Extraction and analysis of T waves in electrocardiograms during atrial flutter

Analysis of T waves in the ECG is an essential clinical tool for diagnosis, monitoring, and follow-up of patients with heart dysfunction. During atrial flutter, this analysis has been so far limited by the perturbation of flutter waves superimposed over the T wave. This paper presents a method based on missing data interpolation for eliminating flutter waves from the ECG during atrial flutter. To cope with the correlation between atrial and ventricular electrical activations, the CLEAN deconvolution algorithm was applied to reconstruct the spectrum of the atrial component of the ECG from signal segments corresponding to TQ intervals. The locations of these TQ intervals, where the atrial contribution is presumably dominant, were identified iteratively. The algorithm yields the extracted atrial and ventricular contributions to the ECG. Standard T-wave morphology parameters (T-wave amplitude, T peak-T end duration, QT interval) were measured. This technique was validated using synthetic signals, compared to average beat subtraction in a patient with a pacemaker, and tested on pseudo-orthogonal ECGs from patients in atrial flutter. Results demonstrated improvements in accuracy and robustness of T-wave analysis as compared to current clinical practice.     

Supramolecular Order of Solution‐Processed Perylenediimide Thin Films: High‐Performance Small‐Channel n‐Type Organic Transistors

N,N′‐1H,1H‐perfluorobutyl dicyanoperylenecarboxydiimide (PDIF‐CN₂), a soluble and air stable n‐type molecule, undergoes significant reorganization upon thermal annealing after solution deposition on several substrates with different surface energies. Interestingly, this system exhibits an exceptional edge‐on orientation regardless of the substrate chemistry. This preferential orientation is rationalized in terms of strong intermolecular interactions between the PDIF‐CN₂ molecules. The presence of a pronounced π–π stacking is confirmed by combining near‐edge X‐ray absorption fine structure spectroscopy (NEXAFS), dynamic scanning force microscopy (SFM) and surface energy measurements. The remarkable charge carrier mobility measured in field‐effect transistors, using both bottom‐ and top‐contact (bottom‐gate) configurations, underlines the importance of strong intermolecular interactions for the realization of high performing devices.     

Digital canvas removal in paintings

The periodic structure of the underlying support of paintings on canvas can become quite prominent and disturbing in high resolution digital recordings. In this paper, we construct a new model and method for the digital removal of canvas which is considered as a noise component superimposed on the painting artwork. The high resolution of the images prohibits the efficient application of existing adaptive denoising filters. Hence, a two-step approach is proposed. First a (smoothing) Wiener filter is applied to the complete image. The second step consists of a spatially adaptive extension with low-complexity to obtain a generic digital canvas removal filter.     

SDN-based architecture for providing quality of service to high-performance distributed applications

The specification of quality of service (QoS) requirements in most of the existing networks is still challenging. In part, traditional network environments are limited by their high administrative cost, although software-defined networks (SDNs), a newer network paradigm, simplify the management of the whole network infrastructure. In fact, SDN provides a simple way to effectively develop QoS provisioning mechanisms. In this sense, we explore the SDN model and its flexibility to develop a QoS provisioning architecture. Through the use of our new architecture, network operators are able to specify QoS levels in a simple way. Each individual data flow can be addressed, and the architecture we propose also negotiates the QoS requirements between the network controller and applications. On the other hand, the network controller continuously monitors the network environment. Then, it allocates network elements resources and prioritizes traffic, adjusting the network performance. We evaluate the feasibility of our QoS provisioning mechanism by presenting three experimental setups under realistic scenarios. For example, for a given scenario where we evaluate file transfers, our results indicate that the additional SDN modules present negligible overhead. Moreover, for a given setup, we observe a reduction of up to 82% in the file transfer times.     

