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Renewed interest in fiscal policy has increased the use of quantitative models to evaluate policy. Because of modeling uncertainty, it is essential that policy evaluations be robust to alternative assumptions. We find that models currently being used in practice to evaluate fiscal policy stimulus proposals are not robust. Government spending multipliers in an alternative empirically-estimated and widely-cited new Keynesian model are much smaller than in these old Keynesian models; the estimated stimulus is extremely small with GDP and employment effects only one-sixth as large.
We examined the neural signatures of stimulus features in visual working memory (WM) by integrating functional magnetic resonance imaging (fMRI) and event-related potential data recorded during mental manipulation of colors, rotation angles, and color–angle conjunctions. The N200, negative slow wave, and P3b were modulated by the information content of WM, and an fMRI-constrained source model revealed a progression in neural activity from posterior visual areas to higher order areas in the ventral and dorsal processing streams. Color processing was associated with activity in inferior frontal gyrus during encoding and retrieval, whereas angle processing involved right parietal regions during the delay interval. WM for color–angle conjunctions did not involve any additional neural processes. The finding that different patterns of brain activity underlie WM for color and spatial information is consistent with ideas that the ventral/dorsal “what/where” segregation of perceptual processing influences WM organization. The absence of characteristic signatures of conjunction-related brain activity, which was generally intermediate between the 2 single conditions, suggests that conjunction judgments are based on the coordinated activity of these 2 streams. Keywords: EEG, fMRI, source analysis, visual, working memory
We show that loanword adaptation can be understood entirely in terms of phonological and phonetic comprehension and production mechanisms in the first language. We provide explicit accounts of several loanword adaptation phenomena (in Korean) in terms of an Optimality-Theoretic grammar model with the same three levels of representation that are needed to describe L1 phonology: the underlying form, the phonological surface form, and the auditory-phonetic form. The model is bidirectional, i.e., the same constraints and rankings are used by the listener and by the speaker. These constraints and rankings are the same for L1 processing and loanword adaptation.
Experimental data shows that adult learners of an artificial language with a phonotactic restriction learned this restriction better when being trained on word types (e.g. when they were presented with 80 different words twice each) than when being trained on word tokens (e.g. when presented with 40 different words four times each) (Hamann & Ernestus submitted). These findings support Pierrehumbert’s (2003) observation that phonotactic co-occurrence restrictions are formed across lexical entries, since only lexical levels of representation can be sensitive to type frequencies.
The present study argues that variation across listeners in the perception of a non-native contrast is due to two factors: the listener-specic weighting of auditory dimensions and the listener-specic construction of new segmental representations. The interaction of both factors is shown to take place in the perception grammar, which can be modelled within an OT framework. These points are illustrated with the acquisition of the Dutch three-member labiodental contrast [V v f] by German learners of Dutch, focussing on four types of learners from the perception study by Hamann and Sennema (2005a).
The multiplicity fluctuations in A+A collisions at SPS and RHIC energies are studied within the HSD transport approach. We find a dominant role of the fluctuations in the nucleon participant number for the final fluctuations. In order to extract physical fluctuations one should decrease the fluctuations in the participants number. This can be done considering very central collisions. The system size dependence of the multiplicity fluctuations in central A+A collisions at the SPS energy range – obtained in the HSD and UrQMD transport models – is presented. The results can be used as a ‘background’ for experimental measurements of fluctuations as a signal of the critical point. Event-by-event fluctuations of the K/p , K/p and p/p ratios in A+A collisions are also studied. Event-by-event fluctuations of the kaon to pion number ratio in nucleus-nucleus collisions are studied for SPS and RHIC energies. We find that the HSD model can qualitatively reproduce the measured excitation function for the K/p ratio fluctuations in central Au+Au (or Pb+Pb) collisions from low SPS up to top RHIC energies. The forward-backward correlation coefficient measured by the STAR Collaboration in Au+Au collisions at RHIC is also studied. We discuss the effects of initial collision geometry and centrality bin definition on correlations in nucleus-nucleus collisions. We argue that a study of the dependence of correlations on the centrality bin definition as well as the bin size may distinguish between these ‘trivial’ correlations and correlations arising from ‘new physics’. 5th International Workshop on Critical Point and Onset of Deconfinement - CPOD 2009, June 08 - 12 2009 Brookhaven National Laboratory, Long Island, New York, USA
