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121.
A review of the biology and genetics of sea lice   总被引:5,自引:0,他引:5  
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122.
Zusammenfassung In Locarno-Monti am Alpensüdfu? wurde w?hrend zwei Jahren die kurzwellige Strahlung von Sonne + Himmel (Globalstrahlung) auf eine horizontale, je eine um 30° bzw. 60° nach Süden und je eine um 30° nach Osten bzw. Westen geneigte Auffangfl?che mit Solarimetern registriert. Die Tages- und Jahresg?nge der Globalstrahlung zeigen an wolkenlosen Tagen gro?e Unterschiede im Strahlungsgenu? der verschieden orientierten und verschieden geneigten Fl?chen. Im Mittel aller Tage sind diese Unterschiede zwar kleiner, jedoch wegen der gro?en relativen Sonnenscheindauer in Locarno-Monti immer noch sehr ausgepr?gt. Bei vollkommen bedecktem Himmel verschwinden die Unterschiede fast v?llig. Aufgrund der Beziehungen zwischen der Globalstrahlung und der relativen Sonnenscheindauer genügen Parallelmessungen von wenigen Jahren, um daraus klimatologische Mittelwerte der Globalstrahlung auf verschieden orientierte und geneigte Fl?chen berechnen zu k?nnen. Das Verh?ltnis der Strahlung auf geneigte H?nge zu der auf die horizontale Fl?che h?ngt von der Jahreszeit und der Bew?lkung ab. Diese Beziehung kann dazu dienen, bei Kenntnis der Globalstrahlung auf eine horizontale Fl?che jene auf eine geneigte Auffangfl?che zu bestimmen. Schlie?lich wird auf die Bedeutung dieser Untersuchungen für die praktische Meteorologie hingewiesen.
Summary For a two years' period the total (short wave) radiation of sun and sky falling on a horizontal surface, on southern slopes of 30° and 60° inclination, resp., and on eastern and western slopes of 30° inclination has been recorded with solarimeters at Locarno-Monti (Switzerland). On cloudless days the diurnal and annual variations of the total radiation indicate rather big differences between the radiation falling on the surfaces of different inclination and orientation. Considering the radiation covering all days, these differences are smaller but still distinctly marked because of the high relative duration of sunshine at Locarno-Monti. On overcast days all surfaces receive almost the same amount of radiation. Climatological averages of the total radiation falling on surfaces of different orientation and inclination can be deduced using the relation between the total radiation and the duration of sunshine. The ratio between the radiation falling on inclined planes and the radiation falling on a horizontal surface depends on season and cloudiness. By means of these relations the radiation falling on inclined surfaces can be calculated using the radiation falling on the horizontal surface. Finally the importance of such investigations for applied meteorology is pointed out.

Résumé Le rayonnement de courte longueur d'onde du soleil et du ciel (rayonnement global) a été enregistré pendant deux ans à Locarno-Monti, au pied sud des Alpes, au moyen de solarimètres présentant différentes orientations. Les surfaces réceptrices étaient respectivement horizontale, inclinées de 30° et 60° vers le sud, ainsi que de 30° vers l'est et l'ouest. Les variations journalières et saisonnières du rayonnement global mettent en évidence les grandes différences d'éclairement des surfaces réceptrices selon leur azimut et leur inclinaison, lors des journées ensoleillées surtout. Ces différences sont plus faibles lorsque l'on prend tous les jours en considération, mais restent cependant bien marquées par suite de la grande durée relative d'insolation à Locarno-Monti; elles disparaissent presque complètement par ciel entièrement couvert. En s'appuyant sur les relations entre le rayonnement global et la durée relative d'insolation, l'on peut calculer des moyennes climatologiques du rayonnement global tombant sur des surfaces d'orientation différente à l'aide de quelques années seulement d'enregistrements parallèles. Le quotient des rayonnements re?us par une pente inclinée et par une surface horizontale dépend de la saison et de la couverture nuageuse. Une fois cette relation connue, il est possible d'évaluer le rayonnement global re?u par une surface inclinée à partir des valeurs relatives à une surface horizontale. Enfin, l'on signale l'importance de ces recherches pour la météorologie appliquée.

