bluuebunny/crossref_metadata_2025 huggingface dataset:
ROBUST FORECAST COMPARISON
Authors: Jin Sainan , Corradi Valentina , Swanson Norman R.
Published: October 2016

Forecast accuracy is typically measured in terms of a given loss function. However, as a consequence of the use of misspecified models in multiple model comparisons, relative forecast rankings are loss function dependent. In order to address this issue, a novel criterion for forecast evaluation that utilizes the entire distribution of forecast errors is introduced. In particular, we introduce the concepts of general-loss (GL) forecast superiority and convex-loss (CL) forecast superiority; and we develop tests for GL (CL) superiority that are based on an out-of-sample generalization of the tests introduced by Linton, Maasoumi, and Whang (2005,Review of Economic Studies72, 735–765). Our test statistics are characterized by nonstandard limiting distributions, under the null, necessitating the use of resampling procedures to obtain critical values. Additionally, the tests are consistent and have nontrivial local power, under a sequence of local alternatives. The above theory is developed for the stationary case, as well as for the case of heterogeneity that is induced by distributional change over time. Monte Carlo simulations suggest that the tests perform reasonably well in finite samples, and an application in which we examine exchange rate data indicates that our tests can help identify superior forecasting models, regardless of loss function.
Diplopods as Soil Bioindicators of Toxicity After Application of Residues From Sewage Treatment Plants and Ethanol Industry
Authors: Christofoletti Cintya A. , Francisco Annelise , Pedro-Escher Janaína , Gastaldi Vinícius D. , Fontanetti Carmem S.
Published: October 2016

Residues like sewage sludge and vinasse have been reused as agricultural fertilizers, but they also present a potential to contaminate soils. Diplopods have been considered excellent bioindicators of soil contamination. In the present study,Rhinocricus padbergiwere used to assess toxicity in samples of sewage sludge, biosolids, and sugarcane vinasse. The behavioral analysis, mortality rate, and histological, histochemical, and ultrastructural analyses of the midgut of diplopods were the parameters evaluated. Behaviorally, some diplopods avoided burying themselves after 30 days in soil with biosolid or vinasse. Besides, certain residue combinations were able to cause death of all individuals between 60 and 90 days of exposure. The main tissue responses were significant brush border thickening, induction of epithelial renovation, clustering of hemocytes, accumulation of cytoplasmic granules in hepatic cells, hepatic cells with heteropycnotic nuclei, and cytoplasmic degradation. Alterations were observed at various levels among treatments with different samples and exposure times. Ultrastructural analysis revealed elongation of microvilli coated with a layer of an amorphous substance, resulting in a thicker brush border as observed in the histological analysis. After 30 days of exposure, animals showed an accumulation of spherocrystals in hepatic cells and high absorption of substances, based on the elongation of microvilli. Results obtained in the chemical analysis and the behaviors observed in diplopods suggest that animals processed the residues. Therefore, caution should be exercised in the disposal of these residues in agriculture.
Spectroscopic and Microscopic Study of Peroxyformic Pulping of Agave Waste
Authors: Hernández-Hernández Hilda M. , Chanona-Pérez Jorge J. , Vega Alberto , Ligero Pablo , Farrera-Rebollo Reynold R. , Mendoza-Pérez Jorge A. , Calderón-Domínguez Georgina , Vera Norma Güemes
Published: October 2016

The peroxyformic process is based on the action of a carboxylic acid (mainly formic acid) and the corresponding peroxyacid. The influences of processing time (60–180 min), formic acid concentration (80–95%), temperature (60–80°C), and hydrogen peroxide concentration (2–4%) on peroxyformic pulping of agave leaves were studied by surface response methodology using a face-centered factorial design. Empirical models were obtained for the prediction of yield,κnumber (KN) and pulp viscosity as functions of the aforementioned variables. Mathematical optimization enabled us to select a set of operational variables that produced the best fractionation of the material with the following results: pulp yield (26.9%), KN (3.6), and pulp viscosity (777 mL/g). Furthermore, this work allowed the description and evaluation of changes to the agave fibers during the fractionation process using different microscopic and spectroscopic techniques, and provided a comprehensive and qualitative view of the phenomena occurring in the delignification of agave fibers. The use of confocal and scanning electron microscopy provided a detailed understanding of the microstructural changes to the lignin and cellulose in the fibers throughout the process, whereas Raman spectroscopy and X-ray diffraction analysis indicated that cellulose in the pulp after treatment was mainly of type I.
Dynamical Problems in Extrasolar Planetary Science
Authors: Morbidelli Alessandro , Haghighipour Nader
Published: October 2016

The past few years have witnessed a large increase in the number of extrasolar planets. Thanks to successful surveys from the ground and from space, there are now over 1000 confirmed exoplanets and more then 3000 planetary candidates. More than 130 of these systems host multiple planets. Many of these systems demonstrate physical and orbital characteristics fundamentally different from those of our solar system. The challenges associated with the diversity of planetary systems have raised many interesting questions on planet formation and orbital dynamics.
The Effect of Convective Overstability on Planet Disk Interactions
Authors: Klahr Hubert , Gomes Aiara Lobo
Published: October 2016

