bluuebunny/crossref_metadata_2025 huggingface dataset:
THE NUMBER OF TIDAL DWARF SATELLITE GALAXIES IN DEPENDENCE OF BULGE INDEX
Authors: López-Corredoira Martín , Kroupa Pavel
Published: January 2016

We show that a significant correlation (up to 5σ) emerges between the bulge index, defined to be larger for a larger bulge/disk ratio, in spiral galaxies with similar luminosities in the Galaxy Zoo 2 of the Sloan Digital Sky Survey and the number of tidal-dwarf galaxies in the catalog by Kaviraj et al. In the standard cold or warm dark matter cosmological models, the number of satellite galaxies correlates with the circular velocity of the dark matter host halo. In generalized gravity models without cold or warm dark matter, such a correlation does not exist, because host galaxies cannot capture infalling dwarf galaxies due to the absence of dark-matter-induced dynamical friction. However, in such models, a correlation is expected to exist between the bulge mass and the number of satellite galaxies because bulges and tidal-dwarf satellite galaxies form in encounters between host galaxies. This is not predicted by dark matter models in which bulge mass and the number of satellites are a priori uncorrelated because higher bulge/disk ratios do not imply higher dark/luminous ratios. Hence, our correlation reproduces the prediction of scenarios without dark matter, whereas an explanation is not found readily from the a priori predictions of the standard scenario with dark matter. Further research is needed to explore whether some application of the standard theory may explain this correlation.
VARIATIONS OF THE ISM COMPACTNESS ACROSS THE MAIN SEQUENCE OF STAR FORMING GALAXIES: OBSERVATIONS AND SIMULATIONS
Authors: Martínez-Galarza J. R. , Smith H. A. , Lanz L. , Hayward Christopher C. , Zezas A. , Rosenthal L. , Weiner A. , Hung C. , Ashby M. L. N. , Groves B.
Published: January 2016

The majority of star-forming galaxies follow a simple empirical correlation in the star formation rate (SFR) versus stellar mass (M
*) plane, of the form

, usually referred to as the star formation main sequence (MS). The physics that sets the properties of the MS is currently a subject of debate, and no consensus has been reached regarding the fundamental difference between members of the sequence and its outliers. Here we combine a set of hydro-dynamical simulations of interacting galactic disks with state-of-the-art radiative transfer codes to analyze how the evolution of mergers is reflected upon the properties of the MS. We present Chiburst, a Markov Chain Monte Carlo spectral energy distribution (SED) code that fits the multi-wavelength, broad-band photometry of galaxies and derives stellar masses, SFRs, and geometrical properties of the dust distribution. We apply this tool to the SEDs of simulated mergers and compare the derived results with the reference output from the simulations. Our results indicate that changes in the SEDs of mergers as they approach coalescence and depart from the MS are related to an evolution of dust geometry in scales larger than a few hundred parsecs. This is reflected in a correlation between the specific star formation rate, and the compactness parameter

, that parametrizes this geometry and hence the evolution of dust temperature (

) with time. As mergers approach coalescence, they depart from the MS and increase their compactness, which implies that moderate outliers of the MS are consistent with late-type mergers. By further applying our method to real observations of luminous infrared galaxies (LIRGs), we show that the merger scenario is unable to explain these extreme outliers of the MS. Only by significantly increasing the gas fraction in the simulations are we able to reproduce the SEDs of LIRGs.
DETECTION OF REMNANT DUST CLOUD ASSOCIATED WITH THE 2007 OUTBURST OF 17P/HOLMES
Authors: Ishiguro Masateru , Sarugaku Yuki , Kuroda Daisuke , Hanayama Hidekazu , Kim Yoonyoung , Kwon Yuna G. , Maehara Hiroyuki , Takahashi Jun , Terai Tsuyoshi , Usui Fumihiko , Vaubaillon Jeremie J. , Morokuma Tomoki , Kobayashi Naoto , Watanabe Jun-ichi
Published: January 2016

This article reports a new optical observation of 17P/Holmes one orbital period after the historical outburst event in 2007. We detected not only a common dust tail near the nucleus but also a long narrow structure that extended along the position angle 274.°6 ± 0.°1 beyond the field of view (FOV) of the Kiso Wide Field Camera, i.e., >0.°2 eastward and >2.°0 westward from the nuclear position. The width of the structure decreased westward with increasing distance from the nucleus. We obtained the total cross section of the long extended structure in the FOV, C
FOV = (2.3 ± 0.5) × 1010 m2. From the position angle, morphology, and mass, we concluded that the long narrow structure consists of materials ejected during the 2007 outburst. On the basis of the dynamical behavior of dust grains in the solar radiation field, we estimated that the long narrow structure would be composed of 1 mm–1 cm grains having an ejection velocity of >50 m s−1. The velocity was more than one order of magnitude faster than that of millimeter–centimeter grains from typical comets around a heliocentric distance r
h of 2.5 AU. We considered that sudden sublimation of a large amount of water-ice (≈1030 mol s−1) would be responsible for the high ejection velocity. We finally estimated a total mass of M
TOT = (4–8) × 1011 kg and a total kinetic energy of E
TOT = (1–6) × 1015 J for the 2007 outburst ejecta, which are consistent with those of previous studies that were conducted soon after the outburst.
ELM: AN ALGORITHM TO ESTIMATE THE ALPHA ABUNDANCE FROM LOW-RESOLUTION SPECTRA
Authors: Bu Yude , Zhao Gang , Pan Jingchang , Kumar Yerra Bharat
Published: January 2016

