Non-Destructive Characterization of Magnetic Polymeric Scaffolds using Terahertz Time-of-Flight Imaging

Magnetic Scaffolds MagS are 3D composite materials, in which magnetic nanoparticles (MNPs) are used to load a polymeric matrix. Due to their wide use in various medical applications, there is an increasing demand of advanced techniques for non-destructive quality assessment procedures aimed at verifying the absence of defects and, more generally, dedicated to the characterization of MagS. In this framework, the use of TeraHertz (THz) waves for the non-destructive characterization of multifunctional scaffolds represents an open challenge for the scientific community. This paper deals with an approach for the characterization of MagS by means of a THz time-domain system used in reflection mode. THz analyses are performed on poly($\epsilon$ - capprolactone) (PCL) scaffolds magnetized with iron oxide (Fe $_{3}$ O$_{4}$) MNPs through a drop-casting deposition and tuned to obtain different distributions of MNP in the biomaterial. The proposed data processing approach allows a quantitative characterization MagS, in terms of their (estimated) thickness and refractive index. Moreover, the proposed procedure allows to identify the areas of the scaffold wherein MNP are mainly concentrated and thus, it gives us information about MNP spatial distribution

Preliminary In-Line Microwave Imaging Experimental Assessment for Food Contamination Monitoring

Food producers must deal with contaminants (wood, plastic, glass) inside packaged products that could lead to customer dissatisfaction. The assessed technologies fail to detect some of these contaminants, leading to the need for new technologies with different signal qualities, such as microwave sensing. This paper presents a preliminary result of a microwave imaging system designed for industrial applications. The measurement system was designed for and works on an industrial conveyor belt where packaged products are scanned. The scanned signals are processed to obtain an accurate 3D image of the size and position of the contaminant inside the food package. In addition to the results, we describe the implemented system and some considerations on data acquisition

Cancellation of vorticity in steady-state non-isentropic flows of complex fluids

In steady-state non-isentropic flows of perfect fluids there is always thermodynamic generation of vorticity when the difference between the product of the temperature with the gradient of the entropy and the gradient of total enthalpy is different from zero. We note that this property does not hold in general for complex fluids for which the prominent influence of the material substructure on the gross motion may cancel the thermodynamic vorticity. We indicate the explicit condition for this cancellation (topological transition from vortex sheet to shear flow) for general complex fluids described by coarse-grained order parameters and extended forms of Ginzburg-Landau energies. As a prominent sample case we treat first Korteweg's fluid, used commonly as a model of capillary motion or phase transitions characterized by diffused interfaces. Then we discuss general complex fluids. We show also that, when the entropy and the total enthalpy are constant throughout the flow, vorticity may be generated by the inhomogeneous character of the distribution of material substructures, and indicate the explicit condition for such a generation. We discuss also some aspects of unsteady motion and show that in two-dimensional flows of incompressible perfect complex fluids the vorticity is in general not conserved, due to a mechanism of transfer of energy between different levels.Comment: 12 page

Microwave imaging device prototype for brain stroke 3D monitoring

This paper summarizes the development and the experimental testing of a scanning device, in the microwave range, to monitor brain stroke. The device comprehends 4 main sections: a sensors helmet, a switching matrix, a data acquisition part, and a control/processing core. The sensors in the helmet are 22 custom-made flexible antennas working around 1 GHz, placed conformally to the upper head part. A first validation of the system consists in the detection of a target in the head region. Experimental testing is performed on a single-cavity head phantom, while the target is a balloon mimicking the stroke. The shape of the balloon and phantom are extracted from medical images, and tissues properties are emulated with liquids that resemble their dielectric properties. A differential measurement approach senses the field on the antennas in two different situations, and from their difference computes a 3-D image through a singular value decomposition of the discretized scattering operator obtained from an accurate numerical model. The results verify the capabilities of the system on detecting and monitoring stroke evolution

A low-complexity microwave scanner for cerebrovascular diseases monitoring

This work gathers the pathway from the design to the experimental testing of a microwave imaging prototype to monitor brain stroke in real-time conditions, approaching thus the electromagnetic inverse problem of retrieving a dielectric temporal variation within the head. To this end, it presents a low-complexity device consisting of twentytwo custom-made radiating elements working with a linear imaging algorithm based on distorted Born approximation and a truncated singular value decomposition, able to localize, identify and track the stroke evolution. The system is prototyped using a compact two-ports vector analyzer and electromechanical switching matrix. It is assessed experimentally via a mimicked hemorrhagic condition, demonstrating the system’s capabilities to follow up centimetric confined variations, retrieving 3-D maps of the studied cases in real-time

