El surco de desarrollo radicular como causa de fracaso endodóncico: a propósito de un caso

El surco de desarrollo radicular es una anomalía dentaria de origen embriológico presente en el 8,5% de la población que se localiza principalmente en la cara palatina de los incisivos laterales superiores. Este surco se origina en la fosa central y atravesando el cíngulo se dirige hacia el ápice, siendo su longitud variable. A través de él, los microorganismos penetran en el ligamento periodontal, causando una destrucción ósea localizada. Clínicamente los dientes afectados por esta anomalía pueden ser asintomáticos o bien presentar patología periodontal, pulpitis o necrosis pulpar por afectación secundaria de la pulpa. Presentamos el caso de una paciente que acudió a nuestro Servicio para realizarse la cirugía periapical del 1.2

Cosmological Rescaling through Warped Space

We discuss a scenario where at least part of the homogeneity on a brane world can be directly related to the hierarchy problem through warped space. We study the dynamics of an anti-D3-brane moving toward the infrared cut-off of a warped background. After a region described by the DBI action, the self-energy of the anti-D3-brane will dominate over the background. Then the world-volume scale of the anti-D3-brane is no longer comoving with the background geometry. After it settles down in the infrared end, the world-volume inhomogeneity will appear, to a Poincare observer, to be stretched by an exponentially large ratio. This ratio is close to that of the hierarchy problem between the gravitational and electroweak scales.Comment: 12 pages, 2 figures; v2, PRD version, comments and references adde

On the Use of A Priori Information for Sparse Signal Approximations

Recent results have underlined the importance of incoherence in redundant dictionaries for a good behavior of decomposition algorithms like Matching and Basis Pursuits. However, appropriate dictionaries for a given application may not necessarily be able to meet the incoherence condition. In such case, decomposition algorithms may completely fail in the retrieval of the sparsest approximation. This paper studies the effect of introducing a priori knowledge when recovering sparse approximations over redundant dictionaries. Theoretical results show how the use of reliable a priori information (which in this work appears under the form of weights) can improve the performances of standard approaches such as greedy algorithms and relaxation methods. Our results reduce to the classical case when no a priori information is available. Examples validate and illustrate our theoretical statements

On the Use of A Priori Information for Sparse Signal Representations

This report studies the effect of introducing a priori knowledge to recover sparse representations when overcomplete dictionaries are used. We focus mainly on Greedy algorithms and Basis Pursuit as for our algorithmic basement, while a priori is incorporated by suitably weighting the elements of the dictionary. A unique sufficient condition is provided under which Orthogonal Matching Pursuit, Matching Pursuit and Basis Pursuit are able to recover the optimally sparse representation of a signal when a priori information is available. Theoretical results show how the use of "reliable" a priori information can improve the performances of these algorithms. In particular, we prove that sufficient conditions to guarantee the retrieval of the sparsest solution can be established for dictionaries unable to satisfy the results of Gribonval and Vandergheynst and Tropp. As one might expect, our results reduce to the classical case when no a priori information is available. Some examples illustrate our theoretical findings

On supersymmetric Minkowski vacua in IIB orientifolds

Supersymmetric Minkowski vacua in IIB orientifold compactifications based on orbifolds with background fluxes and non-perturbative superpotentials are investigated. Especially, microscopic requirements and difficulties to obtain such vacua are discussed. We show that orbifold models with one and two complex structure moduli and supersymmetric 2-form flux can be successfully stabilized to such vacua. By taking additional gaugino condensation on fixed space-time filling D3-branes into account also models without complex structure can be consistently stabilized to Minkowski vacua.Comment: 17 pages, 2 figures; More detailed proof for absence of complex flat directions in susy AdS vacua given; Footnotes and reference adde

Quiste globulomaxilar: presentación de seis casos

Se presentan seis casos de quiste globulomaxilar, cinco de los cuales se diagnosticaron de modo casual y el sexto por dolor y tumefacción causados por sobreinfección. Se practicó extirpación en todos los casos y el resultado fue satisfactorio. No aparecieron recidivas después de un año de la intervención quirúrgica. Se revisa la anatomía patológica, la clinica, el diagnóstico diferencial y el tratamiento del quiste globulomaxilar

Development and validation of a questionnaire to evaluate lifestyle-related behaviors in elementary school children