We have investigated a novel methodology using the extreme learning machine (ELM) algorithm to determine the α abundance of stars. Applying two methods based on the ELM algorithm—ELM+spectra and ELM+Lick indices—to the stellar spectra from the ELODIE database, we measured the α abundance with a precision better than 0.065 dex. By applying these two methods to the spectra with different signal-to-noise ratios (S/Ns) and different resolutions, we found that ELM+spectra is more robust against degraded resolution and ELM+Lick indices is more robust against variation in S/N. To further validate the performance of ELM, we applied ELM+spectra and ELM+Lick indices to SDSS spectra and estimated α abundances with a precision around 0.10 dex, which is comparable to the results given by the SEGUE Stellar Parameter Pipeline. We further applied ELM to the spectra of stars in Galactic globular clusters (M15, M13, M71) and open clusters (NGC 2420, M67, NGC 6791), and results show good agreement with previous studies (within 1σ). A comparison of the ELM with other widely used methods including support vector machine, Gaussian process regression, artificial neural networks, and linear least-squares regression shows that ELM is efficient with computational resources and more accurate than other methods.
ORBITAL ARCHITECTURES OF PLANET-HOSTING BINARIES. I. FORMING FIVE SMALL PLANETS IN THE TRUNCATED DISK OF KEPLER-444A*
Authors: Dupuy Trent J. , Kratter Kaitlin M. , Kraus Adam L. , Isaacson Howard , Mann Andrew W. , Ireland Michael J. , Howard Andrew W. , Huber Daniel
Published: January 2016

We present the first results from our Keck program investigating the orbital architectures of planet-hosting multiple star systems. Kepler-444 is a metal-poor triple star system that hosts five sub-Earth-sized planets orbiting the primary star (Kepler-444A), as well as a spatially unresolved pair of M dwarfs (Kepler-444BC) at a projected distance of

(66 AU). We combine our Keck/NIRC2 adaptive optics astrometry with multi-epoch Keck/HIRES RVs of all three stars to determine a precise orbit for the BC pair around A, given their empirically constrained masses. We measure minimal astrometric motion (1.0 ± 0.6 mas yr−1, or 0.17 ± 0.10 km s−1), but our RVs reveal significant orbital velocity (1.7 ± 0.2 km s−1) and acceleration (7.8 ± 0.5 m s−1 yr−1). We determine a highly eccentric stellar orbit (

) that brings the tight M dwarf pair within

AU of the planetary system. We validate that the system is dynamically stable in its present configuration via n-body simulations. We find that the A–BC orbit and planetary orbits are likely aligned (98%) given that they both have edge-on orbits and misalignment induces precession of the planets out of transit. We conclude that the stars were likely on their current orbits during the epoch of planet formation, truncating the protoplanetary disk at ≈2 AU. This truncated disk would have been severely depleted of solid material from which to form the total ≈1.5 M
⊕ of planets. We thereby strongly constrain the efficiency of the conversion of dust into planets and suggest that the Kepler-444 system is consistent with models that explain the formation of most close-in Kepler planets in more typical, not truncated, disks.
FUV IRRADIATED DISK ATMOSPHERES: LYα AND THE ORIGIN OF HOT H2 EMISSION
Authors: Ádámkovics Máté , Najita Joan R. , Glassgold Alfred E.
Published: January 2016

Protoplanetary disks are strongly irradiated by a stellar FUV spectrum that is dominated by

photons. We investigate the impact of stellar

irradiation on the terrestrial planet region of disks (≲1 AU) using an updated thermal-chemical model of a disk atmosphere irradiated by stellar FUV and X-rays. The radiative transfer of

is implemented in a simple approach that includes scattering by H i and absorption by molecules and dust. Because of their non-radial propagation path, scattered

photons deposit their energy deeper in the disk atmosphere than the radially propagating FUV continuum photons. We find that

has a significant impact on the thermal structure of the atmosphere. Photochemical heating produced by scattered

photons interacting with water vapor and OH leads to a layer of hot (1500–2500 K) molecular gas. The temperature in the layer is high enough to thermally excite the

to vibrational levels from which they can be fluoresced by

to produce UV fluorescent

emission. The resulting atmospheric structure may help explain the origin of UV fluorescent

that is commonly observed from classical T Tauri stars.
STAR-FORMING BRIGHTEST CLUSTER GALAXIES AT 0.25 < z < 1.25: A TRANSITIONING FUEL SUPPLY
Authors: McDonald M. , Stalder B. , Bayliss M. , Allen S. W. , Applegate D. E. , Ashby M. L. N. , Bautz M. , Benson B. A. , Bleem L. E. , Brodwin M. , Carlstrom J. E. , Chiu I. , Desai S. , Gonzalez A. H. , Hlavacek-Larrondo J. , Holzapfel W. L. , Marrone D. P. , Miller E. D. , Reichardt C. L. , Saliwanchik B. R. , Saro A. , Schrabback T. , Stanford S. A. , Stark A. A. , Vieira J. D. , Zenteno A.
Published: January 2016

We present a multiwavelength study of the 90 brightest cluster galaxies (BCGs) in a sample of galaxy clusters selected via the Sunyaev Zel’dovich effect by the South Pole Telescope, utilizing data from various ground- and space-based facilities. We infer the star-formation rate (SFR) for the BCG in each cluster—based on the UV and IR continuum luminosity, as well as the [O ii]λλ3726,3729 emission line luminosity in cases where spectroscopy is available—and find seven systems with SFR > 100 M
⊙ yr−1. We find that the BCG SFR exceeds 10 M
⊙ yr−1 in 31 of 90 (34%) cases at 0.25 < z < 1.25, compared to ∼1%–5% at z ∼ 0 from the literature. At z ≳ 1, this fraction increases to