This paper analyzes the risk properties of typical asset-backed securities (ABS), like CDOs or MBS, relying on a model with both macroeconomic and idiosyncratic components. The examined properties include expected loss, loss given default, and macro factor dependencies. Using a two-dimensional loss decomposition as a new metric, the risk properties of individual ABS tranches can directly be compared to those of corporate bonds, within and across rating classes. By applying Monte Carlo Simulation, we find that the risk properties of ABS differ significantly and systematically from those of straight bonds with the same rating. In particular, loss given default, the sensitivities to macroeconomic risk, and model risk differ greatly between instruments. Our findings have implications for understanding the credit crisis and for policy making. On an economic level, our analysis suggests a new explanation for the observed rating inflation in structured finance markets during the pre-crisis period 2004-2007. On a policy level, our findings call for a termination of the 'one-size-fits-all' approach to the rating methodology for fixed income instruments, requiring an own rating methodology for structured finance instruments. JEL Classification: G21, G28 Keywords: credit risk, risk transfer, systematic risk
The genus Haroldiataenius Chalumeau, 1981 (Aphodiinae: Eupariini) from southern United States, Mexico, and Central America is revised and nine species are recognized. The subgeneric name Sayloria Chalumeau, 1981 is synonymized with Haroldiataenius (sensu stricto) and Ataenius sabinoi Cartwright, 1974 is synonymized with A. lucanus Horn, 1871. Five species are transferred to Haroldiataenius from the genus Ataenius Harold creating the following new combinations: H. convexus (Robinson), H. griffini (Cartwright), H. lucanus (Horn), H. saramari (Cartwright), and H. semipilosus (Van Dyke). One new species,Haroldiataenius buvexus is described from Texas, USA. A key to species of Haroldiataenius is included and pertinent morphological details are illustrated.
The New World euparine scarab genera Parataenius Balthasar, 1961 and Pseudataenius Brown, 1927 are revised. Ataenius brunneus Schmidt is transferred to the genus Parataenius becoming Parataenius brunneus (Schmidt), new combination. The monospecific genus Ataenioides Petrovitz, 1973, is synonymized with Pseudataenius Brown, 1927, (new synonymy) and the type species, Ataenioides gracilitarsis Petrovitz, is given the new combination Pseudataenius gracilitarsis (Petrovitz). New species of Parataenius are described from southern South America: Parataenius selvae, P. estero, and P. martinezi. Keys for species of both genera are presented and pertinent morphological details are illustrated.
Interesse für und Liebe zu den Vögeln und vor allem zu den Vogelstimmen entwickelten sich an getrennten Orten: Bei Hans-Heiner Bergmann in Marburg und Osnabrück, bei Hans-Wolfgang Helb in Erlangen und Kaiserslautern. Neue Forschungsmöglichkeiten und moderne Technik wie die Sonagraphie ließen aus den beiden Ornitho-Akustikern ein Kollegen-Team werden. Beide Stimmen-Sammlungen zusammen mündeten in gemeinsamen Publikationen, auch in dem Werk „Die Stimmen der Vögel Europas“.
Epidermal growth factor (EGF) receptor belongs to the broad family of enzymatic receptors called receptor tyrosine kinases (RTKs). Generally, the binding of a ligand to these receptors leads to activation of their intracellular kinase activity that sets in motion a cascade of signaling events. In order to ensure appropriate responses to physiological stimuli, the cell is endowed with the ability to regulate signal transduction via numerous mechanisms such as dephosphorylation of the RTK and its substrates as well as downregulation of the RTK. Activation of EGFR is a potent mitogenic (proliferative) and motogenic (cell motility) signal that plays crucial roles during embryonic development and maintenance of adult tissue. EGFR signaling is primarily regulated by ligand-induced receptor internalization with subsequent degradation in lysosomes. While the complex of proteins that are recruited to EGFR after its activation is well understood, proteins that interact with the receptor in the absence of ligand binding are still not systematically studied. With the goal of identifying novel binding partners of non-activated EGFR, a membrane based yeast-two hybrid screen (MYTH) was conducted. MYTH is based on the principle of in vivo reconstitution of the N-terminus (Nub) and C-terminus (Cub) halves of ubiquitin once brought into close proximity. A chimeric protein consisting of EGFR fused to Cub and a transcription factor was used as a bait to screen Nub-tagged cDNA library. Analysis of resultant yeast transformants revealed