P-RANSAC: An Integrity Monitoring Approach for GNSS Signal Degraded Scenario

Satellite navigation is critical in signal-degraded environments where signals are corrupted and GNSS systems do not guarantee an accurate and continuous positioning. In particular measurements in urban scenario are strongly affected by gross errors, degrading navigation solution; hence a quality check on the measurements, defined as RAIM, is important. Classical RAIM techniques work properly in case of single outlier but have to be modified to take into account the simultaneous presence of multiple outliers. This work is focused on the implementation of random sample consensus (RANSAC) algorithm, developed for computer vision tasks, in the GNSS context. This method is capable of detecting multiple satellite failures; it calculates position solutions based on subsets of four satellites and compares them with the pseudoranges of all the satellites not contributing to the solution. In this work, a modification to the original RANSAC method is proposed and an analysis of its performance is conducted, processing data collected in a static test

A Galileo IOV Assessment: Measurement and Position Domain

The European GNSS, Galileo, is currently in its In-Orbit Validation (IOV) phase where four satellites are finally available for computing the user position. In this phase, the analysis of the measurements and Position Velocity and Time (PVT) obtained from the IOV satellites can provide insight on the potentialities of the Galileo system. A methodology is suggested for the analysis of the Galileo IOV pseudorange and pseudorange rates collected from the E1 and E5 frequencies. Several days of data were collected and processed to determine figures of merits such as RMS and maximum errors of the Galileo observables. From the analysis, it emerges that Galileo is able to achieve better accuracy with respect to GPS. A thorough analysis of the PVT performance is also achieved using broadcast ephemerides. Galileo and GPS PVTs are compared under similar geometry conditions showing the potential of the Galileo system.JRC.G.5-Security technology assessmen

Identification of Walker Identity Using Smartphone Sensors: An Experiment Using Ensemble Learning

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Novel Antimicrobial Strategies to Prevent Biofilm Infections in Catheters after Radical Cystectomy: A Pilot Study

Catheter-associated infections in bladder cancer patients, following radical cystectomy or ureterocutaneostomy, are very frequent, and the development of antibiotic resistance poses great challenges for treating biofilm-based infections. Here, we characterized bacterial communities from catheters of patients who had undergone radical cystectomy for muscle-invasive bladder cancer. We evaluated the efficacy of conventional antibiotics, alone or combined with the human ApoB-derived antimicrobial peptide r(P)ApoBLAla, to treat ureteral catheter-colonizing bacterial communities on clinically isolated bacteria. Microbial communities adhering to indwelling catheters were collected during the patients' regular catheter change schedules (28 days) and extracted within 48 h. Living bacteria were characterized using selective media and biochemical assays. Biofilm growth and novel antimicrobial strategies were analyzed using confocal laser scanning microscopy. Statistical analyses confirmed the relevance of the biofilm reduction induced by conventional antibiotics (fosfomycin, ceftriaxone, ciprofloxacin, gentamicin, and tetracycline) and a well-characterized human antimicrobial peptide r(P)ApoBLAla (1:20 ratio, respectively). Catheters showed polymicrobial communities, with Enterobactericiae and Proteus isolates predominating. In all samples, we recorded a meaningful reduction in biofilms, in both biomass and thickness, upon treatment with the antimicrobial peptide r(P)ApoBLAla in combination with low concentrations of conventional antibiotics. The results suggest that combinations of conventional antibiotics and human antimicrobial peptides might synergistically counteract biofilm growth on ureteral catheters, suggesting novel avenues for preventing catheter-associated infections in patients who have undergone radical cystectomy and ureterocutaneostomy

Human Cryptic Host Defence Peptide {GVF}27 Exhibits Anti-Infective Properties against Biofilm Forming Members of the Burkholderia cepacia Complex

