209 research outputs found

    Monitoring lianas from space: using Sentinel-2 imagery to observe liana removal in logged tropical forests

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    Liana removal – the cutting of over-abundant woody climbing plants (lianas) – has the potential to substantially increase tree growth and biomass accumulation across millions of hectares of degraded tropical forest. Satellite imagery could provide data capable of observing the effect of liana removal on the forest canopy, enabling the large-scale monitoring and validation of liana removal, which remains a key hurdle to its widespread implementation. Using a 320-ha liana removal experiment in Sabah, Malaysian Borneo, we tested whether a time series of Sentinel-2 images could observe the canopy signature of liana removal. Calculating a range of metrics derived from the Normalized Burn Ratio – a vegetation index based on spectral reflectance that differentiates leaf from non-leaf – we quantified satellite-derived canopy disturbance and fragmentation across a range of liana removal intensities and examined how canopy disturbance changed in the 12-months following removal treatments. We find that liana removal significantly increases canopy disturbance and fragmentation metrics one month after removal, with partial removal having a smaller effect than complete removal. The impact of liana removal on the canopy metrics declined over time, with measures of canopy disturbance and fragmentation largely indistinguishable from control forest within 12-months of treatment. Our findings evidence that freely available satellite imagery can be used to efficiently monitor large-scale liana removal applied at a range of intensities and suggest that partial liana removal could significantly reduce canopy disturbance of this restoration method

    Філософія популізму як варіант сучасної філософії

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    We have previously reported on the functional interaction of Lipid II with human alpha-defensins, a class of antimicrobial peptides. Lipid II is an essential precursor for bacterial cell wall biosynthesis and an ideal and validated target for natural antibiotic compounds. Using a combination of structural, functional and in silico analyses, we present here the molecular basis for defensin-Lipid II binding. Based on the complex of Lipid II with Human Neutrophil peptide-1, we could identify and characterize chemically diverse low-molecular weight compounds that mimic the interactions between HNP-1 and Lipid II. Lead compound BAS00127538 was further characterized structurally and functionally; it specifically interacts with the N-acetyl muramic acid moiety and isoprenyl tail of Lipid II, targets cell wall synthesis and was protective in an in vivo model for sepsis. For the first time, we have identified and characterized low molecular weight synthetic compounds that target Lipid II with high specificity and affinity. Optimization of these compounds may allow for their development as novel, next generation therapeutic agents for the treatment of Gram-positive pathogenic infections

    Impact of alcohol use disorder severity on human immunodeficiency virus (HIV) viral suppression and CD4 count in three international cohorts of people with HIV.

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    Alcohol use has been linked to worse human immunodeficiency virus (HIV) immunologic/virologic outcomes, yet few studies have explored the effects of alcohol use disorder (AUD). This study assessed whether AUD severity is associated with HIV viral suppression and CD4 count in the three cohorts of the Uganda Russia Boston Alcohol Network for Alcohol Research Collaboration on HIV/AIDS (URBAN ARCH) Consortium. People with HIV (PWH) in Uganda (n = 301), Russia (n = 400), and Boston (n = 251), selected in-part based on their alcohol use, were included in analyses. Logistic and linear regressions were used to assess the cross-sectional associations between AUD severity (number of DSM-5 diagnostic criteria) and (1) HIV viral suppression, and (2) CD4 count (cells/mm <sup>3</sup> ) adjusting for covariates. Analyses were conducted separately by site. The proportion of females was 51% (Uganda), 34% (Russia), and 33% (Boston); mean age (SD) was 40.7 (9.6), 38.6 (6.3), and 52.1 (10.5), respectively. All participants in Uganda and all but 27% in Russia and 5% in Boston were on antiretroviral therapy. In Uganda, 32% met criteria for AUD, 92% in Russia, and 43% in Boston. The mean (SD) number of AUD criteria was 1.6 (2.4) in Uganda, 5.6 (3.3) in Russia, and 2.4 (3.1) in Boston. Most participants had HIV viral suppression (Uganda 92%, Russia 57%, Boston 87%); median (IQR) CD4 count was 673 (506, 866), 351 (201, 542), and 591 (387, 881), respectively. In adjusted models, there were no associations between AUD severity and HIV viral suppression: adjusted odds ratios (AOR) (95%CI) per 1 additional AUD criterion in Uganda was 1.08 (0.87, 1.33); Russia 0.98 (0.92, 1.04); and Boston 0.95 (0.84, 1.08) or CD4 count: mean difference (95%CI) per 1 additional criterion: 5.78 (-7.47, 19.03), -3.23 (-10.91, 4.44), and -8.18 (-24.72, 8.35), respectively. In three cohorts of PWH, AUD severity was not associated with HIV viral suppression or CD4 count. PWH with AUD in the current era of antiretroviral therapy can achieve virologic control

