1,746 research outputs found

    Factorization fits to charmless strangeless B decays

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    We present fits to charmless strangeless hadronic B decay data for mean branching ratios and CP-violating asymmetries using the QCD factorization model of Beneke et al. Apart from one CP-violating parameter, the model gives a very good representation of 26 measured data. We find the CKM angle alpha = (93.5 +/- 8.4 -1.3) degrees and to be quite stable to plausible "charming penguin" corrections.Comment: 4 pages, LaTeX, Minor changes to text, references adde

    Gluon and gluino penguin diagrams and the charmless decays of the b quark

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    Gluon mediated exclusive hadronic decays of b quarks are studied within the standard model (SM) and the constrained minimally supersymmetric standard model (MSSM). For all allowed regions of the MSSM parameter space (A, tan beta, m_0, m_{1/2}) the penguin magnetic dipole form factor F^R_2 is dominant over the electric dipole and can be larger than the magnetic dipole form factor of the SM. However, overall the SM electric dipole decay amplitude F^L_1 dominates the decay rate. The MSSM penguin contributions to the free quark decay rate approach the 10% level for those regions of parameter space close to the highest allowed values of tan beta (~55) for which the gluino is light (m_{\tilde{g}} \approx 360 GeV) and lies within the range of the six d-squark masses. In these regions the supersymmetric box amplitudes are negligible. The MSSM phases change very little over the allowed parameter space and can lead to significant interference with the SM amplitudes

    Evaluation of the Ecosystem Services of the Central Marsh in Southern Iraq

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    Ecosystems provide humans with services that include benefits from food, fresh water, climate regulation, and socio-economic assets. The Mesopotamian marshlands are among the largest wetlands in the Middle East and they provide various benefits. However, ecosystem services of the Marshlands are consistently undervalued in national economic analysis and decision making. This study focusses on the Central Marshes, the first National Park in Iraq, and is the first attempt at valuing a series of ecosystem services from a valuable natural ecosystem in Iraq. We adopted the Toolkit for Ecosystem Services Site-Based Assessment (TESSA) for the determination of biophysical and economic values of services at the site level. Data on key ecosystem services (as determined by 30 interviews with residents of the Marshes) included the trading of fish, harvested plants, water buffalo milk, and fodder were collected across six months in 2014. We valued the ecosystem services within the CM (40,000 ha) over a 6-month period to have a total value of 860,078.23 USD. This estimated total value was the sum of 86,637.25 USD from harvested plants, 551,334.80 USD from trading fish, 167, 303.70 USD from trading water buffalo milk, and 54,804.00 USD from trading fodder. The average income per individual in Iraq in 2014 was 6720 USD (World Bank data - https://data.worldbank.org/country/iraq): thus, the CM provided an average salary for 256 people. Our results provided greater understanding of the ecosystem services contributed by the Central Marshes and has highlighted the crucial role of nature in supporting sustainable well-being for humans living in the area. In addition, the results can be used to enhance local policy, to aid management plans of the National park, and to estimate lost and damage that could result from impact of climate change on the area

