bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fourier‐resolved spectroscopy of AGN using XMM‐Newton data
Authors: Papadakis I. E. , Ioannou Z. , Kazanas D. 
Published: November 2006

AbstractWe present a brief account of the theory on which the novel method of ‘Fourier‐resolved spectroscopy’ is based. We summarize the results from the past application of this method to the study of Galactic Black Hole candidate sources and MCG‐6‐30‐15, and we present new results from the Fourier‐resolved spectroscopy of archival XMM‐Newton data of five AGN, namely, Mrk 766, NGC 3516, NGC 3783, NGC 4051 and Ark 564. When we combine all the past and present results from Galactic sources and AGN, we find that the slope of the Fourier‐resolved spectra in accreting black hole systems decreases with increasing frequency as ∝ f –0.25, irrespective of whether the system is in its High or Low state. We find significant evidence that the iron line in Mrk 766, NGC 3783 and NGC 4051 is variable on time scales ∼1 day – 1 hour. There is an indication that, just like in Galactic sources, the equivalent width of the line in the Fourier‐resolved spectra of AGN decreases with increasing frequency. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
General Relativity effects and line emission
Authors: Matt G. 
Published: November 2006

AbstractGeneral Relativity effects (gravitational redshift, light bending, …) strongly modify the characteristics of the lines emitted close to the Black Hole in Active Galactic Nuclei and Galactic Black Hole systems. These effects are reviewed and illustrated, with particular emphasis on line emission from the accretion disc. Methods, based on the iron line, to measure the two astrophysically relevant parameters of a Black Hole, the mass and spin, are briefly discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Search for narrow energy‐shifted lines in AGN spectra in the XMMNewton archive
Authors: Longinotti A. L. , Bianchi S. , Guainazzi M. , Roa J. , Santos‐Lleo M. 
Published: November 2006

AbstractThanks to the large effective area and the spectral resolution of current X‐ray satellites, the detection of X‐ray narrow spectral features in the 5–7 keV band is becoming commonplace in many AGN observations. Such lines, both in emission and in absorption, are mostly interpreted as arising from Iron atoms. When observed with some displacement from their rest frame position, these lines carry the potential to study the motion of circumnuclear gas in AGN, providing a diagnostic of the effects of the gravitational field of the central black hole. These narrow features have been often found with marginal statistical significance. A systematic search for narrow features in type1 AGN is being performed on all spectra available in the XMM‐Newton archive with the aim to estimate the significance of the features with Monte Carlo simulations of synthetic spectra. The project and preliminary results are presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Statistics of relativistically broadened Fe Kα lines in AGN
Authors: Guainazzi M. , Bianchi S. , Dovčiak M. 
Published: November 2006

AbstractWe present preliminary results on the properties of relativistically broadened Fe Kα lines in a collection of more then 100 Active Galactic Nuclei (AGN) observed by the XMM‐Newton EPIC‐pn camera. Our main conclusions can be summarized as follows: a) we detect broad lines in about 25% of the sample objects. This fraction increases to 42 ± 13% if we consider only objects with more than 104 counts in the hard (2–10 keV) band, and to 50 ± 32% for the small sub‐sample (6 objects) of type 1 Piccinotti AGN with optimal XMM‐Newton exposure (at least 2 × 105 counts in the hard band); b) we find no significant difference in the detection rate of broad lines between obscured and unobscured AGN; c) the strongest relativistic profiles are measured in low‐luminosity (L X < 1043 erg s–1) AGN; d) Equivalent Widths (EWs) associated with relativistic profiles in stacked spectra are ≲150 eV for all luminosity classes; e) models of relativistically broadened iron line profiles (kyrline, Dovčiak et al. 2005), which include full relativistic treatment of the accretion disk emission around a Kerr black hole in the strong gravity regime, yield an average disk inclination angle ≃30°, and a radial dependence of the disk emissivity profile ≃–3. The distribution of EW is very broad, with 〈log (EW)〉 = 2.4 and σ log (EW) = 1.4. We estimate that an investment of about 1 Ms of XMM‐Newton time would be required to put these results on a sound statistical basis. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Connection between spectral complexity and X‐ray weakness: testing the reflection interpretation
Authors: Gallo L. C. 
Published: November 2006

