This study investigates the constraint provided by greenhouse gas measurements from space on surface fluxes. Imperfect knowledge of the light path through the atmosphere, arising from scattering by ...clouds and aerosols, can create biases in column measurements retrieved from space. To minimize the impact of such biases, ratios of total column retrieved CH4 and CO2 (Xratio) have been used. We apply the ratio inversion method described in to retrievals from the Greenhouse Gases Observing SATellite (GOSAT). The ratio inversion method uses the measured Xratio as a weak constraint on CO2 fluxes. In contrast, the more common approach of inverting proxy CH4 retrievals prescribes atmospheric CO2 fields and optimizes only CH4 fluxes.The TM5–4DVAR (Tracer Transport Model version 5–variational data assimilation system) inverse modeling system is used to simultaneously optimize the fluxes of CH4 and CO2 for 2009 and 2010. The results are compared to proxy inversions using model-derived CO2 mixing ratios (XCO2model) from CarbonTracker and the Monitoring Atmospheric Composition and Climate (MACC) Reanalysis CO2 product. The performance of the inverse models is evaluated using measurements from three aircraft measurement projects.Xratio and XCO2model are compared with TCCON retrievals to quantify the relative importance of errors in these components of the proxy XCH4 retrieval (XCH4proxy). We find that the retrieval errors in Xratio (mean = 0.61 %) are generally larger than the errors in XCO2model (mean = 0.24 and 0.01 % for CarbonTracker and MACC, respectively). On the annual timescale, the CH4 fluxes from the different satellite inversions are generally in agreement with each other, suggesting that errors in XCO2model do not limit the overall accuracy of the CH4 flux estimates. On the seasonal timescale, however, larger differences are found due to uncertainties in XCO2model, particularly over Australia and in the tropics. The ratio method stays closer to the a priori CH4 flux in these regions, because it is capable of simultaneously adjusting the CO2 fluxes. Over tropical South America, comparison to independent measurements shows that CO2 fields derived from the ratio method are less realistic than those used in the proxy method. However, the CH4 fluxes are more realistic, because the impact of unaccounted systematic uncertainties is more evenly distributed between CO2 and CH4. The ratio inversion estimates an enhanced CO2 release from tropical South America during the dry season of 2010, which is in accordance with the findings of and.The performance of the ratio method is encouraging, because despite the added nonlinearity due to the assimilation of Xratio and the significant increase in the degree of freedom by optimizing CO2 fluxes, still consistent results are obtained with respect to other CH4 inversions.
Identifying migration routes and key habitats is critical for the management and conservation of migratory species. Tracking and stable isotope analysis (SIA), particularly of carbon (δ 13 C) and ...nitrogen (δ 15 N), are often used to study animal movements, with SIA particularly useful when animals move through isotopic gradients. Marine turtles are typically highly migratory, moving between nesting and foraging grounds often located 100s-1000s km apart. The flatback turtle Natator depressus is endemic to the Australian continental shelf. Satellite tracking (n = 44) and SIA (n = 33) of females nesting in eastern Queensland, Australia, were used to identify main foraging areas, describe intraspecific variation in the location of foraging areas, and determine if δ 13 C and/or δ 15 N values can be used to identify foraging regions. Although foraging grounds were widely dispersed, tracking identified 3 main foraging regions. SIA agreed with tracking, indicating foraging site fidelity. Generalized linear models and linear discriminant analysis (LDA) were used to estimate how well δ 13 C/δ 15 N and nesting sites can perform as indicators of broad foraging regions and to predict foraging regions for turtles with no tracking data. δ 15 N was a strong predictor of the foraging region. LDA correctly classified the foraging region of 94% of individuals and was suitable to predict foraging regions of untracked individuals. A strong negative linear relationship between turtle δ 15 N and foraging latitude indicates the presence of a δ 15 N isoscape along the eastern Queensland coast. This is the first demonstration of an isoscape for the region, which should be useful for studying and monitoring the habitat use of flatback turtles and other migratory species.