%, implying a steady decrease in the BCG SFR over the past ∼9 Gyr. At low-z, we find that the specific SFR in BCGs is declining more slowly with time than for field or cluster galaxies, which is most likely due to the replenishing fuel from the cooling ICM in relaxed, cool core clusters. At z ≳ 0.6, the correlation between the cluster central entropy and BCG star formation—which is well established at z ∼ 0—is not present. Instead, we find that the most star-forming BCGs at high-z are found in the cores of dynamically unrelaxed clusters. We use data from the Hubble Space Telescope to investigate the rest-frame near-UV morphology of a subsample of the most star-forming BCGs, and find complex, highly asymmetric UV morphologies on scales as large as ∼50–60 kpc. The high fraction of star-forming BCGs hosted in unrelaxed, non-cool core clusters at early times suggests that the dominant mode of fueling star formation in BCGs may have recently transitioned from galaxy–galaxy interactions to ICM cooling.
SPECTROSCOPY OF LUMINOUS COMPACT BLUE GALAXIES IN DISTANT CLUSTERS. II. PHYSICAL PROPERTIES OF dE PROGENITOR CANDIDATES
Authors: Crawford S. M. , Wirth Gregory D. , Bershady M. A. , Randriamampandry S. M.
Published: January 2016

Luminous Compact Blue Galaxies (LCBGs) are an extreme star-bursting population of galaxies that were far more common at earlier epochs than today. Based on spectroscopic and photometric measurements of LCBGs in massive (M > 1015
M
⊙), intermediate redshift (0.5 < z < 0.9) galaxy clusters, we present their rest-frame properties including star formation rate, dynamical mass, size, luminosity, and metallicity. The appearance of these small, compact galaxies in clusters at intermediate redshift helps explain the observed redshift evolution in the size–luminosity relationship among cluster galaxies. In addition, we find the rest-frame properties of LCBGs appearing in galaxy clusters are indistinguishable from field LCBGs at the same redshift. Up to 35% of the LCBGs show significant discrepancies between optical and infrared indicators of star formation, suggesting that star formation occurs in obscured regions. Nonetheless, the star formation for LCBGs shows a decrease toward the center of the galaxy clusters. Based on their position and velocity, we estimate that up to 10% of cluster LCBGs are likely to merge with another cluster galaxy. Finally, the observed properties and distributions of the LCBGs in these clusters lead us to conclude that we are witnessing the quenching of the progenitors of dwarf elliptical galaxies that dominate the number density of present-epoch galaxy clusters.
FREELY DECAYING TURBULENCE IN FORCE-FREE ELECTRODYNAMICS
Authors: Zrake Jonathan , East William E.
Published: January 2016

Freely decaying, relativistic force-free turbulence is studied for the first time. We initiate the magnetic field at a short wavelength and simulate its relaxation toward equilibrium on two- and three-dimensional periodic domains in both helical and nonhelical settings. Force-free turbulent relaxation is found to exhibit an inverse cascade in all settings and in three dimensions to have a magnetic energy spectrum consistent with the Kolmogorov 5/3 power law. Three-dimensional relaxations also obey the Taylor hypothesis; they settle promptly into the lowest-energy configuration allowed by conservation of the total magnetic helicity. However, in two dimensions, the relaxed state is a force-free equilibrium whose energy greatly exceeds the Taylor minimum and that contains persistent force-free current layers and isolated flux tubes. We explain this behavior in terms of additional topological invariants that exist only in two dimensions, namely the helicity enclosed within each level surface of the magnetic potential function. The speed and completeness of turbulent magnetic free-energy discharge could help account for rapidly variable gamma-ray emission from the Crab Nebula, gamma-ray bursts, blazars, and radio galaxies.
BREEDING SUPER-EARTHS AND BIRTHING SUPER-PUFFS IN TRANSITIONAL DISKS
Authors: Lee Eve J. , Chiang Eugene
Published: January 2016

The riddle posed by super-Earths (1–4R
⊕, 2–20M
⊕) is that they are not Jupiters: their core masses are large enough to trigger runaway gas accretion, yet somehow super-Earths accreted atmospheres that weigh only a few percent of their total mass. We show that this puzzle is solved if super-Earths formed late, as the last vestiges of their parent gas disks were about to clear. This scenario would seem to present fine-tuning problems, but we show that there are none. Ambient gas densities can span many (in one case up to 9) orders of magnitude, and super-Earths can still robustly emerge after ∼0.1–1 Myr with percent-by-weight atmospheres. Super-Earth cores are naturally bred in gas-poor environments where gas dynamical friction has weakened sufficiently to allow constituent protocores to gravitationally stir one another and merge. So little gas is present at the time of core assembly that cores hardly migrate by disk torques: formation of super-Earths can be in situ. The basic picture—that close-in super-Earths form in a gas-poor (but not gas-empty) inner disk, fed continuously by gas that bleeds inward from a more massive outer disk—recalls the largely evacuated but still accreting inner cavities of transitional protoplanetary disks. We also address the inverse problem presented by super-puffs: an uncommon class of short-period planets seemingly too voluminous for their small masses (4–10R
⊕, 2–6M
⊕). Super-puffs most easily acquire their thick atmospheres as dust-free, rapidly cooling worlds outside ∼1 AU where nebular gas is colder, less dense, and therefore less opaque. Unlike super-Earths, which can form in situ, super-puffs probably migrated in to their current orbits; they are expected to form the outer links of mean-motion resonant chains, and to exhibit greater water content. We close by confronting observations and itemizing remaining questions.
HUBBLE TARANTULA TREASURY PROJECT. III. PHOTOMETRIC CATALOG AND RESULTING CONSTRAINTS ON THE PROGRESSION OF STAR FORMATION IN THE 30 DORADUS REGION*
Authors: Sabbi E. , Lennon D. J. , Anderson J. , Cignoni M. , Marel R. P. van der , Zaritsky D. , Marchi G. De , Panagia N. , Gouliermis D. A. , Grebel E. K. , III J. S. Gallagher , Smith L. J. , Sana H. , Aloisi A. , Tosi M. , Evans C. J. , Arab H. , Boyer M. , Mink S. E. de , Gordon K. , Koekemoer A. M. , Larsen S. S. , Ryon J. E. , Zeidler P.
Published: January 2016

