A Training-Based Iterative Detection/Channel Estimation Scheme for Large Non-Orthogonal STBC MIMO Systems

In this paper, we propose a training-based channel estimation scheme for large non-orthogonal space-time block coded (STBC) MIMO systems.The proposed scheme employs a block transmission strategy where an N-t x N-t pilot matrix is sent (for training purposes) followed by several N-t x N-t square data STBC matrices, where Nt is the number of transmit antennas. At the receiver, we iterate between channel estimation (using an MMSE estimator) and detection (using a low-complexity likelihood ascent search (LAS) detector) till convergence or for a fixed number of iterations. Our simulation results show that excellent bit error rate and nearness-to-capacity performance are achieved by the proposed scheme at low complexities. The fact that we could show such good results for large STBCs (e.g., 16 x 16 STBC from cyclic division algebras) operating at spectral efficiencies in excess of 20 bps/Hz (even after accounting for the overheads meant for pilot-based channel estimation and turbo coding) establishes the effectiveness of the proposed scheme.

A Low-Complexity Algorithm for Intrusion Detection in a PIR-Based Wireless Sensor Network

We present a low-complexity algorithm for intrusion detection in the presence of clutter arising from wind-blown vegetation, using Passive Infra-Red (PIR) sensors in a Wireless Sensor Network (WSN). The algorithm is based on a combination of Haar Transform (HT) and Support-Vector-Machine (SVM) based training and was field tested in a network setting comprising of 15-20 sensing nodes. Also contained in this paper is a closed-form expression for the signal generated by an intruder moving at a constant velocity. It is shown how this expression can be exploited to determine the direction of motion information and the velocity of the intruder from the signals of three well-positioned sensors.

Development of a probe-based blotting technique for the detection of Tobacco streak virus

Digoxigenin (DIG)-labeled DNA probe was developed for a sensitive and rapid detection of the Tobacco streak virus (TSV) isolates in India by dot-blot and tissue print hybridization techniques. DIG-labeled DNA probe complementary to the coat protein (CP) region of TSV sunflower isolate was designed and used to detect the TSV presence at field levels. Dot-blot hybridization was used to check a large number of TSV isolates with a single probe. In addition, a sensitivity of the technique was examined with the different sample extraction methods. Another technique, the tissue blot hybridization offered a simple, reliable procedure and did not require a sample processing. Thus, both non-radioactively labeled probe techniques could facilitate the sample screening during TSV outbreaks and offer an advantage in quarantine services.

New Concepts for PVC Detection

A new scheme is proposed for the detection of premature ventricular beats, which is a vital function in rhythm monitoring of cardiac patients. A transformation based on the first difference of the digitized electrocardiogram (ECG) signal is developed for the detection and delineation of QRS complexes. The method for classifying the abnormal complexes from the normal ones is based on the concepts of minimum phase and signal length. The parameters of a linear discriminant function obtained from a training feature vector set are used to classify the complexes. Results of application of the scheme to ECG of two arrhythmia patients are presented.

Random-Restart Reactive Tabu Search Algorithm for Detection in Large-MIMO Systems

We present a low-complexity algorithm based on reactive tabu search (RTS) for near maximum likelihood (ML) detection in large-MIMO systems. The conventional RTS algorithm achieves near-ML performance for 4-QAM in large-MIMO systems. But its performance for higher-order QAM is far from ML performance. Here, we propose a random-restart RTS (R3TS) algorithm which achieves significantly better bit error rate (BER) performance compared to that of the conventional RTS algorithm in higher-order QAM. The key idea is to run multiple tabu searches, each search starting with a random initial vector and choosing the best among the resulting solution vectors. A criterion to limit the number of searches is also proposed. Computer simulations show that the R3TS algorithm achieves almost the ML performance in 16 x 16 V-BLAST MIMO system with 16-QAM and 64-QAM at significantly less complexities than the sphere decoder. Also, in a 32 x 32 V-BLAST MIMO system, the R3TS performs close to ML lower bound within 1.6 dB for 16-QAM (128 bps/Hz), and within 2.4 dB for 64-QAM (192 bps/Hz) at 10(-3) BER.

Optimum weighting function in bispectral analysis in speckle interferometry - Binary star parity detection

In order to describe the atmospheric turbulence which limits the resolution of long-exposure images obtained using ground-based large telescopes, a simplified model of a speckle pattern, reducing the complexity of calculating field-correlations of very high order, is presented. Focal plane correlations are used instead of correlations in the spatial frequency domain. General tripple correlations for a point source and for a binary are calculated and it is shown that they are not a strong function of the binary separation. For binary separations close to the diffraction limit of the telescope, the genuine triple correlation technique ensures a better SNR than the near-axis Knox-Thompson technique. The simplifications allow a complete analysis of the noise properties at all levels of light.

