11 research outputs found

    Shell closings and geometric structure effects : a systematic approach to the interpretation of abundance distributions observed in photoionisation mass spectra for alkali cluster beams

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    Recent mass spectrometric studies of continuous cluster beams resulting from supersonic expansions of alkali metal vapor have led to the postulation of islands of enhanced thermodynamic stability among the clusters produced. We discuss the various assumptions being made in converting ion abundances measured in these mass spectra into information about neutral stabilities. In this connection a number of experiments are described which allow insight into unimolecular dissociation of alkali cluster ions and into neutral cluster growth

    Sodium cluster ionization potentials revisited : higher resolution measurements for Nax (x<23) and their relation to bonding models

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    Controversy regarding the interpretation of ionisation efficiency measurements obtained for alkali clusters has provided impetus for higher-resolution studies (3.3 nm). The new data presented here cover the full range of cluster sizes Nax, x < 23. We discuss methods of assigning ionisation potentials and compare the resulting numbers with predictions from various model calculation

    Alkali clusters : structure, stability, large amplitude motion and chemical properties

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    Extensive measurements of ionisation potentials and relative thermodynamic stabilities for pure alkali and alkali/heteroatom species have provided much data pertiment to the electronic structure of simple metal clusters. Due to poorly characterized internal temperatures, an understanding of the relative magnitude of electronic versus geometric structure effects remains tenuous. Particle specific studies of chemical reactivity are ongoing

    Adherence to Contouring and Treatment Planning Requirements Within a Multicentric Trial: Results of the Quality Assurance of the SAKK 09/10 trial

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    PURPOSE To evaluate the results of the radiation therapy (RT) quality assurance (QA) program of the phase 3 randomized SAKK 09/10 trial in patients with biochemically recurrent prostate cancer after prostatectomy. METHODS AND MATERIALS Within the Schweizerische Arbeitsgemeinschaft fĂŒr Klinische Krebsforschung (SAKK) 09/10 trial testing 64-Gy versus 70-Gy salvage RT, a central collection of treatment plans was performed and thoroughly reviewed by a dedicated medical physicist and radiation oncologist. Adherence to the treatment protocol and specifically to the European Organization for the Research and Treatment of Cancer (EORTC) guidelines for target volume definition (classified as deviation observed yes vs no) and its potential correlation with acute and late toxicity (Common Terminology Criteria for Adverse Events version 4.0) and freedom from biochemical progression (FFBP) were investigated. RESULTS The treatment plans for 344 patients treated between February 2011 and April 2014 depicted important deviations from the EORTC guidelines and the recommendations per trial protocol. For example, in up to half of the cases, the delineated structures deviated from the protocol (eg, prostate bed in 48.8%, rectal wall [RW] in 41%). In addition, variations in clinical target volume (CTV) and planning target volume (PTV) occurred frequently (eg, CTV and PTV deviations in up to 42.4% and 25.9%, respectively). The detected deviations showed a significant association with a lower risk of grade ≄2 gastrointestinal acute toxicity when the CTV did not overlap the RW versus when the CTV overlapped the RW (odds ratio [OR], 0.43; 95% confidence interval [CI], 0.22-0.85; P = .014), and a higher rate of grade ≄2 late genitourinary (GU) toxicity when the CTV overlapped the RW (OR, 2.58; 95% CI, 1.17-5.72; P = .019). A marginally significant lower risk of grade ≄2 late GU toxicity was observed when the prostate bed did not overlap versus did overlap the RW (OR, 0.51; 95% CI, 0.25-1.03; P = .06). In addition, a marginally significant decrease in FFBP was observed in patients with PTV not including surgical clips as potential markers of the limits of the prostate bed (hazard ratio, 1.44; 95% CI, 0.96-2.17; P = .07). CONCLUSIONS Despite a thorough QA program, the central review of a phase 3 trial showed limited adherence to treatment protocol recommendations, which was associated with a higher risk of toxicity by means of acute or late gastrointestinal or GU toxicity and showed a trend toward worse FFBP. Data from this QA review might help to refine future QA programs and prostate bed delineation guidelines

    Adherence to contouring and treatment planning requirements within a multicentric trial -results of the quality assurance of the SAKK 09/10 trial.

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    PURPOSE To evaluate the results of the radiation therapy (RT) quality assurance (QA) program of the phase III randomized "XXXX-Anonymized for Review" trial in biochemically recurrent prostate cancer (PC) patients after prostatectomy. METHODS AND MATERIALS Within the "XXXX-Anonymized for Review" trial testing 64Gy versus 70Gy salvage RT, a central collection of treatment plans were performed, which were thoroughly reviewed by a dedicated medical physicist and radiation oncologist. Adherence to the treatment protocol and specifically to the European Organization for the Research and Treatment of Cancer (EORTC) guidelines for target volume definition (classified as deviation observed yes vs. no) and its potential correlation with acute and late toxicity (Common Terminology Criteria for Adverse Events (CTCAE) v4.0) and freedom from biochemical progression (FFBP) were investigated. RESULTS The treatment plans of 344 patients treated between February 2011 and April 2014 depicted important deviations to the EORTC guidelines and to the recommendations per trial protocol. For example, in up to half of the cases, the delineated structures deviated from the protocol (e.g., prostate bed (PB) in 48.8%, rectal wall (RW) in 41%). In addition, variations in clinical (CTV) - and planning target volume (PTV) occurred frequently (e.g., CTV and PTV deviations in up to 42.4% and 25.9%, respectively). The detected deviations showed a significant association with a lower risk of grade ≄ 2 gastrointestinal (GI) acute toxicity when CTV not overlapped RW vs. CTV overlapping RW, (OR 0.43; CI [0.22, 0.85]; p= 0.014), and a higher rate of grade ≄ 2 late genitourinary (GU) toxicity in case of the CTV overlapped with RW, (OR 2.58; CI [1.17, 5.72]; p= 0.019). A marginally significant lower risk of grade ≄ 2 late GU toxicity in patients when PB not overlapping RW versus overlapping RW was observed (OR 0.51; CI [0.25, 1.03]; p= 0.06). In addition, a marginally significant decrease of FFBP in patients with PTV not including surgical clips as potential markers of the limits of the prostate bed, (HR 1.44; CI [0.96, 2.17]; p= 0.07) was observed. CONCLUSIONS Despite a thorough QA program, the central review of a phase-III trial showed limited adherence to treatment protocol recommendations which was associated with a higher risk of toxicity by means of acute or late GI or GU toxicity and showed a trend towards worse FFBP. Data from this QA review may help refine future QA programs and prostate bed delineation guidelines

    MAP D-PHASE: Real-Time Demonstration of Weather Forecast Quality in the Alpine Region

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    International audienceDemonstration of probabilistic hydrological and atmospheric simulation of flood events in the Alpine region (D-PHASE) is made by the Forecast Demonstration Project in connection with the Mesoscale Alpine Programme (MAP). Its focus lies in the end-to-end flood forecasting in a mountainous region such as the Alps and surrounding lower ranges. Its scope ranges from radar observations and atmospheric and hydrological modeling to the decision making by the civil protection agents. More than 30 atmospheric high-resolution deterministic and probabilistic models coupled to some seven hydrological models in various combinations provided real-time online information. This information was available for many different catchments across the Alps over a demonstration period of 6 months in summer/ fall 2007. The Web-based exchange platform additionally contained nowcasting information from various operational services and feedback channels for the forecasters and end users. D-PHASE applications include objective model verification and intercomparison, the assessment of (subjective) end user feedback, and evaluation of the overall gain from the coupling of the various components in the end-to-end forecasting system
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