We present and describe the astro-photometric catalog of more than 800,000 sources found in the Hubble Tarantula Treasury Project (HTTP). HTTP is a Hubble Space Telescope Treasury program designed to image the entire 30 Doradus region down to the sub-solar (∼0.5 M
⊙) mass regime using the Wide Field Camera 3 and the Advanced Camera for Surveys. We observed 30 Doradus in the near-ultraviolet (F275W, F336W), optical (F555W, F658N, F775W), and near-infrared (F110W, F160W) wavelengths. The stellar photometry was measured using point-spread function fitting across all bands simultaneously. The relative astrometric accuracy of the catalog is 0.4 mas. The astro-photometric catalog, results from artificial star experiments, and the mosaics for all the filters are available for download. Color–magnitude diagrams are presented showing the spatial distributions and ages of stars within 30 Dor as well as in the surrounding fields. HTTP provides the first rich and statistically significant sample of intermediate- and low-mass pre-main sequence candidates and allows us to trace how star formation has been developing through the region. The depth and high spatial resolution of our analysis highlight the dual role of stellar feedback in quenching and triggering star formation on the giant H ii region scale. Our results are consistent with stellar sub-clustering in a partially filled gaseous nebula that is offset toward our side of the Large Magellanic Cloud.
AN EXTREME LUMINOUS X-RAY SOURCE CATALOG BASED ON CHANDRA ACIS OBSERVATIONS
Authors: Gong Hang , Liu Jifeng , Maccarone Thomas
Published: January 2016

Using Chandra archive data we conduct a thorough survey of luminous X-ray sources. We directly analyze about 9400 ACIS Observations and cross-correlate the X-ray sources with 77,000 galaxies within 250 Mpc. The final catalog includes 119 unique luminous X-ray source candidates with

from 93 galaxies or 41 HLX candidates with

from 35 galaxies. We derive a moderate contamination rate due to foreground or background sources. We also cross-correlate the catalog with FIRST, perform variability and periodicity tests, and analyze one HLX candidate in particular. Our catalog could be a starting point to perform follow-up observations.
L’affranchissement philosophique de la danse
Authors: Beauquel Julia
Published: January 2016

La danse bénéficie indirectement de l’insistance de Danto sur la dimension cognitive de l’art. Ce qu’elle gagne d’un côté risque toutefois d’être perdu de l’autre. Certes, l’art chorégraphique ne se limite pas au plaisir des yeux. Mais le rôle de l’intellect dans son appréciation et sa compréhension ne doit pas évincer celui, primordial, des sensations visuelles, kinesthésiques et auditives. Saisir la signification de la danse requiert un ancrage dans l’expérience sensible ; une attention soutenue, à la fois empirique et intellectuelle , ne devant pas être conçue comme l’enquête dualiste d’un esprit allant débusquer un contenu caché sous d’anecdotiques et trompeuses surfaces visibles 1 .
Enseignement d’un parcours militant
Authors: Mansour Moustafa , Seniguer Haouès
Published: January 2016

Dans l’entretien accordé à « Confluences Méditerranée », Moustafa Mansour revient sur un engagement actif de vingt-cinq ans contre les discriminations raciales et les inégalités de classe. Ses multiples expériences, sa connaissance du terrain et ses responsabilités associatives (en particulier au sein du CRI : « Coordination contre le racisme et l’islamophobie ») lui permettent avec le recul de porter des critiques fortes sur de nombreux sujets : les instrumentalisations politiques, le positionnement de diverses associations ayant pignon sur rue, les formes de lutte contre l’islamophobie, l’élitisme d’une certaine intelligentsia musulmane… La déception ayant été au bout de tous les dialogues classiques comme des promesses d’intégration, une démarche radicalement autonome s’imposerait désormais en privilégiant l’auto-organisation de tous les mouvements de libération de l’immigration postcoloniale et des quartiers populaires.
De Socrate à Illich
Authors: Soriano Paul
Published: January 2016

De Socrate à Ivan Illich, via le projet éducatif moderne et l’école républicaine, tout est dit, il suffit de faire le tri dans l’héritage. Et le numérique donne une nouvelle jeunesse aux plus anciens principes.
L’effondrement symbolique
Authors: Gaudy Jean-Noël
Published: January 2016

La crise de l’institution scolaire trouve son pendant médiologique dans les atteintes portées à l’architecture même de la classe et aux aménagements qui accueillent la mise en scène de la transmission.
Métamorphoses du pédagogue
Authors: Mathias Paul
Published: January 2016

Le numérique est un milieu, pour ainsi dire déjà une culture. C’est ainsi qu’il accueille de nouveaux parcours pour produire, valider, diffuser, faire usage des connaissances, anciennes et nouvelles. Comment naviguer dans cet océan ? Sous l’autorité de quels maîtres ?
La voix noire
Authors: Baas Bernard
Published: January 2016