AbstractIn recent work it was demonstrated that narrow‐line Seyfert 1 galaxies, which possessed spectral complexity in the 2–10 keV band were at the same time X‐ray weak. In this contribution I show how X‐ray weakness can be understood in the context of reflection and light bending picture. In fact, X‐ray weakness should be expected from objects that are in a reflection dominated state. With simultaneous UV and X‐ray data available with most XMM‐Newton observations, an estimate of the X‐ray weakness is relatively straightforward. As such, it is an easy way to substantiate conclusions of reflection dominated spectra, and we use this method to examine recent claims. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Suzaku observation of NGC 3516: complex absorption and the broad and narrow Fe K lines
Authors: Markowitz A. , Reeves J. N. , Serlemitsos P. , Yaqoob T. , Awaki H. , Fabian A. , Gallo L. , Griffiths R. E. , Kunieda H. , Miniutti G. , Mushotzky R. , Okajima T. 
Published: November 2006

AbstractWe present preliminary results from a 150 ks Suzaku observation of the Seyfert 1 galaxy NGC 3516. Suzaku 's wide bandpass has enabled us to deconvolve the broadband emitting and absorbing components in this object, breaking model degeneracies inherent in previous, smaller‐bandpass spectra. The primary power‐law continuum is absorbed by an ionized absorber as well as a partial‐covering absorber; the column density of the ionized absorber has increased by a factor of ∼3 since XMM‐Newton observations in 2001. We detect a soft power‐law component which may be scattered emission. We confirm the presence of the broad Fe line, finding a $ 185^{+130} _{-70} $ eV equivalent width line that indicates emission extending down to a few Schwarzschild radii. Models which exclude either the broad line or the partial‐covering absorber are rejected. Suzaku 's high effective area and low background near 6 keV also allow us to resolve the narrow Fe K emission line; we find a FWHM velocity width near 4000 km s–1, commensurate with Broad Line Region velocities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton monitoring observations of Mrk 3
Authors: Akylas A. , Georgantopoulos I. , Nandra K. 
Published: November 2006

AbstractWe present monitoring analysis of 8 XMM‐Newton observations of the Seyfert 2 galaxy Mrk 3, spanning a period of ∼19 months. The continuum flux in the 3–12 keV band remains constant during this observing period. The X‐ray spectrum is well described, in agreement with previous works, by a highly absorbed (N H > 1024 cm–2) power law model, with a photon index Γ = 1.9 and a strong reflection component. A strong Fe Kα line at 6.4 keV with an equivalent width of ∼500 eV is detected in the X‐ray spectrum. When we consider the co‐added spectrum we also detect a weaker emission line at 7.4 keV corresponding to neutral Ni Kα emission and weak evidence for the presence of an ionized Fe Kα line at 6.7 keV. Direct comparison with the results obtained from an earlier XMM‐Newton observation of Mrk 3, shows a decrease in the continuum flux of ∼30 per cent followed by a similar decrease in the reflected component. Both emission line components at 6.4 and 6.7 keV do not vary. However we find that an alternative model where the N H varies by 20 per cent is also plausible. In this case both the continuum and the reflected emission do not change. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Narrow‐Line Seyfert 1 Galaxies with high‐energy sharp spectral drops: reflection‐versus absorption models
Authors: Boller Th. 
Published: November 2006

AbstractWith the launch of XMM‐Newton in 1999, two Narrow‐Line Seyfert 1 Galaxies (NLS1s) have been detected (IRAS 13224–3809 and 1H 0707–495) showing sharp spectral drops at energies equal or above the neutral Fe K edge at 7.1 keV without any narrow Fe K reemission. In this paper I summarize our present knowledge on the observed properties of sharp high‐energy spectral drops. I list the problems presently arising from the reflection dominated and the optically thick disc models. Finally, I present an alternative solution which consists of a combination of the accretion disc model and the reflection dominated model. This might solve the problems of the standard accretion disc model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of dimerization of Serratia marcescens endonuclease on water dynamics
Authors: Chen Chuanying , Beck Brian W. , Krause Kurt , Weksberg Tiffany E. , Pettitt B. Montgomery 
Published: November 2006

