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[en] Probabilities of longitudinal wave emission by an atom traveling in a plasma in the region of anomalous Doppler effect, are obtained. The role of the recoil effect is evaluated. The question of the influence of the form of a Hamiltonian upon the probabilities indicated is discussed. (orig.)
[en] Kitt Peak data on O-type stars have been combined with those of Morrison (1975) to derive interstellar reddening slopes for the uvby system. The results are E(c1) = 0.20 E(b--y), E(m1) = -0.32 E(b - y), E(u - b) = 1.5 E(b - y), and E(b - y) = 0.74 E(B - V). (auth)
[en] The most luminous quasars (with bolometric luminosities are ≳ 1047 erg/s) show a high prevalence of CIV λ1549 and [OIII]λλ4959,5007 emission line profiles with strong blueshifts. Blueshifts are interpreted as due to Doppler effect and selective obscuration, and indicate outflows occurring over a wide range of spatial scales. We found evidence in favor of the nuclear origin of the outflows diagnosed by [OIII]λλ4959,5007. The ionized gas mass, kinetic power, and mechanical thrust are extremely high, and suggest widespread feedback effects on the host galaxies of very luminous quasars, at cosmic epochs between 2 and 6 Gyr from the Big Bang. In this mini-review we summarize results obtained by our group and reported in several major papers in the last few years with an eye on challenging aspects of quantifying feedback effects in large samples of quasars.
[en] Ultrasound is now accepted as important in cardiac diagnosis. It is possible to get information about the heart both from echocardiography and Doppler ultrasound, which is not available by other diagnostic methods. It is also possible, in some circumstances, to obtain the information normally achieved by cardiac catheterisation and so avoid an invasive study
[en] The lunula is the white, half-moon-shaped area seen on some, but not all nails. Usually the lunula is the topographic marker of the distal part of the nail matrix, and known to have the ability of nail production. Ultrasonographic imaging of the lunula has not been reported before. This study was undertaken to demonstrate normal ultrasonographic features of the lunula. Ultrasonographic examination of the lunula was performed in the right thumb of 20 healthy volunteers (10M, 10F, mean age 30, range 26-36 years) with a real-time, high-resolution ultrasound unit (Sequoia 512, Acuson, Mountain view, CA, USA) with 8-15 MHz linear transducers. Gray scale color, and special Doppler imagings were performed with longitudinal scanning. The lunula was not seen inspection in three of the 20 volunteers. The mean size of the lunula in the other 17 volumteen was 3.31 ± 1.24 mm (range 2-6.2 mm). Gray scale ultrasound imaging showed the lunula; ovoid shaped hypo-echoic zone in proximal fingernail in 18 of 20 volunteers (mean size, 6.74 ± 0.98 mm, range 5-8.8 mm). In two of 20 volunteers, the lunula was indistinct on gray scale ultrasound examination. However, all lunula were identifiable on color Doppler imaging by detecting vascularity within the lunula. Spectral wave pattern of the lunula was a bi-directional pulsatile wave. Peak velocity was within 5-15 m/sec (mean 8 m/sec). The lunula is identifiable on ultrasound examination as a hyper-vascular, ovoid shaped, hypo-echoic zone in proximal fingernail. This normal structure should not be misinterpreted as an abnormal sub-ungual lesion.
[en] Our purpose was to investigate the relation between the vascular resistance of uterine artery and placental location and to establish the reference value of Doppler index in uterine artery by placental location. Placental location and flow velocity waveforms of both uterine arteries in 7,016 pregnant women after 18 weeks gestation were examined using color Doppler ultrasonography. Placental location was classified as central and lateral placental and the uterine artery with lateral placental were divided into ipsilateral uterine artery (same side of the placental) and contralateral uterine artery (opposite side of the placenta). The uterine artery with central placental was classified as the central uterine artery. Systolic-Diastolic ratio (S/D ratio) of uterine arteries by gestational weeks were calculated and compared with the placental location and perinatal outcomes. In the lateral placental group, the S/D ratio of the contralateral uterine artery was higher than the ipsilateral one (mean=2.08+0.34 vs 1.89+0.34, p=0.0001). S/D ratio of the uterine artery decreased during second trimester and the ratio after 27 weeks was a tendency to have a constant values(ipsilateral: 1.85+ 0.34, central : 1.96+ 0.40, contralateral: 2.01+0.54). S/D ratio of the uterine artery was affected by placental location. So when we evaluate Doppler spectrum of uterine artery, placental location should be considered and we established the reference value of Doppler index of uterine artery by placental location.
[en] A brief account is given of Christian Doppler's scientific activities during his stay in Prague, as well as of events organized in Prague and abroad on the occasion of the 150th anniversary of discovery of the effect named after Doppler (1842). (Z.S.). 4 figs., 7 refs