399 research outputs found
Uninsurable Investment Risks
The authors study a general-equilibrium economy in which agents have the ability to invest in a risky technology. The investment risk cannot be fully insured with optimal contracts, because shocks are private information. The authors show that the presence of these risks may lead to an underaccumulation of capital relative to an economy where idiosyncratic shocks can be fully insured. They also show that, although the availability of state-contingent (optimal) contracts cannot provide full insurance, it brings the aggregate stock of capital close to the complete markets level. Institutional reforms that make the use of these contracts possible have important welfare consequences.Economic models; Financial institutions; Financial markets
Testing the Dispersion of Nanoparticles in a Nanocomposite with an Ultra-Low Fill Content Using a Novel Non-Destructive Evaluation Technique
A non-destructive evaluation (NDE) technique capable of testing the dispersion of nanoparticles in a nanocomposite would be of great use to the industry to check the quality of the products made and to ensure compliance with their specifications. Very few NDE techniques found in the literature can evaluate the level of dispersion of the nanoparticles in the whole nanocomposite. Here, a recently developed NDE technique based on pulsed phase thermography (PPT) in transmission mode was used to assess the particle dispersion in ultra-low, less than 0.05 wt%, Ag enriched polymeric based nanocomposite manufactured with an innovative nano-coating fragmentation technique. The phasegrams obtained with the presented technique clearly showed clusters or bundles of Ag nanoparticles when present, down to the size of 6 µm. Therefore, the new NDE approach can be applied to verify that the expected levels of dispersion are met in the production process
A Virtual PEP for Web Optimization over a Satellite-Terrestrial Backhaul
The availability of network softwarization and virtualization technology in the field of telecommunications has opened the door to a radical review of the applications, protocols, and deployment models. In this evolving framework, old assumptions and constraints specific to satellite communications must be carefully re-assessed. To this aim, we revisit the role of the performance enhancing proxy (PEP), replaced by a chain of custom virtual network functions properly enabled to optimize common web traffic performance over a backhaul dynamically enabled with a supplementary satellite link. The resulting virtual PEP (vPEP) is compliant with the breakthrough virtualization and slicing paradigms and can fruitfully exploit the advanced features of the most recent IETF technologies such as QUIC and MPTCP
Abiraterone acetate in metastatic castration-resistant prostate cancer after chemotherapy. A retrospective “Real Life” analysis of activity and safety
Abiraterone acetate (AA) is a potent, selective androge (CYP17) biosynthesis inhibitor, which showed to improve overall survival (HR = 0.646) in mCRPC patients progressing after docetaxel. In this retrospective analysis we assessed the safety and efficacy of AA in patients affected with mCRPC progressing after chemotherapy, treated in the normal clinical practice, in several Italian Oncologic Units, after the approval of the drug from the Italian Drug Agency (AIFA)
IBIS/PICsIT in-flight performances
PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy
detector of the IBIS telescope on-board the INTEGRAL satellite. PICsIT operates
in the gamma-ray energy range between 175 keV and 10 MeV, with a typical energy
resolution of 10% at 1 MeV, and an angular resolution of 12 arcmin within a
\~100 square degree field of view, with the possibility to locate intense point
sources in the MeV region at the few arcmin level. PICsIT is based upon a
modular array of 4096 independent CsI(Tl) pixels, ~0.70 cm^2 in cross-section
and 3 cm thick. In this work, the PICsIT on-board data handling and science
operative modes are described. This work presents the in-flight performances in
terms of background count spectra, sensitivity limit, and imaging capabilities.Comment: 8 pages, 4 figures. Accepted for publication on A&A, special issue on
First Science with INTEGRA
Systematic effects induced on IBIS detectors by background and inhomogeneity of the spatial response
The spatial distribution of the background events may affect the source
detection capability of IBIS at high energies (> 200 keV) for both ISGRI and
PICsIT layers. The observed background is found to be variable and spatially
structured, and in some cases its properties strongly deviate from the expected
statistical behaviour. Background correction methods are then necessary to
improve the quality of the shadowgrams obtained from sources. In order to
perform an efficient flat-fielding the response of the detector to both source
gamma-rays and background events is investigated using data from Monte Carlo
simulations and in-flight calibration observations.Comment: 5 pages, 1 latex file, 6 figures, accepted for publication on
Astronomy and Astrophysics, INTEGRAL special issu
In-flight calibrations of IBIS/PICsIT
PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy
detector of the IBIS telescope on-board the INTEGRAL satellite. It consists of
4096 independent detection units, ~0.7 cm^2 in cross-section, operating in the
energy range between 175 keV and 10 MeV. The intrinsically low signal to noise
ratio in the gamma-ray astronomy domain implies very long observations, lasting
10^5-10^6 s. Moreover, the image formation principle on which PICsIT works is
that of coded imaging in which the entire detection plane contributes to each
decoded sky pixel. For these two main reasons, the monitoring, and possible
correction, of the spatial and temporal non-uniformity of pixel performances,
expecially in terms of gain and energy resolution, is of paramount importance.
The IBIS on-board 22Na calibration source allows the calibration of each pixel
at an accuracy of <0.5% by integrating the data from a few revolutions at
constant temperature. The two calibration lines, at 511 and 1275 keV, allow
also the measurement and monitoring of the PICsIT energy resolution which
proves to be very stable at ~19% and ~9% (FWHM) respectively, and consistent
with the values expected analytical predictions checked against pre-launch
tests.Comment: 5 pages, 7 figures. Accepted for publication on A&A Special Issue on
First Science with INTEGRA
Looking at NB-IoT over LEO Satellite Systems: Design and Evaluation of a Service-Oriented Solution
The adoption of the NB-IoT technology in satellite communications intends to boost Internet of Things services beyond the boundaries imposed by the current terrestrial infrastructures. Apart from link-level studies in the scientific literature and preliminary 3GPP technical reports, the overall debate is still open. To provide a further step forward in this direction, the work presented herein pursues a novel service-oriented methodology to design an effective solution, meticulously stitched around application requirements and technological constraints. To this end, it conducts link-level and system-level investigations to tune physical transmissions, satellite constellation, and protocol architecture, while ensuring the expected system behavior. To offer a real smart agriculture service operating in Europe, the resulting solution exploits 24 Low Earth Orbit satellites, grouped into 8 different orbits, moving at an altitude of 500 km. The configured protocol stack supports the transmission of tens of bytes generated at the application layer, by also counteracting the issues introduced by the satellite link. Since each satellite has the whole protocol stack on-board, terminals can transmit data without the need for the feeder link. This ensures communication latencies ranging from 16 minutes to 75 minutes, depending on the served number of terminals and the physical transmission settings. Moreover, the usage of the Early Data Transmission scheme reduces communication latencies up to 40%. These results pave the way towards the deployment of an effective proof-of-concept, which drastically reduces the time-to-market imposed by the current state of the art
- …