We run global two dimensional hydrodynamical simulations, using the PLUTO code and the planet-disk model of Uribe et al. 2011, to investigate the effect of the convective overstability (CO) on planet-disk interactions. First, we study the long-term evolution of planet-induced vortices. We found that the CO leads to smoother planetary gap edges, thus weaker planet-induced vortices. The main result was the observation of two generation of vortices, which can pose an explanation for the location of the vortex in the Oph IRS48 system. The lifetime of the primary vortices, as well as the birth time of the secondary vortices are shown to be highly dependent on the thermal relaxation timescale. Second, we study the long-term evolution of the migration of low mass planets and assess whether the CO can prevent the saturation of the horseshoe drag. We found that the disk parameters that favour slow inward or outward migration oppose the amplification of vortices, meaning that the CO does not seem to be a good mechanism to prevent the saturation of the horseshoe drag. On the other hand, we observed a planetary trap, caused by vortices formed in the horseshoe region. This trap may be an alternative mechanism to prevent the fast type I migration rates.
The Diversity of Low-mass Exoplanets Characterized via Transit Timing
Authors: Jontof-Hutter Daniel , Ford Eric B. , Rowe Jason F. , Lissauer Jack. J. , Fabrycky Daniel C.
Published: October 2016

Transit timing variations (TTV) in multi-transiting systems enables precise characterizations of low-mass planets and their orbits. The range of orbital periods and incident fluxes with detailed TTV constraints complements the radial velocity sample for low-mass planets, pushing exoplanet characterization to the regime sub-Earth size planets and out to Mercury-like distances. This has revealed an astonishing diversity in the density of super-Earth mass planets. We summarize these and other contributions to exoplanet science from TTVs.
Establishing the credibility of archaeoastronomical sites
Authors: Ruggles Clive
Published: October 2016

In 2011, an attempt to nominate a prehistoric “observatory” site onto the World Heritage List proved unsuccessful because UNESCO rejected the interpretation as statistically and archaeologically unproven. The case highlights an issue at the heart of archaeoastronomical methodology and interpretation: the mere existence of astronomical alignments in ancient sites does not prove that they were important to those who constructed and used the sites, let alone giving us insights into their likely significance and meaning. The fact that more archaeoastronomical sites are now appearing on national tentative lists prior to their WHL nomination means that this is no longer just an academic issue; establishing the credibility of the archaeoastronomical interpretations is crucial to any assessment of their value in heritage terms.
An artificial Kepler dichotomy? Implications for the coplanarity of planetary systems
Authors: Bovaird Timothy , Lineweaver Charles H.
Published: October 2016

We challenge the assumptions present in previous efforts to model the ensemble of detected Kepler systems, which require a dichotomous stellar population of ‘fertile’ and ‘sterile’ planet producing stars. We remove the assumption of Rayleigh distributed mutual inclinations between planets and show that the need for two distinct stellar populations disappears when the inner part of planetary disks are assumed to be flat, rather than flared.
Kepler Reliability and Occurrence Rates
Authors: Bryson Steve ,   The Kepler Team
Published: October 2016

The Kepler mission has produced tables of exoplanet candidates (“KOI table”), as well as tables of transit detections (“TCE table”), hosted at the Exoplanet Archive (http://exoplanetarchive.ipac.caltech.edu). Transit detections in the TCE table that are plausibly due to a transiting object are selected for inclusion in the KOI table. KOI table entries that have not been identified as false positives (FPs) or false alarms (FAs) are classified as planet candidates (PCs, Mullally et al. 2015). A subset of PCs have been confirmed as planetary transits with greater than 99% probability, but most PCs have <99% probability of being true planets. The fraction of PCs that are true transiting planets is the PC reliability rate. The overall PC population is believed to have a reliability rate >90% (Morton & Johnson 2011).
Significance of periodogram peaks
Authors: Süveges Maria , Guy Leanne , Zucker Shay ,   the Gaia CU7 team
Published: October 2016

Three versions of significance measures or False Alarm Probabilities (FAPs) for periodogram peaks are presented and compared for sinusoidal and box-like signals, with specific application on large-scale surveys in mind.
Chemical diversity in the comet population
Authors: Biver Nicolas , Bockelée-Morvan Dominique
Published: October 2016

For the last 3 decades, infrared and microwave techniques have enabled the detection of up to 27 parent molecules in the coma of comets. Several molecules have been detected in over 40 different comets. A large diversity of composition is seen in the sample, comprising comets of various dynamical origins. Abundances relative to water for the molecules can vary by a factor 3 to more than 10. The taxonomic study of a sample of comets in which the abundance of several molecules (e.g., HCN, CH3OH, CO, CH4, C2H6, H2S, H2CO, CH3CN, CS, . . .) has been measured does not show any clear grouping. Except for fragments of a common parent comet, every observed comet shows a different composition. The absence of any clear correlation between the volatile content of the comets and their dynamical origin (Kuiper Belt versus Oort Cloud) is consistent with a common origin for these two populations. Their diversity in composition may also suggest that radial and temporal mixing in the early proto-planetary nebula may have played an important role.
Icy Dwarf Planets: Colored Popsicles in the Outer Solar System
Authors: Pinilla-Alonso Noemi
Published: October 2016

