3,177 research outputs found
DNA methylation in Dictyostelium discoideum
No full textPublications: Kuhlmann M*, Borisova BE*, Kaller M, Larsson P, Stach D, Na J, Eichinger L, Lyko F, Ambros V, Söderbom F, Hammann C, Nellen W.
Silencing of retrotransposons in Dictyostelium by DNA methylation and RNAi.
NAR, 2005 Vol.33, 6405-6417
* The first two authors equally contributed to this work
Critical Casimir effect in classical binary liquid mixtures
No full textIf a fluctuating medium is confined, the ensuing perturbation of its fluctuation spectrum generates Casimir-like effective forces acting on its confining surfaces. Near a continuous phase transition of such a medium the corresponding order parameter fluctuations occur on all length scales and therefore close to the critical point this effect acquires a universal character, i.e., to a large extent it is independent of the microscopic details of the actual system. Accordingly it can be calculated theoretically by studying suitable representative model systems. We report on the direct measurement of critical Casimir forces by total internal reflection microscopy with femtonewton resolution. The corresponding potentials are determined for individual colloidal particles floating above a substrate under the action of the critical thermal noise in the solvent medium, constituted by a binary liquid mixture of water and 2,6-lutidine near its lower consolute point. Depending on the relative adsorption preferences of the colloid and substrate surfaces with respect to the two components of the binary liquid mixture, we observe that, upon approaching the critical point of the solvent, attractive or repulsive forces emerge and supersede those prevailing away from it. Based on the knowledge of the critical Casimir forces acting in film geometries within the Ising universality class and with equal or opposing boundary conditions, we provide the corresponding theoretical predictions for the sphere-planar wall geometry of the experiment. The experimental data for the effective potential can be interpreted consistently in terms of these predictions and a remarkable quantitative agreement is observed
Using astronomical data to derive flux predictions for the annihilation of Dark Matter in the Local Group
Get PDFThe Dark Matter distribution inside the halos is a still unsolved cosmological issue. N-body simulations data, which are usually assumed to represent the Dark Matter shape inside the halos, suffer from the bug of fitting all types of Galaxy with a universal profile, without taking into account the peculiar properties of each Galaxy. In this work we extract informations on the Dark Matter distribution for the four closest and most Dark Matter dominated dwarf spheroidal galaxies of the Local Group, and we shape the density profile according to the available data. We then make a prediction for the γ-ray flux arising from the annihilation of Dark Matter in these structures, and study the experimental sensitivity of a GLAST-like satellite to these sources
Indirect detection of clumps inside the Milky Way with GLAST-like satellites: a closer look
No full textWithin the Cold Dark Matter scenario of structure formation, assuming the dark matter is composed by common candidates such as supersymmetric particles, the smallest bound structures have masses as low as 10-6. High-resolution N-body experiments have shown that a large fraction of these small structures survive hierarchical clustering and can be found within the halo of our own Galaxy. These clumps are expected to boost up significantly the expected annihilation signal. In this work we perform a thorough analysis of the prospects for indirect detection of these objects with GLAST-like experiments, exploring different prescriptions for the formation and evolution of dark matter clumps, and allowing the sub-halos shape parameters to vary within the range currently allowed by numerical simulations. Our results show that an experiment like GLAST can detect the annihilation signal if the subhalo mass distribution within our Galaxy is as clumpy as in the more optimistic, yet not unrealistic, cases we have explored. We also show that the annihilation signal comes preferably from the top-massive (in the range [108,109] or [104,109] Msun, depending on the model) rather than the many lightest (10-6 Msun) sub-Galactic clumps
On the liability of the uninformed taxable person in EU VAT
No full textIn this contribution, the author analyses the information need of the taxable person in EU value added tax (VAT). He explores the extent to which the taxable person depends, in the course of taxation, on the provision of information that is held by others. In addition, the author discusses EU Court of Justice (ECJ) case law in order to establish whether the taxable person can be held liable for the payment of VAT in case that person is unable to obtain all necessary information.</p
Unpaid tax collectors: the ‘public’ function of private parties in EU VAT
No full textThis contribution centres on the legal position of private parties ('VAT entrepreneurs') who are tasked with the collection of Value Added Tax (VAT) on behalf of the public authorities. The author discusses the main characteristics of the EU VAT system, and concludes that the VAT entrepreneurs do not have at their disposal any of the investigative competences that traditional fiscal public bodies such as the tax authorities enjoy (e.g. the possibility of instigating tax audits). As such, they are exposed to the risk of not having sufficient information to apply VAT to their transactions in line with the legal requirements - potentially leading to double taxation, non-taxation, and other adversities. The central research aim of this contribution is to establish whether VAT entrepreneurs should, with regard to their 'public' function as unpaid tax collectors, enjoy information procurement prerogatives similar to those enjoyed by conventional tax authorities. To that end, the author explores various options to reinforce the information procurement capabilities of VAT entrepreneurs
Scaling factor for the A-ref1 configuration of the SWGO array
No full textSeveral air shower observables exhibit sensitivity to the geometric layout of the detector array. In this note, we present an analysis of the A-ref1 configuration within the SWGO (The Southern Wide-field Gamma-ray Observatory) array. The results yield a crucial scaling factor that establishes a linkage for these observables between the central and outrigger arrays.Examining the A-ref1 configuration helps reveal how array geometry impacts observable outcomes. The conclusions highlight the importance of understanding and considering these geometric effects when interpreting air shower data.Fil: Vergara Quispe, Indira Dajhana. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Hansen, Patricia Maria. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Nellen, L.. Universidad Nacional Autónoma de México; MéxicoFil: Mariazzi, Analisa Gabriela. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Melo, Diego Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Tecnología en Detección y Astropartículas. Comisión Nacional de Energía Atómica. Instituto de Tecnología en Detección y Astropartículas. Universidad Nacional de San Martín. Instituto de Tecnología en Detección y Astropartículas; Argentin
(I) Onderzoekingen over steenkolenteer, door dr. Ir. F. J. Nellensteyn, directeur van het laboratorium voor chemisch-technisch onderzoek van bouwstoffen voor den wegenbouw te delft: (II) De analyse van verhard beton, door ir. R. Loman, ingenieur van den rijkswaterstaat
No full textErratum to “Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory” [Astroparticle Physics 32(2) (2009), 89-99]
Get PDFThe affiliations were incorrectly published in the original version of this article for the following authors D. Allard, J.A. Bellido, R.M. Kieckhafer, L. Nellen, R. Pelayo, I. Rodriguez-Cabo, B.E. Smith, D. Veberic, L. Wiencke, D. Zavrtanik and M. Zavrtanik which has been corrected now.Este documento es una errata de "Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger Observatory" (ver "Documentos relacionados").La lista completa de autores puede verse en el archivo asociado.Instituto de Física La Plat
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