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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 3566-3570 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Absolute cross sections for electron-impact detachment and electron-impact dissociation of CN− and BO− were measured for electron energies from threshold to 40 eV. With both ions we see only little dissociation when electron detachment occurs. In the case of CN− a resonance in the detachment cross section is discovered at an energy of ∼10 eV. No resonances were seen in the case of BO−. We argue that the resonance observed for CN− is due to an excited state of the dianion. The nonresonant part of the detachment cross section is found to follow the classical prediction given by Andersen et al. [Phys. Rev. Lett. 74, 892 (1995)]. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1440
    Keywords: Diabetic cardiopathy ; Radionuclide Ventriculography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Left ventricular function was assessed by means of radionuclide ventriculography in 42 patients with long-standing (13±5 yrs) insulin-dependent diabetes mellitus and in eleven healthy age matched control subjects. Only diabetics were included in the study without diabetes related cardiac risk factors such as hypertension and CAD in order to evaluate diabetes specific changes of cardiac function. No differences were seen between diabetics and controls concerning heart rate and functional parameters of left ventricle in systole and diastole. The rapid filling period was not prolonged. According to our radionuclide data there is no evidence of diabetes related impairment of ventricular function in young patients with long-standing type-1-diabetes mellitus.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1440
    Keywords: Vitamin B12 ; Vitamin B12 absorption ; Schilling test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It was the purpose of this study to evaluate the diagnostic usefulness of an oral absorption test using nonlabeled Vit B12 suggested by a commercial distributor as an alternative for the more expensive Schilling test (ST). Plasma levels of Vit B12 were measured with a commercial kit before and 4 h after oral administration of 1 mg Vit B12 in 32 normals, in 16 patients with normal ST, and in 14 patients with abnormal ST for determination of sensitivity and specificity with the ST as golden standard. In normals, a mean of 767±404 pg/ml before and 1096±776 pg/ml after oral Vit B12 with a mean increase of 331±453 pg/ml was measured. Because of the obvious large variation, no meaningful range for normal absorption could be established. In the two patient subsets, there was no Gaussian distribution of the results, with a meridian of Vit B12 increase after absorption of 142 pg/ml, range 27–2668 pg/ml, in the group with normal ST and a meridian of 244 pg/ml ranging from 40 to 2453 pg/ml in the group with abnormal ST. Statistical nonparametric analysis did not reveal any difference between the two groups. Assuming a minimum required increase of 100 pg/ml, as suggested by the kit distributor, a sensitivity of only 27% and a specificity of 75% was obtained. The lack of any diagnostic value of this approach might be caused by the known nonintrinsic-factor mediated absorption of approximately 1% of any B12 given orally even in complete intrinsic factor deficiency and by the relatively large amount of oral Vit B12 needed for a “cold” absorption test. The latter can, thus, not replace the Schilling test.
    Type of Medium: Electronic Resource
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  • 4
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    Wien : Periodicals Archive Online (PAO)
    Journal of economics/Zeitschrift für Nazionalökonomie. 23 (1964) 209 
    ISSN: 0931-8658
    Topics: Economics
    Description / Table of Contents: "Wirtschaftspolitik"
    Abstract: Industrie-, Handels- und Verkehrspolitik
    Notes: Einzelbesprechungen
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  • 5
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    Wien : Periodicals Archive Online (PAO)
    Journal of economics/Zeitschrift für Nazionalökonomie. 23 (1964) 208 
    ISSN: 0931-8658
    Topics: Economics
    Description / Table of Contents: "Wirtschaftspolitik"
    Abstract: Industrie-, Handels- und Verkehrspolitik
    Notes: Einzelbesprechungen
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nuclear medicine 13 (1987), S. 439-442 
    ISSN: 1619-7089
    Keywords: Emission tomography ; Image distortion ; Gamma camera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Image quality in single photon emission computed tomography (SPECT) using a rotating gamma camera is dependent on the time course of the tracer in the field of view. If acquisition times are slow comapred to the tracer turnover, artifacts may occur in the reconstructed images. The properties of such artifacts were studied by computer simulation. Experimental projection data of point sources, cylindrical phantoms, and an anatomically realistic brain phantom were altered by sequentially weighting the projections with a function that varied exponentially or linearly with time. The observed distortion in the reconstructed images could be related to the ratio between the object activity variation and the camera rotation time. If the tracer concentration changed less than a factor of two during one camera rotation then little image distortion was visible although quantitatively the resolution was degraded. If the object's activity variation with time is fast enough to produce noticeable distortion, the artifacts can be reduced by performing multiple, rapid, camera rotations, instead of one rotation, for the same total acquisition time. The proposed procedure is computer storage space intensive and takes longer to produce the transaxial images, but improves image quality.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1619-7089
