Showing papers by "Paul Scherrer Institute published in 1990"
TL;DR: The grafts, which were implanted unilaterally into the putamen by stereotactic surgery, restored dopamine synthesis and storage in the grafted area, as assessed by positron emission tomography with 6-L-[18F]fluorodopa.
Abstract: Neural transplantation can restore striatal dopaminergic neurotransmission in animal models of Parkinson's disease. It has now been shown that mesencephalic dopamine neurons, obtained from human fetuses of 8 to 9 weeks gestational age, can survive in the human brain and produce marked and sustained symptomatic relief in a patient severely affected with idiopathic Parkinson's disease. The grafts, which were implanted unilaterally into the putamen by stereotactic surgery, restored dopamine synthesis and storage in the grafted area, as assessed by positron emission tomography with 6-L-[18F]fluorodopa. This neurochemical change was accompanied by a therapeutically significant reduction in the patient's severe rigidity and bradykinesia and a marked diminuation of the fluctuations in the patient's condition during optimum medication (the "on-off" phenomenon). The clinical improvement was most marked on the side contralateral to the transplant.
1,169 citations
TL;DR: The results suggest diminished neuronal firing or decreased dendritic synaptic density with age, as well as a strict coupling between CMRO2 and CBF, and between CBF and CBV was found, while OER was constant and independent ofCBF andCMRO2.
Abstract: Regional cerebral blood flow (CBF), oxygen extraction ratio (OER), oxygen utilization (CMRO2) and blood volume (CBV) were measured in a group of 34 healthy volunteers (age range 22–82 yrs) using the 15O steady-state inhalation method and positron emission tomography. Between subjects CBF correlated positively with CMRO2, although the interindividual variability of the measured values was large. OER was not dependent on CMRO2, but highly negatively correlated with CBF. CBV correlated positively with CBF. When considering the values of all the regions of interest within a single subject, a strict coupling between CMRO2 and CBF, and between CBF and CBV was found, while OER was constant and independent of CBF and CMRO2. In ‘pure’ grey and white matter regions CMRO2, CBF and CBV decreased with age approximately 0.50% per year. In other regions the decline was less evident, most likely due to partial volume effects. OER did not change or showed a slight increase with age (maximum in the grey matter region 0.35%/yr). The results suggest diminished neuronal firing or decreased dendritic synaptic density with age.
1,038 citations
01 Apr 1990-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The L3 experiment as discussed by the authors is one of the six large detectors designed for the new generation of electron-positron accelerators, which is the only detector that concentrates its efforts on limited goals of measuring electrons, muons and photons.
Abstract: The L3 experiment is one of the six large detectors designed for the new generation of electron-positron accelerators. It is the only detector that concentrates its efforts on limited goals of measuring electrons, muons and photons. By not attempting to identify hadrons, L3 has been able to provide an order of magnitude better resolution for electrons, muons and photons. Vertices and hadron jets are also studied. The construction of L3 has involved much state of the art technology in new principles of vertex detection and in new crystals for large scale electromagnetic shower detection and ultraprecise muon detection. This paper presents a summary of the construction of L3.
505 citations
TL;DR: In this paper, the authors show that 10Be concentrations in polar ice can be used to study variations in the solar activity, particularly the 11-year cycle, in time periods pre-dating historical records.
Abstract: A DETAILED knowledge of the history of solar magnetic activity is important in several respects. From satellite data there is increasing evidence that solar magnetic activity and solar irradiance are positively correlated, a conclusion with important implications for climatology1. Because of the complexity of variations in solar activity, a long record is necessary for understanding the mechanisms responsible for heliomagnetic cyclicity2. Here we show that 10Be concentrations in polar ice can be used to study variations in the solar activity—particularly the 11-year cycle—in time periods pre-dating historical records.
353 citations
TL;DR: In this article, the limits of solar radiation concentration in geometrical and fluorescent systems are described as a function of the index of refraction, angular collection range, as well as the frequency shift.
229 citations
TL;DR: In this paper, a detailed overview of metal oxides in relation to their behavior in batteries is presented, covering electrochemical, conductivity, ion diffusivity, spectroscopic, and other physico-chemical data.
