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81.
The analysis of light and dark spots in the equatorial regions of Jupiter by Browne and Meadows (1978) is shown to have major inconsistencies in the interpretation of the colours of these features. In order to prevent similar errors with subsequent analyses of multispectral Jovian images, it is essential to use the data in digital form and analyse it using an interactive computing facility. 相似文献
82.
We investigated the occurrence of behaviors that maximize predator avoidance and seaward transport in estuarine decapod zoeae
by collecting larvae from discrete depths in a partially mixed estuary, Willapa Bay, Washington, USA, and relating their abundance
and vertical distribution to a suite of environmental variables. Abundances of first zoeae of Neotrypaea californiensis and Pinnotheridae were associated with tidal phase, diel phase, and water height. Both taxa were most abundant during ebb
tides, and abundances increased with water height, suggesting behaviors that enhanced seaward transport. Additionally, N. californiensis were both shallower and more abundant at night, indicative of behaviors to avoid visual predators. Our results suggest that
both tidal transport and predator avoidance are important and sometimes interactive selective forces shaping larval decapod
behavior. 相似文献
83.
Much of the existing knowledge about breaking waves comes from physical model experiments scaled using Froude's law. A widely held assumption is that surface tension effects are not significant at typical laboratory scales and specifically for waves longer than 2 m. Since, however, smaller wavelengths are not untypical in small to medium scale laboratory facilities, a consideration of surface tension effects is indeed important. Although some emphasis has been given in the past, little is known regarding the importance of surface tension following impingement of the breaking-wave crest and especially on the overall energy dissipation by laboratory breaking waves. 相似文献
84.
Jacco Th. van Loon Sneana Stanimirovi A. Evans Erik Muller 《Monthly notices of the Royal Astronomical Society》2006,365(4):1277-1282
We present the results of a survey, the deepest to date, for H i emission at 21 cm and OH emission at 18 cm (lines at 1612, 1665, 1667 and 1720 MHz) in the direction towards the Galactic globular clusters M15, M2, NGC 6934, NGC 7006 and Pal 13. The aim is to measure the amount of hydrogen in the intracluster medium, and to find OH masers in the circumstellar envelopes of globular cluster red giants. We present a tentative detection of 0.3 M⊙ of neutral hydrogen in M15 and possible detections of neutral hydrogen in M2 and Pal 13. We derive upper limits to the neutral hydrogen content of NGC 6934 and 7006. No OH emission is detected. We also present deep H i data of the northern tip of the Magellanic Stream behind Pal 13. 相似文献
85.
A subaltern critical geopolitics of the war on terror: Postcolonial security in Tanzania 总被引:1,自引:0,他引:1
Joanne Sharp 《Geoforum》2011,42(3):297-305
Currently, hegemonic geographical imaginations are dominated by the affective geopolitics of the War on Terror, and related security practice is universalised into what has been called “globalized fear” (Pain, 2009). Critical approaches to geopolitics have been attentive to the Westerncentric nature of this imaginary, however, studies of non-Western perceptions of current geopolitics and the nature of fear will help to further displace dominant geopolitical imaginations. Africa, for example, is a continent that is often captured in Western geopolitics - as a site of failed states, the coming anarchy, passive recipient of aid, and so on - but geopolitical representations originating in Africa rarely make much of an impact on political theory.This paper aims to add to critical work on the so-called War on Terror from a perspective emerging from the margins of the dominant geopolitical imagination. It considers the geopolitical imagination of the War on Terror from a non-Western source, newspapers in Tanzania. 相似文献
86.
