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Showing papers by "Paul Scherrer Institute published in 1999"


Journal ArticleDOI
TL;DR: It is concluded that the 3D method provides the greatest flexibility for constructing conformal doses in challenging situations, but that when large numbers of beam ports are available, little advantage may be gained from the additional modulation of intensity in depth.
Abstract: The characteristic Bragg peak of protons or heavy ions provides a good localization of dose in three dimensions. Through their ability to deliver laterally and distally shaped homogenous fields, protons have been shown to be a precise and practical method for delivering highly conformal radiotherapy. However, in an analogous manner to intensity modulation for photons, protons can be used to construct dose distributions through the application of many individually inhomogeneous fields, but with the localization of dose in the Bragg peak providing the possibility of modulating intensity within each field in two or three dimensions. We describe four different methods of intensity modulation for protons and describe how these have been implemented in an existing proton planning system. As a preliminary evaluation of the efficacy of these methods, each has been applied to an example case using a variety of field combinations. Dose-volume histogram analysis of the resulting dose distributions shows that when large numbers of fields are used, all techniques exhibit both good target homogeneity and sparing of neighbouring critical structures, with little difference between the four techniques being discerned. As the number of fields is decreased, however, only a full 3D modulation of individual Bragg peaks can preserve both target coverage and sparing of normal tissues. We conclude that the 3D method provides the greatest flexibility for constructing conformal doses in challenging situations, but that when large numbers of beam ports are available, little advantage may be gained from the additional modulation of intensity in depth.

522 citations


Journal ArticleDOI
TL;DR: In this article, the available results of research, both on rechargeable negative electrodes based either on metallic magnesium or alternative materials, and on materials suitable as positive, magnesium-inserting (counter)electrodes for secondary magnesium batteries, are critically reviewed.

339 citations


Journal ArticleDOI
TL;DR: In this article, the complete matrix elements for all final states were reduced to a few compact generic functions in the Electroweak Standard Model for polarized massless fermions. But their results are limited to the case where the fermion mass obeys all Ward identities.

338 citations



Journal ArticleDOI
TL;DR: A review on the synthesis and properties of the organometallic aqua-ion [M(OH2)3(CO)3]- (M=Re, 99Tc, 99mTc), as relevant for radiopharmaceutical application, is presented in this paper.

327 citations


Journal ArticleDOI
TL;DR: In this study, antibody single-chain Fv fragments were labeled to high specific activities (90 mCi/mg), and the label was very stable to serum and all other challenges tested, and thus scFV fragments labeled by the new method will be suitable for biodistribution studies.
Abstract: Stable one-step technetium-99m labeling of His-tagged recombinant proteins with a novel Tc(I)–carbonyl complex

322 citations


Journal ArticleDOI
TL;DR: In this article, a natural illite (illite du Puy) was purified and converted to the homo-ionic Na form, and a two-site cation exchange model was developed to describe the sorption of Cs over the whole range of experimental conditions.

285 citations


Journal ArticleDOI
TL;DR: In this paper, the plastic behavior of two model f.c. metals, Ni and Cu, with different stacking fault energies, and average grain sizes in the range of 3-12nm, is analyzed.

284 citations


Journal ArticleDOI
TL;DR: Different specialized analytical dose calculations have been developed, which attempt to model the effects of density heterogeneities in the patient's body on the dose, and in most cases an elemental pencil beam dose calculation has been found to be most accurate.
Abstract: The gantry for proton radiotherapy at the Paul Scherrer Institute (PSI) is designed specifically for the spot-scanning technique. Use of this technique to its full potential requires dose calculation algorithms which are capable of precisely simulating each scanned beam individually. Different specialized analytical dose calculations have been developed, which attempt to model the effects of density heterogeneities in the patient's body on the dose. Their accuracy has been evaluated by a comparison with Monte Carlo calculated dose distributions in the case of a simple geometrical density interface parallel to the beam and typical anatomical situations. A specialized ray casting model which takes range dilution effects (broadening of the spectrum of proton ranges) into account has been found to produce results of good accuracy. This algorithm can easily be implemented in the iterative optimization procedure used for the calculation of the optimal contribution of each individual scanned pencil beam. In most cases an elemental pencil beam dose calculation has been found to be most accurate. Due to the long computing time, this model is currently used only after the optimization procedure as an alternative method of calculating the dose.