    Keywords: Radionuclide ventriculography ; Myocardial scanning ; Functional imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Myocardial scanning (MS) and radionuclide ventriculography (RNV) are the foundation of nuclear cardiology. These procedures aim in two completely different directions: RNV tries to image heart motion, that is, mechanical (pump) function, and therefore belongs to the group of first-order functional imaging (FI, imaging mechanical function), whereas MS is based on myocardial metabolism, and therefore can be attributed to third-order functional imaging (metabolism). This statement is relevant for the assessment of the clinical position of RNV: Third-order (metabolism) functional imaging is the domain of nuclear medicine (NM), whereas first-order FI has to face the competition of alternative noninvasive procedures such as ultrasound (US), digital subtraction angiography (DSA), computer tomography (CT), and nuclear magnetic resonance (NMR). The domain of RNV includes stages two (acute infarction) and three (postinfarction period) of coronary arterial disease (CAD). The advantageous combination of quantitative data on global, left ventricular (LV) function and imaging of regional motion ensures the superiority of RNV over US. However, RNV is inferior to MS in physical examinations in the preinfarction stage of CAD, whereas US is clearly inferior to both NM procedures. Recent progress could be attained by gated SPECT (GASPECT). A proposal is presented for simplification of this time-consuming procedure. Technetium-labeled isonitriles offer the chance for the combination of “perfusion-motion” imaging of the myocardium. However, even standard RNV offers new possibilities. The multitude of parameters produced by quantitation has not yet been exploited completely. This can be done by discriminant analysis. The computer finds out an optimal subset from the whole set of parameters for the solution of a significant clinical problem. The software “learns” to find the “label” of a special pathognomonic entity. This computer work is supported by a relational data bank (Oracle) and an optical disk. Two examples for the effectiveness of the computer in problem solving are presented. It is concluded that RNV, even in the very competitive class of first-order functional imaging, enjoys a preferred position. The future indeed seems brighter because labeled isonitriles offer the chance for the combination of perfusion-motion imaging of the myocardium.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1619-7089
    Keywords: Contraction fraction ; 99mTc-MIBI ; SPECT ; Myocardial size ; Radionuclide ventriculography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Criteria for the detection of coronary artery disease in nuclear cardiology include visualization of perfusion defects and functional impairment of contraction. The purpose of this study is to combine both methods in one procedure with the new myocardial perfusion tracer, 99mTc-methoxy-isobutyl-isonitril (MIBI), reducing time and radiation burden to the patient. Following an uncomplicated recovery, ten patients with first myocardial infarction participated in this study. Radionuclide ventriculography (RNV) was performed at rest and during exercise. Within 2–3 days, 370 MBq 99mTc-MIBI were injected and SPECT acquisition commenced 1 h later. Data processing included a scar image in polar coordinates. Areas of significantly reduced tracer uptake were expressed as a percentage of the total myocardial area. Directly following SPECT, resting and maximum exercise gated planar LAO images were recorded and the contraction was quantified. The concept of the contraction fraction (CF) rested on the end systolic change in count distribution: their increase in density and their centripetal concentration. For comparison, geometrical inner edge detection techniques were also applied. All algorithms for describing an EF equivalent were verified by computer simulations, showing a perfect correlation over a wide range of preset EFs. When applied to the patient studies only the non geometric methods revealed a good correlation with the ejection fraction (EF) obtained by RNV, and with the infarct size measured by SPECT. The corresponding correlation coefficients (r), standard errors (SEE) and the regression lines read as follows (in %): CF=0.56×EF+24.8; r=0.87; SEE=4.98; CF=-0.53×SPECT+71.5; r=0.93; SEE=4.19. Thus, estimation of the left ventricular function by the above defined CF is feasible, easy to perform and clinically meaningful. In one procedure with 99mTc-labelled MIBI not only the perfusion abnormalities were detectable, but also any reduction in function by a valied EF equivalent. Although the monochromatic gamma spectrum of the radionuclide provided better tissue penetrating power, the inner edge of the left ventricle was poorly outlined (especially in the stress studies) and does not lend itself to clinical routine practice.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1617-7134
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
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