Refine
Year of publication
Document Type
- Article (596)
- Preprint (299)
- Postprint (257)
- Conference Proceeding (160)
- Doctoral Thesis (51)
- Working Paper (48)
- Review (36)
- Monograph/Edited Volume (26)
- Part of a Book (24)
- Other (16)
Language
- English (1517) (remove)
Is part of the Bibliography
- no (1517) (remove)
Keywords
- Curriculum Framework (31)
- European values education (31)
- Europäische Werteerziehung (31)
- Familie (31)
- Family (31)
- Lehrevaluation (31)
- Studierendenaustausch (31)
- Unterrichtseinheiten (31)
- curriculum framework (31)
- lesson evaluation (31)
Institute
- Institut für Mathematik (309)
- Extern (259)
- Institut für Physik und Astronomie (119)
- Vereinigung für Jüdische Studien e. V. (108)
- Department Linguistik (91)
- Department Psychologie (86)
- Institut für Chemie (65)
- Hasso-Plattner-Institut für Digital Engineering GmbH (55)
- Historisches Institut (52)
- Institut für Umweltwissenschaften und Geographie (49)
A woman and a language
(2008)
Inhalt: 1. Introduction 2. Summary of the narratives 3. Classification and structure of the narratives 3.1 The Death of R. Johanan's Tenth Son 3.2 The King's Son and His Three False Friends 4. The context of the narratives in Beer Sheva and Glikl's Memoirs 4.1 The context in Beer Sheva 4.2 The context in Glikl's Memoirs 5. Conclusion
Information structure
(2007)
Semantics
(2007)
Syntax
(2007)
Morphology
(2007)
The annotation guidelines introduced in this chapter present an attempt to create a unique infrastructure for the encoding of data from very different languages. The ultimate target of these annotations is to allow for data retrieval for the study of information structure, and since information structure interacts with all levels of grammar, the present guidelines cover all levels of grammar too. After introducing the guidelines, the current chapter also presents an evaluation by means of measurements of the inter-annotator agreement.
Phonology and intonation
(2007)
The encoding standards for phonology and intonation are designed to facilitate consistent annotation of the phonological and intonational aspects of information structure, in languages across a range of prosodic types. The guidelines are designed with the aim that a nonspecialist in phonology can both implement and interpret the resulting annotation.
In 2002 guidelines for the implementation of the internship programme for prospective teachers have been released in a joint venture by the Basic Education Sector Programme(BESP) of the GTZ (Gesellschaft für Technische Zusammenarbeit/German Technical Cooperation) and the Professional Development Centre (Teacher Education) of the National Institute for Education of Sri Lanka (NIE). These guidelines aim at assisting the National Colleges of Education (NCOEs) and internship schools in implementing the internship programme and at improving its efficiency and effectiveness in the local venues of teacher training. The Monitoring & Evaluation activity described in the present article was to assess as to how far the intentions originally associated with the internship programme are being accomplished. Its main task is to bring strengths and weaknesses of the programme to light and to appraise the current status of its implementation.
The concept of the virtual corporation (VC), which describes a modern form of collaboration among organizations, was introduced in the scientific discussion in the mid 1990th. The practice shows that VCs need new forms of governance because the traditional mechanisms of control, management, and steering are hardly applicable. Until now there is only a few research related to the question how to govern VC. The main problems to govern a VC are to coordinate the communication among dispersed partners and to motivate employees to actively involve themselves into the network. Open source projects are confronted with similar problems. As several governance mechanisms are already analyzed in this context, the authors analyze and adopt governance concepts from open source projects to extract a governance framework for virtual corporations. This new approach leads to innovative insights in governing virtual corporations by using community techniques as an appropriate way for communication and collaboration purposes.
The requirements of modern e-learning techniques change. Aspects such as community interaction, flexibility, pervasive learning and increasing mobility in communication habits become more important. To meet these challenges e-learning platforms must provide support on mobile learning. Most approaches try to adopt centralised and static e-learning mechanisms to mobile devices. However, often technically it is not possible for all kinds of devices to be connected to a central server. Therefore we introduce an application of a mobile e-learning network which operates totally decentralised with the help of an underlying ad hoc network architecture. Furthermore the concept of ad hoc messaging network (AMNET) is used as basis system architecture for our approach to implement a platform for pervasive mobile e-learning.
Rezensiertes Werk: Frontiers and the writing of history, 1500-1850 / ed. by Steven G. Ellis and Raingard Esser. - Hannover-Laatzen : Wehrhahn, 2006. - 318 S. ISBN 3–86525–251-6
Rezensiertes Werk: Caferro, William: John Hawkwood : an English mercenary in fourteenth-century Italy / William Caferro. - Baltimore : Johns Hopkins University Press, 2006. - XV, 459 S. ISBN 0-8018-8323-7
Rezensiertes Werk: Arfaioli, Maurizio: The black bands of Giovanni : infantry and diplomacy during the Italian wars; 1526-1528 / Maurizio Arfaioli. - Pisa : Edizioni Plus-Pisa University Press, 2005. - 204 S.: Ill. ISBN 88-8492-231-3
Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface
(1986)
Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data are discussed.
Cinnamic acid moieties were incorporated into amphiphilic compounds containing one and two alkyl chains. These lipid-like compounds with photoreactive units undergo self-organization to form monolayers at the gas-water interface and bilayer structures (vesicles) in aqueous solutions. The photoreaction of the cinnamic acid moiety induced by 254 nm UV light was investigated in the crystalline state, in monolayers, in vesicles and in solution in organic solvents. The single-chain amphiphiles undergo dimerization to yield photoproducts with twice the molecular weight of the corresponding monomers in organized systems. The photoreaction of amphiphiles containing two cinnamic acid groups occurs via two mechanisms: The intramolecular dimerization produces bicycles, with retention of the molecular weight of the corresponding monomer. The intermolecular reaction leads to oligomeric and polymeric photoproducts. In contrast to the single-chain amphiphiles, photodimerization processes of lipoids containing two cinnamic acid moieties also occur in solution in organic solvents.
Sinefungin inhibited the S-adenosylmethionine-dependent farnesoic acid methyltransferase in a cell-free system containing a homogenate of corpora allata from female locusts, Locusta migratoria. The enzyme catalyzed the penultimate step of juvenile hormone biosynthesis in the insects. Culturing corpora allata in the presence of sinefungin greatly suppressed juvenile hormone production. The following in vivo effects were visible after injection of the inhibitor: increase in mortality and reduction of total haemolymph protein liter and ovary fresh weight, as well as length of terminal oocytes. Attempts to reverse these effects by topical application of the juvenile hormone analog ZR-515 (methoprene) were only partly successful. Therefore, the in vivo effects may be due to a general inhibition of methyltransferase enzymes in the insect. Sinefungin appeared to be of potential interest as the first representative of a new class of insect growth regulators.
The spectral efficiency of blackness induction was measured in three normal trichromatic observers and in one deuteranomalous observer. The psychophysical task was to adjust the radiance of a monochromatic 60–120′ annulus until a 45′ central broadband field just turned black and its contour became indiscriminable from a dark surrounding gap that separated it from the annulus. The reciprocal of the radiance required to induce blackness with annulus wavelengths between 420 and 680 nm was used to define a spectral-efficiency function for the blackness component of the achromatic process. For each observer, the shape of this blackness-sensitivity function agreed with the spectral-efficiency function based on heterochromatic flicker photometry when measured with the same 60–120′ annulus. Both of these functions matched the Commission Internationale de l'Eclairage Vλ function except at short wavelengths. Ancillary measurements showed that the latter difference in sensitivity can be ascribed to nonuniformities of preretinal absorption, since the annular field excluded the central 60′ of the fovea. Thus our evidence indicates that, at least to a good first approximation, induced blackness is inversely related to the spectral-luminosity function. These findings are consistent with a model that separates the achromatic and the chromatic pathways.