266 citations


Journal ArticleDOI
TL;DR: In this article, a systematic review of laboratory data on metal coprecipitation with calcite, presented in the form of phenomenological partition coefficients, is presented, which can be used to predict the partition coefficients of radionuclides for which no laboratory data exists.

227 citations


Journal ArticleDOI
TL;DR: In this article, a methodology for the initial development of solar thermochemical reactors for converting concentrated solar energy into chemical fuels is described, which consists of determining the implications that the thermodynamics and kinetics of the chemical transformation have on the initial reactor design.

Journal ArticleDOI
TL;DR: The use of protons has been found to reduce the medium to low dose load to OARs and all non-target tissues compared to both standard and inversely planned photons, but that the use of intensity modulated photons can result in similar levels of high dose conformation to that afforded by protons.

Journal ArticleDOI
TL;DR: The present results indirectly support the hypothesis of a serotonin-dopamine dysbalance in schizophrenia and suggest that psilocybin is a valuable tool in the analysis of serotonin- dopamine interactions in acute psychotic states.

Journal ArticleDOI
TL;DR: In this paper, the high pressure phase γ-MgH2 was formed by heating the low-pressure phase MgH 2 in a multianvil press at 2 GPa pressure to 1070 K for 120 min and successive rapid quenching.

Journal ArticleDOI
TL;DR: In this paper, the 15N ratio of nitrogen oxides emitted from vehicles, measured in the air adjacent to a highway in the Swiss Middle Land, was very high [δ15N(NO2) = +5.7‰].
Abstract: The 15N ratio of nitrogen oxides (NOx) emitted from vehicles, measured in the air adjacent to a highway in the Swiss Middle Land, was very high [δ15N(NO2) = +5.7‰]. This high 15N abundance was used to estimate long-term NO2 dry deposition into a forest ecosystem by measuring δ15N in the needles and the soil of potted and autochthonous spruce trees [Picea abies (L.) Karst] exposed to NO2 in a transect orthogonal to the highway. δ15N in the current-year needles of potted trees was 2.0‰ higher than that of the control after 4 months of exposure close to the highway, suggesting a 25% contribution to the N-nutrition of these needles. Needle fall into the pots was prevented by grids placed above the soil, while the continuous decomposition of needle litter below the autochthonous trees over previous years has increased δ15N values in the soil, resulting in parallel gradients of δ15N in soil and needles with distance from the highway. Estimates of NO2 uptake into needles obtained from the δ15N data were significantly correlated with the inputs calculated with a shoot gas exchange model based on a parameterisation widely used in deposition modelling. Therefore, we provide an indication of estimated N inputs to forest ecosystems via dry deposition of NO2 at the receptor level under field conditions.

Journal ArticleDOI
01 Mar 1999
TL;DR: It has been shown recently that Dirac operators satisfying the Ginsparg-Wilson relation provide a solution of the chirality problem in QCD at finite lattice spacing as mentioned in this paper.
Abstract: It has been shown recently that Dirac operators satisfying the Ginsparg-Wilson relation provide a solution of the chirality problem in QCD at finite lattice spacing. We discuss different ways to construct these operators and their properties. The possibility to define lattice chiral gauge theories is briefly discussed as well.

Journal ArticleDOI
TL;DR: It is shown that hPMS1 is expressed in human cells and that it interacts with hMLH1 with high affinity to form the heterodimer hMutLβ, which functions in postreplicative mismatch repair.

Journal ArticleDOI
TL;DR: Vanadium oxide nanotubes were prepared in a modified sol-gel reaction of vanadium oxide triisopropoxide conducted in the presence of the structurally directing hexadecylamine and followed by hydrothermal treatment as discussed by the authors.
Abstract: Vanadium oxide nanotubes were prepared in a modified sol‐gel reaction of vanadium oxide triisopropoxide conducted in the presence of the structurally directing hexadecylamine and followed by hydrothermal treatment. The tubes consist of concentric shells of highly crystalline vanadium oxide separated by alternating organic amine layers. The template molecules were removed without structural breakdown of the nanotubes by a combined ion‐exchange reaction and extraction process. The vanadium oxide nanotubes are redox‐active and can electrochemically insert lithium reversibly. A specific charge up to (with respect to the oxide) was measured for insertion into porous electrodes containing template‐free nanotubes. The specific charge decreased during cycling, indicating a loss of electroactivity. © 1999 The Electrochemical Society. All rights reserved.