Les recherches phénoménologiques de Ludwig Binswanger sur la spécificité de la temporalité mélancolique conduisent à référer à une catégorie transcendantale le sentiment de perte qui caractérise le vécu mélancolique. On doit toutefois distinguer entre le motif de la perte dans la mélancolie et le motif du manque dont se soutient le désir (Lacan). L’objet perdu auquel « colle » le mélancolique n’est pas tant un objet empirique auquel le mélancolique se serait identifié au point de se perdre lui-même avec cet objet (Freud), que, bien plutôt, l’ objet a , dans lequel le sujet se fond au point d’abolir le manque dont procède le désir. Ainsi la voix du mélancolique apparaît-elle vidée de toute intention signifiante : une voix déliée du discours. Mais, contrairement à la « voix blanche  » de la peur ou de l’angoisse, dans laquelle est encore maintenue la suspension dynamique du discours, la « voix noire  » de la mélancolie abolit cette dynamique : elle est une suspension atonique. Les travaux de Nicole Loraux sur la tragédie grecque permettent de penser que cette voix noire de la mélancolie peut aussi caractériser le kommos , le chant funèbre qui fait entendre une douleur qui s’éternise et se nourrit d’elle-même. La temporalité mélancolique apparaît ainsi comme le temps de « l’entre-deux-morts ».
Tueries en milieu scolaire
Authors: Steinkoler Manya
Published: January 2016

Cet article porte sur les massacres en milieu scolaire aux États-Unis et plus particulièrement sur le cas d’Adam Lanza, l’auteur du massacre à Newtown dans le Connecticut qui eut lieu en 2012. Ce cas pose la question du traitement, celle des identifications comme celle du rapport à l’autorité chez les enfants psychotiques. Il permet d’avancer quelques hypothèses et quant à l’acte de Lanza et quant à cette forme de violence de plus en plus populaire chez les adolescents.
La Marche sur Buenos Aires de 1935
Authors: González Alemán Marianne
Published: January 2016

Le 13 octobre 1935, les habitants de la ville Buenos Aires assistent stupéfaits à un spectacle inédit : le défilé d’environ cent mille citoyens venant de la province de Buenos Aires qui convergent vers la place de Mai, cœur de la ville de Buenos Aires, pour manifester leur soutien à Manuel Fresco, alors candidat du parti conservateur aux élections pour le poste de gouverneur. Dans ce contexte, la Marche sur Buenos Aires rend compte d’un changement notable de la façon dont le Parti conçoit la représentation politique. L’étude de cette grande mobilisation et du contexte dans lequel elle prend place permet de comprendre ce changement, à un moment où la province entre dans l’ère des mobilisations de masse.
Les relations entre les mouvements étudiants américain et français dans les années 1960
Authors: Lamarre Jean
Published: January 2016

Cet article analyse les relations entre les deux plus importantes unions étudiantes des années 1960, soit l’Union nationale des étudiants de France (UNEF) et l’United States National Student Association (NSA), et identifie les points de convergence et de divergence qui ont marqué leurs rapports. Ces deux syndicats étudiants, bien qu’aux antipodes quant à leur philosophie, leur fonctionnement et leur objectif, ont entretenu des relations cordiales et continues, moins par volonté de collaborer que pour s’épier, afin d’identifier leurs failles respectives, s’en servir pour miner leur crédibilité et gagner en leadership auprès des autres unions nationales.
Management public et développement agricole
Authors: Brunier Sylvain
Published: January 2016

L’article revient sur l’introduction de nouveaux instruments de contrôle et de gestion de la politique de développement agricole au début des années 1970. Ce tournant managérial n’est pas imposé de l’extérieur, il s’inscrit dans les luttes internes au champ des organisations professionnelles agricoles françaises et des administrations d’État spécifiques à ce secteur. Les nouvelles méthodes introduites dans le sillage de la politique de Rationalisation des choix budgétaires (RCB) participent à délégitimer l’ancienne conception du développement agricole qui liait la sélection des agriculteurs à la promotion des exploitations familiales, pour favoriser la parcellisation du travail de conseil agricole, la primauté accordées aux indicateurs de performance, la spécialisation et l’intensification des productions.
Choroidal Involvement in Acute Posterior Multifocal Placoid Pigment Epitheliopathy
Authors: Mrejen Sarah , Sarraf David , Chexal Saradha , Wald Kenneth , Freund K. Bailey
Published: January 2016

BACKGROUND AND OBJECTIVE:

To evaluate choroidal involvement in acute posterior multifocal placoid pigment epitheliopathy (APMPPE).

PATIENTS AND METHODS:

Retrospective study in five eyes of three patients evaluated through multimodal imaging, including enhanced-depth imaging optical coherence tomography (OCT), ultra-wide field color photography, fundus autofluorescence, and fluorescein angiography (FA). Choroidal thickness and structure were evaluated on OCT.

RESULTS:

During the acute phase, choroidal OCT showed choroidal thickening and a lucency at the level of the inner choroid. Subclinical lesions detected in the retinal periphery using wide-field retinal imaging were isoautofluorescent and corresponded to choriocapillaris filling-defects on FA. At final follow-up, all patients showed resolution of choroidal thickening and the inner choroidal lucency, as well as the disappearance of subclinical lesions.

CONCLUSION:

These results suggest a transient ischemic choroiditis in APMPPE that may lead to secondary permanent retinal pigment epithelium damage in the posterior pole but not in the retinal periphery.

[Ophthalmic Surg Lasers Imaging Retina.
2016;47:20–26.]
A Comparison of Immediate and Delayed Vitrectomy for the Management of Vitreous Hemorrhage due to Proliferative Diabetic Retinopathy
Authors: Fassbender Janelle M. , Ozkok Ahmet , Canter Hannah , Schaal Shlomit
Published: January 2016

BACKGROUND AND OBJECTIVE:

To compare immediate and delayed vitrectomy for the management of vitreous hemorrhage (VH) due to proliferative diabetic retinopathy (PDR).

PATIENTS AND METHODS:

Retrospective review of 134 eyes receiving vitrectomy for non-clearing, PDR-associated VH. Primary outcome was area under the vision curve (AUC) in patients receiving immediate (< 30 days) versus delayed (> 30 days) vitrectomy with endolaser.

