Lowermost mantle anisotropy beneath the Pacific: Imaging the source of the Hawaiian plume

We utilized recordings of seismic shear phases provided by several North American broadband seismometer arrays to provide unique constraints on shear wave anisotropy beneath the northern and central Pacific Ocean. Using a new analysis method that reduces measurement errors and enables the analysis of a larger number of available waveforms, we examined relative travel times of teleseismic S and Sdiff that sample a large area of lowermost mantle structure. The results of this study provide evidence for small-scale lateral and depth variations in shear wave anisotropy for a broad region of the lowermost mantle beneath the Pacific Ocean. In particular, we image a localized zone of anomalously strong anisotropy whose strength increases toward the top of D″ beneath Hawaii. Our results, combined with a previous study of V_P/V_SH ratios, indicate that ancient subducted slab material may be responsible for observations beneath the northern Pacific, while lenses or layers of core–mantle boundary reaction products or partial melt, oriented by horizontal inflow of mantle material to the Hawaiian plume source, can explain observations beneath the central Pacific.     

Combined analysis and test of earthquake-resistant circuit breakers

Following the severe earthquake damage at San Fernando in 1971, it became of technical and perhaps psychological importance to demonstrate that properly re-designed electrical equipment is able to withstand even worse transient vibration phenomena which can be produced in an earthquake simulator laboratory. This has been accomplished for one column of a 500 kV gas circuit breaker and the test results are used to qualify the much larger original 3-column assembly by means of a computer-aided structural analysis. Since the equipment exhibited some closely spaced, cross-coupled modes of vibration, a valuable comparison could be obtained between the effects produced by El Centro 1940 ground acceleration and those for a more purposeful sine beat vibration input. The latter can be adjusted to produce definite stresses and fatigue effects in specific parts of the equipment due to quasi-resonance response.     

Quasitrapped protons (E p =1–11 MeV) nearL=4 registered by intercosmos-13 satellite

Summary Data obtained from apparatus detecting energetic particles on low altitude polar orbiting satellite Intercosmos-13 show enhancement of quiasitrapped proton flux (E_p=1–11 MeV) near L=4 in comparison with both and lower L. This phenomenon persists during intervals with low level of geomagnetic activity. Possibility of influence of false pulses on the result is discussed.     

Ion whistlers in mid-latitude trough of light ions

Summary In the set of VLF data from the Interkosmos-14 satellite (launched on 11 December 1975 with apogee height of 1707 km, perigee 345 km and inclination 74°) as received in direct telemetry transmissions at the Observatory Panská Ves (Czechoslovakia), ion cyclotron whistlers were found at unusually high geomagnetic latitudes. These whistlers indicate a marked decrease of proton density in the close vicinity of the satellite with increasing geomagnetic latitude. It appeared, moreover, that proton whistlers at higher geomagnetic latitudes even sensitively reflected the rapid changes of plasma parameters within the region of the mid-latitude trough of light ions.     

Airborne microorganisms: Their occurrence,distribution and dependence on environmental factors — Especially on organic compounds of air-pollution

For a period of approximately six months the concentrations of airborne microorganisms were determined by the uptake of their day-characteristic at local places differing by the extent of air pollution. By simultaneously recording the meteorological parameters as temperature, relative humidity, direction and velocity of wind and intensity of solar radiation, it was intended to find out the relationship between these factors and the viability of airborne microorganisms. The present data show an oscillation of the concentration counts over a wide range and seem not yet to depend on the local situation of air pollution.In a further series of experiments the atmospheric aerosol <10 m was collected on air-filters. The decreased substances were extracted from the filter material by aqueous and organic solutants and tested for their antimicrobial activities. In this context the seasonal dependence of the microbicidal activity of organic compounds of aerosol is discussed.     

The deflection of the vertical in the Western and Central Mediterranean area

The deflection of the vertical at 23 stations was determined by gravimetrical methods and compared to the difference of astronomic observations and geodetic values of the European adjustment. The results show a fair agreement between the two independent sets of values, indicating that doubts about the relative reliability of submarine gravity observations are not justified. A systematic discrepancy in the meridian components of the deflection may reflect on theHayford ellipsoid as used in the European adjustment.

