Eine neue Methode der Kondensationskernzählung

Zusammenfassung In der vorliegenden Arbeit wird eine Methode beschrieben, die es gestattet, mit Hilfe lackierter Glasplatten Kondensationskerntröpfchen oder andere Tröpfchen mit einem Durchmesser von 5 zu fixieren und dann elektronisch auszuzählen. Vorversuche, bei denen diese Methode angewendet wurde, machen es wahrscheinlich, dass bei Kondensationskernzählern, die nach dem Expansionsprinzip arbeiten, ein Teil der Kerne wegen ihrer Aktivität schon vor der Expansion als Wassertröpfchen ausfällt und damit der Zählung entgeht.

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Summary In the present paper a method is described, which allows to fix droplets of condensation nucleus or other droplets (diameter 5 ) by means of varnished plates of glass and count them afterwards electronically. Preliminary experiments with this method show up the probability, that in the nucleus counter, working on the principle of expansion, some of the very active nucleus drops out before the expansion chamber is dilated and thus escapes registration.

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Riassunto Nella presente ricerca si descrive un metodo il quale consente di fissare goccioline provenienti da nuclei di condensazione, o altre goccioline (diam. 5 ), su dischi di vetro verniciati, e in seguito di contarle elettronicamente. Prove eseguite con questo metodo rendono probabile che, in contatori di nuclei di condensazione che lavorano secondo il principio dell'espansione, una parte dei nuclei, in seguito alla loro stessa attività, cada sotto forma di goccioline d'acqua già prima dell'espansione e che quindi sfugga al conteggio.

     

Über die Bestimmung von Differenzen der Lotrichtung mit Hilfe des GradientenU zzs

Zusammenfassung R. v. Eötvös hat für die Bestimmung von Lotrichtungsdifferenzen mit seiner Drehwaage zwei Verfahren angegeben, die aber nur unter Hinzuziehung astronomisch-geodätischer Messungen zum Ziel führen. Beide Verfahren sind sehr umständlich, und in der einschlägigen Literatur finden sich keine Hinweise, daß eines der genannten Verfahren seitEötvös nochmals angewandt wurde. — In Freiburg i. Br. wird zur Zeit eine Drehwaage erprobt, mit der voraussichtlich die direkte Messung des GradientenU_zzs möglich sein wird. Es soll nun gezeigt werden, daß die Bestimmung der Lotrichtungsdifferenz zweier Feldpunkte mit Hilfe dieser Größe, ohne Zuhilfenahme von astronomisch-geodätischen Messungen, möglich ist.

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Summary R. v. Eötvös has showed two methods for the measurement of differences between vertical lines with his torsion-balance. Both methods are only applicable, if they are connected with astronomic and geodetic measurements, and they are very troublesome. In the special publications are no remarks, that one of these methods everytime has been applied since the measurement ofEötvös. —At Freiburg i. Br. (Western Germany) now a new torsion-balance is built, with which foreseeable the direct measurement of the gradientU_zzs will be possible. In the following publication will be demonstrated, that the fixation of differences between the vertical lines of two points of the gravity field of the earth is possible with this gradientU_zzs without astronomic and geodetic measurements.

     

Die atlantischen Ankerstationen des „Armauer Hansen“ im Jahre 1930 in der Bearbeitung von V. W. Ekman

Summary The main subject of Ekman's most careful and detailed analysis of the current measurements of Armauer Hansen is to elucidate the periodical character of ocean currents. A survey of his results is given in table 2 and by means of an outline chartlet a comparison is made between the values which are derived from the observations on board Armauer Hansen and those attained by the reviewer by numerical calculation.

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Les observations faites à bord du navire Armauer Hansen en 1930 à ses mouillages dans l'Atlantique et leur exploitation par V. W. Ekman

Résumé Le but principal de V. W. Ekman dans son analyse scrupuleuse et détaillée des mesures de courant est d'élucider le caractère periodique des courants océaniques. Les résultats les plus importants en sont donnés dans la table 2; en outre le rapporteur compare ces résultats empiriques d'Ekman avec ses propres calculs numériques en les confrontant dans une petite carte.

