Pulse morphology visualization and analysis with applications in cardiovascular pressure signals

We present a new analysis and visualization method for studying the functional relationship between the pulse morphology of pressure signals and time or signal metrics such as heart rate, pulse pressure, and means of pressure signals, such as arterial blood pressure and central venous pressure. The pulse morphology is known to contain potentially useful clinical information, but it is difficult to study in the time domain without the aid of a tool such as the method we present here. The primary components of the method are established signal processing techniques, nonparametric regression, and an automatic beat detection algorithm. Some of the insights that can be gained from this are demonstrated through the analysis of intracranial pressure signals acquired from patients with traumatic brain injuries. The analysis indicates the point of transition from low-pressure morphology consisting of three distinct peaks to a high-pressure morphology consisting of a single peak. In addition, we demonstrate how the analysis can reveal distinctions in the relationship between morphology and several signal metrics for different patients.     

Point Defects in Pb-, Bi-, and In-Doped CdZnTe Detectors: Deep-Level Transient Spectroscopy (DLTS) Measurements

We studied, by current deep-level transient spectroscopy (I-DLTS), point defects induced in CdZnTe detectors by three dopants: Pb, Bi, and In. Pb-doped CdZnTe detectors have a new acceptor trap at around 0.48?eV. The absence of a V_Cd trap suggests that all Cd vacancies are compensated by Pb interstitials after they form a deep-acceptor complex [[Pb_Cd]⁺-V _Cd ^2? ]^?. Bi-doped CdZnTe detectors had two distinct traps: a shallow trap at around 36?meV and a deep donor trap at around 0.82?eV. In detectors doped with In, we noted three well-known traps: two acceptor levels at around 0.18?eV (A-centers) and 0.31?eV (V_Cd), and a deep trap at around 1.1?eV.     

业务使能软交换技术在市场的推动下前进

最初的软交换技术在电信领域的商业化应用为VoIP长途电话业务,即C4替代。接着,C5替代和应用使能软交换系统受到关注。前者由于承载和业务开放性方面的限制、业务集成困难和端到端QoS的困难而停滞不前;相比之下,后者却受到了许多中小企业的欢迎。在应用使能软交换的基础上,UT斯达康公司倡导业务使能交换技术,其核心为电信业务网络技术,适用于基于IP的下一代宽带固定多媒体网络和第三代移动多媒体网络。     

Determination of Thermoelectric Module Efficiency: A Survey

The development of thermoelectrics (TE) for energy conversion is in the transition phase from laboratory research to device development. There is an increasing demand to accurately determine the module efficiency, especially for the power generation mode. For many TE, the figure of merit, ZT, of the material sometimes cannot be fully realized at the device level. Reliable efficiency testing of thermoelectric modules is important to assess the device ZT and provide end-users with realistic values for how much power can be generated under specific conditions. We conducted a general survey of efficiency testing devices and their performance. The results indicated a lack of industry standards and test procedures. This study included a commercial test system and several laboratory systems. Most systems are based on the heat flow meter method, and some are based on the Harman method. They are usually reproducible in evaluating thermoelectric modules. However, different systems often showed large differences that are likely caused by uncertain heat loss and thermal resistance. Efficiency testing is an important capability for the thermoelectric community to improve. A follow-up international standardization effort is planned.     

King Solomon’s Mines: A 20th Century Myth

Over the last twenty years, there has been a discernable increase in the number of scholars who have focused their research on metal production, working and use in antiquity, a field of study which has come to be known as ARCHAEOMETALLURGY. Materials scientists and conservators have worked primarily in the laboratory while archaeologists have conducted fieldwork geared to the study of metal technology in a cultural context with laboratory analysis as one portion of the interpretive program.     

Evaluation of four probability distribution models for speckle in clinical cardiac ultrasound images

Segmenting cardiac ultrasound images requires a model for the statistics of speckle in the images. Although the statistics of speckle are well understood for the raw transducer signal, the statistics of speckle in the image are not. This paper evaluates simple empirical models for first-order statistics for the distribution of gray levels in speckle. The models are created by analyzing over 100 images obtained from commercial ultrasound machines in clinical settings. The data in the images suggests a unimodal scalable family of distributions as a plausible model. Four families of distributions (Gamma, Weibull, Normal, and Log-normal) are compared with the data using goodness-of-fit and misclassification tests. Attention is devoted to the analysis of artifacts in images and to the choice of goodness-of-fit and misclassification tests. The distribution of parameters of one of the models is investigated and priors for the distribution are suggested.     

模拟信号输入的数字显示技术

现代数字视频显示器已经随处可见,数字视频投影机的性价比正在攀升到新的高度.持续走低的价格,以及平板显示器明显的占用空间少优势,使企业客户及个人消费者迅速远离传统的阴极射线管(CRT)显示器.     

驱动高功率LED照明应用的新方法

在路灯、层板灯体育场照明及其他许多高功率照明应用中,发展的趋势正转向使用LED做为光源的固态照明,其中的原因在于LED具有更高的能源效率及较低的维护频率,而这两项因素也证明如此的转向确有其必要性。     

Mechanisms of access to the Internet in rural areas of developing countries

Because of severe affordability and skills constraints it is especially difficult to bring the Internet to rural areas of developing countries. But a number of promising alternatives are beginning to emerge. These are mainly designed to bring the Internet to non-users, that is, persons who do not actually come into direct contact with the technology. Such persons make up the bulk of the rural population in most developing countries. Two possibilities exist: one that involves intermediation at a distance (blending) and the other that takes place at close range (via say Internet kiosks). I use numerous examples to illustrate the potential of both these categories. For the minority of those who are able to actually use the Internet, costs can be lessened by a combination of communal institutions and technical sharing devices.     

Robustness of quantitative compressive sensing MRI: the effect of random undersampling patterns on derived parameters for DCE- and DSC-MRI

Compressive sensing (CS) in Cartesian magnetic resonance imaging (MRI) involves random partial Fourier acquisitions. The random nature of these acquisitions can lead to variance in reconstruction errors. In quantitative MRI, variance in the reconstructed images translates to an uncertainty in the derived quantitative maps. We show that for a spatially regularized 2 ×-accelerated human breast CS DCE-MRI acquisition with a 192 (2) matrix size, the coefficients of variation (CoVs) in voxel-level parameters due to the random acquisition are 1.1%, 0.96%, and 1.5% for the tissue parameters K(trans), v(e), and v(p), with an average error in the mean of -2.5%, -2.0%, and -3.7%, respectively. Only 5% of the acquisition schemes had a systematic underestimation larger than than 4.2%, 3.7%, and 6.1%, respectively. For a 2 × -accelerated rat brain CS DSC-MRI study with a 64(2) matrix size, the CoVs due to the random acquisition were 19%, 9.5%, and 15% for the cerebral blood flow and blood volume and mean transit time, respectively, and the average errors in the tumor mean were 9.2%, 0.49%, and -7.0%, respectively. Across 11 000 different CS reconstructions, we saw no outliers in the distribution of parameters, suggesting that, despite the random undersampling schemes, CS accelerated quantitative MRI may have a predictable level of performance.