RESULTS:

Forty-six eyes were included, with 17 undergoing immediate (< 30 days) vitrectomy with endolaser and 29 undergoing delayed (> 30 days) vitrectomy with endolaser. Time to vitrectomy was 14.8 days ± 8.26 days compared to 629.6 days ± 894.9 days in the immediate and delayed groups, respectively. AUC was significantly greater for patients undergoing delayed versus immediate vitrectomy (276.1 ± 0.601 logMAR*time versus 165.7 ± 0.761 logMAR*time;P< .0001). There was no difference in AUC postoperatively for delayed versus immediate surgery. Both groups required significantly less postoperative panretinal photocoagulation (P< .05). Preoperative and final visual acuities were equivalent (immediate: 1.86 ± 0.99 and 0.35 ± 0.25;P= .002; delayed: 1.71 ± 1.05 and 0.31 ± 0.34;P< .0001).

CONCLUSIONS:

Immediate vitrectomy with endolaser for PDR-associated VH (< 30 days) decreases time spent with vision loss and the need for adjunctive PRP. Modern vitrectomy is safe and may be considered earlier in VH management.

[Ophthalmic Surg Imaging Lasers Retina. 2016;47:35–41.]
Pharmacologic Vitreolysis in Vascular Diseases of the Retina
Authors: Soliman Mohamed Kamel , Agarwal Aniruddha , Sarwar Salman , Hanout Mostafa , Sadiq Mohammad Ali , Do Diana V. , Nguyen Quan Dong
Published: January 2016

Vascular diseases of the retina such as diabetic retinopathy and vascular occlusions account for a large proportion of visual morbidity and blindness worldwide. The role of vitreous in the pathogenesis of these conditions has been increasingly recognized. Despite advances in the surgical technique of pars plana vitrectomy, the use of intravitreal agents for the lysis of vitreous has received attention, guided largely by promising results from the trials involving patients with non-vascular retinal diseases such as vitreomacular traction. The purpose of this review is to provide a comprehensive summary of the present knowledge on pathophysiologic basis of pharmacologic vitreolysis and its efficacy in vascular diseases of the retina. A review of completed and ongoing clinical trials will be presented, along with insights into future directions of this therapy.

[
Ophthalmic Surg Lasers Imaging Retina
. 2016;47:60–68.]
OCT Angiography Identification of Choroidal Neovascularization Secondary to Acute Zonal Occult Outer Retinopathy
Authors: Levison Ashleigh L. , Baynes Kimberly , Lowder Careen Y. , Srivastava Sunil K.
Published: January 2016

A 74-year-old female with acute zonal occult outer retinopathy presented with a new lesion suspicious for choroidal neovascularization (CNV) in her right eye. Optical coherence tomography angiography (OCTA) confirmed the presence of CNV. OCTA is a new imaging technique that may help guide diagnosis and management of choroidal neovascular membranes in uveitic diseases.

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Ophthalmic Surg Lasers Imaging Retina
. 2016;46:73–75.]
Saturday Night Retinopathy: Characterization of a Rare Ophthalmic Condition
Authors: Peracha Zuhair H. , Ahmed Shareef B. , Desai Ankit , Peracha-Riyaz Manal , Kumar Nitin , Desai Uday R.
Published: January 2016

A 48-year-old, black female with a history of heroin and daily alcohol abuse presented to the emergency room in a lethargic state with severe right eye pain and vision loss. She had been unconscious for 10 hours prior to presentation. On exam she was found to have no light perception vision, severe retinal edema, and complete ophthalmoplegia of the right eye. Imaging and clinical course confirmed the diagnosis of Saturday Night Retinopathy — only the second documented case to be published.

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Ophthalmic Surg Lasers Imaging Retina
. 2016;47:85–89.]
The Characterization of Flame Cut Heavy Steel – The Residual Stress Profiling of Heat Affected Surface Layer
Authors: Jokiaho Tuomas , Saarinen Tuomo , Santa-Aho Suvi , Peura Pasi , Vippola Minnamari
Published: January 2016

Flame cutting is commonly used thermal cutting method in metal industry when processing thick steel plates. Cutting is performed with controlled flame and oxygen jet, which burns steel and forms cutting edge. Flame cutting process is based on controlled chemical reaction between steel and oxygen at elevated temperature. Flame cutting of thick wear-resistant steels is challenging while it can result in cracks on and under the cut edge. Flame cutting causes uneven temperature distribution in the plate, which can introduce residual stresses. In addition, heat affected zone (HAZ) is formed and there both volume and microstructural changes as well as hardness variations are taking place. Therefore flame cutting always causes thermal stress, shape changes and consequently residual stresses to the material. Material behaviour under thermal and mechanical loading depends on the residual stress state of the material. Due to this, it is important to be able to measure the residual stresses. The aim of this study was to examine residual stresses on the cutting edge as a function of different flame cutting parameters. Also resulting microstructures and hardness values were verified. Varying parameters were the cutting speed, preheating and post heating procedures. Flame cut samples were investigated with X-ray diffraction method to produce residual stress profiles of the heat affected surface layer. Results indicated that different cutting parameters provide different residual stress profiles and that these profiles can be modified by changing the cutting speed and pre-or post-treatment procedures. Cutting parameters also affect the depth of the reaustenized region in the surface. The results correlate well with the actual industrial flame cutting and thus they provide an effective tool for optimizing the flame cutting process parameters.
Hybrid Graphene/Alumina Nanofibers for Electrodonductive Zirconia
Authors: Drozdova Maria , Pérez-Coll Domingo , Aghayan Marina , Ivanov Roman , Rodríguez Miguel Angel , Hussainova Irina
Published: January 2016

