32 research outputs found
A rationale for the payback criterion
No full textTextbooks on financial management have emphasized the shortcomings of the payback criterion for decades. However, empirical evidence suggests that in actual capital budgeting procedures the payback method is used quite regularly. Mostly, it is implemented supplementary to net present value or internal rate of return, but small companies tend to rely on payback times as single criterion. A convincing theoretical foundation for the observed use of the payback criterion is lacking. Consequently, our goal is to provide such an explanation for the payback criterion’s popularity. We demonstrate from a decision theoretical perspective how relying on payback times simplifies investment decisions in modern organizations. Gathering information from different management levels and ensuring the utilization of individual skills requires a multi-stage capital budgeting process. Accordingly, we consider fundamental organizational features of this process with respect to their impact on the payback method’s use. For this purpose, we built upon almost stochastic dominance (ASD) as modeling device. Firstly, we show that applying his concept allows to include the risk preferences of all relevant decision makers into the analysis. Secondly, we illustrate that the criteria derived from this model help conveying these preferences to those who do the preparatory work preceding the final decision. To some extent, these new criteria are generalizations of payback times. This finding provides a potential explanation for the payback’s persisting prominence.
Relict Bettongia lesueur warrens in Western Australian deserts
No full textThe Boodie or Burrowing Bettong Bettongia lesueur became extinct on the Australian mainland by about 1960 but, in some areas, left evidence of its previous distribution in the form of relict landscape features, which remain widespread in arid areas with hard soils. We recorded the location of landscape features ('mounds'), which we attributed to B. lesueur, in the western deserts during the 1980s and 1990s. There were two types of mounds - large, irregular shaped mounds of calcrete or clayey soils that were accumulated spoil from warren digging and smaller, regular, and largely circular mounds on lateritic surfaces. We mapped mounds, which are visible as obvious features in an otherwise often monotonous landscape, during vehicular traverses of desert tracks over a 10-15 year period. Mound density along one 215 km traverse in the northern Gibson Desert was 5.9±0.96 km-2. We measured attributes of both types of mound in the Gibson Desert. The former persist as warrens (often occupied by Rabbits Oryctolagus cuniculus), have many entrances, are often large in aerial extent, and often associated with rock capping. The latter are largely symmetrical mounds, smaller (typically < 20 m in diameter), and with soil penetrability typically far greater than surrounding soil that often has a hard pan
Is conceptual vagueness an asset? Resilience research from the perspective of philosophy of science
No full textI analyze the research on social-ecological resilience from the perspective of philosophy of science in three steps. First, I explore to what degree resilience research exhibits conceptual vagueness. I find a wide spectrum of research, ranging from approaches relying on a concise conceptual framework to the perspective of “resilience thinking”, which builds on a cluster of vague concepts. Second, I set out the methodological arguments in favor and against conceptual vagueness. Merging both strands of reasoning in the third step, I conclude that a trade-off between vagueness and precision exists, which is to be solved differently depending on the context of resilience research. In some contexts, resilience research benefits from conceptual vagueness while in others it depends on precision. Specifically, I argue that in “resilience thinking” the trade-off might be enhanced by a coherent restructuring of the conceptual framework.vagueness, philosophy of science, precision, resilience thinking, socialecological systems
Explosion hazards of aluminum finishing operations
No full textMetal dust deflagrations have become increasingly common in recent years. They are also more devastating than deflagrations involving organic materials, owing to metals' higher heat of combustion, rate of pressure rise, explosion pressure and flame temperature. Aluminum finishing operations offer a particularly significant hazard from the very small and reactive aluminum particles generated, and thus require high attention to details of operation and explosion safety management. This paper presents available statistics on metal dust explosions and studies the specific explosion hazards of aluminum finishing operations. The analysis of seven case studies shows that the proper design, monitoring and maintenance of dust collection systems are particularly important. Furthermore, the isolation of deflagrations occurring in dust collection systems, as well as good housekeeping practices in buildings, are critical safeguards to avoid the occurrence of catastrophic secondary explosions.Fluid MechanicsChemE/Delft Ingenious Desig
Metal dusts explosion hazards and protection
No full textMany industrial processes handle, use, or produce metallic particles small enough to explode in air, thus posing severe explosion hazards. Finishing operations, for example, create very fine particles and have been involved in a growing number of accidents in recent years. New emerging processes, such as 3D printing, are being rapidly developed and directly use micrometric particles to create complete objects by welding layers of material together. Finely divided metals also enter into the composition of plastics, rubber, fibers, paints, coatings, inks, pesticides, detergents, and even drugs; additionally, they are used as catalysts for major industrial chemical reactions, and are even being explored as possible clean alternatives to fossil fuels. Metal dusts are of special concern due to their peculiar combustion properties, including their higher heat of combustion and pyrophoric nature,. As a result, metal dusts explosions are often much more devastating than explosions involving organic materials. Additionally, due to their high reactivity, many fine and most ultra-fine metal powders can burn in carbon dioxide, water vapor and even nitrogen. Whereas preventive measures may reduce explosion risks efficiently, they rarely are sufficient to eliminate explosions completely, especially when dealing with highly reactive metallic particles. Therefore explosion protection measures usually also need to be considered. The high energetic content of metal dusts poses new challenges to conventional explosion protection systems in terms of robustness and response time. This paper reviews the special hazards of metal dusts and presents the state-of-the-art in terms of explosion protection.ISBN 978-88-95608-74-7Fluid MechanicsChemE/Delft Ingenious Desig
Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization.
