475 research outputs found

    Potential of MODIS EVI and surface temperature for directly estimating per-pixel ecosystem C fluxes

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    We tested the potential of estimating per-pixel gross primary production (GPP) directly from the MODIS enhanced vegetation index (EVI) and respiration directly from MODIS surface temperature (MOD11). Carbon flux data were obtained from 10 eddy covariance tower sites representing a wide range of North American vegetations. The correlation between across-site tower GPP and EVI was comparable (r = 0.77) to that between tower GPP and MOD17-GPP (r = 0.73), suggesting that EVI could be used to provide reasonably accurate direct estimates of GPP on a truly per-pixel basis. There was also a strong relationship (r2 = 0.67) between respiration and surface temperature of dense vegetation, suggesting that estimation of net ecosystem exchange (NEE) may be possible with relatively simple pixel based models, at least for some vegetation types

    Detecting Recent Crop Phenology Dynamics in Corn and Soybean Cropping Systems of Kentucky

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    Accurate phenological information is essential for monitoring crop development, predicting crop yield, and enhancing resilience to cope with climate change. This study employed a curve-change-based dynamic threshold approach on NDVI (Normalized Differential Vegetation Index) time series to detect the planting and harvesting dates for corn and soybean in Kentucky, a typical climatic transition zone, from 2000 to 2018. We compared satellite-based estimates with ground observations and performed trend analyses of crop phenological stages over the study period to analyze their relationships with climate change and crop yields. Our results showed that corn and soybean planting dates were delayed by 0.01 and 0.07 days/year, respectively. Corn harvesting dates were also delayed at a rate of 0.67 days/year, while advanced soybean harvesting occurred at a rate of 0.05 days/year. The growing season length has increased considerably at a rate of 0.66 days/year for corn and was shortened by 0.12 days/year for soybean. Sensitivity analysis showed that planting dates were more sensitive to the early season temperature, while harvesting dates were significantly correlated with temperature over the entire growing season. In terms of the changing climatic factors, only the increased summer precipitation was statistically related to the delayed corn harvesting dates in Kentucky. Further analysis showed that the increased corn yield was significantly correlated with the delayed harvesting dates (1.37 Bu/acre per day) and extended growing season length (1.67 Bu/acre per day). Our results suggested that seasonal climate change (e.g., summer precipitation) was the main factor influencing crop phenological trends, particularly corn harvesting in Kentucky over the study period. We also highlighted the critical role of changing crop phenology in constraining crop production, which needs further efforts for optimizing crop management practices

    National Forest Funds: mechanisms adapted to today’s challenges - Overview of the situation of 4 Southern and Eastern Mediterranean countries: Lebanon, Morocco, Tunisia and Turkey

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    National Forest Funds (NFFs) are mechanisms that could be adapted to address today’s many challenges: their role as funding instruments, they can also act as catalysts to harness international funding such as the REDD+. If properly set, an NFF can also be an efficient tool to rationalize the use of these funds in a context of good governance and to ensure, for example, a redistribution to environmental service providers such as through payments for ecosystem services. Well equipped to deal with global changes, such as increasing anthropogenic stress with poverty in Southern and Eastern Mediterranean countries, which increase wooded areas degradation and withering and desertification due to climate change. An overview of the situation of 4 Southern and Eastern Mediterranean countries (Lebanon, Morocco, Tunisia, and Turkey) was compiled in order to take stock of the context and of the purpose of the implementation or the reinforcement of a national forest fund in terms of development opportunities, structuring, cross sectoral approach, objectives and schedule

    Les Fonds forestiers nationaux : des mĂ©canismes adaptĂ©s aux dĂ©fis d’aujourd’hui - Tour d’horizon de la situation de quatre pays du sud et de l’est de la MĂ©diterranĂ©e : Liban, Maroc, Tunisie et Turquie

