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Search Results: 1 - 10 of 177826 matches for " Erik de Vries "
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Supercharges, Quantum States and Angular Momentum for N=4 Supersymmetric Monopoles
Erik Jan de Vries,Bernd J. Schroers
Physics , 2010, DOI: 10.1016/j.nuclphysb.2010.06.013
Abstract: We revisit the moduli space approximation to the quantum mechanics of monopoles in N=4 supersymmetric Yang-Mills-Higgs theory with maximal symmetry breaking. Starting with the observation that the set of fermionic zero-modes in N=4 supersymmetric Yang-Mills-Higgs theory can be viewed as two copies of the set of fermionic zero-modes in the N=2 version, we build a model to describe the quantum mechanics of N=4 supersymmetric monopoles, based on our previous paper [1] on the N=2 case, in which this doubling of fermionic zero-modes is manifest throughout. Our final picture extends the familiar result that quantum states are described by differential forms on the moduli space and that the Hamiltonian operator is the Laplacian acting on forms. In particular, we derive a general expression for the total angular momentum operator on the moduli space which differs from the naive candidate by the adjoint action of the complex structures. We also express all the supercharges in terms of (twisted) Dolbeault operators and illustrate our results by discussing, in some detail, the N=4 supersymmetric quantum dynamics of monopoles in a theory with gauge group SU(3) broken to U(1) x U(1).
Competition between Influenza A Virus Genome Segments
Ivy Widjaja,Erik de Vries,Peter J. M. Rottier,Cornelis A. M. de Haan
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047529
Abstract: Influenza A virus (IAV) contains a segmented negative-strand RNA genome. How IAV balances the replication and transcription of its multiple genome segments is not understood. We developed a dual competition assay based on the co-transfection of firefly or Gaussia luciferase-encoding genome segments together with plasmids encoding IAV polymerase subunits and nucleoprotein. At limiting amounts of polymerase subunits, expression of the firefly luciferase segment was negatively affected by the presence of its Gaussia luciferase counterpart, indicative of competition between reporter genome segments. This competition could be relieved by increasing or decreasing the relative amounts of firefly or Gaussia reporter segment, respectively. The balance between the luciferase expression levels was also affected by the identity of the untranslated regions (UTRs) as well as segment length. In general it appeared that genome segments displaying inherent higher expression levels were more efficient competitors of another segment. When natural genome segments were tested for their ability to suppress reporter gene expression, shorter genome segments generally reduced firefly luciferase expression to a larger extent, with the M and NS segments having the largest effect. The balance between different reporter segments was most dramatically affected by the introduction of UTR panhandle-stabilizing mutations. Furthermore, only reporter genome segments carrying these mutations were able to efficiently compete with the natural genome segments in infected cells. Our data indicate that IAV genome segments compete for available polymerases. Competition is affected by segment length, coding region, and UTRs. This competition is probably most apparent early during infection, when limiting amounts of polymerases are present, and may contribute to the regulation of segment-specific replication and transcription.
Traumatic lingual ulceration in a newborn: Riga-Fede disease
Erik H van der Meij, Tjalling W de Vries, Henk F Eggink, Jan GAM de Visscher
Italian Journal of Pediatrics , 2012, DOI: 10.1186/1824-7288-38-20
Abstract: Beside the presentation of a six-month-old boy with Riga Fede disease, the literature has been reviewed as well. From this review it can be concluded that Riga Fede disease is almost exclusively restricted to the tongue, occurs soon after birth when associated with (neo)natal teeth, has a male predilection, and is in one quarter of the cases associated with neurologic disorders. In the later case, Riga Fede disease develops after the age of 6?months.
Radiopharmaceuticals for imaging chronic lymphocytic inflammation
Malviya, Gaurav;Vries, Erik F.J. de;Dierckx, Rudi A.;Signore, Alberto;
Brazilian Archives of Biology and Technology , 2007, DOI: 10.1590/S1516-89132007000600002
Abstract: in the last few decades, a number of radiopharmaceuticals for imaging inflammation have been proposed that differ in their specificity and mechanism of uptake in inflamed foci as compared to the traditional inflammation imaging agents. radiolabelled cytokines represent a reliable tool for the preclinical diagnosis of chronic inflammatory processes, even before anatomical and functional changes occur in affected tissues. moreover, the introduction of radiolabelled monoclonal antibodies and sophisticated technique like pet/ct now make the field of inflammation imaging highly specific and accurate. in this review, different approaches of the established and experimental radiopharmaceuticals for imaging of chronic inflammation are discussed.
Profile Matching in Electronic Social Networks Using a Matching Measure for Fuzzy Numerical Attributes and Fields of Interests  [PDF]
Andreas de Vries
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.516250
Abstract: The problem of profile matching in electronic social networks asks to find those offering profiles of actors in the network fitting best to a given search profile. In this article this problem is mathematically formulated as an optimization problem. For this purpose the underlying search space and the objective function are defined precisely. In particular, data structures of search and offering profiles are proposed, as well as a function measuring the matching of the attributes of a search profile with the corresponding attributes of an offering profile. This objective function, given in Equation (29), is composed of the partial matching degrees for numerical attributes, discrete non-numerical attributes, and fields of interests, respectively. For the matching degree of numerical profile attributes a fuzzy value approach is presented, see Equation (22), whereas for the matching degree of fields of interest a new measure function is introduced in Equation (26). The resulting algorithm is illustrated by a concrete example. It not only is applicable to electronic social networks but also could be adapted for resource discovery in grid computation or in matchmaking energy demand and supply in electrical power systems and smart grids, especially to efficiently integrate renewable energy resources.