AbstractThe dynamics and structure of Serratia marcescens endonuclease and its neighboring solvent are investigated by molecular dynamics (MD). Comparisons are made with structural and biochemical experiments. The dimer form is physiologic and functions more processively than the monomer. We previously found a channel formed by connected clusters of waters from the active site to the dimer interface. Here, we show that dimerization clearly changes correlations in the water structure and dynamics in the active site not seen in the monomer. Our results indicate that water at the active sites of the dimer is less affected compared with bulk solvent than in the monomer where it has much slower characteristic relaxation times. Given that water is a required participant in the reaction, this gives a clear advantage to dimerization in the absence of an apparent ability to use both active sites simultaneously. © 2006 Wiley Periodicals, Inc. Biopolymers 85: 241–252, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Genetische und linguistische Sprachspiele. Grenzen der Beliebigkeit
Authors: Wieser Wolfgang 
Published: November 2006

AbstractIn komplexen dynamischen Systemen wie dem biologischen Organismus und der menschlichen Sprache entsteht die Beziehung zwischen Zeichen (Form) und Bedeutung unter dem Druck einer Selektion und entwickelt sich weiter. Inwieweit von einer “Beliebigkeit” oder “Nichtbeliebigkeit” dieses Verhältnisses gesprochen werden kann, hängt von der Quelle (natürlich, künstlich, sozial), Stärke und Dauer des Angriffs der Selektion ab.
Der Keuper. Zeitreise ins Dinosaurierland
Authors: Nitsch Edgar 
Published: November 2006

AbstractWährend der späten Trias war Mitteleuropa ein subtropisches, überwiegend von Flusslandschaften und Seen geprägtes Tiefland, in welches das Meer nur selten und vorübergehend eindringen konnte. Die Ablagerungen des Keupers dokumentieren ein breites Spektrum fossiler Sedimentations‐ und Lebensräume – vom Flachmeer über Brack‐ und Süßwassermilieus bis auf das Festland, von sumpfigen Mooren bis zu trockenen Salzseen. Landtiere und Landpflanzen beherrschen ihrer Artenzahl nach die fossile Überlieferung und bezeugen eine Welt im Umbruch zwischen Überlebenden aus dem Paläozoikum und Pionieren des Mesozoikums: die letzten Calamiteen wuchsen im Schatten der ersten Benettiteen, die letzten Thecodontier jagten die ersten Dinosaurier – und umgekehrt –, die letzten Therapsiden wichen den ersten Säugetieren.
Die Evolution der Sprache: Vom Affenlaut zum Menschenwort
Authors: Jürgens Uwe 
Published: November 2006

AbstractAus der Untersuchung der kulturellen Entwicklung, der Hirnentwicklung und des Sprechapparates innerhalb der Hominiden lässt sich schließen, dass seit mindestens 40.000 Jahren eine differenzierte Sprache existiert. Die frühesten Anfänge von Sprache reichen möglicherweise sogar 2,5 Millionen Jahre zurück. Eine ihrer Wurzeln ist in den nicht‐verbalen emotionalen Lautäußerungen nicht‐menschlicher Primaten zu sehen. Die Entwicklung führte in einem jahrtausende währenden Prozess über ein Stadium zunehmender Willkürkontrolle über den Stimmapparat (die Affen abgeht) zu einfachen Protosprachen (Ein‐ und Zweiwortsätze mit fehlender Syntax und Grammatik, aber begleitender bedeutungstragender Gestik) zu Sprachen, wie wir sie heute kennen.
Angepasst an Schritt und Tritt? Pflanzen in Pflasterritzen
Authors: Lüthje Erich 
Published: November 2006

AbstractIst die Trittgesellschaft der Pflanzen im Pflaster des Schulhofes Folge einer evolutiven Anpassung? Diese Frage lässt sich vorzüglich im Unterricht diskutieren. Der Extremstandort “Pflasterritzen und ‐fugen” wird tatsächlich nur von wenigen Arten mit markanten Eignungsmerkmalen besiedelt. Diese erweisen sich bei näherer Betrachtung allerdings nicht als spezifische Anpassungen, wie auch die Trittpflanzen selbst keineswegs nur im Trittbereich zu finden sind. Der anthropogene Vertrittbereich konnte nicht Schauplatz ihrer Evolution sein. Ihre Eignung als Trittpflanzen erwarben sie als “Anpassung auf Verdacht” an verschiedenen Herkunftsorten – zumindest für Schüler ein unvermutetes Ergebnis!
Genetik und Krankheitsmechanismen erblicher Epilepsien
Authors: Heils Armin , Lerche Holger 
Published: November 2006

