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The catchability of western rock lobsters (Panulirus cygnus) during the spawning season (October and November) may be affected by their reproductive state. In this study, movement and food consumption of males and females of different reproductive states held in laboratory tanks were measured as proxies for catchability. Density of lobsters was found to influence both movement and food consumption. Solitary animals and, to a lesser extent, two lobsters per tank, were more sedentary and consumed significantly less food than animals at a density of three or four specimens per tank. Tests using three animals per tank confirmed that mature, unmated, and ovigerous females carrying early stage eggs moved more frequently away from their shelters than males or females carrying late stage eggs (P < 0.0001, d.f. = 3). Further, unmated females and females with early stage eggs recorded significantly higher food consumption (P < 0.0061, d.f. = 3) compared with males or females carrying late stage eggs. The greater time spent away from shelter and also food consumption make unmated females and females with early stage eggs likely to be more catchable than males or females with late stage eggs. As catchability is commonly used to obtain population estimates from survey data, these results have implications for surveys which use catch rates of breeding animals as indicators of egg production. 相似文献
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North Atlantic Oscillation: Description,Mechanisms, and Influence on the Eurasian Climate 总被引：1，自引：0，他引：1
Polonskii A. B. Basharin D. V. Voskresenskaya E. N. Worley S. 《Physical Oceanography》2004,14(2):96-113
The present work is devoted to the characteristic of the North-Atlantic Oscillation and the analysis of the state-of-the-art of this problem. In the survey section of the work, we deal with the following issues: the definition of the North Atlantic and Arctic Oscillations, their interaction with oceanic processes, and their influence on the variations of climate in Eurasia. In addition, by using the COADS (Comprehensive Ocean Atmosphere Data Set) data and the data on the discharge of European and Asian rivers, we establish some new original results. It is confirmed that the anomalies of the sea-surface temperature are consequences of the integral response of the ocean to the preceding atmospheric actions and that the spectra of these anomalies are characterized by the presence of significant peaks within the band of periods of 10–20 yr. These periods correspond to inherent oceanic variability. The atmospheric response manifests itself in the form of abnormal conditions over the catchment areas of European and Asian rivers, which leads to oscillations of their discharges. As a result of the intensification of the North Atlantic Oscillation and the displacement of the centers of action of the atmosphere in the 60–90s of the previous century, the influence of this oscillation on the climatic conditions in the European-Asian region became more intense. 相似文献
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Brenton A. Wilder Jeremy T. Lancaster Peter H. Cafferata Drew B. R. Coe Brian J. Swanson Donald N. Lindsay William R. Short Alicia M. Kinoshita 《水文研究》2021,35(1):e13976
Following wildfires, the probability of flooding and debris flows increase, posing risks to human lives, downstream communities, infrastructure, and ecosystems. In southern California (USA), the Rowe, Countryman, and Storey (RCS) 1949 methodology is an empirical method that is used to rapidly estimate post-fire peak streamflow. We re-evaluated the accuracy of RCS for 33 watersheds under current conditions. Pre-fire peak streamflow prediction performance was low, where the average R2 was 0.29 and average RMSE was 1.10 cms/km2 for the 2- and 10-year recurrence interval events, respectively. Post-fire, RCS performance was also low, with an average R2 of 0.26 and RMSE of 15.77 cms/km2 for the 2- and 10-year events. We demonstrated that RCS overgeneralizes watershed processes and does not adequately represent the spatial and temporal variability in systems affected by wildfire and extreme weather events and often underpredicted peak streamflow without sediment bulking factors. A novel application of machine learning was used to identify critical watershed characteristics including local physiography, land cover, geology, slope, aspect, rainfall intensity, and soil burn severity, resulting in two random forest models with 45 and five parameters (RF-45 and RF-5, respectively) to predict post-fire peak streamflow. RF-45 and RF-5 performed better than the RCS method; however, they demonstrated the importance and reliance on data availability. The important parameters identified by the machine learning techniques were used to create a three-dimensional polynomial function to calculate post-fire peak streamflow in small catchments in southern California during the first year after fire (R2 = 0.82; RMSE = 6.59 cms/km2) which can be used as an interim tool by post-fire risk assessment teams. We conclude that a significant increase in data collection of high temporal and spatial resolution rainfall intensity, streamflow, and sediment loading in channels will help to guide future model development to quantify post-fire flood risk. 相似文献
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High-precision geothermobarometry across the High Himalayan metamorphic sequence, Langtang Valley, Nepal 总被引：9，自引：0，他引：9
