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David J. Gower Marcel T. Kouete Thomas M. Doherty-Bone Echalle S. Ndeme Mark Wilkinson 《Journal of Natural History》2015,49(3-4):233-253
The indotyphlid caecilian amphibian Idiocranium russeli Parker, 1936 is the only nominal species in its genus. Apart from two additional, largely overlooked locality records that we consider to be of an undescribed species, I. russeli is known with certainty from only a single collection of c.50 specimens from a single locality in 1933. We report new material from fieldwork in 2012 carried out in the vicinity of the type locality. Digging surveys at 34 sites for a total of >2000 person minutes found 50 I. russeli at 15 of these sites, extending the known range of the species by more than 40 km south and from an elevation of c.670 m to 104–820 m. The species probably occurs in nearby Nigeria and in some protected areas, is tolerant of some human disturbance, and is likely to move from Data Deficient to Least Concern on the IUCN Red List. Males have relatively longer and wider heads than females. Total length measured for preserved specimens is less than for freshly anaesthetized specimens, by up to 14.1%. Previously, preserved I. russeli were reported as having a maximum length of 114 mm, but the new sample includes specimens with total lengths of 145 mm in preservation and 167 mm when fresh. The sex of the smallest independent specimens (total length 62 mm in preservation) could be determined from examination of the gonads, hatchlings are c.30 mm, and I. russeli is confirmed as one of the smallest known caecilian species. 相似文献
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Alfvénic waves with sufficient energy to power the quiet solar corona and fast solar wind 总被引:1,自引:0,他引:1
Energy is required to heat the outer solar atmosphere to millions of degrees (refs 1, 2) and to accelerate the solar wind to hundreds of kilometres per second (refs 2-6). Alfvén waves (travelling oscillations of ions and magnetic field) have been invoked as a possible mechanism to transport magneto-convective energy upwards along the Sun's magnetic field lines into the corona. Previous observations of Alfvénic waves in the corona revealed amplitudes far too small (0.5?km?s(-1)) to supply the energy flux (100-200?W?m(-2)) required to drive the fast solar wind or balance the radiative losses of the quiet corona. Here we report observations of the transition region (between the chromosphere and the corona) and of the corona that reveal how Alfvénic motions permeate the dynamic and finely structured outer solar atmosphere. The ubiquitous outward-propagating Alfvénic motions observed have amplitudes of the order of 20?km?s(-1) and periods of the order of 100-500?s throughout the quiescent atmosphere (compatible with recent investigations), and are energetic enough to accelerate the fast solar wind and heat the quiet corona. 相似文献
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'Water-tastes' are gustatory after-impressions elicited by water following the removal of a chemical solution from the mouth, akin to colour after-images appearing on 'white' paper after fixation on coloured images. Unlike colour after-images, gustatory after-effects are poorly understood. One theory posits that 'water-tastes' are adaptation phenomena, in which adaptation to one taste solution causes the water presented subsequently to act as a taste stimulus. An alternative hypothesis is that removal of the stimulus upon rinsing generates a receptor-based, positive, off-response in taste-receptor cells, ultimately inducing a gustatory perception. Here we show that a sweet 'water-taste' is elicited when sweet-taste inhibitors are rinsed away. Responses of cultured cells expressing the human sweetener receptor directly parallel the psychophysical responses-water rinses remove the inhibitor from the heteromeric sweetener receptor TAS1R2-TAS1R3, which activates cells and results in the perception of strong sweetness from pure water. This 'rebound' activity occurs when equilibrium forces on the two-state allosteric sweet receptors result in their coordinated shift to the activated state upon being released from inhibition by rinsing. 相似文献
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Marcel Monnier 《Cellular and molecular life sciences : CMLS》1959,15(8):321-323
Summary Psilocybin, the by-product of which Psilocin] has been identified as 4-hydroxy-dimethyl-tryptamine (4-HTP) develops in the waking rabbit a marked activation of the somatic behaviour and of the electrical brain activity. This stimulating action is due to a depression of the mediothalamic recruiting and moderating system rather than to an activation of the reticular arousal system. The electrophysiological effects of 4-HTP are compared with those of 5-HTP. 相似文献
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An expression profile for diagnosis of lymph node metastases from primary head and neck squamous cell carcinomas 总被引:15,自引:0,他引:15
Roepman P Wessels LF Kettelarij N Kemmeren P Miles AJ Lijnzaad P Tilanus MG Koole R Hordijk GJ van der Vliet PC Reinders MJ Slootweg PJ Holstege FC 《Nature genetics》2005,37(2):182-186
Metastasis is the process by which cancers spread to distinct sites in the body. It is the principal cause of death in individuals suffering from cancer. For some types of cancer, early detection of metastasis at lymph nodes close to the site of the primary tumor is pivotal for appropriate treatment. Because it can be difficult to detect lymph node metastases reliably, many individuals currently receive inappropriate treatment. We show here that DNA microarray gene-expression profiling can detect lymph node metastases for primary head and neck squamous cell carcinomas that arise in the oral cavity and oropharynx. The predictor, established with an 82-tumor training set, outperforms current clinical diagnosis when independently validated. The 102 predictor genes offer unique insights into the processes underlying metastasis. The results show that the metastatic state can be deciphered from the primary tumor gene-expression pattern and that treatment can be substantially improved. 相似文献
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