This article presents the development and application of the continuous adjoint method for designing/optimizing the shape of hydraulic turbomachines. The Reynolds-averaged flow equations are solved ...in the rotating reference frame and the terms arising from the differentiation of the Coriolis and centripetal forces are taken into account in the formulation of the adjoint equations. The objective functions presented in this article can be used for achieving (a) the optimal collaboration of the runner impeller with the draft tube, by controlling the meridional and circumferential velocity profiles at the exit of the runner, (b) the operation at the desired hydraulic head and/or (c) the cavitation suppression. All of them are used to improve an existing Francis runner. It is important to note that the objective function related to cavitation is, by definition, non-differentiable and a way to effectively handle it, is proposed. The continuous adjoint method is presented in its most general form and could readily be adapted to other objective functions in the field of hydraulic turbomachines.
•Development/application of adjoint methods for designing hydraulic turbomachines.•Various objective functions related to the performance of a Francis runner.•Respecting the inlet velocity profiles of existing draft tubes.•Tackling the non-differentiable cavitation suppression objective function.
The purpose of this study was to establish whether exploration and neurolysis is an effective method of treating neuropathic pain in patients with a sciatic nerve palsy after total hip replacement ...(THR). A total of 56 patients who had undergone this surgery at our hospital between September 1999 and September 2010 were retrospectively identified. There were 42 women and 14 men with a mean age at exploration of 61.2 years (28 to 80). The sciatic nerve palsy had been sustained by 46 of the patients during a primary THR, five during a revision THR and five patients during hip resurfacing. The mean pre-operative visual analogue scale (VAS) pain score was 7.59 (2 to 10), the mean post-operative VAS was 3.77 (0 to 10), with a resulting mean improvement of 3.82 (0 to 10). The pre- and post-neurolysis VAS scores were significantly different (p < 0.001). Based on the findings of our study, we recommend this form of surgery over conservative management in patients with neuropathic pain associated with a sciatic nerve palsy after THR.
Membrane transport plays a leading role in a wide spectrum of cellular and subcellular pathways, including multidrug resistance (MDR), cellular signaling, and cell−cell communication. Pseudomonas ...aeruginosa is renowned for its intriguing membrane transport mechanisms, such as the interplay of membrane permeability and extrusion machinery, leading to selective accumulation of specific intracellular substances and MDR. Despite extensive studies, the mechanisms of membrane transport in living microbial cells remain incompletely understood. In this study, we directly measure real-time change of membrane permeability and pore sizes of P. aeruginosa at the nanometer scale using the intrinsic color index (surface plasmon resonance spectra) of silver (Ag) nanoparticles as the nanometer size index probes. The results show that Ag nanoparticles with sizes ranging up to 80 nm are accumulated in living microbial cells, demonstrating that these Ag nanoparticles transport through the inner and outer membrane of the cells. In addition, a greater number of larger intracellular Ag nanoparticles are observed in the cells as chloramphenicol concentration increases, suggesting that chloramphenicol increases membrane permeability and porosity. Furthermore, studies of mutants (nalB-1 and ΔABM) show that the accumulation rate of intracellular Ag nanoparticles depends on the expression level of the extrusion pump (MexAB−OprM), suggesting that the extrusion pump plays an important role in controlling the accumulation of Ag nanoparticles in living cells. Moreover, the accumulation kinetics measured by Ag nanoparticles are similar to those measured using a small fluorescent molecule (EtBr), eliminating the possibility of steric and size effects of Ag nanoparticle probes. Susceptibility measurements also suggest that a low concentration of Ag nanoparticles (1.3 pM) does not create significant toxicity for the cells, further validating that single Ag nanoparticles (1.3 pM) can be used as biocompatible nanoprobes for the study of membrane transport kinetics in living microbial cells.
We evaluated the quality of guidelines on thromboprophylaxis in orthopaedic surgery by examining how they adhere to validated methodological standards in their development. A structured review was ...performed for guidelines that were published between January 2005 and April 2013 in medical journals or on the Internet. A pre-defined computerised search was used in MEDLINE, Scopus and Google to identify the guidelines. The AGREE II assessment tool was used to evaluate the quality of the guidelines in the study. Seven international and national guidelines were identified. The overall methodological quality of the individual guidelines was good. 'Scope and Purpose' (median score 98% interquartile range (IQR)) 86% to 98%) and 'Clarity of Presentation' (median score 90%, IQR 90% to 95%) were the two domains that received the highest scores. 'Applicability' (median score 68%, IQR 45% to 75%) and 'Editorial Independence' (median score 71%, IQR 68% to 75%) had the lowest scores. These findings reveal that although the overall methodological quality of guidelines on thromboprophylaxis in orthopaedic surgery is good, domains within their development, such as 'Applicability' and 'Editorial Independence', need to be improved. Application of the AGREE II instrument by the authors of guidelines may improve the quality of future guidelines and provide increased focus on aspects of methodology used in their development that are not robust.
A biomechanical model of the brain is presented, using a finite-element formulation. Emphasis is given to the modeling of the soft-tissue deformations induced by the growth of tumors and its ...application to the registration of anatomical atlases, with images from patients presenting such pathologies. First, an estimate of the anatomy prior to the tumor growth is obtained through a simulated biomechanical contraction of the tumor region. Then a normal-to-normal atlas registration to this estimated pre-tumor anatomy is applied. Finally, the deformation from the tumor-growth model is applied to the resultant registered atlas, producing an atlas that has been deformed to fully register to the patient images. The process of tumor growth is simulated in a nonlinear optimization framework, which is driven by anatomical features such as boundaries of brain structures. The deformation of the surrounding tissue is estimated using a nonlinear elastic model of soft tissue under the boundary conditions imposed by the skull, ventricles, and the falx and tentorium. A preliminary two-dimensional (2-D) implementation is presented in this paper, and tested on both simulated and patient data. One of the long-term goals of this work is to use anatomical brain atlases to estimate the locations of important brain structures in the brain and to use these estimates in pre-surgical and radiosurgical planning systems.