We update the list of candidates to be considered by the IAU as dwarf planets using the criterium suggested by Tancredi & Favre (2008). We add here the information collected in the last 10 years (mostly the sizes and albedos by the herschel hey program TNOs Are Cool). We compare the physical characteristics of these candidates with the physical characteristics of the rest of the TNOs. Our goal is to study if there are common physical properties among the candidates that enable the identification of a dwarf planet.
Water-Rock Differentiation of Icy Bodies by Darcy law, Stokes law, and Two-Phase Flow
Authors: Neumann Wladimir , Breuer Doris , Spohn Tilman
Published: October 2016

The early Solar system produced a variety of bodies with different properties. Among the small bodies, objects that contain notable amounts of water ice are of particular interest. Water-rock separation on such worlds is probable and has been confirmed in some cases. We couple accretion and water-rock separation in a numerical model. The model is applicable to Ceres, icy satellites, and Kuiper belt objects, and is suited to assess the thermal metamorphism of the interior and the present-day internal structures. The relative amount of ice determines the differentiation regime according to porous flow or Stokes flow. Porous flow considers differentiation in a rock matrix with a small degree of ice melting and is typically modelled either with the Darcy law or two-phase flow. We find that for small icy bodies two-phase flow differs from the Darcy law. Velocities derived from two-phase flow are at least one order of magnitude smaller than Darcy velocities. The latter do not account for the matrix resistance against the deformation and overestimate the separation velocity. In the Stokes regime that should be used for large ice fractions, differentiation is at least four orders of magnitude faster than porous flow with the parameters used here.
CO isotopologue ratios in the solar photosphere
Authors: Lyons James R. , Gharib-Nezhad Ehsan , Ayres Thomas R.
Published: October 2016

We re-evaluate the CO dipole moment function in order to obtain more accurate isotope ratios for the solar photosphere using previous infrared observations. We used a new set of dipole moments from HITEMP which were accurately determined by both semi-empirical and ab initio methods. Preliminary values of isotope ratios using the new dipole moments are in better agreement with the inferred photosphere values from Genesis, showing that the solar photosphere is isotopically similar to primitive inclusions in meteorites.
Laboratory constraints on ice formation, restructuring and desorption
Authors: Öberg Karin I.
Published: October 2016

Ices form on the surfaces of interstellar and circumstellar dust grains though freeze-out of molecules and atoms from the gas-phase followed by chemical reactions. The composition, chemistry, structure and desorption properties of these ices regulate two important aspects of planet formation: the locations of major condensation fronts in protoplanetary disks (i.e. snow lines) and the formation efficiencies of complex organic molecules in astrophysical environments. The latter regulates the availability of prebiotic material on nascent planets. With ALMA it is possible to directly observe both (CO) snowlines and complex organics in protoplanetary disks. The interpretation of these observations requires a detailed understanding of the fundamental ice processes that regulate the build-up, evolution and desorption of icy grain mantles. This proceeding reviews how experiments on thermal CO and N2 ice desorption, UV photodesorption of CO ice, and CO diffusion in H2O ice have been used to guide and interpret astrochemical observations of snowlines and complex molecules.
Laboratory and theoretical work applied to planetary atmospheres
Authors: Coustenis Athena
Published: October 2016

We look at applications of recent work in theoretical and experimental spectroscopy for the analysis of IR data concerning giant planets, Titan and possibly exoplanets.
Sun-like Stars: magnetic fields, cycles and exoplanets
Authors: Fares Rim
Published: October 2016

In Sun-like stars, magnetic fields are generated in the outer convective layers. They shape the stellar environment, from the photosphere to planetary orbits. Studying the large-scale magnetic field of those stars enlightens our understanding of the field properties and gives us observational constraints for field generation dynamo models. It also sheds light on how “normal” the Sun is among Sun-like stars. In this contribution, I will review the field properties of Sun-like stars, focusing on solar twins and planet hosting stars. I will discuss the observed large-scale magnetic cycles, compare them to stellar activity cycles, and link that to what we know about the Sun. I will also discuss the effect of large-scale stellar fields on exoplanets, exoplanetary emissions (e.g. radio), and habitability.
Preface - Focus Meeting 20: Astronomy for Development
Authors: Govender Kevin
Published: October 2016

This Focus Meeting was about the global developmental impact that all aspects related to astronomy can deliver. The interdisciplinary nature of the meeting made it relevant to all IAU Divisions and the professional astronomy community in general. The manner in which the strategic plan has been designed and the way in which OAD implements it allows for input and innovation from the professional community both to develop the astronomy field globally and to stimulate the developmental benefits arising from the astronomy field. IAU members have played a key role in every stage of implementation of the strategic plan, from its ratification, through to strong participation in its implementation. This meeting served to report back to them in terms of progress, as well as seek input from them in terms of shaping the way forward.
The new Andean Regional Office of Astronomy for Development
Authors: Char Farid , Forero-Romero Jaime
Published: October 2016

