1,501 research outputs found

    The Economics of Desertification, Land Degradation, and Drought; Toward an Integrated Global Assessment

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    Land degradation has not been comprehensively addressed at the global level or in developing countries. A suitable economic framework that could guide investments and institutional action is lacking. This study aims to overcome this deficiency and to provide a framework for a global assessment based on a consideration of the costs of action versus inaction regarding desertification, land degradation, and drought (DLDD). Most of the studies on the costs of land degradation (mainly limited to soil erosion) give cost estimates of less than 1 percent up to about 10 percent of the agricultural gross domestic product (GDP) for various countries worldwide. But the indirect costs of DLDD on the economy (national income), as well as their socioeconomic consequences (particularly poverty impacts), must be accounted for, too. Despite the numerous challenges, a global assessment of the costs of action and inaction against DLDD is possible, urgent, and necessary. This study provides a framework for such a global assessment and provides insights from some related country studies.Agricultural Finance, Crop Production/Industries, Environmental Economics and Policy, Land Economics/Use, Resource /Energy Economics and Policy,

    On the potential and challenges of laser-induced thermal acoustics for experimental investigation of macroscopic fluid phenomena

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    Mixing and evaporation processes play an important role in fluid injection and disintegration. Laser-induced thermal acoustics (LITA) also known as laser-induced grating spectroscopy (LIGS) is a promising four-wave mixing technique capable to acquire speed of sound and transport properties of fluids. Since the signal intensity scales with pressure, LITA is effective in high-pressure environments. By analysing the frequency of LITA signals using a direct Fourier analysis, speed of sound data can be directly determined using only geometrical parameters of the optical arrangement no equation of state or additional modelling is needed at this point. Furthermore, transport properties, like acoustic damping rate and thermal diffusivity, are acquired using an analytical expression for LITA signals with finite beam sizes. By combining both evaluations in one LITA signal, we can estimate mixing parameters, such as the mixture temperature and composition, using suitable models for speed of sound and the acquired transport properties. Finally, direct measurements of the acoustic damping rate can provide important insights on the physics of supercritical fluid behaviour.Deutsche ForschungsgemeinschaftProjekt DEA

    On the potential and challenges of laser-induced thermal acoustics for experimental investigation of macroscopic fluid phenomena

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    Mixing and evaporation processes play an important role in fluid injection and disintegration. Laser-induced thermal acoustics (LITA) also known as laser-induced grating spectroscopy (LIGS) is a promising four-wave mixing technique capable to acquire speed of sound and transport properties of fluids. Since the signal intensity scales with pressure, LITA is effective in high-pressure environments. By analysing the frequency of LITA signals using a direct Fourier analysis, speed of sound data can be directly determined using only geometrical parameters of the optical arrangement no equation of state or additional modelling is needed at this point. Furthermore, transport properties, like acoustic damping rate and thermal diffusivity, are acquired using an analytical expression for LITA signals with finite beam sizes. By combining both evaluations in one LITA signal, we can estimate mixing parameters, such as the mixture temperature and composition, using suitable models for speed of sound and the acquired transport properties. Finally, direct measurements of the acoustic damping rate can provide important insights on the physics of supercritical fluid behaviour

    Characterisation of the transient mixing behaviour of evaporating near-critical droplets

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    With technical progress, combustion pressures have been increased over the years, frequently exceeding the critical pressure of the injected fluids. For conditions beyond the critical point of the injected fluids, the fundamental physics of mixing and evaporation processes is not yet fully understood. In particular, quantitative data for validation of numerical simulations and analytical models remain sparse. In previous works, transient speed of sound studies applying laser-induced thermal acoustics (LITA) have been conducted to investigate the mixing behaviour in the wake of an evaporating droplet injected into a supercritical atmosphere. LITA is a seedless, non-intrusive measurement technique capable of direct speed of sound measurements within these mixing processes. The used setup employs a high-repetition-rate excitation laser source and, therefore, allows the acquisition of time-resolved speed of sound data. For the visualisation of the evaporation process, measurements are accompanied by direct, high-speed shadowgraphy. In the present work, the measured speed of sound data are evaluated by applying an advection-controlled mixing assumption to estimate both the local mole fraction and mixing temperature. For this purpose, planar spontaneous Raman scattering results measured under the same operating conditions are evaluated using an advection-controlled mixing assumption with the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state. Successively, the resulting concentration–temperature field is used for the estimation of local mixture parameters from the detected speed of sound data. Moreover, models using the PC-SAFT equation of state and the NIST database for the computation of the speed of sound are compared. The investigations indicate a classical two-phase evaporation process with evaporative cooling of the droplet. The subsequent mixing of fluid vapour and ambient gas also remains subcritical in the direct vicinity of the droplet.Deutsche Forschungsgemeinschaf

    Domain-dependent surface adhesion in twisted few-layer graphene: Platform for moir\'e-assisted chemistry

