Search results for "rings"

Cohomology and associated deformations for not necessarily co-associative bialgebras

1992

In this Letter, a cohomology and an associated theory of deformations for (not necessarily co-associative) bialgebras are studied. The cohomology was introduced in a previous paper (Lett. Math. Phys.25, 75–84 (1992)). This theory has several advantages, especially in calculating cohomology spaces and in its adaptability to deformations of quasi-co-associative (qca) bialgebras and even quasi-triangular qca bialgebras.

Contractions yielding new supersymmetric extensions of the poincaré algebra

1991

Two new Poincare superalgebras are analysed. They are obtained by the Wigner-Inonu contraction from two real forms of the superalgebra OSp(2;4;C) - one describing the N = 2 anti-de-Sitter superalgebra with a non-compact internal symmetry SO(1, 1) and the other corresponding to the de-Sitter superalgebra with internal symmetry SO(2). Both are 19-dimensional self-conjugate extensions of the Konopel'chenko superalgebra. They contain 10 Poincare generators and one generator of internal symmetry in addition to 8 odd generators half of which, however, do not commute with translations.

Pre‐instrumental summer precipitation variability in northwestern Greece from a high‐elevation Pinus heldreichii network

2021

The spatiotemporal variability of precipitation is of vital importance to Mediterranean ecology and economy, but pre‐instrumental changes are not well understood. Here, we present a millennial‐length June–July precipitation reconstruction derived from a network of 22 Pinus heldreichii high‐elevation sites in the Pindus Mountains of northwestern Greece. Tree‐ring width chronologies from these sites cohere exceptionally well over the past several hundred years (r1467–2015 = 0.64) revealing coherence at inter‐annual to centennial timescales across the network. The network mean calibrates significantly against instrumental June–July precipitation over the past 40 years (r1976–2015 = 0.71), even…

Jauno darbinieku adaptācija uzņēmumā.

2018

Darba autore Inga Brauna Kvalifikācijas darba pētījumam izvēlējās tēmu “Jaunā darbinieka adaptācija uzņēmumā”. Autore izvirzīja uzdevumu noskaidrot kādi kritēriji raksturo veiksmīgu jauno darbinieku adaptācijas programmu. Teorijas pētniecības laikā tika lasīts par tādiem terminiem kā adaptācija, integrācija un socializācija, kā arī mobings un mentorings. Pētījuma laikā tika veikta iepazīšanās ar teorētisko literatūru un analizēta informāciju par darbinieku adaptācijas procesu uzņēmumā un mēģināta noskaidrot adaptācijas procesa nozīme, jēga un nepieciešamība uzņēmumā. Epmīriskajā, jeb praktiskajā daļā tika pētīts būvniecības uzņēmuma “Skandināvu Būvnieks” adaptācijas process. Pētījumā izmant…

Pirmsskolas skolotāja mentora iniciatīva kā profesionālās kompetences sastāvdaļa

2017

Maģistra darba nosaukums: Pirmsskolas skolotāja mentora iniciatīva kā profesionālās kompetences sastāvdaļa. Autore: Irina Beļuna. Pētījuma mērķis: Izpētīt teorijās balstītu pirmsskolas skolotāja mentora kompetences saturu, iniciatīvas veidošanās kritērijus un, apzinot pirmsskolas iestāžu skolotāju pieredzi, izstrādāt pirmsskolas skolotāja mentora darbībai atbilstīgus iniciatīvas kā kompetences struktūrkomponenta veidošanas rādītājus. Pētījuma teorētisko bāzi veido: A. Homičas, I. Maslo, T. Koķes, I. Tiļļas, J. Stabiņa, E. Konstantinovas, B. Rivžas darbi. Maģistra darbs sastāv no: ievada, 3 nodaļām, secinājumiem, izmantoto avotu un literatūras saraksta (40 vienības), 3. pielikumiem. Pirmajā …

A high-yielding modular access to the lamellarins: synthesis of lamellarin G trimethyl ether, lamellarin η and dihydrolamellarin η.

2013

From Five- to Six-Membered Rings:  3,4-Diarylquinolinone as Lead for Novel p38MAP Kinase Inhibitors

2007

In this study we describe the design, synthesis, and biological evaluation of 3-(4-fluorophenyl)-4-pyridin-4-ylquinoline-2(1H)-one (5) as a new inhibitor of MAPK with a p38alphaMAPK IC50 of 1.8 muM. By keeping the common vicinal pyridine/4-F-phenyl pharmacophore, such as in prototypical imidazole 20 or isoxazole 13 but in 5 connected to the six-membered quinoline core, we were particularly interested in comparing biological activity, details of molecular geometry, and different binding modes of these compounds. Compounds 20 and 13 were active both in the p38alpha- and JNK3-assay, whereas 5 was selective for p38alpha, with no JNK3 inhibition. By comparing the X-ray structures of the compound…

Measurement of elastic forces between iron colloidal particles in a nematic liquid crystal.

2006

The forces that arise between two iron particles in a nematic liquid crystal with a strong homeotropic anchoring were studied. For the first time, the short range repulsive force resulting from the presence of a hedgehog defect between two particles was precisely determined thanks to application of a small magnetic field and observation of the equilibrium position resulting from the balance between the elastic and magnetic forces. Above a given threshold force, the particles stuck together whereas the hedgehog defect was expelled and transformed into a Saturn ring located between the particles. The attractive part of the interparticle force was determined with the same method on the entire …

Design and Synthesis of 4-Substituted Indolo[3,2-e][1,2,3]triazolo[1,5-a]pyrimidine Derivatives with Antitumor Activity

2008

New derivatives of the indolo[3,2- e][1,2,3]triazolo[1,5- a]pyrimidine system, substituted in the 4 position, were designed as novel antitumor agents because of their theoretical capability to form stable complexes with DNA fragments. The calculated free energies of binding were found in the range -12.76 --> -39.68 Kcal/mol. The docking studies revealed a common binding mode with the chromophore intercalated between GC base pairs, whereas the side chain lies along the minor groove. Compounds, selected on the basis of the docking studies and suitably synthesized, showed antiproliferative activity against each type of tumor cell line investigated, generally in the low micromolar range. The mo…

Synthesis and antiproliferative activity of new derivatives containing the polycyclic system 5,7:7,13-dimethanopyrazolo[3,4-b]pyrazolo[3’,4’:2,3]azep…

2013

The reaction under reflux between 1-phenyl-3-R-5-methylaminopyrazoles and 2,5-hexanedione lead to 5,7:7,13-dimethanopyrazolo[3,4-b]pyrazolo[3′,4′:2,3]azepino[4,5-f]azocine derivatives 3b–g. These unusual molecules show the structural complexity of many biologically active natural products and are endowed with the chemical diversity that is required in drug discovery. The compounds 3b,e were reduced by hydrogen in the presence of Palladium on activated charcoal to give the dihydro derivatives 5b,e. Compounds 3b–f and 5b,e were selected by the NCI to evaluate their in vitro antiproliferative activity against 60 human cell lines derived from nine clinically isolated cancer types (leukaemia, lu…