The growth of decagonal Al-Co-Ni single crystals as a function of chemical composition

Decaprismatic single crystals taken from a series of alloys of nominal compositions within Al65-77Co3-22Ni3-22 have been studied by means of x-ray diffraction techniques. The substitution of Co by Ni in increasing amounts changes the (pseudo)decagonal diffraction patterns drastically and indicates structural changes which range from a single-crystalline approximant via orientationally ordered nanodomain structures and quasiperiodic phases with different types of ordering phenomena, to a basic decagonal phase. A quantum phase diagram analysis shows a clear separation of the stability regions of the ternary systems described in this study and other decagonal phase

Identifying Diagnostic Studies in MEDLINE: Reducing the Number Needed to Read

Objectives: The search filters in PubMed have become a cornerstone in information retrieval in evidence-based practice. However, the filter for diagnostic studies is not fully satisfactory, because sensitive searches have low precision. The objective of this study was to construct and validate better search strategies to identify diagnostic articles recorded on MEDLINE with special emphasis on precision. Design: A comparative, retrospective analysis was conducted. Four medical journals were hand-searched for diagnostic studies published in 1989 and 1994. Four other journals were hand-searched for 1999. The three sets of studies identified were used as gold standards. A new search strategy was constructed and tested using the 1989-subset of studies and validated in both the 1994 and 1999 subsets. We identified candidate text words for search strategies using a word frequency analysis of the abstracts. According to the frequency of identified terms, searches were run for each term independently. The sensitivity, precision, and number needed to read (1/precision) of every candidate term were calculated. Terms with the highest sensitivity × precision product were used as free text terms in combination with the MeSH term "SENSITIVITY AND SPECIFICITY” using the Boolean operator OR. In the 1994 and 1999 subsets, we performed head-to-head comparisons of the currently available PubMed filter with the one we developed. Measurements: The sensitivity, precision and the number needed to read (1/precision) were measured for different search filters. Results: The most frequently occurring three truncated terms (diagnos*; predict* and accura*) in combination with the MeSH term "SENSITIVITY AND SPECIFICITY” produced a sensitivity of 98.1 percent (95% confidence interval: 89.9-99.9%) and a number needed to read of 8.3 (95% confidence interval: 6.7-11.3%). In direct comparisons of the new filter with the currently available one in PubMed using the 1994 and 1999 subsets, the new filter achieved better precision (12.0% versus 8.2% in 1994 and 5.0% versus 4.3% in 1999. The 95% confidence intervals for the differences range from 0.05% to 7.5% (p = 0.041) and -1.0% to 2.3% (p = 0.45), respectively). The new filter achieved slightly better sensitivities than the currently available one in both subsets, namely 98.1 and 96.1% (p = 0.32) versus 95.1 and 88.8% (p = 0.125). Conclusions: The quoted performance of the currently available filter for diagnostic studies in PubMed may be overstated. It appears that even single external validation may lead to over optimistic views of a filter's performance. Precision appears to be more unstable than sensitivity. In terms of sensitivity, our filter for diagnostic studies performed slightly better than the currently available one and it performed better with regards to precision in the 1994 subset. Additional research is required to determine whether these improvements are beneficial to searches in practic

Regulación epigenética del IFN-y en tuberculosis

M. tuberculosis (Mtb) es el principal asesino microbiológico en el mundo. Las modificaciones epigenéticas son claves en la plasticidad del sistema inmune y como mediadores entre el ambiente y los fenotipos celulares. El IFN-v, media la respuesta protectiva frente a Mtb, pero se desconocen los mecanismos epigenéticos que regularían su activación y mediarían la susceptibilidad a la tuberculosis.Área: Ciencias Biológicas, Ambiente y Salud

Electromagnetic properties of non-Dirac particles with rest spin 1/2

We resolve a number of questions related to an analytic description of electromagnetic form factors of non-Dirac particles with the rest spin 1/2. We find the general structure of a matrix antisymmetric tensor operator. We obtain two recurrence relations for matrix elements of finite transformations of the proper Lorentz group and explicit formulas for a certain set of such elements. Within the theory of fields with double symmetry, we discuss writing the components of wave vectors of particles in the form of infinite continued fractions. We show that for $Q^{2} \leq 0.5$ (GeV/c)$^{2}$, where $Q^{2}$ is the transferred momentum squared, electromagnetic form factors that decrease as $Q^{2}$ increases and are close to those experimentally observed in the proton can be obtained without explicitly introducing an internal particle structure.Comment: 18 pages, 2 figure

