Liquid Dynamics in a Horizontal Capillary: Extended Similarity Analysis

Abstract The topic of this study is an extended similarity analysis for a one-dimensional model of liquid dynamics in a horizontal capillary. The bulk liquid is assumed to be initially at rest and is put into motion by capillarity, that is the only driving force acting on it. Besides the smaller is the capillary radius the steeper becomes the initial transitory of the meniscus location derivative, and as a consequence the numerical solution to a prescribed accuracy becomes harder to achieve. Here, we show how an extended scaling invariance can be used to define a family of solutions from a computed one. The similarity transformation involves both geometric and physical feature of the model. As a result, density, surface tension, viscosity, and capillary radius are modified within the required invariance. Within our approach a target problem of practical interest can be solved numerically by solving a simpler transformed test case. The reference solution should be as accurate as possible, and therefore we suggest to use for it an adaptive numerical method. This study may be seen as a complement to the adaptive numerical solution of the considered initial value problems

Role for serotonin2A (5-HT2A) and 2C (5-HT2C) receptors in experimental absence seizures

Absence seizures (ASs) are the hallmark of childhood/juvenile absence epilepsy. Monotherapy with first-line anti-absence drugs only controls ASs in 50% of patients, indicating the need for novel therapeutic targets. Since serotonin family-2 receptors (5-HT2Rs) are known to modulate neuronal activity in the cortico-thalamo-cortical loop, the main network involved in AS generation, we investigated the effect of selective 5-HT2AR and 5-HT2CR ligands on ASs in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well established polygenic rat model of these non-convulsive seizures. GAERS rats were implanted with fronto-parietal EEG electrodes under general anesthesia, and their ASs were later recorded under freely moving conditions before and after intraperitoneal administration of various 5-HT2AR and 5-HT2CR ligands. The 5-HT2A agonist TCB-2 dose-dependently decreased the total time spent in ASs, an effect that was blocked by the selective 5-HT2A antagonist MDL11,939. Both MDL11,939 and another selective 5-HT2A antagonist (M100,907) increased the length of individual seizures when injected alone. The 5-HT2C agonists lorcaserin and CP-809,101 dose-dependently suppressed ASs, an effect blocked by the selective 5-HT2C antagonist SB 242984. In summary, 5-HT2ARs and 5-HT2CRs negatively control the expression of experimental ASs, indicating that selective agonists at these 5-HT2R subtypes might be potential novel anti-absence drugs

One-dimensional mathematical and numerical modeling of liquid dynamics in a horizontal capillary

Abstract. This paper is concerned with a mathematical and numerical study of liquid dynamics in a horizontal capillary. We derive a two-liquids model for the prediction of capillary dynamics. This model takes into account the effects of real phenomena: like the outside flow action, or the entrapped gas inside a closed-end capillary. Moreover, the limitations of the one-dimensional model are clearly indicated. Finally, we report on several tests of interest: an academic test case that can be used to check available numerical methods, a test for decreasing values of the capillary radius, a simulation concerning a closed-end capillary, and two test cases for two liquids flow. In order to study the introduced mathematical model, our main tool, is a reliable one-step adaptive numerical approach based on a one-step one-method strategy

Probability of Detection for Penetrant Testing in Industrial Environment

Abstract Introduced at the end of 60's by NASA, Probability of Detection (PoD) is becoming more and more one of the main approach in order to assess, quantitatively, the general detection capabilities of a Non Destructive Inspection process. In spite of its importance, PoD can be elaborated in a variety of ways and can lead to some misinterpretations. Alenia Aeronautica assessed a specific approach for liquid penetrant inspection that is strictly connected to the estimation of the inspection sensitivity and it can be aimed at various targets, such as: inspection procedure validation, evaluation of personnel proficiency, comparative analysis of penetrant inspection processing materials, equipment and procedures, and evaluation of automated inspection systems. To this purpose, PoD is conceived as the probability, at a fixed confidence level, to detect a discontinuity belonging to a predefined class. Experimental PoD curves are obtained by processing metallic samples with defects generated and developed under controlled conditions

Dopaminergic modulation of tonic but not phasic GABAA-receptor-mediated current in the ventrobasal thalamus of Wistar and GAERS rats

Activation of GABAA receptors by GABA causes phasic and tonic conductances in different brain areas. In the ventrobasal (VB) thalamus, tonic inhibition originates from GABA acting on extrasynaptic receptors. Here we show that dopamine (DA), the D2-like agonist quinpirole and the selective D4R agonist PD-168,077 decrease the magnitude of the tonic GABAA current while D1-like agonist SKF39383 lacks any significant effects in VB neurons of Wistar rats. On the other hand, DA and D1/D2 receptor activation does not alter phasic GABAA conductance. As we previously reported that an increased tonic GABAA current in VB neurons is critical for absence seizure generation, we also investigated whether D2–D4 receptor activation is capable of normalizing this aberrant conductance in genetic absence epilepsy rats from Strasbourg (GAERS). Quinpirole and PD-168,077 selectively reduces tonic GABAA current as in normal rats. Therefore, it is conceivable that some DA anti-absence effects occur via modulation of tonic GABAA current in the VB

Extrasynaptic GABAA receptors : their function in the CNS and Implications for disease

γ-Aminobutyric acid type A (GABAA) receptors (GABAARs), the main inhibitory neurotransmitter-gated ion channels in the central nervous system, are finely tuned by other neurotransmitters and endogenous ligands. The regulation of synaptic GABAARs (sGABAARs) by G protein-coupled receptors (GPCRs) has been well characterized and is known to occur either through the conventional activation of second-messenger signalling cascades by G proteins or directly by protein–protein coupling. In contrast, research on the modulation of extrasynaptic GABAAR (eGABAARs) is still in its infancy and it remains to be determined whether both of the above mechanisms are capable of controlling eGABAAR function. In this chapter, we summarize the available literature on eGABAAR modulation by GPCRs, including GABAB, serotonin (5-HT), dopamine (DA), noradrenaline (NA) and metabotropic glutamate (mGlu) receptors. Although at present these GPCRs-eGABAARs cross-talks have been investigated in a limited number of brain areas (i.e., thalamus, cerebellum, hippocampus, striatum), it is already evident that eGABAARs show a nucleus- and neuronal type-selective regulation by GPCRs that differs from that of sGABAARs. This distinct regulation of eGABAARs versus sGABAARs by GPCRs provides mechanisms for receptor adaptation in response to a variety of physiological stimuli and under different pathophysiological conditions. Further research will advance our understanding of eGABAAR and GPCR signalling and offer novel targets for the treatment of many neurological and neuropsychiatric disorders where abnormalities in eGABAAR have been suggested to exist.peer-reviewe