878 research outputs found
Biofilm formation and Biocide resistance in Listeria
La presente attività di ricerca ha avuto come oggetto di studio la formazione di biofilm in condizioni dinamiche: per raggiungere tale obiettivo, è stato costruito un idoneo apparato che permettesse di ottenere una valutazione quantitativa sia delle cellule presenti nella soluzione di crescita sia di quelle adese su tre materiali di prova(acciaio inossidabile, PET e rame).
Oltre ad esprimere una valutazione dell’adesione batterica alle superfici, si è proceduto ad indagare sui possibili parametri sperimentali che potessero influenzare la formazione di biofilmdi Listeria su superfici abiotiche. Allo stesso tempo l’efficacia battericida di alcuni biocidi è stata valutata sulle cellule planctoniche così come su biofilm batterici sviluppati su superfici abiotiche.
Il ruolo del sistema di quorum sensing basato su luxS nella formazione di biofilm batterici: un ceppo di L. innocua con buone capacità adesive è stato confrontato con il suo ceppo deficiente di luxS per la sua suscettibilità ad agenti biocidi così come per la sua capacità di adesione superficiale
L’effetto della precendentemente menzionata inattivazione genetica sulla cinetica di crescita batterica e, quindi, sull’efficienza metabolica complessiva è stata esaminate mediante lo strumento BioscreenC. L’effetto inibitorio di due composti polifenolici è stato valutato sul ceppo deficiente di luxS così come sul ceppo originale.The current research activity was focused on biofilm formation in dynamic conditions. A suitable device was thus constructed, in order to have a quantitative evaluation of the cells freely suspended in the flowing nutrient solution used as well as the sessile cells which adhered on the three tested surfaces (stainless steel, polyethylene therephthalate and copper).
During this project, other than of a quantitative assessment of bacterial adhesion, we investigated also on the parameters which could affect significantly the biofilm formation of Listeria on abiotic surfaces. At the same time antimicrobial efficiency of selected biocides was investigated on planktonic cells as well as on bacterial biofilms grown on abiotic surfaces.
The role of luxS-based quorum sensing system in the biofilm development process was evaluated: a luxS-null mutant of an adhesive strain of L. innocua was obtained through Campbell-like genetic inactivation and then evaluated for its sensitivity to biocidal agents and adhesion to surfaces, in comparison with its parental strains. Furthermore the effect of genetic inactivation on bacterial growth kinetic and thus on overall bacterial metabolic efficiency was assessed through the apparatus of BioscreenC. Finally two polyphenolic compounds were investigated for their inhibitory effect on Listeria
Generalized Analysis and Unified Design of EM Skins
A generalized formulation is derived for the analysis of the field
manipulation properties of electromagnetic skins (EMSs) in the working regimes
of interest for wireless communications. Based on such a theoretical framework,
a unified method for the design of anomalous-reflecting and focusing EMSs is
presented. Representative results, from a wide set of numerical experiments,
are reported and validated with full-wave HFSS simulations to give the
interested readers some insights on the accuracy, the effectiveness, and the
computational efficiency of the proposed analysis/synthesis tools
Features and Potentialities of Static Passive EM Skins for NLOS Specular Wireless Links
The ability of passive flat patterned electromagnetic skins (EMSs) to
overcome the asymptotic limit of the total path attenuation (TPA) of flat
metallic reflectors of arbitrary size in non-line-of-sight (NLOS) specular
wireless links is assessed. Closed-form expressions for the achievable TPA in
EMS-powered NLOS links as well as the condition on the panel size of
EMS-screens to improve the performance of flat passive conductive screens
(PCSs) with the same aperture are derived and numerically validated by
considering different incidence angles, screen apertures, transmitter/receiver
distances, antenna gains, meta-atom geometries, and carrier frequencies
Seismic amplification in presence of topography and their consequences for ground motion predictions and seismic code for building: the case of Italy
This work talks about the relevance of topographic effects in local site response evaluations. In this way some
Italian test sites, characterized by the presence of a seismic station installed at the top of a steep topography,
were investigated. The influence of the morphology was evaluated, at first, by performing rotational spectral
ratio analyses, both in term of single station measurements (i.e. horizontal to vertical spectral ratio, HVSR) and,
if possible, also considering reference sites (i.e.standard spectral ratio, SSR) and, at second, evaluating the
residuals (logarithmic difference between observed and predicted data) estimated in term of acceleration
response spectra for period up to 2.0 s. In this way, the ground motion prediction equations calibrated for Italy
by Bindi et al., 2010 were considered. Finally, in correspondence of two selected topographies with seismic
stations installed both at the top and at the base, the design elastic acceleration response spectra as proposed by
the Italian seismic regulations (NTC, 2008) were evaluated in terms of shape and amplitude
Velocity profile report at the seismic station IV.MODE - MODENA
In this report, we present the geophysical measurements and the results obtained in the framework of the 2018 agreement between INGV and DPC, called Allegato B2: Obiettivo 1 - TASK B: Caratterizzazione siti accelerometrici (Coord. G. Cultrera, F. Pacor). In this report, the results for station IV.MODE, belonging to the Italian National Seismic Network (RSN-INGV), are presented.