The Andean Regional Office of Astronomy for Development (ROAD) is a new effort in South America to serve several goals in astronomical development. The six countries in the Andean ROAD (Bolivia, Colombia, Chile, Ecuador, Peru and Venezuela) represent a common language block in the region. They work together to develop strategies to strengthen the professional research, education and popularization of astronomy. Our current Working Structure comprises a ROAD Coordinator and one Coordinators in each Task Force. Here we describe the main points of the ROAD's current action plan.
Planetary nebulae as kinematic tracers of galaxy halos
Authors: Coccato Lodovico ,   PNS collaboration
Published: October 2016

The kinematics and dynamical properties of galaxy stellar halos are difficult to measure, given the faint surface brightness that characterizes these regions. Gas-rich systems such as spiral galaxies can be probed using the radio Hi emission. Early-type galaxies contain less gas, therefore alternative kinematic tracers need to be used. Planetary Nebulae (PNe) can be easily detected far out in the halo thanks to their bright [O iii] emission at 5007 Å. It is therefore possible to map the halo kinematics also in early-type galaxies, typically out to 5 effective radii or beyond. Thanks to the recent spectroscopic surveys targeting extra-galactic PNe, we can now rely on few tens of galaxies where the kinematics of the stellar halos are measured. I will discuss the most important results: (a) the relation of the stellar surface brightness and the PNe number density; (b) the velocity and velocity dispersion two-dimensional fields; (c) the radial profiles of angular momentum; and (d) the relation between the derived kinematics physical properties of the host galaxies.
FM5. The Legacy of Planck
Authors: Tauber Jan A. ,   on behalf of the Planck Collaboration
Published: October 2016

This paper is an introduction to Focus Meeting 5 held at the IAU's General Assembly held in Honolulu in August 2015. It describes the rationale for the meeting, and summarizes the introductory talk to FM5, which contained a description of the Planck data products released by ESA and the Planck Collaboration in the first half of 2015.
Galaxy cluster cosmology from X-ray surveys of the hot and energetic Universe
Authors: Clerc Nicolas , Sartoris Barbara , Dolag Klaus , Vijayaraghavan Rukmani , Biffi Veronica
Published: October 2016

We discuss recent advances and prospects in our understanding of the formation of structures on cosmic scales based on surveys of galaxy clusters in the X-ray bands. We highlight the interaction between observations and numerical simulations of the X-ray sky. We show how future surveys will unveil the nature of the dark energy and study its evolution with time.
IAU Focus Meeting 7: Stellar Physics in Galaxies throughout the Universe
Authors: Leitherer Claus , Charlot Stéphane , Maraston Claudia
Published: October 2016

A 3-day Focus Meeting entitled “Stellar Physics in Galaxies throughout the Universe” was held during the IAU XXIX General Assembly. The meeting brought together astrophysicists from the stellar physics, extragalactic astrophysics and cosmology communities to discuss how current and future results can foster progress in these disjoint science areas. Areas covered include stellar evolution of single and binary stars from the zero-age main-sequence to the terminal stage, the feedback of stars to the interstellar medium via radiation, dust production and chemical enrichment, and the properties of the most massive stars and of cosmologically significant stellar phases such as AGB and Wolf-Rayet stars. The limitations of our understanding of the physics of local stars and their effects on, e.g., ages, chemical composition and the initial mass function of galaxies at low to high redshift were evaluated.
The Carbon Stars Adventure
Authors: Rau Gioia , Paladini C. , Hron J. , Aringer B. , Eriksson K. , Groenewegen M. A. T. , Nowotny W.
Published: October 2016

We compare in a systematic way spectrometric, photometric and mid-infrared (VLTI/MIDI) interferometric measurements with different types of model atmospheres. Self-consistent dynamic model atmospheres in particular were used to interpret in a consistent way the dynamic behavior of gas and dust. The results underline how the joint use of different kind of observations, as photometry, spectroscopy and interferometry, is essential to understand the atmospheres of pulsating C-rich AGB stars. The sample of C-rich stars discussed in this work provides crucial constraints for the atmospheric structure.
Stellar yields – theory and observations
Authors: Karakas Amanda I.
Published: October 2016

Stellar yields are an essential tool for studies of chemical evolution. For low and intermediate-mass stars (0.8 up to 8-10M⊙) the richest nucleosynthesis occurs when the stars are on the asymptotic giant branch (AGB) of stellar evolution. We discuss the main nucleosynthesis outcomes, along with the uncertainties that affect the theoretical calculations. The uncertainties in the physics can be improved by comparing theoretical models to observations, including chemically peculiar metal-poor stars, along with AGB stars and their progeny.
Determining the fraction of dust heating from young and old stellar populations with 3D dust radiative transfer
Authors: Natale Giovanni , Popescu Cristina C. , Tuffs Richard. J. , Debattista Victor P. , Fischera Jörg , Grootes Meiert W.
Published: October 2016

