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21.
22.
Chronic obstructive pulmonary disease in patients with end‐stage kidney disease on hemodialysis 下载免费PDF全文
Louis L. Plesner Peder E. Warming Ture L. Nielsen Morten Dalsgaard Morten Schou Ulla Høst Casper Rydahl Lisbet Brandi Lars Køber Jørgen Vestbo Kasper Iversen 《Hemodialysis international. International Symposium on Home Hemodialysis》2016,20(1):68-77
The objectives of this study were to assess the prevalence of chronic obstructive pulmonary disease (COPD) in hemodialysis patients with spirometry and to examine the effects of fluid removal by hemodialysis on lung volumes. Patients ≥18 years at two Danish hemodialysis centers were included. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio were measured with spirometry before and after hemodialysis. The diagnosis of COPD was based on both the GOLD criteria and the lower limit of normal criteria. There were 372 patients in treatment at the two centers, 255 patients (69%) completed spirometry before dialysis and 242 of these (65%) repeated the test after. In the initial test, 117 subjects (46%) had airflow limitation indicative of COPD with GOLD criteria and 103 subjects (40.4%) with lower limit of normal criteria; COPD was previously diagnosed in 24 patients (9%). Mean FVC and FEV1 decreased mildly after dialysis (FVC: 2.84 to 2.79 L, P < 0.01. FEV1: 1.97 to 1.93 L, P < 0.01) Hemodialysis did not affect the FEV1/FVC ratio or number of subjects with airflow limitation indicative of COPD (113 vs. 120, P = 0.324; n = 242). COPD is a frequent and underdiagnosed comorbidity in patients on chronic hemodialysis. Spirometry should be considered in all patients on dialysis in order to address dyspnea adequately. Hemodialysis induced a small fall in mean FEV1 and FVC, which was more pronounced in patients with little or no fluid removal, but the FEV1/FVC ratio and the number of subjects with airflow limitation indicative of COPD were not affected by dialysis. 相似文献
23.
Electrochemical migration (ECM) of tin can result in the growth of a metal deposit with a dendritic structure from cathode to anode. In electronics, such growth can lead to short circuit of biased electrodes, potentially leading to intermittent or complete failure of an electronic device. In this paper, mechanistic aspects of ECM of tin are discussed in detail, using experimental results on ECM of tin in various environments and varying potential bias. Results on the formation of local pH changes by the electrodes and experiments observations are combined with thermodynamic stability of tin species as depicted in the Pourbaix diagram. 相似文献
24.
Gunnar Gudnason Erik Bruun Morten Haugland 《Analog Integrated Circuits and Signal Processing》2000,22(1):81-89
This paper describes a chip for a multichannel neural stimulator for functional electrical stimulation (FES). The purpose of FES is to restore muscular control in disabled patients. The chip performs all the signal processing required in an implanted neural stimulator. The power and digital data transmission to the stimulator passes through a 5 MHz inductive link. From the signals transmitted to the stimulator, the chip is able to generate charge-balanced current pulses with a controllable length up to 256 s and an amplitude up to 2 mA, for stimulation of nerve fibers. The quiescent current consumption of the chip is approx. 650 A at supply voltages of 6–12 V, and its size is 3.9×3.5 mm2. It has 4 output channels for use in a multipolar cuff electrode. 相似文献
25.
Christensen JK Lamberth K Nielsen M Lundegaard C Worning P Lauemøller SL Buus S Brunak S Lund O 《Neural computation》2003,15(12):2931-2942
Strategies for selecting informative data points for training prediction algorithms are important, particularly when data points are difficult and costly to obtain. A Query by Committee (QBC) training strategy for selecting new data points uses the disagreement between a committee of different algorithms to suggest new data points, which most rationally complement existing data, that is, they are the most informative data points. In order to evaluate this QBC approach on a real-world problem, we compared strategies for selecting new data points. We trained neural network algorithms to obtain methods to predict the binding affinity of peptides binding to the MHC class I molecule, HLA-A2. We show that the QBC strategy leads to a higher performance than a baseline strategy where new data points are selected at random from a pool of available data. Most peptides bind HLA-A2 with a low affinity, and as expected using a strategy of selecting peptides that are predicted to have high binding affinities also lead to more accurate predictors than the base line strategy. The QBC value is shown to correlate with the measured binding affinity. This demonstrates that the different predictors can easily learn if a peptide will fail to bind, but often conflict in predicting if a peptide binds. Using a carefully constructed computational setup, we demonstrate that selecting peptides with a high QBC performs better than low QBC peptides independently from binding affinity. When predictors are trained on a very limited set of data they cannot be expected to disagree in a meaningful way and we find a data limit below which the QBC strategy fails. Finally, it should be noted that data selection strategies similar to those used here might be of use in other settings in which generation of more data is a costly process. 相似文献
26.
Asmild M Oswald N Krzywkowski KM Friis S Jacobsen RB Reuter D Taboryski R Kutchinsky J Vestergaard RK Schrøder RL Sørensen CB Bech M Korsgaard MP Willumsen NJ 《Receptors & channels》2003,9(1):49-58
Effective screening of large compound libraries in ion channel drug discovery requires the development of new electrophysiological techniques with substantially increased throughputs compared to the conventional patch clamp technique. Sophion Bioscience is aiming to meet this challenge by developing two lines of automated patch clamp products, a traditional pipette-based system called Apatchi-1, and a silicon chip-based system QPatch. The degree of automation spans from semi-automation (Apatchi-1) where a trained technician interacts with the system in a limited way, to a complete automation (QPatch 96) where the system works continuously and unattended until screening of a full compound library is completed. The performance of the systems range from medium to high throughputs. 相似文献
27.