a total of 87 proteins to interact with EGFR. Of these only 11 were previously shown to bind to EGFR. A majority of the other proteins were shown to interact with the receptor by yeast retransformation. Fifteen were confirmed to bind to EGFR by coimmunoprecipitation assays in mammalian cells. One of the novel EGFR interactors identified in the screen was histone deacetylase 6 (HDAC6). This deacetylase is localized in the cytoplasm and known to deacetylate alpha-tubulin, HSP90 and cortactin. The juxtamembrane region of EGFR binds to the Cterminus of HDAC6. Functionally, overexpression of wild type HDAC6 stabilized ligand-induced degradation of the receptor. On the other hand, deacetylase deficient or EGFR binding compromised mutants of HDAC6 were able to stabilize EGFR only partially. Downmodulation of HDAC6 expression by RNAi markedly accelerated degradation of the receptor. Taken together, HDAC6 is a negative regulator of EGFR downregulation that is dependent on its deacetylase activity and ability to bind to the receptor. Imaging studies revealed that HDAC6 does not affect internalization of EGFR from the plasma membrane but rather influences the post-endocytic trafficking of the receptor-ligand complex to lysosomes. Pulse-chase experiments using fluorophoretagged EGF showed that EGFR is transported faster towards the peri-nuclear region and delivered to late endosomes rapidly in HDAC6 depleted cells. HDAC6 is demonstrated to act, at least partly, by regulating the acetylation of alpha-tubulin. Upon EGFR activation, acetylation of alpha-tubulin on lysine 40 is progressively increased as shown by mass spectrometry and immunoblotting. Forced expression of a dominant negative mutant of alpha-tubulin, but not wild type alpha-tubulin, led to reduced speed and processive movement of early endosomes in GFP-Rab5 expressing cells. In a surprising twist, EGFR is able to phosphorylate HDAC6 on Tyr570. Phosphorylation of Tyr570 and Ser568 leads to inactivation of the deacetylase function of HDAC6 as shown by in vivo and in vitro assays. In summary, HDAC6 diminishes EGFR downregulation by slowing the transport of intracellular vesicles. The inhibitory effect is removed once HDAC6 is phosphorylated on key residues. In line with these findings, two recent reports have shown that hyper-acetylation of alpha-tubulin induced by inhibition of HDAC6 increases the transport of brain derived neurotrophic factor and JNK interacting protein-1 in different cell systems. Acetylated microtubules are more efficient in recruiting motor proteins like kinesin-1 and dynein. These findings indicate that HDAC6 plays an important regulatory role in intracellular trafficking pathways. However, several outstanding issues still remain unresolved. How does acetylation of microtubules influence vesicular trafficking? In this regard, the temporal and spatial dynamics of alpha-tubulin acetylation following EGFR activation should be studied. Furthermore, whether HDAC6 affects the trafficking of other endocytic cargos and additional organelles is an interesting question to address.
Die vorliegende Arbeit analysierte die Behandlung von Patienten mit Infektionserkrankungen am Zentrum der Zahn-, Mund- und Kieferheilkunde des Klinikums der Johann Wolfgang Goethe-Universität, Frankfurt am Main (Carolinum). Dabei wurde vor allem untersucht, welche Auswirkungen die Reduzierung von Personalressourcen speziell für die Behandlung dieser Patienten ab dem Jahr 2000 hinsichtlich der Betreuung und Versorgung hatte. Die Studie war retrospektiv angelegt und wertete Daten aus den Jahren 1998 bis 2002 aus. Hierfür wurden alle im Archiv lagernden Karteikarten herangezogen und die Daten in eine dafür entwickelte FilemakerPro©-Datenbank übertragen. Im Untersuchungszeitraum nahmen 940 Patienten mit Infektionskrankheiten etwa 3700 Besuche wahr. Regelmäßig erschienen 25% der Patienten, auf sie entfielen 60% aller Besuche. Diese Gruppe wurde einer näheren Betrachtung unterzogen: Die Auswertung der erhobenen Daten zeigte, dass das Ziel der Absenkung der Patientenzahlen und die Anzahl der Behandlungstermine erreicht werden konnte, die systematische Betreuung der Patienten sich jedoch verschlechterte. Der Anteil der sanierten Patienten sank von 34% auf 18% ab, die Zahl der unsystematisch behandelten Patienten verdreifachte sich dagegen von 1999 auf 2000 und blieb bei diesem hohen Wert. Vorsorgebehandlungen nahmen maximal ein fünftel aller Behandlungen ein, mit abnehmender Systematik sank dieser Anteil gegen null. Begünstigender Faktor für eine Sanierung waren ein erstelltes OPG (ersatzweise ein Zahnfilmstatus) und die Erstellung einer Behandlungsplanung. Das Vorhandensein eines OPGs erhöhte aber nicht die Wahrscheinlichkeit für eine folgende Behandlungsplanung. Patienten die an das Carolinum von außerhalb überwiesen wurden, hatten eine größere Chance auf eine Sanierung. Letztlich wurden nur 4% aller regelmäßig erschienenen Patienten systematisch mit Recall betreut, zahnärztlich saniert wurden insgesamt jedoch 30% der behandelten Patienten. Entgegen allgemeiner Annahmen waren kurzfristig abgesagte oder nicht eingehaltene Termine die Ausnahme.
