Distinct impact of CURLY LEAF and SWINGER on the Arabidopsis Histone H3 Lysine 27 trimethylation pattern is linked to the underlying genetic code

Polycomb Group Proteins (PcG) are a conserved class of transcriptional repressors in animals and plants, controlling the expression of hundreds of genes. Specifically, they repress gene expression by histone H3 trimethylation at lysine 27 (H3K27me3) via the Polycomb Repressive Complex 2 (PRC2). In Arabidopsis thaliana CURLY LEAF (CLF), a PRC2 methyltransferase, is partially redundant with the closely related protein SWINGER (SWN). The phenotype of clf null mutant plants is less severe than the phenotype of clf/swn double mutants. Plants that are mutated in swn exhibit no obvious phenotype. The large degree of sequence conservation of both CLF and SWN throughout the plant kingdom, suggests that they have distinct and conserved functions in plant development. I set out to identify the individual target genes of CLF and SWN and to uncover their functions. To this end, I used chromatin immunoprecipitation followed by deep sequencing to create genome-wide H3K27me3 profiles of wild type, clf and swn seedlings. The three genotypes share many H3K27me3 target regions but they exhibit partially distinct methylation profiles. In clf null mutants, H3K27me3 is significantly reduced at 643 genes, indicating that at these genes CLF is the major catalytic component of PRC2. A part of the CLF dependent genes is significantly physically clustered along chromosomes and surprisingly, 60% of CLF dependent genes contain a conserved AAACCCTA or telo box which has been previously reported to enhance transcription. Unexpectedly, reduction of H3K27me3 in clf mutant plants does not correlate frequently with an increase of gene expression. The swn mutation can either have the same effect, oppose or contribute to the effect of clf on the expression of these genes. Moreover, in swn null mutants, H3K27me3 seems to be slightly increased in 294 genes compared to wild-type. These results suggest that the interplay between CLF and SWN might be important to establish wild-type-like H3K27me3 and expression levels. Finally, in swn, expression of some CLF dependent genes changes dramatically, although H3K27me3 is unaffected. This indicates that SWN might have an H3K27me3 independent function. In short, these results demonstrate that CLF and SWN have partially distinct effects on the Arabidopsis thaliana H3K27me3 pattern and that their function is linked to the underlying genetic code. SWN might control expression in a H3K27me3 independent pathway and the interplay between CLF and SWN is presumably important to maintain establish wild-type-like H3K27me3 and expression levels

Investigations into the burning-out of organic substances in the ceramic body

Pressed compacts were made of spray dried alumina containing water soluble polyvinyl alcohol or cellulose derivative binder. The burning out of organic binder on gradual heating was investigated by visual and microscopic observations of the cross section and by thermogravimetry. Burning out proceeds inward from the peripheries, gradually reducing the size of the black core, which first consists of a dark boundary layer and later turns uniformly black with a sharp boundary. A detailed mechanism of the burning out process between and within the spray dried granules is observed under the microscope. Oxygen atmosphere accelerates the burning out process

Un oracle homérique de l’Antiquité tardive

La présente étude propose une lecture « à la verticale » des vers homériques composant l’Ὁμηρομαντεῖον du Papyrus de Londres 121, au-delà du mode d’emploi interactif selon lequel fonctionne ce texte. Outre le recours à un stock de vers homériques circulant de façon relativement autonome dans le monde érudit, l’étude des critères de sélection des vers composant ce passage révèle un effort conscient d’y reproduire les caractéristiques de la littérature oraculaire : caractère gnomique ou proverbial, obscurité, ton instructif et offensant, etc. Tirés des discours des dieux ou de leurs élus, ces vers/oracles introduisent le questionneur dans une relation intime avec le divin tout en lui proposant des modèles de comportement moyennant les figures de Diomède ou d’Ulysse. Or, dans l’Oracle…, tout comme dans l’Iliade, Diomède paraît en quête d’un juste équilibre entre les maîtres du jeu, à savoir Athéna et Apollon.This paper proposes a “vertical” reading of the Homeric verses composing the Homeromanteion (Ὁμηρομαντεῖον) of the London Papyrus 121, beyond the interactive method that is normally prescribed for this kind of divinatory text. The study of the selection criteria for these verses reveals, not only the use of a stock of Homeric verses circulating autonomously among learned people, but also an intentional infusion of oracular characteristics: gnomic or proverbial style, obscurity, instructive and offensive tone, etc. Selected from speeches of the gods or of their favorite mortals, these verses/oracles introduce the inquirer to an intimate relationship with the divine while providing behavioral models through figures such as Diomedes and Odysseus. In fact, in the Oracle… as well in the Iliad, Diomedes seems to seek out a suitable balance between the major players, Athena and Apollo

