Isoprene photochemistry over the Amazon rainforest Liu, Yingjun; Brito, Joel; Dorris, Matthew R. ...
Proceedings of the National Academy of Sciences - PNAS,
05/2016, Letnik:
113, Številka:
22
Journal Article
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Isoprene photooxidation is a major driver of atmospheric chemistry over forested regions. Isoprene reacts with hydroxyl radicals (OH) and molecular oxygen to produce isoprene peroxy radicals ...(ISOPOO). These radicals can react with hydroperoxyl radicals (HO₂) to dominantly produce hydroxyhydroperoxides (ISOPOOH). They can also react with nitric oxide (NO) to largely produce methyl vinyl ketone (MVK) and methacrolein (MACR). Unimolecular isomerization and bimolecular reactions with organic peroxy radicals are also possible. There is uncertainty about the relative importance of each of these pathways in the atmosphere and possible changes because of anthropogenic pollution. Herein, measurements of ISOPOOH and MVK + MACR concentrations are reported over the central region of the Amazon basin during the wet season. The research site, downwind of an urban region, intercepted both background and polluted air masses during the GoAmazon2014/5 Experiment. Under background conditions, the confidence interval for the ratio of the ISOPOOH concentration to that of MVK + MACR spanned 0.4–0.6. This result implies a ratio of the reaction rate of ISOPOO with HO₂ to that with NO of approximately unity. A value of unity is significantly smaller than simulated at present by global chemical transport models for this important, nominally low-NO, forested region of Earth. Under polluted conditions, when the concentrations of reactive nitrogen compounds were high (>1 ppb), ISOPOOH concentrations dropped below the instrumental detection limit (<60 ppt). This abrupt shift in isoprene photooxidation, sparked by human activities, speaks to ongoing and possible future changes in the photochemistry active over the Amazon rainforest.
Dengue virus (DENV) is estimated to infect 390 million people annually. However, few host factors that alter disease severity are known. Malnutrition, defined as both over- and undernutrition, is a ...growing problem worldwide and has long been linked to dengue disease severity by epidemiological and anecdotal observations. Accordingly, we sought to establish a mouse model to assess the impact of nutritional status on DENV disease severity.
Using transiently immunocompromised mice, we established a model of mild dengue disease with measurable viremia. We then applied it to study the effects of healthy weight, obese, and low-protein diets representing normal, over-, and undernutrition, respectively. Upon infection with DENV serotype 2, obese mice experienced more severe morbidity in the form of weight loss and thrombocytopenia compared to healthy weight groups. Additionally, obesity altered cytokine expression following DENV infection. Although low protein-fed mice did not lose significant weight after DENV2 infection, they also experienced a reduction in platelets as well as increased spleen pathology and viral titers.
Our results indicate that obese or undernourished mice incur greater disease severity after DENV infection. These studies establish a role for nutritional status in DENV disease severity.
The biophysical details of how transcription factors and other proteins interact with RNA polymerase are of great interest as they represent the nexus of how structure and function interact to ...regulate gene expression in the cell. We used an in vitro microfluidic approach to map interactions between a set of ninety proteins, over a third of which are transcription factors, and each of the four subunits of E. coli RNA polymerase, and we compared our results to those of previous large-scale studies. We detected interactions between RNA polymerase and transcription factors that earlier high-throughput screens missed; our results suggest that such interactions can occur without DNA mediation more commonly than previously appreciated.
This article provides a comparative analysis of the opening sessions of Prime Minister's Questions (PMQs) for the last five Prime Ministers in order to test a general perception that PMQs has become ...increasingly a focal point for shallow political point scoring rather than serious prime ministerial scrutiny. Our data appear to confirm that PMQs has become both rowdier and increasingly dominated by the main party leaders. It also indicates that Prime Ministers are increasingly expected to be able to respond to a wider range of questions, female MPs are as likely to ask helpful questions but less likely to ask unanswerable questions than male counterparts, and MPs are less likely to ask helpful questions and more likely to ask unanswerable questions the longer their parliamentary tenure. More surprisingly perhaps, our findings also suggest that, at the beginning of their premierships at least, Thatcher and Brown appear the most accomplished in terms of the fullness of their answers, and Blair and Cameron the least accomplished.