Geophysical measurements consist in a 2D array in passive configuration that provide results in terms of dispersion curves of surface waves. These curves are inverted to obtain a shear-wave velocity (Vs) profile that is suitable for assigning the soil class according to the current Italian seismic code (NTC 2018) and the current Eurocode (EC8)
Learned Global Optimization for Inverse Scattering Problems -- Matching Global Search with Computational Efficiency
The computationally-efficient solution of fully non-linear microwave inverse
scattering problems (ISPs) is addressed. An innovative System-by-Design (SbD)
based method is proposed to enable, for the first time to the best of the
authors knowledge, an effective, robust, and time-efficient exploitation of an
evolutionary algorithm (EA) to perform the global minimization of the
data-mismatch cost function. According to the SbD paradigm as suitably applied
to ISPs, the proposed approach founds on (i) a smart re-formulation of the ISP
based on the definition of a minimum-dimensionality and representative set of
degrees-of-freedom (DoFs) and on (ii) the artificial-intelligence (AI)-driven
integration of a customized global search technique with a digital twin (DT)
predictor based on the Gaussian Process (GP) theory. Representative numerical
and experimental results are provided to assess the effectiveness and the
efficiency of the proposed approach also in comparison with competitive
state-of-the-art inversion techniques
Towards Real-World Indoor Smart Electromagnetic Environments -- A Large-Scale Experimental Demonstration
To the best of the authors' knowledge, this work presents the first
large-scale indoor experimental assessment of an implementation of the emerging
Smart ElectroMagnetic Environment (SEME) paradigm, which is based on the
deployment of static-passive EM skins (SP-EMSs) to enhance the coverage in a 5
[GHz] Wi-Fi network. Unlike standard (laboratory-based) validations reported in
the state-of-the-art (SoA) literature, the scenario at hand mimics a realistic
indoor environment to replicate as close as possible the user experience when
using commodity devices. Representative results from the experimental field
trials are re-ported to confirm the performance predictions arising from the
numerical studies and the tolerance analyses carried out with a commercial
ray-tracing (RT) tool. Besides experimentally validating the SEME idea, this
study is also aimed at (roughly) quantifying the economic advantage of a SEME
implementation, relying on simple-manufacturing/low-cost field manipulating
devices without any additional biasing circuitry, with respect to standard
approaches that imply the densification of the active radiating sources
A Physics-Driven AI Approach for Microwave Imaging of Breast Tumors
In this paper, an innovative microwave imaging (MI) approach for breast tumor
diagnosis is proposed that employs a differential formulation of the inverse
scattering problem (ISP) at hand to exploit arbitrary-fidelity priors on the
inhomogeneous reference/healthy tissues. The quantitative imaging of the
unknown tumor is then rephrased into a global optimization problem, which is
efficiently solved with an ad-hoc physics-driven artificial intelligence (AI)
strategy inspired by the concepts and guidelines of the System-by-Design (SbD)
paradigm. The effectiveness, the robustness, the reliability, and the
efficiency of the proposed method are assessed against both synthetic and
experimental data
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