Detection of a CpA methylase in an insect system: characterization and substrate specificity

A cytosine-specific DNA methyltransferase (EC 2.1.1.37) has been purified to near homogeneity from a mealybug (Planococcus lilacinus). The enzyme can methylate cytosine residues in CpG sequences as well as CpA sequences. The apparent molecular weight of the enzyme was estimated as 135,000 daltons by FPLC. The enzyme exhibits a processive mode of action and a salt dependance similar to mammalian methylases. Mealybug methylase exhibits a preference for denatured DNA substrates.

Detection of edges from projections

In a number of applications of computerized tomography, the ultimate goal is to detect and characterize objects within a cross section. Detection of edges of different contrast regions yields the required information. The problem of detecting edges from projection data is addressed. It is shown that the class of linear edge detection operators used on images can be used for detection of edges directly from projection data. This not only reduces the computational burden but also avoids the difficulties of postprocessing a reconstructed image. This is accomplished by a convolution backprojection operation. For example, with the Marr-Hildreth edge detection operator, the filtering function that is to be used on the projection data is the Radon transform of the Laplacian of the 2-D Gaussian function which is combined with the reconstruction filter. Simulation results showing the efficacy of the proposed method and a comparison with edges detected from the reconstructed image are presented

Detection of IgG, IgA, IgM and IgE Antibodies in Invasive Amoebiasis in Endemic Areas

Entamoeba histolytica-specific serum IgG, IgA, IgM and IgE antibodies were assayed in cases of amoebiasis in an endemic area. Patient groups consisted of amoebic liver abscess (n=18), pre-abscess hepatic amoebiasis (n=22) and amoebic colitis (n=30). Control subjects comprised 26 asymptomatic cyst passers, 13 giardiasis cases, 20 typhoid patients and 24 non-amoebic individuals. Serum IgG was assayed by ELISA, using a monoclonal anti IgG β- galactosidase (IgG β-gal) conjugate, a polyclonal avidin biotin horse radish peroxidase (AB-HRP), and a polyclonal anti IgG horse radish peroxidase (IgG HRP) conjugate. IgA and IgM were assayed by the β-gal ELISA and IgE by AB-HRP. Diagnostically significant IgG and IgA while lower IgM and IgE antibody levels were seen in extraintestinal cases. About 40% of suspected pre-abscess hepatic amoebiasis cases were confirmed by antibody estimation. All isotype levels in most dysentery cases were in the range of the controls.

Detection and characterisation of circulating cysticercal antigens in human cerebrospinal fluid

With biotin labelled and unlabelled immunoglobulin fraction of anticysticercal antibodies raised in rabbits, tandem-enzyme linked immunosorbent assay (T-ELISA), capture-dot immunobinding assay (C-DIA) and reverse passive haemagglutination (RPHA) tests were developed for the detection of cysticercal antigens. The sensitivity levels were respectively, 9 ng ml−1, 2 ng ml−1 and 45 ng ml−1. All three methods were of equal specificity as none of the antigens of Mycobacterium tuberculosis, Japanese encephalitis virus and Echinococcus granulosus reacted with anticysticercal IgG. Cysticercal antigens were detected in the cerebrospinal fluid (CSF) of confirmed neurocysticercosis at sensitivity levels of 91·6% by T-ELISA, 83·33% by C-DIA and 75% by RPHA and specificity levels of >93%. Western analysis of these antigens in CSF showed mainly antigens of 64–68 kDa and 24–28 kDA. By crossed immunoelectrophoresis (CIE) with an intermediate gel technique, five circulating antigens were found to be released from scolex and fluid.

