Chandra Observation of 3C 212: a New Look at the X-ray and UV Absorbers

The red quasar 3C 212 (z=1.049) is one of the most distant and most luminous AGN which has shown evidence of an X-ray warm absorber. In order to further investigate this unusual quasar, we used Chandra/ACIS-S to observe 3C 212 for 19.5 ksec, resulting in a net detection of ~4000 counts. The Chandra data confirm the presence of an excess absorbing column N_H ~ 4 x 10^21 cm^-2 at the quasar redshift, but we find no compelling evidence for a warm absorber. Using both the Chandra and archival ROSAT PSPC data, we obtain very good fits for both a partially covered neutral absorber and a low-ionization (U = 0.03) photo-ionized absorber. In the ultraviolet, 3C 212 shows a strong associated MgII absorber. Based on a moderate resolution (80 km/s) MMT spectrum we show that the absorber is highly saturated and has a covering fraction less than 60%, implying that the absorber is truly intrinsic to the quasar. Photo-ionization modeling of the MgII absorber yields a constraint on the ionization parameter of U < 0.03, inconsistent with a warm UV/X-ray absorber. In addition to our spectral analysis, we find evidence in the ACIS image data for weak extended emission surrounding the quasar as well as emission corresponding to the radio lobes at a distance of 5 arcsec from 3C 212. The statistical significance of these features is low, but we briefly explore the implications if the detections are valid.Comment: 8 pages, 6 figures, Accepted for publication in the Astrophysical Journa

Archeologische verwachtingskaart uiterwaarden rivierengebied

Dit rapport betreft het project archeologische verwachtingskaart uiterwaarden rivierengebied (‘UIKAV 2014’), uitgevoerd door Deltares, Rijksuniversiteit Groningen en Universiteit Utrecht, in opdracht van Rijkswaterstaat en de Rijksdienst voor het Cultureel Erfgoed. Het rapport en de bijbehorende producten (een archeologische verwachtingskaart, met onderliggende databases, basiskaarten en documentatie op detailniveau in catalogusvorm, en verdere digitale bijlagen) bieden een overzicht van in de uiterwaarden van het Nederlandse riviergebied te verwachten archeologie. Het doel van het project was het maken van een gedetailleerde, tijd-specifieke, archeologische verwachtingskaart voor de uiterwaarden. Er zijn een aantal eisen gesteld aan dit product. Een belangrijke eis was dat de nieuwe archeologische kennis en gegevens zoals opgedaan en verzameld binnen het programma Ruimte voor de Rivier met dit product zouden worden geborgd. Daarnaast was een eis dat de kaart een transparant en reproduceerbaar product zou worden. Om die reden is een onderhoudbaar systeem opgezet (gebruik makend van de functionaliteit van Geografische Informatie Systemen, GIS), waarmee de verwachtingskaart volgens vastgelegde beslisregels gegenereerd is, volgens welke zij ook in toekomstige cycli van archeologische toetsing vernieuwd kan worden. Dit systeem betrekt landschapsgenetische en archeologische brongegevens en combineert deze automatisch tot een verwachtingskaart. Dankzij deze methodiek is lokale aanpassing naar aanleiding van nieuwe gegevens of veranderd inzicht relatief eenvoudig. Een bijkomend voordeel van het systeem is dat er verwachtingen worden uitgesproken voor zowel terrestrische (landgebonden) archeologie op en langs de oevers van de rivieren, als voor aquatische (watergebonden) archeologie langs de waterkant en begraven in de rivier. Bovendien kunnen verwachtingskaarten voor specifieke archeologische periodes gemaakt worden. In het project zijn de verwachtingskaarten voor negen opeenvolgende tijdsnedes uitgewerkt. Samen geven deze de trefkans op archeologie uit de tijd van de jager-verzamelaars (sinds het begin van het Holoceen, 9500 v. Chr.) tot en met de nieuwe tijd (WO II, 20ste eeuw). De kaarten bestrijken de uiterwaarden van de (i) Bovenrijn, Waal en Merwede van Lobith tot Gorinchem, (ii) Nederrijn en Lek van de Pannerdense Kop tot Schoonhoven, (iii) Gelderse IJssel van de IJsselkop (Westervoort) tot de IJsseldelta (Kampen) en (iv) Maas en Afgedamde Maas van Mook tot Woudrichem (en ook de Bergsche Maas). Het gebied omvat ook de door dijkverleggingen en aanleg van bypasses ontstane vergrotingen van de uiterwaarden door projecten zoals die zijn uitgevoerd binnen het programma Ruimte voor de Rivier. Alle gegevens – input en tussenproducten, berekeningsmethode en eindproducten - zijn in aanvulling op het rapport digitaal beschikbaar gesteld. Daartoe hoort ook een catalogus die per deeluiterwaard naar de gebruikte bronnen refereert en relevante informatie over geomorfologie, archeologie en landschapsouderdom samenvat. In het rapport is de totstandkoming van de kaarten uitgebreid gedocumenteerd, en worden de uiteindelijke verwachtingsbeelden beknopt besproken en vergeleken met bestaande producten. Zowel de basiskaarten (input) als de verwachtingskaarten (output) zijn primair ontsloten als GIS bestanden. Deze zijn bruikbaar voor fysisch-geografische en archeologische specialisten en geschikt voor ontsluiting via web-portalen zoals opdrachtgevers RWS (interne web-portalen) en RCE (extern portaal: http://www.archeologieinnederland.nl) deze hebben ingericht en beheren. Als snelle, laagdrempelige ingang tot het product fungeren PDF atlassen met de kaartseries in een standaardopmaak (steeds 34 bladen, schaal 1:25,000). Alle digitale producten worden zowel in de oorspronkelijke vorm (ESRI GIS shapefiles, MS-Access databases) opgeleverd, als in een vorm (PDF Atlassen) die geschikt is voor printen en analoge raadpleging van de producten (Bijlagen G tot N). De volledige dataset (volledige Digitale Bijlage) is duurzaam gedeponeerd bij DANS Data Archiving and Networked Services als dataset 57727. Web-viewer: http://www.archeologieinnederland.nl/bronnen-en-kaarten/verwachtingskaart-uiterwaarden-rivierengebied Aankonding verschijnen: http://www.mailinglijst.nl/mailings/show.aspx?mai=130118&mem=3135&a=1171800

