Integrated Support for Handoff Management and Context-Awareness in Heterogeneous Wireless Networks

The overwhelming success of mobile devices and wireless communications is stressing the need for the development of mobility-aware services. Device mobility requires services adapting their behavior to sudden context changes and being aware of handoffs, which introduce unpredictable delays and intermittent discontinuities. Heterogeneity of wireless technologies (Wi-Fi, Bluetooth, 3G) complicates the situation, since a different treatment of context-awareness and handoffs is required for each solution. This paper presents a middleware architecture designed to ease mobility-aware service development. The architecture hides technology-specific mechanisms and offers a set of facilities for context awareness and handoff management. The architecture prototype works with Bluetooth and Wi-Fi, which today represent two of the most widespread wireless technologies. In addition, the paper discusses motivations and design details in the challenging context of mobile multimedia streaming applications

Analytical computation of the off-axis Effective Area of grazing incidence X-ray mirrors

Focusing mirrors for X-ray telescopes in grazing incidence, introduced in the 70s, are characterized in terms of their performance by their imaging quality and effective area, which in turn determines their sensitivity. Even though the on-axis effective area is assumed in general to characterize the collecting power of an X-ray optic, the telescope capability of imaging extended X-ray sources is also determined by the variation in its effective area with the off-axis angle. [...] The complex task of designing optics for future X-ray telescopes entails detailed computations of both imaging quality and effective area on- and off-axis. Because of their apparent complexity, both aspects have been, so far, treated by using ray-tracing routines aimed at simulating the interaction of X-ray photons with the reflecting surfaces of a given focusing system. Although this approach has been widely exploited and proven to be effective, it would also be attractive to regard the same problem from an analytical viewpoint, to assess an optical design of an X-ray optical module with a simpler calculation than a ray-tracing routine. [...] We have developed useful analytical formulae for the off-axis effective area of a double-reflection mirror in the double cone approximation, requiring only an integration and the standard routines to calculate the X-ray coating reflectivity for a given incidence angle. [...] Algebraic expressions are provided for the mirror geometric area, as a function of the off-axis angle. Finally, the results of the analytical computations presented here are validated by comparison with the corresponding predictions of a ray-tracing code.Comment: 12 pages, 11 figures, accepted for publication in "Astronomy & Astrophysics", section "Instruments, observational techniques, and data processing". Updated version after grammatical revision and typos correctio

Towards Runtime Verification via Event Stream Processing in Cloud Computing Infrastructures

Software bugs in cloud management systems often cause erratic behavior, hindering detection, and recovery of failures. As a consequence, the failures are not timely detected and notified, and can silently propagate through the system. To face these issues, we propose a lightweight approach to runtime verification, for monitoring and failure detection of cloud computing systems. We performed a preliminary evaluation of the proposed approach in the OpenStack cloud management platform, an “off-the-shelf” distributed system, showing that the approach can be applied with high failure detection coverage

Viscosity of choline chloride-based deep eutectic solvents: Experiments and modeling

Deep eutectic solvents (DESs) have emerged as promising “green” solvents, but their successful industrial application requires relatively low viscosity. DESs prepared from choline chloride and glycols offer such a possibility. Viscosity and density are reported for a number of DESs obtained by mixing choline chloride and a glycol (ethylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol). The measurements were performed at 101.3 kPa, at temperatures between 293.15 and 333.15 K, and for different mole ratios of glycol and choline chloride. The viscosity was measured with a capillary viscometer, while the density was measured by means of a vibrating U-tube densimeter. The density and viscosity data have expanded relative uncertainties of 0.2 and 2.0%, respectively, with a coverage factor of 2. The viscosity of pure glycols was modeled using the extended hard-sphere (EHS) model that has its basis in kinetic theory and the molecular description of the fluid. Each DES was treated as a binary mixture, and the EHS model was used, with a mole average mixing rule, to calculate its viscosity. The measured DES viscosity data were represented with an average absolute deviation of 1.4% and a maximum deviation of 7%

Response of the Pacific Sector of the Southern Ocean to wind stress variability from 1995 to 2017

AbstractDrifter, satellite, expendable bathythermograph (XBT), and Argo float data are used to study the response of the Pacific Sector of the Southern Ocean (PSSO) to the wind stress field in the period 1995–2017, in terms of eddy field, water mass transport, and heat fluxes at large and regional scales. Increasing wind stress over the PSSO in those two decades led to a growth of the Eddy Kinetic Energy (EKE) in the region of the Antarctic Circumpolar Current (ACC). Increases of the EKE occur with delays of 1–4 years with respect to peaks in the zonal component of the wind stress. The persistent ACC meander located south of New Zealand (between 150°E and 180°W and 50°S to 66°S) responds to the interannual wind variations earlier than the entire ACC branch in the PSSO. In the same area, an estimate of the ACC transport based on in situ data shows interannual variability but no significant decadal trend over the study period. The effects of the EKE variability on the meridional eddy heat fluxes are significant on interannual scales. The strengthening of the EKE field leads to a local increase in the poleward meridional eddy heat fluxes in the PSSO, especially in the ACC band. The weakening of the EKE field defines an area of equatorward meridional eddy heat fluxes in the middle of the PSSO (south of 40°S, between 130°W and 160°W) and prevalent poleward fluxes in the further western and eastern regions

EVIL: Exploiting Software via Natural Language

Writing exploits for security assessment is a challenging task. The writer needs to master programming and obfuscation techniques to develop a successful exploit. To make the task easier, we propose an approach (EVIL) to automatically generate exploits in assembly/Python language from descriptions in natural language. The approach leverages Neural Machine Translation (NMT) techniques and a dataset that we developed for this work. We present an extensive experimental study to evaluate the feasibility of EVIL, using both automatic and manual analysis, and both at generating individual statements and entire exploits. The generated code achieved high accuracy in terms of syntactic and semantic correctness

