58 research outputs found

    Thar she bursts - Reducing confusion reduces bubbles

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    To explore why bubbles frequently emerge in the experimental asset market model of Smith, Suchanek and Williams (1988), we vary the fundamental value process (constant or declining) and the cash-to-asset value-ratio (constant or increasing). We observe high mispricing in treatments with a declining fundamental value, while overvaluation emerges when coupled with an increasing C/A-ratio. A questionnaire reveals that the declining fundamental value process confuses subjects, as they expect the fundamental value to stay constant.Running the experiment with a different context (“stocks of a depletable gold mine” instead of “stocks”) significantly reduces mispricing and overvaluation as it reduces confusion.Experimental economics, asset market, bubble, market efficiency, confusion

    Motivations To Produce User Generated Content: Differences Between Webloggers And Videobloggers

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    This explorational study seeks to elucidate the question of what motivates weblogger and videoblogger to produce user generated content. Particular focus was laid on the question whether motivational differences can be discerned between webloggers and video producers and why people do not produce content. The findings show that it is the intrinsic motivations that are responsible for today’s user generated content. Video producers and webloggers differ in their motivations. Video production is more associated with fun and time passing than is weblogging. Weblogging is regarded as being more useful in the dissemination of information. The main reasons for not producing content are opportunity costs and privacy issues

    Southern Brazilian indigenous populations and the forest: towards an environmental history

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    Human societies and economies are inextricably linked to oceans and seas. Eight of the world’s ten largest cities lie adjacent to the ocean (UN Atlas of the Oceans, 2010) and about half of the world’s population lives within 200 km of a coast – a quarter within 100 km (IPCC, 2007). Oceans and seas provide a range of ecosystem services (including regulating, provisioning and cultural services) that enhance human well‐being in numerous ways (Millennium Ecosystem Assessment, 2003, 2005; Hicks, 2011). To the extent that climate change affects ecosystems, it will affect fisheries (as discussed in the preceding chapters of this book) and, by extension, human well‐being. In this chapter, we focus on provisioning and cultural services associated with fisheries. Although important, the ocean’s regulating and supporting services, including the fixation of atmospheric carbon, are not further discussed here (for further details, see UNEP‐WCMC, 2011). We describe the numerous contributions of marine‐based ecosystems to human well‐being and the ways in which climate change and other confounding factors are likely to disrupt relationships between fishers, fisheries and fishing communities. Our three case‐studies: small‐scale, artisanal and subsistence‐based fisheries of the western Indian Ocean (WIO), fishing of cultural keystone species in the Torres Strait, and commercial fishing in Australia, serve to highlight the various changes to fisheries likely to be brought about by climate change in three markedly different contexts

    Modeling and design of the vector control for a three-phase single-stage grid-connected PV system with LVRT capability according to the spanish grid code

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    This article deals with the vector control in dq axes of a three-phase grid-connected photovoltaic system with single-stage topology and low-voltage-ride-through capability. The photovoltaic generator is built using an array of several series-parallel Suntech PV modules and is modeled as a Lookup Table (two-dimensional; 2-D). The requirements adopted when grid voltage sags occur are based in both the IEC 61400-21 European normative and the allowed amount of reactive power to be delivered according to the Spanish grid code, which avoids the disconnection of the inverter under grid faults by a limitation in the magnitude of the three-phase output inverter currents. For this, the calculation of the positive- and negative-sequences of the grid voltages is made and a conventional three-phase Phase-Locked Loop is used for the inverter-grid synchronization, allowing the control of the active and reactive powers solely with the dq components of the inverter currents. A detailed enhanced flowchart of the control algorithm with low-voltage-ride-through capability is presented and several simulations and experiments using Matlab/SIMULINK and the Controller Hardware-in-the-Loop simulation technique, respectively, are run for several types of one- and three-phase voltage sags in order to validate its behavior.This work was supported by: the project "Nuevas topologias para convertidores en MT para grandes Instalaciones Fotovoltaicas" from the Spanish Government (Ref. TEC2016-80136-P) (A. B. Rey-Boue); the European Community's Horizon 2020 Program (H2020/2014-2020) in project "ERIGrid" (Grant Agreement No. 654113) under the Trans-national Access (TA) User Project: 04.003-2018

    Improved control of grid-connected DFIG-based wind turbine using proportional-resonant regulators during unbalanced grid