Parietal but not temporoparietal alpha-tACS modulates endogenous visuospatial attention

Visuospatial attention can either be voluntarily directed (endogenous/top-down attention) or automatically triggered (exogenous/bottom-up attention). Recent research showed that dorsal parietal transcranial alternating current stimulation (tACS) at alpha frequency modulates the spatial attentional bias in an endogenous but not in an exogenous visuospatial attention task. Yet, the reason for this task-specificity remains unexplored. Here, we tested whether this dissociation relates to the proposed differential role of the dorsal attention network (DAN) and ventral attention network (VAN) in endogenous and exogenous attention processes respectively. To that aim, we targeted the left and right dorsal parietal node of the DAN, as well as the left and right ventral temporoparietal node of the VAN using tACS at the individual alpha frequency. Every participant completed all four stimulation conditions and a sham condition in five separate sessions. During tACS, we assessed the behavioral visuospatial attention bias via an endogenous and exogenous visuospatial attention task. Additionally, we measured offline alpha power immediately before and after tACS using electroencephalography (EEG). The behavioral data revealed an effect of tACS on the endogenous but not exogenous attention bias, with a greater leftward bias during (sham-corrected) left than right hemispheric stimulation. In line with our hypothesis, this effect was brain area-specific, i.e., present for dorsal parietal but not ventral temporoparietal tACS. However, contrary to our expectations, there was no effect of ventral temporoparietal tACS on the exogenous visuospatial attention bias. Hence, no double dissociation between the two targeted attention networks. There was no effect of either tACS condition on offline alpha power. Our behavioral data reveal that dorsal parietal but not ventral temporoparietal alpha oscillations steer endogenous visuospatial attention. This brain-area specific tACS effect matches the previously proposed dissociation between the DAN and VAN and, by showing that the spatial attention bias effect does not generalize to any lateral posterior tACS montage, renders lateral cutaneous and retinal effects for the spatial attention bias in the dorsal parietal condition unlikely. Yet the absence of tACS effects on the exogenous attention task suggests that ventral temporoparietal alpha oscillations are not functionally relevant for exogenous visuospatial attention. We discuss the potential implications of this finding in the context of an emerging theory on the role of the ventral temporoparietal node

Analytic frameworks for assessing dialogic argumentation in online learning environments

