71 research outputs found

    Revisit the performance of MODIS and VIIRS leaf area index products from the perspective of time-series stability

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    As an essential vegetation structural parameter, leaf area index (LAI) is involved in many critical biochemical processes, such as photosynthesis, respiration, and precipitation interception. The MODerate resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imager Radiometer Suite (VIIRS) LAI sequence products have long supported various global climate, biogeochemistry, and energy flux research. These applications all rely on the accuracy of the product’s long time series. However, uncontrolled interferences (e.g., adverse observation conditions and sensor uncertainties) potentially introduce substantial uncertainties to time series in product applications. As one of the most sensitive areas in response to global climate change, the Tibet Plateau (TP) has been treated as a crucial testing ground for thousands of studies on vegetation. To ensure the credibility of the studies arising from MODIS/VIIRSLAI products, the temporal quality uncertainties of data need to be clarified. This article proposed a method to revisit the temporal stability of the MODIS (MOD and MYD) and VIIRS (VNP) LAI in the TP, expecting to provide useful information for better accounting for the uncertainties in this area. Results show that the MODIS and VIIRS LAI were relatively stable in time series and available to be used continuously, among which the temporal quality of the MODIS LAI was the most stable. Moreover, the MODIS and VIIRS LAI products performed similarly in both time-series stability and time-series anomaly distribution, magnitudes and fluctuations. The time-series stability evaluation strategy applied to the MODIS and VIIRS LAI can also be employed to other remote sensing products.Published versio

    Multiplatform Analysis of 12 Cancer Types Reveals Molecular Classification within and across Tissues of Origin

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    Recent genomic analyses of pathologically-defined tumor types identify “within-a-tissue” disease subtypes. However, the extent to which genomic signatures are shared across tissues is still unclear. We performed an integrative analysis using five genome-wide platforms and one proteomic platform on 3,527 specimens from 12 cancer types, revealing a unified classification into 11 major subtypes. Five subtypes were nearly identical to their tissue-of-origin counterparts, but several distinct cancer types were found to converge into common subtypes. Lung squamous, head & neck, and a subset of bladder cancers coalesced into one subtype typified by TP53 alterations, TP63 amplifications, and high expression of immune and proliferation pathway genes. Of note, bladder cancers split into three pan-cancer subtypes. The multi-platform classification, while correlated with tissue-of-origin, provides independent information for predicting clinical outcomes. All datasets are available for data-mining from a unified resource to support further biological discoveries and insights into novel therapeutic strategies

    Effect of No-Tillage Management on Soil Organic Matter and Net Greenhouse Gas Fluxes in a Rice-Oilseed Rape Cropping System

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    No-tillage (NT) management is considered a leading approach for sustaining crop production and improving soil and environmental quality. Based on a long-term no-tillage experiment in a rice–oilseed rape cropping system, we examined differences in soil organic matter (SOM), soil microbial carbon (C) and nitrogen (N) content, and methane (CH4) and carbon dioxide (CO2) fluxes between NT and conventional tillage (CT) management. SOM under NT was 21.0 g kg–1, and a significant difference was detected between 2004 and 2016. SOM increased under NT and CT by averages of 0.60 and 0.32 g kg–1 year–1, respectively. Soil microbial C and N content were higher under CT than under NT. However, soil C:N ratios under NT were 17.4 and 9.7% higher than the CT, respectively, whereas soil microbial C:N ratios under NT were on average 9.47 and 9.70% higher. In addition, about 70% of CO2 net uptake and over 99% of net CH4 emissions occurred during the rice season in May–September in the rice–oilseed rape cropping system. Annual cumulative CH4 and daytime net ecosystem CO2 exchange (NEE) under NT was 1813.9 g CO2 equiv. m–2, 10.8% higher than that under CT. Our results suggest that a higher soil microbial C:N ratio and NEE (CH4 and daytime CO2) could contribute to increasing SOM/C in the surface soil under NT management

    Data from: Detection of somatic epigenetic variation in Norway spruce via targeted bisulfite sequencing

