Stresses around a pin-loaded hole in orthotropic plates with arbitrary loading direction

Lekhnitskii's method of complex stress function is extensively used to solve the pin-loaded circular hole problem in an infinite orthotropic plate. The approach is similar to the one used earlier by the authors, but extended into a more general fashion. The direction of pin-load is arbitrary and the presence of friction is considered.An analytic solution which satisfies the major displacement boundary conditions on the pin-loaded hole has been obtained. Certain parameters are introduced for simplifying the expressions. These formulas can be used for computing the stress distribution around a pin-loaded hole and estimating the effect of direction of the pin-load and the presence of friction. The degree of such an effect depends on the orthotropy of the material. Some numerical results have been calculated and presented in this paper. They are compared with other results available in the literature.     

Joint detection for OFDM-CDMA communications in multipath fading channels

This paper proposes and compares four block joint detection algorithms for the orthogonal frequency division multiplexing (OFDM)-code division multiple access (CDMA) communication systems. The performance of the proposed OFDM-CDMA joint detectors with orthogonal and non-orthogonal spreading sequences are investigated in mobile radio channels. The proposed OFDM-CDMA detectors are zero forcing (ZF) and minimum mean square error (MMSE) detectors with decision feedback (DF) structures. The proposed joint detectors do not require discrete Fourier transform (DFT) or fast Fourier transform (FFT) operations and can be used to compensate the channel distortion. Hence for hardware implementation, the proposed detectors are more efficient than the conventional methods. The channel sorting method offers approximately 2 dB gain for the DF joint detectors and reduces the impairing effect of error propagation. The bit error rate (BER) performance of orthogonal codes is better than that of non-orthogonal ones in time varying channels. Simulation examples are given to demonstrate the effectiveness of the proposed detectors.     

Management of small infected tibial defects with antibiotic-impregnated autogenic cancellous bone grafting

Between January of 1991 and December of 1993, 36 patients who had tibia fractures complicated by small infected tibia defects were treated at the authors' service. The group included 30 men and 6 women whose average age was 36.5 years (range, 18-72 years). The average follow-up period was 3.7 years. By using the Cierney-Mader staging classification of chronic osteomyelitis, 26 of 36 patients (72%) were stage 4A and 10 of 36 patients (28%) were stage 4B. Ten patients required muscle transfer. All patients were treated with a two-stage protocol. In the first stage, antibiotic-impregnated polymethylmethacrylate bead chains were used to obliterate the debrided osseous defect. In the second stage, the beads were removed, and the defects were reconstructed with antibiotic-impregnated autogenic cancellous bone graft. The time between the first and second stage was 2 to 8 weeks for patients without muscle transfer and 8 to 12 weeks for the patients with muscle transfer. The bone defects ranged from 2 to 4 cm. Wound healing and bony union were achieved in all patients. Only two patients had recurrent infections. The infection arrest rate was 94.4%. Minor pin tract infection of the external skeletal fixation was seen in two patients. Two patients developed skin rashes secondary to antibiotic therapy. Radiographs at an average follow-up of 3.7 years showed good consolidation and hypertrophy of grafted bones in all patients. After 3 to 5 years of follow-up, our results suggest that the use of impregnating antibiotics have no adverse effects on autogenic cancellous bone graft incorporation and may help to eliminate infection. This treatment protocol provided rapid recovery from osteomyelitis. The use of antibiotic-impregnated autogenic bone graft seems to be an effective and safe method for the management of small infected tibial defects.     

Adaptive blind equalization using second- and higher orderstatistics

This paper presents two classes of adaptive blind algorithms based on second- and higher order statistics. The first class contains fast recursive algorithms whose cost functions involve second and third- or fourth-order cumulants. These algorithms are stochastic gradient-based but have structures similar to the fast transversal filters (FTF) algorithms. The second class is composed of two stages: the first stage uses a gradient adaptive lattice (GAL) while the second stage employs a higher order-cumulant (HOC) based least mean squares (LMS) filter. The computational loads for these algorithms are all linearly proportional to the number of taps used. Furthermore, the second class, as various numerical examples indicate, yields very fast convergence rates and low steady state mean square errors (MSE) and intersymbol interference (ISI). MSE convergence analyses for the proposed algorithms are also provided and compared with simulation results     

Performance analyses of adaptive noncoherent receivers for MC‐CDMA communications

In this paper, we propose differential phase‐shift keying (DPSK) noncoherent receivers for multicarrier code division multiple access systems in multipath channels. The noncoherent receivers are composed of a linear equalizer and a decision‐feedback differential detector to detect DPSK signals. The performances of the proposed noncoherent receivers can be improved by increasing the number of feedback symbols. For an infinite number of feedback symbols, the optimum weight can be derived analytically, and the performances of the proposed noncoherent receivers approach that of the conventional coherent receiver. For adaptation of the equalizer coefficients, modified least mean square and recursive least squares algorithms are proposed. Furthermore, the reduced‐rank schemes are proposed to simplify the system complexities. Some simulation examples are given to show the system performances of the four proposed receivers. Copyright © 2014 John Wiley & Sons, Ltd.     

