Self-attraction effect and correction on three absolute gravimeters

The perturbations of the gravitational field due to the mass distribution of an absolute gravimeter have been studied. The so called Self Attraction Effect (SAE) is crucial for the measurement accuracy, especially for the International Comparisons, and for the uncertainty budget evaluation. Three instruments have been analysed: MPG-2, FG5-238 and IMPG-02. The SAE has been calculated using a numerical method based on FEM simulation. The observed effect has been treated as an additional vertical gravity gradient. The correction (SAC) to be applied to the computed g value has been associated with the specific height level, where the measurement result is typically reported. The magnitude of the obtained corrections is of order 1E-8 m/s2.Comment: 14 pages, 8 figures, submitted to Metrologi

Correction due to finite speed of light in absolute gravimeters

Correction due to finite speed of light is among the most inconsistent ones in absolute gravimetry. Formulas reported by different authors yield corrections scattered up to 8 $\mu$Gal with no obvious reasons. The problem, though noted before, has never been studied, and nowadays the correction is rather postulated than rigorously proven. In this paper we make an attempt to revise the subject. Like other authors, we use physical models based on signal delays and the Doppler effect, however, in implementing the models we additionally introduce two scales of time associated with moving and resting reflectors, derive a set of rules to switch between the scales, and establish the equivalence of trajectory distortions as obtained from either time delay or distance progression. The obtained results enabled us to produce accurate correction formulas for different types of instruments, and to explain the differences in the results obtained by other authors. We found that the correction derived from the Doppler effect is accountable only for $\frac23$ of the total correction due to finite speed of light, if no signal delays are considered. Another major source of inconsistency was found in the tacit use of simplified trajectory models

The Mechanisms Responsible for Lack of Reproducible Induction of Atrioventricular Nodal Reentrant Tachycardia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75434/1/j.1540-8167.1996.tb00556.x.pd

A Quantitative Fluoroscopic Comparison of the Coronary Sinus Ostium in Patients With and Without AV Nodal Reentrant Tachycardia

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75367/1/j.1540-8167.1995.tb00444.x.pd

Perturbations of the local gravity field due to mass distribution on precise measuring instruments: a numerical method applied to a cold atom gravimeter

We present a numerical method, based on a FEM simulation, for the determination of the gravitational field generated by massive objects, whatever geometry and space mass density they have. The method was applied for the determination of the self gravity effect of an absolute cold atom gravimeter which aims at a relative uncertainty of 10-9. The deduced bias, calculated with a perturbative treatment, is finally presented. The perturbation reaches (1.3 \pm 0.1) \times 10-9 of the Earth's gravitational field.Comment: 12 pages, 7 figure

Comparison between two mobile absolute gravimeters: optical versus atomic interferometers

We report a comparison between two absolute gravimeters: the LNE-SYRTE cold atoms gravimeter and FG5#220 of Leibniz Universit\"at of Hannover. They rely on different principles of operation: atomic and optical interferometry. Both are movable which enabled them to participated to the last International Comparison of Absolute Gravimeters (ICAG'09) at BIPM. Immediately after, their bilateral comparison took place in the LNE watt balance laboratory and showed an agreement of 4.3 +/- 6.4 {\mu}Gal

927-37 Is Coronary Revascularization Complete Therapy for Secondary Prevention of Ischemic Cardiac Arrest?

Coronary revascularization has been suggested assole therapy for secondary prevention of sudden cardiac arrest associated with ischemia. Among 412 consecutive patients receiving an implantable defibrillator (ICD), 23 (6%) were identified as: sudden cardiac arrest survivors, noninducible with programmed stimulation, unstable angina or ischemia on a functional study, and underwent successful coronary revascularization. In follow-up, 10 (43%) of the 23 patients received ICD shocks (8±8 per patient, range: 1–22) shocks) and 9/10 had syncope/presyncope associated with at least one ICD discharge.Clinical Characteristics:ICD firings (n=10)*No ICD firings (n=13)*Follow-up (months)39±1331±21Age (years)63±763±12Male gender89Mean left ventricular ejection fraction (%)36±1040±14Previous history of a myocardial infarction1010Presence of a left ventricular aneurysm41Q-wave infarction pattern on electrocardiogram75Sudden cardiac arrest presenting with exertion, angina, or CPK elevation88Mean number of vessels with coronary disease2.2±0.823±0.9Mean severity of coronary stenosis (%)87±1888±16Coronary revascularization considered complete710β-blocker therapy55Antiarrhythmic therapy812*p value>0.05No clinical characteristic was statistically different between patients with and without ICD shocks. In conclusion, coronary revascularization alone may be inadequate therapy for survivors of sudden cardiac arrest associated with ischemia who are noninducible with programmed stimulation, and clinical variables cannot predict which patients are likely to experience recurrent malignant ventricular arrhythmias. Therefore, ICD therapy should be considered in these patients

The Economic Impact of Transvenous Defibrillation Lead Systems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72437/1/j.1540-8159.1994.tb02379.x.pd

927-37 Is Coronary Revascularization Complete Therapy for Secondary Prevention of Ischemic Cardiac Arrest?

Coronary revascularization has been suggested assole therapy for secondary prevention of sudden cardiac arrest associated with ischemia. Among 412 consecutive patients receiving an implantable defibrillator (ICD), 23 (6%) were identified as: sudden cardiac arrest survivors, noninducible with programmed stimulation, unstable angina or ischemia on a functional study, and underwent successful coronary revascularization. In follow-up, 10 (43%) of the 23 patients received ICD shocks (8±8 per patient, range: 1–22) shocks) and 9/10 had syncope/presyncope associated with at least one ICD discharge.Clinical Characteristics:ICD firings (n=10)*No ICD firings (n=13)*Follow-up (months)39±1331±21Age (years)63±763±12Male gender89Mean left ventricular ejection fraction (%)36±1040±14Previous history of a myocardial infarction1010Presence of a left ventricular aneurysm41Q-wave infarction pattern on electrocardiogram75Sudden cardiac arrest presenting with exertion, angina, or CPK elevation88Mean number of vessels with coronary disease2.2±0.823±0.9Mean severity of coronary stenosis (%)87±1888±16Coronary revascularization considered complete710β-blocker therapy55Antiarrhythmic therapy812*p value>0.05No clinical characteristic was statistically different between patients with and without ICD shocks. In conclusion, coronary revascularization alone may be inadequate therapy for survivors of sudden cardiac arrest associated with ischemia who are noninducible with programmed stimulation, and clinical variables cannot predict which patients are likely to experience recurrent malignant ventricular arrhythmias. Therefore, ICD therapy should be considered in these patients

A 1.82 m^2 ring laser gyroscope for nano-rotational motion sensing

We present a fully active-controlled He-Ne ring laser gyroscope, operating in square cavity 1.35 m in side. The apparatus is designed to provide a very low mechanical and thermal drift of the ring cavity geometry and is conceived to be operative in two different orientations of the laser plane, in order to detect rotations around the vertical or the horizontal direction. Since June 2010 the system is active inside the Virgo interferometer central area with the aim of performing high sensitivity measurements of environmental rotational noise. So far, continuous not attempted operation of the gyroscope has been longer than 30 days. The main characteristics of the laser, the active remote-controlled stabilization systems and the data acquisition techniques are presented. An off-line data processing, supported by a simple model of the sensor, is shown to improve the effective long term stability. A rotational sensitivity at the level of ten nanoradiants per squareroot of Hz below 1 Hz, very close to the required specification for the improvement of the Virgo suspension control system, is demonstrated for the configuration where the laser plane is horizontal