The development of phonetic codes in memory of 141 pairs of normal and disabled readers from 7.8 to 16.8 years of age was tested with a task adapted from L. S. Mark, D. Shankweiler, I. Y. Liberman, and C. A. Fowler (Memory & Cognition, 1977, 5, 623–629) that measured false-positive errors in recognition memory for foil words which rhymed with words in the memory list versus foil words that did not rhyme. Our younger subjects replicated Mark et al., showing a larger difference between rhyming and nonrhyming false-positive errors for the normal readers. The older disabled readers' phonetic effect was comparable to that of the younger normal readers, suggesting a developmental lag in their use of phonetic coding in memory. Surprisingly, the normal readers' phonetic effect declined with age in the recognition task, but they maintained a significant advantage across age in the auditory WISC-R digit span recall test, and a test of phonological nonword decoding. The normals' decline with age in rhyming confusion may be due to an increase in the precision of their phonetic codes.
Linguistic and psycholinguistic accounts based on the study of English may prove unreliable as guides to sentence processing in even closely related languages. The present study illustrates this claim in a test of sentence interpretation by German-, Italian-, and English-speaking adults. Subjects were presented with simple transitive sentences in which contrasts of (1) word order, (2) agreement, (3) animacy, and (4) stress were systematically varied. For each sentence, subjects were asked to state which of the two nouns was the actor. The results indicated that Americans relied overwhelming on word order, using a first-noun strategy in NVN and a second-noun strategy in VNN and NNV sentences. Germans relied on both agreement and animacy. Italians showed extreme reliance on agreement cues. In both German and Italian, stress played a role in terms of complex interactions with word order and agreement. The findings were interpreted in terms of the “competition model” of Bates and MacWhinney (in H. Winitz (Ed.), Annals of the New York Academy of Sciences Conference on Native and Foreign Language Acquisition. New York: New York Academy of Sciences, 1982) in which cue validity is considered to be the primary determinant of cue strength. According to this model, cues are said to be high in validity when they are also high in applicability and reliability.
The optical density of human macular pigment was measured for 50 observers ranging in age from 10 to 90 years. The psychophysical method required adjusting the radiance of a 1°, monochromatic light (400–550 nm) to minimize flicker (15 Hz) when presented in counterphase with a 460 nm standard. This test stimulus was presented superimposed on a broad-band, short-wave background. Macular pigment density was determined by comparing sensitivity under these conditions for the fovea, where macular pigment is maximal, and 5° temporally. This difference spectrum, measured for 12 observers, matched Wyszecki and Stiles's standard density spectrum for macular pigment. To study variation in macular pigment density for a larger group of observers, measurements were made at only selected spectral points (460, 500 and 550 nm). The mean optical density at 460 nm for the complete sample of 50 subjects was 0.39. Substantial individual differences in density were found (ca. 0.10–0.80), but this variation was not systematically related to age.
The inhibitory effect of sinefungin on juvenile hormone biosynthesis and development in locusts
(1987)
The antibiotic fungal metabolite sinefungin is a potent inhibitor of S-adenosylmethionine-acceptor methyltransferases. Its effect on insect metabolism and especially on corpora allata farnesoic acid methyltransferase, which catalyzes the penultimate step of juvenile hormone biosynthesis, was investigated in Locusta migratoria. Injection of sinefungin results in a delay of imaginal molt and in suppression of ovary development. Isolated corpora allata are unable to synthesize juvenile hormone III in the presence of more than 1.0 mM sinefungin. In a cell-free system containing the S-adenosylmethionine-dependent farnesoic acid methyltransferase from corpora allata sinefungin is a competitive inhibitor of the synthesis of methylfarnesoate with Ki of 1 μM.
An der Universität Potsdam wird seit 2008 ein automatisiertes Verfahren angewandt, um Bruchparamter großer Erdbeben in quasi-Echtzeit, d.h. wenige Minuten nachdem sich das Beben ereignet hat, zu bestimmen und der Öffentlichkeit via Internet zur Verfügung zu stellen. Es ist vorgesehen, das System in das Deutsch-Indonesische Tsunamifrühwarnsystem (GITEWS) zu integrieren, für das es speziell konfiguriert ist. Wir bestimmen insbesondere die Dauer und die Ausdehnung des Erdbebens, sowie dessen Bruchgeschwindigkeit und -richtung. Dabei benutzen wir die Seismogramme der zuerst eintreffenden P Wellen vom Breitbandstationen in teleseimischer Entfernung vom Beben sowie herkömmliche Arrayverfahren in teilweise modifizierter Form. Die Semblance wir als Ähnlichkeitsmaß verwendet, um Seismogramme eines Stationsnetzes zu vergleichen. Im Falle eines Erdbebens ist die Semblance unter Berücksichtigung des Hypozentrums zur Herdzeit und während des Bruchvorgangs deutlich zeitlich und räumlich erhöht und konzentriert. Indem wir die Ergebnisse verschiedener Stationsnetzwerke kombinieren, erreichen wir Unabhängigkeit von der Herdcharakteristik und eine raum-zeitliche Auflösung, die es erlaubt die o.g. Parameter abzuleiten. In unserem Beitrag skizzieren wir die Methode. Anhand der beiden M8.0 Benkulu Erdbeben (Sumatra, Indonesien) vom 12.09.2007 und dem M8.0 Sichuan Ereignis (China) vom 12.05.2008 demonstrieren wir Auflösungsmöglichkeiten und vergleichen die Ergebnisse der automatisierten Echtzeitanwendung mit nachträglichen Berechnungen. Weiterhin stellen wir eine Internetseite zur Verfügung, die die Ergebnisse präsentiert und animiert. Diese kann z.B. in geowissenschaftlichen Einrichtungen an Computerterminals gezeigt werden. Die Internetauftritte haben die folgenden Adressen: http://www.geo.uni-potsdam.de/arbeitsgruppen/Geophysik_Seismologie/forschung/ruptrack/openday http://www.geo.uni-potsdam.de/arbeitsgruppen/Geophysik_Seismologie/forschung/ruptrack
In Allefeld & Kurths [2004], we introduced an approach to multivariate phase synchronization analysis in the form of a Synchronization Cluster Analysis (SCA). A statistical model of a synchronization cluster was described, and an abbreviated instruction on how to apply this model to empirical data was given, while an implementation of the corresponding algorithm was (and is) available from the authors. In this letter, the complete details on how the data analysis algorithm is to be derived from the model are filled in.
In order to investigate the temporal characteristics of cognitive processing, we apply multivariate phase synchronization analysis to event-related potentials. The experimental design combines a semantic incongruity in a sentence context with a physical mismatch (color change). In the ERP average, these result in an N400 component and a P300-like positivity, respectively. The synchronization analysis shows an effect of global desynchronization in the theta band around 288ms after stimulus presentation for the semantic incongruity, while the physical mismatch elicits an increase of global synchronization in the alpha band around 204ms. Both of these effects clearly precede those in the ERP average. Moreover, the delay between synchronization effect and ERP component correlates with the complexity of the cognitive processes.
