Polarization ratio characteristics of electromagnetic scattering fromsea ice inpolar areas

In the global climate system, the polar regions are sensitive indicators of climate change, in which sea ice plays an important role. Satellite remote sensing is a significant tool for monitoring sea ice. The use of synthetic aperture radar(SAR) images to distinguish sea ice from sea water is one of the current research hotspots in this topic. To distinguish sea ice from the open sea, the polarization ratio characteristics of sea ice and sea water are studied for L-band and C-band radars, based on an electromagnetic scattering model of sea ice derived from the integral equation method(IEM) and the radiative transfer(RT) model. Numerical experiments are carried out based on the model and the results are given as follows. For L-band, the polarization ratio for sea water depends only on the incident angle, while the polarization ratio for sea ice is related to the incident angle and the ice thickness. For C-band, the sea water polarization ratio is influenced by the incident angle and the root mean square(RMS) height of the sea surface. For C-band, for small to medium incident angles,the polarization ratio for bare sea ice is mainly determined by the incident angle and ice thickness. When the incident angle increases, the RMS height will also affect the polarization ratio for bare sea ice. If snow covers the sea ice, then the polarization ratio for sea ice decreases and is affected by the RMS height of snow surface, snow thickness, volume fraction and the radius of scatterers. The results show that the sea ice and the open sea can be distinguished by using either L-band or C-band radar according to their polarization ratio difference. However, the ability of L-band to make this differentiation is higher than that of C-band.

Transcription factors T-bet/GATA-3/Foxp3 in peripheral blood of patients with chronic otitis media with effusion

To the Editor:Otitis media with effusion(OME),also known as secretory otitis,is a disease in which secreted fluid accumulates in the middle ear cavity and is a major cause of hearing loss,both in children and adults.[1]Causes of OME include recurrent infections,inflammatory conditions,malformations,and eustachian tube dysfunctions.[2]Although most patients could recover spontaneously,by medication,or by surgery,some patients show frequent recurrence of otitis media for more than 3 months,called chronic otitis media with effusion(COME).[1]The pathogenesis of COME is not completely understood.Increasing evidence suggests a central role of immunologic cells and th&r associated cytokines in the chronic inflammation that characterizes COME.

Stereoselective Synthesis of a Tetrasaccharide Fragment from RhamnogalacturonanⅡSide Chain A

Comprehensive Summary An efficient synthesis of a complex tetrasaccharide fragment 1 structurally related to rhamnogalacturonan ll side chain A has been accomplished through a stepwise glycosylation strategy.Challenges involved in the synthesis include the facile construction of the sterically crowded L-fucopyranose core and the stereoselective formation of two 1,2-cis-glycosidic linkages.The 3,4-disubstituted L-fucopyranoside structure was successfully constructed through a'counterclockwise'glycosylation sequence,namely,the less reactive axial 4-OH group of the central fucose unit was glycosylated first,then the 3-OH.Besides,a 2-pyridinecarbonyl-assistedα-D-xylosylation was developed to synthesize theα-D-xylopyranosidic linkage and a 3,4-O-benzoyl-controlledα-L-galactosylation reaction was usedforthe stereoselective synthesis of the correspondingα-L-galactopyranosidic linkage.