In this study we present a noninvasive method that enables the investigation of the fetal heart rate (FHR) fluctuations. The objective was to design a quantitative measurement to assess the fetal autonomic nervous system and to investigate its development as a function of the gestational age. Our Medical Physics group has developed a complex algorithm for online beat-to-beat detection of the fetal ECG (FECG), extracted from the maternal abdominal ECG signal. We used our previously acquired FECG data, which includes noninvasive recordings of 200 maternal abdominal ECG signals. From these, we chose 35 cases of healthy pregnancies that we divided into three groups according to gestational age: Group 1, 23 +/- 2 wk; Group 2, 32 +/- 1 wk; and Group 3, 39 +/- 1 wk. The FHR variability was analyzed by a time-frequency decomposition based on a continuous wavelet transform. We showed that, independent of the gestational age, most of the FHR power is concentrated in the very-low-frequency range (0.02-0.08 Hz) and in the low-frequency range (0.08-0.2 Hz). In addition, there is power in the high-frequency range that correlates with the frequency range of fetal respiratory motion (0.4-1.7 Hz). In the intermediate-frequency range (0.2-0.4 Hz), the power is significantly smaller. The changes in the average power spectrum in relation to gestation time were carefully and quantitatively examined. The results imply that there is a neural organization during the last trimester of the pregnancy, and the sympathovagal balance is reduced with the gestational age.

A B S T R A C T Analysis of multiple noninvasive tests offers the promise of more accurate diagnosis of coronary artery disease, but discordant test responses can occur frequently and, when observed, result in diagnostic uncertainty. Accordingly, 43 patients undergoing diagnostic coronary angiography were evaluated by noninvasive testing and the results subjected to analysis using Bayes' theorem of conditional probability. The procedures used included electrocardiographic stress testing for detection of exercise-induced ST segment depression, cardiokymographic stress testing for detection of exercise-induced precordial dyskinesis, myocardial perfusion scintigraphy for detection of exerciseinduced relative regional hypoperfusion, and cardiac fluoroscopy for detection of coronary artery calcification.The probability for coronary artery disease was estimated by Bayes' theorem from each patient's age, sex, and symptom classification, and from the observed test responses. This analysis revealed a significant linear correlation between the predicted probability for coronary artery disease and the observed prevalence of angiographic disease over the entire range of probability from 0 to 100% (P < 0.001 by linear regression). The 12 patients without angiographic disease had a mean posttest likelihood of only 7.0+±2.6% despite the fact that 13 of the 60 historical and test responses were falsely "positive." In contrast, the mean posttest likelihood was 94.1±2.8% in the 31 patients with angiographic coronary artery disease, although 45 of the 155 historical and test responses were falsely "negative." In 8 of the 12 normal patients, the final posttest likelihood was under 10% and in 26 ofthe 31 coronary artery disease patients, it was over 90%. These estimates also correlated well with the pooled clinical judgment of five experienced cardiologists (P < 0.001 by linear reReceivedfor publication 13 August 1979 and in revisedform 30 November 1979. 1210 gression). The observed change in probability for disease for each of the 15 different test combinations correlated with their information content predicted according to Shannon's theorem (P < 0.001 by linear regression).These results support the use of probability analysis in the clinical diagnosis of coronary artery disease and provide a formal basis for comparing the relative diagnostic effectiveness and cost-effectiveness of different test combinations.

The assessment of the functional state of the autonomic nervous system (ANS) in real time, by means of spectral analysis of fetal heart rate variability, may serve to improve the diagnosis of pathologic conditions of importance to the perinatologist. The combination of two approaches, namely an efficient method for detecting fetal ECG from the abdominal maternal signal, followed by spectral analysis of heart rate variability, is tested as a new noninvasive tool to assess fetal viability in real time. This study demonstrates a pattern of ANS development via the spectral contents of heart rate variability. It is shown that during "quiet state," the "young" fetuses (gestational age = 23.5 +/- 1 wk) present twice as much power of heart rate fluctuations at all frequencies from 0.2 to 1.0 Hz as "mature" fetuses (gestational age = 39.75 +/- 1.5 wk). This finding is coherent with the evolution of a stable and mature ANS activity. At frequencies below 0.1 Hz, a 1/f alpha power law relationship (alpha = 0.85, r2 > 0.9) between spectral density and frequency is displayed in the two age groups. A respiratory peak has been observed in some of the short (64-s) traces we analyzed. However, no respiratory peak was ever observed in a long (256-s) trace, due to the episodic nature of the fetal breathing and immaturity of the ANS.

We describe some of the design choices that were made during the development of a fast, scalable, inline, deduplication device. The system's design goals and how they were achieved are presented. This is the firs deduplication device that uses similarity matching. The paper provides the following original research contributions: we show how similarity signatures can serve in a deduplication scheme; a novel type of similarity signatures is presented and its advantages in the context of deduplication requirements are explained. It is also shown how to combine similarity matching schemes with byte by byte comparison or hash based identity schemes.

Strong thermal emission velocity enhancement (STEVE) is an optical phenomenon of the subauroral ionosphere arising from extreme ion drift speeds. STEVE consists of two distinct components in true-color imagery: a mauve or whitish arc extended in the magnetic east-west direction and a region of green emission adjacent to the arc, often structured into quasiperiodic columns aligned with the geomagnetic field (the "picket fence"). This work employs high-resolution imagery by citizen scientists in a critical examination of fine-scale features within the green emission region. Of particular interest are narrow "streaks" of emission forming underneath field-aligned picket fence elements in the 100-to 110-km altitude range. The streaks propagate in curved trajectories with dominant direction toward STEVE from the poleward side. The elongation is along the direction of motion, suggesting a drifting point-like excitation source, with the apparent elongation due to a combination of motion blur and radiative lifetime effects. The cross-sectional dimension is <1 km, and the cases observed have a duration of ∼20-30 s. The uniform coloration of all STEVE green features in these events suggests a common optical spectrum dominated by the oxygen 557.7-nm emission line. The source is most likely direct excitation of ambient oxygen by superthermal electrons generated by ionospheric turbulence induced by the extreme electric fields driving STEVE. Some conjectures about causal connections with overlying field-aligned structures are presented, based on coupling of thermal and gradient-drift instabilities, with analogues to similar dynamics observed from chemical release and ionospheric heating experiments. Plain Language Summary STEVE is a recently identified atmospheric phenomenon caused by supersonic plasma jets flowing at altitudes >100 km. STEVE appears as a whitish pink arc extending in the magnetic east-west direction, which is often accompanied by an adjacent region of green features. In some cases, the green features appear as periodic vertical columns resembling a "picket fence". These features were thought to be caused by the same mechanism as the aurora, but the color is wrong. This article examines these features from a morphological perspective. We use time lapse images recorded by citizen scientists to examine fine-scale structures in STEVE's green emission region. We focus particular attention on a narrow streak of emission commonly observed underneath the picket fence. These streaks have width of just a few hundred meters and propagate horizontally. They have identical coloration to other green objects in the field, suggesting a common source. Although we cannot state conclusively what that source mechanism is, they are most likely excited by turbulent heating related to the extreme plasma flows of STEVE. Our initial analysis suggests a physical connection between these tiny streaks and the extended picket fence features above them. Advancing this physics will benefit greatly from continued involvement of citizen scien...