La adivinación en los papiros mágicos griegos

Over the last decades we have grown used to seeing the terms magic and divination alongside each other in titles of books, articles and book chapters. Despite the indefiniteness of magic and the frequent association of divination with official shrines, both terms refer to religious phenomena that are often studied together; they are often considered as tools of dealing with life crisis and other uncertainties or practices dependent upon the knowledge of religious experts. In this context, spe..

Resilience Assessment of Offshore Wind-to-Hydrogen Systems

Low-cost green hydrogen production will be key in reaching net zero carbon emissions by 2050. Green hydrogen can be produced by electrolysis using renewable energy, including wind energy. However, the configuration of offshore wind-to-hydrogen systems is not yet standardised. For example, electrolysis can take place onshore or offshore. This work presents a framework to assess and quantify which configuration is more resilient, so that security of hydrogen supply is incorporated in strategic decisions with the following key findings. First, resilience should be assessed according to hydrogen supply, rather than hydrogen production. This allows the framework to be applicable for all identified system configurations. Second, resilience can be quantified according to the quantity, ratio, and lost revenue of the unsupplied hydrogen

Not Too Warm, Not Too Cold: Thermal Treatments to Slightly Warmer or Colder Conditions from Mother’s Origin Can Enhance Performance of Montane Butterfly Larvae

Climate change alters organismal performance via shifts in temperature. However, we know little about the relative fitness impacts of climate variability and how cold-adapted ectotherms mediate these effects. Here, we advance the field of climate change biology by directly testing for species performance, considering the effects of different thermal environments at the first developmental stage of larvae. We conducted our experiments in climatic chambers (2019–2020) using five coldadapted butterflies of the genus Erebia (Erebia aethiops, Erebia cassioides, Erebia manto, Erebia tyndarus, Erebia nivalis). Larvae were reared indoors and were treated with higher and lower temperatures than those of their mothers’ origins. Overall, we found evidence of better performance at warmer temperatures and a decreased performance at lower temperatures, and larvae were able to tolerate small temperature changes from mother’s origin. Warmer conditions, however, were unfavorable for E. nivalis, indicative of its limited elevational range and its poor ability to mediate a variety of thermal conditions. Further, larvae generally performed poorly where there was a large difference in thermal regimen from that of their maternal origin. Future efforts should include additional life history stages and focus on a more mechanistic understanding of species thermal tolerance. Such studies could increase the realism of predicted responses to climate change and could account for asynchronous changes in species development, which will alter community composition and ecosystem functioning

Επίδραση Εταιρικής Διακυβέρνησης στην Εταιρική Αποδοτικότητα: η Περίπτωση των Εισηγμένων Επιχειρήσεων στο Χρηματιστήριο Αξιών Αθηνών