Turbo coded multiple-antenna systems for near-capacity performance

For a turbo coded BLAST (Bell LAbs Space-Time architecture) system with N_t transmit antennas and N_r receive antennas, there is a significant gap between its detection threshold and the capacity in case N_t > N_r. In this paper, we show that by introducing a convolutional interleaver with block delay between the BLAST mapper and the turbo encoder, the threshold can be improved. Near-capacity thresholds can be achieved for some cases. To take advantage of the low detector complexity in Alamouti STBC (space-time block code), we also investigate a STBC system, which is the concatenation of the Alamouti STBC with a turbo trellis coded modulation. By using a proper labelling and adding a convolutional interleaver with block delay to such a STBC system, we achieve both lower error floors and lower thresholds.     

Metabolic Activation of Chrysene by Human Hepatic and Pulmonary Cytochrome P450 Enzymes

The metabolic activation of chrysene, a weak carcinogen found in tobacco smoke, gasoline engine exhaust, and other environmental sources was analyzed in 18 human hepatic and 11 pulmonary microsomal samples. The major metabolites formed were 3,4-dihydroxy-3,4-dihydrochrysene (chrysene-3,4-diol), chrysene-1,2-diol and to lower extents phenols. Chrysene-5,6-diol was found in trace amounts only. All human liver samples formed the proximate carcinogen chrysene-1,2-diol (1.3–5.8 pmol/mg protein/min). Comparable results were seen with pulmonary microsomes, but metabolites were formed to about 10 fold lower extents. Here the most prominent metabolite was chrysene-1,2-diol. Catalytic activities known to be associated with specific cytochrome P450s were determined and correlated with the levels of metabolites formed in each sample. The results of the correlation analysis as well as studies with the inhibitor α-naphthoflavone indicated that hepatic cytochrome P450 1A2 plays a major role in the formation of the proximate carcinogen chrysene-1,2-diol and most of the other metabolites. The formation of metabolites in human lung seems mainly to be due to cytochrome P450 1A1 activity. These results demonstrate that cytochrome-P450 1A mediated metabolic activation processes occur for chrysene in human liver and lung.     

Long-term results of radiofrequency catheter ablation in patients with multiple accessory pathways

Information on the long-term results of radiofrequency catheter ablation in a large group of patients with multiple accessory pathways (APs) was not available. This study included 858 patients with Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency catheter ablation: 73 patients (8.5%) had multiple APs. Sixty-six patients had 2 APs, 5 had 3 APs, 1 had 4 APs, and 1 had 5 APs. The most common combination pattern of these pathways were concealed APs (38 patients, 52%). Localization of accessory pathways showed a higher incidence of right free wall (22% vs 11%, p < 0.05), anteroseptal, and midseptal APs (9% vs 5%, p < 0.05) in patients with multiple APs than in patients with 1 AP. The most common anatomic sites for multiple APs were 2 APs in the left wall (21 patients, 28%). Although the success rate was similar (98% vs 99%, p > 0.05), procedure time (3.1 +/- 1.2 vs 2.0 +/- 1.1 hours, p < 0.05) and radiation exposure time (48 +/- 26 vs 29 +/- 19 minutes, p < 0.05) were longer in patients with multiple APs. The recurrence rate was higher in patients with multiple APs (9.5% vs 2.5%, p < 0.05), and the most common site of recurrent APs was in the left free wall (7.2%); in contrast, it was in the right free wall in patients with 1 AP. These findings demonstrated that a high success rate of radiofrequency catheter ablation was found in patients with multiple APs; however, the higher recurrence rate in patients with multiple APs should be considered.     

Improvement of arterial oxygenation by selective infusion of prostaglandin E1 to ventilated lung during one-lung ventilation

Stride length, stance width and gait symmetry were measured as parameters of gait analysis in young (5 months) and old (28 months) Sprague-Dawley rats following 3 months of treadmill running as well as in sedentary controls. Stride length decreased significantly with age and increased significantly following training in both young and old rats. Means of stance width increased significantly with age, but were unaffected by training. Gait symmetry declined with age; however, treadmill running counteracted the decline of gait symmetry. It was concluded that treadmill running compensates for or prevents age-related changes in the neuromuscular function of rats, which lead to gait deterioration.