Qualitative and quantitative evaluation of heart sound reduction from lung sound recordings

Recursive least squares (RLS) adaptive noise cancellation (ANC) and wavelet transform (WT) ANC have been applied and compared for heart sound (HS) reduction from lung sounds (LS) recordings. Novel processes for quantitative and qualitative evaluation of any method for HS reduction from LS have also been proposed.     

A 2.5-ns clock access, 250-MHz, 256-Mb SDRAM with synchronousmirror delay

A 256-Mb SDRAM (245.7 mm²) has been developed using (1) a high cell occupation ratio (60.2%) array design for chip size reduction and a high yield, (2) a prefetched pipeline scheme (PPS) using a first-in first-out (FIFO) buffer with parallel serial converter for 250-MHz clock frequency operation, and (3) a synchronous mirror delay (SMD) circuit for 2.5-ns clock access and low standby current     

Determination of axisymmetric elastic constants in anisotropic silicon for a thyristor tablet

The stress distribution in a thyristor tablet due to thermal shrinkage is considered. The thyristor tablet consists of two cylindrical layers, anisotropic silicon (the semiconductor) and molybdenum (the substrate). Using the software package ‘ANSYS’ stresses are calculated for 4 different cases namely, I) the axisymmetric case, II) the 3-dimensional isotropic silicon, III) the 3-dimensional anisotropic (100) silicon and IV) the 3-dimensional anisotropic (111) silicon. Good agreement is found between cases I and II which serves as a check for the accuracy of the numerical calculations. Comparing cases III and IV one finds that for (111) Si the Van Mises stress lies up to 15% above the value of (100) Si. Although a 4-fold axis in the stress distribution is observed for (100) Si and a 3-fold axis for (111) Si, for practical purposes one can neglect this anisotropy for Si and perform an axisymmetric calculation, since the dependence of the stresses on the azimutal angle is rather weak. Finally, the elastic constants (or more precisely, the material property matrices) for (100) and (111) Si, respectively, as they should be used in an axisymmetric (but not isotropic) analysis, are presented.     

Two-electrode biopotential measurements: power line interference analysis

In this paper, an analysis of power line interference in two-electrode biopotential measurement amplifiers is presented. A model of the amplifier that includes its input stage and takes into account the effects of the common mode input impedance Z(C) is proposed. This approach is valid for high Z(C) values, and also for some recently proposed low-Z(C) strategies. It is shown that power line interference rejection becomes minimal for extreme Z(C) values (null or infinite), depending on the electrode-skin impedance's unbalance deltaZ(E). For low deltaZ(E) values, minimal interference is achieved by a low Z(C) strategy (Z(C) = 0), while for high deltaZ(E) values a very high Z(C) is required. A critical deltaZ(E) is defined to select the best choice, as a function of the amplifier's Common Mode Rejection Ratio (CMRR) and stray coupling capacitances. Conclusions are verified experimentally using a biopotential amplifier specially designed for this test.     

A general approach for obtaining joint representations in signalanalysis. I. Characteristic function operator method

A general approach for obtaining joint representations for arbitrary physical quantities is presented. The characteristic function operator method of Moyal (1949) and Ville (1960) and generalized by Cohen (1966, 1976) and Scully and Cohen (1987) for the time-frequency case is developed for arbitrary variables     

Energy-based scatter correction for 3-D PET scanners using NaI(T1) detectors

Earlier investigations with BGO positron emission tomography (PET) scanners showed that the scatter correction technique based on multiple acquisitions with different energy windows are problematic to implement because of the poor energy resolution of BGO (22%), particularly for whole-body studies. We believe that these methods are likely to work better with NaI(TI) because of the better energy resolution achievable with NaI(TI) detectors (10%). Therefore, we investigate two different choices for the energy window, a low-energy window (LEW) on the Compton spectrum at 400-450 keV, and a high-energy window (HEW) within the photopeak (lower threshold above 511 keV). The results obtained for our three-dimensional (3-D) (septa-less) whole-body scanners [axial field of view (FOV) of 12.8 cm and 25.6 cm] as well as for our 3-D brain scanner (axial FOV of 25.6 cm) show an accurate prediction of the scatter distribution for the estimation of trues method (ETM) using a HEW, leading to a significant reduction of the scatter contamination. The dual-energy window (DEW) technique using a LEW is shown to be intrinsically wrong; in particular, it fails for line source and bar phantom measurements. However, the method is able to produce good results for homogeneous activity distributions. Both methods are easy to implement, are fast, have a low noise propagation, and will be applicable to other PET scanners with good energy resolution and stability, such as hybrid NaI(TI) PET/SPECT dual-head cameras and future PET cameras with GSO or LSO scintillators.     

