Geographies of governance in the European Union: an introduction     

Herman van der Wusten  Virginie Mamadouh 《GeoJournal》2008,72(1-2):1-5

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A New World Order (No Less)     

Herman van der Wusten 《The Professional geographer》1992,44(1):19-22

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The Reproduction of the Anemone Sagartia troglodytes (PRICE): No Influence of Tidal Manipulation     

Herman  Hummel Roelof H.  Bogaards 《Marine Ecology》1991,12(1):35-40

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Monitoring meiobenthos using cm-, m- and km-scales in the Southern Bight of the North Sea     

Jian Li  Magda Vincx  Peter M.J. Herman  Carlo Heip 《Marine environmental research》1997,43(4):265-278

Meiobenthos at the mouth of the Grevelingen and Oosterschelde Estuaries in the Southern Bight of the North Sea was monitored using meiobenthic abundance and nematode community structure. Hierarchical sampling included 54 subsamples nested within 18 cores within six stations within two transects. The spatial patterns of the meiofaunal populations and communities are presented in cm-scale (among subsamples), m-scale (among cores), km-scale (among stations) and 10 km-scale (between transects). The variance components analysis of meiofaunal abundances showed that km-scale and 10 km-scale represented 63–90% of total variance while m-scale and cm-scale provided only 10–37%. Different communities were found among stations rather than among cores or subsamples by detrended correspondence analysis ordination and clustering analysis. The main assemblage of meiofauna occurred at the km-scale. Nematode diversity was more powerful than meiofaunal abundance in detecting spatial variation at all scales. However, at least two replicates are required for monitoring when sampling using a 10 cm² subsampling core.  相似文献   

Mass movement of fine-grained sediment to the basin floor,bering sea,Alaska     

Paul R. Carlson  Herman A. Karl 《Geo-Marine Letters》1984,4(3-4):221-225

Large volumes of fine-grained sediment have been transported to the deepbasin floor in the Bering Sea, especially during glacial low stands of sea level. Turbidity currents and several types of mass movement have been the chief transporting agents.  相似文献   

The clinopyroxene/plagioclase symplectite in retrograde eclogites: A potential geothermobarometer   总被引：3，自引：0，他引：3  

Veronique Joanny  Herman van Roermund  Jean Marc Lardeaux 《International Journal of Earth Sciences》1991,80(2):303-320

The retrograde P-T-t path of intermediate and high-temperature eclogites (T 500 ± 50°C) is characterized by the transformation of omphacite into a symplectitic intergrowth of clinopyroxene and plagioclase lamellae. Often, this symplectite shows a two stage microstructural evolution, i.e. a coarse lamellar width symplectite, »S1«, followed by a thinner lamellar width symplectite, »S2«. Each symplectite may also evolve independently into a final globular microstructure, »SG«.According to metallurgical concepts, the phase transition »omphacite clinopyroxene + plagioclase« is classified as a discontinuous precipitation reaction. In discontinuous precipitation reactions, the lamellar spacing (L) depends on temperature (T) according to the growth law log (L) = A-B/T, in which A and B are constants. Therefore thin symplectites characterize low temperatures, where-as coarse symplectites characterize higher temperatures.In order of specify the thermal evolution of continental collision zones, the reliability of the discontinuous precipitation growth law has been tested on eclogites showing contrasted retrograde P-T-t histories in different geological environments, i.e. Alpine, Caledonian and Variscan Belts. Indeed, our investigations reveal that the clinopyroxene/plagioclase symplectite can be used as a potential geothermobarometer in eclogites recording temperatures above 500 ± 50°C. The temperature is obtained by the lamellar spacing and pressure by the Jadeite content of the symplectite clinopyroxene in the presence of plagioclase and quartz.

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Zusammenfassung Der retrograde P-T-t Pfad von intermediären und hochtemperierten Eklogiten (T 500 ±50°C) ist charakterisiert durch die Umformung von Omphazit in symplektitische Verwachsungen von Klinopyroxen und Plagioklas-Lamellen. Häufig zeigt dieser Symplektit eine zweiphasige mikrostrukturelle Entwicklung, das heißt, ein Symplektit mit breiten Lamellen »S1« wird gefolgt von einem Symplektit mit dünneren Lamellen »2«. Jeder Symplektittyp kann sich schließlich selbständig zu einer kugelförmigen MikroStruktur »SG« entwikkeln.Auf Grund von metallurgischen Vorstellungen wir die Phasenumwandlung Omphazit zu Klinopyroxen + Plagioklas als diskontinuierliche Ausfällungsreaktion klassifiziert. In diskontinuierlichen Ausfällungsreaktionen hängt der Lamellenabstand (L) von der Temperatur (T) nach dem Wachstumsgesetz log (L) = A-B/T ab, in dem A und B Konstanten sind. Daher zeigen dünne Symplektite niedrige Temperaturen an, während breite Symplektite höhere Temperaturen anzeigen.Um die thermische Entwicklung von kontinentalen Kollisionszonen zu spezifizieren mußte die Zuververlässigkeit des diskontinuierlichen Ausfällungswachstumsgesetz an Eklogiten getestet werden, die unterschiedlich retrograde P-T-t Geschichten aus verschieden Umgebungen zeigen; das heißt aus alpinen, kaledonischen und variszischen Gebirgszügen. Tatsächlich offenbaren unsere Bemühungen, daß der Klinopyroxen/Plagioklas Symplektit als potentielles Geothermobarometer in Eklogiten benutzt werden kann, die Temperaturen über 500°C ± 50°C erfahren haben. Die Temperatur kann man aus dem Lamellenabstand erhalten; den Druck durch den Jadeitgehalt des symplektitischen Pyroxens, in Anwesenheit von Plagioklas und Quarz.

