Remote Sensing of Aerosol Over Vegetation Cover Based on Pixel Level Multi-Wavelength Polarized Measurements

Often the aerosol contribution is small compared to the surface covered vegetation. while, atmospheric scattering is much more polarized than the surface reflection. In essence, the polarized light is much more sensitive to atmospheric scattering than to reflection by vegetative cover surface. Using polarized information could solve the inverse problem of separating the surface and atmospheric scattering contributions. This paper presents retrieval of aerosols properties from multi-wavelength polarized measurements. The results suggest that it is feasible and possibility for discriminating the aerosol contribution from the surface in the aerosol retrieval procedure using multidirectional and multi-wavelength polarization measurements. Keywords: Aerosol, remote sensing, polarized measurements, short wave infrare

Finite-Time Convergent Algorithms for Time-Varying Distributed Optimization

This paper focuses on finite-time (FT) convergent distributed algorithms for solving time-varying distributed optimization (TVDO). The objective is to minimize the sum of local time-varying cost functions subject to the possible time-varying constraints by the coordination of multiple agents in finite time. We first provide a unified approach for designing finite/fixed-time convergent algorithms to solve centralized time-varying optimization, where an auxiliary dynamics is introduced to achieve prescribed performance. Then, two classes of TVDO are investigated included unconstrained distributed consensus optimization and distributed optimal resource allocation problems (DORAP) with both time-varying cost functions and coupled equation constraints. For the previous one, based on nonsmooth analysis, a continuous-time distributed discontinuous dynamics with FT convergence is proposed based on an extended zero-gradient-sum method with a local auxiliary subsystem. Different from the existing methods, the proposed algorithm does not require the initial state of each agent to be the optimizer of the local cost function. Moreover, the provided algorithm has a simpler structure without estimating the global information and can be used for TVDO with nonidentical Hessians. Then, an FT convergent distributed dynamics is further obtained for time-varying DORAP by dual transformation. Particularly, the inverse of Hessians is not required from a dual perspective, which reduces the computation complexity significantly. Finally, two numerical examples are conducted to verify the proposed algorithms

Identification and functional characterisation of the promoter of the calcium sensor gene CBL1 from the xerophyte Ammopiptanthus mongolicus

<p>Abstract</p> <p>Background</p> <p><it>CBL1 </it>is a calcium sensor that regulates drought, cold and salt signals in <it>Arabidopsis</it>. Overexpression of <it>CBL1 </it>gene in <it>Arabidopsis </it>and in <it>Ammopiptanthus mongolicus </it>showed different tolerant activities. We are interested in understanding the molecular mechanism of the upstream region of the <it>CBL1 </it>gene of <it>A. mongolicus </it>(<it>AmCBL1</it>). We investigated and characterized the promoter of the <it>AmCBL1 </it>gene, for promoters play a very important role in regulating gene expression in eukaryotes.</p> <p>Results</p> <p>A 1683-bp 5' flanking region was isolated from <it>A. mongolicus</it>. The sequence was identified as <it>AmCBL1 </it>promoter. Analysis of the promoter sequence indicated a 690-bp intron and some basic cis-acting elements were related to various environmental stresses and plant hormones. To identify the functional region of the <it>AmCBL1 </it>promoter, five plant expression vectors fused with the GUS (β-glucuronidase) gene, driven by series deleted fragments of <it>AmCBL1 </it>promoter at different lengths from -1659, -1414, -1048, -296 to -167 bp relative to the transcriptional start site were constructed and transformed into <it>Nicotiana tabacum </it>L. cv. 89. Functional properties of each promoter segment were examined by GUS staining and fluorescence quantitative analyses using at least three single-copy PCR-positive plants of transgenic tobacco, treated with various environmental stresses and plant hormones for different times. We demonstrated that the <it>AmCBL1 </it>promoter was a vascular-specific and multiple-stress-inducible promoter. Our results further imply that the promoter fragment B1S3 possessed sufficient essential cis-acting elements, accounting for vascular-specific and stress-induced expression patterns. It may also indicate that for response to some stresses certain cis-elements are required in tissues outside the region of the B1S3 construct.</p> <p>Conclusions</p> <p>To help resolve uncertainties about the upstream regulatory mechanism of the <it>CBL1 </it>gene in desert plants, we suggest that the function of the <it>AmCBL1 </it>promoter, particularly under conditions of abiotic stress, to be examined for possible usefulness in molecular breeding. Regardless of the outcome, the allocation and relative quantification of the GUS-fusion <it>AmCBL1 </it>promoter segments at transcriptional levels in different tissues under various stresses across separate promoter segments suggests that the <it>AmCBL1 </it>promoter is a phloem-specific and multiple-stress-inducible promoter. These data coupled with the ongoing <it>AmCBL1 </it>5' UTR intron analyses provide a solid foundation for their future use in molecular breeding as new promoters of stress-resistance genes from desert plants.</p

Impact of cropland displacement on the potential crop production in China:a multi-scale analysis

Changes in the amount and location of cropland areas may affect the potential crop production at different spatial scales. However, most studies ignore the impacts of cropland displacement on potential crop production. In many countries, cropland protection policies mainly aim for no loss in cropland area, while there is no restriction on change of cropland location. Taking China as the study area, we analyze the impacts of cropland displacement on potential crop production at four administrative levels during the period 2000 and 2018. At the national level, we find a net decrease in cropland area of 0.81 Mha, while another 19.63 Mha was displaced. The former led to a decrease of 4.20 Mton in potential crop production, while the latter resulted in a decrease of 43.26 Mton as a result of lower quality of the newly cultivated lands. In other words, cropland displacement explains 91% of the total loss in potential crop production at the national scale. However, the contribution of cropland displacement to total change in potential crop production is increasingly smaller at provincial level, municipal level, and county levels. These findings highlight the importance of geographic location on crop production and suggest that cropland policies should consider geographic location in addition to cropland area