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A reaction-diffusion model for Mycobacterium tuberculosis infection
Authors:
C. Accarino,
R. Accarino,
F. Capone,
R. De Luca,
L. Fiorentino,
G. Massa
Abstract:
This paper aims to investigate a reaction-diffusion model which describes in-host infection for Mycobacterium tuberculosis (Mtb) allowing random motion (i.e. linear diffusion) and chemotaxis (i.e. non-linear diffusion) of macrophages and bacteria populations. In particular, chemotaxis-driven aggregation of macrophages plays a fundamental role in the development of the Mtb infection and the product…
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This paper aims to investigate a reaction-diffusion model which describes in-host infection for Mycobacterium tuberculosis (Mtb) allowing random motion (i.e. linear diffusion) and chemotaxis (i.e. non-linear diffusion) of macrophages and bacteria populations. In particular, chemotaxis-driven aggregation of macrophages plays a fundamental role in the development of the Mtb infection and the production of chemokine - located in the infection site - represents an attractant for the uninfected macrophages, therefore we consider chemotaxis between infected macrophages and uninfected macrophages. The linear stability of the endemic equilibria is investigated. In particular, by looking for conditions guaranteeing that an equilibrium, stable in the absence of diffusion, becomes unstable when diffusion is allowed, the formation of Turing patterns - that biologically represent the formation of granuloma initiated by the immune cells - is investigated. The weakly nonlinear analysis is performed to deeply explore the patterns amplitude. Furthermore, via numerical simulations, the formation of Turing patterns is analysed.
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Submitted 14 October, 2024;
originally announced October 2024.
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Compressibility effect on Darcy porous convection
Authors:
Giuseppe Arnone,
Florinda Capone,
Roberta De Luca,
Giuliana Massa
Abstract:
Perfectly incompressible materials do not exist in nature but are a useful approximation of several media which can be deformed in non-isothermal processes but undergo very small volume variation. In this paper the linear analysis of the Darcy-Bénard problem is performed in the class of extended-quasi-thermal-incompressible fluids, introducing a factor $β$ which describes the compressibility of th…
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Perfectly incompressible materials do not exist in nature but are a useful approximation of several media which can be deformed in non-isothermal processes but undergo very small volume variation. In this paper the linear analysis of the Darcy-Bénard problem is performed in the class of extended-quasi-thermal-incompressible fluids, introducing a factor $β$ which describes the compressibility of the fluid and plays an essential role in the instability results. In particular, in the Oberbeck-Boussinesq approximation, a more realistic constitutive equation for the fluid density is employed in order to obtain more thermodynamic consistent instability results. Via linear instability analysis of the conduction solution, the critical Rayleigh-Darcy number for the onset of convection is determined as a function of a dimensionless parameter $\widehatβ$ proportional to the compressibility factor $β$, proving that $\widehatβ$ enhances the onset of convective motions.
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Submitted 14 October, 2022;
originally announced October 2022.
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The combined effects of rotation and anisotropy on double diffusive bi-disperse convection
Authors:
Florinda Capone,
Roberta De Luca,
Giuliana Massa
Abstract:
In the present paper double-diffusive convection, taking into account Coriolis effects, in a horizontal layer of Brinkman-anisotropic bi-disperse porous medium is analysed. Via linear instability analysis, we found that convection can set in through stationary or oscillatory motions and the critical Rayleigh numbers for the onset of stationary secondary flow (steady convection) and overstability (…
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In the present paper double-diffusive convection, taking into account Coriolis effects, in a horizontal layer of Brinkman-anisotropic bi-disperse porous medium is analysed. Via linear instability analysis, we found that convection can set in through stationary or oscillatory motions and the critical Rayleigh numbers for the onset of stationary secondary flow (steady convection) and overstability (oscillatory convection) are determined.
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Submitted 9 September, 2022;
originally announced September 2022.
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Variants in managing supply chains on distributed ledgers
Authors:
Paolo Bottoni,
Claudio Di Ciccio,
Remo Pareschi,
Nicola Gessa,
Gilda Massa
Abstract:
Smart contracts show a high potential for ensuring that Supply Chain Management strategies make a qualitative leap toward higher levels of optimality, not only in terms of efficiency and profitability but also in the aggregation of skills aimed at creating the best products and services to bring to the market. In this article, we illustrate an architecture that employs smart contracts to implement…
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Smart contracts show a high potential for ensuring that Supply Chain Management strategies make a qualitative leap toward higher levels of optimality, not only in terms of efficiency and profitability but also in the aggregation of skills aimed at creating the best products and services to bring to the market. In this article, we illustrate an architecture that employs smart contracts to implement various algorithmic versions of the Income Sharing principle between companies participating in a supply chain. We implement our approach on Hyperledger Fabric, the most widespread platform for private and consortium distributed ledgers, and discuss its suitability to our purposes by comparing this design choice with the alternative given by public blockchains, with particular attention to Ethereum.