A Standalone Burst-Mode Receiver With Clock and Data Recovery, Clock Phase Alignment, and RS(255, 239) Codes for SAC-OCDMA Applications

We demonstrate a standalone (no global clock) burst-mode receiver (BMRx) for a 7 times 622 Mb/s incoherent spectral-amplitude-coded optical code-division multiple-access system. The receiver provides the following functions: quantization (intensity noise filtering), clock and data recovery, burst-mode functionality (automatic phase acquisition) using a clock phase aligner (CPA), framing (for byte synchronization), and forward-error correction (FEC) using a (255, 239) Reed-Solomon decoder. The receiver provides an instantaneous (zero preamble bit) phase acquisition time for any phase step (plusmn2pi rads) between consecutive packets. With the CPA, we report a zero packet loss ratio (PLR) for up to four simultaneous users and more than a 300-fold improvement in the PLR for a fully loaded system. The BMRx also accomplishes more than 2.5 dB of coding gain, and achieves error-free (bit-error rate ) operation for a fully loaded system.     

Optimal low-complexity detection for space division multiple access wireless systems

A symbol detector for wireless systems using space division multiple access (SDMA) and orthogonal frequency division multiplexing (OFDM) is derived. The detector uses a sphere decoder (SD) and has much less computational complexity than the naive maximum likelihood (ML) detector. We also show how to detect non-constant modulus signals with constrained least squares (CLS) receiver, which is designed for constant modulus (unitary) signals. The new detector outperforms existing suboptimal detectors for both uncoded and coded systems.     

Thin-stratified medium fast-multipole algorithm for solvingmicrostrip structures

An accurate and efficient technique called the thin-stratified medium fast-multipole algorithm (TSM-FMA) is presented for solving integral equations pertinent to electromagnetic analysis of microstrip structures, which consists of the full-wave analysis method and the application of the multilevel fast multipole algorithm (MLFMA) to thin stratified structures. In this approach, a new form of the electric-field spatial-domain Green's function is developed in a symmetrical form which simplifies the discretization of the integral equation using the method of moments (MoM). The patch may be of arbitrary shape since their equivalent electric currents are modeled with subdomain triangular patch basis functions. TSM-FMA is introduced to speed up the matrix-vector multiplication which constitutes the major computational cost in the application of the conjugate gradient (CG) method. TSM-FMA reduces the central processing unit (CPU) time per iteration to O(N log N) for sparse structures and to O(N) for dense structures, from O(N³) for the Gaussian elimination method and O(N²) per iteration for the CG method. The memory requirement for TSM-FMA also scales as O(N log N) for sparse structures and as O(N) for dense structures. Therefore, this approach is suitable for solving large-scale problems on a small computer     

Decision-feedback differential detection of MDPSK for flat Rayleighfading channels

In this paper, decision-feedback differential detection (DF-DD) of M-ary differential phase-shift keying (MDPSK) signals, which has been introduced previously for the additive white Gaussian noise (AWGN) channel by Leib et al. (1988) and Edbauer (1992), is extended to flat Rayleigh fading channels. The corresponding DF-DD metric is derived from the multiple-symbol detection (MSD) metric and for genie-aided DF-DD, an exact expression for the bit-error rate (BER) of QDPSK (M=4) is calculated. Furthermore, the dependence of BER on the power spectrum of the fading process is investigated for feedback filters of infinite order. It is shown that in this case, for ideally bandlimited fading processes, the error floor of conventional differential detection (DD) can be removed entirely. Simulation results confirm that both MSD and DF-DD with feedback filters of finite order can reduce the error floor of conventional DD significantly. DF-DD thereby causes considerably less computational load     

An Integrated Therapeutic Delivery System for Enhanced Treatment of Hepatocellular Carcinoma

Nanomaterials hold promise for the treatment of human carcinomas but integrating multiple functions into a single drug carrier system remains challenging. Herein, an integrated therapeutic delivery system for human hepatocellular carcinoma (HCC) treatment is reported, which is based on rhodamine B (RhB) end‐labeled cationic poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) and hydrophobic poly(3‐azido‐2‐hydroxypropyl methacrylate) (PGMA‐N₃) segments equipped with a covalently bound galactose. This biocompatible and safe platform RhB‐PDMAEMA25‐c‐PGMA50‐Gal micelles (Gal‐micelles) offers four advantages: (1) Galactose ligands enhance cellular uptake by targeting the asialoglycoprotein receptor (ASGPR) that is overexpressed on HCC cell lines surfaces; (2) RhB end‐labeling facilitates real‐time imaging for tracking both in vitro and in vivo; (3) the acidic tumor microenvironment protonates the carrier system for efficient drug release as well as gene transfection, (4) codelivery of anticancer drug doxorubicin (DOX) and B‐cell lymphoma 2 small interfering RNA (Bcl‐2 siRNA) works synergistically against tumor growth in both subcutaneous and orthotopic HCC bearing mouse models. This integrated therapeutic delivery system holds potential for future clinical HCC treatment.     