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    Epigenetic mechanisms represent a possible mechanism for achieving a rapid response of long‐lived trees to changing environmental conditions. However, our knowledge on plant epigenetics is largely limited to a few model species. With increasing availability of genomic resources for many tree species, it is now possible to adopt approaches from model species that permit to obtain single‐base pair resolution data on methylation at a reasonable cost. Here, we used targeted bisulfite sequencing (TBS) to study methylation patterns in the conifer species Norway spruce (Picea abies). To circumvent the challenge of disentangling epigenetic and genetic differences, we focused on four clone pairs, where clone members were growing in different climatic conditions for 24 years. We targeted >26.000 genes using TBS and determined the performance and reproducibility of this approach. We characterized gene body methylation and compared methylation patterns between environments. We found highly comparable capture efficiency and coverage across libraries. Methylation levels were relatively constant across gene bodies, with 21.3 ± 0.3%, 11.0 ± 0.4% and 1.3 ± 0.2% in the CG, CHG, and CHH context, respectively. The variance in methylation profiles did not reveal consistent changes between environments, yet we could identify 334 differentially methylated positions (DMPs) between environments. This supports that changes in methylation patterns are a possible pathway for a plant to respond to environmental change. After this successful application of TBS in Norway spruce, we are confident that this approach can contribute to broaden our knowledge of methylation patterns in natural tree populations

    Fabrication of amorphous Al2O3 optical film with various refractive index and low surface roughness

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    Alumina(Al _2 O _3 ) thin film has been widely used in many applications due to its excellent properties, especially in optical films and semiconductor industries. Refractive index, amorphous property and surface roughness are essential parameters related to its applications. In this study, the fabrication method of preparing various refractive index Al _2 O _3 optical films was proposed. The Al _2 O _3 optical films were deposited at room temperature by electron beam evaporation(EBE) technique. The effects of deposition rate and post-annealed temperature on refractive index, vibration peak of molecular and atom, amorphous property and surface roughness were investigated. Refractive index ranging from 1.519 to 1.627 was realized by EBE method at different deposition rates and different post-annealed temperatures. The variable refractive index was very important in adjusting half-width of reflector band. Meanwhile, analysis showed that the suitable post-annealed temperature could not exceed 400 °C. In short, this work provided an effective approach to fabricate amorphous Al _2 O _3 optical film, which was pretty important in its applications in UV antireflection films and blue light reflection films

    A new phylogeny for the genus Picea from plastid, mitochondrial, and nuclear sequences

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    Studies over the past ten years have shown that the crown groups of most conifer genera are only about 15-25 Ma old. The genus Picea (spruces, Pinaceae), with around 35 species, appears to be no exception. In addition, molecular studies of co-existing spruce species have demonstrated frequent introgression. Perhaps not surprisingly therefore previous phylogenetic studies of species relationships in Picea, based mostly on plastid sequences, suffered from poor statistical support. We therefore generated mitochondria], nuclear, and further plastid DNA sequences from carefully sourced material, striking a balance between alignability with outgroups and phylogenetic signal content. Motif duplications in mitochondria] introns were treated as characters in a stochastic Dollo model; molecular clock models were calibrated with fossils; and ancestral ranges were inferred under maximum likelihood. In agreement with previous findings, Picea diverged from its sister clade 180 million years ago (Ma), and the most recent common ancestor of today's spruces dates to 28 Ma. Different from previous analyses though, we find a large Asian clade, an American clade, and a Eurasian clade. Two expansions occurred from Asia to North America and several between Asia and Europe. Chinese P. brachytyla, American P. engelmannii, and Norway spruce, P. abies, are not monophyletic, and North America has ten, not eight species. Divergence times imply that Pleistocene refugia are unlikely to be the full explanation for the relationships between the European species and their East Asian relatives. Thus, northern Norway spruce may be part of an Asian species complex that diverged from the southern Norway spruce lineage in the Upper Miocene, some 6 Ma, which can explain the deep genetic gap noted in phylogeographic studies of Norway spruce. The large effective population sizes of spruces, and incomplete lineage sorting during speciation, mean that the interspecific relationships within each of the geographic clades require further studies, especially based on genomic information and population genetic data
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