130,477 research outputs found
Voting systems and fiscal policy: Evidence from runoff and plurality elections
No full textThis paper compares policy outcomes under the runoff voting system and the plurality rule by exploiting the assignment of municipalities in Italy to different voting systems based on a population threshold. Mayors, who are the head of the local political power, are elected using a plurality rule in municipalities having fewer than 15,000 residents, while they are elected using a runoff system in municipalities above the threshold. Regression-discontinuity estimates show that municipalities under the runoff system spend 12 percent more than those under the plurality rule and that additional expenditures are not financed via higher taxation
Powers that be? Political alignment, government formation, and government stability
No full textWe study how partisan alignment across levels of government affects coalition formation and government stability using a regression discontinuity design and a large dataset of Spanish municipal elections. We document a positive effect of alignment on both government formation and stability. Alignment increases the probability that the most-voted party appoints the mayor and decreases the probability that the government is unseated during the term. Aligned parties also obtain sizeable electoral gains in the next elections. We show that these findings are not the consequence of favoritism in the allocation of transfers towards aligned governments
Olefin polymerisation catalysts: when perfection is not enough
No full textDespite decades of thorough mechanistic investigations, it is still hard to predict the activity of a novel olefin polymerisation catalyst, even when the precursor is a well-defined molecular entity. In the present study, we highlight the crucial importance of activation entropy on the polymerisation rate and how weak interactions of the catalytic species with electron donating species in the reaction pool can ultimately lower the activation free energy
Pompe disease: clinical, diagnostic and genetic aspects. Introductory notes to Pompe disease and aims of the Meeting.
No full textCharacterization of GTPBPs involved in ribosome assembly and function in human mitochondria
No full textMitochondria are organelles often referred to as the powerhouses of the cell as they provide most of the chemical energy via aerobic respiration. However, in the last half a century, it has become clear that their function extends to other fundamental metabolic tasks. These fascinating organelles have their own DNA and protein synthesis machinery, the mitochondrial ribosome (mitoribosome), the latter made of a set of mitoribosomal proteins (MRPs) and rRNA that all together build a 2.7 MDa complex. The mitoribosome translates for 13 polypeptides which are later incorporated in the respiratory chain. Therefore, it is not surprising that mutations in MRPs or auxiliary factors involved in its assembly can lead to multisystemic human disorders. Here lies the importance of studying the molecular mechanisms of the mitoribosomal assembly process, which has been the focus of my PhD studies. Guanosine triphosphate binding proteins (GTPBPs) involved in ribosome biogenesis in bacteria have extensively been studied and have provided key knowledge for the understanding of the role of their human mitochondrial homologues identified so far.In my work, I have addressed the role of human mitochondrial proteins GTPBP5, GTPBP10 and GTPBP8 and their possible involvement in mitochondrial ribosome biogenesis. In paper I, we have biochemically characterised GTPBP5 by assessing its interactome and the effects of its depletion on mitochondrial functionality, showing the importance of this protein as an assembly factor. These data have later been confirmed in paper II, where we have structurally determined in more details the function of GTPBP5 as well as several other late-stage mitoribosomal assembly factors. GTPBP10 involvement in the assembly process has been determined biochemically in paper III, where we also co-immunoprecipitated GTPBP10 with the mitoribosome in vivo using a knock-in mouse model. Additionally, preliminary results discussed in this thesis regard the investigation of GTPBP8 function in mitochondrial gene expression, demonstrating its significance for mitochondrial viability.List of scientific papersI. Miriam Cipullo, Sarah F. Pearce, Isabel G. Lopez Sanchez, Shreekara Gopalakrishna, Annika Krüger, Florian Schober, Jakob D. Busch, Xinping Li, Anna Wredenberg, Ilian Atanassov, Joanna Rorbach† (2021). Human GTPBP5 is involved in the late stage of mitoribosome large subunit assembly. Nucleic Acids Research. 