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    Les fonds forestiers nationaux (FFN) sont des mĂ©canismes adaptĂ©s aux dĂ©fis d’aujourd’hui : en plus d’ĂȘtre un instrument de financement, ils peuvent Ă©galement ĂȘtre un catalyseur en appelant des financements internationaux tels que la REDD+ par exemple. Correctement habilitĂ©, un FFN peut Ă©galement ĂȘtre un outil efficient pour rationaliser l’utilisation des fonds dans le cadre d’une bonne gouvernance et assurer par exemple une redistribution vers les fournisseurs des services environnementaux dans le cadre de mĂ©canismes de paiements pour services Ă©cosystĂ©miques. Autant d’atouts pour mieux faire face aux changements globaux, tels que les pressions anthropiques croissantes et les phĂ©nomĂšnes de pauvretĂ© dans les pays du sud et de l’est de la MĂ©diterranĂ©e, qui accroissent les dĂ©gradations aux espaces boisĂ©s mais Ă©galement les phĂ©nomĂšnes de dĂ©pĂ©rissements et de dĂ©sertification inhĂ©rents au changement climatique. Un tour d’horizon de la situation de quatre pays du sud et de l’est de la MĂ©diterranĂ©e (Liban, Maroc, Tunisie et Turquie) est rĂ©alisĂ© afin de faire le point sur le contexte dans chaque pays et l’intĂ©rĂȘt de la mise en place ou du renforcement d’un fonds forestier national en termes d’opportunitĂ©s de dĂ©veloppement, de structuration, d’approche intersectorielle, d’objectifs et de calendrier

    Foldamers Reveal and Validate Therapeutic Targets Associated with Toxic α-Synuclein Self-Assembly

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    Parkinson’s disease (PD) is a progressive neurodegenerative disorder for which there is no successful prevention or intervention. The pathological hallmark for PD involves the self-assembly of functional Alpha-Synuclein (αS) into non-functional amyloid structures. One of the potential therapeutic interventions against PD is the effective inhibition of αS aggregation. However, the bottleneck towards achieving this goal is the identification of αS domains/sequences that are essential for aggregation. Using a protein mimetic approach, we have identified αS sequences-based targets that are essential for aggregation and will have significant therapeutic implications. An extensive array of in vitro, ex vivo, and in vivo assays is utilized to validate αS sequences and their structural characteristics that are essential for aggregation and propagation of PD phenotypes. The study aids in developing significant mechanistic and therapeutic insights into various facets of αS aggregation, which will pave the way for effective treatments for PD

    On the use of MODIS EVI to assess gross primary productivity of North American ecosystems

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    [1] Carbon flux models based on light use efficiency (LUE), such as the MOD17 algorithm, have proved difficult to parameterize because of uncertainties in the LUE term, which is usually estimated from meteorological variables available only at large spatial scales. In search of simpler models based entirely on remote‐sensing data, we examined direct relationships between the enhanced vegetation index (EVI) and gross primary productivity (GPP) measured at nine eddy covariance flux tower sites across North America. When data from the winter period of inactive photosynthesis were excluded, the overall relationship between EVI and tower GPP was better than that between MOD17 GPP and tower GPP. However, the EVI/GPP relationships vary between sites. Correlations between EVI and GPP were generally greater for deciduous than for evergreen sites. However, this correlation declined substantially only for sites with the smallest seasonal variation in EVI, suggesting that this relationship can be used for all but the most evergreen sites. Within sites dominated by either evergreen or deciduous species, seasonal variation in EVI was best explained by the severity of summer drought. Our results demonstrate that EVI alone can provide estimates of GPP that are as good as, if not better than, current versions of the MOD17 algorithm for many sites during the active period of photosynthesis. Preliminary data suggest that inclusion of other remote‐sensing products in addition to EVI, such as the MODIS land surface temperature (LST), may result in more robust models of carbon balance based entirely on remote‐sensing data

    Galectin-1 Deactivates Classically Activated Microglia and Protects from Inflammation-Induced Neurodegeneration

