be the result of the delivery of heavy elements by icy planetesimals, which were assumed to be essentially identical to comets. However, comets are notoriously deficient in nitrogen (e.g., Geiss 1987; Krankowsky 1991) and recent upper limits on argon in three comets (Weaver et al. 2002) indicate that this element is also sub-solar relative to O. Hence it was assumed that Jupiter would exhibit the same deficiency in argon and nitrogen relative to carbon (Pollack and Bodenheimer 1989; Owen & Bar-Nun 1995). Yet the mass spectrometer on the Galileo Probe clearly showed that Ar, Kr, Xe, N, C, and S are all enriched in Jupiter’s atmosphere by the same factor of 3 ± 1 (Niemann et al. 1998; Owen et al. 1999).
Physics of Solar-Like Oscillations
Authors: Christensen-Dalsgaard Jørgen 
Published: March 2016

AbstractThe physics of solar and stellar oscillations determine their observable characteristics. I provide a brief overview of the properties of solar-like oscillations, excited by stochastic processes, in other stars. In addition, I consider the current state of investigations of such oscillations, as well as the prospects for an improved understanding of their physics and the properties of the pulsating stars.
Renal cell carcinoma escapes death by p53 depletion through transglutaminase 2-chaperoned autophagy
Authors: Kang J H , Lee J-S , Hong D , Lee S-H , Kim N , Lee W-K , Sung T-W , Gong Y-D , Kim S-Y 
Published: March 2016

AbstractIn renal cell carcinoma, transglutaminase 2 (TGase 2) crosslinks p53 in autophagosomes, resulting in p53 depletion and the tumor’s evasion of apoptosis. Inhibition of TGase 2 stabilizes p53 and induces tumor cells to enter apoptosis. This study explored the mechanism of TGase 2-dependent p53 degradation. We found that TGase 2 competes with human double minute 2 homolog (HDM2) for binding to p53; promotes autophagy-dependent p53 degradation in renal cell carcinoma (RCC) cell lines under starvation; and binds to p53 and p62 simultaneously without ubiquitin-dependent recognition of p62. The bound complex does not have crosslinking activity. A binding assay using a series of deletion mutants of p62, p53 and TGase 2 revealed that the PB1 (Phox and Bem1p-1) domain of p62 (residues 85–110) directly interacts with the β-barrel domains of TGase 2 (residues 592–687), whereas the HDM2-binding domain (transactivation domain, residues 15–26) of p53 interacts with the N terminus of TGase 2 (residues 1–139). In addition to the increase in p53 stability due to TGase 2 inhibition, the administration of a DNA-damaging anti-cancer drug such as doxorubicin-induced apoptosis in RCC cell lines and synergistically reduced tumor volume in a xenograft model. Combination therapy with a TGase 2 inhibitor and a DNA-damaging agent may represent an effective therapeutic approach for treating RCC.
Zyxin-Siah2–Lats2 axis mediates cooperation between Hippo and TGF-β signalling pathways
Authors: Ma Biao , Cheng Hongcheng , Gao Ruize , Mu Chenglong , Chen Ling , Wu Shian , Chen Quan , Zhu Yushan 
Published: March 2016

AbstractThe evolutionarily conserved Hippo pathway is a regulator that controls organ size, cell growth and tissue homeostasis. Upstream signals of the Hippo pathway have been widely studied, but how microenvironmental factors coordinately regulate this pathway remains unclear. In this study, we identify LIM domain protein Zyxin, as a scaffold protein, that in response to hypoxia and TGF-β stimuli, forms a ternary complex with Lats2 and Siah2 and stabilizes their interaction. This interaction facilitates Lats2 ubiquitination and degradation, Yap dephosphorylation and subsequently activation. We show that Zyxin is required for TGF-β and hypoxia-induced Lats2 downregulation and deactivation of Hippo signalling in MDA-MB-231 cells. Depletion of Zyxin impairs the capability of cell migration, proliferation and tumourigenesis in a xenograft model. Zyxin is upregulated in human breast cancer and positively correlates with histological stages and metastasis. Our study demonstrates that Zyxin-Lats2–Siah2 axis may serve as a potential therapeutic target in cancer treatment.
Early ERK1/2 activation promotes DRP1-dependent mitochondrial fission necessary for cell reprogramming
Authors: Prieto Javier , León Marian , Ponsoda Xavier , Sendra Ramón , Bort Roque , Ferrer-Lorente Raquel , Raya Angel , López-García Carlos , Torres Josema 
Published: March 2016