Journal ArticleDOI
TL;DR: In this paper, a thermal method for the determination of ambient organic carbon (OC) and elemental carbon (EC) concentrations in carbonaceous samples was further developed, which was applied to samples obtained with an aethalometer from an ongoing campaign at the high-alpine research station Jungfraujoch.

Journal ArticleDOI
TL;DR: In this paper, the evolution of rare earth elements (REE) in non-mature streams from small catchment areas in the Vosges mountains downstream to more mature plain rivers including the river Rhine was studied.

Journal ArticleDOI
TL;DR: In this article, two different teflon-like films, one obtained by ion sputtering, and the other by plasma polymerization, were used for hot embossing into two different polymers.

Proceedings ArticleDOI
06 Oct 1999
TL;DR: The progress achieved in MRT research to date is described using immature and adult rats irradiated at the European Synchrotron Radiation Facility in Grenoble, France, and investigated thereafter at the Institute of Pathology of the University of Bern.
Abstract: The central nervous system of vertebrates, even when immature, displays extraordinary resistance to damage by microscopically narrow, multiple, parallel, planar beams of x rays Imminently lethal gliosarcomas in the brains of mature rats can be inhibited and ablated by such microbeams with little or no harm to mature brain tissues and neurological function Potentially palliative, conventional wide-beam radiotherapy of malignant brain tumors in human infants under three years of age is so fraught with the danger of disrupting the functional maturation of immature brain tissues around the targeted tumor that it is implemented infrequently Other kinds of therapy for such tumors are often inadequate We suggest that microbeam radiation therapy (MRT) might help to alleviate the situation Wiggler-generated synchrotron x-rays were first used for experimental microplanar beam (microbeam) radiation therapy (MRT) at Brookhaven National Laboratory's National Synchrotron Light Source in the early 1990s We now describe the progress achieved in MRT research to date using immature and adult rats irradiated at the European Synchrotron Radiation Facility in Grenoble, France, and investigated thereafter at the Institute of Pathology of the University of Bern

Journal Article
TL;DR: The novel labeling method using the organometallic 99mTc-aquaion combines the advantage of highest specific activities with minimal functionalization of proteins and peptides under retention of biologic affinity.
Abstract: A new peptide labeling method that uses the organometallic aquaion [99mTc(H2O)3(CO)3]+ has been developed. METHODS: A selection of amino acids was labeled at different concentrations with the organometallic aquaion, and the labeling yield was determined by high-performance liquid chromatography. This investigation has shown histidine to be a very potent ligand, with specific activities of up to 6 TBq/micromol (160 Ci/micromol) ligand. Histidine derivatives have been coupled to neurotensin(8-13) (NT[8-13]) and have been labeled with the aquaion, resulting in high specific activities with (N(alpha)-histidinyl)acetic acid-NT(8-13) similar to those with histidine. RESULTS: Histidine derivatives of NT(8-13) labeled using this approach fully retained their receptor affinity, showing KD values of all investigated NT analogs below 1 nmol/L on colon carcinoma HT29 cells. Biodistrbution experiments in BALB/c mice showed complete clearance of (N(alpha)-histidinyl)acetic acid-NT(8-13) from the blood after 24 h and no unwanted accumulation in any tissue. CONCLUSION: The novel labeling method using the organometallic 99mTc-aquaion combines the advantage of highest specific activities with minimal functionalization of proteins and peptides under retention of biologic affinity.

Journal ArticleDOI
TL;DR: In this article, the authors describe the design, fabrication, and preliminary test of a solar chemical reactor for conducting the thermal dissociation of ZnO into zinc and oxygen at above 2000 K.

Journal ArticleDOI
TL;DR: In this paper, the authors present an overview of studies that are today integrated into national or international projects initiated since the first Inert MAtrix Workshops held at the Paul Scherrer Institute and elsewhere since September 1995, as well as from other specific actions.

