3,542 research outputs found

    Managing droughts in the low-rainfall areas of the Middle East and North Africa:

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    Drought is a recurrent and often devastating threat to the welfare of countries in the Middle East and North Africa (MENA) where three-quarters of the arable land has less than 400 mm of annual rainfall, and the natural grazings, which support a majority of the 290 million ruminant livestock, have less than 200 mm. Its impact has been exacerbated in the last half century by the human population increasing yearly at over 3%, while livestock numbers have risen by 50% over the quinquennium. Virtually no scope exists for further expansion of rainfed farming and very little for irrigation, hence there is competition between mechanized cereal production and grazing in the low rainfall areas, and traditional nomadic systems of drought management through mobility are becoming difficult to maintain. Moreover droughts seem to be increasing in frequency, and their high social, economic, and environmental costs have led governments to intervene with various forms of assistance to farmers and herders, including distribution of subsidized animal feed, rescheduling of loans, investments in water development, and in animal health. In this paper we examine the nature and significance of these measures, both with respect to their immediate benefits and costs to the recipients and to governments, and to their longer term impact on poverty and the environment. We conclude that while they have been valuable in reducing catastrophic losses of livestock and thus alleviating poverty, especially in the low rainfall areas where they are the predominant source of income, continued dependence on these programs has sent inappropriate signals to farmers and herders, leading to moral hazards, unsustainable farming practices, and environmental degradation, while generally benefiting the affluent recipients most.Rainfed farming., Environmental impact analysis., Irrigation., Droughts., Middle East., North Africa.,

    Can the polarization of the strange quarks in the proton be positive ?

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    Recently, the HERMES Collaboration at DESY, using a leading order QCD analysis of their data on semi-inclusive deep inelastic production of charged hadrons, reported a marginally positive polarization for the strange quarks in the proton. We argue that a non-negative polarization is almost impossible.Comment: 6 pages, latex, minor changes in the discussion after Eq. (9

    Non-invasive methods for the estimation of mPAP in COPD using Cardiovascular Magnetic Resonance Imaging

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    Purpose Pulmonary hypertension (PH) is associated with a poor outcome in chronic obstructive pulmonary disease (COPD) and is diagnosed invasively. We aimed to assess the diagnostic accuracy and prognostic value of non-invasive cardiovascular magnetic resonance (CMR) models. Methods Patients with COPD and suspected PH, who underwent CMR and right heart catheter (RHC) were identified. Three candidate models were assessed: 1, CMR-RV model, based on right ventricular (RV) mass and interventricular septal angle; 2, CMR PA/RV includes RV mass, septal angle and pulmonary artery (PA) measurements; 3, the Alpha index, based on RV ejection fraction and PA size. Results Of 102 COPD patients, 87 had PH. The CMR-PA/RV model had the strongest diagnostic accuracy (sensitivity 92%, specificity 80%, positive predictive value 96% and negative predictive value 63%, AUC 0.93, p<0.0001). Splitting RHCmPAP, CMR-RV and CMR-PA/RV models by 35mmHg gave a significant difference in survival, with log-rank chi-squared 5.03, 5.47 and 7.10. RV mass and PA relative area change were the independent predictors of mortality at multivariate Cox regression (p=0.002 and 0.030). Conclusion CMR provides diagnostic and prognostic information in PH-COPD. The CMR-PA/RV model is useful for diagnosis, the RV mass index and PA relative area change are useful to assess prognosis. Key Points • Pulmonary hypertension is a marker of poor outcome in COPD. • MRI can predict invasively measured mean pulmonary artery pressure. • Cardiac MRI allows for estimation of survival in COPD. • Cardiac MRI may be useful for follow up or future trials. • MRI is potentially useful to assess pulmonary hypertension in patients with COPD

    Modelling marine emissions and atmospheric distributions of halocarbons and dimethyl sulfide: the influence of prescribed water concentration vs. prescribed emissions