No full textThe QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD
A Master on the Move
No full textAuthor describes the process of moving Dali's works into their new home using ""Galacidalacidesoxiribunucleicacid"" as an example of the process from start to finish. She also includes facts and information on the overall move as well as photos of the painting being hung at the new museum
The initial morphological response of the Sand Engine: A process-based modelling study
No full textAbstractSand nourishments are presently widely applied to maintain or enhance coastal safety and beach width. Over the last decades, global sand nourishment volumes have increased greatly, and the demand for nourishments is anticipated to increase further in coming decades due to sea level rise. With the increase in nourishment size and the request for more complex nourishment shapes, an adequate prediction of the morphodynamic evolution is of major importance. Yet, neither the skill of current state-of-the-art models for such predictions nor the primary drivers that control the evolution are known. This article presents the results of a detailed numerical modelling study undertaken to examine the model skill and the processes governing the initial morphological response of the Sand Engine and the adjacent coastline. The process-based model Delft3D is used to hindcast the first year after completion of the mega-nourishment. The model reproduces measured water levels, velocities and nearshore waves well. The prediction of the morphological evolution is consistent with the measured evolution during the study period, with Brier Skill Scores in the ‘Excellent’ range. The model results clearly indicate that the sand eroded from the main peninsular section of the Sand Engine is deposited along adjacent north and south coastlines, accreting up to 6km of coastline within just one year. Analysis of model results further show that the erosional behaviour of the Sand Engine is linearly dependent on the cumulative wave energy of individual high energy wave events, with the duration of a storm event being more dominant than the maximum wave height occurring during the storm. The integrated erosion volume due to the 12 events with the highest cumulative wave energy density accounts for about 60% of the total eroded volume of the peninsula, indicating that the less energetic wave events, with a higher probability of occurrence, are also important for the initial response of the Sand Engine. A structured model experiment using the verified Delft3D model indicates that wave forcing dominates the initial morphological response of the Sand Engine, accounting for approximately 75% of the total erosion volume in the first year. The vertical tide is the second most important factor accounting for nearly 17% of the total erosion volume, with surge, wind and horizontal tide playing only a minor role
A Tale of Three Countries: Italian, Spanish and Swiss Manufacturing Operations in China
No full textIn this paper we investigate the choice of FDI versus joint-venture, made by Italian, Spanish and Swiss multinationals in China, as shaped by the risk of Dissipation of Intangible Assets. Probit estimates, based on an entirely new firm-level dataset, constructed by the author, show that FDI is more likely to emerge when know-how easily spills over - namely for firms endowed with more Intangible Assets or belonging to high tech sectors - in line with the theoretical expectations.Intangible Assets, Internalisation, FDI, Joint-venture, China
Identification of heart rate-associated loci and their effects on cardiac conduction and rhythm disorders
No full textElevated resting heart rate is associated with greater risk of cardiovascular disease and mortality. In a 2-stage meta-analysis of genome-wide association studies in up to 181,171 individuals, we identified 14 new loci associated with heart rate and confirmed associations with all 7 previously established loci. Experimental downregulation of gene expression in Drosophila melanogaster and Danio rerio identified 20 genes at 11 loci that are relevant for heart rate regulation and highlight a role for genes involved in signal transmission, embryonic cardiac development and the pathophysiology of dilated cardiomyopathy, congenital heart failure and/or sudden cardiac death. In addition, genetic susceptibility to increased heart rate is associated with altered cardiac conduction and reduced risk of sick sinus syndrome, and both heart rate-increasing and heart rate-decreasing variants associate with risk of atrial fibrillation. Our findings provide fresh insights into the mechanisms regulating heart rate and identify new therapeutic targets
