Sobre la recuperación de la certeza

En el documento se examinan cualitativamente algunos aspectos y condiciones relacionadas con el proceso por el cual los estudiantes abandonan el estado de duda y recuperan su certeza en torno a proposiciones de contenido matemático; los sujetos que intervienen en el estudio participan en un diplomado de enseñanza del álgebra en línea. Se argumenta que la recuperación de la certeza puede estar ligada tanto a sustentos extra-matemáticos como a los de tipo matemático y que la primera vía suele conducir a la incomprensión mientras que la segunda puede llevar a un aumento de la comprensión. Esto desvela que la duda no siempre genera condiciones necesarias para el aprendizaje. Para el análisis se recurre a una interpretación de los argumentos basada en el Modelo de Toulmin

Conformational profiling of a G-rich sequence within the c-KIT promoter

G-quadruplexes (G4) within oncogene promoters are considered to be promising anticancer targets. However, often they undergo complex structural rearrangements that preclude a precise description of the optimal target. Moreover, even when solved structures are available, they refer to the thermodynamically stable forms but little or no information is supplied about their complex multistep folding pathway. To shed light on this issue, we systematically followed the kinetic behavior of a G-rich sequence located within the c-KIT proximal promoter (kit2) in the presence of monovalent cations K + and Na + . A very short-lived intermediate was observed to start the G4 folding process in both salt conditions. Subsequently, the two pathways diverge to produce distinct thermodynamically stable species (parallel and antiparallel G-quadruplex in K + and Na + , respectively). Remarkably, in K + -containing solution a branched pathway is required to drive the wild type sequence to distribute between a monomeric and dimeric G-quadruplex. Our approach has allowed us to identify transient forms whose relative abundance is regulated by the environment; some of them were characterized by a half-life within the timescale of physiological DNA processing events and thus may represent possible unexpected targets for ligands recognition

Centers of probability measures without the mean

In the recent years, the notion of mixability has been developed with applications to operations research, optimal transportation, and quantitative finance. An n-tuple of distributions is said to be jointly mixable if there exist n random variables following these distributions and adding up to a constant, called center, with probability one. When the n distributions are identical, we speak of complete mixability. If each distribution has finite mean, the center is obviously the sum of the means. In this paper, we investigate the set of centers of completely and jointly mixable distributions not having a finite mean. In addition to several results, we show the (possibly counterintuitive) fact that, for each (Formula presented.), there exist n standard Cauchy random variables adding up to a constant C if and only if (Formula presented.

Two-channel charge-Kondo physics in graphene quantum dots

Nanoelectronic quantum dot devices exploiting the charge-Kondo paradigm have been established as versatile and accurate analog quantum simulators of fundamental quantum impurity models. In particular, hybrid metal-semiconductor dots connected to two metallic leads realize the two-channel Kondo (2CK) model, in which Kondo screening of the dot charge pseudospin is frustrated. Here, we consider theoretically a two-channel charge-Kondo device made instead from graphene components, realizing a pseudogapped version of the 2CK model. We solve the model using Wilson's Numerical Renormalization Group method, and uncover a rich phase diagram as a function of dot-lead coupling strength, channel asymmetry, and potential scattering. The complex physics of this system is explored through its thermodynamic properties, scattering T-matrix, and experimentally measurable conductance. We find that the strong coupling pseudogap Kondo phase persists in the channel-asymmetric two-channel context, while in the channel-symmetric case frustration results in a novel quantum phase transition. Remarkably, despite the vanishing density of states in the graphene leads at low energies, we find a finite linear conductance at zero temperature at the frustrated critical point, which is of non-Fermi liquid type. Our results suggest that the graphene charge-Kondo platform offers a unique possibility to access multichannel pseudogap Kondo physics.Comment: 12 pages, 4 figure

A korai kezdetu ujszulottkori B csoportu Streptococcus-szepszis megelozesenek helyzete Magyarorszagon 2012-ben. Egy orszagos felmeres adatai.

Introduction: At present, there is no obligatory guideline for the prevention of early-onset neonatal group B streptococcal disease in Hungary. Aim: The aim of the present study was to gain insight into the spontaneously developed preventive strategy of the domestic obstetric divisions and departments in Hungary. Method: Standardized questionnaire was sent out to each of the 71 obstetric divisions and departments in Hungary. Results: Overall, 20 (27.4%) of the chairpersons replied, and thus, 39.9% of the total number of live births in Hungary were included in the study. Despite missing public health guidelines, each of the divisions and departments developed their own strategy to prevent neonatal group B streptococcal disease. In 95% of cases, bacterial culture of the lower vagina was the method of identifying pregnant women at risk. In 5% of the cases intrapartum antibiotic prophylaxis was based on risk assessment only. Of the departments using culture-based prophylaxis, 58% departments sampled women after completion of 36th gestational weeks. Antibiotic of choice was penicillin or ampicillin in 100% of cases. Of the study participants, 80% reported on multiple administration of colonized pregnant women after onset of labor or rupture of the membranes. Conclusions: The authors concluded that the rate of participation in the study was low. However, prevention of early-onset neonatal group B streptococcal infection is a priority of obstetric care in Hungary. Lack of a nation-wide public health policy did not prevent obstetric institutions in this country to develop their own prevention strategy. In the majority of cases and institutions, the policy is consistent with the widely accepted international standards. Orv. Hetil., 2014, 155(29), 1167-1172

Computing the kk-binomial complexity of the Thue--Morse word

Two words are $k$-binomially equivalent whenever they share the same subwords, i.e., subsequences, of length at most $k$ with the same multiplicities. This is a refinement of both abelian equivalence and the Simon congruence. The $k$-binomial complexity of an infinite word $\mathbf{x}$ maps the integer $n$ to the number of classes in the quotient, by this $k$-binomial equivalence relation, of the set of factors of length $n$ occurring in $\mathbf{x}$. This complexity measure has not been investigated very much. In this paper, we characterize the $k$-binomial complexity of the Thue--Morse word. The result is striking, compared to more familiar complexity functions. Although the Thue--Morse word is aperiodic, its $k$-binomial complexity eventually takes only two values. In this paper, we first obtain general results about the number of occurrences of subwords appearing in iterates of the form $\Psi^\ell(w)$ for an arbitrary morphism $\Psi$. We also thoroughly describe the factors of the Thue--Morse word by introducing a relevant new equivalence relation