Over the last decade, researchers have developed sophisticated online learning environments to support students engaging in argumentation. This review first considers the range of functionalities incorporated within these online environments. The review then presents five categories of analytic frameworks focusing on (1) formal argumentation structure, (2) normative quality, (3) nature and function of contributions within the dialog, (4) epistemic nature of reasoning, and (5) patterns and trajectories of participant interaction. Example analytic frameworks from each category are presented in detail rich enough to illustrate their nature and structure. This rich detail is intended to facilitate researchers’ identification of possible frameworks to draw upon in developing or adopting analytic methods for their own work. Each framework is applied to a shared segment of student dialog to facilitate this illustration and comparison process. Synthetic discussions of each category consider the frameworks in light of the underlying theoretical perspectives on argumentation, pedagogical goals, and online environmental structures. Ultimately the review underscores the diversity of perspectives represented in this research, the importance of clearly specifying theoretical and environmental commitments throughout the process of developing or adopting an analytic framework, and the role of analytic frameworks in the future development of online learning environments for argumentation

On the nature of Seyfert galaxies with high [OIII]5007 blueshifts

We have studied the properties of Seyfert galaxies with high [OIII]5007 blueshifts (`blue outliers'), originally identified because of their strong deviation from the M_BH - sigma relation of normal, narrow-line Seyfert 1 (NLS1) and broad-line Seyfert 1 (BLS1) galaxies. These blue outliers turn out to be important test-beds for models of the narrow-line region (NLR), for mechanisms of driving large-scale outflows, for links between NLS1 galaxies and radio galaxies, and for orientation-dependent NLS1 models. We report the detection of a strong correlation of line blueshift with ionization potential in each galaxy, including the measurement of coronal lines with radial velocities up to 500--1000 km/s. All [OIII] blue outliers have narrow widths of their broad Balmer lines and high Eddington ratios. While the presence of non-shifted low-ionization lines signifies the presence of a classical outer quiescent NLR in blue outliers, we also report the absence of any second, non-blueshifted [OIII] component from a classical inner NLR. These results place tight constraints on NLR models. We favor a scenario in which the NLR clouds are entrained in a decelerating wind which explains the strong stratification and the absence of a zero-blueshift inner NLR of blue outliers. The origin of the wind remains speculative at this time (collimated radio plasma, thermal winds, radiatively accelerated clouds). It is perhaps linked to the high Eddington ratios of blue outliers. Similar, less powerful winds could be present in all Seyfert galaxies, but would generally only affect the coronal line region (CLR), or level off even before reaching the CLR. Similarities between blue outliers in NLS1 galaxies and (compact) radio sources are briefly discussed.Comment: ApJ in press (scheduled for June 20 issue); incl. 4 colour figures. This, and related paper showing that NLS1 galaxies follow the M-sigma relation based on [SII], is also available at http://www.xray.mpe.mpg.de/~skomossa

Extended High-Ionization Nuclear Emission-Line Region in the Seyfert Galaxy NGC 4051

We present an optical spectroscopic analysis of the well-known Seyfert galaxy NGC 4051. The high-ionization nuclear emission-line region (HINER) traced by [Fe X]6374 is found to be spatially extended to a radius of 3a rcseconds (150 pc) west and southwest from the nucleus; NGC 4051 is the third example which has an extended HINER. The nuclear spectrum shows that the flux of [Fe X]6374 is stronger than that of [Fe VII] 6087 in our observation. This property cannot be interpreted in terms of a simple one-zone photoionization model. In order to understand what happens in the nuclear region in NGC 4051, we investigate the physical condition of the nuclear emission-line region in detail using new photoionization models in which the following three emission-line components are taken into account; (1) optically thick, ionization-bounded clouds; (2) optically thin, matter-bounded clouds; and (3) a contamination component which emits H$\alpha$ and H$\beta$ lines. Here the observed extended HINER is considered to be associated with the low-density, matter-bounded clouds. Candidates of the contamination component are either the broad-line region (BLR) or nuclear star forming regions or both. The complexity of the excitation condition found in NGC 4051 can be consistently understood if we take account of these contamination components.Comment: 16 pages, including figures. To Appear in the Astronomical Journal February 2000 Issu

Multi-component analysis, molecular model construction, and thermodynamics performance prediction on various rejuvenators of aged bitumen