Journal ArticleDOI
TL;DR: In this paper, the same basic parameters such as site types, site capacities, and acidity constants could be used for both materials and to see to what extent the Ni and Zn surface complexation constants were influenced by the form of the montmorillonite Sorption edges for Ni at different Ca(NO3)2 background electrolyte concentrations, together with sorption isotherms measured over a range of pH values, were presented and modelled using the MINSORB code.

Journal ArticleDOI
TL;DR: In this paper, the authors compared the Lake Misery moraines with an Egesen moraine complex at Julier Pass in the Swiss Alps (46°30'N, 2200 m).
Abstract: Samples taken from the top surfaces of boulders on the Lake Misery moraines at Arthur's Pass, in the Southern Alps of New Zealand, were analysed for 10 Be by accelerator mass spectrometry. Exposure ages calculated with the currently accepted production rate, along with scaling corrections for sample latitude and elevation (42°50'S, 960 m), are: 9300 ± 990, 1 1,000 ± 1360, 11,410 ± 1030, 12,050 ± 960, and 12,410 ± 1180 years. We consider the date of 9300 years to be an outlier, not included in our mean exposure age of 11,720±320 years for the Lake Misery moraines. Based on exposure ages and geomorphologic similarities, we compare the Lake Misery moraines with an Egesen moraine complex at Julier Pass in the Swiss Alps (46°30'N, 2200 m). Based on the 10 Be, 26 Al, and 36 Cl exposure ages of three boulders, we calculate a mean exposure age of 11,750 ± 140 years for the outer Egesen moraine at Julier Pass. Based solely on 10 Be measurements, we obtain a mean exposure age of 11,860 ± 210 years for this outer moraine. Egesen moraines in the Swiss Alps represent glacier readvance during the Younger Dryas cold reversal, based on regional correlations and on basal radiocarbon dates from bogs located up-valley of Egesen moraines. The exposure dates from Arthur's Pass and Julier Pass show synchronous glacier advances both in the Southern Alps and in the European Alps during the European Younger Dryas chronozone of Mangerud et al.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the heavy metal binding properties of phytochelatins in heavy metal tolerant (Silene vulgaris) and sensitive (tomato) cell cultures, in water cultures of these plants and in a medieval copper mining dump.

Book ChapterDOI
TL;DR: The PDRP topography identified previously in Group A is highly reproducible across patient populations and tomographs and can accurately discriminate patients from controls in multiple populations studied with different tomographs.
Abstract: In a previous [F-18]fluorodeoxyglucose (FDG) PET study we analyzed regional metabolic data from a combined group of Parkinson's disease (PD) patients and healthy volunteers (N), using network analysis. By this method, we identified a unique pattern of regional metabolic covariation with an expression which accurately discriminated patients from healthy volunteers. To assess the reproducibility of this pattern as a potential marker for PD, we compared the pattern's topography with that of the disease-related covariance patterns identified in three other independent populations of patients with PD and healthy individuals studied in different PET laboratories. Methods: The following patient populations were studied: group A (original cohort: 22 PD, 20 N; resolution: 7.5 mm full width at half maximum [FWHM]); group B (18 PD, 12 N; resolution: 4.2 mm FWHM); group C (25 PD, 15 N; resolution: 8.0 mm FWHM); and group D (14 PD, 10 N; resolution: 10 mm FWHM). Region weights for the PD-related covariance pattern (PDRP) identified in the group A analysis were correlated with those for the disease-related patterns identified in the analyses of groups B, C and D, In addition, subject scores for the group A PDRP were computed prospectively for every individual in each of the study populations. PDRP scores for PD and N within each cohort were compared. Results: The PDRP topography identified in group A was highly correlated with each of the corresponding topographies identified in the other populations (r(2) similar to 0.60, P <0.0001). Prospectively computed subject scores for the group A PDRP significantly discriminated PD from N in each population (P <0.004). Conclusion: The PDRP topography identified previously in Group A is highly reproducible across patient populations and tomographs. Prospectively computed PDRP scores can accurately discriminate patients from controls in multiple populations studied with different tomographs. Brain network imaging with FDG PET can provide robust metabolic markers for the diagnosis of PD.

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional elliptic fluid mechanical model was used, which included elementary reactions for both gaseous and surface chemistry, to investigate the catalytically stabilized combustion (CST) of a lean (equivalence ratio Φ = 0.4) methane-air mixture.