Simultaneous broadcasting of analog FM and digital audio signals bymeans of adaptive precanceling techniques

A method for broadcasting digital audio simultaneously with existing analog frequency modulation (FM) radio is presented. The method is based on precomputing the response of the host analog FM signal at the digital receiver and precanceling it at the transmitter. As a result, the digital transmission is free from interference from analog FM. We select the rate and power level of the digital transmission in a manner that the interference the digital data incur on the analog FM signal remains at acceptably low levels. The digital transmission is based on adaptive orthogonal frequency-division multiplexing (OFDM) (adaptive multicarrier). The frequencies and number of carriers of the digital multicarrier modem are judiciously selected in a time-varying fashion so as to cause a negligible distortion in a standard receiver for analog FM. Simulations based on conservative nonoptimized signal design indicate that data rates up to about 130 kb/s inside the 200-kHz FM channel are achievable for acoustic test signals. We present a number of numerical examples where the average digital data use up to 50% of the 200-kHz power spectrum with digital signal power levels 25-35 dB below the analog signal. Due to the resulting variable-rate digital transmission, a control channel is required. A method of precanceling with multiple orthogonal direct-sequence spread-spectrum schemes is also presented     

Phase II study of neoadjuvant concurrent biochemotherapy in melanoma patients with local-regional metastases

Our results with concurrent biochemotherapy in patients with stage IV melanoma have been encouraging. Based on these data, we conducted a phase II study to determine the clinical and histological response rate to neoadjuvant concurrent biochemotherapy in patients with local-regional metastases of cutaneous melanoma (stage III). A total of 65 patients with biopsy-proven, measurable and potentially resectable local-regional disease (nodal, satellite/in-transit metastases and/or local recurrence) were treated with cisplatin 20 mg/m2 intravenously (i.v.) on days 1 to 4, vinblastine 1.5 mg/m2 i.v. on days 1 to 4, dacarbazine 800 mg/m2 i.v. on day 1 only, interleukin-2 9 MIU/m2 per day i.v. by 96 h continuous infusion on days 1 to 4, and interferon-alpha 2a 5 MU/m2 subcutaneously on days 1 to 5, repeated every 3 weeks. Patients underwent surgery after two to four courses of biochemotherapy. Those with tumour regression after two preoperative courses received two additional postoperative courses. Of the 64 patients assessable for clinical response, 28 (44%) had a partial response. Of the 62 patients whose response was assessed histologically, four (6.5%) had no evidence of viable tumour in the surgical specimen (pathological complete remission, pCR) and 27 (43.5%) had a partial response, giving an overall response rate of 50%. Tumour burden did not correlate with response, although patients who achieved a pCR had a significantly lower tumour burden (P = 0.02). Our phase II study indicates that neoadjuvant biochemotherapy is an active treatment for melanoma patients with local-regional metastases. However, it is unclear if biochemotherapy is more active than chemotherapy alone; phase III randomized trials are ongoing to answer this question in patients with stage IV disease.     

Phase I trial of sequential high-dose chemotherapy with escalating dose paclitaxel, melphalan, and cyclophosphamide, thiotepa, and carboplatin with peripheral blood progenitor support in women with responding metastatic breast cancer