    Engineering of B800 bacteriochlorophyll binding site specificity in the Rhodobacter sphaeroides LH2 antenna.

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    The light-harvesting 2 complex (LH2) of the purple phototrophic bacterium Rhodobacter sphaeroides is a highly efficient, light-harvesting antenna that allows growth under a wide-range of light intensities. In order to expand the spectral range of this antenna complex, we first used a series of competition assays to measure the capacity of the non-native pigments 3-acetyl chlorophyll (Chl) a, Chl d, Chl f or bacteriochlorophyll (BChl) b to replace native BChl a in the B800 binding site of LH2. We then adjusted the B800 site and systematically assessed the binding of non-native pigments. We find that Arg-10 of the LH2 β polypeptide plays a crucial role in binding specificity, by providing a hydrogen-bond to the 3-acetyl group of native and non-native pigments. Reconstituted LH2 complexes harbouring the series of (B)Chls were examined by transient absorption and steady-state fluorescence spectroscopies. Although slowed 10-fold to ~6 ps, energy transfer from Chl a to B850 BChl a remained highly efficient. We measured faster energy-transfer time constants for Chl d (3.5 ps) and Chl f (2.7 ps), which have red-shifted absorption maxima compared to Chl a. BChl b, red-shifted from the native BChl a, gave extremely rapid (≤0.1 ps) transfer. These results show that modified LH2 complexes, combined with engineered (B)Chl biosynthesis pathways in vivo, have potential for retaining high efficiency whilst acquiring increased spectral range

    A framework for orthology assignment from gene rearrangement data

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    Abstract. Gene rearrangements have successfully been used in phylogenetic reconstruction and comparative genomics, but usually under the assumption that all genomes have the same gene content and that no gene is duplicated. While these assumptions allow one to work with organellar genomes, they are too restrictive when comparing nuclear genomes. The main challenge is how to deal with gene families, specifically, how to identify orthologs. While searching for orthologies is a common task in computational biology, it is usually done using sequence data. We approach that problem using gene rearrangement data, provide an optimization framework in which to phrase the problem, and present some preliminary theoretical results.

    Spatial regulation of the glycocalyx component podocalyxin is a switch for prometastatic function

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    The glycocalyx component and sialomucin podocalyxin (PODXL) is required for normal tissue development by promoting apical membranes to form between cells, triggering lumen formation. Elevated PODXL expression is also associated with metastasis and poor clinical outcome in multiple tumor types. How PODXL presents this duality in effect remains unknown. We identify an unexpected function of PODXL as a decoy receptor for galectin-3 (GAL3), whereby the PODXL-GAL3 interaction releases GAL3 repression of integrin-based invasion. Differential cortical targeting of PODXL, regulated by ubiquitination, is the molecular mechanism controlling alternate fates. Both PODXL high and low surface levels occur in parallel subpopulations within cancer cells. Orthotopic intraprostatic xenograft of PODXL-manipulated cells or those with different surface levels of PODXL define that this axis controls metastasis in vivo. Clinically, interplay between PODXL-GAL3 stratifies prostate cancer patients with poor outcome. Our studies define the molecular mechanisms and context in which PODXL promotes invasion and metastasis