Phase synchronization analysis, including our recently introduced multivariate approach, is applied to event-related EEG data from an experiment on language processing, following a classic psycholinguistic paradigm. For the two types of experimental manipulation distinct effects in overall synchronization are found; for one of them they can also be localized. The synchronization effects occur earlier than those found by the conventional analysis method, indicating that the new approach provides additional information on the underlying neuronal process.
A method for the multivariate analysis of statistical phase synchronization phenomena in empirical data is presented. A first statistical approach is complemented by a stochastic dynamic model, to result in a data analysis algorithm which can in a specific sense be shown to be a generic multivariate statistical phase synchronization analysis. The method is applied to EEG data from a psychological experiment, obtaining results which indicate the relevance of this method in the context of cognitive science as well as in other fields.
We present different tests for phase synchronization which improve the procedures currently used in the literature. This is accomplished by using a two-samples test setup and by utilizing insights and methods from directional statistics and bootstrap theory. The tests differ in the generality of the situation in which they can be applied as well as in their complexity, including computational cost. A modification of the resampling technique of the bootstrap is introduced, making it possible to fully utilize data from time series.
The requirements of modern e-learning techniques change. Aspects such as community interaction, flexibility, pervasive learning and increasing mobility in communication habits become more important. To meet thesechallenges e-learning platforms must provide support on mobile learning. Most approaches try to adopt centralized and static elearning mechanisms to mobile devices. However, often technically it is not possible for all kinds of devices to be connected to a central server. Therefore we introduce an application of a mobile e-learning network which operates totally decentralized with the help of an underlying ad hoc network architecture. Furthermore the concept of ad hoc messaging network (AMNET) is used as basis system architecture for our approach to implement a platform for pervasive mobile elearning.
In recent years, the development of software in open source communities has attracted immense attention from research and practice. The idea of commercial quality, free software, and open source code accelerated the development of well-designed open source software such as Linux, Apache tools, or Perl. Intrinsic motivation, group identification processes, learning, and career concerns are the key drivers for a successful cooperation among the participants. These factors and most mechanisms of control, coordination, and monitoring forms of open source communities can hardly be explained by traditional organizational theories. In particular, the micro and macro structures of open source communities and their mode of operation are hardly compatible with the central assumption of the New Institutional Theory, like opportunistic behavior. The aim of this contribution is to identify factors that sustain the motivation of the community members over the entire life cycle of an open source project. Adequate coordination and controlling mechanisms for the governance in open source communities may be extracted.
Several types of insect cuticle contain enzymes catalyzing the formation ofof adducts between N-acetyldopamine (NADA) and N-acetylhistidine (NAH). Two such adducts, NAH-NADA-I and NAH NADA-II, have been isolated and their structures determined. In one of the adducts the link connecting the two residues occurs between the I-position (ß-position) in the NADA side chain and the 1-N atom (τ-N) in the imidazole ring of histidine. Diphenoloxidase activity alone is not sufficient for formation of this adduct, whereas extracts containing both diphenoloxidase and o-quinone-p-quinone methide isomerase activities catalyze the coupling reaction. The adduct consists of a mixture of two diastereomers and they are presumably formed by spontaneous reaction between enzymatically produced NADA-p-quinone methide and N-acetylhistidine. The other adduct has been identified as a ring addition product of N-acetylhistidine and NADA. In contrast to the former adduct it can be formed by incubation of the two substrates with mushroom tyrosinase alone. An adduct between N-acetylhistidine and the benzodioxan-type NADA-dimer is produced in vitro, when the N-acetylhistidine-NADA adduct is incubated with NADA and locust cuticle containing a 1,2-dehydro-NADA generating enzyme system. Trimeric NADA-polymerization products of the substituted benzodioxan-type have been obtained from in vivo sclerotized locust cuticle, confirming the ability of cuticle to produce NADA-oligomers. The results indicate that some insect cuticles contain enzymes promoting linkage of oxidized NADA to histidine residues. It is suggested that histidine residues in the cuticular proteins can serve as acceptors for oxidized NADA and that further addition of NADA-residues to the phenolic groups of bound NADA can occur, resulting in formation of protein-linked NADA-oligomers. The coupling reactions identified may be an important step in natural cuticular sclerotization.
Fast analysis of different species of molecules in soils is investigated by capillary electrophoresis (CE). Several CE techniques for the analysis of inorganic ions and carbohydrates have been tested. With regard to the intents of pedologists and the usually large number of soil analyses a bundle of CE systems is proposed, capable of effecting time-saving soil analyses. Adapted electrolyte systems recently published and new separation systems are described. Examples of the application of these methods to two different soil samples are presented.
The haemolymph of the adult Colorado potato beetle, Lepinotarsa decemlineata Say, contains a high molecular weight (MW > 200,000) JH-III specific binding protein. The Kd value of the protein for racemic JH-III is 1.3 ± 0.2 × 10−7 M. It has a lower affinity for racemic JH-I and it does not bind JH-III-diol or JH-III-acid. The binding protein does discriminate between the enantiomers of synthetic, racemic JH-III as was determined by stereochemical anaysis of the bound and the free JH-III. Incubation of racemic JH-III with crude haemolymph results in preferential formation of (10S)-JH-III-acid, the unnatural configuration. The JH-esterase present in L. decemlineata haemolymph is not enantioselective. It is concluded that the most important function of the binding protein is that of a specific carrier, protecting the natural hormone against degradation by esterases. The carrier does not protect JH-I as efficiently as the lower homologue.
The site of confluence of the artery and the portal vein in the liver still appears to be controversial. Anatomical studies suggested a presinusoidal or an intrasinusoidal confluence in the first, second or even final third of the sinusoids. The objective of this investigation was to study the problem with functional biochemical techniques. Rat livers were perfused through the hepatic artery and simultaneously either in the orthograde direction from the portal vein to the hepatic vein or in the retrograde direction from the hepatic vein to the portal vein. Arterial how was linearly dependent on arterial pressure between 70 cm H2O and 120 cm H2O at a constant portal or hepatovenous pressure of 18 cm H2O. An arterial pressure of 100 cm H2O was required for the maintenance of a homogeneous orthograde perfusion of the whole parenchyma and of a physiologic ratio of arterial to portal how of about 1:3. Glucagon was infused either through the artery or the portal vein and hepatic vein, respectively, to a submaximally effective ''calculated'' sinusoidal concentration after mixing of 0.1 nmol/L. During orthograde perfusions, arterial and portal glucagon caused the same increases in glucose output. Yet during retrograde perfusions, hepatovenous glucagon elicited metabolic alterations equal to those in orthograde perfusions, whereas arterial glucagon effected changes strongly reduced to between 10% and 50%. Arterially infused trypan blue was distributed homogeneously in the parenchyma during orthograde perfusions, whereas it reached clearly smaller areas of parenchyma during retrograde perfusions. Finally, arterially applied acridine orange was taken up by all periportal hepatocytes in the proximal half of the acinus during orthograde perfusions but only by a much smaller portion of periportal cells in the proximal third of the acinus during retrograde perfusions. These findings suggest that in rat liver, the hepatic artery and the portal vein mix before and within the first third of the sinusoids, rather than in the middle or even last third.