Simbol-X Hard X-ray Focusing Mirrors: Results Obtained During the Phase A Study

Simbol-X will push grazing incidence imaging up to 80 keV, providing a strong improvement both in sensitivity and angular resolution compared to all instruments that have operated so far above 10 keV. The superb hard X-ray imaging capability will be guaranteed by a mirror module of 100 electroformed Nickel shells with a multilayer reflecting coating. Here we will describe the technogical development and solutions adopted for the fabrication of the mirror module, that must guarantee an Half Energy Width (HEW) better than 20 arcsec from 0.5 up to 30 keV and a goal of 40 arcsec at 60 keV. During the phase A, terminated at the end of 2008, we have developed three engineering models with two, two and three shells, respectively. The most critical aspects in the development of the Simbol-X mirrors are i) the production of the 100 mandrels with very good surface quality within the timeline of the mission; ii) the replication of shells that must be very thin (a factor of 2 thinner than those of XMM-Newton) and still have very good image quality up to 80 keV; iii) the development of an integration process that allows us to integrate these very thin mirrors maintaining their intrinsic good image quality. The Phase A study has shown that we can fabricate the mandrels with the needed quality and that we have developed a valid integration process. The shells that we have produced so far have a quite good image quality, e.g. HEW <~30 arcsec at 30 keV, and effective area. However, we still need to make some improvements to reach the requirements. We will briefly present these results and discuss the possible improvements that we will investigate during phase B.Comment: 6 pages, 3 figures, invited talk at the conference "2nd International Simbol-X Symposium", Paris, 2-5 december, 200

Thin-shell plastic lenses for space and laboratory applications

We have identified an inexpensive, readily available, mechanically stable, extremely smooth, elastic, and mechanically uniform plastic suitable for thin film X-ray optics. Polyethylene terephthalate (PET) is easily deformed without losing its elastic properties or surface smoothness. Most important, PET can be coated with mono- or multilayers that reflect X-rays at grazing incidence. We have used these properties to produce X-ray optics made either as a concentric nest of cylinders or as a spiral. We have produced accurately formed shells in precisely machined vacuum mandresl or used a pin and wheel structure to form a continuously wound spiral. The wide range of medical, industrial and scientific applications for our technology includes: a monochromatic X-ray collimater for medical diagnostics, a relay optic to transport an X-ray beam from the target in a scanning electron microscop0e to a lithium-drifted silicon and microcalorimeter detectors and a satellite mounted telescope to collect celestial X-rays. A wide variety of mono- and multilayer coatings allow X-rays up to ~100 keV to be reflected. Our paper presents data from a variety of diagnostic measurements on the properties of the PET foil and imaging results form single- and multi-shell lenses

Postępowanie w niewydolności serca u osób starszych

Wstęp: Celem pracy był przegląd aktualnie dost&#234;pnej wiedzy dotyczącej objawów oraz cech klinicznych i post&#234;powania w niewydolności serca (HF) u osób starszych. Metody: Autorzy dokładnie przeszukali kilka źródeł informacji opartych na dowodach naukowych, obejmujących Cochrane Database of Systemic Reviews, Clinical Evidence, wytyczne oparte na dowodach naukowych z National Guidelines Clearinghouse, zaś w bazie MEDLINE sprawdzili takie terminy, jak "niewydolność serca", "osoby starsze" oraz "postępowanie". Wyniki: Różne cechy związane z procesem starzenia mogą predysponowa&#230; osoby starsze do HF i upośledzać ich zdolność do reakcji na uszkodzenie. Inną cechą charakterystyczną u starszych pacjentów jest rosnąca częstość występowania wielu towarzyszących chorób przewlekłych i zespołów geriatrycznych, które mogą wikłać obraz kliniczny i rozwój HF. Kryteria diagnostyczne nie zmieniają się u osób starszych, mimo że rozpoznanie może stanowić wyzwanie z powodu często atypowych objawów i manifestacji klinicznej, a choroby towarzyszące mogą naśladować lub wikłać obraz kliniczny. Farmakoterapia nie różni się znacząco od tej zalecanej u młodszych pacjentów i w dużym stopniu pozostaje empiryczna, ponieważ zwykle wyklucza się osoby starsze oraz osoby z chorobami współistniejącymi z prób klinicznych. Programy postępowania mogą potencjalnie przyczynią się do zmniejszenia chorobowości i śmiertelności pacjentów z HF. Wnioski: Niewydolność serca jest najczęstszą przyczyną hospitalizacji i rehospitalizacji osób starszych. Wykazuje ona szczególne cechy u starszych pacjentów i jest zwykle powikłana chorobami towarzyszącymi, stanowiąc na całym świecie ogromne obciążenie finansowe. Pomimo to osoby starsze zwykle wykluczano z prób klinicznych i dlatego postępowanie w dużym stopniu pozostaje empiryczne i oparte na dowodach naukowych dotyczących osób z młodszych grup wiekowych

The future of Cybersecurity in Italy: Strategic focus area

This volume has been created as a continuation of the previous one, with the aim of outlining a set of focus areas and actions that the Italian Nation research community considers essential. The book touches many aspects of cyber security, ranging from the definition of the infrastructure and controls needed to organize cyberdefence to the actions and technologies to be developed to be better protected, from the identification of the main technologies to be defended to the proposal of a set of horizontal actions for training, awareness raising, and risk management