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    SummaryInflammation-mediated neurodegeneration occurs in the acute and the chronic phases of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Classically activated (M1) microglia are key players mediating this process. Here, we identified Galectin-1 (Gal1), an endogenous glycan-binding protein, as a pivotal regulator of M1 microglial activation that targets the activation of p38MAPK-, CREB-, and NF-ÎșB-dependent signaling pathways and hierarchically suppresses downstream proinflammatory mediators, such as iNOS, TNF, and CCL2. Gal1 bound to core 2 O-glycans on CD45, favoring retention of this glycoprotein on the microglial cell surface and augmenting its phosphatase activity and inhibitory function. Gal1 was highly expressed in the acute phase of EAE, and its targeted deletion resulted in pronounced inflammation-induced neurodegeneration. Adoptive transfer of Gal1-secreting astrocytes or administration of recombinant Gal1 suppressed EAE through mechanisms involving microglial deactivation. Thus, Gal1-glycan interactions are essential in tempering microglial activation, brain inflammation, and neurodegeneration, with critical therapeutic implications for MS

    Building block libraries and structural considerations in the self-assembly of polyoxometalate and polyoxothiometalate systems

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    Inorganic metal-oxide clusters form a class of compounds that are unique in their topological and electronic versatility and are becoming increasingly more important in a variety of applications. Namely, Polyoxometalates (POMs) have shown an unmatched range of physical properties and the ability to form structures that can bridge several length scales. The formation of these molecular clusters is often ambiguous and is governed by self-assembly processes that limit our ability to rationally design such molecules. However, recent years have shown that by considering new building block principles the design and discovery of novel complex clusters is aiding our understanding of this process. Now with current progress in thiometalate chemistry, specifically polyoxothiometalates (POTM), the field of inorganic molecular clusters has further diversified allowing for the targeted development of molecules with specific functionality. This chapter discusses the main differences between POM and POTM systems and how this affects synthetic methodologies and reactivities. We will illustrate how careful structural considerations can lead to the generation of novel building blocks and further deepen our understanding of complex systems

    Mapping a Novel Black Spot Resistance Locus in the Climbing Rose Brite Eyesℱ (‘RADbrite’)

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    Rose black spot, caused by Diplocarpon rosae, is one of the most devastating foliar diseases of cultivated roses (Rosa spp.). The globally distributed pathogen has the potential to cause large economic losses in the outdoor cultivation of roses. Fungicides are the primary method to manage the disease, but are often viewed unfavorably by home gardeners due to potential environmental and health impacts. As such, rose cultivars with genetic resistance to black spot are highly desired. The tetraploid climbing rose Brite EyesTM (‘RADbrite’) is known for its resistance to black spot. To better characterize the resistance present in Brite EyesTM, phenotyping was conducted on a 94 individual F1 population developed by crossing Brite EyesTM to the susceptible tetraploid rose ‘Morden Blush’. Brite EyesTM was resistant to all D. rosae races evaluated except for race 12. The progeny were either resistant or susceptible to all races (2, 3, 8, 9, 10, 11, and 13) evaluated. The segregation ratio was 1:1 (χ2 = 0.3830, P = 0.5360) suggesting resistance is conferred by a single locus. The roses were genotyped with the WagRhSNP 68K Axiom array and the ‘polymapR’ package was used to construct a map. A single resistance locus (Rdr4) was identified on the long arm of chromosome 5 homoeolog 4. Three resistance loci have been previously identified (Rdr1, Rdr2, and Rdr3). Both Rdr1 and Rdr2 are located on a chromosome 1 homoeolog. The chromosomal location of Rdr3 is unknown, however, races 3 and 9 are virulent on Rdr3. Rdr4 is either a novel gene or an allele of Rdr3 as it provides resistance to races 3 and 9. Due to its broad resistance, Rdr4 is an excellent gene to introgress into new rose cultivars

    Probing Mechanical Properties of Graphene with Raman Spectroscopy

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    The use of Raman scattering techniques to study the mechanical properties of graphene films is reviewed here. The determination of Gruneisen parameters of suspended graphene sheets under uni- and bi-axial strain is discussed and the values are compared to theoretical predictions. The effects of the graphene-substrate interaction on strain and to the temperature evolution of the graphene Raman spectra are discussed. Finally, the relation between mechanical and thermal properties is presented along with the characterization of thermal properties of graphene with Raman spectroscopy.Comment: To appear in the Journal of Materials Scienc
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