34 research outputs found

    Indirect effects - a formal definition and degrees of dependency as an alternative to technical coefficients

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    The use of input-output analysis for the computation of secondary effects of final demand changes is well-known. These 'final demand effects' can be calculated using technical coefficients and the inverse of the Leontief matrix. This paper offers an alternative to the use of technical coefficients. Its goal is threefold. First of all degrees of dependency are defined and it is shown how they can be used to compute secondary effects. Their definition is based on an input-output table. Secondly the concept of secondary effects is extended to what is called indirect effects. These indirect effects are not only related to final demand but to total industry output. It is shown how these indirect effects can be calculated using technical coefficients or degrees of dependency. The method used is a variant of the so-called Hypothetical Extraction Methods. Double counting is avoided, as such the resulting multipliers are 'net multipliers'. It is formally demonstrated that technical coefficients and degrees of dependency give the same results when a recent input-output table is available. If this is not the case then the results are different. It is impossible to say which of the two estimates is better. Since technical coefficients are already broadly accepted, some examples are given to justify the use of degrees of dependency. Finally it is explained how the unavailability of an input-output table can be solved. Starting from the supply-use tables a 'quick and dirty method' to infer an input-output table is provided. This topic is justified by the fact that for Belgium input-output tables are only published for those years that are divisible by five, with a three year lag. A short empirical analysis, based on currently available data, shows that technical coefficients and degrees of dependency have comparable performance, with a slight advantage for the technical coefficients. This performance is measured relative to a 'right' result, being the indirect effects for the year 2000 computed using the now available input-output table for the year 2000. This result is called 'right' because it does not make any assumptions on stability of technical coefficients nor of degrees of dependency. The empirical analysis also compares the use of a recent supply-use table to the use of an old input-output table. Supply-use tables on average overestimate the 'right' result. They are however often closest to the 'right' result at the first level. Since these conclusions are based on limited data further analysis is required as more data becomes available.indirect effects, input-output analysis, degrees of dependency, technical coefficients, net multiplier

    Density Functional Theory of doped superfluid liquid helium and nanodroplets

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    During the last decade, density function theory (DFT) in its static and dynamic time dependent forms, has emerged as a powerful tool to describe the structure and dynamics of doped liquid helium and droplets. In this review, we summarize the activity carried out in this field within the DFT framework since the publication of the previous review article on this subject [M. Barranco et al., J. Low Temp. Phys. 142, 1 (2006)]. Furthermore, a comprehensive presentation of the actual implementations of helium DFT is given, which have not been discussed in the individual articles or are scattered in the existing literature. This is an Accepted Manuscript of an article published on August 2, 2017 by Taylor & Francis Group in Int. Rev. Phys. Chem. 36, 621 (2017), available online: http://dx.doi.org/10.1080/0144235X.2017.1351672Comment: 113 pages, 42 figure

    The Economic Impacts of Port Activity in Antwerp: A Disaggregated Analysis

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    The importance of ports is usually measured by indicators such as added value, employment and investment on a much aggregated level. This paper tries to define the importance of the port of Antwerp for the regional and national economy on a disaggregated level. It attempts to identify, quantify and locate the mutual relationships between the different players in the port and between these players and other industries. Finally, it proposes a method to calculate the effects of changes in port activity at a detailed level. A sector analysis is done by means of a reduced regional input-output table, through a bottom-up approach. The most important customers and suppliers of the port's key players or stakeholders are identified. A geographical analysis is feasible by using data on a disaggregated level. Each customer or supplier can be located by means of their postcode. In this way, the extent of the economic impact of the port of Antwerp is quantified.

    Alkali atoms attached to vortex-hosting helium nanodroplets

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    Light absorption or fluorescence excitation spectroscopy of alkali atoms attached to 4He droplets is investigated as a possible way for detecting the presence of vortices. To this end, we have calculated the equilibrium configuration and energetics of alkali atoms attached to a 4He1000 droplet hosting a vortex line using 4He density functional theory. We use them to study how the dipole absorption spectrum of the alkali atom is modified when the impurity is attached to a vortex line. Spectra are found to be blue-shifted (higher frequencies) and broadened compared to vortex-free droplets because the dimple in which the alkali atom sits at the intersection of the vortex line and the droplet surface is deeper. This effect is smaller for lighter alkali atoms and all the more so when using a quantum description since, in this case, they sit further away from the droplet surface on average due to their zero-point motion. Spectral modifications due to the presence of a vortex line are minor for np ← ns excitation and therefore insufficient for vortex detection. In the case of higher n′p ← ns or n′s ← ns (n′ > n) excitations, the shifts are larger as the excited state orbital is more extended and therefore more sensitive to changes in the surrounding helium density