49(1):354-370. †Corresponding authors. https://doi.org/10.1093/nar/gkaa1131 II. Miriam Cipullo*, Genís Valentín Gesé*, Anas Khawaja, B. Martin Hällberg†, Joanna Rorbach† (2021). Structural basis for late maturation steps of the human mitoribosomal large subunit. Nature Communications. 12(1):3673. *These authors contributed equally. †Corresponding authors. https://doi.org/10.1038/s41467-021-23617-8 III. Jakob D. Busch, Miriam Cipullo, Ilian Atanassov, Ana Bratic, Eduardo Silva Ramos, Thomas Schöndorf, Xinping Li, Sarah F Pearce, Dusanka Milenkovic, Joanna Rorbach†, Nils-Göran Larsson† (2019). MitoRibo-Tag Mice Provide a Tool for In Vivo Studies of Mitoribosome Composition. Cell Reports. 29(6):1728-1738. †Corresponding authors. https://doi.org/10.1016/j.celrep.2019.09.080 </p
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
HTE methods and results in PO catalysis and materials characterization
No full textHigh Throughput Experimentation (HTE) was originally introduced in olefin polymerization R&D as a discovery tool. In recent years, we spent a considerable effort to extend the scope of the HTE approach to mechanistic investigations. A high-performance polymerization platform (Freeslate PPR48) was integrated with state-of-art polymer characterization tools (including GPC, 13C NMR and A-CEF), and the resulting workflow was optimized for the fast acquisition of large structure-properties databases usable in QSAR studies. The workflow was successfully applied to Ziegler-Natta and molecular olefin polymerization systems and products thereof.(1)
In this presentation, we will illustrate case histories of increasing complexity, covering molecular kinetics as well as polymer characterization aspects
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Extraction of Reliable Molecular Information from Diffusion NMR Spectroscopy: Hydrodynamic Volume or Molecular Mass?
No full textMeasuring accurate translational self-diffusion coefficients (D-t) by NMR techniques with modern spectrometers has become rather routine. In contrast, the derivation of reliable molecular information therefrom still remains a nontrivial task. In this paper, two established approaches to estimating molecular size in terms of hydrodynamic volume (V-H) or molecular weight (M) are compared. Ad hoc designed experiments allowed the critical aspects of their application to be explored by translating relatively complex theoretical principles into practical take-home messages. For instance, comparing the D-t values of three isosteric Cp2MCl2 complexes (Cp=cyclopentadienyl, M=Ti, Zr, Hf), having significantly different molecular mass, provided an empirical demonstration that V-H is the critical molecular property affecting D-t. This central concept served to clarify the assumptions behind the derivation of D-t=integral(M) power laws from the Stokes-Einstein equation. Some pitfalls in establishing log (D-t) versus log (M) linear correlations for a set of species have been highlighted by further investigations of selected examples. The effectiveness of the Stokes-Einstein equation itself in describing the aggregation or polymerization of differently shaped species has been explored by comparing, for example, a ball-shaped silsesquioxane cage with its cigar-like dimeric form, or styrene with polystyrene macromolecules
Interfering Effects of Growing Chain Epimerization on Metallocene-Catalyzed Isotactic Propene Polymerization
No full textThe stereoregularity of polypropylene produced with C2-symmetric group 4 ansa-metallocene catalysts results from the interplay of two competing reactions, namely isotactic monomer polyinsertion and a side process of epimerization of the polymer chain at its active end; therefore, for this class of homogeneous catalysts, at variance with the “classical” heterogeneous Ziegler−Natta ones, enantioselectivity and stereoselectivity are not (necessarily) coincident. In this paper, possible methods for the separate determination of these two parameters are introduced and applied to propene polymerization in the presence of the prototypical catalyst rac-ethylene−bis(4,5,6,7-tetrahydro-1-indenyl)ZrCl2. The results prove that the relatively poor stereoselectivity of this catalyst above room temperature is consequent primarily to chain epimerization; monomer insertion indeed is highly enantioselective up to at least 80 °C. Preliminary evidence for the existence of more than one epimerization mechanism is also presented; this complicates the measurements of enantioselectivity based on 13C NMR characterizations of d-labeled poly(propene)
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