Fetal Doppler mechanical PR interval: correlation with fetal heart rate, gestational age and fetal sex.

OBJECTIVES: To establish normal fetal values for the mechanical PR interval by pulsed-wave Doppler at 16-36 weeks of gestation, and to evaluate the influence of fetal heart rate (FHR), gestational age (GA) and fetal sex. METHODS: Fetal mechanical PR intervals were evaluated prospectively by obstetric ultrasound examination. Healthy mothers with sonographically normal fetuses from singleton pregnancies were included. Mechanical PR intervals were measured from simultaneous mitral and aortic Doppler waveforms, from the onset of left atrial contraction (mitral A-wave) to the onset of left ventricular ejection (aortic pulse wave). Simple and multiple linear regression analyses were performed to examine the correlation between PR interval and GA, FHR and fetal sex. RESULTS: We evaluated 336 fetuses at 16-36 weeks. The mean +/- SD FHR was 143.4 +/- 8.3 beats per min (bpm). The PR intervals had a typical Gaussian distribution with a mean +/- SD of 122.4 +/- 10.3 ms. Robust linear regression showed that the PR increased by about 0.40 ms (95% CI, 0.22-0.58) per gestational week (P < 0.001), and this relationship remained after adjustment for FHR and fetal sex. PR intervals diminished by 1.4 (95% CI, 0.75 to 2.0) ms for each 5 bpm increase in FHR (P < 0.001), independently of GA and fetal sex. No fetal sex differences were observed. CONCLUSIONS: We provide normal fetal values for the mechanical PR interval at 16-36 weeks of gestation. Mechanical PR intervals in normal fetuses are influenced by GA and FHR independently, and both variables should be taken into account when evaluating fetuses at risk for congenital heart block.

Two-channel Kondo effect in glasslike ThAsSe.

We present low-temperature heat and charge transport as well as caloric properties of a ThAsSe single crystal. An extra -AT(1/2) term in the electrical resistivity, independent of magnetic fields as high as 14 T, provides evidence for an unusual scattering of conduction electrons. Additionally, both the thermal conductivity and the specific heat show a glass-type temperature dependence which signifies the presence of tunneling states. These observations apparently point to an experimental realization of a two-channel Kondo effect derived from structural two-level systems.

Structural studies on single crystals of Chevrel phase selenides REMo6Se8 (RE = La, Ce, Pr, Nd, or Sm) at 298 K.

We report on structural studies at room temperature of rare-earth based Chevrel phase selenides of the formula RExMo6Se8, where RE stands for a light rare-earth La (1), Ce (2), Pr (3), Nd (4), or Sm (5). The single crystals were grown at 1650 degrees C < T < 1690 degrees C from off-stoichiometric starting compositions, with the exception of 3, which was grown at 1710 degrees C from a stoichiometric charge (congruently melting material). The crystal structures were solved in space group R3 (No. 148; Z = 1) and found to be isostructural with the well-known Chevrel phases having large cations (e.g., PbMo6S8, REMo6S8). The structures are based on Mo6Se8 metallic clusters that are slightly rotated inside a pseudocubic rare-earth sublattice. Structural refinements revealed that the origin site, occupied by the RE atoms, exhibits slight deficiencies, leading to a RExMo6Se8 composition, with x ranging between approximately 0.82 and approximately 0.92: 1 La0.88Mo6Se8, arh = 6.7577(9) A, alpha rh = 88.62(2) degrees; 2a Ce0.82Mo6Se8, arh = 6.7407(6) A, alpha rh = 88.83(2) degrees; 2b Ce0.92Mo6Se8, arh = 6.7473(9) A, alpha rh = 88.69(2) degrees; 3 Pr0.86Mo6Se8, arh = 6.7385(6) A, alpha rh = 88.81(2) degrees; 4 Nd0.85Mo6Se8, arh = 6.7286(5) A, alpha rh = 88.85(1) degrees; and 5 Sm0.87Mo6Se8, arh = 6.7182(2) A, alpha rh = 88.956(3) degrees. All of the structural data presented in this work (lattice constants, positional parameters and interatomic distances) concern an average RE content of x approximately 0.87. In this way, any influence due to electronic effects (VEC number) can be discarded, and exact correlations between these parameters and the ionic radius of the rare-earth atoms can then be established.

[Transient involuntary movements after severe cranio-cerebral trauma]. / Przemijajace ruchy mimowolne u chorego po ciezkim urazie czaszkowo-mózgowym.

In a patient rhythmic, coarse tremor of the right hand and fingers 5/sec. was observed 5 weeks after severe craniocerebral injury. The tremor occurred at rest and increased during movements but disappeared in sleep. In view of associated mask-like facial expression, salivation, cog-wheel sign in the right upper extremity the diagnosis of traumatic, hemiparkinsonian syndrome was made and treatment with Nacom was started. Normal concentration of homovanilic acid in the cerebrospinal fluid and lack of effect of Nacom treatment failed to confirm this diagnosis. Nine weeks after trauma a rotatory movement of the right upper extremity appeared additionally. It is to be accepted that this was an involuntary movement poorly classificable which disappeared spontaneously.