Therapeutic solutions to counter Burkholderia cepacia complex (Bcc) bacteria are challenging due to their intrinsically high level of antibiotic resistance. Bcc organisms display a variety of potential virulence factors, have a distinct lipopolysaccharide naturally implicated in antimicrobial resistance. and are able to form biofilms, which may further protect them from both host defence peptides (HDPs) and antibiotics. Here, we report the promising anti-biofilm and immunomodulatory activities of human HDP GVF27 on two of the most clinically relevant Bcc members, Burkholderia multivorans and Burkholderia cenocepacia. The effects of synthetic and labelled GVF27 were tested on B. cenocepacia and B. multivorans biofilms, at three different stages of formation, by confocal laser scanning microscopy (CLSM). Assays on bacterial cultures and on human monocytes challenged with B. cenocepacia LPS were also performed. GVF27 exerts, at different stages of formation, antibiofilm effects towards both Bcc strains, a significant propensity to function in combination with ciprofloxacin, a relevant affinity for LPSs isolated from B. cenocepacia as well as a good propensity to mitigate the release of pro-inflammatory cytokines in human cells pre-treated with the same endotoxin. Overall, all these findings contribute to the elucidation of the main features that a good therapeutic agent directed against these extremely leathery biofilm-forming bacteria should possess

A New Orbiting Deployable System for Small Satellite Observations for Ecology and Earth Observation

In this paper, we present several study cases focused on marine, oceanographic, and atmospheric environments, which would greatly benefit from the use of a deployable system for small satellite observations. As opposed to the large standard ones, small satellites have become an effective and affordable alternative access to space, owing to their lower costs, innovative design and technology, and higher revisiting times, when launched in a constellation configuration. One of the biggest challenges is created by the small satellite instrumentation working in the visible (VIS), infrared (IR), and microwave (MW) spectral ranges, for which the resolution of the acquired data depends on the physical dimension of the telescope and the antenna collecting the signal. In this respect, a deployable payload, fitting the limited size and mass imposed by the small satellite architecture, once unfolded in space, can reach performances similar to those of larger satellites. In this study, we show how ecology and Earth Observations can benefit from data acquired by small satellites, and how they can be further improved thanks to deployable payloads. We focus on DORA—Deployable Optics for Remote sensing Applications—in the VIS to TIR spectral range, and on a planned application in the MW spectral range, and we carry out a radiometric analysis to verify its performances for Earth Observation studies

Digital Surface Models for GNSS Mission Planning in Critical Environment

GNSS surveys performed in critical environments (e.g. the urban canyons) usually suffer for satellites lack due to obstacle such as building and vegetation. A GNSS mission planning software allows to estimate satellite visibility and DOP (Dilution Of Precision) values along a planned trajectory in order to establish the best laps of time to perform the survey. However, this estimation is not reliable in complex scenario as the surrounding environment morphology is not considered. A method to obtain a more reliable GNSS satellite visibility prediction is proposed. This method, in addition to the calculation of the position of the GNSS satellites by means of the orbital parameters, uses 3D DSM (Digital Surface Models) to get a more reliable mission plan. The temporal evolution of key parameters describing the GNSS constellation through a visibility georeferenced map are supplied, either for dynamic but also for static type of surveys