Abstract: Due to their rather low molecular weight and their favorable electrochemical and solid‐state properties, first row transition metal oxides seem to be specially attractive as cathode materials in electrochemical energy storage systems. Therefore, we undertook a detailed overview, covering electrochemical, conductivity, ion diffusivity, spectroscopic, and other physico‐chemical data on metal oxides in relation to their behavior in batteries. Metal oxide‐based primary batteries have achieved a high technological level and yield energy densities of up to 300 Wh kg−1 or 880 Wh l−1. Oxide‐based secondary batteries, on the other hand, typically yield less than 100 Wh kg−1. Based on the present review, V, Cr, Mn, and Co oxides seem to be the most promising solid‐state cathode materials for future high performance secondary batteries.
182 citations
TL;DR: In this article, the strangeness-changing nonleptonic weak interactions of the pseudoscalar mesons were investigated in the framework of the effective low-energy chiral lagrangian.
180 citations
01 Sep 1990
TL;DR: These results demonstrate, that fluorinated membranes with “defined” morphology can be applied in electrolysis cells, and give evidence for asymmetric degradation of membranes at the H2-side.
Abstract: A brief description of the ion exchange membrane fuel cell, of important membrane properties and of some earlier membrane development work is given. We describe some results of membrane stability tests in electrolysis cells, which are important for fuel cell application, in context with fluorination degree and morphology of the membrane. These results demonstrate, that fluorinated membranes with “defined” morphology can be applied in these cells. Finally, we give evidence for asymmetric degradation of membranes at the H2-side.
165 citations
Journal Article•
TL;DR: The purified 123I-Ro 16-0154 was found to be stable in rat brain preparations and to be metabolized in rat liver preparations, and its pharmacologic properties were comparable to those of flumazenil.
Abstract: The flumazenil analogue, Ro 16-0154, a benzodiazepine partial inverse agonist, has been labeled by halogen exchange to enable SPECT investigations of central benzodiazepine receptors in the human brain. The purified 123I-Ro 16-0154 was found to be stable in rat brain preparations and to be metabolized in rat liver preparations. Its pharmacologic properties were comparable to those of flumazenil. The biodistribution in rats (1 hr postinjection) resulted in a high brain-to-blood ratio of 16. Clinical studies revealed images of the benzodiazepine receptor density in the brain. Since the receptor labeling was markedly reduced by injection of flumazenil, it was considered to be specific. Storage defects due to pathologic cerebral blood flow and changed receptor density were detected; this shows the potential usefulness of the substance for diagnostic purposes, e.g., the differential diagnosis of various forms of epilepsy.
160 citations
TL;DR: An extensive photoemission study of the low-energy excitations in a series of Ce and Yb systems showing quite different electronic properties resulting from the weak hybridization of the 4{ital f} electrons with band states is presented.
Abstract: We present an extensive photoemission study of the low-energy excitations in a series of Ce and Yb systems showing quite different electronic properties resulting from the weak hybridization of the 4f electrons with band states. We discuss briefly the application of the single-impurity model to the calculation of the excitation spectra and review the influence of the different parameters. We analyze the spectra of each compound separately and show that they can be remarkably well simulated within the single-impurity framework. From these data we attempt to predict the linear coefficient of the specific heat and the magnetic susceptibility at T=0 K. A comparison with experimental values points to the limitations of this model to yield a unified description of different properties.
153 citations
15 Mar 1990-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The double-axis multicounter diffractometer (DMC) installed at the 10MW reactor SAPHIR (PSI) has been designed as a good-flux, good-resolution (presently Δd/d ⩾ 4×10−3) neutron powder diffractometers as discussed by the authors.
Abstract: The double-axis multicounter diffractometer (DMC) installed at the 10-MW reactor SAPHIR (PSI) has been designed as a good-flux, good-resolution (presently Δd/d ⩾ 4×10−3) neutron powder diffractometer. The detector bank is based on a commercial position-sensitive linear BF3 detector which may be automatically and precisely positioned on air cushions (standard epoxy floor). Vertically variable focusing germanium or pyrolythic graphite monochromators are used. Special efforts were made to optimize the sample environment, e.g. by developing an oscillating radial collimator system. Although the monochromator shielding is not yet in a final state, the diffractometer is successfully operating since several years. Design properties and operational experience are discussed. Online data analysis based on LSI and VAX computers is facilitated by user-friendly software.
TL;DR: In this paper, a model hamiltonian defined in the channel-space H = πN⊕γN ⊕B with B = δ and N. The model is consistent with the existing unitary πNN models and hence can be directly applied to study pion photoproduction on the deuteron and heavier nuclei.
