Inference of Absolute Time Value from Temporal Expressions

Changes in myocardial metabolism can be detected externally by registration of time-activity curves after administration of radioiodinated fatty acids. In this scintigraphic study the influence of lactate on fatty acid metabolism was investigated in the normal human myocardium, traced with 123l-17-iodoheptadecanoic acid (123l-17-HDA). In patients (paired, n = 7) lactate loading decreased the uptake of 123l-17-HDA significantly from 27 (control: 22-36) to 20 counts/min/pixel (16-31; p <0.05 Wilcoxon). The half-time value increased to more than 60 rriin (n = 5), oxidation decreased from 61 to 42%. Coronary vasodilatation, a well-known side effect of lactate loading, was studied separately in a dipyridamole study (paired, n = 6). Coronary vasodilatation did not influence the parameters of the time-activity curve. These results suggest that changes in plasma lactate level as occurring, among other effects, during exercise will influence the parameters of dynamic 123l-17-HDA scintigraphy of the heart.

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Analysis of Myocardial Time-Activity Curves of 123l-Heptadecanoic Acid II. The Acquisition Time

Nuklearmedizin ◽

10.1055/s-0038-1628898 ◽

1987 ◽

Vol 26 (06) ◽

pp. 248-252 ◽

Cited By ~ 3

Author(s):

M. J. van Eenige ◽

F. C. Visser ◽

A. J. P. Karreman ◽

C. M. B. Duwel ◽

G. Westera ◽

...

Keyword(s):

Standard Deviation ◽

Acquisition Time ◽

Half Time ◽

Constant Ratio ◽

Time Activity ◽

Time Activity Curve ◽

Time Value ◽

Activity Curve ◽

Low Amplitude ◽

Parameter Values

Optimal fitting of a myocardial time-activity curve is accomplished with a monoexponential plus a constant, resulting in three parameters: amplitude and half-time of the monoexponential and the constant. The aim of this study was to estimate the precision of the calculated parameters. The variability of the parameter values as a function of the acquisition time was studied in 11 patients with cardiac complaints. Of the three parameters the half-time value varied most strongly with the acquisition time. An acquisition time of 80 min was needed to keep the standard deviation of the half-time value within ±10%. To estimate the standard deviation of the half-time value as a function of the parameter values, of the noise content of the time-activity curve and of the acquisition time, a model experiment was used. In most cases the SD decreased by 50% if the acquisition time was increased from 60 to 90 min. A low amplitude/constant ratio and a high half-time value result in a high SD of the half-time value. Tables are presented to estimate the SD in a particular case.

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Chief Resource Management Officer

Departures in Critical Qualitative Research ◽

10.1525/dcqr.2014.3.2.144 ◽

2013 ◽

Vol 3 (2) ◽

pp. 144-150

Author(s):

Ellen Mueller

Keyword(s):

Resource Management ◽

Corporate Management ◽

Time Value ◽

Asking Questions

This series of videos, Chief Resource Management Officer, decontextualizes and amplifies mundane tasks and actions, exposing an inherent absurdity and dry humor. Conceptually and visually, I engage themes of corporate management structures, cult dynamics, and Sisyphean tasks. Within this work, I am primarily interested in developing situations that disrupt familiar social and political hierarchies. Utilizing recognizable apparel and gestures, I playfully occupy the threshold of absurdity while asking questions about time, value, routines, and the monetization of work and/or presence.

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