A search for Galactic transients disguised as gamma-ray bursts

A significant fraction of cosmological gamma-ray bursts (GRBs) are characterised by a fast rise and exponential decay (FRED) temporal structure. This is not a distinctive feature of this class, since it is observed in many Galactic transients and is likely descriptive of a sudden release of energy followed by a diffusion process. Possible evidence has recently been reported by Tello et al. (2012) for a Galactic contamination in the sample of FRED GRBs discovered with Swift. We searched for possible Galactic intruders disguised as FRED GRBs in the Swift catalogue up to September 2014. We selected 181 FRED GRBs (2/3 with unknown redshift) and considered different subsamples. We tested the degree of isotropy through the dipole and the quadrupole moment distributions, both with reference to the Galaxy and in a coordinate-system-independent way, as well as with the two-point angular autocovariance function. In addition, we searched for possible indicators of a Galactic origin among the spectral and temporal properties of individual GRBs. We found marginal (~3 sigma) evidence for an excess of FREDs with unknown redshift towards the Galactic plane compared with what is expected for an isotropic distribution corrected for the non-uniform sky exposure. However, when we account for the observational bias against optical follow-up observations of low-Galactic latitude GRBs, the evidence for anisotropy decreases to ~2 sigma. In addition, we found no statistical evidence for different spectral or temporal properties from the bulk of cosmological GRBs. We found marginal evidence for the presence of a disguised Galactic population among Swift GRBs with unknown redshift. The estimated fraction is f=(19 +- 11)%, with an upper limit of 34% (90% confidence).Comment: 6 pages, 4 figures, accepted by A&

A revisitation of the 1888 H.Hertz experiment

We propose a revisitation of the original experiment performed by H. Hertz in 1888. With a simple setup it is possible to produce electromagnetic waves with a frequency in the range of 3 MHz. By performing Fourier analysis of the signal captured by a resonant antenna it is possible to study the behaviour of the RLC series circuit, frequency splitting of coupled resonances and finally the characteristics of the near-field emitted by the loop antenna

Studij dinamike zvezdne snovi med dogodkom plimskega raztrganja

The number of observed tidal disruption events is increasing rapidly with the advent of new surveys. Thus, it is becoming increasingly important to improve TDE models using different stellar and orbital parameters. We study the dynamical behaviour of tidal disruption events produced by a massive black hole like Sgr A* by changing different initial orbital parameters, taking into account the observed orbits of S stars. Investigating different types of orbits and penetration factors is important since their variations lead to different timescales of the tidal disruption event debris dynamics, making mechanisms such as self-crossing and pancaking act strongly or weakly, thus affecting the circularisation and accretion disk formation. We have performed smoothed particle hydrodynamics simulations. Each simulation consists in modelling the star with $10^5$ particles, and the density profile is described by a polytrope with $gamma$ = 5/3. The massive black hole is modelled with a generalised post-Newtonian potential, which takes into account relativistic effects of the Schwarzschild space-time. Our analyses find that mass return rate distributions of solar-like stars and S-like stars with same eccentricity have similar durations, but S-like stars have higher mass return rate, as expected due to their larger mass. Regarding debris circularisation, we identify four types of evolution, related to the mechanisms and processes involved during circularisation: in type 1 the debris does not circularise efficiently, hence a disk is not formed or is formed after relatively long timein type 2 the debris slowly circularises and eventually forms a disk with no debris falling backin type 3 the debris relatively quickly circularises and forms a disk while there is still debris falling backfinally, in type 4 the debris quickly and efficiently circularises, mainly through self-crossings and shocks, and forms a disk with no debris falling back. Finally, we find that the standard relation of circularisation radius $r_{rm circ} = 2r_{rm t}$ holds only for $beta = 1$ and eccentricities close to parabolic.v Stevilo opav zenih dogodkov plimskih raztrganj hitro narav sv ca zahvaljujov c novim pregledom neba. Zato postaja vedno pomembneje, da izboljv samo modele dogodkov plimskih raztrganj in dobimo teoretiv cne napovedi za razliv cne zvezdne in orbitalne parametre. V tej disertaciji smo prouv cevali dinamiv cno obnav sanje snovi ob plimskih raztrganjih zvezd v bliv zini masivne v crne luknje, kakrv sna je Sgr A* v srediv sv cu nav se Galaksije, pri v cemer smo spreminjali zav cetne orbitalne parametre in upov stevali opazovane orbite S zvezd. Prouv cevanje razliv cnih vrst orbit in parametrov trka je pomembno, saj le-ti vplivajo na v casovno skalo dinamike ostankov plimskih raztrganj, na jakost mehanizmov, kot sta samo-prev ckanje in splov sv citev, ter s tem na cirkularizacijo in nastanek akrecijskega diska. Simulacije smo izvedli z metodo hidrodinamike zglajenih delcev. V simulacijah smo zvezdo modelirali z $10^5$ delci in gostotnim profilom, kot ga opiv se politropni model z $gamma = 5/3$. Vpliv masivne v crne luknje smo modelirali s posplov senim post-Newtonskim potencialom, ki upov steva relativistiv cne efekte Schwarzschildovega prostor-v casa. Nav se analize kav zejo, da imajo porazdelitve hitrosti vrav canja snovi za zvezde podobne Soncu in za zvezde podobne S-zvezdam pri enaki ekscentriv cnosti podoben v cas trajanja, vendar imajo S-zvezde viv sjo vrednost histrosti vrav canja snovi, kot je priv cakovano zaradi njihove vev cje mase. Glede cirkularizacije ostankov smo identificirali v stiri tipe razvoja, ki so povezani z mehanizmi in procesi med cirkularizacijo: pri tipu 1 se ostanki zvezde ne cirkularizirajo uv cinkovito in poslediv cno disk ne nastane ali pa nastane po relativno dolgem v casupri tipu 2 se ostanki zvezde cirkularizirajo pov casi in sv casoma tvorijo disk, pri v cemer ne ostane niv c snovi, ki bi v se padala proti diskupri tipu 3 se ostanki zvezde relativno hitro cirkularizirajo in tvorijo disk, vendar ostane v se nekaj snovi, ki pada na diskpri tipu 4 pa se ostanki zvezde hitro in uv cinkovito cirkularizirajo, vev cinoma zaradi samo-prev ckanja in udarnih valov, in tvorijo disk, pri v cemer ne ostane niv c snovi, ki bi padala proti disku. Ugotovili smo tudi, da standardna zveza, da je cirkularizacijski polmer enak dvakratniku plimskega polmera, $r_{circ} = 2r_t$ , velja le za parameter trka $beta = 1$ in ekscentriv cnosti blizu paraboliv cni