Η σύνδεση μεταξύ εταιρικής διακυβέρνησης και οικονομικής αποδοτικότητας των επιχειρήσεων έχει απασχολήσει πολλές μελέτες στο παρελθόν. Εταιρίες με πιο ποιοτική και διαφανή εταιρική διακυβέρνηση αναμένονται να λαμβάνουν καλύτερες αποφάσεις με γνώμονα το συμφέρον των μετόχων και, έτσι, να έχουν υψηλότερες οικονομικές αποδόσεις. Η εταιρική διακυβέρνηση χαρακτηρίζεται από τους μηχανισμούς του διοικητικού συμβουλίου, της επιτροπής ελέγχου και του εξωτερικού ελέγχου. Διάφορες θεωρίες έχουν αναπτυχθεί ως προς το πώς επηρεάζει ο κάθε μηχανισμός την οικονομική αποδοτικότητα και αντίστοιχες εμπειρικές μελέτες έχουν δείξει πολλά διαφορετικά αποτελέσματα. Σε δείγμα 127 επιχειρήσεων εισηγμένων στο Χρηματιστήριο Αθηνών κατά την περίοδο 2017-2019 εξετάστηκε η επίδραση της εταιρικής διακυβέρνησης στην οικονομική αποδοτικότητα, η οποία μετρήθηκε με λογιστικούς δείκτες καθώς και δείκτες της χρηματιστηριακής αγοράς. Τα αποτελέσματα έδειξαν κατ’ αρχάς ότι το μέγεθος του ΔΣ επηρεάζει θετικά την αγοραία αποδοτικότητα, αλλά όχι την λογιστική. Επίσης, η ανεξαρτησία του ΔΣ επηρεάζει αρνητικά την αγοραία και λογιστική αποδοτικότητα, ενώ επιχειρήσεις, όπου πρόεδρος και διευθύνων σύμβουλος είναι το ίδιο πρόσωπο, τείνουν να έχουν υψηλότερη λογιστική αποδοτικότητα. Περαιτέρω, το πλήθος των συναντήσεων της επιτροπής ελέγχου επιδρά αρνητικά στη λογιστική, αλλά όχι στην αγοραία αποδοτικότητα. Τέλος, ο εξωτερικός έλεγχος από μεγάλες ελεγκτικές εταιρείες (big4) δεν συνδέεται με αυξημένη οικονομική αποδοτικότητα. Τα αποτελέσματα αυτά επιβεβαιώνουν κάποιες από τις ερευνητικές μας υποθέσεις και είναι συμβατά με τα ευρήματα άλλων παλαιότερων ερευνών.The association between corporate governance and financial performance has been studied many times in the past. Firms with more qualitative and more transparent corporate governance are expected to make more qualitative decisions for the best interest of shareholders and, thus, to enjoy higher financial performance. Corporate governance is characterized by mechanisms like board of directors, audit committee and external audit. Several theories have been developed concerning of how each mechanism affects financial performance and several related empirical studies have shown mixed results. Using a sample of 127 Greek listed firms during the period 2017-2019, the effect of corporate governance on financial performance was examined. Financial performance was measured both with accounting and with market ratios. Results showed that board size positively affects market performance but not accounting performance. Board independence negatively affects both market and accounting performance. Firms with CEO duality tend to have higher accounting performance, but not market performance. Number of audit committee meetings negatively affects accounting performance, but not market performance. Finally, external audit by big 4 is not associated with higher financial performance. These results confirm some of research hypotheses and are consistent with findings of some past researches

Optimal scheduling of Distributed Energy Resources connected to Electricity Distribution Networks using Robust Mixed-Integer Second Order Cone Programming

Eng. D. Thesis.Tackling climate change is a global emergency, driving the electricity sector to go through rapid changes, including the increasing reliance on local generating assets, called distributed energy resources (DER). DER range from onsite energy storage systems, to gas or diesel generators, and renewable generators, but could also include other forms of generation such as electric vehicles with vehicle-to-grid capabilities. This PhD proposes a model to optimally schedule DER connected to radial distribution networks, which can form an active distribution network or a microgrid, aiming at delivering improvements in operational cost, security of supply and environmental sustainability. This is mathematically formulated using robust mixed-integer second-order cone programming. The proposed model takes into account an accurate power flow model for radial networks and a robust approach to deal with uncertainty in the market price, the electricity demand, the renewable generation, and the time and duration of a scheduled interruption from the main grid when DER form part of a microgrid. Computational experiments support the suitability of the proposed model, in a number of case studies informed by real-world data and operational scenarios. This research concludes the following. Firstly, that it is important to account for detailed modelling of network losses in operational decisions of such systems, as they profoundly affect both the cost and the network’s operating state and conditions. Secondly, that the robust approach used in this thesis in order to deal with uncertainty allows distribution system and/or microgrid operators to manage trade-offs between the level of the aforementioned uncertainties they are willing to tolerate, and the operational cost of network assets. Benefits of using the proposed model include, reduction of the operational cost, and mitigation of technical constraint violations in actual conditions. The proposed model can be used by a range of stakeholders including, microgrid operators, distribution system operators, and DER owners.Newcastle University, Engineering and Physical Sciences Research Council (EPSRC