BACKGROUND: Adenoid cystic carcinoma (ACC) of the head and neck (ACCHN) is a rare tumor of minor salivary, parotid, and submandibular glands. The biologic behavior of the disease is poorly understood, and nonsurgical treatment strategies have yet to be standardized. The long-term prognosis continues to be guarded, with an estimated 10-year survival of <60%. Population-based studies examining ACC are scarce. The authors aimed to analyze incidence rates and survival outcomes for patients diagnosed with ACCHN using national population-based data. METHODS: Data were obtained from the US National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program. Newly diagnosed ACCHN cases reported to SEER from 1973 through 2007 were categorized according to their sex, race, age, year of diagnosis, marital status, treatment interventions, primary tumor site, and disease stage. Incidence of ACCHN and postdiagnosis survival were examined over time and compared across different demographic and disease-related categories. RESULTS: The authors identified 3026 patients with ACCHN. The mean age at diagnosis among those cases was 57.4 years (range, 11-99 years). Analyses of incidence data demonstrated a decline in ACCHN rates between 1973 and 2007, noted across all sexes and races with no detectable inflexion points. The overall 5-year, 10-year, and 15-year survival outcomes for ACCHN patients were 90.3%, 79.9%, and 69.2%, respectively. Females, patients with localized disease, and younger patients were found to have significantly better survival across all time periods (all comparison-specific log-rank P values <0.001).
Abstract. Incoherent scatter (IS) radar measurements of the ionospheric electron density are analyzed for the signature of the magnetic separatrix in the dayside ionosphere by comparison with separatrix locations determined using precipitating electron data from DMSP spacecraft within 1.5 hours in magnetic local time (MLT) of the Sondrestrom radar. A model of photoionization is used to remove its effects from the measured electron density to study the ionization by precipitating particles. The altitude of peak ionization and the peak ionization rate are used to determine whether a magnetic field line is open or closed. We observe that on closed field lines the peak ionization rate is high (> 2200 cm '3 s 'l) or the peak is lower than 140 km in altitude, and on open field lines the peak ionization is low (< 900 cm "• s -•) or the peak is h!gher than 140 km. These rules are used to identify the separatrix with an accuracy of 0.36 ø and a precision of +0.39 ø. This signature of the separatrix is only apparent in the prenoon and noon sectors (0600 to 1300 MLT). In the postnoon sector (1630-1800 MLT) the altitude of peak ionization and the peak ionization rate do not show any systematic difference between the open and closed field line regions. Finally, an example is presented in which the data on the location and motion of the separatrix and IS radar measurements of F region plasma velocity are used to measure the magnetic reconnection rate as a function of the interplanetary magnetic field clock angle.
[1] Both high-frequency (HF) and incoherent scatter (IS) radar have previously been used to identify the open-closed magnetic field separatrix and to measure the magnetospheric reconnection rate. The HF radar signature of open magnetic field on the dayside is a high spectral width in the backscatter Doppler spectrum. The IS radar signature of closed field lines is the presence of ionization indicating boundary plasma sheet precipitation. We investigate the consistency of these different signatures of the separatrix and show that the consistency depends on the local reconnection electric field. The two signatures yield a consistent identification of the separatrix at local times where the reconnection electric field is low. In the merging gap, however, where the reconnection electric field is high, the signature in the HF radar signature moves several degrees equatorward of the signature in the IS radar. These observations are backed up by DMSP precipitating particle observations, which indicate that the IS radar technique is properly identifying the poleward edge of the dayside BPS precipitation but also that the trapping boundary of magnetospheric ions and the electron edge occur at a latitude consistent with the HF radar signature of the separatrix. These observations are consistent with the theory that a portion of the dayside BPS is on open magnetic field lines. The latitudinal width of the dayside BPS on open field lines is given by ÁÃ = 0.14°E rec [mV/m] . We conclude that the HF radar signature is the more accurate identifier of the magnetic separatrix in the region of active reconnection.
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