Search

Probabilistic domain decomposition (PDD) is an alternative paradigm for solving boundary value problems (BVPs) in parallel with excellent scalability properties, thanks to its reliance on stochastic representations of the BVP. However, there are cases when the latter is less numerically convenient, or unknown. Semilinear elliptic BVPs and the Helmholtz equation are prominent examples of either class. In this paper, we overcome this issue by designing suitable iterative schemes for either problem. These schemes not only retain the desirable properties of PDD but also are optimally suited for pathwise variance reduction, resulting in a systematic, nearly cost-free reduction of the statistical error through the iterations. Numerical tests carried out on the supercomputer Marconi100 are presented. [ABSTRACT FROM AUTHOR]

Background and objective. Scar contractures in the hand are a sequela of burns that can lead to functional impairment. The perforator flap from the digital artery, taken from the lateral aspect of the fingers, represents an excellent therapeutic option for managing these injuries. We present our experience with this surgical technique and our morphological and functional results. Methods. We present our experience with 14 flaps in 7 patients affected by web contractures in the hand. These flaps, based on perforators from the digital artery, use the adjacent lateral aspect of the proximal phalanx as the donor site. The donor area was covered with full-thickness skin grafts. Patients underwent early rehabilitation, pressure therapy, and nighttime splinting. Results. The survival of the flaps was successful in all 14 cases. One case experienced graft necrosis in the donor site of the flap, which resolved with conservative treatment. Commissural contractures were resolved in 85.7% of the cases (13 out of 14 cases). The mean follow-up period was 27.3 months (range 12-45 months). In 1 case, partial recurrence occurred at 10 months and it was successfully managed with Z-plasty. Patients reported subjective improvement in hand functionality and aesthetics. The interdigital space angle, measured in degrees, improved from a mean of 22.5 degrees preoperatively (range 15°-35°) to a mean of 36.8 degrees postoperatively (range 25°-45°). Conclusions. In our experience, the perforator flap from the digital artery represents a rapid, straightforward, and effective therapeutic option for treating contractures after burns in the second to fourth interdigital spaces. Adequate postoperative care, rehabilitation, pressure therapy and splinting are essential for optimal outcomes. [ABSTRACT FROM AUTHOR]

A methodology is presented for the numerical solution of nonlinear elliptic systems in unbounded domains, consisting of three elements. First, the problem is posed on a finite domain by means of a proper nonlinear change of variables. The compressed domain is then discretised, regardless of its final shape, via the radial basis function partition of unity method. Finally, the system of nonlinear algebraic collocation equations is solved with the trust-region algorithm, taking advantage of analytically derived Jacobians. We validate the methodology on a benchmark of computational fluid mechanics: the steady viscous flow past a circular cylinder. The resulting flow characteristics compare very well with the literature. Then, we stress-test the methodology on less smooth obstacles—rounded and sharp square cylinders. As expected, in the latter scenario the solution is polluted by spurious oscillations, owing to the presence of boundary singularities. • Infinite domain compression removes the need for artificial computational domain and the hard-to-quantify associated error. • Nonlinear elliptic PDEs, particularly systems thereof, are very rare in the RBF literature. • RBF-PU allows for handling systems of nonlinear PDEs in strong form on irregular domains without loss of performance. • RBF-PU's accurate derivates lead to a compact, sparse, easy-to-derive analytical Jacobian. • Detailed transition from circular to square cylinder investigated numerically, showing good agreement with published results. [ABSTRACT FROM AUTHOR]

ATP, one of the signaling molecules most commonly secreted in the nervous system and capable of stimulating multiple pathways, binds to the ionotropic purinergic receptors, in particular, the P2X7 receptor (P2X7R) and stimulates neuronal cell death. Given this effect of purinergic receptors on the viability of dopaminergic neurons model cells and that Ras GTPases control Erk1/2-regulated mitogen-activated cell proliferation and survival, we have investigated the role of the small GTPases of the Ras superfamily, together with their regulatory and effector molecules as the potential molecular intermediates in the P2X7R-regulated cell death of SN4741 dopaminergic neurons model cells. Here, we demonstrate that the neuronal response to purinergic stimulation involves the Calmodulin/RasGRF1 activation of the small GTPase Ras and Erk1/2. We also demonstrate that tyrosine phosphatase PTPRβ and other tyrosine phosphatases regulate the small GTPase activation pathway and neuronal viability. Our work expands the knowledge on the intracellular responses of dopaminergic cells by identifying new participating molecules and signaling pathways. In this sense, the study of the molecular circuitry of these neurons is key to understanding the functional effects of ATP, as well as considering the importance of these cells in Parkinson's Disease. [ABSTRACT FROM AUTHOR]

Nucleus incertus (NI) neurons in the pontine tegmentum give rise to ascending forebrain projections and express the neuropeptide relaxin-3 (RLN3) which acts via the relaxin-family peptide 3 receptor (RXFP3). Activity in the hippocampus and entorhinal cortex can be driven from the medial septum (MS), and the NI projects to all these centers, where a prominent pattern of activity is theta rhythm, which is related to spatial memory processing. Therefore, we examined the degree of collateralization of NI projections to the MS and the medial temporal lobe (MTL), comprising medial and lateral entorhinal cortex (MEnt, LEnt) and dentate gyrus (DG), and the ability of the MS to drive entorhinal theta in the adult rat. We injected fluorogold and cholera toxin-B into the MS septum and either MEnt, LEnt or DG, to determine the percentage of retrogradely labeled neurons in the NI projecting to both or single targets, and the relative proportion of these neurons that were RLN3-positive (+). The projection to the MS was threefold stronger than that to the MTL. Moreover, a majority of NI neurons projected independently to either MS or the MTL. However, RLN3 + neurons collateralize significantly more than RLN3-negative (–) neurons. In in vivo studies, electrical stimulation of the NI induced theta activity in the MS and the entorhinal cortex, which was impaired by intraseptal infusion of an RXFP3 antagonist, R3(BΔ23-27)R/I5, particularly at ~ 20 min post-injection. These findings suggest that the MS plays an important relay function in the NI-induced generation of theta within the entorhinal cortex. [ABSTRACT FROM AUTHOR]

Introduction: Metabolic and inflammatory disorders are widely described in COVID-19 disease by SARS-CoV-2, especially in advanced gravity stages, nevertheless, the increase in inflammatory and tissue damage biomarkers could identify patients with higher mortality risk since early disease stages. Material and Method: A retrospective Cohort study was performed to evaluate the progression pattern and mortality risk of proinflammatory (Ferritin and IL- 6) and damage tissue biomarkers seric levels (LDH, CPK, CPK-MB and TnIc) since the beginning of the disease to end outcome considered, in this study, as death or recovery. Results: We evaluated 120 patients with mean age 51±10 years. The CAT study showed in all patients bilateral polished glass lung lesions. The inflammatory and seric tissue injured biomarkers were significantly higher since the beginning of the hospitalization in patients who died compared with patients that survived (p = 0.01). The myocardial injury biomarkers (CPK-MB and TnIc) were significantly higher in severe gravity stages of deceased patients compared to patients who survived (p = 0.001 and 0.003 respectively) with a global mortality of 38.3% (n = 48). The mortality risk was extremely elevated (RR> 10) when inflammatory and tissue injury biomarkers showed seric levels 2 folds above normal values, showing survival of < 60% after tenth day since the beginning disease. Conclusion: Since the beginning of COVID-19 disease by SARS CoV2 virus, patients show serum elevation in ferritin, LDH and CPK. This seric values were associated with higher mortality risk, when elevated 2 folds above normal values. [ABSTRACT FROM AUTHOR]