The names of God and the celestial powers : their function and meaning in the Hekhalot literature
(1987)
Excerpt: "Names and adjurations are the two main theurgic means found in the Hekhalot literature applied in connect ion with the descent to the Merkhavah and the invocation of angels to come down to earth and to reveal secrets," says Ithamar Gruenwald in his book on the Merkavah literature. He continues and maintains, with Gershom Scholem, that "that particular element in the Hekhalot Literature actually belonged to its very heart and this almost from its beginning." It is very seductive for the student of this literature to go straight to the heart of these texts; but the danger of this approach is as great as the danger of yeridat merkavah itself. Indeed, I feel as if I am passing the gates of the Hekhalot, the watchers of the gates standing on both sides prepared to throw their iron axes at my head. I can only hope that I may present the proper names! [...]
Focus and Tone
(2007)
Tone is a distinctive feature of the lexemes in tone languages. The information-structural category focus is usually marked by syntactic and morphological means in these languages, but sometimes also by intonation strategies. In intonation languages, focus is marked by pitch movements, which are also perceived as tone. The present article discusses prosodic focus marking in these two language types.
Three dimensions can be distinguished in a cross-linguistic account of information structure. First, there is the definition of the focus constituent, the part of the linguistic expression which is subject to some focus meaning. Second and third, there are the focus meanings and the array of structural devices that encode them. In a given language, the expression of focus is facilitated as well as constrained by the grammar within which the focus devices operate. The prevalence of focus ambiguity, the structural inability to make focus distinctions, will thus vary across languages, and within a language, across focus meanings.
Contrastive focus
(2007)
The article puts forward a discourse-pragmatic approach to the notoriously evasive phenomena of contrastivity and emphasis. It is argued that occurrences of focus that are treated in terms of ‘contrastive focus’, ‘kontrast’ (Vallduví & Vilkuna 1998) or ‘identificational focus’ (É. Kiss 1998) in the literature should not be analyzed in familiar semantic terms like introduction of alternatives or exhaustivity. Rather, an adequate analysis must take into account discourse-pragmatic notions like hearer expectation or discourse expectability of the focused content in a given discourse situation. The less expected a given content is judged to be for the hearer, relative to the Common Ground, the more likely a speaker is to mark this content by means of special grammatical devices, giving rise to emphasis.
New evidence is provided for a grammatical principle that singles out contrastive focus (Rooth 1996; Truckenbrodt 1995) and distinguishes it from discourse-new “informational” focus. Since the prosody of discourse-given constituents may also be distinguished from discourse-new, a three-way distinction in representation is motivated. It is assumed that an F-feature marks just contrastive focus (Jackendoff 1972, Rooth 1992), and that a G-feature marks discoursegiven constituents (Féry and Samek-Lodovici 2006), while discoursenew is unmarked. A crucial argument for G-marking comes from second occurrence focus (SOF) prosody, which arguably derives from a syntactic representation where SOF is both F-marked and G-marked. This analysis relies on a new G-Marking Condition specifying that a contrastive focus may be G-marked only if the focus semantic value of its scope is discourse-given, i.e. only if the contrast itself is given.
Focus presuppositions
(2007)
This paper reviews notions related to focus and presupposition and addresses the hypothesis that focus triggers an existential presupposition. Presupposition projection behavior in certain examples appears to favor a presuppositional analysis of focus. It is argued that these examples are open to a different analysis using givenness theory. Overall, the analysis favors a weak semantics for focus not including an existential presupposition.
While the Information Structure (IS) is most naturally interpreted as 'structure of information', some may argue that it is structure of something else, and others may object to the use of the word 'structure'. This paper focuses on the question of whether the informational component can have structural properties such that it can be called 'structure'. The preliminary conclusion is that, although there are some vague indications of structurehood in it, it is perhaps better understood to be a representation that encodes a finite set of information-based partitions, rather than structure.
Topic and focus
(2007)
The paper explicates the notions of topic, contrastive topic, and focus as used in the analysis of Hungarian. Based on distributional criteria, topic and focus are claimed to represent distinct structural positions in the left periphery of the Hungarian sentence, associated with logical rather than discourse functions. The topic is interpreted as the logical subject of predication. The focus is analyzed as a derived main predicate, specifying the referential content of the set denoted by the backgrounded post-focus section of the sentence. The exhaustivity associated with the focus and the existential presupposition associated with the background are shown to be properties following from their specificational predication relation.
This article takes stock of the basic notions of Information Structure (IS). It first provides a general characterization of IS — following Chafe (1976) — within a communicative model of Common Ground(CG), which distinguishes between CG content and CG management. IS is concerned with those features of language that concern the local CG. Second, this paper defines and discusses the notions of Focus (as indicating alternatives) and its various uses, Givenness (as indicating that a denotation is already present in the CG), and Topic (as specifying what a statement is about). It also proposes a new notion, Delimitation, which comprises contrastive topics and frame setters, and indicates that the current conversational move does not entirely satisfy the local communicative needs. It also points out that rhetorical structuring partly belongs to IS.
The paper presents a novel approach to explaining word order variation in the early Germanic languages. Initial observations about verb placement as a device marking types of rhetorical relations made on data from Old High German (cf. Hinterhölzl & Petrova 2005) are now reconsidered on a larger scale and compared with evidence from other early Germanic languages. The paper claims that the identification of information-structural domains in a sentence is best achieved by taking into account the interaction between the pragmatic features of discourse referents and properties of discourse organization.
The paper presents an in-depth study of focus marking in Gùrùntùm, a West Chadic language spoken in Bauchi Province of Northern Nigeria. Focus in Gùrùntùm is marked morphologically by means of a focus marker a, which typically precedes the focus constituent. Even though the morphological focus-marking system of Gùrùntùm allows for a lot of fine-grained distinctions in information structure (IS) in principle, the language is not entirely free of focus ambiguities that arise as the result of conflicting IS- and syntactic requirements that govern the placement of focus markers. We show that morphological focus marking with a applies across different types of focus, such as newinformation, contrastive, selective and corrective focus, and that a does not have a second function as a perfectivity marker, as is assumed in the literature. In contrast, we show at the end of the paper that a can also function as a foregrounding device at the level of discourse structure.
A series of production and perception experiments investigating the prosody and well-formedness of special sentences, called Wide Focus Partial Fronting (WFPF), which consist of only one prosodic phrase and a unique initial accented argument, are reported on here. The results help us to decide between different models of German prosody. The absence of pitch height difference on the accent of the sentence speaks in favor of a relative model of prosody, in which accents are scaled relative to each other, and against models in which pitch accents are scaled in an absolute way. The results also speak for a model in which syntax, but not information structure, influences the prosodic phrasing. Finally, perception experiments show that the prosodic structure of sentences with a marked word order needs to be presented for grammaticality judgments. Presentation of written material only is not enough, and falsifies the results.
Focus asymmetries in Bura
(2008)
(Chadic), which exhibits a number of asymmetries: Grammatical focus marking is obligatory only with focused subjects, where focus is marked by the particle án following the subject. Focused subjects remain in situ and the complement of án is a regular VP. With nonsubject foci, án appears in a cleft-structure between the fronted focus constituent and a relative clause. We present a semantically unified analysis of focus marking in Bura that treats the particle as a focusmarking copula in T that takes a property-denoting expression (the background) and an individual-denoting expression (the focus) as arguments. The article also investigates the realization of predicate and polarity focus, which are almost never marked. The upshot of the discussion is that Bura shares many characteristic traits of focus marking with other Chadic languages, but it crucially differs in exhibiting a structural difference in the marking of focus on subjects and non-subject constituents.
Intonation and discourse
(2007)
This paper surveys a range of constructions in which prosody affects discourse function and discourse structure.We discuss English tag questions, negative polar questions, and what we call “focus” questions. We postulate that these question types are complex speech acts and outline an analysis in Segmented Discourse Representation Theory (SDRT) to account for the interactions between prosody and discourse.