    Pollution threatens water quality in the Central Marshes of Southern Iraq

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    تلوث المياه مشكلة يمكن أن تتفاقم بسبب الجفاف مع زيادة تراكيز المواد غير المرغوب فيها. توفر الاهوار الطبيعية إمكانية تحسين جودة المياه وهنا نقدم أدلة على هذه الخدمة بناءً على تدفق المياه من نهر الفرات (الذي عانى من انخفاض كبير في التدفق) إلى الأهوار في جنوب العراق. تم إنشاء سدة ترابية في عام 2010 على نهر الفرات لمنع المياه التي يقل ارتفاعها عن 1.7 متر من المرور من محافظة ذي قار (الجبايش) إلى محافظة البصرة (المدَينه) كاستجابة للجفاف الشديد الذي واجه المنطقة في عامي 2009 و 2010. ونتيجة لذلك ، أصبحت الاهوار الوسطى في الجبايش موقعا نهائيا (بدون منفذ) الى كل مياه نهر الفرات التي تاتي من غرب العراق محملة بمختلف الملوثات والنفايات الزراعية. تم اختبار قدرة الاهوار الوسطى على العمل كبالوعة لتقليل تراكم العناصر الغذائية (NO2 ، NO3 ، PO4) ، والملوحة ، والأيونات الرئيسة ، والمعادن الثقيلة (Cu ، Ni ، Pb ، Cd ، Zn) في نهر الفرات. قسمت منطقة الدراسة إلى أربع مناطق أفقية (النهر وثلاث مناطق داخل الهور) وأجريت ثمانية مسوحات ميدانية من تشرين الثاني 2013 إلى حزيران 2014 لجمع عينات المياه باستخدام منهجية الخط المستقيم (transect line methodology). كانت الملوحة والأيونات الرئيسية أعلى بشكل معنوي داخل الهور مقارنة بالنهر. ومع ذلك ، لم يتم العثور على اختلافات بين قيم المغذيات في النهر والهور مما يشير إلى أن دور الهور للعمل كبالوعة لهذه المواد كان محدودا  وان تراكم الملوثات وتركيزها كان اكثر في داخل الهور منه الى المناطق القريبة للنهر. لذلك فإن التراكم طويل الأمد يشكل تحديًا كبيرًا يواجه الهور في ظل ظروف شحة المياه في نهر الفرات ، وهذا يتطلب اهتمامًا عاجلاً ، خاصة بالنظر إلى مكانة الموقع كموقع للتراث العالمي (لخدمات النظم الطبيعية المقدمة للسكان المحليين) وكمنطقة تنوع بيولوجي مهمة. ملف ملحقWater pollution is an issue that can be exacerbated by drought as increased concentrations of unwanted substances are a consequence of lower water levels. Polluted water that flows into natural marshlands leads to the deposition of pollutants in the interior of the marsh. Here we present evidence that the interior of the Central Marsh (CM) in southern Iraq suffers from higher levels of pollution than areas closer to the source of water entering the marsh (the Euphrates River). A 1.7m embankment that halts the flow of the Euphrates is only infrequently breached and so the CM is effectively the terminal destination of the waters (and their associated pollutants and agricultural waste) flowing from the West of Iraq. A range of water quality metrics were measured where the Euphrates enters the CM and at increasing distances into the interior of the CM. The following measures were taken:  NO2, NO3, PO4 , Salinity, Major ions, and Heavy Metals (Cu, Ni, Pb, Cd, Zn). The area of study was divided into four horizontal zones (the river and three zones inside the marsh) and eight field surveys were carried out from November 2013 to June 2014 to collect water samples by using a transect line methodology.  Salinity and major ions (Na, K, Cl, Ca, and Mg) were significantly higher inside the marsh compared with levels in the river water immediately before it entered the CM.  These findings indicate  the increased risk of these pollutants to humans and wildlife living in and using the CM.  This issue  requires urgent attention, especially to the status of the CM as a World Heritage site (for the ecosystem services provided to local people) as an Important Biodiversity Area. The reported declines in water quantity in the Euphrates over recent decades will likely further exacerbate the problems we report. Supplement fil

    Synthesis of H<sub>x</sub>Li<sub>1-x</sub>LaTiO<sub>4</sub> from quantitative solid-state reactions at room temperature

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    The layered perovskite HLaTiO4 reacts stoichiometrically with LiOH·H2O at room temperature to give targeted compositions in the series HxLi1-xLaTiO4. Remarkably, the Li+ and H+ ions are quantitatively exchanged in the solid state and this allows stoichiometric control of ion exchange for the first time in this important series of compounds

    Modular access to substituted azocanes via a rhodium-catalyzed cycloaddition-fragmentation strategy

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    A short entry to substituted azocanes by a Rh-catalyzed cycloaddition–fragmentation process is described. Specifically, exposure of diverse <i>N</i>-cyclopropylacrylamides to phosphine-ligated cationic Rh­(I) catalyst systems under a CO atmosphere enables the directed generation of rhodacyclopentanone intermediates. Subsequent insertion of the alkene component is followed by fragmentation to give the heterocyclic target. Stereochemical studies show, for the first time, that alkene insertion into rhodacyclopentanones can be reversible

