2,805 research outputs found
N3 (TNM-UICC) metastatic neck nodes managed by combined radiation therapy and hyperthermia: Clinical results and analysis of treatment parameters
No full textIn an attempt to improve the control of N3 (TNM-UICC) fixed and inoperable metastatic nodes, local microwave hyperthermia (HT) was combined with radiation therapy (RT). From February 1981 to January 1985, 34 patients, with N3 metastatic nodes from primary tumours in the head and neck, were treated according to two different prospective, non-randomized protocols: 23 patients received HT combined with the first course of conventionally fractionated radical RT (40 Gy + HT--2 week interval--20-30 Gy), and 11 patients received HT combined with palliative RT (20-50 Gy + HT). All the patients were treated with the same microwave applicator (MA-150) on the BSD-1000 unit, at a frequency of 280-300 MHz. Temperatures were measured by means of 2-3 Bowman probes placed within the tumour (core and periphery) and 5-6 probes on the skin surface. HT sessions were delivered after RT (less than 20 min), 2 or 3 times weekly, for a duration of 30 min after steady-state temperatures were obtained. Twenty-seven patients out of 34 were evaluable, with a follow-up of at least 3 months (range 3-39 months; median 10 months). Clinical results at 3 months revealed 59 per cent complete responses, 30 per cent partial responses, and 11 per cent with progressive disease. Analyses of response rates showed: a marginally significant difference (P = 0.095) between RT alone (historical control) and the entire group of patients treated with RT plus HT; a significant difference (P = 0.034) if RT alone is compared with Protocol A (RT greater than or equal to 60 Gy + HT); no significant difference between the two protocols employing HT, despite the different RT doses utilized; no significant differences in response rates, as a function of minimal intratumoural temperatures achieved, number of weekly HT sessions or total number of HT sessions; and a significantly lower response rate for nodes with maximum diameter greater than 6 cm (P = 0.043). No important differences in acute side effects between irradiated and heated regions in the same patient were noted. Late side effects in patients treated with RT plus HT included three cases (9 per cent) of severe fibrosis, possibly as a consequence of excessive maximum tumour temperature (greater than 46 degrees C)
Performance of Broadband Multicarrier DS-CDMA using Space-Time Spreading-Assisted Transmit Diversity
No full textIn this contribution multicarrier direct-sequence code-division multiple-access (MC DS-CDMA) using space–time spreading (STS)-assisted transmit diversity is investigated in the context of broadband communications over frequency-selective Rayleigh-fading channels. We consider the issue of parameter design for the sake of achieving high-efficiency communications in various dispersive environments. Furthermore, in contrast to conventional MC DS-CDMA schemes employing time (T)-domain spreading only, in this contribution we also investigate broadband MC DS-CDMA schemes employing both T-domain and frequency (F)-domain spreading, i.e., employing TF-domain spreading. The bit-error rate (BER) performance of STS-assisted broadband MC DS-CDMA is investigated for downlink transmissions associated with the correlation based single-user detector and the decorrelating multiuser detector. Our study demonstrated that when appropriately selecting the system parameters, broadband MC DS-CDMA using STS-assisted transmit diversity constitutes a promising downlink transmission scheme. This scheme is capable of supporting ubiquitous communications over diverse communication environments without BER performance degradation. Index Terms—Broadband system, code-division multiple access (CDMA), frequency-domain spreading, frequency-selective fading, multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA), multicarrier CDMA, multicarrier modulation, multiuser detection, space–time spreading (STS), transmit diversity
From Suessel Hechtsheim to David Kapp : The Hechtsheim Jews.