This paper deals with the conditions under which singular definites, on the one hand, and universally quantified DPs, on the other hand, receive interpretations according to which the sets denoted by the NP-complements of the respective determiner vary with the situations quantified over by a Q-adverb. I show that in both cases such interpretations depend on the availability of situation predicates that are compatible with the presuppositions associated with the respective determiner, as co-variation in both cases comes about via the binding of a covert situation variable that is contained within the NP-complement of the respective determiner. Secondly, I offer an account for the observation that the availability of a co-varying interpretation is more constrained in the case of universally quantified DPs than in the case of singular definites, as far as word order is concerned. This is shown to follow from the fact that co-varying definites in contrast to universally quantified DPs are inherently focus-marked.
Human manual action exhibits a differential use of a non-dominant (typically, left) and a dominant (typically, right) hand. Human communication exhibits a pervasive structuring of utterances into topic and comment. I will point out striking similarities between the coordination of hands in bimanual actions, and the structuring of utterances in topics and comments. I will also show how principles of bimanual coordination influence the expression of topic/comment structure in sign languages and in gestures accompanying spoken language, and suggest that bimanual coordination might have been a preadaptation of the development of information structure in human communication.
Focus expressions in Foodo
(2007)
This paper aims at presenting different ways of expressing focus in Foodo, a Guang language. We can differentiate between marked and unmarked focus strategies. The marked focus expressions are first syntactically characterized: the focused constituent is in sentence-initial position and is second always marked obligatorily by a focus marker, which is nɩ for non-subjects and N for subjects. Complementary to these structures, Foodo knows an elliptic form consisting of the focused constituent and a predication marker gɛ́. It will be shown that the two focus markers can be analyzed as having developed out of the homophone conjunction nɩ and that the constraints on the use of the focus markers can be best explained by this fact.
The paper investigates focus marking devices in the scarcely documented North-Ghanaian Gur language Konkomba. The two particles lé and lá occur under specific focus conditions and are therefore regarded as focus markers in the sparse literature. Comparing the distribution and obligatoriness of both alleged focus markers however, I show that one of the particles, lé, is better analyzed as a connective particle, i.e. as a syntactic rather than as a genuine pragmatic marker, and that comparable syntactic focus marking strategies for sentence-initial constituents are also known from related languages.
Prosodic focus in Vietnamese
(2007)
This paper reports on pilot work on the expression of Information Structure in Vietnamese and argues that Focus in Vietnamese is exclusively expressed prosodically: there are no specific focus markers, and the language uses phonology to express intonational emphasis in similar ways to languages like English or German. The exploratory data indicates that (i) focus is prosodically expressed while word order remains constant, (ii) listeners show good recoverability of the intended focus structure, and (iii) that there is a trading relationship between several phonetic parameters (duration, f0, amplitude) involved to signal prosodic (acoustic) emphasis.
Extract: [...]Of all the print-media newspapers are the most commonly used. They are not literature in the sense of belles letters, but they should not be underestimated in their political, social and personal importance. No other printed product is as closely linked with everyday life as the newspapers. The day begins under their influence, and their contents mirror the events of the day with varying accuracy. Newspapers are strongly reader-oriented. They want to inform, but they also want to instil opinions. Specific choices of information shape the content level. Specific choices of language are resorted to in order to spread opinions and viewpoints. Language creates solidarity between the producers and the consumers of newspapers and thereby supports ideologies by specifically targeted linguistic means. Other strategies are employed for the same purpose, too. Visual aspects are of great importance, such as the typographical layout, the use of pictures, drawings, colours, fonts, etc.[...]
Conventional wisdom since the earliest studies of Irish English has attributed much of what is distinctive about this variety to the influence of the Irish language. From the early philologists (Joyce 1910, van Hamel 1912) through the classic works of Henry (1957, 1958) and Bliss (1979) down to present-day linguistic orientations (e.g. Corrigan 2000 a, Filppula 1999, Fiess 2000, Hickey 2000, Todd 1999, and others), the question of Irish-language influence may be disputed on points of detail, but remains a central focus for most studies in the field. It is not our intention to argue with this consensus, nor to examine specific points of grammar in detail, but, rather, to suggest an approach to this question which (a) takes for its empirical base a sample of the standard language, rather than dialectal material or the sample sentences so beloved of many papers on the subject, and (b) understands Celticity not just in terms of the formal transfer of grammatical features, but as an indexical feature of language use, i.e. one in which English in Ireland is used in such a way as to point to the Irish language as a linguistic and cultural reference point. In this sense, our understanding of Celticity is not entirely grammatical, but relies as well on Pierce’s notion of indexicality (see Greenlee 1973), by which semiotic signs ‘point to’ other signs. Our focus in assessing Celticity, then, derives in the first instance from an examination of the International Corpus of English (ICE). We have recently completed the publication of the Irish component of ICE (ICE-Ireland), a machinereadable corpus of over 1 million words of speech and writing gathered from a range of contexts determined by the protocols of the global International Corpus of English project. The international nature of this corpus project makes for ready comparisons with other varieties of English, and in this paper we will focus on comparisons with the British corpus, ICE-GB. For references on ICE generally, see Greenbaum 1996; for ICE-GB, see especially Nelson, Wallis and Aarts 2002; and for ICE-Ireland, see papers such as Kirk, Kallen, Lowry & Rooney (2003), Kirk & Kallen (2005), and Kallen & Kirk (2007). Our first approach will be to look for signs of overt Celticity in those grammatical features of Irish English which have been put forward as evidence of Celtic transfer (or of the reinforcement between Celtic and non-Celtic historical sources); our second approach will be to look at non-grammatical ways in which texts in ICEIreland become indexical of Celticity by less structural means such as loanwords, code-switching, and covert reference using ‘standard’ English in ways that are specific to Irish usage. We argue that, at least within the standard language as we have observed it, Celticity is at once less obvious than a reading of the dialectal literature might suggest and, at the same time, more pervasive than a purely grammatical approach would imply.
Extract: [...]The New English Dictionary, later to become the Oxford English Dictionary, was first published between 1884 and 1928. To add new material, two supplements were issued after this, the first in 1933, and another, more extensive one between 1972 and 1986. In 1989, the Oxford English Dictionary, second edition (OED2) was published, which integrated the material from the original dictionary and the supplements into a single alphabetical sequence. However, virtually all material contained in this edition still remained in the form in which it was originally published. This is the edition most commonly used today, as it forms the basis of the Oxford English Dictionary Online and is also still being sold in print and on CD-ROM. In 1991, a new project started to revise the entire dictionary and bring its entries up to date, both in terms of English usage and in terms of associated scholarship, such as encyclopaedic information and etymologies. The scope was also widened, placing a greater emphasis on English spoken outside Britain. The revision of the dictionary began with the letter M, and the first updated entries were published online in March 2000 (OED3). Quarterly publication of further material has extended the range of revised entries as far as PROTEOSE n. (June 2007). New words from all parts of the alphabet have been published alongside the regular revision.[...]