AbstractJeder Zwanzigste hat in seinem Leben mindestens einmal einen epileptischen Anfall. Doch erst, wenn bei einem Menschen wiederholt derartige Anfälle auftreten, spricht man von der Krankheit Epilepsie. Dahinter verbirgt sich eine große Anzahl unterschiedlicher Erkrankungen. Im NeuroNet des Nationalen Genomforschungsnetzes (NGFN) beschäftigen sich mehrere Arbeitsgruppen mit Epilepsie, um den genetischen Ursachen des Anfallsleidens auf die Spur zu kommen.
Auxin und die apikale Dominanz
Authors: Brennicke Axel 
Published: November 2006

AbstractEin Weihnachtsbaum ohne gute Spitze ist kein Weihnachtsbaum. Wie aber wächst eine schöne Spitze heran? Dafür ist nach klassischer Lehrmeinung das Hormon Auxin zuständig: Auxin wird in der Spitze des Haupttriebes gebildet und in der Pflanze nach unten transportiert. Dort unterdrückt es den Austrieb von Seitensprossen aus den ruhenden Knospen. Möglicherweise erreicht das Auxin jedoch gar nicht die Knospen selbst, sondern wirkt über den Syntheseweg der Carotenoide.
Nobelpreis für schweigende Gene
Authors: Gebhardt Nicole , Hellwig Katharina , Nellen Wolfgang 
Published: November 2006

AbstractDer Nobelpreis für Physiologie oder Medizin 2006 geht an die Molekularbiologen Andrew Fire (Stanford University, USA) und Craig Mello (University of Massachusetts, USA) für die Entdeckung der RNA‐Interferenz im Fadenwurm Caenorhabditis elegans. Durch diesen Mechanismus können Gene spezifisch ausgeschaltet werden.
Rate and Mechanism of the Reaction of Alkenes with Aryl Palladium Complexes Ligated by a Bidentate P,P Ligand in Heck Reactions
Authors: Amatore Christian , Godin Béatrice , Jutand Anny , Lemaître Frédéric 
Published: November 2006

AbstractThe regioselectivity of the Heck reaction is supposed to be highly affected by the electronic properties of the alkene and the ionic or neutral character of the aryl palladium(II) complexes involved in the reaction with alkenes. In Heck reactions performed in dmf, [Pd(dppp){dppp(O)}Ph]+ (dppp=1,2‐bis(diphenylphosphino)propane) is generated in the oxidative addition of PhI with [Pd0(dppp)(OAc)]− formed in situ from Pd(OAc)2 associated to two equivalents of dppp. [Pd(dppp){dppp(O)}Ph]+ is not very reactive with alkenes (styrene or methyl acrylate); however, it reacts with iodide ions (released in the catalytic reactions) to give [Pd(dppp)IPh] and with acetate ions (used as base) to give [Pd(dppp)(OAc)Ph]. [Pd(dppp)(OAc)Ph] reacts with styrene and methyl acrylate exclusively by an ionic mechanism, that is, via the cationic complex [Pd(dppp)(dmf)Ph]+ formed by dissociation of the acetate ion. The reaction of [Pd(dppp)IPh] is more complex and substrate dependent. It reacts with styrene exclusively by the ionic mechanism via [Pd(dppp)(dmf)Ph]+. [Pd(dppp)IPh] (neutral mechanism) and [Pd(dppp)(dmf)Ph]+ (ionic mechanism) react in parallel with methyl acrylate. [Pd(dppp)(dmf)Ph]+ is more reactive than [Pd(dppp)IPh] but is always generated at lower concentration.
An Easy‐To‐Use, Regioselective, and Robust Bis(amidate) Titanium Hydroamination Precatalyst: Mechanistic and Synthetic Investigations toward the Preparation of Tetrahydroisoquinolines and Benzoquinolizine Alkaloids
Authors: Zhang Zhe , Leitch David C. , Lu Man , Patrick Brian O. , Schafer Laurel L. 
Published: November 2006

