6,944 research outputs found

    Projections for future radiocarbon content in dissolved inorganic carbon in hardwater lakes: a retrospective approach

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    Inland water bodies contain significant amounts of carbon in the form of dissolved inorganic carbon (DIC) derived from a mixture of modern atmospheric and pre-aged sources, which needs to be considered in radiocarbon-based dating and natural isotope tracer studies. While reservoir effects in hardwater lakes are generally considered to be constant through time, a comparison of recent and historical DI14C data from 2013 and 1969 for Lake Constance reveals that this is not a valid assumption. We hypothesize that changes in atmospheric carbon contributions to lake water DIC have taken place due to anthropogenically forced eutrophication in the 20th century. A return to more oligotrophic conditions in the lake led to reoxygenation and enhanced terrigenous organic matter remineralization, contributing to lake water DIC. Such comparisons using DI14C measurements from different points in time enable nonlinear changes in lake water DIC source and signature to be disentangled from concurrent anthropogenically induced changes in atmospheric 14C. In the future, coeval changes in lake dynamics due to climate change are expected to further perturb these balances. Depending on the scenario, Lake Constance DI14C is projected to decrease from the 2013 measured value of 0.856 Fm to 0.54–0.62 Fm by the end of the century

    A participatory design approach for the development of support environments in eGovernment services to citizens

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    The introduction of eGovernment services and applications leads to major changes in the structure and operation of public administrations. In this paper we describe the work in progress in an Italian project called “SPO.T.” aimed at the analysis, development, deployment and evaluation of tools and environments to support the people who plan, deliver, use and evaluate user-centred provision of One-Stop-Shop services to citizens. The “SPO.T.” project has focused on two requirements: 1. the support tools and environments must facilitate the active involvement of all stakeholders in the definition and evolution of eGovernment applications and services, and it is argued that through participatory design changes of structure, process and culture can be delivered effectively; 2. they must embody a set of architecturally coherent resources which reflect the new roles and relationships of public administration and which are sufficiently generic to be relevant to a wide range of local contexts across the community

    Follow-up of a suspected excess of brain tumours among Namibian children

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    The original publication is available at http://www.samj.org.zaTo the Editor: The aim of this follow-up study was to further investigate a suggested excess of childhood brain tumours (CBT) among Herero children in Namibia from 1983 to 1988. Incidence rates of primary brain tumours among Herero children were found to be 4 times higher than rates among Namibian children in any of the 10 other tribal groups or among children of European origin. The causes of CBTs remain largely unknown. The only established causes are ionizing radiation and predisposing inherited syndromes. A particularly compelling hypothesis is that exposure during gestation to N-nitroso compounds (NOCs) may lead to the development of CBT. This hypothesis was suggested by experimental work in which 100% production of nervous system (NS) tumours in rat offspring resulted from transplacental exposure to the neurocarcinogen ethylnitrosourea (ENU) or to low levels of the precursor compounds sodium nitrite and ethyl urea added to the food and drinking water of pregnant rat

    The Interactive Lecture: A new Teaching Paradigm based on Ubiquitous Computing

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    In this paper we present a new teaching paradigm based on ubiquitous computing, which we call the Interactive Lecture. It specifically supports situations where the interactivity between students and lecturer is usually limited, such as lectures with a large number of students, or teleteaching scenarios. In an Interactive Lecture each student is equipped with a handheld computer. These computers connect to the computer of the lecturer via wireless communication. Interactivity between students and lecturer is then increased by a number of services. Examples for these services are: online-feedback which enables students to give immediate feedback about the lecture (e.g., about its speed and difficulty), or online-quizzes were all students participate in solving problems described by the lecturer. We have developed a first prototype of the software and performed a thorough evaluation during a graduate course. The results of this evaluation indicate that interactivity was increased significantly and that the students were very enthusiastic about participating in Interactive Lectures in the future

    Petrogenic organic carbon retention in terrestrial basins: a case study from perialpine Lake Constance

