Supersymmetric Kaluza-Klein reductions of M-waves and MKK-monopoles

We investigate the Kaluza-Klein reductions to ten dimensions of the purely gravitational half-BPS M-theory backgrounds: the M-wave and the Kaluza-Klein monopole. We determine the moduli space of smooth (supersymmetric) Kaluza-Klein reductions by classifying the freely-acting spacelike Killing vectors which preserve some Killing spinor. As a consequence we find a wealth of new supersymmetric IIA configurations involving composite and/or bound-state configurations of waves, D0 and D6-branes, Kaluza-Klein monopoles in type IIA and flux/nullbranes, and some other new configurations. Some new features raised by the geometry of the Taub-NUT space are discussed, namely the existence of reductions with no continuous moduli. We also propose an interpretation of the flux 5-brane in terms of the local description (close to the branes) of a bound state of D6-branes and ten-dimensional Kaluza-Klein monopoles.Comment: 36 pages (v2: Reference added, "draft" mode disabled; v3: two singular reductions discarded, appendix on spin structures added, references updated

The big five: Discovering linguistic characteristics that typify distinct personality traits across Yahoo! answers members

Indexación: Scopus.This work was partially supported by the project FONDECYT “Bridging the Gap between Askers and Answers in Community Question Answering Services” (11130094) funded by the Chilean Government.In psychology, it is widely believed that there are five big factors that determine the different personality traits: Extraversion, Agreeableness, Conscientiousness and Neuroticism as well as Openness. In the last years, researchers have started to examine how these factors are manifested across several social networks like Facebook and Twitter. However, to the best of our knowledge, other kinds of social networks such as social/informational question-answering communities (e.g., Yahoo! Answers) have been left unexplored. Therefore, this work explores several predictive models to automatically recognize these factors across Yahoo! Answers members. As a means of devising powerful generalizations, these models were combined with assorted linguistic features. Since we do not have access to ask community members to volunteer for taking the personality test, we built a study corpus by conducting a discourse analysis based on deconstructing the test into 112 adjectives. Our results reveal that it is plausible to lessen the dependency upon answered tests and that effective models across distinct factors are sharply different. Also, sentiment analysis and dependency parsing proven to be fundamental to deal with extraversion, agreeableness and conscientiousness. Furthermore, medium and low levels of neuroticism were found to be related to initial stages of depression and anxiety disorders. © 2018 Lithuanian Institute of Philosophy and Sociology. All rights reserved.https://www.cys.cic.ipn.mx/ojs/index.php/CyS/article/view/275

The geometry of null rotation identifications

The geometry of flat spacetime modded out by a null rotation (boost+rotation) is analysed. When embedding this quotient spacetime in String/M-theory, it still preserves one half of the original supersymmetries. Its connection with the BTZ black hole, supersymmetric dilatonic waves and one possible resolution of its singularity in terms of nullbranes are also discussed.Comment: 1+18 pages, 5 figures. v2 references adde

The uses of Connes and Kreimer's algebraic formulation of renormalization theory

We show how, modulo the distinction between the antipode and the "twisted" or "renormalized" antipode, Connes and Kreimer's algebraic paradigm trivializes the proofs of equivalence of the (corrected) Dyson-Salam, Bogoliubov-Parasiuk-Hepp and Zimmermann procedures for renormalizing Feynman amplitudes. We discuss the outlook for a parallel simplification of computations in quantum field theory, stemming from the same algebraic approach.Comment: 15 pages, Latex. Minor changes, typos fixed, 2 references adde

The holonomy of the supercovariant connection and Killing spinors

We show that the holonomy of the supercovariant connection for M-theory backgrounds with $N$ Killing spinors reduces to a subgroup of SL(32-N,\bR)\st (\oplus^N \bR^{32-N}). We use this to give the necessary and sufficient conditions for a background to admit $N$ Killing spinors. We show that there is no topological obstruction for the existence of up to 22 Killing spinors in eleven-dimensional spacetime. We investigate the symmetry superalgebras of supersymmetric backgrounds and find that their structure constants are determined by an antisymmetric matrix. The Lie subalgebra of bosonic generators is related to a real form of a symplectic group. We show that there is a one-one correspondence between certain bases of the Cartan subalgebra of sl(32, \bR) and supersymmetric planar probe M-brane configurations. A supersymmetric probe configuration can involve up to 31 linearly independent planar branes and preserves one supersymmetry. The space of supersymmetric planar probe M-brane configurations is preserved by an SO(32,\bR) subgroup of SL(32, \bR).Comment: 27 pages, a key reference was added. v3: minor change

Solución positiva minimal de - div A(x, grad u) + b(x, u) = Λ g(x, u) Vía iteraciones monótonas

Se considera la ecuación elíptica no lineal F(u) = - div A(x, grad u) + b(x, u) =  Λ g(x, u) con condiciones de frontera de tipo Dirichlet. El campo de vectores A y las funciones b y g son monótonas con respecto a la segunda variable. Si A es menor que el primer autovalor del problema linealizado, las iteraciones de Newton dadas por: vo = O y F(vn + 1) = Λ [g(x, vn) + gu (x, vn) (vn + 1 - vn)] convergen uniformemente a la solución positiva mínimal. Si g es convexa (Cóncava) entonces la convergencia es desde abajo (arriba). La Concavidad implica unicidad

Supersymmetry and homogeneity of M-theory backgrounds

We describe the construction of a Lie superalgebra associated to an arbitrary supersymmetric M-theory background, and discuss some examples. We prove that for backgrounds with more than 24 supercharges, the bosonic subalgebra acts locally transitively. In particular, we prove that backgrounds with more than 24 supersymmetries are necessarily (locally) homogeneous.Comment: 19 pages (Erroneous Section 6.3 removed from the paper.

High-Speed Running Density in Collegiate Women’s Soccer

High-speed running density (HSRd) is a relatively new concept developed to discern between HSR volume and intensity. HSRd is the ratio of high-speed efforts to distance covered. PURPOSE: This study aimed to assess the differences in HSRd between training and games, and among positions in collegiate women’s soccer. A second aim was to correlate HSRd with other training metrics. METHODS: Data was collected during the in-season through global positioning units (GPS) worn by athletes (n = 20) for 42 training sessions and 15 games. A speed of 5 m×s-1 was used as the threshold for defining HSR. RESULTS: HSRd did not differ between training sessions and games (H(1) = 0.875, p = .349) or by position during training sessions (H(3) = 7.503, p = .057). However, HSRd differed by position during games (H(3) = 116.560, p \u3c .001, d = .165-484). Midfielders had higher HSRd than goalies and defenders. HSRd had low correlations (p \u3c .001) with HSR efforts (r = .128), top speed (r = .061), and HSRd intensity (r = .043, p = .003). A low inverse correlation (p \u3c .001) was found between HSRd and sprint distance (r = -.135). CONCLUSION: There is a difference in HSRd between positions during games, but not training sessions. Midfielders had higher HSRd than goalies and defenders during games. The increase in HSRd for midfielders may be a result of games being less predictable than training sessions, or the expectations of competitive play. The coaching staff and athletes may have tendencies which force midfielders to display higher HSRd during games. Observing HSRd over the course of multiple seasons with various teams, coaching staffs, and athletes will increase the reliability of the data produced. This information would help coaching staffs plan load management strategies for their athletes, potentially decreasing risk of injury