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Submitted 7 April, 2022;
originally announced May 2022.
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The effects of Vadasz term, anisotropy and rotation on bi-disperse convection
Authors:
Florinda Capone,
Giuliana Massa
Abstract:
The onset of thermal convection in a uniformly rotating and horizontally isotropic bi-disperse porous medium, taking into account the Vadasz term, is investigated. Via linear instability analysis, it has been proven that the Vadasz term allows the onset of convection via an oscillatory state but does not affect convection via a stationary motion.
The onset of thermal convection in a uniformly rotating and horizontally isotropic bi-disperse porous medium, taking into account the Vadasz term, is investigated. Via linear instability analysis, it has been proven that the Vadasz term allows the onset of convection via an oscillatory state but does not affect convection via a stationary motion.
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Submitted 8 March, 2021;
originally announced March 2021.
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A multivariate spatial interpolation of airborne γ-ray data using the geological constraints
Authors:
E. Guastaldi,
M. Baldoncini,
G. P. Bezzon,
C. Broggini,
G. P. Buso,
A. Caciolli,
Carmignani L.,
I. Callegari,
T. Colonna,
K. Dule,
G. Fiorentini,
M. Kaçeli Xhixha,
F. Mantovani,
G. Massa,
R. Menegazzo,
L. Mou,
C. Rossi Alvarez,
V. Strati,
G. Xhixha,
A. Zanon
Abstract:
In this paper we present maps of K, eU, and eTh abundances of Elba Island (Italy) obtained with a multivariate spatial interpolation of airborne γ-ray data using the constraints of the geologic map. The radiometric measurements were performed by a module of four NaI(Tl) crystals of 16 L mounted on an autogyro. We applied the collocated cokriging (CCoK) as a multivariate estimation method for inter…
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In this paper we present maps of K, eU, and eTh abundances of Elba Island (Italy) obtained with a multivariate spatial interpolation of airborne γ-ray data using the constraints of the geologic map. The radiometric measurements were performed by a module of four NaI(Tl) crystals of 16 L mounted on an autogyro. We applied the collocated cokriging (CCoK) as a multivariate estimation method for interpolating the primary under-sampled airborne γ-ray data considering the well-sampled geological information as ancillary variables. A random number has been assigned to each of 73 geological formations identified in the geological map at scale 1:10,000. The non-dependency of the estimated results from the random numbering process has been tested for three distinct models. The experimental cross-semivariograms constructed for radioelement-geology couples show well-defined co-variability structures for both direct and crossed variograms. The high statistical correlations among K, eU, and eTh measurements are confirmed also by the same maximum distance of spatial autocorrelation. Combining the smoothing effects of probabilistic interpolator and the abrupt discontinuities of the geological map, the results show a distinct correlation between the geological formation and radioactivity content. The contour of Mt. Capanne pluton can be distinguished by high K, eU and eTh abundances, while different degrees of radioactivity content identify the tectonic units. A clear anomaly of high K content in the Mt. Calamita promontory confirms the presence of felsic dykes and hydrothermal veins not reported in our geological map. Although we assign a unique number to each geological formation, the method shows that the internal variability of the radiometric data is not biased by the multivariate interpolation.
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Submitted 20 June, 2013;
originally announced June 2013.
