3,242 research outputs found

    Multimetric Supergravities

    Get PDF
    Making use of integral forms and superfield techniques we propose supersymmetric extensions of the multimetric gravity Lagrangians in dimensions one, two, three and four. The supersymmetric interaction potential covariantly deforms the bosonic one, producing in particular suitable super-symmetric polynomials generated by the Berezinian. As an additional application of our formalism we construct supersymmetric multi-Maxwell theories in dimensions three and four.Comment: 37 pages, Latex2e, no figure

    Underpricing and Firm’s Distance from Financial Centre: Evidence from three European Countries

    Get PDF
    We provide international evidence on the relationship between the extent of underpricing related to initial public offerings (IPOs) and the distance of the issuing firm from the financial centre of a country: for France, Germany and Italy, the higher the distance, the higher the level of underpricing. Under the maintained assumption that headquarters of institutional investors and underwriters are part of a financial centre, our evidence is consistent with the hypothesis that ex ante uncertainty regarding the value per share of an issuing firm increases with the firm’s physical distance from the underwriter. As financial centres are usually located in the richest areas of the countries concerned, spatial difference in the cost of equity financing may contribute to the persistence or the widening of local disparities.Asymmetric information, Distance, IPO, Underpricing

    Multitemporal dendrogeomorphological analysis of slope instability in Upper Orcia Valley (Southern Tuscany, Italy)

    Get PDF
    The Upper Orcia Valley (Southern Tuscany, Italy) is a key site for the comprehension of denudation processes typically acting in Mediterranean badlands (calanchi) areas, thanks to the availability of long-lasting erosion monitoring datasets and the rapidity of erosion processes development. These features make the area suitable as an open air laboratory for the study of badlands dynamic and changes in geoheritage due to erosion (i.e. active geomorphosites). Decadal multitemporal investigations on the erosion rates and the geomorphological dynamics of the study area allowed to highlight a decrease in the average water erosion rates during the last 60 years. More in detail, a reduction of bare land and, consequently, of erosion processes effectiveness and a contemporary increasing frequency of mass wasting events were recorded. These trends can be partly related to the land cover changes occurred in the study area from the 1950s onwards, which consist of the significant increase of reforestation practices and important other forms of human impacts on slopes, mainly land levelling for agricultural exploitation. In order to better identify the most significant phases of geomorphological instability occurred in this area during the last decades, an integrated approach based on multitemporal geomorphological mapping and dendrogeomorphology analysis on specimen of Pinus nigra Arn. was used. In detail, trees colonizing a denudation slope located in the surrounding of the Radicofani town (Tuscany, Italy) and characterized by calanchi and shallow mass movements deposits, were analyzed for the 1985-2012 time period. The analysis of the growth anomaly indexes and of compression wood allowed to determine a spatio-temporal differentiation along the slope and respect to an undisturbed reference site. The negative anomaly index results to be more pronounced in the trees located on the investigated slope with respect to the ones sampled in a non-disturbed area. Compression wood characterizes trees on slope sectors mainly affected by runoff and/or mass movements with a different persistence. Erosion rates were finally calculated through dendrogeomorphological analysis on tree roots exposure (0.31-3 cm/y runoff prevailing; 5.86-27.5 cm/y, mass movements prevailing). Dendrogeomorphological results are in accordance with those obtained in the investigated areas with multitemporal photogrammetric and geomorphologic analyses

    Supersymmetric Field Theories and Isomonodromic Deformations

    Get PDF
    The topic of this thesis is the recently discovered correspondence between supersymmetric gauge theories, two-dimensional conformal field theories and isomonodromic deformation problems. Its original results are organized in two parts: the first one, based on the papers [1], [2], as well as on some further unpublished results, provides the extension of the correspondence between four-dimensional class S theories and isomonodromic deformation problems to Riemann Surfaces of genus greater than zero. The second part, based on the results of [3], is instead devoted to the study of five-dimensional superconformal field theories, and their relation with q-deformed isomonodromic problems