Broadband Electromagnetic Sensing for Food Quality Control: A Preliminary Experimental Study

Quality control is of great importance in food industry, both for the evaluation of product characteristics and to avoid the occurrence of foreign bodies contamination in packaged items. With respect to the inspections against possible contaminants inside the product, different technologies are currently adopted along production chain lines. However, the number of accidents involving low density objects remains very large. To overcome this limitation, the use of electromagnetic technologies has been recently proposed. In this work, the synergic use of terahertz and microwaves technologies is proposed, so to provide high resolution images and in-depth inspections of different scenarios, including low density materials. A focus study on sugar samples is considered, reporting both its broadband characterization at microwaves and preliminary terahertz imaging to evaluate the integrity of the packaging. Ongoing research is devoted to the development and validation of a microwave device for monitoring food products along the production line

Accuracy and limitations of the growth hormone (GH) releasing hormone-arginine retesting in young adults with childhood-onset GH deficiency

Background: Re-testing for GH secretion is needed to confirm the diagnosis of GH deficiency (GHD) after adult height achievement in childhood-onset GHD (COGHD). Aim: To define the cut-off of GH peak after retesting with GH-releasing hormone plus arginine (GHRHarg) in the diagnosis of permanent GHD in COGHD of different etiology. Patients and methods: Eighty-eight COGHD (median age 17.2 y), 29 idiopathic GHD (IGHD), 44 cancer survivors (TGHD) and 15 congenital GHD (CGHD) were enrolled in the study; 54 had isolated GHD (iGHD) and 34 had multiple pituitary hormone deficiencies (MPHD). All were tested with insulin tolerance test (ITT) and GHRHarg. IGHD with a GH response to ITT 656\ub5g/L were considered true negatives and served as the control group, and patients with a GH response <6\ub5g/L as true positives. Baseline IGF-I was also measured. The diagnostic accuracy of GHRHarg testing and of IGF-I SDS in patients with GHD of different etiologies was evaluated by ROC analysis. Results: Forty-six subjects with a GH peak to ITT 656\ub5g/L and 42 with GH peak <6 \ub5g/L showed a GH peak after GHRHarg between 8.8\u2013124\ub5g/L and 0.3\u201326.3\ub5g/L, respectively; 29 IGHD were true negatives, 42 were true positives and 17 with a high likelihood GHD showed a GH peak to ITT 656\ub5g/L. ROC analysis based on the etiology indicated the best diagnostic accuracy for peak GH cutoffs after GHRHarg of 25.3 \ub5g/L in CGHD, 15.7 in TGHD, and 13.8 in MPHD, and for IGF-1 SDS at 122.1 in CGHD, 121.5 in TGHD, and 121.9 in MPHD. Conclusions: Our findings indicate that the best cut-off for GH peak after retesting with GHRHarg changes according to the etiology of GHD during the transition age. Based on these results the diagnostic accuracy of GHRHarg remains questionable

Energy Release on the Surface of a Rapidly Rotating Neutron Star during Disk Accretion: A Thermodynamic Approach

The total energy E of a star as a function of its angular momentum J and mass M in the Newtonian theory: E = E(J, M) [in general relativity, the gravitational mass M of a star as a function of its angular momentum J and rest mass m, M = M(J, m)], is used to determine the remaining parameters (angular velocity, equatorial radius, chemical potential, etc.) in the case of rigid rotation. Expressions are derived for the energy release during accretion onto a cool (with constant entropy), rapidly rotating neutron star (NS) in the Newtonian theory and in general relativity. A separate analysis is performed for the cases where the NS equatorial radius is larger and smaller than the radius of the marginally stable orbit in the disk plane. An approximate formula is proposed for the NS equatorial radius for an arbitrary equation of state, which matches the exact one at J = 0.Comment: 12 pages, 0 figures (Astronomy Letters in press

Radical anti-realism and substructural logics

We first provide the outline of an argument in favour of a radical form of anti-realism premised on the need to comply with two principles, implicitness and immanence, when trying to frame assertability-conditions. It follows from the first principle that one ought to avoid explicit bounding of the length of computations, as is the case for some strict finitists, and look for structural weakening instead. In order to comply with the principle of immanence, one ought to take into account the difference between being able to recognize a proof when presented with one and being able to produce one and thus avoid the idealization of our cognitive capacities that arise within Hilbert-style calculi. We then explore the possibility of weakening structural rules in order to comply with radical anti-realist strictures