Can portfolio diversification increase systemic risk? evidence from the U.S and European mutual funds market

This paper tests the hypothesis that portfolio diversification can increase the threat of systemic financial risk. The paper provides first a theoretical rationale for the possibility that systemic risk may be increased by the proliferation of financial instruments that lead operators to hold increasingly similar portfolios. Secondly, the paper tests the hypothesis that diversification may result in increasing systematic risk, by analyzing the portfolio dynamics of some of the major world open funds.Systemic Risk, Portfolio Diversification, Mutual Funds, CAPM

Donor/Acceptor Heterojunction Organic Solar Cells

The operation and the design of organic solar cells with donor/acceptor heterojunction structure and exciton blocking layer is outlined and results of their initial development and assessment are reported. Under halogen lamp illumination with 100 mW/cm2 incident optical power density, the devices exhibits an open circuit voltage VOC = 0.45 V, a short circuit current density JSC between 2 and 2.5 mA/cm2 with a fill factor FF ≈ 50%, an external quantum efficiency (electrons/s over incident photons/s) EQE ≈ 5% and a power conversion efficiency of about 0.5%. Measurements of the photoelectrical characteristics with time are also reported, confirming that non encapsulated organic solar cells have limited stability in ambient atmosphere

A two-step hybrid approach for modeling the nonlinear dynamic response of piezoelectric energy harvesters

An effective hybrid computational framework is described here in order to assess the nonlinear dynamic response of piezoelectric energy harvesting devices. The proposed strategy basically consists of two steps. First, fully coupled multiphysics finite element (FE) analyses are performed to evaluate the nonlinear static response of the device. An enhanced reduced-order model is then derived, where the global dynamic response is formulated in the state-space using lumped coefficients enriched with the information derived from the FE simulations. The electromechanical response of piezoelectric beams under forced vibrations is studied by means of the proposed approach, which is also validated by comparing numerical predictions with some experimental results. Such numerical and experimental investigations have been carried out with the main aim of studying the influence of material and geometrical parameters on the global nonlinear response. The advantage of the presented approach is that the overall computational and experimental efforts are significantly reduced while preserving a satisfactory accuracy in the assessment of the global behavior

Parameter identification strategy for online detection of faults in smart structures for energy harvesting and sensing

Abstract In this work, we propose a simple computational method to detect faults in smart piezoelectric structures based on a synchronization strategy. The flexible smart structures are in general described as distributed systems governed by partial differential equations. Numerical discetization is employed to derive a reduced order model such as his dynamic response is simulated solving only ordinary differential equations. Then, the parameter identification strategy is formalized as a dynamic optimization and evolution problem through a further proper set of ordinary differential equations. Lyapunov' theorems are employed to derive an integral type identification algorithm and to ensure the convergence of the procedure. The method is suitable to assess and model nonlinearities in the response of a flexible piezoelectric smart device due to material degradation or local failure. These features are very important to detect faults in the structure and to assess the system reconfiguration properties in real time

Coastline extraction using high resolution WorldView-2 satellite imagery

AbstractThe aim of this paper is to remark possibilities to use WorldView-2 imagery for coastline extraction. Applications are conducted on a Phlegrean area in the Campania Region (Italy): the considered range of coastline is particularly interesting because it shows two typologies of shoreline including reefs interspersed with segments of sandy beach. Two indices are used: Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI).To enhance geometric resolution of the results pan-sharpening is applied so as to obtain maps with the same pixel dimensions of the panchromatic data. To solve the problem of thresholds determination that typically affects the classification, Maximum Likelihood method based on training sites is adopted to distinguish bare soil and sea water. Best results are given by NDWI and, comparing the resultant coastline with that obtained with visual interpretation of images, shifts of less than 1 m outcome from pan-sharpened data

High Resolution Satellite Images to Reconstruct Recent Evolution of Domitian Coastline

In the last decades, combinations of natural and human factors have resulted in extensive morphological changes to our coastlines and in many cases have amplified erosion. In order to limit these changes and their impact on coastal zone, it is important to plan specific actions; for this purpose detailed cognizance of coastal zone is necessary. Different and heterogeneous data such as historical and recent maps, remotely sensed images and topographic survey result very useful to reconstruct temporal shoreline changes. In this study the attention is focalized on Domitian coastal zone (Italy), which is one of the most emblematic examples of coastal erosion in Europe. Study of the shoreline evolution in this area between 1876 and 2005 was used as the starting point of the present paper that investigates over a span of seven years (2005 to 2012), by using remotely sensed data. The aim is to adapt and integrate geomatics techniques to transform very high resolution satellite images in powerful tools to analyse coastline changes. So, in order to identify eroded and added areas, IKONOS-2 (2005), GeoEye-1 (2011) and WorldView-2 (2012) imageries are compared. These data-sets were re-georeferred to improve the positional accuracy. More over Normalized Difference Water Index (NDWI) was applied to pan-sharpened multispectral images to facilitate coastline vectorising at the same geometric resolution of panchromatic data. In addition, variance propagation was considered to establish the accuracy of the reconstruction of coastal evolution. Added and eroded areas were defined and related to the impact of the defence structures that were built in this zone in 2011

Annular elastolytic giant cell granuloma treated with topical pimecrolimus.

4openopenErrichetti E; Stinco G; Avellini C; Patrone P.Errichetti, E; Stinco, Giuseppe; Avellini, C; Patrone, Pasqual

Scalable Recovery-based Adaptation on Quadtree Meshes for Advection-Diffusion-Reaction Problems

We propose a mesh adaptation procedure for Cartesian quadtree meshes, to discretize scalar advection-diffusion-reaction problems. The adaptation process is driven by a recovery-based a posteriori estimator for the $L^2(\Omega)$-norm of the discretization error, based on suitable higher order approximations of both the solution and the associated gradient. In particular, a metric-based approach exploits the information furnished by the estimator to iteratively predict the new adapted mesh. The new mesh adaptation algorithm is successfully assessed on different configurations, and turns out to perform well also when dealing with discontinuities in the data as well as in the presence of internal layers not aligned with the Cartesian directions. A cross-comparison with a standard estimate--mark--refine approach and with other adaptive strategies available in the literature shows the remarkable accuracy and parallel scalability of the proposed approach

Obsidian use in the mosaic of the St. Juvenal church, Narni (Italy): chemical characterization and origin

Tesserae from the mosaic on the front of the San Giovenale chapel inside the Narni Cathedral were analyzed through non-destructive XRF analysis for the characterization of both colouring matters and opacifiers of the glass matrix. Subsequently, the concentration of the elements present at trace levels (μg g-1) was determined by means of Instrumental Neutron Activation Analysis (INAA) for comparisons with obsidians of known provenance and well-studied micro-elemental composition, in order to identify the geographical origin of the obsidian used in this Middle Ages mosaic. The main result is that the black tesserae were made with obsidian fragments coming from the Sardinia deposits (probably, Arci Mountain site C)