AbstractAmidate‐supported titanium amido complexes are efficient and regioselective precatalysts for intermolecular hydroamination of terminal alkynes with primary amines. The synthesis and characterization of the first bis(amidate)‐supported titanium‐imido complex is reported. Its role as the active catalytic species is suggested in the course of product distribution studies using deuterated substrates. The bis(amidate)‐supported precatalysts exhibit good functional‐group tolerance, even performing hydroaminations in the presence of ester and amide groups. This functional‐group tolerance was exploited in the synthesis of a variety of 1‐substituted tetrahydroisoquinoline alkaloids and a one‐pot hydroaminative procedure for the high yielding preparation of the benzo[a]quinolizine skeleton.
La17Si9Al4N33‐xOx (x ≤ 1): A Nitridoaluminosilicate with Isolated Si/Al—N/O Clusters.
Authors: Pilet Guillaume , Grins Jekabs , Eden Mattias , Esmaeilzadeh Saeid 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
From Thorium Phosphate Hydrogenphosphate Hydrate to β‐Thorium Phosphate Diphosphate: Structural Evolution to a Radwaste Storage Ceramic.
Authors: Wallez Gilles , Clavier Nicolas , Dacheux Nicolas , Quarton Michel , van Beek Wouter 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Intermetallic Compounds with 1D Infinite Tunnels. Syntheses and Structures of AAu4In2 (A: K, Rb).
Authors: Li Bin , Corbett John D. 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Chiral Amino‐Amides as Solution Phase and Immobilized Ligands for the Catalytic Asymmetric Alkylation of Aromatic Aldehydes.
Authors: Lesma Giordano , Danieli Bruno , Passarella Daniele , Sacchetti Alessandro , Silvani Alessandra 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
New Efficient Organic Activators for Highly Enantioselective Reduction of Aromatic Ketones by Trichlorosilane.
Authors: Matsumura Yoshihiro , Ogura Kanako , Kouchi Yoshimi , Iwasaki Fumiaki , Onomura Osamu 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
An Efficient and Practical Synthesis of Chiral Imidazolium Ionic Liquids and Their Application in an Enantioselective Michael Reaction.
Authors: Ou Wen‐Hua , Huang Zhi‐Zhen 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Phosphine—Olefin Ligands: A Facile Dehydrogenative Route to Catalytically Active Rhodium Complexes.
Authors: Douglas Thomas M. , Le Notre Jerome , Brayshaw Simon K. , Frost Christopher G. , Weller Andrew S. 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Highly Efficient Alkylation to Ketones and Aldimines with Grignard Reagents Catalyzed by Zinc(II) Chloride.
Authors: Hatano Manabu , Suzuki Shinji , Ishihara Kazuaki 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of Novel Calix[4]arenes Containing One and Two Substituents on the “Upper Rim”.
Authors: Li Lei , Lv Ping , Xian Chunying , Zheng Limin 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Preparation of Aryl—Alkylamines via Electrophilic Amination of Functionalized Arylazo Tosylates with Alkylzinc Reagents.
Authors: Sinha Pradipta , Kofink Christiane C. , Knochel Paul 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Nickel‐Catalyzed Conjugate Addition of Arylboron Reagents to α,β‐Unsaturated Carbonyl Compounds with the Aid of a Catalytic Amount of an Alkyne.
Authors: Shirakawa Eiji , Yasuhara Yuichi , Hayashi Tamio 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Chiral Scandium Catalysts for Enantioselective Michael Reactions of β‐Ketoesters.
Authors: Ogawa Chikako , Kizu Keiko , Shimizu Haruka , Takeuchi Masahiko , Kobayashi Shu 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Tb6N@C84: An Improbable, Egg‐Shaped Endohedral Fullerene that Violates the Isolated Pentagon Rule.
Authors: Beavers Christine M. , Zuo Tianming , Duchamp James C. , Harich Kim , Dorn Harry C. , Olmstead Marilyn M. , Balch Alan L. 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Efficient Synthesis of 1,3,5‐Trisubstituted (Pyrrol‐2‐yl)acetic Acid Esters via Dual Nucleophilic Reactions of Sulfonamides or Carbamate with 4‐Trimethyl‐siloxy‐(5E)‐hexen‐2‐ynoates: Lewis Acid Catalyzed SN1 and Intramolecular Michael Addition.
Authors: Ishikawa Teruhiko , Aikawa Toshiaki , Watanabe Shinichiro , Saito Seiki 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Intermolecular Reactions of Chlorohydrine Anions: Acetalization of Carbonyl Compounds under Basic Conditions.
Authors: Barbasiewicz Michal , Makosza Mieczyslaw 
Published: November 2006

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.