    Sexual selection explains Rensch's rule of allometry for sexual size dimorphism

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    In 1950, Rensch first described that in groups of related species, sexual size dimorphism is more pronounced in larger species. This widespread and fundamental allometric relationship is now commonly referred to as ‘Rensch's rule’. However, despite numerous recent studies, we still do not have a general explanation for this allometry. Here we report that patterns of allometry in over 5300 bird species demonstrate that Rensch's rule is driven by a correlated evolutionary change in females to directional sexual selection on males. First, in detailed multivariate analysis, the strength of sexual selection was, by far, the strongest predictor of allometry. This was found to be the case even after controlling for numerous potential confounding factors, such as overall size, degree of ornamentation, phylogenetic history and the range and degree of size dimorphism. Second, in groups where sexual selection is stronger in females, allometry consistently goes in the opposite direction to Rensch's rule. Taken together, these results provide the first clear solution to the long-standing evolutionary problem of allometry for sexual size dimorphism: sexual selection causes size dimorphism to correlate with species size

    Global inequities and political borders challenge nature conservation under climate change

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    Underlying sociopolitical factors have emerged as important determinants of wildlife population trends and the effectiveness of conservation action. Despite mounting research into the impacts of climate change on nature, there has been little consideration of the human context in which these impacts occur, particularly at the global scale. We investigate this in two ways. First, by modeling the climatic niches of terrestrial mammals and birds globally, we show that projected species loss under climate change is greatest in countries with weaker governance and lower Gross Domestic Product, with loss of mammal species projected to be greater in countries with lower CO2 emissions. Therefore, climate change impacts on species may be disproportionately significant in countries with lower capacity for effective conservation and lower greenhouse gas emissions, raising important questions of international justice. Second, we consider the redistribution of species in the context of political boundaries since the global importance of transboundary conservation under climate change is poorly understood. Under a high-emissions scenario, we find that 35% of mammals and 29% of birds are projected to have over half of their 2070 climatic niche in countries in which they are not currently found. We map these transboundary range shifts globally, identifying borders across which international coordination might most benefit conservation and where physical border barriers, such as walls and fences, may be an overlooked obstacle to climate adaptation. Our work highlights the importance of sociopolitical context and the utility of a supranational perspective for 21st century nature conservation

    Agriculturally Improved and Semi-Natural Permanent Grasslands Provide Complementary Ecosystem Services in Swedish Boreal Landscapes

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    \ua9 2024 by the authors. Permanent grasslands cover more than a third of European agricultural land and are important for a number of ecosystem services. Permanent grasslands used for agriculture are broadly separated into agriculturally improved and semi-natural grasslands. High cultural and natural values linked to semi-natural grasslands are well documented. However, in boreal and hemi-boreal agricultural landscapes, less information is available about the areal coverage of improved permanent grasslands and their role for ecosystem service provision and biodiversity. In Sweden, grasslands are administratively separated into semi-natural (i.e., land that cannot be ploughed) or arable (i.e., improved temporary or permanent grassland on land that can be ploughed). We used data from a large-scale environmental monitoring program to show that improved permanent grassland (i.e., permanent grasslands on arable fields) may be a previously unrecognised large area of the agricultural land use in Sweden. We show that improved permanent grasslands together with semi-natural grasslands are both comparable but also complementary providers of a range of ecosystem services (plant species richness, plant resources for pollinators and forage amount for livestock production). However, as expected, semi-natural grasslands with the highest-level AESs (special values) show high species richness values for vascular plants, plants indicating traditional semi-natural management conditions and red-listed species. Improved permanent grasslands on arable fields are likely an underestimated but integral part of the agricultural economy and ecological function in boreal landscapes that together with high nature value semi-natural grasslands provide a broad range of ecosystem services

    The Anode Challenge for Lithium-Ion Batteries: A Mechanochemically Synthesized Sn-Fe-C Composite Anode Surpasses Graphitic Carbon

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    Carbon-based anodes are the key limiting factor in increasing the volumetric capacity of lithium-ion batteries. Tin-based composites are one alternative approach. Nanosized Sn-Fe-C anode materials are mechanochemically synthesized by reducing SnO with Ti in the presence of carbon. The optimum synthesis conditions are found to be 1:0.25:10 for initial ratio of SnO, Ti, and graphite with a total grinding time of 8 h. This optimized composite shows excellent extended cycling at the C/10 rate, delivering a first charge capacity as high as 740 mAh g(-1) and 60% of which still remained after 170 cycles. The calculated volumetric capacity significantly exceeds that of carbon. It also exhibits excellent rate capability, delivering volumetric capacity higher than 1.6 Ah cc(-1) over 140 cycles at the 1 C rate
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