A major difficulty hampering the accuracy of UV/optical star formation rate tracers is the effect of interstellar dust, absorbing and scattering light produced by both young and old stellar populations (SPs). Although empirically calibrated corrections or energy balance SED fitting are often used for fast de-reddening of galaxy stellar emission, eventually only radiative transfer calculations can provide self-consistent predictions of galaxy model spectra, taking into account important factors such as galaxy inclination, different morphological components, non-local heating of the dust and scattered radiation. In addition, dust radiative transfer can be used to determine the fraction of monochromatic dust emission powered by either young or old SPs. This calculation needs to take into account the different response of the dust grains to the UV and optical radiation field, depending on the grain size and composition. We determined the dust heating fractions, on both global and local scales, for a high-resolution galaxy model by using our 3D ray-tracing dust radiative transfer code “DART-Ray”. We show the results obtained using this method and discuss the consequences for star formation rate indicators.
Age derivation from UV absorption indices and the effect of the UV upturn
Authors: Le Cras Claire , Maraston Claudia , Thomas Daniel
Published: October 2016

We exploit stellar population models of absorption features in the ultraviolet to assess their power in determining the age of the stellar population in galaxies. We focus in particular on features that can differentiate between an old UV-bright population, contributing to the UV upturn, and a young population due to recent star formation. We use a system of 8 indices between 2200 - 3200Å, tracing several chemical elements including Mg and Fe. We apply these models to a large sample of z ~ 0.6 massive galaxies from the Sloan Digital Sky Survey (SDSS) - III / Baryon Oscillation Spectroscopic Survey (BOSS) to derive the ages of the UV-bright populations. We find a subset of indices to be non-degenerate between old and young UV ages allowing us to find evidence for old stars contributing to the UV, rather than new star formation. We find up to 84% of our working sample (274,661 galaxies) to contain a contribution from old UV-bright stars. Those found to have higher contributing mass fractions being on average more massive and redder then those with lower mass fractions.
IMF variations in unresolved stellar populations: Challenges
Authors: Ferreras Ignacio , La Barbera Francesco , Vazdekis Alexandre
Published: October 2016

This talk focuses on the challenges facing the recent discovery of variations of the stellar initial mass function in massive early-type galaxies, with special emphasis on the constraints via gravity-sensitive spectral features.
Ionising photon budget in galaxies
Authors: Östlin Göran ,   the LARS team
Published: October 2016

Understanding the production of ionising photons in galaxies, how these photons propagate, ionise and heat the interstellar medium and possibly leak out of their host galaxies is key to understand many aspects of galaxy evolution and their contribution to reionisation. I will outline some projects currently undertaken to investigate the ionising photon budget.
Are LGRBs biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of LGRBs
Authors: Vergani Susanna D. ,   collaborators
Published: October 2016

Long gamma-ray bursts (LGRBs) are associated to the deaths of massive stars and could thus be used as a potentially powerful tool to trace cosmic star formation. However the conditions needed to produce a LGRBs may introduce a bias in the LGRB rate versus star formation rate (SFR) relation (called LGRB efficiency hereafter).

We have undertaken a study of the properties of the host galaxies of the BAT6 complete sample of LGRB to improve our knowledge on the LGRB efficiency, its redshift evolution, and the factor affecting it. This is the base to properly use LGRBs as SFR tracers.

We show that at z < 1 LGRBs are not direct SFR tracers because they tend to avoid high-metallicity galaxies. The use of the BAT6 complete sample keeps this result from being affected by possible biases that could have influenced past results based on incomplete samples. The preference for low (but not extremely low) metallicities can be a consequence of the particular conditions needed for the progenitor star to produce a GRB.
On the kinematics of neutral gas in GRB host galaxies
Authors: Arabsalmani M. , Møller P. , Freudling W. , Zafar T. , Fynbo J. P. U. , Christensen L. , Savaglio S.
Published: October 2016

We analyze a sample of 20 absorption systems intrinsic to long duration GRB host galaxies at z > 2 forwhich the metallicities are known. We compare the relation between the metallicity and cold gas velocity width for thissample to that of the Damped Lyman-alpha systems (DLAs) in the sight-lines of quasars (QSOs), and find completeagreement. We then compare the redshift evolution of the velocity-metallicity relation of our sample to that of QSODLAsand find that also GRB hosts favour a late onset of this evolution, around a redshift of ~2.6. We compute predicted stellar masses for the GRB host galaxies using the prescription determined from QSO-DLAsamples and compare the measured stellar masses for the four hosts where stellar masses have been determinedfrom SED fits. We find excellent agreement and conclude that, on basis of all available data and tests, long durationGRB-DLA hosts and intervening QSO-DLAs are consistent with being drawn from the same underlying population.
The CALIFA survey: Oxygen abundances
Authors: Sánchez S. F. ,   the CALIFA collaboration
Published: October 2016

We present here the last results we obtained on the spatial resolved analysis of the ionized gas of disk-dominated galaxies based on CALIFA data. CALIFA is an ongoing IFS survey of galaxies in the Local Univese (0.005 < z < 0.03) that has already obtained spectroscopic information up to ~2.5re with a spatial resolution better than ~1 kpc for a total number of an statiscal sample of galaxies of different morphological types, covering the CM-diagram up to Mr<−18 mag. With nearly 2000 spectra obtained for each galaxy, CALIFA offer one of the best IFU data to study the starformation histories and chemical enrichment of galaxies. In this article we focus on the main results based on the analysis of the oxygen abundances based on the study of ionized gas in H ii regions and individual spaxels, and their relations with the global properties of galaxies. In summary we have found that: (1) the $\mathcal{M}$-Z relation does not present a secondary relation with the star-formation rate, when the abundance is measured at the effective radius; (2) the oxygen abundance present a strong correlation with the stellar surface density (Σ-Z relation); (3) the oxygen abundance profiles present three well defined regimes, (a) an overall negative radial gradient, between 0.5-2 re, with a characteristic slope of αO/H∼-0.1 dex/re, (b) an universal flatenning beyond >2re and (c) an inner drop at <0.5re which presence depends on the mass. All these results indicates that disk-galaxies present an overall inside-out growth, although with clear deviations from this simple scenario.
Spatially-resolved imaging of stripped-envelope supernova environments
Authors: Van Dyk Schuyler D.
Published: October 2016

