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This work investigates the effect of channel noise on the performances of the constant modulus algorithm (CMA), the multimodulus algorithm (MMA), and a phase tracker (PT), following the CMA for carrier phase recovery, when various symmetrical two-dimensional complex-valued source constellations are used. The contributions of this work are two-fold. First, a generalized formulation of the relocation of stationary points toward the origin owing to channel noise is derived for both the CMA and the MMA, allowing their sensitivity to channel noise to be explicitly compared when various constellations are used. Second, the curvatures of the error surface at the stationary points in both the radial and the angular directions are reduced in a way that is linearly proportional to the square of the distances between the stationary points and the origin as the stationary points of the CMA and the MMA relocate toward the origin in the presence of additive channel noise. The reduction of the error surface curvature in the radial direction reduces the rate of blind equalization convergence, whereas the reduction in the angular direction degrades the capacity for carrier phase recovery.

This paper analyzes and compares the robustness of the constant modulus algorithm (CMA) and multimodulus algorithm (MMA) in the presence of additive channel noise when the channel satisfies the zero-forcing conditions. A generalized formulation of the relocation of stationary points toward the origin in terms of signal-to-noise ratio (SNR) was developed for both the CMA and the MMA to facilitate the comparison of the sensitivity to channel noise of CMA with that of MMA for various source constellations. Relationships between the relocation of the stationary points for the MMA and CMA were derived. Simulation results appear to confirm the main results of this work, regarding the sensitivity to channel noise when the fractionally spaced CMA (FS-CMA) and fractionally spaced MMA (FS- MMA) criteria were applied with various sources.

Sixty-nine patients with a uterine sarcoma were reviewed in detail. The histological types included 32 leiomyosarcomas, 10 endometrial stromal sarcomas, 5 rhabdomyosarcomas, 14 mixed mesodermal sarcomas, and 3 fibrosarcomas. The type of sarcoma was not classified in 5 cases. Using International Federation of Gynecology & Obstetrics (FIGO) classification, 29 patients were categorized as Stage I, 5 as Stage II, 11 as Stage III, and 7 as Stage IV. Three percent of patients had a history of pelvic radiotherapy. In any given stage, patients with leiomyosarcoma had a better survival than other histologic types. Extent of disease at the diagnosis was directly related to the survival. Fifty-eight percent of patients with Stage I survived disease-free for 5 years, compared to 40% with Stage II and none with Stages III and IV. Despite the varied and individualized treatment policies adopted in these patients, comparable survival was noted in patients treated with surgery only and those with combined surgery and radiation. Fewer pelvic failures were seen in the combined treatment group. Sites of failure were analyzed in the 30 patients. Distant metastases occurred in 73.3% of the patients. Pulmonary metastases occurred in all the patients who failed with leiomyosarcoma and 53% of the patients with other tumor types. Hepatic metastases were second in frequency with non-leiomyosarcoma patients. Adjuvant postoperative radiotherapy is recommended for (greater than Stage I) leiomyosarcoma and for all patients with other tumor types. We suggest that systemic chemotherapy be incorporated in the comprehensive treatment of these tumors.

Quantitative determination of the effect of cavities on the dose measured by an ionization chamber at a suitable point behind the cavity has shown that the percentage of dose increase varies markedly as.a function of the build-up layer, the diameter and thickness of the cavity, and the electron energy. A study of dose distribution showed that cylindrical cavities similar in size to those encountered in the head and neck may result in a localized dose of up to 160% of that measured at the depth of maximum dose within a homogeneous tissue-equivalent medium.

X rays from a 32-McV betatron were used in rotational therapy for deep tumors. Tissue-air ratios for 14 × 14 cm fields at a source-to-dosimeter distance of 104 cm do not vary significantly as a function of field size or source-to-dosimeter distance.

We performed a retrospective analysis of 45 patients with malignant melanoma who were treated with radiation therapy at the University of Illinois and Mercy Hospitals, Chicago, between 1%2 and 1978. Thirty-nine patients received 69 courses of radiation therapy for metastatic disease, six patients received radiotherapy with curative intent for localized lesions. We analyzed some of the factors governing the response to radiation therapy. Although most of the patients were treated with conventional daily fractions, their response seemed comparable to that reported by other investigators using large fractions. Until the issue of optimum fraction size is settled by a comparative trial, our experience indicates that conventional fractionation may be equally effective.

The perturbation of dose distribution caused by small air cavities during electron-beam therapy is a well known phenomenon (1). When a void is present in a volume of material irradiated by highenergy electrons, more electrons will be scattered into the void than will be scattered out. This results in an increased dose in the material near the surface of the void on the side opposite the incident beam. This dose is greater than would be measured if the complete segment of material bounded by the edges of the void in the dimension parallel to the beam and of infinite dimensions perpendicular to the beam were removed to form the void. The increase in dose, which is a complex function of the dimensions of the void, the depth of the void below the surface of the material, and of the energy of the electrons, may result in severe radiation reactions during therapy, particularly in the treatment of tumors of the head and neck. In this investigation a Lucite phantom was constructed which allowed the diameter of th...

The increase in dose adjacent to voids was systematically measured as a function of void diameter for combinations of incident electron energy and void thickness, utilizing build-up layer thicknesses of 1/4 inch, 1/2 inch, and 1 inch. Plots of “percentage void dose” vs. void diameter are shown. Marked changes in dose are observed when the build-up layer thickness is varied.

Neuroblastoma is primarily a disease of infants and children. It is not rare, since some 700 cases are reported in the literature. Among the malignancies of children it is probably second only to leukemia. The features of this disease have been reported in detail by others.2,8,10,12,14,15,18 The tumor may arise from any part of the sympathetic nervous system, but the usual site is the adrenal gland. The commonest sites of metastasis are the skeleton and the liver, but the concept that skeletal metastasis accompanies a primary left adrenal tumor (Hutchison syndrome) and liver metastasis, a right adrenal tumor (Pepper syndrome), as suggested by Frew,5has repeatedly been refuted.7,8,10,11The usual presenting sign is progressive enlargement of the upper abdomen caused by the primary tumor, liver metastases, retroperitoneal nodal metastases, ascites or combinations of these. Among the skeletal metastases, those to the skull are most frequent and may