Coordination-Driven Self-Assembly of M3L2 Trigonal Cages from Preorganized Metalloligands Incorporating Octahedral Metal Centers and Fluorescent Detection of Nitroaromatics

The design and preparation of novel M3L2 trigonal cages via the coordination-driven self-assembly of preorganized metalloligands containing octahedral aluminum(III), gallium(III), or ruthenium(II) centers is described. When tritopic or dinuclear linear metalloligands and appropriate complementary subunits are employed, M3L2 trigonal-bipyramidal and trigonal-prismatic cages are self-assembled under mild conditions. These three-dimensional cages were characterized with multinuclear NMR spectroscopy (H-1 and P-31) and high-resolution electrospray ionization mass spectrometry. The structure of one such trigonal-prismatic cage, self-assembled from an arene ruthenium metalloligand, was confirmed via single-crystal X-ray crystallography. The fluorescent nature of these prisms, due to the presence of their electron-rich ethynyl functionalities, prompted photophysical studies, which revealed that electron-deficient nitroaromatics are effective quenchers of the cages' emission. Excited-state charge transfer from the prisms to the nitroaromatic substrates can be used as the basis for the development of selective and discriminatory turn-off fluorescent sensors for nitroaromatics.

A Multiuser Interference Cancellation Scheme for Uplink OFDMA

In uplink orthogonal frequency division multiple access (OFDMA) systems, multiuser interference (MUI) occurs due to different carrier frequency offsets (CFO) of different users at the receiver. In this paper, we present a multistage linear parallel interference cancellation (LPIC) approach to mitigate the effect of this MUI in uplink OFDMA. The proposed scheme first performs CFO compensation (in time domain), followed by K DFT operations (where K is the number of users) and multistage LPIC on these DFT outputs. We scale the MUI estimates by weights before cancellation and optimize these weights by maximizing the signal-to-interference ratio (SIR) at the output of the different stages of the LPIC. We derive closed-form expressions for these optimum weights. The proposed LPIC scheme is shown to effectively cancel the MUI caused by the other user CFOs in uplink OFDMA.

Ring Resonators and Micro Fluidics: Novel Design for Drug/Disease Detection

MEMS systems are technologically developed from integrated circuit industry to create miniature sensors and actuators. Originally these semiconductor processes and materials were used to build electrical and mechanical systems, but expanded to include biological, optical fluidic magnetic and other systems 12]. Here a novel approach is suggested where in two different fields are integrated via moems, micro fluidics and ring resonators. It is well known at any preliminary stage of disease onset, many physiological changes occur in the body fluids like saliva, blood, urine etc. The drawback till now was that current calibrations are not sensitive enough to detect the minor physiological changes. This is overcome using optical detector techniques 1]. The basic concepts of ring resonators, with slight variations can be used for optical detection of these minute disease markers. A well known fact of ring resonators is that a change in refractive index will trigger a shift in the resonant wavelength 5]. The trigger for the wavelength shift in the case discussed will be the presence of disease agents. To trap the disease agents specific antibody has to be used (e. g. BSA).

Development and characterization of monoclonal antibodies against WbSXP-1 for the detection of circulating filarial antigens

The importance of developing effective assays to diagnose, monitor and evaluate human lymphatic filariasis has been emphasized by the World Health Organization. Presently, few immunodiagnostics are available for filarial monitoring programmes. The Wuchereria bancrofti (Wb) SXP-1 parasite protein, with 84% homology to Brugia malayi (Bm) SXP-1, was found to be highly immunogenic. WbSXP-1 is one among the diagnostic candidate molecules that were used for developing a rapid-antibody-flow-through diagnostic kit for filariasis. Studies were initiated with the aim of developing monoclonal antibodies against recombinant WbSXP-1 and prospective applications for the detection of both circulating Wb and Bm antigens in serum samples from infected individuals. The monoclones 1A6C2 of subclass IgG1k, and 2A12F8 of class IgM, specifically detected Wb and Bm microfilaria isolated from patients and did not show cross-reactivity with other filarial recombinant antigens. We anticipate that this work will address the problems faced in the rapid diagnosis of human lymphatic filariasis in endemic areas in developing countries.

Improving fault detection and reliability in FDDI networks

FDDI (Fibre Distributed Data Interface) is a 100 Mbit/s token ring network with two counter rotating optical rings. In this paper various possible faults (like lost token, link failures, etc.) are considered, and fault detection and the ring recovery process in case of a failure and the reliability mechanisms provided are studied. We suggest a new method to improve the fault detection and ring recovery process. The performance improvement in terms of station queue length and the average delay is compared with the performance of the existing fault detection and ring recovery process through simulation. We also suggest a modification for the physical configuration of the FDDI networks within the guidelines set by the standard to make the network more reliable. It is shown that, unlike the existing FDDI network, full connectivity is maintained among the stations even when multiple single link failures occur. A distributed algorithm is proposed for link reconfiguration of the modified FDDI network when many successive as well as simultaneous link failures occur. The performance of the modified FDDI network under link failures is studied through simulation and compared with that of the existing FDDI network.