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91.
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Matthieu Gounelle Marc Chaussidon Alessandro Morbidelli Jean-Alix Barrat Cécile Engrand Michael E. Zolensky Kevin D. McKeegan 《Proceedings of the National Academy of Sciences of the United States of America》2009,106(17):6904-6909
Micrometeorites with diameter ≈100–200 μm dominate the flux of extraterrestrial matter on Earth. The vast majority of micrometeorites are chemically, mineralogically, and isotopically related to carbonaceous chondrites, which amount to only 2.5% of meteorite falls. Here, we report the discovery of the first basaltic micrometeorite (MM40). This micrometeorite is unlike any other basalt known in the solar system as revealed by isotopic data, mineral chemistry, and trace element abundances. The discovery of a new basaltic asteroidal surface expands the solar system inventory of planetary crusts and underlines the importance of micrometeorites for sampling the asteroids'' surfaces in a way complementary to meteorites, mainly because they do not suffer dynamical biases as meteorites do. The parent asteroid of MM40 has undergone extensive metamorphism, which ended no earlier than 7.9 Myr after solar system formation. Numerical simulations of dust transport dynamics suggest that MM40 might originate from one of the recently discovered basaltic asteroids that are not members of the Vesta family. The ability to retrieve such a wealth of information from this tiny (a few micrograms) sample is auspicious some years before the launch of a Mars sample return mission. 相似文献
93.
U. Zingg C. Langton B. Addison B. P. L. Wijnhoven J. Forberger S. K. Thompson A. J. Esterman D. I. Watson 《Journal of gastrointestinal surgery》2009,13(4):611-618
Background Different prediction models for operative mortality after esophagectomy have been developed. The aim of this study is to independently validate prediction models from Philadelphia, Rotterdam, Munich, and the ASA. Methods The scores were validated using logistic regression models in two cohorts of patients undergoing esophagectomy for cancer from Switzerland (n = 170) and Australia (n = 176). Results All scores except ASA were significantly higher in the Australian cohort. There was no significant difference in 30-day mortality or in-hospital death between groups. The Philadelphia and Rotterdam scores had a significant predictive value for 30-day mortality (p = 0.001) and in-hospital death (p = 0.003) in the pooled cohort, but only the Philadelphia score had a significant prediction value for 30-day mortality in both cohorts. Neither score showed any predictive value for in-hospital death in Australians but were highly significant in the Swiss cohort. ASA showed only a significant predictive value for 30-day mortality in the Swiss. For in-hospital death, ASA was a significant predictor in the pooled and Swiss cohorts. The Munich score did not have any significant predictive value whatsoever. Conclusion None of the scores can be applied generally. A better overall predictive score or specific prediction scores for each country should be developed. No score generally applicable 相似文献
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95.
Keller M Perrin G Meurisse M Ferreira G Lévy F 《The European journal of neuroscience》2004,20(12):3433-3441
Ewes form a selective olfactory memory for their lambs after 2 h of mother-young interaction following parturition. Once this recognition is established, ewes will subsequently reject any strange lamb approaching the udder (i.e. maternal selectivity). The present study tested the functional contribution of different amygdala nuclei to lamb olfactory memory formation. Using the anaesthetic lidocaine, cortical, medial or basolateral nuclei of the amygdala were transiently inactivated during lamb odour memory formation. Reversible inactivation of either cortical or medial amygdala during the first 8 h postpartum impaired lamb olfactory recognition, whereas inactivation of the basolateral nucleus or infusion of artificial cerebrospinal fluid did not. Control experiments indicate that inactivation of the cortical and medial nuclei of the amygdala specifically disrupt memory formation rather than olfactory perception or memory retrieval. These findings show that both nuclei of the amygdala are required for the formation of a lamb olfactory memory and suggest functional interaction between these two nuclei. 相似文献
96.
Dominique Marnet Matthieu Vinchon Olivier Kerdraon Sylvie Joriot Caroline Chafiotte Patrick Dhellemmes 《Child's nervous system》2008,24(8):887-891
BACKGROUND: Fetus in fetu (FIF) is a rare condition in medicine where an aberrant monozygotic twining results in inclusion of a degenerated fetus inside its twin bearer. Whereas FIF is generally defined as a fetiform vertebrate mass, teratoma is considered as a tumor composed of disorganized tissues derived from the three embryological layers. Recent data plead for a common origin and suggest a continuum between FIF and teratoma. CASE HISTORY: We describe the case of an intraventricular mass diagnosed by prenatal imaging and associated with triventricular hydrocephalus. Surgical removal of a non-vertebrate mass covered by normal skin was performed when the child was 15 months old. Now aged of 30 months, the child continues to develop normally. Histological data were in favor of a FIF. DISCUSSION: We discuss the diagnosis, pathogenesis, and prognosis in the light of data from the recent literature. CONCLUSIONS: Aberrant monozygotic twining leading to inclusion of a degenerate fetus inside its twin bearer results in FIF or teratomas. Surgical removal represents the main treatment. Intracranial FIF remains an extremely rare congenital condition, with a favorable oncological prognosis; the developmental prognosis appears conditioned by the absence of other malformation, the small size of the lesion, and the early management of intracranial hypertension. 相似文献
97.
Matthieu Keller Michael J. Baum Olivier Brock Peter A. Brennan Julie Bakker 《Behavioural brain research》2009,200(2):268
In the field of sensory perception, one noticeable fact regarding olfactory perception is the existence of several olfactory subsystems involved in the detection and processing of olfactory information. Indeed, the vomeronasal or accessory olfactory system is usually conceived as being involved in the processing of pheromones as it is closely connected to the hypothalamus, thereby controlling reproductive function. By contrast, the main olfactory system is considered as a general analyzer of volatile chemosignals, used in the context of social communication, for the identification of the status of conspecifics. The respective roles played by the main and the accessory olfactory systems in the control of mate recognition and sexual behavior are at present still controversial. We summarize in this review recent results showing that both the main and accessory olfactory systems are able to process partially overlapping sets of sexual chemosignals and that both systems support complimentary aspects in mate recognition and in the control of sexual behavior. 相似文献
98.
Matthieu Vinchon 《Child's nervous system》2009,25(6):639-640
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100.