Riassunto A Locarno-Monti al piede meridionale delle Alpi durante due anni fu registrata con solarimetri la radiazione ad onde corte del sole + cielo (radiazione globale) su superfici orizzontale, inclinate di 30° e rispettivamete 60° e rivolte verso sud, nonchè su superfici orizzontale, inclinate di 30° e rivolte verso est, rispettivamente verso ovest. Gli andamenti giornaliero ed annuale della radiazione globale mostrano nei giorni senza nuvole grandi differenze nella quantità di radiazione ricevuta dalle superfici diversamente inclinate e orientate. Nella media di tutti i giorni tali differenze sono si più piccole, tuttavia sempre ancora ben pronunciate causa l'elevata durata relativa dell'insolazione. Con cielo completamente coperto le differenze scompaiono quasi completamente. In base alle relazioni tra la radiazione globale e la durata relativa dell'insolazione, sono sufficienti misure parallele di soli pochi anni per poter calcolare valori climatologici della radiazione globale su diverse superfici orientate e inclinate. Il rapporto tra la radiazione su pendii inclinati e quella su superfici orizzontale dipende dalla stagione e dalla nuvolosità. Questa relazione può servire, conoscendo la radiazione globale su una superficie orizzontale, a determinare quella su una superficie di ricezione inclinata. Da ultimo viene accennato all'importanza di queste ricerche per la meteorologia pratica.


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This study presents the age control and environmental magnetism components of a new, late Pleistocene paleoclimate record for the Great Basin of western North America. Two new cores from the Summer Lake sub-basin of pluvial Lake Chewaucan, Oregon, USA are correlated to basin margin outcrops on the basis of tephrochronology, lithostratigraphy, sediment magnetism and paleomagnetic secular variation. Eleven tephra layers were found in the cores that correlate to tephra identified previously in the outcrop. The Olema ash was also found in one of the cores; its stratigraphic position, relative to 3 dated tephra layers, indicates that its age is 50-55 ka, somewhat younger than has been previously reported. The Summer Lake sediments are divided into deep and shallow lake lithosomes based on sedimentary features. The stratigraphic position of these lithosomes support the tephra-based correlations between the outcrop and the cores. These sediments contain a well resolved record of the Mono Lake Excursion (MLE) and an earlier paleomagnetic excursion as well as a high quality replication of the paleosecular variation immediately above the MLE.Relative sedimentation rates increased dramatically toward the depocenter during intervals of low-lake level. In contrast, during intervals of high-lake level, relative sedimentation rates were comparable along the basin axis from the basin margin to the depocenter. The magnetic mineralogy of the Summer Lake sediments is dominated by pseudo-single domain (titano)magnetite and intervals of high/low magnetite concentration coincide with lithosomes that indicate high/low lake levels. Magnetic grain size also varies in accord with bulk sediment grain size as indicated by the silt/clay ratio. To a first order, variations in magnetic parameters, especially those attributable to the concentration of magnetic minerals, correlate well with global glacial/interglacial oscillations as indicated by marine oxygen isotope stages. This relationship can be explained by increased dissolution of (titano)magnetite minerals as lake level dropped and the lake became more productive biologically. This inference is supported by a correspondence between lower concentrations of magnetite with higher levels of total organic carbon and vice-versa.  相似文献   
127.
The Earthquake Model of Middle East (EMME) Project aimed to develop regional scale seismic hazard and risk models uniformly throughout a region extending from the Eastern Mediterranean in the west to the Himalayas in the east and from the Gulf of Oman in the south to the Greater Caucasus in the North; a region which has been continuously devastated by large earthquakes throughout the history. The 2014 Seismic Hazard Model of Middle East (EMME-SHM14) was developed with the contribution of several institutions from ten countries. The present paper summarizes the efforts towards building a homogeneous seismic hazard model of the region and highlights some of the main results of this model. An important aim of the project was to transparently communicate the data and methods used and to obtain reproducible results. By doing so, the use of the model and results will be accessible by a wide community, further support the mitigation of seismic risks in the region and facilitate future improvements to the seismic hazard model. To this end all data, results and methods used are made available through the web-portal of the European Facilities for Earthquake Hazard and Risk (www.efehr.org).  相似文献   
128.
