Direct Numerical Simulation of natural, mixed and forced convection in liquid metals: selected results

Selected results of three Direct Numerical Simulations are presented, on relevant test cases for the thermal hydraulics of liquid–metal-cooled nuclear reactors, encompassing a wide spectrum of turbulent convection regimes. The first test case is a Rayleigh-Bénard cell at a Grashof number Gr=5×107, representative of the conditions in the unstably stratified layer of coolant in a reactor pool in both standard operating conditions and emergency situations, e.g. shutdown of the cooling system. The second case is the mixed convection in a cold-hot–cold triple jet configuration, representative of liquid streams exiting from the core into the pool, and relevant for the modeling of thermal striping and thermal fatigue phenomena on the vessel containment walls. The third case is the fully-developed flow in a vertical bare rod bundle with triangular arrangement and a pitch-to-diameter ratio P/D=1.4, in both forced and mixed convection conditions. These regimes respectively represent normal operation or decay heat removal conditions in reactor cores. The availability of these numerical databases will allows for an in-depth analysis of the turbulent flow and heat transfer in liquid metals under different convection regimes, and is also relevant for the development, calibration and validation of turbulent heat transfer models

Structure of turbulence in temporal planar jets

A detailed analysis of the structure of turbulence in a temporal planar turbulent jet is reported. Instantaneous snapshots of the flow and three-dimensional spatial correlation functions are considered. It is found that the flow is characterized by large-scale spanwise vortices whose motion is felt in the entire flow field. Superimposed to this large-scale motion, a hierarchy of turbulent structures is present. The most coherent ones take the form of quasi-streamwise vortices and high and low streamwise velocity streaks. The topology of these interacting structures is analyzed by quantitatively addressing their shape and size in the different flow regions. Such information is recognized to be relevant for a structural description of the otherwise disorganized motion in turbulent free-shear flows and can be used for the assessment of models based on coherent structure assumptions. Finally, the resulting scenario provides a phenomenological description of the elementary processes at the basis of turbulence in free-shear flows

Tumor-Derived Mesenchymal Stem Cells Use Distinct Mechanisms to Block the Activity of Natural Killer Cell Subsets.

Mesenchymal stem cells (MSCs) display pleiotropic functions, which include secretion of soluble factors with immunosuppressive activity implicated in cancer progression. We compared the immunomodulatory effects on natural killer (NK) cells of paired intratumor (T)- and adjacent non-tumor tissue (N)-derived MSCs from patients with squamous cell lung carcinoma (SCC). We observed that T-MSCs were more strongly immunosuppressive than N-MSCs and affected both NK function and phenotype, as defined by CD56 expression. T-MSCs shifted NK cells toward the CD56 <sup>dim</sup> phenotype and differentially modulated CD56 <sup>bright/dim</sup> subset functions. Whereas MSCs affected both degranulation and activating receptor expression in the CD56 <sup>dim</sup> subset, they primarily inhibited interferon-γ production in the CD56 <sup>bright</sup> subset. Pharmacological inhibition of prostaglandin E2 (PGE2) synthesis and, in some MSCs, interleukin-6 (IL-6) activity restored NK function, whereas NK cell stimulation by PGE2 alone mimicked T-MSC-mediated immunosuppression. Our observations provide insight into how stromal responses to cancer dampen NK cell activity in human lung SCC

Effect of a single session of transcranial direct-current stimulation on balance and spatiotemporal gait variables in children with cerebral palsy: A randomized sham-controlled study

Background: Transcranial direct-current stimulation (tDCS) has been widely studied with the aim of enhancing local synaptic efficacy and modulating the electrical activity of the cortex in patients with neurological disorders. Objective: The purpose of the present study was to determine the effect of a single session of tDCS regarding immediate changes in spatiotemporal gait and oscillations of the center of pressure (30 seconds) in children with cerebral palsy (CP). Method: A randomized controlled trial with a blinded evaluator was conducted involving 20 children with CP between six and ten years of age. Gait and balance were evaluated three times: Evaluation 1 (before the stimulation), Evaluation 2 (immediately after stimulation), and Evaluation 3 (20 minutes after the stimulation). The protocol consisted of a 20-minute session of tDCS applied to the primary motor cortex at an intensity of 1 mA. The participants were randomly allocated to two groups: experimental group - anodal stimulation of the primary motor cortex; and control group - placebo transcranial stimulation. Results: Significant reductions were found in the experimental group regarding oscillations during standing in the anteroposterior and mediolateral directions with eyes open and eyes closed in comparison with the control group (p<0.05). In the intra-group analysis, the experimental group exhibited significant improvements in gait velocity, cadence, and oscillation in the center of pressure during standing (p<0.05). No significant differences were found in the control group among the different evaluations. Conclusion: A single session of tDCS applied to the primary motor cortex promotes positive changes in static balance and gait velocity in children with cerebral palsy

