Closed Strings in Misner Space: Stringy Fuzziness with a Twist

Misner space, also known as the Lorentzian orbifold $R^{1,1}/boost$, is the simplest tree-level solution of string theory with a cosmological singularity. We compute tree-level scattering amplitudes involving twisted states, using operator and current algebra techniques. We find that, due to zero-point quantum fluctuations of the excited modes, twisted strings with a large winding number $w$ are fuzzy on a scale $\sqrt{\log w}$, which can be much larger than the string scale. Wave functions are smeared by an operator $\exp(\Delta(\nu) \partial_+ \partial_-)$ reminiscent of the Moyal-product of non-commutative geometry, which, since $\Delta(\nu)$ is real, modulates the amplitude rather than the phase of the wave function, and is purely gravitational in its origin. We compute the scattering amplitude of two twisted states and one tachyon or graviton, and find a finite result. The scattering amplitude of two twisted and two untwisted states is found to diverge, due to the propagation of intermediate winding strings with vanishing boost momentum. The scattering amplitude of three twisted fields is computed by analytic continuation from three-point amplitudes of states with non-zero $p^+$ in the Nappi-Witten plane wave, and the non-locality of the three-point vertex is found to diverge for certain kinematical configurations. Our results for the three-point amplitudes allow in principle to compute, to leading order, the back-reaction on the metric due to a condensation of coherent winding strings.Comment: 29 pages, Latex2e, uses JHEP3.cls; v3: minor corrections, final version to appear in JCA

Lyman alpha SMM/UVSP absolute calibration and geocoronal correction

Lyman alpha observations from the Ultraviolet Spectrometer Polarimeter (UVSP) instrument of the Solar Maximum Mission (SMM) spacecraft were analyzed and provide instrumental calibration details. Specific values of the instrument quantum efficiency, Lyman alpha absolute intensity, and correction for geocoronal absorption are presented

Stavrogin’s Crime and Punishment Revisited: Dostoevskian Intertexts in J.M. Coetzee’s Disgrace (1999)

F.M. Dostoevsky has often been acknowledged as one of the major influences on contemporary South African-born novelist J.M. Coetzee. Nevertheless, his 1999 Booker Prize-winning Disgrace has not been given a reading in consistently Dostoevskian terms. Therefore, the present paper focuses on the implicit intertextual links connecting Disgrace to Devils (1872) and Crime and Punishment (1866). I will argue that Coetzee’s central character, David Lurie is a present-day rewriting of both Dostoevskian Stavrogin and Raskolnikov. As to the first of these, I read Lurie’s engagement with the Romantic figure of Byron as a critique of the Romantic aspects of Stavrogin’s character in Devils. Second, I will argue that while Lurie and his crime largely evoke Stavrogin, his fate is also a ‘corrective’ rewriting of Raskolnikov’s: apart from the obvious thematic similarities, Coetzee’s novel is also clearly reminiscent of both Dostoevskian characters’ respective narratives in its central scenes of confession. Coetzee, however, seems to most ambiguously revise the Dostoevskian motif of ‘rewarding’ both Raskolnikov and Stavrogin with epiphanic visions, just like Stavrogin’s potential liberation from guilt in suicide. Lurie has to live on with the consequences of crimes committed and suffered, turning for most equivocal relief to Romantic art again in the closing scenes of the novel. All in all, the exploration of both intertextual references contributes to an understanding of Disgrace as an ambiguous comment on depriving evil of its Romantic aspects in a continuing polemic with Dostoevsky

Progression of myopathology in Kearns-Sayre syndrome

We report on the progression of myopathology by comparing two biopsies from a patient with a Kearns-Sayre-Syndrome. The first biopsy was taken in 1979 and showed 10% ragged-red fibers. Myopathic changes were slight including internal nuclei and fiber splitting in 10% of the fibers. Electron microscopy revealed typical mitochondrial abnormalities with regard to number and shape. In 1989 a second biopsy was performed for an extended analysis of mitochondrial DNA. This time less than 5% of all fibers were ragged-red. Severe myopathic changes could be detected which so far has rarely been reported in mitochondrial cytopathy

Benutzerforschung für zwei Teilbibliotheken der Universitätsbibliothek Graz

User studies for two branch libraries of the Graz University Library (translation of the title). In this paper a user study for two libraries of the University of Graz, namely the main library and the Law and Social and Economic Sciences Library, is presented. In detail, user structure, user behavior, and user satisfaction are evaluated by interviewing 276 library users. The results reveal that most users are students who use both libraries quite intensively and are quite satisfied with the existing offer

Interaction and localisation studies of the lipoteichoic acid synthesis proteins in staphylococcus aureus

Lipoteichoic acid (LTA) is an important component of the cell envelope of various Gram-positive bacteria. In Staphylococcus aureus it consists of a polyglycerolphosphate chain that is decorated with D-alanine esters and anchored to the cell membrane via a glycolipid. The lack of D-alanine modifications leads to increased susceptibility to cationic antimicrobial peptides and the complete absence of LTA results in aberrant positioning of septa, enlargement of cells and eventual cell lysis, indicating a link between LTA synthesis and cell division. Although key enzymes required for LTA synthesis and D-alanylation have been identified, the full process has not been elucidated and is investigated in this study. Using a bacterial two-hybrid approach it was shown that the three key LTA synthesis enzymes, YpfP, LtaA and LtaS, interact with one another, indicating the formation of a multi-enzyme complex. In addition, these three proteins interacted with numerous cell division and peptidoglycan synthesis proteins. Fluorescence microscopy studies indicated that YpfP and LtaA localise to the membrane, while LtaS appeared to accumulate at the site of cell division in cells with fully formed septa. Together, these data provide further experimental evidence for the coordination between the processes of cell division and LTA synthesis. Four proteins, DltA-D, are essential for the D-alanylation of LTA. The mechanism begins with DltA transferring D-alanines onto the carrier protein DltC. However, Fischer and colleagues, and Neuhaus and Baddiley have proposed two conflicting models for the remainder of the mechanism for D-alanylation. Here, using a cellular protein localisation analysis it was shown that DltC does not traverse the membrane and membrane topology studies indicated that DltD is anchored to the outside of the cell, contrary to the Neuhaus and Baddiley model. In summary, the data presented in this study are in support of the D-alanine substitution model proposed by Werner Fischer.Open acces