TL;DR: Zero-field muon-spin-resonance and lower-critical-field data are presented for a wide range of Th concentrations in U1-x,Thx,Be13, spanning the region where both a superconducting and a second, lower-temperature phase transition are observed.
Abstract: Zero-field muon-spin-resonance and lower-critical-field data are presented for a wide range of Th concentrations in U1-x,Thx,Be13, spanning the region where both a superconducting and a second, lower-temperature phase transition are observed OverallT-xphase boundaries are assigned and discussed according to the nature of the lower phase transition Arguments for associating the lower phase with a possible magnetic (time-reversal-violating) superconducting state are given
01 Apr 1990
TL;DR: The optical characteristics of diffractive microstructures designed for zero-order read-out are discussed and offer new optical behaviour which can be exploited for applications in the field of visual and machine readable security features.
Abstract: The optical characteristics of diffractive microstructures designed for zero-order read-out are discussed. Such devices offer new optical behaviour which can be exploited for applications in the field of visual and machine readable security features. They can be fabricated by low-cost embossing and evaporation techniques.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
TL;DR: In this article, scaling relations for mass, surface and radius of fractal-like agglomerated particles are derived, and partly corroborated experimentally, for the free molecular regime and the continuum regime.
02 Dec 1990-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this article, 36 Cl measurements have been made in an arctic ice core from the Dye-3 site (65°11'N, 43°50'W).
Abstract: 36 Cl measurements have been made in an arctic ice core drilled near the Dye-3 site (65°11'N, 43°50'W). The samples analyzed cover the period between 1945 and 1985 with annual resolution. Due to the release of 36 Cl to the atmosphere from nuclear bomb tests, the data shown a peak in the late fifties with 36 Cl fallout rates about three orders of magnitude higher than expected from cosmic ray production. The time resolution is now precise enough to resolve the structure of the descending part of the fallout pattern. From the fallout rates obtained, a stratospheric residence time for bomb-produced 36 Cl could be derived. A detailed interpretation of the data is done with a four-box atmospheric transport model. The large and well-defined 36 Cl bomb pulse provides an excellent tracer for ground water studies.
TL;DR: In this article, the results of the joint Japanese (Central Research Institute of Electric Power Industry, CRIEPI, Tokyo), Swiss (National Cooperative for the Storage of Radioactive Waste, NAGRA, Baden), Swedish (Swedish Nuclear Fuel and Waste Management Company, SKB, Stockholm) international "JSS" project on the determination of the chemical durability of the French nuclear waste borosilicate glass, which was completed in 1988, were summarized.
Abstract: This review summarizes the results of the joint Japanese (Central Research Institute of Electric Power Industry, CRIEPI, Tokyo), Swiss (National Cooperative for the Storage of Radioactive Waste, NAGRA, Baden), Swedish (Swedish Nuclear Fuel and Waste Management Company, SKB, Stockholm) international ‘JSS’ project on the determination of the chemical durability of the French nuclear waste borosilicate glass, which was completed in 1988. Radioactive and nonradioactive glass specimens were investigated. A data base was created with results from glass corrosion tests performed with different water compositions, pH values, temperatures, sample surface areas (S), solution volumes (V), and flow rates. Glass corrosion tests were performed with and without bentonite and/or steel corrosion products present. Variation of the glass composition was taken into account by including the borosilicate glass ‘MW’ in the investigations, formulated by British Nuclear Fuels, plc. An understanding was achieved of the glass corrosion process in general, and of the performance of the French glass under various potential disposal conditions in particular. A special effort was made to establish a corrosion data base, using high S/V ratios in the experiments in order to understand the glass durability in the long term.
TL;DR: In this paper, the structure and dynamics of dilute Laponite RD sols were studied by static and dynamic light scattering, and collective diffusion coefficients were determined by slope analysis of the autocorrelation functions.
TL;DR: In this paper, a high-resolution 10Be profile has been measured on DSDP Site 519 (central South Atlantic) in order to search for changes in the flux of10Be into a pelagic sediment during geomagnetic reversals as compared with times of constant magnetic polarity.
01 Jan 1990
TL;DR: In this paper, the electrochromic charge storage reaction in anodic iridium oxide films (AIROF) was investigated in aqueous electrolytes using the probe beam deflection (PBD) technique in combination with cyclic voltammetry.
TL;DR: In this article, it is shown that the goal of space valorization cannot be considered without relational investment between the partners and their accumulated background, and that the capacity of the territory to solve these problems will depend closely on the richness of the network and co-operations which it shelters or it will suggest.
