Experimental Assessment of Linear Sampling and Factorization Methods for Microwave Imaging of Concealed Targets

Shape reconstruction methods are particularly well suited for imaging of concealed targets. Yet, these methods are rarely employed in real nondestructive testing applications, since they generally require the electrical parameters of outer object as a priori knowledge. In this regard, we propose an approach to relieve two well known shape reconstruction algorithms, which are the linear sampling and the factorization methods, from the requirement of the a priori knowledge on electrical parameters of the surrounding medium. The idea behind this paper is that if a measurement of the reference medium (a medium which can approximate the material, except the inclusion) can be supplied to these methods, reconstructions with very high qualities can be obtained even when there is no information about the electrical parameters of the surrounding medium. Taking the advantage of this idea, we consider that it is possible to use shape reconstruction methods in buried object detection. To this end, we perform several experiments inside an anechoic chamber to verify the approach against real measurements. Accuracy and stability of the obtained results show that both the linear sampling and the factorization methods can be quite useful for various buried obstacle imaging problems

Effect of Calcined Colemanite Addition on the Rheological Behaviour of Porcelain Suspension

A standard composition for hard porcelain production was prepared by mixing 50 wt% kaolin, 25 wt% potassium feldspar and 25 wt% quartz. Calcined colemanite powders were added to the porcelain formulation by replacing the potassium feldspar up to 5 wt% to explore its effect on the rheological behaviour of porcelain slip casting. A rheological study has been carried out in order to optimize the processing of the slip casting by using a rotational stress-controlled rheometer. The measurements were performed at constant temperature (25°C) using a parallel plate configuration. Sweep measurements were then conducted in the shear rates ranging from about 0.1-1000 s¯¹. The stability of the suspensions with ammonium polyacrylate (Darvan 821A) was determined in order to select the suitable dispersant amount. In order to achieve casting of acceptable characteristics on a plaster of Paris mould, the slurry should have the appropriate thixotropic or shear-thinning behaviours. Therefore, the same favourable thixotropic behaviour of slurries of different amount of calcined colemanite powders, the solid contents of the slurries have been optimised

Decreased serum orexin A levels in drug-naive children with attention deficit and hyperactivity disorder

Attention deficit/hyperactivity disorder (ADHD) is one of the most common psychiatric disorders of childhood and characterized by inattention, hyperactivity, and impulsivity. ADHD is a neurodevelopmental disorder, and its etiology has not yet been determined precisely. Orexin A is thought to play an important role in different forms of learning, memory, and attention. Despite its importance in attention and learning, no study has investigated serum orexin levels in patients with ADHD. In the present study, we aimed to compare serum orexigenic neuropeptides such as orexin A and orexin B, neuropeptide Y, and ghrelin between drug naive children with ADHD and healthy children. Fifty-six drug-naive children with ADHD and 40 healthy controls were enrolled in the study. After comparison of serum orexin A and orexin B, neuropeptide Y, and ghrelin, we found that serum orexin A levels were significantly lower in the ADHD group (p = 0.001). Furthermore, serum orexin A levels were compared between ADHD subgroups. Orexin A levels were significantly lower in the inattentive subtype compared with the hyperactive subtype and combined subtype (p = 0.009). Our results indicate that orexin A might be a neurobiological etiological factor in ADHD, particularly associated with attention symptoms. The present study is the first to demonstrate decreased serum orexin A levels in drug-naive children with ADHD. Further studies are needed to confirm our results and to show the effects of treatments involving orexin A in patients with ADHD. © 2019, Fondazione Società Italiana di Neurologia.NKUBAP.02Funding The present study was supported by Tekirdağ Namık Kemal University Scientific Research Community (Grant Number: NKUBAP.02.GA.17.09