702 research outputs found

    A Chern-Simons Pandemic

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    In this paper we study the consistency of generalized global symmetries in theories of quantum gravity, in particular string theory. Such global symmetries arise in theories with (p+1)(p+1)-form gauge fields, and for spacetime dimension dp+3d\leq p+3 there are obstructions to their breaking even by quantum effects of charged objects. In 4d theories with a 2-form gauge field (or with an axion scalar), these fields endow Schwarzschild black holes with quantum hair, a global charge leading to usual trouble with remnants. We describe precise mechanisms, and examples from string compactifications and holographic pairs, in which these problems are evaded by either gauging or breaking the global symmetry, via (suitable versions of) Stuckelberg or Kaloper-Sorbo couplings. We argue that even in the absence of such couplings, the generic solution in string theory is the breaking of the global symmetries by cubic Chern-Simons terms involving different antisymmetric tensor fields. We conjecture that any theory with (standard or higher-degree antisymmetric tensor) gauge fields is in the Swampland unless its effective action includes such Chern-Simons terms. This conjecture implies that many familiar theories, like QED (even including the charged particles required by the Weak Gravity Conjecture) or N=8\mathcal{N}=8 supergravity in four dimensions, are inconsistent in quantum gravity unless they are completed by these Chern-Simons terms.Comment: 60 pages, 2 figure

    Relaxion Monodromy and the Weak Gravity Conjecture

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    The recently proposed relaxion models require extremely large trans-Planckian axion excursions as well as a potential explicitly violating the axion shift symmetry. The latter property is however inconsistent with the axion periodicity, which corresponds to a gauged discrete shift symmetry. A way to make things consistent is to use monodromy, i.e. both the axion and the potential parameters transform under the discrete shift symmetry. The structure is better described in terms of a 3-form field CμνρC_{\mu \nu \rho} coupling to the SM Higgs through its field strength F4F_4. The 4-form also couples linearly to the relaxion, in the Kaloper-Sorbo fashion. The extremely small relaxion-Higgs coupling arises in a see-saw fashion as gF4/fg\simeq F_4/f, with ff being the axion decay constant. We discuss constraints on this type of constructions from membrane nucleation and the Weak Gravity Conjecture. The latter requires the existence of membranes, whose too fast nucleation could in principle drive the theory out of control, unless the cut-off scale is lowered. This allows to constrain relaxion models on purely theoretical grounds. We also discuss possible avenues to embed this structure into string theory.Comment: 26 pages + appendices, 3 figures; v3: Corrected bounds on relaxion parameter spac

    Colecta y conservación de fósiles

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    http://archive.org/details/identificationof1094516179NAN

    Radiotherapy for non-malignant diseases

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    A design for rapid transit networks considering rolling stock's reliability and redistribution of services during disruptions

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    This paper presents a model for designing a public transit network system combining the traditional approach of transport demand coverage in bimodal scenarios of operation with the recovery of possible disruptions due to limited reliability of the rolling stock. The model balances construction and operational costs with the benefits to the users for the optimization of their travel times. Two transportation modes have been considered, public and private transport and the proportion of the users choosing one mode or the other is assumed to obey to a bimodal logit choice model. While construction costs are a first stage decision, user travel costs and recovery action costs are scenario dependent. Two types of scenarios are taken into account: a) the scenarios of normal operation and b) disruption scenarios which are associated to a link's breakdown of the network. The disruptions in the links are assumed to follow a probability disruption model accordingly to the number of services that operate on them. The model can be used to analyze the influence of the rate of failures of the units on the reliability of the designed RTN. The proposed model can be considered as a two recourse stochastic programming model with a bi-level structure where the probabilities of failure are an implicit function of the number of services and the routing of the transit lines of the transport system. A heuristic solution method is examined for small to medium networks demonstrating the computational viability of the approach

    “El coaching y la motivación laboral en el área comercial de la empresa Globokas S.A, Surco, año 2017”

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    Se realizó la investigación titulada “El Coaching y la Motivación laboral en el área comercial de la empresa Globokas S.A, Surco, Año 2017”, cuyo objetivo fue explicar si existe influencia entre la Coaching y Motivación Laboral. Para dicho estudio se utilizó la técnica de la encuesta, para su aplicación se elaboró un cuestionario de 20 preguntas dicho instrumento fue validado mediante el Juicio de Expertos y la Fiabilidad del mismo se calculó a través del coeficiente Alfa de Cronbach de valor mayor a 0.9. Para la recolección de datos se consideró una población de 135 trabajadores en las cuales se calculó una muestra de 100 trabajadores con un margen de error de 5% y un nivel de confianza de 95%. Los datos obtenidos fueron procesados mediante el SPSS V. 23. Finalmente, se obtuvo como resultado que el coaching y Motivación Laboral tienen un coeficiente de significancia de valor 0.00 y una correlación positiva fuerte mayor a 0.90, por lo que se aceptó la hipótesis de investigación

    Gestión y comportamientos éticos en redes sociales de los estudiantes de odontología de una universidad pública peruana durante el 2022

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    Describe la gestión y el comportamiento ético en redes sociales de los estudiantes de Odontología de la UNMSM durante el año 2022. La metodología empleada es el estudio básico de nivel descriptivo, no experimental, observacional y transversal que evaluó 190 estudiantes, utilizando un cuestionario elaborado por Andrade et al, dividido en dos partes, una contestada por los estudiantes y otra por el investigador. Resultados: El 98,9% de estudiantes usa redes sociales, de las cuales las más utilizadas fueron WhatsApp (98,9%), Facebook (88,8%) e Instagram (85%), se determinó que el principal uso que le dan a las redes es el social (77,79%), se halló que la frecuencia con mayor preponderancia para subir contenido a las redes sociales es de cada tres o seis meses (46,5%) y que la publicación de contenido de profesional es bajo (3,4%). Se encontró que el 10,1% nunca solicita permiso para subir una foto o video donde están otras personas, que el 13% no protege la identidad de los pacientes y que el 75,6% no adule la autorización del paciente al subir contenido. Concluyendo que la mayoría de estudiantes utiliza redes sociales, publican contenido cada 3 o 6 meses, del cual predominantemente no es contenido profesional. También se concluyó que la actividad más frecuente en redes sociales es el informarse sobre novedades en el mundo. Además, se encontraron faltas éticas en estudiantes que nunca piden permiso para subir contenido de otras personas y que no protegen la identidad de sus pacientes

    The 5Rs dilemma of radiotherapy for non-malignant diseases: 5Rs to darken or 5Rs to shine

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    Many benign diseases, so called because they are not a direct cause of death, nevertheless cause significant damage to the health of patients due to the associated pain, reduced functionality, increased disability and the negative impact they have on quality of life, which, together with the limited efficacy of many of the available treatments, make their management a challenge for every specialist. Radiotherapy, which has demonstrated its efficacy not only against cancer but also in many non-tumorous diseases, appears as a therapeutic option that deserves to be taken into account. However, there is still much resistance to considering the use of radiotherapy as a valid and acceptable alternative. The 5Rs to darken summarize the doubts and contradictions many specialists face to accept radiotherapy in non-neoplastic diseases. However, other 5Rs (to shine) can be argued to claim for the safety, reliability, and usefulness of radiation treatment for benign disease and as radiotherapy specialists we have to help the evidence shine and the darkness disappear
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