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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Child's nervous system 9 (1993), S. 131-135 
    ISSN: 1433-0350
    Keywords: Supratentorial tumors ; Astrocytomas ; Ependymomas ; Secondary malignancies ; Paediatric patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sixty-four malignant hemispheric tumors in children less than 15 years old were treated in the pediatric neurosurgical department of the H ôpital des Enfants Malades between 1970 and 1989. (1) These tumors evolved rapidly in most cases. However the pre-operative evolution in 20% of the patients had a duration of more than 6 months, which favors the hypothesis that at least one-fifth of these tumors result from malignant transformation of a benign lesion. This observation should prompt neurosurgeons to operate on all benign hemispheric tumors as soon as they are diagnosed. (2) Five of the 64 patients had two successive malignant diseases. In four cases the other malignant disease was an acute lymphoblastic leukemia. (3) Among the malignant hemispheric tumors, the grade III and IV astrocytomas had a dismal prognosis. As it is known from previous studies that grade I and II astrocytomas have a good prognosis in children, it can be concluded that grading these tumors is essential. By contrast, almost one out of two patients with malignant ependymoma was alive 5 years after treatment. This implies that the grading of ependymomas is of modest prognostic values. (4) The harmful effect of radiotherapy was evaluated by comparing the functional outcome of children operated for a benign hemispheric tumor to that of children operated and irradiated for a malignant hemispheric tumor.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1433-0350
    Keywords: Children ; Medulloblastoma ; Psychological sequelae ; Radiotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A series of 120 medulloblastomas in children operated on between 1967 and 1987 at the Hôpital des Enfants-Malades has been reviewed in order to check whether the conclusions of our study published 10 years ago have remained valid and, in particular, to verify whether the quality of life of these patients, which had been found to be poor at the time, had improved or worsened over the years. The postoperative mortality for the whole series was 6.5% there have been no deaths in the 35 patients operated on after 1980. The overall survival rate for the 120 children was 60% at 5 years and 53% at 10 years; for the patients who completed radiotherapy, the survival rates was 73% at 5 years and 64% at 10 years. Survival rates were surprisingly better in patients treated when under 6 years of age than in older children. They were also better in girls than in boys, and in desmoplastic compared with other medulloblastomas; however, the differences were not significant. When comparing the groups after total or subtotal resection of tumors, survival rates were not significantly different, but were lower in the small group of partial resections. Cell differentiation did not influence the prognosis. Psychological sequelae were significant and worsened over the years. Five years after treatment 58% of the children showed an IQ above 80; 5 years later this group included only 15% of the patients. These psychological sequelae were related to age at the time of radiotherapy: the younger the child, the lower the final IQ. Five years after treatment, 40% of the children had a normal academic level; 5 years later this group was reduced to 11%. Ten years after treatment, 36% of the patients were unempolyed and 64% worked in a protected environment. No patient had normal employment. These disastrous results concerning the quality of life of these medulloblastoma patients justify new trials with reduced doses of irradiation over the hemispheres, at least in low-risk groups.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-0350
    Keywords: Stereotaxy ; Fibrin gene ; Surgical approach of space-occupying lesions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract When intracerebral space-occupying lesions are small or located deeply within the brain parenchyma, it is sometimes difficult to localize them at surgery or to design the most direct and least hazardous surgical approach. Therefore, we have developed a method that combines conventional neurosurgical techniques with craniotomy using stereotactic guidance. We have used the Brown-Roberts-Wells (BRW) stereotactic system, which allows for computed tomography (CT) or magnetic resonance imaging (MRI) guidance and does not interfere with the absolute sterility mandatory each time a flap is created. Eleven patients were operated on using this method. The deep tumors were approached through a linear incision of the cerebral cortex. Then a needle, fixed in the right position on the arc system of the BRW, was inserted toward the surface of the lesion; the exposure was finally widened by inflation of a rubber balloon set on the stereotactic needle. This technique allows the two lips of the cortical incision to be glued at the end of the operation. Gluing with a fibrin glue avoids the postoperative subdural collections that often develop when the ventricle has been opened. Except for one case, the post-operative course was uncomplicated in these patients. No permanent postoperative neurological worsening was observed even after the removal of an intrathalamic tumor.
