Search Results (5)

Background: Carotid web (CaW) usually presents as a shelf-like intimal flap at the beginning of the internal carotid artery. It has been proven that CaW is associated with ischemic stroke, particularly in young patients without other risk factors. This case report aimed to describe the carotid web that causes ischemic stroke due to embolic complications. Moreover, both pathologies were successfully treated with endovascular techniques in the presented case study. Methods: A 59-year-old male presented to the neurological department with motor aphasia, right-sided weakness, and hypoesthesia. Computer tomography (CT) of the head and computed tomography angiography (CTA) of the aortic arch and intracranial arteries were performed. Due to the unknown onset of the presented stroke symptoms, diagnostics were extended to magnetic resonance (MR), and based on this, the patient qualified for immediate mechanical thrombectomy (according to the DAWN trial protocol). Intraoperative digital subtraction angiography (DSA) revealed embolism material in the left middle cerebral artery (segment M1). The artery was recanalized via aspiration thrombectomy using the Penumbra system, and complete restoration of flow was obtained (according to the TICI scale). In addition, DSA revealed the presence of CaW changes in the left internal carotid artery (LICA). In the control CT scanning, an acute ischemic area in the left temporal lobe was found. After the treatment, the patient demonstrated complete neurological improvement from his initial presentation. He qualified for carotid artery stenting of the LICA, which was postponed to a later period due to the presence of an area of infarction. The angioplasty with stenting was performed 6 months later, and a carotid antiembolic “mesh” stent (Roadsaver, Terumo) was implanted into the LICA across the carotid web. Conclusions: CaW should be considered in the case of stroke resulting from unknown causes. The presented case study demonstrated that both carotid web and ischemic stroke pathologies can be effectively treated with emerging endovascular techniques. Full article

In the past decade, there has been renewed interest in wave energy harvesting utilizing oscillating water columns (OWC), one of the most well-studied wave energy harnessing technologies. In the OWC, pneumatic power from ocean waves is converted to mechanical energy by Wells turbines. It should be noted, however, that such turbines tend to perform poorly, have a limited operating range, and have low efficiency. In the present study, we incorporate a rectangular Gurney flap (GF) at the trailing edge (TE) of a Wells turbine consisting of hybrid airfoil (NACA 0015 and NACA 0025) blades with variable chord distribution along the span. This passive flow control mechanism was adopted to achieve increased power production by the Wells turbine. This study aimed to determine the aerodynamic performance of the variable chord turbine with GF compared to a turbine with a constant chord. By using ANSYS™ CFX, the three-dimensional, steady-state, incompressible Reynolds averaged Navier–Stokes (RANS) equations coupled with the k-ω SST turbulence model are solved. The performance was evaluated through the use of non-dimensional coefficients of torque, pressure drop, and efficiency. In addition, the numerical accuracy was achieved through a grid independence study. There was a good agreement between the computed results and the available experimental and numerical data. The GF increased the torque coefficient by 18.6% and 47.3% but with the expense of peak efficiency of 8.5% and 7.4% for the baseline and the hybrid turbine, respectively. Additionally, the hybrid turbine with GF delayed the onset of the stall by ~3° angle of attack (AOA). Full article

A convex corner models the upper surface of a deflected flap and shock-induced boundary layer separation occurs at transonic speeds. This study uses micro-vortex generators (MVGs) for flow control. An array of MVGs (counter-rotating vane type, ramp type and co-rotating vane type) with a height of 20% of the thickness of the incoming boundary layer is installed upstream of a convex corner. The surface pressure distributions are similar regardless of the presence of MVGs. They show mild upstream expansion, a strong favorable pressure gradient near the corner’s apex and downstream compression. A corrugated surface oil flow pattern is observed in the presence of MVGs and there is an onset of compression moving downstream. The counter-rotating vane type MVGs produce a greater reduction in peak pressure fluctuations and the ramp type decreases the separation length. The presence of MVGs stabilizes the shock and shock oscillation is damped. Full article

In this paper, an insect flapping onset control method based on electrical stimulation is proposed. The beetle (Allomyrina dithotomus, Coleoptera) is employed for the research carrier, and it’s left and right longitudinal muscles are electrically stimulated to control the flapping onset behavior. The control principle of insect flapping onset utilizing electrical stimulation is analyzed firstly followed by the movement function of the dorsal longitudinal muscle. Subsequently, a micro-control system, which is composed of a PC controller, coordinator and electronic backpack, is designed to realize the wireless control of beetle movements. Finally, the verification experiment is implemented to verify the effectiveness of dorsal longitudinal muscle stimulation with respect to the beetle flapping onset, whereas the comparative experiment emphasizes on determining optimal simulating parameters. The experimental results demonstrate that when the period, duty ratio, number of and amplitude of pulses stimulation signal are assigned to 5 ms, 20%, 90 and 3.3 V respectively, the beetle flapping onset can be controlled with an average response time of 1.69 s. Simultaneously, the optimization of duty ratio from 20% to 40%, and the number of pulses from 90 to 100, is proved to the best parameter configuration. Full article

Replication and maintenance of mtDNA entirely relies on a set of proteins encoded by the nuclear genome, which include members of the core replicative machinery, proteins involved in the homeostasis of mitochondrial dNTPs pools or deputed to the control of mitochondrial dynamics and morphology. Mutations in their coding genes have been observed in familial and sporadic forms of pediatric and adult-onset clinical phenotypes featuring mtDNA instability. The list of defects involved in these disorders has recently expanded, including mutations in the exo-/endo-nuclease flap-processing proteins MGME1 and DNA2, supporting the notion that an enzymatic DNA repair system actively takes place in mitochondria. The results obtained in the last few years acknowledge the contribution of next-generation sequencing methods in the identification of new disease loci in small groups of patients and even single probands. Although heterogeneous, these genes can be conveniently classified according to the pathway to which they belong. The definition of the molecular and biochemical features of these pathways might be helpful for fundamental knowledge of these disorders, to accelerate genetic diagnosis of patients and the development of rational therapies. In this review, we discuss the molecular findings disclosed in adult patients with muscle pathology hallmarked by mtDNA instability. Full article