Self-dual formulations of d=3 gravity theories in the path-integral framework

We study the connection, at the quantum level, between d=2+1 dimensional self-dual models with actions of growing (from first to fourth) order, governing the dynamics of helicity +2 (or -2) massive excitations. We obtain identities between generating functionals of the different models using the path-integral framework, this allowing to establish dual maps among relevant vacuum expectation values. We check consistency of these v.e.v.'s with the gauge invariance gained in each mapping.Comment: 26 pages. LaTeX. Minor changes. Published in Int. J Modern Phys. A; http://www.worldscinet.com/ijmp

Evolución del conocimiento físico

In this paper we wish to present the evolution of the structure of the physic knowledge from the level of 1st year BUP to science graduates. The reliability of the responses also analysed

Adults with sedentary lifestyle, overweight, obesity and the risk of developing obstructive sleep apnea hypoapnea syndrome in a sample of the Ecuadorian population

Overweight, obesity, and a sedentary lifestyle have been associated with poor sleep quality, which includes obstructive sleep apnea-hypoapnea syndrome. The objective of this research was to relate sedentary lifestyle, overweight, and obesity as risk factors for developing obstructive sleep apnea-hypoapnea syndrome in a sample of Ecuadorian adults. For this research, adults over 18 years of age belonging to 17 provinces of Ecuador were considered as the study population, the non-probability sampling technique was used for convenience, and different questionnaires were used for data collection: Berlin questionnaire was used to evaluate the risk of obstructive sleep apnea-hypoapnea syndrome, Epworth sleepiness questionnaire for the study of sleep quality, as well as the IPAQ international physical activity questionnaire. Among the most important results, 61.4% women, 95.2% mestizos, 47.8% people were those who performed high physical activities, 82.4% resided in the urban areas. Participants with normal weight predominated, 57.7%. It was found that 10.3% of the surveyed population presents a high risk of suffering from obstructive sleep apnea-hypoapnea syndrome. When relating it to the physical activity variable, it was observed that sedentary people have 17.3% of suffering from the syndrome of obstructive sleep apnea-hypoapnea, when relating to overweight and obesity we found 10.85% and 63.6%, respectively. These differences were statistically significant p < 0.05. In conclusion, the risk of obstructive sleep apnea-hypoapnea syndrome was related to sedentary, overweight, and obese people. Keywords: obstructive sleep apnea-hypopnea syndrome sedentary lifestyle, physical activity, overweight, obesity. Resumen En los últimos años se ha asociado al sobrepeso, obesidad y sedentarismo como causas de una mala calidad del sueño que han provocado enfermedades como el síndrome de apneahipoapnea obstructiva del sueño. El objetivo de la investigación fue relacionar el sedentarismo, sobrepeso y obesidad como factores de riesgo para desarrollar el síndrome de apneahipoapnea obstructiva del sueño en una muestra de personas adultas ecuatorianas. Para la investigación se tomó como población de estudio a personas adultas mayores de 18 años pertenecientes a 17 provincias del Ecuador, se utilizó la técnica de muestreo no probabilístico por conveniencia, para la recolección de datos se utilizó diferentes cuestionarios: cuestionario de Berlín que evalúa el riesgo de padecer síndrome de apnea-hipoapnea obstructiva del sueño, cuestionario de somnolencia de Epworth para el estudio de la calidad del sueño y el cuestionario internacional de actividad física IPAQ. Entre los resultados más importantes se resalta mujeres 61,4%, mestizos 95,2%, personas que realizan actividades físicas altas 47,8%, residen en la zona urbana 82,4%. Predominaron los participantes con normopeso 57,7%. Se encontró que el 10,3% de la población encuestada presenta riesgo alto de padecer síndrome de apnea-hipoapnea obstructiva del sueño, al relacionar con la variable de actividad física se pudo observar que las personas sedentarias tienen un 17,3% de padecer síndrome de apneahipoapnea obstructiva del sueño, al relacionar con el sobrepeso y obesidad encontramos el 10,85% y 63,6% respectivamente, estas diferencias fueron estadísticamente significativas p<0,05. En conclusión, el riesgo de padecer el síndrome de apnea-hipoapnea obstructiva del sueño se relacionó con las personas con sedentarismo, sobrepeso y obesidad. Palabras Clave: Síndrome de Apnea-Hipoapnea Obstructiva del Sueño, SAHOS, Actividad Física, Sobrepeso, Obesidad