    Geologic framework of the 2005 Keathley Canyon gas hydrate research well, northern Gulf of Mexico

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    This paper is not subject to U.S. copyright. The definitive version was published in Marine and Petroleum Geology 25 (2008): 906-918, doi:10.1016/j.marpetgeo.2008.01.012.The Keathley Canyon sites drilled in 2005 by the Chevron Joint Industry Project are located along the southeastern edge of an intraslope minibasin (Casey basin) in the northern Gulf of Mexico at 1335 m water depth. Around the drill sites, a grid of 2D high-resolution multichannel seismic data designed to image depths down to at least 1000 m sub-bottom reveals 7 unconformities and disconformities that, with the seafloor, bound 7 identifiable seismic stratigraphic units. A major disconformity in the middle of the units stands out for its angular baselapping geometry. From these data, three episodes of sedimentary deposition and deformation are inferred. The oldest episode consists of fine-grained muds deposited during a period of relative stability in the basin (units e, f, and g). Both the BSR and inferred gas hydrate occur within these older units. The gas hydrate occurs in near-vertical fractures. A second episode (units c and d) involved large vertical displacements associated with infilling and ponding of sediment. This second interval corresponds to deposition of intercalated fine and coarse-grained material that was recovered in the drill hole that penetrated the thin edges of the regionally much thicker units. The final episode of deposition (units a and b) occurred during more subdued vertical motions. Hemipelagic drape (unit a) characterizes the modern seafloor. The present-day Casey basin is mostly filled. Its sill is part of a subsiding graben structure that is only 10–20 m shallower than the deepest point in the basin, indicating that gravity-driven transport would mostly bypass the basin. Contemporary faulting along the basin margins has selectively reactivated an older group of faults. The intercalated sand and mud deposits of units c and d are tentatively correlated with Late Pleistocene deposition derived from the western shelf-edge delta/depocenter of the Mississippi River, which was probably most active from 320 ka to 70 ka [Winker, C.D., Booth, J., 2000. Sedimentary dynamics of the salt-dominated continental slope, Gulf of Mexico: integration of observations from the seafloor, near-surface, and deep subsurface. In: Proceedings of the GCSSEPM Foundation 20th Annual Research Conference, Deep-water Reservoirs of the World, pp. 1059–1086]. The presence of sand within the gas hydrate stability zone (in units c and d) is not sufficient to concentrate gas hydrate even though dispersed gas hydrate occurs deeper in the fractured mud/clay-rich sections of units e and f.Partial support for the field and interpretive aspects of this project were provided by the Department of Energy, National Energy Technology Lab (NETL)

    Passive shielding in CUORE

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    The nature of neutrino mass is one of the friontier problems of fundamental physics. Neutrinoless Double Beta Decay (0νDBD) is a powerful tool to investigate the mass hierarchy and possible extensions of the Standard Model. CUORE is a 1‐Ton next generation experiment, made of 1000 Te bolometers, aiming at reaching a background of 0.01 (possibly 0.001) counts keV −1 kg −1 y −1 and therefore a mass sensitivity of few tens of meV The background contribution due to environmental neutrons, muon‐induced neutrons in the shieldings and external gamma is discussed

    CUORE Experiment: The Search for Neutrrinoless Double Beta Decay

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    The main purpose of the Cryogenic Underground Observatory for Rare Events (CUORE) experiment is the search for the Neutrinoless Double Beta Decay (0νDBD) of n130Te reaching a sensitivity on Majorana mass better than 50 meV. Cuoricino represents not only the first stage of CUORE, but also the most massive 0νDBD experiment presently running. Present results and future planning of these experiments will be described in the paper
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