Background and Scope Because of the crucial role coarse roots (>2 mm diameter) play in plant functions and terrestrial ecosystems, detecting and quantifying the size, architecture, and biomass of coarse roots are important. Traditional excavation methods are labor intensive and destructive, with limited quantification and repeatability of measurements over time. As a nondestructive geophysical tool for delineating buried features in shallow subsurface, ground penetrating radar (GPR) has been applied for coarse root detection since 1999. This article reviews the state-ofknowledge of coarse root detection and quantification using GPR, and discusses its potentials, constraints, possible solutions, and future outlooks. Some useful suggestions are provided that can guide future studies in this field. Conclusions The feasibility and accuracy of coarse root investigation by GPR have been tested in various site conditions (mostly in controlled conditions or within plantations) and for different plant species (mostly tree root systems). Thus far, single coarse root identification and coarse root system mapping have been conducted using GPR, including roots under pavements in urban environment. Coarse root diameter and biomass have been estimated from indexes extracted from root GPR radargrams. Coarse root development can be observed by repeated GPR scanning over time. Successful GPR-based coarse root investigation is site specific, and only under suitable conditions can reliable measurements be accomplished. The best quality of root detection by GPR is achieved in well-drained and electrically-resistive soils (such as sands) under dry conditions. Numerous factors such as local soil conditions, root electromagnetic properties, and GPR antenna frequency can impact the reliability and accuracy of GPR detection and quantification of coarse roots. As GPR design, data processing software, field data collection protocols, and root parameters estimation methods are continuously improved, this noninvasive technique could offer greater potential to study coarse roots.

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Previous studies in our lab have identified Pre-B-cell colony enhancing factor as a novel biomarker in acute lung injury. This study continues to elucidate the underlying molecular mechanism of Pre-B-cell colony enhancing factor (PBEF) in the pathogenesis of acute lung injury in pulmonary cell culture models. Our results revealed that IL-1β induced PBEF expression in pulmonary vascular endothelial cells at the transcriptional level and a -1535 T-variant in the human PBEF gene promoter significantly attenuated its binding to an IL-1β induced unknown transcription factor. This may underlie the reduced expression of PBEF and thus the less susceptibility to acute lung injury in those -1535T carriers. Furthermore, overexpression of PBEF significantly augmented IL-8 secretion and mRNA expression by more than 6 fold and 2 fold in A549 cells and HPAEC, respectively. It also significantly augmented IL-1β mediated cell permeability by 44% in A549 cells and 65% in endothelial cells. The knockdown of PBEF expression significantly inhibited IL-1β-stimulated IL-8 secretion and mRNA level by 60% and 70%, respectively; and the knockdown of PBEF expression also significantly attenuated IL-1β-induced cell permeability by 29% in epithelial cells and 24% in endothelial cells. PBEF expression also affected the expression of two other inflammatory cytokines (IL-16 and CCR3 genes). These results suggest that PBEF is critically involved in pulmonary vascular and epithelial inflammation and permeability, which are hallmark features in the pathogenesis of acute lung injury. This study lend further support that PBEF is a potential new target in acute lung injury.

Abstract:As a nondestructive geophysical tool, Ground penetrating radar (GPR) has been applied in tree root study in recent years. With increasing amounts of GPR data collected for roots, it is imperative to develop an efficient automatic recognition of roots in GPR images. However, few works have been completed on this topic because of the complexity in root recognition problem. Based on GPR datasets from both controlled and in situ experiments, the randomized Hough transform (RHT) algorithm was evaluated in root object recognition for different center frequencies (400 MHz, 900 MHz, and 2000 MHz) in this paper. Reasonable accuracy was obtained (both a high recognition rate and a low false alarm rate) in these datasets, which shows it is feasible to apply the RHT algorithm for root recognition. Furthermore, we evaluated the influence of root and soil factors on the recognition. We found that the performance of RHT algorithm is mainly affected by root interval length, root orientation, and clutter noise of soil. The recognition results by RHT could be applied for large scale root system distribution study in belowground ecology. Further studies should be conducted to reduce clutter noise and improve the recognition of the complex root reflections.

The pleiotropic effects of estrogen are mediated via stimulation of two estrogen receptor (ER) subtypes, ER␣ and ER␤. Although a number of studies have identified expression of one or both subtypes in estrogen target tissues, fewer studies have correlated ER expression with a functional role of these proteins in regulating cellular excitability. In the present study, we have combined cellular fluorescence, immunocytochemistry, and molecular expression techniques with single-channel patch-clamp studies to determine which ER mediates estrogen-stimulated potassium channel activity in human coronary artery smooth muscle cells (HCASMC). We had demonstrated previously that estrogen stimulates activity of the large-conductance, calcium-and voltage-activated potassium (BK Ca ) channel in HCASMC via a nongenomic mechanism. We now demonstrate expression of both ER␣ and ER␤ subtypes in HCASMC. Functionally, however, expression of ER␣ antisense plasmid abolished the acute effect of estrogen on these channels, whereas estrogen retained its ability to stimulate BK Ca channels in cells transfected with only green fluorescence protein. In contrast, overexpression of ER␣ enhanced the stimulatory action of estrogen in HCASMC. Transfection with ER␣ antisense/sense plasmid did not alter ER␤ expression. These findings indicate that the ER␣ isoform mediates estrogen-induced stimulation of BK Ca channels in HCASMC and thereby provide evidence for a receptor-dependent signaling mechanism that can mediate estrogen-induced inhibition of cellular excitability.

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Edge impurity transport is studied in electron cyclotron resonance heating (ECRH) L-mode plasmas of the HL-2A tokamak based on space-resolved vacuum ultraviolet spectroscopy with which radial profiles of impurity line emissions are measured from the core region inside the last closed flux surface (LCFS) and the edge region in the scrape-off layer, simultaneously. The radial profile of carbon emissions of C V (2271 Å: 1s2s 3 S-1s2p 3 P) reconstructed into the local emissivity profile is analysed with a one-dimensional impurity transport code, and the diffusion coefficient and convective velocity of impurity ions are determined in the core region of the HL-2A tokamak. The impurity source is also determined with the measured absolute emissivity profiles of C IV (1548 Å: 1s 2 2s 2 S-1s 2 2p 2 P) located at the LCFS. The ratio of C V to C IV can therefore be used as an index to characterize the core impurity transport between the LCFS and the radial region of the C V emission at a normalized radius of about ρ = 0.6. The ratio measured from ohmic discharges shows a gradual decrease with electron density. However, the ratio suddenly decreases by a factor of three when the ECRH focused in the plasma centre is switched on, suggesting a strong enhancement of the impurity transport. The analysis with the transport code indicates a change in the convective term. The convective velocity of C 4+ ions changes from inward to outward direction during the ECRH phase, while an inward velocity usually exists in the ohmic phase. Possible mechanisms for the reversal of the convective velocity are discussed.