648 research outputs found

    Lowland river responses to intraplate tectonism and climate forcing quantified with luminescence and cosmogenic 10Be

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    Intraplate tectonism has produced large-scale folding that steers regional drainage systems, such as the 1600 km-long Cooper Ck, en route to Australia’s continental depocentre at Lake Eyre. We apply cosmogenic 10Be exposure dating in bedrock, and luminescence dating in sediment, to quantify the erosional and depositional response of Cooper Ck where it incises the rising Innamincka Dome. The detachment of bedrock joint-blocks during extreme floods governs the minimum rate of incision (17.4±6.5 mm/ky) estimated using a numerical model of episodic erosion calibrated with our 10Be measurements. The last big-flood phase occurred no earlier than ~112–121ka. Upstream of the Innamincka Dome long-term rates of alluvial deposition, partly reflecting synclinal-basin subsidence, are estimated from 47 luminescence dates in sediments accumulated since ~270 ka. Sequestration of sediment in subsiding basins such as these may account for the lack of Quaternary accumulation in Lake Eyre, and moreover suggests that notions of a single primary depocentre at base-level may poorly represent lowland, arid-zone rivers. Over the period ~75–55 ka Cooper Ck changed from a bedload- dominant, laterally-active meandering river to a muddy anabranching channel network up to 60 km wide. We propose that this shift in river pattern was a product of base-level rise linked with the slowly deforming syncline–anticline structure, coupled with a climate-forced reduction in discharge. The uniform valley slope along this subsiding alluvial and rising bedrock system represents an adjustment between the relative rates of deformation and the ability of greatly enhanced flows at times during the Quaternary to incise the rising anticline. Hence, tectonic and climate controls are balanced in the long term

    Soil quality: to regulate or to manage?

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    The concept of soil quality was conceived in the early 1990s as a parallel to those of air and water quality in response to concerns about soil 'health,' sustainability and environmentally `friendly' crop production. The concept has the potential to be used by researchers to link soil research issues to broader environmental issues when applying for funds. However, unlike air and water, soils have no defined 'pure' state against which measures can be taken and comparisons made. The physical, chemical and biological composition of soils varies widely and no single attribute or soil type can be established as a standard. The choice of appropriate soil properties and their standards depends on the use to which the soil is put. We suggest concentrating on quality management of the soil, rather than managing generically-chosen soil properties, collectively called soil 'quality'. Quality management puts the onus on managers to use the technical tools that are readily available to manage soils and landscapes, and on scientists to develop new tools

    Cornerstones of Sampling of Operator Theory

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    This paper reviews some results on the identifiability of classes of operators whose Kohn-Nirenberg symbols are band-limited (called band-limited operators), which we refer to as sampling of operators. We trace the motivation and history of the subject back to the original work of the third-named author in the late 1950s and early 1960s, and to the innovations in spread-spectrum communications that preceded that work. We give a brief overview of the NOMAC (Noise Modulation and Correlation) and Rake receivers, which were early implementations of spread-spectrum multi-path wireless communication systems. We examine in detail the original proof of the third-named author characterizing identifiability of channels in terms of the maximum time and Doppler spread of the channel, and do the same for the subsequent generalization of that work by Bello. The mathematical limitations inherent in the proofs of Bello and the third author are removed by using mathematical tools unavailable at the time. We survey more recent advances in sampling of operators and discuss the implications of the use of periodically-weighted delta-trains as identifiers for operator classes that satisfy Bello's criterion for identifiability, leading to new insights into the theory of finite-dimensional Gabor systems. We present novel results on operator sampling in higher dimensions, and review implications and generalizations of the results to stochastic operators, MIMO systems, and operators with unknown spreading domains

    The spread of epidemic disease on networks

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    The study of social networks, and in particular the spread of disease on networks, has attracted considerable recent attention in the physics community. In this paper, we show that a large class of standard epidemiological models, the so-called susceptible/infective/removed (SIR) models can be solved exactly on a wide variety of networks. In addition to the standard but unrealistic case of fixed infectiveness time and fixed and uncorrelated probability of transmission between all pairs of individuals, we solve cases in which times and probabilities are non-uniform and correlated. We also consider one simple case of an epidemic in a structured population, that of a sexually transmitted disease in a population divided into men and women. We confirm the correctness of our exact solutions with numerical simulations of SIR epidemics on networks.Comment: 12 pages, 3 figure

    From Cholera to Burns: A Role for Oral Rehydration Therapy

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    According to the practice guidelines of the American Burn Association on burn shock resuscitation, intravenous (IV) fluid therapy is the standard of care for the replacement of fluid and electrolyte losses in burn injury of 6520% of the total body surface area. However, in mass burn casualties, IV fluid resuscitation may be delayed or unavailable. Oral rehydration therapy (ORT), which has been shown to be highly effective in the treatment of dehydration in epidemics of cholera, could be an alternate way to replace fluid losses in burns. A prospective case series of three patients was carried out as an initial step to establish whether oral Ceralyte\uae90 could replace fluid losses requiring IV fluid therapy in thermal injury. The requirement of the continuing IV fluid therapy was reduced by an average of 58% in the first 24 hours after the injury (range 37-78%). ORT may be a feasible alternative to IV fluid therapy in the resuscitation of burns. It could also potentially save many lives in mass casualty situations or in resource-poor settings where IV fluid therapy is not immediately available. Further studies are needed to assess the efficacy of this treatment and to determine whether the present formulations of ORT for cholera need modification

    Full adoption of the most effective strategies to mitigate methane emissions by ruminants can help meet the 1.5 °C target by 2030 but not 2050

