Leptogenesis, Z' bosons, and the reheating temperature of the Universe

We study the impact for leptogenesis of new U(1) gauge bosons coupled to the heavy Majorana neutrinos. They can significantly enhance the efficiency of thermal scenarios in the weak washout regime as long as the Z' masses are not much larger than the reheating temperature ($M_{Z'}<10 T_{rh}$), with the highest efficiencies obtained for Z' bosons considerably heavier than the heavy neutrinos ($M_{Z'} > 100 M_1$). We show how the allowed region of the parameter space is modified in the presence of a Z' and we also obtain the minimum reheating temperature that is required for these models to be successful.Comment: 14 pages, 6 figures; One figure added, discussion on the reheating temperature extende

Complete CKM quark mixing via dimensional deconstruction

It is shown that the deconstruction of $[SU(2)\times U(1)]^N$ into $[SU(2)\times U(1)]$ is capable of providing all necessary ingredients to completely impliment the complex CKM mixing of quark flavors. The hierarchical structure of quark masses originates from the difference in the deconstructed chiral zero-mode distribution in theory space, while the CP-violating phase comes from the genuinely complex vacuum expectation value of link fields. The mixing is constructed in a specific model to satisfy experimental bounds on quarks' masses and CP violation.Comment: RevTex4, 25 pages, typos in section IIC corrected, published versio

Fuentes primarias, objetos y artefactos en la interpretación de la historia. Diseño y evaluación de un taller de numismática en Educación Secundaria

Este trabajo presenta el diseño y evaluación de una experiencia de innovación para la enseñanza de la historia, basada en el uso de un taller de numismática en la unidad didáctica sobre el Antiguo Régimen. Se incide principalmente en los aspectos metodológicos de la experiencia, y en el uso de diferentes fuentes para desarrollar la interpretación y argumentación histórica en el alumnado. La experiencia se realizó en tres cursos consecutivos. La valoración de la experiencia se realizó a través de un cuestionario cerrado con una escala de estimación tipo Likert (1-5), donde el alumnado debía valorar tanto la actividad, como el proceso de enseñanza y el aprendizaje adquirido. Los resultados fueron positivos a lo largo de los tres años.This paper presents the design and evaluation of an innovative experience to teach history based on the use of a numismatic workshop in the teaching unit on the Old Regime. We deepen mainly on methodological aspects of the experience, and the use of different sources to develop the interpretation and historical argument in students. The experience was carried out in three consecutive courses. The assessment of the experience was carried out through a closed questionnaire with a Likert scale (1-5), where students should assess both the activity and the process of teaching and learning acquired. The results were positive over the three years

Estilos arquitectónicos y estadios constructivos en el grupo May, Oxkintok, Yucatán.

Sin resume

Retrograde filling material in periapical surgery: a systematic review

Background: Periapical surgery focuses on the treatment of teeth with persistent periapical lesions when orthograde root canal treatment fails. Although MTA® is the gold standard material for retrograde filling, Biodentine® - a tricalcium silicate-based cement - has been proposed in order to resolve several of its limitations. A systematic review has been carried out to compare the physicochemical properties of Biodentine® versus MTA® as root-end filling material in periapical surgery. Material and methods: An electronic search was conducted by two independent examiners during March 2020 in the Cochrane, PubMed-MEDLINE and Scopus databases. In addition, a manual search was made in specialized journals. Comparative human or in vitro studies that evaluated bond strength, the presence of marginal gap and sealing ability were included. No restriction on publication date was applied. Animal studies, clinical cases, cases series and expert opinions were excluded. Results: After analyzing 147 initially selected studies, 13 publications were included. Regarding bond strength, the studies seemed to evidence better performance of Biodentine® in both acidic and blood contaminated environments. In relation to the presence of marginal gap and sealing ability, the studies yielded contradictory results. According to some authors, the sealing ability of Biodentine® is greater than that of MTA® during the first 24 hours, though both materials prove equal after one week. Other authors recorded no significant differences. Conclusions: Considering the limitations and heterogeneity of the studies included, there is not sufficient evidence to confirm the clinical superiority of Biodentine® as a root-end filling material in periapical surgery

The dual equivalence of equations and coequations for automata

Because of the isomorphism (X x A) -> X = X -> (A -> X), the transition structure t: X -> (A -> X) of a deterministic automaton with state set X and with inputs from an alphabet A can be viewed both as an algebra and as a coalgebra. Here we will use this algebra-coalgebra duality of automata as a common perspective for the study of equations and coequations. Equations are sets of pairs of words (v,w) tha

Las complicaciones de la resonancia magnética nuclear en la exploración de la articulación temporomandibular

La presencia de ciertos materiales ferromagnéticos , implantes y aparatos metálicos en el organismo se considera una contraindicación relativa para la práctica de una resonancia magnética nuclear, debido a los riesgos asociados al desplazamiento o dislocación de los mismos al ser atraídos en el campo magnético a que se les somete. Se presenta un resumen sobre los materiales con un riesgo potencial de complicaciones durante la práctica de la resonancia magnética nuclear de la articulación temporomandibular y se destaca la importancia de la detección previa de los mismos mediante la anamnesis y la exploración fisica de los pacientes que precisan dicha técnica. En algunos casos, se precisará asesoramiento especializado

Primary intraosseous squamous cell carcinoma arising in dentigerous cyst : report of 2 cases and review of the literature

Dentigerous cysts are one of the most common odontogenic cysts of the oral cavity. Odontogenic cysts can give rise to a variety of neoplasms. Carcinoma arising in a dentigerous cyst is extremely rare, with a review of literature showing near 30 cases. The present report describes 2 cases of primary intraosseous squamous cell carcinoma originated from a dentigerous cyst. The first one refers to a 57-year old female with a persistent lesion in the left retromolarregion and diagnosed with squamous cell carcinoma originated fromthe incomplete excision of the lower third molar follicle during its surgical extraction. The second case describes the case of an 18-year old male with an impacted upper canine with previous history of infection and swelling of the oral cavity. The histopathological study revealed the malignization of the follicle surrounding the dental crown. These two cases confirmed the importance of the histopathological study of all the tissue samples obtained from surgical procedures. Although the development of a malignant lesion from a dentigerous cyst is rare and its clinical-radiological features are apparently innocuous, this entity should be considered as a differential diagnosis