No full textAccount of the history of the Jewish population in Hechtsheim and their persecution during the Nazi era. Translated from German to English by Robert R. Wolf (2001).Robert R. Wolf, October 16, 2001Translation of: "Keim, Anton Maria, 1928- : Von Suessel Hechtsheim bis David Kapp : die Hechtsheimer Juden / Anton Maria Keim. Hechtsheim : Verein Hechtsheimer Ortsgeschichte, 1994." (LBI Library call number: DS 135 G4 P35 K4 1994
Adaptive Minimum-BER Linear Multiuser Detection for DS-CDMA Signals in Multipath Channels
No full textThe problem of constructing adaptive minimum bit error rate (MBER) linear multiuser detectors is considered for direct-sequence code division multiple access (DS-CDMA) signals transmitted through multipath channels. Based on the approach of kernel density estimation for approximating the bit error rate (BER) from training data, a least mean squares (LMS) style stochastic gradient adaptive algorithm is developed for training linear multiuser detectors. Computer simulation is used to study the convergence speed and steady-state BER misadjustment of this adaptive MBER linear multiuser detector, and the results show that it outperforms an existing LMS-style adaptive MBER algorithm first presented at Globecom'98 by Yeh, Lopes and Barry
Measurement of the branching fractions of Ds+→η'X and Ds+→η'ρ+ in e+e-→Ds+Ds-
No full textÇetin, Serkant Ali (Dogus Author)We study Ds+ decays to final states involving the η' with a 482 pb-1 data sample collected at s=4.009 GeV with the BESIII detector at the BEPCII collider. We measure the branching fractions B(Ds+→η'X)=(8.8±1.8±0.5)% and B(Ds+→η'ρ+)=(5.8±1.4±0.4)% where the first uncertainty is statistical and the second is systematic. In addition, we estimate an upper limit on the non-resonant branching ratio B(Ds+→η'π+π0)<5.1% at the 90% confidence level. Our results are consistent with CLEO's recent measurements and help to resolve the disagreement between the theoretical prediction and CLEO's previous measurement of B(Ds+→η'ρ+)
Correlations of thermal washout rate, steady state temperatures, and tissue type in deep seated recurrent or metastatic tumors
No full textThe rates of cooling ("thermal washout") in selected sites in tumor and adjacent normal tissues following the completion of clinical hyperthermia sessions were analyzed in ten patients treated with combined radiation and hyperthermia for deep seated recurrent or metastatic tumors. The temperatures were recorded at 10 second intervals for at least 2 minutes after the cessation of microwave power at the end of the 30-60 minute duration hyperthermia treatments. These thermal washouts were characterized by the slope of a log-linear relation between temperature elevation above the oral baseline temperature and time. Washout rates (expressed as a perfusion rate in ml/100g-min) significantly correlated with tissue categories as noted on CAT scan (i.e., tumor, normal tissue, tumor/normal tissue interface, hypodense tumor areas). Relationships between thermal washout rate and steady-state temperature elevation were tested and also showed significant correlations in general and for some specific tissue categories. The implications of these findings in explaining inhomogeneities in heating patterns, and in hyperthermia treatment modeling will be presented
Groupwise Multiuser Detection in a Multirate DS-CDMA System
No full textThis report presents the performance of groupwise successive interference cancellation (GSIC) within a direct sequence code division multiple access system (DS-CDMA). Within the groups, matched filter and PIC receivers are used for detection of the users. A multirate DS-CDMA system model, based on a single rate system is presented. Although the study of multiuser detection for single rate systems has resulted in several structures, multiuser receivers designed specifically for a DS-CDMA variable spreading factor multirate system are shown to be benificial. Since they can exploit the specific properties of these systems. The bit error rate performance of matched filter, parallel interference cancellation and GSIC receivers are compared in AWGN channel. The GSIC receiver is seen to perform best. The various GSIC receiver variants are then simulated in a Rayleigh fading channel to investigate how they will perform in a realistic mobile environment. Finally the impact of fixed delay is studied.Applied SciencesElectrical EngineeringTelecommunications and Traffic-Control Systems Grou
Multibeam Adaptive Antenna Array Applied to DS-CDMA Communication Systems
No full textIn this thesis, the multibeam adaptive antenna array has been investigated for application to DS/CDMA The objective is to design an adaptive controller and a beamformer for an Adaptive Antenna Array suitable for the wideband DS/CDMA environment. The research was in accordance with the current research on third generation mobile communications systems in development in Europe…Applied SciencesInformation Technology and SystemsTelecommunications and Traffic Control Systems Grou
Performance Analysis of DS, SFH and Hybrid DS/SFH CDMA in an Micro - and Macro cellular Environment with Fading and Shadowing: Task report
No full textIn this report, a performance analysis of DS, SFH and Hybrid DS/SFH in terms of biterror probability, throughput and delay are presented. The modulation techniques used are BPSK and QPSK. The effect of Selection Diversity and Forward Error Correction (FEC) Codeon the performance are also investigated. A comparison between the CDMA techniques is made in macro- and micro cellular environment.Applied SciencesElectrical EngineeringTelecommunications and Traffic Control Systems Grou
Reduced-rank adaptive least bit-error-rate detection in hybrid direct-sequence time-hopping ultrawide bandwidth systems
No full textDesign of high-efficiency low-complexity detection schemes for ultrawide bandwidth (UWB) systems is highly challenging. This contribution proposes a reduced-rank adaptive multiuser detection (MUD) scheme operated in least bit-errorrate (LBER) principles for the hybrid direct-sequence timehopping UWB (DS-TH UWB) systems. The principal component analysis (PCA)-assisted rank-reduction technique is employed to obtain a detection subspace, where the reduced-rank adaptive LBER-MUD is carried out. The reduced-rank adaptive LBERMUD is free from channel estimation and does not require the knowledge about the number of resolvable multipaths as well as the knowledge about the multipaths’ strength. In this contribution, the BER performance of the hybrid DS-TH UWB systems using the proposed detection scheme is investigated, when assuming communications over UWB channels modeled by the Saleh-Valenzuela (S-V) channel model. Our studies and performance results show that, given a reasonable rank of the detection subspace, the reduced-rank adaptive LBER-MUD is capable of efficiently mitigating the multiuser interference (MUI) and inter-symbol interference (ISI), and achieving the diversity gain promised by the UWB systems
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