The selection of features for classification, clustering and approximation is an important task in pattern recognition, data mining and soft computing. For real-valued features, this contribution shows how feature selection for a high number of features can be implemented using mutual in-formation. Especially, the common problem for mutual information computation of computing joint probabilities for many dimensions using only a few samples is treated by using the Rènyi mutual information of order two as computational base. For this, the Grassberger-Takens corre-lation integral is used which was developed for estimating probability densities in chaos theory. Additionally, an adaptive procedure for computing the hypercube size is introduced and for real world applications, the treatment of missing values is included. The computation procedure is accelerated by exploiting the ranking of the set of real feature values especially for the example of time series. As example, a small blackbox-glassbox example shows how the relevant features and their time lags are determined in the time series even if the input feature time series determine nonlinearly the output. A more realistic example from chemical industry shows that this enables a better ap-proximation of the input-output mapping than the best neural network approach developed for an international contest. By the computationally efficient implementation, mutual information becomes an attractive tool for feature selection even for a high number of real-valued features.
Die Landschaft der Zeichen : eine semiotische Analyse von W. G. Sebalds "Die Ringe des Saturn"
(2009)
W. G. Sebald's "The Rings of Saturn" resists genre classification: Neither novel nor mere travel literature, it combines report with fiction, historical anecdotes with melancholy musings, explanations of economic and political facts with accounts of personal anxieties. This vast material, however, is joined by a semiotic regard, a way of looking at the world attentive on signs and their use. Hence, some of the far-ranging narratives, observations and reflections, often barely connected by associations of the narrator, can be systematically linked by a semiotic methodology. In this article, semiotic categories like index, icon and symbol, encoding, decoding and recoding, change of meaning and pattern recognition are applied to different levels of the text. The semiotic approach thus integrates the disparate episodes in "The Rings of Saturn", revealing them as being linked by their interest in signs and signification. In this way, semiotics proves itself as a method for literary studies.
In this thesis we have studied the physics of different ultracold Bose-Fermi mixtures in optical lattices, as well as spin 1=2 fermions in a harmonic trap. To study these systems we generalized dynamical mean-field theory for a mixture of fermions and bosons, as well as for an inhomogeneous environment. Generalized dynamical mean-field theory (GDMFT) is a method that describes a mixture of fermions and bosons. This method consists of Gutzwiller mean-field for the bosons, and dynamical mean-field theory for the fermions, which are coupled on-site by the Bose-Fermi density-density interaction and possibly a Feshbach term which converts a pair of up and down fermions into a molecule, i.e. a boson. We derived the self-consistency equations and showed that this method is well-controlled in the limit of high lattice coordination number z. We develop real-space dynamical mean-field theory for studying systems in an inhomogeneous environment, e.g. in a harmonic trap. The crucial difference compared to standard DMFT is that we are taking into account that different sites are not equivalent to each other and thus take into account the inhomogeneity of the system. Different sites are coupled by the real-space Dyson equation. ...
Dieser Beitrag befasst sich erstmals mit Fugenelementen in Lehnwortbildungen, genauer: in N+N-Komposita mit fremdem Bestimmungswort (auch Determinations- oder Erstglied). Da Fugenelemente morphologisch zum Bestimmungs- und nicht zum Grundwort gehören, spielt das Grundwort keine Rolle bei der Entscheidung, ob die Kompositionsnahtstelle verfugt wird oder nicht […]. […] Dabei fällt auf – und hierauf spielt der Zweifelsfall Subjekt(+s+)pronomen im Titel an –, dass es zahlreiche Schwankungen gibt […]. Schwankungsfälle erfordern u. E. besondere Aufmerksamkeit, weil sie in der Regel Sprachwandel im Vollzug darstellen, d. h. den Übergang eines älteren zu einem jüngeren Sprachzustand markieren. […] Was die Fremdwortkomposita so interessant macht, ist die Tatsache, dass nichtnatives Material einem sehr nativen Verfahren […] unterzogen wird […]. In diesem Beitrag gehen wir wie folgt vor: Zunächst – in Kapitel 2 – definieren wir das Fugenelement und stellen kurz seine Entstehung, sein Inventar von immerhin sechs Allo-Formen und deren Distribution dar. In Kapitel 3 fragen wir nach der bzw. den Funktionen von Fugenelementen, die in der bisherigen Forschung vorgebracht wurden. […]. Kapitel 4 befasst sich speziell mit dem Fugenverhalten in Fremdwortkomposita, genauer: in Komposita mit nichtnativem Erstglied. Hier zeigen wir, dass es in erster Linie die phonologische Wortstruktur des Erstglieds ist, die die s-Fugensetzung steuert.