Search results for "BOS"
showing 10 items of 3713 documents
More mathematics on pseudo-bosons
2013
We propose an alternative definition for pseudo-bosons. This simplifies the mathematical structure, minimizing the required assumptions. Some physical examples are discussed, as well as some mathematical results related to the biorthogonal sets arising out of our framework. We also briefly extend the results to the so-called nonlinear pseudo-bosons.
Pseudo-bosons, so far
2011
In the past years several extensions of the canonical commutation relations have been proposed by different people in different contexts and some interesting physics and mathematics have been deduced. Here, we review some recent results on the so-called pseudo-bosons. They arise from a special deformation of the canonical commutation relation [a,a †]= ll, which is replaced by [a,b]=ll, with b not necessarily equal to a †. We start discussing some of their mathematical properties and then we discuss several examples.
Alteraciones en el proceso de biogénesis de la subunidad 60S ribosómica como terapia contra el cáncer
2023
Los ribosomas son las estructuras subcelulares encargadas de llevar a cabo la síntesis proteica. La biogénesis ribosómica es un proceso muy complejo que comienza con la transcripción del ARN ribosómico por la ARN polimerasa I en el nucléolo. Este tránscrito inicial sufre un largo procesamiento que implica su plegamiento y asociación con las distintas proteínas ribosómicas. Además, el proceso de biogénesis requiere de la participación de un grupo heterogéneo de proteínas denominadas factores de ensamblaje ribosómicos. Se trata de proteínas que ejercen un papel esencial en el proceso de biogénesis ribosómica pero no forman parte del ribosoma maduro. Muchas de estas proteínas establecen intera…
Superradiant Quantum Phase Transition for an Exactly Solvable Two-Qubit Spin-Boson Model
2023
A spin-boson-like model with two interacting qubits is analysed. The model turns out to be exactly solvable since it is characterized by the exchange symmetry between the two spins. The explicit expressions of eigenstates and eigenenergies make it possible to analytically unveil the occurrence of first-order quantum phase transitions. The latter are physically relevant since they are characterized by abrupt changes in the two-spin subsystem concurrence, in the net spin magnetization and in the mean photon number.
Comparison of Microscopic Interacting Boson Model and Quasiparticle Random Phase Approximation 0νββ Decay Nuclear Matrix Elements
2021
The fundamental nature of the neutrino is presently a subject of great interest. A way to access the absolute mass scale and the fundamental nature of the neutrino is to utilize the atomic nuclei through their rare decays, the neutrinoless double beta (0νββ) decay in particular. The experimentally measurable observable is the half-life of the decay, which can be factorized to consist of phase space factor, axial vector coupling constant, nuclear matrix element, and function containing physics beyond the standard model. Thus reliable description of nuclear matrix element is of crucial importance in order to extract information governed by the function containing physics beyond the standard m…
Rho GTPases in human breast tumours: expression and mutation analyses and correlation with clinical parameters
2002
In the present study, we addressed the question of a putative relevance of Rho proteins in tumour progression by analysing their expression on protein and mRNA level in breast tumours. We show that the level of RhoA, RhoB, Rac1 and Cdc42 protein is largely enhanced in all tumour samples analysed (n=15) as compared to normal tissues originating from the same individual. The same is true for 32P-ADP-ribosylation of Rho proteins which is catalysed by Clostridium botulinum exoenzyme C3. Also the amount of Rho-GDI and ERK2 as well as the level of overall 32P-GTP binding acvitity was tumour-specific elevated, yet to a lower extent than Rho proteins. Although the amount of Rho proteins was enhance…
Sobre la identidad y procedencia del poeta Filóxeno y la autoría del ditirambo ???????
2019
El presente estudio pretende resolver la controversia en torno a la identidad y procedencia del poeta Filóxeno, célebre ditirambógrafo del siglo V-IV a.C. Para ello, hemos recopilado todos los testimonios que citan a personajes con el nombre de Filóxeno desde la primera mención de Aristófanes. La investigación ha revelado que existen varios individuos con el mismo nombre y rasgos comunes. No obstante, el examen de estos testimonios revela la existencia de un único autor de ditirambos: Filóxeno de Citera. Además, creemos que este poeta fue el autor del ditirambo ???????, que algunos editores atribuyeron falsamente a Filóxeno de Léucade. Posteriormente, reflexionamos sobre la identidad de Fil…
Rimboschimento e recupero di soprassuoli forestali artificiali degradati: due aspetti fondamentali per la salvaguardia del territorio montano - Refor…
2015
I fenomeni di dissesto del territorio che in questi ultimi anni sembrano acutizzarsi e recare ferite profonde in tutto il Paese, se da un lato sono quasi endemici data la morfologia e la natura dei terreni, certamente dall'altro sono frutto della mancanza di gestione pianificata e programmatica dell'uso del territorio. Ad esse si unisce il profondo mutamento del tessuto sociale e il conseguente abbandono di molte aree agricole e forestali divenute marginali all'attività economica, cui non ha fatto fronte una politica di salvaguardia del territorio efficace e duratura. Ai problemi di stabilità del territorio montano e collinare, spesso originati da inadeguate attività umane, si è fatto front…
Cytotoxic necrotizing factor type 2 produced by virulent Escherichia coli modifies the small GTP-binding proteins Rho involved in assembly of actin s…
1994
Cytotoxic necrotizing factor type 2 (CNF2) produced by Escherichia coli strains isolated from intestinal and extraintestinal infections is a dermonecrotic toxin of 110 kDa. We cloned the CNF2 gene from a large plasmid carried by an Escherichia coli strain isolated from a lamb with septicemia. Hydropathy analysis of the deduced amino acid sequence revealed a largely hydrophilic protein with two potential hydrophobic transmembrane domains. The N-terminal half of CNF2 showed striking homology (27% identity and 80% conserved residues) to the N-terminal portion of Pasteurella multocida toxin. Methylamine protection experiments and immunofluorescence studies suggested that CNF2 enters the cytosol…
Rho GTPases are over-expressed in human tumors.
1999
Small GTPases of the Rho family are involved in the regulation of a variety of cellular processes, such as the organization of the microfilamental network, cell-cell contact and malignant transformation. To address the question of whether Rho proteins are involved in carcinogenesis in man, we compared their expression in tumors from colon, breast and lung with that of the corresponding normal tissue originating from the same patient. As shown by Rho-specific 32P-ADP-ribosylation, as well as Western-blot analysis, the amount of RhoA protein was largely increased in all 3 types of tumors tested. The most dramatic differences in the expression of Rho GTPases were observed in breast tissue. All…