Extract: [...]Intriguing as they undoubtedly are, the early sixteenth-century lists of books in the Earl of Kildare’s library may well have inadvertently helped to lull scholars into visualising a rather idealised picture of language balance in multilingual late medieval Ireland. The lists reflect a society in which the four languages, Irish, English, Latin and French, vied as scholarly media and where the outcome in the Earl’s library was a four-way photo-finish. The number of volumes in each of the languages was recorded as follows: Latin, 34; French, 35; English, 22; Irish, 20 (Mac Niocaill 1992: 312-314). But of course the multilingual contact situation in Ireland had always been quite dynamic, both at vernacular and at scholarly levels, following the Anglo-Norman invasion of 1169. Although French continued to be employed in official documents into the second half of the 15th century, it had already ceded its vernacular role to English in the towns of the colonists prior to the drawing up of the Statutes of Kilkenny in 1366. These Statutes, composed in Norman-French, the primary language of English law at the time, provide an earlier snapshot of the language situation within the areas under English jurisdiction, as they sought to compel the colonists to desist from adopting Irish as a community vernacular. Ironically, no mention is made of Norman-French in the Statutes themselves. It is clear that what was at issue was a contest for supremacy between Irish and English as the principal vernacular among the colonists.[...]
Extract: [...]In the first part of this paper I trace the language shift from Breton to French within the historical, social and ideological framework in which it occurred. I then argue that 19th and 20th-century attempts by scholars and militants to rehabilitate the Breton language led to the creation of a unified standard (peurunvan).2 The consequence has been the rise of a three-way diglossic rapport between the speakers of French, the new Breton standard3 and those of the traditional Breton vernaculars. Taking the varieties of southern Cornouaille (Finistère) between Quimper and Quimperlé as a point of comparison,4 I focus on a number of phonological, morphological, syntactical and lexical features which, though far from exhausttive, are not generally taken into account in the new standard language. These details provide a general idea of how varieties of Breton function at the micro-dialectological level, as well as ways in which they can differ from the standard and other spoken varieties. The paper concludes with observations regarding the necessity to consider languages, language varieties and their speakers within relevant social contexts.[...]
Extract: [...] One of the often noted characteristic features of the Celtic languages is the absence of a singular verbal form with the meaning ‘to have’.1 The principal way of expressing possession is through periphrastic constructions with prepositions (such as Irish ag, Scottish Gaelic aig ‘at’; Welsh gan, Breton gant ‘at, with’) and appropriate forms of the substantive verb. Pronominal prepositions, another distinctive feature of the Celtic languages, consist of a preposition and a suffixed pronoun, or rather a pronominal personal ending. This construction may be analyzed as an instance of category fusion. Thus, the Irish and Welsh equivalents of English ‘I have money’ are Tá airgead agam or Mae arian gen i, respectively, both literally meaning ‘is money at-me/with-me’. This note discusses pronominal possessive constructions in Celtic languages (and some comparable examples from Celtic Englishes) and provides some background information on pronominal prepositions and comments on historical developments of these forms. It also discusses some terminological issues involved in labelling the construction in question. [...]
Extract: That the Celtic languages were of the Indo-European family was first recognised by Rasmus Christian Rask (*1787), a young Danish linguist, in 1818. However, the fact that he wrote in Danish meant that his discovery was not noted by the linguistic establishment until long after his untimely death in 1832. The same conclusion was arrived at independently of Rask and, apparently, of each other, by Adolphe Pictet (1836) and Franz Bopp (1837). This agreement between the foremost scholars made possible the completion of the picture of the spread of the Indo-European languages in the extreme west of the European continent. However, in the Middle Ages the speakers of Irish had no awareness of any special relationship between Irish and the other Celtic languages, and a scholar as linguistically competent as Cormac mac Cuillennáin (†908), or whoever compiled Sanas Chormaic, treated Welsh on the same basis as Greek, Latin, and the lingua northmannorum in the elucidation of the meaning and history of Irish words. [...]
Contents: The Sociolinguistic Conditions favourable to spread of Structural Features Contact-induced Changes in Insular Celtic Phonological Changes The Lenition of Voiceless Stops Raising / i-Affection Lowering / a-Affection Apocope Syncope Morphological The Loss of Case Inflection of Personal Pronouns The Creation of the Equative Degree The Creation of the Imperfect Tense The Creation of the Conditional Mood Morphosyntactic and Syntactic The Creation of Preposed Definite Articles
Extract: [...]The Roman conquest of what was to become the province of Gallia Narbonensis in the second and then of the whole of Transalpine Gaul in the first century B.C. led to the incorporation into the Roman empire of a large part of the territory in which Gaulish was then spoken.1 In consequence, the vernacular rapidly lost its footing at least in public life and was soon replaced by Latin, the language of the new masters, which enjoyed higher prestige (cf. e.g. Meid 1980: 7-8). On the other hand, Gaulish continued to be written for some three centuries and was probably used in speech even longer, especially in rural areas. We must therefore posit a prolonged period of bilingualism. The effects of this situation on the Latin spoken in the provinces of Gaul seem to have been rather limited. A number of lexical items, mostly from the field of everyday life, and some phonetic characteristics are the sole testimonies of a Gaulish substratum in the variety of Latin that was later to develop into the Romance dialects of France (cf. Meid 1980: 38, fn. 77). [...]
Celtic and Afro-Asiatic
(2007)
Extract: [...]It is not remarkable that structural similarities between the Insular Celtic and some Afro-Asiatic1 languages continue to exert a fascination on many people. Research into any language may be enlightening with regard to the understanding of all languages, and languages that show similar features are particularly likely to provide useful information. It is remarkable that the structural similarities between Insular Celtic and Afro-Asiatic languages continue to be interpreted as diagnostic of some sort of special relationship between them; some sort of affinity or mutual affiliation that goes beyond the fact that they are two groups of human languages. This paper investigates again the fallacious nature of the arguments for the Afro-Asiatic/Insular Celtic contact theory (henceforth AA/IC contact theory). It takes its point of departure from Gensler (1993). That work is as yet unpublished, but has had considerable resonance. Such statements as the following indicate the importance that has been attached to the work: “After the studies of Morris-Jones, Pokorny, Wagner2 and Gensler it seems impossible to deny the special links between Insular Celtic and Afro-Asiatic” (Jongeling 2000:64). And the ideas in question have been propagated in the popular scientific press,3 with the usual corollary that it is these ideas that are perceived by the interested but non-specialist public as being at the cutting edge of sound new research, when in fact they may simply be recycled ideas of a discredited theory. For these reasons it is appropriate to subject Gensler’s unpublished work to detailed critique.4 In particular, with regard to the twenty features of affinity between Insular Celtic and Afro-Asiatic which Gensler investigated, it will be shown (yet again, in some cases): [...]
Extract: [...]In Celtic languages (both Continental and Insular) we can find words with uncertain etymology which presumably represent loanwords from other language-families. One can see the traces of the pre-Indo-European substratum of Central and Western Europe, “an original non-Celtic/non-Germanic North West block” according to Kuhn (1961). But we may suppose that this conclusion is not sufficiently justified. This problem can have many different solutions, and we may never be in a position to resolve it definitively.[...]
Small livestock is an important resource for rural human populations in dry climates. How strongly will climate change affect the capacity of the rangeland? We used hierarchical modelling to scale quantitatively the growth of shrubs and annual plants, the main food of sheep and goats, to the landscape extent in the eastern Mediterranean region. Without grazing, productivity increased in a sigmoid way with mean annual precipitation. Grazing reduced productivity more strongly the drier the landscape. At a point just under the stocking capacity of the vegetation, productivity declined precipitously with more intense grazing due to a lack of seed production of annuals. We repeated simulations with precipitation patterns projected by two contrasting IPCC scenarios. Compared to results based on historic patterns, productivity and stocking capacity did not differ in most cases. Thus, grazing intensity remains the stronger impact on landscape productivity in this dry region even in the future.
