Beyond General Relativity: Modified Theories and Non-Singular Black Holes

Einstein's general relativity is an extremely elegant and successful theory. Recent observations coming from the LIGO/VIRGO collaboration as well as from the Event Horizon Telescope give us the possibility to perform precision test of general relativity in regimes never tested before. Even though all the current observations are in perfect agreement with the predictions of general relativity, there are several reasons to study extensions of the theory. From the experimental point of view, we are forced to include a dark sector for the matter and energy content of the universe to explain the cosmological data. Whereas from a conceptual point of view, the theory is not perturbatively renormalizable, and it predicts the formation of spacetime singularities. This thesis studies possible modifications of general relativity both considering specific theories of modified gravity and implementing a model-independent approach. In the first part of the thesis, we study a specific class of modified theory of gravity which has the peculiarity of propagating the same number of degrees of freedom of general relativity. The existence of these theories apparently challenges the distinctive role of general relativity as the unique non-linear theory of massless spin-2 particles. However, we provide strong evidence that these theories are actually equivalent to general relativity in vacuum. In the second part of the thesis, we focus on the problem of black hole singularities which are unavoidably present in general relativity. However, it is reasonable to assume that there will be a mechanism preventing their formation in a full theory of quantum gravity. Without specifying any theory of quantum gravity or the nature of such mechanism, simply assuming a minimal set of kinematical constraints, we classify and study the properties of non-singular spacetime with a trapping horizon. Contrary to what one might expect, the set of regular geometries that arises is remarkably limited. Furthermore, we show that it is very difficult to construct a self-consistent geometry without any long range effect. This gives us further motivation to study the phenomenology of non-singular black holes. To this end, we provide a set of parameters describing the deviations from classical black holes, and we review the possible observational channels that can measure or constrain them

Collapse or transformation? Regeneration and innovation at the turn of the first millennium BC at Arslantepe, Turkey

Ongoing excavations at Arslantepe in south-eastern Turkey are revealing settlement continuity spanning two crucial phases at the transition from the second to the first millennium BC: the post-Hittite period and the development of Syro-Anatolian societies

Iconographic analysis and computational modelling for the study of the Iron Age free-standing lions of the Elbistan plain (south-eastern Anatolia)

Lying between the central Anatolian plateau and the Euphrates region, the Elbistan plain represents an ideal environment for inspecting forms of cultural interconnection. During the Iron Age, this territory was marked by the presence of notable inscribed monuments, the study of which allowed scholars to establish relationships with the most significant Neo-Hittite dynasties. This region is also characterized by the presence of sets of anepigraphic portal lions, positioned seemingly at random in the open landscape and with no apparent relationship with coeval archaeological remains, which have never been concretely integrated into the historical picture. In this contribution, the iconographic and stylistic analysis of these sculptures will allow us to situate them in their chronological and historical framework. A computational spatial model is further used to evaluate the meaning of their positioning as markers of a visual networking system that may have represented the most significant thoroughfares to and from the Elbistan plain.Die Elbistan-Ebene liegt zwischen der zentralanatolischen Hochebene und der Euphratregion, und ist ein ideales Gebiet, um Formen kultureller Verflechtungen zu untersuchen. Während der Eisenzeit gab es in der Ebene zahlreiche Denkmäler mit Inschriften, deren Untersuchung es den Forscherinnen und Forschern ermöglichte, die Beziehungen zu den bedeutendsten der neu-hethitischen Dynastien herzustellen. Die Ebene ist zudem dadurch gekennzeichnet, dass hier anepigraphische Portallöwen wie zufällig und ohne Bezug zu anderen archäologischen Hinterlassenschaften in der offenen Landschaft platziert scheinen. Bisher wurden noch keine Versuche unternommen, die Bedeutung dieser Portallöwen für das historische Gesamtbild zu klären. Daher werden, ausgehend von ikonographischen und stilistischen Analysen dieser Skulpturen, zunächst Vorschläge zu ihrer chronologischen und historischen Einordnung gemacht. Im Anschluss daran werden die Ergebnisse einer computergestützten räumlichen Analyse vorgestellt, durch die die Position und Bedeutung der Löwenskulpturen in einem visuellen Netzwerk und unter Berücksichtigung der wichtigsten Verkehrswege von und zur Elbistan-Ebene untersucht wurden

Brain imaging in Kufs disease type B. case reports

The clinical traits of Kufs disease (KD) type B (CLN13), an adult-onset neuronal ceroid lipofuscinosis (NCL), are well established according to the neurological features of the cases reported with mutations in CTSF. The neuroradiological characteristics of this uncommon disease have not yet been outlined

