Synthetic TEC mapping with ordinary and universal kriging
2007 3RD INTERNATIONAL CONFERENCE ON RECENT ADVANCES IN SPACE TECHNOLOGIES, VOLS 1 AND 2
Authors: Sayin, I.; Arikan, F.; Arikan, O.
Abstract
Spatiotemporal variations in the ionosphere affects the BF and satellite communications and navigation systems. Total Electron Content (TEC) is an important parameter since it can be used to analyze the spatial and temporal variability of the ionosphere. In this study, the performance of the two widely used Kriging algorithms, namely Ordinary Kriging (OrK-) and Universal Kriging (UnK), is compared over the synthetic data set In order to represent various ionospheric states, such as quiet and disturbed days, spatially correlated residual synthetic TEC data with different variances is generated and added to trend functions. Synthetic data sampled with various type of sampling patterns and for a wide range of sampling point numbers. It is observed that for small sampling numbers and with higher variability, OrK gives, smaller errors. As the sample number increases, UnK errors decrease faster. For smaller variances in the synthetic surfaces, UnK gives better results. For increasing variance and decreasing range values, usually, the errors increase for both OrK and Unk.
Recruitment of uterine NK cells: Induction of CXC chemokine ligands 10 and 11 in human endometrium by estradiol and progesterone
JOURNAL OF IMMUNOLOGY
Authors: Sentman, CL; Meadows, SK; Wira, CR; Eriksson, M
Abstract
Uterine NK (uNK) cells express a unique set of markers compared with blood NK cells. However, recent studies suggest that uNK cells may be derived from the recruitment of blood NK cells into the endometrium. In this study, we used an in vitro organ culture system to demonstrate that estradiol induces expression of chemokines CXCL10 and/or CXCL11 within human endometrium in 85% of patient samples tested. The average increase in gene expression after 10(-9) M estradiol treatment was 8.5-fold for CXCL10 and 7.7-fold for CXCL11 compared with medium alone. We observed that a specific estrogen receptor antagonist (ICI182780) was able to prevent chemokine gene induction, indicating that the effect of estradiol was receptor mediated. Moreover, our study showed that progesterone induced CXCL10 and CXCL11 expression in 83% of endometrial samples tested. We have also found that uNK cells and blood NK cells express the receptor for CXCL10 and CXCL11, CXCR3, with the highest expression found on uNK cells and CD56(bright) blood NK cells. These data indicate that sex hormones induce specific chemokines in nonpregnant human endometrium that can activate NK cell migration, and suggest that this mechanism may account for the increased NK cell numbers in endometrium during the menstrual cycle.