SU(2) Kinetic Mixing Terms and Spontaneous Symmetry Breaking

The non-abelian generalization of the Holdom model --{\it i.e.} a theory with two gauge fields coupled to the kinetic mixing term $g {tr}(F_{\mu \nu} (A) F_{\mu \nu} (B))$-- is considered. Contrarily to the abelian case, the group structure $G\times G$ is explicitly broken to $G$. For SU(2) this fact implies that the residual gauge symmetry as well as the Lorentz symmetry is spontaneusly broken. We show that this mechanism provides of masses for the involved particles. Also, the model presents instanton solutions with a redefined coupling constant.Comment: 9pp. typos and clarifications are adde

A joint time-dependent density-functional theory for excited states of electronic systems in solution

We present a novel joint time-dependent density-functional theory for the description of solute-solvent systems in time-dependent external potentials. Starting with the exact quantum-mechanical action functional for both electrons and nuclei, we systematically eliminate solvent degrees of freedom and thus arrive at coarse-grained action functionals which retain the highly accurate \emph{ab initio} description for the solute and are, in principle, exact. This procedure allows us to examine approximations underlying popular embedding theories for excited states. Finally, we introduce a novel approximate action functional for the solute-water system and compute the solvato-chromic shift of the lowest singlet excited state of formaldehyde in aqueous solution, which is in good agreement with experimental findings.Comment: 11 page

Ecuaciones diferenciales del c?lculo de variaciones

46 p. Recurso Electr?nic

Biexciton oscillator strength

Our goal is to provide a physical understanding of the elementary coupling between photon and biexciton and to derive the physical characteristics of the biexciton oscillator strength, following the procedure we used for trion. Instead of the more standard two-photon absorption, this work concentrates on molecular biexciton created by photon absorption in an exciton gas. We first determine the appropriate set of coordinates in real and momentum spaces to describe one biexciton as two interacting excitons. We then turn to second quantization and introduce the "Fourier transform in the exciton sense" of the biexciton wave function which is the relevant quantity for oscillator strength. We find that, like for trion, the oscillator strength for the formation of one biexciton out of one photon plus a \emph{single} exciton is extremely small: it is one biexciton volume divided by one sample volume smaller than the exciton oscillator strength. However, due to their quantum nature, trion and biexciton have absorption lines which behave quite differently. Electrons and trions are fermionic particles impossible to pile up all at the same energy. This would make the weak trion line spread with electron density, the peak structure only coming from singular many-body effects. By contrast, the bosonic nature of exciton and biexciton makes the biexciton peak mainly rise with exciton density, this rise being simply linear if we forget many-body effects between the photocreated exciton and the excitons present in the sample

Ferromagnetic transition of a two-component Fermi gas of Hard Spheres

We use microscopic many-body theory to analyze the problem of itinerant ferromagnetism in a repulsive atomic Fermi gas of Hard Spheres. Using simple arguments, we show that the available theoretical predictions for the onset of the ferromagnetic transition predict a transition point at a density ($k_F a \sim 1$) that is too large to be compatible with the universal low-density expansion of the energy. We present new variational calculations for the hard-sphere Fermi gas, in the framework of Fermi hypperneted chain theory, that shift the transition to higher densities ($k_F a \sim 1.8$). Backflow correlations, which are mainly active in the unpolarized system, are essential for this shift

Analytic and geometric properties of photoinduced effects in noncentrosymmetric crystals: photovoltaic current and optical rectification

An original dispersion relation between the stationary coherent nonlinear optical responses by current and polarisation is obtained. The dispersion relation provides a new complimentary tool that can be employed to study light-induced charge transport models and facilitate experimental data analysis. It is shown that the origin of the coherent current and the dc-polarisation induced in a noncentrosymmetric crystal under illumination is related to the theory of the Berry phase and can be represented in terms of the renormalised geometric potentials. This renormalisation originates from the extra phase difference acquired by a carrier in the light field on the quantum transition between the electronic bands. The gauge invariance of the corresponding expressions for the current and the polarisation is demonstrated.Comment: 7 page