131,717 research outputs found
The Impact of Institutional Differences on Derivatives Usage: A Comparative Study of US and Dutch Firms
No full textThis paper tests the influence of institutional differences on risk management practices.Several survey studies have investigated derivatives usage for risk management purposes in the US (see, among others, Bodnar, Hayt, Marston and Smithson, 1995 and Bodnar, Hayt and Marston, 1996, 1998).In this paper, we compare derivative practices of US and Dutch firms.This comparison is interesting because the institutional setting for Dutch firms differs from the US setting with respect to shareholder orientation, international trade, disclosure regulation, and the reliance on financial markets.In a number of survey studies additional countries have been studied, such as New Zealand (Berkman, Bradbury and Magan, 1997), Sweden (Alkebäck and Hagelin, 1999) and Germany (Bodnar and Gebhardt, 1999).In contrast with these papers, we facilitate a comparison by applying a matching and a weighting strategy, which corrects for different distributions over industry and size classes in the Dutch and US samples.After these corrections, the remaining results can be attributed to institutional differences.We find that Dutch firms hedge more financial risk. Because of the greater openness of the Netherlands, Dutch firms experience far more foreign exchange exposure and hedge more currency risk.US firms have more concerns regarding derivative usage, which may be linked to the stricter disclosure requirements in the US.US firms also focus more on accounting earnings, which may be attributable to the shareholder orientation in the US versus the stakeholder orientation in the Netherlands.Whereas Dutch firms tend to rely on OTC-transactions, US firms use exchange-traded derivatives and therefore require a higher counter party rating for derivatives transactions. This distinction can be accredited to the differences in the financial environments between the US and the Netherlands.The aforementioned results indicate that institutional differences between the US and the Netherlands have a significant effect on the risk management practices and derivatives use of US and Dutch firms.risk management;hedging;derivatives
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Zinc-mediated anionic cyclization of unstabilized ketone enolates with unactivated alkenes
No full textWe report herein general conditions for a zinc-mediated anionic cyclization of unstabilized ketone enolates. This anionic cyclization allows access to various carbocyclic architectures by utilizing abundant ketones and unactivated alkenes as precursors. The transformation is enabled by the use of Zn(TMP)2 as base and Zn(OTf)2 as an additive. The resulting alkylzinc species can be intercepted by electrophiles for tandem C–X and C–O bond formation
Long-term follow up of the Biocor (R) porcine bioprosthesis in the mitral position - Meeting discussion
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Fast charging techniques and compact integrated implementations for electrochemical double layer capacitors in portable applications
No full textThe widespread increase in the range and types of portable electronic devices in the past decades has resulted in higher requirements for energy storage and conversion modules. Most of these devices use rechargeable batteries as energy storage elements. No matter what type of batteries are used (Ni-Cd, Ni-MH, Li-Ion, etc.) they all have one serious drawback in common, in terms of charging time. Electrochemical double layer capacitors (EDLCs) also known as ultracapacitors or supercapacitors seem to have overcome this disadvantage, at the cost of lower energy storage capacity.This work aims to explore the design of fast and compact integrated charging techniques for ultracapacitors using the AC mains network as the source. The main constraints that arise are the power dissipation on-chip and in the magnetic components due to the large amount of energy that has to be transferred in a very short time interval. Two other limitations come from the EDLC side due to the device parasitics and the widely varying voltages over the operational envelope. This will impose the need for a flexible control system providing high efficiency over the whole output voltage range.The structure of this thesis comprises five main parts: literature review, behavioural modelling of the control system (including matlab simulations); implementation of the device with discrete components; design of an analogue circuit implementation and design of a mixed signal circuit implementation. As ultracapacitors represent one of the newest solutions in the field of electrical energy storage there are very few designs for chargers from the mains network. Therefore the literature review will also examine the properties and the modelling of EDLCs, as well as the choice of converter topologies available and the characteristics of the magnetic devices required for the system. The behavioural model of the control module gives a preview of the system parameters, while the design chapter introduces a series of new control techniques. The simulations and measurements of the breadboard circuit come as a first confirmation of the design approach and make it a viable starting point for an IC implementation. The analogue IC design presents the integration of the algorithms in a medium-voltage process using the current mode approach, as a demonstrator for a fully monolithic high-voltage IC. Once the functionality of the system is demonstrated at IC level, the mixed-signal system aims to optimize the device and provide a broader flexibility for the system parameters and control algorithms
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
The Interaction between Murine Dendritic Cell and Mycobacterium tuberculosis
No full textThe interaction of microbes with dendritic cells (DCs) is likely to have an enormous impact on the initiation of the immune response against a pathogen. In this study, we compared the interaction of Mycobacterium tuberculosis with murine bone marrow derived DCs and macrophages in vitro. M. tuberculosis grew equally well within non-activated DCs and MØ. Activation of DCs and MØ with IFN-g and LPS inhibited the growth of the intracellular bacteria in an NOS2-dependent fashion. However, while this activation enabled MØ to kill the intracellular bacteria, the M. tuberculosis bacilli within activated DCs were not killed. Thus, DC could restrict the growth of the intracellular mycobacteria, but were less efficient than macrophages at eliminating the infection. These results may have implications for priming immune responses to M. tuberculosis. In addition, they suggest that DCs may serve as a reservoir for M. tuberculosis in tissues, including lymph nodes and lungs. Dendritic cells (DC) possess anti-microbial mechanisms that may play a role in M. tuberculosis infection. Activated DC and MØ produce a comparable amount of reactive nitrogen intermediates, as measured by nitrite production but our data indicate that nitric oxide production is not directly responsible for the differences in the ability of DC and MØ to kill M. tuberculosis. Activated DC have the capacity to produce greater quantities of (reactive oxygen intermediate) ROI than activated MØ. The higher levels of ROI in infected DC may affect the formation of different (reactive nitrogen intermediate) RNI species, such as peroxynitrite, and alter the lethal effect on M. tuberculosis. In addition DC may not able to acidify their phagosomal compartment, where the bacilli reside, to the same degree as macrophages. This may contribute to the ineffectiveness of their anti-microbial compounds
Local Curricular Diffusion of Gamified Learning in First Year Engineering Curricula: A Case Study
No full textmplementation of educational innovations on a local scale requires consideration of a variety of different factors including stakeholders, curriculum design, classroom context, and culture. Although theories exist for dimensions of scale and diffusion of educational innovations across multiple institutions, they do not focus on the elements necessary to achieve a successful diffusion of a curricular innovation in a local context. This work leverages Actor Network Theory (ANT) and other theories on dimensions of scale to develop a framework for the local diffusion of a digital gamified homework platform called 3D GameLab. As a case study, we offer research findings around the key actors in the local curricula scale-up network and explore the relationships between these actors and how they work together to ensure an effective implementation. This model can be used as a guide for engineering education practitioners when seeking to expand the reach of their local educational innovations
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