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31.
Accuracy of patient positioning and dose delivery in mantle field irradiations was investigated on 29 patients treated between August 1990 and December 1991. Patients were treated in two different centers, University Hospital St. Rafa?l in Leuven and Institut Gustave Roussy in Villejuif, where different techniques and procedures were used. Measurements were performed on 341 portal films and entrance doses were measured in 518 treatment set-ups. The impact of systematic errors occurring during treatment preparation and day-to-day variations on the accuracy of treatment execution were separately analysed. Daily reproducibility, defined as the deviation from the respective mean measured value for a treatment was demonstrated to be good for both the treated volume and the delivered dose and no difference between the two techniques was shown. Comparing the successive portal films of individual patients (reproducibility of a treatment, once it has started), only small day-to-day variations are found: the SD is 3.4 mm for craniocaudal movements and 2.6 mm for lateral movements. For dose delivery very narrow distributions are obtained with SDs of, respectively, 1.5% and 1.85% for the Leuven and the Villejuif group. This suggests that the position of the patient, which is often thought as the critical point in this complex set-up can be done in a very accurate way, regardless of the position used. To assess the global accuracy of the treatment, the actually treated volume and delivered dose were compared with the planned values. Apart from reproducibility this also takes into account the whole preparatory procedure between planning and the start of the therapy (first session).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
32.
Examined the differential prevalence of 10 major dimensions of psychotic and affective signs (e.g., auditory hallucinations, delusions of control, excitement/agitation, catatonic and bizarre behavior) and symptoms in 18 neuropsychologically impaired and 30 neuropsychologically intact schizophrenics who were diagnosed under Research Diagnostic Criteria. Assessments were based on the Present State Examination and on the Luria-Nebraska Neuropsychological Battery. Results show that the neuropsychologically impaired Ss had a lower incidence of delusions of reference and persecution and a diminished capacity for insight compared to neuropsychologically unimpaired Ss. Findings are discussed in terms of a frontal lobe dysfunction hypothesis of schizophrenic psychopathology. (3 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
33.
34.
P O'Hara JE Connett WW Lee M Nides R Murray R Wise 《Canadian Metallurgical Quarterly》1998,148(9):821-830
The authors examine weight gains associated with smoking cessation in the Lung Health Study (1986-1994) over a 5-year follow-up period. A cohort of 5,887 male and female smokers in the United States and Canada, aged 35-60 years, were randomized to either smoking intervention or usual care. Among participants who achieved sustained quitting for 5 years, women gained a mean of 5.2 (standard error, 5.0) kg in year 1 and a mean of 3.4 (standard error, 5.5) kg in years 1-5. Men gained a mean of 4.9 (standard error, 4.9) kg in year 1 and a mean of 2.6 (standard error, 5.8) kg in years 1-5. In regression analyses, smoking-change variables were the most potent predictors of weight change. Participants going from smoking to quit-smoking in a given year had mean weight gains of 2.95 kg/year (3.61%) in men and 3.09 kg/year (4.69%) in women. Over 5 years, 33% of sustained quitters gained > or = 10 kg compared with 6% of continuing smokers. Also among sustained quitters, 7.6% of men and 19.1% of women gained > or = 20% of baseline weight; 60% of the gain occurred in year 1, although significant weight gains continued through year 5. The average gains and the high proportions of sustained and intermittent quitters who gained excessive weight suggest the need for more effective early interventions that address both smoking cessation and weight control. 相似文献
35.
Michael E. Fraker Anisha Shrestha Lauren Marshall Lacey Mason Russ Miller 《Journal of Great Lakes research》2021,47(4):1228-1234
The Cooperative Institute for Great Lakes Research (CIGLR) in collaboration with the Great Lakes Observing System and National Oceanic and Atmospheric Administration, Great Lakes Environmental Research Laboratory (NOAA GLERL) deployed an autonomous underwater glider in southern Lake Michigan several times per year between 2012 and 2019 to collect offshore (>30 m depth) limnological measurements, including temperature, photosynthetically active radiation (beginning during 2015), and chlorophyll-α fluorescence. From these data, we calculated mixed layer depth, several measures of light penetration (diffuse attenuation coefficient, first optical depth, euphotic zone depth), and depth of the subsurface chlorophyll-α maxima. During summer, mean offshore mixed layer depth was typically 10–15 m, Kd for PAR was 0.1–0.17 m?1, first optical depth was 6–9 m, euphotic zone depth was 35–40 m, and depth of subsurface chlorophyll-α maxima was 30–35 m. We also observed substantial spatial and temporal variation in these values across the basin and within and among seasons. Glider-based observations provide a wider horizontal and vertical perspective than other methods (e.g., ship- and satellite-based observations, buoys, and fixed moorings), and are therefore a valuable, complementary tool for Great Lakes limnology. The set of observations reported here provide seasonal and basin-scale information that may help to identify anomalies useful for future glider-assisted investigation into the role of biophysical processes in Great Lakes limnology and ecology. 相似文献
36.