Atmospheric radiocarbon (14C) represents an important observational constraint on emissions of fossil-fuel derived carbon into the atmosphere due to the absence of 14C in fossil fuel reservoirs. The ...high sensitivity and precision that accelerator mass spectrometry (AMS) affords in atmospheric 14C analysis has greatly increased the potential for using such measurements to evaluate bottom-up emissions inventories of fossil fuel CO2 (CO2ff), as well as those for other co-emitted species. Here we use observations of 14CO2 and a series of primary hydrocarbons and combustion tracers from discrete air samples collected between June 2009 and September 2010 at the National Oceanic and Atmospheric Administration Boulder Atmospheric Observatory (BAO; Lat: 40.050° N, Lon: 105.004° W) to derive emission ratios of each species with respect to CO2ff. The BAO tower is situated at the boundary of the Denver metropolitan area to the south and a large industrial and agricultural region to the north and east, making it an ideal location to study the contrasting mix of emissions from the activities in each region. The species considered in this analysis are carbon monoxide (CO), methane (CH4), acetylene (C2H2), benzene (C6H6), and C3–C5 alkanes. We estimate emissions for a subset of these species by using the Vulcan high resolution CO2ff emission data product as a reference. We find that CO is overestimated in the 2008 National Emissions Inventory (NEI08) by a factor of ~2. A close evaluation of the inventory suggests that the ratio of CO emitted per unit fuel burned from on-road gasoline vehicles is likely over-estimated by a factor of 2.5. Using a wind-directional analysis of the data, we find enhanced concentrations of CH4, relative to CO2ff, in air influenced by emissions to the north and east of the BAO tower when compared to air influenced by emissions in the Denver metro region to the south. Along with enhanced CH4, the strongest enhancements of the C3–C5 alkanes are also found in the north and east wind sector, suggesting that both the alkane and CH4 enhancements are sourced from oil and gas fields located to the northeast, though it was not possible to rule out the contribution of non oil and gas CH4 sources.
Abstract We present a measurement of the low-mass quiescent size–mass relation at cosmic noon (1 < z < 3) from the JWST PRIMER and UNCOVER treasury surveys, which highlights two distinct classes of ...quiescent galaxies. While the massive population is well studied at these redshifts, the low-mass end has been previously underexplored due to a lack of observing facilities with sufficient sensitivity and spatial resolution. We select a conservative sample of low-mass quiescent galaxy candidates using rest-frame UVJ colors and specific star formation rate criteria and measure galaxy morphology in both rest-frame UV/optical wavelengths (F150W) and rest-frame near-infrared (F444W). We confirm an unambiguous flattening of the low-mass quiescent size–mass relation, which results from the separation of the quiescent galaxy sample into two distinct populations at log ( M ⋆ / M ⊙ ) ∼ 10.3 : low-mass quiescent galaxies that are notably younger and have disky structures, and massive galaxies consistent with spheroidal morphologies and older median stellar ages. These separate populations imply mass quenching dominates at the massive end while other mechanisms, such as environmental or feedback-driven quenching, form the low-mass end. This stellar mass-dependent slope of the quiescent size–mass relation could also indicate a shift from size growth due to star formation (low masses) to growth via mergers (massive galaxies). The transition mass between these two populations also corresponds with other dramatic changes and characteristic masses in several galaxy evolution scaling relations (e.g., star formation efficiency, dust obscuration, and stellar-to-halo mass ratios), further highlighting the stark dichotomy between low-mass and massive galaxy formation.
Hemp (Cannabis sativa) is a multi-use crop garnering newfound attention from researchers and consumers. While interest has emerged, a lack of substantiated research still exists regarding effects of ...adverse weather events on physiological health and secondary metabolite production of hemp. The aim of this experiment was to assess cold tolerance of hemp using the cultivars ‘FINOLA’ and ‘AutoCBD’. Effects of cultivar, plant age, cold acclimation, frequency of cold treatments, and intensity of cold treatments were all considered in regard to their influence on physiological stress, biomass, and cannabinoid profile. Few effects of sequential cold treatments were noted, and they were not moderated by cold acclimation, which tended to have negative effects across many responses. This detrimental effect of cold acclimation conditions was further observed in decreased total CBD % and total THC % compared to non-acclimated plants. These findings bear consideration when assessing the unpredictability of a changing climate’s effects on the heath and cannabinoid profile of hemp.
Imaging mass spectrometry in transmission geometry Richards, Alicia L.; Lietz, Christopher B.; Wager-Miller, James B. ...
