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We develop a comprehensive approach to the evaluation of the uncertainty of a primary frequency standard. Indirect, model-dependent means are employed for the evaluation of all known biases. This approach leads to a lower combined standard uncertainty (CSU) and leaves frequency measurements under altered conditions as a powerful search technique for unknown… (More)
We report idiopathic chylopericardium in a physically active, asymptomatic 29-year-old man. Preoperative diagnosis was made by external cardiac imaging after oral administration of 131-I-labeled triolein. To our knowledge this is the first report of preoperative noninvasive diagnosis of chylopericardium. After open drainage and pericardial biopsy, the… (More)
The evaluation procedure of a new laser-cooled caesium fountain primary frequency standard developed at the National Institute of Standards and Technology (NIST) is described. The new standard, NIST-F1, is described in some detail and typical operational parameters are discussed. Systematic frequency biases for which corrections are made – second-order… (More)
We discuss the implications of using high-power microwave tests in a fountain frequency standard to measure the frequency bias resulting from distributed cavity-phase shifts. We develop a theory which shows that the frequency bias from distributed cavity phase depends on the amplitude of the microwave field within the cavity. The dependence leads to the… (More)
In atomic fountain primary frequency standards, the atoms ideally are subjected to microwave fields resonant with the ground-state, hyperfine splitting only during the two pulses of Ramsey's separated oscillatory field measurement scheme. As a practical matter, however, stray microwave fields can be present that shift the frequency of the central Ramsey… (More)
The presence of spurious spectral components in the microwave excitation may induce frequency shifts in an atomic fountain frequency standard. We discuss how such shifts behave as a function of power variations of the excitation carrier and in the spur-to-carrier ratio. The discussion here is limited to the case of single-sideband spurs, which are generally… (More)
An unusually high association of other primary cancers (9.7%) was found during the analysis of 403 consecutive cases of carcinoma of the lung diagnosed at DGMC between 1960 and 1975. Incidence by stage included 17.3% for Stage I (75 cases) and 16.9% for Stage II (59 cases). Median survival by stage was not adversely affected by the associated malignancy.… (More)
The case history of a young man with bilateral intralobar sequestrations is presented. The patient underwent bilateral resection of the sequestrations, although only the left side was symptomatic. We have found no previous reports in the literature in which bilateral pulmonary resections were performed for this condition. We present the clinical features… (More)
The National Institute of Standards and Technology is developing an optically pumped, cesium-beam primary frequency standard. The design follows from an analysis of systematic errors found in cesium beam standards. The details of the design, performance of major subsystems, and preliminary tests of the standard are presented .
† We show that the frequency bias caused by distributed cavity phase has a strong dependence on microwave power. We also show that frequency biases associated with microwave leakage have distinct signatures in their dependence on microwave power and the physical location of the leakage interaction with the atom.