Purpose
Real‐world data for observational research commonly require formatting and cleaning prior to analysis. Data preparation steps are rarely reported adequately and are likely to vary between ...research groups. Variation in methodology could potentially affect study outcomes. This study aimed to develop a framework to define and document drug data preparation and to examine the impact of different assumptions on results.
Methods
An algorithm for processing prescription data was developed and tested using data from the Clinical Practice Research Datalink (CPRD). The impact of varying assumptions was examined by estimating the association between 2 exemplar medications (oral hypoglycaemic drugs and glucocorticoids) and cardiovascular events after preparing multiple datasets derived from the same source prescription data. Each dataset was analysed using Cox proportional hazards modelling.
Results
The algorithm included 10 decision nodes and 54 possible unique assumptions. Over 11 000 possible pathways through the algorithm were identified. In both exemplar studies, similar hazard ratios and standard errors were found for the majority of pathways; however, certain assumptions had a greater influence on results. For example, in the hypoglycaemic analysis, choosing a different variable to define prescription end date altered the hazard ratios (95% confidence intervals) from 1.77 (1.56‐2.00) to 2.83 (1.59‐5.04).
Conclusions
The framework offers a transparent and efficient way to perform and report drug data preparation steps. Assumptions made during data preparation can impact the results of analyses. Improving transparency regarding drug data preparation would increase the repeatability, reproducibility, and comparability of published results.
This article employs critical realism to reflect on two views of the body found within Marxism. It is argued that the first view-that of the body as simple prerequisite-found within the 1844 ...Manuscripts should be rejected due to a latent idealism and residual dualisms that render the body under-theorised, ontologically primitive and in limbo. It is then argued that the second view-that of the thinking body-introduced within The German Ideology would be strengthened further by using critical realism in an underlabouring role to reconceptualise the body-in-general as emergent so as to recognise more fully the paradoxical situation in which humans both are and have bodies. This conceptualisation would help both to aid the perception or actuality of a reductionist position and to acknowledge fully the stratified nature of human beings. In so doing, it is argued that, once there is a move back towards the concrete, such a theory of the body is able to inform more insightful analyses of the ways in which the body is (re)produced in a society in which biological space, as well as geographical and social spaces, is being infiltrated and colonised by a capitalist logic.
Change is central to critical realism yet there has been little theoretical explication on the temporal dimension. It is shown that this oversight results in Archer's morphogenetic approach employing ...an ontological dualism of cyclical and linear temporalities similar to that contained within Giddens' structuration theory. Consequently, neither Archer nor Giddens is able to explain change and the transition between different epochs in a persuasive manner. In order to minimize these problems, Adam's concept of circadian time is adopted. This allows for a diachronic analysis that synchronically incorporates both continuity and change. Accordingly, it is able to transcend the temporal dualism of repetition and transformation. This temporal conceptualization is then incorporated within a critical realist framework. It is suggested that employing a double helix analogy allows for the integration of the notion of a stratified social ontology with a non-dichotomous temporal conceptualization.
Abstract The Winchcombe meteorite is a CM chondrite breccia composed of eight distinct lithological units plus a cataclastic matrix. The degree of aqueous alteration varies between intensely altered ...CM2.0 and moderately altered CM2.6. Although no lithology dominates, three heavily altered rock types (CM2.1–2.3) represent >70 area%. Tochilinite–cronstedtite intergrowths (TCIs) are common in several lithologies. Their compositions can vary significantly, even within a single lithology, which can prevent a clear assessment of alteration extent if only TCI composition is considered. We suggest that this is due to early alteration under localized geochemical microenvironments creating a diversity of compositions and because later reprocessing was incomplete, leaving a record of the parent body's fluid history. In Winchcombe, the fragments of primary accretionary rock are held within a cataclastic matrix (~15 area%). This material is impact‐derived fallback debris. Its grain size and texture suggest that the disruption of the original parent asteroid responded by intergranular fracture at grain sizes <100 μm, while larger phases, such as whole chondrules, splintered apart. Re‐accretion formed a poorly lithified body. During atmospheric entry, the Winchcombe meteoroid broke apart with new fractures preferentially cutting through the weaker cataclastic matrix and separating the breccia into its component clasts. The strength of the cataclastic matrix imparts a control on the survival of CM chondrite meteoroids. Winchcombe's unweathered state and diversity of lithologies make it an ideal sample for exploring the geological history of the CM chondrite group.
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