Recuperação pós-eletroconvulsoterapia: comparação entre propofol, etomidato e tiopental

OBJECTIVES: To compare post anesthetic time for patient recovery after electroconvulsive therapy, as measured by the post anesthetic Recovery Score of Aldrete and Kroulik, using three different types of hypnotic drugs (propofol, etomidate and thiopental). METHOD: Thirty patients were randomized to receive one of the three drugs (n = 10 in each group), during a course of electroconvulsive therapy treatment. Patients and raters were blinded to which drug was received. Main treatment characteristics were recorded (as total electric charge received seizure threshold, number of treatments, and the mean time for recovery) along the whole treatment. RESULTS: Thiopental and propofol were associated with a significance increase in charge needed to induce a seizure (p < 0.0001) when compared to etomidate, as well as a significant decrease of time for recovery (p = 0.042). CONCLUSIONS: These findings suggest that, although there seems to be no difference in the clinical outcome across these three drugs, propofol offers the best recovery profile. However, it makes a higher mean electric charge necessary.OBJETIVOS: Comparar o tempo de recuperação dos pacientes após eletroconvulsoterapia avaliada com a escala de recuperação pós-anestésica de Aldrete e Kroulik, utilizando três tipos de medicações anestésicas (propofol, etomidato and tiopental). MÉTODO: Trinta pacientes foram randomizados para receber uma das medicações (n = 10 em cada grupo) durante uma série de tratamentos com eletroconvulsoterapia. Os pacientes e o examinador ficaram cegos para o tipo de anestésico utilizado. As principais características do tratamento foram avaliadas (como carga total de eletricidade recebida, limiar convulsivo, número de sessões e o tempo médio para recuperação) ao longo de toda a série de tratamentos. RESULTADOS: Tiopental e propofol se associaram a um aumento significativo na carga elétrica total utilizada (p < 0,0001) quando comparados com etomidato, bem como uma diminuição significativa no tempo de recuperação pós-anestésica (p = 0,042). CONCLUSÕES: Estes achados sugerem que, apesar de não haver diferença na evolução clínica entre os três grupos estudados, a droga propofol oferece o melhor perfil de recuperação apesar de requerer uma carga elétrica média maior

Delayed pain decrease following M1 tDCS in spinal cord injury: A randomized controlled clinical trial

Despite some encouraging findings for the treatment of neuropathic pain in patients with spinal cord injury (SCI), transcranial direct current stimulation (tDCS) directed to the primary motor cortex (M1) has faced some mixed results. Prior to translating this technology to clinical care, consistent results and durable effects need to be found. We, therefore, aimed to assess the direct and long-term effects of tDCS on pain following SCI.We performed a two-phase randomized sham-controlled clinical trial where patients received 5 days of tDCS followed by a 3-month follow-up period (Phase I); then, Phase II consisted of 10 days of tDCS with an 8-week follow-up period. We assessed the level of pain with the Visual Analogue Scale (VAS). Patients' quality of life and life satisfaction were also evaluated.33 patients were enrolled in Phase I and 9 in Phase II. We observed a treatment effect at 1-week follow-up for Phase I and at 4-week follow-up for Phase II. The overall level of pain was significantly lower for the active group, as compared to sham, in Phase II.Our exploratory study shows that tDCS does seem to be a promising tool to manage pain in patients with SCI and repeated stimulation sessions are needed to induce long-lasting effects. Based on our protocol, it appears that adding a second treatment period could induce long-lasting effects.This project was supported by the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR grant numbers 90DP0035 and H133N110010)

Transcranial direct current stimulation for the treatment of Major Depressive Disorder : a summary of preclinical, clinical and translational findings

Major depressive disorder (MDD) is a common psychiatric illness, with 6-12% lifetime prevalence. It is also among the five most disabling diseases worldwide. Current pharmacological treatments, although relatively effective, present important side effects that lead to treatment discontinuation. Therefore, novel treatment options for MDD are needed. Here, we discuss the recent advancements of one new neuromodulatory technique - transcranial direct current stimulation (tDCS) - that has undergone intensive research over the past decade with promising results. tDCS is based on the application of weak, direct electric current over the scalp, leading to cortical hypo- or hyper-polarization according to the specified parameters. Recent studies have shown that tDCS is able to induce potent changes in cortical excitability as well as to elicit long-lasting changes in brain activity. Moreover, tDCS is a technique with a low rate of reported side effects, relatively easy to apply and less expensive than other neuromodulatory techniques - appealing characteristics for clinical use. In the past years, 4 of 6 phase II clinical trials and one recent meta-analysis have shown positive results in ameliorating depression symptoms. tDCS has some interesting, unique aspects such as noninvasiveness and low rate of adverse effects, being a putative substitutive/augmentative agent for antidepressant drugs, and low-cost and portability, making it suitable for use in clinical practice. Still, further phase II and phase III trials are needed as to better clarify tDCS role in the therapeutic arsenal of MOD