Surco en cabeza femoral como signo de inestabilidad de cadera en pacientes con Síndrome de Down.

La inestabilidad de cadera en pacientes afectos de síndrome de Down es una entidad poco frecuente, en la actualidad todavía existe controversia sobre las anomalías anatómicas asociadas. El objetivo de este trabajo es describir los cambios anatómicos en las caderas de pacientes con inestabilidad en el síndrome de Down (SD). Hemos revisado las tomografías computarizadas (TC) de los pacientes afectos de luxación de cadera con SD. A tres de los 7 pacientes intervenidos en nuestro centro, se les había realizado TC de caderas. En todas las TC mostraban la presen - cia de lesión lineal vertical (surco) localizada en región epifisaria, atravesando la fisis, de localización antero-interna. Creemos que la posición adoptada cuando duermen (flexión, aducto y rotación interna) puede producir hiperpresión de la cabeza femoral sobre la ceja acetabular posterior, produciendo un surco vertical. La presencia de esta lesión puede ser sugestiva de inestabilidad subclínica de cadera en ausencia de episodio de luxación.Hip instability in patients with Down syndrome is a rare entity, currently there is still controversy about the associated anatomical anomalies. The aim of the study is to describe the anatomical changes in the hips of patients with instability in Down syndrome (DS). We have reviewed the computed tomography (CT) of patients with hip dislocation with SD. Three of the 7 patients treated in our center are performed CT had hips. All CT showed the presence of vertical linear lesion (groove) located in epiphyseal region, crossing the physis, antero-internal location. We believe that the position taken when sleeping (flexion, adduction and internal rotation) can produce overpressure of the femoral head over the posterior acetabular rim, producing a vertical groove. The presence of this lesion can be suggestive of subclinical instability in the absence of hip dislocation

Probing Noncommutative Space-Time in the Laboratory Frame

The phenomenological investigation of noncommutative space-time in the laboratory frame are presented. We formulate the apparent time variation of noncommutativity parameter $\theta_{\mu\nu}$ in the laboratory frame due to the earth's rotation. Furthermore, in the noncommutative QED, we discuss how to probe the electric-like component $\overrightarrow{\theta_{E}}=(\theta_{01},\theta_{02},\theta_{03})$ by the process $e^-e^+\to\gamma\gamma$ at future $e^-e^+$ linear collider. We may determine the magnitude and the direction of $\overrightarrow{\theta_{E}}$ by detailed study of the apparent time variation of total cross section. In case of us observing no signal, the upper limit on the magnitude of $\overrightarrow{\theta_E^{}}$ can be determined independently of its direction.Comment: 12 pages, 7 figures, typos are corrected, one graph have been added in figure

Quantum gauge models without classical Higgs mechanism

We examine the status of massive gauge theories, such as those usually obtained by spontaneous symmetry breakdown, from the viewpoint of causal (Epstein-Glaser) renormalization. The BRS formulation of gauge invariance in this framework, starting from canonical quantization of massive (as well as massless) vector bosons as fundamental entities, and proceeding perturbatively, allows one to rederive the reductive group symmetry of interactions, the need for scalar fields in gauge theory, and the covariant derivative. Thus the presence of higgs particles is explained without recourse to a Higgs(-Englert-Brout-Guralnik-Hagen-Kibble) mechanism. Along the way, we dispel doubts about the compatibility of causal gauge invariance with grand unified theories.Comment: 20 pages in two-column EPJC format, shortened version accepted for publication. For more details, consult version

Quantum gravity phenomenology at the dawn of the multi-messenger era—A review

The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review, prepared within the COST Action CA18108 “Quantum gravity phenomenology in the multi-messenger approach”, is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers.publishedVersio

Quantum gravity phenomenology at the dawn of the multi-messenger era—A review

The exploration of the universe has recently entered a new era thanks to the multi-messenger paradigm, characterized by a continuous increase in the quantity and quality of experimental data that is obtained by the detection of the various cosmic messengers (photons, neutrinos, cosmic rays and gravitational waves) from numerous origins. They give us information about their sources in the universe and the properties of the intergalactic medium. Moreover, multi-messenger astronomy opens up the possibility to search for phenomenological signatures of quantum gravity. On the one hand, the most energetic events allow us to test our physical theories at energy regimes which are not directly accessible in accelerators; on the other hand, tiny effects in the propagation of very high energy particles could be amplified by cosmological distances. After decades of merely theoretical investigations, the possibility of obtaining phenomenological indications of Planck-scale effects is a revolutionary step in the quest for a quantum theory of gravity, but it requires cooperation between different communities of physicists (both theoretical and experimental). This review, prepared within the COST Action CA18108 “Quantum gravity phenomenology in the multi-messenger approach”, is aimed at promoting this cooperation by giving a state-of-the art account of the interdisciplinary expertise that is needed in the effective search of quantum gravity footprints in the production, propagation and detection of cosmic messengers