TL;DR: In this paper, a quenched equilibrium state of a $ −6531$.1 at. % Zn single crystal was investigated by elastic diffuse neutron scattering, where the short-range order intensity showed maxima that could be related to the flat portions of the Fermi surface perpendicular to the 〈110〉 directions.
Abstract: A quenched equilibrium state of a $^{65}31$.1 at. % Zn single crystal was investigated by elastic diffuse neutron scattering. The short-range order intensity showed maxima that could be related to the flat portions of the Fermi surface perpendicular to the 〈110〉 directions. Effective pair potentials ${V}_{\mathrm{lmn}}$ were determined from 71 short-range order parameters ${\ensuremath{\alpha}}_{\mathrm{lmn}}$ obtained from a fit to the diffuse intensity. Furthermore, 40 linear displacement parameters were also extracted. A dominant ${V}_{110}$ of \ensuremath{\sim}18 meV was obtained. Based on a Monte Carlo simulation, an ordered low-temperature phase ${\mathrm{Cu}}_{3}$Zn with the ${\mathrm{DO}}_{23}$ structure and a critical temperature of \ensuremath{\sim}330 K is suggested.
TL;DR: In this article, a search for the neutral Higgs boson using the processes Z 0 → H 0 e + e −, Z0 → H ε + ε, Z ε → H τ + τ −, Zε → ε v v, and Z 0→ H 0 q q q, is performed on data collected by the ALEPH detector corresponding to about 11 550 events of Z0→ hadrons.
TL;DR: In this paper, the Burgers vectors have been determined for a rhombohedral twin boundary in order to decide which one among three possible coincidence descriptions best represents the boundary structure, and their Burgers vector has been used to determine which one of the three possible co-occurrence descriptions best represent the boundary structures.
Abstract: Tables are given of all coincidence orientations with multiplicity Σ ≤ 36 for rhombohedral lattices with axial ratios in the range of corundum type structures (2.696 < c/a < 2-765). Measurements of the relative orientation of 133 pairs of neighbouring grains in sintered a-alumina showed that near-coincidence boundaries (14 cases) and one-dimensional coincidence boundaries (17 cases) occurred more frequently than would be the case for randomly distributed orientations and that many of these special boundaries contained periodic arrays of grain boundary dislocations. Their Burgers vectors have been determined for a rhombohedral twin boundary in order to decide which one among three possible coincidence descriptions best represents the boundary structure.
TL;DR: In this paper, a precise measurement of the cross section for e+e−→Z0→hadrons with the L3 detector at LEP was made, covering the s range from 88.28 to 95.04 GeV.
TL;DR: In this article, a two-stage concentrator with a rectangular glass heliostat and a parabolic dish was used to produce a primary image of the sun at a distance of 100 m to the South.
TL;DR: In this article, the authors calculated the threshold displacement energies for atomic displacements along {l angle}110{r angle, {l angles}100{r angles, and { l angle}111{ r angle} directions, and formation enthalpies of several symmetric interstitial atom configurations for Ni-Ni(100) dumbbells.
Abstract: Threshold displacement energies for atomic displacements along {l angle}110{r angle}, {l angle}100{r angle} and {l angle}111{r angle} directions, and formation enthalpies of several symmetric interstitial atom configurations were calculated for Ni{sub 3}Al by computer simulation using embedded atom method'' potentials The Ni-Ni(100) dumbbell in the plane containing only Ni atoms has the lowest interstitial-atom enthalpy although the enthalpies of other configurations are similar Interstitial configurations involving Al atoms all have much higher enthalpies The anisotropy of the threshold energies in Ni{sub 3}Al is similar to pure metals and no significant difference in threshold energy was observed for {l angle}110{r angle} replacement chains in rows containing all Ni atoms or alternating Ni-Al atoms Various metastable interstitial atom configurations were observed, including crowd-ions In addition, the spontaneous recombination volume for some configurations can be much smaller than in pure metals The consequences of these results for radiation induced segregation and amorphization {ital are} {ital discussed}
TL;DR: In this article, the authors measured the properties of Z0 → b b decays using a sample of 944 inclusive muon events, corresponding to 18 000 hadron events obtained with the L3 detector at LEP.
TL;DR: In this article, the authors present the results from a search for the light neutral scalar Higgs boson h° and the pseudoscalar higgs Boson A° of the minimal super-symmetric standard model.