Excerpt: The shrill sounds of the now seemingly outdated controversy between Gershom Scholem and Martin Buber at the beginning of the sixties are still in the minds of every student of Hasidic literature and thought. - The "Scholem-community" feels content and the "Buber-community" upset. We can summarize the case in a few words. Martin Buber, the pioneer of Hasidism in the Western World, held the position that whoever would want to understand Hasidism had to turn to Hasidic tale as here, in the tales of the Hasidim, real Hasidic life was to be found. Whereas in the Hasidic homilies we meet mere non-creative tradition especially in the form of Kabbalah. Buber did not totally deny the importance of the Hasidic Midrash but he regarded it just as a commentary, i.e. as secondhand material, whereas, in his view, the tale was a true mirror of real Hasidic life [...]
A multitype Dawson-Watanabe process is conditioned, in subcritical and critical cases, on non-extinction in the remote future. On every finite time interval, its distribution is absolutely continuous with respect to the law of the unconditioned process. A martingale problem characterization is also given. Several results on the long time behavior of the conditioned mass process - the conditioned multitype Feller branching diffusion - are then proved. The general case is first considered, where the mutation matrix which models the interaction between the types, is irreducible. Several two-type models with decomposable mutation matrices are analyzed too .
Excerpt: Hasidic Ashkenazi literature is known to scholars of Jewish religion as one of the most prolific sources of medieval Jewish magic or magical beliefs. This is all the more astonishing as the non esoteric writings of the Hasidey Ashkenaz represent a rather traditional Jewish piety as known to us from talmudic sources. Considering this duality of an almost traditional Jewish piety on the one hand and very distinct magic tenets on the other, we may ask whether the Hasidey Ashkenaz themselves perceived any difference between magic and religion. There are indeed a number of modern historians of religion who completely deny the validity of such a distinction, for in most historical religions magic and religion are in fact intertwined to a certain degree, thus permitting almost no differentiation between the two.
Excerpt: The writings from the thirteenth century called by Gershom Scholem the "Writings of the 'lyyun circle" are one of the most intriguing chapters of early kabbalah - this I need not to elaborate on as it is a well known fact to anyone whoever had read these texts or the literature about them. When reading these texts, one gets the impression as if the authors had at hand a box full of terms and phrases into which everybody could just stick his hand and take terms and phrases out of it in order to arrange them according to his own taste, disregarding the meaning they have in the writings of his fellow kabbalists. The result was, that we now have before us a large number of varying mosaic pictures in which we detect again and again the same mosaic pebbles, however composed differently.
Rapid and robust characterization of large earthquakes in terms of their spatial extent and temporal duration is of high importance for disaster mitigation and early warning applications. Backtracking of seismic P-waves was successfully used by several authors to image the rupture process of the great Sumatra earthquake (26.12.2004) using short period and broadband arrays. We follow here an approach of Walker et al. to backtrack and stack broadband waveforms from global network stations using traveltimes for a global Earth model to obtain the overall spatio-temporal development of the energy radiation of large earthquakes in a quick and robust way. We present results for selected events with well studied source processes (Kokoxili 14.11.2001, Tokachi-Oki 25.09.2003, Nias 28.03.2005). Further, we apply the technique in a semi-real time fashion to broadband data of earthquakes with a broadband magnitude >= 7 (roughly corresponding to Mw 6.5). Processing is based on first automatic detection messages from the GEOFON extended virtual network (GEVN).
We use seismic array methods (semblance analysis) to image areas of seismic energy release in the Sunda Arc region and world-wide. Broadband seismograms at teleseismic distances (30° ≤ Δ ≤ 100°) are compared at several subarrays. Semblance maps of different subarrays are multiplied. High semblance tracked over long time (10s of second to minutes) and long distances indicate locations of earthquakes. The method allows resolution of rupture characteristics important for tsunami early warning: start and duration, velocity and direction, length and area. The method has been successfully applied to recent and historic events (M>6.5) and is now operational in real time. Results are obtained shortly after source time, see http://www.geo.uni-potsdam.de/Forschung/Geophysik/GITEWS/tsunami.htm). Comparison of manual and automatic processing are in good agreement. Computational effort is small. Automatic results may be obtained within 15 - 20 minutes after event occurrence.
Team diversity
(2007)
Team diversity refers to the differences between team members on any attribute that may lead each single member of the group to perceive any other member of the group as being different from the self of this particular member. These attributes and perceptions refer to all dimensions people can differ on, such as age, gender, ethnicity, religious and functional background, personality, skills, abilities, beliefs, and attitudes.
Receiver functions are a good tool to investigate the seismotectonic structure beneath the a seismic station. In this study we apply the method to stations situated on or near Sumatra to find constraints on a more detailed velocity model which should improve earthquake localisation. We estimate shallow Moho-depths (~ 21 km) close to the trench and depths of ~30 km at greater distances. First evidences for the dip direction of the slab of ~60° are provided. Receiver functions were calculated for 20 stations for altogether 110 earthquakes in the distance range between 30° and 95° from the receiver. However the number of receiver functions per station is strongly variable as it depends on the installation date, the signal-to-noise-ratio of the station and the reliability of the acquisition.
The authors used the frameworks of reciprocal determinism and occupational socialization to study the effects of work characteristics (consisting of control and complexity of work) on personal initiative (PI)--mediated by control orientation (a 2nd-order factor consisting of control aspiration, perceived opportunity for control, and self-efficacy) and the reciprocal effects of PI on changes in work characteristics. They applied structural equation modeling to a longitudinal study with 4 measurement waves (N = 268) in a transitional economy: East Germany. Results confirm the model plus 1 additional, nonhypothesized effect. Work characteristics had a synchronous effect on PI via control orientation (full mediation). There were also effects of control orientation and of PI on later changes in work characteristics: As predicted, PI functioned as partial mediator, changing work characteristics in the long term (reciprocal effect); unexpectedly, there was a 2nd reciprocal effect of an additional lagged partial mediation of control orientation on later work characteristics.
Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are also considered as candidate sites for non-thermal high-energy photon production up to gamma-ray energies. The present work considers the effects of wind clumpiness expected on the emitting relativistic particle spectrum in colliding wind systems, built up from the pool of thermal wind particles through diffusive particle acceleration, and taking into account inverse Compton and synchrotron losses. In comparison to a homogeneous wind, a clumpy wind causes flux variations of the emitting particle spectrum when the clump enters the wind collision region. It is found that the spectral features associated with this variability moves temporally from low to high energy bands with the time shift between any two spectral bands being dependent on clump size, filling factor, and the energy-dependence of particle energy gains and losses.
The most massive stars are those with the shortest but most active life. One group of massive stars, the Luminous Blue Variables (LBVs), of which only a few objects are known, are in particular of interest concerning the stability of stars. They have a high mass loss rate and are close to being instable. This is even more likely as rotation becomes an important factor in stellar evolution of these stars. Through massive stellar winds and sometimes giant eruptions, LBV nebulae are formed. Various aspects in the evolution in the LBV phase lead, beside the large scale morphological and kinematical differences, to a diversity of small structures like clumps, rims, and outflows in these nebulae.
