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We investigate the effect of the temperature–size rule upon zooids of the tropical American bryozoan Cupuladria exfragminis. Results show that mean zooid length, zooid width and zooid area vary significantly between clonal replicates of C. exfragminis kept under different controlled temperature conditions. Significantly larger zooids are produced during times of lowered water temperature that are comparable with the temperatures that occur during seasonal upwelling along the Pacific coast of Panama where the animal lives in abundance. Interpolation of data suggests that a drop of 1 °C causes a 5% increase in zooid size, and that almost all variation in zooid size in natural populations can be explained by temperature. Results are discussed in context of the potential use of zooid size variation in cupuladriid bryozoans to measure the strength of seasonal upwelling in ancient seas by analysing zooid size changes in fossil colonies. The technique of cloning cupuladriid colonies by fragmentation is also discussed with reference to its benefits in experimental studies where genotypes need to be controlled or replicated. 相似文献
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Viability theory for an ecosystem approach to fisheries 总被引:1,自引:1,他引:1
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Combining indicator trends to assess ongoing changes in exploited fish communities: diagnostic of communities off the coasts of France 总被引:1,自引:1,他引:1
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A new approach for the solution of the two-dimensional guillotine-cutting problem in ship production
A. Cemil Dikili 《Ocean Engineering》2004,31(8-9):1193-1203
A new approach has been developed for the arrangement of rectangular pieces in plates for the guillotine-cutting problem as encountered in ship production and similar manufacturing processes. The algorithm is quite novel in the sense that instead of making preliminary specifications and ignoring all the alternative arrangements, as is the case for most of the current models, it selectively considers feasible arrangements by eliminating the majority of the probable arrangements that render the problem insolvable. Intermediate steps of the algorithm produce results which cannot be obtained through integer programming. Losses are distributed to the minimum number of plates. The number of arrangement plans is also minimized. Overall the solution of the problem has been drastically simplified to allow even hand calculations instead of long computer runs. 相似文献
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The indicator kriging (IK) is one of the most efficient nonparametric methods in geo-statistics. The order relation problem in the conditional cumulative distribution values obtained by IK is the most severe drawback of it. The correction of order relation deviations is an essential and important part of IK approach. A monotone regression was proposed as a new correction method which could minimize the deviation from original quintiles value, although, ensuring all order relations. 相似文献
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The Bayesian detection of discontinuities in a polynomial regression and its application to the cycle-slip problem 总被引:4,自引:1,他引:3
Maria Clara de Lacy Mirko Reguzzoni Fernando Sansò Giovanna Venuti 《Journal of Geodesy》2008,82(9):527-542
This paper deals with the problem of detecting and correcting cycle-slips in Global Navigation Satellite System (GNSS) phase
data by exploiting the Bayesian theory. The method is here applied to undifferenced observations, because repairing cycle-slips
already at this stage could be a useful pre-processing tool, especially for a network of permanent GNSS stations. If a dual
frequency receiver is available, the cycle-slips can be easily detected by combining two phase observations or phase and range
observations from a single satellite to a single receiver. These combinations, expressed in a distance unit form, are completely
free from the geometry and depend only on the ionospheric effect, on the electronic biases and on the initial integer ambiguities;
since these terms are expected to be smooth in time, at least in a short period, a cycle-slip in one or both the two carriers
can be modelled as a discontinuity in a polynomial regression. The proposed method consists in applying the Bayesian theory
to compute the marginal posterior distribution of the discontinuity epoch and to detect it as a maximum a posteriori (MAP)
in a very accurate way. Concerning the cycle-slip correction, a couple of simultaneous integer slips in the two carriers is
chosen by maximazing the conditional posterior distribution of the discontinuity amplitude given the detected epoch. Numerical
experiments on simulated and real data show that the discontinuities with an amplitude 2 or 3 times larger than the noise
standard deviation are successfully identified. This means that the Bayesian approach is able to detect and correct cycle-slips
using undifferenced GNSS observations even if the slip occurs by one cycle. A comparison with the scientific software BERNESE
5.0 confirms the good performance of the proposed method, especially when data sampled at high frequency (e.g. every 1 s or
every 5 s) are available. 相似文献