High-resolution transmission electron microscopy study of Ca(3)Co(4)O(9)

The crystal structure of Ca(3)Co(4)O(9) was investigated using high-resolution transmission electron microscopy (HRTEM) and the image-simulation method. The c(*) was 10.8A and the b parameters were 4.56A for the Ca(2)CoO(3) block and 2.82A for the CoO(2) sheet. The [110] zone axis HRTEM images confirmed that Ca(3)Co(4)O(9) has a modulated layered structure with modulation. For the first time, the atomic positions of the Ca and Co atoms in the Ca(2)CoO(3) block were identified, corresponding to three rows of dark spots in the [110] direction. The observed HRTEM images for Ca(2)CoO(3) agreed well with the calculated images based on the structural model obtained by the Rietveld refinement method.     

Modular design and improvement of the management system in the smart home with the use of interval multiset estimates

The paper addresses modular design and improvement/extension of the management system in the smart home and the building automation system (BAS). The design procedure is based on the hierarchical morphological multicriteria design (HMMD) approach: (a) construction of a tree-like system model, (b) generation of design alternatives for leaf nodes of the system model, (c) the bottom-up process: (i) selection of design alternatives for system parts/components and (ii) composition of the selected alternatives into a resultant combination. Here, the HMMD approach with interval multiset estimates for design alternatives is used. The system improvement scheme is based on the following: (a) upgrade of the system components (strategy 1), (b) system extension by adding an additional part (strategy 2). The multiple choice problem with interval multiset estimates for improvement operations is used in system improvement procedure. Two basic applied illustrative numerical examples are considered: (1) a modular management system for the smart home and (2) a modular building automation system consisting of four parts.     

Linear binary shift register circuits utilizing a minimum number of mod-2 adders

A family of linear binary shift register circuits is described in terms of generator polynomialsg(x)which require fewer mod-2adders than those derived from the companion matrices. These circuits are derived from various combinations of the functionsa(x), b(x), andx^{d}ing(x) = 1 + a(x)x^{d}b(x)andc(D), e(D), andD^{m}of the reciprocal polynomialg^{ast}(x) = f(D) = 1 + c(D)D^{m}e(D). Tables are provided for all simplifications thus achievable for primitive polynomial of degrees5through9, and for some nonprimitive polynomials.     

Effects of record length selection on the accuracy of spectralestimates of heart rate variability: a simulation study

To evaluate the effects of record length selection on the accuracy of spectral estimates of heart rate variability (HRV), a simulation study was carried out using a set of 58 signals obtained by autoregressive (AR) fitting a representative sample of real HRV signals. Four record lengths of 180, 300, 420, and 540 s were considered. Spectral estimation was performed by both the Blackman-Tukey (B-T) and AR methods. Accuracy was assessed for: (1) point spectral estimates, by computing the normalized averaged bias (NAB) and variance (NAV); and (2) the most commonly used spectral parameters [total power (TP) and the powers in the bands: very low frequency (VLF) (0÷0.04 Hz), low frequency (LF) (0.04÷0.15 Hz), and high frequency (HF) (0.15÷0.45 Hz)], by computing the normalized bias (NB) and variance (NV). The results are: whatever the record length considered, the 90th percentiles (90P) of the NAB were <10%, whereas those of the NB were <9% for TP, LF, and HF powers, and <14% for the VLF power, in both methods. The NAV was proportional to the reciprocal of record length, showing high 90P values for the shortest record length (26.4% for B-T and 44.2% for AR). The NV showed the same trend but 90P values were much lower (<8% for TP, LF, and HF powers and <19% for VLF power, in both methods). In the final part of the paper a procedure for the computation of approximate upper bounds of the relative absolute error of spectral measures at each record length, based on the knowledge of the NE and NV, is presented     

Annihilation density distribution calculations for medically important positron emitters

The effect of positron range on the image-plane resolution of tomographic images is evaluated through calculations based on a model which employs beta-decay energy spectra and an empirical range formula. Predicted range distribution functions are compared with published measurements for three medically important positron emitters: (11 )C, (68)Ga, and (82)Rb. The effect of tomographic slice thickness on point-source annihilation distribution functions is also demonstrated. Line-spread functions are calculated using the model, for the above isotopes as well as for (18)F, (15)O, and (13)N. Image-plane resolution predictions are made for high-resolution positron cameras for various positron emitting isotopes with end-point energies up to 4 MeV.     