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Zusammenfassung Auf 23 Stationen wurde die Lotabweichung gravimetrisch bestimmt und den astro-geod?tischen Werten der europ?ischen Ausgleichung gegenübergestellt. Die beiden Ergebnisse stimmen sehr gut überein. Damit werden die Bedenken hinf?llig, die sich gegen den Wert von Messungen in Unterseebooten richteten. Systematische Abweichungen in den meridionalen Komponenten beruhen m?glicherweise auf der art der Anwendung des Hayfordschen Ellipsoids in der Ausgleichung des Zentraleurop?ischen Netzes.

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Resumen La desviación de la vertical en 23 estaciones ha sido determinada por el método gravimétrico y compara con los resultados astrogeodéticos de la compensación europea. Existe muy buen acuerdo entre los dos conjuntos de datos, que demuestra que las dudas emitidas en cuanto al valor de las observaciones en submarino son injustificadas. Una discordancia sistemática en las componentes meridianas podria ser debida al empleo del elipsoide deHayford en la compensación de la red europea.

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Résumé La déviation de la verticale en 23 stations a été déterminée par la méthode gravimétrique et comparée aux résultats astrogéodésiques de la compensation européenne. Il y a très bon accord entre les 2 ensembles de données, ce qui montre que les doutes émis quant à la valeur des observations en sous-marins sont injustifiés. Une discordance systématique dans les composantes méridiennes pourrait être due à la fa?on dont on a employé l'ellipso?de deHayford dans la compensation du réseau central européen.

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Sommario E'stata determinata col metodo gravimetrico la deviazione della verticale in 23 stazioni e comparata ai risultati astro-geodetici della compensazione europea. Vi é molto buon accordo tra i due insiemi di dati, ciò che dimostra che i dubbi emessi circa il valore delle osservazioni in sottomarino sono ingiustificati. Una discordanza sistematica tra le componenti maridiane potrebbe essere dovuta all'impiego nella compensazione della rete central europea dell'ellisoide diHayford.

     

Die Kristallstruktur von Molybdomenit,PbSeO3

Zusammenfassung Die Kristallstruktur von Molybdomenit, PbSeO₃, wurde mit Hilfe von Einkristallmethoden bestimmt und nach der Methode der kleinsten Quadrate verfeinert. Die Gitterparameter, der Elementarzelle (Raumgruppe P2₁/m–C _2h ² ) betragen:a ₀=6,91,b ₀=5,48,c ₀=4,51 Å, =112° 50;Z=2. Mit allen beob. Reflexen wurde einR-Wert von 0,079, unter Einschluß derHamilton-Reflexe einR-Wert von 0,092 erhalten. Die Selenatome sitzen an der Spitze einer trigonalen Pyramide, deren Basis aus drei Sauerstoffatomen besteht. Die vier nächsten Sauerstoffnachbarn des Bleis liegen zwar auf einer Seite, doch sind die weiteren fünf Sauerstoffabstände nicht viel länger. Die Baueinheiten sind zu einem dreidimensionalen Gerüst verknüpft.

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The crystal structure of molybdomenite, PbSeO₃

Summary The crystal structure of molybdomenite, PbSeO₃, has been determined by single crystal X-ray methods and refined by the full-matrix least-squares technique. Molybdomenite crystallizes in the monoclinic space group P 2₁/m–C _2h ² ,a ₀=6.91,b ₀=5.48,c ₀=4.51, =112° 50;Z=2. With all abserved reflections aR=0.092. The SeO₃ ^2–-ion has a pyramidal shape with the selenium at the vertex and three oxygen atoms at the base. Lead has the nearest four oxygen neighbours lying all to one side, but ht edistances to the next five oxygens lying to the other side are not much longer. These units are linked together to a three-dimensional structure.

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