University of Crete

About: University of Crete is a education organization based out in Rethymno, Greece. It is known for research contribution in the topics: Population & Galaxy. The organization has 8681 authors who have published 21684 publications receiving 709078 citations. The organization is also known as: Panepistimio Kritis.

RNA polymerase III transcription factor TFIIIC2 is overexpressed in ovarian tumors

Abstract: Most transformed cells display abnormally high levels of RNA polymerase (pol) III transcripts. Although the full significance of this is unclear, it may be fundamental because healthy cells use two key tumor suppressors to restrain pol III activity. We present the first evidence that a pol III transcription factor is overexpressed in tumors. This factor, TFIIIC2, is a histone acetyltransferase that is required for synthesis of most pol III products, including tRNA and 5S rRNA. TFIIIC2 is a complex of five polypeptides, and mRNAs encoding each of these subunits are overexpressed in human ovarian carcinomas; this may explain the elevated TFIIIC2 activity that is found consistently in the tumors. Deregulation in these cancers is unlikely to be a secondary response to rapid proliferation, because there is little or no change in TFIIIC2 mRNA levels when actively cycling cells are compared with growth-arrested cells in culture. Using purified factors, we show that raising the level of TFIIIC2 is sufficient to stimulate pol III transcription in ovarian cell extracts. The data suggest that overexpression of TFIIIC2 contributes to the abnormal abundance of pol III transcripts in ovarian tumors.

A space-time finite element method for the nonlinear Schro¨dinger equation: the discontinuous Galerkin method

Abstract: The convergence of the discontinuous Galerkin method for the nonlinear (cubic) Schrodinger equation is analyzed in this paper. We show the existence of the resulting approximations and prove optimal order error estimates in L∞(L 2 ). These estimates are valid under weak restrictions on the space-time mesh.

Sites and Regulation of Polyamine Catabolism in the Tobacco Plant. Correlations with Cell Division/Expansion, Cell Cycle Progression, and Vascular Development

Abstract: We previously gave a picture of the homeostatic characteristics of polyamine (PA) biosynthesis and conjugation in tobacco (Nicotiana tabacum) plant organs during development. In this work, we present the sites and regulation of PA catabolism related to cell division/expansion, cell cycle progression, and vascular development in the tobacco plant. Diamine oxidase (DAO), PA oxidase (PAO), peroxidases (POXs), and putrescine N-methyltransferase expressions follow temporally and spatially discrete patterns in shoot apical cells, leaves (apical, peripheral, and central regions), acropetal and basipetal petiole regions, internodes, and young and old roots in developing plants. DAO and PAO produce hydrogen peroxide, a plant signal molecule and substrate for POXs. Gene expression and immunohistochemistry analyses reveal that amine oxidases in developing tobacco tissues precede and overlap with nascent nuclear DNA and also with POXs and lignification. In mature and old tissues, flow cytometry indicates that amine oxidase and POX activities, as well as pao gene and PAO protein levels, coincide with G2 nuclear phase and endoreduplication. In young versus the older roots, amine oxidases and POX expression decrease with parallel inhibition of G2 advance and endoreduplication, whereas putrescine N-methyltransferase dramatically increases. In both hypergeous and hypogeous tissues, DAO and PAO expression occurs in cells destined to undergo lignification, suggesting a different in situ localization. DNA synthesis early in development and the advance in cell cycle/endocycle are temporally and spatially related to PA catabolism and vascular development.

A Blocking Framework for Entity Resolution in Highly Heterogeneous Information Spaces

Abstract: In the context of entity resolution (ER) in highly heterogeneous, noisy, user-generated entity collections, practically all block building methods employ redundancy to achieve high effectiveness. This practice, however, results in a high number of pairwise comparisons, with a negative impact on efficiency. Existing block processing strategies aim at discarding unnecessary comparisons at no cost in effectiveness. In this paper, we systemize blocking methods for clean-clean ER (an inherently quadratic task) over highly heterogeneous information spaces (HHIS) through a novel framework that consists of two orthogonal layers: the effectiveness layer encompasses methods for building overlapping blocks with small likelihood of missed matches; the efficiency layer comprises a rich variety of techniques that significantly restrict the required number of pairwise comparisons, having a controllable impact on the number of detected duplicates. We map to our framework all relevant existing methods for creating and processing blocks in the context of HHIS, and additionally propose two novel techniques: attribute clustering blocking and comparison scheduling. We evaluate the performance of each layer and method on two large-scale, real-world data sets and validate the excellent balance between efficiency and effectiveness that they achieve.

Detection of the Buried Active Galactic Nucleus in NGC 6240 with the Infrared Spectrograph on the Spitzer Space Telescope

Abstract: We present mid-infrared spectra of the nearby ultraluminous infrared galaxy NGC 6240 taken with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. The spectrum of NGC 6240 is dominated by strong fine-structure lines, rotational H2 lines, and polycyclic aromatic hydrocarbon (PAH) emission features. The H2 line fluxes suggest molecular gas at a variety of temperatures. A simple two-temperature fit to the S(0) through S(7) lines implies a mass of ~6.7 × 106 M☉ at T ~ 957 K and ~1.6 × 109 M☉ at T ~ 164 K, or about 15% of the total molecular gas mass in this system. Notably, we have detected the [Ne V] 14.3 μm emission line, with a flux of 5 × 10-14 ergs cm-2 s-1, providing the first direct detection of the buried active galactic nucleus (AGN) in the mid-infrared. Modeling of the total spectral energy distribution (SED) from near- to far-infrared wavelengths requires the presence of a hot dust (T ~ 700 K) component, which we also associate with the buried AGN. The small [Ne V]/[Ne II] and [Ne V]/IR flux ratios, the relative fraction of hot dust emission, and the large 6.2 μm PAH equivalent width (EQW), are all consistent with an apparent AGN contribution of only 3%-5% to the bolometric luminosity. However, correcting the measured [Ne V] flux by the extinction implied by the silicate optical depth and our SED fitting suggests an intrinsic fractional AGN contribution to the bolometric luminosity of ~20%-24% in NGC 6240, which lies within the range implied by fits to the hard X-ray spectrum.