    BPS Spectra and Algebraic Solutions of Discrete Integrable Systems

    Full text link
    This paper extends the correspondence between discrete Cluster Integrable Systems and BPS spectra of five-dimensional N=1\mathcal{N}=1 QFTs on R4×S1\mathbb{R}^4\times S^1 by proving that algebraic solutions of the integrable systems are exact solutions for the system of TBA equations arising from the BPS spectral problem. This statement is exemplified in the case of M-theory compactifications on local del Pezzo Calabi-Yau threefolds, corresponding to q-Painlev\'e equations and SU(2)SU(2) gauge theories with matter. A degeneration scheme is introduced, allowing to obtain closed-form expression for the BPS spectrum also in systems without algebraic solutions. By studying the example of local del Pezzo 3, it is shown that when the region in moduli space associated to an algebraic solution is a ``wall of marginal stability'', the BPS spectrum contains states of arbitrarily high spin, and corresponds to a 5d uplift of a four-dimensional nonlagrangian theory.Comment: 38 pages, 11 figure

    Fluvial dynamics and watermills location in Basilicata (Southern Italy)

    Get PDF
    Watermills (grain mills, waulk mills, olive mills, sawmills and threshing machines) operated in the Basilicata Region from the Roman Period until the early decades of the twentieth century, representing an important feature of waterways that is today almost totally forgotten. Using documentary sources, ancient maps and field survey it is possible to catalogue and identify the location of these ancient hydraulic structures. Watermills were usually placed far enough away from the river to avoid inundation during floods, and near natural knickpoints or artificial steps in the river long profile that were created by mill engineers. Mill construction often had significant impacts on a rivers morphology, because it was necessary to divert the river discharge towards the mill wheel, to drive the grain-grinding mechanism. Watermill typological variations have been examined in relation to variations in river pattern to assess the ways in which the hydrographic and hydrological settings of the Basilicata Region have affected mill siting and operation. Most Basilicata watermills were built with a horizontal water-wheel and a tower. The characteristics of the tower and the associated hydraulic structures varied according to the environmental setting. Finally, mill positions define also the locations on the river system that have already been used to exploit hydraulic power and thus could be useful for future use in the micro-hydroelectric secto

    Progettazione di un sistema di interfaccia per bio-sensore basato su piattaforma "ISIF"

    Get PDF
    Questa tesi tratta la progettazione e realizzazione di un sistema di interfaccia e condizionamento per un bio-sensore basato su piattaforma "ISIF". La piattaforma ISIF é un sistema dotato di una sezione di acquisizione analogica, una di processamento digitale e una CPU in grado di eseguire routine firmware. L'obiettivo del presente lavoro é stato trovare la configurazione piú adeguata per la sezione analogica, nonché realizzare il firmware; inoltre é sato sviluppato un software per l'acquisizione dei dati

    Clinical relevance of free peritoneal tumor cells detection in gastric and colorectal cancer: a multiple molecular approach

    Get PDF
    Background Free disseminated peritoneal tumor cells derive from the detachment from primary cancer and may result in peritoneal carcinomatosis. Peritoneal lavage cytology has low sensitivity in detecting free peritoneal tumor cells; reverse-transcriptase polymerase reaction showed higher sensitivity but low specificity. Our study introduces the combination of the RT-PCR, the immunomagnetic enrichment and the immunofluorescence for the detection of peritoneal free tumor cells. Materials and Methods Samples of peritoneal lavage were collected from 22 gastric and 45 colorectal cancer patients; samples were also obtained from 6 patients who underwent abdominal surgery for non-malignant diseases. CEA and CK20 mRNA levels were quantified using a real-time qRT-PCR system. Immunomagnetic enrichment followed by immunofluorescence analysis was performed using monoclonal antibody against the pan-epithelial marker EpCAM/CD326 and polyclonal antibodies against the carcinoembryonic antigen. Results For gastric carcinoma the positivity rate for cytology, immunofluorescence and qRT-PCR was 14%, 18% and 77% respectively; for colorectal carcinoma the positivity rate for cytology, immunofluorescence and qRT-PCR was 0%, 18% and 44% respectively. All patients except one when positive at immunofluorescence were also positive at qRT-PCR. All samples of peritoneal lavage from the control group resulted negative for cytology, IF and real time qRT-PCR. Conclusion The combination of conventional real time qRT-PCR with immunoenrichment and immunofluorescence, which permit morphological assessment and unequivocal identification of the DTCs as well as validation of the molecular analysis, could be an useful and more powerful procedure for the detection of free peritoneal tumor cells
    • …
    corecore