223 research outputs found
Successful Non-Invasive treatment of stricturing fibrosing colonopathy in an adult patient
<p>Abstract</p> <p>Objective</p> <p>Fibrosing colonopathy (FC) is a rare entity associated with cystic fibrosis (CF). Until now, patients with stricturing FC have usually been treated surgically. In this instance, we aimed at avoiding surgery by applying a new conservative approach.</p> <p>Methods</p> <p>Case report on an adult with CF who developed persistent abdominal pain due to a non-passable stricture in the right transverse colon. Histology confirmed fibrosing colonopathy.</p> <p>Results</p> <p>Initially we treated the patient with prednisolone pulse therapy and additive antibiotic therapy. For maintenance therapy we administered budesonide. The patient underwent clinical, laboratory and endoscopic follow-up over a three-year period. The stricture healed and was easy to pass. A relapse in the cecum at the ileocecal valve again improved under steroid and antibiotic therapy.</p> <p>Conclusions</p> <p>We present a novel therapeutic approach for advanced stricturing FC in an adult patient which successfully avoided surgery (right hemicolectomy) over a three year follow up.</p
Polarization of coalitions in an agent-based model of political discourse
Political discourse is the verbal interaction between political actors in a policy domain. This article explains the formation of polarized advocacy or discourse coalitions in this complex phenomenon by presenting a dynamic, stochastic, and discrete agent-based model based on graph theory and local optimization. In a series of thought experiments, actors compute their utility of contributing a specific statement to the discourse by following ideological criteria, preferential attachment, agenda-setting strategies, governmental coherence, or other mechanisms. The evolving macro-level discourse is represented as a dynamic network and evaluated against arguments from the literature on the policy process. A simple combination of four theoretical mechanisms is already able to produce artificial policy debates with theoretically plausible properties. Any sufficiently realistic configuration must entail innovative and path-dependent elements as well as a blend of exogenous preferences and endogenous opinion formation mechanisms
Thermodynamics of C incorporation on Si(100) from ab initio calculations
We study the thermodynamics of C incorporation on Si(100), a system where
strain and chemical effects are both important. Our analysis is based on
first-principles atomistic calculations to obtain the important lowest energy
structures, and a classical effective Hamiltonian which is employed to
represent the long-range strain effects and incorporate the thermodynamic
aspects. We determine the equilibrium phase diagram in temperature and C
chemical potential, which allows us to predict the mesoscopic structure of the
system that should be observed under experimentally relevant conditions.Comment: 5 pages, 3 figure
Isotopes in pyrogenic carbon: a review
Pyrogenic carbon (PC; also known as biochar, charcoal, black carbon and soot) derived from natural and anthropogenic burning plays a major, but poorly quantified, role in the global carbon cycle. Isotopes provide a fundamental fingerprint of the source of PC and a powerful tracer of interactions between PC and the environment. Radiocarbon and stable carbon isotope techniques have been widely applied to studies of PC in aerosols, soils, sediments and archaeological sequences, with the use of other isotopes currently less developed. This paper reviews the current state of knowledge regarding (i) techniques for isolating PC for isotope analysis and (ii) processes controlling the carbon (<sup>13</sup>C and <sup>14</sup>C), nitrogen, oxygen, hydrogen and sulfur isotope composition of PC during formation and after deposition. It also reviews the current and potential future applications of isotope based studies to better understand the role of PC in the modern environment and to the development of records of past environmental change
Multi-objective calibration of RothC using measured carbon stocks and auxiliary data of a long-term experiment in Switzerland
Interactions between model parameters and low spatiotemporal resolution of available data mean that conventional soil organic carbon (SOC) models are often affected by equifinality, with consequent uncertainty in SOC forecasts. Estimation of belowground C inputs is another major source of uncertainty in SOC modelling. Models are usually calibrated on SOC stocks and fluxes from longâterm experiments (LTEs), whereas other point data are not used for constraining the model parameters. We used data from an agricultural longâterm (> 65 years) fertilization experiment to test a multiâobjective parameter estimation approach on the RothC model, combining SOC data from different fertilization treatments with microbial biomass, basal respiration and Zimmermannâs fractions data. We also compared two methods to estimate the belowground C inputs: a conventional scaling of belowground biomass from crop harvest yield and an alternative approach based on constant belowground C for cereals measured experimentally in the field. The resulting posterior parameter distributions still suffered from some equifinality; the most stable C pool kinetic constants and composition of exogenous organic matter were the most sensitive parameters. The use of fixed belowground C inputs for cereals improved the model performance, reducing the importance of treatmentâspecific parameters and processes. The introduction of microbial biomass and basal respiration data was effective for increasing determination of the calibration, but also suggested a change in the model structure: the microbial biomass pool, which is proportional to the C inputs in the traditional models, could be represented by different microbial physiology functions
MAGGnet: an international network to foster mitigation of agricultural greenhouse gases.
