119 Result(s)
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R. Jenkins
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Systems of Psychiatric Care: Principles and Desiderata of Good Services
Systems of psychiatric care can be conceived of as complex, multi-dimensional frameworks or matrices which do not exist in isolation but are firmly rooted in and influenced by prevailing mores, political clima...
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Psychiatrische Versorgungsstrukturen: Prinzipien und Voraussetzungen einer adäquaten Versorgung
Psychiatrische Versorgungsstrukturen stellen komplexe, multidimensio-nale Systeme oder Raster dar, die nicht unabhängig bestehen, sondern in allgemeinen Wertvorstellungen, dem politischen Klima und kulturellen...
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Immediate-early gene activation as a window on mechanism in the nervous system
Immediate early genes (IEGs) were originally described as a class of genes rapidly and transiently expressed in cells stimulated with growth factors without the requirement for de novo protein synthesis (Cochr...
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Interleukin-2 Induced Changes in Mononuclear Cell Surface Charge
Interleukin-2 (IL-2) is not only the hormone responsible for progression of the T cell cycle, but it is also a potent activator of cytolytic (lymphokine-activated killer, LAK) activity against a wide variety o...
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Crystal Structures of EumgF4, SmMgF4 and SrMgF4
Crystal structures of EuMgF4 and SrMgF4 were determined using a computer-controlled x-ray powder diffractometer. Single crystal growth has been unsuccessful to date because the materials melt incongruently. It wa...
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Estimation of Error Introduced by Ignoring the Background
Whenever X-ray intensity measurements are made on a selected peak, occuring at a certain setting of the goniometer, some fraction of the measured counting rate is always due to background. The significance of ...
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Variation of limit of detection with analysis time
A series of measurements of fluorine in cement sample yielded a peak counting rate of 4 c/s/% for fluorine (F Kα) over a background of 6.5 c/s.
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Continuous radiation — Scattered radiation
A The continuous radiation from an X-ray tube is scattered by the sample, diffracted by the analyzing crystal and measured by the detector.
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Particle statistics in X-ray diffractometry
Only those crystallites having the reflecting planes almost parallel to the specimen surface can contribute to a certain reflection. The intensity of the resulting diffraction is thus dependent on this number ...
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Dispersion as a function of ‘d’ spacing
LiF is commonly used as an analysing crystal. The (200) reflection planes are commonly used, having a “2d” value of 4.028 Å. It is, however, possible to use reflecting planes with other Miller indices (hkl) for e...
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Determination of CaO in cement (ratio measurement)
The following data were obtained using a series of cement samples. Counting ratios were determined on the Ca Kα line using sample 5 as the ratio standard.
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Absorption correction involving primary and secondary absorption
The slope of a calibration curve for a certain element is dependent upon the total absorption of the measured wavelength within the sample matrix. Although it is common practice to assume that only secondary a...
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Pulse height selection — crystal fluorescence
It is necessary to set up an X-ray spectrometer for the measurement of sodium in a series of rock specimens. An argon/methane flow counter is being employed and a KAP (potassium hydrogen phthalate) analysing ...
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Calculation of matrix absorption and prediction of absorption effects
The total secondary absorption of a matrix is given by
16 <math display='block'> <mrow> <msub> <mi>μ</mi> <mrow> <mi>m</mi><mi>a</mi><mi>t</mi><mi>r</mi><mi>i</mi><mi>x</mi... -
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Calculation of quantity of heavy absorber needed to minimize matrix effects
In the analysis of tin ores it is found that a very curved calibration line is obtained due to the large difference in the mass absorption coefficients of the two matrix components Sn (µ = 13) and SiO2 (µ = 1.80)...
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Use of α correction factors (concentration correction)
A series of samples are being analysed for lead using the Pb Lα line. It is found that zinc which is also present strongly absorbs the Pb Lα wavelength resulting in a very poor calibration curve. The following da...
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Quantitative diffractometry — determination of Anatase in Rutile
A sample is known to contain two crystalline modifications of TiO2, namely rutile and anatase. Spectrographic analysis failed to reveal the presence of other elements, so the sample can be assumed to consist only...
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Determination of dead time
It is necessary to determine the dead time of an X-ray spectrometer using the Kβ/Kα counting ratio method. The following data were obtained on the Kα and Kβ lines of tin by varying the X-ray tube current and keep...
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Estimation of expected intensities in mixtures
The intensity of the 3.34 Å line of α-quartz (SiO2) has to be estimated in a mixture consisting of 10% α-quartz and 90% CaSiO3. Nickel filtered Cu Kα radiation is used. The intensity of the 3.34 Å line in pure α ...
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Measurement of coating thickness on irregular shaped objects
The thickness of Cr plating on a piece of iron of rather irregular but flat shape has to be measured.