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V. W. Ekmann, Studies on Ocean Currents. Geofysiske Publikasjoner Vol. XIX, No. 1, Bergen 1953.     

Surveillance for previously unmonitored organic contaminants in the San Francisco Estuary

The San Francisco Estuary Regional Monitoring Program initiated surveillance monitoring to identify previously unmonitored synthetic organic contaminants in the San Francisco Estuary. Organic extracts of water samples were analyzed using gas chromatography-mass spectrometry in full scan mode. The major contaminant classes identified in the samples were fire retardants, pesticides, personal care product ingredients, and plasticizers. Evidence from the literature suggests that some of these contaminants can persist in the environment, induce toxicity, and accumulate in marine biota and in higher food chain consumers. The major sources of these contaminants into the marine environment are the discharge of municipal and industrial wastewater effluents, urban stormwater, and agricultural runoff. As a proactive effort, it is suggested that surveillance studies be used routinely in monitoring programs to identify and prevent potential problem contaminants from harming the marine environment.     

Nachweis der allgemeinen Gültigkeit des Gefrierkernspektrums

Zusammenfassung Durch weitere experimentelle Untersuchungen wird festgestellt, dass das an destillierten Wassertropfen ermittelte Gefrierkernspektrum von speziellen Versuchsbedingungen unabhängig ist und auch für Wasserarten mit verschiedenen natürlichen oder künstlichen Verunreinigungen gilt. Es kann ausserdem in allen bisher im Laboratorium und in der Atmosphäre durchgeführten Untersuchungen über die Eiskeimbildung nachgewiesen werden. Dieser Befund stützt als notwendige Bedingung die Deutung des Gefrierkernspektrums durch Strukturänderungen des Wassers und besagt, dass im Laboratorium und in der Atmosphäre dieselben Gefrierkerne vorhanden sind und dass bei der atmosphärischen Eiskeimbildung auch nur die aus Untersuchungen im Laboratorium bekannten Besonderheiten des Gefrieveorgangs (im unterkühlten Wasser) vorliegen.

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Summary Further experimental investigations demonstrate the «Gefrierkernspektrum», which was found for droplets from destilled water, to be independent from special experimental conditions and valid for sorts of water containing natural or artificial impurities, too. Furthermore it can be pointed out from all existing investigations on ice-nucleation, made in laboratory and in the atmosphere. This result supports, as a necessary condition, the interpretation of the «Gefrierkernspektrum» by means of changes in the structure of water itself and proves, that there are the same freezing nuclei both in the laboratory and the fre atmosphere and that ice-nucleation in the atmosphere holds but the same peculiarities of freezing (of supercooled water), known from laboratory work.

     

Development of site-specific design ground motions in Western and Eastern North America

This paper presents results recently obtained for generating site-specific ground motions needed for design of critical facilities. The general approach followed in developing these ground motions using either deterministic or probabilistic criteria is specification of motions for rock outcrop or very firm soil conditions followed by adjustments for site-specific conditions. Central issues in this process include development of appropriate attenuation relations and their uncertainties, differences in expected motions between Western and Eastern North America, and incorporation of site-specific adjustments that maintain the same hazard level as the control motions, while incorporating uncertainties in local dynamic material properties. For tectonically active regions, such as the Western United States (WUS), sufficient strong motion data exist to constrain empirical attenuation relations for M up to about 7 and for distances greater than about 10–15 km. Motions for larger magnitudes and closer distances are largely driven by extrapolations of empirical relations and uncertainties need to be substantially increased for these cases.

For the Eastern United States (CEUS), due to the paucity of strong motion data for cratonic regions worldwide, estimation of strong ground motions for engineering design is based entirely on calibrated models. The models are usually calibrated and validated in the WUS where sufficient strong motion data are available and then recalibrated for applications to the CEUS. Recalibration generally entails revising parameters based on available CEUS ground motion data as well as indirect inferences through intensity observations. Known differences in model parameters such as crustal structure between WUS and CEUS are generally accommodated as well. These procedures are examined and discussed.