Research networks provide a framework for review, synthesis and systematic testing of theories by multiple scientists across international borders critical for addressing global-scale issues. In 2012, a GHG research network referred to as MAGGnet (Managing Agricultural Greenhouse Gases Network) was established within the Croplands Research Group of the Global Research Alliance on Agricultural Greenhouse Gases (GRA). With involvement from 46 alliance member countries, MAGGnet seeks to provide a platform for the inventory and analysis of agricultural GHG mitigation research throughout the world. To date, metadata from 315 experimental studies in 20 countries have been compiled using a standardized spreadsheet. Most studies were completed (74%) and conducted within a 1-3-year duration (68%). Soil carbon and nitrous oxide emissions were measured in over 80% of the studies. Among plant variables, grain yield was assessed across studies most frequently (56%), followed by stover (35%) and root (9%) biomass. MAGGnet has contributed to modeling efforts and has spurred other research groups in the GRA to collect experimental site metadata using an adapted spreadsheet. With continued growth and investment, MAGGnet will leverage limited-resource investments by any one country to produce an inclusive, globally shared meta-database focused on the science of GHG mitigation
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The greenhouse gas impacts of converting food production in England and Wales to organic methods
Agriculture is a major contributor to global greenhouse gas (GHG) emissions and must feature in efforts to reduce emissions. Organic farming might contribute to this through decreased use of farm inputs and increased soil carbon sequestration, but it might also exacerbate emissions through greater food production elsewhere to make up for lower organic yields. To date there has been no rigorous assessment of this potential at national scales. Here we assess the consequences for net GHG emissions of a 100% shift to organic food production in England and Wales using life-cycle assessment. We predict major shortfalls in production of most agricultural products against a conventional baseline. Direct GHG emissions are reduced with organic farming, but when increased overseas land use to compensate for shortfalls in domestic supply are factored in, net emissions are greater. Enhanced soil carbon sequestration could offset only a small part of the higher overseas emissions
Contemporary review of risk-stratified management in acute uncomplicated and complicated diverticulitis
BACKGROUND: Acute colonic diverticulitis is a common clinical condition. Severity of the disease is based on clinical, laboratory, and radiological investigations and dictates the need for medical or surgical intervention. Recent clinical trials have improved the understanding of the natural history of the disease resulting in new approaches to and better evidence for the management of acute diverticulitis.
METHODS: We searched the Cochrane Library (years 2004-2015), MEDLINE (years 2004-2015), and EMBASE (years 2004-2015) databases. We used the search terms "diverticulitis, colonic" or "acute diverticulitis" or "divertic*" in combination with the terms "management," "antibiotics," "non-operative," or "surgery." Registers for clinical trials (such as the WHO registry and the https://clinicaltrials.gov/) were searched for ongoing, recruiting, or closed trials not yet published.
RESULTS: Antibiotic treatment can be avoided in simple, non-complicated diverticulitis and outpatient management is safe. The management of complicated disease, ranging from a localized abscess to perforation with diffuse peritonitis, has changed towards either percutaneous or minimally invasive approaches in selected cases. The role of laparoscopic lavage without resection in perforated non-fecal diverticulitis is still debated; however, recent evidence from two randomised controlled trials has found a higher re-intervention in this group of patients.
CONCLUSIONS: A shift in management has occurred towards conservative management in acute uncomplicated disease. Those with uncomplicated acute diverticulitis may be treated without antibiotics. For complicated diverticulitis with purulent peritonitis, the use of peritoneal lavage appears to be non-superior to resection
Membership nominations in international scientific assessments
International scientific assessments are transnational knowledge-based expert networks with a mandate to advise policymakers. A well-known example is the Millennium Ecosystem Assessment (MA), which synthesized research on ecosystem services between 2001 and 2005, utilizing the knowledge of 1,360 expert members. Little, however, is known about the membership composition and the driving forces behind membership nominations in the MA and similar organizations. Here we introduce a survey data set on recruitment in the MA and analyse nomination patterns among experts as a complex network. The results indicate that membership recruitment was governed by prior contacts in other transnational elite organizations and a range of other factors related to personal affinity. Network analysis demonstrates how some core individuals were particularly influential in shaping the overall membership composition of the group. These findings add to recently noted concerns about the lack of diversity of views represented in international scientific assessments
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