Geomorphological characteristics of tidal basins control hydrodynamics and sediment transport potential within such basins, for example, by adjusting the balance in tidal asymmetry. In this study we examine the effects of entrance geometry on tidal velocity asymmetry, slack water asymmetry, bed shear stress patterns and hypsometric profile shapes by comparison of six shallow meso-tidal basins of Tauranga Harbour, New Zealand. Numerical model results show how tidal distortion increases with distance from a basin entrance. A simple ratio between basin width and entrance width defines levels of basin dilation. Sub-basins with a constricted geometry and deep entrance channels are associated with small bed shear stress values and high rates of flood-directed tidal velocity asymmetry in the sheltered basin centres, indicating a large potential for sediment deposition of larger particles. Moreover, slack water asymmetry within these basins is weakly ebb-directed, indicating a small potential for transport of fine sediments out of the basins. The constricted depositional basins are characterized by convex hypsometric profiles with elevated intertidal regions. Unconstricted geometries are associated with larger bed shear stress values and more ebb-directed tidal velocity asymmetry within basin centres, suggesting limited potential for overall sediment deposition. The slack tide duration asymmetry is weakly flood-dominant indicating that limited input of fine sediment into the basins is possible. The comparatively high-energy conditions within these exposed basins are associated with a less convex hypsometric intertidal profile. The ability to estimate tidal asymmetries is advantageous when developing management strategies related to ecosystem functioning, navigability or coastal protection in specific geomorphic settings. © 2019 John Wiley & Sons, Ltd.  相似文献   
129.
The 3.6 Ma El'gygytgyn impact structure, located in northeast Chukotka in Arctic Russia, was largely formed in acidic volcanic rocks. The 18 km diameter circular depression is today filled with Lake El'gygytgyn (diameter of 12 km) that contains a continuous record of lacustrine sediments of the Arctic from the past 3.6 Myr. In 2009, El'gygytgyn became the focus of the International Continental Scientific Drilling Program (ICDP) in which a total of 642.4 m of drill core was recovered. Lithostratigraphically, the drill cores comprise lacustrine sediment sequences, impact breccias, and deformed target rocks. The impactite core was recovered from 316.08 to 517.30 meters below lake floor (mblf). Because of the rare, outstanding recovery, the transition zone, ranging from 311.47 to 317.38 m, between the postimpact lacustrine sediments and the impactite sequences, was studied petrographically and geochemically. The transition layer comprises a mixture of about 6 m of loose sedimentary and volcanic material containing isolated clasts of minerals and melt. Shock metamorphic effects, such as planar fractures (PFs) and planar deformation features (PDFs), were observed in a few quartz grains. The discoveries of silica diaplectic glass hosting coesite, kinked micas and amphibole, lechatelierite, numerous impact melt shards and clasts, and spherules are associated with the impact event. The occurrence of spherules, impact melt clasts, silica diaplectic glass, and lechatelierite, about 1 m below the onset of the transition, marks the beginning of the more coherent impact ejecta layer. The results of siderophile interelement ratios of the transition layer spherules give indications of the relative contribution of the meteoritical component.  相似文献   
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Pollen and organic-walled dinoflagellate cyst assemblages from core GeoB 9503-5 retrieved from the mud-belt ( 50 m water depth) off the Senegal River mouth have been analyzed to reconstruct short-term palaeoceanographic and palaeoenvironmental changes in subtropical NW Africa during the time interval from ca. 4200 to 1200 cal yr BP. Our study emphasizes significant coeval changes in continental and oceanic environments in and off Senegal and shows that initial dry conditions were followed by a strong and rapid increase in humidity between ca. 2900 and 2500 cal yr BP. After ca. 2500 cal yr BP, the environment slowly became drier again as indicated by slight increases in Sahelian savannah and desert elements in the pollen record. Around ca. 2200 cal yr BP, this relatively dry period ended with periodic pulses of high terrigenous contributions and strong fluctuations in fern spore and river plume dinoflagellate cyst percentages as well as in the fluxes of pollen, dinoflagellate cysts, fresh-water algae and plant cuticles, suggesting “episodic flash flood” events of the Senegal River. The driest phase developed after about 2100 cal yr BP.  相似文献   
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