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101.
Gary L Rowe Jr Shinji Ohsawa Bokuichiro Takano Susan L Brantley Jose F Fernandez Jorge Barquero 《Bulletin of Volcanology》1992,54(6):494-503
Monitoring of crater lake chemistry during the recent decline and disappearance of the crater lake of Poás Volcano revealed that large variations in SO4/Cl, F/Cl, and Mg/Cl ratios were caused by the enhanced release of HCl vapor from the lake surface due to increasing lake temperature and solution acidity. Variation in the concentration of polythionic acids (H2SxO6, x=4–6) was the most reliable predictor of renewed phreatic eruptive activity at the volcano, exhibiting sharp decreases three months prior to the initiation of phreatic eruptions in June 1987. Polythionic acids may offer a direct indicator of changing subsurface magmatic activity whereas chloride-based element ratios may be influenced by surface volatilization of HCl and subsequent recycling of acidic fluids in crater lake volcanoes. 相似文献
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Mark Leipnik Xinyue Ye Jose Serna James Strong Christopher Wilkins Ling Wu 《Geographical review》2016,106(2):312-330
Restrictions in the USA on registered sex offenders (RSOs) are examined from the spatial aspects. The long history of various restrictions imposed by government, particularly local ones, is covered in the introduction. Spatial aspects, such as delineation of zones from which certain activities or certain people are excluded is the focus. Then the nature of restrictions on RSOs is considered at the state, county and municipal level. Typical of restrictions are that RSOs are prohibited from moving into residence within a prescribed distance of certain features in a community. The distances are typically 1,000 feet but are quite variable. Typical proscribed venues are schools, parks and day care centers, but there can be many others such as bus stops. Spatial aspects of these restrictions, such as how offender locations are geocoded and represented and how proscribed venues are delineated is analyzed. Specific details and theoretical concerns related to the many problematic issues with RSO restrictions is presented. In particular questions of their constitutionality and efficacy are raised. The paper concludes with a discussion of the implications of RSO restrictions for the discipline of geography in general and for the evolution of increasingly precise methods of spatial analysis in particular. 相似文献
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Summary By analogy with the calculation from data of angular momentum flow across latitude surfaces in the earth's atmosphere, the corresponding calculation is proposed for the case of our galaxy and possibly other spiral nebulae. A cylindrical wall of constant radius is used to replace the latitude wall, and the subject is developed through consideration of an ideal model. Gravitational torques enter the problem in addition to advective effects and possible other torques in actual systems. The relation of gravitational torques to the structure of ordinary spirals is discussed, and certain more special effects for the case of barred spirals are introduced and discussed. The connection of the subject with the classical theory of tidal evolution is pointed out.
Zusammenfassung Analog mit der Berechnung von Daten des Flusses des Momentes der Bewegungsgrösse über Breiten-Oberflächen in der Erd-Atmosphäre wird eine korrespondierende Berechnung für den Fall unseres Sternsystems und eventuell anderer spiraler Himmelskörper vorgeschlagen. Eine zylindrische Wand mit konstantem Radius wird benutzt, um die Breitenwand zu ersetzen, und dieses Problem wird entwickelt durch die Betrachtung eines idealen Modelles. Drehmomente der Schwerkraft kommen bei diesen Problem hinzu, zusätzlich der Wirkungen von Advektion und in aller Wahrscheinlichkeit anderer Drehmomente in den vorhandenen Systemen. Die Beziehung der Drehmomente der Schwerkraft in Bezug auf gewöhnliche Spiralen ist besprochen, und gewisse mehr spezialisierte Wirkungen für den Fall von Stangen-Spiralen werden eingeführt und besprochen. Der Zusammenhang dieses Problems mit der klassischen Theorie von Drehmomenten der Gezeiten ist nachgewiesen.
Sommario In analogia ai calcoli che, partendo da dati sperimentali, vengono fatti sul trasferimento del momento angolare fra zone dell'atmosfera a diverse latitudini, vengono qui proposti corrispondenti calcoli per la nostra galassia e possibilmente per altre nebulose a spirale. Viene usata una superficie cilindrica a raggio costante in sostituzione della superficie conica a latitudine costante; l'argomento è sviluppato secondo un modello ideale. La coppia gravitazionale viene presa in considerazione insieme agli effetti convettivi e ad altre possibili coppie. Viene discussa la relazione fra la coppia gravitazionale e la struttura di una spirale ordinaria; sono quindi introdotti e discussi certi effetti nel caso di spirali a sbarra. Infine viene messo in luce la relazione del presente argomento con la teoria classica della coppia dovuta alle marce.相似文献
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The molluscan macrofauna living in shallow muddy bottoms with the green algae Caulerpa prolifera was studied monthly between February 1994 and January 1996 in the inner Bay of Cádiz (SW Spain). The molluscan assemblage followed a similar pattern over the 2 years, displaying seasonal trends in species richness, abundance and structure. During the autumn and winter months, a decrease in abundance, species richness and diversity and an increase in evenness occurred. During the spring and summer months, the molluscan assemblage was characterised by an increase in species richness, abundance and diversity. These seasonal trends were supported statistically by the presence of significantly different groupings of seasonal samples in multivariate analyses.Despite human impacts in the bay (e.g. aquaculture activities, sewage), the presence of repetitive seasonal trends, based on the qualitative and quantitative data, indicates the stability of the molluscan assemblage over 2 years. Benthic characteristics from the inner Bay of Cádiz, such as shallow soft bottoms with the presence of macrophytes and current dynamics, seem to be key factors influencing the composition and seasonality of this molluscan assemblage. 相似文献