Stripped-envelope supernovae (SNe), i.e., those of Type Ib, Ic, and IIb, arise from massive progenitor stars which have had most or all of their outer hydrogen-rich layers removed before explosion by some process, either through a strong stellar wind or through binary mass transfer. The connection between some long-duration gamma-ray bursts (GRBs) and broad-lined Type Ic SNe makes a broader discussion of stripped-envelope SNe and their environments particularly relevant. If the SN progenitor itself cannot be directly identified, it is possible that examination of its immediate environment can provide some insight into the nature of the progenitor. It is also possible that revisiting the SN site sufficiently late enough after explosion could reveal the presence of a binary companion. I will present high-spatial-resolution observations obtained with the Hubble Space Telescope of the sites and environments of stripped-envelope supernovae, and I will discuss the implications of the resulting analysis. I will include here, e.g., the environments of the recent SN 2011dh, SN 2012au, SN 2013df, SN 2013dk, and iPTF13bvn.
Growth of Supermassive Black Holes, Galaxy Mergers and Supermassive Binary Black Holes
Authors: Komossa S. , Baker J. G. , Liu F. K.
Published: October 2016

The study of galaxy mergers and supermassive binary black holes (SMBBHs) is central to our understanding of the galaxy and black hole assembly and (co-)evolution at the epoch of structure formation and throughout cosmic history. Galaxy mergers are the sites of major accretion episodes, they power quasars, grow supermassive black holes (SMBHs), and drive SMBH-host scaling relations. The coalescing SMBBHs at their centers are the loudest sources of gravitational waves (GWs) in the Universe, and the subsequent GW recoil has a variety of potential astrophysical implications which are still under exploration. Future GW astronomy will open a completely new window on structure formation and galaxy mergers, including the direct detection of coalescing SMBBHs, high-precision measurements of their masses and spins, and constraints on BH formation and evolution in the high-redshift Universe.
Limits on First Structure Formation from Pulsar Timing
Authors: Shannon R. M.
Published: October 2016

By monitoring the arrival times from millisecond pulsars for years to decades, it is possible to search for, or place limits on, nanohertz frequency gravitational radiation. The most promising source of gravitational waves in this band is a stochastic background emitted from a population of supermassive black hole binaries. As these binaries are the direct product of of galaxy mergers and the properties of the SMBHs correlated strongly with their host galaxies, the gravitational wave emission of the binaries can be used to study how galaxies evolve. Here I discuss how pulsar timing can be used to search for gravitational waves, and how limits on the strength of the background are being used to challenge models of supermassive black hole formation and evolution.
Constraining Supermassive Black Hole Binary Dynamics Using Pulsar Timing Data
Authors: Ellis J. A. ,   for the NANOGrav Collaboration
Published: October 2016

The most likely sources of nanohertz gravitational waves (GWs) are supermassive black holes (SMBHs) at the center of merging galaxies. A stochastic superposition of GWs from these sources is expected to produce a stochastic GW background that will leave a unique signature in the correlations of arrival times of pulses from a collection of radio pulsars. Using the 9-year data release from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration, we perform the first analysis that places constraints on the amplitude and shape of the stochastic GW background. We find that the data favor a turn over in the GW strain spectrum for current models of SMBH merger rates. This result indicates that environmental factors, other than GWs from circular binaries, are influencing the GW spectrum. Furthermore, we map constraints on the spectral shape to constraints on various environmental factors that drive the binary to the GW-driven regime including the stellar mass density for stellar-scattering, mass accretion rate for circumbinary disk interaction, and orbital eccentricity for eccentric binaries.
The Future of Pulsar Timing Arrays
Authors: Stappers B. W.
Published: October 2016

Significant advances have been made in the sensitivity of pulsar timing arrays for the detection of gravitational waves in the last decade. This presentation looked forward to consider where the development of pulsar timing arrays might go as we head towards the Square Kilometre Array (SKA) and then beyond. I reviewed where progress needs to be made in terms of sensitivity to gravitational waves, including improvements to existing observing approaches and new telescopes such as MeerKAT and FAST and techniques like LEAP. The dramatic increase in the number of millisecond pulsars is presented and how that might affect progress towards a first detection is discussed. Developments in analytic techniques were also discussed, including the removal of interstellar medium effects, red noise and pulse profile variations. A summary of how the SKA can contribute through an increased millisecond pulsar population and pulsar timing sensitivity was presented. With the likelihood that the SKA will implement some form of Key Science Project approach, some ideas of how will this affect how the International Pulsar Timing Array effort and how it might evolve into a KSP were discussed.
Observations of planet-forming volatiles
Authors: Pontoppidan Klaus M.
Published: October 2016

