A highly sensitive paired ion electrospray ionization mass spectrometry (PIESI-MS) approach was developed for the trace determination of sphingolipids. Apart from their structure role, specific sphingolipids can play a role in cell signaling and as disease markers. With the optimal pairing reagents, detection limits ranged from low femtomole to picomole levels for 14 selected sphingolipids. Thi...

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Does job control act as a stress-buffer when employees’ type and level of work selfdetermination is taken into account? It was anticipated that job control would only be stress-buffering for employees high in self-determined and low in non-self-determined work motivation. In contrast, job control would be stress-exacerbating for employees who were low in self-determined and high in non-self-det...

By diffusing from the sediments into ocean, 227Ac (half-life = 21.8 y) is a powerful tracer of vertical mixing in deep ocean on decadal time scales. However, its use limited by very low concentration resulting large volumes (hundreds L) water required for analysis. We have developed new method analysis isotope dilution and MC-ICPMS that significantly improves measurement accuracy reduces sample...

in this paper, the performance of 11 different distances for image retrieval and classification, based on color, shape and texture, is evaluated. the precision-recall measure and the correct classification rate of the k-nn classifier are used to evaluate retrieval and classification performances, respectively. the experimental results for a database of 1000 images from 10 different semantic gro...