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    The quality of power and current control are the greatest challenges of grid-connected wind farms during abnormal conditions. The negative- and positive-sequence components of the grid currents may be injected into a wind generation system during grid faults, which can affect the power stability and damage the wind system. The proposed work assures a low-voltage ride through capability of doubly-fed induction generator- based wind turbines under the grid voltage sag. A new technique to protect the wind system and to recompense the reactive power during failures of the utility grid according to the Spanish grid code is proposed. The control design is implemented to the power converters, and the grid current regulation is developed by using proportional-resonant regulators in a stationary two-phase (alpha beta) reference frame. The control performance is significantly validated by applying the real-time simulation for the rotor-side converter and the hardware in the loop simulation technique for the experiment of the generator's grid-side converter control.This work was supported by: the project "Nuevas topologias para convertidores en MT para grandes Instalaciones Fotovoltaicas" from the Spanish Government (Ref. TEC2016-80136-P) (from A.B.R.); the European Community's Horizon 2020 Program (H2020/2014-2020) in project "ERIGrid" (grant ggreement No. 654113) under the Trans-national Access (TA) User Project (Ref. 04.003-2018); and the Erasmus + KA107 mobility program 2018/2019 between Europe and Morocco, Universidad Politecnica de Cartagena (UPCT) & Sidi Mohamen Ben Abdellah University (USMBA)-Fez (from Y.E.K.)

    The Crowding Out of Complex Social Goods

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    The valuation of ecosystem services to inform natural resource management and development has gained acceptance in many arenas. Yet, contemporary economic valuation is constrained to the appraisal of simple goods that generate benefits that accrue to individuals, neglecting complex goods that generate benefits that accrue to society more broadly. Methodological barriers to the valuation of complex social goods have led to their frequent omission from natural resource management deliberations. The prevailing valuation paradigm that focuses on simple individual goods may erode conservation efforts by crowding out the institutions and behaviours that support socially constructed ecosystem service values. Erosion of these values ultimately harms the environment and society as a whole. The institutionalisation of appropriate methods for estimating the value of complex social goods alongside existing methods for valuing simple individual goods within international conservation, development and policy-making discourses, is therefore an important evolution for sustainable natural resource management

    Performance and Mix Measurements of Indirect Drive Cu-Doped Be Implosions

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    The ablator couples energy between the driver and fusion fuel in inertial confinement fusion (ICF). Because of its low opacity, high solid density, and material properties, beryllium has long been considered an ideal ablator for ICF ignition experiments at the National Ignition Facility. We report here the first indirect drive Be implosions driven with shaped laser pulses and diagnosed with fusion yield at the OMEGA laser. The results show good performance with an average DD neutron yield of ~2 × 10[superscript 9] at a convergence ratio of R[subscript 0]/R ~ 10 and little impact due to the growth of hydrodynamic instabilities and mix. In addition, the effect of adding an inner liner of W between the Be and DD is demonstrated.United States. Dept. of Energy (Lawrence Livermore National Laboratory Contract DE-AC52-07NA27344

    Excision of HIV-1 Proviral DNA by Recombinant Cell Permeable Tre-Recombinase

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    Over the previous years, comprehensive studies on antiretroviral drugs resulted in the successful introduction of highly active antiretroviral therapy (HAART) into clinical practice for treatment of HIV/AIDS. However, there is still need for new therapeutic approaches, since HAART cannot eradicate HIV-1 from the infected organism and, unfortunately, can be associated with long-term toxicity and the development of drug resistance. In contrast, novel gene therapy strategies may have the potential to reverse the infection by eradicating HIV-1. For example, expression of long terminal repeat (LTR)-specific recombinase (Tre-recombinase) has been shown to result in chromosomal excision of proviral DNA and, in consequence, in the eradication of HIV-1 from infected cell cultures. However, the delivery of Tre-recombinase currently depends on the genetic manipulation of target cells, a process that is complicating such therapeutic approaches and, thus, might be undesirable in a clinical setting. In this report we demonstrate that E.coli expressed Tre-recombinases, tagged either with the protein transduction domain (PTD) from the HIV-1 Tat trans-activator or the translocation motif (TLM) of the Hepatitis B virus PreS2 protein, were able to translocate efficiently into cells and showed significant recombination activity on HIV-1 LTR sequences. Tre activity was observed using episomal and stable integrated reporter constructs in transfected HeLa cells. Furthermore, the TLM-tagged enzyme was able to excise the full-length proviral DNA from chromosomal integration sites of HIV-1-infected HeLa and CEM-SS cells. The presented data confirm Tre-recombinase activity on integrated HIV-1 and provide the basis for the non-genetic transient application of engineered recombinases, which may be a valuable component of future HIV eradication strategies
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