Niels Hovius Albert Galy Robert G. Hilton Robert Sparkes Joanne Smith Kao Shuh-Ji Chen Hongey Lin In-Tian A. Joshua West 《Applied Geochemistry》2011
Rapidly eroding, coastal mountain belts, where steep rivers and submarine channels connect upland sources to nearby marine sinks are hotspots of organic carbon transfer from life biomass, soil and exhumed bedrock into geological storage. Using observations from the Southern Alps of New Zealand, and Taiwan, we have mapped this organic pathway to geological carbon sequestration, and can evaluate the magnitude and efficiency of transfers between sources and sinks. We demonstrate that POC is harvested by landsliding, but importantly also by common and widespread surface runoff on steep hillslopes. Although terrestrially sourced POC is found in many sedimentary environments associated with mountain belts and frontier basins, it appears to be most abundantly trapped and preserved in marine turbidites. The loss of all forms of POC in onward transport through short, steep routing systems to this repository is limited. This is in marked contrast to larger routing systems, in which only the most resilient forms of POC survive into long-term deposition. 相似文献
87.
AbstractHyLogger profile scanning is commonly utilised for drill-core logging but the limited scanning area may not detect all important geological features. The study presented in this paper aims to develop a mineral mapping solution for this core-logging process by leveraging the colour image captured during the scanning process. A machine-learning-based computer vision program was developed by implementing a k-means clustering and a global colour profiling algorithm. A suite of drill-core images was used to validate the developed program. Results indicate that there is a direct correlation between the mineral assemblage of a rock type and its colour specifications. The identified mineral type and relative abundance were comparable with HyLogger scan results. 相似文献
88.
89.
Scales and structure of frontal adjustment and freshwater export in a region of freshwater influence
Sea surface temperature satellite imagery and a regional hydrodynamic model are used to investigate the variability and structure
of the Liverpool Bay thermohaline front. A statistically based water mass classification technique is used to locate the front
in both data sets. The front moves between 5 and 35 km in response to spring–neap changes in tidal mixing, an adjustment that
is much greater than at other shelf-sea fronts. Superimposed on top of this fortnightly cycle are semi-diurnal movements of
5–10 km driven by flood and ebb tidal currents. Seasonal variability in the freshwater discharge and the density difference
between buoyant inflow and more saline Irish Sea water give rise to two different dynamical regimes. During winter, when cold
inflow reduces the buoyancy of the plume, a bottom-advected front develops. Over the summer, when warm river water provides
additional buoyancy, a surface-advected plume detaches from the bottom and propagates much larger distances across the bay.
Decoupled from near-bed processes, the position of the surface front is more variable. Fortnightly stratification and re-mixing
over large areas of Liverpool Bay is a potentially important mechanism by which freshwater, and its nutrient and pollutant
loads, are exported from the coastal plume system. Based on length scales estimated from model and satellite data, the erosion
of post-neap stratification is estimated to be responsible for exporting approximately 19% of the fresh estuarine discharge
annually entering the system. Although the baroclinic residual circulation makes a more significant contribution to freshwater
fluxes, the episodic nature of the spring–neap cycle may have important implications for biogeochemical cycles within the
bay. 相似文献
90.
Jonathan P. A. Gardner Martin J. Curwen Joanne Long Robert J. Williamson Ann R. Wood 《新西兰海洋与淡水研究杂志》2013,47(1):179-194
The Kermadec Islands Marine Reserve (KIMR), which is located at 30°S, is New Zealand's largest marine reserve at 748 000 ha, and its biota is composed of a mix of warm temperate, subtropical, and tropical species. A depth‐stratified ecological survey was conducted of the abundance and percentage cover of macrobenthic species and of the water column at two sites (Meyer Island and West Chanter Island), 2km apart. Significant differences in benthic community structure and in water column turbidity and chlorophyll concentrations were observed between the two sites despite their proximity and physical similarity. Compared with other “snapshot” surveys of benthic community structure at sites within the KIMR there was a high degree of similarity among the species observed, but often a low degree of similarity in species abundance or percentage cover as a function of depth. We suggest that despite its isolation and the degree of difficulty of working at this location, a full‐scale ecological survey of the coastal marine biota of the KIMR is warranted to better understand New Zealand's subtropical marine biota and its affinities with other marine biotas of the South Pacific. 相似文献