David B. Marshall Joseph J. Ratto Fred F. Lange 《Journal of the American Ceramic Society》1991,74(12):2979-2987
Laminar composites, containing layers of Ce-ZrO2 and either Al2 O3 or a mixture of Al2 O3 and Ce-ZrO2 , have been fabricated using a colloidal method that allowed formation of layers with thicknesses as small as 10 μm. Strong interactions between these layers and the martensitic transformation zones surrounding cracks and indentations have been observed. In both cases, the transformation zones spread along the region adjacent to the layer, resulting in an increased fracture toughness. The enhanced fracture toughness was observed for cracks growing parallel to the layers as well as for those that were oriented normal to the layers. 相似文献
37.
Philip E. Sonnet Edwin G. Piotrowski William B. Wise Thomas J. Micich 《Journal of the American Oil Chemists' Society》1986,63(12):1579-1583
Oxyethylated amides that are good wetting agents have been prepared as mixtures by allowing amides to react with ethylene
oxide under base catalysis. Individual components of such mixtures can be synthesized by allowing 1-alkylaziridines to react
with p-toluenesulfonic acid in monomethylethers of di-, tri- and tetraethylene glycol used as solvents. The aminoethers are
then acylated, and the methylether group is removed with trimethylsilyliodide from the resulting amide ethers. The sequence
should allow the synthesis of specific wetting agents of quite varied structure (alkyl, aryl groups) with an option for isotopic
labeling for more detailed analysis of the wetting properties. 相似文献
38.
ABA-type “tapered” block polymers were prepared from styrene (monomer A) and butadiene or isoprene, using an initiator of sec-butyllithium complexed with two molecules of ethyl ether. The stress–strain curves of polymers containing about 20–50% styrene show the usual resemblance to curves of crosslinked elastomers. The SBS polymers had higher tensile strengths than the SIS polymers. They also had slightly higher tensile strengths than comparable SBS polymers made with sec-butyllithium. The SIS polymers, however, had generally lower tensile strengths than those made with sec-butyllithium. This is probably caused by higher styrene content of the isoprene block, brought about by increased randomization of the styrene–isoprene copolymerization due to the presence of the ether. The A and B blocks become more compatible, producing loss of strength in the polymer. Infrared analyses of polydienes made with the sec-C4H9Li·2(C2H5)2O initiator showed a 6% to 8% increase in 1,2-content (for polybutadiene) or 3,4-content (for polyisoprene), compared to polymers made with sec-butyllithium. The polymer microstructures still have high (>80%) total 1,4-content, however. Thus, this amount of ether can be tolerated in the polymerization system without great loss of rubbery properties or block structure in the resultant polymers. 相似文献
39.
High-Strength Zirconia Fibers 总被引:1,自引:0,他引:1
David B. Marshall F. F. Lange Peter D. Morgan 《Journal of the American Ceramic Society》1987,70(8):187-C
Fine-grained polycrystalline zirconia fibers have been formed from an acetate precursor. The fibers contained a Y2 O3 additive, which inhibited grain growth (grain size ≤0.5 μm) and allowed the tetragonal phase to be retained at room temperature. Fibers with diameters in the range 2 to 5 μm had strengths in the range 1.5 to 2.6 GPa. 相似文献
40.
K. D. Bartle D. W. Jones T. G. Martin W. S. Wise 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1970,20(6):197-202
Tar resulting from fluidised-bed, low-temperature carbonisation of coal was treated to yield a neutral oil from which a series of six other samples was extracted. These were examined by proton magnetic resonance (p.m.r.) spectroscopy, low-ionising-voltage (11 eV) mass spectroscopy (m.s.), gel chromatography followed by fluorescent indicator analysis, and cryoscopy. Aliphatic fractions separated chromatographically were also examined by infra-red spectroscopy. Distributions of hydrogen between chemical types were found for the several fractions from 60 MHz p.m.r. spectra and presented in terms of average structural parameters. M.s. analysis indicated negligible cracking of paraffin components, and the average molecular weight of 197 agreed well with cryoscopic determinations. For the carbon ratio, fa, between aromatic and total, agreement between m.s. and p.m.r. depends on the p.m.r. structural analysis scheme adopted. P.m.r. and m.s. structural analyses of the aromatics emphasise the predominance of di- and tri-nuclears, with about 40% of available sites substituted, and the importance of acenes in lowtemperature carbonisation material. Gas and gel chromatography showed urea-adductable paraffins to be largely straight-chain C10-C26, much as for tars from carbonisation at higher temperature. 相似文献