Rapid communications in mass spectrometry,
30 March 2011, Letnik:
25, Številka:
6
Journal Article
Propagation of light beams through scattering or multimode systems may lead to the randomization of the spatial coherence of the light. Although information is not lost, its recovery requires a ...coherent interferometric reconstruction of the original signals, which have been scrambled into the modes of the scattering system. Here we show that we can automatically unscramble optical beams that have been arbitrarily mixed in a multimode waveguide, undoing the scattering and mixing between the spatial modes through a mesh of silicon photonics tuneable beam splitters. Transparent light detectors integrated in a photonic chip are used to directly monitor the evolution of each mode along the mesh, allowing sequential tuning and adaptive individual feedback control of each beam splitter. The entire mesh self-configures automatically through a progressive tuning algorithm and resets itself after significantly perturbing the mixing, without turning off the beams. We demonstrate information recovery by the simultaneous unscrambling, sorting and tracking of four mixed modes, with residual cross-talk of -20 dB between the beams. Circuit partitioning assisted by transparent detectors enables scalability to meshes with a higher port count and to a higher number of modes without a proportionate increase in the control complexity. The principle of self-configuring and self-resetting in optical systems should be applicable in a wide range of optical applications.
Objectives:
We examine the association between perceived discrimination, mental health, social support, and support for violent radicalization (VR) in young adults from three locations across two ...countries: Montréal and Toronto, Canada, and Boston, United States. A secondary goal is to test the moderating role of location.
Methods:
A total of 791 young adults between the ages of 18 and 30, drawn from the Somali Youth longitudinal study and a Canada-based study of college students, participated in the study. We used multivariate linear regression to assess the association between scores on the Radical Intentions Scale (RIS) with demographic characteristics, anxiety, depression, social support, and discrimination.
Results:
In the full sample, discrimination, age, and gender were associated with RIS scores. When we examined moderation effects by location, RIS scores were associated with depression only in Montréal, and with social support (negatively) and discrimination in Toronto. None of the variables were significant in Boston.
Conclusion:
These findings suggest that an understanding of risk and protective factors for support of VR may be context-dependent. Further research should take into consideration local/regional differences.
Transmission electron microscopy characterization of irradiated U-7 wt%Mo dispersion fuel were performed on various U-Mo fuel samples to understand the effect of irradiation parameters (fission ...density, fission rate, and temperature) on the self-organized fission-gas-bubble superlattice that forms in the irradiated U-Mo fuel. The bubble superlattice was seen to form a face centered cubic structure coherent with the host U-7 wt%Mo body-centered cubic structure. At a fission density between 3.0 and 4.5 x 10 super(21) fiss/cm super(3), the superlattice bubbles appear to have reached a saturation size with additional fission gas associated with increasing bumup predominately accumulating along grain boundaries. At a fission density of ~4.5 x 10 super(21) fiss/cm super(3), the U-7 wt%Mo microstructure starts to undergo grain subdivision and can no longer support the ordered bubble superlattice. The sub-divided fuel grains are less than 500 nm in diameter with what appears to be micron-size fission-gas bubbles present on the grain boundaries. Solid fission products typically decorate the inside surface of the micron-sized fission-gas bubbles. Residual superlattice bubbles are seen in areas where fuel grains remain micron sized. Potential mechanisms of the formation and collapse of the bubble superlattice are discussed.
Water uptake is a critical issue for postharvest physiology of cut flowers. After harvest, cut flowers lose access to water from roots and sometimes develop emboli inside the xylem, which can disrupt ...water uptake and undermine flower longevity. The duration of dry storage (desiccation) before flowers are placed in a vase may affect rehydration capability. Despite the appreciated importance of desiccation time on water balance, the duration of desiccation that might cause irreversible damage in Lilium sp. L. is unknown. Therefore, we investigated effects of pre-vase dehydration on water uptake and postharvest quality of cut lilies. Stems of Lilium ‘Nashville’, ‘Santander’, and ‘Sorbonne’ were subjected to 0, 8, 24, or 48 hours of dehydration at 20 °C, then rehydrated in a solution containing 2% sucrose and a biocide. Water uptake in the first 24 hours of rehydration was significantly greater in dehydrated stems than in control (0 hour) stems. Although dehydration treatments increased water uptake in the first 24 hours after rehydration, total water uptake in dehydrated stems over the ensuing 9- to 10-day vase period was significantly less than in controls. In the vase, 48 hours of dehydration reduced the total water uptake in ‘Nashville’ by 27% and in ‘Sorbonne’ by 48%. Individual flower life and stem vase life were not affected significantly by dehydration treatment; however, ‘Sorbonne’ stems dehydrated for 24 or 48 hours had smaller flowers than controls and those that underwent the 8-hour dehydration treatment. ‘Nashville’ stems dehydrated for 24 hours showed visible leaf yellowing 3 days earlier than controls; ‘Sorbonne’ dehydrated for 48 hours showed leaf yellowing 2 days earlier. We conclude cut lilies have an ability to recover partially from significant dehydration and can restore water uptake initially, but pre-vase dehydration reduces total water uptake and affects some postharvest attributes negatively.
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