32nm CMOS工艺技术挑战

根据国际半导体技术发展蓝图(international technology roadmap for semiconductor,ITRS),CMOS技术将于2009年进入32nm技术节点.然而,在CMOS逻辑器件从45nm向32nm节点按比例缩小的过程中却遇到了很多难题.为了跨越尺寸缩小所带来的这些障碍,要求把最先进的工艺技术整合到产品制造过程中.文中总结并讨论了可能被引入到32nm节点的新的技术应用,涉及如下几个方面:浸入式光刻的延伸技术、迁移率增强衬底技术、金属栅/高介电常数栅介质(metal/high-k,MHK)栅结构、超浅结(ultra-shallow junction,USJ)以及其他应变增强工程的方法,包括应力邻近效应(stress proximity effect,SPT)、双重应力衬里技术(dualstress liner,DSL)、应变记忆技术(stress memorization technique,SMT)、STI和PMD的高深宽比工艺(high aspect ratio process,HARP)、采用选择外延生长(selective epitaxial growth,SEG)的嵌入SiGe(pFET)和SiC(nFET)源漏技术、中端(middle of line,MOL)和后端工艺(back-end of line,BEOL)中的金属化以及超低k介质(ultra low-k,ULK)集成等问题.     

Capacity results for the discrete memoryless network

A discrete memoryless network (DMN) is a memoryless multiterminal channel with discrete inputs and outputs. A sequence of inner bounds to the DMN capacity region is derived by using code trees. Capacity expressions are given for three classes of DMNs: (1) a single-letter expression for a class with a common output, (2) a two-letter expression for a binary-symmetric broadcast channel (BC) with partial feedback, and (3) a finite-letter expression for push-to-talk DMNs. The first result is a consequence of a new capacity outer bound for common output DMNs. The third result demonstrates that the common practice of using a time-sharing random variable does not include all time-sharing possibilities, namely, time sharing of channels. Several techniques for improving the bounds are developed: (1) causally conditioned entropy and directed information simplify the inner bounds, (2) code trellises serve as simple code trees, (3) superposition coding and binning with code trees improves rates. Numerical computations show that the last technique enlarges the best known rate regions for a multiple-access channel (MAC) and a BC, both with feedback. In addition to the rate bounds, a sequence of inner bounds to the DMN reliability function is derived. A numerical example for a two-way channel illustrates the behavior of the error exponents.     

Using repair-depot system reliability to determine the distributionof supportability turn-around time

Assuming constant repair times, Linton, et al. (1995) used an `expression for the reliability of the system for repairing failed units (FU) at a repair-depot' to compute the longest repair time for a newly failed unit (NFU) which assures a given reliability level (also termed the NFU supportability turn-around time, STAT) in terms of the: (1) constant failure rate for all components, number of spares (s) on-hand; (2) number (n) of FU either `under repair' or `scheduled to begin repair in the future'; and (3) downstream repair completion times (DRCT) for FU. Since subtraction of the repair time for a NFU from its STAT-value yields the NFU's latest repair start-time (LRST) which assures a given repair-depot system reliability (RDSR), STAT-values are important for scheduling RST. This paper assumes that repair time is a random variable and, consequently, DRCT is a random variable. As shown in Linton, et al, (1995), STAT is the zero of a nonlinear, nonpolynomial function of DRCT; thus, STAT is also a random variable, and determining the distribution of STAT is a stochastic root-finding problem. For n=1 and s⩾0, numerical analysis and probability theory are used to find the Cdf and pdf of STAT in terms of any repair time pdf. Using the pdfs for STAT and repair time, expressions are derived for: (1) E{LRST} for a NFU; and (2) q=Pr{(repair time+c)相似文献   

NMF-SVM based CAD tool applied to functional brain images for the diagnosis of Alzheimer's disease

This paper presents a novel computer-aided diagnosis (CAD) technique for the early diagnosis of the Alzheimer's disease (AD) based on nonnegative matrix factorization (NMF) and support vector machines (SVM) with bounds of confidence. The CAD tool is designed for the study and classification of functional brain images. For this purpose, two different brain image databases are selected: a single photon emission computed tomography (SPECT) database and positron emission tomography (PET) images, both of them containing data for both Alzheimer's disease (AD) patients and healthy controls as a reference. These databases are analyzed by applying the Fisher discriminant ratio (FDR) and nonnegative matrix factorization (NMF) for feature selection and extraction of the most relevant features. The resulting NMF-transformed sets of data, which contain a reduced number of features, are classified by means of a SVM-based classifier with bounds of confidence for decision. The proposed NMF-SVM method yields up to 91% classification accuracy with high sensitivity and specificity rates (upper than 90%). This NMF-SVM CAD tool becomes an accurate method for SPECT and PET AD image classification.