Ceramic materials have become of high industrial importance in some applications as their properties outperform ones of metallic components. However, use of ceramics is limited due to the difficulties in shaping. Electrically conductive ceramics can be machined by Electro-Discharge Machining (EDM) irrespective of its hardness or strength. In this study, yttria stabilized zirconia (YTZP) conductive composite was produced by incorporation of the cost-effective graphene coated alumina nanofibers (ANFC) into the matrix. Almost fully dense YTZP/5 vol.% ANFC nanocomposite was obtained by spark plasma sintering (SPS) at 1250 °C with uniaxial pressure of 40 MPa. Scanning electron microscopy observation of the microstructures showed that ANFCs were homogeneously dispersed in the matrix. Addition of ANFC resulted in slightly decreased mechanical properties, but the electrical resistivity of the composite dropped 9 orders of magnitude compared to monolithic zirconia, exhibiting 1.4 Ω∙m, satisfying the required condition for the EDM.
Damage Mechanisms of Plasma, Gas and Salt Bath Nitrocarburized Steel in Lab-Scale Sliding Test
Authors: Velkavrh Igor , Trausmuth Andreas , Rodríguez Ripoll Manel , Kunze Wolfgang , Glück Johann , Lingenhöle Klaus , Orth Peter , Diem Alexander , Badisch Ewald
Published: January 2016

Nitrocarburized steel surfaces are often used in tribological forming applications due to their beneficial sliding properties. One typical application field can be found in bending machines where the nitrocarburized layer can withstand massive volume loss and prevent from adhesion of the work sheet material. However, under non-lubricated sliding conditions abrupt failure of the nitrocarburized layer can occur, which results in pronounced increase of friction and wear. In order to characterise the wear mechanisms of nitrocarburized surfaces under non-lubricated sliding conditions, a lab-scale study was carried out. Different nitrocarburizing processes including plasma, gas and salt bath nitrocarburizing were investigated. Oscillating sliding tests with DIN 100Cr6 bearing steel cylinder sliding against nitrocarburized plate were performed at contact pressures typical for bending machines. Evaluation of wear was performed by white-light interferometer with measurements of the wear-scar topography and a subsequent calculation of the average wear depth. A strong influence of the nitrocarburizing process on friction and wear behaviour was observed. This behaviour could be correlated with the microstructure of the compound layer.
Fracture Description of AZ61 Mg-Al2O3 Materials Studied by “In Situ Tensile Test in SEM“
Authors: Besterci Michael , Nagy Štefan , Huang Song Jeng , Velgosová Oksana , Sülleiová Katarína , Kulu Priit
Published: January 2016

In situ observation of AZ61 Mg alloy with 5 wt. % of Al2O3 in the SEM was performed to study influence of the weight fraction of Al2O3 particles on the deformation and fracture description during the tensile test. Structure of the experimental materials was also analysed; microstructures were heterogeneous, with randomly distributed globular Al2O3 particles (average diameter of 25 nm) and Mg17Al12 intermetallic phase (average diameter of 0.4 mm). It was shown that during the tensile deformation the failure of Mg17Al12 particles and decohesion of the matrix-Al2O3 particles interphase boundary started simultaneously. Decohesion resulted from the different physical properties of matrix and Al2O3 particles. The influence of the Al2O3 weight fraction on the final fracture was evident; for the material with 5 wt. % of Al2O3, the fracture surface was approximately perpendicular to the loading direction. The fracture surface had transcrystalline ductile character.
Effect of Basalt Reinforcement Type and Content on the Abrasive Wear Behaviour of Polymer Composites
Authors: Antonov Maksim , Kers Jaan , Liibert Laura , Shuliak Volodymyr , Smirnov Anton , Bartolomé Jose F.
Published: January 2016

Basalt reinforced composites are quite recently (during last 20 years) developed materials having low density, high specific strength, good frictional, heat and chemical resistance. Natural mineral based fibres are potential alternatives to glass fibres for their strength and to carbon fibres for their lower cost. In order to use basalt reinforced composites for lightweight applications, it is necessary to perform wear characterisation. Basalt fibre, powder and scales reinforced, unsaturated polyester and epoxy resin composites were fabricated with various ratios of basalt and polymeric matrixes. The tribological behaviour of basalt reinforced composites was determined according to the ASTM G132 standard test method for pin abrasion testing. Results showed that type and content of reinforcement have a significant influence on the mechanical and tribological properties of the composites. Scanning electron microscope images are given to illustrate the wear mechanism of composites.
Experimental Studies on Abrasive Wear of Surface-Hardened and Shot Peened Alloy Cast Steels
Authors: Wieczorek Andrzej Norbert
Published: January 2016

The paper presents the results of wear tests of shot-peened and non-shot-peened cast steels with the use of an especially designed test rig simulating real operating conditions of chain wheels. The chain wheels subjected to tests were operated with the use of loose quartz abrasive. The studies involved the determination of strength and plastic properties, hardness distributions, microstructure and linear wear of the selected cast steels. Based on the results obtained, the following was found: the abrasive wear of cast steel chain wheels increased after shot peening.
Tribological Behaviour of Gradient TiAlSiN Superhard Coatings
Authors: Mourlas Athanasios , Psyllaki Pandora , Chaliampalias Dimitrios , Vourlias George , Kolaklieva Lyliana , Kakanakov Roumen
Published: January 2016