    Type of Medium: Electronic Resource
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  • 4
    Book
    Book
    Chichester u.a. :Wiley,
    Title: Computational methods for inviscid and viscous flow; 2
    Author: Hirsch, Charles
    Publisher: Chichester u.a. :Wiley,
    Year of publication: 1990
    Pages: 691 S.
    Series Statement: Numerical computation of internal and external flows 2
    Type of Medium: Book
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  • 5
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 7446-7452 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: During removal of amorphous silicon films deposited on crystalline silicon substrates by dry etching in a hydrogen plasma the kinetics of mobile excess charge carriers have been followed by measuring the change of the microwave reflection after laser pulse illumination. Following the amplitude of the measured transient signals the thickness of the remaining amorphous silicon film can be determined and the decay in the nanosecond time range yields information about the defect density of the substrate surface. The impact of the plasma process on the surface recombination is shown and a criterion for endpoint detection is given in the case of a-Si:H removal from crystalline silicon covered with a SiO2 layer.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Perturbative corrections of various types are employed in conjunction with variational configuration-interaction (CI) treatments in order to obtain estimates of the energy eigenvalues of a large series of full CI benchmark calculations recently reported by Bauschlicher et al. It is found that the best agreement is generally obtained when an extrapolation procedure based on the results of truncated secular equations is employed to estimate the zero-threshold multiple reference double-excitation configuration-interaction (MRD-CI) energy values, after which these intermediate results are then corrected for effects of higher excitations by means of a multireference analogue of the Davidson–Langhoff correction D1. A root-mean-square (rms) deviation of 0.94 kcal mol−1 relative to the full CI energy results for 66 cases is obtained with this perturbative method, which has been in general use now for most of the last decade. By comparison the T=0 variational MRD-CI energy values give a higher rms deviation of 3.19 kcal mol−1. This behavior is shown to result from a systematic cancellation of errors in the two types of perturbative corrections employed in the above scheme. The advantages of employing a multireference set of configurations in generating singles and doubles CI spaces are also underscored by the present results, and the advisability of employing a nearly uniform value of ∑mpc2p for all states and nuclear conformations of a given atomic or molecular system is stressed.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ab initio CI (configuration interaction) calculations are carried out for O2 in various 3Σ−u excited states in order to study the avoided crossing that is responsible for the discrete B'–X bands found in the high-energy region of the Schumann–Runge continuum. A diabatic transformation is carried out which allows for the description of nonadiabatic effects in this spectral range. A coupled vibrational treatment is employed in conjunction with the complex scaling technique in order to compute the predissociation linewidths of the B' levels, and these results are found to be in good agreement with experiment, particularly for trends observed between different isotopomers of this system. Optical f values and generalized oscillator strengths (GOS) are calculated for a series of vibrational transitions and are also found to compare well with measured data. The observed finding that the GOS varies quite slowly with K2 for the 0–0 transition, but decreases rather sharply for the 1–0 species is reproduced in the calculations and the behavior of this property for other transitions is predicted.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 2284-2290 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A broadband heterodyne reflectometer, operating in the frequency range 75–110 GHz in extraordinary mode polarization, has been installed and operated at the Wendelstein 7-AS stellarator for the study of density fluctuations and density profile determination. At 2.5 T it covers the density range between 5×1018 and 5×1019 m−3. The system differs from the usual setup as it combines the advantages of heterodyne detection with broadband capability avoiding the limitations of phase-locked sources and permits the unambiguous determination of the phase delay independent of amplitude fluctuations in the reflected beam. After a first downconversion to an intermediate frequency of about 6 GHz, two additional mixing steps lead to an intermediate frequency of 60 MHz, which carries the phase delay from the plasma as a phase modulation. The phase information is yielded numerically from sin/cos detection at 60 MHz. Due to the balanced detection scheme, the drift as well as the broadband noise of the signal and local oscillators are canceled. The system has a dynamic range of about 60 dB and is within this range almost insensitive to amplitude fluctuations of the reflected beam. Examples are given demonstrating the potential of the system installed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 3338-3339 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The dc operation of some laser diodes produces high-frequency amplitude modulation of the laser output in the GHz frequency range. This phenomenon provides a simple and inexpensive method for checking the sweep linearity of a fast-gated streak camera.
    Type of Medium: Electronic Resource
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