An Investigation of the Secular Acceleration of Psychiatric Disorders  [PDF]
Sebastian Lemke, Sunka De Vries
Open Journal of Psychiatry (OJPsych) , 2015, DOI: 10.4236/ojpsych.2015.51013
Abstract: Secular acceleration, for example an increase in height in groups of people over a period of time of more than a century, is a unique, perhaps “ecological” event. In the study presented here, historical patient files from the Jena Psychiatric Clinic were evaluated in relation to the problem of acceleration. A first sampling of 119 patient files for the years 1880-1890 revealed that, for children and adolescents up until the end of their twentieth year of life, the average age at the time of their first admission was 17 years. Compared to this, the first admission of a second sample of 132 patient records for the years 1985-1987 revealed a clearly younger average age at first admission of 11 years. This difference in age was found to be statistically significant. The heights of 14-year-old subjects from the city of Jena for the years 1880 to 1975 obtained from the literature showed a documented increase in height of almost 20 cm. The results of our investigation revealed that, in addition to physical acceleration, there was also an advancement of pathological mental processes in the course of a period of 100 years.
Electricity Market Mechanism regarding the Operational Flexibility of Power Plants  [PDF]
Cem Kiyak, Andreas de Vries
Modern Economy (ME) , 2017, DOI: 10.4236/me.2017.84043
Abstract: Electricity market mechanisms designed to steer sustainable generation of electricity play an important role for the energy transition intended to mitigate climate change. One of the major problems is to complement volatile renewable energy sources by operationally flexible capacity reserves. In this paper, a proposal is given to determine prices on electricity markets taking into account the operational flexibility of power plants, such that the costs of long-term capacity reserves can be paid by short-term electricity spot markets. For this purpose, a measure of operational flexibility is introduced enabling to compute an inflexibility fee charging each individual power plant on a wholesale electricity spot market. The total sum of inflexibility fees is accumulated on the spot markets and then can be used to finance a capacity mechanism keeping the necessary reserves to warrant grid reliability. Here each reserve power plant then gets a reliable payment depending on its operational flexibility. The proposal is applied to an exemplary small grid, illustrating its main idea and also revealing the caveat that too high fees paradoxically could create incentives to employ highly flexible power plants on the spot market rather than to run them as backup capacity.
Seaweeds as Biomonitoring System for Heavy Metal (HM) Accumulation and Contamination of Our Oceans  [PDF]
Vincent van Ginneken, Evert de Vries
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.97111
Abstract: This research manuscript reports the heavy metal accumulation in four marine seaweeds sp. 1)?Caulerpa sertlatioides (Cuba); 2) Caulerpa cf. brachypus; (Bali, Indonesia); 3) Undaria pinnatifida (West-Donegal, Ireland); 4) Ulva lactuca (Easters-Scheldt, the Netherlands). Mechanical pressure at 10 bar of fresh seaweed fronds
Dissection of the Influenza A Virus Endocytic Routes Reveals Macropinocytosis as an Alternative Entry Pathway
Erik de Vries,Donna M. Tscherne,Marleen J. Wienholts,Viviana Cobos-Jiménez,Florine Scholte,Adolfo García-Sastre,Peter J. M. Rottier,Cornelis A. M. de Haan
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1001329
Abstract: Influenza A virus (IAV) enters host cells upon binding of its hemagglutinin glycoprotein to sialylated host cell receptors. Whereas dynamin-dependent, clathrin-mediated endocytosis (CME) is generally considered as the IAV infection pathway, some observations suggest the occurrence of an as yet uncharacterized alternative entry route. By manipulating entry parameters we established experimental conditions that allow the separate analysis of dynamin-dependent and -independent entry of IAV. Whereas entry of IAV in phosphate-buffered saline could be completely inhibited by dynasore, a specific inhibitor of dynamin, a dynasore-insensitive entry pathway became functional in the presence of fetal calf serum. This finding was confirmed with the use of small interfering RNAs targeting dynamin-2. In the presence of serum, both IAV entry pathways were operational. Under these conditions entry could be fully blocked by combined treatment with dynasore and the amiloride derivative EIPA, the hallmark inhibitor of macropinocytosis, whereas either drug alone had no effect. The sensitivity of the dynamin-independent entry pathway to inhibitors or dominant-negative mutants affecting actomyosin dynamics as well as to a number of specific inhibitors of growth factor receptor tyrosine kinases and downstream effectors thereof all point to the involvement of macropinocytosis in IAV entry. Consistently, IAV particles and soluble FITC-dextran were shown to co-localize in cells in the same vesicles. Thus, in addition to the classical dynamin-dependent, clathrin-mediated endocytosis pathway, IAV enters host cells by a dynamin-independent route that has all the characteristics of macropinocytosis.
Surgical Challenges in Lymphatic Filariasis
CR de Vries
African Journal of Urology , 2004,
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