On the detection of dominant points on digital curves

A parallel algorithm is presented for detecting dominant points on a digital closed curve. The procedure requires no input parameter and remains reliable even when features of multiple sizes are present on the digital curve. The procedure first determines the region of support for each point based on its local properties, then computes measures of relative significance (e.g. curvature) of each point, and finally detects dominant points by a process of nonmaximum suppression. This procedure leads to the observation that the performance of dominant points detection depends not only on the accuracy of the measure of significance, but also on the precise determination of the region of support. This solves the fundamental problem of scale factor selection encountered in various dominant point detection algorithms. The inherent nature of scale-space filtering in the procedure is addressed, and the performance of the procedure is compared to those of several other dominant point detection algorithms, using a number of examples     

Power Doppler ultrasound evaluation of the shear rate and shear stress dependences of red blood cell aggregation

The use of power Doppler ultrasound at 10 MHz is evaluated as a method to study the shear rate and the shear stress dependences of red blood cell aggregation. This evaluation was based on six in vitro experiments conducted in a 1.27-cm diameter tube under steady flow conditions. Porcine whole blood was circulated in the flow model at flow rates ranging between 125 to 1500 ml/min (mean shear rate across the tube ranging between 6 and 74 s-1). For each flow condition, the variation of the Doppler power across the tube and the velocity profile were measured by moving the Doppler sample volume across the tube diameter. For each radial position, the shear rate within the Doppler sample volume was also determined by considering the radial power pattern of the ultrasound beam. To estimate the shear stress within the Doppler sample volume, the apparent viscosity of blood samples withdrawn from the flow model was measured for each experiment. The variation of the Doppler power as a function of the shear rate within the sample volume showed a rapid reduction of the power between 1 and 5 s-1, a transition region between 5 and 10 s-1, and a very slow reduction beyond 10 s-1. Little variation of the Doppler power was measured for shear stress higher than 2 dyn/cm2. The maximum Doppler power for all flow rates was usually found near the center of the tube. Based on the ultrasonic scattering models, which predict that the Doppler power is related to the volume square of the scatterers, the method described in the present study showed a very high sensitivity to the presence of red blood cell aggregation for shear rates below 10 s-1.     

Performance of FFH/BFSK product combining receiver over aRician-fading channel with partial-band jamming

A theoretical performance evaluation for an FFH/BFSK spread spectrum product combining receiver over a Rician-fading channel in the presence of partial-band jamming and AWGN is presented. The BER of this receiver is better than that of a linear combining receiver for a strong direct signal, and improvement is significant when diversity is increased     

Performance analysis of an FFH/BFSK linear-combining receiveragainst multitone jamming

A computationally efficient bit-error rate (BER) expression for a fast frequency-hopping binary frequency-shift-keying (FFH/BFSK) spread-spectrum system is derived based on Taylor-series expansion of the central differences. The FFH system employs a soft-decision linear-combining receiver against the worst-case band multitone jamming (MTJ) and additive white Gaussian noise. The analytical results are shown to match closely with the BER results based on simulation. This approach allows us to efficiently analyze the performance of the linear-combining receiver with higher diversity levels, which is otherwise mathematically intractable     

Linked genes for calmodulin and E2 ubiquitin-conjugating enzyme in Trichomonas vaginalis

In searching the genomes of early-diverging protists to study whether the possession of calmodulin is ancestral to all eukaryotes, the gene for calmodulin was identified in Trichomonas vaginalis. This flagellate is a member of the Parabasalia, one of the earliest lineages of recognized eukaryotes to have diverged. This sequence was used to isolate a homologous 1.250-kb fragment from the T. vaginalis genome by inverse polymerase chain reaction. This fragment was also completely sequenced and shown to contain the 3' end of the single-copy calmodulin gene and the 3' end of a gene encoding a protein with high similarity to E2 ubiquitin-conjugating enzymes, a family which has previously only been identified in animals, plants, and fungi. Phylogenetic analysis of 50 members of the E2 family distinguishes at least nine separate subfamilies one of which includes the T. vaginalis E2-homologue and an uncharacterized gene from yeast chromosome XII.     

Cigarette smoking and risk of prostate cancer: a population-based case-control study in Ontario and British Columbia, Canada

The relationship between cigarette smoking and risk of prostate cancer was examined in a case-control study conducted in Ontario and British Columbia, Canada. In each centre, cases were men with a histologically confirmed diagnosis of adenocarcinoma of the prostate notified to the provincial cancer registry. In Ontario, controls were selected randomly from assessment lists maintained by the Ontario Ministry of Revenue and were frequency matched to the cases on age. In British Columbia, controls were also frequency matched to the cases on age and were selected randomly from a roster maintained by the Medical Services Plan of British Columbia. The study in Ontario was conducted between April 1990 and April 1992, and that in British Columbia was conducted between January 1989 and December 1991. In all, the study included 408 cases (207 in Ontario and 201 in British Columbia) and 407 controls (207 in Toronto and 200 in British Columbia (one case was unmatched). Overall, there was little variation in risk of prostate cancer with pack-years of cigarette consumption (filter and non-filter cigarettes combined), and there was no evidence for an effect confined to filter or non-filter cigarettes. There was some evidence for a positive association with non-filter cigarettes in British Columbia, but on formal testing for heterogeneity, this finding was not inconsistent with the absence of an association in Ontario. There was also little variation in risk by years since first smoked or (for ex-smokers) by years since quitting. These data provide little support for an association between cigarette smoking and prostate cancer risk.     

Iterative reduced-complexity multiuser detection based on Chase decoding for synchronous turbo-coded CDMA system

The conventional multiuser detector (MUD) based on the a posteriori probability (APP) algorithm has an exponential computational complexity in terms of the number of users. In this paper, we propose a low-complexity iterative multiuser receiver for synchronous turbo-coded code-division multiple-access (CDMA) systems. The proposed receiver is based on the Chase decoding algorithm that was previously used to decode turbo product codes. Simulation results show that the proposed receiver can significantly reduce the computational complexity with slight performance degradation compared with the APP MUD over highly correlated channels. Moreover, in this paper, we develop a numerical approach to analyze the convergence behavior of iteratively decoded CDMA channels based on density evolution technique. Analytical results are presented and shown to provide a reasonable match with what is observed in simulation.     

Iterative multiuser detection with Gauss-Seidel soft detector asfirst stage for asynchronous coded CDMA

A new iterative detection and decoding structure for asynchronous convolutionally coded and turbo coded CDMA is proposed. The new scheme is based on the combination of Gauss-Seidel soft detection and parallel interference cancellation. The complexity of the new scheme is linear to the number of users. It is shown that for a heavily loaded system, near-optimal performance can be obtained