One of the long recognized features of Himalayan geology is the apparent inversion of metamorphic sequences, as evidenced in both metamorphic parageneses and thermobarometric data. With the aid of an extended thermobarometric dataset from the Langtang Valley section of the Higher Himalayan Crystallines, it can be demonstrated that the relatively large uncertainties associated with traditional thermobarometric techniques severely limit the tectonic interpretation of metamorphic gradients across the Himalayas. We apply the recently developed Δ PT approach, which significantly improves the precision to which pressure and temperature differences between samples may be calculated. High-precision thermobarometric data reveal an isothermal, rather than inverted, temperature array at Langtang, while the pressure data suggest significant structural complexity, with the Higher Himalayan Crystallines in the Langtang section comprising two distinct, possibly duplicated sequences, each having experienced considerable structural attenuation following metamorphism. 相似文献
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Lou Daniel Brenton R. Clarke Drew F. Parsons 《Geostandards and Geoanalytical Research》2019,43(3):435-452
We investigate the performance of sample preparation of gold ores using vibratory (bowl, ring and puck type) mills in common use in mineral analytical laboratories. The main criteria for effective grinding are using reduced grinding charge masses ≤ ca. 50% of nominal bowl capacity and using a grinding aid to prevent caking. We show that gold particles of millimetre scale can be comminuted to ≤ 100 µm by grinding in silica flour, bauxite, synthetic carborundum, or mixtures of silica and these materials using times of up to 5 min and that 95% < 50 µm is achievable with extended grinding. This suggests that modified grinding techniques can be used to make sample masses ≤ 5 g viable for routine determination of gold in geological samples. We also demonstrate homogenisation of a gold‐bearing copper sulfide mineral flotation concentrate alone and in mixtures with silica by extended grinding at reduced charge masses. To support this work, we develop a convenient new benchmark of gold ore sample preparation performance ‘G’, an apparent maximum gold particle size interpolated from replicate analytical variance in order to overcome the limitations of laborious sieve fraction analysis of gold particle size. We show useful agreement between G and sieve fraction analysis of gold particle size in samples and test the viability of G experimentally and by analysis of literature data. 相似文献
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Charles E. Worley 《Astrophysics and Space Science》1991,177(1-2):371-372
Any use of stars for astrometric purposes necessarily involves examination of their duplicity characteristics. The Washington Double Star Catalog (WDS) provides this information in a continuously updated and machine-readable format. This contribution describes the current data base and plans for its future extension. 相似文献
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Mineral equilibria calculations in the system K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–Fe2O3 (KFMASHTO) using thermocalc and its internally consistent thermodynamic dataset constrain the effect of TiO2 and Fe2O3 on greenschist and amphibolite facies mineral equilibria in metapelites. The end‐member data and activity–composition relationships for biotite and chloritoid, calibrated with natural rock data, and activity–composition data for garnet, calibrated using experimental data, provide new constraints on the effects of TiO2 and Fe2O3 on the stability of these minerals. Thermodynamic models for ilmenite–hematite and magnetite–ulvospinel solid solutions accounting for order–disorder in these phases allow the distribution of TiO2 and Fe2O3 between oxide minerals and silicate minerals to be calculated. The calculations indicate that small to moderate amounts of TiO2 and Fe2O3 in typical metapelitic bulk compositions have little effect on silicate mineral equilibria in metapelites at greenschist to amphibolite facies, compared with those calculated in KFMASH. The addition of large amounts of TiO2 to typical pelitic bulk compositions has little effect on the stability of silicate assemblages; in contrast, rocks rich in Fe2O3 develop a markedly different metamorphic succession from that of common Barrovian sequences. In particular, Fe2O3‐rich metapelites show a marked reduction in the stability fields of staurolite and garnet to higher pressures, in comparison to those predicted by KFMASH grids. 相似文献
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Sir Anthony Brenton 《Climate Policy》2013,13(5):541-546
The concept of ‘Great Powers’ extends well beyond its nineteenth century origins to current business in, for example, the EU, the UN Security Council, and the World Trade Organisation (WTO). Such core groups can be crucial to finding agreement in complex and fractured negotiations. Climate change was not initially seen as an issue for the Great Power-type architecture. The problem was of universal concern, requiring universal involvement. Moreover, climate's natural great powers (the EU, the US, China, Japan, Russia, Brazil, India, and Canada) split into three antagonistic camps: the EU pressing for sharp emissions reductions; the US, with the other developed powers, much more cautious; and China, India, and Brazil determined that action should be confined to the developed world. These divisions contributed hugely to the ineffectiveness of both the 1992 Rio convention and the 1997 Kyoto Protocol. In addition, as non-Organisation for Economic Co-operation and Development (OECD; particularly Chinese) emissions fast outgrew OECD emissions, their exclusion from any constraint became visibly untenable. So, from 2005 on, the Great Powers began to meet more closely in what became the Major Economies Forum. That cooperation contributed significantly to the 2009 Copenhagen Accord. The climate problem is of course far from being solved, but maintaining Great Power cooperation will be crucial to further progress. 相似文献