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Résumé La déstabilisation de l'omphacite, en une symplectite à alternance de lamelles de clinopyroxène et de plagioclase, caractérise l'initiation du trajet rétrograde P-T-t pour les éclogites de température 500 ± 50°C. Cette symplectite présente parfois une évolution microstructurale depuis une symplectite grossière à alternance de lamelles larges, »S1«, relayée par une symplectite à alternance de lamelles fines, »S2«. Chaque symplectite peut aussi évoluer indépendemment en une microstructure globulaire tardive, »Sg«.En accord avec les concepts établis par les métallurgistes, la transformation »omphacite clinopyroxène + plagioclase« est une précipitation discontinue. Pour ce type de transformation, l'espace interlamellaire (L) dépend de la température (T) selon la loi de croissance Log (L) =A-B/T (*), où A et B sont des constantes. Ainsi, une symplectite fine (de type S2) caractérise des températures relativement plus basses qu'une symplectite grossière (de type S1).Afin de préciser l'évolution thermique des zones de collision continentale, nous avons testé la loi de croissance (*) sur des éclogites échantillonnées dans divers contextes géologiques (chaînes alpine, calédonide et varisque), présentant des trajets rétrogrades P-T-t contrastés. Les résultats montrent que la symplectite à clinopyroxène/plagioclase représente un géothermobaromètre potentiel de la rétromorphose des éclogites: la taille de l'espace interlamellaire dépend de la température et la teneur en jadéite des lamelles de clinopyroxène, en présence de quartz et à l'équilibre avec le plagioclase, dépend de la pression.

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. , .. , «S 1», «S 2». «SG». , . (L) () — — log (L) = - /, . , . , , , .: , . , , / , , 500° + 50°. , — , .

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Light scattering in cometary dust comae     

Gary Herman  Heikki Salo 《Earth, Moon, and Planets》1987,39(1):51-74

Detailed single and multiple scattering calculations were carried out for a spherically symmetric cometary atmosphere irradiated by a plane parallel source. Using simplifying assumptions in the single scattering approximation, analytical expressions were derived for the total flux impinging the cometary nucleus, which was shown to be a decreasing function of the coma opacity. Moreover, while highly anisotropic phase functions resulted in more light reaching the nucleus than was the case for isotropic phase functions, the net energy flux at the nucleus surface was still found to be smaller in the presence of a coma than in the no coma case. This increased flux due to the anisotropic phase functions was attributed mostly to the effect of directional scattering in the forward Sun-comet axis. The isotropic multiply scattered flux at the surface was found tobe an increasing function of the opacity, , for 2.5. At larger values of , the maximum in the downward directed scattered flux was still seen to increase, but occurred at a height of several radii above the nucleus, resulting in a reduction at the surface. On the other hand, the total flux at the surface was again shown to be a decreasing function of and always less than in the no coma case. Finally, on comparing the multiply scattered flux with that obtained in the plane parallel approximation, it was quite apparent that except in the vicinity of the Sun-comet axis, the plane parallel geometry tends to underestimate the degree of scattering.NRC Resident Research Associate.  相似文献   

Climate-induced boreal forest change: Predictions versus current observations   总被引：4，自引：0，他引：4  

Amber J. Soja  Nadezda M. Tchebakova  Nancy H.F. French  Michael D. Flannigan  Herman H. Shugart  Brian J. Stocks  Anatoly I. Sukhinin  E.I. Parfenova  F. Stuart Chapin III  Paul W. Stackhouse  Jr. 《Global and Planetary Change》2007,56(3-4):274

For about three decades, there have been many predictions of the potential ecological response in boreal regions to the currently warmer conditions. In essence, a widespread, naturally occurring experiment has been conducted over time. In this paper, we describe previously modeled predictions of ecological change in boreal Alaska, Canada and Russia, and then we investigate potential evidence of current climate-induced change. For instance, ecological models have suggested that warming will induce the northern and upslope migration of the treeline and an alteration in the current mosaic structure of boreal forests. We present evidence of the migration of keystone ecosystems in the upland and lowland treeline of mountainous regions across southern Siberia. Ecological models have also predicted a moisture-stress-related dieback in white spruce trees in Alaska, and current investigations show that as temperatures increase, white spruce tree growth is declining. Additionally, it was suggested that increases in infestation and wildfire disturbance would be catalysts that precipitate the alteration of the current mosaic forest composition. In Siberia, 7 of the last 9 yr have resulted in extreme fire seasons, and extreme fire years have also been more frequent in both Alaska and Canada. In addition, Alaska has experienced extreme and geographically expansive multi-year outbreaks of the spruce beetle, which had been previously limited by the cold, moist environment. We suggest that there is substantial evidence throughout the circumboreal region to conclude that the biosphere within the boreal terrestrial environment has already responded to the transient effects of climate change. Additionally, temperature increases and warming-induced change are progressing faster than had been predicted in some regions, suggesting a potential non-linear rapid response to changes in climate, as opposed to the predicted slow linear response to climate change.  相似文献   

The Dutch confrontation with the growing gap between politics and policies     

Herman van der Wusten 《GeoJournal》2008,72(1-2):121-125

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Geomorfología | Geomorfología,Mateo Gutiérrez Elorza,Pearson Educación. S.A., Prentice Hall,Madrid (2008), 920 pp. (RRP €94.99). ISBN: 978-84-8322-398-5/551.4     

Herman Th. Verstappen 《Quaternary Science Reviews》2009,28(27-28):3459-3460

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