Gamma-rays can be produced by the interaction of a relativistic jet and the matter of the stellar wind in the subclass of massive X-ray binaries known as “microquasars”. The relativistic jet is ejected from the surroundings of the compact object and interacts with cold protons from the stellar wind, producing pions that then quickly decay into gamma-rays. Since the resulting gamma-ray emissivity depends on the target density, the detection of rapid variability in microquasars with GLAST and the new generation of Cherenkov imaging arrays could be used to probe the clumped structure of the stellar wind. In particular, we show here that the relative fluctuation in gamma rays may scale with the square root of the ratio of porosity length to binary separation, $\sqrt{h/a}$, implying for example a ca. 10% variation in gamma ray emission for a quite moderate porosity, h/a ∼ 0.01.
The optical spectrum of Eta Carinae (η Car) is prominent in H I, He i and Fe ii wind lines, all of which vary both in absorption and emission with phase. The phase dependance is a consequence of the interaction between the two objects in the η Car binary (η Car A & B). The binary system is enshrouded by ejecta from previous mass ejection events and consequently, η Car B is not directly observable. We have traced the He i lines over η Car’s spectroscopic period, using HST/STIS data obtained with medium spectral, but high angular, resolving power, and created a radial velocity curve for the system. The He I lines are formed in the core of the system, and appear to be a composite of multiple features formed in spatially separated regions. The sources of their irregular line profiles are still not fully understood, but can be attributed to emission/absorption near the wind-wind interface and/or a direct consequence of the η Car A’s, massive, clumpy wind. This paper will discuss the spectral variability, the narrow emission structure of the He i lines and how clumpiness of the winds may impede the construction of the reliable radial velocity curve, necessary for characterizations of especially η Car B.
The spatially-resolved winds of the massive binary, Eta Carinae, extend an arcsecond on the sky, well beyond the 10 to 20 milliarcsecond binary orbital dimension. Stellar wind line profiles, observed at very different angular resolutions of VLTI/AMBER, HST/STIS and VLT/UVES, provide spatial information on the extended wind interaction structure as it changes with orbital phase. These same wind lines, observable in the starlight scattered off the foreground lobe of the dusty Homunculus, provide time-variant line profiles viewed from significantly different angles. Comparisons of direct and scattered wind profiles observed in the same epoch and at different orbital phases provide insight on the extended wind structure and promise the potential for three-dimensional imaging of the outer wind structures. Massive, long-lasting clumps, including the nebularWeigelt blobs, originated during the two historical ejection events. Wind interactions with these clumps are quite noticeable in spatially-resolved spectroscopy. As the 2009.0 minimum approaches, analysis of existing spectra and 3-D modeling are providing bases for key observations to gain further understanding of this complex massive binary.
The H.E.S.S. collaboration recently reported the discovery of VHE γ-ray emission coincident with the young stellar cluster Westerlund 2. This system is known to host a population of hot, massive stars, and, most particularly, the WR binary WR 20a. Particle acceleration to TeV energies in Westerlund 2 can be accomplished in several alternative scenarios, therefore we only discuss energetic constraints based on the total available kinetic energy in the system, the actual mass loss rates of respective cluster members, and implied gamma-ray production from processes such as inverse Compton scattering or neutral pion decay. From the inferred gammaray luminosity of the order of 1035erg/s, implications for the efficiency of converting available kinetic energy into non-thermal radiation associated with stellar winds in the Westerlund 2 cluster are discussed under consideration of either the presence or absence of wind clumping.
We model the line profile variability (lpv) in spectra of clumped stellar atmospheres using the Stochastic Clump Model (SCM) of the winds of early-type stars. In this model the formation of dense inhomogeneities (clumps) in the line driven winds is considered as being a stochastic process. It is supposed that the emission due to clumps mainly contributes to the intensities of emission lines in the stellar spectra. It is shown that in the framework of the SCM it is possible to reproduce both the mean line profiles and a common pattern of the lpv.
We study the time variability of emission lines in three WNE stars : WR 2 (WN2), WR 3 (WN3ha) and WR152 (WN3). While WR 2 shows no variability above the noise level, the other stars do show variation, which are like other WR stars in WR 152 but very fast in WR 3. From these motions, we deduce a value of β ∼1 for WR 3 that is like that seen in O stars and β ∼2–3 for WR 152, that is intermediate between other WR stars and WR 3.
Luminous Blue Variables show strong changes in their stellar wind on time scales of typically years to decades when they expand and contract radially at approximately constant luminosity. Micro-variability on shorter time scales and amplitudes can be observed superimposed to the larger scale radial changes. I will show long-term time series of high resolution spectra which we have collected in the past 20 years for many of the well known LBVs together with a few time series of weekly sampling (HR Car, R40, R71, R110, R127, S Dor) covering a time windows of up to a few months. Wind variability is seen on short and intermediate time scales with the line profiles changing from P Cygni to inverse P Cygni and double peeked profiles sometimes for the same star and spectral line. On longer time scales the ionisation levels for all chemical elements change drastically due to the strong change of the temperature on the stellar surface. While on the long term the characteristic radial changes may have impact on the over all mass loss rates, the variabilities and asymmetries on short and intermediate time scales may cause false estimates of the mass loss rates when confronting models with the observed line profiles
Hα observations of Rigel obtained on 184 nights during the past ten years with the 1-m telescope and ´echelle spectrograph of Ritter Observatory are surveyed. The line profiles were classified in terms of morphology. About 1/4 of them are of P Cygni type, about 15% inverse P Cygni, about 25% double-peaked, about 1/3 pure absorption, and a few are single emission lines. Transformation of the profile from one type to another typically takes a few days. Although the line stays in absorption for extended intervals, only one high-velocity absorption event of the intensity reported by Kaufer et al. (1996a) was observed, in late 2006. Late in this event, Hα absorption occurred farther to the red than the red wing of a plausible photospheric absorption component, an indication of infalling material. In general, as the absorption events come to an end, the emission typically returns with an inverse P Cygni profile. The Hα profile class shows no obvious correlation with the radial velocity of C II λ6578, a photospheric absorption line.
X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from He-like ions in the X-ray spectra of O-stars highlighted problems with this general paradigm: the measured line ratios of highest ions are consistent with the location of the hottest X-ray emitting plasma very close to the base of the wind, perhaps indicating the presence of a corona, while measurements from lower ions conform with the wind-embedded shock model. Generally, to correctly model the emerging Xray spectra, a detailed knowledge of the cool wind opacities based on stellar atmosphere models is prerequisite. A nearly grey stellar wind opacity for the X-rays is deduced from the analyses of high-resolution X-ray spectra. This indicates that the stellar winds are strongly clumped. Furthermore, the nearly symmetric shape of X-ray emission line profiles can be explained if the wind clumps are radially compressed. In massive binaries the orbital variations of X-ray emission allow to probe the opacity of the stellar wind; results support the picture of strong wind clumping. In high-mass X-ray binaries, the stochastic X-ray variability and the extend of the stellar-wind part photoionized by X-rays provide further strong evidence that stellar winds consist of dense clumps.
By quantitatively fitting simple emission line profile models that include both atomic opacity and porosity to the Chandra X-ray spectrum of ζ Pup, we are able to explore the trade-offs between reduced mass-loss rates and wind porosity. We find that reducing the mass-loss rate of ζ Pup by roughly a factor of four, to 1.5 × 10−6 M⊙ yr−1, enables simple non-porous wind models to provide good fits to the data. If, on the other hand, we take the literature mass-loss rate of 6×10−6 M⊙ yr−1, then to produce X-ray line profiles that fit the data, extreme porosity lengths – of h∞ ≈ 3 R∗ – are required. Moreover, these porous models do not provide better fits to the data than the non-porous, low optical depth models. Additionally, such huge porosity lengths do not seem realistic in light of 2-D numerical simulations of the wind instability.