AbstractDuring the process of reprogramming to induced pluripotent stem (iPS) cells, somatic cells switch from oxidative to glycolytic metabolism, a transition associated with profound mitochondrial reorganization. Neither the importance of mitochondrial remodelling for cell reprogramming, nor the molecular mechanisms controlling this process are well understood. Here, we show that an early wave of mitochondrial fragmentation occurs upon expression of reprogramming factors. Reprogramming-induced mitochondrial fission is associated with a minor decrease in mitochondrial mass but not with mitophagy. The pro-fission factor Drp1 is phosphorylated early in reprogramming, and its knockdown and inhibition impairs both mitochondrial fragmentation and generation of iPS cell colonies. Drp1 phosphorylation depends on Erk activation in early reprogramming, which occurs, at least in part, due to downregulation of the MAP kinase phosphatase Dusp6. Taken together, our data indicate that mitochondrial fission controlled by an Erk-Drp1 axis constitutes an early and necessary step in the reprogramming process to pluripotency.
Quantitative non-invasive cell characterisation and discrimination based on multispectral autofluorescence features
Authors: Gosnell Martin E. , Anwer Ayad G. , Mahbub Saabah B. , Menon Perinchery Sandeep , Inglis David W. , Adhikary Partho P. , Jazayeri Jalal A. , Cahill Michael A. , Saad Sonia , Pollock Carol A. , Sutton-McDowall Melanie L. , Thompson Jeremy G. , Goldys Ewa M. 
Published: March 2016

AbstractAutomated and unbiased methods of non-invasive cell monitoring able to deal with complex biological heterogeneity are fundamentally important for biology and medicine. Label-free cell imaging provides information about endogenous autofluorescent metabolites, enzymes and cofactors in cells. However extracting high content information from autofluorescence imaging has been hitherto impossible. Here, we quantitatively characterise cell populations in different tissue types, live or fixed, by using novel image processing and a simple multispectral upgrade of a wide-field fluorescence microscope. Our optimal discrimination approach enables statistical hypothesis testing and intuitive visualisations where previously undetectable differences become clearly apparent. Label-free classifications are validated by the analysis of Classification Determinant (CD) antigen expression. The versatility of our method is illustrated by detecting genetic mutations in cancer, non-invasive monitoring of CD90 expression, label-free tracking of stem cell differentiation, identifying stem cell subpopulations with varying functional characteristics, tissue diagnostics in diabetes and assessing the condition of preimplantation embryos.
Landscape of genomic diversity and trait discovery in soybean
Authors: Valliyodan Babu , Dan Qiu  , Patil Gunvant , Zeng Peng , Huang Jiaying , Dai Lu , Chen Chengxuan , Li Yanjun , Joshi Trupti , Song Li , Vuong Tri D. , Musket Theresa A. , Xu Dong , Shannon J. Grover , Shifeng Cheng , Liu Xin , Nguyen Henry T. 
Published: March 2016

AbstractCultivated soybean [Glycine max (L.) Merr.] is a primary source of vegetable oil and protein. We report a landscape analysis of genome-wide genetic variation and an association study of major domestication and agronomic traits in soybean. A total of 106 soybean genomes representing wild, landraces and elite lines were re-sequenced at an average of 17x depth with a 97.5% coverage. Over 10 million high-quality SNPs were discovered and 35.34% of these have not been previously reported. Additionally, 159 putative domestication sweeps were identified, which includes 54.34 Mbp (4.9%) and 4,414 genes; 146 regions were involved in artificial selection during domestication. A genome-wide association study of major traits including oil and protein content, salinity and domestication traits resulted in the discovery of novel alleles. Genomic information from this study provides a valuable resource for understanding soybean genome structure and evolution and can also facilitate trait dissection leading to sequencing-based molecular breeding.
Long range recognition and selection in IDPs: the interactions of the C-terminus of p53
Authors: Kannan Srinivasaraghavan , Lane David P. , Verma Chandra S. 
Published: March 2016

AbstractThe C-terminal domain of p53 is an extensively studied IDP, interacting with different partners through multiple distinct conformations. To explore the interplay between preformed structural elements and intrinsic fluctuations in its folding and binding we combine extensive atomistic equilibrium and non-equilibrium simulations. We find that the free peptide segment rapidly interconverts between ordered and disordered states with significant populations of the conformations that are seen in the complexed states. The underlying global folding-binding landscape points to a synergistic mechanism in which recognition is dictated via long range electrostatic recognition which results in the formation of reactive structures as far away as 10 Å and binding proceeds with the steering of selected conformations followed by induced folding at the target surface or within a close range.