The Sum over Topologies in Three-Dimensional Euclidean Quantum Gravity

In Hawking's Euclidean path integral approach to quantum gravity, the partition function is computed by summing contributions from all possible topologies. The behavior such a sum can be estimated in three spacetime dimensions in the limit of small cosmological constant. The sum over topologies diverges for either sign of $\Lambda$, but for dramatically different reasons: for $\Lambda>0$, the divergent behavior comes from the contributions of very low volume, topologically complex manifolds, while for $\Lambda<0$ it is a consequence of the existence of infinite sequences of relatively high volume manifolds with converging geometries. Possible implications for four-dimensional quantum gravity are discussed.Comment: 12 pages (LaTeX), UCD-92-1

The wave nature of biomolecules and fluorofullerenes

We demonstrate quantum interference for tetraphenylporphyrin, the first biomolecule exhibiting wave nature, and for the fluorofullerene C60F48 using a near-field Talbot-Lau interferometer. For the porphyrins, which are distinguished by their low symmetry and their abundant occurence in organic systems, we find the theoretically expected maximal interference contrast and its expected dependence on the de Broglie wavelength. For C60F48 the observed fringe visibility is below the expected value, but the high contrast still provides good evidence for the quantum character of the observed fringe pattern. The fluorofullerenes therefore set the new mark in complexity and mass (1632 amu) for de Broglie wave experiments, exceeding the previous mass record by a factor of two.Comment: 5 pages, 4 figure

The Stern-Gerlach Experiment Revisited

The Stern-Gerlach-Experiment (SGE) of 1922 is a seminal benchmark experiment of quantum physics providing evidence for several fundamental properties of quantum systems. Based on today's knowledge we illustrate the different benchmark results of the SGE for the development of modern quantum physics and chemistry. The SGE provided the first direct experimental evidence for angular momentum quantization in the quantum world and thus also for the existence of directional quantization of all angular momenta in the process of measurement. It measured for the first time a ground state property of an atom, it produced for the first time a `spin-polarized' atomic beam, it almost revealed the electron spin. The SGE was the first fully successful molecular beam experiment with high momentum-resolution by beam measurements in vacuum. This technique provided a new kinematic microscope with which inner atomic or nuclear properties could be investigated. The original SGE is described together with early attempts by Einstein, Ehrenfest, Heisenberg, and others to understand directional quantization in the SGE. Heisenberg's and Einstein's proposals of an improved multi-stage SGE are presented. The first realization of these proposals by Stern, Phipps, Frisch and Segr\`e is described. The set-up suggested by Einstein can be considered an anticipation of a Rabi-apparatus. Recent theoretical work is mentioned in which the directional quantization process and possible interference effects of the two different spin states are investigated. In full agreement with the results of the new quantum theory directional quantization appears as a general and universal feature of quantum measurements. One experimental example for such directional quantization in scattering processes is shown. Last not least, the early history of the `almost' discovery of the electron spin in the SGE is revisited.Comment: 50pp, 17 fig

Internally Electrodynamic Particle Model: Its Experimental Basis and Its Predictions

The internally electrodynamic (IED) particle model was derived based on overall experimental observations, with the IED process itself being built directly on three experimental facts, a) electric charges present with all material particles, b) an accelerated charge generates electromagnetic waves according to Maxwell's equations and Planck energy equation and c) source motion produces Doppler effect. A set of well-known basic particle equations and properties become predictable based on first principles solutions for the IED process; several key solutions achieved are outlined, including the de Broglie phase wave, de Broglie relations, Schr\"odinger equation, mass, Einstein mass-energy relation, Newton's law of gravity, single particle self interference, and electromagnetic radiation and absorption; these equations and properties have long been broadly experimentally validated or demonstrated. A specific solution also predicts the Doebner-Goldin equation which emerges to represent a form of long-sought quantum wave equation including gravity. A critical review of the key experiments is given which suggests that the IED process underlies the basic particle equations and properties not just sufficiently but also necessarily.Comment: Presentation at the 27th Int Colloq on Group Theo Meth in Phys, 200

Trust and the Governance of Higher Education: The Introduction of Chancellor System in Hungarian Higher Education

Trust plays a vital role in the cooperation of social actors. While researching trust becomes important in public management, the impact of trust on higher education policy and management has drawn less attention. This chapter analyses the introduction of the chancellor system in Hungarian higher education from the perspective of trust. In this new governance model, chancellors, who are appointed by the government, became responsible for the administration and budgets of higher institutions (HEIs), while rectors kept their prerogatives only on academic issues. The success of an institution now depends on the cooperation of its two interdependent leaders. Trust plays an especially critical role in such leadership constellation. The study is based on empirical data collected through two surveys conducted in 2015 and 2016 among academic leaders of Hungarian higher education institutions and uses Hurley’s decision-to-trust-model (Hurley 2012) as an analytic framework