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The worldwide NORM production and a fully automated gamma-ray spectrometer for their characterization
Authors:
G. Xhixha,
GP. Bezzon,
C. Broggini,
GP. Buso,
A. Caciolli,
I. Callegari,
S. De Bianchi,
G. Fiorentini,
E. Guastaldi,
M. Kaçeli Xhixha,
F. Mantovani,
G. Massa,
R. Menegazzo,
L. Mou,
A. Pasquini,
C. Rossi Alvarez,
M. Shyti
Abstract:
Materials containing radionuclides of natural origin, which is modified by human made processes and being subject to regulation because of their radioactivity are known as NORM. We present a brief review of the main categories of non-nuclear industries together with the levels of activity concentration in feed raw materials, products and waste, including mechanisms of radioisotope enrichments. The…
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Materials containing radionuclides of natural origin, which is modified by human made processes and being subject to regulation because of their radioactivity are known as NORM. We present a brief review of the main categories of non-nuclear industries together with the levels of activity concentration in feed raw materials, products and waste, including mechanisms of radioisotope enrichments. The global management of NORM shows a high level of complexity, mainly due to different degrees of radioactivity enhancement and the huge amount of worldwide waste production. The future tendency of guidelines concerning environmental protection will require both a systematic monitoring based on the ever-increasing sampling and high performance of gamma ray spectroscopy. On the ground of these requirements a new low background fully automated high-resolution gamma-ray spectrometer MCA_Rad has been developed. The design of Pb and Cu shielding allowed to reach a background reduction of two order of magnitude with respect to laboratory radioactivity. A severe lowering of manpower cost is obtained through a fully automation system, which enables up to 24 samples to be measured without any human attendance. Two coupled HPGe detectors increase the detection efficiency, performing accurate measurements on sample volume (180 cc) with a reduction of sample transport cost of material. Details of the instrument calibration method are presented. MCA_Rad system can measure in less than one hour a typical NORM sample enriched in U and Th with some hundreds of Bq/kg, with an overall uncertainty less than 5%. Quality control of this method has been tested. Measurements of certified reference materials RGK-1, RGU-2 and RGTh-1 containing concentrations of K, U and Th comparable to NORM have been performed, resulting an overall relative discrepancy of 5% among central values within the reported uncertainty.
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Submitted 24 April, 2012;
originally announced April 2012.
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A new FSA approach for in situ $γ$-ray spectroscopy
Authors:
A. Caciolli,
M. Baldoncini,
G. P. Bezzon,
C. Broggini,
G. P. Buso,
I. Callegari,
T. Colonna,
G. Fiorentini,
E. Guastaldi,
F. Mantovani,
G. Massa,
R. Menegazzo,
L. Mou,
C. Rossi Alvarez,
M. Shyti,
A. Zanon,
G. Xhixha
Abstract:
An increasing demand of environmental radioactivity monitoring comes both from the scientific community and from the society. This requires accurate, reliable and fast response preferably from portable radiation detectors. Thanks to recent improvements in the technology, $γ$-spectroscopy with sodium iodide scintillators has been proved to be an excellent tool for in-situ measurements for the ident…
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An increasing demand of environmental radioactivity monitoring comes both from the scientific community and from the society. This requires accurate, reliable and fast response preferably from portable radiation detectors. Thanks to recent improvements in the technology, $γ$-spectroscopy with sodium iodide scintillators has been proved to be an excellent tool for in-situ measurements for the identification and quantitative determination of $γ$-ray emitting radioisotopes, reducing time and costs. Both for geological and civil purposes not only $^{40}$K, $^{238}$U, and $^{232}$Th have to be measured, but there is also a growing interest to determine the abundances of anthropic elements, like $^{137}$Cs and $^{131}$I, which are used to monitor the effect of nuclear accidents or other human activities.
The Full Spectrum Analysis (FSA) approach has been chosen to analyze the $γ$-spectra. The Non Negative Least Square (NNLS) and the energy calibration adjustment have been implemented in this method for the first time in order to correct the intrinsic problem related with the $χ^2$ minimization which could lead to artifacts and non physical results in the analysis.
A new calibration procedure has been developed for the FSA method by using in situ $γ$-spectra instead of calibration pad spectra. Finally, the new method has been validated by acquiring $γ$-spectra with a 10.16 cm x 10.16 cm sodium iodide detector in 80 different sites in the Ombrone basin, in Tuscany. The results from the FSA method have been compared with the laboratory measurements by using HPGe detectors on soil samples collected in the different sites, showing a satisfactory agreement between them. In particular, the $^{137}$Cs isotopes has been implemented in the analysis since it has been found not negligible during the in-situ measurements.
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Submitted 7 November, 2011;
originally announced November 2011.
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Undulation textures at the phase transitions of some alkyloxybenzoic acids
Authors:
A. Sparavigna,
A. Mello,
G. Massa
Abstract:
We observed undulated smectic textures for some compounds of the 4,n-alkyloxybenzoic (nOBAC) acid series, at transitions between the smectic and the isotropic phase and between the smectic and nematic phase. Studied compounds were 12OBAC, 16OBAC and a binary mixture of 12- and 16OBAC. The undulations are dressing a usual Schlieren texture. In the case of the binary mixture, an interesting finger…
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We observed undulated smectic textures for some compounds of the 4,n-alkyloxybenzoic (nOBAC) acid series, at transitions between the smectic and the isotropic phase and between the smectic and nematic phase. Studied compounds were 12OBAC, 16OBAC and a binary mixture of 12- and 16OBAC. The undulations are dressing a usual Schlieren texture. In the case of the binary mixture, an interesting fingerprint pattern is observed too.
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Submitted 3 March, 2009; v1 submitted 11 December, 2008;
originally announced December 2008.