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991.
Zoé Uhry Laurent Remontet Marc Colonna Aurélien Belot Pascale Grosclaude Nicolas Mitton Solenne Delacour-Billon Julie Gentil Marjorie Boussac-Zarebska Nadine Bossard Arlette Danzon Michelle Altana François Frete Alain Weill Agnès Rogel 《Cancer epidemiology》2013,37(2):99-114
Background: District-level cancer incidence estimation is an important issue in countries without a national cancer registry. This study aims to both evaluate the validity of district-level estimations in France for 24 cancer sites, using health insurance data (ALD demands – Affection de Longue Durée) and to provide estimations when considered valid. Incidence is estimated at a district-level by applying the ratio between the number of first ALD demands and incident cases (ALD/I ratio), observed in those districts with cancer registries, to the number of first ALD demands available in all districts. These district-level estimations are valid if the ratio does not vary greatly across the districts or if variations remain moderate compared with variations in incidence rates. Methods: Validation was performed in the districts covered by cancer registries over the period 2000–2005. The district variability of the ALD/I ratio was studied, adjusted for age (mixed-effects Poisson model), and compared with the district variability in incidence rate. The epidemiological context is also considered in addition to statistical analyses. Results: District-level estimation using the ALD/I ratio was considered valid for eight cancer sites out of the 24 studied (lip–oral cavity–pharynx, oesophagus, stomach, colon–rectum, lung, breast, ovary and testis) and incidence maps were provided for these cancer sites. Conclusion: Estimating cancer incidence at a sub-national level remains a difficult task without a national registry and there are few studies on this topic. Our validation approach may be applied in other countries, using health insurance or hospital discharge data as correlate of incidence. 相似文献
992.
993.
The Fractal Model: a new model to describe the species accumulation process and relative abundance distribution (RAD) 总被引:2,自引:0,他引:2
Quantifying a sampled collection of taxa is a widespread problem in ecology. A number of diversity indices have been proposed and used in numerous works in spite of a lack of statistical characteristics and tests of comparison. These Relative Abundance Distributions (RAD) can also be described using graphic representations exhibiting both the number of taxa and the quantitative distribution of the individuals which constitute these taxa. Fitting these RADs to deterministic or stochastic models remains problematic for different reasons like scale dependence or complexity of the numerical procedures. In our study, we introduce a new model to describe RAD and ecological succession. This model is a Fractal Model based on the assumption that during an ecological succession/accumulation process, at each step of the succession, K new species appear which are k times more abundant with K = k d (where d is a fractal dimension). We use a Monte-Carlo procedure with a Kolmogorov-Smirnov distance to fit this model and to estimate parameters. Through the study of entomological data from a Mediterranean Man And Biosphere reserve, we demonstrate the qualities of the new Fractal Model. Thus, the Fractal Model was rejected for none of the 13 RADs tested. In addition, the parameters ( K , k and d ) are independent of the Hill family diversity indices and of three evenness indices and are able to provide additional information concerning both the diversity of the sampled ecosystem and development of this biodiversity during the species accumulation process in this ecosystem. 相似文献
994.
Amanda E. I. Proudfoot Steven C. Brown Alain R. Bernard Jean-Yves Bonnefoy Eric H. Kawashima 《The protein journal》1993,12(4):489-497
A synthetic gene for human interleukin-6 has been expressed inE. coli. The protein has been purified and renatured and has the same activity as natural human IL-6 using the 7TD1 cell proliferation assay. The protein undergoes specific cleavage by a thiol protease, yielding two new N-termini at Arg-9 and His-15. The truncated proteins retain full biological activity. The degradation results in the loss of sharp amide resonances in the1H-NMR spectrum, and little change to the ultraviolet CD spectrum. Several amino acid type assignments could be made for these sharp amides using a DQF-COSY 2D-NMR experiment. The N-terminal 15 amino acids exist as a flexible, random coil, attached to a central structure. 相似文献
995.
Adnane Hitmi Alain Coudret Chantal Barthomeuf 《Critical reviews in biochemistry and molecular biology》2013,48(5):317-337
Pyrethrins, the most economically important natural insecticide, comprise a group of six closely related monoterpene esters. The industrial production is based on their extraction from Chrysanthemum cinerariaefolium (Pyrethrum) capitula. The world production of natural pyrethrins still falls short of global market demand stimulating the research in in vitro production as an alternative to conventional cultivation methods. The different biotechnological alternatives such as callus cultures, shoot and root cultures, plant cell suspension cultures, and bioconversion of precursors by means of enzymatic synthesis or genetically engineered microorganisms, as well as the progress achieved in methods for the identification and quantitation of insecticidal compounds have been reviewed. Although technology for plant cell culture exists, industrial applications have, to date, been limited due to both the low economical viability and technological feasibility at large scale. Bioconversion of readily available precursors looks more attractive, but more research is needed before this technology is used for the industrial production of pyrethrins. 相似文献
996.
A noticeable characteristic of nervous systems is the arrangement of synapses into distinct layers. Such laminae are fundamental for the spatial organisation of synaptic connections transmitting different kinds of information. A major example of this is the inner plexiform layer (IPL) of the vertebrate retina, which is subdivided into at least ten sublayers. Another noticeable characteristic of these retina layers is that neurons are displayed in the horizontal plane in a non-random array termed as mosaic patterning. Recent studies of vertebrate and invertebrate systems have identified molecules that mediate these interactions. Here, we review the last mechanisms and molecules mediating retinal layering. 相似文献
997.
998.
The proportions of the different bibionid genera are used to estimate the temperature changes between the Late Eocene and the Late Miocene in Western Europe. The genus Plecia is a good indicator of the warm Cenozoic palaeoclimates. We propose a new approach for the estimation of the value of the palaeoclimatic information that could be obtained by actualistic inferences using extinct taxa. Other taxa (i.e. Mastotermitidae) that could appear a priori better palaeoclimatic indicators result to be less sensitive than bibionids to temperature changes. Intraspecific and intrageneric morphological diversity is explored for the genera Bibio, Penthetria and Plecia, showing the difficulties to characterize the fossil bibionid species. 相似文献
999.
1000.
Serrastruma lujae ants individually search for collembolans in the leaf litter of humid tropical forests. During the dry season, collembolans aggregate in wet patches randomly scattered in the dry litter where numerous single workers come hunting from their nest. We simulated this situation in the laboratory, and observed that workers seem to be able to use the humidity gradient direction to efficiently orient themselves towards a wet patch. Once the patch has been reached, they exhibit area-concentrated searching,consisting, in particular, of adopting a high sinuosity and a low speed. After capturing a collembolan, the ants return to their nest along nearly straight paths. This ability may rely on a spatial memory of the nest location by means of a path-integration process. In the absence of prey, however, various behaviours were observed after an unsuccessful search. Comparisons between these data and the results obtained with a homogeneously wet environment simulating the rainy season situation showed that these ants do not simply respond to the humidity level but are also sensitive to the degree of patchiness of their environment. They can therefore be said to be able to adapt suitably to the considerable climatic changes they encounter during the year. 相似文献