The molecular dynamics (MD) simulation method is proved as an efficient tool to explore the intermolecular interaction between rejuvenators and aged bitumen, but the simple “single-molecule” model of rejuvenator would bring the inaccuracy to simulation outputs due to a huge difference with its realistic multi-component chrematistic. This study aims to in-depth analyze the chemical components of four commonly-used rejuvenators with the Gas chromatography-mass spectrometry (GC–MS) method, and propose their multi-component molecular models for the first time. Further, MD simulations are performed on the multi-component models of various rejuvenators to anticipate and compare their atomic-level properties. The GC–MS results reveal that the chemical components of petroleum-based rejuvenators are more complicated than the bio-oil (BO). The alkane, naphthenic, and aromatic molecules are the main constituents of engine-oil (EO), naphthenic-oil (NO), and aromatic-oil (AO) rejuvenators. The experimental density results validate the reliability of these multi-component molecular models of four rejuvenators. From the MD simulations outputs, there is a significant difference in the energetic indices, cohesive energy density (CED), solubility parameter δ, volumetric parameters, dynamic behaviors, structural indicators, expansion coefficient (α and β), and isobaric heat capacity (Cp) between the multi-component models of four rejuvenators. However, the multi-component molecular model of aromatic-oil based on the GC–MS method is not accurate because the polycyclic aromatic molecules with heavy-weight are not detected and considered. This study detects the difference in chemical components and thermodynamics properties between four rejuvenators and proposes their more realistic multi-component molecular models for further MD simulations on the rejuvenation of aged bitumen

Water diffusion mechanisms in bitumen studied through molecular dynamics simulations

Water transport is one of the major factors responsible for moisture damage in asphalt pavements. To study the thermodynamics and kinetics of water transport in bitumen and to uncover microscale mechanisms of moisture-induced damage, molecular dynamics simulations were performed for up to 600 ns for water–bitumen systems with realistic water contents that varied from 0 to 1.76 wt%. Hydrogen bonding interactions and clustering of water molecules at various combinations of temperature and water content were investigated, and their effects on the self-diffusion coefficient of water and bitumen properties are computed and discussed. It is shown that the saturated water concentration in bitumen is small, especially at low temperatures, and additional water molecules tend to form large water clusters via hydrogen bonding, indicating micro-phase separation of the water and bitumen phases inside the simulation box. Hydrogen bonding and water clustering play a crucial role on the magnitude of the self-diffusion coefficient of water. Physical properties of bitumen that include viscosity and cohesive energy are affected by water. The presence of large water clusters is indicative of how degradation in cohesion is observed on the microscale

Molecular dynamics simulation on bulk bitumen systems and its potential connections to macroscale performance: Review and discussion

Molecular dynamics (MD) simulation plays an effective role in predicting the critical properties and explaining the macroscale phenomenon at the nanoscale. This review summarized the application cases of MD simulations in various bitumen systems, considering aging, modification, and rejuvenation factors. Meanwhile, the potential relationships between the nanoscale parameters predicted from MD simulations and macroscale properties measured from experimental tests were discussed for the first time. Different molecular models of virgin bitumen, commonly-used Forcefields, and validation parameters for MD simulations on bituminous materials were summarized. Based on the reactive MD simulation outputs, the oxidative aging reaction path at the atomic scale of bitumen molecules was reviewed. Furthermore, the influence of aging (short-term and long-term), modification (polymers, fillers, and bio-bitumen), and rejuvenation (various rejuvenators) on the molecular-scale properties of virgin bitumen models would be evaluated through MD simulations. This review could help us further explore the main functions of MD simulations in different bulk bitumen systems and build an integral multi-scale research method from the molecular design and performance prediction to material optimization and synthesis of bituminous materials without lots of experimental attempts

The Narrow Line Region of Ark 564

The continuum and emission-line spectrum of the narrow-line Seyfert 1 galaxy Ark 564 is used to investigate, for the first time, the physical conditions and structure of its narrow line region (NLR). For this purpose, composite models, accounting for the coupled effect of photoionization and shocks, are employed. The emission-line spectrum of Ark 564, which ranges from the ultraviolet to the near-infrared, shows a rich forbidden line spectrum. Strong emphasis is given to the study of the coronal line region. The diversity of physical conditions deduced from the observations requires multi-cloud models to reproduce the observed lines and continuum. We find that a combination of high velocity (Vs = 1500 km/s) shock-dominated clouds as well as low velocity (Vs = 150 km/s) radiation-dominated clouds explains the coronal lines, while the optical low-ionization lines are mainly explained by shock-dominated clouds. The results for Ark 564 are compared with those obtained for other Seyfert galaxies previously analyzed such as NGC 5252, Circinus, NGC 4051 and NGC 4151. The model results for the ultraviolet and optical permitted lines suggest that the broad line region may contribute up to 80%, depending on the emission-line, being of about 30% for Hbeta. The consistency of the multi-cloud model is checked by comparing the predicted and observed continuum, from radio to X-ray, and indicate that the dust-to-gas ratio in the clouds varies from 10^{-15} to 10^{-12}.Comment: 18 pages, 1 figure. Accepted in A&