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    To meet the 1.5 °C target, methane (CH) from ruminants must be reduced by 11 to 30% by 2030 and 24 to 47% by 2050 compared to 2010 levels. A meta-analysis identified strategies to decrease product-based (PB; CH per unit meat or milk) and absolute (ABS) enteric CH emissions while maintaining or increasing animal productivity (AP; weight gain or milk yield). Next, the potential of different adoption rates of one PB or one ABS strategy to contribute to the 1.5 °C target was estimated. The database included findings from 430 peer-reviewed studies, which reported 98 mitigation strategies that can be classified into three categories: animal and feed management, diet formulation, and rumen manipulation. A random-effects meta-analysis weighted by inverse variance was carried out. Three PB strategies—namely, increasing feeding level, decreasing grass maturity, and decreasing dietary forage-to-concentrate ratio—decreased CH per unit meat or milk by on average 12% and increased AP by a median of 17%. Five ABS strategies—namely CH inhibitors, tanniferous forages, electron sinks, oils and fats, and oilseeds—decreased daily methane by on average 21%. Globally, only 100% adoption of the most effective PB and ABS strategies can meet the 1.5 °C target by 2030 but not 2050, because mitigation effects are offset by projected increases in CH due to increasing milk and meat demand. Notably, by 2030 and 2050, low- and middle-income countries may not meet their contribution to the 1.5 °C target for this same reason, whereas high-income countries could meet their contributions due to only a minor projected increase in enteric CH emissions.We thank the GLOBAL NETWORK project for generating part of the database. The GLOBAL NETWORK project (https://globalresearchalliance.org/research/livestock/collaborative-activities/global-research-project/; accessed 20 June 2020) was a multinational initiative funded by the Joint Programming Initiative on Food Security, Agriculture, and Climate Change and was coordinated by the Feed and Nutrition Network (https://globalresearchalliance.org/research/livestock/networks/feed-nutrition-network/; accessed 20 June 2020) within the Livestock Research Group of the Global Research Alliance on Agricultural GHG (https://globalresearchalliance.org; accessed 20 June 2020). We thank MitiGate, which was part of the Animal Change project funded by the EU under Grant Agreement FP7-266018 for sharing their database with us (http://mitigate.ibers.aber.ac.uk/, accessed 1 July 2017). Part of C.A., A.N.H., and S.C.M.’s time in the early stages of this project was funded by the Kravis Scientific Research Fund (New York) and a gift from Sue and Steve Mandel to the Environmental Defense Fund. Another part of C.A.’s work on this project was supported by the National Program for Scientific Research and Advanced Studies - PROCIENCIA within the framework of the "Project for the Improvement and Expansion of the Services of the National System of Science, Technology and Technological Innovation" (Contract No. 016-2019) and by the German Federal Ministry for Economic Cooperation and Development (issued through Deutsche Gesellschaft für Internationale Zusammenarbei) through the research “Programme of Climate Smart Livestock” (Programme 2017.0119.2). Part of A.N.H.’s work was funded by the US Department of Agriculture (Washington, DC) National Institute of Food and Agriculture Federal Appropriations under Project PEN 04539 and Accession no. 1000803. E.K. was supported by the Sesnon Endowed Chair Fund of the University of California, Davis

    The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

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    Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect

    Study of the production of Λb0\Lambda_b^0 and B0\overline{B}^0 hadrons in pppp collisions and first measurement of the Λb0J/ψpK\Lambda_b^0\rightarrow J/\psi pK^- branching fraction

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    The product of the Λb0\Lambda_b^0 (B0\overline{B}^0) differential production cross-section and the branching fraction of the decay Λb0J/ψpK\Lambda_b^0\rightarrow J/\psi pK^- (B0J/ψK(892)0\overline{B}^0\rightarrow J/\psi\overline{K}^*(892)^0) is measured as a function of the beauty hadron transverse momentum, pTp_{\rm T}, and rapidity, yy. The kinematic region of the measurements is pT<20 GeV/cp_{\rm T}<20~{\rm GeV}/c and 2.0<y<4.52.0<y<4.5. The measurements use a data sample corresponding to an integrated luminosity of 3 fb13~{\rm fb}^{-1} collected by the LHCb detector in pppp collisions at centre-of-mass energies s=7 TeV\sqrt{s}=7~{\rm TeV} in 2011 and s=8 TeV\sqrt{s}=8~{\rm TeV} in 2012. Based on previous LHCb results of the fragmentation fraction ratio, fΛB0/fdf_{\Lambda_B^0}/f_d, the branching fraction of the decay Λb0J/ψpK\Lambda_b^0\rightarrow J/\psi pK^- is measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4}, \end{equation*} where the first uncertainty is statistical, the second is systematic, the third is due to the uncertainty on the branching fraction of the decay B0J/ψK(892)0\overline{B}^0\rightarrow J/\psi\overline{K}^*(892)^0, and the fourth is due to the knowledge of fΛb0/fdf_{\Lambda_b^0}/f_d. The sum of the asymmetries in the production and decay between Λb0\Lambda_b^0 and Λb0\overline{\Lambda}_b^0 is also measured as a function of pTp_{\rm T} and yy. The previously published branching fraction of Λb0J/ψpπ\Lambda_b^0\rightarrow J/\psi p\pi^-, relative to that of Λb0J/ψpK\Lambda_b^0\rightarrow J/\psi pK^-, is updated. The branching fractions of Λb0Pc+(J/ψp)K\Lambda_b^0\rightarrow P_c^+(\rightarrow J/\psi p)K^- are determined.Comment: 29 pages, 19figures. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-032.htm
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