Background: The SI! Program promotes cardiovascular health through a multilevel school-based intervention on four lifestyle-related components: diet, physical activity, understanding the body and heart, and management of emotions. We report here the development and validation of the KAH (knowledge, attitudes and habits)-questionnaire adapted for elementary school children (6-7 years old) as a tool for the forthcoming evaluation of the SI! Program, where the KAH scoring will be the primary outcome. The efficacy of such an intervention will be based on the improvements in children's KAH towards a healthy lifestyle. Methods: The questionnaire validation process started with a pool of items proposed by the pedagogical team who developed the SI! Program for elementary school. The questionnaire was finalized by decreasing the number of items from 155 to 48 using expert panels and statistical tests on the responses from 384 children (ages 6-7). A team of specialized psychologists administered the questionnaire at schools providing standard directions for the final administration. The internal consistency was assessed using Cronbach's a coefficients. Reliability was measured through the split-half method, and problematic items were detected applying the item response theory. Analysis of variance and Tukey's test of additivity were used for multiple comparisons. Results: The final KAH-questionnaire for elementary school children should be administered to children individually by trained staff. The 48 items-questionnaire is divided evenly between the 4 components of the intervention, with an overall Cronbach's a = 0.791 (a = 0.526 for diet, a = 0.537 for physical activity, a = 0.523 for human body and heart, and a = 0.537 for management of emotions). Conclusions: The KAH-questionnaire is a reliable instrument to assess the efficacy of the SI! Program on instilling healthy lifestyle-related behaviors in elementary school children.This work is supported by the SHE Foundation (Foundation for Science, Health and Education) and the Daniel and Nina Carasso Foundation.S

Development and validation of a questionnaire to evaluate lifestyle-related behaviors in elementary school children

Background The SI! Program promotes cardiovascular health through a multilevel school-based intervention on four lifestyle-related components: diet, physical activity, understanding the body and heart, and management of emotions. We report here the development and validation of the KAH (knowledge, attitudes and habits)-questionnaire adapted for elementary school children (6-7 years old) as a tool for the forthcoming evaluation of the SI! Program, where the KAH scoring will be the primary outcome. The efficacy of such an intervention will be based on the improvements in children's KAH towards a healthy lifestyle. Methods The questionnaire validation process started with a pool of items proposed by the pedagogical team who developed the SI! Program for elementary school. The questionnaire was finalized by decreasing the number of items from 155 to 48 using expert panels and statistical tests on the responses from 384 children (ages 6-7). A team of specialized psychologists administered the questionnaire at schools providing standard directions for the final administration. The internal consistency was assessed using Cronbach's α coefficients. Reliability was measured through the split-half method, and problematic items were detected applying the item response theory. Analysis of variance and Tukey's test of additivity were used for multiple comparisons. Results The final KAH-questionnaire for elementary school children should be administered to children individually by trained staff. The 48 items-questionnaire is divided evenly between the 4 components of the intervention, with an overall Cronbach's α = 0.791 (α = 0.526 for diet, α = 0.537 for physical activity, α = 0.523 for human body and heart, and α = 0.537 for management of emotions). Conclusions The KAH-questionnaire is a reliable instrument to assess the efficacy of the SI! Program on instilling healthy lifestyle-related behaviors in elementary school children

Characterization of Mechanically Alloyed Nanocrystalline Fe(Al): Crystallite Size and Dislocation Density

A nanostructured disordered Fe(Al) solid solution was obtained from elemental powders of Fe and Al using a high-energy ball mill. The transformations occurring in the material during milling were studied with the use of X-ray diffraction. In addition lattice microstrain, average crystallite size, dislocation density, and the lattice parameter were determined. Scanning electron microscopy (SEM) was employed to examine the morphology of the samples as a function of milling times. Thermal behaviour of the milled powders was examined by differential scanning calorimetry (DSC). The results, as well as dissimilarity between calorimetric curves of the powders after 2 and 20 h of milling, indicated the formation of a nanostructured Fe(Al) solid solution

An Approach to the Cosmological Constant Problem(s)

We propose an approach to explaining why naive large quantum fluctuations are not the right estimate for the cosmological constant. We argue that the universe is in a superposition of many vacua, in such a way that the resulting fluctuations are suppressed by level repulsion to a very small value. The approach combines several aspects of string theory and the early history of the universe, and is only valid if several assumptions hold true. The approach may also explain why the effective cosmological constant reamins small as the universe evolves though several phase transitions. It provides a non-anthropic mechansim leading to a small, non-zero cosmological constant.Comment: Talk given at Rencontres de Moriond, 2004 by G.L. Kan