Water is observed to be a major constituent of planet-forming disks around young stars and its presence likely plays a major role in formation of planets and their atmospheres, including those destined to orbit in a habitable zone. Yet, the path from disks to planets is one fraught with complexity, making it difficult to derive precise theoretical predictions for planetary chemistry. Planet-forming disks are no longer considered uniform well-mixed structures; rather, they are complex worlds with many different heterogenous environments, most of which play some part in determining the composition of planetesimals and planets. Direct observations of atomic and molecular abundances on all size scales are therefore needed for understanding planet formation at a very fundamental level, and for answering the question of how chemically common the Earth is among exoplanets. In the past years, great progress has been made in observing protoplanetary chemistry, in particular in measuring the molecular composition in protoplanetary disks across the planet-forming regions from 1 to 10s of AU. We will present recent observations of water with Herschel, the VLT and Gemini in disks, and we will demonstrate how we retrieve the local abundances and radial distribution of water vapor and ice using detailed radiative transfer models. We find that most of the oxygen is likely bound in water near 1 AU in disks around solar-mass stars and that the disk surface composition at these radii is likely dominated by local gas-phase chemistry rather than by primordial material delivered from the interstellar medium. We discuss how these observations relate to complementary constraints from the solar system. We further discuss the implications for the observed composition of exoplanetary atmospheres.
Interstellar and Solar System organic matter preserved in interplanetary dust
Authors: Messenger Scott , Nakamura-Messenger K.
Published: October 2016

Interplanetary dust particles (IDPs) collected in the Earths stratosphere derive from collisions among asteroids and by the disruption and outgassing of short-period comets. Chondritic porous (CP) IDPs are among the most primitive Solar System materials. CP-IDPs have been linked to cometary parent bodies by their mineralogy, textures, C-content, and dynamical histories. CP-IDPs are fragile, fine-grained (< um) assemblages of anhydrous amorphous and crystalline silicates, oxides and sulfides bound together by abundant carbonaceous material. Ancient silicate, oxide, and SiC stardust grains exhibiting highly anomalous isotopic compositions are abundant in CP-IDPs, constituting 0.01-1% of the mass of the particles. The organic matter in CP-IDPs is isotopically anomalous, with enrichments in D/H reaching 50x the terrestrial SMOW value and 15N/14N ratios up to 3x terrestrial standard compositions. These anomalies are indicative of low T (10-100 K) mass fractionation in cold molecular cloud or the outermost reaches of the protosolar disk. The organic matter shows distinct morphologies, including sub-um globules, bubbly textures, featureless, and with mineral inclusions. Infrared spectroscopy and mass spectrometry studies of organic matter in IDPs reveals diverse species including aliphatic and aromatic compounds. The organic matter with the highest isotopic anomalies appears to be richer in aliphatic compounds. These materials also bear similarities and differences with primitive, isotopically anomalous organic matter in carbonaceous chondrite meteorites. The diversity of the organic chemistry, morphology, and isotopic properties in IDPs and meteorites reflects variable preservation of interstellar/primordial components and Solar System processing. One unifying feature is the presence of sub-um isotopically anomalous organic globules among all primitive materials, including IDPs, meteorites, and comet Wild-2 samples returned by the Stardust mission. We will present an overview of the current state of understanding of the properties and origins of organic matter in primitive IDPs.
Core-hydrogen-burning RSGs in the early globular clusters
Authors: Szécsi Dorottya , Mackey Jonathan , Langer Norbert
Published: October 2016

The first stellar generation in galactic globular clusters contained massive low-metallicity stars (Charbonnel et al. 2014). We modelled the evolution of this massive stellar population and found that such stars with masses 100-600 M⊙ evolve into cool RSGs (Szécsi et al. 2015). These RSGs spend not only the core-He-burning phase but even the last few 105 years of the core-H-burning phase on the SG branch. Due to the presence of hot massive stars in the cluster at the same time, we show that the RSG wind is trapped into photoionization confined shells (Mackey et al. 2014). We simulated the shell formation around such RSGs and find them to become gravitationally unstable (Szécsi et al. 2016). We propose a scenario in which these shells are responsible for the formation of the second generation low-mass stars in globular clusters with anomalous surface abundances.
Scaling of oscillation frequencies in rotating stars
Authors: Castaneda Diego , Deupree Robert G.
Published: October 2016

We have studied oscillation frequencies of two-dimensional uniformly rotating zero-age main sequence stellar models in the delta Scuti mass range. We identified 370 p and g axisymmetric modes for non-rotating models and then traced their evolution as the rotational velocity was increased. For each mass we considered a rotation sequence of ten models, with the largest rotation rate being about 200 km s−1. We constrained the models to have the same surface shape, which can be characterized for uniform rotation by the ratio between the polar and the equatorial radii. We find that scaling relationships exist among the oscillation frequencies calculated for models with the same shape. For p modes, this scaling closely follows the period root-mean-density relation found in spherical stars. The g modes also scale between models of the same shape, with the scaling reflecting the change in properties outside the convective core as the stellar mass increases. These scaling relationships can be particularly useful in finding specific stellar models to match the oscillation frequencies of individual stars.
Gravity, turbulence and the scaling “laws” in molecular clouds
Authors: Ballesteros-Paredes Javier
Published: October 2016

The so-called Larson (1981) scaling laws found empirically in molecular clouds have been generally interpreted as evidence that the clouds are turbulent and fractal. In the present contribution we discussed how recent observations and models of cloud formation suggest that:

(a)

these relations are the result of strong observational biases due to the cloud definition itself: since the filling factor of the dense structures is small, by thresholding the column density the computed mean density between clouds is nearly constant, and nearly the same as the threshold (Ballesteros-Paredes et al. 2012).

