UHMWPE oxidation increases matrix metalloproteinase-2 (MMP-2) release in human fibroblast

MRC-5 human fibroblast were grown polystyrene plates, UHMWPE slices and UHMWPE slices oxidized in air in oven at 120 °C for 80 h. Cell proliferation and cytotoxicity were assessed after 24, 48, and 72 h. Control cells grown on polystyrene doubled their number after 72 h while both cell population grown on UHMWPE and oxidized UHMWPE showed a reduced proliferation rate. Both UHMWPE types seem to induce a cytostatic rather than a cytotoxic effect, in fact, no difference in the LDH release were observed between the three cell populations at 24, 48, and 72 h. Gelatinase activity was assessed in cell medium at every time point using gelatin zymography. Only gelatinase B (MMP-2) activity was present in MRC-5 conditioned medium. Oxidized UHMWPE induced a strong release of MMP-2 after 72 h compared to control and UHMWPE samples. The augmented MMP-2 release in the absence of a cytotoxic phenomenon suggests a possible role for UHMWPE oxidation in the MMPs stimulation observed in the periprosthetic tissues.     

Design of CMOS checkers with improved testability of bridging and transistor stuck-on faults

This work presents a design technique for CMOS static and dynamic checkers (to be used in self-checking circuits), that allows the detection of all internal single transistor stuck-on and bridging faults causing unacceptable degradations of the circuit dynamic performance (but not logical errors). Such a technique exploits simple voltage detector circuits to make sure that the intermediate faulty voltages inevitably produced by the faults of interest are always propagated at the checker output as logic errors.With the use of our technique, the main disadvantages of static checkers, so far preventing their use in practical applications, are overcome.The method has been applied to the particular case of two-rail (static as well as dynamic) checkers and its validity has been verified by means of electrical level simulations.     

Influence of annealing on the phase composition,transmission and resistivity of SnOx thin films

Undoped and antimony-doped tin oxide films were prepared by d.c. reactive ion sputtering in an argon atmosphere with oxygen partial pressures ranging from 0 to 50%. The films were annealed in air, nitrogen and a vacuum in the temperature range 570–750 K. The influence of thermal annealing on the structural properties, electrical resistance and optical transmittance is described.     

Increasing usability when interacting through screen readers

The application of appropriate Web site design and evaluation methods helps to ensure more usable and accessible Web sites. While in the literature guidelines and evaluation methods for accessibility and usability are given and discussed separately, we aim at identifying the relationships between these two concepts, in particular considering usability criteria for accessible Web sites. In this work, we propose a set of such criteria targeted to improving the navigability for a specific group of disabled users, i.e., vision-impaired people. The identification of the eighteen criteria suggested herein was performed through empirical feedback, by which potential issues were identified. Subsequently, a systematic method was developed on the basis of the analysis of potential solutions, resulting in a classification of the criteria according to usability aspects. Some example applications of the proposed criteria to three existing public administration Web sites are discussed.     

Agent communication and artificial institutions

In this paper we propose an application-independent model for the definition of artificial institutions that can be used to define open multi-agent systems. Such a model of institutional reality makes us able also to define an objective and external semantics of a commitment-based Agent Communication Language (ACL). In particular we propose to regard an ACL as a set of conventions to act on a fragment of institutional reality, defined in the context of an artificial institution. Another contribution of the work presented in this paper is an operational definition of norms, a crucial component of artificial institutions. In fact in open systems interacting agents might not conform to the specifications. We regard norms as event-driven rules that when are fired by events happening in the system create or cancel a set of commitments. An interesting aspect of our proposal is that both the definition of the ACL and the definition of norms are based on the same notion of commitment. Therefore an agent capable of reasoning on commitments can reason on the semantics of communicative acts and on the system of norms.     

Evaluating robustness in a two layer simulated robot architecture

Many two layer robot architectures have been proposed and implemented. While justification for the design can be well argued, how does one know it is really a good idea? In this paper, one describes a two layer architecture (reinforcement learning in the bottom layer and POMDP planning at the top) for a simulated robot and summarize a set of three experiments in which one evaluated the design. To address the many difficulties of evaluating robot architectures, one advocates an experimental approach in which design criteria are elucidated and then form the basis for the evaluation experiments. In our case, one tests the implementation for its reliability and generalization (our design criteria) by comparing our architecture to one in which a key component is substituted; in these experiments, one demonstrates significant performance gains on the design criteria for our architecture.     

Evaluation of the surface urban heat island effect in the city of Madrid by thermal remote sensing

The surface urban heat island (SUHI) effect is defined as the increased surface temperatures in urban areas in contrast to cooler surrounding rural areas. In this article, the evaluation of the SUHI effect in the city of Madrid (Spain) from thermal infrared (TIR) remote-sensing data is presented. The data were obtained from the framework of the Dual-use European Security IR Experiment (DESIREX) campaign that was carried out during June and July 2008 in Madrid. The campaign combined the collection of airborne hyperspectral and in situ measurements. Thirty spectral and spatial high-resolution images were acquired with the Airborne Hyperspectral Scanner (AHS) sensor in a 11, 21, and 4 h UTC scheme. The imagery was used to retrieve the SUHI effect by applying the temperature and emissivity separation (TES) algorithm. The results show a nocturnal SUHI effect with a highest value of 5 K. This maximum value agrees within 1 K with the highest value of the urban heat island (UHI) observed using air temperature data (AT). During the daytime, this situation is reversed and the city becomes a negative heat island.     

In situ surface temperature retrieval in a boreal forest under variable cloudiness conditions

Canopy temperature retrieval was one of the purposes during the Solar Induced FLuorescence EXperiment (SIFLEX‐2002) of the European Space Agency, carried out in a Finnish boreal forest. In this work, we describe the strategy used to determine this temperature from ground thermal infrared (TIR) data under skies with variable cloud cover. TIR radiance was measured by a CIMEL Electronique CE 312 radiometer. An analysis of the radiative transfer equation showed which terms were necessary to obtain accurate surface temperatures during the campaign. Atmospheric correction was considered negligible due to the small atmospheric path, but hemispheric downwelling sky radiance determination was needed for the emissivity correction. Since most days during the campaign the sky showed partial cloudiness, a methodology to estimate this last term was proposed, using continuous information of cloudiness amount and cloud height given by a weather station. These thermal data were used to analyse some correlations between canopy and air temperatures and plant‐activity‐related variables in the context of the SIFLEX‐2002 campaign.