A single high-dose cycle of chemotherapy with stem cell support can produce disease-free survival of 15-20% for at least 3 years in women with responding stage IV breast cancer. North American Autologous Bone Marrow Transplant Registry data suggest that a complete response (CR) is the single most important prognostic factor associated with prolonged disease-free survival. Therefore, if sequential high-dose chemotherapy can increase the CR rate, then perhaps an increased proportion of patients will remain disease free. Women with at least a partial response (PR) to induction chemotherapy received three separate high-dose cycles of chemotherapy with peripheral blood progenitor support and granulocyte colony-stimulating factor. The first intensification was a dose escalation of paclitaxel (400-825 mg/ m2), the second intensification was melphalan (180 mg/m2), and the third intensification consisted of 6000 mg/m2 cyclophosphamide (1500 mg/m2/day), 500 mg/m2 thiotepa (125 mg/m2/day), and 800 mg/m2 carboplatin (200 mg/m2/day; CTCb). Thirty-six women were enrolled and 31 completed all three cycles. After the paclitaxel infusion most patients developed reversible predominantly sensory neuropathy. Of the 19 patients with measurable disease, 6 converted to CR, 7 converted to a PR* (the complete resolution of all soft tissue or visceral disease with sclerosis of prior lytic bone lesions), and 2 had a further PR for an overall response rate of 79%. Two patients had no further response and disease in two patients progressed, and thus they were taken off the study before CTCb. Seventy-eight percent are progression-free at a median follow-up of 14 months (range, 3-24+). Three sequential cycles of high-dose chemotherapy are feasible and were administered in this study with no mortality. Single agent paclitaxel at doses up to 825 mg/m2 were well tolerated with moderate reversible toxicity.     

Physical-layer secrecy in AWGN via a class of chaotic DS/SS systems: analysis and design

We study a class of pseudo-chaotic spread spectrum systems for secure communication over additive white Gaussian noise (AWGN) channels, whereby a symbol stream is linearly modulated on a spreading sequence generated by iterating an initial condition through a suitably chosen chaotic map. We compare the uncoded probability of error (Pr(/spl epsiv/)) attainable by intended receivers that know the initial condition to the associated Pr(/spl epsiv/) of unintended receivers that know the modulation scheme but not the initial condition. The sensitive dependence of chaotic sequences on initial conditions, together with the presence of channel noise, can be exploited to provide substantially lower Pr(/spl epsiv/) to intended than to unintended receivers. We develop computationally efficient methods for obtaining tight bounds on the best P r(/spl epsiv/) performance of intended and unintended receivers. In the process, we identify chaotic map attributes that affect the relative Pr(/spl epsiv/) advantages provided to intended receivers and develop methods for designing maps that achieve a target gap between the intended and unintended receiver Pr(/spl epsiv/).     

Bayesian Confidence Bounds for the Weibull Failure Model

The following bounds are derived for the Weibull failure model when the parameter is being characterized by the inverted gamma and uniform probability density functions (pdf); they are lower and upper Bayes-confidence bounds for the scale parameter and lower bounds for the reliability function. To illustrate the results a Monte Carlo simulation was performed to obtain 90% and 95% Bayes-confidence bounds for the scale parameter and lower limits for the corresponding reliability function of the Weibull failure distribution. The consequences that one encounters when the following ``wrong' priors have been chosen to characterize the random behavior of the scale parameter are investigated. The results are compared when the prior pdf of ? is uniform but inverted gamma was used, and vice versa.     

Stress-corrosion crack growth in aluminum alloys

A macroscopic study of the growth of a stress corrosion crack in an aluminum alloy was undertaken by using the optical method of caustics. The dependence of the crack-tip stress intensity factors K_I on the applied stress, as well as on the molarity of a NaCl aqueous solution was studied in detail. The calculation of these quantities was made by taking into account the thickness variation of the specimen due to the corrosive environment. A criterion of the crack growth in terms of the caustics obtained by illuminating the cracked specimen by a light beam was formulated and the corresponding values of the threshold stress intensity factor K_ISCC were accurately determined. Finally, the creation and the evolution of the pits developed at the vicinity of the crack tip was studied and their significance on the mechanisms of fracture of the specimens was examined.     

Maximum-likelihood estimation of a class of chaotic signals

The chaotic sequences corresponding to tent map dynamics are potentially attractive in a range of engineering applications. Optimal estimation algorithms for signal filtering, prediction, and smoothing in the presence of white Gaussian noise are derived for this class of sequences based on the method of maximum likelihood. The resulting algorithms are highly nonlinear but have convenient recursive implementations that are efficient both in terms of computation and storage. Performance evaluations are also included and compared with the associated Cramer-Rao bounds