Optimized ITO-free tri-layer electrode for organic solar cells

The optical properties of ZnO/Ag/ZnO (ZAZ) multilayer structures were numerically modeled and calculated by a FDTD method. Such tri-layers were also manufactured using an ion beam sputtering plant. A good agreement is obtained between modelizations and realizations. The impact of the oxide thicknesses on the optical properties of the ZAZ structures were experimentally and numerically investigated, and allow us to adjust the spectral position of the transmission maximum. The transmission of these structures is optimized up to around 74%, on the whole absorption spectral range of the photoactive P3HT:PCBM bulk heterojunction. The best electrode design is glass/ZnO (30 nm)/Ag (14 nm)/ZnO (30 nm), which presents a sheet resistance of 7 Ω/□. The optimized ZAZ structure was successfully integrated in an organic solar cell as anode. A photovoltaic efficiency of 2.58% is obtained and is compared to an organic solar cell integrating a traditional ITO anode with an efficiency of 2.99%. Numerical calculations of the intrinsic absorption inside each layer of the organic solar cells are performed. Alternative ITO-free electrodes for organic solar cells are demonstrated.     

Survey and comparison of message authentication solutions on wireless sensor networks

Security is an important concern in any modern network. This also applies to Wireless Sensor Networks (WSNs), especially those used in applications that monitor sensitive information (e.g., health care applications). However, the highly constrained nature of sensors imposes a difficult challenge: their reduced availability of memory, processing power and energy hinders the deployment of many modern cryptographic algorithms considered secure. For this reason, the choice of the most memory-, processing- and energy-efficient security solutions is of vital importance in WSNs. To date, a number of extensive analyses comparing different encryption algorithms and key management schemes have been developed, while very little attention has been given to message authentication solutions. In this paper, aiming to close this gap, we identify cipher-based Message Authentication Codes (MACs) and Authenticated Encryption with Associated Data (AEAD) schemes suitable for WSNs and then evaluate their features and performance on a real platform (TelosB). As a result of this analysis, we identify the recommended choices depending on the characteristics of the target network and available hardware.     

Residual stress in hydroxyapatite coating: nonlinear analysis and high-energy synchrotron measurements

The thermal deposition of hydroxyapatite (HA) on titanium alloy substrate (Ti-6A1-4V) leads to a structure that has very good osseointegration properties. However, clinical failures have been occasionally reported at the interface between substrate and coating. Lifetime is the main parameter in such prostheses; therefore, in order to improve their quality, it is necessary to evaluate the level of stresses near the interface. The high-energy synchrotron radiation combines the advantages of a bulk analysis and reduced volume of the gauge. The objective of our study was to calculate the residual stress using a nonlinear finite-element model and to measure residual stress level near the interface, in the hydroxyapatite coating and in titanium alloy substrate with a nondestructive and high-resolution experiment. The high-energy synchrotron radiation of the BM16 beam-line at ESRF (Grenoble-France) was used with a resolution of down to 10 micrometers. The experimental measurements validate the results found by means of nonlinear finite-element analysis of the plasma spraying induced stress.     

用于电源测试的精确压控电流阱

为了检测潜在的电源缺陷,必须进行动态和静态测试。这里的简单电流阱可测试低到中功率电源和恒压源。在该应用中,在输入电压范围为0V～5V,电源电压最高为20V时,电流阱可吸收0A～1.5A的电流。该电路的基本部件为一个精密运放IC1,采用Texas Instruments的OPA277。该器件特点为：最大输入偏置电压仅为100μV,最大输入偏置电流为4nA,在-40℃-＋85℃温度范围内温漂较低（图1）。运放IC将其正输入电压与检测电阻RSENSE上的电压进行比较。     

Some statistical properties of mathematical morphology

Analyzes the statistical properties of the basic binary and multilevel morphological operations with both 1-D and 2D structuring elements. Very simple expressions for the output distribution of erosion and opening are derived in the case of any independent identically or nonidentically distributed inputs. The probability relations between erosion and dilation, also between opening and closing, are developed. The output expectation bias and variances are analyzed and computed to show the efficiency of morphological operations for noise supression. As applications of theoretical results, the effects of the morphological operations on noisy signals are illustrated by several examples. The study reveals certain interesting phenomena. For example, the output variances of opening for some input distributions are greater than those of erosion, and morphological operations perform better than median filters in edge preservation