Quantum Geometry Phenomenology: Angle and Semiclassical States

The phenomenology for the deep spatial geometry of loop quantum gravity is discussed. In the context of a simple model of an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used to develop a model of angular corrections to local, continuum flat-space 3-geometries. The physical effects involve neither breaking of local Lorentz invariance nor Planck scale suppression, but rather reply on only the combinatorics of SU(2) recouping theory. Bhabha scattering is discussed as an example of how the effects might be observationally accessible.Comment: 5 pages, slightly extended version of the contribution to the Loops'11 conference proceeding

Relations and evolution in "Cheilanthes" ("Sinopteridaceae, Pteridophyta") in Macaronesia and Mediterranean area, deduced from genome analysis of their hybrids

Nine species of "Cheilantoid ferns" are known to grow in Macaronesia and the Mediterranean basin. Two of them (lacking a pseudo-indusium and having the basic chromosome number X = 29), both aggregate species which we prefer to retain in Notholaena, are not included in this study. The other seven species (with distinct pseudo-indusium and the basic chromosome number X = 30), which we accept as members of the genus Cheilanthes Sw. sensu stricto, were subjected to detailed genome analysis of their natural and experimentally produced hybrids and shown to represent an aggregate of four very distinct ancestral diploids and three allotetraploids. The latter must have once been formed by chromosome doubling in the three diploid hybrids of C. maderensis Lowe with the other three diploid species. Theoretically three more allotetraploids would be possible but their formation has obviously been prevented by the geographical separation of the three respective diploids. The most widely distributed of the tetraploids, i.e. C. pteridioides (Reich.) C.Chr. has also been resynthesized from its ancestors (still sympatric) under experimental conditions. The intermediate morphology of the allotetraploids (as compared with their diploid ancestors) is obviously the reason why their status and existence has so long escaped recognition in Europe. These seven species form a natural group and, in our opinion, should not be divided into sections.Se conocen nueve especies de "helechos Cheilantoides" que viven en Macaronesia y la cuenca Mediterranea. Dos de ellos, (sin pseudoindusio y con número cromosómico básico X = 29) que preferimos incluir en Notholaena, no se estudian en este trabajo. Las otras siete especies (con pseudoindusio y número cromosómico básico X = 30) que reconocemos como miembros del género Cheilanthes Sw. sensu stricto, fueron objeto de un análisis detallado del genoma de sus híbridos, tanto de los naturales, como de los producidos experimentalmente mostrando un agregado de cuatro ancestrales diploides muy distintos y tres alotetraploides. Estos últimos deben haberse formado por duplicación de los cromosomas en los tres híbridos diploides resultantes del cruzamiento de C. maderensis con las otras tres especies diploides. Teóricamente son posibles otros tres alotetraploides, pero su formación se ha impedido por la separación geográfica de los 3 diploides respectivos. Los tetraploides más ampliamente distribuidos, como por ejemplo Cheilanthes pteridioides (Reich.) C. Chr., han sido igualmente resintetizados a partir de sus ancestros bajo condiciones experimentales. La morfología intermedia de los alotetraploides (comparada con sus ancestros diploides) es obviamente la razón por la que su existencia y status han pasado inadvertidos en Europa. Estas siete especies forman un grupo natural que, en nuestra opinión, no debe ser dividido en secciones

Shape in an Atom of Space: Exploring quantum geometry phenomenology

A phenomenology for the deep spatial geometry of loop quantum gravity is introduced. In the context of a simple model, an atom of space, it is shown how purely combinatorial structures can affect observations. The angle operator is used to develop a model of angular corrections to local, continuum flat-space 3-geometries. The physical effects involve neither breaking of local Lorentz invariance nor Planck scale suppression, but rather reply on only the combinatorics of SU(2) recoupling. Bhabha scattering is discussed as an example of how the effects might be observationally accessible.Comment: 14 pages, 7 figures; v2 references adde

Eigenvalues of the volume operator in loop quantum gravity

We present a simple method to calculate certain sums of the eigenvalues of the volume operator in loop quantum gravity. We derive the asymptotic distribution of the eigenvalues in the classical limit of very large spins which turns out to be of a very simple form. The results can be useful for example in the statistical approach to quantum gravity.Comment: 12 pages, version accepted in Class. Quantum Gra

Prospecting for an HIV Vaccine

Human immunodeficiency virus (HIV) sets several challenges for the development of a preventative HIV vaccine. Predictable, protective natural immunity against HIV does not occur and so unlike most other diseases for which vaccines exist, there are few guideposts from natural infection. Nonetheless, six vaccine efficacy trials have occurred. One in particular, the Thai trial called RV144, showed partial protective efficacy and potential ways ahead to a better vaccine approach. This coupled with other lessons from studies of acute infections as well as an increasingly complex knowledge of HIV-related vaccine immunology bring hope that a vaccine solution might be reached for this pervasive and deadly pandemic

Background independent quantizations: the scalar field II

We are concerned with the issue of quantization of a scalar field in a diffeomorphism invariant manner. We apply the method used in Loop Quantum Gravity. It relies on the specific choice of scalar field variables referred to as the polymer variables. The quantization, in our formulation, amounts to introducing the `quantum' polymer *-star algebra and looking for positive linear functionals, called states. Assumed in our paper homeomorphism invariance allows to derive the complete class of the states. They are determined by the homeomorphism invariant states defined on the CW-complex *-algebra. The corresponding GNS representations of the polymer *-algebra and their self-adjoint extensions are derived, the equivalence classes are found and invariant subspaces characterized. In the preceding letter (the part I) we outlined those results. Here, we present the technical details.Comment: 51 pages, LaTeX, no figures, revised versio

Native Speaker Perceptions of Accented Speech: The English Pronunciation of Macedonian EFL Learners

The paper reports on the results of a study that aimed to describe the vocalic and consonantal features of the English pronunciation of Macedonian EFL learners as perceived by native speakers of English and to find out whether native speakers who speak different standard variants of English perceive the same segments as non-native. A specially designed computer web application was employed to gather two types of data: a) quantitative (frequency of segment variables and global foreign accent ratings on a 5-point scale), and b) qualitative (open-ended questions). The result analysis points out to three most frequent markers of foreign accent in the English speech of Macedonian EFL learners: final obstruent devoicing, vowel shortening and substitution of English dental fricatives with Macedonian dental plosives. It also reflects additional phonetic aspects poorly explained in the available reference literature such as allophonic distributional differences between the two languages and intonational mismatch