(b)

When accounting for column density variations, the velocity dispersion-size relation does not appears anymore. Instead, dense cores populate the upper-left corner of the δ v-R diagram (Ballesteros-Paredes et al. 2011a).

(c)

Instead of a δ v-R relation, a more appropriate relation seems to be δ v2 / R = 2 GMΣ, which suggest that clouds are in collapse, rather than supported by turbulence (Ballesteros-Paredes et al. 2011a).

(d)

These results, along with the shapes of the star formation histories (Hartmann, Ballesteros-Paredes & Heitsch 2012), line profiles of collapsing clouds in numerical simulations (Heitsch, Ballesteros-Paredes & Hartmann 2009), core-to-core velocity dispersions (Heitsch, Ballesteros-Paredes & Hartmann 2009), time-evolution of the column density PDFs (Ballesteros-Paredes et al. 2011b), etc., strongly suggest that the actual source of the non-thermal motions is gravitational collapse of the clouds, so that the turbulent, chaotic component of the motions is only a by-product of the collapse, with no significant “support" role for the clouds. This result calls into question if the scale-free nature of the motions has a turbulent, origin (Ballesteros-Paredes et al. 2011a; Ballesteros-Paredes et al. 2011b, Ballesteros-Paredes et al. 2012).
The Galactic magnetic field and its lensing of ultrahigh energy and Galactic cosmic rays
Authors: Farrar Glennys R.
Published: October 2016

It has long been recognized that magnetic fields play an important role in many astrophysical environments, yet the strength and structure of magnetic fields beyond our solar system have been at best only qualitatively constrained. The Galactic magnetic field in particular is crucial for modeling the transport of Galactic CRs, for calculating the background to dark matter and CMB-cosmology studies, and for determining the sources of UHECRs. This report gives a brief overview of recent major advances in our understanding of the Galactic magnetic field (GMF) and its lensing of Galactic and ultrahigh energy cosmic rays.
Which way to the next frontier? Finding the most powerful cluster lenses
Authors: Ebeling Harald ,   the eMACS team
Published: October 2016

While the identification of a worthy topic or challenge is fundamental to the goal of conducting cutting-edge research, another ingredient is indispensable in the field of observational astronomy: the best possible target. Indeed, the ability to choose from a significant number of extremely powerful gravitational lenses was central to the success of the Frontier Fields project. We here briefly review the surveys that provided this crucial pool of targets, before focusing on the results of ongoing work to identify similarly extreme (if not more extreme) systems at higher redshift for the exploration of a yet more distant extragalactic frontier – with JWST and other, evermore ambitious missions.
Spatially resolved spectroscopy of lensed galaxies in the Frontier Fields
Authors: Jones Tucker ,   the GLASS collaboration
Published: October 2016

The Grism Lens-Amplified Survey from Space (GLASS) has obtained slitless near-infrared spectroscopy of 10 galaxy clusters selected for their strong lensing properties, including all six Hubble Frontier Fields. Slitless grism spectra are ideal for mapping emission lines such as [O ii], [O iii], and Hα at z=1–3. The combination of strong gravitational lensing and Hubble's diffraction limit provides excellent sensitivity with spatial resolution as fine as 100 pc for highly magnified sources, and ~500 pc for less magnified sources near the edge of the field of view. The GLASS survey represents the largest spectroscopic sample with such high resolution at z > 1. GLASS and Hubble Frontier Field data provide the distribution of stellar mass, star formation, gas-phase metallicity, and other aspects of the physical structure of high redshift galaxies, reaching stellar masses as low as ~107 M⊙ at z=2. I discuss precise measurements of these physical properties and implications for galaxy evolution.
Glioblastoma, hypoxia and autophagy: a survival-prone ‘ménage-à-trois’
Authors: Jawhari Soha , Ratinaud Marie-Hélène , Verdier Mireille
Published: October 2016

Glioblastoma multiforme is the most common and the most aggressive primary brain tumor. It is characterized by a high degree of hypoxia and also by a remarkable resistance to therapy because of its adaptation capabilities that include autophagy. This degradation process allows the recycling of cellular components, leading to the formation of metabolic precursors and production of adenosine triphosphate. Hypoxia can induce autophagy through the activation of several autophagy-related proteins such as BNIP3, AMPK, REDD1, PML, and the unfolded protein response-related transcription factors ATF4 and CHOP. This review summarizes the most recent data about induction of autophagy under hypoxic condition and the role of autophagy in glioblastoma.