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    Twisted van der Waals multilayers are widely regarded as a rich platform to access novel electronic phases, thanks to the multiple degrees of freedom such as layer thickness and twist angle that allow control of their electronic and chemical properties. Here, we propose that the stacking domains that form naturally due to the relative twist between successive layers act as an additional "knob" for controlling the behavior of these systems, and report the emergence and engineering of stacking domain-dependent surface chemistry in twisted few-layer graphene. Using mid-infrared near-field optical microscopy and atomic force microscopy, we observe a selective adhesion of metallic nanoparticles and liquid water at the domains with rhombohedral stacking configurations of minimally twisted double bi- and tri-layer graphene. Furthermore, we demonstrate that the manipulation of nanoparticles located at certain stacking domains can locally reconfigure the moir\'e superlattice in their vicinity at the {\mu}m-scale. In addition, we report first-principles simulations of the energetics of adhesion of metal atoms and water molecules on the stacking domains in an attempt to elucidate the origin of the observed selective adhesion. Our findings establish a new approach to controlling moir\'e-assisted chemistry and nanoengineering.Comment: 11 pages, 3 figure

    The Economics of Desertification, Land Degradation, and Drought Toward an Integrated Global Assessment

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    Since the publication of the Report of the Brundtland Commission (Our Common Future) in 1987, and the consequent Earth Summit on sustainable development, global attention on natural resource scarcity and degradation has been increasing, because of climate change and rising food and energy prices. This awareness, in turn, has led to growing interest in land investments by the private and public sectors. Despite this interest, however, land degradation has not been comprehensively addressed at the global level or in developing countries. A suitable economic framework that could guide investments and institutional action is lacking. This study aims to overcome this deficiency and to provide a framework for a global assessment based on a consideration of the costs of action versus inaction. Thus, a type of Stern Review (Stern 2006) for desertification, land degradation, and drought (DLDD) is aimed for on the basis of this study. The urgency of land degradation problems, the increased value of land, and new science insights all suggest that the time is ripe for a global assessment of the economics of DLDD (E-DLDD)

    O‐HEALTH‐EDU: A scoping review on the reporting of oral health professional education in Europe

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    Introduction The variability in oral health professional education is likely to impact on the management of oral health needs across Europe. This scoping review forms the initial part of a larger EU‐funded collaborative Erasmus+ project, ‘O‐Health‐Edu’. The aim of this scoping review is to investigate how oral health professional education in Europe is reported. Methods The PRISMA and Arksey & O’Malley methodological frameworks for scoping reviews were used to guide reviewers in answering the research question “How is oral health professional education reported in Europe?”. The search strategy encompassed published literature searches, internet searches and further searching of relevant documents from educational organisations, regulators and professional bodies. Once the search strategy was developed it was sent to key stakeholders for consultation. Sources were reviewed by two authors (JD, JF), and included in the review if they reported on oral health professional education in Europe. Results A total of 508 sources were retrieved from all of the searches. 405 sources were excluded as they did not report on the topic of interest, leaving 103 sources that reported on oral health professional education in Europe. Handsearching the references of published sources lead to a further 41 sources being screened, of which 15 were included. In total, 33 duplications were removed and the final number of included sources was 85. The average year of publication for the included sources was 2007, with sources most commonly published in journals dedicated to dental education. Surveys represented the most common form of reporting. From the data obtained, four broad themes of reporting were evident: Dental education at a Programme Level, Dental education at a Discipline Level, Other Oral Health Professional Education, and, Postgraduate Education and Continuous Professional Development. Conclusion The reporting of dental and oral health professional education in Europe is limited. Whilst there are many useful documents that provide guidelines on dental education, there is limited knowledge on how education is implemented and delivered. There is a greater need for comprehensive educationally driven programme level data on oral health professional education across Europe

    O-Health-Edu: A viewpoint into the current state of oral health professional education in Europe: Part 2: Curriculum structure, facilities, staffing and quality assurance

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    Oral health professional (OHP) education is likely to vary across Europe in accordance with an EU directive that is open to broad interpretation. It is not clear how OHP curricula are structured or delivered across Europe. The objectives of Part 2 of this paper series are: (i) to provide an overview of common practices in curriculum structure, the availability of facilities, staffing (faculty) and quality assurance processes and (ii) to consider how the existing programme structures align to stakeholder guidance documents

    Methadone, Buprenorphine, and Street Drug Interactions with Antiretroviral Medications

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    While street drugs appear unlikely to alter the metabolism of antiretroviral (ARV) medications, several ARVs may induce or inhibit metabolism of various street drugs. However, research on these interactions is limited. Case reports have documented life-threatening overdoses of ecstasy and gamma-hydroxybutyrate after starting ritonavir, an ARV that inhibits several metabolic enzymes. For opioid addiction, methadone or buprenorphine are the treatments of choice. Because a number of ARVs decrease or increase methadone levels, patients should be monitored for methadone withdrawal or toxicity when they start or stop ARVs. Most ARVs do not cause buprenorphine withdrawal or toxicity, even if they alter buprenorphine levels, with rare exceptions to date including atazanavir/ritonavir associated with significant increases in buprenorphine and adverse events related to sedation and mental status changes in some cases. There are newer medications yet to be studied with methadone or buprenorphine. Further, there are many frequently used medications in treatment of complications of HIV disease that have not been studied. There is need for continuing research to define these drug interactions and their clinical significance
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