University of Warsaw

About: University of Warsaw is a education organization based out in Warsaw, Poland. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 20832 authors who have published 56617 publications receiving 1185084 citations. The organization is also known as: Uniwersytet Warszawski & Warsaw University.

The exoribonuclease Dis3L2 defines a novel eukaryotic RNA degradation pathway.

Abstract: The final step of cytoplasmic mRNA degradation proceeds in either a 5′-3′ direction catalysed by Xrn1 or in a 3′-5′ direction catalysed by the exosome Dis3/Rrp44, an RNase II family protein, is the catalytic subunit of the exosome In humans, there are three paralogues of this enzyme: DIS3, DIS3L, and DIS3L2 In this work, we identified a novel Schizosaccharomyces pombe exonuclease belonging to the conserved family of human DIS3L2 and plant SOV Dis3L2 does not interact with the exosome components and localizes in the cytoplasm and in cytoplasmic foci, which are docked to P-bodies Deletion of dis3l2+ is synthetically lethal with xrn1Δ, while deletion of dis3l2+ in an lsm1Δ background results in the accumulation of transcripts and slower mRNA degradation rates Accumulated transcripts show enhanced uridylation and in vitro Dis3L2 displays a preference for uridylated substrates Altogether, our results suggest that in S pombe, and possibly in most other eukaryotes, Dis3L2 is an important factor in mRNA degradation Therefore, this novel 3′-5′ RNA decay pathway represents an alternative to degradation by Xrn1 and the exosome

Impact of the Halide Cage on the Electronic Properties of Fully Inorganic Cesium Lead Halide Perovskites

Abstract: Perovskite solar cells with record power conversion efficiency are fabricated by alloying both hybrid and fully inorganic compounds. While the basic electronic properties of the hybrid perovskites are now well understood, key electronic parameters for solar cell performance, such as the exciton binding energy of fully inorganic perovskites, are still unknown. By performing magneto-transmission measurements, we determine with high accuracy the exciton binding energy and reduced mass of fully inorganic CsPbX3 perovskites (X = I, Br, and an alloy of these). The well-behaved (continuous) evolution of the band gap with temperature in the range of 4–270 K suggests that fully inorganic perovskites do not undergo structural phase transitions like their hybrid counterparts. The experimentally determined dielectric constants indicate that at low temperature, when the motion of the organic cation is frozen, the dielectric screening mechanism is essentially the same for both hybrid and inorganic perovskites and is do...

Supersymmetric Gauge Theories, Intersecting Branes and Free Fermions

Abstract: We show that various holomorphic quantities in supersymmetric gauge theories can be conveniently computed by configurations of D4-branes and D6-branes. These D-branes intersect along a Riemann surface that is described by a holomorphic curve in a complex surface. The resulting I-brane carries two-dimensional chiral fermions on its world-volume. This system can be mapped directly to the topological string on a large class of non-compact Calabi-Yau manifolds. Inclusion of the string coupling constant corresponds to turning on a constant B-field on the complex surface, which makes this space non-commutative. Including all string loop corrections the free fermion theory is elegantly formulated in terms of holonomic D-modules that replace the classical holomorphic curve in the quantum case.

The 2010 very high energy gamma-ray flare and 10 years of multi-wavelength observations of M 87

Abstract: The giant radio galaxy M 87 with its proximity (16 Mpc), famous jet, and very massive black hole ((3-6) x 10(9) M-circle dot) provides a unique opportunity to investigate the origin of very high energy (VHE; E > 100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of supermassive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz Very Long Baseline Array, VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times of tau(rise)(d) = (1.69 +/- 0.30) days and tau(decay)(d) = (0.611 +/- 0.080) days, respectively. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (similar to day), peak fluxes (Phi(>0.35 TeV) similar or equal to (1-3) x 10(-11) photons cm(-2) s(-1)), and VHE spectra. VLBA radio observations of 43 GHz of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken similar to 3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core (flux increased by factor similar to 2; variability timescale <2 days). The long-term (2001-2010) multi-wavelength (MWL) light curve of M 87, spanning from radio to VHE and including data from Hubble Space Telescope, Liverpool Telescope, Very Large Array, and European VLBI Network, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified. In the outer kiloparsec jet region, in particular in HST-1, no enhanced MWL activity was detected in 2008 and 2010, disfavoring it as the origin of the VHE flares during these years. Shortly after two of the three flares (2008 and 2010), the X-ray core was observed to be at a higher flux level than its characteristic range (determined from more than 60 monitoring observations: 2002-2009). In 2005, the strong flux dominance of HST-1 could have suppressed the detection of such a feature. Published models for VHE gamma-ray emission from M 87 are reviewed in the light of the new data.

Cosmic microwave background anisotropy power spectrum statistics for high precision cosmology

Abstract: As the era of high precision cosmology approaches, the empirically determined power spectrum of the microwave background anisotropy $C_l$ will provide a crucial test for cosmological theories. We present an exact semi-analytic framework for the study of the ampling statistics of the $C_l$ resulting from observations with partial sky coverage and anisotropic noise distributions. This includes space-borne, air-borne and ground-based experiments. We apply this theory to demonstrate its power for constructing fast but unbiased approximate methods for the joint estimation of cosmological parameters. Further applications, such as a test for possible non-Gaussianity of the underlying theory and a ``poor man's power spectrum estimator'' are suggested. An appendix derives recursion relations for the efficient computation of the couplings between spherical harmonics on the cut sky.