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    Marine-produced short-lived trace gases such as dibromomethane (CH2Br2), bromoform (CHBr3), methyliodide (CH3I) and dimethyl sulfide (DMS) significantly impact tropospheric and stratospheric chemistry. Describing their marine emissions in atmospheric chemistry models as accurately as possible is necessary to quantify their impact on ozone depletion and Earth's radiative budget. So far, marine emissions of trace gases have mainly been prescribed from emission climatologies, thus lacking the interaction between the actual state of the atmosphere and the ocean. Here we present simulations with the chemistry climate model EMAC (ECHAM5/MESSy Atmospheric Chemistry) with online calculation of emissions based on surface water concentrations, in contrast to directly prescribed emissions. Considering the actual state of the model atmosphere results in a concentration gradient consistent with model real-time conditions at the ocean surface and in the atmosphere, which determine the direction and magnitude of the computed flux. This method has a number of conceptual and practical benefits, as the modelled emission can respond consistently to changes in sea surface temperature, surface wind speed, sea ice cover and especially atmospheric mixing ratio. This online calculation could enhance, dampen or even invert the fluxes (i.e. deposition instead of emissions) of very short-lived substances (VSLS). We show that differences between prescribing emissions and prescribing concentrations (−28 % for CH2Br2 to +11 % for CHBr3) result mainly from consideration of the actual, time-varying state of the atmosphere. The absolute magnitude of the differences depends mainly on the surface ocean saturation of each particular gas. Comparison to observations from aircraft, ships and ground stations reveals that computing the air–sea flux interactively leads in most of the cases to more accurate atmospheric mixing ratios in the model compared to the computation from prescribed emissions. Calculating emissions online also enables effective testing of different air–sea transfer velocity (k) parameterizations, which was performed here for eight different parameterizations. The testing of these different k values is of special interest for DMS, as recently published parameterizations derived by direct flux measurements using eddy covariance measurements suggest decreasing k values at high wind speeds or a linear relationship with wind speed. Implementing these parameterizations reduces discrepancies in modelled DMS atmospheric mixing ratios and observations by a factor of 1.5 compared to parameterizations with a quadratic or cubic relationship to wind spee

    Developing a Dementia information portal for Deaf British Sign Language users: A pilot study

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    A small project called ‘Developing a dementia information portal for Deaf British Sign Language users: a pilot study’, funded internally by MICRA (Manchester Interdisciplinary Collaboration for Research on Ageing) was completed in August 2014. A summary report with a number of recommendations is now available with kind permission from the committee.The project produced two different versions of information on dementia, signed in BSL. The first version was a BSL translation using text from ‘Getting to know me’ as a script, presented by a Deaf BSL translator. The latter version was a presentation of information, using the same text as a guide, transposed by the same translator in a number of different real-life settings. Both videos were uploaded onto the website with an explanation of the purpose of the pilot study. A short survey was inserted onto the website with a few closed questions for feedback. Following the survey, we were able to present to the committee respondents’ comments and figures showing a breakdown of respondents’ preference of video clip, thus indicating which clip was most popular as a resource for Deaf people who need information about dementia in BSL

    Are language production problems apparent in adults who no longer meet diagnostic criteria for attention-deficit/hyperactivity disorder?

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    In this study, we examined sentence production in a sample of adults (N = 21) who had had attention-deficit/hyperactivity disorder (ADHD) as children, but as adults no longer met DSM-IV diagnostic criteria (APA, 2000). This “remitted” group was assessed on a sentence production task. On each trial, participants saw two objects and a verb. Their task was to construct a sentence using the objects as arguments of the verb. Results showed more ungrammatical and disfluent utterances with one particular type of verb (i.e., participle). In a second set of analyses, we compared the remitted group to both control participants and a “persistent” group, who had ADHD as children and as adults. Results showed that remitters were more likely to produce ungrammatical utterances and to make repair disfluencies compared to controls, and they patterned more similarly to ADHD participants. Conclusions focus on language output in remitted ADHD, and the role of executive functions in language production

    Trends and emissions of six perfluorocarbons in the Northern Hemisphere and Southern Hemisphere