In Part I of this article, the influence of various testing parameters and environments on the fatigue-crack growth rates
in samples of beta-annealed Ti-6Al-4V-0.1Ru (extra-low interstitials) ELI was reported.[1] A design-of-experiments (DOE) approach was used to survey different combinations of variables, all expected to be important
for dynamically loaded offshore oil and gas production risers, and to identify significant effects on the fatigue-crack propagation
rate at a stress-intensity range of ΔK=17 MPa
. The da/dN vs ΔK curves also were examined for the DOE and supplementary tests, and the results of the two approaches were compared. In this
part of the study, the microstructural basis for the robust fatigue-crack growth resistance of beta-annealed Ti-6Al-4V-0.1Ru
(ELI) samples was investigated with optical metallography and scanning electron microscopy (SEM). A gradual transition from
structure-sensitive (microfacet formation) to structure-insensitive (striation formation) crack propagation centered at ΔK
trans ≅24 MPa
, regardless of the combination of testing/environmental conditions examined; the absence of a sharp transition in the slope
of the da/dN vs ΔK curves was, therefore, entirely consistent with the fracture-surface morphology. The size of the reversed cyclic plastic
zone at the transition ΔK value correlated with the size of the lamella packets, but the number of cycles required to generate a striation ranged between
one and ten, suggesting that the crack actively grew over only a portion of its front at any one instant. It is interesting
to note that ΔK
trans was the same as the stress range where the da/dN curves at 0.2, 2, and 20 Hz (in seawater) converged to a single curve (refer to Part I of this article): at lower stress
ranges, crack growth rates at 20 Hz were significantly higher than those at 0.2 and 2 Hz. The quantitative data showed that
fatigue cracks propagated parallel to lamellae interfaces when the long axes of the lamellae made a relatively small angle
(<30 deg) to the nominal crack-propagation direction. The crack cut directly across lamellae (i.e., perpendicular to their surfaces) when the long axes of the lamellae were nearly perpendicular to the nominal crack-propagation
direction. If the lamellae long axes lay 45 deg to the crack-propagation direction, the crack deflected to run parallel or
perpendicular to the lamellae. This behavior occurred regardless of the environment and loading conditions investigated. There
was considerable variation in the amount that the cracks deviated from their nominal plane (i.e., the plane normal to the load axis and through the notch tip), with much greater deflections in the cold-rolled than in the
parent material, but the angle of the macroscopic crack plane did not exceed 11 deg. Crack branching was observed both at
the center and outer surfaces of the samples, regardless of ΔK or other parameters. The relationship between micro- and macrobranches was examined, and branching was more prominent below
ΔK
trans, which separated the structure-sensitive and continuum-mode crack-propagation regimes. The relative amounts of micro- and
microbranches are reported, and this branching may explain the large scatter in the measurements of the fatigue-crack growth
rate often encountered in Ti-6Al-4V and its variants and points to the need for thorough characterization of crack paths,
both midplane and surface, as part of the interpretation of da/dN vs ΔK data. 相似文献
28.
The note addresses the calculation of piecewise quadratic (PWQ) Lyapunov functions for PWA (piecewise affine) systems. New LMI relaxations are proposed. These relaxations have been found to be effective in cases where the traditional relaxations fail. 相似文献
29.
The explicit solution of multi-parametric optimisation problems (MPOP) has been used to construct an off-line solution to relatively small- and medium-sized constrained control problems. The control design principles are based on receding horizon optimisation and generally use linear prediction models for the system dynamics. In this context, it can be shown that the optimal control law is a piecewise linear (PWL) state feedback defined over polytopic cells of the state space. However, as the complexity of the related optimisation problems increases, the memory footprint and implementation of such explicit optimal solution may be burdensome for the available hardware, principally due to the high number of polytopic cells in the state-space partition. In this article we provide a solution to this problem by proposing a patchy PWL feedback control law, which intend to approximate the optimal control law. The construction is based on the linear interpolation of the exact solution at the vertices of a feasible set and the solution of an unconstrained linear quadratic regulator (LQR) problem. With a hybrid patchy control implementation, we show that closed-loop stability is preserved in the presence of additive measurement noise despite the existence of discontinuities at the switch between the overlapping regions in the state-space partition. 相似文献
30.
Niels Aage Morten Nobel-Jørgensen Casper Schousboe Andreasen Ole Sigmund 《Structural and Multidisciplinary Optimization》2013,47(1):1-6
This paper presents an interactive topology optimization application designed for hand-held devices running iOS or Android. The TopOpt app solves the 2D minimum compliance problem with interactive control of load and support positions as well as volume fraction. Thus, it is possible to change the problem settings on the fly and watch the design evolve to a new optimum in real time. The use of an interactive app makes it extremely simple to learn and understand the influence of load-directions, support conditions and volume fraction. The topology optimization kernel is written in C# and the graphical user interface is developed using the game engine Unity3D. The underlying code is inspired by the publicly available 88 and 99 line Matlab codes for topology optimization but does not utilize any low-level linear algebra routines such as BLAS or LAPACK. The TopOpt App can be downloaded on iOS devices from the Apple App Store, at Google Play for the Android platform, and a web-version can be run from www.topopt.dtu.dk. 相似文献