Poetics of the Elsewhere Notes on Peter Sloterdijk and the Question of Utopia

The paper explores the question of utopia in the work of Peter Sloterdijk from a narratological and meta-poetic perspective. The analysis focuses on a new text by the German thinker, published in 2018 as an afterword to the German edition of Thomas More’s Utopia, translated from the original Latin by Jacques Laager. In the paper I will present the text, contextualizing it in the complexity of Sloterdijk’s work. I will examine some of its thematical and stylistic features, which disclose the in-terplay between storytelling, space, and writing in the construction processes of the concepts of sub-jectivity, otherness, and community. Moreover, such an interplay allows to read the space of writing as a place of meta-reflection through which the author, by rethinking and rewriting the (hi)story of mankind from different conceptual prisms, rethinks and rereads also the peregrination of a new philosophical subject in the landscape of writing.

Crossed alliances in Argentina: A theoretical causal approach

La política de alianzas electorales es un elemento estratégico de los partidos para obtener votos y cargos. Además de estar facultados para armar sus propias alianzas para competir por cargos provinciales, los partidos subnacionales en Argentina pueden efectuar alianzas para cargos legislativos nacionales independientemente de las alianzas que sus mismas estructuras a nivel nacional realicen para competir por la presidencia. El presente trabajo tiene el propósito de realizar una revisión de las literaturas que resultan útiles para estudiar las alianzas electorales en sistemas presidencialistas multinivel, señalando asimismo, los posibles interrogantes que se plantean al pensar causalmente las alianzas cruzadas.Electoral alliances are strategic elements parties use to obtain votes and seats. Argentinean sub-national parties are allowed by law to form alliances both, for provincial elections and for federal Congress ones, independently of the strategy the party conducts at the national level. Sub-national parties’ autonomy for partners selection may cause that allies in a level of competition could be competitors at other level at the same time, what we called incongruent alliances. This paper seeks to review relevant literature in order to analyze electoral alliances under presidential systems. Additionally, it will invite to think about possible causes of incongruent alliances.Fil: Clerici, Paula Andrea. Universidad de Buenos Aires. Facultad de Cs.sociales. Carrera de Ciencia Politica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Torcuato Di Tella; Argentin

Encounters, in Spite of All. Samuel Beckett and Paul Celan

The paper investigates from a literary perspective the question of the ‘missed encounter’ between two crucial authors of 20th century: Samuel Beckett and Paul Celan. Although both living in Paris for the most part of their adult life, sharing acquaintances and friendships, Beckett and Celan never met in person. A last chance presented in March 1970, as the poet and translator Franz Wurm, a mutual friend, invited Celan to come along and meet Beckett. The meeting never took place; few weeks thereafter, Celan drowned unobserved in the Seine. In this paper, I propose a retrospective reading of the ‘missed’, or ‘failed’ encounter between Beckett and Celan within a psychoanalytic framework. I will analyse it as a negative event, re-elaborating thus an expression used by André Green in his interpretation of Henry James’ The Beast in the Jungle (1903). What Green calls negative event does not provide a patho-biographical category. On the contrary, it bridges the reverberations of the psychic work on absence with the creative process of writing and the dynamics of sublimation. Shifting the attention from the bare biographical data to the textual dimension of such ‘missed encounter’, I aim to show how the writings of the two authors may be read as an articulation of an après-coup of a non-encounter which, instead of taking place in ‘real life’, opens new margins of representation of an alterity within the ‘life of writing’. As such, writing becomes—between poetry and psychoanalysis—that ‘thirdness’ harbouring the very possibility of an encounter beyond phenomenological categories, bearing testimony for an unknown transgenerational reader

Synthesis, Conformation and Antiproliferative Activity of Isothiazoloisoxazole 1,1-dioxides

Sixteen new isothiazoloisoxazole 1,1-dioxides, one new isothiazolotriazole and one new isothiazolopyrazole have been synthesised by using 1,3-dipolar cycloadditions to isothiazole 1,1-dioxides. One sub-set of these isothiazoloisoxazoles showed low μM activity against a human breast carcinoma cell line, whilst a second sub-set plus the isothiazolotriazole demonstrated an interesting restricted rotation of sterically hindered bridgehead substituents. A thiazete 1,1-dioxide produced from one of the isothiazole 1,1-dioxides underwent conversion into an unknown 1,2,3-oxathiazolin-2-oxide upon treatment with Lewis acids, but was inert towards 1,3-dipoles and cyclopropenones. Six supporting crystal structures are included