TY - JOUR A1 - Scholz, M. A1 - Sauer, C. A1 - Wiessner, M. A1 - Nguyen, N. A1 - Scholl, A. A1 - Reinert, F. T1 - Structure formation in organic thin films observed in real time by energy dispersive near-edge x-ray absorption fine-structure spectroscopy JF - New Journal of Physics N2 - We study the structure formation of 1,4,5,8-naphthalenetetracarboxylicacid- dianhydride (NTCDA) multilayer films on Ag(111) surfaces by energy dispersive near-edge x-ray absorption fine-structure spectroscopy (NEXAFS) and photoelectron spectroscopy. The time resolution of seconds of the method allows us to identify several sub-processes, which occur during the post-growth three-dimensional structural ordering, as well as their characteristic time scales. After deposition at low temperature the NTCDA molecules are preferentially flat lying and the films exhibit no long-range order. Upon annealing the molecules flip into an upright orientation followed by an aggregation in a transient phase which exists for several minutes. Finally, threedimensional islands are established with bulk-crystalline structure involving substantial mass transport on the surface and morphological roughening. By applying the Kolmogorov–Johnson–Mehl–Avrami model the activation energies of the temperature-driven sub-processes can be derived from the time evolution of the NEXAFS signal. KW - physics Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-129749 VL - 15 IS - 083052 ER - TY - JOUR A1 - Nguyen, Tu N. A1 - Müller, Laura S. M. A1 - Park, Sung Hee A1 - Siegel, T. Nicolai A1 - Günzl, Arthur T1 - Promoter occupancy of the basal class I transcription factor A differs strongly between active and silent VSG expression sites in Trypanosoma brucei JF - Nucleic Acid Research N2 - Monoallelic expression within a gene family is found in pathogens exhibiting antigenic variation and in mammalian olfactory neurons. Trypanosoma brucei, a lethal parasite living in the human bloodstream, expresses variant surface glycoprotein (VSG) from 1 of 15 bloodstream expression sites (BESs) by virtue of a multifunctional RNA polymerase I. The active BES is transcribed in an extranucleolar compartment termed the expression site body (ESB), whereas silent BESs, located elsewhere within the nucleus, are repressed epigenetically. The regulatory mechanisms, however, are poorly understood. Here we show that two essential subunits of the basal class I transcription factor A (CITFA) predominantly occupied the promoter of the active BES relative to that of a silent BES, a phenotype that was maintained after switching BESs in situ. In these experiments, high promoter occupancy of CITFA was coupled to high levels of both promoter-proximal RNA abundance and RNA polymerase I occupancy. Accordingly, fluorescently tagged CITFA-7 was concentrated in the nucleolus and the ESB. Because a ChIP-seq analysis found that along the entire BES, CITFA-7 is specifically enriched only at the promoter, our data strongly indicate that monoallelic BES transcription is activated by a mechanism that functions at the level of transcription initiation. KW - RNA-polymerase-I KW - blood-stream forms KW - acrican trypanosomes KW - gene expression KW - antigenic variation KW - ribosomal RNA KW - plasmodium falciparum KW - virulence genes KW - subunit KW - complex Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-117232 SN - 1362-4962 VL - 42 IS - 5 ER - TY - JOUR A1 - Trafimow, David A1 - Amrhein, Valentin A1 - Areshenkoff, Corson N. A1 - Barrera-Causil, Carlos J. A1 - Beh, Eric J. A1 - Bilgiç, Yusuf K. A1 - Bono, Roser A1 - Bradley, Michael T. A1 - Briggs, William M. A1 - Cepeda-Freyre, Héctor A. A1 - Chaigneau, Sergio E. A1 - Ciocca, Daniel R. A1 - Correa, Juan C. A1 - Cousineau, Denis A1 - de Boer, Michiel R. A1 - Dhar, Subhra S. A1 - Dolgov, Igor A1 - Gómez-Benito, Juana A1 - Grendar, Marian A1 - Grice, James W. A1 - Guerrero-Gimenez, Martin E. A1 - Gutiérrez, Andrés A1 - Huedo-Medina, Tania B. A1 - Jaffe, Klaus A1 - Janyan, Armina A1 - Karimnezhad, Ali A1 - Korner-Nievergelt, Fränzi A1 - Kosugi, Koji A1 - Lachmair, Martin A1 - Ledesma, Rubén D. A1 - Limongi, Roberto A1 - Liuzza, Marco T. A1 - Lombardo, Rosaria A1 - Marks, Michael J. A1 - Meinlschmidt, Gunther A1 - Nalborczyk, Ladislas A1 - Nguyen, Hung T. A1 - Ospina, Raydonal A1 - Perezgonzalez, Jose D. A1 - Pfister, Roland A1 - Rahona, Juan J. A1 - Rodríguez-Medina, David A. A1 - Romão, Xavier A1 - Ruiz-Fernández, Susana A1 - Suarez, Isabel A1 - Tegethoff, Marion A1 - Tejo, Mauricio A1 - van de Schoot, Rens A1 - Vankov, Ivan I. A1 - Velasco-Forero, Santiago A1 - Wang, Tonghui A1 - Yamada, Yuki A1 - Zoppino, Felipe C. M. A1 - Marmolejo-Ramos, Fernando T1 - Manipulating the Alpha Level Cannot Cure Significance Testing JF - Frontiers in Psychology N2 - We argue that making accept/reject decisions on scientific hypotheses, including a recent call for changing the canonical alpha level from p = 0.05 to p = 0.005, is deleterious for the finding of new discoveries and the progress of science. Given that blanket and variable alpha levels both are problematic, it is sensible to dispense with significance testing altogether. There are alternatives that address study design and sample size much more directly than significance testing does; but none of the statistical tools should be taken as the new magic method giving clear-cut mechanical answers. Inference should not be based on single studies at all, but on cumulative evidence from multiple independent studies. When evaluating the strength of the evidence, we should consider, for example, auxiliary assumptions, the strength of the experimental design, and implications for applications. To boil all this down to a binary decision based on a p-value threshold of 0.05, 0.01, 0.005, or anything else, is not acceptable. KW - statistical significance KW - null hypothesis testing KW - p-value KW - significance testing KW - decision making Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-189973 SN - 1664-1078 VL - 9 IS - 699 ER -