Morphology of Lipari offshore (Southern Tyrrhenian Sea)

High-resolution multibeam bathymetry was recently collected around Lipari, the largest and most densely populated island of the Aeolian Archipelago (Southern Tyrrhenian Sea). The data were acquired within the context of marine geological studies performed in the area over the last 10 years. We present the first detailed morphological map of the Lipari offshore at 1:100,000 scale (Main Map). A rugged morphology characterizes the submarine portions of Lipari volcano, reflecting both volcanic and erosive-depositional processes. The volcanic features include cones, lava flows and bedrock outcrops. Erosive-depositional features include an insular shelf topped by submarine depositional terraces related to LateQuaternary sea-level fluctuations, as well as landslide scars, channelized features, fanshaped deposits and wavy bedforms. The different distribution of volcanic and erosivedepositional features on the various sectors of Lipari is mainly related to the older age of the western flank with respect to the eastern one. The map also provides insights for a first marine geohazard assessment of this active volcanic area

Targeting Polymorphonuclear Leukocytes in Acute Myocardial Infarction

Several studies have recognized the strong impact that the acute myocardial infarctions (AMI) have on the morbidity and mortality of patients affected by cardiovascular diseases. Still open, however, is the field concerning the mediators and the pathways involved in the etiology of this cardiovascular event. The present review would support the relatively new discovered role that the polymorphonuclear leukocytes (PMNs) have in the pathogenesis of the AMI, through a brief analysis of past and ongoing research. Particularly, it is reviewed here the possibility that inhibition of the activity of PMNs and inhibition of the signaling pathways related to their activity may result useful in AMI and may improve the prognosis of this pathology. This review, indeed, presents and discusses new data on one of the lipid kinase, the phosphoinositide 3-kinase gamma (PI3Kγ), and its role in neutrophil recruitment during AMI

Erratum: Minimally modified theories of gravity: a playground for testing the uniqueness of general relativity

In a recent paper [1], it was introduced a new class of gravitational theories with two local degrees of freedom. The existence of these theories apparently challenges the distinctive role of general relativity as the unique non-linear theory of massless spin-2 particles. Here we perform a comprehensive analysis of these theories with the aim of (i) understanding whether or not these are actually equivalent to general relativity, and (ii) finding the root of the variance in case these are not. We have found that a broad set of seemingly different theories actually pass all the possible tests of equivalence to general relativity (in vacuum) that we were able to devise, including the analysis of scattering amplitudes using on-shell techniques. These results are complemented with the observation that the only examples which are manifestly not equivalent to general relativity either do not contain gravitons in their spectrum, or are not guaranteed to include only two local degrees of freedom once radiative corrections are taken into account. Coupling to matter is also considered: we show that coupling these theories to matter in a consistent way is not as straightforward as one could expect. Minimal coupling, as well as the most straightforward non-minimal couplings, cannot be used. Therefore, before being able to address any issues in the presence of matter, it would be necessary to find a consistent (and in any case rather peculiar) coupling scheme

Charge transfer and trapping as origin of a double dip in the transfer characteristics of graphene based field-effect transistors

We discuss the origin of an additional dip other than the charge neutrality point observed in transfer characteristics of graphene-based field-effect transistors. The double-dip is proved to arise from charge transfer between graphene and metal electrodes, while charge storage at the graphene/SiO2 interface enhances it. Considering different Fermi energy from the neutrality point along the channel and partial charge pinning at the contacts, we propose a model which explains all features in gate voltage loops.Comment: 14 pages, 5 figure

Picking out a wine: Consumer motivation behind different quality wines choice

The quality scale of Italian wines is mainly organized in four categories: PDO, PGI, basic and bulk wine. Our analysis explicitly investigates the patterns and determinants of consumption for these four different types of wine by analyzing a representative sample of consumers from a traditional wine-producing country. This study provides for first time insights on quality perceptions of wines and verifies whether Italian consumers perceive significant differences among the different categories of wines. The overall results, obtained through a system of equation estimates, show that consumer motivations and wine consumption determinants change according to each different range of wine quality and thereby support a hierarchical scale of quality wines, as a fact consumers' motivation progressively changes as the quality scales of the wine increase or decrease. In addition, this study highlights for first time any differences in the consumption determinants between the PDO and the PGI wines in a national context and it suggests that the influence of the two different GI labels on the wine choice of consumers is truly different. Important insights were also provided for bulk wine whose consumption seems to be closely related to wine tourism and the desire to buy locally produced wines. Keywords: Basic wines, Bulk wines, Local wines, PDO, PG