Multidrug resistance (MDR) has been reported in both prokaryotes and eukaryotes, underscoring the challenge of design and screening of more efficacious new drugs. For instance, the efflux pump of ...Pseudomonas aeruginosa (gram-negative bacteria) can extrude a variety of structurally and functionally diverse substrates, which leads to MDR. In this study, we present a new platform that studies modes of action of antibiotics in living bacterial cells (P. aeruginosa), in real-time, at nanometer scale and single-cell resolution using nanoparticle optics and single living cell imaging. The color index of silver (Ag) nanoparticles (violet, blue, green, and red) is used as the sized index (30 ± 10, 50 ± 10, 70 ± 10, and 90 ± 10 nm) for real-time measurement of sized transformation of the cell wall and membrane permeability at the nanometer scale. We have demonstrated that the number of Ag nanoparticles accumulated in cells increases as the aztreonam (AZT) concentration increases and as incubation time increases, showing that AZT induces the sized transformation of membrane permeability and the disruption of the cell wall. The results demonstrate that nanoparticle optics assay can be used as a new powerful tool for real-time characterization of modes of action of antimicrobial agents in living cells at the nanometer scale. Furthermore, studies of mutants of WT bacteria (nalB-1 and ΔABM), suggest that an efflux pump (MexA−MexB−OprM) effectively extrudes substrates (nanoparticles) out of the cells, indicating that the MDR mechanism involves the induction of changes in membrane permeability and the intrinsic pump machinery.
The draft tube design of a hydraulic turbine, particularly in low to medium head applications, plays an important role in determining the efficiency and power characteristics of the overall machine, ...since an important proportion of the available energy, being in kinetic form leaving the runner, needs to be recovered by the draft tube into static head. For large units, these efficiency and power characteristics can equate to large sums of money when considering the anticipated selling price of the energy produced over the machine's life-cycle. This same draft tube design: is also a key factor in determining the overall civil costs of the powerhouse, primarily in excavation and concreting, which can amount to similar orders of magnitude as the price of the energy produced. Therefore, there is a need to find the optimum compromise between these two conflicting requirements. In this paper, an elaborate approach is described for dealing with this optimization problem. First, the draft tube's detailed geometry is defined as a function of a comprehensive set of design parameters (about 20 of which a subset is allowed to vary during the optimization process) and are then used in a non-uniform rational B-spline based geometric modeller to fully define the wetted surfaces geometry. Since the performance of the draft tube is largely governed by 3D viscous effects, such as boundary layer separation from the walls and swirling flow characteristics, which in turn governs the portion of the available kinetic energy which will be converted into pressure, a full 3D meshing and Navier-Stokes analysis is performed for each design. What makes this even more challenging is the fact that the inlet velocity distribution to the draft tube is governed by the runner at each of the various operating conditions that are of interest for the exploitation of the powerhouse. In order to determine these inlet conditions, a combined steady-state runner and an initial draft tube analysis, using a stage interface between them, must first be performed for each operating condition. Due to the computationally intensive nature of the evaluation process, the efficiency of the optimization algorithm becomes important. Therefore, a state-of-the-art hierarchical-metamodel-assisted evolutionary algorithm is used.
Rupture of intracranial saccular aneurysms is the most common cause of spontaneous subarachnoid hemorrhage which, despite advances in neurosurgery, continues to result in significant morbidity and ...mortality. Currently, the decision to treat a diagnosed, unruptured aneurysm is based primarily on the maximum dimension of the lesion even though there is controversy over the ‘critical size’ (e.g. many ‘large’ lesions do not rupture whereas some ‘small’ ones do). There is a need, therefore, for improved predictors of the rupture-potential of these lesions. In this paper, we show that it is highly unlikely that saccular aneurysms expand or rupture due to a limit point instability, and suggest that a rupture-criterion should be based on local
multiaxial states of stress or strain. Moreover, our results from nonlinear finite element analyses reveal important roles of lesion shape, material properties, and loading conditions, not just size, in governing the distributions of stress and strain within a sub-class of axisymmetric saccular aneurysms. For example, we find that maximum biaxial stresses and strains are most often at the fundus, where rupture tends to occur, and that maximum stresses increase markedly with increases in lesion size, the ratio of neck diameter to lesion height, and the distending transmural pressure.
The measurement of the luminosity recorded by the CMS detector installed at LHC interaction point 5, using proton–proton collisions at
s
=
13
TeV
in 2015 and 2016, is reported. The absolute ...luminosity scale is measured for individual bunch crossings using beam-separation scans (the van der Meer method), with a relative precision of 1.3 and 1.0% in 2015 and 2016, respectively. The dominant sources of uncertainty are related to residual differences between the measured beam positions and the ones provided by the operational settings of the LHC magnets, the factorizability of the proton bunch spatial density functions in the coordinates transverse to the beam direction, and the modeling of the effect of electromagnetic interactions among protons in the colliding bunches. When applying the van der Meer calibration to the entire run periods, the integrated luminosities when CMS was fully operational are 2.27 and 36.3
fb
-
1
in 2015 and 2016, with a relative precision of 1.6 and 1.2%, respectively. These are among the most precise luminosity measurements at bunched-beam hadron colliders.
PDF