The present study addresses the influence of the gradient microstructure of nanocrystalline TiAlSiN coatings on their tribological behaviour. Cathodic arc deposition was applied to elaborate such coatings, with a total thickness of 3.5 μm, onto stainless steel substrates. Their microstructure has been characterised via Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS) and has been reported in detail previously. Since the main application of TiN-based coatings is the enhancement of the anti-wear resistance of metallic substrates, this work is focused on the tribological performance of gradient TiAlSiN coatings under dry sliding conditions. For this purpose, tests were carried out in a ball-on-disc apparatus, using an alumina ball as counterbody. The influence of the sliding velocity on the evolution of the friction coefficient and the wear lifetime of the gradient coatings has been evaluated in comparison to those of TiN coatings of the same thickness, tested under the same experimental conditions. It was found that the gradient microstructure results in an increase of the coatings’ mean lifetime by an average factor of three.
The Effect of Temperature on Wear Mechanism of the AlCrN Coated Components
Authors: Michalak Michał , Michalczewski Remigiusz , Osuch-Słomka Edyta , Maldonado-Cortés Demófilo , Szczerek Marian
Published: January 2016

The aim of the paper was to investigate the temperature effect on the wear mechanism of AlCrN coated components. The coating was deposited by Physical Vapour Deposition process (PVD) on WC/Co substrate. Tribological tests were performed in sliding conditions using high temperature T‑21 tribotester, produced by ITeE-PIB Radom. The tests were performed in a ball-on-disc configuration (Si3N4 ceramic ball), under dry friction conditions at room temperature, 600°C and 750°C. An optical microscope, interferometer, and scanning electron microscope were used to analyse the worn surfaces. Following this study, it was found that wear resistance of the coating AlCrN tribosystem depended on the temperature. The biggest wear was reported at room temperature. At 600°C the intensity of wear of the coating was 4-fold lower, and at 750°C wear was 6-fold lower that at room temperature. High temperature wear resistance of AlCrN coating involves creating protective oxide layer. Performed analysis of structure the surface layer, showed a much higher content of oxygen in wear scar than outside. At high temperatures, friction additional intensified oxidation process thus the amount of oxygen in surface layer increased with temperature. Oxide layer, Al2O3 and Cr2O3 probably, created at high temperature was a barrier to further oxidation of the coating and had very high wear resistance at high temperature.
Study of Frictional Properties of AMS Nickel-Chromium Alloys
Authors: Trzepieciński Tomasz , Trytek Andrzej , Lemu Hirpa G.
Published: January 2016

The research reported in this article has considered the frictional characteristics of three kinds of AMS nickel-chromium alloys that are commonly used in aerospace industry. These are alloys with additions of titanium and aluminum AMS5542, nickel-chromium alloy AMS5596, and non-magnetic, corrosion and oxidation resistant, nickel-chromium alloy AMS5599. To determine the friction coefficient two tribological tests, a strip drawing test and a pin-on-disc tribometer have been conducted. Three different friction conditions were considered, dry friction, lubrication conditions using two grades of oils used in sheet metal forming of AMS alloys. The experimental results have ascertained several relationships showing the effect of sheet metal surface roughness, lubricant conditions and sheet orientation on the value of friction coefficient in sheet metal forming processes. Different levels of normal pressure were also used in friction tests. The results further showed that the surface topography and sample orientation in the rolling direction of the sheet are significant factors that influence the friction coefficient. It has been observed that the tested AMS alloys, selected from aerospace industry applications, exhibit anisotropic resistance to the friction corresponding to the measured orientation in relation to the rolling direction of the sheet.
Wear Resistance of TiN/TiCN and TiN/TiBN Multilayer Coatings Applied on Hot Work Tool Steel
Authors: Kovačić Saša , Cajner Franjo , Landek Darko
Published: January 2016

T
This paper examines the abrasive and erosive wear of duplex multilayer TiN/TiCN and TiN/TiBN coatings deposited on quenched and tempered hot work tool steel grade X37CrMoV5-1. The coatings were produced by duplex method composed of a plasma nitriding and pulsed direct current (DC) plasma-assisted chemical-vapor deposition (PACVD). Measurements of the thickness of the deposited coatings were determined by calotest. Adhesion of the layers were determined by the Rockwell-C indentation test and the microhardness profile in a diffusion zone beneath the surface was determined by Vickers method (HV 0.05). Tests of abrasive wear resistance were carried out using "Dry Sand-Rubber Wheel” method. Test of erosion resistance of the base material and of duplex layers was carried out by exposing test samples to impact erosion of fine sand particles and determining the loss of mass after 60 minutes of wear. Worn surface were analysed by stereomicroscopy. The results show increasing wear resistance of duplex multilayer coatings of TiN/TiCN and TiN/TiBN in relation to plasma nitrided and uncoated steel (in the quenched in tempered condition).
Influence of the Coated Carbide Grade on the Cutting Tool Life When Machining Inconel 718
Authors: Bakša Tomáš , Morávek Michal , Zetek Miroslav
Published: January 2016

This article deals with the machining of Inconel 718 alloy. In the research, several carbide milling tools with different carbide grades and coatings were used. The main aim is compare all cutting tools in terms of their cutting tool life during machining super alloy Inconel 718. This material is used for highly stressed components in the nuclear industry, such as combustion turbine. Due to its rapid hardening and high heat generation, it is very problematic to machining. The right choice of appropriate carbide grade is necessary to achieve high-quality cutting wedge, which is important for good adhesion of the coating. The results of this work will be used for further research and development of cutting tools for machining Inconel 718.
The Influence of PVD Coatings on the Wear Performance of Steel Dental Curettes
Authors: Leppäniemi Jarmo , Lyytinen Jussi , Elomaa Oskari , Suomalainen Kimmo , Koskinen Jari
Published: January 2016

The wear properties of steel dental curettes coated with wear resistant Diamond Like Carbon (DLC) and metal nitride coatings deposited by Physical Vapor Deposition (PVD) were studied by using a customized mechanical device simulating motion and load of dental curettes against human teeth. The wear surfaces were studied by optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Nanoindentation. Rockwell indentation testing was used to evaluate the coating adhesion. With the optimized combination of substrate steel and wear resistant coating reduction of 80% in the wear of instruments could be achieved.