    Fall-back time for photo-ionized Cs atoms attached to superfluid He-4 nanodroplets

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    We have studied the dynamic evolution of a Cs atom photo-excited from 6s to 6p and 7s states on a helium droplet using time-dependent 4He-DFT simulations. Depending on the excited electronic state, the Cs impurity remains on the droplet surface or it is ejected. Upon subsequent photo-ionization of the excited Cs atom the resulting Cs+ cation may either be ejected or come back to the droplet, depending on the time delay between photo-excitation and photo-ionization. We have calculated the critical time delay separating these two different behaviors, as well as final ion velocities. These observables will be used for future comparison with planned pump-probe experiments

    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

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    In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

    The single European electricity market: A long road to convergence. NBB Working Paper Nr. 84, May 2006

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    In the context of a first Working Paper the authors argued that electricity has a number of characteristics that set it apart from other commodities. It was demonstrated that some of these characteristics might complicate the deregulation process. This paper analyses the ongoing deregulation process in the European electricity sector and attempts to establish whether these difficulties can more readily be solved at European level. It would appear that some problems, e.g. economies of scale in electricity generation, have less of an impact at European level than within smaller national markets. However, a number of difficulties have to be overcome before a unified European electricity market can become a reality. These include the limited interconnection capacities between Member States. The European Commission has taken steps to improve the situation, for example by offering financial support for investments and promoting the development of regional markets as an interim measure ultimately leading to a fully integrated market. Apart from the difficulties related to electricity generation and transmission there are also exogenous factors that influence the ongoing deregulation process, e.g. the implementation of the Kyoto protocol and the dramatic increases in primary fuel prices. This paper argues that a consistent, stable and uniform European regulatory framework must be put in place if the impact of these difficulties is to be minimised

    A Possible Source of Error in 14C Dates: Volcanic Emanations (Examples from the Monte Amiata District, Provinces of Grosseto and Sienna, Italy)

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    Wood from regular timbering of a shallow seated mine in Tuscany gave 14C ages of 5730 +/- 100 years BP, much too old to be attributed to one of the known civilizations of Italy. This mine is located in a region of declining volcanic activity, noticeable especially through numerous emanations (natural or incidentally induced by drillings). It was suspected that the analyzed wood had grown in an environment where the normal atmosphere had been diluted by volcanic emanations. To check this hypothesis, living plants (trees, bushes and reeds) and volcanic emanations have been sampled and their 14C content measured. All present day plants are depleted in 14C, giving a fictitious age different from 0 (1805, 1820, 2540, 4350 years BP). Of the gaseous emanations sampled, two have a high pressure and show virtually no 14C (>41,000 years BP). Two others have a pressure close to atmospheric, and small amounts of 14C were introduced by atmospheric contamination (22,570 and 30,580 years BP). Conclusion: plants grown in the vicinity of volcanic emanations have 14C activities that are too low because of a natural 14C dilution and yield anomalously high ages. The delta-13C values obtained for two of these plants (-27.4 per mil and -23.7 per mil) are close to the average for plants in general (-25 per mil), whereas the CO2 of mofettes is heavier than atmospheric CO2.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

    Delftia tsuruhatensis TC1 symbiont suppresses malaria transmission by anopheline mosquitoes

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    Malaria control demands the development of a wide range of complementary strategies. We describe the properties of a naturally occurring and non-genetically modified symbiotic bacterium, Delftia tsuruhatensis TC1, which was isolated from mosquitoes incapable of sustaining the development of Plasmodium falciparum parasites. D. tsuruhatensis TC1 inhibits early stages of Plasmodium development and subsequent transmission by the Anopheles mosquito via secretion of a small molecule inhibitor. We have identified the inhibitor as a small hydrophobic molecule, harmane. We also found that on mosquito contact, harmane penetrates the cuticle, resulting in the inhibition of Plasmodium development. D. tsuruhatensis TC1 stably populates the mosquito gut, does not impose a fitness cost to the mosquito, and inhibits Plasmodium development for the mosquito’s life. Contained field studies in Burkina Faso and modelling showed that D. tsuruhatensis TC1 has the potential to complement mosquito-targeted malaria transmission control
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