An EGNOS Based Navigation System for Highly Reliable Aircraft Automatic Landing

Highly precise navigation is the core technology required for many applications, such as automated aerial refueling (AAR), sea-based joint precision approach and landing systems (JPALS), station-keeping, unmanned aerial vehicles (UAV) swarming and formation flight and unmanned ground vehicles (UGV) convoys. Advances in the above mentioned technology are possible considering the future GNSS framework, given that adequate characterization of new GNSS devices are performed and that new algorithms are developed that fully exploits the functionalities made available by the future GNSS systems. In this paper both aspects are considered, with specific reference to the use of GPS/EGNOS for reliable fixed wing aircraft automatic landing applications. For what concern experimental characterization of the satellite based navigation system GPS/EGNOS, the main aim of the activity was to describe the broadcasted messages to enhance the navigation accuracy and integrity of the core GNSS-1 elements GPS and GLONASS, and to exploit how the data can be used to compute and analyze the performance in terms of Required Navigation Performance (RNP) parameters. The paper describes the algorithm implemented to process the broadcasted EGNOS SIS in order to obtain a position solution and integrity information compliant with RTCA DO229C. Moreover, the paper presents test procedures and experimental results that may be used as a design guideline for monitoring manufacturing compliance and, in certain cases, for obtaining formal DO229C certification of equipment design and manufacture. On the other hand, concerning the development of new algorithms for Guidance, Navigation & Control of fixed wing vehicles, that are already compatible with the future GNSS framework, it was initially considered a suite of navigation sensors with accuracy similar to the one obtainable by EGNOS. In order to overcome the effects due to an insufficient accuracy, the satellite measures can be in fact integrated with different sensor sources allowing a high precision navigation and an improvement of the integrity and reliability of navigation solutions. By means of an appropriate sensor suite, described in the next, and of a sensor fusion algorithm we obtained a high precision level in navigation measurements that, for instance, allows a high autonomous precision approach and landing. A very simple but effective sensor fusion algorithm based on the use of complementary filtering technique has been implemented. This algorithm uses the vehicle position and velocity vectors fed by GPS and the vehicle acceleration vector fed by AHRS. The filter is developed with the aim of trading off the advantages and drawbacks of both sensors: the AHRS has a larger band, a limited signal noise but it is affected by remarkable bias errors, vice versa the GPS. Therefore, it can be thought to integrate the accelerations from AHRS and to process them through a high-pass filter, obtaining the medium-high frequency component of the considered signals. The low frequency components can be obtained by a filtering stage of the GPS measures through a low-pass filter. A simple sum of the above two components gives the final estimation of position and speed. It is important to emphasize that, in both velocity and position measures estimation, the high-pass filter applied to AHRS measures and the low-pass filter applied to GPS measures must be “complementary”, in the sense that the sum of the transfer functions of the two filters must be equal to one. Moreover, some critical autonomous functionality, such as Autolanding, will utilize the GPS integrity signal in its decision-making logic for evaluating the key-decisions regarding the possible execution of an altitude recovery manoeuvre and, in case, also considering a degraded mode by changing the desired performances at touch down, with the aim to be still compatible with the current navigation system precision. In this way the integrity information provided by EGNOS is efficiently used for achieving a higher safety level during autonomous flight operations. The selected on-board software architecture is actually fully compliant to the use of EGNOS based GPS units, without requiring any upgrade and the proposed sensor fusion algorithms have been already developed being basically compatible with integrity information coming from the future GNSS sensors. Anyway, in the presented first phase of flight experiments, we used a coarse DGPS unit, because EGNOS is still in the testing phase. The next steps are to perform autonomous GN&C flight experiment with EGNOS constellation with a runway completely not instrumented. In the first part of the paper, concerning EGNOS system characterization, is presented an overview of EGNOS (chapter 2), are described the processing of the SBAS Signal-In-Space correction and integrity data and the related algorithm to estimate the integrity supplied by the system (chapter 3), the classes of equipment at which the test requirement are referred and the equipment performance and test procedure focusing on processing requirements and the validation performance assessment logic to assess the performance achievable with EGNOS (chapter 4). In its second part, describing the development of GNC algorithms already compatible with the future GNSS framework, the paper deals with the autolanding algorithms (chapter 5), the sensor fusion algorithms to achieve the desired navigation precision and the methodologies developed in order to safely manage the possible presence of sensor failures (chapter 6), the preliminary results of the real time validation with hardware in the loop simulation (chapter 7) and, finally, the algorithm performances achieved during the first experimental flights by using the CIRA experimental flying platform (chapter 8)

Fattori di controllo della fungistasi: il ruolo della sostanza organica e della microflora tellurica