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    Perfluorocarbons (PFCs) are potent greenhouse gases with global warming potentials up to several thousand times greater than CO2 on a 100-year time horizon. The lack of any significant sinks for PFCs means that they have long atmospheric lifetimes of the order of thousands of years. Anthropogenic production is thought to be the only source for most PFCs. Here we report an update on the global atmospheric abundances of the following PFCs, most of which have for the first time been analytically separated according to their isomers: c-octafluorobutane (c-C4F8), n-decafluorobutane (n-C4F10), n-dodecafluoropentane (n-C5F12), n-tetradecafluorohexane (n-C6F14), and n-hexadecafluoroheptane (n-C7F16). Additionally, we report the first data set on the atmospheric mixing ratios of perfluoro-2-methylpentane (i-C6F14). The existence and significance of PFC isomers have not been reported before, due to the analytical challenges of separating them. The time series spans a period from 1978 to the present. Several data sets are used to investigate temporal and spatial trends of these PFCs: time series of air samples collected at Cape Grim, Australia, from 1978 to the start of 2018; a time series of air samples collected between July 2015 and April 2017 at Tacolneston, UK; and intensive campaign-based sampling collections from Taiwan. Although the remote “background” Southern Hemispheric Cape Grim time series indicates that recent growth rates of most of these PFCs are lower than in the 1990s, we continue to see significantly increasing mixing ratios that are between 6 % and 27 % higher by the end of 2017 compared to abundances measured in 2010. Air samples from Tacolneston show a positive offset in PFC mixing ratios compared to the Southern Hemisphere baseline. The highest mixing ratios and variability are seen in air samples from Taiwan, which is therefore likely situated much closer to PFC sources, confirming predominantly Northern Hemispheric emissions for most PFCs. Even though these PFCs occur in the atmosphere at levels of parts per trillion molar or less, their total cumulative global emissions translate into 833 million metric tonnes of CO2 equivalent by the end of 2017, 23 % of which has been emitted since 2010. Almost two-thirds of the CO2 equivalent emissions within the last decade are attributable to c-C4F8, which currently also has the highest emission rates that continue to grow. Sources of all PFCs covered in this work remain poorly constrained and reported emissions in global databases do not account for the abundances found in the atmosphere

    Tropospheric observations of CFC-114 and CFC-114a with a focus on long-term trends and emissions

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    Chlorofluorocarbons (CFCs) are ozone-depleting substances as well as strong greenhouse gases, and the control of their production and use under the Montreal Protocol has had demonstrable benefits to both mitigation of increasing surface UV radiation and climate forcing. A global ban on consumption came into force in 2010, but there is evidence of continuing emissions of certain CFCs from a range of sources. One compound has received little attention in the literature, namely CFC-114 (C2Cl2F4). Of particular interest here is the differentiation between CFC-114 (CClF2CClF2) and its asymmetric isomeric form CFC-114a (CF3CCl2F) as atmospheric long-term measurements in the peer-reviewed literature to date have been assumed to represent the sum of both isomers with a time-invariant isomeric speciation. Here we report the first long-term measurements of the two isomeric forms separately, and find that they have different origins and trends in the atmosphere. Air samples collected at Cape Grim (41° S), Australia, during atmospheric background conditions since 1978, combined with samples collected from deep polar snow (firn) enable us to obtain a near-complete record of both gases since their initial production and release in the 1940s. Both isomers were present in the unpolluted atmosphere in comparably small amounts before 1960. The mixing ratio of CFC-114 doubled from 7.9 to 14.8 parts per trillion (ppt) between the start of the Cape Grim record in 1978 and the end of our record in 2014, while over the same time CFC-114a trebled from 0.35 to 1.03 ppt. Mixing ratios of both isomers are slowly decreasing by the end of this period. This is consistent with measurements of recent aircraft-based samples showing no significant interhemispheric mixing ratio gradient

    Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) experiment: design, execution and science overview

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    We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of air masses that contain the emission products from seasonal boreal wildfires and how these air masses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada, based out of Halifax, Nova Scotia. Atmospheric ground-based and sonde measurements over Canada and the Azores associated with the planned July 2010 deployment of the ARA, which was postponed by 12 months due to UK-based flights related to the dispersal of material emitted by the Eyjafjallajökull volcano, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 involved the same atmospheric measurements, but included the ARA, special satellite observations and a more comprehensive ground-based measurement suite. The high-frequency aircraft data provided a comprehensive chemical snapshot of pyrogenic plumes from wildfires, corresponding to photochemical (and physical) ages ranging from 45 sr 10 days, largely by virtue of widespread fires over Northwestern Ontario. Airborne measurements reported a large number of emitted gases including semi-volatile species, some of which have not been been previously reported in pyrogenic plumes, with the corresponding emission ratios agreeing with previous work for common gases. Analysis of the NOy data shows evidence of net ozone production in pyrogenic plumes, controlled by aerosol abundance, which increases as a function of photochemical age. The coordinated ground-based and sonde data provided detailed but spatially limited information that put the aircraft data into context of the longer burning season in the boundary layer. Ground-based measurements of particulate matter smaller than 2.5 μm (PM2.5) over Halifax show that forest fires can on an episodic basis represent a substantial contribution to total surface PM2.5
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