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    Inland waters play a major role in the global carbon cycle, with particulate organic carbon (POC) burial in terrestrial wetlands surpassing that in ocean sediments. Lake Constance, the second largest lake at the periphery of the European Alps, receives POC sourced from both aquatic and terrestrial productivity as well as petrogenic OC (OCpetro) from bedrock erosion. Distinguishing POC inputs to lake sediments is key to assessing carbon flux and fate as reworked OCpetro represents neither a net sink of atmospheric CO2 nor source of O2. New stable and radiocarbon isotopic data indicate that 11 (9–12) Gg/yr of OCpetro is buried in Lake Constance with underlying sediments on average containing 0.3 (0.25–0.33) wt% OCpetro. Extrapolation of these results suggests that 27 TgOCpetro/yr (12–54 TgOC/yr) could be subject to temporary geological storage in lakes globally, which is comparable to estimates of 43−25+61 TgOCpetro/yr delivered to the ocean by rivers (Galy et al., 2015). More studies are needed to quantify OCpetro burial in inland sedimentary reservoirs in order to accurately account for atmospheric carbon sequestration in terrestrial basins

    Tools and instruments for needs assessment, monitoring and evaluation of health research capacity development activities at the individual and organizational level: a systematic review

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    Background: In the past decades, various frameworks, methods, indicators, and tools have been developed to assess the needs as well as to monitor and evaluate (needs assessment, monitoring and evaluation;"NaME") health research capacity development (HRCD) activities. This systematic review gives an overview on NaME activities at the individual and organizational level in the past 10 years with a specific focus on methods, tools and instruments. Insight from this review might support researchers and stakeholders in systemizing future efforts in the HRCD field. Methods: A systematic literature search was conducted in PubMed and Google Scholar. Additionally, the personal bibliographies of the authors were scanned. Two researchers independently reviewed the identified abstracts for inclusion according to previously defined eligibility criteria. The included articles were analysed with a focus on both different HRCD activities as well as NaME efforts. Results: Initially, the search revealed 700 records in PubMed, two additional records in Google Scholar, and 10 abstracts from the personal bibliographies of the authors. Finally, 42 studies were included and analysed in depth. Findings show that the NaME efforts in the field of HRCD are as complex and manifold as the concept of HRCD itself. NaME is predominately focused on outcome evaluation and mainly refers to the individual and team levels. Conclusion: A substantial need for a coherent and transparent taxonomy of HRCD activities to maximize the benefits of future studies in the field was identified. A coherent overview of the tools used to monitor and evaluate HRCD activities is provided to inform further research in the field

    Стабилизация излучения бетатрона

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    A fast and simple method for the simultaneous analysis of midazolam, 1-hydroxymidazolam, 4-hydroxymidazolam and 1-hydroxymidazolam glucuronide in human serum, plasma and urine

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    For the quantification of the sedative and anesthetic drug midazolam and its main (active) metabolites 1-hydroxymidazolam, 4-hydroxymidazolam and 1-hydroxymidazolam glucuronide in human serum, human EDTA plasma, human heparin plasma and human urine a single accurate method by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has been developed. Protein precipitation as sample preparation, without the need of a time-consuming deglucuronidation step for the quantification of 1-hydroxymidazolam glucuronide, resulted in a simple and rapid assay suitable for clinical practice with a total runtime of only 1.1 min. The four components and the isotope-labeled internal standards were separated on a C18 column and detection was performed with a triple-stage quadrupole mass spectrometer operating in positive ionization mode. The method was validated based on the "Guidance for Industry Bioanalytical Method Validation" (Food and Drug Administration, FDA) and the "Guideline on bioanalytical method validation" of the European Medicines Agency (EMA). Linearity was proven over the ranges of 5-1500 μg/L for midazolam, 1-hydroxymidazolam and 4-hydroxymidazolam and 25-5000 μg/L for 1-hydroxymidazolam glucuronide, using a sample volume of 100 μL. Matrix comparison indicated that the assay is also applicable to other human matrices like EDTA and heparin plasma and urine. Stability experiments showed good results for the stability of midazolam, 1-hydroxymidazolam and 1-hydroxymidazolam glucuronide in serum, EDTA and heparin plasma and urine stored for 7 days under different conditions. At room temperature, 4-hydroxymidazo-lam is stable for 7 days in EDTA plasma, but stable for only 3 days in serum and heparin plasma and less than 24 h in urine. All four compounds were found to be stable in serum, EDTA plasma, heparin plasma and urine for 7 days after sample preparation and for 3 freeze-thaw cycles. The assay has been applied in therapeutic drug monitoring of midazolam for (pediatric) intensive care patients
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