Soilborne plant pathogens are among the most important limiting factors for the productivity of agro-ecosystems. Identifying reliable and effective control methods is crucial for efficient biological control. Soil fungistasis is the capability of soils to inhibit the germination and growth of soil-borne fungi in presence of optimal abiotic conditions. The first aim of this PhD thesis was to clarify the relationships between soil amendments with plant residues spanning a wide range of biochemical quality with soil fungistasis. Microcosms experiments were performed with 42 different plant residues and the effect on soil fungistasis was assessed by using four different fungi (Aspergillus niger, Botrytis cinerea, Pyrenochaeta lycoperici and Trichoderma harzianum). We measured soil respiration and soil enzymatic activity and compared classic litter proximate chemical analysis with 13C-CPMAS NMR spectroscopy to define plant residues biochemistry. Results showed that the quality of organic amendments is a major controlling factor of soil fungistasis. The dramatic relief of soil fungistasis when soil was amended with lignin poor, but labile carbon rich, substrates gives strong support to the competition-based hypothesis. The positive correlation between soil respiration and fungal growth further supports the competition hypothesis. Finally, 13C-CPMAS NMR results showed clear-cut relationships between soil fungistasis and the biochemical quality of plant residues, and provided a quantitative assessment of the time required for fungistasis restoration after organic materials application. The second aim of this work was to assess the effects of different soil amendment histories, in terms of amendment types and amounts, on fungistasis. The few studies concerning the history of soil amendment pointed out its effect on basic soil functions such as respiration, enzymatic activities, carbon and nitrogen mineralization. Previous studies demonstrated that soils with a long-term (i.e. months to years) application history of organic amendments, compared with unamended soils, have a higher and more active microbial biomass and enhanced enzymatic activities. It is not know however, because of the lack of experimental evidences, whether and how a story of organic amendments affects fungistasis. The aforementioned considerations about basic soil processes and soil amendment history drove the hypothesis to us that training a soil with organic carbon, by stimulating the activity of the resident microbial community can positively affect soil fungistasis. With this background, aim of this study was to assess the effects of different soil amendment histories on fungistasis in terms of amendment types and amounts. For this purpose microcosm experiments were performed by training a soil with different amounts and types of organic sources covering a wide range of biochemical qualities (glucose, alfalfa and wheat straw). Thereafter, the fungistasis response was assessed by using four different fungi (Aspergillus niger, Botrytis cinerea, Pyrenochaeta lycoperici and Trichoderma harzianum). Trained soils were characterized for microbial activity (respiration) and functional diversity by the BIOLOG EcoPlates™ method. Results showed that, irrespectively of fungal species and amendment types, frequent supplies of organic C reduce fungistasis relief (i.e. increase fungistasis resistance to organic matter pulse) as well as the time required for fungistasis restoration (i.e. increase fungistasis resilience). Moreover, the frequent addition of organic carbon as a result of the continuous supply of easily decomposable organic compounds enhance soil respiration and its specific catabolic capabilities. In conclusion, organic amendment applications create a soil functionally distinct from its not amended counterpart, with greatly enhanced fungistasis resistance and resilience. Finally, the third aim of this work was to provide the first monitor of soil fungistasis in the Campania Region. Soil quality, especially in the presence of reduced organic inputs, degrades in a few years with the following negative effects: the increased incidence of soil-borne pathogens, the traditional chemical methods loses its effectiveness for the development of strains resistant to fungicides, the efficiency of the fertilizer use is lowered, and the soil food webs become simplified. In order to mitigate these effects is necessary to test innovative farming techniques. In both biological and conventional agriculture, to the recovery of the quality of the soils, it has been proposed to use organic amendments. In this context, the aim of this work was to assess the level of fungistasis in different soils sampled in the Campania Region, from both agro-ecosystems and natural ecosystems. In general, we wanted to assess the combined effect of soil type and a different management on fungistasis. To this end, the analysis included a wide spectrum of types of soils to better understand the relationships between physico - chemical-microbiological characteristics of soils and their fungistatic activity. Since the quality of the soil depends on multiple factors, and the same fungistasis is dependent on several processes and properties of the soil system, in order to evaluate the power fungistatic of soils sampled and to differentiate them according to their ability to induce or less fungistasis and thus inhibit or slow the development of soil-borne fungi, it is necessary to measure a variety of parameters, chemical, physical, biological and microbiological processes. In this multidisciplinary study were compared 12 different soils from different ecosystems and collected in different geographical areas of the Campania Region. Each soil has been subjected to chemical, physical, microbiological, enzymatic analysis, fungistasis assessment with three fungi (Aspergillus niger, Botrytis cinerea and Trichoderma harzianum). The hypothesis to be tested was that soils with higher organic matter content and higher microbial activity showed higher levels of fungistasis. Contrary to the initial hypothesis there was no evidence correlation between microbial biomass and fungistasis, but for the metabolic profile of the telluric microorganisms. The monitoring showed that there are significant differences in the fungistatic power of the different soils, it allows us to classify soils on the basis of their ability to inhibit or slow the development of soil-borne fungi